Hybrid desalting systems - a new alternative

Abstract

Currently, most large scale seawater desalting complexes are dual-purpose power/MSF plants. These plants produce high purity distilled water and also provide excess electrical power for sale at a typical ratio of 10 MW power per 1 MGD of water. In the simple integrated hybrid MSF/RO desalination power process, a seawater RO plant is combined with either a new or existing dual purpose MSF/power plant with the following advantages: • A common, considerably smaller seawater intake can be used. • Product waters from the RO amd MSF plants are blended to obtain suitable product water quality. • A single stage RO process can be used. • The RO membrane life can be extended. • Excess power production from the desalting complex can be reduced significantly. The fully integrated MSF/RO desalination power process which is particularly suitable for new seawater desalting complexes, takes additional advantage of integration features, such as: • The feedwater temperature to the RO plant is optimized and controlled by using cooling water from the heat eject section of the MSF plant. • The low pressure steam from the MSF plant is used to deaerate the feed water to the RO plant to minimize corrosion and reduce residual chlorine. • A common post treatment is used for the product water from both plants. • The brine discharge from the RO plant is combined with the brine recycle in the MSF plant. Further integration can be done with the use of vapor compression evaporation which consumes additional electrical power and which can be made to operate very efficiently by utilizing waste heat to preheat the feed water.