Design of shell and tube heat exchangers considering the interaction of fouling and hydraulics

Abstract

We extend a formulation of the heat exchanger design optimization with fouling modeling to consider the effect of fouling on hydraulics. A shell-side fouling model was added so the optimization can consider cases with fouling in the tube and shell sides. The focus is the design of heat exchangers with fouling behavior associated with a threshold model, like in crude preheat trains. We solve the optimization problem by using a newly proposed Set Trimming technique. We compare our results with the traditional approach of using fixed fouling factors and the previous approach of not considering the hydraulic impact of fouling. We conclude that considering the deposit thickness leads to more realistic results that are different than the ones obtained using the previous approaches. Moreover, we show that previous approaches can render designs with larger pressure drops than the maximum imposed by the constraints, as well as exchangers with higher areas.