Common Plumbing and Control Errors in Plantwide Flowsheets
For almost a decade, the senior design course at Lehigh University has included development of plantwide control structures as a significant component of the course content. Students develop and optimize their steady-state process flowsheets during the fall semester. Then in the spring semester, they develop plantwide control schemes. “Pressure-driven” dynamic simulations are used because they correspond to reality and strengthen the students’ understanding of practical fluid mechanics (“plumbing” of pumps, valves, and compressors). Over the years students have frequently proposed control structures and plumbing systems that violate the laws of plumbing and plantwide control. Many of the errors are repeated year after year by even the best students in the class. The purpose of this paper is to point out to students and young engineers some of these common errors. The hope is that these practical common-sense examples will help students avoid some of the common pitfalls that can make the difference between an operable and an inoperable chemical process.