School of Energy and Power Engineering, Xi′an Jiaotong University

近年来,天然气低氮燃烧技术层出不穷,然而单一低氮技术的控制效果始终有限。 为实现天然气清洁燃烧和低氮排放,设计了一种集分级燃烧、旋流燃烧和烟气再循环等低氮技术于一体的新型低氮燃烧器,以降低燃烧过程中氮氧化物的生成和排放。 建立了功率 14 MW 的燃烧器模型并对其进行数值模拟计算,分析了不同燃烧器结构和运行参数下燃烧器出口附近温度场、速度场以及氮氧化物(NO)浓度场,探究了混合气体旋流强度和二次风出口速度等因素对低氮燃烧性能的影响,优化该燃烧器的结构和运行参数使其达到最佳低氮性能。 结果表明:优化前的燃烧器可使燃气在出口截面分布均匀并与空气充分混合,出口截面 NO 质量浓度已经低于 30 mg·m-3的低氮排放标准;燃气支管数量优化为 8 根时,高温区的集中度和氮氧化物的排放量最低,出口截面 NO 质量浓度低至 7.61 mg·m-3;一次风和燃气混合气体旋流强度 S0优化为 0.6 时,出口截面 NO 质量浓度低至 5.04 mg·m-3,S0越大,产生的旋流效果越好,炉膛内的烟气内循环效应越明显;二次风出口速度优化到 15~30 m·s-1范围内时,能形成“山”字型的氮氧化物分布特征,有效降低氮氧化物的排放,炉膛出口截面 NO 的平均质量浓度能够降至 4.91 mg·m-3。 优化后的新型低氮燃烧可使 NO 接近零排放,为后续的实验和工程实践提供重要参考。

In recent years, a variety of natural gas low - nitrogen combustion technologies haveemerged, but the control effect of a single low - nitrogen technology is always limited. In order toachieve clean combustion and low -nitrogen emissions for natural gas, a new type of low - nitrogenburner has been designed, integrating low-nitrogen technologies such as stratified combustion, swirlcombustion, and flue gas recirculation techniques. The aim is to reduce the generation and emission ofnitrogen oxides (NOx) during the combustion process. A burner model with a power output of 14 MWwas established, and numerical simulations were conducted to analyze the temperature field, velocityfield, and nitrogen oxide (NO) concentration field near the burner outlet under different burner struc⁃tures and operating parameters. The study investigated the influence of factors such as the swirl intensityof the mixed gas and the outlet velocity of the secondary air on the low-nitrogen combustion perform⁃ance, in order to optimize the burner′s structure and operating parameters for the best low-nitrogenperformance. The results showed that prior to optimization, the burner could distribute the gas uniformlyin the outlet cross-section and mix it sufficiently with air. The NO mass concentration in the outlet cross-section was lower than the low- nitrogen emission standard of 30 mg·m-3. After optimizing the num⁃ber of gas branches to 8, the concentration of the high-temperature zone and the emission of NOx wereat the lowest level, with an NO mass concentration of 7.61 mg·m-3 in the outlet cross-section. Opti⁃mizing the swirl intensity S0 of the primary air and the mixed gas to 0.6 reduced the NO mass concentra⁃tion in the outlet cross-section to as low as 5.04 mg·m-3. Increasing S0 enhanced the swirl effect andthe internal flue gas circulation within the furnace chamber. Optimizing the outlet velocity of the sec⁃ondary air to a range of 15~30 m·s-1 resulted in a "mountain" -shaped NOx distribution characteristic,effectively reducing NOx emissions, and achieving an average NO mass concentration of 4.91 mg·m-3 inthe furnace′s outlet cross-section. The optimized new low-nitrogen burner can lead to near-zero NOemissions, providing an important reference for subsequent experiments and engineering practices.

国家自然科学基金资助项目(51906193)

褚恒, 王登辉, 吴锋, 等. 天然气燃烧器的低氮优化及数值模拟[ J]. 能源环境保护, 2023, 37(5):209-220.

CHU Heng, WANG Denghui, WU Feng, et al. Low-nitrogen optimization and numerical simulation of natural gasburners[J]. Energy Environmental Protection, 2023, 37(5): 209-220.