膜蒸馏的现状及发展前景综述.doc

膜蒸馏的现状及发展前景综述 刘凡 环境科学 摘要 近年来，随着膜分离技术的快速发展，Summarize of present situation and development prospects of membrane distillation Fanliu Environmental science ABSTRACT In recent years, with the rapid development of membrane separation technology, more and more film applied to real life and production. Membrane distillation is a new type of separation technology that developed in the 1980s. It is the new type that combination of membrane separation technology and traditional evaporation procession. Like conventional distillation, membrane separation process is basis on the vapor liquid equilibrium, and depending on the implementation phase change latent heat of evaporation. Vacuum membrane distillation is one of the four kinds of membrane distillation operation mode with large flux, high separation factor, simple equipment, easy to operate and implement etc. that can be widely used in the removal of volatile components and seawater, brackish water desalination, etc. The state advocates the construction of a harmonious society today, develop and use the membrane distillation technology for desalination has the vital significance to achieve energy conservation, emission reduction and comprehensive utilization of wastewater. It’s mainly used in metallurgy industry, organic wastewater, and seawater desalination. This review will present situation and prospects of membrane distillation for sorting and summary. Key words: Membrane distillation Waste water treatment Seawater desalination 1膜蒸馏技术简介 膜蒸馏是在上个世纪八十年代初发展起来的一种新型分离技术，是膜分离技术与传统蒸发过程相结合的新型膜分离过程。它与常规蒸馏一样都以汽液平衡为基础，依靠蒸发潜热来实现相变。它以膜两侧的温差所引起的传递组分的蒸汽压力差为传质驱动力，以不被待处理的溶液润湿的疏水性微孔膜为传递介质。在传递过程中，膜的唯一作用是作为两相间的屏障，不直接参与分离作用。分离选择性完全由气——液平衡决定。膜蒸馏过程是热量和质量同时传递的过程。膜的一侧与热的待处理的溶液直接接触称为热侧，另一侧直接或间接地与冷的液体接触称为冷侧。由于膜的疏水性，水溶液不会从膜孔中通过，但膜两侧由于挥发组分蒸气压差的存在，而使挥发蒸气通过膜孔从高蒸气压侧传递到低蒸气压侧，而其它组分则被疏水膜阻挡在热侧。从而使膜有透过通量，实现了混合物的分离或提纯。这与常规蒸馏中的蒸发、传质、冷凝过程十分相似。所以称其为膜蒸馏。过程如图： 根据挥发性组分在膜冷侧冷凝方式的不同膜蒸馏可分为四种不同结构和操作方式，即：直接接触式膜蒸馏