二次燃料喷射对燃气轮机中低热值燃烧室性能的影响

摘要

针对燃气轮机天然气燃烧室改烧中低热值气所导致的头部流速过快、回流区减小、壁面温度过高等问题，提出从火焰筒横侧实施二次燃料喷射的方案。建立了简化的模型燃烧室，利用计算流体动力学（ CFD）软件和Chemkin软件进行了计算和分析。结果表明，实施二次燃料喷射，能够增大回流区，有效加强空燃掺混。二次燃料喷射对燃烧室总压损失和燃烧效率影响不大，合理分配两级燃料喷射比例，能够有效降低燃烧室壁面温度，同时也能达到较低污染排放。%Aimed at solving the problems result from transforming a natural gas turbine combustor into a Low-Btu gas combustor, such as decrease of the circulation zone and high wall temperature, a secondary fuel injection technique, which was carried out by the flame tube wall, was proposed.A simplified combustor model was established, and a numerical study was carried on by commercial code of Fluent and Chemkin.The results show that the design of secondary fuel injection increases the size of recirculation zone and enhance the mixture.In addition, it has a very small impact on the total pressure loss and combustion efficiency.Rational distribution of the two levels of fuel could effectively reduce the temperature of the tube wall, but also to achieve lower emissions.