Christchurch City Council

CWTP Biogas Storage Upgrade (Advance Notice)

The following scope of works will form the CWTP Biogas upgrade project:
• Removal and replacement of all biogas collection pipework with appropriate materials and improved design to avoid digester relief valve lifting and to minimise drainage points and minimise hazardous areas.
• Modification of flare control to be able to operate in pressure control mode as well as level control mode. Review backup candle flares to consider the required future flows when the high efficiency flare is out of service.
• Installation of a low pressure effluent water spray scrubber to provide cooling, condensate removal and cleaning of biogas before going to consumers.
• Modifications to Flare knockout to remove underground pumps, hazardous areas and provide knockout before candle flares.
• Installation of gas storage membrane to improve gas mixing, minimise flaring and allow consumers more flexibility.
• Install centralised biogas blowers to remove multiple hazardous areas from the plant, improve blower availability and reduce distribution pipework sizes.
• Install biogas drier to provide water dewpoint suppression to reduce opex and allow surplus biogas to be used in the BEC drier plant to back out wood pellet and supplement biogas.
• Relocation of the BHR heaters and or install new compliant pipeline to BHR.
• Deconstruction of all redundant pipework and equipment
• Process automation of Digesters 1 – 6
• Implementation of a wider scope of automation across the new Biogas Upgrades.