Demineralisation is a technique used to eliminate mineral salts from water utilising the process of ion exchange. Most natural water sources can be demineralised to produce water of high quality as compared to other methods of purification.

Demineralised water is also called deionized water. Mineral ions such as cations of sodium, calcium, iron, copper and anions of chloride, sulphate, and nitrate that are commonly present in water are removed during demineralisation. The process is physical in nature and occurs quickly without scale in the build-up.

Using demineralisation technology improves the flow of water tremendously. Systems of demineralising water find wide application in fields of power, process, cooling, and steam.

Demineralisation of water takes place in demineralisation plants which are available in different sizes and materials and can be manual or automatically operated. The plants are built to conserve water and to save costs. Thermax is among the top manufacturer in India that makes such water purification systems. The plants they provide are ready to install and can even be custom made for specific needs.

Principle

In a DM plant, water is allowed to flow through two small polystyrene bead-filled beds. Here the cations are exchanged with hydrogen ions in the first bed, and the anions are exchanged with hydroxyl ions in the second one.

Process

Ion-exchange is a rapid and reversible process in the context of water purification. Impure ions present in the water are replaced by ions which are released by an ion-exchange resin. This resin takes up the impure ions. This resin is periodically regenerated to restore it to its original ionic form.

Operating Principle

A Typical two-bed demineralised water plant consists of rubber lined pressure vessels that are connected in a series with other internal fittings. The first unit has a high capacity strongly acidic cation exchange resin. This converts positive ions of salt and replaces them with hydrogen ions to form respective acids. These acids are absorbed in the next vessel by an anion exchange resin that is strongly basic. he water obtained by this process shows conductivity less than 20 µ S / cm at 250 C and total dissolved solids less than 10 ppm.

Mixed bed de-mineralisers are used on the downstream of the DM unit to achieve high purity levels in the treated water. These mixed bed units contain a single vessel with a mixture of cation and anion resins.

Demineralisation plants offered by Thermax are in demand across a number of industries. Visit https://www.thermaxglobal.com/ to know more about these and choose a high-quality plant for your facility.