Disk Centrifuge

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Navigation: Main Page -> Models -> Mass Separation Models


General Description

The Disk Centrifuge mixes perfectly all the incoming feed streams and then, based on the user configuration, calculates the amount, temperature and composition of material reporting to the products.

Diagram

DiskCentrifuge.png

The diagram shows the default drawing of the Disk Centrifuge, with all of the streams that are required for operation of the unit. The physical location of the streams connecting to the unit 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 1 Required In 1 20 The slurry feed to the Disk Centrifuge
Centrate Required Out 1 1 Centrate outlet from the unit
Cake Required Out 1 1 Solids outlet from the unit
Vent Optional Out 0 1 Vent Stream (Vapour only).

Behaviour when Model is OFF

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

  • The field MassFracToCake becomes visible and the user may set the fraction of the feed stream that reports to the 'Cake' outlet. The default is 100%.
  • All streams connected to the unit will flow out of the 'Cake' outlet, unless the user has changed the above field from 100%. In which case the user defined fraction of the Feed will report to the Centrate stream;

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

Model Theory

The Disk Centrifuge is based on user defined variables that define the solids / liquids split. There are four methods available in this model:

  1. SolidsRec/SolidAnalysis: User specified feed solids recovery to the centrifuge cake and cake percent solids.
  2. SolidsRec/MoistAnalysis: User specified feed solids recovery to the centrifuge cake and cake moisture contents.
  3. CentConc/SolidAnalysis: User specified centrate solids concentration @ 25 and cake percent solids.
  4. CentConc/MoistAnalysis: User specified centrate solids concentration @ 25 and cake moisture contents.

Flowchart

The following shows the sequence of events if sub model options are switched on. See next heading for more information.

DiskCentrifugeFlowchart.png

Data Sections

The default sections and variable names are described in detail in the following tables. The default Disk Centrifuge access window consists of three sections. This number may increase based on user configuration.

  1. DiskCentrifuge tab - This first tab contains general information relating to the unit, as well as check boxes that allow the user to enable Reactions and/or a heat loss to the environment.
  2. PC - Optional tab that is visible if EB.Solubility.On and/or [email protected] is enabled in the Evaluation Block. (Available from SysCAD 9.3 Build 137.21979 and later.)
  3. RB - Optional tab, only visible if the Reactions are enabled in the Evaluation Block.
  4. EHX - Optional tab, only visible if the EnvironHX is enabled in the Evaluation Block.
  5. Evap - Optional tab that is visible if Evaporator is enabled in the Evaluation Block. (Available from SysCAD 9.3 Build 137.21979 and later.)
  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. (Available from SysCAD 9.3 Build 137.21979 and later.)
  7. 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.
  8. Info tab - Contains general settings for the unit and allows the user to include documentation about the unit and create Hyperlinks to external documents.
  9. Links tab, contains a summary table for all the input and output streams.
  10. Audit tab - Contains summary information required for Mass and Energy balance. See Model Examples for enthalpy calculation Examples.

Disk Centrifuge Page

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

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:
  • For pipes, SysCAD will use the text in the 'ConnectDesc' field - this displays the Source and Destination tags of the pipe;
  • For Feeders/Cross Page Connectors, SysCAD will display the state of the unit, i.e. if it is a Feeder or a Sink, etc.;
  • For other units SysCAD will display the unit class ID.

Requirements

On Tick box Switch the model on or off. If the unit is 'Off' then by default all Feed reports to the Cake outlet. If user specifies a value (less than 100%) in the MassFracToCake field, then some feed may report to the Centrate stream.
MassFracToCake_WhenOff / MassFracToCake Input This field becomes visible when the unit is switched off. The user may set the fraction of the feed stream that reports to the 'Cake' outlet. The default is 100%.
Method SolidsRec/SolidAnalysis User defines the required solids recovery and cake percent solids.
SolidsRec/MoistAnalysis User defines the required solids recovery and cake percent moisture.
CentConc/SolidAnalysis User defines the required centrate concentration at 25°C and cake percent solids.
CentConc/MoistAnalysis User defines the required centrate concentration at 25°C and cake percent moisture.
The visibility of the variables below will depend on method selection above.
SolidsToCake Input Required Solids Recovery - The fraction of the feed solids reporting to the cake.
CakeSolidFracReqd Input The required cake percent solids.
CakeMoistReqd Input Required Cake Moisture.
CentrateSolidConc25Reqd Input The required concentration of solids in the centrate measured at 25°C.
 
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 (Flow Evaluation Block)

The Evaluation Block section is only available from SysCAD 9.3 Build 137.21979 onwards.

Solubility.On Tickbox Only available in Build 137 or later. 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 available in Build 137 or later. Only visible if Phase Change at Temperature has been defined for at least one species in the project. 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 sequence followed will be MU1, MU2, etc., RB, EHX, Evap, DB1, DB2, etc.
Makeups Input Only available in Build 137 or later. The number of makeup blocks required. Extra dropdown options Makeup1, Makeup2, etc will be added to allow these to be switched on.
MakeupX List Only available in Build 137 or later. 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 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 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 Only available in Build 137 or later. This can be used to switch on the Evaporation Block (Evap). 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.
Discards 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

TrackStatus Tick Box Allows warning messages be displayed if requirements are not met.
 

Results

Cake.SolidFrac / Cake.Sf Calc Cake percent solids.
Cake.SolidsConc Calc The cake solids concentration measured at 25°C.
Centrate.SolidFrac / Centrate.Sf Calc Centrate percent solids.
Centrate.SolidConc25 Calc The centrate solids concentration measured at 25°C.

Adding this Model to a Project

Insert into Configuration file

Sort either by DLL or Group.

 

DLL: (prior to Build 137.21979)

Separ1.dll

Units/Links

Separation: Disk Centrifuge

 

DLL: (Latest build)

Separation.dll

Units/Links

Separation: Disk Centrifuge

OR

Group:

Mass Separation

Units/Links

Separation: Disk Centrifuge

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

Insert into Project

 

Insert Unit

Separation

Disk Centrifuge

See Insert Unit for general information on inserting units.