PTFE平板膜用于不同膜蒸馏过程淡化盐水的实验研究

Experimental study on desalination of brine by different membrane distillation process using PTFE flat membrane

为了提高膜蒸馏的通量、热效率,并加快膜蒸馏产业化进程,采用聚四氟乙烯(PTFE)平板疏水多孔膜开展膜蒸馏淡化盐水的实验研究,着重考察直接接触式膜蒸馏(DCMD)、真空膜蒸馏(VMD)、吹扫式膜蒸馏(SGMD)过程中热侧料液进口温度、热侧料液流速、冷侧料液流速、进料液浓度、真空度对膜蒸馏性能的影响。实验结果表明,膜通量随着热侧料液进口温度、热侧料液流速和真空度的增加而增加,其中,热侧料液进口温度对膜通量影响最大,热侧料液进口流速对膜蒸馏影响很小,而DCMD中冷侧料液流速对膜通量基本没有影响。在本实验研究范围内,料液浓度对膜通量和截留率的影响很小。在VMD过程中获得的膜通量的最大值为35 kg/(m^2·h),其对应的操作条件分别为热侧料液进口温度为80℃,流速为130 L/h,真空度0.07 MPa,进料液浓度6%。整个实验过程中截留率都在98%以上。

In order to increase flux and thermal efficiency of membrane distillation,and accelerate the industrialization process of membrane distillation,an experimental study on membrane distillation desalination of salt water was carried out using polytetrafluoroethylene（ PTFE） hydrophobic porous membrane. The effects of the operating conditions,including the temperature of hot side,flow rate of hot and cold side,vacuum and the concentration of the feed solution,on the process of direct contact membrane distillation（ DCMD）,vacuum membrane distillation（ VMD） and sweeping gas membrane distillation（ SGMD） were investigated. The results showed that the flux for DCMD,VMD and SGMD processes increase with the increasing of the temperature,and flow rate of hot side and vacuum. In addition,the temperature of hot side had the dominant effect on the flux,and the flowrate had little effect on membrane distillation,and the flow rate of cold side had little effect on flux in DCMD. The effect of liquid concentration on membrane flux and rejection were both small. In the process of the experiment,the maximum flux was 35 kg/（ m2·h）,and it was obtained in VMD.The corresponding operating temperature and flow rate of hot side were 80 ℃,130 L/h respectively.The vacuum was 0. 07 MPa and the concentration of Na Cl was 6%. Moreover,the rejection rate was98% in the whole process.