Simultaneous design of heat exchanger network for heat integration using hot direct discharges/feeds between process plants

Abstract

A chemical or petrochemical site is generally made up of several plants that are linked together throughprocess streams. The linking process streams are often cooled down in their source plants, then transferredinto storage tanks, and reheated in destination plants. This repeatedly cooling and heating resultsin low energy-use efficiency and more area installed in heat exchanger network. In this study, weintroduce a heat exchanger network superstructure based on stage-wise model for heat integration usinghot direct discharges/feeds between plants, and develop a new mixed-integer nonlinear optimizationmodel to simultaneously design heat exchanger network. Unlike conventional HEN design, the modelcan simultaneously synthesize heat exchanger networks for multiple plants, and be able to addressvariable supply or target temperatures of process streams. The objective is to minimize total annual costof heat exchanger networks in source and destination plants. Three examples are used to demonstratethe performance of the proposed model and solution approach. The computational results indicate thatthe simultaneous design of heat exchanger network for heat integration using hot direct discharges/feedsbetween plants achieves a significant decrease in total annual cost when compared to the separatedesign of heat exchanger networks for source and destination plants