Reaction Block (RB)

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Navigation: Main Page -> Models -> Sub-Models

Reaction Format Reaction Block (RB) Sub Model Heat of Reaction
Reaction Editor Text File Format Reaction Block (RB) Summary Solving Order - Sequential or Simultaneous Reaction Extents Individual Reactions Source /Sink /Heat Exchange Energy Balance Heat of Reaction Heat of Dilution Partial Pressures of Gases

General Description

Many SysCAD models have the facility to allow the user to enable chemical reactions in the unit. If a unit has this facility, the first access window will have a field called 'Reactions'.

To enable the reactions, change the status of the field from 'Off' to 'On-AutoSequence' and SysCAD creates a reaction block for the model.

  • If the Reaction Block is part of an Evaluation Block (EB) then the user may change the evaluation sequence relative to other sub-models by selecting On-Sequence1, On-Sequence2, etc. (refer to Evaluation Block for more information).

In dynamic mode, units which have the facility for surge may allow reactions as part of a Content Evaluation Block (CEB). This allows the user to have the reactions occur on the content or surge of the unit and is referred to as a Content Reaction Block (CRB).

Once reactions are switched 'On', an RB or CRB tab will appear as shown below.

The user may then access the RB tab and click on the 'Edit_RCT' button, as shown below:

Edit Reactions.png


SysCAD will start the reaction editor (The editor used by SysCAD will have been set in the Tools/General Options/Global tab page. See Reaction Editor) to edit a text file, with the extension .rct. The reaction file will have the same name as the unit - in the case shown here it will be called 'Neutralisation.rct'.

This file is read into the unit and SysCAD solves the reactions.

Location of Reaction Files

  • All reaction files used in a project must be stored within the project in a folder called Reactions.
  • SysCAD automatically creates this folder when you start a new project or upgrade an older project to SysCAD 9.2.
  • You may check the location and names of all reaction files in a project by accessing the Project Window - Files List.

Video Links

  • Turn on Reactions in a Unit - this short video in the Tutorial section shows you how to turn on Reactions in a unit.
  • Reaction Troubleshooting - this short video in the Tutorial section gives a brief example of reaction troubleshooting.
  • Reaction Information - this short video in the Tutorial section explains some of the information available for each Reaction in a Reaction Block.

Solving Reactions

Reactions within a single reaction block may be solved sequentially or simultaneously. By default the reactions will be solved sequentially, which is the recommended method. Please refer to Solving Reactions for more information.

Reaction File Format

Chemical reactions are defined in a text file.

The recommended method of editing reaction files is to use the SysCAD Reaction Editor. However, any text editor can be used to edit or view these reactions (see Reaction File (RCT) Text Format). The reaction filename must have the extension .rct.

NOTE: The reaction file must contain at least one reaction. Sources, sinks and heat exchange can not be used in isolation without at least one reaction.

Reaction Block Options and Features

  • A reaction may proceed in the forward direction only, or may be a reversible reaction, refer to Reaction Directions for more information.
  • There several methods for specifying the extent of each reaction, refer to Reaction Block - Extents for more information.
  • Reactions are solved sequentially (recommended for speed) or simultaneously, based on the sequence number set by the user. Refer to Sequential and Simultaneous Reactions for more information.
  • A reaction block can optionally have sources and/or sinks of species. Refer to Reaction Block - Other for more information.

Data Sections

A description of the variables on the Reaction Block access pages is given here.

  • RB - When the user adds a reaction block to a unit, SysCAD creates the RB tab. This tab contains a summary of the reaction conditions.
  • RS - Displays the reactions in a summary table. User can select to display more or less fields.
  • Individual Reactions - When a reaction file is loaded into the unit, SysCAD creates at least one additional tab, R1. Depending on the number of reactions specified within the reaction file, there may be more than one of these tabs. The additional sections will be numbered Rn, where n is the number of the first reaction on that page. For example, if the reaction file contains 5 reactions, the first 3 may appear on the R1 page, then the next page will be labelled R4.
  • Source (Src) - This tab will be visible if the user adds a Source in the reaction file. This will display all of the fields relating to the Source species.
  • Sink (Snk) - This tab will be visible if the user adds a Sink in the reaction file. This will display all of the fields relating to the Sink species.
  • Heat Exchange (RHX) - This tab will be visible if the user adds a Heat Exchange in the reaction file. This will display all of the fields relating to the Heat Exchange configuration.

