Multi-stage flash desalination: present and future outlook

Multi-stage flash desalination (MSF) is currently the workhorse of the desa lination industry with a market share close to 60% of the total world produ ction capacity. As the turning point of the new millennium nears, the proce ss faces many challenges dictated by industrial demands and public needs. T he conservative nature of the desalination owner, as well as the strategic characteristics of the product, makes the MSF process favored over other co mpetitive thermal desalination methods. In addition, the process has severa l merits, which include a large production capacity, proven reliability and well-developed construction and operation experience. This study offers an overview of the present and future developments in the MSF process, which aims to reduce the production cost. Special attention is given to the proce ss fundamentals, which are the key elements for any serious and physically sound development of the MSF process. Also, a summary of the novel (MSF-M) configuration is given, which has recently been proposed by the authors. Th e process is based on the modification of operational MSF plants as well as the concept of once-through MSE The modification involves removal of the h eat rejection section and the addition of a mixing tank for the feed stream and the unevaporated brine recycle. This eliminates the amount of energy r ejected in the cooling seawater stream and reduces the amount of energy rej ected in the brine blowdown stream. Analysis of the MSF-M process shows an increase in the thermal performance ratio by a factor of 2-3 over conventio nal MSE (C) 1999 Elsevier Science S.A. All rights reserved.