Plant Model - Species

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Navigation: User Guide ➔ View ➔ Plant Model ➔ Species

FlwSolve Tab Settings Tab Audit Tab Project Tab RC Tab Species Tab Views Tab Soluble Tab WaterQuality Tab Qualities Tab
Environment Tab System Tab ModelList Tab Flowsheets Tab PrjNetworks Tab Status Tab Statistics Tab States Tab EvalSeq Tab Globals Tab

This page is for Build 137 or later. For Build 136, please see Plant Model 9.3 - Species.


Introduction

This tab page on the Plant Model Access Window has a number of parameters that the user may either set or read for Global settings.

Tag (Long/Short) Input / Calc / Options Description/Calculated Variables

Calculation Methods

TreatWaterAsAq Display Only available in Build 136. This displays whether the Recognise H2O(l) As Aqueous option has been selected in the Project's Configuration File or not. The default for this is Yes.
Enthalpy Strategy Best_Temperature The method used for energy balance when mixing streams with different properties models that may have different stream enthalpy calculations. Attempt to maintain temperature, adjust enthalpy. Use the outgoing properties enthalpy model when mixing streams. Note that in this case, the enthalpy of the outgoing stream may not be equal to the sum of the incoming stream enthalpies. When mixing two streams of the same temperature, the outgoing temperature will be equal to incoming temperature provided there is no concentration dependence of the enthalpy function.
Conserve_Heat The method used for energy balance when mixing streams with different properties models that may have different stream enthalpy calculations. Maintain enthalpy, adjust temperature. In this case the enthalpy of the outgoing stream is guaranteed to equal to the sum of the incoming stream enthalpies.
SaturationCmp H2O By default the saturation component used in any VLE blocks will be H2O. The user can override this in the individual VLE block.
All - H2O The saturation component used in all VLE blocks will be H2O, the user cannot override this in the individual VLE block.
component X By default the saturation component used in any VLE blocks will be component X (any component which is available for VLE). The user can override this in the individual VLE block.
All - component X The saturation component used in all VLE blocks will be component X (any component which is available for VLE), the user cannot override this in the individual VLE block.
DefaultSpModel Display This displays the default species model as selected in the Project's Configuration File.

Species Property Overrides

SysCAD has a number of different options that the user can select to calculate the properties of water and steam:

  • The default option is to use the IF97 method. This provides accurate simulation results involving steam and water. SysCAD 9.3 includes improved equations for steam in Region 5.
  • The Low Fidelity steam/water equations are much faster. The low fidelity correlations match IF97 closely for models where temperatures and pressures are appropriate. However, there is a significant speed improvement when using the Low Fidelity methods.
  • The Simple equations are less accurate, but suitable for low temperature projects that do not require high accuracy for steam/water calculation.
Species Property Overrides - Liquids
H2O(l).Rho None The default method will be used to calculate the water density. This is IF97.
IF97 The industrial standard IAPWS-IF97 equation will be used for the water density calculation. The default equation.
LowFid The Low Fidelity equation will be used for the water density calculation.
Simple Simple Water equation will be used for the water density calculation.
H2O(l).Cp None The default method will be used to calculate the water specific heat. This is IF97.
IF97 The industrial standard IAPWS-IF97 equation will be used for the water heat capacity calculation. (The default equation.)
LowFid The Low Fidelity equation will be used for the water heat capacity calculation.
Simple The Simple Water equation will be used for the water heat capacity calculation.
H2SO4(aq).Cp None The default equation (KWA) will be used for the sulfuric acid heat capacity calculation.
Fasullo The Fasullo equation will be used for the sulfuric acid heat capacity calculation.
KWA A constant heat capacity estimated by Kenwalt will be used for the sulfuric acid heat capacity calculation.
Zaytsev The Zaytsev equation will be used for the sulfuric acid heat capacity calculation.
Species Property Overrides - Vapours
H2O(g).Rho None The default method will be used to calculate the steam density. This is IF97.
IF97

For Build136 to Build138:

  • IF97 - (SysCAD 9.2 version) - The industrial standard IAPWS-IF97 equation will be used for the steam density calculation. (The default equation.)
  • IF97_2 - (Improved equations in Region 5) - The industrial standard IAPWS-IF97 equation will be used for the steam density calculation, with improved equations in Region 5.

