List of top Instrumentation and Process Control Questions on P&ID equipment symbols asked in GATE CH

In the P&ID shown below, which one of the following is the function of PAH in the process?

Consider the control structure for the overhead section of a distillation column shown in the figure. The composition controller (CC) controls the heavy key impurity in the distillate by adjusting the setpoint of the reflux flow controller in a cascade arrangement. The sign of the controller gain for the pressure controller (PC) and that for the composition controller (CC) are, respectively,