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

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