Hierarchy of processing equipment configuration design problems for multiproduct chemical plants

Abstract

A procedure for performing one stage of designing multiproduct chemical plant--definition of the processing equipment configuration is proposed. At this stage, a three-level hierarchical structure of problems is formed--at the upper level, the parameters of the operational mode of the chemical engineering system that ensures the desired output of each product are found; at the middle level, the size and number of equipment units and methods of product processing for all processing stages are chosen; at the lower level, technological and mechanical design of individual pieces of equipment (machines) are performed. The decomposition of the processing equipment design problem into three problems described above reduces the original mixed integer nonlinear programming problem to one nonlinear programming problem and a set of integer programming problems, where the number of integer programming problems is equal to the number of processing stages. The reduced problems can be solved using available optimization methods, which considerably reduces the solution time and improves the quality of design solutions. Basic information links between the problems of different hierarchical levels are determined, general problem statements and an algorithm for the simultaneous solution of the upper and middle level problems is proposed. By way of example, the problem of selection and design of a mechanical agitator for a vertical bulk-capacity storage is considered.