Claus Sulfur Recovery Unit¶

DWSIM Plus

Available with a DWSIM Plus (Patreon) subscription.

Shortcut Claus Sulfur Recovery Unit. Takes an acid-gas feed and converts a configurable fraction of the H₂S into elemental sulfur via the overall reaction 2 H₂S + O₂ → 2 S + 2 H₂O. The sulfur outlet is emitted as moles of a surrogate "Sulfur" compound; the tail gas outlet carries unreacted feed plus produced water. Air is not tracked (shortcut). Heat of reaction is exported on the energy stream.

DWSIM.UnitOperations.Refining.Claus.ClausUnitOperation
Assembly DWSIM.UnitOperations.Refining.dll · Object ← BaseClass ← UnitOpBaseClass ← ClausUnitOperation

At a glance¶

Claus Sulfur Recovery Unit in the example flowsheet

Port	Index	Connected in the example
Inlet, material	`0`	Acid-gas
Inlet, material	`1`	Air
Outlet, material	`0`	Sulfur
Outlet, material	`1`	Tail-gas
Outlet, energy	`2`	Waste-heat

Example¶

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

Python

fs = (Flowsheet.Create("ClausExample")
      .WithCompounds("Hydrogen sulfide", "Carbon dioxide", "Water", "Oxygen", "Nitrogen", "Sulfur")
      .WithPropertyPackage(PropertyPackages.PengRobinson))

# Acid gas: 90 mol% H2S, 6 % CO2, 4 % water vapour, 100 kmol/h
acid_gas = (fs.AddMaterialStream("Acid-gas").At(Q.Celsius(50.0), Q.Bar(1.8))
            .SetCompoundMolarFlow("Hydrogen sulfide", 90.0 / 3.6)
            .SetCompoundMolarFlow("Carbon dioxide", 6.0 / 3.6)
            .SetCompoundMolarFlow("Water", 4.0 / 3.6))
# Combustion air: enough O2 for H2S + 1/2 O2 -> S + H2O, 5 % excess
o2 = 0.5 * 90.0 * 1.05
air = (fs.AddMaterialStream("Air").At(Q.Celsius(30.0), Q.Bar(1.8))
       .SetCompoundMolarFlow("Oxygen", o2 / 3.6)
       .SetCompoundMolarFlow("Nitrogen", o2 * 79.0 / 21.0 / 3.6))
sulfur = fs.AddMaterialStream("Sulfur")
tail_gas = fs.AddMaterialStream("Tail-gas")
heat = fs.AddEnergyStream("Waste-heat")

sru = (fs.AddClausSRU("SRU-1")
       .WithSulfurRecovery(0.97)
       .WithOperatingTemperature(Q.Celsius(150.0))   # outlet temperature after the condensers
       .WithOperatingPressure(Q.Bar(1.5))
       .ConnectFeed(acid_gas, 0).ConnectFeed(air, 1)
       .ConnectProduct(sulfur, 0).ConnectProduct(tail_gas, 1))
# The waste-heat duty leaves through outlet port 2
sru.ConnectEnergyProduct(heat, 2)

fs.AutoLayout()
fs.Solve()

h2s_in = acid_gas.Object.Phases[0].Compounds["Hydrogen sulfide"].MolarFlow     # mol/s
h2s_out = tail_gas.Object.Phases[0].Compounds["Hydrogen sulfide"].MolarFlow
print(f"Sulfur produced   = {sulfur.MassFlowKgPerSecond * 86.4:.1f} t/d")
print(f"Sulfur recovery   = {100.0 * (1.0 - h2s_out / h2s_in):.1f} %")
print(f"H2S in tail gas   = {tail_gas.OverallMoleFraction('Hydrogen sulfide') * 100.0:.2f} mol%")
print(f"Tail gas flow     = {tail_gas.MassFlowKgPerSecond * 3600.0:.0f} kg/h")
print(f"Waste heat        = {heat.EnergyFlowKW:.0f} kW")

Output

Sulfur produced   = 67.2 t/d
Sulfur recovery   = 97.0 %
H2S in tail gas   = 0.96 mol%
Tail gas flow     = 7095 kg/h
Waste heat        = 5335 kW

DWSIM 10.2.11.0, generated 2026-10-08.

