Thickener 2

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Navigation: Models ➔ Mass Separation Models ➔ Thickener 2

Thickener Thickener 2 (for Dynamic Projects)

General Description

The Thickener 2 model is mainly used in the Dynamic mode to separate solids from the liquids in the feed stream.

  • The user may set the fraction of solids and liquids in the Input stream (usually the wash stream) to bypass directly to the Clarified Liquid portion of the unit.
  • The user may add Reactions, Makeups, energy transfer and Solubility to the combined Feed stream of this unit.
  • The user defines the percentage solids in both the underflow and the overflow from the unit. The Thickener will calculate the liquid split to the under and over flows to satisfy the user defined solids percentages.
  • If there is insufficient solids in the feed to the Thickener to satisfy both the under and over flow requirements, the unit will try to satisfy the underflow solids / liquids requirements first.

There are 2 dynamic operating modes:

  1. Calculated underflow rate - here the model calculates the required underflow rate to give the user defined underflow solids fraction. This rate is then set by the model and the user may not adjust this value. This is useful for projects with large step sizes that require the thickener to act as solid/liquid splitter with volume, but no control.
  2. User defined underflow rate - The model does NOT set the underflow rate from the thickener. This can be controlled by the user or a controller in the project. This mode is useful when the project has smaller step sizes and the thickener control must be emulated.

Note: The UF pipe demand option allows both pull and/or capacity (including batch capacity). Where both are present it uses the minimum. When the capacity is off or unrestricted, the logic falls back to unit operation settings for that outlet.

Diagram

Thickener2-Image001.gif

The diagram shows the default drawing of the Thickener, with all of the streams that have to be connected for the unit to operate.

The physical location of the streams connecting to the Thickener is unimportant. The user may connect the streams to any position on the unit.

Inputs and Outputs

Label Required / Optional Input /Output Number of Connections Description
      Min Max.  
Feed Required In 1 20 The slurry feed to the Thickener
Input Optional In 0 20 The wash water or liquor input to the Thickener
Overflow Required Out 1 1 Thickener overflow
Underflow Required Out 1 1 Thickener underflow
Vent Optional Out 0 1 Vent Stream (Vapour Only)

Model Theory

The thickener unit acts as a solid/liquid splitter. The user defines the operating parameters.

Flowchart

The following diagram shows the sequence of events in the Thickener 2 model.

Thickener 2 Flowchart.png

Data Sections

The default access window consists of a number of sections:

  1. Thickener2 - contains general information relating to the unit.
  2. Results - displays a summary of current parameters for the unit.
  3. PC - Optional tab that is visible if EB.Solubility.On and/or EB.PhaseChange@T.On is enabled in the Evaluation Block.
  4. RB - Optional tab, only visible if the Reactions are enabled in the Evaluation Block.
  5. EHX - Optional tab, only visible if the EnvironHX is enabled in the Evaluation Block.
  6. 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.
  7. QEBFeed - Optional tab, only visible if ShowQEBFeed is enabled. This page shows the properties of the mixed stream as the feed to the Evaluation Block sub-model.
    • This is before any Reactions are evaluated.
  8. Bed - Optional tab, only visible if ShowBed is enabled. This page shows the contents of the Thickener Bed.
  9. CL - Optional tab, only visible if ShowCL is enabled. This page shows the contents of the Clarified Liquid.
  10. PresetBed - Optional tab, only visible if UsePresetImg option is enabled on the first tab page under PresetData heading. Allows user to define the Preset Image composition of the Bed.
  11. PresetCL - Optional tab, only visible if UsePresetImg option is enabled on the first tab page under PresetData heading. Allows user to define the Preset Image composition of the Clarified Liquid.
  12. Info tab - contains general settings for the unit and allows the user to include documentation about the unit and create Hyperlinks to external documents.
  13. Links tab, contains a summary table for all the input and output streams.
  14. Audit tab - contains summary information required for Mass and Energy balance. See Model Examples for enthalpy calculation Examples.

