Drum Filter

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Contents 1 General Description 1.1 Diagram 2 Inputs and Outputs 3 Model Theory 4 Flowchart 5 Data Sections 5.1 Requirements 5.2 Results 6 Adding this Model to a Project

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

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	Input / Output	No. of Connections		Description
		Min	Max.
Feed	In	1	20	The slurry feed to the Drum Filter
Wash Water	In	0	1	Wash water to the Drum Filter
Filtrate	Out	1	1	Filtrate outlet from the unit
Cake	Out	1	1	Solids outlet from the unit

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

Data Sections

The default access window consists of three sections:

1. The first tab has the same name as the model tag and contains general information relating to the unit.
2. The Info section, contains general settings for the unit and allows the user to include documentation about the unit and create Hyperlinks to external documents. This is fully described in Common Data Sections.
3. Links tab, only visible in SysCAD 9.2, contains a summary table for all the input and output streams.
4. Audit tab - contains summary information required for Mass and Energy balance. See Model Examples for enthalpy calculation Examples.

Class: DrumFilt-0 - The first tab page in the access window will have this name.

Tag / Symbol	Input / Calc	Description/Calculated Variables / Options
Common First Data Section
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.
Method	List	FiltrateSolidsFraction - User specifies the required filtrate % solids.
		FiltrateConcentration - User specifies the filtrate solids concentration.
RqdFiltSolids	Input	The required filtrate % solids - visible with FiltrateSolidsFraction method.
RqdFiltSolConc25	Input	The required filtrate solids concentration, measured at 25°C - visible with FiltrateConcentration method.
FiltSolidsUsed	Calc	The actual filtrate % solids.
RqdCakeMoist	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.
OperatingP... (available in SysCAD 9.2 or later)
Method	List	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.
		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.
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).
TrackStatus	Tick Box	Allows warning messages be displayed if requirements are not met.
Results
CakeSolids	Calc	The calculated percentage of solids in the filter cake.
FiltSolids	Calc	The calculated percentage of solids in the filtrate.
CakeSolConc25	Calc	The cake solids concentration measured at 25°C.
FiltSolConc25	Calc	The filtrate solids concentration measured at 25°C.
WashComp	Input	Choose Compound/species from the drop down list for the calculation of Wash efficiency on a concentration base. (OPTIONAL)
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:	Separ1.dll	→	Units/Links	→	Separation: Drum Filter
OR	Group:	Mass Separation	→	Units/Links	→	Separation : Drum Filter

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

Insert into Project

Insert Unit

→

Separation

→

Drum Filter

See Insert Unit for general information on inserting units.