某F级燃气轮机燃烧与NO_(x)排放特性研究

Research on combustion and NO_(x) emission characteristics in a cylinder combustion chamber of an F-class gas turbine

为了给我国F级燃气轮机燃烧系统的燃烧调整与自主升级提供技术参考,以某F级燃气轮机环管燃烧室单筒为三维物理模型,采用Realizable k-ε湍流模型与小火焰生成流形(flamelet generated manifold,FGM)燃烧反应模型,研究了过量空气系数、主旋流叶片偏转角度及值班燃料占比等因素对燃烧室单筒内的温度分布规律、燃烧污染物NO_(x)的生成与排放特性的影响。结果表明:随着燃烧室单筒入口过量空气系数的增加,燃烧室单筒出口的平均温度与最大温度均下降,出口温度分布系数(out-let temperature distribution factor,OTDF)略微上升,出口温度分布均匀性降低,但NO_(x)排放量呈下降趋势;适当增大主旋流叶片偏转角度,可以降低燃烧室单筒内及过渡段出口截面的最高温度并提升温度均匀性,但出口NO_(x)排放量则呈先急剧下降后缓慢上升的趋势;在总燃料流量不变的情况下,值班燃料占比(质量分数)从4%增大到8%时,燃烧室单筒出口温度水平的变化很小,但会导致NO_(x)排放量明显增加。

This work aims to provide technical reference for the combustion adjustment and autonomous upgrade of China’s F-class gas turbine combustion system.Specifically,a full three-dimensional physical model of a cylinder annular combustion chamber in an F-class gas turbine was employed,and the Realizable k-ε turbulence model and the flamelet generated manifold(FGM)combustion model were used to study the effects of the deflection angle of the excess air coefficient,the main swirl vanes and the pilot fuel ratio on the temperature distribution in the single cylinder and the generation and emission characteristics of the combustion chamber.The results show that both the maximum and average temperatures at the outlet surface of the single cylinder reduce with the rise of the excess air coefficient at the inlet of single cylinder.The outlet temperature distribution coefficient(OTDF)increases slightly,and the uniformity of temperature distribution at the exit surface decreased,but the NO_(x) emission shows a downward trend.By appropri⁃ately increasing the deflection angle of the main swirl vanes,the maximum temperature in the combustion chamber and on the outlet surface can be reduced,and the temperature uniformity can be improved,however,the NO_(x) emission shows a trend of first sharp decline and then slows increase.When the pilot fuel ratio increases from 4%to 8%and the total fuel flow remains unchanged,the change of temperature level in the single tube outlet of the combustion chamber is small,but it leads to a significant decrease in NO_(x) emissions.