Additive scale control optimization and operation modes

Abstract

Along the Gulf Coast there are three Saudi main desalination sites. These are, South to North, Al-Khobar, Al-Jubail and Al-Khafji. In these plants some 300 MIGD of distillate could be produced when all 58 MSF evaporators are run at a low top brine temperature (TBT) of 90°C. An additional 50 MIGD could be produced when the 52 evaporators designed as well, for high TBT of 113°C or more are run near this temperature. All these 58 evaporators are designed with additive scale control. Therefore additive treatment and cost are vital to East Coast Saudi Arabian plants. This paper will review original design operating parameters and performance. It will also report on some revisions reviewed or developed and executed at these plants. The changes were developed and adopted in an attempt to optimize production cost particularly scale control additive dose levels at different top temperatures. These plants were designed and undergone performance and trial runs at additive dose levels of 12 to 3 ppm. These were then reduced after the warranty periods to extremely low values of 2.2 to 0.8 ppm at different top temperatures.