Experimental Study And Chemcal Kinetics Molding Of Advanced Pulverized Coal Reburning No Reduction

Nitrogen oxide (NOx) from coal-fired boiler is one of the major pollutants in the atmosphere. With the gradual increase of environmental requirements, coal-fired power station flue gas denitration is imminent that low-cost and efficient denitration technology is in urgent need. Advanced reburning technology which is the combination of reburning and SNCR technology has important technical superiority and an economic advantage, and it is expected that China will adopt as a mainstream technology to control the NOx emissions from coal-fired power stations.First, by conducting experiments on pulverized coal reburning in a Two-staged Drop Tube Reactor, SNCR and advanced pulverized coal reburning NO reduction, a study was carried out on the effects of the stoichiometric ratio of reburn zone(SR), reburning fule proportion(RFP), reburning zone temperature(T1),NH3/NO molar ratio(NSR) and the residence time(τ) on advanced pulverized coal reburning. Afterwards, analysis was completed on the effects of reburning zone exit conditions of the reaction system on the downstream NOx reduction reaction.The results showed that: considering as a whole, it is more suitable for advanced reburning NO reduction total when SR=0.8 or so; when SR=0~0.6, the advanced reburning NO reduction efficiency of RFP=25% is the highest; when SR=0.8~1.2, advanced reburning NO reduction efficiency of RFP=15% is the highest. There is an optimal ratio value on reburning fuel and reductant inputs of nitrogen, under the circumstance that T1=1250℃, T2=900℃, when RFP=20%, NSR=1, the efficiency of advanced reburning NO reduction is the highest; when RFP=10%, NSR=1.5, the efficiency of advanced reburning NO reduction is the highest; the best value for T1of advanced reburning is 1100℃; NO, NH3, CH4, CO , HCN of reburning section exports are the main gas component which have effect on advanced reburning NO reduction efficiency. The research showed that, CH4, CO and HCN all help to promote NO reduction in advanced reburning process. Among the three kinds of gases, CH4 and HCN have the greatest impact on advanced reburning while the impact of CO is relatively insignificant.In this paper, the existing reburning and SNCR reaction mechanism are integrated and we employ the Chemkin software to build chemical kinetics model and to simulate the same phase reaction process of advanced pulverized coal reburning. The test results and simulation results were compared to verify the accuracy and availability of integrated mechanism. Finally, the impacts of important elementary reactions and important reactants on NO reduction are studied by rate of production analysis and the NO reduction processes are described by the normalized rate of production. NO reduction paths of advanced reburning reactions are given and compared with the existing NO reduction paths of reburning, SNCR reaction. The results showed that: advanced reburning NO reduction reaction is amidogen-oriented and reburning fuel plays an important role in the reduction reaction. In the three NO reduction reactions, the work substances, the important intermediate products and the important active groups all make some changes, while NH2 is a common important intermediate products, and the OH is an common important active groups in the three processes.