SplitFlow - General Operation

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Split Flows (Split) SplitFlow
General Operation
PGM Example
Set Species Splits

Latest SysCAD Version: 17 May 2022 - SysCAD 9.3 Build 139.30918


OPERATION - General

For Build139 and later
GM General139.png
  For earlier builds of SysCAD
GM General01.png
  1. This method allows the user to configure each outgoing stream using mixture of methods.
  2. This method is required if a tie exist within a flash train configuration. See topics Tie in Flash Train and Demand - Passing Demand through a Unit

Overall Options

Tag (Long/Short) Input / Calc Description/Calculated Variables / Options
QmMode Demand The outgoing streams accept the flows that the unit assigns to them. If the tie is to be included in a flash train configuration, this mode must be used. See topic Tie in Flash Train
PercSplit The stream flows are based on percentage split of the material in the unit.
PhaseSplit The stream flows are based on phase splits of the material in the unit.
MassFlow The stream flows are based on mass flow rates.
VolumeFlow The stream flows are based on volume flow rates.
MkMode Mixture The composition of the material flowing from the streams is the same as the composition of the material in the unit.
LSRatio This allows the user to set the Liquids : Solids ratio in the outgoing streams.
Composition This allows the user to set the phase composition of the outgoing streams.
AllTarget Tickbox If this is ticked (On) then the user will NOT receive warning messages if the user specified requirements are not met, ie. they are all targets.

Individual Stream Options

The user may configure all, or none of the streams. When solving, the model will first try and satisfy the requirements of the configured streams or the stream with the lowest order number. Material remaining in the unit will then be divided equally amongst the remaining un-configured streams.

Order Display The actual stream solving order of priority.
Priority Drop list Lets the user select the stream solving order.
QmMode (GM.QmMode) Using the overall QmMode specified above. The QmMode in use is displayed on RHS as a postscript.
Demand The user may not configure the stream in this mode. The stream will accept whatever flows from the unit that is required to balance the incoming flows. If the tie is to be included in a flash train configuration, this mode must be used. See topic Tie in Flash Train
PercSplit User can specify the mass split for this stream, based on the material available to this stream.
PhaseSplit User can specify the phase mass split for this stream, based on the material available to this stream.
Massflow User can specify the mass flow for this stream. This mode of operation will have priority over all other modes. Therefore, while in Auto priority mode, the unit will first try to satisfy this mass flow, and then send any remaining material to the other streams. User can still change the priority manually as required, see examples
VolumeFlow User can specify the volume flow for this stream. This mode of operation will have priority over all other modes. Therefore, while in Auto priority mode, the unit will first try to satisfy this volume flow, and then send any remaining material to the other streams. User can still change the priority manually as required, see examples
Split Input Visible when QmMode= PercSplit. The required mass percentage of the material available to this stream (based on order and priority, see examples).
SolSplit Input Visible when QmMode= PhaseSplit. The required mass percentage of solids available to this stream (based on order and priority, see examples).
LiqSplit Input Visible when QmMode= PhaseSplit. The required mass percentage of liquids available to this stream (based on order and priority, see examples).
VapSplit Input Visible when QmMode= PhaseSplit. The required mass percentage of vapours available to this stream (based on order and priority, see examples).
Qm Input Visible when QmMode= Massflow . The required mass flow from the stream.
QmErr Calc Visible when QmMode= Massflow. If the unit cannot satisfy the required mass flow, the difference between the actual and required flow will be reported here.
Qv Input Visible when QmMode= VolumeFlow . The required volume flow from the stream.
QvErr Calc Visible when QmMode= VolumeFlow. If the unit cannot satisfy the required volume flow, the difference between the actual and required flow will be reported here.
Note: MkMode is not applicable if the PhaseSplit QmMode is used.
MkMode (GM.MkMode) Using the overall MkMode specified above. The MkMode in use is displayed on RHS as a postscript.
Mixture The user need not specify any further variables. The unit will first satisfy any composition requirements of any other stream. The stream will then receive material with the composition of the material remaining in the unit.
LSRatio User can specify the Liquid : Solid ratio required in the stream. 100% means Liquid : Solid ratio is 1:1.
Composition This allows the user to specify the phase composition of the stream. See Notes below.
Species Fracs This method allows the user to specify the species composition of the stream. NOTE: user can over specify this stream using this method, when this happens, not all of the criteria will be met.
LSRatio Input Visible when MkMode= LSRatio. The Liquid : Solid ratio required in the stream. Note: Specifying this variable as a % (or PERCENT) may confuse the user. e.g. if the user specifies 10%, the liquid will not be 10% of the stream, but L:S = 1:10.
Solids Frac Input Visible when MkMode= Composition. The mass fraction of solids required in the stream
Liquid Frac Input Visible when MkMode= Composition. The mass fraction of liquids required in the stream
Vapour Frac Input Visible when MkMode= Composition. The mass fraction of vapour required in the stream
Splt... visible when MkMode= Species Fracs.
Solids Input Visible when MkMode= Species Fracs. The mass fraction of solids available (based on order and priority) reporting to the stream.
Liquid Input Visible when MkMode= Species Fracs. The mass fraction of liquids available (based on order and priority) reporting to the stream.
Vapour Input Visible when MkMode= Species Fracs. The mass fraction of vapour available (based on order and priority) reporting to the stream.
Splt...
Species x Input or * Visible when MkMode= Species Fracs. The fraction of each species reporting to the stream can be specified individually. All of the species left in the default mode (*) will follow the phase splits. The fractions of the species that are specified are calculated separately to the phase split numbers. (See the example below this table)

NOTE:

  1. If the unit is unable to supply the specified phase composition, the model will send no flow to that stream. e.g. if the user specifies a required composition of 50% Solids, 20% Liquid and 30% Vapour, and the unit contains no vapour, then the outgoing stream will have no flow.
  2. If the fractions specified do not sum to 100%, then the model will adjust the fractions such that the specified ratio is maintained.</nowiki>

Examples

Species Frac Example

Input Specification GM Configuration Results
General Model (GM) image001.gif
Stream Split Spec:
* 50% of the H2SO4 to Stream C
* 2% of feed solids to Stream C.
GM General02.png GM General03.png

Stream C Flowrate will be:

  • Total Flow - 0.78 t/h
  • Solids Flow - 0.03 t/h (2% of the incoming flows)
  • H2SO4 Flow - 0.75 t/h (50% of the incoming flows)
Note: The model ignores the 10% split requirement, but satisfies the phase and species split requirements. The rest of the material (14.22 t/h) will be sent to stream D.


Phase Split and Mass Flow Combined Method Example

Input Specification GM Configuration Results
GM General04.png
Stream Split Spec:
* All the gas to go to stream B.
* 2 t/h of the slurry to go to stream C.
GM General05.png GM General06.png
Note: The flow to each outlet will be evaluated sequentially, therefore it is important to place the phase split at Priority 1 to send all the vapour out first.
If the phase split was placed after the mass flow, then the mass flow will contain a small amount of vapour, then the remaining vapour will be sent by the phase split option.


Exporting Steam in a Flash Train

Input Specification GM Configuration Results
GM General10.png
* Flash train is broken when a tie is added.
* User must fix the Tie configuration to reform the flash train.
Stream Split Spec:
* 1 t/h flash vapour to be exported.
* flash vapour to HX based on HX configuration.
GM General11.png GM General12.png
NOTE: By default, Tie - Split Flow will start with the MassFrac Mode. User must change the operation to General and any streams that need to be part of a flash train must be placed in the Demand mode.