330MW火电机组锅炉旋流低氮燃烧技术改造及模拟分析  

Technical innovation and simulation analysis of swirl low NO_(x) combustionof a 330 MW thermal power unit boiler

作　　者：蒙涛 康志忠[2] 梁双荣 MENG Tao;KANG Zhizhong;LIANG Shuangrong(CHN Energy Long Yuan Bluesky Energy Conservation Technology Co.,Ltd.,Beijing 100039,China;School of Energy,Power and Mechanical Engineering,North China Electric Power University,Beijing 102206,China)

机构地区：[1]国能龙源蓝天节能技术有限公司,北京100039 [2]华北电力大学能源动力与机械工程学院,北京102206

出　　处：《洁净煤技术》2021年第6期108-114,共7页Clean Coal Technology

基　　金：国家能源投资集团科技资助项目(GJNY-18-20)。

摘　　要：近年来,我国大力推进燃煤发电机组超低排放改造,火电行业NO_(x)排放得到有效控制,但尚有一批早期投运的机组在节能减排方面存在技术瓶颈。国内某电厂330 MW机组锅炉为改善炉内燃烧特性和降低SCR系统入口NO_(x)浓度,对锅炉制粉系统、燃烧器结构和布置方式等提出了一系列改造方案。为预测改造效果,利用FLUENT软件进行了数值模拟,采用考虑详细化学反应的涡耗散概念(EDC)模型来计算伴随煤粉和气体热载体混合快速热解机理的燃烧过程,其中包含了焦炭对NO的异相还原反应。通过观察炉内流场、温度场、O_(2)和NO的分布,分析了改造方案对锅炉炉内各量场、污染物排放的影响。模拟结果表明:制粉系统改造后细煤粉比表面积加大,快速热解反应条件充分,挥发分释放速率提高,氢组分及CO含量高,消耗氧量,减少了NO生成。改变燃烧器结构和布置方式改善了炉内空气动力场,炉内速度分布更均匀,各层旋流燃烧器出口回流区及还原区较明显,也有利于煤粉气流的着火和降低NO_(x)的生成。改造后炉膛出口NO_(x)排放质量浓度可由552 mg/m^(3)下降至345 mg/m^(3),与改造前后现场试验数据较为接近,且趋势相符,从而验证了模拟方法的准确性和改造方案的合理性。In recent years,China has been vigorously promoting the transformation of ultra-low emissions of coal-fired generating units,and nitrogen oxide emissions in the thermal power industry have been effectively controlled.However,there are still a number of early-stage units that have technical bottlenecks in energy conservation and emission reduction.In order to improve the combustion characteristics of the boiler and reduce the NO_(x) concentration at the inlet of the SCR system,a 330 MW unit boiler of a power plant has proposed a series of reform plans for boiler pulverizing system,burner structure and arrangement.In order to predict the effect of the retrofit,numerical simulation was carried out based on FLUENT software.Eddy Dissipation Concept(EDC)model considering detailed chemical reactions was used to calculate the combustion process accompanied by the mixed rapid pyrolysis mechanism of pulverized coal and gas heat carrier,including the heterogeneous reduction of NO by coke.By observing the distribution of the flow field,temperature field,O_(2) and NO distribution in the furnace,the influence of the modification plan on the various measurement fields and pollutant emissions in the boiler furnace was analyzed.The simulation results show that the specific surface area of fine coal powder increases after the modification of pulverizing system.The rapid pyrolysis reaction conditions are sufficient,and the release rate of volatile is increased,the content of hydrogen components and CO are high.It consumes oxygen and reduces NO production.The change of burner structure and arrangement improves the aerodynamic field in the furnace,the velocity distribution in the furnace is more even.The recirculation zone and reduction zone at the outlet of each layer swirl burner are more obvious,which is conducive to the ignition of pulverized coal flow and reduce the formation of NO_(x).The concentration of NO_(x) at the outlet of the furnace decreases from 552 mg/m^(3) to 345 mg/m^(3) after the modification,which is close to the

关 键 词：低氮燃烧技术 NO_(x)排放 涡耗散概念(EDC)模型 技术改造 

分 类 号：TQ53[化学工程—煤化学工程] TK16[动力工程及工程热物理—热能工程]