# DyssolTEC — full site content

> DyssolTEC builds simulation software for solids and particulate processes — Dyssol Pro (macroscale flowsheet simulation) and MUSEN (microscale GPU-accelerated DEM) — and works as a particle process-engineering partner across pharma, chemicals, food, and minerals.

This file is the full-content companion to https://www.dyssoltec.com/llms.txt. All pages exist in German under /de/.

## Dyssol Pro — dynamic flowsheet simulation software

URL: https://www.dyssoltec.com/the-software/

Dyssol Pro is a dynamic flowsheet simulator for solids processes: it resolves particle size distribution (PSD) and stream properties across connected unit operations over time, and runs calibration, sensitivity, optimization, and scale-up studies. It supports startup, shutdown, batch, semi-batch, and continuous operation. It is not a CFD, mechanical-strength, or equipment-sizing tool. Dyssol Pro comes with enterprise support, custom unit models, and validated workflows from DyssolTEC; the free Dyssol Free edition is available to download.

Key capabilities: dynamic flowsheet simulation; graphical flowsheet editor; automated process optimization; sensitivity analysis; multidimensional interdependent solids properties (size, composition, moisture); population-balance methods with transformation matrices; custom Model Maker for company-specific unit models; unit library covering agglomeration, granulation, crushing, classification, spray and fluidized-bed drying, and more (see "Unit operations" below).

## Dyssol Free — free edition

URL: https://www.dyssoltec.com/dyssol-free/

Dyssol Free is a permanently free, feature-capped edition of Dyssol for evaluating and learning flowsheet simulation, with no time limit and no credit card required. It covers the core process units and single-flowsheet projects; Dyssol Pro adds the full unit library, scripting and automation, large-scale and multi-flowsheet projects, and direct engineering support.

## Dyssol Academic — academic licensing program

URL: https://www.dyssoltec.com/the-software/#dyssol-academic

Dyssol Academic brings the full Dyssol Pro feature set to universities and research institutes for teaching and non-commercial research, with campus and institutional licensing scoped from a single lab to a whole faculty.

## MUSEN — GPU-accelerated DEM particle simulation

URL: https://www.dyssoltec.com/musen/

MUSEN is an open-source discrete element method (DEM) framework for microscale particle simulation: GPU-accelerated, BSD-licensed, developed and maintained by DyssolTEC. Features: GPU-accelerated DEM solver; bonded-particle method (BPM) for breakage and structural DEM; multi-sphere and irregular particle shapes; custom contact models via C++ API; STL-based boundary geometry; cross-platform GUI (Windows, Linux).

## Services

URL: https://www.dyssoltec.com/services/

Process engineering, modeling, and simulation services for solids processes: custom model development (Model Maker), scale-up and debottlenecking, full-plant simulation, training for engineers and researchers, and embedded engineering support.

## Scientific background

Key method publications (full list with ~50 papers: https://www.dyssoltec.com/about-us/):
- Skorych, Dosta, Hartge & Heinrich (2017): Novel system for dynamic flowsheet simulation of solids processes. Powder Technology. https://doi.org/10.1016/j.powtec.2017.01.061
- Skorych et al. (2019): Application of transformation matrices to the solution of population balance equations. Processes. https://doi.org/10.3390/pr7080535
- Skorych et al. (2019): Investigation of an FFT-based solver applied to dynamic flowsheet simulation of agglomeration processes. Advanced Powder Technology. https://doi.org/10.1016/j.apt.2018.12.007
- Dosta & Skorych (2020): MUSEN: an open-source framework for GPU-accelerated DEM simulations. SoftwareX. https://doi.org/10.1016/j.softx.2020.100618
- Dosta et al. (2024): Comparing open-source DEM frameworks for simulations of common bulk processes. Computer Physics Communications. https://doi.org/10.1016/j.cpc.2023.109066
- Mehra et al. (2025): Implementation of multi-level coarse-graining method on GPU using MUSEN. Powder Technology. https://doi.org/10.1016/j.powtec.2025.121510

## Contact

https://www.dyssoltec.com/contact-us/ — contact form and company details. Jobs: https://www.dyssoltec.com/jobs/. Team and publications: https://www.dyssoltec.com/about-us/.

# Unit operations in Dyssol Pro

Each section below is the content of one unit-operation page: the simulation model, the equipment it represents, typical engineering studies, and a technical FAQ.

## Agglomerator

URL: https://www.dyssoltec.com/granulation/agglomerator/ (German: https://www.dyssoltec.com/de/granulation/agglomerator/)

Agglomerator simulation in Dyssol Pro: a dynamic population-balance model of particle collision and coalescence, resolving the full product particle size distribution.

A dynamic population-balance model for size enlargement by particle collision and coalescence — resolving the full particle size distribution inside a connected flowsheet.

### How it works

Agglomeration is a size-enlargement process: two particles collide and, if they stick, merge into a single larger particle of their combined volume. Whether a collision leads to lasting growth depends on the particles meeting, on a binding mechanism — a liquid binder bridge, van der Waals forces, or partial melting — and on the impact being gentle enough not to rebound or break the bond.

How fast the population grows is governed by how often particles collide and how likely each collision is to succeed, which in turn depends on particle size, concentration, and the operating conditions in the vessel. Larger, more numerous, or wetter particles collide and bind more readily, so the whole distribution shifts toward coarser sizes over time.

Total solid mass is conserved — agglomeration only redistributes mass across size classes, turning fines into coarser granules rather than creating or destroying material.

### The model

Dyssol Pro solves a dynamic population balance over the particle population by number: particles are born into a size class when smaller ones agglomerate into it and die from a class when they grow into a larger one, with the inlet and outlet streams completing the balance at every time point of the flowsheet.

### Equipment this model can represent

- **Fluidized bed agglomerators**: Bed agglomeration where suspended particles collide and bind into larger structures.
- **High-shear granulators**: Intensive mixing where impeller-driven collisions promote rapid agglomerate growth.
- **Batch granulators**: Drum, pan, and mixer granulators operated batch-wise for controlled size enlargement.
- **Continuous mixer granulators**: Continuous units where coalescence governs the product size distribution.

### Typical engineering studies

- **Homogeneity studies**: Assess how uniformly agglomerates develop across the population under given operating conditions.
- **Moisture distribution**: Study moisture in connected flowsheets when binder or liquid streams feed the growth zone.
- **Particle size distribution**: Track the full PSD evolution from feed fines to the agglomerated product.
- **Agglomeration efficiency**: Quantify growth and the conversion of fines into product across operating conditions.
- **Process-parameter sensitivity**: Map how growth rate and residence time move the product size.
- **Model-based Design of Experiments**: Plan and screen experiments in simulation before running them on the plant.
- **Scale-up and optimization**: Carry validated parameters from lab to production and optimize against product targets.

### Example: Validated population-balance agglomeration

A demonstration flowsheet (Agglomerator.dflw) ships with Dyssol Pro, and the population-balance method behind dynamic agglomeration simulation was published and validated against reference solutions.

### FAQ

**Q: How can I improve agglomerate strength without increasing binder usage?**

A: Strength comes from the number and strength of solid bridges and the contact area between primary particles, so denser packing, longer consolidation, and a binder of the right viscosity often help more than simply adding binder. In Dyssol Pro you run operating-window studies on residence time, growth, and binder input to reach the target size at lower binder use before committing to lab trials.

**Q: Why are my agglomerates breaking apart after drying?**

A: Post-drying breakage usually means the binder bridges shrink or embrittle as moisture leaves, or thermal stress cracks them — gentler drying and a binder that stays ductile help. In Dyssol Pro you connect the agglomerator with the downstream dryer and handling units in one flowsheet to see how moisture and thermal load evolve, which localizes whether the problem starts in growth, drying, or transport.

**Q: How do I choose the right binder for powder agglomeration?**

A: The binder is matched to the powder on wettability, bridge strength, viscosity, and product compatibility. Dyssol Pro propagates a binder’s captured effect through the growth and nucleation parameters across the process and predicts the downstream PSD.

**Q: What causes oversized lumps in an agglomeration process?**

A: Oversize comes from local over-wetting, excessive residence, or uncontrolled coalescence in the growth zone. With a population-balance growth model Dyssol Pro lets you study how growth rate, liquid input, and residence time drive the coarse tail of the PSD and screen for operating points that suppress oversize.

**Q: How can I control particle size distribution in an agglomerator?**

A: PSD is governed by the balance of nucleation, growth, and breakage, set through binder rate, mixing intensity, and residence time. PSD is a first-class quantity in Dyssol Pro: the agglomerator tracks the full distribution, so you can run sensitivity and optimization studies on the parameters that shape it across the connected process.

**Q: What is the difference between wet agglomeration and dry agglomeration?**

A: Wet agglomeration uses a liquid binder that forms bridges and then solidifies; dry agglomeration relies on pressure and van der Waals or mechanical interlocking with no added liquid. In Dyssol Pro you represent the relevant mechanism through the model parameters and compare the two process variants in one flowsheet.

**Q: How do impeller speed and residence time affect agglomerate size?**

A: Higher impeller speed raises collision frequency but also breakage, so size peaks at an optimum, while longer residence grows particles until breakage balances growth. These map onto growth parameters and holdup in Dyssol Pro, so you vary them in sensitivity studies to see the effect on size and throughput before plant trials.

**Q: How can I reduce dust formation during agglomeration?**

A: Dust is unagglomerated fines, reduced by more effective wetting and nucleation and by recycling fines back into the growth zone. In Dyssol Pro you connect the agglomerator with cyclone and gas-filter units and study how much fines and dust leave with the gas stream under different operating points.

**Q: What process parameters influence agglomerate porosity?**

A: Porosity is set by consolidation — binder content, compaction forces, and residence time — with denser packing giving lower porosity. Dyssol Pro tracks the residence time and growth that drive consolidation, so you can study how operating points move toward denser, lower-porosity granules.

**Q: How do I scale up an agglomeration process from lab to production?**

A: Reliable scale-up preserves the growth kinetics and the wetting and mixing regime, transferring material parameters rather than geometry alone. Dyssol Pro is built for this: fit model parameters to lab data, then run the validated model at production scale inside the full flowsheet to check feasibility before commissioning.

**Q: How can I prevent uncontrolled growth in an agglomerator?**

A: Runaway growth comes from over-wetting or too little breakage and recycle; capping the binder rate and closing the circuit with classification stabilizes it. Dynamic simulation of growth and recycle in Dyssol Pro identifies the stable operating windows and control settings that avoid it.

**Q: Why does my agglomeration process produce too many fines?**

A: Excess fines mean nucleation is outpacing growth, or agglomerates are breaking — usually under-wetting or too much mechanical stress. In Dyssol Pro you study the fines fraction of the PSD against growth and breakage parameters and against recycle load in the connected flowsheet.

**Q: How does liquid spray droplet size affect agglomerate formation?**

A: Droplet size sets the nucleation regime: drops large relative to the particles nucleate big granules quickly, while fine drops spread binder for steadier growth. Droplet effects enter Dyssol Pro through nucleation parameters, so you can study how changing them shifts the resulting PSD.

**Q: How can I optimize binder concentration for agglomeration?**

A: There is an optimum liquid-to-solid ratio that drives the target growth without over-wetting — too little starves growth, too much makes lumps. Once the binder effect is parameterized in Dyssol Pro, use the integrated optimization tool to search binder concentration against a target product property.

**Q: What causes agglomerates to be too soft or too friable?**

A: Weak granules come from thin or brittle binder bridges, insufficient consolidation, or excessive porosity. In Dyssol Pro you can couple a custom strength or breakage correlation through Model Maker and use the simulation to study which process drivers move it.

**Q: How do I model wetting and nucleation in agglomeration?**

A: Wetting and nucleation describe how binder droplets contact and immobilize primary particles to form the first agglomerates. This is core to the unit: population-balance agglomeration in Dyssol Pro represents nucleation and growth, and Model Maker lets you implement specific wetting and nucleation kinetics.

**Q: What is the best way to measure agglomerate quality?**

A: Quality is measured as size distribution, strength, porosity, and dissolution behavior, using sieving, texture testing, and imaging. Dyssol Pro complements measurement by predicting size and PSD, so you know what to expect and can reconcile model and measurement.

**Q: How does powder wettability influence agglomeration behavior?**

A: Poorly wetting powders resist nucleation and need more energy or a surfactant, while readily wetting powders nucleate and grow easily. Wettability is a material input reflected through nucleation parameters in Dyssol Pro, whose influence on growth and PSD you then study in the flowsheet.

**Q: How can I reduce recycle load in an agglomeration circuit?**

A: Recycle load falls when more feed reports to product in a single pass — better on-size yield through nucleation and growth control and the right screen cut. Dyssol Pro simulates recycle loops, so you can study how operating points and screen cut sizes change the recycle load around the agglomerator.

**Q: What are typical control strategies for continuous agglomeration?**

A: Common strategies regulate the binder rate to a moisture or size target and manage the recycle of fines and crushed oversize to hold the PSD steady. Dynamic simulation of startup, shutdown, and disturbances in Dyssol Pro lets you test these strategies and operating windows before implementing them on the plant.

---

## Spray Drying

URL: https://www.dyssoltec.com/drying/spray-dryer/ (German: https://www.dyssoltec.com/de/drying/spray-dryer/)

Spray drying simulation in Dyssol Pro: predict product moisture, gas and droplet temperature profiles, and yield in co- and counter-current dryers.

A unit that atomizes a liquid feed and dries the droplets into powder in hot gas — co-current and counter-current — resolving temperature profiles inside a connected flowsheet.

### How it works

Spray drying turns a pumpable feed (solution, suspension, or slurry) into powder in one step. The feed is atomized into a fine spray, enormously increasing surface area, and the droplets meet a hot drying gas. Each droplet first dries at a roughly constant rate: liquid evaporates from the surface, the droplet shrinks, and evaporative cooling keeps it cool. When the surface solids reach a critical concentration, a solid crust forms and shrinkage stops; drying enters a falling-rate stage where moisture must diffuse out through the crust, so the rate tapers toward the equilibrium moisture.

The gas–droplet contacting pattern matters. In co-current flow, spray and gas move together, so the hottest gas meets the wettest, coolest droplets — gentle on heat-sensitive products. In counter-current flow they move oppositely, giving higher thermal efficiency and denser powder but exposing nearly-dry particles to the hottest gas. The whole process is fast — seconds from atomization to dry powder.

### The model

Dyssol Pro resolves the dryer along its height into a series of compartments, and in each one the heat and mass exchanged between the droplets and the drying gas set how the droplets evaporate and cool — a steady-state description justified by the seconds-long residence time, at every operating point of the flowsheet.

### Equipment this model can represent

- **Rotary-atomizer spray dryers**: A spinning wheel creates droplets; robust, broad droplet sizes.
- **Pressure-nozzle spray dryers**: High-pressure nozzles for coarser, denser particles.
- **Two-fluid / multi-fluid nozzle dryers**: Gas-assisted atomization for fine droplets and small powders.
- **Co- and counter-current chambers**: Chosen for heat sensitivity versus thermal efficiency and bulk density.

### Typical engineering studies

- **Moisture & size prediction**: Predict product moisture and the droplet-to-particle size relation for given inlet conditions.
- **Co- vs. counter-current**: Compare configurations for a heat-sensitive product on temperature exposure.
- **Geometry & gas studies**: Study inlet gas temperature, flow, and chamber geometry against final moisture and yield.
- **Calibration & scale-up**: Calibrate the drying-curve parameters to lab data, then scale up to production geometry.
- **Flowsheet coupling**: Couple to a downstream cyclone/gas filter to capture fines and to upstream concentration units.

### FAQ

**Q: How do I avoid overdrying in a spray dryer?**

A: Overdrying comes from too high an outlet temperature or too long a gas contact; you target the outlet condition that lands the product at its moisture spec. Dyssol Pro predicts product moisture from the inlet gas conditions and chamber geometry, so you can tune outlet temperature and gas flow to stop at the target without overdrying.

**Q: Why is powder sticking to the walls of my spray dryer?**

A: Wall deposits form when semi-dry, sticky droplets hit the wall above their glass-transition/sticky point. Dyssol Pro computes droplet temperature, moisture, and trajectory along the chamber, so you can study operating points and chamber size that let droplets dry enough before reaching the wall.

**Q: How can I control particle size in spray drying?**

A: Final particle size is set mostly by droplet size (atomization) and feed solids. Dyssol Pro takes the droplet size distribution as input and computes the droplet-to-particle size relation through drying, so you can study how feed concentration and droplet size map to product size.

**Q: How do inlet and outlet air temperature affect product moisture?**

A: Inlet temperature sets the heat available; outlet temperature reflects how much drying capacity is left and correlates strongly with product moisture. Dyssol Pro resolves both through the gas–droplet energy balance, so you can map product moisture against inlet and outlet temperature directly.

**Q: How can I improve powder yield in a spray dryer?**

A: Yield is lost to wall deposits and to fines escaping with the exhaust. Dyssol Pro predicts the fines in the gas stream, so you can size a downstream cyclone/filter to recover them and study conditions that finish drying before the wall.

**Q: What causes hollow or collapsed spray-dried particles?**

A: Morphology depends on how fast a crust forms relative to internal evaporation and any inflation. Dyssol Pro computes the drying history — when the critical moisture is reached and the crust forms — which is the driver of morphology, so you can study the drying conditions that shape it.

**Q: How does atomizer type affect spray dryer performance?**

A: Atomizer choice (rotary, pressure, two-fluid) sets the droplet size distribution, which drives drying and product size. Dyssol Pro takes that distribution as input, so you can compare atomizers by entering their droplet sizes and seeing the effect on drying and product moisture.

**Q: How can I reduce energy consumption in spray drying?**

A: Energy use drops with a higher feed concentration (less water to evaporate) and good heat utilization. Dyssol Pro lets you study feed concentration, inlet temperature, and gas flow against the evaporation load and outlet conditions to find the leanest operating point that still dries the product.

**Q: How do I prevent thermal degradation during spray drying?**

A: Heat-sensitive products favor co-current contacting, where the hottest gas meets the coolest, wettest droplets. Dyssol Pro models both co- and counter-current configurations and tracks droplet temperature along the chamber, so you can choose the arrangement and conditions that keep product temperature below the degradation limit.

**Q: How can I scale up a spray drying process from lab to production?**

A: Scale-up transfers the drying-curve parameters and matches residence and gas conditions at larger geometry. Dyssol Pro is built for this: fit the parameters to lab data, then run the model at production chamber height, diameter, and gas flow to check moisture and temperature before commissioning.

**Q: How can I prevent nozzle clogging in spray drying?**

A: Clogging comes from feed rheology and nozzle design — high viscosity, high solids, or crystallization drying at the nozzle tip. It is controlled by conditioning the feed viscosity and solids loading, keeping the feed moving, and selecting a nozzle bore and geometry suited to the slurry.

**Q: Why is my spray-dried powder too sticky?**

A: Stickiness is driven by residual moisture and the product’s glass-transition temperature relative to the outlet conditions. Dyssol Pro predicts product moisture and the temperature history, so you can target an outlet condition that brings moisture below the sticky threshold.

**Q: How does feed concentration affect spray dryer capacity?**

A: Higher feed solids mean less water to evaporate per kg of product, raising capacity and cutting energy — limited by feed viscosity and atomization. Dyssol Pro lets you study how feed concentration changes the evaporation load and outlet conditions, quantifying the capacity gain.

**Q: How do I optimize outlet temperature for product quality?**

A: Outlet temperature is the master variable: too low leaves the powder wet, too high risks degradation and stickiness. Dyssol Pro resolves outlet temperature and the resulting product moisture, so you can find the window that meets both the moisture spec and the thermal limit.

**Q: What causes low bulk density in spray-dried powders?**

A: Low bulk density usually comes from hollow or puffed particles formed during rapid drying or with entrained gas. Dyssol Pro computes the drying rate and crust-formation point that influence it, so you can study conditions — such as gentler co-current drying — that tend toward denser particles.

**Q: How can I improve solubility of spray-dried particles?**

A: Solubility depends on morphology and surface composition, which are shaped by the drying conditions and the formulation. Dyssol Pro models the drying conditions — temperature history and moisture — that shape those outcomes, so you can steer the process side toward better solubility.

