结合氯化钾结晶工序对蒸发工序氯化钾溶液出料温度的要求及多效蒸发最佳效数的确定原则，建立了以NaCl-KCl为溶质的浓海水提钾蒸发过程的四效错流蒸发模型。根据NaCl-KCl-H₂O的水盐体系相图溶解度呈线性变化的特点，拟合出不同浓度范围的NaCl-KCl溶液的溶解度方程；通过实验测得常压下不同浓度NaCl-KCl溶液的沸点数据，并拟合出沸点随浓度变化的经验公式。对6种带有固相析出的四效错流蒸发过程进行模拟计算，并对计算结果进行经济性评价，得出最优蒸发工艺方案为Ⅳ-Ⅲ-Ⅰ-Ⅱ；在此最优工艺方案基础上得出本设计条件下的加热蒸汽压力在260~270 kPa为最佳。

Based on the requirement of the potassium chloride crystallization process on the discharging temperature of potassium chloride solution in the evaporation process and the confirming principle for the best number of multi-effect evaporation,a four-effect crossflow evaporation model is established for the evaporation process of potassium extraction from concentrated seawater with NaCl-KCl as solute.According to the characteristics of linear change on solubility curve of the phase diagram of NaCl-KCl-H₂O system,theequationsoftheliquid-solid phase equilibrium curves are obtained by mathematical fitting method.The boiling point data of the solution at different concentrations of NaCl-KCl are obtained by fitting experimental data at atmospheric pressure.Six kinds of four-effect crossflow feed evaporation process with solid precipitation are simulated and the simulation results are evaluated in economy,from which the Ⅳ-Ⅲ-Ⅱ process scheme is selected as the optimal evaporation process.The most suitable heating steam pressure is in the range of 260-270 kPa based on the optimal process.