Demineralisation plant for multi-fuel power station

The station can generate 68MW of low carbon electricity using a range of fuels including municipal solid waste, commercial and industrial waste and waste wood.

In March, following a 12 month proving trial, the make-up water treatment plant was handed over on schedule to main contractor Hitachi Zosen Inova.

The bespoke engineered plant was designed to treat a blend of borehole and towns mains water. It consists of two streams, each capable of producing up to 8m3/h of high purity demineralised water, which can operate as duty/standby. Each stream has duplex softeners and a MegaRO reverse osmosis unit followed by CEDI-VNX continuous electro-deionisation and final non-regenerable mixed bed polishers charged with nuclear grade resin to meet the treated water specification of conductivity <0.1µS/cm, silica <5µg/kg and dissolved organic carbon (DOC) <0.1µg/kg.

A mobile rig allows in situ cleaning of the RO membranes. The plant is skid mounted, factory tested and is fully compliant with Hitachi’s specifications. It is controlled by a motor control centre with a process control section using a Siemens S7-300 PLC which interfaces, via a Profibus DP communication link, with the site DCS.