RB Section

Tag (Long/Short) Input / Calc / Options Description
RB...
Reaction Block
On Tick Box Used to enable the reaction file. The default is On.
RCT_Name Input The user may type in the name of the required reaction file, or if the user leaves this field Blank and clicks on the Edit_RCT button, SysCAD will create a reaction file with the same name as the unit.
RCT_Path / RCT_Folder Display The full path of the folder which contains the reaction file is displayed here.
AutoReload Tick Box This enables the automatic reloading of the reaction file if it has been changed. The user then does not have to click on the 'ReLoad' button each time a change is made to the reaction file.
LoadState Display A number of possibilities exist here. Before a reaction file is entered, this field will state 'No Reactions'. Once the reaction file is entered it will have either 'OK', if all is well, or an error message if there is a problem. The message will depend on the error.
Error Display If there is an error with the RCT file, this will give the line number of the error, and a brief message describing the error.
Edit_RCT Button Opens the reaction file in the editor defined in the General Options (Please see Setting the Reaction Editor for more information on selecting the editor. The default editor is Notepad, but we recommend using the SysCAD Reaction Editor).
Reload_RCT Button Manually reloads the reaction file after changes are made.
Browse_RCT Button The user can browse for the reaction file by clicking on this button.
Notes Input The user may type in notes related to the reactions. This field can be accessed in the same way as all other fields, i.e. it may be added to Excel reports, to be read or set.
Settings
ExtentType
This list box allows the user to set the error tracking methods for the current RB block.
Notes:
1. If the user wants to set the options for individual reactions, select either of the two options, Strict or Target, and then set the desired option for each reaction in the Extent.Type field.
2. For simultaneous reactions, the user should change this to All_Target.
All_Strict Error tracking is switched on and ALL reactions in this Reaction Block will be tracked.
All_Target Error tracking is switched off for ALL reactions in this Reaction Block.
Strict Error tracking can be switched on or off for each individual reaction. The default for reactions in this Reaction Block will be on.
Target Error tracking can be switched on or off for each individual reaction. The default for reactions in this Reaction Block will be off.
LimitAmountReacted
(Only available in Build 137 or later)
This list box allows the user to limit the amount of the extent species reacted for each individual reaction.
Depending on the option chosen, additional input fields will be available for each individual reaction.
Off There are no limits on the amount reacted.
AsMass - Fwd & Rev The user can limit the mass reacted of the extent species in both the forward and reverse directions.
AsMass - Forward The user can limit the mass reacted of the extent species in the forward direction only.
AsMass - Reverse The user can limit the mass reacted of the extent species in the reverse direction only.
AsMoles - Fwd & Rev The user can limit the moles reacted of the extent species in both the forward and reverse directions.
AsMoles - Forward The user can limit the moles reacted of the extent species in the forward direction only.
AsMoles - Reverse The user can limit the moles reacted of the extent species in the reverse direction only.
LimitFractionReacted
(Only available in Build 137 or later)
This list box allows the user to limit the fraction of the extent species reacted for each individual reaction.
Depending on the option chosen, additional input fields will be available for each individual reaction.
Off There are no limits on the amount reacted.
Fwd & Rev The user can limit the fraction reacted of the extent species in both the forward and reverse directions.
Forward The user can limit the fraction reacted of the extent species in the forward direction only.
Reverse The user can limit the fraction reacted of the extent species in the reverse direction only.
StandardSpModel Tick Box If user is using a non-standard species model, e.g. Bayer model, then selecting this box will force the reaction block to calculate values using the Standard Species Model. (If the user IS using the Standard Model, then this will have no effect)
OverrideHtDil Tick Box If this option is enabled then the reaction energy will NOT include any Heat of Dilution effects (this is NOT recommended), ie. the reactions will not take any dilution or concentrating effects into account. This is only relevant IF the project includes any species that have Heat of Dilution data entered in the database. See Heat of Dilution in Reaction Energy Calculations for more information.
OverridePP Tick Box If this is enabled then user can choose the Partial Pressure override method used when calculating the enthalpy of gaseous species used in the reaction block energy calculations. If this is disabled, then the reaction calculations are carried out using the feed partial pressure to calculate the enthalpy of gaseous species. This is only relevant if Steam and other gases are present in the Reaction Block. See Partial Pressure of Gases in Reaction Energy Calculations for more information. If this is enabled an additional group of RB.VapourHf tags will be visible.
VapourHf.Method
(Only visible in this location in Build 137 or later)
Only visible if the OverridePP option has been selected. There are several methods available to the user for calculating/setting the partial pressure used when calculating the enthalpy of gaseous species to be used in the reaction block calculations. Use of the different methods will not change the amount of material reacted or the final temperature of the stream. It will only change where the energy is reported between the HOR for an individual reaction and the Work term. Refer to Partial Pressure of Gases in Reaction Energy Calculations for more information.
TotalPressure The partial pressure used will be the total feed pressure.
FeedPP The partial pressure used will be the feed partial pressure (this is identical to not using the Partial Pressure Override).
ProductPP The partial pressure used will be the product partial pressure.
EnviroPPFrac The partial pressure used will be the environmental fraction of the gas (as defined on the Plant Model-Environment page) multiplied by the total pressure.
UserDefinedPPFrac The partial pressure used will be the user defined fraction of the gas multiplied by the total pressure.
UserDefinedPP The partial pressure used will be the user defined partial pressure.
IgnoreLockup Tick Box This option allows the user to ignore the LockUp functionality, if it has been enabled. Normally, lockup is specifically enabled so that the 'locked up' portion of a species will NOT react. However, it can also be used to emulate a portion of a species as some quality, such as Fines, or orginating from a different source. In this case, the user may require the locked up portion to react, in which case this 'Ignore Lockup' tickbox must be enabled.
OverrideProductT Tick Box This option is recommended if the final temperature from the RB block is set by the user. The overall Energy Balance of the model is maintained and reported in the overall Energy Balance on the first RB tab page and on the Audit page. See Override Product Temperature Option for more information.
Selecting this option results in fewer computations in SysCAD and hence increases the solver speed. The HOR of individual reactions does not need to be calculated and is not shown.
