高温多效膜蒸馏用于处理高盐溶液的实验研究

Deep Concentration of Brine by Multiple-Effect Membrane Distillation at High Temperature

膜蒸馏通常在温度低于90℃的条件下操作,而对于高盐溶液,由于浓差极化和饱和蒸气压下降比较明显,在通常操作温度下膜通量和热利用率都很低。采用具有内部潜热回收功能的多效膜蒸馏组件在高温操作条件下对以氯化钠为代表的无机盐浓溶液的深度浓缩进行了研究,着重考察了冷进料温度T1,加热后料液温度T3、浓度、流量等操作参数对膜通量、造水比和截留率的影响。结果表明,当料液质量分数为5%,热料液温度T3为100℃时,膜通量和造水比的值分别为3.1 L/(m2·h)和15.2;虽然膜通量和造水比均随料液浓度增大而下降,但是当料液质量浓度为25%,T3为105℃时,膜通量和造水比值仍可达1.53 L/(m2·h)和5.8;且截留率达到99.95%以上。在60 d的连续运行中,膜组件保持了良好的性能稳定性。结果表明高温多效膜蒸馏技术能够有效用于高盐溶液的深度浓缩。

Membrane distillation is usually operated at temperature 〈 90 ~C. However, when dealing with concentrated salt, permeation flux （J） and thermal efficiency are much lower because of the reduction of vapor pressure, as well as concentration and temperature polarization effects. In this paper, multiple- effect membrane distillation （MEMD） was explored in the range of 85--105℃ for deep concentrating feed of NaC1 solutions. The effects of cold feed-in temperature T1, heated feed temperature T3, feed-in concentration and feed-in flow rate on J, performance ratio （PR） and retention rate were investigated. The experimental result indicated that the J and PR were 3.1 L/（m2.h） and 15.2 for 5% NaC1 solution when T3 was 100 ℃ , the values of both J and PR decreased with the increase of feed concentration, how- ever, their values could still achieve 1.53 L/（m2·h） and 5.8 respectively for 25% NaC1 solution when the value of T3 was 105℃, while the salt retention rate could reach more than 99.95%. Also, a long tern operational stability of the MEMD process was tested for 15% NaC1 solution for 60 days. The experimental results indicated that MEMD process showed good operation stability.