27 Apr 2016
Power stations that generate electricity consume very large amounts of water. Other than raw cooling water, most of the water consumed requires treatment of some form. Ion exchange resins employed in a Make up Water Treatment Plant (MUWTP) are initially used to produce ultra pure water from raw water often obtained from a standard domestic water supplies or bore holes. Each day a typical MUWTP produces around one hundred cubic meters every hour to a conductivity of 0.06 μS cm-1. Both weak and strong acid cation resins and strong and weak base anion resins are exclusively used to remove all impurities from the source water. The weak acid cation resin removes a large proportion of the cationic species, for example, Iron, Fe2+,Fe3+ with a strong acid cation removing the remainder. Weak and strong base anion resins follow to remove the anionic impurities in the same way, for example, Silica, SiO2. The benefit of this configuration is that the regeneration of the resins is a highly efficient process with the regenerant from the strong resins being sufficient to regenerate the weak ones too.
The product of the water treatment plant is stored in large tanks and is available for boiler feed system make up and other uses. The feed system water, with make up, is recirculated within the feed system and in this respect is recycled continually. However, the feed water quality monitoring systems and other system losses require a continuous feed from the make up system.
As the feed water is recirculated any impurity pick up arising from a small ingress of during normal plant operation needs to be quickly and efficiently removed. An in-line Condensate Polishing Plant (CPP) uses strong acid cation and strong base anion resins for this purpose. These resins must be in peak performance in order to process the volume of fast flowing water (typically around 400 kg s-1) arising from normal operation.
Essentially, ion exchange resins provide a cost effective and efficient method for creating and maintaining a continual supply of ultra-pure water which is in essence the life blood of the power generation industry.
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