Synthesis of control systems for chemical plants A challenge for creativity

Abstract

Synthesis of control systems for chemical plants is that step during process design and process engineering where the chemical engineer selects the control objectives; measured outputs and manipulated inputs; the control structure connecting measurements and manipulations as well as the control laws between them. This paper reviews the problem, its characteristics, previous works on the subject and finally attempts a broad outline of future developments. First, it presents the scope of its content and then proceeds to discuss the various facets of process control system synthesis. The review of the previous works provides a critical panorama of earlier problem formulations, solutions and methodologies, outlining their assumptions, extent of applicability, advantages and shortcomings. A series of specific examples demonstrates the multitude of control system synthesis problems and sets the stage for an in depth examination of its proper formulation and characteristics. It is pointed out that the synthesis of a process control system is only a part of the general system which oversees the operation of a plant. Consequently, questions related to safety, performance monitoring, detection of faults, etc., are also discussed. Since the operability of a chemical process is closely related to its design, the paper explores the effect that process design has on the synthesis of a control system and vice versa. Furthermore, the paper attempts to organize all the above issues in a coherent system which can guide the control designer towards the synthesis of effective control systems. Finally, the need for a change in the process control curricula is examined and some new provocative questions for future research are raised.