Co-gasification And Co-firing Characteristics Of Municipal Waste On CFB

Li Zhiwei (Engineering Thermophysics) Directed by Professor Lu QinggangIncineration and gasification of municipal waste were investigated in a 0. ISMWth circulating fluidized bed combustor/gasifier (CFBC/G). The furnace is 6000mm in height and 300mm in inner diameter, and it is made of high temperature alloy covered with heat insulation material on the outside. The temperature of the test system was maintained by the combustion of the waste and the auxiliary fuel. The investigation was made on co-firing of municipal solid waste (MSW, collected in Beijing city) and coal, co-firing and co-gasification of sewage sludge with coal and PE.The MSW and sewage sludge can be successfully disposed through incineration or gasification in CFB under certain temperatures with energy recycling, weight and volume reduction.Co-firing MSW with coals meets the requirement of "3T", with low emission of PCDDs/Fs, with I-TEQ less than l.Ong/m3. SO2 concentration in the gas decreases significantly with the increase of co-firing rates, and HC1 concentration in the gas does not rise when co-firing rates increase. Increase in co-firing rates leads to the reduction of conversion ratios of fuel-S to SO2 and fuel-Cl to HC1. With the co-firing rate of 50%, the SO2 concentration in the flue gas is about 0 and the conversion ratio of chlorine to HC1 is lower than 50%. In addition, HC1 in flue gas promotes the absorption of SO2 by CaO.Nitrogen content in the municipal waste is higher than that in the coal and in the PE, and an increase in co-firing rates leads; to the rise of those concentrations of N2O and NO in the flue gas. In the experiments. NO concentration in the flue gas increases with higher co-firing rates, but N2O concentration decreasesAn increase in furnace temperature; leads to signaficiant reduction in N2O emission, but does not lead to higher NO emission.During co-firing and co-gasification of Datong bituminous and sewage sludge,an increase in the equivalent ratio of air to fuel leads to decrease of N2O emission anddecrease of conversion ratio of fuel-N to N2O, but leads to higher NO emission andhigher conversion ratio of fuel-N to NO, and higher conversion ratio of sulfur to S02.Under reduction condition, some sulfur is converted to E^S.