The term “plant-wide control” is used here to describe the use of advanced software that sits above (or on top of) the individual PID controllers running a number of process units in a plant. Depending on the technology employed, this advanced process control software can perform a variety of predictive, scheduling, supervisory and/or optimizing computations. […]
Processes with streams comprised of gases, liquids, powders, slurries and melts tend to exhibit changing (or nonlinear) process behavior as operating level changes. We discussed the nonlinear nature of the gravity drained tanks and heat exchanger processes in an earlier post. As we observed in that article and explore below, processes that are nonlinear with […]
There are two sample times, T, used in process controller design and tuning. One is the control loop sample time (step 4 of the design and tuning recipe) that specifies how often the controller samples the measured process variable (PV) and computes and transmits a new controller output (CO) signal.