利用空氣間隔式薄膜蒸餾法進行海水淡化之研究

Desalination by air gap membrane distillation

陳建智(Chien-Chih Chen)

指導教授 ： 黃孟槺

國立臺北科技大學/工程學院/化學工程研究所/碩士(2012年)

摘要

薄膜蒸餾(membrane distillation,MD)為近來被重視發展的一種技術，其特色為具有裝置簡單、可模組化、低成本、高介面面積等多方面之優點，氣隔式薄膜蒸餾原理乃是利用提升熱流體端的溫度差以及飽和蒸汽壓差為驅動力，以促使水蒸氣通過一多孔性疏水薄膜，再由冷流體端冷卻水蒸氣變成餾出液，進而達到分離的效果。
本研究以聚四氟乙烯薄膜(PTFE)利用空氣間隔式薄膜蒸餾系統模擬蒸餾海水，主要探討系統內流體流動型態對薄膜蒸餾之滲透通量的影響情形，預估蒸餾海水之理論滲透通量。固定冷卻水冷流體溫度在室溫25℃，增加熱流體的溫度差，以提升薄膜蒸餾的效率和純水產率。針對空氣間隔式薄膜蒸餾做海水淡化，根據不同之操作條件討論：(一)熱流體進口溫度、(二)流體體積流量、(三)薄膜孔隙尺寸、(四)NaCl濃度，進而得知在不同條件下所得到的滲透液純水產率與NaCl的去除率。研究結果顯示，熱進料溫度和冷熱流體流量增加，NaCl的去除率及純水的生產量也會增加。薄膜孔徑的大小對於去除NaCl沒有很大影響，但它會直接影響產水率。

關鍵字

薄膜蒸餾 ； 海水淡化 ； Memstill(海水淡化荷蘭文) ； 疏水薄膜 ； 空氣間隔式薄膜蒸餾

並列摘要

The membrane distillation (MD) has recently been developed to become an important technology in desalination become it owns some advantages，such as：simple design with modularity，high level of interface area and low installation and operating costs. Membrane distillation uses the driving forces coming from and the difference of vapor pressure across the membrane and the temperature difference between the hot sea water and the cold water，which is the difference between MD and other membrane technology for separation. In MD technology，the water vapor will pass a porous hydrophobic membrane and then the water comes out after the vapor goes through the cold end.
In this study，Teflon film PTFE (Polytetrafluoroethene) air gap membrane was used in the system to distill the simulated sea water，investigate the influence of the fluid flow pattern on the flux of permeation and estimate the theoretical flux of permeation. The water temperature at the cold end was set at 25℃ and the temperature difference between the hot and cold fluid was changed to enhance the efficiency of MD and the production of pure water. Based on the air gap membrane distillation model for desalination，there were four key factors：(a).the hot fluid inlet temperature (b). the volume of fluid flow (c). the size of membrane pores (d). sodium chloride (NaCl) concentration. Which would affect the water production and NaCl removal，to be discussed in this study. The experimental results showed that both of the NaCl removal rate and the water production were be increased with the hot fluid inlet temperature and the volume of fluid flow. The size of membrane pores did not affect the removal of NaCl that much but it would affect the water production rate.

並列關鍵字

Membrane distillation(MD) ； Desalination ； Memstill ； Hydrophobic Membrane ； AGMD

參考文獻

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