General Model (GM)

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General Description

By enabling the General Model (GM) or Split Flows sub-model, within a unit, the user has control over the split to the outgoing streams. If this sub-model is NOT enabled, then the unit will split the material from the unit equally between the outgoing streams.

  • To enable the Split Flows or General Model, the user must tick the SplitFlows tickbox on the first tab page of the unit;
  • In SysCAD 9.3 the Split tab is then available for configuration.
  • In SysCAD 9.2 the GM tab becomes visible;
  • The user may configure the split between the outgoing flows.
  • The streams may then be split purely on a mass percentage basis, or the phase split may be specified, or user defined species may be controlled in certain streams.
  • This sub-model is commonly used in the Tie and Tank in Steady State models to control the flows from these units.

Video Links

There are a number of videos describing the various operational methods available in the General Model - these links are shown in the table below. This link describes how to enable the General Model and set pipe priorities: YouTube link.

Important Notes

  1. If there are n streams leaving the unit, then the user may control (n-1) streams. The nth stream must be free to balance the incoming and outgoing flows.
    • For example, if there are 3 outgoing streams, then the user may configure 2 streams, and the 3rd stream will be the balance stream.
  2. The only exception to this rule is if the user selects Operation = 'Demand Mass Flow', in which case the user must set the Demand flow for ALL outgoing streams. This option is only available in SysCAD 9.3.
  3. It is strongly recommended that the user sets the priority field for all configured streams in the GM to avoid order swapping. (see the following point)
  4. If the user configures the GM, and then at a later stage adds or removes a stream from the unit operation containing the GM, this may have an impact on the GM configuration. It is recommended that the user checks the GM settings every time a stream change is made.
  5. If the GM configuration data is read in from MS Excel or text files, it is recommended that the priority field be included as part of the settings.
  6. In SysCAD 9.3 and later, users may Find or Access each link listed in the Splitter section by clicking on the binoculars or magnifying glass displayed next to each link name - as shown in the diagram below:
Splitter Link Display.png

Data Sections

The first variable that can be configured on the access page for the GM is "Operation". Depending on the option chosen by the user, the access page will change. Each option and its associated access page are described in the sections below.

General Mass Fraction Mass Flow Volume Fraction Volume Flow Phase Mass Fraction Phase Mass Flow Phase Volume Flow Species Mass Fraction Species Mass Flow Demand Mass Flow Phase Recovery Solids Recovery Water Recovery Gas Vent

Tag (Long/Short) Input/ Outputs Description

OPERATION - General

General.png
  • This method allows the user to configure each outgoing stream using mixture of methods.
  • This method is required if a tie exist within a flash train configuration. See topic Tie in Flash Train
  • For method, variable list and some examples for the General Operation please see GM - General Operation.
  • For a short video on how the General operation works please see YouTube link

OPERATION - Mass Frac

MassFrac.png
  • This option allows the user to specify the mass percentage split to (n-1) streams. All of the outgoing streams will have the same composition as the material in the unit. All of the streams leaving the unit will be displayed on the access page. However, the last stream in the list cannot be configured, the user may use the priority field to select which stream should be configured.
  • For a short video on how the Mass Fraction split works please see YouTube link
Order Display The actual stream solving order of priority.
Priority Drop list Lets the user select the stream solving order.
Split Input Allows the user to specify the fraction of the total mass which is to be directed to this stream.

OPERATION - Mass Flow

MassFlow.png
  • This option allows the user to specify the mass flow to (n-1) streams. All of the outgoing streams will have the same composition as the material in the unit. All of the streams leaving the unit will be displayed on the access page. However, the last stream in the list cannot be configured, the user may use the priority field to select which stream should be configured.
  • When solving, the model will try and satisfy the requirements of the stream with the lowest order number, and then the next lowest, etc.
  • For a short video on how the Mass Fraction split works please see YouTube link
Order Display The actual stream solving order of priority.
Priority List Lets the user select the stream solving order.
Flow Input Allows the user to specify the mass flow of this stream.
Target Tickbox This option is only available in Build 134 or later. If this is ticked (On) then the user will NOT receive warning messages if the user specified requirements for this stream are not met, ie. it is only a target.
QmErr Display Displays the difference between the mass flow specified by the user and the actual mass flow of the stream.

OPERATION - Volume Frac

VolFrac.png
  • This option allows the user to specify the volume percentage split to (n-1) streams. All of the outgoing streams will have the same composition as the material in the unit. All of the streams leaving the unit will be displayed on the access page. However, the last stream in the list cannot be configured, the user may use the priority field to select which stream should be configured.
  • The data fields are the same as for the Operation - Mass Frac option except that the specified Split is the fraction of the total volume rather than the total mass.

