A Cost-Based Strategy to Design Multiple Shell and Tube Heat Exchangers

Process Integration has been applied in several industrial processes mainly using standard shell and tube heat exchangers (1-1 or 1-2). The flow arrangement in 1-2 multiple shell and tube heat exchangers involves part counter-current flow and part co-current flow. This fact is accounted for in the design by introducing a $FT$ correction factor into the 1-1 heat exchanger design equation. To avoid some steep regions in the feasible space of heat exchangers design some authors introduce other parameters like $XP$ or G. Until now it was not possible to have an overall map to give some guidelines of how to choose between the several $XP$ approaches established in the literature. This paper summarizes the current existing criteria in a general design algorithm $DeAl12$ to show a path for the calculations of the main design variables of the heat exchanger. Also a new strategy design algorithm $StratDeAl12$ is introduced in this paper to allow the best choice between the existing $XP$ approaches based on the heat exchanger cost minimisation. Several examples illustrate the advantage of using the developed algorithm and the deviations obtained in the heat exchanger cost if a wrong approach was chosen.