低负荷一次风掺烟量对Π型切圆锅炉NOx生成特性影响  

Effect of mixing ratio of flue gas in primary air on NOx generation characteristics inΠ-type tangentially fired boiler at low load

作　　者：景雪晖 唐权利 朱建平 李骥 刘坤朋 王建江 魏博[2] JING Xuehui;TANG Quanli;ZHU Jianping;LI Ji;LIU Kunpeng;WANG Jianjiang;WEI Bo(Xinjiang Xinneng Group Co.,Ltd.,Urumqi 830047,China;Key Laboratory of Coal Clean Conversion&Chemical Engineering Process,Xinjiang University,Urumqi 830046,China)

机构地区：[1]新疆新能集团有限责任公司,新疆乌鲁木齐830047 [2]新疆大学煤炭清洁转化与化工过程自治区重点实验室,新疆乌鲁木齐830046

出　　处：《热力发电》2020年第12期84-88,共5页Thermal Power Generation

摘　　要：锅炉在低负荷运行时,为了保证携粉能力,一次风量不能随负荷等比例降低,导致燃烧初期氧煤比增大,NOx生成量增加。采用一次风掺烟方式,将风量与氧量解耦,分别控制一次风量和氧量,保证一次风量的同时降低含氧量,可从源头减少NOx的生成。以某330 MW机组锅炉结构参数和低负荷运行参数为依据,对该锅炉在低负荷一次风不同掺烟量进行数值模拟研究,分析不同的掺烟量对炉内截面平均温度、氧体积分数、CO体积分数以及NOx生成质量浓度的影响。结果表明:低负荷一次风掺烟能有效降低锅炉NOx的生成,随着掺烟量的升高,炉内截面平均温度逐渐降低,CO体积分数逐渐降低,炉膛出口平均温度逐渐升高,NOx生成质量浓度减少;掺烟量为15%时与未掺烟比较,炉内NOx生成质量浓度降低79.92 mg/m^3。To ensure the powder carrying capacity of primary air,when the boiler is running at a low load,the primary air volume cannot be reduced in proportion to the load,which leads to an increase in oxygen-to-coal ratio at initial stage of combustion and an increase in NOx production.By using the method of primary air mixed with flue gas,the air volume and oxygen quantity are decoupled,the primary air volume and oxygen quantity are controlled individually,thus to reduce the oxygen concentration on the premise of ensuring the primary air volume,which can decrease the formation of NOx from the source.According to the structural parameters and low-load operating parameters of a 330 MW unit boiler,numerical simulation was carried out to study the effects of flue gas mixing ratio on the average temperature in furnace section and the volume fraction of O2 and CO as well as the mass concentration of NOx produced.The results show that,blending flue gas in primary air at low load can effectively reduce the NOx generation in the boiler.With the increase of the mixing ratio of flue gas,the average temperature in the furnace section and the CO volume fraction gradually decreases,the average temperature at the furnace outlet gradually increases,and the NOx production reduces.Compared with the furnace with no flue gas mixing in primary air,the mass concentration of NOx production in the furnace with flue gas’s mixing ratio of 15%reduces by 79.92 mg/m^3.

关 键 词：低负荷 一次风掺烟 NOX排放 数值模拟 切圆锅炉 

分 类 号：TK224[动力工程及工程热物理—动力机械及工程]