For Build139:

  • IF97 - (SysCAD 9.3 Build139 version including improved equations in Region 5) - The industrial standard IAPWS-IF97 equation will be used for the steam density calculation. (The default equation.)
LowFid Low Fidelity correlations will be used for the steam density calculation.
Simple The Simple equation will be used for the steam density calculation.
H2O(g).Cp None The default method will be used to calculate the steam heat capacity. This is IF97.
IF97

For Build136 to Build138:

  • IF97 - (SysCAD 9.2 version) - The industrial standard IAPWS-IF97 equation will be used for the steam heat capacity calculation. (The default equation.)
  • IF97_2 - (Improved equations in Region 5) - The industrial standard IAPWS-IF97 equation will be used for the steam heat capacity calculation, with improved equations in Region 5.

For Build139:

  • IF97 - (SysCAD 9.3 Build139 version including improved equations in Region 5) - The industrial standard IAPWS-IF97 equation will be used for the steam heat capacity calculation. (The default equation.)
LowFid Low Fidelity correlations will be used for the steam heat capacity calculation.
Simple The Simple equation will be used for the steam heat capacity calculation.

Water properties below 0C

Reference: “Smith, Van Ness, Abbott – “Introduction to Chemical Engineering Thermodynamics", 5th Ed, 1996”

H2O(l).UseNewLowT.Cp Tickbox Implemented in Build 139.
  • If this option is selected, then water Cp between 235K and 273.15K are based on Reference given above. For temperatures below 235K (-38.15°C), data is extrapolated.
  • If this option is not selected, then water Cp is extrapolated below 0°C. (This is original method used in Build138 and earlier, retained here for backward compatibility purposes.)
  • This options is auto selected for any new project or existing project with a minimum temperature >0°C.
  • For projects with below 0°C temperatures, user can check this option to improve the accuracy of the enthalpy values between 235K and 273.15K.
    • If this option is not selected, a warning is given in Message Window - Project settings Tab: PlantModel - Using old Water Cp extrapolation below 0C. Review 'PlantModel.H2O(l).UseNewLowT.Cp.
H2O(l).UseNewLowT.Rho Tickbox Implemented in Build 139.
  • If this option is selected, then water density between 235K and 273.15K are based on Reference given above. For temperatures below 235K (-38.15°C), data is extrapolated.
  • If this option is not selected, then water density is extrapolated below 0°C. (This is original method used in Build138 and earlier, retained here for backward compatibility purposes.)
  • This options is auto selected for any new project or existing project with a minimum temperature >0°C.
  • For projects with below 0°C temperatures, user can check this option to improve the accuracy of the density values between 235K and 273.15K.
    • If this option is not selected, a warning is given in Message Window - Project settings Tab: PlantModel - Using old Water Density extrapolation below 0C. Review PlantModel.H2O(l).UseNewLowT.Rho.

Auto Phase Change Equilibrium

PhaseChange@T Off Phase change at Temperature will NOT occur automatically. This will be the default (and greyed out) if there is no function defined in the species database.
On Phase change at Temperature will occur automatically throughout the project for all species with defined Phase change at Temperature functions in the species database. Please see Phase Change in Species Database for further details.
(An example of this is Hematite (Fe2O3(s)) changing automatically from the alpha to the beta form at 427oC.)
Do not use this with the FEM model if phases are present, it may for example convert molten liquids (which are stable in a mixture below the melting point) into solids
PhaseChange@MF Off Phase change at Mass Fraction will NOT occur automatically. This will be the default (and greyed out) if there is no function defined in the species database.
On Phase change at Mass Fraction will occur automatically throughout the project for all species with defined Phase change at Mass Fraction functions in the species database. Please see Phase Change in Species Database for further details.
(An example of this is H2SO4 changing automatically from the liquid to the aqueous phase at 98.3% acid)
AutoVLE Off Automatic vapour-liquid equilibrium (VLE) will NOT occur automatically. This is the default setting for all upgraded and new projects.
On Automatic vapour-liquid equilibrium (VLE) will be enabled in all pipes. The calculations will use the default Saturation species for the calculations. See Vapour Liquid Equilibrium (VLE) for further details.

