Tank

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Navigation: Models ➔ General Models ➔ Tank

Tank Tank - Dynamic Mode Dynamic Tank - Optional Data Sections

This section is for the Tank model when used in Steady State, mode. For help on the Tank model in Dynamic mode, please see Tank - Dynamic Mode (There are significant differences in the tank behaviour between Steady State and Dynamic).


General Description

In Steady State the tank model is very similar to the tie model. When materials are mixed in the tank, a homogeneous product is produced.

Available Sub-Models

Evaluation Block:

  1. Makeup Blocks (one or more) may be enabled in a Tank. This allows the user to control the addition of streams such as reagents, water, air, etc to the tank, often without having to use a PID or General controller.
  2. The Reaction Block (RB) allows the user to configure any number of reactions within the tank.
  3. The Environmental Heat Exchanger Block allows the user to add or remove energy from the tank using a number of different methods.
  4. The Evaporation Block allows the user to set the evaporation of either water only or a mixture of water and all other species that are specified as both liquid and vapour.
  5. The Vapour Liquid Equilibrium Block will attempt to ensure that the vapours and liquids of the selected species will be in equilibrium in the Tank. For example, if the equilibrium species is water and the tank is at atmospheric pressure, then SysCAD will maintain the temperature at, or below, the saturated temperature of 99.97°C by evaporating water if required.
  6. Discard Blocks (one or more) may be enabled in a Tank. This allows the user to control the discarding of material from the Tank, usually without having to use a PID or General controller. This is available in Build 138 or later.

Options:

  1. The General Model (GM) may be enabled in the tank in Steady State, allowing the user to control the split between the outgoing stream flows.
  2. The Thermal Split may also be enabled in Steady State IF the General Model is enabled. This option is used to adjust the temperatures of the outgoing streams from the unit.
  3. The Heat Exchanger (HX) may be enabled. The user must also connect links to the HX input and the HX output. The Heat Exchange page needs to be configured with the relevant heat exchange area and overall heat transfer coefficient. The model combines all of the incoming streams, performs any reactions, and then carries out the heat exchange operation. Please note that the fluid in the heat exchanger will transfer energy via sensible heat ONLY. There is NO condensing or boiling in the heat exchanger.

Model Procedures

Model Procedures allows the user to implement code directly within the Tank.

To enable this, on the Info tab page tick the "Procedures" tickbox.

Diagram

Tank.jpg

The diagram shows a drawing of the tank, with a number of connecting streams. When the user inserts the tank into a flowsheet, a different graphics symbol can be selected from a pull down menu. The streams may be connected to any area of the drawing without affecting the actual connection point as SysCAD ignores the physical position of the connection. In dynamic mode, you can set the connection height of the links.

Inputs and Outputs

Label Required
Optional
Input
Output
Number of Connections Description
Min Max.
Input 1 Required In 0 30* General purpose inlet. *Maximum was 20, limit increased in Build 138.25939.
Output 1 Required Out 0 20 General purpose outlet
HX_in Optional In 0/1* 20 Heat exchanger inlet. *This is required only if the HX block is selected. (No condensing or evaporating allowed. See notes on options)
HX_Out Optional Out 0/1* 20 Heat exchanger outlet. *This is required only if the HX block is selected. (No condensing or evaporating allowed. See notes on options)

Model Theory

In Steady State, all the input streams (excluding the HX streams) are perfectly mixed, then any sub-model actions occur on the mixture. This is very similar to the Tie model.

Flowchart

The following flowchart shows the sequence of events if any Evaluation Block sub-model options or the HX Block are enabled:

Tank-ProBal.png

Data Sections

Summary of Data Sections

The tank access window may consist of a number of sections. This number may increase or decrease, based on user configuration and / or number of species.