**Q: How do I reduce wall deposits in a spray dryer chamber?**

A: Deposits come from sticky, semi-dry droplets reaching the wall. Dyssol Pro computes droplet trajectory, temperature, and moisture along the chamber, so you can study chamber diameter, gas flow, and temperature that let droplets dry past the sticky stage before contacting the wall.

**Q: How does droplet size distribution affect drying behavior?**

A: Smaller droplets dry faster and finish sooner; a wide distribution dries unevenly. Dyssol Pro takes the droplet size distribution as input and resolves drying per size, so you see directly how the spread affects product moisture and the size of the final powder.

**Q: How can I model heat and mass transfer in a spray dryer?**

A: This is the core of the unit: compartment-wise convective heat and mass transfer between droplets and gas, with a two-stage drying curve. In Dyssol Pro you set geometry and the moisture parameters and it returns the temperature, humidity, and moisture profiles along the chamber.

**Q: How do I control residual moisture and particle morphology in spray drying?**

A: Residual moisture is directly predicted and controlled through outlet temperature, gas flow, and residence; morphology follows from the drying history. Dyssol Pro gives you the moisture control explicitly and the drying-rate and crust-formation history that governs morphology, so you can steer moisture to target and reason about the resulting shape.

---

## Crusher & Mill

URL: https://www.dyssoltec.com/size-reduction/crusher/ (German: https://www.dyssoltec.com/de/size-reduction/crusher/)

Crusher and mill simulation in Dyssol Pro: predict product particle size distribution, specific energy, and mill–classifier circuit behavior in dynamic flowsheets.

Reduce particle size and reshape the full particle size distribution inside a connected dynamic flowsheet — from coarse crushing to fine grinding.

### How it works

Comminution is the controlled application of mechanical stress until particles fracture. A particle stores elastic strain energy as it is loaded; once the local stress exceeds the material’s strength at a flaw, it breaks into fragments. The energy required scales with the new surface area created, which is why producing fine powder costs far more energy than coarse crushing.

How the stress is applied selects the breakage mechanism: compression cleaves particles into a few large fragments, impact shatters them into many with a broader spread, and attrition chips fines off the surface. Real machines combine these, and the dominant mechanism shapes the product — how much the size is reduced and how broad the distribution.

How far the size comes down in a single pass depends on the material and on the stressing: the strength and flaw density of the particles, the stress intensity the machine applies, and how many stress events each particle experiences before it leaves the crushing zone. Small particles carry fewer flaws and are harder to break, which is why every real comminution step produces a distribution of sizes rather than a single one.

### The model

Dyssol Pro describes comminution at the population level: the crusher takes the feed particle size distribution and shifts mass from coarse size classes to finer ones — mass-conserving, for every solid compound, at every time point of the dynamic flowsheet.

### Equipment this model can represent

- **Jaw crushers**: Coarse primary crushing of hard rock by compression between a fixed and a moving jaw.
- **Cone & gyratory crushers**: Secondary and tertiary compression crushing; product top size is set by the close-side setting.
- **Impact crushers & hammer mills**: Breakage by high-speed impact, giving strong size reduction with more fines.
- **Ball, rod & SAG mills**: Tumbling mills where grinding media — or, in SAG mills, the coarse ore itself — reduce size by impact and attrition, from primary grinding down to fine wet or dry grinding.
- **High-pressure grinding rolls (HPGR)**: Two counter-rotating rolls compress a particle bed at high pressure; inter-particle stressing breaks the material at low specific energy.
- **Jet mills**: Particle-on-particle impact in a high-velocity gas jet for very fine, contamination-free powder.

### Typical engineering studies

- **Product PSD prediction**: Predict the product size distribution for a given crusher setting and feed.
- **Energy & throughput**: Relate power input and Bond work index to the achievable product size through Bond’s law.
- **Mill–classifier circuits**: Couple the crusher with a screen or classifier and study recycle load and circuit performance.
- **Process-parameter sensitivity**: Map how the model parameters and feed PSD move the product size and the fines fraction.
- **Feed-variability studies**: See how changes in feed PSD propagate to the product and downstream units.
- **Model-based Design of Experiments**: Screen experiments in simulation before running them on the plant.
- **Scale-up & optimization**: Fit parameters to lab data, then run the validated unit at production throughput and optimize against targets.

### FAQ

**Q: How do I reduce particle size in a mill without generating too many fines?**

A: Run the mill in closed circuit with a screen or classifier, so particles leave the loop as soon as they reach product size — most fines come from over-grinding material that was already fine enough. Keeping the specific energy per pass moderate and accepting a higher recycle load also shifts breakage toward cleaner fracture. In Dyssol Pro you simulate exactly this recycle loop and tune cut size and recycle ratio against the fines fraction.

**Q: What causes overheating during milling?**

A: Only a few percent of the grinding energy actually creates new surface — the rest dissipates as heat, so thermal load rises directly with specific energy input and peaks at fine grinding targets with poor heat removal. Relaxing the fineness target, staged grinding, and better ventilation or cooling are the countermeasures. Dyssol Pro quantifies the specific energy behind that heat load for every operating point in the flowsheet.

**Q: How can I choose the right mill for brittle powder?**

A: Brittle materials fracture readily under impact, so hammer, pin, and jet mills are the natural candidates; the final choice follows from target fineness, abrasiveness, and heat sensitivity. In Dyssol Pro you parameterize each candidate and compare the predicted product distribution and specific energy at your throughput.

**Q: How do mill speed and grinding media affect particle size?**

A: Higher speed and larger or denser media raise the stress intensity per event and push the product finer — but past the optimum the extra energy mainly produces fines and heat, while media that are too small fail to break the coarse feed at all. Once the breakage model is calibrated, these effects map onto its parameters, so a Dyssol Pro sensitivity study shows the response of the product distribution before you change the machine.

**Q: How can I reduce energy consumption in grinding?**

A: Energy demand rises steeply toward fine sizes, so the biggest lever is not grinding finer than the specification requires; the second is a closed circuit that stops over-grinding. Bond’s law links power, grindability, and throughput to the achieved product size — in Dyssol Pro you optimize size target and circuit configuration against specific energy.

**Q: Why is my mill product particle size distribution too broad?**

A: In an open circuit every particle sees a different stressing history — some pass barely broken, others are ground repeatedly — which inevitably broadens the product. Narrowing it requires classification: remove particles at product size and return only true oversize. In Dyssol Pro you couple the crusher with a classifier and see directly how cut size and recycle sharpen the distribution.

**Q: How do I prevent material buildup inside a crusher?**

A: Buildup is almost always a moisture or stickiness problem: keep the feed moisture below the material’s caking threshold, condition or dry the feed, and avoid fines accumulating in dead zones. Dyssol Pro tracks moisture through the upstream flowsheet, so critical feed conditions can be identified and corrected before material reaches the mill.

**Q: What is the difference between impact milling and compression milling?**

A: Compression loads particles slowly between two surfaces and cleaves them into a few coarse fragments at low specific energy; impact loads them abruptly and shatters them into many finer fragments, with more fines and heat. In Dyssol Pro either route is represented by calibrating the crusher model to the machine’s measured product.

**Q: How can I model breakage kinetics in a mill?**

A: The standard description is a population balance with two material functions: a selection function for the breakage probability of each size class and a breakage function for the fragment size distribution. That is exactly how Dyssol Pro’s crusher model works — calibrate the functions to milling data, or implement custom kinetics in Model Maker.

**Q: How do I scale up milling from lab scale to industrial scale?**

A: Scale up via material functions, not geometry: grindability and the selection–breakage behavior are fitted at lab scale and remain valid at production rates, while machine-specific effects are corrected against pilot data. In Dyssol Pro you fit the model to lab measurements, then run the validated unit at full throughput inside the complete flowsheet.

**Q: How do I prevent product contamination during milling?**

A: Contamination comes from wear of media and liners, so the countermeasures are autogenous comminution — jet mills with no grinding media — ceramic or hardened linings, and moderate stress intensities. Dyssol Pro predicts PSD and stream composition through the circuit, so the process design is settled before committing to a contamination-critical machine.

**Q: Why is my mill throughput decreasing over time?**

A: The usual suspects are wear — liners and gap opening up, media charge degrading — or a drift toward harder, coarser, or moister feed. In Dyssol Pro you can separate the two: vary the effective machine setting and the feed properties independently and see which reproduces the observed product change.

**Q: How does feed particle size affect mill performance?**

A: Coarser feed needs more energy per ton for the same product size and can hit the machine’s capacity limit, while feed already near product size wastes grinding volume. In Dyssol Pro you vary the inlet PSD and see the effect on product size, specific energy, and recycle load directly.

**Q: How can I avoid excessive wear in a crusher?**

A: Wear scales with specific energy, feed abrasiveness, and circulating load, so it is limited by running at the coarsest acceptable product size, keeping tramp and oversize material out of the feed, and matching liner hardness to the material. Dyssol Pro computes the specific energy and recycle load of an operating point, so you can steer toward the settings that reduce its main drivers.

**Q: What causes agglomeration during fine grinding?**

A: Below a few micrometres, adhesive surface forces exceed the particle weight, so freshly created fines stick to each other and to walls — the practical limit of dry grinding. If re-agglomeration matters for your product, place an agglomeration unit downstream of the crusher in the same Dyssol Pro flowsheet and study the net result.

**Q: How do I choose between ball mill, hammer mill, and jet mill?**

A: Rule of thumb: hammer mills for coarse-to-medium brittle feed, ball mills for medium-to-fine grinding at large scale, jet mills for ultra-fine, heat-sensitive, or contamination-critical powders. Dyssol Pro turns the shortlist into numbers by comparing predicted product PSD and specific energy for each candidate at your throughput.

**Q: How can I control temperature-sensitive materials during milling?**

A: Limit the specific energy input, remove heat actively — chilled air, inert gas, or cryogenic milling — and avoid over-grinding, which is pure heat generation. Dyssol Pro computes the specific energy behind that heat, so you can minimize the source and size the cooling and gas-handling units in the same flowsheet.

**Q: How does classifier integration affect milling efficiency?**

A: A classifier in closed circuit removes product-size particles immediately, so grinding energy goes only into true oversize — throughput rises and over-grinding drops at the same power. In Dyssol Pro you simulate the mill–classifier recycle dynamically and optimize cut size and circulating load.

**Q: How do I calculate specific energy consumption in milling?**

A: Bond’s law gives it directly: specific energy equals ten times the material’s work index times the difference between one over the square root of the product’s 80%-passing size and one over the square root of the feed’s 80%-passing size, with energy in kilowatt-hours per tonne. Dyssol Pro applies this relation directly in the flowsheet, linking power, throughput, and achieved product size.

**Q: How can I simulate particle breakage and classification in a mill circuit?**

A: Represent the mill with a selection–breakage (population-balance) model and the classifier with a separation curve, connect them with a recycle stream, and solve to steady state. That is a standard Dyssol Pro flowsheet: crusher plus screen or classifier, solved dynamically for product PSD and circulating load.

---

## Screen

URL: https://www.dyssoltec.com/classification/screen/ (German: https://www.dyssoltec.com/de/classification/screen/)

Screen simulation in Dyssol Pro: predict the oversize/undersize split, both product PSDs, and screening-circuit behavior in dynamic solids-process flowsheets.

Split a feed at a defined cut size into oversize and undersize — resolving the full particle size distribution of both product streams — inside a connected dynamic flowsheet.

### How it works

Screening separates particles by whether they can pass an aperture. Material is presented to a screening surface; particles smaller than the opening have a chance to pass to the undersize (fine) stream, while larger ones are retained as oversize (coarse). The chance of passing is not a clean step at the mesh size — it depends on how often a particle meets an aperture, its orientation, and near-mesh particles that only just fit.

The result is a smooth grade efficiency (partition) curve: the fraction of each size class that reports to the coarse stream. Two numbers summarize it — the cut size (where half the material goes each way) and the sharpness (how steeply the curve rises around the cut). High sharpness means a clean separation; low sharpness leaves near-size material in the wrong fraction.

Before a particle can be tested at all, it must reach the deck: the bed stratifies under vibration, fines percolate downward through the coarse layer, and the transport velocity sets how long each particle stays on the screen. Real screens lose sharpness to blinding, overloading, and cohesive or moist material — near-size particles lodge in the apertures, and adhering fines ride along with the coarse fraction instead of passing.

### The model

Dyssol Pro splits the feed at the population level: for every particle size class it computes the fraction reporting to the coarse stream, with the fine stream taking the remainder — mass-conserving, at every time point of the dynamic flowsheet.

### Equipment this model can represent

- **Vibrating / shaker screens**: Inclined or horizontal decks vibrated to stratify and transport material across the mesh.
- **Tumbler / gyratory screens**: Gentle gyratory motion for fine, accurate classification.
- **Trommel (drum) screens**: A rotating cylindrical screen for robust scalping and washing duty.
- **Ultrasonic-assisted fine screens**: High-frequency excitation of the mesh to keep fine, cohesive powders from blinding.

### Typical engineering studies

- **Cut and split prediction**: Predict the oversize/undersize split and both product PSDs for a given cut size and sharpness.
- **Closed mill–screen circuit**: Return oversize to a crusher and study recycle load and product PSD across the loop.
- **Cut & sharpness sensitivity**: Map how cut size and sharpness move misplacement and yield.
- **Partition-curve fitting**: Fit the separation curve to a measured partition curve, then use it predictively.
- **Cut optimization**: Optimize the cut to balance product quality against recovery across the connected process.

### FAQ

**Q: How do I choose the right screen mesh size?**

A: The mesh opening starts at roughly the target cut size and is then corrected for near-size load, particle shape, and expected blinding — in practice the effective cut sits somewhat below the nominal opening. In Dyssol Pro you set the cut size in the screen unit, predict the split and both product PSDs, and iterate until the product spec is met before committing to a mesh.

**Q: Why is my vibrating screen blinding?**

A: Blinding comes from near-size particles wedging in the apertures or sticky, moist fines coating the mesh; the countermeasures are aperture shape, deck motion, ultrasonics, and drier feed. Its process signature is a blunted cut — in Dyssol Pro you represent that as a reduced effective sharpness and quantify what the degraded separation costs downstream.

**Q: How can I improve screening efficiency?**

A: Efficiency needs enough aperture encounters per particle — sufficient area, controlled bed depth, the right transport velocity — and a feed that is not overloading the deck. In Dyssol Pro you vary cut size and sharpness inside the connected circuit, so the improvement is judged with recycle effects included rather than on the screen alone.

**Q: What causes too much good product in the oversize fraction?**

A: Undersize retained in the coarse fraction means the effective cut sits too coarse or the separation is too blunt — typically overloading, too little screening length, or partially blinded apertures. In Dyssol Pro you move the cut or sharpen the separation curve and read directly how much good product returns to the right stream.

**Q: How does moisture content affect screening performance?**

A: Surface moisture makes fines adhere to coarse particles and to the mesh, so the cut blunts and undersize reports coarse; most materials have a critical moisture band where screening is at its worst. In Dyssol Pro you model the upstream drying in the flowsheet to find a safe moisture window and represent the residual effect as a reduced sharpness.

**Q: How do vibration frequency and amplitude affect separation?**

A: They set stratification and transport: enough acceleration to loosen the bed so fines reach the deck, but not so much that particles fly over apertures without being tested — most decks run at a few g. Their net result is a cut size and sharpness, which is exactly how the screen enters a Dyssol Pro flowsheet, calibrated to the measured performance.

**Q: How can I reduce screen wear when processing abrasive particles?**

A: Wear is fought with harder or resilient deck materials such as polyurethane or rubber, lower impact angles, and taking the abrasive coarse load out early. Dyssol Pro computes the split and the mass loads each deck actually sees, so wear parts are specified against the real duty.

**Q: What is the difference between scalping, classification, and dedusting screens?**

A: They differ only in where the cut sits relative to the product: scalping removes a small coarse tail, classification cuts inside the distribution, and dedusting takes fines off the bottom end. In Dyssol Pro all three are the same screen unit with a different cut size and sharpness.

**Q: How do I size a screen for a powder processing line?**

A: Deck area follows from the material-specific capacity per unit area, the fraction of near-size particles, and the efficiency you are willing to accept — the near-size load is what really drives area. Dyssol Pro supplies the duty that sizing depends on: the split and the mass loads at every operating point of the line, so the area calculation starts from the right numbers.

**Q: How can I model screen separation efficiency?**

A: Separation efficiency is described by the grade-efficiency (partition) curve — the fraction of each size class reporting to the coarse stream — summarized by cut size and sharpness. That curve is the core of Dyssol Pro’s screen unit: set it or fit it to data, and the unit returns the size-resolved split and both product PSDs inside the flowsheet.

**Q: How can I prevent screen clogging with sticky powders?**

A: Sticky powders need conditioning — drier feed, flow aids, heated or coated decks — plus aggressive anti-blinding measures such as ultrasonic excitation. In Dyssol Pro you study the upstream drying and handling that reduce cohesion, and check what cut remains realistically achievable once the feed is conditioned.

**Q: Why is screen throughput lower than expected?**

A: Falling throughput usually means the effective open area is shrinking — blinding, overloading, or moist feed — or the feed carries more near-size material than the design assumed. In Dyssol Pro you vary the feed PSD and the effective separation independently, which tells you whether the cause is the process or the machine.

**Q: How does particle shape affect screening accuracy?**

A: Elongated and flaky particles pass an aperture by their intermediate dimension, so they classify at a different size than a sieve analysis suggests and smear the cut. In the flowsheet this appears as a reduced sharpness, so in Dyssol Pro you calibrate the separation curve to measured data and the shape effect is carried automatically.

**Q: How can I reduce fines in the oversize stream?**

A: Fines report coarse when they never reach the deck — too deep a bed, too fast a transport, or moist, agglomerated feed — so the fix is stratification and residence time as much as the mesh. In Dyssol Pro you tune the separation curve and quantify the fines-in-oversize fraction against cut and sharpness directly.

**Q: How do I optimize screen inclination angle?**

A: Inclination trades capacity against accuracy: a steeper deck moves material faster, giving fewer aperture encounters and a coarser, blunter cut; a flatter deck cuts finer but carries a deeper bed. Its net effect lands in the cut size and sharpness, which you calibrate in Dyssol Pro from the screen’s measured performance at each setting.

**Q: What causes product loss through the undersize stream?**

A: Coarse product leaks to undersize when the effective cut is finer than intended or the separation is blunt — often worn or oversized apertures. In Dyssol Pro you shift the cut or sharpen the curve and read the recovered product straight off the partition curve.

**Q: How can I select between ultrasonic and mechanical screen cleaning?**

A: Ultrasonics excel on fine, dry, blinding-prone powders; ball trays and brushes are the robust choice for coarser, tougher duties. Dyssol Pro defines the separation the process must maintain — the cut and sharpness the product spec requires — so the cleaning system is chosen to protect exactly that performance.

**Q: How do I improve screening of cohesive powders?**

A: Cohesive powders screen better with drier feed, flow aids, ultrasonic decks, and a shallow bed so agglomerates break up and fines actually reach the apertures. In Dyssol Pro you model the upstream conditioning and test what effective cut and sharpness are achievable before promising a product spec.

**Q: How can I measure screening efficiency in production?**

A: Sample feed, oversize, and undersize, sieve each, and compute the recovery of every size class to the coarse stream — that gives the partition curve, the honest measure of screen performance. Dyssol Pro then fits its separation curve to that measurement, turning the audit into a validated unit you can use predictively.

**Q: How can I model screen performance using partition curves?**

A: The partition (Tromp) curve is the complete description of a screen: the fraction of each size class reporting coarse, characterized by cut size and sharpness. Dyssol Pro’s screen unit is built on exactly this curve — fit it to your measured data and the unit reproduces the screen inside the connected flowsheet.

---

## Air Classifier

URL: https://www.dyssoltec.com/classification/classifier/ (German: https://www.dyssoltec.com/de/classification/classifier/)

Air classifier simulation in Dyssol Pro: predict the size-resolved split into fine and coarse fractions, the cut size, and mill–classifier circuit behavior in dynamic flowsheets.

Split a feed by size into a fine and a coarse fraction at an adjustable cut — resolving the full particle size distribution of both streams — inside a connected dynamic flowsheet.

