Verbrennung und Vergasung in Wirbelschichtanlagen : Stand, Entwicklung und Forschungsbedarf

Fluidized bed combustion systems can meet current emission limits without any secondary flue gas cleaning. Circulating fluidized bed combustion is superior to bubbling fluidized bed and is the dominating technology today. Fluidized bed combustion systems can be designed for a variety of fuels and mixes, i.e. high ash bituminous coals, high sulfur brown coals, peat, wood and sludges. Current activities focus on increasing the capacity and a compact design. Utilization of ash residues is not yet completely solved. Operational problems are specific for the used fuel. Atmospheric fluidized bed gasifiers have been developed in recent years and are demonstrated in large scale for fuels like biomass and wastes. The produced gas can be utilized in conventional pulverized coal firing or for example in cement kilns. The development of pressurized fluidized bed combustion allows the utilization of solid fuels in combined cycles and offers the advantage of high efficiencies. Both gasification and combustion under pressure have been developed and demonstrated in large scale. Pressurized bubbling fluidized bed combustion units are offered commercially with capacities up to 800 MWth. Although circulating systems are of advantage under pressure as well, they are less developed. Further efforts concentrate on increased gas turbine inlet temperatures by combination of combustion and gasification (2(nd) Generation PFBC).