Continuous Cake Filter¶

Represents a continuous cake filter unit operation that separates solids from a liquid stream. The calculation is based on the cake filter equations from McCabe, Smith and Harriott, "Unit Operations of Chemical Engineering", Chapter 29. Solids removal efficiency is governed by the specified cake relative humidity, filter area, and operating parameters.

DWSIM.UnitOperations.UnitOperations.Filter
Assembly DWSIM.UnitOperations.dll · Object ← BaseClass ← UnitOpBaseClass ← Filter

At a glance¶

Continuous Cake Filter in the example flowsheet

Port	Index	Connected in the example
Inlet, material	`0`	Slurry
Outlet, material	`0`	Filtrate
Outlet, material	`1`	Cake

Example¶

This code runs on every build of this site, and the output below is what it printed.

Python

fs = (Flowsheet.Create("FilterExample")
      .WithCompounds("Water", "Benzoic acid")
      .WithPropertyPackage(PropertyPackages.Raoult))

# Keep benzoic acid in the solid phase: the filter reads the solids from phase 7.
pp = list(fs.Inner.PropertyPackages.Values)[0].__implementation__
pp.ForcedSolids.Add("Benzoic acid")

slurry = (fs.AddMaterialStream("Slurry")
          .At(Q.Celsius(25.0), Q.Bar(1.0))
          .SetCompoundMassFlow("Water", 5.0)          # kg/s
          .SetCompoundMassFlow("Benzoic acid", 0.5))
filtrate = fs.AddMaterialStream("Filtrate")
cake = fs.AddMaterialStream("Cake")

flt = (fs.AddFilter("F-1")
       .ConnectFeed(slurry)
       .ConnectProduct(filtrate, 0)
       .ConnectProduct(cake, 1))

# Simulation mode: the pressure drop needed to pass the feed through a given area.
f = flt.Object
f.CalcMode = Filter.CalculationMode.Simulation
f.TotalFilterArea = 8.0                 # m2
f.SubmergedAreaFraction = 0.35
f.FilterCycleTime = 90.0                # s per drum revolution
f.SpecificCakeResistance = 3.0e9        # m/kg
f.FilterMediumResistance = 1.0e9        # 1/m
f.CakeRelativeHumidity = 15.0           # % liquid in the discharged cake

fs.AutoLayout()
fs.Solve()

c = cake.Object
print(f"Pressure drop   = {f.PressureDrop / 1e5:.3f} bar")
print(f"Filtrate        = {filtrate.Object.GetMassFlow():.3f} kg/s")
print(f"Cake            = {c.GetMassFlow():.3f} kg/s, "
      f"{c.Phases[0].Compounds['Water'].MassFraction * 100:.1f} wt% water")
print(f"Mass balance    = {slurry.Object.GetMassFlow():.3f} kg/s in, "
      f"{filtrate.Object.GetMassFlow() + c.GetMassFlow():.3f} kg/s out")

Output

Pressure drop   = 0.161 bar
Filtrate        = 4.912 kg/s
Cake            = 0.588 kg/s, 15.0 wt% water
Mass balance    = 5.500 kg/s in, 5.500 kg/s out

DWSIM 10.2.11.0, generated 2026-10-08.

Calculation modes¶

Set with CalcMode (CalculationMode). The mode decides which properties are inputs; every other one is a result and is overwritten by the calculation.

Mode	Value	What it does	Inputs
`Design`	0	Design mode: calculates the required total filter area given a specified pressure drop.	`PROP_FT_2`, `PROP_FT_3`, `PROP_FT_4`, `PROP_FT_5`, `PROP_FT_6`, `PROP_FT_7`
`Simulation`	1	Simulation mode: calculates the pressure drop given a specified total filter area.	`PROP_FT_1`, `PROP_FT_2`, `PROP_FT_3`, `PROP_FT_4`, `PROP_FT_5`, `PROP_FT_6`

Properties¶

IDs accepted by GetPropertyValue, SetPropertyValue, the sensitivity analysis, the optimizer, the Adjust block and dynamic events. Units are SI; pass another unit system to GetPropertyValue to get them converted.

ID	Name	Unit (SI)	Input in
`PROP_FT_0`	Energy Balance	kW	result
`PROP_FT_1`	Total Filter Area	m2	`Simulation`
`PROP_FT_2`	Cake Relative Humidity (%)	%	all modes
`PROP_FT_3`	Cycle Time	s	all modes
`PROP_FT_4`	Filter Medium Resistance	m-1	all modes
`PROP_FT_5`	Specific Cake Resistance	m/kg	all modes
`PROP_FT_6`	Submerged Area Fraction		all modes
`PROP_FT_7`	Total Pressure Drop	Pa	`Design`

Dynamic mode¶

Extra properties used when the flowsheet runs in dynamic mode.

Name	Unit
Cake Mass	kg
Backwash Interval	s
Backwash Duration	s
Time Since Last Backwash	s
Backwash Active
Separation Efficiency

Learn more¶

User guide
- Continuous Cake Filter
FluentAPI
- FilterBuilder

API members¶

Public members declared by this class. Inherited members are documented on the base classes.

