Reaction Block (RB)

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

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 File' button , as shown below:
Pressing the 'Edit_RCT File' button will start the reaction editor, see Reaction File for more information.
- If reaction editor does not start, please see Reaction Editor for instructions.
The completed reaction file is loaded into the unit
- User can also manually reload the reaction by pressing the "Reload RCT Files" button.
When the SysCAD solver is activated, it will solve the unit with the defined 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.
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.
The calculation of Heat of Reaction (HOR) is explained in Reaction Block - HOR & Energy. This includes an explanation of the HOR override for individual reactions and overall in Override Product Temperature options.
A reaction block can optionally have sources and/or sinks of species. Refer to Reaction Block - Other for more information.
A reaction block can have heat exchange defined. Refer to Reaction Heat Exchange for more information.
There are additional options and reporting fields available/relevant when a heat of dilution species (eg. H2SO4(aq)) or a species whose enthalpy changes with pressure (eg. H2O(g)) is present in a stream where a reaction is taking place. These topics are discussed in more detail in Heat of Dilution in Reaction Energy Calculations and Partial Pressure of Gases in Reaction Energy Calculations.

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.
StopForRCTFileError	Tick Box	Only available in Build 139.31388 or later. Prevents project from running if there is an RCT file missing or fails to load. This a global option which applies to all reaction blocks. Also available in Solver Settings. Will not be applied if RB is not 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. 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. For simultaneous reactions, the user should change this to All_Target. This setting will also affect whether warnings are displayed if reactions are restricted by the LimitAmountReacted or LimitFractionReacted settings.
	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	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. If the limits are reached, the unit will give a warning if ExtentType is set to Strict.
	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	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. If the limits are reached, the unit will give a warning if ExtentType is set to Strict.
	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 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.
The following fields are only visible if the EnergyInfo list box (under the Display Extra Information section) is set to User Defined Info or All Energy Info.
UsrDefT	Input	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 [email protected] fields and the [email protected] fields under each individual reaction.
UsrDefP	Input	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 [email protected] fields and the [email protected] 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 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	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 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.
Tolerances	Reset to Defaults	Pressing this button will reset the tolerances to default values.
The table row and column headings are described below (note: units shown on far right of table):
Extent	Row heading	The values displayed are for the iterative reaction extent solver.
Blocks	Row heading	The values displayed are for the iterative Simultaneous Equations Convergence solver.
Mass	Row heading	The values displayed are for the transfer of Mass & Source/Recycle Convergence solver.
HeatXchg	Row heading	The values displayed are for the iterative reaction Heat Exchange Convergence solver.
Temperature	Row heading	The values displayed are for the iterative reaction temperature Convergence solver.
Iters.Max	Column heading	The maximum number of iterations of the convergence solver.
Tol.SigDigits	Column heading	Convergence relative tolerance in the form of Significant Digits. SigDigits = -log(Tol.Rel).
Tol.Rel	Column heading	The convergence relative tolerance. 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.
Tol.Abs	Column heading	The convergence absolute tolerance. 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.

RB.. (RB Continued)

Tag (Long/Short)	Input / Calc / Options	Description
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).
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. 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. 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. The total mass flow of material exiting the reaction block, after material has been sent to the sink.
Solve (RB Solver Results)...
The table row and column headings are described below:
Extent	Row heading	The number of iterative Extent Calculations
Reaction	Row heading	The number of iterative Reaction Rates.
Blocks	Row heading	The number of iterative Simultaneous Equations.
Transfer	Row heading	Iterative Amounts Transferred.
HeatXchg	Row heading	The number of iterative reaction heat exchange Calculations.
Overall	Row heading	Main RB Solution
Iters.Total	Column heading	The total iteration count.
Iters.Loop	Column heading	The iteration loop count.
Loop.Fail	Column heading	The number of iteration loop failed to solve.
Loops.Good	Column heading	The number of iteration loop converged.
Loops.Bad	Column heading	The number of iteration loop not converged.
Reaction.Transfers	Calc	The number of species transfers in the reaction block.
Time	Calc	The solve time that was required for the current iteration for just this reaction block.
VapourHf... (these fields are only visible if the OverridePP option has been selected)
VapourHf.Method	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.
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.
Energy Balance
[email protected]	Calc	The difference between "calculated Heat of reaction (HOR)" and the "HOR used".
SysCAD calculates the Energy values for the overall reaction block at up to 5 different Temperatures and Pressures: [email protected] 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: [email protected] - the values at Feed conditions; [email protected] - the values at Product conditions; [email protected] - the values at Reference conditions (0°C and 1 atmosphere (101.325 kPa); and [email protected] - 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. Refer to Heat of Dilution in Reaction Energy Calculations for details on how this is calculated.
HX	Calc	Energy supplied or removed from the unit using the HeatExchange method or by using OverrideProductT. 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.
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.
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.
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 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. Note: For extent types with two parameters, such as the Dynamic Rate or Dynamic Fraction, the required column will be blank. In these cases, the Achieved column shows the FracPerStep.Achieved.
Basic
Extent
Extent,Transfer
Extent,Energy
Transfer
Transfer,Energy
All
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	The number of species involved in reactions in this reaction block.
SpeciesList / SpList	Display	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	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 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	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	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	Reaction Index. Useful for sorting the reactions in reports
TypeID	Display	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

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.
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.
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).
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.
Make sure -> is used instead of = or <-> when writing reactions that are non-reversible.
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.
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%.
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.
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.
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.)
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.)
If reactions are not solving, the user can either increase the maximum iterations or increase the tolerance values. These are set at the bottom of the first RB tab page.