Computer Automated Start-Up and Shutdown of an Air Separation Plant

Abstract

Process control computers have gained wide acceptance within the chemical process industries. Their application has, however, been predominantly limited to processes which have already completed start-up and have achieved reasonably steady operating conditions. Recently, however, inexpensive "time-of-day" electric power rates are causing many companies to consider intermittent operation; this has also provided the impetus for computer automated start-up and shutdown. Air Products and Chemicals, Inc. has implemented a computer automated start-up and shutdown program in an air separation plant. Minimal operator intervention is required, but where necessary the operator is directed via a display on the CRT to take any necessary action. The computer waits for the operators confirmation of task completion before proceeding to the next sequence. Start-up and shutdown times are as good as the "best operators." This paper discusses the scope of the project, the method of implementatlon, the performance of the system, the benefits achievable, and possible extensions of this program.