不同一次风浓淡比下半焦与烟煤混燃热态实验研究

Hot-state Experiment on Co-combustion of Semi-char and Bituminous Coal Under Different Primary Air Bias Concentration Ratios

在350 kW热态中试炉上开展一次风浓淡比(煤粉质量流量比)对一次风着火特性影响的热态实验研究。通过测量燃烧器下游主燃区不同轴向位置、径向位置处的炉膛温度、O2体积分数、CO体积分数以及NOx质量浓度等参数,研究浓淡比对神华烟煤与神木半焦混合燃烧时(掺混比为50%)着火特性和NOx质量浓度的影响。结果表明:除了浓淡比为1.0,混合燃料浓侧射流着火燃烧均优于淡侧,焦炭稳定燃烧位置向炉膛上游移动,O2消耗及燃烧产物生成也主要集中在浓侧;随着浓淡比的增加,着火距离减小,高温区燃烧稳定性增强,NOx质量浓度大幅降低,但浓淡比为3.8和5.0时,主燃区出口中心NOx质量浓度差值仅为20.27 mg/m3,差距较小,推荐半焦混合燃烧的合适浓淡比为3.8~5.0。

Hot-state experiments were conducted to investigate the influence of the change of bias concentration ratio of pulverized coal at primary air outlet on the ignition properties of primary air-coal mixtures in a 350 kW pilot-scale furnace.The furnace temperature at different axial and radial positions,and the concentrations of gaseous species O2,CO and NOx were measured in the primary combustion zone to study the effects of bias concentration ratio on pulverized coal ignition,NOx emission and burnout properties for co-combustion of Shenhua bituminous coal and Shenmu pyrolyzed semi-char(with blend ratio of semi-char to bituminous coal of 1∶1).Results show that,except for the bias concentration ratio of 1.0 the ignition and combustion properties of the fuel-rich jet are better than the fuel-poor jet;the steady combustion position of coke moves upward in the furnace,while the O2 consumption and flue gas generation mainly concentrate on the fuel-rich side.With the increase of bias concentration ratio,the ignition stand-off distance shortens,the combustion stability in high-temperature region enhances,and the NOx concentration decreases sharply.However,the difference in NOx emission is only 20.27 mg/m3 between the cases with bias concentration ratio of 3.8 and 5.0 respectively,showing very small difference of NOx emission.Therefore it is recommended adopting the bias concentration ratio of 3.8-5.0 for the co-combustion of semi-char and bituminous coal.