膜蒸馏过程探讨  

Discuss about membrane distillation

作　　者：吕晓龙[1] 

机构地区：[1]天津市中空纤维膜材料与膜过程重点实验室-省部共建国家重点实验室培育基地,天津工业大学生物化工研究所,天津300160

出　　处：《膜科学与技术》2010年第3期1-10,共10页Membrane Science and Technology

基　　金：863课题工业循环冷却水膜集成净化过程研究(2008AA06Z303);天津市重点基金课题废水浓缩减排与淡化再利用技术研究(09JCZDJC26300)

摘　　要：讨论了膜蒸馏涉及的膜材料特性.提出水膜阻力概念,认为疏水膜材料结构的优化与膜蒸馏工艺有关.提出鼓泡膜蒸馏方法,在热流体中鼓入空气气泡,由气液两相流效应来强化热流体的扰动.提出透气膜蒸馏方法,通过气体的吹扫夹带作用,使膜孔内水蒸气的传质由低效的扩散转为高效的对流机理.提出曝气膜蒸发方法,利用不同温度的空气吸湿原理进行膜曝气.将膜蒸馏过程与化学除硬度、超滤耦合,可除去结垢性钙镁离子;将膜蒸馏过程与气浮絮凝过程耦合,可除去有机污染物,实现高倍率浓缩.提出多效膜蒸馏方法,膜组件兼有蒸发与换热功能,使膜蒸馏过程中的水蒸气冷凝与原水加热过程耦合,可以实现低成本的膜蒸馏过程.The characteristics of materials for membrane distillation（MD） process were discussed. ＂Liquidfilm resistance＂ was presented to define the resistance for gas/vapor molecules penetrating through membrane-solution interface. The relevance between membrane structure design and MD process optimization was emphasized. On the basis of membrane design and process optimization, an novel process method, bubble strengthened MD process was presented, in which compressed air was pumped into the hot feed solution. The heat and mass transfer was strengthened by gas-liquid two phases flow. What＇s more, the compressed air could partly penetrate the liquid film on membrane-solution interface, and so pass through the membrane millipores to the cool side of the membrane. The mass transfer of the vapor molecules in membrane pores was also strengthened. An air circulation sweeping membrane distillation process was also constructed using saturation humidity grads of the circulated sweeping gas to fulfill the MD process. A MD integration process was exploited. Traditional chemical method and ultrafiltration were used for the removal of calcium and magnesium. Floatation/air lifting and flocculation were used to remove the organic pollutant. Coupling with condign pretreatment method, wastewater could be concentrated to near saturation. As for energy recovery in MD process, an multiple-effect membrane distillation process was brought out, in which the membrane module possessed both evaporating and heat exchanging properties. The latent heat was used to preheat the feed solution and to low energy cost in MD process.

关 键 词：膜蒸馏 疏水膜 超疏水性 水膜阻力 膜过程 工艺耦合 

分 类 号：TQ028.8[化学工程]