MOE Key Laboratory of Thermo-Fluid Science and Engineering,Xi′an Jiaotong University
Key Laboratory for Clean Combustion and Flue Gas Purification of Sichuan Province
Shandong Shunye pressure vessel Co.,Ltd

煤粉预燃低氮燃烧技术可兼顾稳定燃烧与NOx排放控制,在燃煤锅炉灵活性调峰稳燃领域的应用潜力巨大。依托5MW燃烧试验平台,研究一种带小型预燃室的高浓度煤粉预燃低氮燃烧器运行性能。通过CFD数值模拟,系统研究了一次风率、内外二次风配风与分离式燃尽风(SOFA)对燃烧器燃烧性能及污染物排放特性的影响。结合5MW燃烧试验平台测试结果对燃烧模型进行验证验证,试验实际温度与数值计算结果的最大偏差为44℃,误差范围±3.3%,证明所选燃烧模型的准确性。研究结果表明:一次风率是影响预燃室环形回流区的关键因素,过低或过高的一次风速会分别对稳燃能力与降氮能力产生影响,在约8.8%的一次风率条件下能够保证有充足的回流量,有利于煤粉着火和排放控制;升高内二次风率能卷吸更多炉膛内高温烟气,有利于煤粉燃尽,但炉膛内部高温氧化性气氛区域增加,会导致污染物排放有所升高,约为43.5%的内二次风率能兼顾稳燃与降氮效果;采取适当比率的SOFA替代外二次风,能使得燃烧区域的含氮化合物更易被还原,从而降低排放,在23%SOFA风率下出现明显的低氮效果,NOx排放为72mg/m3(6%O2),与0%SOFA风率相比减排约67%。

The low nitrogen combustion technology of pulverized coal pre - combustion can balance stable combustion and NO emission control,which has great application potential in the field of flexible peak shaving and stable combustion of coal-fired boilers. Based onthe 5 MW combustion test rig,the operation performance of a high-concentration pulverized coal pre-combustion low-nitrogen burner witha small pre-combustion chamber developed by the authors′ team was studied. The effects of primary air rate,internal and external secondary air distribution and separate over-fire air (SOFA) on the combustion performance and pollutant emission of the burner were systematically studied by CFD numerical simulation. The combustion model was verified by the test results of the 5 MW combustion test rig.The maximum deviation between the actual temperature and the numerical calculation results is 44 ℃ ,and the error range is ±3.3%,whichproves the accuracy of the selected combustion model. The results show that the primary air rate is the key factor affecting the backflowzone of the pre-combustion chamber,and too low or too high primary air rate will affect the combustion stability and nitrogen reductionability respectively. Under the condition of 8.8% primary air rate,sufficient backflow can be guaranteed,which is conducive to the ignitionand emission control of pulverized coal. Increasing the internal secondary air rate can entrain more high-temperature flue gas in the furnace,which is conducive to the burning of pulverized coal. However,the increase of the high-temperature oxidizing atmosphere area in thefurnace will lead to the increase of pollutant emission. The internal secondary air rate of about 43.5% can both stabilize combustion and reduce nitrogen. Replacing the external secondary air with an appropriate proportion of SOFA can make the nitrogen-containing compoundsin the combustion area more easily reduced,thus reducing emissions. At 23% SOFA rate,a significant nitrogen reduction effect was observed,with NO emissions of 72 mg/ m(6% O),a reduction of about 67% compared to 0% SOFA rate.

国家重点研发计划青年科学家资助项目(2022YFB4100500)

周旭,张瀚霖,张锋,等.高浓度煤粉预燃式强稳燃低氮燃烧器配风组织优化[J].洁净煤技术,2024,30(9):43-51.

ZHOU Xu,ZHANG Hanlin, ZHANG Feng, et al. Optimization of air distribution of high concentration pulverized coalpre-combustion strong stable combustion low nitrogen burner[J].Clean Coal Technology,2024,30(9):43-51.