Abstract:

A new spiral-wound air-gap membrane distillation (AGMD) module based on hollow fiber (SW-AGMD-HF) involved with the adiabatic tubular net was developed for seawater desalination. Permeate flux (J_W), gained output ratio (GOR) and thermal efficiency (η) were introduced to indicate process performance. The effects of hot feed-in temperature, hot feed-in flow rate, cold feed-in temperature and cold feed-in flow rate on the above three indicators were studied with 3.5% (mass) modeled seawater as feed solution. J_W, GOR and η increased as a higher hot feed temperature was used. J_W decreased with increasing cold feed temperature, while GOR and η presented an opposite tendency. A larger hot feed flow rate would only increase J_W. Cold feed flow rate showed a slight influence on desalination process performance. During the experiments, total dissolved solid of permeate was kept blow 3.0 mg·L^-1 all the time, and relative ion rejection rate was above 99.99%. The maximum permeate flux of 5.87 L·m^-2·h^-1, maximum gained output ratio of 5.37 and maximum thermal efficiency of 0.943 were also obtained. Consequently, the introduction of clean energy as an alternative of conventional electric heat source could further raise the actual application potentiality of membrane distillation process.

Key words: hollow fiber membrane module, air gap membrane distillation, distillation, desalination, design

摘要：

利用自制的添加隔热管状隔网并呈螺旋缠绕结构编排的中空纤维膜组件进行了空气隙式膜蒸馏(AGMD)海水淡化过程性能研究, 实验以模拟标准海水(质量分数3.5%, 总溶解性固体含量35000 mg·L^-1)为热料液进水, 考察了热料液进水温度、热料液流量、冷凝液进水温度和冷凝液流量对膜通量、造水比和热效率的影响。结果表明, 随着热料液进水温度增加, 膜通量、造水比和热效率均增加;冷凝液进水温度增加, 膜通量下降而造水比和热效率增加;热料液流量增加, 膜通量上升而造水比和热效率明显下降;冷凝液进水流量对膜蒸馏过程性能影响较小。实验过程中产水TDS始终保持在3.0 mg·L^-1以下, 相应的离子去除率高于99.99%, 膜通量、造水比和热效率最高可分别达5.87 L·m^-2·h^-1、5.37和0.943。研究表明, 引入清洁能源取代传统电加热驱动热源将进一步突出膜蒸馏技术的实际应用潜力。

关键词: 中空纤维膜组件, 空气隙式膜蒸馏, 蒸馏, 脱盐, 设计