摘要
对纯水体系以及NaCl溶液浓缩过程中真空膜蒸馏传递阻力的分布进行了研究,考察了操作条件对传递阻力分布的影响,分析了传递阻力在浓缩过程的变化原因.结果表明：在纯水体系下,温度和膜表面流速对膜阻力影响较小,其值在162-164.7（Pa·h·m^2）/kg范围内变化;边界层阻力受操作条件影响较大,较低的流量和较高的料液温度导致较高的边界层阻力.在NaCl溶液浓缩过程中,渗透通量随浓缩时间起先呈缓慢下降趋势,传递阻力以边界层阻力和膜阻力为主,当料液浓度超过临界值时,渗透通量发生骤降,污染层阻力骤升,膜表面发生结晶污染.但利用清水冲洗受污染膜后,渗透通量恢复率95%左右.因此,控制浓缩终点的浓度低于临界点浓度将有效避免膜污染的形成.
Vacuum membrane distillation process（VMD）was carried out on the pure water system and the NaCl solution concentration process,respectively.The transfer resistances of VMD were studied.In pure water system,the effect of both feed temperature and feed flow rate on membrane resistance could be avoided.The value of membrane resistance was ranged in 162.0 - 164.7（Pa·h·m^2）/kg.However,a lower feed flow rate and a higher feed temperature could lead to a higher boundary layer resistance.The permeate flux decreased gradually and the membrane fouling resistance increased slightly,when the solution was concentrated up to a critical point in the NaCl solution concentration process.The crystallization fouling was occurred,while the concentration was beyond the critical point.The recovery of permeate flux could reach about 95% by fresh water flushing.Therefore,the membrane fouling could be avoided efficiently by controlling the determining concentration below the critical point.
出处
《膜科学与技术》
CAS
CSCD
北大核心
2014年第6期1-5,34,共6页
Membrane Science and Technology
基金
上海市科技攻关计划(11DZ1205201和1351102000)
江苏省科技工业支撑计划(BE2013031)
关键词
真空膜蒸馏
传递阻力分布
浓缩
膜污染
vacuum membrane distillation
transfer resistances
concentration
membrane fouling
