EXERGY ANALYSIS OF MAJOR RECIRCULATING MULTISTAGE FLASH DESALTING PLANTS IN SAUDI-ARABIA

A simple and auspicious scheme to estimate exergy losses in multi-stag e flash (MSF) plants is described. This method is used to evaluate maj or MSF plants in Saudi Arabia, namely, Al-Khobar II, Al-Jubail II, and Shuaibah. This study presents a quantitative assessment of the exergy losses, exergetic efficiency, and exergy-destruction term for each pl ant. The effect of these terms on the performance of the three MSF pla nts when operating at various top brine temperature (load conditions) is also investigated. The results obtained for the three plants show t hat the three MSF desalting plants are highly irreversible with exerge tic efficiencies ranging from 1.12-10.38%. The associated total exergy destruction is found to range from 6.75-26.16% MW, with the exergy-de struction term epsilon ranging from 40.52-77.96 kJ/kg. The exergetic e fficiency of brine heaters, when calculated separately, ranges from 72 .20-87.98%, with exergy losses of 1.20-5.42 MW. The study concludes th at the top brine temperature (TBT) is directly proportional to the exe rgy losses in the MSF plants.