ELGA Process Water, a Veolia Water Solutions & Technologies company, has supplied a two-stage membrane water purification system to E.ON’s Castleford Power Station to recover harvested rainwater for use as boiler make-up. Castleford is a 56MWe Combined Cycle Gas Turbine (CCGT) power station and its 45bar boiler needs very high purity make-up water. The new system allows the production of up to 5m3/h of “mixed bed” water quality (better than 0.2µS/cm conductivity with less than 10µg/l of silica) from rainwater rather than mains water from the old plant.
Collected rainwater is stored in a holding tank, which also has an emergency mains water connection, and then pumped to the treatment plant. The treatment process consists of reverse osmosis followed by continuous electro-deionization (CEDI), so there are no regeneration chemicals, and the Castleford plant is the first of its kind in the UK power generation industry to use this technology.
Rainwater harvesting needs rain, and the winter was particularly dry. However, during a very wet April, the site collected 100m3/day of rainwater. E.ON’s Plant Manager, Paul Gooding, looks pleased beneath his umbrella: “If this keeps up,” he smiles, “we could be completely independent of the mains water supply!”
In order to minimize site construction time and avoid a prolonged shutdown as the new plant was commissioned, ELGA Process Water built the MegaRO™ reverse osmosis and Ionpro CEDI units in a container. The plant was pre-commissioned at works then delivered to site and simply connected up to the recovered water tank and the boiler feed tank.