Unit Type: Thickener2 - The first tab page in the access window will have this name.

Thickener2

Tag (Long/Short) Input / Calc Description/Calculated Variables / Options
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
On Tick Box This allows the user to enable or disable the unit.
OpMode Calc UF The thickener model calculates the underflow rate required to give the user defined solids fraction. This rate is set by the thickener and the user cannot set the underflow rate.
User UF (Qm) This operating mode allows the user to set the thickener underflow mass rate. This is the only option when the model is used in a steady-state project.
User UF (Qv) This operating mode allows the user to set the thickener underflow volumetric rate.
UF pipe demand This operating mode allows the thickener underflow rate to be set by the capacity setting in the underflow pipe.
UFQmReqd Input Only visible if OpMode = User UF (Qm). The required mass underflow rate.
UFQvReqd Input Only visible if OpMode = User UF (Qv). The required volumetric underflow rate.
OFSolidFracReqd Input The required overflow solids fraction.
UFSolidFracReqd Input The required underflow solids fraction.
LiqBypassFrac Input The fraction of wash water/liquor (Input) that must bypass straight to the clarified liquid layer. Any material in this bypass will NOT be involved in any Evaluation Block submodels such as reactions.
SolBypassFrac Input The fraction of feed slurry (Feed) that must bypass straight to the thickener bed. Any material in this bypass will NOT be involved in any Evaluation Block submodels such as reactions.
 
VolumeSpecMethod / Capacity.Defn None Only visible if OpMode = Calc UF. The thickener will operate like a steady-state unit model with no surge. This is the only option when the model is used in a steady-state project.
Total Mass The user only has to specify the total mass of the thickener and the fraction occupied by the solids bed.
Total Volume The user only has to specify the total volume and height of the thickener as well as the fraction occupied by the solids bed.
Capacity.Mass Input Only visible if VolumeSpecMethod = Total Mass. The total mass of material that the thickener can hold.
Capacity.Volume Input Only visible if VolumeSpecMethod = Total Volume. The total volume of the thickener.
Capacity.Height Input Only visible if VolumeSpecMethod = Total Volume. The total height of the thickener.
BedSizeFrac Input Only visible if VolumeSpecMethod = Total Mass or Total Volume. The target fraction occupied by the solids bed.
(The following two fields are only visible if VolumeSpecMethod = Total Mass or Total Volume. Only available in Build 139 or later.)
OpModeOF OF at Level The user can set the level at which the overflow stream is taken from.
OF pipe demand In addition to setting the level at which the overflow stream is taken from, the thickener overflow rate to be set by the capacity setting in the overflow pipe.
OFSizeFrac Input The target fraction for the overflow outlet.
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).
EB (Evaluation Block) (NOTE: These submodels act on the combined feed to the thickener, EXCLUDING any material which is bypassed.)
Solubility.On Tickbox Only visible if Solubility has been defined for at least one species in the project and Plant Model - Soluble Tab - Global.Solubility = OFF. Allows the user to switch on any predefined solubility curve to adjust the composition of material in the unit.
PhaseChange@T.On Tickbox Only visible if Phase Change at Temperature has been defined for at least one species in the project and Plant Model - Species Tab - PhaseChange@T = 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.
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.
Evap...
Method None There is no evaporation from the unit.
MassFlow The user may specify the mass flow of water vapour from the unit.
VolumeFlow The user may specify the volume flow of water vapour from the unit.
MassFlowReqd / QmReqd Input Only visible if the evaporation method is MassFlow. The required mass flow of evaporated water from the unit.
VolFlowReqd / QvReqd Input Only visible if the evaporation method is VolumeFlow. The required volume flow of evaporated water from the unit.
PresetData...
UsePresetImg Tick Box If this is enabled then the user may use the preset image to initialise contents of the Thickener. The PresetBed and PresetCL tab pages will be available for the user to configure the compositions of both the bed and clarified liquid layers of the Thickener.
(the following fields will only be displayed if the UsePresetImg option has been enabled)
Method Empty The contents of the Thickener will be emptied when Preset is enabled.
Full The Thickener will be full (maximum capacity) when Preset is enabled.
Mass The user may specify the preset bed and total mass.
Volume The user may specify the preset bed and total volume.
Level The user may specify the preset bed and total level.
Height The user may specify the preset height.
Temperature Input Only visible if the preset method is NOT set to Empty. The required temperature of the thickener contents after a Preset.
Bed.Mass Input Only visible if the preset method is set to Mass. The required mass of material in the bed after a Preset.
Mass Input Only visible if the preset method is set to Mass. The required total mass of material in the thickener after a Preset.
Bed.Volume Input Only visible if the preset method is set to Volume. The required volume of material in the bed after a Preset.
Volume Input Only visible if the preset method is set to Volume. The required total volume of material in the thickener after a Preset.
Bed.Level Input Only visible if the preset method is set to Level. The required level of material in the bed after a Preset.
Level Input Only visible if the preset method is set to Level. The required level of all material in the thickener after a Preset.
Height Input Only visible if the preset method is set to Height. The required height of all material in the thickener after a Preset.
Options
ShowQEBFeed Tick Box If this is enabled then the unit will display the combined feed stream to the thickener evaluation block. This will NOT include any material which is bypassed.
ShowBed Tick Box If this is enabled then the unit will display the contents of the Bed.
ShowCL Tick Box If this is enabled then the unit will display the contents of the Clarified Liquid layer.
Empty_Bed Button Clicking on this button will empty the contents of the Bed.
Empty_CL Button Clicking on this button will empty the contents of the Clarified Liquid layer.
Empty_All Button Clicking on this button will empty the total contents of the unit - both the Bed and Clarified Liquid layers.
FillNextIter Button If this is clicked then the unit will be set to 100% capacity in the next step.

