鼓气减压膜蒸馏过程研究

STUDY ON AIR-BLOWING VACUUM MEMBRANE DISTILLATION

设计了新型鼓气减压膜蒸馏(AVMD)过程,在原水进入疏水膜组件前鼓入低压压缩空气,形成气液混合流进入疏水膜组件,在疏水膜组件的产汽出口外接负压系统,构成AVMD系统。采用疏水性聚偏氟乙烯中空纤维微孔膜,以自来水为测试液,研究了鼓气强度、进料温度、流速、冷侧真空度对AVMD过程性能的影响,考察了AVMD对不同NaCl含量溶液的分离性能。结果表明,随着鼓气量、进料液温度、流速、真空度的提高,AVMD过程通量有明显的增加,而产水电导率始终低于0.3mS.m-1。当进料液温度70℃,冷侧真空度85kPa,进料流速1.33m.s-1时,AVMD过程膜通量可高达45kg.m-.2h-1,而相同实验条件下减压膜蒸馏(VMD)过程的通量约为30kg.m-.2h-1。

Hydrophobic polyvinylidene fluoride （PVDF）bollow fiber membranes were employed in the newly designed air-blowing vacuum membrane distillation （AVMD） process for purpose of desalination and pure water production. Effect of operation conditions, such as the air-blowing intensity, feed temperature, flowing velocity, concentration and the vacuum pressure on the performance of AVMD process were studied. The results showed that the flux increased obviously as the feed temperature, air-blowing intensity, or the vacuum pressure enhanced. But it declined as the feed concentration enhanced. The conductivity of the product water was kept lower than 0.3 mS ·m^-1 as the operation conditions varied. When tested at 85 kPa vacuum degree, 70 ℃ with a velocity of 1.33 m·s^-1, the flux of AVMD process reached 45 kg·m^-2·h^-1, which is 15 kg·m^-2·h^-1 higher than that of VMD process tested at the same conditions.