Target-Oriented Methodology on Matching Heat Transfer Areas for a Multiperiod Heat Exchanger Network Retrofit

Abstract

Heat exchanger network retrofit problems in a multiperiod operation are commonly solved in a stepwise manner. The matching of heat transfer areas is generally used to finalize the retrofit after the determination of the retrofit target of the heat exchanger network. Conventional heat transfer area matching methods are either experience based or model based methods, which may lead to indeterminate solutions or scale limitations in the optimal matching strategy. In this work, a systematic approach and algorithms for matching heat transfer areas in a multiperiod heat exchanger network retrofit are proposed. The methodology is based on the reverse order matching method and the matching algorithms of a bipartite graph. The proposed approach achieves four main objectives: to maximize the number of substituted heat exchangers, to minimize the increases in heat transfer area, to minimize the investment cost after a retrofit, and to minimize the investment cost given the preference rankings restrictions of heat exchanger operation pressures. The heat exchanger network retrofit of a diesel hydrogenation unit in a multiperiod operation is employed to illustrate the procedure and advantages of the proposed method. The results obtained by the proposed method and the methods in the literature are compared and analyzed. The results indicate that the proposed method enables the practical matching restrictions and costs to be taken into account. In addition, the proposed method is simple and easy to implement, which is conducive to solving the problems of heat exchanger network retrofitting quickly and accurately.

Framework for the Multiperiod Sequential Synthesis of Heat Exchanger Networks with Selection, Design, and Scheduling of Multiple Utilities

“…In addition, most industrial plants must operate under different conditions (e.g., multiproduct chemical plants, power plants running at part-load, and systems integrated with intermittent renewable sources) for a large number of hours. Examples are oil refineries, , combined cycles, and solar-driven supercritical biomass gasification plants . For these types of industrial plants, it is necessary to design a multiperiod HEN which takes into consideration the expected mass flow rates and temperatures of the streams during the different operating periods.…”