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	Unit (SI)	Input
`Operating Temperature`	K	yes
`Operating Pressure`	Pa	yes
`Sulfur Recovery Fraction`	NF	yes
`Feed Mass Flow`	kg/s	result
`Sulfur Mass Flow`	kg/s	result
`Tail Gas Mass Flow`	kg/s	result
`Waste Heat Duty`	kW	result

Learn more¶

User guide
- Claus Sulfur Recovery Unit

API members¶

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

Constructors¶

ClausUnitOperation()

C#VB.NET

public ClausUnitOperation()

Public Sub New()

Properties¶

ComponentDescription: Gets or sets the CAPE-OPEN component description for this unit operation.

Gets or sets the CAPE-OPEN component description for this unit operation.

C#VB.NET

public override string ComponentDescription { get; set; }

Public Overrides Property ComponentDescription As String

Config: Gets or sets the configuration of this Claus sulfur recovery unit: the operating temperature and pressure, sulfur...

Gets or sets the configuration of this Claus sulfur recovery unit: the operating temperature and pressure, sulfur recovery fraction, heat release per mole of H2S, and the names of the H2S, sulfur surrogate, water and oxygen compounds.

C#VB.NET

public ClausConfiguration Config { get; set; }

Public Property Config As ClausConfiguration

IsRefining: Gets a value indicating that this unit operation belongs to the refining group.

Gets a value indicating that this unit operation belongs to the refining group. Always true; the object palette uses it to list the unit under the Refinery category.

C#VB.NET

public bool IsRefining { get; }

Public ReadOnly Property IsRefining 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. Always false.

C#VB.NET

public override bool MobileCompatible { get; }

Public Overrides ReadOnly Property MobileCompatible As Boolean

ObjectClass: Gets the simulation object class category (Reactors).

Gets the simulation object class category (Reactors).

C#VB.NET

public override SimulationObjectClass ObjectClass { get; }

Public Overrides Property ObjectClass As SimulationObjectClass

Prefix: Gets the default name prefix for this unit operation ('SRU-').

Gets the default name prefix for this unit operation ("SRU-").

C#VB.NET

public string Prefix { get; }

Public ReadOnly Property Prefix As String

Methods¶

Calculate(object): Calculates the object.

Calculates the object.

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 of this object by round-tripping through XML serialization.

Creates a deep copy of this object by round-tripping through XML serialization.

C#VB.NET

public override object CloneXML()

Public Overrides Function CloneXML() As Object

CloseEditForm(): Closes the editor of this object, if it is open.

Closes the editor of this object, if it is open.

C#VB.NET

public override void CloseEditForm()

Public Overrides Sub CloseEditForm()

CreateConnectors(): Creates the graphic connector definitions on the flowsheet: two inlets (Acid Gas and Combustion Air) on the left...

Creates the graphic connector definitions on the flowsheet: two inlets (Acid Gas and Combustion Air) on the left, two outlets (Sulfur and Tail Gas) on the right, and a Waste Heat energy outlet.

C#VB.NET

public void CreateConnectors()

Public Sub CreateConnectors()

DeCalculate(): Decalculates the object.

Decalculates the object.

C#VB.NET

public override void DeCalculate()

Public Overrides Sub DeCalculate()

DisplayEditForm(): Opens the editor of this object.

Opens the editor of this object. A host that has no editor for it does nothing.

C#VB.NET

public override void DisplayEditForm()

Public Overrides Sub DisplayEditForm()

Draw(object): Draws the unit operation icon on the given SkiaSharp canvas.

Draws the unit operation icon on the given SkiaSharp canvas. Draw mode 2 uses the embedded PNG image (falling back to the vector icon if it cannot be loaded), draw mode 1 draws the vector icon as a silhouette, and other modes draw the vector icon.

Parameter	Type	Description
`g`	`Object`	The SkiaSharp canvas (`SKCanvas`).

C#VB.NET

public void Draw(object g)

Public Sub Draw(g As Object)

GetDisplayDescription(): Returns the description string for this unit operation type.

Returns the description string for this unit operation type.

C#VB.NET

public override string GetDisplayDescription()

Public Overrides Function GetDisplayDescription() As String

GetDisplayName(): Returns the display name for this unit operation type.

Returns the display name for this unit operation type.

C#VB.NET

public override string GetDisplayName()

Public Overrides Function GetDisplayName() As String

GetIconBitmapBytes(): Returns the raw bytes of the icon image for this unit operation, rendered from the vector icon at 64 x 64 pixels.

