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

Abstract

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.