Plant Model - RC

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Introduction

This tab page on the Plant Model Access Window allows the user to set up range check related parameters.

Tag (Long/Short)	Options	Description/Calculated Variables
Range Checks
RC...
Action	Off	Never carry out any Range Checks - the user will not get any warnings if values are outside of their expected ranges. If this option is selected then none of the fields described below will be visible.
	WhenNotBusy	Do the Range Checks when the solver is not busy, i.e. when the model is stopped or paused.
	Continuous	Do the Range Checks at every iteration.
	OnCount	Do the Range Checks at specific iteration intervals - the interval is defined by the user.
	WhenSolved	Only available in a steady state project. Do the Range Checks when the project is solved.
Count	Input	The number of iterations/steps between each range check - this field is only visible if OnCount is chosen above.
RelMassTolerance	Input	The Relative Mass Tolerance value, as a percent, used to check if a stream has flow of the relevant species. If the flow of the species is less than this tolerance then no checks will be performed.
Mixture
Project.T	Tickbox	This enables a check of the unit or stream temperature against the maximum and minimum values specified in the project configuration file. (The maximum and minimum values specified in the project configuration file are displayed next to this tick box). Please see Temperatures and Pressures in the Project Configuration.
Project.P	Tickbox	This enables a check of the unit or stream pressure against the maximum and minimum values specified in the project configuration file. (The maximum and minimum values specified in the project configuration file are displayed next to this tick box). Please see Temperatures and Pressures in the Project Configuration.
BPE.T	Tickbox	This enables a check of the Boiling Point Elevation (BPE). Please see Boiling Point Elevation for more information on the BPE.
SaturationT	Tickbox	This enables a check of the Saturation temperature.
Density.Correction	Tickbox	This enables a check of the mass fraction of species with density corrections against the maximum mass fraction specified in the species database when using the Standard Species Model. Please see Density Correction in the Species Table for more information on the Density Correction function.
Density.NoSolvent	Tickbox	Only available in Build 138 or later. This enables a warning to be given if a species with a Density Correction function is present with no solvent. Please see Density Correction in the Species Table for more information on the Density Correction function.
Density.HiSolute	Tickbox	Only available in Build 138 or later. This enables a check of the mass fraction of species with density corrections against the maximum mass fraction specified in the species database when using the Standard Species Model. For each species, warnings will only be given if the Generate Warnings field in the Density Correction Function specification in the Species Database is 'On'. Please see Density Correction in the Species Table for more information on the Density Correction function.
Cp.LowLiq	Tickbox	This enables a check when using the Standard Species Model to ensure that stream specific heats are greater than a user defined value (see Cp.LowLiq.Value below). SysCAD allows users to enter negative Cp values for aqueous species only. This allows the aqueous species to lower the specific heat of an aqueous stream. However, if the aqueous species are more concentrated than expected, the stream Cp may become negative, which is physically impossible and this causes problems with the energy balance and temperature calculations. The following 2 fields are only visible if this Tickbox is enabled.
Cp.LowLiq.Value	Input	This is only visible if Cp.LowLiq is enabled. The user may enter lowest allowable Cp value in an aqueous stream. SysCAD will flag a warning if the Cp is below this value and Cp.LowLiq is enabled. It does not adjust the Cp value actually used.
Cp.LowLiq.Rule	All Solutions	When using the Standard Species Model, report errors for ALL liquid streams that have a Cp value lower than the value in the field above.
	IgnoreIfNoH2O	When using the Standard Species Model, report errors only for liquid streams that contain water AND that have a Cp value lower than the value in the field above. This prevents users getting errors when they add a stream, either as a makeup or a normal stream, that contains only an aqueous species with a negative Cp.
VelLimit.ShowAs	Off	No velocity limit messages will be shown.
	Note	Velocity limit messages will be shown as notes.
	Warning	Velocity limit messages will be shown as warnings.
	Error	Velocity limit messages will be shown as errors.
VelLimit.Slurry	Input	Allows user to set an upper limit for slurry velocity. Messages may be displayed based on the VelLimit.ShowAs method selected. See the above field.
VelLimit.Vapour	Input	Allows user to set an upper limit for vapour velocity. Messages may be displayed based on the VelLimit.ShowAs method selected. See the above field.
Individual Species The first 2 fields below allow the user to enable or disable specific heat (Cp) checks for INDIVIDUAL species, rather than for the total stream. These are for Standard Species Model.
Cp.T	Tickbox	If this is ticked, then SysCAD will check the temperature of the unit or stream against the extended temperature range, as specified in the configuration file. If the measured temperature is outside the species Cp extended temperature range, then SysCAD will give the user a warning. Please see Heat Capacity (Cp) in the Species Table for more information on the Cp function and Increasing the Temperature Range of a Species in the Species Configuration.
Cp.T.Tolerance	Tickbox	If this is ticked, then SysCAD will NOT give the user a message if the temperature of the unit or stream is outside of the temperature range specified for the species specific heat (Cp) value in the species database, but within the extended temperature range. If this is NOT ticked, and the measured temperature is outside the species Cp normal temperature range, but within the extended range, then SysCAD will give the user a message. NOTE: If the measured temperature is outside the species Cp extended temperature range SysCAD will still give the user a warning.
H2O.CriticalTemp	Tickbox	If the tick box is checked and H2O liquid, H2O(l), is present and the stream temperature is above the Critical Temperature of water, SysCAD will give the user a warning.