Technical aspects of reducing desalting water cost by distillation methods

In Kuwait, the installed capacity of desalting plants is continuously increasing (from 1 mgd in 1953 to 263 mgd in 1989) as well as the water consumption per capita (from 57 1/d in late fifties to 272 1/s in mid eighties). Any decrease in the desalted water unit costs means saving millions of KD to Kuwait due to the huge amounts of desalted water production. In this paper, prospects of the present and near future improvements in desalination technologies by distillation processes that may effect the desalted water unit cost are discussed. These prospects include the capital cost (i.e., equipment, site, etc.) and running costs (i.e., energy, chemicals, etc.) of the main distillation systems such as multi-stage flash (MSF), multi-effect boiling (MEB), and vapor compression (VC) systems. The effects of the design and operating parameters that have impact on the cost are outlined, as well as the practical constrains imposed on these parameters. These parameters include maximum brine temperatures, Type of water treatment, number of stages or effects, means of supplying energy, material selection, etc. Case studies are reviewed where designs, different than conventional designs, were adopted with the hope to decrease the cost.