A full decade of operating experience on Al-Khobar-II multi-stage flash (MSF) evaporators (1982–1992)

• Published in: Desalination 1994, Vol.96 (1), p.313-323
• Main Authors: Al-Sofi, Mohammad Abdul-Kareem, Al-Hussain, Mohammad Abdullah, Al-Omran, Adnan Abdul-Aziz, Farran, Khalil Mahmood
• Format: Article
• Language: English
• ISSN: 0011-9164; 1873-4464
• DOI: 10.1016/0011-9164(94)85182-4

The Saline Water Conversion Corporation (SWCC) has been operating multi-stage flash evaporators in Saudi Arabia for the last 23 years. Along the Gulf coast first medium capacity MSF's (3 × 2.5 mgd) were commissioned in 1973 as Al-Khobar Phase-I [1]. About 9 years later ten MSF's were commissioned in 1982 as Al-Khobar Phase-II (AK-II) [2]. This paper will discuss experiences gained at this site by the authors, since they were involved (at various capacities and levels) in AK-II from the days of its design and construction up to the present time. This paper makes some general observations and sets some guidelines for future design, operation and maintenance of the MSF process. AK-II evaporators were designed by SIDEM of France. Most specific design uniqueness of these ten units lies in their limited number of stages when compared to other designs (16 vs 19–24). As per design, maximum TBT was set at 115°C for a maximum output of 1.34 times the nominal capacity of 5 migd at TBT of 90°C with summer seawater temperature of 35°C. It was established that surplus surface areas, be it of heat transfer or demister, were facilitating for the desired level of production per unit at a TBT of not more than 112°C. Through optimization trials it was found that antiscalants market could not provide a grade suitable for safe and prolonged operation at TBT of more than 108°C at this site. Consequently, high temperature operation were restricted to the bare minimum with a TBT limit of 105°C. It was established that excellent design with proper and closely monitored operation plus thorough inspection and timely maintenance can lead to prolonged successful operation of MSF.