OPERATION - Volume Flow

VolFlow.png
  • This option allows the user to specify the volume flow to (n-1) streams. All of the outgoing streams will have the same composition as the material in the unit. All of the streams leaving the unit will be displayed on the access page. However, the last stream in the list cannot be configured, the user may use the priority field to select which stream should be configured.
  • When solving, the model will try and satisfy the requirements of the stream with the lowest order number, and then the next lowest, etc.
Order Display The actual stream solving order of priority.
Priority Drop list Lets the user select the stream solving order.
VFlow Input Allows the user to specify the volume flow of this stream.
Target Tickbox This option is only available in Build 134 or later. If this is ticked (On) then the user will NOT receive warning messages if the user specified requirements for this stream are not met, ie. it is only a target.
QvErr Display Displays the difference between the volume flow specified by the user and the actual volume flow of the stream.

OPERATION - Phase Mass Frac

PhaseFrac.png
  • This option allows the user to specify the mass percentage split for the different phases reporting to (n-1) streams. All of the streams leaving the unit will be displayed on the access page. However, the last stream in the list cannot be configured, the user may use the priority field to select which stream should be configured.
  • For a short video on how the Phase Mass Fraction split works please see YouTube link
PhaseSpec Drop List Allows user to choose either Total phases (solids, liquids and gases) or Individual phases.

If Total is chosen for the PhaseSpec, then the user will have the following fields for each stream:

Order Display The actual stream solving order of priority.
Priority Drop list Lets the user select the stream solving order.
Solids Input Allows the user to specify the mass fraction of the total solids which is to be directed to this stream.
Liquids Input Allows the user to specify the mass fraction of the total liquids which is to be directed to this stream.
Vapours Input Allows the user to specify the mass fraction of the total gases which is to be directed to this stream.

If Individual is chosen for the PhaseSpec, then the fields will be the same except instead of Solids, Liquids and Vapours, the user will be able to specify fractions for each individual phase defined in the project (for example, aq (aqueous), o (organic), sl (slag), etc.).

OPERATION - Phase Mass Flow

PhaseMassFlow.png
  • This option allows the user to specify the mass flow for each of the different phases reporting to (n-1) streams. All of the streams leaving the unit will be displayed on the access page. However, the last stream in the list cannot be configured, the user may use the priority field to select which stream should be configured.
  • When solving, the model will try and satisfy the requirements of the stream with the lowest order number, and then the next lowest, etc.
  • For a short video on how the Phase Mass Flow split works please see YouTube link
Order Display The actual stream solving order of priority.
Priority Drop list Lets the user select the stream solving order.
Solids Input Allows the user to specify the mass flow of solids in this stream.
Liquids Input Allows the user to specify the mass flow of liquids in this stream.
Vapours Input Allows the user to specify the mass flow of gases in this stream.
Target Tickbox This option is only available in Build 134 or later. If this is ticked (On) then the user will NOT receive warning messages if the user specified requirements for this stream are not met, ie. they are only targets.
QmErr Display Displays the difference between the total mass flow specified by the user (sum of all three phases) and the actual total mass flow of the stream.

OPERATION - Phase Volume Flow

PhaseVolFlow.png
  • This option allows the user to specify the volume flow for each of the different phases reporting to (n-1) streams. All of the streams leaving the unit will be displayed on the access page. However, the last stream in the list cannot be configured, the user may use the priority field to select which stream should be configured.
  • The data fields are the same as for the Operation - Phase_MassFlow option except that the inputs specified are volume flows instead of mass flows. The QvErr field displays the difference between the total volume flow specified by the user (sum of all three phases) and the actual total volume flow of the stream.

OPERATION - Species Mass Frac

SpeciesMassFrac.png
  • This option allows the user to specify the mass percentage split for the individual species reporting to (n-1) streams. All of the streams leaving the unit will be displayed on the access page. However, the last stream in the list cannot be configured, the user may use the priority field to select which stream should be configured.
  • The data fields are similar to the Operation - MassFrac option except that fractions are specified for each individual species rather than for the whole stream.
  • For a short video on how the Species Mass Fraction split works please see YouTube link

OPERATION - Species Mass Flow

SpeciesMassFlow.png
  • This option allows the user to specify the mass flow for each individual species reporting to (n-1) streams. All of the streams leaving the unit will be displayed on the access page. However, the last stream in the list cannot be configured, the user may use the priority field to select which stream should be configured.
  • The data fields are similar to the Operation - Phase_MassFlow option except that flows are specified for each individual species rather than for the whole stream. The QmErr field will display the difference between the total mass flow specified by the user (sum of all species) and the actual total mass flow of the stream.

