Deionisers help reduce silica at Veolia Environmental Services, UK

Make-up water for the boiler is produced in an on-site ion exchange demineralisation plant consisting of cation exchanger, anion exchanger and mixed bed polishing to meet the 0.1µS/cm conductivity and 20µg/l silica. Silica in the make-up water can cause major problems, not only expensive damage to the turbine but increased blowdown frequency which consumes large volumes of water and wastes heat energy. Neil Clark, Maintenance Manager for Veolia Environmental Services, regularly uses Veolia Water Technology’s AQUAMOVE mobile solutions for support during outages and planned maintenance of the on-site plant. So, when the plant started to leak silica, he turned to Veolia for advice.

Veolia Water Technology’s solution was to provide three 10m3 /h IHF mixed bed deionisers to polish the water from the demin plant to reduce silica to an acceptable level. The units operate as two duty and a standby, this configuration ensures a reliable and continuous supply of pure water. A water quality meter has been installed to monitor the treated water, for added peace of mind. The ionic load on to the IHF units is very low, so regeneration is infrequent. When exhausted they are returned to Veolia Water Technology’s central regeneration station in exchange for a regenerated unit.

• Continuous secure supply of make-up water
• Low silica levels and conductivity
• Reduced boiler blowdown and associated chemical usage