Results tab page

Tag (Long/Short) Input / Calc Description/Calculated Variables / Options
Results
(the following fields are only visible when VolumeSpecMethod = Total Mass or Total Volume)
BedMassReqd Calc Only visible when VolumeSpecMethod = Total Mass. The required bed mass in the thickener.
CLMassReqd Calc Only visible when VolumeSpecMethod = Total Mass. The required clarified liquid mass in the thickener.
CLMassAvail Calc Only visible when VolumeSpecMethod = Total Mass. The available mass in the thickener. This is non-zero when the thickener is filling up. During normal operation this value is zero.
CLSurgeMassAvail Calc Only available in Build 139 or later. Only visible when VolumeSpecMethod = Total Mass. The available mass of the thickener above the overflow level, based on the total capacity of the thickener and the setting of OFSizeFrac. This is zero when OFSizeFrac is at 100%.
BedVolumeReqd Calc Only visible when VolumeSpecMethod = Total Volume. The required bed volume in the thickener.
CLVolumeReqd Calc Only visible when VolumeSpecMethod = Total Volume. The required clarified liquid volume in the thickener.
CLVolumeAvail Calc Only visible when VolumeSpecMethod = Total Volume. The available volume in the thickener. This is non-zero when the thickener is filling up. During normal operation this value is zero.
CLSurgeMassAvail Calc Only available in Build 139 or later. Only visible when VolumeSpecMethod = Total Volume. The available volume of the thickener above the overflow level, based on the total capacity of the thickener and the setting of OFSizeFrac. This is zero when OFSizeFrac is at 100%.
TotalMass / Mt Calc The total mass of material in the thickener.
InitTtlMass / InitMt Calc The initial mass of material in the thickener.
DeltaTtlMass / DeltaMt Calc The change in mass of material in the thickener from the beginning of the run (TotalMass - InitTtlMass).
TotalVol / Vt Calc The total volume of material in the thickener.
Bed.Level / Lvl Calc The Bed level. During normal operation this will be equal to the user specified BedSizeFrac.
Level / Lvl Calc The thickener level. During normal operation this is 100%.
OFSurge.Level / Lvl Calc Only available in Build 139 or later. The overflow surge thickener level. This is 0% when Level = OFSizeFrac. This is 100% when the Level is at 100%.
UF.MassFlowEst / QmEst Calc Only available in Build 137 or earlier. Only visible if OpMode = UF pipe demand. The required underflow mass rate based on the specified flow capacity of the underflow pipe.
MassRateOfChange / QmAcc Calc The net mass flow of material into the thickener.
(the following fields are always shown)
BypassMassFlow / BypassQm Calc The mass flow of material in the bypass streams.
VentMassFlow / VentQm Calc The mass flow of material in the vent stream.
EvapMassFlow / EvapQm Calc The mass flow of water evaporated.
EvapDuty Calc Only available in Build 137 or later. The energy required to evaporate the required amount of water at the current temperature.
HeatFlow Calc Only available in Build 137 or later. The external energy added (or removed) from the unit model.
EB.FeedMassFlow / FeedQm Calc The total mass flow of material in the feed to the Evaluation Block (EB).
