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如何高效洁净地燃烧合成气是整体煤气化联合循环(IGCC)系统中面临的主要问题。利用旋流贫燃预混燃烧可以达到强化传热传质,提高燃烧反应效率,降低NOx等目的,但由于合成气中所含有的H2成分,同样面临燃烧不稳定问题。为了对合成气旋流预混燃烧室的燃烧不稳定性及污染物排放提供理论和数值上的指导,采用大涡模拟方法,对典型的旋流预混燃烧室中的合成气燃烧进行了模拟。结果显示,随着H2含量的增加,火焰缩短向上游发展,燃烧室下游涡破碎更加集中。较高的入口雷诺数,加剧了涡团破碎的程度和速度,同时影响中心回流区和几何回流区的大小及分布。随着当量比的减小,火焰褶皱程度加大,燃烧趋向不稳定。增大压力火焰长度会明显缩短,NOx排放量也会随之增大,但NOx的反应速率只有在较低压力下才会对压力变化比较敏感。
How to efficiently and cleanly combust syngas is a major issue in the integrated gasification combined cycle (IGCC) system. Swirling lean burn premixed combustion can achieve the purpose of enhancing the heat and mass transfer, improving the combustion reaction efficiency and reducing NOx. However, due to the H2 component contained in the syngas, the combustion instability is also faced. In order to provide theoretical and numerical guidance on the combustion instability and pollutant emissions of the synthesis gas swirling premixed combustion chamber, a large eddy simulation method was used to simulate the combustion of syngas in a typical swirling premixed combustion chamber. The results show that with the increase of H2 content, the flames shorten to the upstream and the vortex is more concentrated in the downstream of the combustion chamber. The higher inlet Reynolds number exacerbates the degree and speed of vortex fragmentation, and affects the size and distribution of the central and geometrical recirculation zones. As the equivalent ratio decreases, the degree of flame fold increases, and the combustion tends to be unstable. When the pressure is increased, the length of the flame will be significantly shortened and the NOx emission will also increase. However, the reaction rate of NOx will be sensitive to pressure changes only under lower pressure.