COMPARATIVE-STUDY OF 2 ANTI-SCALE AGENTS BELGARD-EVN AND BELGARD-EV-2000 IN MULTISTAGE FLASH DISTILLATION PLANTS IN KUWAIT

The performance of MSF distiller depends on scale formation inside the condenser tubes since scale impairs heat transfer and adversely affec ts the production of the main utility. In the past three decades a gre at deal of research activity has focussed on the development and testi ng of anti-scale agents. Three basic methods are commonly applied in i nhibition of scale formation. The first method involves the prevention of scale deposition through pH adjustment by acid addition. The secon d method controls scale precipitation through the addition of special chemicals either alone or coupled with sponge ball cleaning. The third method is a combination of additive and acid addition. In 1988, a com parative performance study was carried out using two polymer-based che micals as anti-scale agents in the two identical units of Doha East de salination plants. Both units were multi-stage flash, low temperature, cross-tubed and brine recirculation with a nominal capacity of 6.0 mi gdp (27,276 m(3)/d). The test period was 92 days. Both distillers exhi bited excellent performance and demonstrated a steady successful opera tion. The results of the comparative study show that Belgard EV 2000 a nd Belgard EVN are effective in controlling alkaline scale deposition on critical heat transfer surfaces of the evaporators. The results sho w a remarkable improvement in heater overall heat transfer coefficient , reducing significantly the heater fouling factor, increasing the Gai ned Output Ratio (GOR) and Performance Ratio (PR) values, maintaining the distillate production and steam consumption. Belgard EV 2000 showe d better performance and was slightly more effective than Belgard EVN. The results of Belgard EV 2000 show an insignificant difference in th e values of Overall H.T. coefficient and fouling factor of heat gain s ection.