Development of a pressure recovery unit for seawater reverse osmosis system

• Main Author: Tan, Yu En
• Other Authors: Low Seow Chay
• Format: Theses and Dissertations
• Language: English
• Published: 2008
• Subjects: DRNTU::Engineering::Mechanical engineering::Fluid mechanics; DRNTU::Engineering::Environmental engineering::Water supply
• Online Access: https://hdl.handle.net/10356/13505
• Institution: Nanyang Technological University

As supplies of clean water diminish, increasing numbers of countries are turning to desalination to meet their water needs. Australia, for instant, is gearing up to build the largest desalination plant in the world after facing a seven-year drought from 2001-2007. Unfortunately, desalination is an energy intensive process that adds to their energy woes. To lower its energy consumption, energy recovery devices (ERDs) were invented or adapted from other industries for use in desalination plants. In general, there are two types of ERDs. The first is a turbine type ERD and the second is a positive displacement type ERD. The latter has proven to be more effective in lowering energy consumption due to higher energy transfer efficiency (ETE). In fact, industrial observers even believed that the efficiency of these ERDs has already reached a plateau. So far, the most efficient desalination plants have achieved an energy consumption of 1.9 kWh/m3 of clean water processed. This level of efficiency is more than 100% better than older designs. In the interest of design excellence, this project has identified two areas suited for further development. The first is to raise energy efficiency through the novel use of pressure exchange between the high pressure brine flow and the low pressure seawater flow. The second is to smooth out pressure fluctuations in the inlets and outlets of the ERD.