A&U Energie in Wielsbeke received a cost-efficient CHP plant with Dieffenbacher Energy as the EPC. Low emissions and low operating costs are achieved with bubbling fluidized bed technology. The boiler accommodates a variety of fuels. With a maximum fuel heat input of 90 MW, the plant uses waste wood classes A1–A4 (according to the German Waste Wood Ordinance). To allow the plant operator to adapt to fuel prices and availability, the boiler can also be fired with up to 50% wood dust, which is injected into the fluidized bed via a pneumatic conveying system.
The live steam is expanded via a condensing steam turbine that generates 20 MW of electrical power. Via an extraction port, up to 32 t/h extraction steam is directed to a secondary steam generator, which produces up to 31 t/h of process steam and hot water for a food manufacturer. The turbine’s exhaust steam is condensed in an air-cooled condenser.
Due to the low NOₓ emissions of the bubbling fluidized bed combustion, the strict NOₓ emission limits can be met using an SNCR system only. The plant is a “zero wastewater plant,” meaning that all wastewater generated is reused within the power plant process, so under normal operation, no wastewater needs to be discharged into the sewer system. To optimize disposal costs, the ash fractions from the boiler, pre-separator, and fabric filter are collected and stored separately.