A bench-scale evaluation of scale inhibitors in multistage flash evaporation plants under high-temperature operation mode.

Seawater desalination is currently considered a vital and dependable water resource to meet all requirements of fresh water. Kuwait has been a leading country in fresh water production from the sea using the multistage flash (MSF) unit. All MSF plants in Kuwait are operated on the principle of chemical additives dosing for scale inhibition, and at a top brine temperature below 120°C. This is because calcium sulfate scaling phenomenon usually occurs when the temperature is higher than 120°C. This type of scaling is a hard scale that cannot be removed easily by chemical or mechanical cleaning. Until recent years, no antiscalants could overcome this type of scaling at high temperatures. The new generation of antiscalants is able to stand high operation temperature without hydrolysis or without losing their reactivity and can solve sulfate scaling problem. This paper consists of laboratory tests to evaluate the performance of new inhibitors that can overcome sulfate scaling. In particular, experiments were conducted to study the antiscalants effectiveness under different operating conditions with different brine concentration, especially in high-temperature operation mode. The result of the experiment showed that the performance of these chemical additives varied with the operating temperature, flow rate, and the brine concentration. The tested chemicals showed reduction in the percentage precipitation at high temperature up to 160°C. A techno-economic feasibility study was also conducted. [ABSTRACT FROM AUTHOR]