The classifier 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.
The diagram shows the default drawing of the Classifier, 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
|Number of Connections||Description|
|Feed||1 Required||In||1||20||The slurry feed to the Classifier|
|Overflow||Required||Out||1||1||The classifier overflow.|
|Underflow||Required||Out||1||1||The classifier underflow.|
|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 MassFracToUF becomes visible and the user may set the fraction of the feed stream that reports to the 'Underflow' outlet. The default is 100%.
- All streams connected to the unit will flow out of the 'Underflow' 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 Overflow stream;
So basically, the unit will be 'bypassed' without the user having to change any connections.
The Classifier is based on user defined variables that define the solids / liquids split. There are three methods available in this model:
- UFSolRec User specified feed solids recovery and underflow solids concentration.
- OFConc User specified underflow and overflow solids concentrations.
- UFVolFlow User specified underflow solids concentration and volume flowrate.
The following shows the sequence of events if sub model options are switched on. See next heading for more information.
The default access window consists of several sections,
- Classifier tab - Contains general information relating to the unit.
- PC - Optional tab that is visible if EB.Solubility.On is enabled on the first tab.
- MU - Optional tab, or multiple tabs if more than 1 Makeup is selected. Only visible if one of more Makeup is enabled in the Evaluation Block.
- RB - Optional tab, only visible if the Reactions are enabled.
- EHX - Optional tab, only visible if the EnvironHX is enabled.
- Evap - Optional tab that is visible if Evaporator is enabled.
- Info tab - Contains general settings for the unit and allows the user to include documentation about the unit and create Hyperlinks to external documents.
- Links tab, contains a summary table for all the input and output streams.
- Audit tab - Contains summary information required for Mass and Energy balance. See Model Examples for enthalpy calculation Examples.
Unit Type: Classifier - The first tab page in the access window will have this name.
|Tag (Long/Short)||Input / Calc||Description/Calculated Variables / Options|
|Common Data on First Tab Page|
|On||Tick Box||This allows the user to enable or disable the unit. If the unit is disabled, no reactions will occur and the field MassFracToUF becomes visible.|
|MassFracToUF_WhenOff / MassFracToUF||Input||This field is only visible if the On tickbox is NOT ticked. This field allows the user to specify the fraction of the incoming streams that will flow to the classifier underflow when the unit is disabled.|
|Method||UFSolRec||User specifies the required feed solids recovery to the underflow and underflow solids concentration at 25°C.|
|OFConc||User specifies the required underflow and overflow solids concentration at 25°C.|
|UFVolFlow||User specifies the required underflow volume flowrate and solids concentration at 25°C.|
|The visibility of the variables below will depend on method selection above.|
|SolidsToUF||Input||The required percentage of the feed solids reporting to the underflow, this is the underflow solids recovery.|
|UFSolidConc25Reqd||Input||The required underflow solids concentration measured at 25°C.|
|OFSolidConc25Reqd||Input||The required overflow solids concentration measured at 25°C.|
|UFQv25Reqd||Input||The required underflow volumetric flowrate measure at 25°C.|
|Method||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 Species tab page of the Plant Model.|
|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.|
|RequiredP||outlet streams will be at the user specified pressure.|
|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.|
|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||Display||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)
|Solubility.On||Tickbox||Allows the user to switch on any predefined solubility curve to adjust the composition of material in the unit. This sub model has been added to this unit operation in SysCAD 9.3.|
|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, VLE.
|Makeups||Input||The number of makeup blocks required. Extra dropdown options Makeup1, Makeup2, etc will be added to allow these to be switched on. This sub model has been added to this unit operation in SysCAD 9.3.|
|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|| 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|| 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. This sub model has been added to this unit operation in SysCAD 9.3.
|Calc||TickBox||Allows user to enter a volume for the classifier, then a residence time is estimated based on the flowrate of the feed.|
|The following fields will only be visible if the Calc tick box is selected.|
|Volume||Input||The operating volume of the unit. This will be used to calculate the apparent residence time in the unit.|
|MassFlow / Qm||Calc||The mass flow of the material.|
|Temperature / T||Calc||The temperature of the material.|
|Slurry||Calc||The residence time of the slurry in the unit.|
|Total||Calc||The residence time for the slurry and the vapours in the unit.|
|ShowQFeed||Tick Box||QFeed and associated tab pages (eg Qm) 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.|
|TrackStatus||Tick Box||Allows warning messages be displayed if requirements are not met.|
Slurry Separation Results
|UFSolidsRecovery||Display||The fraction of feed solids sent to the underflow.|
|UFLiquidRecovery||Display||The fraction of feed liquid sent to the underflow.|
|VapourMassFlow / VQm||Calc||Only available in SysCAD 9.3 Build 137 or later. The total flow of vapour to the Underflow and Overflow streams. (This does NOT include the vapour to the Vent)|
|The following table displays the flows and compositions of the Underflow and Overflow streams. Note: These are for slurry only, vapours are excluded.|
|MassFlow / Qm||Display||The total mass flow in each of the Underflow and Overflow streams.|
|VolFlow / Qv||Display||The total volume flow in each of the Underflow and Overflow streams.|
|SolidMassFlow / SQm||Display||The solids mass flow in each of the Underflow and Overflow streams.|
|LiquidMassFlow / LQm||Display||The liquid mass flow in each of the Underflow and Overflow streams.|
|SolidFrac / Sf||Display||The solid fraction in each of the Underflow and Overflow streams.|
|Density / Rho||Display||The total density of each of the Underflow and Overflow streams.|
|SolidConc||Display||The solid concentration (mass of solids/density of slurry) in each of the Underflow and Overflow streams.|
|SolidConc25||Display||The solid concentration at 25°C (mass of solids/density of slurry at 25°C) in each of the Underflow and Overflow streams.|
|GridDisplay||Tick Box||This is a global selection, if this is selected, then where available, variables will display in a table format, if not selected, they will be listed in separate groups as a single list.|
Adding this Model to a Project
Insert into Configuration file
Sort either by DLL or Group.
|DLL:||Separation.dll||→||Units/Links||→||Separation: Thickener - Classifier|
|or||Group:||Mass Separation||→||Units/Links||→||Separation: Thickener - Classifier|
See Project Configuration for more information on adding models to the configuration file.
Insert into Project
|Insert Unit||→||Separation||→||Thickener - Classifier|
See Insert Unit for general information on inserting units.