Experiment and mechanism investigation on advanced reburning for NO(x) reduction: influence of CO and temperature.
Pulverized coal reburning, ammonia injection and advanced reburning in a pilot scale drop tube furnace were investigated. Premix of petroleum gas, air and NH3 were burned in a porous gas burner to generate the needed flue gas. Four kinds of pulverized coal were fed as reburning fuel at constant rate of 1g/min. The coal reburning process parameters including 15% approximately 25% reburn heat input, temperature range from 1100 degrees C to 1400 degrees C and also the carbon in fly ash, coal fineness, reburn zone stoichiometric ratio, etc. were investigated. On the condition of 25% reburn heat input, maximum of 47% NO reduction with Yanzhou coal was obtained by pure coal reburning. Optimal temperature for reburning is about 1300 degrees C and fuel-rich stoichiometric ratio is essential; coal fineness can slightly enhance the reburning ability. The temperature window for ammonia injection is about 700 degrees C approximately 1100 degrees C. CO can improve the NH3 ability at lower temperature. During advanced reburning, 72.9% NO reduction was measured. To achieve more than 70% NO reduction, Selective Non-catalytic NO(x) Reduction (SNCR) should need NH3/NO stoichiometric ratio larger than 5, while advanced reburning only uses common dose of ammonia as in conventional SNCR technology. Mechanism study shows the oxidization of CO can improve the decomposition of H2O, which will rich the radical pools igniting the whole reactions at lower temperatures.
Wang
Zhi-Hua
ZH
Clean Energy & Environment Engineering Key Laboratory of Ministry of Education, Zhejiang University, Hangzhou 310027, China wangzh@sun.zju.edu.cn
Zhou
Jun-Hu
JH
Zhang
Yan-Wei
YW
Lu
Zhi-Min
ZM
Fan
Jian-Ren
JR
Cen
Ke-Fa
KF
D000393:Air Pollutants / Q000737:chemistry* / Q000302:isolation & purification; D002248:Carbon Monoxide / Q000737:chemistry*; D003031:Coal; D003198:Computer Simulation; D006358:Hot Temperature; D008956:Models, Chemical; D009589:Nitrogen Oxides / Q000737:chemistry* / Q000302:isolation & purification; D010084:Oxidation-Reduction; D013696:Temperature
D000393:Air Pollutants; D003031:Coal; D009589:Nitrogen Oxides; D002248:Carbon Monoxide