Heat exchanger network synthesis considering detailed heat exchanger design under fouling

Abstract

The synthesis of heat exchanger networks and the design of heat exchangers are critical topics in the field of chemical engineering. The research on both aspects has been ongoing without interruption. Existing coupled designs of heat exchanger networks and heat exchangers often assume steady-state stream characteristics, neglecting the impacts of flow rate fluctuations and fouling effects on network and exchanger performance. This paper introduces flow uncertainty and fouling models into the synthesis of heat exchanger networks and detailed heat exchanger design. The chance constrained programming method is employed to design heat exchanger networks under uncertainty conditions, with utilizing Set Trimming to optimize heat exchanger. The objective is to minimize the total annual cost of the heat exchanger network. Five scenarios are designed to explore the relationships among uncertainty, fouling, and economy. Additionally, sensitivity analyses are conducted on the magnitude of uncertainty and confidence levels. The results indicate that the threshold fouling model can reduce the equipment investment cost slightly, by about 1 %. The synthesis of the heat exchanger network under uncertainty can improve its resistance to fluctuation. The flexibility index can be increased by 75.6 % by only a 3.5 % increase in operating cost.