Experiment and mechanism investigation on advanced reburning for NOx reduction： influence of CO and temperature

• Published in: Journal of Zhejiang University. B. Science Vol. 6; no. 3; pp. 187 - 194
• Main Author: 王智化 周俊虎 张彦威 卢志民 樊建人 岑可法
• Format: Journal Article
• Language: English
• Published: Hangzhou Springer Nature B.V 01.03.2005; Clean Energy & Environment Engineering Key Laboratory of Ministry of Education, Zhejiang University, Hangzhou 310027, China; Zhejiang University Press
• Subjects: Ammonia; Carbon monoxide; Coal; Environment Science; Fineness; Flue gas; Fly ash; Fuels; Injection; Investigations; Nitrogen oxides; NOx; Process parameters; Pulverized coal; Reburning; Reduction; Stoichiometry; Temperature; Tube furnaces; 一氧化碳; 大气污染; 污染物; CO; NO reduction; Advanced burning; Coal reburning; Selective Non-catalytic NOx Reduction (SNCR)
• ISSN: 1673-1581; 1862-1783
• DOI: 10.1631/jzus.2005.B0187

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%-25% reburn heat input, temperature range from 1100 ℃ to 1400℃ 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 ~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 ℃-1100 ℃. 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 NOx 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.