A control philosophy for complex Non-square chemical process. (December 2022)

• Record Type: Journal Article
• Authors: Sujatha, V.; Panda, Rames C.
• Is Part Of: Journal of loss prevention in the process industries. Volume 80(2022)
• Publication Date: 2022-12
• Subjects: Input-output pairing -- Non-square MIMO systems -- Under-defined -- Over-defined -- Interaction analysis; Chemical industries -- Safety measures -- Periodicals; 660.2804
• DOI: 10.1016/j.jlp.2022.104900
• Languages: English
• ISSNs: 0950-4230

Abstract

Abstract: All the complex non-square chemical processes may have thousands of measurement and control loops and these loops should be paired properly. A term control philosophy decides the structural decisions of the overall plant instead of the term plantwide control which is not meant for tuning each of these loops. Operational safety require direct inclusion of control system into associated safety to handle disturbances and failure in critical devices of a chemical process. Though most of the process units are non-linear and multivariable in nature, their operations are based on linear controllers to provide overall stability and safe operations. As the design of an appropriate control structure for complex non-square chemical processes are difficult, it is very challenging to control these processes. Non-square systems offers safe operational procedures and ensures plant safety. The proposed method of control configuration selection for non-square Multi Input Multi Output (MIMO) system is an extension of square MIMO system. An appropriate selection of control configuration for non-square chemical processes have been addressed in this paper. The proposed method of dynamic loop interactions is based on the computation and comparison of areas under responses for all possible combinations of manipulated and controlled variables. The control configurations that emerged from subsequent analyses are able to provide adequate inherent safety to the overall process in a closed-loop sense. This paper assesses the interaction among the loops having unequal number of input and output variables. This procedure is illustrated via simulation of examples taken for both the under-defined and over-defined non–square MIMO system. Also the quantitative measure of process safety index is obtained for the process. Highlights: Interaction analysis for non-square Multi Input Multi Output (MIMO) system. Provides a technique to assess the control loop interactions and rank the loops for non-square MIMO systems. Proposed methods is carried out for 2-by-3 and 3-by-2 non-square MIMO systems.