Behavior of a reverse osmosis plant adopting a brine conversion two-stage process and its computer simulation

A new scheme of reverse osmosis seawater desalination, which is called a br ine conversion two-stage process, has been proposed by Toray Industries. In this process, a second-stage is added to a conventional RO unit, and the c oncentrated brine from the unit is further desalinated at the second-stage to increase the water recovery ratio over 40 up to 60%. The recovered energ y from the first-stage brine is used to pump the feed to the second-stage u p to approximately 10 MPa. For this purpose, a new membrane, UTC-80BCM, has been developed besides a conventional UTC-80. A test plant based on this s cheme (210 m(3)/day) was built at Ehime factory, Toray, Inc. and was run un der a wide range of operation conditions. In this paper, the results of these membrane properties and the mass transf er coefficients of each spiral-type element are reported. Using these data, we found that a computer program, which was developed previously, could si mulate the behavior of the new scheme, when appropriate temperature and pre ssure corrections were adopted. (C) 2001 Elsevier Science B.V. All rights r eserved.