If this option is enabled an additional group of RB.ProductTemp tags will be visible.
ProductTemp... These fields are only visible if the OverrideProductT option has been selected.
Method FeedT The feed temperature will be maintained.
DeltaT The product temperature = Feed temperature + DeltaT.
UserT The product temperature is forced to a user specified value.
ConstHf No external energy will be added. From a temperature and overall energy view, this is equivalent to not using the OverrideProductT option, but due to less required calculations, it is faster.
Reqd.DeltaTemp / DeltaT_Reqd Input This field is only visible if the DeltaT method is selected. This is the user specified required temperature difference between the RB feed and RB product temperatures. A positive number indicates an increase in temperature while a negative number indicates a decrease in temperature.
Reqd.UserTemp / UserT_Reqd Input This field is only visible if the UserT method is selected. This is the user specified required product temperature.
UsrDefT Input This field is only visible if the EnergyInfo list box is set to User Defined Info or All Energy Info.
The user defined temperature for the reactions. The default is 25°C. This temperature is for display purposes only, it does not affect the calculated results. The displayed values affected will be under Tag.RB.dH@UsrDef fields and the xxxx.@UsrDef fields under each individual reaction.
UsrDefP Input This field is only visible if the EnergyInfo list box is set to User Defined Info or All Energy Info.
The user defined Pressure for the reactions. The default is atmospheric. This pressure is for display purposes only, it does not affect the calculated results. The displayed values affected will be under Tag.RB.dH@UsrDef fields and the xxxx.@UsrDef fields under each individual reaction.
Display Extra Information
The following three fields allow the user to display or remove additional information for each individual reaction and, in some cases, for the overall reaction block.
These options apply individually in each reaction block in the project.
EnergyInfo
This field is NOT visible if the OverrideProductT option has been selected.
Please also see Display Additional Reaction Information
Basic Info Only No additional energy values will be displayed.
User Defined Info Overall and individual reaction energy values (such as heat of reaction) are displayed at a User Defined temperature and pressure (@UsrDef).
Feed Info Overall and individual reaction energy values (such as heat of reaction) are displayed at Feed temperature and pressure (@Fd).
Product Info Overall and individual reaction energy values (such as heat of reaction) are displayed at Product temperature and pressure (@Pr).
Feed & Product Info Overall and individual reaction energy values (such as heat of reaction) are displayed at Feed and Product temperature and pressure (@Pr).
Reference Info Overall and individual reaction energy values (such as heat of reaction) are displayed at the reference temperature (0°C) and pressure (101.325 kPa) (@Ref).
All Energy Info Overall and individual reaction energy values (such as heat of reaction) are displayed at all four sets of temperatures and pressures defined above.
SpChangeInfo
Please also see Display Additional Reaction Information
Basic Info Only The mass and molar change for only a single species (the 'report' species) will be displayed for each individual reaction. This is normally the 1st reactant species. However, if the user overrides the Heat of Reaction, then the report species is always the species for which the user Heat of Reaction is specified.
All Species - Mass Extra fields will be displayed for each individual reaction, showing the Mass change for all reactant and product species.
All Species - Molar Extra fields will be displayed for each individual reaction, showing the Molar change for all reactant and product species.
All Species - Both Extra fields will be displayed for each individual reaction, showing both the Mass and Molar change for all reactant and product species.
SummaryTableInfo
(Only available in Build 137 or later.)
Adds RS tab page.
Basic All reactions will be listed in a summary table, fields displayed are: Reaction Number, Reaction On/Off, Reaction
Extent All reactions will be listed in a summary table, fields displayed are: Reaction Number, Reaction On/Off, Reaction Extent Required, Reaction Extent Achieved, Reaction, Reaction Extent Description.
Extent,Transfer All reactions will be listed in a summary table, fields displayed are: Reaction Number, Reaction On/Off, Reaction Extent Required, Reaction Extent Achieved, Mass Reacted (of Xfer report species), Reaction, Reaction Extent Description.
Extent,Energy All reactions will be listed in a summary table, fields displayed are: Reaction Number, Reaction On/Off, Reaction Extent Required, Reaction Extent Achieved, Energy Change (HsGain) @ 0°C, Reaction, Reaction Extent Description.
Transfer All reactions will be listed in a summary table, fields displayed are: Reaction Number, Reaction On/Off, Mass Reacted (of Xfer report species), Reaction
Transfer,Energy All reactions will be listed in a summary table, fields displayed are: Reaction Number, Reaction On/Off, Mass Reacted (of Xfer report species), Energy Change (HsGain) @ 0°C, Reaction
All All reactions will be listed in a summary table, fields displayed are: Reaction Number, Reaction On/Off, Reaction Extent Required, Reaction Extent Achieved, Mass Reacted (of Xfer report species), Energy Change (HsGain) @ 0°C, Reaction, Reaction Extent Description.
ShowReactionLimits
(Only available in Build 137 or later)
Tick Box If this is enabled, then each individual reaction will display additional information about the maximum mass and molar changes that are possible with the reaction in the forward and reverse directions, based on the available amounts of reaction species.
ShowSpRequirements
(Only available in Build 137 or later.)
Please also see Display Additional Reaction Information
Off No additional displays.
AsMass - All Extra fields will be displayed for each individual reaction and overall, showing the Mass required for all reactant and product species to meet the required extent.
AsMass - Select Extra fields will be displayed for each individual reaction and overall, showing the Mass required for selected species to meet the required extent.
AsMoles - All Extra fields will be displayed for each individual reaction and overall, showing the Moles required for all reactant and product species to meet the required extent.
AsMoles - Select Extra fields will be displayed for each individual reaction and overall, showing the Moles required for selected species to meet the required extent.
AsBoth - All Extra fields will be displayed for each individual reaction and overall, showing both the Mass and Moles required for all reactant and product species to meet the required extent.
AsBoth - Select Extra fields will be displayed for each individual reaction and overall, showing both the Mass and Moles required for selected species to meet the required extent.
Sp0X List Only visible if one of the ShowSpRequirements Select methods has been chosen. X is the number of the selected species. Select the required species from the list. There will usually be one extra to allow another species to be added. To remove a species, choose the “-” option instead of the selected species.
ReactionDisplaySigDig Input This is a global setting. It allows the user to set the maximum number of significant digits displayed in the reaction line. This is only for display purposes, it will not affect the elemental balance internally.