  1. Tank-1 tab - Contains general information relating to the unit.
  2. PC - Optional tab that is visible if EB.Solubility.On and/or [email protected] is enabled on the first tab.
  3. MU - Optional tab, or multiple tabs if more than 1 Makeup is selected. Only visible if one of more Makeups are enabled in the Evaluation Block.
  4. RB - Optional tab, only visible if the Reactions are enabled in the Evaluation Block.
  5. HX - Optional tab, only visible if streams (in and out) have been connected to the Tank.HeatExchange IO connection ports.
  6. EHX - Optional tab, only visible if the EnvironHX is enabled in the Evaluation Block.
  7. Evap - Optional tab that is visible if Evaporator is enabled.
  8. VLE - Optional tab, only visible if the VLEquilibrium is enabled in the Evaluation Block.
  9. DB - Optional tab, or multiple tabs if more than 1 Discard Block is selected. Only visible if one of more Discard Blocks are enabled in the Evaluation Block. Only available in Build 138 or later.
  10. Split - Optional tab, only visible if SplitFlows is enabled.
    • This tab is only available for Steady State mode.
  11. SplitT - Optional tab, only visible if SplitThermal is enabled.
    • This may only be enabled after SplitFlow has been enabled.
    • This tab is only available for Steady State mode.
  12. QFeed - Optional tab, only visible if ShowQFeed is enabled. This page shows the properties of the mixed stream as the feed to the tank. If user has specified a required pressure in the tank, the mixed feed will be set to this pressure. This may cause the temperature of the mixture to change if the delta P is significantly different.
  13. QProd - Optional tab, only visible if ShowQProd is selected. This page shows the properties of the mixed output stream as the product before separation to outlet streams of the tank.
    • This is after any Evaluation Block sub-models or the HX are evaluated, but before flow splits.
    • This tab is only available for Steady State mode.
  14. Info tab - Contains general settings for the unit and allows the user to include documentation about the unit and create Hyperlinks to external documents.
  15. MP tab - Optional tab, only visible if Procedures have been enabled on the Info tab page.
  16. Links tab, contains a summary table for all the input and output streams.
  17. Audit tab - Contains summary information required for Mass and Energy balance. See Model Examples for enthalpy calculation Examples.
  18. Additional fields are shown in Dynamic mode. These are described in the Tank - Dynamic Mode.

Tank Page

Unit Type: Tank-1 - The first tab page in the access window will have this name.

