掺混比对半焦与烟煤混合燃烧及NOx排放特性影响的试验研究

Effects of Blend Ratio on Combustion Characteristics and NOx Emission in Co-firing Process of Semi-char and Bituminous Coal

在350kW中试煤粉锅炉上研究了热解半焦掺混比对神华烟煤与神木半焦混合燃烧时着火特性、燃尽特性以及NOx排放特性的影响,测量了不同轴向位置处炉膛温度以及O2体积分数、CO体积分数和NOx质量浓度等参数。结果表明:随着掺混比的增大,着火性能变差,着火距离增加且着火温度升高,主燃烧区出口NOx质量浓度逐渐增大;采用EGA气体释放法分析燃料着火点时,CO释放法对掺混比为60%和100%的燃料适合,NOx释放法在分析高挥发分烟煤的着火时效果更好;纯半焦燃烧时燃尽率最低,掺混高挥发分烟煤对整体燃尽有较大改善。

Effects of blend ratio on the ignition,NOxemission and burnout characteristics in the co-firing process of shenhua bituminous coal and shenmu pyrolyzed semi-char were investigated in a 350kW pulverized coal-fired pilot-scale furnace,during which,the furnace temperature and concentration profiles of gaseous species(O2,CO and NOx)were measured at different axial positions.Results show that with the increase of semi-char blend ratio,the following ignition characteristics get worse,such as elongated ignition stand-off distance,increased ignition temperature and aggravated NOxemission in the primary combustion zone.When EGA gas analysis is used to estimate the ignition point of fuel blends,the CO gas analysis is found to be more appropriate when the blend ratio is 60%and 100%,while the NOxanalysis achieves better results in analyzing the ignition of bituminous coal with high volatile matters.The burnout rate of pure semi-char is the lowest,which could be improved by blending into the bituminous coal with high volatile matters.