内部热能回收式多效膜蒸馏用于海水淡化及浓盐水深度浓缩

利用自制的具有高效内部热量回收功能的多效膜蒸馏组件对不同浓度的氯化钠水溶液进行浓缩研究.考察进料温度、浓度、流速对膜通量、造水比和脱盐率的影响.实验结果表明,料液加热温度T3升高时膜通量和造水比随之明显增加,而脱盐率保持不变；料液流速增加使膜通量增加,而造水比随之降低,脱盐率几乎不受影响；随着料液浓度的增加,膜的通量和造水比逐渐降低,脱盐率略微减小但影响很小.当料液中氯化钠浓度较低时,该过程的最大膜通量为6.8L/(m2·h),造水比为12.5；当料液中氯化钠浓度大于15％时,膜通量为5.2 L/(m2·h),造水比为6.2,脱盐率可达99.99％.实验结果表明,多效膜蒸馏技术可有效应用于海水淡化及常规海水淡化过程,例如反渗透和多效蒸发过程所副产浓盐水的深度浓缩和淡水生产.

Study on multi-effect membrane distillation for production of water from seawater or brine produced from traditional desalination processes

An experimental investigation was carried out on concentrating aqueous solution containing 0.1%~20% sodium chloride by using multi-effect membrane distillation(MEMD) device.Influences of various experimental conditions on water permeate flux,water gained-output-ratio(GOR) and rejection of salt were studied.The experimental results showed that the water permeation flux increased with increase of the feed inlet flow rate,and increased with increase of the heated feed temperature;the water GOR also increased with increase of the heated feed temperature,however,it slightly decreased with increase of the feed inlet flow rate;both the water permeate flux and water GOR decreased with increase of the concentration of sodium chloride in the feed solution;the rejection of salt was hardly affected by these factors.The water permeate flux could reach 6.8 L/(m2·h) and the water GOR could reach 12.5 when the concentration of sodium chloride in the feed solution was low;when the salt concentration was higher than 15%,the water permeate flux was still more than 5.2 L/(m2·h) and the water GOR was more than 6.2,the rejection of salt could reach 99.99%.Thus multi-effect membrane distillation process could efficiently deal with concentrated aqueous solution.