This paper presents the experimental investigations of the emissions of SO2, NO and N20 in a bench scale circulating fluidized bed combustor for coal combustion and co-firing coal and biomass. The thermal capacity of ...This paper presents the experimental investigations of the emissions of SO2, NO and N20 in a bench scale circulating fluidized bed combustor for coal combustion and co-firing coal and biomass. The thermal capacity of the combustor is 30 kW. The setup is electrically heated during startup. The infuence of the excess air, the degree of the air staging, the biomass share and the feeding position of the fuels on the emissions of SO2, NO and N2O were studied. The results showed that an increase in the biomass shares resulted in an increase of the CO concentration in the flue gas, probably due to the high volatile content of the biomass. In co-firing, the emission of SO2 increased with increasing biomass share slightly, however, non-linear increase relationship between SO2 emission and fuel sulfur content was observed. Air staging significantly decreased the NO emission without raising the SO2 level. Although the change of the fuel feeding position from riser to downer resulted in a decrease in the NO emission level, no obvious change was observed for the SO2 level. Taking the coal feeding position R as a reference, the relative NO emission could significantly decrease during co-firing coal and biomass when feeding fuel at position D and keeping the first stage stoichiometry greater than 0.95. The possible mechanisms of the sulfur and nitrogen chemistry at these conditions were discussed and the ways of simultaneous reduction of SO2, NO and N2O were proposed.展开更多
基金Project supported by the National Natural Science Foundation of China (No. 90210034, 50576101,20221603)
文摘This paper presents the experimental investigations of the emissions of SO2, NO and N20 in a bench scale circulating fluidized bed combustor for coal combustion and co-firing coal and biomass. The thermal capacity of the combustor is 30 kW. The setup is electrically heated during startup. The infuence of the excess air, the degree of the air staging, the biomass share and the feeding position of the fuels on the emissions of SO2, NO and N2O were studied. The results showed that an increase in the biomass shares resulted in an increase of the CO concentration in the flue gas, probably due to the high volatile content of the biomass. In co-firing, the emission of SO2 increased with increasing biomass share slightly, however, non-linear increase relationship between SO2 emission and fuel sulfur content was observed. Air staging significantly decreased the NO emission without raising the SO2 level. Although the change of the fuel feeding position from riser to downer resulted in a decrease in the NO emission level, no obvious change was observed for the SO2 level. Taking the coal feeding position R as a reference, the relative NO emission could significantly decrease during co-firing coal and biomass when feeding fuel at position D and keeping the first stage stoichiometry greater than 0.95. The possible mechanisms of the sulfur and nitrogen chemistry at these conditions were discussed and the ways of simultaneous reduction of SO2, NO and N2O were proposed.
文摘水动力特性及流动不稳定性的准确计算和分析,对660MW超超临界CFB锅炉水冷壁的优化设计和安全运行具有重要意义。针对我国自主开发的660 MW超超临界CFB锅炉设计方案,将其水冷壁系统等效为由流量回路、压力节点和连接管组成的流动网络系统,根据质量守恒、能量守恒和动量守恒方程建立了水动力计算数学模型,在此基础上对其4个负荷下的水动力特性进行了计算分析。同时建立了适用于超超临界锅炉流动不稳定性计算分析的一维单通道通用数值计算模型,选取25%锅炉最大连续出力(boiler maximum continue rate,BMCR)负荷下的危险回路进行了流动不稳定性的计算分析。计算结果表明,超超临界CFB锅炉水冷壁系统的总压降低于煤粉炉的压降;水冷壁流量分配呈正响应特性,4个负荷下最大的流量偏差为20.98%;最大的出口工质温度偏差出现在后墙,为8.4℃;各负荷下的壁温均处于管子材料的允许温度范围之内,不会出现高温爆管的现象;水冷壁不会发生流动不稳定性,锅炉的运行是安全可靠的。
