By Bob Rice1 and Doug Cooper Integrating (or non-self regulating) processes display counter-intuitive behaviors that make them surprisingly challenging to control. In particular, they do not naturally settle out to a steady operating level if left uncontrolled. To address this distinctive dynamic character, we modify the controller design and tuning recipe to include a FOPDT […]

By Bob Rice1 and Doug Cooper The case studies on this site largely focus on the control of self regulating processes. The principal characteristic that makes a process self regulating is that it naturally seeks a steady state operating level if the controller output and disturbance variables are held constant for a sufficient period of […]

A fairly common stumbling block for those new to controller tuning relates to step 2 of the controller design and tuning recipe. Step 2 says to “collect controller output (CO) to process variable (PV) dynamic process data around the design level of operation.” But suppose disturbance rejection is our primary control objective (example studyhere). Shouldn’t […]

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 […]