Fixed Bed Reactor - Cascade Control
This is an example of adiabatic cascade control for a catalytic fixed-bed reactor to provide a desired ion concentration of a gas leaving the reactor. The gas is flowing at constant volume and is preheated before entering the reactor.
Sequence Of Operation: This controls a gas ion concentration leaving a fixed bed reactor by preheating the gas before it enters the reactor. The primary controller, sensing concentration, functions to adjust the temperature setpoint for the secondary controller. The secondary temperature controller modulates the heating medium's flow control actuator to maintain the desired temperature.

System Chart: Select the button to view the fixed bed cascade control system strip chart that records each minute: Concentration sensor, Setpoint request, Temperature sensor, and Flow Actutor position values during the previous 100 minutes.

Concentration Chart: The measured concentration strip chart is shown for each minute recording the ion concentration of the gas leaving the reactor, and its setpoint, during the previous 100 minutes.

Analog Gauges: Gauges are provided on the central monitoring panel that display: concentration sensor value, primary controller setpoint adjust value, temperature sensor value, and the secondary controller output position request value for the heating medium flow actuator.

Primary/Secondary Controller Status: A 5-state status pilot light is included for the controller, shown at the controller in the system flow diagram.

Primary/Secondary PID Controllers: The central monitoring panel can tune each PID loop. The Setpoint(SPr), Proportional(P), Intergral(I), Derivative(D), and Controller Output(CO) values can be adjusted.

Flow Actuator Status: A 5-state status pilot light monitors the Flow Actuator status: maximum open position (ON), minimum open position (NORMAL OFF), or modulating (INTERMITTENT), and disabled/repairing (DEFECTIVE). If the Flow Actuator local circuit detects a fault, the status will show ALARM.
Heat Exchanger Fixed Bed Reactor Heating Medium Gas Setpoint Adjust Primary Secondary Temperature Concentration FlowFlow ActuatorSetpoint AdjustConcentrationTemperatureCascade ControlFixed Bed ReactorMinutesConcentrationControl Output
Tune Controller:
SPr: P: I: D: CO:
C % 0 100 0
Tune Controller:
SPr: P: I: D: CO:
SPrA%01000TemperaturedegF8028080 CO % 0 100 0

SVG Source: