Energetic aspects of the fouling of MSF desalination plants with and without the use of on load ball cleaning system

Abstract

Multi-stage flash (MSF) desalination plants are designed with specific permissible fouling factors. When these conditions are met, the performance is said to “meet design”. With single- purpose desalinators, fouling of the brine heater can be compensated for by increasing the steam pressure without substantial increase of heat consumption and within the limits of the boiler pressure. With dual-purpose desalinators, the brine heater pressure will influence the efficiency of the turbine process. Fouling of the heat recovery section increases the heat consumption of the MSF process. The distillate production can be maintained within the limits of the boiler. Typical “design fouling factors” have been compiled from literature. The influence of fouling factor on specific heat consumption has been calculated for typical MSF design conceptions, as well as the increase of water costs per m3 with different fuel prices. The costs of various scale prevention methods have been evaluated. The effectiveness of such countermeasures can be quantified by plant experience. This analysis of cost/return gives a basis for a correct economic comparison.