为了研究煤粉工业锅炉大占比掺混生物质的燃烧特性和NOx排放特点，以高速煤粉燃烧器为研究对象，在型号为WNS的6 t/h蒸汽锅炉系统上进行试验研究，燃料为秸秆和神府烟煤混合粉体。首先研究混合燃料在高速煤粉燃烧器中的燃烧稳定性，其次研究掺混占比、锅炉负荷及空气分级对燃烧和NOx的影响。研究结果表明：不对燃烧器做任何改动，不同占比的混合燃料均能够在燃烧器中着火和稳燃，工况4条件下锅炉从点火到额定负荷只需26 min，燃烧器观火孔处火焰橘红色，炉尾火焰亮红色，锅炉运行氧含量与炉膛压力波动平稳；当深度空气分级时，三次风达到总风量的质量浓度50%，秸秆占比为0时的NOx最低排放质量浓度为420 mg/m3左右，飞灰热值5 525 kcal/kg；秸秆占比分别为50%和70%时NOx最低排放质量浓度为110～120 mg/m3，飞灰热值2 511～2 930 kJ；秸秆占比为100%时NOx最低排放质量浓度为200 mg/m3，飞灰热值为0，表明大占比掺混生物质有利于提高深度空气分级时的燃烧效率和低氮效果；当锅炉负荷从4 t/h提高到6 t/h，掺混秸秆占比为50%和70%的混合燃料燃烧和低氮效果变优，燃用纯秸秆粉体NOx排放质量浓度从135 mg/m3增加到218 mg/m3；二次风是影响NOx排放的决定性因素，以50%掺混占比的混合燃料为例，使用空气分级技术，100%负荷时锅炉二、三次风阀开度分别为27%和100%，NOx初始排放质量浓度从417 mg/m3降低到182 mg/m3，80%负荷时锅炉二、三次风阀开度分别为20%和70%，NOx初始排放质量浓度从711 mg/m3降低到205 mg/m3。

In order to study the combustion and NOx emission characteristics on the industrial pulverized coal boiler，experimental study method is used and the high speed pulverized coal burner installed on a WNS boiler with a volume of 6 t/h is selected as the research object. The mixed fuel for the boiler is straw and Shenfu bituminous coal. Combustion stability at the high speed burner of the mixed fuel is the first research target and the second target is to study the effect of blending proportion，boiler load and air staging combustion on NOx emission. The research result shows that the high speed burner has a good combustion stability performance for the mixed fuel without any structural changes as the oxygen and pressure fluctuating is steadily. The boiler can fire immediately and get to full load in 26 minutes when the straw blending is 100% and its flame is orange in the burner and bright orange at the furnace tail. When the deep air staging combustion technology is used，tertiary air accounts for 50% of the total air. The experiment shows that NOx emission is about 420 mg/m3and the calorific value of fly ash is 1 320 kcal/kg when the straw is 0% while the initial NOx emission is between 110～120 mg/m3 when the straw blending ratio is 50% and 70% with the remaining fly ash calorific value is 600～700 kcal/kg. When the straw blending ratio is 100% the NOx emission is controlled under 200 mg/m3 and the ash calorific value is 0.1 t shows that co-combustion is beneficial to acquire lower NOx emission and higher combustion efficiency when deep air staging combustion technology is used. When the boiler load increases from 4 t/h to 6 t/h，the combustion efficiency is improved and NOx emission is decreasing when the straw blending ratio is 50% and 70%. While the NOx emission increases from 135 mg/m3 to 218 mg/m3 when the pure straw power is burned as the boiler load increases with the fly ash calorific value remains 0.Secondary air is the decisive factor which influences the NOx emission. For example NOx emission reduced from 417 mg/m3 to 182 mg/m3 when the valve lift is 27% and 100% for the secondary and tertiary air at 100% load with the fuel is blended with 50% straw. The NOx emission reduced from 711 mg/m3 to 205 mg/m3 when the valve lift is 20% and 100% for the secondary and tertiary air with the 80% boiler load.

0 引言

1 燃料性质与试验装置

   1.1 燃料准备

   1.2 工程试验装置

   1.3 高速煤粉燃烧器试验工况

2 试验结果与分析

   2.1 燃烧稳定性分析

   2.2 高速燃烧器掺烧秸秆NOx排放研究

3 结论