Increase in efficiency and reduction of generation cost at hard coal-fired power plants: Post-combustion of combustion residues from co-firing of RDF and biomass during dry ash removal

摘要

Operators of coal-fired power plants opt for co-firing of alternative fuels in order to reduce the fuel costs and/or the emission of CO_2. The range of these alternative fuels [1] varies from untreated (pure) biogenous materials such as wood (residual wood, forest timber, plantations) energy plants, cereals, straw up to biogenous residual matter such as matured timber and farm slurry and includes also sewer gas, landfill gas, and sewage sludge. Material disposing of a reasonably high biogenous portion - processed waste (refuse-derived fuel, RDF) from the high calorific value fractions of domestic refuse, bulky waste, and commercial waste, residues from recoverable materials sorting, product-specific commercial waste, and also industrial waste -are, however, also of importance [1]. In some countries of the EU (such as e.g. Denmark, Great-Britain, Benelux, Poland) biomass combustion in utility power stations is subsidised by governments. In Great Britain, the existing hard coal-fired power plants with limited remaining service life are supposed to be redesigned for combusting 100 % wood pellets by public funds of 30 ￡ per MWh_(el) (Figure 1).