The Design and Synthesis of Batch/Semicontinuous Processes

Abstract

Until now, many papers discussed the formulation of sizing problem for the optimal design of batch/semicontinuous processes. In this study it shows that the solutions for the sizing problem of batch/semicontinuous processes are applicable to retrofitting problem. Then several synthesis procedures have been proposed because the economic structural design and efficient equipment utilization can reduce the overall idle time in the processing units. In this study, to improve the initial design of batch/semicontinuous processes, an mathmatical procedure is proposed. The proposed approach is to make a superstructure which fully contains all possible structures. And then using a MINLP(mixed integer nonlinear programming) model, we obtain the optimal process network. The MINLP model contains methodology deciding the candidates of merging tasks and using parallel equipments. Thus, the economic savings of capital cost of batch/semicontinuous processes are possible by adding equipment in parallel for bottleneck stages or merging/splitting tasks. The MINLP model is then solved by using a generalized reduced gradient algorithm. The effectiveness of the MINLP model in single product batch plant is demonstrated by solving example problem. Also, by inserting intermediate storage tanks, we reduce the capital cost for batch/semicontinuous processes and determine the optimal size of the intermediate storage tank.