For example: if ReactionDisplaySigDig = 5, then for reaction:

1 CaCO3(s) + 4/3 NaOH(aq) + 2/3 NaAl[OH]4(aq) = 1/3 3CaO.Al2O3.6H2O(s) + 1 Na2CO3(aq)

The RB.R1.Reaction filed will display:

CaCO3(s) + 1.3333 NaOH(aq) + 0.66667 NaAl[OH]4(aq) <=> 0.33333 3CaO.Al2O3.6H2O(s) + Na2CO3(aq)
ShowReactionSummary
Please also see All Available Reaction Information
Tick Box If this is enabled, then each individual reaction for ALL reaction blocks in the project will display additional information about the Mass and Molar changes associated with the species in that reaction.
RB Solver Settings
AllowStartAtPrevious Tick Box The solver will start the reaction convergence at the previous value.
The following 6 fields are only available in Build 136 or earlier. In Build 137 they have been replaced with otherRB Solver Settings tags which are shown underneath.
ExtentAbsTol Input The convergence absolute tolerance for the reaction solver for each reactions reacted moles to achieve reaction extents. Generally, the user should not have to alter this value.
CnvTolerance / ExtentRelTol Input The convergence relative tolerance for the reaction solver for each reactions reacted moles to achieve reaction extents. Generally, the user should not have to alter this value. For extent type FinalConc the user may need to tighten the tolerance (decrease the value) to more accurately achieve desired concentration. If the solution is difficult, the user may set this to a larger number to improve the speed of the solution.
The tolerance for condition warnings for extent not achieved is set globally in Tolerances for RB.ExtentTest.
MaxIters Input The maximum number of iterations of the reaction solver.
CnvTTolerance / TempAbsTol Input The convergence absolute tolerance for the temperature solver. Generally, the user should not have to alter this value. However, if the solution is difficult, the user may set this to a larger number to improve the speed of the solution.
MaxTIters Input The maximum number of iterations of the temperature solver.
MaxHXIters Input The maximum number of iterations of the HX solver.
UsrDefT
(Only visible in this location in Build 136 or earlier)
Input This field is only visible if the EnergyInfo list box is set to User Defined Info or All Energy Info.
The user defined temperature for the reactions. The default is 25°C. This temperature is for display purposes only, it does not affect the calculated results. The displayed values affected will be under Tag.RB.dH@UsrDef fields and the xxxx.@UsrDef fields under each individual reaction.
UsrDefP
(Only visible in this location in Build 136 or earlier)
Input This field is only visible if the EnergyInfo list box is set to User Defined Info or All Energy Info.
The user defined Pressure for the reactions. The default is atmospheric. This pressure is for display purposes only, it does not affect the calculated results. The displayed values affected will be under Tag.RB.dH@UsrDef fields and the xxxx.@UsrDef fields under each individual reaction.
The following group of fields are only available in Build 137 or later.
Extent.Iters.Max Input The maximum number of iterations for the reaction extent solver.
Blocks.Iters.Max Input The maximum number of iterations for the simultaneous reaction solver.
Mass.Iters.Max Input The maximum number of iterations for the transfer mass/source/recycle solver.
HeatXchg.Iters.Max Input The maximum number of iterations for the heat exchange solver.
Temperature.Iters.Max Input The maximum number of iterations for the temperature solver.
Extent.Tol.SigDigits Input Convergence relative tolerance for the reaction extent solver in the form of Significant Digits. SigDigits = -log(Tol.Rel).
Blocks.Tol.SigDigits Input Convergence relative tolerance for the simultaneous reaction solver in the form of Significant Digits. SigDigits = -log(Tol.Rel).
Mass.Tol.SigDigits Input Convergence relative tolerance for the transfer mass/source/recycle solver in the form of Significant Digits. SigDigits = -log(Tol.Rel).
HeatXchg.Tol.SigDigits Input Convergence relative tolerance for the heat exchange solver in the form of Significant Digits. SigDigits = -log(Tol.Rel).
Temperature.Tol.SigDigits Input Convergence relative tolerance for the temperature solver in the form of Significant Digits. SigDigits = -log(Tol.Rel).
Extent.Tol.Rel Input The convergence relative tolerance for the reaction extent solver. Generally, the user should not have to alter this value. If the solution is difficult, the user may set this to a larger number to improve the speed of the solution.
Blocks.Tol.Rel Input The convergence relative tolerance for the simultaneous reaction solver. Generally, the user should not have to alter this value. If the solution is difficult, the user may set this to a larger number to improve the speed of the solution.
Mass.Tol.Rel Input The convergence relative tolerance for the transfer mass/source/recycle solver. Generally, the user should not have to alter this value. If the solution is difficult, the user may set this to a larger number to improve the speed of the solution.
HeatXchg.Tol.Rel Input The convergence relative tolerance for the heat exchange solver. Generally, the user should not have to alter this value. If the solution is difficult, the user may set this to a larger number to improve the speed of the solution.
Temperature.Tol.Rel Input The convergence relative tolerance for the temperature solver. Generally, the user should not have to alter this value. If the solution is difficult, the user may set this to a larger number to improve the speed of the solution.
