Heat Exchanger Network Retrofit Using the Reduced Superstructure Synthesis Approach

This paper presents a new synthesis method for retrofitting heat exchanger networks using a two-step procedure. In the first step, the problem data for the network to be retrofitted is extracted and solved for a grass-root scenario using the stage-wise superstructure synthesis method. The matches selected in the solution of this first step, together with the existing units in the original network, constitute the candidate matches used to initialise a reduced superstructure in the second step. These initialising matches are the binary variables of the model, which is solved as a mixed integer non-linear model. The reduced superstructure is systematically initialised considering the sizes of the existing units as a guide. This is done so as to ensure that the heat transfer areas of the existing units are utilised as much as possible before making additional investment. One of the key benefits of this new synthesis approach for retrofitting heat exchanger networks is that the resulting reduced superstructure is relatively computationally less intensive to solve. The proposed method of this paper has been applied to two examples from the literature and the solutions obtained compare well with existing solutions. © 2018, Springer Nature Singapore Pte Ltd.