Mode summary for the GG1 example simulation

Purpose

Size the control valves for the required pressure drop.

Set the compressor speed and calculate the compressor outlet temperature.

Initially set control valve Cv and piping size for anti-surge line.

Validate control valve size and piping size for anti-surge line.

Validate anti-surge control strategy for upsets like motor trip and blocked outlet scenarios.

Source

Specify the flow, temperature, and pressure.

Specify the pressure and temperature.

Calculate the flow.

Compressor

Specify the outlet pressure.

Calculate the efficiency from performance curves.

Calculate the flow from performance curves.

Calculate the efficiency based on the calculated flow.

Drum

Calculate the vapor and liquid outlet flow.

Calculate the pressure from the differential mass and energy balances.

Heat Exchangers

Specify the outlet temperature.

Specify the outlet temperature.

Valves

For the inlet and outlet control valves, specify DP to size Cv.

For XV1, XV2: Specify the CheckValve parameter as Check to avoid reverse flow to the upstream unit.

For the anti-surge valves, set the initial Cv value. You should validate this Cv value based on the dynamic surge control scenarios.

For the inlet and outlet control valves, set Cv to calculate the flow.

For XV1, XV2: Specify the CheckValve parameter as Check to avoid reverse flow to the upstream unit.

For the anti-surge valves, adjust the Cv values based on the required dynamic surge control response.

Pipes

For pipes in anti-surge lines, specify D_margin = 0 (instead of DP).

Set initial pipe size. You should validate this pipe size based on maximum velocities during dynamic surge control scenarios (observe Trend “Pipe Velocities”).

Calculate pressure drop.

Headers

Set the the outlet flow ratio (OutRatio) for the anti-surge recycle streams to zero.

Calculate the outlet flow ratio (OutRatio).

Anti-surge Control

Calculate the output to the anti-surge control valve (OP). AVEVA Process Simulation initially calculates this value as zero based on the zero flow through the anti-surge valve.

Specify the maximum capacity (MaxCap) over the design for the stonewall condition.

Specify the margin over the surge flow at which to trigger a control response (MarginSCL).

Specify the margin over the surge flow at which to trigger a larger recycle trip response (MarginRTL).

Specify the maximum compressor design flow expected for the stonewall condition.

Switch

To study the response with the cold recycle anti-surge valve, set the Switch parameter to “One” in model SW1. This setting ensures that the AS1.Output signal is sent to FV1.Control.

To study the response with hot recycle anti-surge valve, set the Switch parameter to “Two” in model SW1. This setting ensures that the AS1.Output signal is sent to FV2.Control.

Same in all modes.