焦炉立火道NO_x形成的数值模拟
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摘要
针对焦炉立火道内的废气循环燃烧多浓度场过程开展数值模拟,详细研究了空气和煤气入口尺寸及废气循环对NO_x生成的影响。结果表明,NO_x绝大部分是在上升立火道高度方向的中间位置高温区生成;增加外循环烟气量可以降低燃烧温度和缩小高温区域,从而降低NO_x生成量;当外循环率为20%时,最高温度降低88℃,温度场更加均匀;当入口面积减小为原来的1/2时,内循环率增加至原来的1.95倍,NO_x排放量降低13.7%。
Numerical simulation of NO_x formation is done for the multi-concentration fields of waste gas recirculation combustion inside coke oven vertical flues.The impact of air and gas inlet size and waste gas recirculation to the NO_x formation is studied.The result shows that most of NO_x is formed at the high temperature zone in the middle of rising vertical flue.Increasing external gas circulation would reduce the combustion temperature and narrow thermal peak so as to decrease the NO_x formation.When the external circulation rate is 20%,the maximum temperature is lowered by 88 ℃ and the temperature field gets more uniform.When the inlet area is cut by half,the internal circulation rate is increased to 1.95 times and the NO_x emission is reduced by 13.7%.
Numerical simulation of NO_x formation is done for the multi-concentration fields of waste gas recirculation combustion inside coke oven vertical flues.The impact of air and gas inlet size and waste gas recirculation to the NO_x formation is studied.The result shows that most of NO_x is formed at the high temperature zone in the middle of rising vertical flue.Increasing external gas circulation would reduce the combustion temperature and narrow thermal peak so as to decrease the NO_x formation.When the external circulation rate is 20%,the maximum temperature is lowered by 88 ℃ and the temperature field gets more uniform.When the inlet area is cut by half,the internal circulation rate is increased to 1.95 times and the NO_x emission is reduced by 13.7%.
引文
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[3] 杨楠,王雪.氮氧化物污染及防治[J].环境保护与循环经济,2010,30(11):63-67.
[4] 田宝龙,朱灿朋,鲁彦,等.焦炉分段加热技术对NOx生成的影响[J].燃料与化工,2016,47(1):4-8.
[5] 张慧玲.焦炉烟气脱硝技术的分析与探讨[J].山西焦煤科技,2016,40(1):151-153.
[6] 何选明,陈康,潘叶,等.焦炉煤气低NOx燃烧技术研究进展[J].燃料与化工,2013,44(1):6-10.
[7] 钟英飞.焦炉加热燃烧时氮氧化物的形成机理及控制[J].燃料与化工,2009,40(6):5-12.
[8] 杨俊峰,康婷,关岚,等.焦炉加热时过量空气系数对氮氧化物生成量的影响[J].燃料与化工,2014,45(4):13-16.
[9] 余明程,王光华,李文兵,等.焦炉加热过程中热力型氮氧化物的生成及影响因素研究[J].工业安全与环保,2016,42(10):75-78.
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[11] 李红.焦炉结焦过程立火道NOx生成特性研究[D].马鞍山:安徽工业大学,2017.
[12] 金珂,冯妍卉,张欣欣.耦合分级燃烧的大容积焦化过程仿真[J].中国电机工程学报,2012,32(35):13-20.
[13] 姚昭章,郑东明.炼焦学(第2版)[M].北京:冶金工业出版社,2008:258.