Technical Aspects of Reducing Desalting Water Costs in Distillation Methods

Abstract

In Kuwait, the installed capacity of desalting plants has steadily increased [from 1 migd (million imperial gallons per day) in 1953 to 254 migd in 1989] and the water consumption per capita risen (from 57 l/day in the late fifties to 272 l/day in the mid eighties). Any decrease in the desalted water unit cost thus means the saving of millions of KD. In this paper, prospects of improvements in desalination technologies by distillation processes that may affect 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 (ME), and vapor compression (VC) systems. The effects of the design and operating parameters that have impact on the costs are outlined as well as the practical constraints 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 non-conventional designs have been adopted with the hope of decreasing cost.