View source for Drum Filter

[[Category:Models]]
{{Navigation|[[Models]]|[[Models#Mass Separation Models|Mass Separation Models]]}}
{{Filter header table|currentpage=2}}
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{{TOC}}
== 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 ===

:[[Image: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 ==

:{| border="1" cellpadding="5" cellspacing="0"  
|- 
| valign="top" rowspan="2" | '''Label''' || valign="top" rowspan="2" | '''Required<br>Optional''' || valign="top" rowspan="2" | '''Input<br>Output ''' ||  colspan="2"   | '''Number of Connections''' || valign="top" rowspan="2" | '''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.

:{| border="1" cellpadding="5" cellspacing="0" 
|-
|Width=100|'''Material''' ||Width=100|'''Feed'''||Width=100|'''Wash Water'''||Width=100|'''Cake'''||Width=100|'''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      ||&nbsp;          ||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.

=== Internal Recycle of Filtrate ===

In Build 139 or later, a new option is included to calculate the required internal recycle of filtrate (which would include wash water) to dilute feed slurry to a user-defined solids concentration. This emulates the use of a feed tank or drum filter bath with filtrate recycle:

:[[Image:DrumFilterInternalRecycle.png]]

== Flowchart ==

:[[Image:DrumFilterFlowchart.png]]

'''Note:''' The Filtrate Recycle option is only available in Build 139 or later.

== Data Sections ==

The default access window consists of three sections:
# '''[[#Drum Filter Page|DrumFilter]]''' tab - Contains general information relating to the unit.
# '''[[Phase Change (PC)|PC]]''' - Optional tab that is visible if EB.Solubility.On is enabled on the first tab.
# '''[[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.
# '''[[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.
# '''[[Material Flow Section|QFilterFeed]]''' - {{Available139}} Optional tab, only visible if ''ShowTotalFeed'' is selected. This page shows the properties of the combined feed stream, including the internal recycle stream. 
#* This is before any [[Evaluation Blocks|Evaluation Block]] sub-models are evaluated.  
#{{ShowQout|Cake}}
#{{ShowQout|Filtrate}}
# '''[[Common Data Sections#Common Data on Info Tab Page|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 Table|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.

===Drum Filter Page===
'''Unit Type: DrumFilter''' - The first tab page in the access window will have this name.

{|   border="1" cellpadding="5" cellspacing="0" 
||'''Tag (Long/Short)'''||'''Input / Calc'''||'''Description/Calculated Variables / Options'''
|-
{{Common Data on First Tab Page}}
|-
|  colspan="3" font style="background: #ebebeb"    |

=== 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.
|-
|  rowspan="2"  |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|| font style="background: #ebebeb"   |Calc||The actual filtrate % solids.
|-
|  colspan="3" font style="background: #ebebeb"    |

=== Filtrate Recycle ===
|-
| RecycleFiltrate ||Tick Box|| {{Available139}} Enables internal filtrate recycle. Additional fields will be displayed on this tab.
|-
|  colspan="3" font style="background: #ebebeb"    | ''The following 2 fields are only visible if the '''RecycleFiltrate''' option has been enabled. {{Available139}}''
|-
| FeedSolidsConcReqd || Input || Target feed solids concentration. The internal filtrate recycle will be varied to try to achieve this concentration.
|-
| MaxFiltrateRecycle || Input || The maximum internal filtrate recycle.
{{OperatingP}}
|-
|  colspan="3" font style="background: #ebebeb"    |

=== EB (Flow Evaluation Block) ===

{{EB Evaluation Data Section | Makeups = Yes | Reactions = Yes | HeatXChg = No | EnvironHX = Yes | Evaporation = Yes | VLE = No | Discard = No}}
|-
|  colspan="3" font style="background: #ebebeb"    |

=== Options ===
|-
|TrackStatus||Tick Box||Allows warning messages be displayed if requirements are not met.
{{ShowQout DataSection|Cake}}
{{ShowQout DataSection|Filtrate}}
|-
| ShowTotalFeed || Tick Box || {{Available139}} Only visible if the '''RecycleFiltrate''' option has been enabled. QFilterFeed and associated tab pages (e.g. Sp) will become visible, showing the properties of the combined feed stream, including the internal recycle stream. See [[Material Flow Section]]. This will be prior to any sub-model (e.g. reactions) actions.
|-
|  colspan="3" font style="background: #ebebeb"    |

=== Results ===
|-
||Cake.SolidFrac / Cake.Sf|| font style="background: #ebebeb"   |Calc||The calculated percentage of solids in the filter cake.
|-
||Cake.SolidConc25||  font style="background: #ebebeb"  |Calc||The cake solids concentration measured at 25°C.
|-
||Filtrate.SolidFrac / Filtrate.Sf||  font style="background: #ebebeb"  |Calc||The calculated percentage of solids in the filtrate.
|-
||Filtrate.SolidConc25|| font style="background: #ebebeb"   |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||  font style="background: #ebebeb"  |Calc||The calculated wash efficiency based on component concentration. 

WashEff = (Conc Feed - Conc Cake) / (Conc Feed - Conc wash)
|-
|  colspan="3" font style="background: #ebebeb"    | ''The following 5 fields are only visible if the '''RecycleFiltrate''' option has been enabled. {{Available139}}''
|-
| SlurryDensToFilter ||  font style="background: #ebebeb"  |Calc||The slurry density of the feed to the filter, including the internal filtrate recycle.
|-
||Filtrate.RecycleFrac ||  font style="background: #ebebeb"  |Calc||The calculated fraction of filtrate that has been (internally) recycled.
|-
||Filtrate.RecycleQm ||  font style="background: #ebebeb"  |Calc||The calculated mass flow of filtrate that has been (internally) recycled.
|-
||Filtrate.RecycleQv ||  font style="background: #ebebeb"  |Calc||The calculated volume flow of filtrate that has been (internally) recycled.
|-
||FeedToFilter.SolidConc25 ||  font style="background: #ebebeb"  |Calc||The calculated solids concentration of total feed to the filter at 25°C, including the internally recycled filtrate.
|}

== Adding this Model to a Project ==

{{Adding Model to a Project | DllName=Separation | DllSubGroup=Separation | UnitOp=Filter - Drum Filter | Group=Mass Separation | }}