Potash Evaporator

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Navigation: Main Page -> Models -> Energy Transfer Models

Related Links: Solid-Liquid Separator, Evaporator, Potash Solubility

This model is only available in SysCAD 9.2 Build 134 and later.


General Description

The Potash Evaporator is only available to users with the Potash add-on.

The unit may be operated at a user defined temperature or pressure, or it may be part of a Flash Train. SysCAD will attempt to run the unit at equilibrium at the required temperature or pressure. This may involve vapour to be flashed in the unit, with a subsequent increase in concentration of the remaining solution.

If the user enables Solubility and selects Potash solubility, if either KCl or NaCl are above their saturation values they will precipitate out as the crystal product. Alternatively, the user may use the Reaction Block (RB) to set the precipitation reaction and extent.

The unit has a 'Body' and a 'Leg'. The Body section receives the main unit feeds, recycles solution to the heat exchangers and the overflow and vent streams come from this section. The crystals drop into the Leg section and are usually washed with the solution in the 'Leg Feed'. The product is then discharged from the Evaporator leg.

Operational Modes

There are two operational modes for the Potash Evaporator:

  1. as a stand-alone unit; or
  2. as part of a Flash Train.

The user sets the required operational mode of the Potash Evaporator. However, if the user sets the mode as Flash Train and the Potash Evaporator is NOT connected to another Evaporator (Embedded Shell), Barometric Condenser, Heat Exchangers of any Flash Train aware destination unit, the model will go to an error state.

Available Sub-Models

Sub-Models Feed Block Body Block Leg Block Description
Solubility No Yes Yes May be enabled in the Body and Leg. This is required to automatically calculate the KCl and NaCl solubility.
Makeup Blocks (one or more) Yes No No This allows the user to control the addition of streams such as reagents or brine to the Potash Evaporator, often without having to use a PID or General controller.
Reaction Block (RB) Yes No Yes Allows the user to configure any number of reactions in the Feed or Leg of the Evaporator.
Environmental Heat Exchanger Block Yes No No Allows the user to add or remove energy from the Evaporator using a number of different methods.
Vapour Liquid Equilibrium Block No Yes No ALWAYS enabled in an Evaporator. This will attempt to ensure that the water and steam will be in equilibrium in the unit.

Heat Exchange Options

The unit may also have connections to an Embedded or to an External Heat Exchanger.

Often Evaporators are operated by recycling the liquor through one or more heat exchangers. This model allows the user to embed these heat exchangers as part of the model. (This is often more efficient when carrying out the modelling calculations.)

The user sets the amount of flow to the heat exchanger, either as a fixed flowrate or as a fraction of the throughput. This flow will then be heated in either the embedded heat exchanger, or sent to an External heat exchanger via the Recycle outlet.

The user may select any of the following 3 options for heat exchange:

  1. None - no Heat Exchange is required.
  2. Embedded - The Embedded Heat Exchange model uses a Shell and Tube style heat exchanger. The user connects the Steam (or other cooling or heating medium) to the Embedded HX Shell input port and the Condensate (or return heat exchange medium) to the Embedded HX Shell output port. The recycle flow to the heat exchanger must to be specified, but this is handled internally within the unit.
  3. External - A recycle stream from the Potash Evaporator is heated, or cooled, in a separate Heat Exchanger unit. The user must connect the Recycle output port from the Potash Evaporator to an external heat exchanger. This recycle stream is then either heated or cooled and returned to the Potash Evaporator via the Recycle input port.

NOTES:

  1. The difference between the two heat exchange methods:
    • With embedded heat exchange, the steam and condensate streams (or other heat exchange medium) are connected directly to Potash Evaporator via the Embedded HX Shell connections. The Recycle stream to the heat exchanger is handled internally within the unit.
    • With external heat exchange, the recycle stream is sent to an external heat exchanger via the Recycle connection and returned to the Potash Evaporator via the Recycle connection.
  2. For both internal and external heat exchange the user must set the recycle flow to the heat exchanger.


Diagram

Potash Evaporartor.png

  • The above 2 diagrams show the Potash Evaporator with and without an embedded heat exchanger.
  • The physical location of the streams connecting to and from the Potash Evaporator is unimportant. The user may connect the streams to any position on the unit.
  • When inserting a Potash Evaporator into a flowsheet, the user may choose a different symbol from the menu.
  • Many of the above connections are optional. Please see the Input/Outputs table below for further information.