### How it works

In an air classifier a gas stream carries the feed through a separation zone. Each particle feels two competing actions: aerodynamic drag from the gas, which tends to carry it along, and gravity or centrifugal force, which tends to settle it out. The deciding quantity is the particle’s settling velocity — large, dense particles settle faster than the gas can carry them and report to the coarse fraction, while fine, light particles are swept off to the fine fraction.

The boundary between the two is the cut velocity: particles whose settling velocity equals it have a 50/50 chance of going either way, which defines the cut size. How sharply the split happens around that cut — the separation sharpness — sets how much material is misplaced into the wrong fraction. A perfect classifier would be a step function at the cut size; real ones smear it.

In a static (gravity) classifier the cut is fixed by the gas flow and the geometry; in a dynamic classifier a rotating wheel adds a centrifugal field, so the cut size can be tuned on the fly through rotor speed.

### The model

Dyssol Pro computes the split at the population level: for every particle size class it weighs the particle’s settling velocity against the gas cut velocity and assigns the matching fraction to the fine and coarse streams — mass-conserving, for every solid compound, at every time point of the dynamic flowsheet.

### Equipment this model can represent

- **Gravity / cross-flow sifters**: Static classifiers where a gas stream lifts fines against gravity; cut set by air velocity and geometry.
- **Zigzag (cascade) classifiers**: Multiple gravity stages in series for a sharper cut.
- **Impeller-wheel (dynamic) classifiers**: A rotating classifying wheel sets a centrifugal cut velocity, giving an adjustable, fine cut size.
- **Air-swept mill classifiers**: A dynamic classifier integrated on a mill to return oversize for regrinding.

### Typical engineering studies

- **Fine/coarse split prediction**: Predict the fine/coarse split and cut size for a given classifier setting and feed.
- **Closed mill–classifier circuit**: Couple with a crusher/mill and a recycle, and study recycle load and product fineness.
- **Operating-point sensitivity**: Map how rotor speed, gas flow, and sharpness move the cut size.
- **Cut optimization**: Optimize the operating point to hit a target fineness with minimum misplacement.
- **Partition-curve fitting**: Calibrate the model’s cut and sharpness to a measured partition curve, then scale up.

### FAQ

**Q: How does an air classifier separate fine and coarse particles?**

A: It plays drag against gravity or centrifugal force: particles whose settling velocity exceeds the gas cut velocity drop into the coarse fraction, while finer, lighter ones are carried out with the fines. Dyssol Pro reproduces exactly this — it computes each size class’s settling velocity, compares it to the cut velocity, and returns the size-resolved split for a gravity or impeller-wheel classifier.

**Q: How can I improve cut size accuracy in a classifier?**

A: Cut size is set by the gas velocity and, in dynamic units, the rotor speed, so accuracy comes from stable flow and a sharp cut. In Dyssol Pro the cut velocity follows from volume flow and geometry (or rotor speed); calibrate the sharpness parameter to your data and run a sensitivity study to find the settings that land the cut where you want it.

**Q: Why is my classifier producing too many fines in the coarse fraction?**

A: That is misplacement — usually a low separation sharpness, overloading, or bypass. In Dyssol Pro you study how the sharpness and cut velocity move that misplaced-fines fraction, and whether fine-powder agglomeration is blurring the cut.

**Q: What parameters affect classification efficiency?**

A: Gas velocity, rotor speed, geometry, solids loading, and particle density. These map onto the model’s cut velocity and sharpness in Dyssol Pro, so you can vary each in a sensitivity study and see its effect on the grade curve before touching the machine.

**Q: How do I calculate the cut point of a particle classifier?**

A: The cut point is the size where the grade efficiency is 0.5 — where a particle’s settling velocity equals the cut velocity. Dyssol Pro computes the cut velocity from flow, geometry, and rotor speed and returns the full grade curve, so you read the cut size directly off it.

**Q: How can I reduce bypass in an air classifier?**

A: Bypass means coarse reporting to fines (or vice versa) regardless of size, often from poor flow distribution or fine re-agglomeration. Dyssol Pro can include an agglomeration term and a throughput dependence, so you study how loading and operating point drive the apparent bypass and find a better point.

**Q: What is the difference between static and dynamic classifiers?**

A: A static classifier fixes the cut through geometry and gas flow; a dynamic one adds a rotating wheel so the cut size is set by rotor speed and can be tuned online. Dyssol Pro provides both static gravity and dynamic impeller-wheel classification, so you can compare the two for your duty.

**Q: How does particle density affect classifier performance?**

A: Settling velocity rises with particle density, so at the same size a denser particle reports coarse. Dyssol Pro takes solid density from the materials database in the settling calculation, which means multi-density feeds separate by both size and density automatically.

**Q: How do I optimize airflow in a powder classifier?**

A: Airflow sets the cut velocity: too high and you lose coarse to the fines, too low and the cut drifts coarse. In Dyssol Pro you vary the gas volume flow and read the cut and yield off the grade curve to find the airflow that meets the fineness target.

**Q: How can I sharpen the separation curve of a classifier?**

A: Mechanically, sharpness comes from uniform flow and low turbulence; in the model it is a single sharpness term. In Dyssol Pro you fit the sharpness to a measured curve, then study how a sharper cut would change product quality and recycle load across the circuit.

**Q: Why is my classifier cut size drifting over time?**

A: Drift usually traces to changing gas flow, rotor speed, or solids loading (or build-up). Dyssol Pro lets you impose those feed and flow variations dynamically and see how the cut moves, helping you separate a process cause from a mechanical one.

**Q: How does rotor speed affect air classifier performance?**

A: Higher rotor speed raises the centrifugal cut velocity and shifts the cut finer. Dyssol Pro’s impeller-wheel model takes rotor speed directly (it sets the circumferential and cut velocities), so you can map cut size against speed in a sensitivity study.

**Q: How can I reduce coarse contamination in the fine product?**

A: Either move the cut finer or sharpen it. In Dyssol Pro you study how cut velocity and the sharpness parameter trade off against the coarse-in-fine fraction, and pick the operating point that meets the product spec.

**Q: What causes poor classification of irregular particles?**

A: Irregular shape changes drag and effective settling velocity, so shape spreads the cut. In Dyssol Pro this is captured through a cut and sharpness calibrated to your measured data, so the shape effect is carried automatically.

**Q: How do feed rate changes affect classifier efficiency?**

A: Higher loading typically blunts the cut and shifts it. Dyssol Pro can carry a throughput dependence in the separation, so you can run a dynamic feed-rate study and see how efficiency and cut respond.

**Q: How can I select a classifier for micronized powders?**

A: Fine cuts need the high centrifugal field of a dynamic impeller-wheel classifier, and fine-powder agglomeration becomes decisive. Dyssol Pro lets you compare static gravity versus dynamic impeller-wheel classification and use an agglomeration term to see how realistic a fine cut is for your powder.

**Q: How do I validate classifier performance experimentally?**

A: You measure the partition (grade) curve by sampling both fractions. In Dyssol Pro you calibrate the model’s cut velocity and sharpness to that measured curve, giving a validated unit you can then use predictively in the flowsheet.

**Q: What is the influence of humidity on powder classification?**

A: Humidity makes fines stick together, so they behave like coarser particles and the apparent cut shifts. In Dyssol Pro an agglomeration term captures that apparent-cut shift, and you model the upstream drying in the flowsheet to find a safe moisture window.

**Q: How can I reduce energy use in air classification?**

A: Energy goes into the fan and rotor, so the lever is the minimum airflow and rotor speed that still hit the cut. Dyssol Pro computes the cut that each airflow and rotor speed produces, so you can find the lowest-airflow, lowest-speed operating point that still hits the target.

---

## Disk Separator

URL: https://www.dyssoltec.com/classification/disk-separator/ (German: https://www.dyssoltec.com/de/classification/disk-separator/)

Disk-stack centrifuge simulation in Dyssol Pro: predict clarification efficiency by particle size and density and the sediment/clarified-liquid split in dynamic flowsheets.

Clarify a suspension across a stack of rotating conical disks — resolving the split into sediment and clarified liquid by particle size and density — inside a connected dynamic flowsheet.

### How it works

A disk-stack centrifuge spins a stack of more than a hundred closely spaced conical disks. The feed suspension enters at the outer radius and flows inward through the thin channels between the disks. Rotation imposes a strong centrifugal field, so every particle denser than the liquid is driven outward and downward onto the underside of a disk, then slides to the outer radius where the sediment collects and is discharged. The clarified liquid continues inward and leaves at the center.

The short inter-disk distance is the trick: a particle only has to settle across a thin channel before it reaches a disk surface, so even fine particles are captured at modest residence time. Capture therefore depends on both particle size and the density difference between solid and liquid — a larger particle or a denser solid settles faster and is caught more completely. Higher rotational speed, more disks, and lower throughput all sharpen the separation; high feed concentration hinders settling because particles get in each other’s way.

### The model

Dyssol Pro computes the clarification at the population level: for every particle size class and every solid compound it determines the fraction settled out to the sediment, splitting the suspension into a sediment with defined residual liquid content and a clarified liquid — at every time point of the dynamic flowsheet.

### Equipment this model can represent

- **Clarifiers (solid-retaining)**: Low solids load; periodic manual cleaning of the retained sediment.
- **Self-cleaning separators**: The bowl opens periodically to eject accumulated solids automatically.
- **Nozzle separators**: Continuous solids discharge through peripheral nozzles for higher solids loads.
- **Purifiers / concentrators**: Liquid–liquid–solid duty, e.g. separating two liquid phases plus solids.

### Typical engineering studies

- **Clarification prediction**: Predict clarification efficiency and sediment/permeate splits for a given machine and feed.
- **Geometry & speed studies**: Study capture versus rotational speed, disk spacing, channel count, and throughput.
- **Concentration effects**: Account for hindered settling on dense feeds at higher solids concentration.
- **Calibration & scale-up**: Calibrate the model’s adjustment factors to measured performance, then scale up.
- **Multi-density separation**: Resolve multi-density solid mixtures, since separation is computed per compound density.

### FAQ

**Q: How does a disk stack separator work?**

A: Closely spaced rotating conical disks create a centrifugal field thousands of times gravity; solids denser than the liquid settle the short distance onto a disk underside, slide outward, and collect as sediment while the clarified liquid leaves at the center. Dyssol Pro reproduces this with a grade efficiency resolved by particle size and density, computed from the machine geometry and speed.

**Q: What is the difference between a disk separator and a decanter centrifuge?**

A: A disk stack clarifies dilute-to-moderate suspensions of fine particles to high clarity; a decanter handles high solids loads and delivers a drier, conveyable cake at a coarser cut. Dyssol Pro provides both units, so clarification and dewatering can be compared for the same feed in one flowsheet.

**Q: How can I improve fine particle removal in a disk separator?**

A: Fine capture improves with higher bowl speed, tighter disk spacing and more disks (a shorter settling distance), and lower throughput — and with anything that raises the density difference or lowers the liquid viscosity. In Dyssol Pro speed, disk geometry, and feed rate are inputs to the grade efficiency, so you see which lever moves the fine end of the curve most.

**Q: Why is my disk separator losing product in the reject stream?**

A: Product reports to the sediment when the separation is set sharper than the product’s size and density require — typically too much speed or too little flow for the duty. Dyssol Pro’s size- and density-resolved efficiency shows exactly which classes go where, so speed and throughput can be retuned to recover the product.

**Q: How does flow rate affect disk separator efficiency?**

A: Higher flow shortens the residence time in the channels, so fine capture falls — every disk stack has a throughput above which clarity degrades visibly. Dyssol Pro takes the volume flow from the connected stream, so efficiency versus throughput is read directly from the flowsheet.

**Q: How do I choose between nozzle discharge and self-cleaning disk separators?**

A: Nozzle machines suit continuous, higher solids loads; self-cleaning bowls suit intermittent, lower loads where clarity matters most — the deciding numbers are the sediment rate and how wet it may be. Dyssol Pro quantifies exactly that duty: the sediment mass flow and its liquid content for your feed.

**Q: What causes fouling in a disk stack centrifuge?**

A: Fouling comes from adhesive solids, precipitating species, or heat-sensitive product coating the disks; it narrows the channels until clarity and capacity fall, and the remedy is feed conditioning plus cleaning cycles. Dyssol Pro helps by modeling the upstream steps that set the fouling propensity and the solids load actually arriving at the machine.

**Q: How can I reduce maintenance frequency for a disk separator?**

A: The maintenance interval is driven by fouling rate and mechanical wear, so the process lever is running at the mildest operating point that still meets clarity — the lowest speed and load, and the cleanest feed. Dyssol Pro finds that operating point by mapping the required clarity against speed and throughput.

**Q: How does particle density difference affect disk separator performance?**

A: Settling velocity scales with the density difference between solid and liquid, so a small difference needs disproportionately more centrifugal effort — which is why cell debris is harder to clarify than mineral fines. Dyssol Pro takes each compound’s density from the materials database, so mixed-density solids separate by size and density automatically.

**Q: How can I simulate liquid-solid separation in a disk separator?**

A: This is the unit’s purpose: the machine geometry, rotational speed, and feed properties define a size- and density-resolved settling efficiency that splits the suspension into sediment and clarified liquid. In Dyssol Pro you place the unit in the flowsheet and it returns the split and both stream compositions dynamically.

**Q: How do I optimize discharge frequency in a disk separator?**

A: The bowl should discharge just before accumulated sediment reaches the disk stack and disturbs clarity — so the frequency follows from the solids arrival rate and the sludge-space volume. Dyssol Pro predicts that solids arrival rate and the sediment’s liquid content, which is precisely the basis for setting the interval.

**Q: Why is my disk separator producing unstable separation results?**

A: Instability usually traces to fluctuating feed flow or solids concentration, and at higher concentrations hindered settling amplifies the swings. In Dyssol Pro you impose the measured feed transients, with the hindered-settling correction active, and see whether the process alone explains the variation.

**Q: How does viscosity affect disk stack separator performance?**

A: Settling velocity is inversely proportional to liquid viscosity, so a viscous broth or a cold feed can cut capture dramatically — preheating the feed is often the cheapest capacity upgrade. Dyssol Pro takes viscosity from the materials database at the operating condition, so its effect appears directly in the predicted efficiency.

**Q: What causes solids buildup inside a disk separator?**

A: Build-up means solids arrive faster than the discharge removes them — a mismatch of feed load, discharge capacity, and timing. Dyssol Pro predicts the sediment mass flow from the feed and the separation, which is the number the discharge system has to keep up with.

**Q: How can I reduce product loss during sludge discharge?**

A: Losses scale with how much liquid — and the product dissolved or suspended in it — leaves with each ejection, so partial-discharge settings and correct timing matter most. Dyssol Pro tracks the sediment’s liquid content and mass flow, so the entrained product per discharge can be minimized on the process side.

**Q: How do I choose the right disk spacing for separation?**

A: Narrower channels shorten the settling distance and capture finer particles, but reduce hydraulic capacity and clog sooner — fine clarification runs tight stacks, fibrous or fouling feeds need wider ones. In Dyssol Pro the channel spacing and count are model inputs, so spacing is traded against efficiency and throughput before touching the machine.

**Q: How can I improve phase separation in a disk separator?**

A: Phase separation improves with more centrifugal effort (speed), more settling area (disks), longer residence (lower flow), and a feed conditioned toward larger effective particle size — flocculation helps where shear allows it to survive. Dyssol Pro ranks these levers by their effect on the sediment/permeate split for your actual feed.

**Q: What is the effect of temperature on disk separator efficiency?**

A: Temperature acts mainly through liquid viscosity — warmer, thinner feed settles solids markedly faster — with a smaller effect through the density difference. In Dyssol Pro you run the unit at the corresponding liquid properties and read the efficiency gain of preheating directly.

**Q: How do I troubleshoot vibration in a disk stack separator?**

A: Vibration in a disk stack points to bowl imbalance — uneven sediment deposits, damaged disks, or worn bearings — and is diagnosed mechanically, starting with cleaning and inspection. Simulation contributes prevention: Dyssol Pro predicts the solids load and discharge duty, so the bowl is not run into the loading that creates uneven deposits.

**Q: How can I model centrifugal clarification of fine suspensions?**

A: Centrifugal clarification is described by a grade efficiency over particle size and density, derived from settling in the rotating channels — with a hindered-settling correction when the suspension is concentrated. That is exactly the Dyssol Pro disk-separator unit, returning clarified-liquid quality and sediment load inside the connected flowsheet.

---

## Gas Filter

URL: https://www.dyssoltec.com/classification/filter-gas/ (German: https://www.dyssoltec.com/de/classification/filter-gas/)

Gas filter (baghouse) simulation in Dyssol Pro: a dynamic cake-filtration model with Darcy pressure drop and size-dependent separation efficiency.

Build a dust cake on a filter medium and predict the size-dependent capture, clean-gas dust load, and the rising pressure-drop cycle — inside a connected dynamic flowsheet.

### How it works

A gas filter passes a dust-laden gas through a permeable fabric or cartridge. Particles are captured by the medium and, increasingly, by the dust cake that builds on its surface — once a cake forms, it does most of the filtration, so capture efficiency rises but so does the resistance to flow. The pressure drop therefore climbs continuously as the cake grows, following Darcy’s law: flow resistance is the sum of the clean fabric and the accumulating cake.

This makes a gas filter an inherently dynamic, cyclic device. The cake cannot grow forever, so when a set time interval or a set pressure drop is reached, the filter is cleaned (e.g. a pulse-jet knocks the cake off), the collected solids drop into the hopper, and the cycle restarts. Fine particles are the hardest to catch on the bare medium but are captured well once a cake is established, which is why cleaning too aggressively or too often can actually hurt efficiency.

### The model

Dyssol Pro models the gas filter dynamically: dust accumulates as a cake on the medium, the cake takes over most of the filtration, and the pressure drop rises continuously as it grows — a direct, size-resolved output at every time point of the flowsheet, with the cake removed on a cleaning cycle.

### Equipment this model can represent

- **Pulse-jet baghouses**: Rows of fabric bags cleaned by reverse compressed-air pulses; the workhorse for high dust loads.
- **Cartridge filters**: Pleated cartridges giving large area in a small footprint, for finer dust at lower loads.
- **Reverse-air / shaker baghouses**: Gentler cleaning for fragile cakes or fine fabrics.
- **Sintered / ceramic element filters**: For high-temperature or chemically aggressive gas streams.

### Typical engineering studies

- **Emissions & ΔP cycle**: Predict clean-gas dust load and the pressure-drop cycle for a given filter and dust.
- **Area & trigger sizing**: Size the filter area and set cleaning triggers (time or ΔP) against an emission target.
- **Gas-cleaning trains**: Place the filter after a cyclone, dryer, or pneumatic-transport unit and study how much load each stage carries.
- **Grade-curve calibration**: Calibrate the size-dependent separation efficiency to a measured grade curve, then use predictively.
- **Cleaning-interval trade-off**: Study how cleaning interval and feed dust load trade off against pressure drop and emissions.

### FAQ

**Q: How do I choose the right gas filter for dusty exhaust air?**

A: You match filter type and media to the dust load, temperature, and target emission — baghouses for heavy loads, cartridges for fine dust at lower loads. Dyssol Pro helps on the sizing side: model the filter on your actual gas and dust, predict clean-gas dust load and the pressure-drop cycle, and check the area needed before specifying the unit.

**Q: Why is pressure drop increasing in my bag filter?**

A: Pressure drop rises as the dust cake builds — that’s normal until cleaning resets it; a steady creep upward means incomplete cake release or blinding. Dyssol Pro models exactly this Darcy-law rise from cake mass, so you can study how cleaning interval and dust load shape the pressure-drop cycle.

**Q: How can I prevent filter blinding in gas filtration?**

A: Blinding — an irreversible cake — comes from sticky, fine, or moist dust embedding in the medium, so it is limited by conditioning the gas upstream (cooling below the sticky range, a cyclone pre-separator to drop the load) and matching the medium to the dust. Dyssol Pro predicts the cake build-up and pressure rise that signal it, and lets you study that upstream conditioning in the flowsheet.

**Q: What filter media is best for fine powder dust collection?**

A: Media selection (PTFE, polyester, membrane-coated, and so on) depends on the dust, temperature, and chemistry. Dyssol Pro covers the process side — the size-dependent capture and clean-gas emissions you should achieve — so the media is chosen to deliver that target.

