Decomposability of the Control Structure Design Problem of Recycle Systems

Abstract

The control structure design is an important part of process synthesis tasks. The design becomes more difficult if recycle is present in the process to be controlled. The objective of this work is to clear up if the control structure design should be completed for the whole process simultaneously or it can be decomposed into subproblems involving only one unit of the whole system. Investigations show that the recycle can have an effect on the control structure that complicates the design problem. Simple case studies and exhaustive investigation of the industrial control problem are completed. Our investigations prove that decomposability can be applied simplifying the proper pairing of the controlled and manipulated variables, and this can facilitate the control structure design problem.

Reductive Elimination of ArCF3 from Bidentate PdII Complexes: A Computational Study

“…Because of the large number of variables and a combinatorial growth in the total number of possible control structures with respect to the number of variables, a complete dynamic evaluation of all alternative control structures is impractical for any realistic process. To deal with this disadvantage, several researchers decomposed the problem into a hierarchy of decisions,206–209 motivated by Douglas's hierarchical procedure for conceptual process design 210. In this approach, some alternatives are eliminated according to economic, environmental, or controllability considerations at each level of hierarchy.…”

An overview on controllability analysis of chemical processes

“…Because of the large number of variables and a combinatorial growth in the total number of possible control structures with respect to the number of variables, a complete dynamic evaluation of all alternative control structures is impractical for any realistic process. To deal with this disadvantage, several researchers decomposed the problem into a hierarchy of decisions, [206][207][208][209] motivated by Douglas's hierarchical procedure for conceptual process design. 210 In this approach, some alternatives are eliminated according to economic, environmental, or controllability considerations at each level of hierarchy.…”