The liquid level in a reboiler of a steam-heated distillation column is to be controlled by adjusting the control valve on the steam line, as shown in figure. The process transfer function has been empirically determined to be where H denotes the liquid level (in inches) and P is the steam pressure (in psi).

The level transmitter and control valves have negligible dynamics and steady-state gains of Km = 0.5 psi/in and Kv = 2.5 (dimensionless), respectively. Design a PI level controller using the Direct Synthesis method. Justify your choice of τc.

Transcribed Image Text:

--1,6(1 - 0.5s) Не) s(3s + 1) P(s)