Power plant residual heat for seawater desalination

The paper describes the results of a feasibility study jointly promoted by Israel Electricity Corporation and Aster – Sowit Division (Italy) aimed at investigation of the possible integration of the low-temperature flash (LTF) desalination technology in existing IEC power stations. The LTF technology exploits the residual heat discharged by the cooling seawater for its distillation, with a dramatic reduction in steam consumption as compared to other distillation processes. A prototype LTF desalination unit has been operating at ENEL power station in Piombino, Italy since 1993, showing the industrial applicability of this technology. In the present study an improved LTF design, with long tube, multistage evaporator, has been applied to a typical IEC site located on the southern shore of the Mediterranean Sea. The study has been carried out both for small-scale units, devoted to boiler make-up production, and for a large plant able to produce the whole water supply for the site. The investigation has shown very interesting perspectives for such an application, with extremely low steam and electrical consumption and a very competitive cost of produced water. Other advantages of LTF technology are related to the extreme plant availability, to the high purity of produced distillate, to the absence of any chemicals consumption and environmental impact.

The study has shown that the LTF desalination technology is a viable solution both from technical and economical point of view, and can be effectively installed in steam power station located on the Mediterranean shore and operating at base load with a minimum seawater temperature increase of 8°C.