**Q: How does humidity affect gas filter performance?**

A: Humidity makes dust cohere and can cause condensation that blinds the medium. Dyssol Pro tracks the upstream gas temperature and cooling in the flowsheet, so you can keep the gas above its dew point and study the resulting dust behavior.

**Q: How can I reduce dust emissions after a dryer or kiln?**

A: The standard answer is a properly sized filter, often behind a cyclone pre-separator. In Dyssol Pro you connect the dryer or kiln to a cyclone and then the gas filter, and optimize the filter’s area and cleaning trigger so the clean-gas dust load meets the limit.

**Q: What causes filter bags to fail prematurely?**

A: Premature failure comes from abrasion, flex fatigue, chemical attack, or over-temperature, so bag life is extended by holding the dust load, gas temperature, and cleaning intensity down. Dyssol Pro computes the dust load and pressure-drop operating point, so you can flag the high-load conditions that stress the bags.

**Q: How do pulse-jet cleaning parameters affect filter efficiency?**

A: Cleaning too hard or too often strips the beneficial cake and lets fines through; too little lets pressure drop climb. Dyssol Pro represents cleaning through the removal trigger — a set time or a pressure-drop threshold — so you can study how the cleaning interval trades emissions against pressure drop.

**Q: How do I size a gas filter for a pneumatic transport system?**

A: You match the filter area to the conveying gas flow and dust load for an acceptable air-to-cloth ratio. In Dyssol Pro you connect the filter to the pneumatic-transport unit, run it at the actual gas flow, and size the area against the resulting pressure-drop cycle and emissions.

**Q: How can I model dust separation in a gas filter?**

A: This is the unit’s purpose: a dynamic filter with size-dependent capture and Darcy-law cake build-up. In Dyssol Pro you set the area, permeabilities, and separation parameters, and it returns the clean-gas dust load, the collected solids, and the pressure-drop cycle.

**Q: How can I reduce compressed air consumption in pulse-jet cleaning?**

A: Compressed-air use falls if you clean less often, which you can only do if pressure drop allows. Dyssol Pro predicts the pressure-drop cycle, so you can find the longest cleaning interval that stays within the pressure-drop limit, minimizing cleaning events.

**Q: Why is dust leaking through my gas filter?**

A: Leakage usually means a torn bag, a failed seal, or cleaning that removes too much cake — partly mechanical. Dyssol Pro models the clean-gas dust load from the separation efficiency, so it tells you the emission you should see; a measured excess points to a physical leak rather than a process cause.

**Q: How do I choose between cartridge filter and baghouse filter?**

A: Cartridges pack more area into less space for fine, lighter dust; baghouses handle heavier loads and coarser dust. Dyssol Pro lets you model each as a filter with the appropriate area and parameters and compare predicted emissions and pressure-drop cycles for your duty.

**Q: What causes condensation problems in gas filters?**

A: Condensation happens when the gas drops below its dew point at the medium — a thermal and humidity effect. Dyssol Pro tracks the upstream gas temperature and cooling in the flowsheet, so you can keep the gas safely above its dew point.

**Q: How can I prevent filter fires or dust explosions?**

A: Dust fires and explosions are prevented by controlling ignition sources, providing explosion venting or suppression, and inerting where the dust demands it, all designed to the dust’s measured explosion characteristics. Keeping dust concentration, oxygen, and ignition energy out of the explosive range is the core of the safety design.

**Q: How does dust cake formation affect filtration efficiency?**

A: The cake is the main filter once formed — efficiency rises with it, which is why some cake is desirable. Dyssol Pro tracks cake mass and its contribution to pressure drop dynamically, so you can study the cake-build/clean cycle and its effect on the operating point.

**Q: How do I optimize cleaning intervals for gas filters?**

A: You want the longest interval that keeps pressure drop and emissions acceptable. Dyssol Pro models the pressure-drop rise and lets you set the cleaning trigger by time or ΔP, so you can optimize the interval directly against both limits.

**Q: What is the influence of particle size distribution on gas filtration?**

A: Finer dust is harder to capture on the bare medium and changes the cake’s resistance. Dyssol Pro’s size-dependent separation efficiency resolves capture per size class, so you see directly how the feed PSD shifts emissions and cake build-up.

**Q: How can I monitor filter performance online?**

A: Online monitoring (ΔP, opacity, triboelectric) is an instrumentation task. Dyssol Pro complements it by predicting the expected pressure-drop cycle and emissions, giving a model baseline to compare live readings against.

**Q: How do I reduce maintenance downtime in dust filtration systems?**

A: Downtime is driven by bag changes and blinding, so it is reduced by running at lower dust loads — for instance with an optimized cyclone pre-separator — and gentler cleaning cycles. Dyssol Pro predicts the dust load and pressure-drop cycle, so you can steer toward the conditions that extend service life.

---

## Cake Filtration

URL: https://www.dyssoltec.com/classification/filter-liquid/ (German: https://www.dyssoltec.com/de/classification/filter-liquid/)

Cake filtration simulation in Dyssol Pro: solid–liquid filtration with cake washing and gas deliquoring, predicting residual cake moisture, purity, and the filtrate split.

Retain solids as a cake, then wash and deliquor it — predicting cake moisture, purity, and the combined filtrate — inside a connected dynamic flowsheet.

### How it works

In cake filtration a suspension is forced through a filter medium (cloth, mesh, or membrane). The solids are too large to pass and accumulate as a filter cake, while the liquid (filtrate) flows through the cake and medium under a pressure difference. As the cake grows it adds resistance, so for a given pressure the flow rate falls — Darcy’s law links the flow to the pressure drop through the cake permeability, height, and the liquid viscosity. The cake is a porous bed whose pores hold liquid, which is why the discharged solids are never bone-dry.

Two finishing steps often follow. Washing displaces contaminated pore liquid with clean wash liquid to purify the cake; how efficiently it does so depends on the wash ratio and on dispersion within the cake. Deliquoring then sucks gas through the cake to push residual liquid out down to a saturation set by the balance between applied pressure and the cake’s capillary pressure. The remaining moisture is what the cake carries away.

### The model

Dyssol Pro models solid–liquid cake filtration for drum, belt, and filter-press duties: all solids report to the cake, the liquid passes through as filtrate, and up to two finishing stages — washing and deliquoring — can be added, with the filtrate and spent wash merged into one outlet and the PSD passing through unchanged.

### Equipment this model can represent

- **Vacuum drum / disc filters**: Continuous filtration with a rotating surface under vacuum.
- **Belt filters**: A moving cloth belt with continuous filtration, washing, and deliquoring zones.
- **Filter presses**: Batch, high-pressure cake filtration for fine or compressible solids.
- **Candle / pressure-leaf filters**: Pressure filtration for polishing and high clarity.

### Typical engineering studies

- **Cake moisture & filtrate split**: Predict cake moisture and filtrate split for a given filtration, washing, and deliquoring setup.
- **Washing optimization**: Study washing-liquid consumption versus residual purity.
- **Deliquoring studies**: Study deliquoring pressure and time versus residual cake moisture.
- **Calibration & scale-up**: Calibrate washing efficiency and cake resistance to lab data, then scale up.
- **Downstream coupling**: Place the filter after a crystallizer or centrifuge and propagate cake and filtrate to downstream drying or treatment.

### FAQ

**Q: How can I improve cake filtration rate?**

A: Filtration rate rises with pressure and cake permeability and falls with viscosity and cake height — so lower, more permeable cakes and higher pressure help. Dyssol Pro computes the Darcy pressure drop from these, so you can study how cake height, permeability, and pressure trade off and find a faster operating point.

**Q: Why is my liquid filter cake too wet?**

A: Wet cake means deliquoring hasn’t driven the saturation down — too little applied pressure or time against the cake’s capillary pressure. Dyssol Pro models deliquoring and returns the residual moisture, so you can study how deliquoring pressure and time reduce it.

**Q: How do I choose between pressure filtration and vacuum filtration?**

A: Vacuum is simple and continuous but limited to ~1 bar of driving force; pressure filtration reaches drier cakes on fine or compressible solids. Dyssol Pro lets you set the pressure difference and compare the resulting filtration rate and cake moisture for each, so the choice rests on predicted performance.

**Q: What causes filter cloth blinding in liquid filtration?**

A: Blinding is fines lodging in the cloth, raising the medium’s resistance, so it is limited by upstream conditioning, a filter aid, or a more open cloth. Dyssol Pro carries the medium resistance in its Darcy pressure-drop calculation, so you can represent a blinded cloth as a higher resistance and quantify its effect on filtration.

**Q: How does particle size distribution affect filtration performance?**

A: Finer particles make a less permeable cake that filters slower and holds more moisture. Dyssol Pro carries the PSD and uses cake permeability in the Darcy calculation, so you can study how a finer feed slows filtration and wets the cake.

**Q: How can I reduce washing liquid consumption in cake filtration?**

A: You want the minimum wash ratio that hits the purity target, which depends on washing efficiency and dispersion. Dyssol Pro models washing, so you can study residual contaminant versus wash-liquid volume and find the smallest effective wash.

**Q: How do I improve solid-liquid separation for fine particles?**

A: Fine particles need higher pressure, sometimes a filter aid or flocculant to build a more open cake. Dyssol Pro models the cake’s filtration and moisture given its permeability, so you can study how a coarser effective cake improves rate and dryness.

**Q: What is the effect of slurry concentration on filtration time?**

A: Higher feed concentration builds the cake faster, reaching the target cake sooner but also raising resistance. Dyssol Pro relates cake height and the Darcy pressure drop to the throughput, so you can study how feed concentration shifts the filtration duty.

**Q: How do I scale up liquid filtration from lab tests?**

A: Scale-up transfers measured cake resistance, washing efficiency, and deliquoring parameters to the full-size area and pressure. Dyssol Pro is built for this: fit those parameters to lab data, then run the model at production area and pressure to predict cake moisture and filtrate before specifying the machine.

**Q: How can I model filter cake buildup over time?**

A: The model relates cake height to the solids filtered and the Darcy resistance it creates. In Dyssol Pro you set the cake parameters and filter area and study how the cake and pressure drop develop for your slurry.

**Q: How can I improve filtrate clarity?**

A: Clarity depends on the medium retaining fines; in this model solids capture is complete, so Dyssol Pro predicts a solids-free filtrate. If real filtrate is turbid, that points to medium penetration or a torn cloth, diagnosed by contrast with the clean-filtrate prediction.

**Q: Why is filtration time increasing during production?**

A: Rising filtration time usually means cloth blinding or a less permeable (finer or more compressible) cake. Dyssol Pro lets you study how reduced permeability or a finer feed raises the Darcy pressure drop and slows filtration, helping separate a feed change from a blinding problem.

**Q: How does cake compressibility affect filtration?**

A: Compressible cakes lose permeability under pressure, so higher pressure yields diminishing rate gains. Dyssol Pro uses cake permeability and resistance in the Darcy calculation, so by varying them with pressure you can study the compressibility effect on rate and moisture.

**Q: How do I choose the right filter aid?**

A: Filter-aid selection (diatomite, perlite, cellulose) is a lab decision about cake structure. Dyssol Pro lets you represent the aid’s effect through a more permeable cake and quantify the gain in rate and dryness, so you can target the performance the aid must deliver.

**Q: What causes cracks in a filter cake?**

A: Cracking comes from cake shrinkage during deliquoring, which lets gas bypass and stalls drying, so it is limited by gentler deliquoring and avoiding over-drying. Dyssol Pro computes the intended deliquoring saturation, so cracking shows up when real moisture exceeds that prediction.

**Q: How can I optimize cake washing efficiency?**

A: Efficient washing means displacing contaminated pore liquid with the least wash, set by wash ratio and dispersion. Dyssol Pro’s washing model lets you study residual contaminant versus wash ratio and find the optimum wash sequence.

**Q: How does pressure affect liquid filtration performance?**

A: Higher pressure raises filtration rate and drives deliquoring to a lower moisture, with diminishing returns on compressible cakes. Dyssol Pro takes the pressure difference as an input to both the Darcy and deliquoring models, so you can map rate and cake moisture against pressure.

**Q: How can I prevent channeling in a filter cake?**

A: Channeling — gas finding open paths during deliquoring — comes from a non-uniform cake, so it is limited by even cake formation and avoiding cracks. Dyssol Pro predicts the uniform-cake deliquoring result, so a worse real outcome points to channeling from cake formation or cracking upstream.

**Q: How do I reduce residual moisture after filtration?**

A: Residual moisture is set by the deliquoring balance of applied pressure against capillary pressure, plus time. Dyssol Pro models this and returns the cake moisture, so you can study how more deliquoring pressure or time dries the cake toward its residual saturation.

**Q: How can I model combined filtration and washing?**

A: The unit does exactly this: filtration, then washing, then deliquoring, with the spent wash merged into the filtrate. In Dyssol Pro you parameterize all three stages and get the washed cake’s purity and moisture together in one unit.

---

## Fluidized Bed Spray Granulator

URL: https://www.dyssoltec.com/granulation/fluidized-bed-spray-granulator/ (German: https://www.dyssoltec.com/de/granulation/fluidized-bed-spray-granulator/)

Fluidized bed spray granulator simulation in Dyssol Pro: a two-zone population-balance layering model resolving particle size, moisture, and temperature.

A fluidized-bed granulator with separate spraying and drying zones — layering growth by population balance with convective drying — resolving size, moisture, and temperature in a connected flowsheet.

### How it works

A fluidized-bed spray granulator combines growth and drying in one fluidized bed. Particles are kept suspended by a hot gas while a liquid suspension is sprayed onto them; the liquid spreads over the surfaces and the solvent evaporates, depositing a thin solid layer, so each pass through the spray makes the particles grow. Evaporation runs at a near-constant rate while the surface stays wet and then slows as the layer dries, which ties growth and drying together — the same heat that dries the shell limits how fast fresh liquid can be added.

The bed behaves as a spraying zone, where wetting and growth happen, and a drying zone, where particles dry between spray passes — a structure that captures real bottom- and top-spray configurations. Fine particles can be carried out by the gas (elutriation), and product is separated out at the discharge. Keeping the wetting and drying in balance is the central challenge: too wet and the bed defluidizes or over-agglomerates, too dry and growth suffers.

### The model

Dyssol Pro models the spray granulator dynamically over two zones — a spraying zone where wetting and growth occur and a drying zone where particles dry between passes — coupling layering growth by population balance with the heat and mass transfer of drying, and resolving particle size, moisture, and temperature at every time point of the flowsheet.

### Equipment this model can represent

- **Continuous FB spray granulators**: Steady layering granulation with integrated drying.
- **Wurster (bottom-spray) granulators**: Bottom spray for uniform layer growth and coating.
- **Top-spray FB granulators**: Spray from above the bed, common for granulation.
- **Spouted-bed spray granulators**: For coarse, dense, or sticky granules.

### Typical engineering studies

- **Product size/moisture prediction**: Predict product size, moisture, and temperature for given spray and gas conditions.
- **Wetting–drying balance**: Study spray rate vs. inlet gas temperature/flow against bed moisture to stay stable.
- **Spray & discharge configuration**: Compare bottom- vs. top-spray configurations and the three discharge modes.
- **Elutriation & dust recovery**: Quantify elutriation/dust losses and couple a downstream cyclone/filter and a screen recycle.
- **Calibration & scale-up**: Calibrate growth, overspray, and drying parameters to data, then scale up.

### FAQ

**Q: How does a fluidized bed spray granulator work?**

A: Hot gas fluidizes the particles, a suspension is sprayed onto them, and the solvent evaporates to leave a solid layer, so particles grow while drying in the same bed. Dyssol Pro models exactly this with coupled spraying and drying zones — population-balance layering growth plus heat and mass transfer — returning size, moisture, and temperature.

**Q: How can I control granule size in fluidized bed spray granulation?**

A: Granule size is set by the spray rate, residence, and the classifier cut at discharge. Dyssol Pro couples growth to the sprayed-solids balance and offers a zig-zag discharge cut, so you can study how spray rate and cut size shape the product PSD.

**Q: Why are granules sticking to the walls of the granulator?**

A: Wall sticking comes from locally overwet, tacky particle surfaces. Dyssol Pro tracks surface moisture and temperature per size class, so you can study spray and drying conditions that keep particles below the tacky state.

**Q: How do spray rate and drying air temperature affect granule growth?**

A: Spray rate adds solids (growth) and liquid (wetting); air temperature sets drying capacity. Dyssol Pro resolves both through the coupled growth and heat/mass balances, so you can map growth rate and bed moisture against spray rate and inlet temperature.

**Q: How can I avoid overwetting in a spray granulation process?**

A: Overwetting is avoided by keeping the spray rate within the bed’s drying capacity. Dyssol Pro models that balance explicitly — sprayed liquid against evaporation — so you can find the spray-rate/temperature window that keeps the bed moisture safe.

**Q: What causes broad particle size distribution in spray granulation?**

A: A broad PSD comes from uneven growth, nucleation of new fines, and recycle. Dyssol Pro’s population balance resolves the full PSD and the classifier cut, so you can study which conditions broaden it and how classification tightens the product.

**Q: How do nozzle position and droplet size influence granule quality?**

A: Nozzle position (bottom/top spray) sets where wetting and drying occur; droplet size affects layering vs. agglomeration. Dyssol Pro models the bottom/top spray gas routing and layering growth, so you can compare spray configurations, with droplet-scale detail entering through the calibrated growth parameters.

**Q: How can I improve binder distribution in fluidized bed granulation?**

A: Even binder distribution comes from spray pattern, bed mixing, and drying balance. Dyssol Pro models the spray and drying zones and the net growth, so you can study the wetting-drying balance that supports uniform layering.

**Q: How do I prevent elutriation of fines in a spray granulator?**

A: Elutriation falls with lower gas velocity and fewer fines. Dyssol Pro models elutriation with a size-dependent grade efficiency, so you can study how gas velocity and the fine fraction drive the loss and size a downstream cyclone/filter to recover it.

**Q: How can I scale up fluidized bed spray granulation?**

A: Scale-up transfers the growth, overspray, and drying parameters to a larger bed and gas flow. Dyssol Pro lets you calibrate them at pilot scale and run the model at production geometry to check PSD, moisture, and dust before building.

**Q: How can I avoid spray nozzle clogging in fluidized bed granulation?**

A: Clogging comes from suspension drying at the nozzle tip or from high solids and viscosity in the feed. It is controlled by conditioning the feed, keeping it flowing, adding nozzle purge or cooling air, and matching the nozzle bore to the suspension.

**Q: Why is my granulator producing hollow or weak granules?**

A: Hollow or weak granules form from rapid drying or poor layer consolidation. Dyssol Pro computes the drying history — moisture and temperature — that governs them, so you can study gentler drying conditions that build denser, stronger layers.

**Q: How does atomization pressure affect granule size?**

A: Atomization pressure sets droplet size, which influences layering vs. agglomeration and the granule structure. This enters Dyssol Pro through the calibrated growth parameters, so you can study its net effect on the product PSD.

**Q: How can I balance drying and wetting in spray granulation?**

A: This is the core trade-off: enough spray for growth, enough heat for drying. Dyssol Pro models both explicitly in the two zones, so you can find the spray-rate/temperature/gas-flow combination that grows granules while keeping the bed in a stable moisture range.

**Q: What causes defluidization during spray granulation?**

A: Defluidization happens when the bed gets too wet and sticky and particles stop fluidizing. Dyssol Pro tracks the surface moisture and temperature that precede it, so you can steer the spray and drying conditions that keep the bed safely fluidized.

**Q: How do seed particles affect granule growth?**

A: Seed (nuclei) number and size set the surface area sharing the spray, hence the per-particle growth rate. Dyssol Pro takes an external-nuclei inlet and couples growth to total surface area, so you can study how seed feed and size control the product size.

**Q: How can I control layering versus agglomeration mechanisms?**

A: Layering (smooth shell growth) dominates at good drying; agglomeration (sticking) dominates when wetter. Dyssol Pro’s granulator models the layering mechanism; for agglomeration-dominated growth the agglomerator’s kernel model is the right tool, and comparing the two helps you target the regime you want.

**Q: What is the impact of binder viscosity on spray granulation?**

A: Binder viscosity affects droplet spreading and layer formation — a material property that enters through the growth behavior. Dyssol Pro captures its net effect via calibrated growth parameters, so you can study how it shifts the product PSD.

