Applied Process Control

5Control Strategy Design for Processing Plants

The piping and instrumentation diagram (Section 2.1) is the key document describing a processing plant, around which the rest of the design revolves. In the design and construction phases, it must be kept up-to-date, and in computerised documentation systems it will be found to link automatically to virtually every other design document. So at an early stage, it becomes necessary to specify the plant instrumentation scheme and control philosophy. The objective of the control engineer is initially that the plant ‘should be able to take care of itself’ under most circumstances. Once that objective is reached, he or she will seek to get the plant to ‘take care of itself optimally’. This rests on ...