SYNTHESIS OF STRUCTURAL-CONSTRAINED HEAT-EXCHANGER NETWORKS - I - SERIES NETWORKS

In this two-part paper, a MILP sequential synthesis approach based on a new network representation is proposed to facilitate the involvement of the process engineer in the synthesis of series and split heat exc hanger networks. The network configuration is defined by choosing the neighboring units for every performed heat match. In this way, the str uctural conditions specified by the designer to simplify the network c omplexity can be considered from the beginning by properly restraining the set of feasible neighbors for each potential unit. Such topology constraints usually have a great impact on the problem feasible space, thus preventing from achieving the least utility usage. Consequently, a net heat flow across the pinch normally arises and the notion of ps eudo-pinch point becomes worthwhile. The proposed network representati on allows to develop a MILP framework to sequentially determine (a) th e structural-constrained utility usage target to be achieved by the so ught design; (b) the stream pseudo-pinch temperatures and (c) the solu tion space within which any configuration stands for a network satisfy ing the design specifications and the constrained utility target. In t his way, a realistic network design featuring the lowest number of uni ts can be found and no further modifications to meet the topology cond itions will be required. To reduce the size of the MILP network design problem, a decomposition strategy is applied so as to independently f ind the network configurations at both sides of the stream pseudo-pinc h temperatures. Series networks are only considered in Part I. Several examples have successfully been solved in a short C-PU time. (C) 1998 Elsevier Science Ltd. All rights reserved.