**Q: How can I reduce batch-to-batch variation in spray granulation?**

A: Variation comes from inconsistent seed, spray, and drying conditions. Dyssol Pro lets you run sensitivity studies on those inputs to see which most move the product PSD and moisture, so you control the critical ones for consistency.

**Q: How do I model nucleation, growth, and breakage in fluidized bed granulation?**

A: A full population balance for granulation growth tracks three mechanisms: nucleation forms new fine particles, layering growth deposits sprayed solids onto existing particle surfaces, and breakage fractures particles into smaller ones. Dyssol Pro’s spray granulator implements nucleation — through the external nuclei inlet and overspray — and layering growth in its population balance, while agglomeration-driven growth and breakage are represented by combining it with Dyssol Pro’s agglomerator and mill units, so you match whichever mechanisms your process actually shows.

---

## Solids Bunker

URL: https://www.dyssoltec.com/storage/bunker/ (German: https://www.dyssoltec.com/de/storage/bunker/)

Solids bunker simulation in Dyssol Pro: an ideally-mixed or non-mixing holdup buffer that stores solids and smooths flow fluctuations between connected units.

Accumulate and smooth the solid stream in a bunker buffer — ideally mixed or non-mixing — tracking holdup and averaged properties over time between connected units in a dynamic flowsheet.

### How it works

A bunker, silo, or hopper holds a mass of bulk solids and releases it on demand. Physically nothing is transformed — the particles are just stored — but the bunker plays a crucial dynamic role in a process: it decouples upstream and downstream units, absorbs flow fluctuations, and provides residence time. Material flows in at one rate and out at another, and the stored mass rises or falls with the difference between them.

How much the contents mix while they pass through matters just as much as how much is stored. At one extreme the whole vessel is well stirred, so what leaves has the averaged composition of everything inside; at the other, material moves through in the order it arrived, so a change at the inlet reappears at the outlet only after the stored material ahead of it has left. Real vessels sit between these, depending on geometry and flow pattern.

### The model

Dyssol Pro models the bunker as a dynamic solids holdup: the stored mass rises or falls with the difference between the inflow and the outflow, and the unit maintains time-dependent norms of the stream properties and distributions so the buffering dynamics are represented correctly at every time point of the flowsheet. Only the solid phase is accumulated; other phases pass through.

### Equipment this model can represent

- **Silos and storage bins**: Large-volume bulk storage between process stages.
- **Hoppers**: Converging vessels feeding a downstream unit at a controlled rate.
- **Surge / buffer bins**: Small day-bins that decouple continuous units.
- **Stirred slurry tanks**: Agitated vessels keeping suspensions homogeneous (the “tank” analogue).

### Typical engineering studies

- **Buffer / surge capacity**: Add buffer capacity to a dynamic flowsheet and damp feed fluctuations.
- **Residence-time studies**: Study residence time and how a buffer smooths disturbances reaching downstream units.
- **Batch/continuous decoupling**: Decouple batch and continuous sections, or stabilize a recycle loop.
- **Buffer sizing**: Size a buffer (target mass) so downstream units see a steady feed under upstream upsets.
- **Upset scenarios**: Investigate startup/shutdown and feed-interruption scenarios dynamically.

### FAQ

**Q: Why does powder stop flowing from a bunker?**

A: Flow stops from arching — a stable bridge over the outlet — or rat-holing — a stable vertical channel — both from cohesive powder in an outlet or hopper that is too small or too shallow. It is cured by sizing the outlet above the powder’s critical arching dimension and making the hopper steep and smooth enough for mass flow, using the measured flow function.

**Q: How can I prevent bridging and rat-holing in a silo or bunker?**

A: Prevention is geometric: a large enough outlet and a hopper steep and smooth enough for mass flow, both sized from the powder’s measured flow function and wall friction. Where geometry alone is not enough, discharge aids such as vibration, air pads, or an activated hopper section restore reliable flow.

**Q: What hopper angle is needed for reliable powder discharge?**

A: The hopper half-angle for mass flow follows from the wall-friction angle between the powder and the wall material and the powder’s internal flow properties, measured in a shear tester. Steeper, smoother walls give mass flow; a rough guide is 15 to 30 degrees from vertical, but the value must be set from the measured properties for the actual powder and wall.

**Q: How do I design a tank for slurry suspension without settling?**

A: Keeping solids suspended needs an agitator sized so its speed exceeds the just-suspended condition for the coarsest, densest particles, which depends on particle size and density, solids loading, and liquid viscosity. The impeller type, diameter, and speed are chosen to reach that condition with margin for the heaviest expected feed.

**Q: How can I avoid segregation during storage of granular material?**

A: Segregation during storage comes from size and density differences as material forms a heap on filling and drains on discharge. It is limited by mass-flow hopper design that keeps first-in-first-out flow, central loading to reduce rolling on the pile, lower drop heights, and a narrower feed size distribution.

**Q: What causes caking in powder storage tanks?**

A: Caking comes from moisture migration, time consolidation under the material’s own weight, and humidity cycling that bonds particles into a solid mass. It is limited by drying the feed, sealing against humid air, and avoiding long static storage. Dyssol Pro tracks the stored mass and the composition of the buffered stream, so you can study how upstream moisture reaches the store in the connected flowsheet.

**Q: How do I calculate residence time distribution in a bunker?**

A: RTD follows from the holdup and the flow pattern — ideal-mixing gives a known exponential-type RTD, plug flow a delay. Dyssol Pro models the ideal-mixed (and plug-flow variant) holdup dynamically, so you obtain the residence behavior directly and see how it buffers disturbances.

**Q: What level measurement technology works best for dusty powders?**

A: Level sensing for dusty powders uses radar, guided-wave, capacitance, or weigh cells, chosen for the dust, dielectric, and vessel geometry. Dyssol Pro predicts the holdup mass over time, which is exactly the quantity such a sensor tracks, giving a model baseline to compare live readings against.

**Q: How can I prevent moisture pickup in a powder storage tank?**

A: Moisture pickup is controlled by sealing the vessel, applying a dry-gas purge or blanket, and controlling the ambient humidity around the store. Dyssol Pro tracks the moisture state of the streams entering and leaving the store, so you can bound the exposure across the connected flowsheet.

**Q: How do I size a buffer tank between continuous unit operations?**

A: Buffer size is set by how much fluctuation you must absorb and the residence you need. This is exactly a Dyssol Pro use case: set the target holdup mass and simulate upstream upsets to see how well the buffer steadies the downstream feed, sizing it against the disturbance.

**Q: How can I improve mass flow in a powder bunker?**

A: Mass flow, where the whole contents move together, is achieved by making the hopper steep and smooth enough and the outlet large enough, set from the powder’s wall friction and flow function. Low-friction liners, the right wall angle, and an adequately sized outlet are the main levers, with discharge aids where geometry alone falls short.

**Q: Why does my silo discharge unevenly?**

A: Uneven or pulsing discharge usually means funnel flow or partial rat-holing, where only a central core moves while material at the walls stays put. It is corrected by steepening and smoothing the hopper toward mass flow, enlarging the outlet, or fitting a flow-promoting insert or discharge aid.

**Q: How do I choose between mass flow and funnel flow bunker design?**

A: Mass flow gives first-in-first-out movement, no dead zones, and minimal segregation but needs steeper, taller hoppers and costs more; funnel flow is cheaper and more compact but risks rat-holing, dead zones, and segregation. The choice is made from the powder’s flow function, its cohesion and segregation tendency, and whether the product tolerates uneven residence time.

**Q: How can I avoid dead zones in a storage tank?**

A: Dead zones — stagnant material at the walls or corners — come from funnel flow in a hopper or poor agitation in a tank. They are avoided by mass-flow hopper geometry with steep, smooth walls and a large outlet, or, in a stirred vessel, by an impeller and baffling that sweep the full volume.

**Q: What causes powder segregation during filling of a bunker?**

A: Fill segregation arises as particles form a heap: coarse or dense particles roll to the walls while fines stay near the centre, and dust can be carried off by air currents. It is limited by central loading, reducing the drop height, using a distributor or fill pipe, and narrowing the feed size distribution.

**Q: How do I design an agitator for a slurry tank?**

A: Agitator design starts from the duty — solids suspension, blending, or heat transfer — then selects an impeller type and diameter and the speed and power that meet it. For suspension the speed is set above the just-suspended condition for the coarsest, densest particles, with the motor sized from the power number, the fluid density, and the resulting torque.

**Q: How can I prevent sedimentation in a suspension tank?**

A: Sedimentation is prevented by keeping the agitation above the level at which the coarsest, densest particles settle, which depends on particle size and density, solids loading, and liquid viscosity. Adequate impeller speed and placement, and sometimes a draft tube or a set off-bottom clearance, keep the solids suspended.

**Q: What is the best way to empty sticky powders from a tank?**

A: Sticky, cohesive powders discharge best from a mass-flow hopper with steep, low-friction walls and a generously sized outlet, backed by flow aids where needed — vibration, air pads or fluidizing cones, or a mechanical activator. Keeping the powder dry and avoiding long static storage that lets it consolidate also helps it release.

**Q: How does wall friction affect bunker discharge?**

A: Wall friction — the friction angle between the powder and the wall material — sets whether a hopper runs in mass flow or funnel flow and the wall angle needed for mass flow. Higher wall friction demands a steeper hopper; lower friction, from a polished or lined wall, allows a shallower one and more reliable flow.

**Q: How can I model residence time in a storage vessel?**

A: This is squarely in scope: Dyssol Pro models the bunker as an ideally mixed (or plug-flow) holdup, so you obtain residence time and the RTD directly and study how the buffer smooths disturbances across the flowsheet.

---

## Heat Exchanger

URL: https://www.dyssoltec.com/thermal/heat-exchanger/ (German: https://www.dyssoltec.com/de/thermal/heat-exchanger/)

Heat exchanger simulation in Dyssol Pro: an effectiveness-based two-stream model for co- and counter-current energy transfer in solids flowsheets.

Transfer energy between two streams without mixing — predicting outlet temperatures and heat duty for co- or counter-current operation — inside a connected dynamic flowsheet.

### How it works

A heat exchanger moves thermal energy from a hot stream to a cold one through a separating wall, so the two never mix — only their energy is exchanged. The hot stream gives up sensible heat and cools; the cold stream takes it up and warms. How much heat actually crosses depends on the two streams’ heat capacities and mass flows (which side can absorb or release more energy) and on how effectively the device is arranged: a counter-current layout, where the streams flow in opposite directions, extracts far more of the available temperature difference than a co-current one, where they flow together and approach a common temperature.

The practical measure is the exchange efficiency (effectiveness) — the fraction of the maximum thermodynamically possible heat transfer that the unit actually achieves. Set it high for a good counter-current exchanger, lower for co-current or a partially fouled one. With the two inlet temperatures, the mass flows, and the heat capacities, the efficiency fixes the outlet temperatures and the duty.

### The model

Dyssol Pro models the heat exchanger as a two-stream energy exchange: the two streams pass through without mixing — each outlet keeps its inlet stream’s mass and composition — and only energy crosses between them, at every time point of the flowsheet.

### Equipment this model can represent

- **Shell-and-tube exchangers**: Robust, high-pressure/temperature duty; one stream in tubes, the other in the shell.
- **Plate / plate-and-frame exchangers**: Compact, high-effectiveness, easy to clean.
- **Spiral and tubular exchangers**: For fouling or particle-laden streams.
- **Recuperators / economizers**: Recover heat from hot exhaust to preheat a feed.

### Typical engineering studies

- **Duty & outlet temperatures**: Predict outlet temperatures and heat duty for two streams at a chosen efficiency.
- **Heat recovery**: Connect a hot dryer or kiln exhaust to a cold feed and quantify recovered energy.
- **Co- vs. counter-current**: Compare arrangements by varying the exchange efficiency.
- **Heat-exchanger networks**: Build and study networks for overall energy efficiency in a flowsheet.
- **Performance matching**: Set the efficiency to match a known exchanger’s performance, then use it predictively.

### FAQ

**Q: How do I calculate heat duty for a solids process heat exchanger?**

A: Heat duty is the energy crossing per unit time, fixed by the streams’ mass flows and heat capacities and the achievable temperature approach. Dyssol Pro computes it directly from the two streams’ mass flows and heat capacities and your exchange efficiency, returning the duty and both outlet temperatures.

**Q: How can I improve heat recovery in a drying or calcination process?**

A: The standard move is to recover hot exhaust heat to preheat the incoming air or feed. In Dyssol Pro you connect the dryer or kiln exhaust to a heat exchanger against the cold feed, set the efficiency, and read off the recovered duty and the preheated-stream temperature.

**Q: Why is my heat exchanger fouling so quickly?**

A: Rapid fouling comes from deposition, scaling, or particle build-up on the surfaces, so it is limited by higher velocities, cleanable geometries, and treating the feed. Dyssol Pro computes the duty and outlet temperatures for a given effectiveness, so a measured drop shows up as a lower effective efficiency you can study across the process.

**Q: How do I choose between direct and indirect heating?**

A: Direct heating mixes a hot medium into the stream; indirect keeps them separate through a wall. Dyssol Pro’s heat exchanger is the indirect case (energy only, no mixing); a direct-contact arrangement would instead be modelled by mixing the streams, so the two are distinct units in the flowsheet.

**Q: How does particle deposition affect heat exchanger efficiency?**

A: Deposits add a thermal resistance that lowers the real heat transfer, i.e. the effectiveness. In Dyssol Pro you capture that by reducing the exchange efficiency, and it computes how the duty and outlet temperatures respond.

**Q: How can I reduce steam consumption in a heat exchanger?**

A: Steam (external heating) falls when more of the duty is met by recovered process heat. Dyssol Pro lets you add recovery exchangers and study how their efficiency and arrangement reduce the residual heating needed, trimming steam use.

**Q: What causes temperature fluctuations after a heat exchanger?**

A: Outlet temperature swings come from fluctuating inlet temperatures or flows on either side. In a dynamic flowsheet Dyssol Pro propagates those inlet variations through the energy balance to the outlet, so you can study how upstream upsets reach the exchanger outlet.

**Q: How do I size a heat exchanger for slurry heating?**

A: Sizing a slurry heater means finding the surface area from the required duty and a heat-transfer coefficient. Dyssol Pro computes that duty and both outlet temperatures for a target effectiveness, defining the load the area must be sized to deliver.

**Q: How can I prevent scaling in liquid heat exchangers?**

A: Scaling grows fastest at hot surfaces with hard water and low velocity, so it is limited by keeping wall temperatures down, maintaining turbulent flow, and treating the feed. Dyssol Pro computes the stream temperatures across the exchanger, so you can favor duties that keep surface temperatures below the scaling threshold.

**Q: How can I model heat transfer between gas, liquid, and solids?**

A: This is exactly the unit’s strength: it exchanges energy between two streams of any phase using their heat capacities and mass flows. In Dyssol Pro you connect the two streams, set the efficiency, and the energy balance gives the heat transferred and both outlet temperatures regardless of phase.

**Q: How do I optimize heat exchanger network energy efficiency?**

A: Network optimization (pinch analysis) maximizes internal heat recovery across many exchangers. Dyssol Pro lets you build the network of heat-exchanger units in the flowsheet, set their efficiencies, and study the overall recovery to find an energy-efficient arrangement.

**Q: Why is my heat exchanger outlet temperature lower than expected?**

A: A lower-than-expected outlet usually means the real effectiveness is below the design value — often fouling or a flow imbalance. Dyssol Pro lets you compare outlet temperatures at the assumed and a reduced efficiency, so you can infer the effectiveness the unit is actually achieving.

**Q: How does slurry viscosity affect heat exchanger design?**

A: Viscosity lowers the real heat transfer coefficient and thus the effectiveness, and raises pressure drop. In Dyssol Pro a more viscous slurry is represented by a lower efficiency, and it computes the resulting duty and outlet temperatures so you can see the process impact.

**Q: How can I reduce fouling in a slurry heat exchanger?**

A: Fouling is reduced by higher velocities, smoother surfaces, and cleanable geometries such as plate or spiral units. Dyssol Pro computes the duty and outlet temperatures for a given effectiveness, so you can quantify how a fouling-driven drop in efficiency plays through the process.

**Q: What causes thermal degradation in heated process streams?**

A: Degradation happens when a sensitive stream is taken above its temperature limit. Dyssol Pro computes the outlet temperatures, so you can choose stream pairings and efficiency that deliver the required heating while keeping the sensitive stream below its degradation threshold.

**Q: How do I calculate overall heat transfer coefficient?**

A: The overall heat transfer coefficient combines the film coefficients on each side and the wall resistance through standard correlations. Dyssol Pro computes the duty and both outlet temperatures the exchanger must deliver, which is exactly the load a coefficient-based sizing is designed to achieve.

**Q: How can I recover waste heat from dryer exhaust air?**

A: Dryer exhaust carries recoverable sensible heat. In Dyssol Pro you connect the exhaust stream to a heat exchanger against a cold inlet (e.g. fresh drying air), set the efficiency, and quantify the recovered heat and the preheat achieved.

**Q: How do I choose between shell-and-tube and plate heat exchangers?**

A: Plate units give higher effectiveness and easy cleaning; shell-and-tube handle higher pressures and fouling. Dyssol Pro models the energy exchange through the efficiency regardless of type, so you set the efficiency to match the candidate’s performance and compare the process outcomes.

**Q: How can I model transient heat exchanger behavior?**

A: Real transient behavior is shaped by the wall and internals storing thermal mass, so the outlet lags and smooths a sudden inlet change. Dyssol Pro’s dynamic flowsheet re-solves the energy balance at every time step as inlet temperatures and flows change, so you can study how upstream swings propagate to the outlet temperatures.

**Q: How do I design a heat exchanger for particle-laden gas?**

A: Particle-laden gas raises fouling and erosion concerns that drive the equipment choice, such as spiral or tubular geometries. Dyssol Pro treats the gas–solids stream’s heat capacity and mass flow and computes the duty and both outlet temperatures, so you can pin down the thermal load the design must meet.

---

## Fluidized Bed Dryer

URL: https://www.dyssoltec.com/drying/fluidized-bed-dryer/ (German: https://www.dyssoltec.com/de/drying/fluidized-bed-dryer/)

Fluidized bed dryer simulation in Dyssol Pro: a dynamic two-phase model predicting size-dependent moisture and temperature over a two-stage drying curve.

Fluidize a bed of moist particles in hot gas and predict size-dependent moisture and temperature over time — inside a connected dynamic flowsheet.

### How it works

In a fluidized bed, an upward gas stream suspends the particles so the bed behaves like a boiling liquid — intense particle motion gives excellent gas–solid contact and very uniform temperature. Each particle is wetted with liquid; the hot gas supplies heat that evaporates that liquid from the particle surface into the gas. While the surface stays wet, drying runs at a constant rate set by the heat and mass transfer between gas and particle.

Once the surface moisture falls below a critical value, drying slows: internal moisture transport now limits the rate, and the rate tapers toward an equilibrium moisture the particle can’t dry below at the given gas humidity. Because fine particles can be carried out of the bed by the gas (elutriation), the dryer also separates: small particles leave with the exhaust while the bed retains and discharges the product over a weir. The whole process is dynamic — bed mass, moisture, and temperature evolve in time toward steady operation.

### The model

Dyssol Pro models the fluidized-bed dryer dynamically with two ideally-mixed phases — a solid phase carrying the particles and their moisture, resolved per particle size class, and a gas phase carrying the evaporated vapor — coupling their mass and heat balances at every time point of the flowsheet, resolving how moisture and temperature develop across the particle size distribution.

### Equipment this model can represent

- **Continuous well-mixed FB dryers**: A back-mixed bed with continuous feed and weir overflow discharge.
- **Plug-flow / vibrated FB dryers**: Long beds giving a narrower residence-time distribution.
- **Batch fluidized-bed dryers**: Charge-and-dry units common in pharma.
- **Spouted beds**: For coarse, sticky, or irregular particles that don’t fluidize smoothly.

### Typical engineering studies

- **Product moisture & temperature**: Predict product moisture and temperature dynamically for given inlet gas conditions.
- **Drying-rate studies**: Study inlet air temperature, gas flow, and bed height against drying rate and final moisture.
- **Elutriation & fines recovery**: Quantify elutriation losses and couple a cyclone/gas filter downstream to recover fines.
- **Transient operation**: Investigate startup, feed disturbances, and the approach to steady state.
- **Calibration & scale-up**: Calibrate the drying-curve parameters to lab data, then scale up.

