Thickener

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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 7 Hints and Comments

General Description

The thickener is used to separate the solids from the liquids in the feed stream.

• All of the feed streams to the Thickener will be completely mixed - there is NO functionality to set mixing efficiency.
• If the user wishes to use mixing efficiency, use either the Washer model or the Counter Current Washer model.
• The user may add reactions to this unit. All incoming streams will be mixed and then the reactions carried out on the resulting homogeneous mixture.
• The user defines the percentage solids in both the underflow and the overflow from the unit. The Thickener will calculate the liquid split to the under and flows to satisfy the user defined solids percentages.
• If there is insufficient solids in the feed to the Thickener to satisfy both the under and over flow requirements, the unit will try to satisfy the underflow solids / liquids requirements first.

Diagram

The diagram shows the default drawing of the Thickener, with all of the streams that have to be connected for the unit to operate.

The physical location of the streams connecting to the Thickener 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 Thickener
Overflow	Out	1	1	Thickener overflow
Underflow	Out	1	1	Thickener underflow
Vent	Out	0	1	Vent Stream (Vapour Only)

Model Theory

In ProBal mode this unit has no theory.

Flowchart

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

Data Sections

The default access window consists of several sections:

1. The first tab has the same name as the model tag, contains general information relating to the unit.
2. RB - Optional tab, only visible if the Reactions are enabled in the Evaluation Block.
3. EHX - Optional tab, only visible if the EnvironHX is enabled in the Evaluation Block.
4. 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.
5. QFeed - Optional tab, only visible if ShowQFeed is enabled. This page shows the properties of the mixed stream as the feed to the unit.
   • This is before any Evaluation Block models are evaluated.
6. Info tab - contains general settings for the unit and allows the user to include documentation about the unit and create Hyperlinks to external documents.
7. Links tab, only visible in SysCAD 9.2, contains a summary table for all the input and output streams.
8. Audit tab - contains summary information required for Mass and Energy balance. See Model Examples for enthalpy calculation Examples.

Class: Thicken-1 - 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	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. Only available in SysCAD 9.2 Build 132 and later.
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 thickener underflow when the unit is disabled.
RqdUFSolids	Input	The required percentage of solids in the underflow stream.
Method	OverFlowSolidsFraction	The user specifies the fraction of solids in the Over Flow stream.
	OverFlowSolidsConcentration	The user specifies the solids concentration in the Over Flow stream.
RqdOFSolids	Input	The required percentage of solids in the overflow stream. Visible only with the OverFlowSolidsFraction method.
RqdOFSolConc25	Input	The required overflow solids concentration measured at 25°C. Visible only with the OverFlowSolidsConcentration method.
IntOFSolidsUsed	Calc	The actual overflow solids used. This is for cases where the specified solids concentration cannot be achieved.
CalcOFSolids	Calc	Visible only with the OverFlowSolidsFraction method.
EB(Flow Evaluation Block)...
EvalSequence	Display	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. In Dynamic, the sub-models act on the feed before they are added to the contents of the tank.
Makeups	Input	The number of makeup blocks required. Extra dropdown options Makeup1, Makeup2, etc will be added to allow these to be switched on and off and prioritised in relation to the other sub-models.
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 then 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 Environmental Heat Exchanger (EHX). If this is 'On' then the associated page, EHX may become visible and may be configured. Note: The user does not have to configure an environmental heat exchange, even if this block is checked.
OperatingP... (available in SysCAD 9.2 or later)
Method	Atmospheric	The unit will operate at Atmospheric pressure. All of the outlet streams will be at this 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	The unit will operate at the lowest pressure of the feeds. All of the outlet streams will be at this pressure.
	HighestFeed	The unit will operate at the highest pressure of the feeds. All of the outlet streams will be at this pressure.
	RequiredP	The unit will operate at the user specified pressure. All of the outlet streams will be at this 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).
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. Eg, if the required and actual solid percentages are different.
Results
UFSolids	Calc	The actual percentage solids in the underflow stream.
OFSolids	Calc	The actual percentage solids in the overflow stream.
UFSolConc25	Calc	The actual underflow solids concentration measured at 25°C.
OFSolConc25	Calc	The actual overflow solids concentration measured at 25°C.
UFSolRec	Calc	The actual percentage underflow solids recovery.

Adding this Model to a Project

Insert into Configuration file

Sort either by DLL or Group.

	DLL:	Separ1.dll	→	Units/Links	→	Separation: Thickener
OR	Group:	Mass Separation	→	Units/Links	→	Separation : Thickener

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

Insert into Project

Insert Unit

→

Separation

→

Thickener

See Insert Unit for general information on inserting units.

Hints and Comments

1. There may be mass entering or leaving the Thickener via the Reaction Block source or sink, so if the outgoing mass is not the same as the incoming mass, this may be a place to check first.
2. If the reaction block is enabled in the model, there may be small errors resulting in the calculation of Overflow/underflow solids due to the feed composition change.