Mixer refurbishment for power station
Energy Power Resources (EPR)'s Thetford Power Station, Norfolk, UK, completed in 1999, is a 38MW station delivering 912 MW of power to the national grid every day.
However, it is not nuclear powered, neither does it burn coal or gas, the EPR power plant consumes 60 tonnes per hour of chicken litter, 420,000 tonnes per year. This makes it the biggest chicken litter powered station in the world, and the largest biomass powered station in Europe.
As a by-product, the station produces 120 tonnes per day of ash, which is blended and sold as high-quality fertiliser. John R Boone Ltd supplied a 16m3 working capacity ash-blending drum mixer to the station when it opened, and all the ash produced through the station goes through this blending drum before going to the company's fertiliser production factory off-site. Ash comes from the generation plant by screw conveyor, bucket elevator and weigh hopper to the drum blender. 12,000 L per hour of water is sprayed onto the ash through a high pressure spray lance as a dust suppressant before it is transported away. The mixing action of this large drum allows the water to quickly and thoroughly dampen the ash before discharge.
EPR has instigated a policy of giving suppliers of major pieces of equipment the responsibility of controlling and undertaking planned maintenance and refurbishment themselves.
John R Boone went back to the original drawings and proposed a refurbishment project, to take place during a planned summer shutdown, that both refurbished and developed the blender installation. After eight years of 24/7 production new inlet and outlet chutes were required, along with the complete replacement of the spray lance and valve gear. Also a new drive ring and chain were fitted to the blender body together with another access door in the side of the drum to ease cleaning.
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