### Example: Continuous vibrated fluidized-bed drying

A dynamic model for continuous vibrated fluidized-bed dryers was implemented in Dyssol Pro and validated across materials, geometries, and vibration settings.

### FAQ

**Q: How to avoid overdrying in a fluidized bed dryer?**

A: Overdrying wastes energy and can damage product, so you target the equilibrium-moisture plateau and stop there. Dyssol Pro tracks the bed’s moisture dynamically against the critical and equilibrium moisture, so you can tune inlet temperature, gas flow, and residence to hit the target moisture without driving past it.

**Q: Why are particles sticking together in my fluidized bed dryer?**

A: Stickiness arises when surface moisture or temperature crosses a material’s sticky point. Dyssol Pro tracks surface moisture and temperature per size class, so you can study operating points that keep them out of the sticky regime.

**Q: How can I reduce energy consumption in fluidized bed drying?**

A: Energy falls if you avoid overdrying and recover exhaust heat, using the minimum air and temperature that meet the moisture target. Dyssol Pro’s heat and mass balances let you study inlet temperature and gas flow against final moisture and exhaust humidity to find the lean operating point.

**Q: What causes uneven drying in a fluidized bed?**

A: Uneven drying comes from poor fluidization, channeling, or a wide residence-time spread. Dyssol Pro models a well-mixed bed with size-resolved moisture, so it shows how size classes dry at different rates and how residence time sets the spread.

**Q: How do inlet air temperature and air velocity affect drying rate?**

A: Higher inlet temperature raises the driving force and air velocity raises heat/mass transfer — both speed drying, up to entrainment limits. Dyssol Pro takes both as inputs to the transfer correlations, so you can map drying rate and final moisture against them directly.

**Q: How can I prevent product attrition in a fluidized bed dryer?**

A: Attrition is mechanical breakage from particle collisions, worsened by vigorous fluidization at high gas velocity, so it is limited by drying at the lowest gas velocity and residence that still meet the duty. Dyssol Pro computes the gas velocity and residence an operating point needs, so you can steer toward the gentler settings; where attrition must be quantified, a dedicated breakage unit represents it in the same flowsheet.

**Q: How do I determine the minimum fluidization velocity?**

A: Minimum fluidization velocity follows from a force balance on the bed — the classic Ergun-type correlation using particle size and density and the gas density and viscosity. Dyssol Pro tracks the particle size distribution, solids density, and gas properties in the stream, so you have the inputs that correlation needs to set the operating gas velocity above minimum fluidization.

**Q: Why is my fluidized bed dryer producing too much dust?**

A: Dust is fines elutriated out of the bed with the exhaust. Dyssol Pro models elutriation with a size-dependent grade efficiency, so you can study how gas velocity and the feed’s fine fraction drive the loss and size a downstream cyclone or filter to recover it.

**Q: How can I control final product moisture content?**

A: Final moisture is set by the balance of heat input, residence, and exhaust humidity against the equilibrium moisture. Dyssol Pro predicts it dynamically, so you can study which combination of inlet temperature, gas flow, and bed (weir) height holds the product on target.

**Q: How do I model heat and mass transfer in a fluidized bed dryer?**

A: This is the core of the unit: convective heat and mass transfer between gas and particles, coupled to a two-stage drying curve. In Dyssol Pro you set the geometry and material moisture parameters and it solves the coupled balances dynamically.

**Q: How can I avoid product overheating in a fluidized bed dryer?**

A: While the surface is wet, evaporative cooling holds particle temperature down; overheating risk rises once the product dries out. Dyssol Pro tracks particle temperature and moisture per size class, so you can find the inlet temperature and residence that finish drying without overheating the product.

**Q: Why does my fluidized bed collapse during drying?**

A: Bed collapse (defluidization) is a hydrodynamic failure, often from stickiness or too-low gas velocity. Dyssol Pro tracks the surface moisture and temperature that precede sticky defluidization, so you can steer the drying conditions that keep the bed safely fluidized.

**Q: How do I prevent channeling in a fluidized bed dryer?**

A: Channeling is uneven gas distribution, where gas finds preferential paths instead of fluidizing the whole bed. It is prevented by a well-designed distributor plate with adequate pressure drop, keeping the gas velocity comfortably above minimum fluidization, and avoiding overwet, cohesive material that resists fluidization.

**Q: How does particle size distribution affect fluidization quality?**

A: A wide PSD fluidizes differently — fines elutriate while coarse particles need more gas. Dyssol Pro resolves drying and elutriation per size class, so you see how the PSD affects fines loss and size-dependent drying.

**Q: What causes agglomeration during fluidized bed drying?**

A: Agglomeration occurs when wet particle surfaces bridge and bind together. Dyssol Pro tracks the surface moisture that drives that tendency, and where agglomeration must be quantified a dedicated agglomeration or granulation unit represents it in the same flowsheet.

**Q: How can I improve drying uniformity across the bed?**

A: Uniformity comes from good mixing and a narrow residence-time spread. Dyssol Pro assumes a well-mixed bed and shows size-resolved drying within it, so you can study how bed height and throughput set residence and even out the drying.

**Q: How do I optimize exhaust air humidity in drying?**

A: Exhaust humidity reflects how fully you’ve used the air’s drying capacity — higher humidity means leaner air use but slower final drying. Dyssol Pro computes exhaust humidity and temperature, so you can optimize gas flow and inlet temperature to balance energy use against drying rate.

**Q: How can I reduce elutriation of fine particles?**

A: Elutriation falls with lower gas velocity and fewer fines in the feed. Dyssol Pro’s elutriation model quantifies the loss against gas velocity and feed PSD, so you can find a velocity that still fluidizes the bed while cutting fines carryover.

**Q: How do I scale up a fluidized bed dryer?**

A: Scale-up transfers the material drying parameters and the heat/mass transfer basis to a larger bed and gas flow. Dyssol Pro lets you fit those at lab scale and run the model at production geometry and throughput to check moisture and energy before building.

**Q: How can I use PAT sensors to control fluidized bed drying?**

A: PAT (e.g. NIR moisture, bed temperature) is an instrumentation-and-control layer. Dyssol Pro complements it by predicting the moisture and temperature trajectories the sensors should see, providing a model basis for control strategies and soft sensors.

---

## Rotary Kiln

URL: https://www.dyssoltec.com/drying/rotary-kiln/ (German: https://www.dyssoltec.com/de/drying/rotary-kiln/)

Rotary kiln simulation in Dyssol Pro: a compartmented counter-current gas–solid model with Arrhenius kinetics and convection/radiation heat transfer.

Resolve the solids-bed and gas temperature profiles and the gas–solid reaction conversion along a counter-current kiln — inside a connected dynamic flowsheet.

### How it works

Calcination is a high-temperature treatment that drives a chemical change in a solid — classically the thermal decomposition of a carbonate (e.g. limestone → lime + CO₂), but also dehydration, phase change, or oxidation. In a rotary kiln the solids form a bed that tumbles as the inclined cylinder rotates and travels slowly toward the discharge, while a hot gas flows counter-current over the bed. Heat reaches the solids three ways: convection from the gas, radiation from the gas and the hot refractory wall, and conduction from the wall the bed rides over (the wall regenerates heat as it rotates from the gas side to the solids side).

The reaction itself is endothermic and surface-controlled — it proceeds where the bed is hot enough and the reactant is exposed, so conversion builds up along the kiln. The key controls are temperature and residence time: the solid must stay hot enough, long enough, for the reaction to complete without overburning. Residence time is set by the kiln rotation, slope, and fill, while the temperature profile is set by the firing and heat transfer.

### The model

Dyssol Pro models the rotary kiln dynamically by dividing it into a series of compartments, each carrying a gas, a solid, and a wall phase, with gas and solids moving counter-current — the solids travel and back-mix along the kiln to set their residence time, at every time point of the flowsheet.

### Equipment this model can represent

- **Directly-fired rotary kilns**: Combustion gases contact the bed (cement, lime).
- **Indirectly-heated rotary kilns**: Heat through the wall, keeping product clean (specialty chemicals, catalysts).
- **Rotary calciners with flights/lifters**: Internal flights improve bed mixing and gas–solid contact.
- **Multi-zone kilns**: Staged temperature profiles for preheat, reaction, and soak.

### Typical engineering studies

- **Temperature & conversion profiles**: Predict the kiln temperature profile and conversion for given firing and feed.
- **Residence-time studies**: Study solids velocity and back-mixing against conversion and product quality.
- **Disturbance & control**: Investigate feed-rate and temperature disturbances dynamically and design stabilizing control.
- **Kinetics calibration**: Calibrate the reaction kinetics and heat/enthalpy constants to plant data, then explore operating points.
- **Flowsheet coupling**: Couple to upstream/downstream units (preheater, cooler, gas cleaning) in one flowsheet.

### Example: Industrial zeolite production

End-to-end catalyst process with synthesis, decanter washing/concentration, spray drying, and two-stage rotary-kiln calcination. Dyssol Pro connected surrogate synthesis models with dynamic downstream units in one flowsheet.

### FAQ

**Q: How do I optimize temperature profile in a rotary kiln?**

A: You shape the profile through firing rate, gas flow, and the heat-transfer path so the bed reaches reaction temperature and holds it without overburning. Dyssol Pro resolves the gas, solid, and wall temperature profiles along the compartments, so you can study how firing and flow move them and find a profile that completes conversion efficiently.

**Q: What causes incomplete calcination in a rotary kiln?**

A: Incomplete calcination means too low a bed temperature or too short a residence for the reaction to finish. Dyssol Pro computes conversion from Arrhenius kinetics coupled to the temperature profile and residence, so you can study which of temperature or residence is limiting and correct it.

**Q: How can I reduce energy consumption in calcination?**

A: Energy falls with better heat recovery and by not overheating beyond what the reaction needs. Dyssol Pro’s coupled heat balances let you study firing rate and gas flow against conversion, finding the minimum thermal input that still completes the calcination — and you can add heat-recovery units in the flowsheet.

**Q: How does residence time affect product quality in a rotary kiln?**

A: Longer residence raises conversion but risks overburning; too short leaves unreacted core. Dyssol Pro takes the solids velocity and back-mixing as parameters, so you can study how residence shifts conversion and the temperature the product experiences.

**Q: What are typical heat transfer mechanisms in rotary kiln calcination?**

A: Convection from the gas, radiation from gas and wall, and conduction from the wall the bed rides on (with wall regeneration). Dyssol Pro models exactly this combination of convective and radiative transfer plus wall conduction, so you can study which mechanism dominates and how to enhance it.

**Q: How do I avoid ring formation in a rotary kiln?**

A: Rings form from partial melting and deposition on the wall, so they are limited by keeping wall and bed temperatures out of the sticky range where material softens and adheres. Dyssol Pro computes the wall and bed temperatures along the kiln, so you can steer toward operating points that stay below that range.

**Q: What causes dust carryover from a rotary kiln?**

A: Dust carryover is fine solids entrained by the counter-current gas, so it is limited by keeping the gas velocity moderate and capturing what escapes downstream. Dyssol Pro computes the gas flow through the kiln and lets you couple a downstream cyclone or gas filter in the flowsheet to capture and quantify the carryover.

**Q: How can I model gas-solid reactions in a calciner?**

A: This is core to the unit: Arrhenius-rate gas–solid reactions with stoichiometry, coupled to the compound mass and enthalpy balances. In Dyssol Pro you define the reaction kinetics and the model returns conversion and heat effects along the kiln.

**Q: How do kiln speed and inclination affect material residence time?**

A: Speed and slope set how fast the bed travels and therefore residence — physically through bed transport. Dyssol Pro parameterizes residence through the solids axial velocity and the degree of back-mixing, so you study residence directly by setting that velocity and mapping it to your kiln’s speed and slope.

**Q: How can I control product particle size after calcination?**

A: Particle size after calcination is driven by decrepitation and sintering during the heat treatment, so it follows from the temperature and conversion history the solid experiences. Dyssol Pro computes that temperature and conversion history along the kiln, and you can chain a downstream breakage or agglomeration unit to resolve the resulting size change.

**Q: How can I prevent overburning in a rotary kiln?**

A: Overburning is excess time at too high a temperature, degrading product. Dyssol Pro tracks the temperature the bed experiences along its residence, so you can find firing and residence settings that complete the reaction while keeping peak bed temperature below the overburning threshold.

**Q: Why is product quality varying along the kiln discharge?**

A: Quality variation reflects an uneven temperature or conversion profile, or transient upsets. Dyssol Pro resolves conversion and temperature per compartment and runs dynamically, so you can localize where the profile falls short and how disturbances propagate to the discharge.

**Q: How do I determine the correct kiln residence time?**

A: The needed residence is the time at temperature for the reaction to reach target conversion. Dyssol Pro couples kinetics to the temperature profile, so you can find the residence (via solids velocity) that achieves the conversion, then map it to kiln speed and slope.

**Q: What causes coating buildup inside a rotary kiln?**

A: Coating builds from partially reacted, sticky material adhering to the wall, so it is limited by keeping wall and bed temperatures out of the regime where material softens and sticks. Dyssol Pro computes the wall and bed temperatures behind it, so you can study operating conditions that avoid the sticky regime.

**Q: How does feed moisture affect calcination efficiency?**

A: Feed moisture consumes heat to evaporate before calcination can proceed, lowering efficiency. Dyssol Pro’s enthalpy balances account for the heat demand of the feed, so you can study how moisture shifts the temperature profile and the firing needed — pre-drying can be added upstream in the flowsheet.

**Q: How can I improve heat transfer in a rotary kiln?**

A: Heat transfer improves with higher gas velocity, more radiating surface, and better bed mixing. Dyssol Pro models convective and radiative transfer and their dependence on the operating conditions, so you can study which lever most raises the heat reaching the bed.

**Q: How do I reduce emissions from a calcination kiln?**

A: Emissions such as CO₂, dust, and NOx come from the reaction and the combustion. Dyssol Pro computes the reaction gases, so the process CO₂ and dust loads are quantified, and you can couple gas-cleaning units downstream in the flowsheet.

**Q: What is the effect of kiln fill degree on conversion?**

A: Fill degree sets the bed cross-section, the exposed surface, and the heat-transfer areas. Dyssol Pro computes the bed geometry (central angle, surfaces) from the holdup, so you can study how fill changes heat transfer and therefore conversion.

**Q: How can I model particle temperature in a rotary kiln?**

A: The solid-phase temperature is a primary model output, computed from the enthalpy balance with convective, radiative, and wall-conduction heat inputs. In Dyssol Pro you read the solids temperature profile along the kiln directly.

**Q: How do I stabilize rotary kiln operation during feed fluctuations?**

A: Feed swings disturb the temperature and conversion profiles, and kilns have long thermal lags. Dyssol Pro is dynamic, so you can impose feed fluctuations and test firing/feed control strategies that keep conversion and discharge temperature stable.

---

## Roller Compactor

URL: https://www.dyssoltec.com/granulation/roller-compactor/ (German: https://www.dyssoltec.com/de/granulation/roller-compactor/)

Roller compactor simulation in Dyssol Pro: a rolling-theory model computing nip angle, ribbon porosity, and throughput for dry granulation.

Compact powder into ribbon between counter-rotating rolls — predicting nip angle, ribbon porosity, and throughput for dry granulation — inside a connected flowsheet.

### How it works

Roller compaction is dry granulation: powder is forced into the converging gap between two counter-rotating rolls and squeezed into a coherent solid ribbon (or flake), with no liquid binder. As powder is drawn in, it first slips, then — past the nip angle — it is gripped by both rolls and compacted as the gap narrows, the particles rearranging and bonding under pressure into a low-porosity ribbon. The achievable compaction depends on the powder’s compressibility and friction and on the roll force and gap.

Because the rolls are rigid cylinders, the pressure is not uniform across the ribbon width: the center is compacted more than the edges, giving a U-shaped porosity profile (denser middle, more porous edges). That porosity distribution matters, because the ribbon is afterwards milled into granules — denser ribbon gives stronger, coarser granules with fewer fines, while the porous edges tend to crumble. So the ribbon’s density and its uniformity across the width set the downstream granule quality.

### The model

Dyssol Pro models the roller compactor from rolling theory: it finds the nip angle — where the powder stops slipping and is gripped by both rolls — from the powder’s internal and wall friction and the roll geometry, and from there the compaction the powder undergoes as the gap narrows, at every operating point of the flowsheet.

### Equipment this model can represent

- **Smooth / knurled / pocketed rolls**: Surface texture aids powder grip and de-aeration.
- **Screw-fed compactors**: A feed screw forces powder into the nip and de-aerates it.
- **Vacuum-deaeration compactors**: Remove entrained air for denser, more uniform ribbon.
- **Integrated compactor–mill systems**: Ribbon is granulated in line to the target size.

### Typical engineering studies

- **Ribbon porosity prediction**: Predict ribbon porosity (and its across-width profile) for a given force, gap, and powder.
- **Force & gap studies**: Study specific compaction force and roll gap against ribbon density and uniformity.
- **Ribbon → granule milling**: Feed the ribbon porosity to a downstream mill/screen to study the resulting granule PSD and fines.
- **Calibration & scale-up**: Calibrate compressibility and friction parameters to compaction data, then scale up.
- **Throughput studies**: Investigate throughput (RPS) versus roll geometry and feed rate.

### FAQ

**Q: How does roller compaction improve powder flowability?**

A: It densifies fine, cohesive powder into ribbon that is then milled into larger, free-flowing granules with fewer fines. Dyssol Pro predicts the ribbon density and porosity distribution that govern the downstream granule size, so you can target a compaction that yields flowable granules after milling.

**Q: Why are ribbons breaking in my roller compactor?**

A: Ribbon breakage and crumbling come from low or uneven density, especially at the porous edges. Dyssol Pro computes the U-shaped porosity profile, so you can study how force and gap raise the minimum density and flatten the profile to make the ribbon more coherent.

**Q: How can I control flake density in roller compaction?**

A: Flake (ribbon) density is set mainly by the specific compaction force, the roll gap, and the powder’s compressibility. Dyssol Pro relates these directly to the minimum ribbon porosity, so you can study how force and gap move the density to target.

**Q: What causes too many fines after roller compaction?**

A: Fines come from under-compacted ribbon (often the porous edges) that crumbles in milling. Dyssol Pro predicts the porosity profile and its weakest regions, so you can study how to raise and even out the density, then feed the result to a mill model to quantify the fines.

**Q: How do roll pressure and roll gap affect granule quality?**

A: Higher specific force and a tighter gap give denser ribbon and therefore stronger, coarser granules; the nip angle shifts with them. Dyssol Pro computes the nip angle and ribbon porosity from force and gap, so you can map them to ribbon density and, via milling, to granule quality.

**Q: How can I prevent powder leakage at the roller sides?**

A: Side leakage, and the soft porous edges it produces, is controlled by cheek plates or rim rolls that seal the ends of the nip. Dyssol Pro computes the across-width porosity profile, so you can see how pronounced those weak edges are and target a compaction that strengthens them.

**Q: How does feed screw speed affect roller compaction performance?**

A: Feed screw speed sets how much powder is delivered (and pre-compacted) into the nip, affecting ribbon density and throughput. Dyssol Pro relates the feed and roll speed (RPS) to the volume flux and density, so you can study the feed-to-roll balance.

**Q: How do I choose between dry granulation and wet granulation?**

A: Dry granulation (roller compaction) suits moisture- or heat-sensitive materials and avoids a drying step; wet granulation gives stronger, denser granules for poorly bonding powders. Dyssol Pro models both routes (this unit for dry, the granulators for wet), so you can compare the resulting granule properties for your material.

**Q: How can I scale up roller compaction from pilot to production?**

A: Scale-up transfers the powder’s compressibility and friction parameters and matches specific compaction force at larger roll geometry. Dyssol Pro lets you calibrate those parameters at pilot scale and run the model at production roll dimensions to predict ribbon density before commissioning.

