Effect of exhaust confinement and fuel type upon the blowoff limits and fuel switching ability of swirl combustors
Effect of exhaust confinement and fuel type upon the blowoff limits and fuel switching ability of swirl combustors
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DOI：
10.1016/j.applthermaleng.2012.04.042
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发表时间：
2012-12
影响因子：
6.4
通讯作者：
M. Abdulsada;N. Syred;P. Bowen;T. O’Doherty;A. Griffiths;R. Marsh;A. Crayford
中科院分区：
文献类型：
--
作者：
M. Abdulsada;N. Syred;P. Bowen;T. O’Doherty;A. Griffiths;R. Marsh;A. Crayford
采用预混氢甲烷混合燃料的旋流燃烧器是一种很有前途的低排放发电技术。使用含氢燃料混合物可以产生低排放水平，但众所周知，这有许多困难，主要是因为氢的层流和湍流火焰速度非常高。在需要燃料灵活性的地方，诸如喷出和回火限制等问题是极其重要的。在这项研究中，卡迪夫大学GTRC的通用旋流燃烧器被用来研究预混燃烧器在保持相同热负荷的情况下切换燃料的喷出和能力，用于一系列替代氢基燃料混合物的配置，其中限制是燃气轮机实践的代表。这是对之前关于同一通用燃烧室的工作的补充，在该工作中，重点完全放在回火限制上。理想情况下，为了实现名义上相似的燃烧室几何形状的燃料切换或双燃料，纯氢和天然气的工作点应该位于两种燃料的喷吹和回火极限之间的运行区域。当量比匹配的正常概念需要修改，以考虑到不同燃料混合物的不同化学计量要求以及与之相关的热值差异。在这里，不同燃料的热输入作为质量流量的函数被用来比较它们在预混燃烧室的相同运行、燃料贫化区域中的运行能力。在实践中，这是非常困难的；然而，在带有某些燃料混合物的旋流燃烧器中(氢含量有限)，燃料切换/双燃料是可能的。结果证明并量化了富氢甲烷火焰的喷吹极限的改进。此外，对于所有的几何构型，与非受限情况相比，受限情况下观察到了相当好的排污特性。这一数据为打算使用含氢替代燃料的旋流燃烧室的燃烧器制造商提供了重要的见解。
The use of swirl burners with premixed hydrogen–methane fuel blends is a promising technology for low-emission power generation. Utilisation of hydrogen containing fuel mixtures can result in low-emission levels, but it is well known that there are many difficulties, primarily because of the very high laminar and turbulent flame speeds of hydrogen. Problems such as blowoff and flashback limits are extremely important where fuel flexibility is required. In this study, a generic swirl combustor at Cardiff University's GTRC is utilised to investigate blowoff and the ability of the premixed combustor to switch fuels whilst still maintain the same thermal load, for a range of alternative hydrogen based fuel mixtures in configurations where the confinement is representative of gas turbine practice. This complements previous work on the same generic combustor, where the focus was entirely on flashback limits. Ideally to achieve fuel switching or dual fuelling for nominally similar combustor geometries, the operating points for pure hydrogen and natural gas should lie in an operational regime between the blowoff and flashback limits of both fuels. Normal concepts of equivalence ratio matching need modification to allow for the varying stoichiometric requirements of different fuel mixtures and the associated differences in their heating values. Here heating input from the various fuels as a function of mass flow is used to compare their ability to operate in the same operational, fuel lean regime of the premixed combustor. In practice this is extremely difficult; however, fuel switching/dual fuelling is possible in the swirl burner with certain fuel blends (where the hydrogen content is limited). The results demonstrate and quantify improvements in blowoff limits for hydrogen-enriched methane flames. Moreover, for all geometrical configurations considerably improved blowoff characteristics were observed for the confined cases in contrast to the unconfined cases. This data offers a significant insight to burner manufacturers aiming to use swirl combustors with hydrogen-containing alternative fuels.