An optimal high recovery, energy efficient dual fully integrated nanofiltration seawater reverse osmosis desalination process and equipment

摘要

An optimal seawater reverse osmosis (SWRO) desalination process is disclosed, which combines two or more substantially different water pretreatment processes in a unique manner and in a special configuration, hereto unknown to prior desalination arts, to produce a high yield of high quality fresh water, including potable water. In this process a two stage NF membrane pretreatment unit (NF2) with an energy recovery turbo charger (TC) device in between the stages is synergistically combined with at least one of two stage SWRO (SWRO2) desalination unit with an energy recovery TC in between the stages to form a dual hybrid of NF2 - SWRO2 or alternatively the two stage NF2 unit is synergistically combined with one stage SWRO unit utilizing high pressure tolerance SWRO membranes (up to 85 bar) with an energy recovery turbocharger in between the membranes assembly and high pressure pump or pressure exchanger (PX) energy recovery system. In a third arrangement the two stage NF unit is synergetically combined with one stage SWRO unit and with part of the SWRO reject recycles part of the SWRO reject as feed to the NF units. The SWRO unit itself is equipped with energy recovery TC or PX system which not only allows for lowering of energy consumption, but also the delivery of recycled SWRO reject, and blending it with seawater feed to the NF unit. In term of energy saving, the use of PX energy recovery system is much superior to that of TC by about 20 to 29%.