以某台燃用贫煤的130 t/h循环流化床（CFB）锅炉为研究对象，制定了锅炉低氮燃烧技术改造方案，预计通过低氮燃烧将NOx最大排放值由230下降到120 mg/m3以下。风帽结构优化改造后，锅炉临界流化风量降低了11.6%，NOx最大排放值由230降至186.66 mg/m3，较改造前降低了18.8%；锅炉旋风分离器改造方案实施后，分离器入口烟气流速由18.7提高到24.2 m/s，悬浮段压差由635升至943 Pa，炉膛温度下降了18 ℃，NOx最大排放值由186.66降至80.74 mg/m3，较改造前降低了56.7%；燃烧调整试验后，炉膛出口氧体积分数由3.48%减小到2.73%，NOx排放值由59.8降至47.61 mg/m3，较调整试验前下降了20.3%。根据锅炉煤质条件，运行参数和结构参数制定的低氮燃烧技术方案实施后，NOx最大排放值降低了64.8%。锅炉90%负荷以下时，不进行SNCR脱硝也可实现NOx超低排放，实现了低氮燃烧的目标，应用效果优于预期。

Taking a 130 t/h circulating fluidized bed(CFB) boiler burning lean coal as the research object,the low nitrogen combustion technical reconstruction scheme of the boiler was developed.It was planned to reduce the maximum NOx emission value from 230 mg/m3 to less than 120 mg/m3 through low NOx combustion technology.After the optimization of hood structure,the critical fluidization air volume of the boiler was reduced by 11.6%,and the maximum NOx emission value was reduced from 230 mg/m3 to 186.66 mg/m3,which was 18.8% lower than before.After the implementation of the reconstruction scheme of boiler cyclone separator,the flue gas velocity at the inlet of the separator increased from 18.7 m/s to 24.2 m/s,the pressure difference in the suspension section increased from 635 Pa to 943 Pa,the furnace temperature decreased by 18 ℃,and the maximum NOx emission value decreased from 186.66 mg/m3 to 80.74 mg/m3,which was 56.7% lower than that before modification.The combustion adjustment test shows that the oxygen volume fraction at the outlet of the furnace is reduced from 3.48% to 2.73%,and the NOx emission value is reduced from 59.8 mg/m3 to 47.61 mg/m3,which is 20.3% lower than that before the adjustment test.After the implementation of the low nitrogen combustion technology scheme based on the coal quality conditions,operation parameters and structural parameters of the boiler,the maximum NOx emission value has been reduced by 64.8%.Under 90% load of the boiler,without SNCR denitrification,the ultra low NOx emission can be achieved,and the goal of low NOx combustion can be achieved.The application effect is better than expected.

TK221

中国华能集团有限公司总部科技项目(HNKJ18-H13)