Inputs and Outputs

Label Required
Optional
Input
Output
Number of Connections Description
Min Max.
Feed 1 Required In 1 20 Feed to the main body of the Potash Evaporator.
Leg Feed Optional In 0 10 Potash Evaporator Leg feed - this is often a wash stream for the crystals.
Embedded HX Shell Optional In 0 10 Inlet stream to the Shell side of Embedded Shell and Tube Heat Exchanger (often the steam inlet).
Recycle Optional In 0 10 Recycle stream from external Heat Exchanger(s).
Product Required Out 1 1 Product Slurry outlet - this stream flows from the evaporator leg and normally contains the crystals.
Vent Required Out 1 1 Vent outlet containing all Vapours from the unit.
Overflow Optional Out 0 1 Overflow liquor outlet - this stream flows from the body of the evaporator and normally contains very little solids.
Embedded HX Shell Optional Out 0 1 Outlet stream from the Shell side of Embedded Shell and Tube Heat Exchanger (often the condensate).
Recycle Optional Out 0 1 Recycle stream from the Potash Evaporator to external Shell and Tube Heat Exchanger(s).

Behaviour when Model is OFF

If the user disables the unit, by un-ticking the On tick box, then the following actions occur:

  • All material in streams connected to the 'Feed' inlet will flow straight out of the 'Product' outlet, with no change in phase or energy exchange with material flowing through the internal heat exchanger;
  • All material in streams connected to the 'Embedded HX Shell' connections will have no change in phase or energy exchange with material flowing through the Potash Evaporator;
  • No sub-models will be called.

So basically, the unit will be 'bypassed' without the user having to change any connections.

Model Theory

Vapour Liquid Equilibrium

The unit is configured to achieve vapour : liquid equilibrium at a required pressure (or temperature) using the user defined VLE method. Any solids that may be in the stream entering the unit are ignored in the flash calculations. However the enthalpy balance does include the solids. For further information on the theory for the VLE calculations see Vapour Liquid Equilibrium (VLE).

Solubility

If Potash Solubility is enabled in the Potash Evaporator then the solubility calculations will be performed simultaneously with the VLE calculations. Therefore, the product from the Potash Evaporator will contain liquid at, or below, the saturation value of KCl, NaCl and optionally CaSO4.

Flow Chart

Potash Evaporator Flow Diagram Rev 2.jpg

Data Sections

The default access window consists of several sections:

  1. PotashEvaporator - The first tab contains general information that can be set by the user.
  2. Results - This tab contains the unit results.
  3. HX - Optional tab, only visible if an Embedded Heat Exchanger is selected. (In this case the Embedded HX Shell connections should be connected).
  4. RB - Optional tab, only visible if the Reactions are enabled in the Feed Evaluation Block.
  5. EHX - Optional tab, only visible if the EnvironHX is enabled in the Feed Evaluation Block.
  6. MU - Optional tab, or multiple tabs if more than 1 Makeup is selected. Only visible if one of more Makeup is enabled in the Feed Evaluation Block.
  7. VLE - Always visible. This is calcualted in the Body of the Evaporator.
  8. PC - Optional tab, only visible if the Solubility is enabled in the Body Evaluation Block.
  9. LPC - Optional tab, only visible if the Solubility is enabled in the Leg Evaluation Block.
  10. LRB - Optional tab, only visible if the Reactions are enabled in the Leg Evaluation Block.
  11. QFeed - Optional tab, only visible if ShowQFeed is enabled. This page shows the properties as a mixed stream of all of the Feed streams to the Potash Evaporator. This EXCLUDES the recycle from the external heat exchanger, if there is one.
    • This is before any Evaluation Block models are evaluated.
  12. QBodyFeed - Optional tab, only visible if ShowQBodyFeed is enabled. This page shows the properties of the mixed stream as the feed to the Body of the Potash Evaporator.
    • This is before any Evaluation Block models are evaluated.
  13. QProd - This page shows the properties of the Potash Evaporator discharge as a single stream.
    • This is AFTER the flash calculations, but before the split to slurry, overflow and vapour streams.
  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. Links tab - contains a summary table for all the input and output streams.
  16. Audit tab - contains summary information required for Mass and Energy balance. See Model Examples for enthalpy calculation Examples.


