OPERATING EXPERIENCE OF A LARGE MULTISTAGE FLASH EVAPORATOR IN SULTANATE OF OMAN.

The desalting plant at Ghubrah has been in operation since early 1976. The plant produces 4 mgd when operated at 90 degree C and up to 6 mgd at higher temperatures. Due to increased water demand, Belgard EV was used to allow plant operation at temperatures above 90 degree C. The plant has operated at 100 degree C with a dose rate of 3 ppm Belgard EV without causing excessive fouling. The use of Belgard EV is continuing at temperatures below 91 degree C while the dosing rate is slowly being reduced. At present a Belgard EV dose rate of 2. 5 ppm has been attained when operating at 95 degree C. The plant has been tested at a maximum brine temperature of 110 degree C using Belgard EV when production was 6 mgd. During 1980, when water demand is expected to be around 6 mgd it is planned to operate the plant at 113 degree C using Belgard EV. It is concluded that operation of the unit with Belgard EV has been satisfactory and scale formation is substantially less than when using polyphosphate additives. There is an appreciable saving in terms of chemical cost as well as plant corrosion when operating at 100 degree C using Belgard EV instead of acid dosing.