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According to the Rules of technical operation of electric power stations and networks (RTO) type of duty of water treatment plants and water-chemical conditions should ensure the work of power stations and heating system manufacturers without damage and reduce the efficiency caused by corrosion of internal surfaces of water treatment, heat-and-power and network equipment, as well as without scaling and deposits on heat exchange surfaces, deposits in the setting of turbines, slurry in equipment, pipelines of power stations and heating systems.

The ion-exchange method of water and condensate treatment is implemented in the following ion-exchange bed filters:

FIPa I: primary ion-exchange parallel-flow filters;
FIPa II: secondary ion-exchange parallel-flow filters;
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This process is applied to soften the water by filtering it through the Na-cation exchange resin layer. During this process Ca2+ and Mg2+ ions causing the hardness of incoming water (hereinafter referred to as the hardness ions) are kept by cation-exchange resin and replaced with the equivalent number of Na2+ ions.

OH-anion exchange of water is performed in order to exchange removed anions for hydroxide ions. Due to the combination of OH-anion exchange and Н-cation exchange, anions as well as cations are removed and exchanged for (OH-) and (H+) ions, in other words, chemical (ion-exchange) water demineralization takes place.

Water treatment includes two main processes applied for removal of ionized impurities from water: cation exchange and anion exchange. Depending on exchangeable ion the following processes and vessels are distinguished: Na-cation exchange, Na-cation exchange filter; H-cation exchange, H-cation exchange filter; OH-anion exchange, OH-anion exchange filter.

Water treatment by means of H-cation exchange is intended for removal of all cations from the water and their exchange for hydrogen ions. Water downstream the H-cation filters contains excess of H ions, and as a result has acidic reaction, that's why this technology is used along with other ion-exchange processes - Na-cation exchange and anion exchange.

The quality of ion-exchange resins is characterized by the number of physical and chemical properties that determine effectiveness and cost-efficiency of the ion exchange methods. The main physical properties include: grain-size distribution, bulk mass, mechanical strength, and osmotic stability, resin structure and swelling index in the aqueous solutions.

The use of water heat and power engineering

Description of the ion-exchange unit of water treatment plants

Na-cation exchange

OH-anion exchange of water

Ion exchange process

H-cation exchange

Process characteristics of the ion-exchange resins