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INTERSTAGE_CONTROL_PRESSURE

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Description​

This keyword can only be utilised for a VARIABLE_SPEED_COMPRESSOR_TRAIN_MULTIPLE_STREAMS_AND_PRESSURES type, and it is used in two separate sections:

  • MODELS - to define the upstream and downstream pressure control methods
  • ENERGY_USAGE_MODEL - to define the interstage pressure

Use in MODELS​

note

This keyword cannot be specified for the first stage, and it may only be used once in a given compression train.

Under the INTERSTAGE_CONTROL_PRESSURE keyword, the UPSTREAM_PRESSURE_CONTROL and DOWNSTREAM_PRESSURE_CONTROL keywords can be specified.

Format​

MODELS:
  - NAME: <compressor model name>
    TYPE: VARIABLE_SPEED_COMPRESSOR_TRAIN_MULTIPLE_STREAMS_AND_PRESSURES
    ...
    STAGES:
      - INLET_TEMPERATURE: <inlet temperature in Celsius for stage>
        COMPRESSOR_CHART: <reference to a compressor chart model defined in MODELS>
        STREAM: <reference stream from STREAMS. Needs to be an INGOING type stream.>
        ...
      - INLET_TEMPERATURE: <inlet temperature in Celsius for stage>
        COMPRESSOR_CHART: <reference to a compressor chart model defined in MODELS>
        INTERSTAGE_CONTROL_PRESSURE:
            UPSTREAM_PRESSURE_CONTROL: <DOWNSTREAM_CHOKE / UPSTREAM_CHOKE / INDIVIDUAL_ASV_RATE> 
            DOWNSTREAM_PRESSURE_CONTROL: <DOWNSTREAM_CHOKE / UPSTREAM_CHOKE / INDIVIDUAL_ASV_RATE>
        ...

The reason why upstream and downstream pressure control methods need to be specified is that the compression train is essentially split in two - before and after the interstage pressure. Thus, a control method for each "side" of the model needs to be defined. See Variable speed compressor train model with multiple streams and pressures for more details.

Use in ENERGY_USAGE_MODEL​

Within the ENERGY_USAGE_MODEL section (only when TYPE is set to VARIABLE_SPEED_COMPRESSOR_TRAIN_MULTIPLE_STREAMS_AND_PRESSURES) the actual value for the interstage pressure is set in bar. This can either be a single value or an EXPRESSION.

Format​

      - NAME: <reference name>
        ...
        ENERGY_USAGE_MODEL:
            TYPE: VARIABLE_SPEED_COMPRESSOR_TRAIN_MULTIPLE_STREAMS_AND_PRESSURES
            ...
            INTERSTAGE_CONTROL_PRESSURE: <interstage control pressure value/expression>
            ...

Example​

      - NAME: export_compressor
        ...
        ENERGY_USAGE_MODEL:
            TYPE: VARIABLE_SPEED_COMPRESSOR_TRAIN_MULTIPLE_STREAMS_AND_PRESSURES
            ...
            SUCTION_PRESSURE: 10 # bar
            INTERSTAGE_CONTROL_PRESSURE: 40 #bar
            DISCHARGE_PRESSURE: 120 #bar