Extent.Tol.Abs Input The convergence absolute tolerance for the reaction extent solver. Generally, the user should not have to alter this value. However, if the solution is difficult, the user may set this to a larger number to improve the speed of the solution.
Blocks.Tol.Abs Input The convergence absolute tolerance for the simultaneous reaction solver. Generally, the user should not have to alter this value. However, if the solution is difficult, the user may set this to a larger number to improve the speed of the solution.
Mass.Tol.Abs Input The convergence absolute tolerance for the transfer mass/source/recycle solver. Generally, the user should not have to alter this value. However, if the solution is difficult, the user may set this to a larger number to improve the speed of the solution.
HeatXchg.Tol.Abs Input The convergence absolute tolerance for the heat exchange solver. Generally, the user should not have to alter this value. However, if the solution is difficult, the user may set this to a larger number to improve the speed of the solution.
Temperature.Tol.Abs Input The convergence absolute tolerance for the temperature solver. Generally, the user should not have to alter this value. However, if the solution is difficult, the user may set this to a larger number to improve the speed of the solution.
GridDisplay Tick Box This is a global selection, if this is selected, then where available (such as the RB Solver Settings), variables will display in a table format, if not selected, they will be listed in separate groups as a single list.
VapourHf... (these fields are only visible if the OverridePP option has been selected) (In Build 137 these fields are shown after the RB Solver Results section)
Method There are several methods available to the user for calculating/setting the partial pressure used when calculating the enthalpy of gaseous species to be used in the reaction block calculations. Use of the different methods will not change the amount of material reacted or the final temperature of the stream. It will only change where the energy is reported between the HOR for an individual reaction and the Work term. Refer to Partial Pressure of Gases in Reaction Energy Calculations for more information.
TotalPressure The partial pressure used will be the total feed pressure.
FeedPP The partial pressure used will be the feed partial pressure (this is identical to not using the Partial Pressure Override).
ProductPP The partial pressure used will be the product partial pressure.
EnviroPPFrac The partial pressure used will be the environmental fraction of the gas (as defined on the Plant Model-Environment page) multiplied by the total pressure.
UserDefinedPPFrac The partial pressure used will be the user defined fraction of the gas multiplied by the total pressure.
UserDefinedPP The partial pressure used will be the user defined partial pressure.
PP.Rqd.H2O(g) Input This field is only visible if the UserDefinedPP method is selected. This is the user specified required partial pressure of steam used when calculating the enthalpy of gaseous species to be used in the reaction block calculations.
PP.Used.H2O(g) Calc This is the partial pressure of steam used when calculating the enthalpy of gaseous species to be used in the reaction block calculations, based on what the user has selected for the method.
PP.Feed.H2O(g) Calc This is the partial pressure of steam in the feed.
PP.Prod.H2O(g) Calc This is the partial pressure of steam in the product.
PPf.Rqd.H2O(g) Input This field is only visible if the UserDefinedPPFrac method is selected. This is the user specified required partial pressure fraction of steam used when calculating the enthalpy of gaseous species to be used in the reaction block calculations.
PPf.Used.H2O(g) Calc This field is only visible if the EnviroPPFrac or UserDefinedPPFrac method is selected. This is the partial pressure fraction of steam used when calculating the enthalpy of gaseous species to be used in the reaction block calculations.
PPf.Feed.H2O(g) Calc This field is only visible if the EnviroPPFrac or UserDefinedPPFrac method is selected. This is the partial pressure fraction of steam in the feed.
PPf.Prod.H2O(g) Calc This field is only visible if the EnviroPPFrac or UserDefinedPPFrac method is selected. This is the partial pressure fraction of steam in the product.
Work.Feed Calc The HOR for H2O(g)@PPFeed –> H2O(g)@PPUsed. Obviously if there is no H2O(g) in the feed then this term is zero.
Work.Product Calc The HOR for H2O(g)@PPUsed –> H2O(g)@PPProd. Obviously if there is no H2O(g) in the product then this term is zero.
Edit_RCT Button Opens the reaction file in the editor.
Results
RunState Display This reports run time messages for the reaction file.
Feed.Temperature / Feed.T Calc The temperature of the feed material to the reaction block.
Rct.Feed.Temperature / Rct.Feed.T Calc The temperature of the feed material prior to any reaction occuring but after any adjustments to enthalpies of species has been made.
Rct.Prod.Temperature / Rct.Prod.T Calc The temperature of the product material after all reactions have taken place but prior to any heat exchange and automatic phase changes have been applied.
Prod.Temperature / Prod.T Calc The temperature of the product material after all reactions, heat exchange and automatic phase changes have occurred.
Pressure / P Calc The pressure of the reaction block. Reactions are carried out at a constant total pressure.
PP.Used.H2O(g) Calc This is the partial pressure of steam used when calculating the enthalpy of gaseous species to be used in the reaction block calculations. If OverridePP is not enabled, then this will be the partial pressure of steam in the feed to the reaction block.
