Optimization of velocity for energy saving and mitigating fouling in a crude oil preheat train with fixed network structure

•Energy saving, fouling and pressure drop are optimized simultaneously.•Fluid velocity is used to correlate heat transfer, fouling and pressure drop for energy saving.•The optimal velocity distribution can be found out by the proposed method.•Sensitivities to velocity for heat exchangers are studied.•The results show a significant increase in energy savings.

Fouling of the inside of tubes in crude oil preheat systems increases pressure drop and pumping costs. In this paper, a method is proposed for optimizing crude oil velocity to reduce fouling of the heat exchanger tubes thereby maintaining heat transfer rates and reducing pressure drop. A simulated annealing algorithm is proposed to describe and optimize the interactions between heat transfer, pressure drop and fouling by adjusting fluid velocity. A specific crude oil heating system is used as a case study to verify the application of the algorithm. Results from case study showed that total annual cost is reduced by 6.4%, indicating that a better performance can be obtained by velocity redistribution using proposed method.