Configuration principles and introductions to the principles of two-shot control and three-shot control

Personal opinion: 1. Based on the configuration for controlling the drum level in the boilers at our plant, we use the feedwater flow rate multiplied by a coefficient, and then subtract the steam flow rate after temperature and pressure compensation; the goal is to keep the value of this subtraction at 0. I believe this is due to water-steam equilibrium. 2. In the methanol synthesis process, there is a small drum that generates medium-pressure steam, and there too, level control is implemented. Configuration is carried out using the standard PID module with feedforward control in the DCS system, and the feedforward variable is also the result of a water-vapor balance subtraction. (The coefficients in the water vapor equilibrium calculation formula here are different from those in the boiler system.) 3. For the control of the liquid level in the vaporizer’s drum, it involves a simple PID control mechanism; however, the compensation calculation formula is complex, and it’s not clear how this formula is derived.

It’s not that simple, right! ? Big brother!