Rct.Feed.MassFlow / Rct.Feed.Qm Calc Only visible in Steady-State projects in Build 137 or later. The total mass flow of material fed to the reaction block, including Locked Up material.
Bypass.MassFlow / Bypass.Qm Calc Only visible in Steady-State projects in Build 137 or later. The mass flow of material which bypasses the reaction block due to LockUp.
Source.MassFlow / Source.Qm Calc The mass flow of the total source material added to the reaction block.
Source.TotalMass / Source.Mt Calc Only visible in Dynamic projects. The total mass of source material added to the reaction block from the beginning of the current run.
Sink.MassFlow / Sink.Qm Calc The mass flow of the total material sent to the reaction block sink.
Sink.TotalMass / Sink.Mt Calc Only visible in Dynamic projects. The total mass of material sent to the reaction block sink from the beginning of the current run.
Rct.Prod.MassFlow / Rct.Prod.Qm Calc Only visible in Steady-State projects in Build 137 or later. The total mass flow of material exiting the reaction block, after material has been sent to the sink.
The following 5 fields are only available in Build 136 or earlier. In Build 137 they have been replaced with the RB Solver Results group of tags.
Transfers Calc
Iterations.Temperature Calc The number of iterations required on the last step of the model run to achieve temperature convergence.
Iterations.Extent Calc The number of iterations required on the last step of the model run to achieve convergence of extents.
Iterations.Blocks Calc
SolveTime Calc The solve time that was required for the current iteration for just this reaction block.
The following group of fields are only available in Build 137 or later.
Solve (RB Solver Results)...
Extent.Iters.Total Calc
Reaction.Iters.Total Calc
Blocks.Iters.Total Calc
Transfer.Iters.Total Calc
HeatXchg.Iters.Total Calc
Overall.Iters.Total Calc
Extent.Iters.Loop Calc
Reaction.Iters.Loop Calc
Blocks.Iters.Loop Calc
Transfer.Iters.Loop Calc
HeatXchg.Iters.Loop Calc
Overall.Iters.Loop Calc
Extent.Loop.Fail Calc
Reaction.Loop.Fail Calc
Blocks.Loop.Fail Calc
Transfer.Loop.Fail Calc
HeatXchg.Loop.Fail Calc
Overall.Loop.Fail Calc
Extent.Loops.Fail Calc
Reaction.Loops.Good Calc
Blocks.Loops.Good Calc
Transfer.Loops.Good Calc
HeatXchg.Loops.Good Calc
Overall.Loops.Good Calc
Extent.Loops.Bad Calc
Reaction.Loops.Bad Calc
Blocks.Loops.Bad Calc
Transfer.Loops.Bad Calc
HeatXchg.Loops.Bad Calc
Overall.Loops.Bad Calc
Reaction.Transfers Calc
Time Calc The solve time that was required for the current iteration for just this reaction block.
SysCAD calculates the Energy values for the overall reaction block at up to 5 different Temperatures and Pressures:
dH@0 is always displayed. This displays values at 0°C and the unit pressure.
The user may choose to also display the following values by selecting one or all in EnergyInfo:
  • dH@Fd - the values at Feed conditions;
  • dH@Pr - the values at Product conditions;
  • dH@Ref - the values at Reference conditions (0°C and 1 atmosphere (101.325 kPa); and
  • dH@UsrDef - the values at the User defined conditions.
Nett Calc The overall enthalpy change in the reaction block. This includes all reactions, any heat exchange specified within the RCT file and the enthalpy of any material added (Sources) or lost (Sinks) in the reaction file. A positive number denotes sensible heat gain.
Rct Calc The overall Heat of Reaction for ALL reactions in the Reaction Block. A Negative number denotes an exothermic result.
Work Calc The sum of the energy required to change steam from its feed partial pressure to the partial pressure used in the reaction block calculations and the energy required to change steam from the partial pressure used in the reaction block calculations to the product partial pressure.
HtDiln.Species Calc The enthalpy change due to Heat of Dilution of the specified species (for example HtDiln.H2SO4(aq)) If the user has chosen to Override the Heat of Dilution then this value will be 0.
HX Calc Energy supplied or removed from the unit using the HeatExchange method. A positive number means energy ADDED to the system.
Source Calc The Energy added to the unit due to the addition of any material via the RB Source. A positive number means energy ADDED to the system.
Sink Calc The Energy removed from the unit due to the removal of the material via the RB Sink. A negative number means energy REMOVED from the system.
The following fields will only be visible if the ShowSpRequirements field is set to one of the AsMass or AsBoth options. (Only available in Build 137 or later).
Estimated Species Requirements (Mass Basis)
MsRequired.SpeciesX (Required) Calc The total mass required of species X in order to satisfy all reaction extents.
MsExcess.SpeciesX (Excess) Calc The total excess mass of species X present in the feed (Feed Mass - MsRequired).
The following fields will only be visible if the ShowSpRequirements field is set to one of the AsMoles or AsBoth options. (Only available in Build 137 or later).
Estimated Species Requirements (Mole Basis)
MlRequired.SpeciesX (Required) Calc The total moles required of species X in order to satisfy all reaction extents.
MlExcess.SpeciesX (Excess) Calc The total excess moles of species X present in the feed (Feed Moles - MlRequired).
The following field will only be visible if one of the ShowSpRequirements methods has been selected. (Only available in Build 137 or later).
RctCount.SpeciesX (#Eqns) Display The number of reactions which contain species X.