Tag (Long/Short) Input/ Calc Description
Tag Display This name tag may be modified with the change tag option.
Condition Display OK if no errors/warnings, otherwise lists errors/warnings.
ConditionCount Display The current number of errors/warnings. If condition is OK, returns 0.
GeneralDescription / GenDesc Display This is an automatically generated description for the unit. If the user has entered text in the 'EqpDesc' field on the Info tab (see below), this will be displayed here.
If this field is blank, then SysCAD will display the unit class ID.
Requirements
OperatingP - NOTE: this pressure is applied to the (combined) feed, before sub-models (if any).
Method AutoDetect If there are any liquids AND no vapours present in the feed, outlet streams will take the highest pressure of the feeds. Else (eg. some vapours present) outlet streams will take the lowest pressure of the feeds.
LowestFeed Outlet streams will take the lowest pressure of the feeds.
HighestFeed Outlet streams will take the highest pressure of the feeds.
Atmospheric Outlet streams will be at Atmospheric Pressure. The atmospheric pressure is calculated by SysCAD based on the user defined elevation (default elevation is at sea level = 101.325 kPa). The elevation can be changed on the Environment tab page of the Plant Model.
RequiredP Outlet streams will be at the user specified pressure.
IgnoreLowMassFlow / IgnoreLowQm Tick Box This option is only visible if the AutoDetect, LowestFeed or HighestFeed methods are chosen. When calculating the outlet pressure and temperature of the tank, SysCAD will ignore the low flow feed streams should this option be selected. The low flow limit is set in the field below.
LowMassFlowFrac / LowQmFrac Input This field is only visible if the IgnoreLowQm option is selected. This is the amount any stream contributes to the total flow. For example, if the total feed to the tank is 10 kg/s, and this field is set to 1%. Then any feed streams with less than 0.1 kg/s will be ignored in the pressure calculations.
PressureReqd / P_Reqd Input This field is only visible if the RequiredP method is chosen. This is user specified pressure.
Result Calc The actual pressure used for the sum of the feeds which will also be the outlet pressure (unless further model options change the pressure).
ResTime (Residence Time)
Volume Input Only visible if the Calc option has been enabled. The operating volume of the unit. This will be used to calculate the apparent residence time in the unit. This is based on the volumetric flow of all outlets from the unit.
Slurry Calc Only visible if the Calc option has been enabled. The residence time of the slurry in the unit.
Total Calc Only visible if the Calc option has been enabled. The residence time for the slurry and the vapours in the unit. If there are any vapours leaving the unit, then this value will be smaller than the Slurry figure.
EB (Flow Evaluation Block)
Solubility.On Tickbox Only visible if Solubility has been defined for at least one species in the project. Allows the user to switch on any predefined solubility curve to adjust the composition of material in the unit.
[email protected] Tickbox Only visible if Phase Change at Temperature has been defined for at least one species in the project and Plant Model - Species Tab - [email protected] = OFF. Allows the user to switch on any predefined phase changes at temperature in the unit.
EvalSequence Calc The sequence in which the sub models (which are part of the evaluation blocks) will be calculated. The sequence is determined by the priority selection for the individual sub-models.
Note: If the user chooses On-AutoSequence then SysCAD will determine the sequence of the sub-models. The auto evaluation sequence followed will be the order the sub models are listed below.
Makeups Input The number of Makeup Blocks required. Extra dropdown options Makeup1, Makeup2, etc will be added to allow these to be switched on and off and prioritised in relation to the other sub-models.
MakeupX List This can be used to switch the Makeup Block (MU) on or off and prioritise it in relation to the other sub-models. If this is 'On' then the associated page, MUX becomes visible and may be configured.
Note: This field is only visible if the entry for 'Makeups' is greater than 0. If there is one makeup then X=1. If there are two makeups, then X=1 and X=2, etc.
Reactions List Reaction Block (RB) - Enable or disable Reactions and set the sequence in relation to the other sub-models. If this is 'On' then the associated page, RB becomes visible and may be configured.
Note: The user does not have to configure a reaction file, even if this block is checked.
HeatXChg List This can be used to switch on the Heat Exchanger (HX). If this is 'On' then the associated page, HX becomes visible and may be configured.
Note: The user does not have to configure the heat exchange, even if this block is checked.
EnvironHX List Environmental Heat Exchanger (EHX) - Enable or disable Environmental Heat Exchange and set the sequence in relation to the other sub-models. If this is 'On' then the associated page, EHX becomes visible and may be configured.
Note: The user does not have to configure an environmental heat exchange, even if this block is checked.
Evaporation List Evaporation Block (Evap) - Enable or disable the Evaporator and set the sequence in relation to the other sub-models. If this is 'On' then the associated page, Evap becomes visible and may be configured.
Note: The user does not have to configure an evaporator, even if this block is checked.
VLEquilibrium List Vapour Liquid Equilibrium (VLE) - Enable or disable Vapour Liquid Equilibrium and set the sequence in relation to the other sub-models. If this is 'On' then the associated page, VLE becomes visible and may be configured.
Note: This option may automatically adjust the species make-up.
Discard Input Only available in Build 138 or later. The number of discard blocks required. Extra dropdown options Discard1, Discard2, etc will be added to allow these to be switched on.
DiscardX List Only available in Build 138 or later. This can be used to switch the Discard Block (DB) on or off and prioritise it in relation to the other sub-models. If this is 'On' then the associated page, DBX becomes visible and may be configured.
Note: This field is only visible if the entry for 'Discards' is greater than 0. If there is one discard then X=1. If there are two discards, then X=1 and X=2, etc.
Options
SplitFlows Tick Box This can be used to enable the Flow separate for output streams. If this box is checked then the associated page, Split, becomes visible and may be configured.
Notes:
  1. This option is used to adjust the outgoing streams from the unit. It cannot be changed while the model is solving.
  2. This option is not available in Dynamic mode.
SplitThermal Tick Box This option is only visible if the SplitFlows option has been chosen. This can be used to enable the uneven Energy distribution for output streams. If this box is checked then the associated page, SplitT, becomes visible and may be configured.
Notes:
  1. This option is used to adjust the temperatures of the outgoing streams from the unit. It cannot be changed while the model is solving.
  2. This option is not available in Dynamic mode.
ShowQFeed Tick Box QFeed and associated tab pages (eg Sp) will become visible, showing the properties of the combined feed stream. See Material Flow Section. This will be prior to any sub-model (eg reactions) actions.
ShowQProd Tick Box QProd and associated tab pages (eg Sp) will become visible, showing the properties of the products. See Material Flow Section. This will be after the actions of any sub-models and before any flow splits with the GM model. This option is not available in Dynamic mode.

Split (Flow) Tab Page

The Split tab page can be used to specify how flow is distributed down stream.

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 SplitFlow - 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 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 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 and later. 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 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 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 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.

Split Thermal Tab Page

The Split Thermal (SplitT) tab page can be used to specify how heat is distributed with the streams.

