进料速率对生物质颗粒燃烧烟气排放特性的影响

Effect of feeding rate on pollutant emission of biomass pellet burner

为探明进料速率对生物质颗粒燃烧过程中烟气成分及污染物排放的影响规律,以5G-20/85-0.23型生物质颗粒燃烧器为对象,研究进料方式为进2 s停13 s、进2 s停15 s、进2 s停17 s、进2 s停19 s、进2 s停21 s(分别用2/13、2/15、2/17、2/19、2/21表示),相应的平均进料速率为6.9、6.2、5.5、5.0和4.5 kg/h时,烟气中CO、O_2和NO_x含量的变化,考察CO和NO_x含量随运行时间的波动及两者排放量之间的关系。结果表明:进料速率从6.9 kg/h(2/13)降低到5.0 kg/h(2/19)时,烟气中CO含量逐渐减小,在5.0 kg/h时达到最小值66 mg/Nm3;NO_x含量变化与CO相似,在进料速率为5.0 kg/h(2/19)时达到最小值8.8 mg/Nm^3;在进料速率为6.9 kg/h(2/13)时烟气中CO含量随运行时间的波动最大;在不同进料速率下CO含量均呈周期性波动,波动周期与进料周期基本吻合,而NO_x含量随运行时间的波动幅度较小。总体而言,平均进料速率为5.0 kg/h,即进2 s停19 s的进料方式能够明显降低污染物的排放。

Biomass pellets,prepared from wood particles,straws,and other agricultural and forestry residues,possessed the advantages of higher energy density,convenient transportation and storage,and reduced fossil energy consumption and greenhouse gas emissions.They have been widely used in industrial boilers,agricultural greenhouses and household heatingunits.Currently,the efficient measurement and control of pollutant emission during biomass pellet combustion become increasingly important and attract more and more public awareness.Feeding rate is one of the critical factors that determine the combustion status and pollutant emissions.Previous researches mainly focused on the effect of feeding rate on carbon oxide(CO)emission,while the impact on nitrogen oxides(NOx)emission was seldomly reported.The new China National Emission Regulation(NER)issued in early2012requires that NOx emission must be controlled below100mg/m3.