**Q: How can I model compaction and breakage in roller compaction?**

A: Compaction densifies the powder into a coherent ribbon through nip-angle-driven pressing between the rolls; breakage is the separate downstream step of reducing that ribbon to granules by shear and impact, typically in a mill with a screen limiting the top size. Dyssol Pro models the compaction explicitly — nip angle and ribbon porosity profile — and you chain a mill/crusher unit after it in the flowsheet to capture the breakage and the resulting granule size distribution.

**Q: How can I improve ribbon uniformity in roller compaction?**

A: Uniformity means flattening the U-shaped density profile across the width. Dyssol Pro computes that profile, so you can study how force, gap, and feed reduce the center-to-edge density difference and produce more uniform ribbon.

**Q: Why is my roller compactor producing inconsistent granules?**

A: Inconsistency traces to variable ribbon density from fluctuating force, gap, or feed. Dyssol Pro lets you study how those inputs move the ribbon porosity, identifying which to control for consistent ribbon (and therefore granules).

**Q: How does roll speed affect compact strength?**

A: Higher roll speed shortens the dwell under pressure and reduces de-aeration time, tending to lower density and strength. Dyssol Pro relates roll speed (RPS), feed, and geometry to the volume flux and density, so you can study the speed–density trade-off.

**Q: How can I reduce material sticking to compaction rolls?**

A: Roll sticking depends on powder adhesion, the roll surface, and lubrication. It is reduced by texturing or coating the rolls, adjusting the formulation or adding a lubricant, and controlling humidity so the powder is less prone to adhere.

**Q: What causes lamination or cracking in roller-compacted ribbons?**

A: Lamination comes from entrained air and stress relaxation as the ribbon exits, so it is limited by de-aerating the feed and producing a denser, more uniform ribbon that resists cracking. Dyssol Pro predicts the ribbon porosity, so you can favour a compaction that raises the density and reduces the tendency to laminate.

**Q: How do I optimize milling after roller compaction?**

A: Milling turns ribbon into granules, and its result depends on the ribbon density you feed it. Dyssol Pro passes the ribbon porosity to a downstream mill/screen model, so you can optimize the mill settings against the ribbon to hit the target granule PSD with minimal fines.

**Q: How does powder compressibility affect roller compaction?**

A: Compressibility governs how much density you gain per unit force — central to the result. Dyssol Pro takes compressibility as a model parameter in the porosity calculation, so you can study how a more or less compressible powder changes the achievable ribbon density.

**Q: How can I control bulk density after dry granulation?**

A: Final bulk density follows from the ribbon density and the milling. Dyssol Pro predicts the ribbon porosity and, through the downstream mill, the granule properties, so you can steer the compaction and milling to a target bulk density.

**Q: How do I monitor ribbon density inline?**

A: Inline density monitoring (e.g. NIR, thickness/force sensors) is an instrumentation task. Dyssol Pro predicts the ribbon density and its profile, providing a model baseline that inline measurements can be compared against for control.

**Q: How can I model pressure distribution in a roller compactor?**

A: The model captures the pressure-driven compaction through the nip-angle solution and the resulting across-width porosity profile (the U-shape). In Dyssol Pro you obtain the ribbon porosity distribution that the pressure produces, which is the practically relevant output.

---

## Decanter Centrifuge

URL: https://www.dyssoltec.com/classification/decanter-centrifuge/ (German: https://www.dyssoltec.com/de/classification/decanter-centrifuge/)

Decanter centrifuge simulation in Dyssol Pro: a dynamic two-zone settling model predicting centrate clarity and compressible cake build-up.

Separate solids from liquid continuously — resolving centrate clarity, cake solids, and the transient cake build-up over time — inside a connected dynamic flowsheet.

### How it works

A decanter centrifuge is a horizontal rotating bowl with a co-rotating screw conveyor (scroll) turning at a slightly different speed. Slurry is fed into the bowl, where the centrifugal field — many times gravity — drives the denser solid particles outward to the bowl wall, where they accumulate as a liquid-saturated sediment. The clarified liquid forms a rotating annular pond and flows toward the overflow weir, while the screw, turning at a small differential speed relative to the bowl, scrapes the sediment along the wall toward the conical end and lifts it out of the pond, where it drains further before discharge.

Two things therefore happen at once and interact: sedimentation of particles out of the flowing slurry, set by bowl speed, particle size, and density difference; and sediment build-up and transport, where the cake compacts (a compressible, hindered-settling material) and is conveyed out. Capture of fine particles depends on the centrifugal force and the residence time in the pond; cake dryness depends on how long the sediment is worked and compacted before it leaves. This is an inherently dynamic, transient process — the cake builds up over time toward a steady state.

### The model

Dyssol Pro models the decanter dynamically at the population level: it splits the machine into two coupled zones — a sedimentation zone and a sediment zone — and solves the unsteady mass and volume balances, so it resolves transient cake build-up and the approach to steady state rather than just a static split, at every time point of the flowsheet.

### Equipment this model can represent

- **Counter-current decanters**: Slurry and sediment move in opposite directions (the classic configuration this model represents).
- **Co-current decanters**: Feed and sediment move the same way, gentler on flocs.
- **High-G / fine-bowl decanters**: Long, slender bowls at high speed for fine-particle clarification.
- **Three-phase (tricanter) decanters**: Separate two liquids plus solids simultaneously.

### Typical engineering studies

- **Centrate & cake prediction**: Predict residual solids and PSD in the centrate, and cake solids for a given decanter setting and feed, including the transient.
- **Speed & pond-depth studies**: Study bowl speed, differential speed, weir/pool depth, and feed flow against centrate solids and cake solids.
- **Dynamic upsets**: Study feed-solids upsets, startup, and the approach to steady cake build-up.
- **Calibration & scale-up**: Calibrate settling, cake transport, and sediment-compression parameters to measured performance, then support validated scale-up or transfer to new feeds.
- **Flowsheet coupling**: Couple the decanter to upstream thickening and downstream cake-handling units in one flowsheet.

### Example: Industrial zeolite production

End-to-end catalyst process with synthesis, decanter washing/concentration, spray drying, and two-stage rotary-kiln calcination. Dyssol Pro connected surrogate synthesis models with dynamic downstream units in one flowsheet.

### FAQ

**Q: How does a decanter centrifuge separate solids from liquid?**

A: A rotating bowl drives denser solids to the wall as a sediment while clarified liquid overflows a weir, and a screw turning at a small differential speed conveys the cake out of the pond. Dyssol Pro models exactly this with coupled sedimentation and sediment-transport zones, resolved over time.

**Q: Why is my decanter centrifuge producing wet solids?**

A: Wet cake means too little compaction or residence in the sediment zone — often too high a feed rate or too low a differential speed. Dyssol Pro models the compressible, liquid-saturated cake build-up, so you can predict cake solids and tune differential speed and flow to dry it.

**Q: How can I improve clarification efficiency in a decanter?**

A: Clarity improves with higher bowl speed, lower throughput, and a deeper pond for more residence. In Dyssol Pro these are model parameters, so you study centrate clarity against bowl speed, flow, and weir radius to find the right setting.

**Q: What causes high solids carryover in the centrate?**

A: Fine particles that don’t settle within the pond residence escape with the centrate. Dyssol Pro’s size-resolved grade efficiency shows which fines escape, so you can study how more bowl speed or less flow captures them.

**Q: How do bowl speed and differential speed affect separation?**

A: Bowl speed sets the centrifugal force (and thus capture and clarity); differential speed sets conveying rate and cake residence (and thus dryness). Dyssol Pro takes both as parameters and models their distinct effects, so you can balance clarity against cake dryness explicitly.

**Q: How can I reduce polymer consumption in centrifuge operation?**

A: Polymer flocculates fines into larger, faster-settling aggregates. Dyssol Pro represents its effect through a coarser effective feed PSD, so you can study how much aggregation is actually needed for target capture and aim for the minimum dose.

**Q: What parameters influence cake dryness in a decanter centrifuge?**

A: Cake dryness is governed by residence and compaction in the sediment zone — differential speed, feed flow, and the compressibility of the solids. Dyssol Pro’s dynamic sediment-zone model predicts cake solids as a function of those settings.

**Q: How do I size a decanter centrifuge for slurry treatment?**

A: Sizing balances throughput against required clarity and cake dryness. In Dyssol Pro you run the model at the feed conditions and read centrate and cake, giving you the duty an operating point must meet.

**Q: How can I optimize decanter operation for changing feed solids?**

A: Robust operation under changing feed solids means picking bowl speed, differential speed, and flow with enough margin that cake compaction and clarification still meet spec across the expected concentration swings, rather than tuning to the average feed alone. Dyssol Pro’s dynamic model lets you impose those feed-concentration transients and watch cake and centrate respond, so you can find the settings that hold up across the whole range before committing them to the plant.

**Q: Why does my decanter cake quality change during operation?**

A: Cake quality evolves as the sediment builds up toward steady state and with feed variation. Dyssol Pro is a transient model, so it shows that cake build-up over time and helps you tell a normal approach-to-steady-state from a genuine upset.

**Q: How do I reduce wear in a decanter centrifuge?**

A: Wear is driven by abrasive solids at high bowl speed, so it is limited by running at the lowest speed and solids load that still meet the separation duty. Dyssol Pro computes the speed and load an operating point needs, so you can steer toward the gentler settings.

**Q: How does feed particle size affect decanter performance?**

A: Finer feed is harder to capture and tends to escape in the centrate. Dyssol Pro resolves the PSD and computes a size-dependent grade efficiency, so you see directly how feed fineness shifts clarity and recovery.

**Q: How can I improve solids recovery in a decanter?**

A: Recovery improves with more centrifugal force and residence — higher bowl speed, lower flow. In Dyssol Pro you study recovery against those settings and the feed PSD to find the operating point that captures the required fraction.

**Q: What causes foaming in centrifuge operation?**

A: Foaming comes from surfactants and entrained air in the feed forming stable gas–liquid films. It is controlled by adding antifoam agents, reducing air entrainment at the feed inlet, and de-aerating the slurry before it enters the bowl.

**Q: How do I optimize pond depth in a decanter centrifuge?**

A: A deeper pond gives more clarification residence but a shorter drying beach, trading clarity against cake dryness. Dyssol Pro takes the weir radius (pond depth) as a parameter, so you can study that trade-off and pick the depth that meets both targets.

**Q: What is the effect of feed flow rate on cake dryness?**

A: Higher feed flow shortens residence, giving a wetter cake and poorer clarity. Dyssol Pro lets you vary the feed flow and read cake solids and centrate clarity off the dynamic model to set the throughput.

**Q: How can I reduce torque overload in a decanter?**

A: Torque overload comes from too much cake load on the screw. Dyssol Pro models the cake build-up that drives torque, so you can avoid the feed-rate and differential-speed combinations that let cake accumulate and overload the screw.

**Q: How do I troubleshoot poor liquid clarity after centrifugation?**

A: Poor clarity means fines are escaping the pond. In Dyssol Pro you study which size classes leave in the centrate against bowl speed and flow, which localizes whether the cause is insufficient force, too much throughput, or a finer feed.

**Q: How can I model sedimentation and transport in a decanter centrifuge?**

A: This is exactly the unit: a dynamic model with a sedimentation zone (time-dependent, size-resolved capture) coupled to a sediment zone (compressible cake build-up and screw transport), giving centrate clarity and cake solids over time inside the flowsheet.

---

## Granulator

URL: https://www.dyssoltec.com/granulation/granulator/ (German: https://www.dyssoltec.com/de/granulation/granulator/)

Granulator simulation in Dyssol Pro: population-balance prediction of particle size for batch and continuous fluidized-bed layering granulation.

Grow particles by spraying suspension onto a fluidized bed — batch and continuous — resolving the full particle size distribution by population balance inside a connected flowsheet.

### How it works

In fluidized-bed spray granulation, seed particles (nuclei) are kept fluidized by a gas stream while a liquid suspension is sprayed onto them. The liquid spreads over the particle surfaces and the solvent evaporates, leaving a thin solid shell — so each pass through the spray adds a layer and the particle grows. This layering mechanism makes growth roughly proportional to the available surface area: the more total particle surface in the bed, the thinner each layer.

The two operating modes differ in how the bed is managed. In continuous operation, fresh nuclei enter and grown product is withdrawn, so the bed reaches a steady size distribution set by the balance of spray rate, nuclei feed, and product withdrawal. In batch operation no product is withdrawn, so the whole size distribution shifts upward over time and the total solid mass in the bed increases, while total solid mass is conserved.

Not all sprayed material lands on particles — a fraction (overspray) dries in flight and leaves as dust. The practical challenge in both modes is to grow granules to target size and strength without overwetting or defluidizing the bed. In high-shear granulators — a different mechanism — growth is dominated by coalescence under impeller shear; that route is better represented by the agglomerator.

### The model

Dyssol Pro models fluidized-bed layering granulation in both continuous and batch operation: it solves a population balance in which sprayed solids deposit over the total particle surface area to grow the granules, with an overspray fraction reporting to dust and a moisture balance setting the liquid leaving with the product, at every time point of the flowsheet.

### Equipment this model can represent

- **Continuous FB granulators**: Steady spray-on-fluidized-bed layering with continuous product draw.
- **Batch FB granulators**: Spray-on-fluidized-bed layering of a fixed charge.
- **Spouted-bed granulators**: For coarse or sticky granules.
- **Wurster-type coaters**: Bottom-spray layering for uniform shells and pellets.

### Typical engineering studies

- **Product PSD prediction**: Predict the steady-state product PSD (continuous) or the PSD-versus-time growth curve and endpoint (batch).
- **Start-up & transients**: Study start-up, feed fluctuations, and the approach to steady state dynamically.
- **Granulation circuits**: Couple with screens/mills and recycle to study size control and recycle load.
- **Dust quantification**: Quantify dust (overspray) losses and couple a downstream cyclone/filter.
- **Sensitivity & scale-up**: Run sensitivity/DoE on spray rate, charge, and seed PSD, then calibrate and scale up from pilot to commercial throughput.

### FAQ

**Q: How do I determine the endpoint of a batch granulation process?**

A: The endpoint is when the granules reach target size (and strength), which for layering corresponds to a spray duration. Dyssol Pro models the PSD growth over time, so you can read off the spray time that reaches the target size and use that as a model-based endpoint, before refining it experimentally.

**Q: Why is my batch granulator producing inconsistent granules?**

A: Inconsistency usually traces to variable seed PSD, spray rate, or wetting between runs. Dyssol Pro lets you vary those inputs and see how sensitively the product PSD responds, pinpointing which to control tightest for reproducibility.

**Q: How does liquid addition rate affect batch granulation?**

A: The spray (liquid) rate sets how fast solids are deposited and how wet the bed gets — too fast risks overwetting. Dyssol Pro couples the deposited-solids growth to the spray rate, so you can study how it drives the growth trajectory and final size.

**Q: How can I avoid overwetting in batch granulation?**

A: Overwetting is avoided by keeping spray rate below the bed’s drying capacity. Dyssol Pro tracks the solids growth and the liquid leaving via exhaust, so you can study spray rates that keep the bed within a safe wetting balance.

**Q: What causes large lumps in a high-shear granulator?**

A: Lumps come from localized overwetting and uncontrolled coalescence under shear, so they are controlled by evening out wetting and capping the liquid input. In Dyssol Pro the coalescence-driven growth is captured with the agglomerator’s kernel model, so you can study the operating points that keep granules on-size.

**Q: How do impeller and chopper speed affect granule size?**

A: Impeller and chopper speed are high-shear variables that drive coalescence and breakage, raising collision frequency until breakage balances growth, so size peaks at an optimum. In Dyssol Pro their net effect on size is captured through calibrated growth parameters or the agglomerator’s coalescence kernel.

**Q: How can I improve reproducibility between batch granulation runs?**

A: Reproducibility comes from controlling the critical inputs (seed, spray, endpoint). Dyssol Pro identifies which inputs most move the product PSD via sensitivity studies, so you know what to standardize to tighten run-to-run consistency.

**Q: What are critical process parameters in batch granulation?**

A: Typically spray rate, total liquid, seed PSD, and endpoint timing. Dyssol Pro lets you rank these by their effect on the product PSD in a model-based DoE, focusing experimental effort on the truly critical ones.

**Q: How do I transfer a batch granulation recipe to larger scale?**

A: Scale-up transfers the fitted growth behavior and matches the spray-to-surface balance at larger charge. Dyssol Pro lets you calibrate the growth parameters on lab batches and run the model at the larger charge to predict the growth curve and endpoint.

**Q: How can I model particle growth in batch granulation?**

A: This is the unit’s purpose: a population balance with surface-area-coupled layering growth and increasing bed mass. In Dyssol Pro you set the spray and charge and it returns the PSD-versus-time growth trajectory.

**Q: How can I identify the optimal granulation endpoint using torque?**

A: Torque-based endpoints belong to high-shear granulation, where torque tracks the wet-mass consistency as liquid is added. Dyssol Pro gives a size-based endpoint from the PSD growth curve, so you can define the endpoint from the target granule size directly.

**Q: Why does my batch granulation produce too many fines?**

A: Excess fines mean insufficient growth or too much overspray/seed carryover. Dyssol Pro tracks the PSD growth, so you can study how spray rate and duration shift the fine fraction toward the target.

**Q: How does fill level affect batch granulator performance?**

A: Fill (charge mass) sets the total surface area sharing the spray and therefore the per-particle growth rate. Dyssol Pro couples growth to total surface area, so you can study how charge mass changes the growth rate and time-to-endpoint.

**Q: How can I avoid overgranulation in high-shear mixing?**

A: Overgranulation is runaway coalescence from too much liquid or massing time. In Dyssol Pro the coalescence-driven regime is captured with the agglomerator’s kernel model, so you can study the liquid input and residence time that keep growth controlled against the target size.

**Q: What causes poor binder distribution in batch granulation?**

A: Uneven binder comes from spray pattern, droplet size, and bed mixing, and is improved with finer atomization and better fluidization. In Dyssol Pro the net growth effect of the binder is propagated through the PSD, so you can study how the overall spray rate shifts the product size.

**Q: How do I optimize wet massing time?**

A: Wet massing is the high-shear step where the wetted mass is worked before or after liquid addition to distribute binder and densify the granules. It is optimized by balancing massing time and liquid level to reach the target granule density and size without tipping into overgranulation.

**Q: How does powder cohesiveness affect batch granulation?**

A: Cohesion affects fluidization quality and how readily the powder wets and nucleates, so cohesive powders may need stronger fluidization or flow aids. In Dyssol Pro the resulting growth behavior is represented through calibrated parameters, so you can study how it shifts the product PSD.

**Q: How can I improve granule flowability after batch granulation?**

A: Flowability improves with larger, rounder, less dusty granules. Dyssol Pro predicts the product PSD and dust, the main drivers of flowability, so you can target a size distribution that flows well.

**Q: How do I reduce cleaning time after batch granulation?**

A: Cleaning time is driven by the equipment geometry and how much sticky material deposits on surfaces. It is reduced with accessible, well-draining geometries, clean-in-place design, and operating points that avoid the overwetting that leaves tacky deposits.

**Q: How can I model batch granulation using population balances?**

A: This is exactly what the unit does: a population balance advancing the PSD by layering growth with increasing bed mass. In Dyssol Pro you parameterize the growth and run it to get the PSD trajectory, the basis for endpoint and scale-up studies.

**Q: How does continuous granulation differ from batch granulation?**

A: In continuous operation nuclei are fed and product withdrawn so the bed runs at a steady size distribution, whereas a batch grows the whole charge over time. Dyssol Pro provides both modes of the granulator, so you can simulate the continuous steady state (and its dynamics) or the batch growth curve and compare them directly.

**Q: How can I control residence time in a continuous granulator?**

A: Residence time is set by the bed holdup divided by the throughput, which you adjust through nuclei feed and product withdrawal. Dyssol Pro models the holdup and flows dynamically, so you can study how feed and withdrawal set residence and therefore the product size.

**Q: Why does continuous granulation produce variable particle size?**

A: Size variability comes from fluctuations in spray rate, nuclei feed, or recycle, and from the granulation dynamics amplifying them. Dyssol Pro’s population-balance model lets you impose those disturbances and see how the product PSD responds, helping you find stabilizing operating points.

**Q: How do feed rate fluctuations affect continuous granulation quality?**

A: Feed swings shift the surface-area balance and therefore the growth rate and product size. In Dyssol Pro you apply feed-rate transients and track the PSD response, quantifying how much a given fluctuation moves the product — and how a buffer or control loop would damp it.