Potash Evaporator Page

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

Tag (Long/Short)
Input / Calc
Description
Common Data on First Tab Page

Requirements:

On Tickbox This variable in used to turn the unit ON or OFF. If this not ticked, the material will flow out of the Product outlet with no change in state, i.e. the unit acts as a pipe.
Mode Stand Alone (Manual) The Evaporator will act as a 'Stand Alone' unit and the user may set the required operating Pressure or Temperature.
Flash Train The Evaporator Body will act as part of a Flash Train. In this mode the Evaporator vent must be connected to a steam consumer, such as a Barometric Condenser, Shell and Tube Heat Exchanger, Shell and Tube Heat Exchanger 2 or a Direct Contact Heater. The steam requirements of the steam consumer will drive the operating pressure of the Evaporator, therefore the user may NOT set the operating temperature or pressure.
Note If the Evaporator does have an embedded Heat Exchanger, this can be set up separately as part of a Flash Train.
OperatingP

The user may only set the operating pressure or temperature of the Evaporator if it is NOT part of a Flash Train.

Method Atmospheric All flash calculations will be done 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 All flash calculations will be done at the user specified pressure.
RequiredT All flash calculations will be done at the user specified temperature.
PressureReqd / P_Reqd Input The Required Flash Pressure - This is only visible if the RequiredP Method is selected.
TemperatureReqd / T_Reqd Input The Required Flash Temperature - This is only visible if the RequiredT Method is selected.
Result Display This field displays the operating pressure of the Evaporator.
MinFlashP Input The minimum Pressure at which the Evaporator may operate. This is useful if the Evaporator is configured as part of a Flash Train, as it will not allow the unit to drop to an unrealistic pressure. This is only visible if the unit is operated as part of a Flash Train.

Feed Evaluation Block

These sub-models operate on the combined Feed streams.

EvalSequence Display 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 sequence followed will be MU1,MU2, etc., RB, EHX.
Makeups Input The number of makeup blocks required. Extra drop-down 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 then 0. If there is one makeup then X=1. If there are two makeups, then X=1 and X=2, etc.
Reactions List This can be used to switch on the Reaction Block (RB). 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.
EnvironHX List This can be used to switch on the Environmental Heat Exchanger (EHX). If this is 'On' then the associated page, EHX may become visible and may be configured.
Note: The user does not have to configure an environmental heat exchange, even if this block is checked.

Body Evaluation Block

These sub-models operate on the streams to the Evaporator body.

Solubility.On Tickbox The user may enable the solubility in the body. This MUST be enabled if the Potash Evaporator is required to automatically calculate the precipitation of KCl and NaCl.
EvalSequence Display This will always only display VLE.
VLEquilibrium Display Vapour Liquid Equilibrium (VLE) is always ON in the Evaporator - the user may NOT turn it off.

Leg Evaluation Block

These sub-models operate on the streams to the Evaporator leg.

Solubility.On Tickbox The user may enable the solubility in the leg. This MUST be enabled if the Potash Evaporator Leg is required to automatically calculate the precipitation of KCl and NaCl.
EvalSequence Display This will display either LRB, if the reactions are enabled, or nothing.
Reactions List This can be used to switch on the Reaction Block (RB) in the Leg. If this is 'On' then the associated page, LRB becomes visible and may be configured.
Note: The user does not have to configure a reaction file, even if this block is checked.
Fraction of Leg Feed Liquid reporting to Evaporator Body
LegFeedToBody Input The Required fraction of the liquid in the leg feed that reports directly to the Evaporator body. The remainder flows to the leg section. Note that all solids in the Leg Feed stream will always report directly to the leg.