Constructors¶

Filter(): Initializes a new instance of the Filter class with default settings.

Initializes a new instance of the Filter class with default settings.

C#VB.NET

public Filter()

Public Sub New()

Filter(string, string): Initializes a new instance of the Filter class with the specified name and description.

Initializes a new instance of the Filter class with the specified name and description.

Parameter	Type	Description
`name`	`String`	The display name of the filter object.
`description`	`String`	A brief description of the filter object.

C#VB.NET

public Filter(string name, string description)

Public Sub New(name As String, description As String)

Properties¶

CakeRelativeHumidity: Gets or sets the relative humidity of the discharged cake as a percentage (%).

Gets or sets the relative humidity of the discharged cake as a percentage (%).

C#VB.NET

public double CakeRelativeHumidity { get; set; }

Public Property CakeRelativeHumidity As Double

CalcMode: Gets or sets the calculation mode (Design or Simulation).

Gets or sets the calculation mode (Design or Simulation).

C#VB.NET

public Filter.CalculationMode CalcMode { get; set; }

Public Property CalcMode As Filter.CalculationMode

EnergyImb: Gets or sets the energy imbalance across the filter (kW).

Gets or sets the energy imbalance across the filter (kW).

C#VB.NET

public double EnergyImb { get; set; }

Public Property EnergyImb As Double

EquipmentTypes: Gets the list of supported equipment types for this unit operation.

Gets the list of supported equipment types for this unit operation.

C#VB.NET

public override List<string> EquipmentTypes { get; }

Public Overrides ReadOnly Property EquipmentTypes As List(Of String)

FilterCycleTime: Gets or sets the filter cycle time (s).

Gets or sets the filter cycle time (s).

C#VB.NET

public double FilterCycleTime { get; set; }

Public Property FilterCycleTime As Double

FilterMediumResistance: Gets or sets the filter medium resistance (1/m).

Gets or sets the filter medium resistance (1/m).

C#VB.NET

public double FilterMediumResistance { get; set; }

Public Property FilterMediumResistance As Double

HasPropertiesForDynamicMode: Gets a value indicating whether this unit operation exposes properties for dynamic mode.

Gets a value indicating whether this unit operation exposes properties for dynamic mode.

C#VB.NET

public override bool HasPropertiesForDynamicMode { get; }

Public Overrides ReadOnly Property HasPropertiesForDynamicMode As Boolean

MobileCompatible: Gets a value indicating whether this unit operation is compatible with mobile interfaces.

Gets a value indicating whether this unit operation is compatible with mobile interfaces.

C#VB.NET

public override bool MobileCompatible { get; }

Public Overrides ReadOnly Property MobileCompatible As Boolean

ObjectClass: Gets or sets the simulation object class for this unit operation.

Gets or sets the simulation object class for this unit operation.

C#VB.NET

public override SimulationObjectClass ObjectClass { get; set; }

Public Overrides Property ObjectClass As SimulationObjectClass

PressureDrop: Gets or sets the total pressure drop across the filter (Pa).

Gets or sets the total pressure drop across the filter (Pa).

C#VB.NET

public double PressureDrop { get; set; }

Public Property PressureDrop As Double

SpecificCakeResistance: Gets or sets the specific cake resistance (m/kg).

Gets or sets the specific cake resistance (m/kg).

C#VB.NET

public double SpecificCakeResistance { get; set; }

Public Property SpecificCakeResistance As Double

SubmergedAreaFraction: Gets or sets the fraction of the filter area that is submerged during filtration (dimensionless, 0 to 1).

Gets or sets the fraction of the filter area that is submerged during filtration (dimensionless, 0 to 1).

C#VB.NET

public double SubmergedAreaFraction { get; set; }

Public Property SubmergedAreaFraction As Double

SupportsDynamicMode: Gets a value indicating whether this unit operation supports dynamic simulation mode.

Gets a value indicating whether this unit operation supports dynamic simulation mode.

C#VB.NET

public override bool SupportsDynamicMode { get; }

Public Overrides ReadOnly Property SupportsDynamicMode As Boolean

TotalFilterArea: Gets or sets the total filter area (m²).

Gets or sets the total filter area (m²).

C#VB.NET

public double TotalFilterArea { get; set; }

Public Property TotalFilterArea As Double

Methods¶

Calculate(object): Calculates the filter separation results.

Calculates the filter separation results.

Parameter	Type	Description
`args`	`Object`

C#VB.NET

public override void Calculate(object args = null)

Public Overrides Sub Calculate(args As Object = Nothing)

CloneXML(): Creates a deep copy via XML serialization.

Creates a deep copy via XML serialization.

C#VB.NET

public override object CloneXML()

Public Overrides Function CloneXML() As Object

CloseEditForm(): Closes and disposes the editing form.

Closes and disposes the editing form.

