Short-Cut Procedures for the Simultaneous Design of a Process and Its Control System. Progress Report, April 16, 1982-April 15, 1983

摘要

Previous studies on heat-exchangers networks and sequences of separation systems have assumed that the process flow rates were fixed, but it is shown that the optimum flows depend on the heat-exchanger network and the separation system chosen. A procedure for controlling these complex processes has been developed and a short-cut method is described for assessing the incremental costs associated with control at the preliminary design stage. In order to simplify the analysis, we have developed very simple approximate solutions of Underwood's equations for the minimum reflux ratios (which are used to find the vapor rates). The approximate solutions can be used to develop very simple quantitative criteria for deciding whether the direct or indirect separation sequence is the cheapest. The simplified solution of Underwood's equation can also be used to develop short-cut design procedures for complex distillation columns, i.e., sidestreams, prefractionators, sidestream strippers and reboilers, etc. An expression for the maximum purity of the sidestream composition has been derived and some results have been obtained for prefractionators. (ERA citation 08:032166)