RS - Summary Table Information

Tag (Long/Short) Input / Calc / Options Description
Edit_RCT Button Opens the reaction file in the editor.
SummaryTableInfo
(Only available in Build 137 or later.)
Adds RS tab page.
Basic All reactions will be listed in a summary table, fields displayed are: Reaction Number, Reaction On/Off, Reaction
Extent All reactions will be listed in a summary table, fields displayed are: Reaction Number, Reaction On/Off, Reaction Extent Required, Reaction Extent Achieved, Reaction, Reaction Extent Description.
Transfer All reactions will be listed in a summary table, fields displayed are: Reaction Number, Reaction On/Off, Mass Reacted (of extent species), Reaction
All All reactions will be listed in a summary table, fields displayed are: Reaction Number, Reaction On/Off, Reaction Extent Required, Reaction Extent Achieved, Mass Reacted (of extent species), Reaction, Reaction Extent Description.
Displays the Reaction Summary Table Information. (Only available in Build 137 or later.)
Basic RS Basic.png
Extent RS Extent.png
Extent,Transfer RS Extent Transfer.png
Extent,Energy RS Extent Energy.png
Transfer RS Transfer1.png
Transfer,Energy RS Transfer Energy.png
All RS All1.png
Reaction and Species Count
NoOfReactions / NumRB.Count Calc The number of reactions in this reaction block.
NumRB.ExtentNotAchieved Calc The number of reactions that have not achieved their required reaction Extents.
NumRB.ExtentSpMissing Calc The number of reactions for which there is no species for which the Extent is defined in the Feed to the reaction. (This condition does not generate an error message)
NumRB.ZeroExtent Calc The number of reactions that have Reaction Extent = 0.
NumRB.NothingReacted Calc The number of reactions that do not have any reaction occurring.
NumRB.Off Calc The number of reactions that are turned Off.
SpeciesCount / SpCount Calc Only available in Build 137 or later. The number of species involved in reactions in this reaction block.
SpeciesList / SpList Display Only available in Build 137 or later. A list of the species involved in reactions in this reaction block.

Individual Reactions

Tag (Long/Short) Input / Calc / Options Description
Each reaction has its own section of data, please see Individual Reactions for more information.

Source Data Fields

Tag (Long/Short) Input / Calc / Options Description
If the user has specified a source of material within the reaction file, the following block(s) will appear. Each species that has been added as a source in the rct file will be listed individually. Please also see Reaction Block - Other for more information.
Reaction Display Displays what type of reaction source (Source / Recycle / Source & Recycle) and lists the relevant species.
On Tick Box This may be used to enable or disable the Source.
Index Display Only available in Build 137 or later. Reaction Index. Useful for sorting the reactions in reports
TypeID Display Source
Recycle
Recycle.Species i / msRecycle.Species i Calc Only visible if the type of source is Recycle or Source & Recycle. The mass of species i that is recyled from later reaction to earlier reactions in the Reaction Block.
Recycle.ml.Species i / mlRecycle.Species i Calc Only visible if the type of source is Recycle or Source & Recycle. The moles of species i that is recyled from later reaction to earlier reactions in the Reaction Block.
Source
Species i / msSrc.Species i Calc Only visible if the type of source is Source or Source & Recycle. The mass of species i required for the Reaction Block.
ml.Species i / mlSrc.Species i Calc Only visible if the type of source is Source or Source & Recycle. The moles of species i required for the Reaction Block.
SourceMass / msXfer Calc Only available in Build 137 or later. Only visible if the type of source is Source or Source & Recycle. The total mass of all species added (sum of sources, not recycles) in the Source.
Source.SetTandP Tick Box Only visible if the type of source is Source or Source & Recycle. This may be used to set the temperature and pressure of the Source. If this is NOT enabled, then the Feed temperature and Pressure are used.
Source.Temperature / Source.T Input Only visible if Source.SetTandP is enabled. The required temperature of the Source.
Source.Pressure / Source.P Input Only visible if Source.SetTandP is enabled. The required pressure of the Source (usually only important for vapours).
HsGain Calc Only visible if the type of source is Source or Source & Recycle. The total enthalpy added via the source species, calculated at the source temperature and pressure.
HfGain Calc Only visible if the type of source is Source or Source & Recycle. The total enthalpy, including Heat of formation, added via the source species, calculated at the source temperature and pressure.
Temperature / T Calc Only visible if the type of source is Source or Source & Recycle. The actual temperature of the source species when added.

