Abstract:

To study the influence of different excess air coefficient （α） on the layer combustion characteristics of biomass briquettes， the typical corn straw pellet fuel in the main grain production areas in Northeast China was used as the research object， and a fixed-bed test rig for biomass pellets was built to simulate of the combustion process of biomass pellets along the height of the furnace and moving direction of the grate， 25 sets of combustion tests under 5 working conditions of 30， 40， 50， 60 and 70 Nm³·h^-1 were carried out， respectively. The test data was collected by the patrol instrument， and the collection step length was 1 min. The collected data was processed and analyzed by methods such as matrix and polynomial fitting. The test results indicated that when the primary air flow （Q_ao） was not less than 50 Nm³·h^-1， the ignition delay time （t_d）， flame downward propagation rate （R_f） and fuel content in ash （η_a） decreased with the increase of Q_ao._{As Qao was less than 50 Nm³·h^-1， td， Rf， and ηa increased with the increasing of Qao. In the combustion zones of 200~150 and 100~50 mm， Rf showed a trend of decreasing and then increasing. In the combustion zone of 150~100 mm， when Qao was not more than 40 Nm³·h^-1， Rf increased with the increasing of Qao， and then as Qao was more than 40 Nm³·h^-1， Rf tended to be stable. It was found that when Qao was 50 Nm³·h^-1 （α was 1.163）， td was 3.34 min， and the combustion temperature was higher and the time was shorter （about 45 min） than other Qao， and ηa was 0.71%， the layer combustion characteristics were more ideal than other conditions.}

Key words: corn straw, pellets, excess air coefficient, ignition characteristics, combustion characteristic, burnout characteristics

摘要：

为了研究不同过量空气系数（α）对生物质成型燃料层燃特性的影响，以我国东北粮食主产区典型的玉米秸秆颗粒燃料为研究对象，搭建生物质成型燃料固定床试验台，模拟生物质成型燃料沿炉膛高度和炉排行进方向上的燃烧过程，分别进行了风量为30、40、50、60和70 Nm³·h^-1共5个工况的25组燃烧试验。应用巡检仪采集试验数据，采集步长为1 min，将采集到的数据用矩阵化、多项式拟合等方法进行处理分析。结果表明：当一次风量（Q_ao）≥50 Nm³·h^-1时，燃料的着火延迟时间（t_d）、火焰向下传递速率（R_f）及灰渣中可燃物含量（η_a）均随Q_ao的增加而降低；当Q_ao<50 Nm³·h^-1时，燃料的t_d、R_f、η_a参量均随Q_ao的增加而增加；在距离炉排高度200~150和100~50 mm燃烧区内，随着Q_ao的增加，R_f呈现先减小后增大的趋势。在距离炉排高度150~100 mm燃烧区内，当Q_ao≤40 Nm³·h^-1时，R_f随Q_ao的增加而增加，当Q_ao>40 Nm³·h^-1时，R_f趋于平稳。由试验分析可知，当Q_ao的值为50 Nm³·h^-1（α的值为1.163）时，t_d为3.34 min，燃烧温度水平较高且时间较短（约为45 min），燃烧后η_a为0.71%，层燃特性较为理想。

关键词: 玉米秸秆, 颗粒, 过量空气系数, 着火特性, 燃烧特性, 燃尽特性