Prospects of improving energy consumption of the multi-stage flash distillation process

The multi-stage flash (MSF) distillation process in the Arab Gulf Region is superceding other conventional desalting processes. Although the MSF process was introduced more than forty years ago, the development of the process has been evolutionary rather than revolutionary. Research and development efforts were mainly directed towards the control of scale formation on heat transfer tubes by developments and dose rate optimization of scale inhibiting chemicals and adoption of on-line sponge ball cleaning. Other areas of R&D are selection of appropriate construction materials, increase of unit capacity and improvements of the quality and variety of control and instrumentation. The MSF process is an energy intensive process that is associated with high irreversibility. Although coupling the water production with power generation in a dual purpose arrangement reduces the specific fuel energy consumption for water production to around 60 kWh/m3 which is 50 percent less than that required by single purpose water production desalting plant, it is still much larger than that required by an ideal reversible desalination process. The specific energy consumption of the MSF process can be reduced either by the use of innovative modifications in conventional power cycles and/or by reducing the irreversibility of the MSF process through the improvements in the design and operating features of the distiller. Accumulated design and operating experiences of the MSF process are effectively utilized for the quest of an improved process design and operation. MSF configuration