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.
The filtration stage follows Darcy’s law — the flow through cake and medium set by the pressure difference, the liquid viscosity, and the cake’s height and permeability — so a finer, less permeable cake filters slower and holds more liquid. The discharged cake is a porous bed whose pores still carry liquid, which is why it never leaves bone-dry.
Optional washing displaces contaminated pore liquid with clean wash, its efficiency set by the wash ratio and the dispersion within the cake, and deliquoring then draws gas through the cake to push residual liquid out down to the saturation fixed by applied pressure against capillary pressure. On this basis Dyssol Pro covers dewatering duties from vacuum drum and belt filters to high-pressure filter presses, and even feed-specific cake behavior beyond the standard description can be brought into the flowsheet.
Equipment this model can represent
Any solid–liquid cake-filtration duty producing a washed, dewatered cake and a clarified filtrate.
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
What teams investigate with the cake-filtration model.
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.
Technical FAQ
How can I improve cake filtration rate?
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.
Why is my liquid filter cake too wet?
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.
How do I choose between pressure filtration and vacuum filtration?
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.
What causes filter cloth blinding in liquid filtration?
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.
How does particle size distribution affect filtration performance?
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.
How can I reduce washing liquid consumption in cake filtration?
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.
How do I improve solid-liquid separation for fine particles?
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.
What is the effect of slurry concentration on filtration time?
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.
How do I scale up liquid filtration from lab tests?
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.
How can I model filter cake buildup over time?
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.
How can I improve filtrate clarity?
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.
Why is filtration time increasing during production?
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.
How does cake compressibility affect filtration?
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.
How do I choose the right filter aid?
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.
What causes cracks in a filter cake?
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.
How can I optimize cake washing efficiency?
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.
How does pressure affect liquid filtration performance?
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.
How can I prevent channeling in a filter cake?
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.
How do I reduce residual moisture after filtration?
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.
How can I model combined filtration and washing?
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.