Simplified Freeze Desalination through Enhanced Recovery Rate and Desalination Efficiency

Document Type : Research Article

Authors

Faculty of Mechanical Engineering, Shiraz University, Shiraz, Iran

Abstract

Freeze desalination is an emerging technique since it uses much less energy than most other thermal technologies. As a portion of zero/minimum liquid discharge technologies, crystallization is being commercially used, however, it is probably the most expensive section of the desalination plant. Several freeze desalination techniques are being developed including progressive layer, falling film, suspension freeze, and gas hydrate desalination. The emphasis of most of these methods is to improve the desalination efficiency. Developing a complete freeze desalination plant requires recognizing the critical importance of both recovery rate and desalination efficiency. In a study, a comprehensive freeze desalination plant was designed with a 50% recovery rate and 50% desalination efficiency. To achieve proper salt rejection from 78% of incoming seawater, the plant needs to undergo at least 46 stages of desalination. The plant is then redesigned with the recovery rate of 90% and the desalination efficiency of 90%. It is shown that in only 6 stages of desalination, 89% of the whole seawater can be desalinated which is a cost reduction of at least 87%.

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