Castleford has a single General Electric LM6000PD 43MWe gas turbine exhausting via a bypass stack into a waste heat recovery boiler. The boiler produces steam to drive a 13MWe condensing steam turbine with steam extraction to provide additional operational flexibility by meeting variations in steam loads and the capacity for additional electricity generation.
Veolia Water Technologies’s solution was a two-stage membrane water purification system with a capacity to produce up to 5m3/h of high purity water. The treatment process consists of reverse osmosis followed by continuous electro-deionisation (CEDI). In reverse osmosis, water is passed through a semi-permeable membrane which removes around 97% of the dissolved salts.
Surface run-off and process wastewater which previously had to be treated and discharged to sewer is now recycled to produce demineralised boiler make-up water. This means that Castleford is largely self sufficient for process water.
It also improves the plant’s environmental footprint, minimising the consumption of mains water, eliminating the old ion exchange demineralisation plant with its regeneration chemicals and reducing effluent discharge. It also makes economic sense. The savings accrued by these reductions means that E.ON anticipates a payback within three years.
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