OPERATION - Demand Mass Flow

GM Demand137.png
  • The Demand.SpecifyTotal option is implemented in SysCAD 9.3 build 137.21604
  • This option allows the user to specify the Total Demand mass flow and upto n-1 individual stream flows. When the Total flow is specified, at least one stream needs to be * (unspecified).
  • Please see Demand for more information on the Demand functionality in SysCAD.
  • If the Demand.SpecifyTotal option is NOT used, then all output flowrates must be specified. (See below)
GM Demand.png
  • This option is implemented in SysCAD 9.3 build 136.
  • This option allows the user to specify the Demand mass flow to ALL n streams.
  • The unit should have a Feeder with 'Demand' enabled upstream of the unit for this functionality to operate correctly. Please see Demand for more information on the Demand functionality in SysCAD.
  • All of the outgoing streams will have the same composition as the material in the unit.
  • When solving, the model will try and satisfy the requirements of the stream with the lowest order number, and then the next lowest, etc.
Demand.SpecifyTotal Tick Box Only available in Build 137. This option allows the user to specify the Total Demand mass flow and upto n-1 individual stream flows. When the Total flow is specified, at least one stream needs to be * (unspecified).
Demand.TotalQmReqd Input Only visible if Demand.SpecifyTotal option is selected. Allows the user to input the total Demand flow.
Order Display The actual stream solving order of priority.
Priority List Lets the user select the stream solving order.
QmReqd Input Allows the user to specify the Demand mass flow to this stream.
QmErr Display Displays the difference between the Demand mass flow specified by the user and the actual mass flow of the stream.

OPERATION - Phase Recovery

PhaseRecovery.png
  • NOTE: This option is only available for models with two output streams only (n = 2).
  • The user chooses the stream (ie, overflow, underflow, etc), phase recovered (ie, solids, liquid or gas), then specifies the split and composition for that particular phase in the chosen stream.
  • For example, if the process unit represents a filter, the user can specify that the recovery of solids is 90% and the filter cake contains 80% solids, (20% moisture).
Phase Drop List The phase to be recovered (solid, liquid or gas)
Stream Drop List The stream which the user wishes to specify the fraction and composition.
Fraction Input The (mass) fraction of the chosen phase which will be sent to the chosen stream. In the above example, we are sending 90% of the feed solids to the specified Stream.
Composition Input The (mass) fraction of the chosen phase in the chosen stream. The fractions of the other phases (other than the phase to be recovered) will be automatically adjusted in order to achieve this composition. In the above example, we are requesting the chosen stream to be 80% solids.

OPERATION - Solids Recovery

SolidsRecovery.png
  • This option is only available in SysCAD 9.3.
  • This option is only available for models with two output streams only (n = 2).
  • The user chooses the stream where solids is to be recovered, then specifies the split and composition for the stream.
  • For example, if the process unit represents a cyclone, the solids recovery stream can represent the cyclone U/F, where 50% of the feed solids will be sent to the U/F, and the U/F has 65% solids by composition. (35% moisture).
Stream Drop List The stream which the user wishes to specify the fraction and composition.
Fraction Input The (mass) fraction of the solid phase which will be sent to the chosen stream. In the above example, we are sending 50% of the feed solids to the specified Stream.
Composition Input The (mass) fraction of the solid phase in the chosen stream. The fractions of the other phases (other than the solid phase) will be automatically adjusted in order to achieve this composition. In the above example, we are requesting the chosen stream to be 65% solids.

OPERATION - Water Recovery

WaterRecovery.png
  • This option is only available in SysCAD 9.3.
  • This option is only available for models with two output streams only (n = 2).
  • This method can be used to simulate a simple water treatment (RO) facility, where user specifies the water recovery rate and Impurities removal efficiency. Or it can be used to represent any other simple process where water is separated out from a stream.
  • If gas or solids are present in the feed, they will be sent to the other stream (brine), the specified stream will only contain water + other liquid species.
ProductStream / Stream Drop List The stream which the user wishes to represent the clean water stream. (The other stream will be the brine)
Yield Input The (mass) fraction of water to be recovered. In the above example, we are sending 75% of the feed water to the Product Stream.
Efficiency Input The (mass) fraction of other liquid compounds removed. In the above example, we are requesting 95% of all other liquid compounds in the feed be removed and sent to the brine. That means, 5% of other liquid compounds present in the feed will be in the water product stream.

OPERATION - Gas Vent

VentRecovery.png
  • This option is only available in SysCAD 9.3.
  • This option is only available for models with two output streams only (n = 2).
  • This method is used to send gaseous components to the vent.
VentStream / Stream Drop List The stream which the user wishes to represent the vent stream.
Fraction Input The (mass) fraction of all gases in the feed to be sent to the vent. In the above example, we are sending 90% of the feed gaseous compounds to the specified Stream.