Effect of flow field for colorless distributed combustion (CDC) for gas turbine combustion
Effect of flow field for colorless distributed combustion (CDC) for gas turbine combustion
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DOI：
10.1016/j.apenergy.2009.09.032
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发表时间：
2010-05
期刊：
影响因子：
11.2
通讯作者：
V. K. Arghode;A. Gupta
中科院分区：
文献类型：
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作者：
V. K. Arghode;A. Gupta
这里研究的无色分布式燃烧 (CDC) 重点关注燃气轮机燃烧应用，因为它具有显着的优势，可大大减少氮氧化物排放、降低噪音，并显着改善模式系数。 CDC 的特点是分布式燃烧反应区，可实现均匀的热场并避免热点区域，从而显着改善模式系数、降低噪音水平并减少氮氧化物排放。在与燃料混合之前，燃烧空气和产物气体之间的混合以形成热且稀释的氧化剂是至关重要的，因此必须确定最合适的混合条件以最小化点火延迟。燃料发生自燃以提供分布式反应燃烧条件。上述要求可以通过不同的燃料和空气喷射配置以及燃烧区内仔细表征的流场分布来满足。这项研究检查了四种不同的样品配置，以实现无色分布式燃烧条件，不显示火焰的可见颜色。它们包括基线扩散火焰配置和提供接近分布式燃烧条件的条件的其他三种配置。对于所有四种模式，使用相同的燃料和空气喷射直径来检查流场配置对燃烧特性的影响。使用数值模拟以及使用全局火焰特征、废气排放、声学特征和热场的实验，对流场和燃料/空气混合的四种不同配置的结果进行比较。数值模拟和实验都是在25kW的恒定热负荷下进行的，使用甲烷作为燃料，在大气压下使用常温空气和燃料。与扩散火焰的基线情况相比，当火焰接近 CDC 模式时，可以观察到更低的 NOx 和 CO 排放、更好的热场均匀性以及更低的声级。当可见火焰特征接近 CDC 模式时，观察到反应区均匀分布在整个燃烧室体积上。
Colorless distributed combustion (CDC) investigated here is focused on gas turbine combustion applications due to its significant benefits for, much reduced NOx emissions and noise reduction, and significantly improved pattern factor. CDC is characterized by distributed reaction zone of combustion which leads to uniform thermal field and avoidance of hot spot regions to provide significant improvement in pattern factor, lower sound levels and reduced NOx emission. Mixing between the combustion air and product gases to form hot and diluted oxidant prior to its mixing with the fuel is critical so that one must determine the most suitable mixing conditions to minimize the ignition delay. Spontaneous ignition of the fuel occurs to provide distributed reaction combustion conditions. The above requirements can be met with different configuration of fuel and air injections with carefully characterized flow field distribution within the combustion zone. This study examines four different sample configurations to achieve colorless distributed combustion conditions that reveal no visible color of the flame. They include a baseline diffusion flame configuration and three other configurations that provide conditions close to distributed combustion conditions. For all four modes same fuel and air injection diameters are used to examine the effect of flow field configuration on combustion characteristics. The results are compared from the four different configurations on flow field and fuel/air mixing using numerical simulations and with experiments using global flame signatures, exhaust emissions, acoustic signatures, and thermal field. Both numerical simulations and experiments are performed at a constant heat load of 25kW, using methane as the fuel at atmospheric pressure using normal temperature air and fuel. Lower NOx and CO emissions, better thermal field uniformity, and lower acoustic levels have been observed when the flame approached CDC mode as compared to the baseline case of a diffusion flame. The reaction zone is observed to be uniformly distributed over the entire combustor volume when the visible flame signatures approached CDC mode.