不同进料方式燃烧器对生物质燃料颗粒物排放特性的影响

摘要

为摸清不同进料方式的燃烧器对生物质成型燃料燃烧后颗粒物排放的影响，该文对上进料式（A 型）、水平进料式（B型）和下进料式（C型）等3种类型的燃烧器进行燃烧颗粒排放试验，采用低压电子冲击仪对玉米秸秆、棉秆、木质3种成型燃料燃烧后颗粒物排放开展数量浓度和质量浓度研究，并计算出每种燃料在3种燃烧器中每秒排放的颗粒物数量和质量分布。试验结果表明：3种燃烧器中的颗粒物质量分布都成双峰分布，主要集中在5～7级和12级，占总颗粒物质量的90%；木质和棉杆燃料在A型燃烧器中的颗粒物质量排放最少，玉米秸秆燃料在B型中颗粒物质量最少。3种燃烧器中的颗粒物数量分布都成单峰分布玉米秸秆和木质在B型燃烧器上的颗粒物数量主要集中在1～5级，在A型和C型燃烧器上颗粒物数量主要集中在3～6级；棉杆在C型燃烧器上集中在1～5级，在A型和B型燃烧器上颗粒物数量主要集中在3～6级。3种燃烧器对颗粒物质量的分布影响不大。根据试验结果，建议不同的燃料匹配不同的燃烧器。从颗粒物排放总量角度，玉米秸秆应该匹配B型燃烧器，棉杆和木质燃料应该匹配A型燃烧器。从PM2.5所占比例得出，玉米秸秆燃料应匹配C型燃烧器，棉杆匹配 B 型燃烧器，木质匹配 A 型燃烧器。并建议生物质成型燃料燃烧器结构应具有以下特点：进料连续平稳；带有主动清渣装置并且清渣波动小；鼓风配风，保证过量空气系数高。研究结果为中国生物质固体成型燃料的颗粒物排放法规的制定提供参考。%Different structure and the different feeding mode burners affect the emission and the combustion efficiency of various biomass solid fuels. However, how the burner structure and feeding mode impact on the particle emissions is not clearly understood. To investigate this, an experiment was conducted to evaluate gas emissions from three types of feeders:the upper feeding type burner (type A), the horizontal feeding type burner (type B) and the bottom feeding type burner (type C), and types of solid biomass fuels:corn straw, cotton stalks and wood compressed into a cylindrical type (diameter, 8 mm, length, 10-30 mm) burned respectively at maximum power on each type of burner. The gas composition emitted was determined using SEMTECH (Sensors, U.S.) for the number and concentration of particulate from the three kinds of biomass solid fuel burned respectively from three burners via Electrical Low Pressure Impactor (ELPI). The particle size was catalogued into 12 classes, ranging from 0.003-10μm. The number of particle size emitted and their corresponding mass distribution per second from the three burners were calculated. The experimental results showed that particle mass distribution from the three burners had two peaks respectively in the 5-7 (>0.165-0.637μm) and 12 (>3.970-10.150μm) levels accounting for the total particulate mass of 90%. For corn straw pellets in A, B, C type of burner combustion, PM 2.5 (PM below grade 10) accounted 68.5%, 70%, 51%for PM10 of particulate mass, respectively, in contrast to the cotton stalks pellets, which accounted 74.2%, 66.9%, 76.7% for PM10 of particulate mass. For wood pellets combustion in the three burners, on the other hand, PM2.5 accounted 61.8%, 67.8%, 68.1%for PM10 of particulate mass. As compared to the particle mass distribution, the number of particles distributed in three burners only had one peak. The most particulate numbers of corn straw and wood were in the 1-5 level in the type B burner, but in the 3-6 level in the type A and type C burner. The particle numbers of cotton straw was mainly in the 1-5 level in the type C burner, and in the 3-6 level in the type A and type B burner. Three kinds of burners had little influence on the distribution of the particle mass. The test results suggested that agriculture residues used as fuels needed to be burner specific. From the point of view of the total emissions of particulate matter, corn straw should be matched with the type B burner, cotton stalk and wood fuel should be matched with the type A burner. From the aspect of proportion of PM2.5 emission, corn straw fuel should be matched with the type C burner, cotton stalk should be matched with the type B burner, wood should be matched with the type A burner. In addition, the structure of biomass solid fuel burner may have following characteristics:Continuous feeding smoothly;equipped with active slag cleaning device and small slag wave; pressured air flow to ensure the high air ratio. The research provided reference for particulate emission regulations of biomass solid fuel of China.