Optimal Synthesis Of The Heat Exchanger Network Based On Pressure Drop Constraints

Since the21st century, the high-speed growth of energy consumption, theincreasingly grim energy situation and improvement of environmental requirements make ourcountry in urgent need of improving the energy utilization efficiency. As the energy recoverysystem is the key for improvement of energy utilization efficiency, the research of heatexchanger network become particularly necessary and the optimal synthesis of heat exchangernetwork has become one of the most important research directions in the process industry.Both pinch technology and mathematical method are based on subjective assumption offilm heat-transfer coefficient and there is no guarantee that assumption of film coefficient isthe same with calculated value in detailed heat exchanger design, which lead to optimalnetwork synthesized by two methods is only close to the optimum but cannot guaranteeconsistently in industrial applications. This paper builds an improved MINLP model of HENbased on pressure drop constraints. The HEN is synthesized on the same basis as detailed heatexchanger design, which ensures the film coefficients in synthetic network are consistent withthe values in the detailed design.At the same time a simultaneous optimization algorithm is proposed in this paper. Byincreasing a manual intervention, most of unreasonable matches which violatethermodynamic principle or engineering requirement can be canceled according to heuristicrules. The cost of pressure drop, the equipment investment and operation can besimultaneously optimized and the model can be applied to complex HEN problems at thesame time. The results of three case study has shown that the improved model andsimultaneous optimization algorithm has better application effect and can get a better networkstructure.