Pulverized coal reburning, ammonia injection and advanced reburning in a pilot scale drop tube furnace were inves- tigated. Premix of petroleum gas, air and NH3 were burned in a porous gas burner to generate the neede...Pulverized coal reburning, ammonia injection and advanced reburning in a pilot scale drop tube furnace were inves- tigated. 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 °C to 1400 °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 °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 °C^1100 °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 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.展开更多
以某台350t/d垃圾焚烧炉为研究对象,利用CFD数值模拟方法,研究掺混不同比例半干化污泥(含水率60%)下的燃烧特性以及污染物排放特性,并对选择性非催化还原(selective non catalytic reduction,SNCR)脱硝喷枪位置进行了优化研究。结果表明...以某台350t/d垃圾焚烧炉为研究对象,利用CFD数值模拟方法,研究掺混不同比例半干化污泥(含水率60%)下的燃烧特性以及污染物排放特性,并对选择性非催化还原(selective non catalytic reduction,SNCR)脱硝喷枪位置进行了优化研究。结果表明:一烟道烟气温度与污泥掺混量成反比,氧含量与污泥掺混量成正相关,在3%~13%的污泥掺混量中,7%是比较合适的污泥掺混量,污泥掺混量低于10%时,第一烟道高温区的燃烧状态能达到二恶英控制的燃烧要求。NO_x生成量与污泥掺混量成正相关,在10%掺混量时仅采用SNCR方法焚烧炉出口烟气NO_x含量高达278.63mg/m^3,未能达到排放标准。但通过对SNCR喷枪位置进行调整,可利用烟气涡旋回流提高脱硝效率,相同氨氮比下出口烟气NO_x含量降低到245.25mg/m^3。模拟计算得出不同污泥掺混量时的温度和NO_x的变化趋势,提出适宜的污泥掺混量及SNCR喷枪布置优化方案,可为垃圾焚烧炉污泥掺混焚烧及SNCR脱硝提供参考。展开更多
文摘Pulverized coal reburning, ammonia injection and advanced reburning in a pilot scale drop tube furnace were inves- tigated. 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 °C to 1400 °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 °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 °C^1100 °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 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.
文摘以某台350t/d垃圾焚烧炉为研究对象,利用CFD数值模拟方法,研究掺混不同比例半干化污泥(含水率60%)下的燃烧特性以及污染物排放特性,并对选择性非催化还原(selective non catalytic reduction,SNCR)脱硝喷枪位置进行了优化研究。结果表明:一烟道烟气温度与污泥掺混量成反比,氧含量与污泥掺混量成正相关,在3%~13%的污泥掺混量中,7%是比较合适的污泥掺混量,污泥掺混量低于10%时,第一烟道高温区的燃烧状态能达到二恶英控制的燃烧要求。NO_x生成量与污泥掺混量成正相关,在10%掺混量时仅采用SNCR方法焚烧炉出口烟气NO_x含量高达278.63mg/m^3,未能达到排放标准。但通过对SNCR喷枪位置进行调整,可利用烟气涡旋回流提高脱硝效率,相同氨氮比下出口烟气NO_x含量降低到245.25mg/m^3。模拟计算得出不同污泥掺混量时的温度和NO_x的变化趋势,提出适宜的污泥掺混量及SNCR喷枪布置优化方案,可为垃圾焚烧炉污泥掺混焚烧及SNCR脱硝提供参考。