Tag (Long/Short) Input/Calc Description
Mixture temperature before thermal split
Feed.Temp Feedback The temperature of the mixture before splitting of streams - this is the temperature in the unit.
Condition Feedback OK if no errors, otherwise displays error message.
AllowHX Tickbox Selecting this option allows the user to specify temperatures for all outgoing streams. SysCAD will add or remove energy to conserve the energy across the unit operation. Any energy added/removed will be shown on the PowerInput field.
PowerInput/HeatFlow FeedBack This is visible when the AllowHX option has been enabled. This shows the amount of energy added or removed in order to achieve temperatures specified by the user.
TIOs.[stream name](IO)...
Order FeedBack This can be changed using the Priority field (if available).
Priority List This is used to change the order of the output streams if the Required or Change modes are selected.
Mode (See
Options and Examples for more info)
Required The user may specify the required temperature of the outlet stream. This temperature may be limited by the temperature change limits specified.
Change The user may specify the required temperature change for the outlet stream. This temperature may be limited by the temperature change limits specified.
FreeDiff The user can set a temperature difference for the selected outlet stream to the streams that are set at Free. For example, if the unit operation has two outlet streams, stream 1 is set at FreeDiff = 10, stream 2 is set at Free, then Stream 1 will be 10 degrees hotter than stream 2 when solved. This temperature may be limited by the temperature change limits specified.
Free The user may not specify any outlet temperature requirements, SysCAD will determine the outlet temperature. If Free is used for all streams then all streams will have the same outlet temperature (same behaviour as when SplitT model is not used at all).
TempReqd Input This is visible with mode set to Required, use this to specify the stream outlet temperature.
TempChange Input This is visible with mode set to Change, use this to specify the stream outlet temperature change.
TempDiff Input This is visible with mode set to FreeDiff, use this to specify the stream outlet temperature difference for the current stream and the streams that are set at Free.
TempOut FeedBack This is the outlet temperature for the stream.
Result FeedBack This shows whether the user specified temperature conditions have been achieved.
Temperature change limits
FinalT.Min Input The minimum temperature of the mixture leaving the unit operation. If the balance stream temperature falls below this minimum when the AllowHX option is ticked, heat will be added to make it up to the minimum temperature. If AllowHX option is not selected, all outlet stream temperatures will be adjusted to keep a balance of heat.
FinalT.Max Input The maximum temperature of the mixture leaving the unit operation. If the balance stream temperature is above this maximum when the AllowHX option is ticked, heat will be removed to limit it to the maximum temperature. If AllowHX option is not selected, all outlet stream temperatures will be adjusted to keep a balance of heat.
ChangeT.Limit Tickbox Selecting this option allows the user to specify temperature limits for all outgoing streams. If AllowHX option is selected, SysCAD will add or remove heat to conserve the energy across the unit operation. Any energy added/removed will be shown on the PowerInput field.
ChangeT.MaxDrop Input Only visible if ChangeT.Limit is enabled. This is the maximum amount that any stream be below the Feed temperature of the SplitT block.
ChangeT.MaxRise Input Only visible if ChangeT.Limit is enabled. This is the maximum amount that any stream be above the Feed temperature of the SplitT block.

Dynamic Mode Data Sections

The fields which appear in the access window for the tank in Dynamic mode only are shown in Tank - Dynamic Mode.

Adding this Model to a Project

Insert into Configuration file

Sort either by DLL or Group.

  DLL:
Basic1.dll
Units/Links Process: Tank(1)
or Group:
General
Units/Links Process: Tank(1)

See Model Selection for more information on adding models to the configuration file.


Insert into Project

  Insert Unit Process Tank(1)

See Insert Unit for general information on inserting units.

Hints and Comments

  1. If the user configures the GM, and then at a later stage adds or removes a stream (input or output), this may have an impact on the GM configuration. It is recommended that the user check the GM every time a stream change is made.
  2. In Steady State, the Tie model is almost identical to the tank model, except that the Tie does not have the Heat Exchanger (HX) sub-model.
  3. In Steady State, the tank model can be used with Demand.
  4. There may be mass entering or leaving the tank via the Reaction Block source or sink, so if the outgoing mass is not the same as the incoming mass, this may be a place to check first.
  5. If the user 'Resets' or uses the 'Empty Process' SetState option, then all connecting flanges will also be set to zero flow.
  6. If the user defined pressure is very different to the feed stream pressure, then this may cause the temperature change to be quite significant. If the inlet temperature is already high, then it is possible for the temperature to go above the critical temperature of water. In this case, the unit will return an energy imbalance error message. To avoid this issue, please consider using the Flash Tank so that VLE, T and P can be solved simultaneously in an iterative process.