Evaporator Heat Exchanger Options

HXType None The unit is not connected to a Heat Exchanger. No other fields are visible for the Heat Exchanger if this option is chosen.
External The Evaporator is connected to an External Heat Exchanger unit. This external unit may be any type of SysCAD model.
Embedded Heater The Evaporator contains an Embedded Heater. If this option is chosen, an additional page HX becomes visible and the user configures the Heat Exchanger within the Evaporator.
HXOut.SplitMethod Off No flow is sent to the Heat Exchanger.
Ratio to Feed MassFlow The flow to the Heat Exchanger (either Embedded or External) is a Ratio of the Feed mass. The composition and temperature of the stream to the Heat Exchanger is the same as the Combined Feed to the Evaluation Block.
Ratio to Prod MassFlow The flow to the Heat Exchanger (either Embedded or External) is a Ratio of the Product mass. The composition and temperature of the stream to the Heat Exchanger is the same as the Product from the Evaluation Block.
Note: The Product mass includes both the Overflow and the Product streams.
MassFlow The flow to the Heat Exchanger (either Embedded or External) is a fixed mass flow. The composition and temperature of the stream to the Heat Exchanger is the same as the Product from the Evaluation Block.
Note: The Product mass includes both the Overflow and the Product streams.
VolumeFlow The flow to the Heat Exchanger (either Embedded or External) is a fixed volumetric flow. The composition and temperature of the stream to the Heat Exchanger is the same as the Product from the Evaluation Block.
Note: The Product mass includes both the Overflow and the Product streams.
MassFlow Per Heater This option can be used for the Embedded Heater option, where user can define the number heaters used. The flow to each Embedded Heater is mass based. The composition and temperature of the stream to the Heat Exchanger is the same as the Product from the Evaluation Block.
Note: The Product mass includes both the Overflow and the Product streams.
VolumeFlow Per Heater This option can be used for the Embedded Heater option, where user can define the number heaters used. The flow to each Embedded Heater is volume based. The composition and temperature of the stream to the Heat Exchanger is the same as the Product from the Evaluation Block.
Note: The Product mass includes both the Overflow and the Product streams.
HXOut.RatioToFeedQm Input The flow to the Heat Exchanger (either Embedded or External) is Feed Flow times by Ratio.
HXOut.RatioToProdQm Input The flow to the Heat Exchanger (either Embedded or External) is Product Flow times by Ratio.
Note: The Product mass includes both the Overflow and the Product streams.
HXOut.MassFlowReqd Input The required Product mass flow to the Heat Exchanger (either Embedded or External).
HXOut.VolumeFlowReqd Input The required Product volumetric flow to the Heat Exchanger (either Embedded or External).
HXOut.EachHeaterQmReqd Input The required Product mass flow to the each Heater (Embedded Heater method only).
HXOut.EachHeaterQvReqd Input The required Product volumetric flow to the each Heater (Embedded Heater method only).

OverFlow and Product Split

CalcSplitMethod Simple Estimate The model will do a simple estimate to calculate the liquid split required from the body to the leg to give the desired solids fraction in the product.
Iterative The model will iteratively calculate the liquid split required from the body to the leg to give the desired solids fraction in the product.
OFSolSaltsReqd Input The required solid salts species fraction in the overflow stream. Salts species include KCl, NaCl and MgCl2.
GypsumSplitMethod
Note: 'Gypsum' includes CaSO4.2H2O(s) and CaSO4(s)
Follow Solid Salts The fraction of gypsum to the Overflow stream will be the same as the solid salts fraction to the Overflow stream.
All to OF All of the gypsum from the Evaporator body will report to the Overflow stream. Note - there may be some gypsum in the Leg that reports to the Product stream.
None to OF None of the gypsum in the Evaporator body will report to the overflow stream, i.e. it will all report to the Product stream.
User Frac to OF The user may define the fraction of gypsum in the Evaporator body that will report to the Overflow stream.
GypsumToOF Input The required fraction of gypsum in the Evaporator body that will report to the Overflow stream. This field is only visible if the user selects User Frac to OF.
OtherSolidSplitMethod
'Other Solids' are any solid
species that are not
gypsum or salts,
i.e. NOT KCl, NaCl, MgCl2 or gypsum.
Follow Solid Salts The fraction of other solids to the Overflow stream will be the same as the solid salts fraction to the Overflow stream.
All to OF All of the other solids from the Evaporator body will report to the Overflow stream. Note - there may be some other solids in the Leg that report to the Product stream.
None to OF None of the other solids in the Evaporator body will report to the overflow stream, i.e. they will all report to the Product stream.
User Frac to OF The user may define the fraction of other solids in the Evaporator body that will report to the Overflow stream.
OtherSolidToOF Input The required fraction of other solids in the Evaporator body that will report to the Overflow stream. This field is only visible if the user selects User Frac to OF.
ProductSolidFracReqd Input The required solids fraction in the Product Stream.
Options
VapStandardSpModel Tickbox This forces the vent stream to revert to the Standard species model. If this is NOT ticked, then the species model in the vent will be the same as the species model used in the Evaporator.
Normally this is left ticked, as the vent contains steam and the Standard species model will calculate all of the properties of steam correctly.
ShowQFeed Tick Box QFeed and associated tab pages (e.g. Qm) will become visible if this is enabled. These tabs will show the properties of the combined feed stream to the Unit. These values are BEFORE the Evaluation Block is processed.
ShowQBodyFeed Tick Box QBodyFeed and associated tab pages (e.g. Qm) will become visible if this is enabled. These tabs will show the properties of the combined feed stream to the Evaporator Body.
ShowQRecycle Tickbox This is only visible if an Embedded Heater is used. If this option is ticked then the recycle stream to the Heat Exchanger is displayed as 'QRecycle' and the user may access properties of the stream feeding the Heat Exchanger.
ShowQProd Tick Box QProd and associated tab pages (e.g. Qm) will become visible if this is enabled. These tabs will show the properties of the product stream from the Unit, AFTER the Evaluation Block is processed, but BEFORE the stream is split to overflow and product.
ShowResultsTable Tick Box This adds a section in the Results Page showing a summary of QFeed, QBodyFeed and QProd Results.

