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Split Range Pressure Control – Interactive Simulator

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Split Range Pressure Control: Surge Drum

One pressure controller drives two valves. When pressure is low the controller opens the gas IN valve to refill the drum. When pressure is high it opens the FLARE valve to vent gas. In the middle both valves stay shut. Create a disturbance, or switch to Manual and drag the controller output to see how the output is split between the two valves.

GAS SUPPLY HEADER TO FLARE SURGE DRUM 5.0 barg PSV PT PIC low output high output GAS IN valve FLARE valve signal to gas IN valvesignal to FLARE valve

What is happening now

Readings

Drum pressure (PV)
Setpoint (SP)
Error (PV – SP)
Controller output (OUT)
Gas IN valve opening
FLARE valve opening
Gas flowing in
Gas going to flare
Process gas imbalance

Why use split range?

One controller, two valves. A single pressure loop can both add gas and remove gas, so the pressure is held from either side.
Never fighting each other. The two valves open in different halves of the output range, so gas is never fed in and flared at the same time.
Dead band saves gas. A small gap in the middle keeps both valves shut when pressure is near target, so small ripples do not waste gas to the flare.

1Mode and setpoint

barg

2Create a disturbance

Positive imbalance = more gas arrives than leaves (pressure wants to rise). Negative = consumers take more gas (pressure wants to fall).

3Set the split range

4Watch

Split range graph (click it to set OUT)

blue = gas IN valve (open at low output), orange = FLARE valve (open at high output). Grey band = dead band. Click or drag on the graph to take manual control and move the output.

Pressure trend

blue = pressure, orange dashed = setpoint. Dashed lines = alarms, red = PSV at 10 barg and low-low at 1 barg. Last 240 s.

Controller output and valves

black = controller output, blue = gas IN valve, orange = FLARE valve (%).

Split Range Pressure Control – Interactive Simulator

Understand the working principle of split range pressure control through an interactive simulation of a gas surge drum. A single Pressure Indicating Controller (PIC) regulates drum pressure by controlling two valves: a gas inlet valve and a flare valve. When drum pressure falls below the setpoint, the gas inlet valve opens to increase pressure. When pressure rises above the setpoint, the flare valve opens to release excess gas. Within the configured dead band, both valves remain closed.

Experiment with Auto and Manual modes, adjust the pressure setpoint, split point, and dead band, and introduce gas supply disturbances to observe how the system responds. Real-time visual animations, controller output calculations, valve opening indicators, pressure trends, and process flow readings help you understand the relationship between controller output and valve operation.

This simulator is designed for instrumentation engineers, DCS/PLC learners, process control students, and maintenance technicians who want to build practical knowledge of split range control, pressure regulation, and control valve behavior.

Note: This is an educational simulation with simplified process dynamics, not a substitute for actual plant control logic or safety system design.

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