Design aspects of large sea water reverse osmosis desalination plants

Abstract

As the size of SWRO plants grow, more attention must be paid to the overall design aspects of the total plant. Some of these are simplifying and improving the pretreatment; reducing the pretreatment chemicals; systems optimization to match sea water conditions and; component size selections. The optimum conversion ratio is generally the maximum possible as limited by brine osmotic pressure and brine flow considerations. This is from 30% to 40% depending on feed temperature and pressure. An economic analysis of cooling of the feedwater is made. This was found to be beneficial for sea water temperatures over 27°C. To utilize larger single streams or “blocks” of permeators, larger high pressure pumps should be employed. These may be driven directly by medium speed diesel engines. A block size of 5 MIGD using a single H.P. pump of 2517 m 3/h (11,080 U.S. GPM) at 701m is envisioned.