Returns the raw bytes of the icon image for this unit operation, rendered from the vector icon at 64 x 64 pixels.

C#VB.NET

public override byte[] GetIconBitmapBytes()

Public Overrides Function GetIconBitmapBytes() As Byte()

GetPreferredGraphicObjectHeight(): Returns the preferred height of the flowsheet graphic object, in pixels.

Returns the preferred height of the flowsheet graphic object, in pixels.

C#VB.NET

public override double GetPreferredGraphicObjectHeight()

Public Overrides Function GetPreferredGraphicObjectHeight() As Double

GetPreferredGraphicObjectWidth(): Returns the preferred width of the flowsheet graphic object, in pixels.

Returns the preferred width of the flowsheet graphic object, in pixels.

C#VB.NET

public override double GetPreferredGraphicObjectWidth()

Public Overrides Function GetPreferredGraphicObjectWidth() As Double

GetProperties(PropertyType): Get a list of all properties of the object.

Get a list of all properties of the object.

Parameter	Type	Description
`proptype`	`PropertyType`	Type of the property.

C#VB.NET

public override string[] GetProperties(PropertyType proptype)

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

GetPropertyUnit(string, IUnitsOfMeasure): Gets the units of a property.

Gets the units of a property.

Parameter	Type	Description
`prop`	`String`	Property identifier.
`su`	`IUnitsOfMeasure`	Units system to use. Null to use the default (SI) system.

C#VB.NET

public override string GetPropertyUnit(string prop, IUnitsOfMeasure su)

Public Overrides Function GetPropertyUnit(prop As String, su As IUnitsOfMeasure) As String

GetPropertyValue(string, IUnitsOfMeasure): Returns the value of a named property, converting from SI to the current unit system.

Returns the value of a named property, converting from SI to the current unit system. Falls back to extra properties if the property is not found in the base implementation.

Parameter	Type	Description
`prop`	`String`	The property identifier string.
`su`	`IUnitsOfMeasure`	Optional units-of-measure system used for conversion; uses the shared SI system when `Nothing`.

C#VB.NET

public override object GetPropertyValue(string prop, IUnitsOfMeasure su)

Public Overrides Function GetPropertyValue(prop As String, su As IUnitsOfMeasure) As Object

LoadData(List<XElement>): Restores the unit operation state from a list of XML elements previously produced by SaveData.

Restores the unit operation state from a list of XML elements previously produced by SaveData.

Parameter	Type	Description
`data`	`List<XElement>`	The list of `XElement` objects containing serialized state.

C#VB.NET

public override bool LoadData(List<XElement> data)

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

PopulateEditorPanel(object): Populates the cross-platform (Avalonia) editor panel with controls: buttons that open the configuration and results...

Populates the cross-platform (Avalonia) editor panel with controls: buttons that open the configuration and results forms. Other container types are ignored.

Parameter	Type	Description
`ctner`	`Object`	The editor panel (layout container) to populate.

C#VB.NET

public void PopulateEditorPanel(object ctner)

Public Sub PopulateEditorPanel(ctner As Object)

ReturnInstance(string): Creates and returns a new instance for deserialization.

Creates and returns a new instance for deserialization.

Parameter	Type	Description
`typename`	`String`	The type name to instantiate (not used).

C#VB.NET

public object ReturnInstance(string typename)

Public Function ReturnInstance(typename As String) As Object

SaveData(): Serializes the unit operation state to a list of XML elements for persistence.

Serializes the unit operation state to a list of XML elements for persistence.

C#VB.NET

public override List<XElement> SaveData()

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

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

Sets the value of a property.

Parameter	Type	Description
`prop`	`String`	Property identifier.
`propval`	`Object`	Property value to set at the specified units.
`su`	`IUnitsOfMeasure`	Units system to use. Null to use the default (SI) system.

C#VB.NET

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

Public Overrides Function SetPropertyValue(prop As String, propval As Object, su As IUnitsOfMeasure) As Boolean

UpdateEditForm(): Redraws the editor of this object with the current values, if it is open.

Redraws the editor of this object with the current values, if it is open.

C#VB.NET

public override void UpdateEditForm()

Public Overrides Sub UpdateEditForm()

Fields¶

_editorForm: 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 FormEditorClaus _editorForm

Public _editorForm As FormEditorClaus