影响焦炉NO_x生成的数值模拟
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摘要
选取JN60型焦炉的单对立火道,利用CFD数值模拟,对传热传质过程进行仿真,计算结果与设计值基本吻合。在此基础上改变焦炉热流密度和跨越孔尺寸,从污染物源头降低NO_x的排放,从而指导工程实际。模拟结果表明,热流密度对NO_x影响很大,当热流密度为4 800 W/m~2时,NO_x浓度为742 mg/m~3,当热流密度为7 600 W/m~2时,NO_x浓度为135.1 mg/m~3,降低了约600 mg/m~3;跨越孔开度越大,则内循环率越大,反应区随之增大,反应物消耗速率降低,NO_x生成量减少。
A pair of vertical flues of JN60 coke oven combustion chamber are selected.The CFD numerical simulation is used to establish a coupled model of air depleted combustion intensity and combustion fluid multi-concentration field.The heat mass transfer process was simulated,and the calculation results are basically consistent with the design values.On this basis,heat flux density of the coke oven and turn point size were changed to minimize the NO_x emission fundamentally.The simulation result shows that the heat flux density has much influence on the NO_x,i.e.when the heat flux density is 4,800 W/m~2,the NO_x concentration is 742 mg/m~3,when the heat flux density reaches 7,600 W/m~2,the NO_x concentration drops down to 135.1 mg/m~3,reduced by about 600 mg/m~3;similarly,the more opening of the turn point,the higher inner circulation rate,the wider reaction zone,the lower consumption rate of the reactant and the lower NO_x formation as a result.
A pair of vertical flues of JN60 coke oven combustion chamber are selected.The CFD numerical simulation is used to establish a coupled model of air depleted combustion intensity and combustion fluid multi-concentration field.The heat mass transfer process was simulated,and the calculation results are basically consistent with the design values.On this basis,heat flux density of the coke oven and turn point size were changed to minimize the NO_x emission fundamentally.The simulation result shows that the heat flux density has much influence on the NO_x,i.e.when the heat flux density is 4,800 W/m~2,the NO_x concentration is 742 mg/m~3,when the heat flux density reaches 7,600 W/m~2,the NO_x concentration drops down to 135.1 mg/m~3,reduced by about 600 mg/m~3;similarly,the more opening of the turn point,the higher inner circulation rate,the wider reaction zone,the lower consumption rate of the reactant and the lower NO_x formation as a result.
引文
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[2] 刘祥凯.机焦炉排放的大气污染物浓度特征研究[J].能源与节能,2015(12):107-108.
[3] 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.
[4] 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.
[5] 姚昭章,郑东明.炼焦学[M].北京:冶金工业出版社,2008:258.
[6] 张建社,张合宾.焦炉复合煤气加热氮氧化物形成模拟研究[J].山东化工,2015,44(12):148-149,152.
[7] 李立业,田京雷,黄世平.焦炉烟气SO2和NOx排放控制[J].燃料与化工,2017,48(2):1-3,8.
[8] 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.
[9] 刘建,司长明,李政.7.63m焦炉脱硝技术的研究与应用[J].煤矿现代化,2017(2):101-102.
[10] 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.
[11] 金珂,冯妍卉,张欣欣,等.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.