**Q: How can I control moisture content in continuous granulation?**

A: Granule moisture is set by the balance of sprayed liquid against evaporation and the moisture leaving with product. Dyssol Pro carries a granule-moisture parameter and the liquid balance, so you can study how spray rate and gas conditions set the product moisture.

**Q: What sensors are useful for real-time granulation control?**

A: Real-time control typically uses PSD (spatial filter velocimetry), bed temperature, and humidity sensors. Dyssol Pro predicts the PSD, moisture, and flows those sensors measure, giving a model basis for control design and soft sensors.

**Q: How do I start up and shut down a continuous granulation process?**

A: Startup and shutdown are transient operations where the bed builds up or runs down toward/away from steady state. Dyssol Pro is dynamic and was validated on continuous-granulation startup, so you can simulate these transients and design the procedure and off-spec handling.

**Q: How can I prevent clogging in a continuous granulator?**

A: Clogging from nozzle fouling and sticky deposits is tied to overwetting and stickiness. Dyssol Pro tracks the liquid balance and overspray, so you can study spray rates that avoid the overwet conditions that lead to clogging.

**Q: How do I compare twin-screw granulation and drum granulation?**

A: Twin-screw and drum granulation use different growth mechanisms — shear-driven coalescence versus tumbling and layering — and different equipment. In Dyssol Pro each mechanism’s net effect is represented through calibrated growth parameters, so you can compare their process behavior and product PSD side by side in the flowsheet.

**Q: How can I model continuous granulation dynamics?**

A: This is the unit’s purpose: a population balance with surface-area-coupled growth, overspray, and continuous feed/withdrawal. In Dyssol Pro you set those parameters and it returns the dynamic and steady-state PSD inside the flowsheet.

**Q: How can I stabilize product quality in continuous granulation?**

A: Stable product comes from steady operating points and control of size via recycle/classification. Dyssol Pro lets you find stable windows and test control strategies on the dynamic model before applying them to the plant.

**Q: What causes residence time distribution broadening in a continuous granulator?**

A: RTD broadening comes from back-mixing in the bed and recycle loops. Dyssol Pro models the bed holdup and any recycle, so you can study how mixing and recycle widen the RTD and affect product uniformity.

**Q: How do screw configuration and speed affect twin-screw granulation?**

A: Screw configuration and speed set the conveying, mixing, and shear in a twin-screw granulator, driving coalescence and breakage and therefore granule size. In Dyssol Pro their net effect on growth and PSD is captured through calibrated growth parameters.

**Q: How can I control liquid-to-solid ratio in continuous granulation?**

A: The liquid-to-solid ratio drives both growth and moisture, set by spray and solids feed rates. Dyssol Pro tracks both the solids growth and the liquid balance, so you can study how the ratio shifts product size and moisture.

**Q: How do I handle off-spec material during continuous granulation startup?**

A: Off-spec product during startup is screened and often recycled. Dyssol Pro simulates the startup transient and any recycle/classification, so you can estimate the off-spec quantity and design how to rework it.

**Q: What is the best control strategy for continuous wet granulation?**

A: Effective control targets PSD and moisture against feed and recycle disturbances. Dyssol Pro lets you test candidate strategies on the dynamic model — how the PSD and moisture respond to control moves — before commissioning.

**Q: How can I integrate drying after continuous granulation?**

A: Granules usually need post-drying to final moisture. In Dyssol Pro you connect the granulator to a fluidized-bed dryer and study how the granule moisture evolves through the combined process.

**Q: How do I reduce waste in continuous granulation?**

A: Waste is mainly dust (overspray) and off-spec product. Dyssol Pro quantifies the overspray-to-dust split and the off-spec fraction, so you can study operating points and recycle that minimize both.

**Q: How can I scale continuous granulation from pilot to commercial scale?**

A: Scale-up transfers the fitted growth and overspray parameters to larger throughput and bed. Dyssol Pro lets you calibrate at pilot scale and run the model at commercial throughput inside the flowsheet to check PSD and dust before building.

**Q: How do I simulate recycle loops in continuous granulation?**

A: Recycle of screened fines/oversize is central to granulation circuits. Dyssol Pro solves the recycle loop dynamically, so you can study how cut sizes and recycle ratios set the product PSD and the circulating load.

---

## Cyclone

URL: https://www.dyssoltec.com/classification/cyclone-separator/ (German: https://www.dyssoltec.com/de/classification/cyclone-separator/)

Cyclone simulation in Dyssol Pro: predict size-resolved separation efficiency, solids capture, and pressure drop for gas–solid separation in dynamic flowsheets.

Spin solids out of a gas stream and predict the size-resolved capture, exhaust dust load, and pressure drop — inside a connected dynamic flowsheet.

### How it works

Gas enters a cyclone tangentially and forms a downward outer vortex and an inner upward vortex that leaves through the vortex finder. In the swirling flow each particle feels a strong centrifugal force flinging it outward against the gas drag pulling it inward to the exit. Coarse, dense particles win, migrate to the wall, slide down the cone, and leave at the bottom as separated solids; fine particles stay entrained and exit with the cleaned gas.

The cut size — where capture probability is 50% — falls as the swirl velocity rises, so smaller cyclones and higher inlet velocities catch finer particles. But two effects complicate the simple picture: a solids-loading limit, where the gas can only carry so much before excess solids drop out en masse at the wall, and a secondary flow near the top that re-separates material around the vortex finder. Together these make real performance depend strongly on loading, geometry, and wall friction, not just particle size.

### The model

Dyssol Pro computes the gas–solid separation at the population level: from the cyclone geometry and the operating gas flow it resolves the internal swirl field into a size-resolved separation efficiency, splitting the feed solids between the captured-solids outlet and the cleaned-gas outlet — together with the pressure drop across the cyclone, at every time point of the dynamic flowsheet.

### Equipment this model can represent

- **Reverse-flow cyclones**: The classic tangential-inlet dust separator; gas reverses and exits the top.
- **Axial-inlet cyclones**: Guide vanes impart swirl; compact, used in multicyclone arrays.
- **Multicyclones**: Many small-diameter cyclones in parallel for a finer cut at high throughput.
- **Cyclone pre-separators**: Coarse-duty cyclones ahead of bag or cartridge filters to offload them.

### Typical engineering studies

- **Capture & exhaust dust**: Predict solids capture and exhaust dust load for a given cyclone geometry and gas flow.
- **Geometry sensitivity**: Study how diameter, vortex-finder size, and inlet shape move the cut.
- **Gas-cleaning trains**: Connect upstream (pneumatic transport, fluid bed) and a downstream gas filter, and optimize the cyclone as a pre-separator.
- **Efficiency calibration**: Calibrate the efficiency adjustment factor to measured performance, then use predictively.
- **Loading & temperature effects**: Study solids-loading and gas-temperature effects on capture across operating points.

### FAQ

**Q: How does a Muschelknautz cyclone differ from a standard cyclone?**

A: It’s not a different cyclone but a more complete way to model one: a loading-based method adds the solids-loading limit, wall friction, and the secondary vortex-finder flow that simpler cut-size formulas ignore. Dyssol Pro works at exactly this level of description, so predicted efficiency reflects geometry and loading rather than particle size alone.

**Q: How do I calculate cyclone separation efficiency?**

A: Efficiency comes from the swirl velocity, geometry, solids loading, and particle size and density. Dyssol Pro computes the size-resolved grade efficiency and the overall capture directly from the cyclone geometry and gas flow you specify.

**Q: Why is my cyclone not removing enough fine particles?**

A: Fines below the cut size simply follow the gas out; capturing them needs a higher swirl velocity or a smaller cyclone. In Dyssol Pro you vary the inlet flow and geometry (outer and vortex-finder diameters) and watch the fine-end capture on the grade curve to see what it would take.

**Q: How can I reduce pressure drop in a cyclone?**

A: Pressure drop falls with lower inlet velocity and larger vortex finder — but so does efficiency, so it’s a trade-off. Dyssol Pro calculates the cyclone pressure drop, so you can study it directly against velocity and geometry alongside the separation efficiency and pick the operating point that balances both.

**Q: How does inlet velocity affect cyclone performance?**

A: Higher inlet velocity raises centrifugal force and captures finer particles, at the cost of more pressure drop, erosion, and re-entrainment. In Dyssol Pro the inlet velocity follows from gas flow and entry geometry and sets the internal tangential velocities, so you can map capture against flow.

**Q: How do particle size and density influence cyclone efficiency?**

A: Capture rises strongly with particle size and with the solid-to-gas density difference. Dyssol Pro uses both — size from the PSD and densities from the materials database — in the cut-size calculation, so multi-size, multi-density feeds are handled per class.

**Q: How can I prevent solids buildup in a cyclone?**

A: Build-up comes from sticky or moist solids and low wall velocity, so it is limited by keeping the solids dry and the wall velocity high enough to scour deposits. Dyssol Pro tracks the upstream moisture and temperature feeding the cyclone, so you can favor conditions that keep the solids in the free-flowing regime.

**Q: What causes re-entrainment of particles in a cyclone separator?**

A: Already-separated solids get picked back up when loading limits and the secondary flow near the vortex finder are exceeded. Dyssol Pro explicitly resolves the loading limit and a secondary stream, so you can study how loading drives re-entrainment and capture.

**Q: How do I improve cyclone efficiency for submicron particles?**

A: Cyclones are intrinsically poor below ~1 µm; you need extreme swirl or, realistically, a downstream filter. Dyssol Pro shows the weak submicron capture on the grade curve and lets you add a gas filter downstream to handle what the cyclone cannot.

**Q: Why is my cyclone outlet dust concentration too high?**

A: Either fines are below the cut or the cyclone is overloaded, so solids leave with the gas. In Dyssol Pro you quantify the solids mass flow at the gas outlet, optimize geometry and flow to lower it, and couple a filter if the target is below what a cyclone can reach.

**Q: How does cyclone geometry affect cut size?**

A: The outer and vortex-finder diameters, heights, and inlet shape all set the swirl field and therefore the cut. In Dyssol Pro these are model parameters, so you run a geometry sensitivity study and see the cut size respond directly.

**Q: How can I reduce product loss through the cyclone exhaust?**

A: This is the same as improving fine capture: raise swirl, tighten geometry, or add a filter. Dyssol Pro lets you study the gas-outlet solids against geometry and flow and design a cyclone-plus-filter train that recovers the product.

**Q: How do I choose between single cyclone and multicyclone systems?**

A: Many small cyclones in parallel give a finer cut at the same throughput, at higher pressure drop. In Dyssol Pro you model a smaller-diameter unit to see the finer cut it achieves and read its pressure drop, so you can weigh the parallel arrangement against the pressure-drop budget.

**Q: How does gas temperature affect cyclone separation?**

A: Temperature changes gas density and viscosity, which shift settling and the cut. Dyssol Pro takes gas properties from the materials database at the operating condition, so you can study temperature by running at the corresponding gas properties.

**Q: How can I detect plugging in a cyclone?**

A: Plugging comes from moist or sticky solids bridging at the cone apex or dust outlet, so it is limited by keeping the feed dry and the solids loading within the range the outlet can clear. Dyssol Pro tracks the upstream moisture and solids loading feeding the cyclone, so you can see when conditions drift toward the sticky, plugging-prone regime and adjust before it happens.

**Q: What is the influence of solids loading on cyclone pressure drop?**

A: Higher solids loading actually lowers pressure drop (the solids damp the swirl) while changing the capture through the loading limit. Dyssol Pro calculates the pressure drop and models the loading effect on separation efficiency, so you can study both responses to solids loading together.

**Q: How can I optimize a cyclone before a bag filter?**

A: The cyclone should strip the coarse bulk so the filter handles only fines, extending filter life. In Dyssol Pro you connect the cyclone to the gas filter and optimize the cyclone cut so it removes as much load as possible before the filter — sizing the whole gas-cleaning train together.

---

## Pneumatic Conveying

URL: https://www.dyssoltec.com/transport/pneumatic-conveying/ (German: https://www.dyssoltec.com/de/transport/pneumatic-conveying/)

Pneumatic conveying simulation in Dyssol Pro: a pressure-drop model from the pipe layout covering gas and solids friction, acceleration, lift, and bends.

Predict the pressure drop of a conveying line from its pipe-and-bend layout — gas and solids friction, acceleration, lift, and bends — inside a connected flowsheet.

### How it works

Pneumatic conveying moves bulk solids by entraining them in a flowing gas through a pipe. The gas drags the particles along; each particle lags the gas slightly (a near-constant slip), and the suspension’s behavior depends on the gas velocity relative to the particles’ tendency to settle. Above a critical velocity the solids stay suspended and travel in dilute phase; too slow and they drop out and slide along the bottom (saltation), risking blockage. Moving the solids costs pressure: the gas itself has wall friction, the solids must be accelerated up to speed, lifted against gravity on inclines, and they rub against the wall and each other; every bend adds a further loss as the solids are re-accelerated after impact.

The total pressure drop along the line is what sizes the blower and sets the conveying capacity. It rises with solids loading, line length, number of bends, and gas velocity — so design is a balance between enough velocity to keep solids suspended and not so much that pressure drop, energy, attrition, and erosion run away.

### The model

Dyssol Pro models the conveying line as a sequence of pipe and bend sections — each with its length, diameter, slope, and bend angle — and computes the pressure drop needed to move the solids through it, given the inlet and outlet pressures, at every operating point of the flowsheet.

### Equipment this model can represent

- **Dilute-phase (lean) conveying**: High velocity, low solids loading; simple and common.
- **Dense-phase conveying**: Low velocity, high loading; gentler on product, less attrition.
- **Pressure (push) systems**: Blower upstream, conveying from one source to many destinations.
- **Vacuum (pull) systems**: Suction from many sources to one destination.

### Typical engineering studies

- **Pressure-drop prediction**: Predict the pressure drop of a conveying line for a given layout, gas flow, and solids loading.
- **Routing comparison**: Compare pipe routings (length, diameter, bends, inclines) on pressure drop.
- **Blower sizing**: Provide the conveying pressure drop to size a blower or check an existing system’s capacity.
- **Gas-handling coupling**: Couple to upstream feeders and a downstream cyclone/filter in a gas-handling flowsheet.
- **Loading vs. velocity**: Study how solids loading and gas velocity trade off against pressure drop.

### FAQ

**Q: How do I design a pneumatic conveying system for powder?**

A: You choose dilute or dense phase, set a gas velocity that keeps the powder suspended, and lay out the line to keep pressure drop within the blower’s range. Dyssol Pro computes the pressure drop for a candidate layout and gas flow, so you can iterate pipe sizing, routing, and velocity against the available pressure before finalizing the design.

**Q: Why is my pneumatic transport line clogging?**

A: Clogging usually means the gas velocity dropped below the saltation velocity, so solids settled and bridged. Dyssol Pro computes the gas velocity and pressure drop along the line, so you can check whether velocity stays above the suspension threshold and find where it falls short.

**Q: How can I reduce particle breakage during pneumatic conveying?**

A: Breakage comes from impacts at bends and high velocity, reduced by lower velocity (dense phase) and gentler bends. Dyssol Pro computes the gas velocity and the bend layout that drive it, so you can choose a lower-velocity design that still conveys the solids reliably.

**Q: What is the difference between dilute phase and dense phase conveying?**

A: Dilute phase uses high velocity and low loading with solids fully suspended; dense phase uses low velocity and high loading, moving solids as slugs — gentler but needing more pressure. Dyssol Pro’s model works on the dilute-phase basis, so it applies directly to suspended-flow, high-velocity conveying lines.

**Q: How do I calculate pressure drop in pneumatic transport?**

A: Pressure drop is the sum of gas friction, solids acceleration, lift, interparticle friction, and bend losses. Dyssol Pro computes exactly this breakdown from your pipe-and-bend layout, gas flow, and solids loading, returning the total and each component.

**Q: How can I prevent powder buildup in conveying pipes?**

A: Build-up is settled material from too-low velocity or sticky powder. Dyssol Pro computes the gas velocity along the line, so you can keep it above the suspension threshold and prevent the solids from dropping out.

**Q: How does air velocity affect product degradation?**

A: Higher air velocity raises impact energy and attrition or degradation, especially at bends. Dyssol Pro relates the gas flow to velocity and pressure drop, so you can study the lowest velocity that still conveys reliably and thereby limits degradation.

**Q: How do bends and pipe length affect pneumatic conveying performance?**

A: Each bend adds a re-acceleration loss and length adds friction, both raising pressure drop. Dyssol Pro models pipes and bends explicitly with their lengths, diameters, and angles, so you can quantify how routing choices change the total pressure drop.

**Q: How can I reduce dust generation during pneumatic conveying?**

A: Dust comes from attrition during transport, reduced by gentler, lower-velocity conveying. Dyssol Pro computes the gas velocity along the line, so you can design a lower-velocity route, and you can couple a downstream cyclone or filter to capture the dust that forms.

**Q: How do I model solids flow in a pneumatic transport system?**

A: Solids flow is governed by the gas velocity relative to the particles, which lag the gas by a roughly constant slip, together with the solids-to-gas loading ratio and the pipe-and-bend layout. Dyssol Pro computes exactly these quantities — gas velocity, solids loading, and the resulting pressure drop — from your defined pipe-and-bend system, so you can quantify the flow rather than infer it.

**Q: How can I prevent electrostatic charging in pneumatic conveying?**

A: Electrostatic build-up comes from particle–wall tribocharging during transport, aggravated by dry gas and insulating pipe. It is controlled by bonding and grounding all conductive parts, raising the gas humidity, and adding antistatic agents or conductive liners.

**Q: Why is my pneumatic conveying system consuming too much air?**

A: Excess air use means the velocity (and thus gas flow) is higher than needed for reliable suspension. Dyssol Pro lets you study the minimum gas flow that keeps solids suspended at acceptable pressure drop, pointing to a leaner air rate.

**Q: How do I select a blower for pneumatic transport?**

A: The blower must deliver the gas flow at the system’s total pressure drop. Dyssol Pro computes that pressure drop for your line and loading, giving the operating point the blower must meet — the blower selection itself is then a straightforward match.

**Q: What causes saltation in pneumatic conveying lines?**

A: Saltation occurs when gas velocity drops below the value needed to keep particles suspended, so they fall out. Dyssol Pro computes the gas velocity along the line, so you can keep it above the saltation threshold and identify any low-velocity zones before they cause trouble.

**Q: How can I reduce erosion in bends and elbows?**

A: Erosion is driven by particle impacts at bends at high velocity, so it is limited by lowering the velocity and using gentler, longer-radius bends. Dyssol Pro computes the gas velocity and the bend loading that drive it, so you can choose a routing and velocity that ease the wear.

**Q: How does particle shape affect pneumatic conveying behavior?**

A: Shape changes drag and saltation velocity, so irregular particles convey differently and need more velocity to stay suspended. Dyssol Pro computes the pressure drop and gas velocity from the bulk flow, so you can study the higher velocity an awkward-flowing powder needs and its cost in pressure.

**Q: How do I choose between pressure and vacuum conveying?**

A: Pressure systems suit one-to-many distribution and longer distances; vacuum suits many-to-one and dust-free pickup. Dyssol Pro computes the pressure drop either way (you set inlet/outlet pressures), so you can compare the conveying duty; the source/destination topology drives the final choice.

**Q: How can I prevent segregation during pneumatic conveying?**

A: Segregation by size or density happens in dilute flow and at bends, where coarse and fine particles travel at different speeds. It is limited by keeping the flow well suspended, avoiding long horizontal runs where heavier particles lag, and re-mixing the solids downstream of the conveying line.

**Q: How do I detect blockages in pneumatic transport lines?**

A: Blockage detection is a monitoring task using pressure and flow sensors. Dyssol Pro predicts the normal pressure drop along the line, providing a baseline that a rising measured pressure can be compared against to flag a developing blockage.

**Q: How can I simulate pressure drop and solids loading in pneumatic conveying?**

A: Pressure drop and solids loading follow from the gas flow, the pipe-and-bend geometry, and the solids feed rate — friction, acceleration, lift, and bend losses all scale with these inputs. Dyssol Pro computes this directly: define the pipe-and-bend layout and the gas/solids feed, and it returns the solids loading and the full pressure-drop breakdown, ready to size the system in the flowsheet.