Drax EcoStore

Project Phoenix was Drax Power Ltd’s £240m innovative programme to convert three of its six generating units at Drax Power Station from coal to renewable, cost effective biomass material. RPS provided Lead Designer, Architecture, Civil/Structural Engineering, Building Services Engineering and Fire Engineering services for the Eco-store and biomass fuel transfer element of the project.

The biomass conversion programme depended upon the design and construction of a new fuel storage and handling facility, together with associated plant modifications to secure the maximum benefit from generating unit conversion.

The implemented solution is an innovative and complex system of fuel delivery, handling, storage and reclaim for the pelletised fuel. It is delivered to site by train and automatically unloaded as the train passes, without stopping, through a dedicated multi-level unloading building incorporating a 15m deep multi-level sheet piled basement.

The fuel is transported via a system of conveyers, supported on steel gantries up to 65m high, to a process building that screens the fuel to remove over-sized materials / contaminants and extract dust. The fuel is then conveyed to one of four 62m diameter, 50m high storage domes, each one capable of storing 135,000 tonnes of biomass fuel.

The innovative domes consist of a durable waterproof fabric, inflated and sprayed internally with a lining of polyurethane foam insulation. This is followed by steel reinforcement and a stabilising internal shell of sprayed concrete. The result is a weather-proof, condensation free and structurally strong store. As the fuel is combustible, the dome is fitted out with dust suppression and fire prevention systems.

Fuel is reclaimed from the domes via vibrating floor modules, fluidising the fuel so it drops through holes onto reclaim conveyers in to underground tunnels. The fuel is conveyed to a final sampling building before 2,800 tonnes per hour are transferred to the power station.

Issues overcome by the project team included:

A challenging design and programme

Construction on a working power station site

Incorporation of complex and innovative process equipment within tight site constraints

The inclusion of extensive fire prevention and suppression measures

Complex co-ordination of specialist designers, contractors, sub-contractors, process engineers and their designs