四角切圆燃煤锅炉不同燃尽风量下的燃烧特性数值模拟
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摘要
对某300 MW机组四角切圆燃煤锅炉进行燃尽风配风方式的数值模拟,将模拟结果与实际检测结果进行对比,验证了模型的准确性。模拟结果表明,炉内燃烧温度分布均匀,未出现火焰偏斜、冲墙等现象;在负荷一定的情况下增加燃尽风量,有利于降低排放的NO_x质量浓度;在高负荷下4台磨煤机运行时,应尽量开大上级燃尽风门开度,进一步降低NO_x质量浓度,而飞灰中碳质量分数和煤粉燃尽率等指标变化较小;在较低负荷下3台磨煤机运行时,在保证一定燃尽风量的条件下,应尽量运行下级燃尽风而停运上级燃尽风,不仅有利于维持较低的NO_x质量浓度,而且可以保证锅炉的燃烧效率。
A numerical simulation has been carried out to evaluate the characteristics of combustion and NO_x emissions in a 300 MW tangentially fired utility boiler with variable over-fire-air distribution. The numerical simulation was validated using the measured data before the combustion modification with a good agreement. The simulation results show that, the combustion temperature in the furnace is evenly distributed, and there is no deviation of flame or wall. Under a certain load, increasing the rate of over-fire-air, and it is conducive to reducing NO_x emissions. In high-load operating condition with 4 coal grinders running, the upper level over-fire-air door should be opened as far as possible to further reduce NO_x, while the carbon content of fly ash and coal burnout rate have little change. When in low-load operating condition with 3 coal grinders running, it′ s a better operation to run lower level over-fire-air while stop higher level over-fire-air with total over-fire-air rate is constant to maintain the NO_x emission at a low level while ensuring the boiler combustion efficiency.
A numerical simulation has been carried out to evaluate the characteristics of combustion and NO_x emissions in a 300 MW tangentially fired utility boiler with variable over-fire-air distribution. The numerical simulation was validated using the measured data before the combustion modification with a good agreement. The simulation results show that, the combustion temperature in the furnace is evenly distributed, and there is no deviation of flame or wall. Under a certain load, increasing the rate of over-fire-air, and it is conducive to reducing NO_x emissions. In high-load operating condition with 4 coal grinders running, the upper level over-fire-air door should be opened as far as possible to further reduce NO_x, while the carbon content of fly ash and coal burnout rate have little change. When in low-load operating condition with 3 coal grinders running, it′ s a better operation to run lower level over-fire-air while stop higher level over-fire-air with total over-fire-air rate is constant to maintain the NO_x emission at a low level while ensuring the boiler combustion efficiency.
引文
[1]旷金国.高效空气分级燃烧控制燃煤NOx排放的技术理论研究[D].上海:上海交通大学,2010.
[2]庞永梅,王晋权,郭建,等.空气分级燃烧降低锅炉NOx排放控制技术[J].电力科学与工程,2007(4):46-49.
[3]郑成峰,贾令剑,崔星源.低氮燃烧技术在对冲燃烧锅炉上的应用[J].广东电力,2017,30(1):22-26,52.
[4]朱利军.300 MW燃煤锅炉低氮氧化物燃烧的改造[J].广东电力,2009,22(4):64-67.
[5]李德波,徐齐胜,李方勇,等.对冲旋流燃烧煤粉锅炉高温腐蚀现场试验与改造的数值模拟研究[J].广东电力,2015,28(11):6-12.
[6]朱天宇,殷立宝,湛志钢,等.涡耗散模型和混合分数模型模拟锅炉煤粉掺烧污泥过程的适应性[J].中南大学学报(自然科学版),2016,47(8):2864-2872.
[7]殷立宝,朱天宇,张成,等.掺烧污泥煤粉锅炉燃烧特性的数值模拟[J].热力发电,2015,44(3):28-33,41.
[8]陈红,耿向瑾,苏昆.300 MW机组锅炉燃烧调整试验[J].云南电力技术,2005(5):29-31.
[9]洪喜生.300 MW集中营循环流化床锅炉低氧量燃烧优化调整实验分析[J].内蒙古电力技术,2016,34(2):56-58.
[10] Launder B E, Spalding D B. The Numerical Computation of Turbulent Flows[J]. Computer Methods in Applied Mechanics and Engineering, 1974, 3(2):269-289.
[11] De Soete GG. Overall reaction rates of NO and N2formation from fuel nitrogen[C]//Fifteenth symposium(international)on combustion. The Combustion Institute, 1975:1093-1102.
[2]庞永梅,王晋权,郭建,等.空气分级燃烧降低锅炉NOx排放控制技术[J].电力科学与工程,2007(4):46-49.
[3]郑成峰,贾令剑,崔星源.低氮燃烧技术在对冲燃烧锅炉上的应用[J].广东电力,2017,30(1):22-26,52.
[4]朱利军.300 MW燃煤锅炉低氮氧化物燃烧的改造[J].广东电力,2009,22(4):64-67.
[5]李德波,徐齐胜,李方勇,等.对冲旋流燃烧煤粉锅炉高温腐蚀现场试验与改造的数值模拟研究[J].广东电力,2015,28(11):6-12.
[6]朱天宇,殷立宝,湛志钢,等.涡耗散模型和混合分数模型模拟锅炉煤粉掺烧污泥过程的适应性[J].中南大学学报(自然科学版),2016,47(8):2864-2872.
[7]殷立宝,朱天宇,张成,等.掺烧污泥煤粉锅炉燃烧特性的数值模拟[J].热力发电,2015,44(3):28-33,41.
[8]陈红,耿向瑾,苏昆.300 MW机组锅炉燃烧调整试验[J].云南电力技术,2005(5):29-31.
[9]洪喜生.300 MW集中营循环流化床锅炉低氧量燃烧优化调整实验分析[J].内蒙古电力技术,2016,34(2):56-58.
[10] Launder B E, Spalding D B. The Numerical Computation of Turbulent Flows[J]. Computer Methods in Applied Mechanics and Engineering, 1974, 3(2):269-289.
[11] De Soete GG. Overall reaction rates of NO and N2formation from fuel nitrogen[C]//Fifteenth symposium(international)on combustion. The Combustion Institute, 1975:1093-1102.