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采用木屑、谷壳和干污泥等3种生物燃料作为再燃燃料,在一台93 kW的燃煤单角炉上进行了生物燃料再燃降低燃煤过程中NO排放的实验,研究再燃燃料种类、再燃燃料载气、再燃燃料比例等各种关键因素对NO还原率的影响,同时对再燃区内的NO、O2、CH4、HCN和NH3等关键气体组分浓度分布进行了测量。实验结果表明:生物燃料再燃能有效降低NO排放,实验条件下,木屑再燃NO还原率最大达到了64%,谷壳达到了55%,污泥达到了43%;循环烟气作为生物燃料载气时NO还原率比空气作为载气时至少提高了10%以上。炉内测量结果表明,对于木屑和谷壳再燃过程,测量得到的含氮中间物质主要是HCN,而对于污泥再燃过程,含氮中间物质以NH3为主。生物燃料再燃过程中再燃区内的O2、CH4、HCN、NH3等关键气体组分的形成和浓度分布特性与NO浓度分布特性表现出了极大的相关性,对NO还原和提高生物燃料再燃过程NO还原率起到了关键作用。
Using three types of biofuels, such as sawdust, chaff and dry sludge, as reburning fuel, experiments were conducted on a 93 kW coal fired single angle combustor to reduce NO emissions from coal combustion and to study the types of reburning fuel, Re-ignited fuel carrier gas, and the proportion of reburning fuel on the NO reduction rate. At the same time, the concentrations of NO, O2, CH4, HCN and NH3 in the reburning zone were measured. The experimental results show that the reburning of biofuels can effectively reduce the NO emission. Under the experimental conditions, the maximum reduction rate of sawdust reburning NO reached 64%, the chaff reached 55% and the sludge reached 43%. As a biogas carrier gas, When the NO reduction rate than the air as a carrier gas increased by at least 10%. The results of in-furnace measurements show that for the woodchip and chaff reburning process, the measured nitrogen-containing intermediate substances are mainly HCN, while for the reburning process of the sludge, the nitrogen-containing intermediate substance is dominated by NH3. The formation and concentration distribution of the key gas components such as O2, CH4, HCN and NH3 in the reburning zone during the reburning process of biofuel showed a great correlation with the distribution characteristics of NO concentration. The reduction of NO and the improvement of reburning process of biofuel NO reduction rate played a key role.