生物质与褐煤循环流化床燃烧污染物排放研究

Study on Pollutant Emission from Biomass and Lignite Circulating Fluidized Bed Combustion

为研究稻壳与褐煤混合燃料在循环流化床中燃烧后产生的污染物的排放特性,在自制小型循环流化床试验台上进行了稻壳与褐煤掺烧试验,分析了燃烧温度和稻壳掺混比例对污染物排放量和炉膛温度分布的影响。结果表明:与煤粉单独燃烧相比,随着稻壳掺混比例的增加,炉膛内垂直方向的放热均匀,燃烧更加稳定,挥发分的析出量增多,CO排放量逐渐升高,炉膛中下部的温度明显上升;由于还原性气氛和多孔性颗粒的共同作用,NO_(x)排放量逐渐降低;当稻壳含量大于30%时,结焦明显;在相同稻壳掺混比例下,随着燃烧温度升高,燃烧效率提高,CO排放量逐渐降低,由于还原性气氛减少和高温加剧煤粉中含氮化合物裂解的影响,NO_(x)排放量上升的程度不同。

In order to study the pollutant emission characteristics of mixed fuel of rice husk and lignite in a circulating fluidized bed,the combustion experiments of rice husk and lignite were carried out on a self-made small circulating fluidized bed test bed.The effects of combustion temperature and mixing ratio of rice husk on pollutant emission and temperature distribution in the furnace were investigated.The results show that compared with pulverized coal combustion alone,with the increase of rice husk mixing ratio,the vertical height of the furnace heat release is uniform,the combustion is more stable,at the same time,the volatilization analysis output increases,the CO emission gradually increases,and the temperature in the middle and lower part of the furnace rises obviously.The NO_(x) emission decreased gradually due to the combined action of reducing atmosphere and porous particles.When the content of rice husk is above 30%,the coking is obvious.Under the same mixing ratio of rice husk,with the rise of combustion temperature,the combustion efficiency is improved,and the CO emission gradually decreases.The NO_(x) emission increases to different degrees because the reducing atmosphere decreases and the high temperature aggravates the fracture of the chemical bond containing nitrogen in the pulverized coal.