Design of heat exchanger network physical layout in process plants using a mixed-integer model

This paper presents a methodology to compute the location of heat exchangers in the chemical process plant based on a fixed-topology heat exchanger network. The location of the heat exchangers is computed by minimising the pipe length required to transport the heat-integrated streams from the supply process equipment to the target process equipment. The pipe length is estimated as the sum of the rectangular distances between the coordinates of the process equipment connected along the pipe, using a mixed-integer linear model, and provides a lower bound for the pipe length required by the exchanger network. Layout constraints can be added to the model, such as minimum distances between equipment and zones of the plant where heat exchangers are restricted to being placed. It is also possible to restrict heat exchangers to being near specific equipment, such as heat-integrated reboilers located beside their distillation columns. The proposed methodology is applied to a number of heat integrated processes, with varying degrees in number of streams and heat exchangers.