C#VB.NET

public override void CloseEditForm()

Public Overrides Sub CloseEditForm()

CreateDynamicProperties(): Registers the dynamic properties for dynamic simulation mode: cake mass, backwash interval, duration, elapsed time...

Registers the dynamic properties for dynamic simulation mode: cake mass, backwash interval, duration, elapsed time and state, and the solids separation efficiency (fraction, 0-1).

C#VB.NET

public override void CreateDynamicProperties()

Public Overrides Sub CreateDynamicProperties()

DeCalculate(): Clears all calculated results.

Clears all calculated results.

C#VB.NET

public override void DeCalculate()

Public Overrides Sub DeCalculate()

DisplayEditForm(): Opens or activates the editing form.

Opens or activates the editing form.

C#VB.NET

public override void DisplayEditForm()

Public Overrides Sub DisplayEditForm()

GetDisplayDescription(): Returns the localised display description.

Returns the localised display description.

C#VB.NET

public override string GetDisplayDescription()

Public Overrides Function GetDisplayDescription() As String

GetDisplayName(): Returns the localised display name.

Returns the localised display name.

C#VB.NET

public override string GetDisplayName()

Public Overrides Function GetDisplayName() As String

GetIconBitmapBytes(): Returns the icon bitmap as a byte array.

Returns the icon bitmap as a byte array.

C#VB.NET

public override byte[] GetIconBitmapBytes()

Public Overrides Function GetIconBitmapBytes() As Byte()

GetProperties(PropertyType): Returns an array of property identifiers for the specified property type.

Returns an array of property identifiers for the specified property type.

Parameter	Type	Description
`proptype`	`PropertyType`

C#VB.NET

public override string[] GetProperties(PropertyType proptype)

Public Overrides Function GetProperties(proptype As PropertyType) As String()

GetPropertyUnit(string, IUnitsOfMeasure): Returns the unit string for the specified property.

Returns the unit string for the specified property.

Parameter	Type	Description
`prop`	`String`
`su`	`IUnitsOfMeasure`

C#VB.NET

public override string GetPropertyUnit(string prop, IUnitsOfMeasure su = null)

Public Overrides Function GetPropertyUnit(prop As String, su As IUnitsOfMeasure = Nothing) As String

GetPropertyValue(string, IUnitsOfMeasure): Returns the value of the specified property.

Returns the value of the specified property.

Parameter	Type	Description
`prop`	`String`
`su`	`IUnitsOfMeasure`

C#VB.NET

public override object GetPropertyValue(string prop, IUnitsOfMeasure su = null)

Public Overrides Function GetPropertyValue(prop As String, su As IUnitsOfMeasure = Nothing) As Object

GetReport(IUnitsOfMeasure, CultureInfo, string): Generates a plain-text report of the filter results.

Generates a plain-text report of the filter results.

Parameter	Type	Description
`su`	`IUnitsOfMeasure`
`ci`	`CultureInfo`
`numberformat`	`String`

C#VB.NET

public override string GetReport(IUnitsOfMeasure su, CultureInfo ci, string numberformat)

Public Overrides Function GetReport(su As IUnitsOfMeasure, ci As CultureInfo, numberformat As String) As String

LoadData(List<XElement>): Loads object data from a list of XML elements.

Loads object data from a list of XML elements.

Parameter	Type	Description
`data`	`List<XElement>`	List of XML elements containing the serialized object data.

C#VB.NET

public override bool LoadData(List<XElement> data)

Public Overrides Function LoadData(data As List(Of XElement)) As Boolean

RunDynamicModel(): Runs one dynamic-mode integration step: accumulates captured solids in the cake, handles the backwash cycle, and...

Runs one dynamic-mode integration step: accumulates captured solids in the cake, handles the backwash cycle, and sets the filtrate flow from the cake and medium resistances and the cake outlet flow.

C#VB.NET

public override void RunDynamicModel()

Public Overrides Sub RunDynamicModel()

SaveData(): Saves object data to a list of XML elements for serialization.

Saves object data to a list of XML elements for serialization.

C#VB.NET

public override List<XElement> SaveData()

Public Overrides Function SaveData() As List(Of XElement)

SetPropertyValue(string, object, IUnitsOfMeasure): Sets the value of the specified property.

Sets the value of the specified property.

Parameter	Type	Description
`prop`	`String`
`propval`	`Object`
`su`	`IUnitsOfMeasure`

C#VB.NET

public override bool SetPropertyValue(string prop, object propval, IUnitsOfMeasure su = null)

Public Overrides Function SetPropertyValue(prop As String, propval As Object, su As IUnitsOfMeasure = Nothing) As Boolean

UpdateEditForm(): Refreshes the editing form with updated data.

Refreshes the editing form with updated data.

C#VB.NET

public override void UpdateEditForm()

Public Overrides Sub UpdateEditForm()

Fields¶

f: The classic (WinForms) editor window open for this unit operation, if any.

The classic (WinForms) editor window open for this unit operation, if any. Not saved with the flowsheet.

C#VB.NET

public object f

Public f As Object