微燃机富氧燃烧室NO_x排放的数值研究

Numerical Research on NO_x Emissions of Micro-Turbine Oxygen-Enriched Combustor

对采用烟气循环富氧燃烧方式设计的50 kW微型燃气轮机的低NOx燃烧室,运用数值软件进行了燃烧模拟计算,从入口氧浓度、水分、进口温度等几个方面对组分分布、及NOx生成规律进行了研究。结果表明:燃烧室出口NOx浓度随着入口温度增加、水分减少、入口氧浓度增加而增大。燃烧室内低NOx生成速率等势面充满整个火焰管,高NOx生成速率等势面分布于火焰下游的氧化性氛围增强的过渡区和掺混冷却区。微型燃气轮机燃烧室采用富氧循环烟气预混燃烧方式,不论入口参数如何变化,燃烧室出口NOx排放浓度都小于5×10-5mol/mol,可以实现低NOx清洁燃烧。

The low-NOx combustor of 50 kW micro-turbine is designed in the mode of flue gas recirculation and oxy- gen-enriched combustion, and numerical software is used for its combustion simulation computation. The study focu- ses on composition distribution and NOx formation rule from several aspect such as inlet oxygen concentration, mois- ture and inlet temperature. As the results show, the combustor outlet NOx concentration increases with the increase of inlet temperature and oxygen concentration, and also with the decrease of water. In the combustor the equipotential surface of low NOx formation rate fill the flame tube ; the equipotential surface of high NOx formation rate distributes in the flame downstream transition region and mixing cooling zone where the oxidizing atmosphere enhances. Micro-tur- bine combustor adopts a fully premixed combustion mode of an oxy-fuel gas recirculation no matter how the inlet pa- rameters change. NOx emission concentration at the combustor outlet is lower than 5 × 10 -5 mol/mol, capable of real- izing the clean combustion of low NOx.