天然气再燃降低NOx排放的热态工业试验研究

Hot-state Industrial Experimental Study of the Reburning of Natural Gas to Reduce NOx Emissions

根据对某电厂采用天然气再燃技术进行低氮改造220 t/h煤粉炉的热态工业试验,研究炉膛氧量、再燃量、停留时间、配风方式等运行因素对再燃还原NOx效果的影响,并与前人的研究成果进行对比。通过分析得出以下结论:排放浓度都随着氧量的增加而增大,随着锅炉负荷降低而减小,最佳氧量为5%(表盘氧量为3.5%左右);随着再燃量的增加NOx浓度下降,最佳再燃量保持在15%;最佳停留时间为0.67 s,过长的停留时间对再燃还原效果影响不大;主燃区最佳配风方式为正宝塔式;最佳运行工况下NOx排放浓度平均值为137 mg/Nm。

Through a hot-state industrial test of a 220 t / h pulverized coal-fired boiler after it had undergone a low nitrogen modification by using the natural gas reburning technology,studied was the influence of the oxygen content in the furnace,amount of natural gas reburned,residence time and air distribution mode etc. operating factors on the NOx reduction effectiveness through reburning and compared were the results with the research findings done by the predecessors. Through an analysis,the authors have arrived at a conclusion that the emissions concentration will increase with an increase of the oxygen content and decrease with a decrease of the load of the boiler. The optimal oxygen content is 5%( the oxygen content indicated on the dial plate is around 3. 5%). With an increase of the amount of natural gas reburned,the NOxconcentration will decline with the optimal amount of natural gas reburned being kept at 15%. The optimal residence time is 0. 67 s. An excessively long residence time has no big influence on the reburning reduction effectiveness. The optimal air distribution mode in the main combustion zone is of the normal tower type. Under the optimum operating condition,the average value of the NOxemissions concentration is137 mg / Nm.