Sink Data Fields

Tag (Long/Short) Input / Calc / Options Description
If the user has specified a sink of material within the reaction file, the following fields will appear. Each species that has been removed via the sink in the rct file will be listed individually. Please also see Reaction Block - Other for more information.
Reaction Display Sink: Species Name(s)
On Tick Box This may be used to enable or disable the Sink.
Index Display Only available in Build 137 or later. Reaction Index. Useful for sorting the reactions in reports
TypeID Display Sink
Sink
Species i Calc The mass of species i that will be discarded in the Sink. The mass of each species specified in the Sink will be displayed in a separate field.
SinkMass / msXfer Calc Only available in Build 137 or later. The total mass of all species that will be discarded in the Sink.
HsGain Calc The total enthalpy removed via the sink species.
HfGain Calc The total enthalpy, including heat of formation, removed via the sink species.
Temperature / T Calc The temperature of the sink species removed.

Heat Exchange Data Fields

Tag (Long/Short) Input / Calc / Options Description
If the user has specified a heat exchange with the reaction file, then the amount of heat that is added, or removed, from the unit will also be shown here. Please also see Reaction Block - Other for more information.
On Tick Box This may be used to enable or disable the Heat Exchange.
Heat Exchange Display The Heat Exchange method chosen in the reaction file will be displayed in this field.
Index Display Only available in Build 137 or later. Reaction Index. Useful for sorting the reactions in reports
TypeID Display Only available in Build 137 or later. HeatExchange
1. FinalT Method (Consider using OverrideProductT instead.)
FinalT_Reqd (Rct/Set) Input / Calc The targeted Final temperature required. This may be user specified (either the value typed in the reaction file (Rct) or overridden in the access window (Set)) or set to the feed temperature.
2. Approach Method (Consider using OverrideProductT instead.)
BasisT Calc The basis temperature. This will either be the feed or product temperature of the reaction block.
TargetT (Rct/Set) Input / Calc The target temperature. This may be user specified (either the value typed in the reaction file (Rct) or overridden in the access window (Set)) or set to the environment temperature.
Approach (Rct/Set) Input The extent to which the unit approaches the target temperature (%). This will be either the value typed in the reaction file (Rct) or overridden in the access window (Set).
FinalT Calc The final temperature achieved.
3. Power Method
PowerInput (Rct/Set) Input Power supplied to the unit. This will be either the value typed in the reaction file (Rct) or overridden in the access window (Set).
4. Electrolysis Method
ElectEff (Rct/Set) Input The cell efficiency (%). This will be either the value typed in the reaction file (Rct) or overridden in the access window (Set).
HeatGain / HsGain Calc The amount of heat added or subtracted is given as the Heat Gain. Heat added to the reaction block is given as a positive number.

Hints and Comments

  1. By default, reactions will solve in a sequential order, the order is defined by how they appear in the reaction file. However, the user can change the reaction evaluation sequence by inserting a different sequence number for each individual reaction. For simultaneous reactions, the user must provide the same sequence number to all the reactions to be solved at the same time. All reactions found under a specified sequence number will be assigned the same sequence number and thus solved simultaneously. Sequential reactions are computationally faster, so it is recommended that simultaneous reactions are only used where absolutely necessary.
  2. For simultaneous reactions, problems may arise if a component act both as a reactant and a product, for the reacting amount available comes solely from the feed, and not from the reactions. This is not a problem for sequential equations.
  3. Heat of formation information must be entered for all components involved in reactions. If Hf information is missing, then Heat of Reaction values should be provided. If neither is present, then SysCAD will give a warning and the Heat of Reaction value calculated will be incorrect (any missing Hf's are assumed to be +100 kJ/mol).
  4. If multiple reactions are present in single reaction block, the Final Concentration or Final Fraction extent methods give the FinalConc or FinalFrac at that specific reaction and NOT for the reaction block exit stream.
  5. Make sure -> is used instead of = or <-> when writing reactions that are non-reversible.
  6. Consider using the more efficient OverrideProductT option (see Override Product Temperature Option) where the product temperature of the unit that includes reactions is set, rather than using EHX or RB.HX.
  7. If the order of the reactions is changed, SysCAD will remember any overridden extents and still associate them with the old reaction number. Eg. if the extent of the old R2 was overridden to be 10%, then the extent of the new R2 will also be manually overridden to 10%.
  8. The outlet temperature from the reaction block (Prod.T) will be set to no less than 10 degrees below the project minimum temperature and no more than 10 degrees above the project maximum temperature. This may cause an energy imbalance across the unit. These temperature limits can be set in the Project Configuration file.
  9. If the user uses a reaction source which is the extent species, then the extent achieved may not be calculated correctly and the user may receive a warning that the extent has not been achieved.
  10. In SysCAD 9.3 Build 137, user may specify a limit for the reaction extent to avoid fully reacting a species. (This option is switched on from RB Tab - under Settings - LimitFractionReacted, when switched on, extra limit fields will be visible for each individual reactions.)
  11. In SysCAD 9.3 Build 137, user may specify a limit for the maximum reaction mass or moles. (This option is switched on from RB Tab - under Settings - LimitAmountReacted, when switched on, extra limit fields will be visible for each individual reactions.)