Comparative study of two anti-scale agents Belgard EVN and Belgard EV 2000 in multi-stage flash distillation plants in Kuwait

• Published in: Desalination 1994, Vol.97 (1), p.97-107
• Main Authors: Al-Saleh, S.A., Khan, A.R.
• Format: Article
• Language: English
• Subjects: Applied sciences; Drinking water and swimming-pool water. Desalination; Exact sciences and technology; Pollution; Water treatment and pollution
• ISSN: 0011-9164; 1873-4464
• DOI: 10.1016/0011-9164(94)00078-6

The performance of MSF distiller depends on scale formation inside the condenser tubes since scale impairs heat transfer and adversely affects the production of the main utility. In the past three decades a great deal of research activity has focussed on the development and testing of anti-scale agents. Three basic methods are commonly applied in inhibition of scale formation. The first method involves the prevention of scale deposition through pH adjustment by acid addition. The second 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 comparative performance study was carried out using two polymer-based chemicals as anti-scale agents in the two identical units of Doha East desalination plants. Both units were multi-stage flash, low temperature, cross-tubed and brine recirculation with a nominal capacity of 6.0 migdp (27,276 m 3/d). The test period was 92 days. Both distillers exhibited excellent performance and demonstrated a steady successful operation. The results of the comparative study show that Belgard EV 2000 and Belgard EVN are effective in controlling alkaline scale deposition on critical heat transfer surfaces of the evaporators. The results show a remarkable improvement in heater overall heat transfer coefficient, reducing significantly the heater fouling factor, increasing the Gained Output Ratio (GOR) and Performance Ratio (PR) values, maintaining the distillate production and steam consumption. Belgard EV 2000 showed better performance and was slightly more effective than Belgard EVN. The results of Belgard EV 2000 show an insignificant difference in the values of Overall H.T. coefficient and fouling factor of heat gain section.