(363l) Matrix Non-Structural Model and Its Application in Heat Exchanger Network without Split Streams

Heat integration by heat exchanger network (HEN) is an important part in chemical process system synthesis, which improves heat recovery and thus reduces the energy required in existing plants. From the perspective of optimization, the simultaneous synthesis of HEN belongs to a mixed-integer and nonlinear programming problem. Both stage-wise superstructure (SWS) model and chessboard model are the most widely used, and belong to structural models, in which a framework is assumed for stream matching, and may make the global optimal solution outside its feasible domain defined by the framework. A node-wise non-structural model (NW-NSM) was proposed to get more universal stream matching options, but it requires a mass of structural variables and extra multiple correction strategies. The aim of this paper is to develop a novel matrix non-structural model (M-NSM) for HEN without split streams from the perspectives of global optimization methods and superstructure model. In proposed M-NSM, the heat exchanger position order is quantized by matrix elements at each stream and a HEN structure is initialized by random generation of matrix elements. An approach for solving HEN problems based on matrix real-coded genetic algorithm (MRCGA) is employed in this model. The MRCGA not only keeps the crossover and mutation flexibility of binary codes, but it is also suitable for matrix optimization computation. Using the proposed coding manner, the MRCGA can directly solve HEN optimization through genetic operations. The results show that M-NSM provides more flexibility and freedom to expand the search region for feasible solutions with higher efficiency than previous models.