EB.FeedSolidFrac / FeedSf Calc The fraction of solids material in the feed to the Evaluation Block (EB).
EB.ProdSolidFrac / ProdSf Calc The fraction of solids material in the product from the Evaluation Block (EB).
(the following section is only visible when VolumeSpecMethod = Total Mass or Total Volume)
Bed and Clarified Liquid layers
(the following parameters are shown in a table with columns for the Bed and Clarified Liquid (CL) layers)
FeedQm Calc The mass flow of material into the layer.
FeedSf Calc The solids mass fraction of the feed to the layer.
Temperature / T Calc The temperature of the layer.
TotalMass / Mt Calc The mass of material in the layer.
TotalVol / Vt Calc The volume of material in the layer.
Density / Rho Calc The density of the material in the layer.
SolidFrac / Sf Calc The solids mass fraction of the material in the layer.
LiquidFrac / Lf Calc The liquid mass fraction of the material in the layer.
Outlet Streams
(the following parameters are shown in a table with columns for the Underflow (UF) and Overflow (OF) streams)
MassFlow / Qm Calc The mass flow of material in the stream.
VolFlow / Qv Calc The volume flow of material in the stream.
SolidFrac / Sf Calc The solids mass fraction of the stream.
Density / Rho Calc The density of the stream.
SolidConc Calc The solids concentration (at product temperature) of the stream.
SolidConc25 Calc The solids concentration at 25C of the stream.
Internal
SolFracToUF Calc The fraction of solids in the feed which is sent to underflow stream.
LiqFracToUF Calc The fraction of liquids in the feed which is sent to underflow stream.
CalcBedMassReqd Calc Only visible when VolumeSpecMethod = Total Mass or Total Volume. The calculated required mass of material in the Bed layer.

PresetBed tab page

The PresetBed page contains a Copy to Clipboard button which copies the current temperature, pressure and composition of the Preset Bed Image to the clipboard for pasting into external programs such as Excel.

The associated DSp page is used to set the required composition of the Bed when it is Preset. This is identical in functionality to the DSp page used in Feeders.

PresetCL tab page

The PresetCL page contains a Copy to Clipboard button which copies the current temperature, pressure and composition of the Preset Clarified Liquid (CL) Image to the clipboard for pasting into external programs such as Excel.

The associated DSp page is used to set the required composition of the tank when it is Preset. This is identical in functionality to the DSp page used in Feeders.

Adding this Model to a Project

Insert into Configuration file

Sort either by DLL or Group.

  DLL:
MatHand2.dll
Units/Links Separation: Thickener - Thickener(2)
or Group:
Mass Separation
Units/Links Separation: Thickener - Thickener(2)

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


Insert into Project

  Insert Unit Separation Thickener - Thickener(2)

See Insert Unit for general information on inserting units.

Hints and Comments

  1. There may be mass entering or leaving the Thickener 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. If the reaction block is enabled in the model, there may be small errors resulting in the calculation of Overflow/underflow solids due to the feed composition change.