Results Page

The page contains the results fields.

Tag (Long/Short)
Input / Calc
Description

Operating Conditions

TemperatureIn / Ti Calc The temperature of the combined Feed stream to the Evaporator. (This is a normally hidden field)
PressureIn / Pi Calc The pressure of the combined Feed stream to the Evaporator. (This is a normally hidden field)
VapFlashed.MassFlow / VapFlashed.Qm Calc The quantity of flashed vapour.
BPE Calc The Boiling Point Elevation used in the Flash calculations in the Evaporator.
FlashT Calc The final temperature (the Flash Temperature) in the Evaporator.
FlashP Calc The final pressure (the Flash Pressure) in the Evaporator.
Flash Train Macro Model

These extra fields are only visible if the unit is part of a Flash Train.

VapourMassFlow / VQm Calc The quantity of flashed vapour.
PressureReqd / P_Reqd Calc The required flash pressure calculated by the Flash Train.
FlashTrain Display A unique tag assigned to the Flash Train by SysCAD. Each unit in the Flash Train will have the same tag in this block.
FlashTearBlock Display Displays the name of the tear block that is part of the Flash Train.
FlashTrainEqp List This contains a list of all of the equipment tags in this Flash Train. For example, the list might be as follows:

Heat_Exchanger_2

Evaporator_1

Summary of QFeed, QBodyFeed and QProd Results

This Summary table is only visible when the ShowQResultsTable option has be ticked (located in the PotashEvaporator Tab). It shows the values of each of the following variables for
  • QFeed
  • QBodyFeed and
  • QProd
Temperature / T Calc The Temperature in each stream.
MassFlow / Qm Calc The total mass flow in each stream.
SolidMassFlow / SQm Calc The mass flow of solids in each stream.
SolidFrac / Sf Calc The solids fraction in each stream - this includes all solids and gypsum.
SolSaltsQm Calc The mass flow of solid salts (KCl and NaCl) in each stream.
SolSaltsFrac Calc The mass frac of solid salts (KCl and NaCl) in each stream.
GypsumMassFlow / GypsumQm Calc The mass flow of Gypsum in each stream.

Summary of Input and Output Streams

This Summary table shows the values of each of the following variables for the Feed and Product streams that are connected to the Evaporator. The possible streams are:
  • Feed - this will display the values for the total Feed stream = Sum of all feed streams connected to the unit.
  • Leg Feed (LF)- this will display the values for the total Leg Feed stream = Sum of all leg feed streams connected to the unit. This will only be visible if there are any streams connected to the Leg Feed connection.
  • Vapour - this will display the values for the Vent stream from the unit.
  • Overflow (OF)- this will display the values for the Overflow stream from the unit, if it is connected.
  • Product (Prod) - this will display the values for the Product stream from the unit.
Temperature / T Calc The Temperature in each stream.
MassFlow / Qm Calc The total mass flow in each stream.
SolidMassFlow / SQm Calc The mass flow of solids in each stream.
SolidFrac / Sf Calc The solids fraction in each stream - this includes all solids and gypsum.
SolSaltsQm Calc The mass flow of solid salts (KCl and NaCl) in each stream.
SolSaltsFrac Calc The mass frac of solid salts (KCl and NaCl) in each stream.
GypsumMassFlow / GypsumQm Calc The mass flow of Gypsum in each stream.

