135MW四角切圆煤粉炉低氮改造及试验研究

Low Nitrogen Modification to and Experimental Study of a 135 MW Tangential Pulverized Coal-fired Boiler

对杭州某电厂135 MW机组锅炉进行低氮改造,采用SOFA(分离式燃尽风)与浓淡煤粉燃烧器相结合来实现空气分级低NOx改造。对比分析改造前后的锅炉效率和NOx排放浓度,改造后NOx排放浓度由原来的650 mg/m3降为300 mg/m3左右,而锅炉效率的变化幅度不超过±0.5%。通过运行试验可以得到,降低运行氧量能够减少NOx的生成,但会导致飞灰含碳量的增加;同样,加大SOFA风量以及调节其风门至上摆也能减少NOx;磨煤机投运方式也会对NOx的排放浓度产生影响。

The authors performed a low nitrogen modification to a 135 MW boiler unit in a power plant in Hangzhou City and adopted separated overfire air( SOFA) nozzles in a combination with pulverized coal bias burners to realize an air staged low NOxmodification. In this connection,the boiler efficiency and NOxemissions concentration before and after the modification were contrasted and analyzed. The NOx emissions concentration after the modification decreased from the original 650 mg / Nm3 to around 300 mg / Nm3 and the variation range of the boiler efficiency did notexceed ± 0. 5%. The operation experience shows that to lower the amount of oxygen consumed in operation can reduce the NOxproduced,however,this can lead to an increase of the carbon content of flying ash. It is also true that to increase the amount of SOFA and to regulate the SOFA damper to its largest opening degree can also reduce the production of NOx. In addition,the mode of putting the pulverizer into operation can also influence the NOxemissions concentration.