Drum Filter

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


General Description

The Drum Filter is used to separate the solids from the liquids in the feed stream. There is a facility to wash the solids using wash water. The wash water will displace some of the feed liquid from the cake. The washings will be combined with the filtrate, as there is no allowance for separate washings outlet.

Diagram

DrumFilter.png

The diagram shows the default drawing of the Drum Filter, with all of the streams that are available for operation of the unit. The user does not have to connect a stream to the 'Wash Water' connection, as the Drum Filter will operate without wash water.

The physical location of the streams connecting to the Drum Filter 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 Drum Filter
Wash Water Optional In 0 10 Wash water to the Drum Filter
Filtrate Required Out 1 1 Filtrate 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:

  • All streams connected to the 'Feed' inlet will flow out of the 'Cake' outlet;
  • All streams connected to the 'Wash Water' inlet will flow straight out of the 'Filtrate' outlet;
  • No mixing will occur.

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

Model Theory

The Drum Filter is based on user defined variables that define the solids / liquids split, as well as the efficiency of the washing action.

The user defines the amount of liquid in the filter cake and the amount of solids reporting to the filtrate. In addition, the user specifies the fractional bypass, which defines the fraction of the wash water that channels through the cake and reports directly to the filtrate. Obviously, if there is no wash water connected to the drum filter, then the user can ignore the washing variable.

For example, if the user defines a 0% fractional bypass, then all of the wash water is used to displace the filter feed liquid from the cake. If the fractional bypass is set at 20%, then 20% of the wash water will report directly to the filtrate stream without displacing any feed liquid from the solids.

NOTE: The model assumes no solids are present in the wash water stream. Any solids present will not be used in the Liq/Sol separation calculations. Furthermore, any solids present in the wash stream will be reported to the cake.

Example

The Drum Filter shown in the Diagram in 2 is configured to give 10% moisture in the cake, 1% of the feed solids in the filtrate, and 10% fractional bypass. The table below shows the material flows, in t/h, around the Filter Press with this configuration.

Material Feed Wash Water Cake Filtrate
H2O(l) 8.0 0.9 0.97 7.93
NaCl(aq) 2.0 0.0 0.04 1.96
KCl(aq) 0.0 0.1 0.09 0.01
Total Liquid 10.0 1.0 1.1 9.9
Solids 10.0   9.9 0.1
Total Mass 20.0 1.0 11.0 10.0

This example shows that 10% of the wash water reported straight to the filtrate. The remaining 90% of the wash water, 0.9t/h, displaced an equal amount of feed liquid from the cake.

Flowchart

DrumFilterFlowchart.png

Data Sections

The default access window consists of three sections:

  1. DrumFilter tab - Contains general information relating to the unit.
  2. PC - Optional tab that is visible if EB.Solubility.On is enabled on the first tab. (Available from SysCAD 9.3 Build137.21979 and later.)
  3. 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. (Available from SysCAD 9.3 Build137.21979 and later.)
  4. RB - Optional tab, only visible if the Reactions are enabled. (Available from SysCAD 9.3 Build137.21979 and later.)
  5. EHX - Optional tab, only visible if the EnvironHX is enabled. (Available from SysCAD 9.3 Build137.21979 and later.)
  6. Evap - Optional tab that is visible if Evaporator is enabled. (Available from SysCAD 9.3 Build137.21979 and later.)
  7. Info tab - Contains general settings for the unit and allows the user to include documentation about the unit and create Hyperlinks to external documents.
  8. Links tab - contains a summary table for all the input and output streams.
  9. Audit tab - Contains summary information required for Mass and Energy balance. See Model Examples for enthalpy calculation Examples.

Drum Filter Page

Unit Type: DrumFilter - 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

Requirements

On Tickbox Switches on the filter operation. If this box is not selected, all the feed will report to the cake, all the wash will report to filtrate.
Filtrate_Method / Method FiltrateSolidsFraction User specifies the required filtrate % solids.
FiltrateConcentration User specifies the filtrate solids concentration.
FiltrateSolidFracReqd Input The required filtrate % solids - visible with FiltrateSolidsFraction method.
FiltrateSolidConc25Reqd Input The required filtrate solids concentration, measured at 25°C - visible with FiltrateConcentration method.
CakeMoistReqd Input The required percentage liquids in the filter cake.
WashBypass Input The required percentage of wash water that should bypass the filter cake, thus reporting directly to the filtrate stream. Note any solids in the wash water will be reported to the cake stream.
FiltrateSolidFracUsed Calc The actual filtrate % solids.
OperatingP...
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)

The Evaluation Block section is only available from SysCAD 9.3 Build137.21979 onwards.

Solubility.On Tickbox Allows the user to switch on any predefined solubility curve to adjust the composition of material 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, 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.
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.

Options

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

Results

Cake.SolidFrac / Cake.Sf Calc The calculated percentage of solids in the filter cake.
Cake.SolidConc25 Calc The cake solids concentration measured at 25°C.
Filtrate.SolidFrac / Filtrate.Sf Calc The calculated percentage of solids in the filtrate.
Filtrate.SolidConc25 Calc The filtrate solids concentration measured at 25°C.
WashComponent / WashComp Input Choose Compound/species from the drop down list for the calculation of Wash efficiency on a concentration base. (OPTIONAL)
CompWashEfficiency / CompWashEff Calc The calculated wash efficiency based on component concentration.

WashEff = (Conc Feed - Conc Cake) / (Conc Feed - Conc wash)

Adding this Model to a Project

Insert into Configuration file

Sort either by DLL or Group.

 

DLL: (prior to Build137.21979)

Separ1.dll

Units/Links

Separation: Filter - Drum Filter

 

DLL: (Latest build)

Separ1.dll

Units/Links

Separation: Filter - Drum Filter

OR

Group:

Mass Separation

Units/Links

Separation : Filter - Drum Filter

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

Insert into Project

 

Insert Unit

Separation

Filter - Drum Filter

See Insert Unit for general information on inserting units.