立体分级燃烧对NO_x排放特性的影响

Effects of Stereo-staged Combustion Technique on NO_x Emmision Charactisctics

采用水平浓淡燃烧器及燃尽风联用的立体分级燃烧技术,对某台220t/h燃烟煤、矩形炉膛锅炉机组进行降低NOx排放的改造,并对其进行试验研究。重点考察水平浓淡燃烧器、二次风配风方式和不同燃尽风份额对NOx排放量、炉膛温度水平、CO、CO2的影响规律。研究表明,采用新型水平浓淡燃烧器后,在强化燃烧的同时,可降低13%左右的NOx排放量;二次风配风方式对NOx排放影响明显,采用倒宝塔配风方式可降低NOx排放浓度至408mg/m3;在燃尽风份额分别为0、0.21、0.31和0.43时,除出口氧量增加外,CO、CO2、飞灰碳体积分数变化不大,主燃烧区域温度水平总体呈降低趋势,燃尽区温度水平呈现先增加后降低趋势,NOx排放浓度持续降低。在未投三次风情况下,NOx排放浓度可降低到363mg/m3。改造后,NOx排放浓度可稳定在450mg/m3以下,为浓淡燃烧与燃尽风联用技术在大容量锅炉机组上的推广提供重要技术依据。

An experimental study to reduce the NOx emission is conducted in a 220 t/h tangential pulverized coal firing rectangle furnace, with a stereo-staged combustion technique combining horizontal bias combustion （HBC） burners and over fire air （OFA）. The primary purpose of this work is to investigate the effects of HBC burners, distribution of secondary air and changing the ratio of OFA on the NOx emission, furnace temperature, and formation of CO and CO2. It is indicated that the combustion is enhanced and furthermore the NOx emission is reduced by 13% after utilizing the new HBC burners. The distribution of secondary air influences the NOx emission obviously, and the concentration of NOx emission decreases to 408 mg/m^3 with reasonable distribution of secondary air. When the ratio of OFA is increased gradually from 0 to 0.21, 0.31 and 0.43, the concentrations of CO, CO2 and unburned carbon in fly ash do not change greatly, except the increase of O 2 concentration at furnace exit. The temperature level of primary zone tends to lower as a whole, while the temperature level of over fire zone tends to rise at first and then to lower, and the. NOx emission concentration decreases continuously. The NOx emission concentration can decrease to 363 mg/m^3 without the operation of tertiary air. The application of stereo-staged combustion technique can make the NOx emission concentration keep at below 450 mg/m^3, and which provides an important technical basis for applying this new technique to the large capacity boiler.