Optimization Design for Mechanical Vapor Recompression Evaporation Crystallization System

To optimize the performance of the parallel-connected double-effect mechanical vapor recompression (MVR) evaporation crystallization system while meeting production requirements, a method for optimization design of the system based on the strength Pareto evolution algorithm (SPEA2) was proposed to further exploit the energy saving potential of the system. A mathematical model of the optimization problem was established by analyzing the effects of the operating variables on the system performance, and the constraints of mass and energy balances of the model were also imposed. The mathematical model was calculated by SPEA2 multi-objective evolutionary algorithm, where the minimization of total power consumption and heat transfer area was taken as the optimization object, and the optimal combination of evaporation temperature and compression temperature rise was obtained following the fuzzy set theory. The results show that the total power consumption of the system is lowered by 22.1 kW and the heat transfer area is reduced by 31.2 m2. The coefficient of performance (COP) and exergy efficiency of the system are heightened by 7.94% and 5.91% respectively, and the exergy loss of the system is reduced by 38.4 kW. It is concluded that application of the optimization design method based on SPEA2 can improve the energy utilization and thermodynamic perfection degree of the parallel-connected double-effect MVR evaporation crystallization system. © 2020, Editorial Office of Journal of Xi'an Jiaotong University. All right reserved.