Results

LegBypass.MassFlow / LegBypass.Qm Calc The mass flow of material bypassed to the Leg.
Body.SolidsYield Calc The mass flow of solids in the Product - mass flow of solids in the Feed.
Leg.SolidsYield Calc The mass flow of solids in the Leg.
SolidsYield Calc The mass flow of solids in the Product - mass flow of solids in the Feed.
 
OF.AqSaltsFrac Calc Aqueous salts fraction in the Overflow.
Leg.SolidFrac / Leg.Sf Calc Solids fraction in the leg.
Leg.SolSaltsFrac Calc Solid Salts fraction in the leg.
Leg.AqSaltsFrac Calc Aqueous Salts fraction in the leg.
Internal Calculations
PrevLiqQmToUF Calc The amount of liquid mass flow to underflow in the previous iteration.
BodySolSaltsFracToLeg Calc Body solid salts fraction to leg.
BodyGypsumSolFracToLeg Calc Body solid gypsum fraction to leg.
BodyOtherFracToLeg Calc Body other solids (not including salts and gypsum) fraction to leg.
BodyLiqFracToLeg Calc Body Liquid fraction to leg.
CalcLegSplit.Iters Calc Number of iterations allow to calculate the split to leg.
Evaporator to Embedded or External Heater / Cooler
HXOut.MassFlow / HXOut.Qm Calc The mass flow to the specified Heat Exchanger.
HXOut.EachHeaterQm Calc The mass flow to the specified Heat Exchanger (per heater if more than one is used).
HXOut.VolFlow / HXOut.Qv Calc The volume flow to the specified Heat Exchanger.
HXOut.EachHeaterQv Calc The volume flow to the specified Heat Exchanger (per heater if more than one is used).
HXOut.Temperature / HXOut.T Calc The temperature of the stream to the specified Heat Exchanger.
Embedded Heater Recycle Loop convergence
RecycleConvergeMethod FullStream User can select to solve the recycle loop using Full stream data (loop has to solve and converge all mass and energy terms.)
Stream Mass Only User can select to solve the recycle loop using mass only. Loop will be solved when mass is converged, ignoring energy.
Duty User can select to solve the recycle loop using energy only. Duty from "shell" side of heat exchanger is added directly to the feed (recycle mass flow is not actually added). Loop will be solved when duty is matched, ignoring mass balance.
MaxIter(Global) Input The maximum number of iteration allowed within the recycle solver loop. Only shown for Stream Recycle Converge Methods.
Iter_Steps Calc The number of iteration used in the current step to solve the recycle loop. Only shown for Stream Recycle Converge Methods.
Iter_LastStep Calc The number of iteration used in the last step to solve the recycle loop. Only shown for Stream Recycle Converge Methods.
Iter_MaxInAStep Calc The maximum number of iterations (in a step) used to solve the recycle loop. Only shown for Stream Recycle Converge Methods.
Iter_Total Calc The total number of iterations used to solve the recycle loop. Only shown for Stream Recycle Converge Methods.
FeedMaxDuty Calc The maximum amount of Duty that can be added to feed before temperature exceeds water critical temperature. Only shown for Duty Recycle Converge Method.
Iter_Duty Calc The number of iterations to apply duty and flash. When this is greater then 1 then the Duty from the condensing steam is applied in iterations, the values displayed on the VLE page reflect this. Only shown for Duty Recycle Converge Method.

Adding this Model to a Project

Insert into Configuration file

Sort either by DLL or Group.

 

DLL:

PotashUnits.dll

Units/Links

Heat Transfer: Evaporator - Potash

or

Group:

Potash

Units/Links

Heat Transfer: Evaporator - Potash

See Project Configuration for more information on adding models to the configuration file.


Insert into Project

 

Insert Unit

Heat Transfer

Evaporator - Potash

See Insert Unit for general information on inserting units.

Hints and Comments

  1. There may be mass entering or leaving the unit 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.
  2. The information in the VLE Section must be correct for the Evaporator to operate as required. If the VLE configuration requires information that is not available, then the flashing will not occur.