并联低温多效海水淡化系统优化与分析

建立了并联流程下的低温多效蒸发海水淡化系统优化数学模型。该模型以整个系统的单位产量淡水成本最小为优化目标,以加热蒸汽温度及各效二次蒸汽温度为决策变量,并应用MATLAB及其优化工具箱对其进行了求解,同时与非优化设计情况进行了比较。结果表明:当淡水产量不变,随着效数的增加,淡水成本先减小后增大,最优效数为7效,优化淡水成本为5.51元/t;与非优化设计相比,在达到6效之前,优化设计的加热蒸汽量减小,蒸发器传热面积增大,优化设计的淡水成本小于非优化设计的淡水成本。在6效之后,二者相差不大。

Optimization and analysis on parallel low temperature multi-effect distillation system for seawater

An optimal mathematical model was established for the parallel low temperature multi-effect distillation system(LT-MED),which aimed at the minimum unit cost of fresh water.Based on such decisive variables as the heating steam temperature,secondary vapor temperature of each effect,the optimum mathematical model was solved by using MATLAB Toolbox.The optimal and non-optimal design cases were compared.The results show that the cost of fresh water decreases firstly and then increases with increasing the number of effects in case of constant fresh water yield.The optimal fresh water cost is the lowest of all when the number of effects reaches 7,which is 5.51 yuan/t.Compared with the non-optimal system,when the number of effects is less than 6,the optimal amount of heating steam decreases,the optimal heat transfer area of evaporator increases,and the optimal cost of fresh water is lower than the non-optimal cost of fresh water.When the number of effects reaches 6,the difference is not obvious.