Standard Properties SpModel Options

DensityCorrection FracInSolventOnly The density correction calculations use the mass fraction of individual species in the solvent ONLY. The resulting density of the solution will be HIGHER than using the method below, because the correction factor is greater. Please see Density Correction Methods for a more detailed description.
FracInAqueousSoln The density correction calculations use the mass fraction of the individual species in the TOTAL aqueous solution. The resulting density of the solution will be LOWER than using the method above, because the correction factor is smaller. Please see Density Correction Methods for a more detailed description.
Note: This method is only valid if the solvent is Water.
BPE_Method None No Boiling Point Elevation (BPE) calculations will be performed, i.e. BPE = 0°C in all streams with the Standard Species Model.
VantHoff The BPE will be calculated using the equation shown in Boiling Point Elevation and the van't Hoff constants as entered in the Species Database.
BPE_LoLimit Input The lower limit for the BPE calculations - usually 0°C.
BPE_HiLimit Input The upper limit for the BPE calculations - the default is 20°C, but if the project has concentrated solutions the upper limit may need to be higher.

Species Count

SpeciesCountDetails / SpCountDetails Display The Species Properties ($SDB) tag for total species count.
SpeciesCount / SpCount Display The total number of species in the project.
SpeciesSolCount / SpSolCount Display The number of solid species in the project.
SpeciesLiqCount / SpLiqCount Display The number of liquid species in the project.
SpeciesVapCount / SpVapCount Display The number of vapour or gas species in the project.

SpUse (Species Use)

This section is only available in Build139 or later. After the project is solved, the list of species used by the project (has flow) can be reported here. User can also copy the list to clipboard for reporting purposes.
User should check this list prior to removing a species from the project configuration file to ensure a species with flow is not removed by mistake.

SpeciesInUse Report Button Clicking on this button will bring up the following options:

Speciesused139.png

  1. Clipboard: Unused - The list of unused species will be added to the clipboard. User can paste the contents of the clipboard in another application such as MS Excel for reporting purposes.
  2. Clipboard: Used - The list of the used species, use count, maximum flow in the project etc will be added to the clipboard. User can paste the contents of the clipboard in another application such as MS Excel for reporting purposes.
  3. Clipboard: All - The list of all species, use count, maximum flow in the project etc will be added to the clipboard. User can paste the contents of the clipboard in another application such as MS Excel for reporting purposes.
  4. Message: Unused - The list of unused species will be added to the message window.
  5. Message: Used - The list of the used species, use count, maximum flow in the project etc will be added to the message window.
  6. Message: All - The list of all species, use count, maximum flow in the project etc will be added to the message window.
TestOnStop Tickbox If this option is ticked, the species used table will be displayed on the bottom of the page. The values will be updated when the SysCAD solver stops or when the "Refresh Now" button is pressed.
SearchCount Display The number of unit operation searched in generating the species used table.
SpFlowCount Display The number of species used by the project (with flow).
SpNoFlowCount Display The number of species not used by the project (with no flow).
The species used table will be displayed here, each species present in the project will be added as a row. The column headings are described below:
Count column heading The species has flow in this number of unit operations (eg: pipes, contents).
MaxQm column heading The species has shown a maximum flow in this unit operations (tag name shown in Max Tag column).
MaxTag column heading The species has shown a maximum flow (flow shown in the MaxQm column) in this unit operations.
Species X row heading Each species present in the project will be added as a new row.