Velocity and turbulence effects on high intensity distributed combustion
Velocity and turbulence effects on high intensity distributed combustion
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速度和湍流对高强度分布式燃烧的影响
DOI：
10.1016/j.apenergy.2013.11.078
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发表时间：
2014
期刊：
影响因子：
11.2
通讯作者：
A. Gupta
中科院分区：
文献类型：
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作者：
A. Khalil;A. Gupta
高强度分布式燃烧有助于为燃气涡轮机应用提供实质性的性能改进，以同时寻求改进的模式因子、超低NOx和CO排放、低噪声、增强的稳定性、燃料灵活性和更高的效率。在这种燃烧方法中，在混合物点火之前，必须发生喷射的空气、燃料和来自燃烧器内的热反应气体之间的受控混合，以在整个燃烧室中实现分布式反应。以甲烷为燃料，在高放热强度（22-36 MW/m~3atm）的分布式燃烧条件下，实现了NO和CO的近零排放。以污染物排放和燃烧室性能为主要输出参数，通过改变空气喷射速度，进一步研究了燃烧室中形成分布反应的条件。采用粒子图像测速仪（PIV）检查等温流场，以确定与流场相关的关键特征及其对污染物排放和稳定性的影响。结果表明，更高的雾沫夹带和湍流在增加喷射速度。在预混燃料-空气条件下，喷射速度的增加使NO排放降低约20 - 48%，而对CO排放的影响最小。当喷射速度为46 m/s、当量比为0.7、放热强度为31.5 MW/m3atm时，常温空气中NO的释放量小于4 ppm。在相同的操作条件下，高喷射速度使NO排放降低约20%至3.2ppm。在预热的入口空气条件下，较高的喷射速度进一步将NO降低至2ppm（降低48%），当量比为0.5。在非预混燃烧条件下的结果显示出类似的行为。采用单喷射参数的NO的减少归因于在高强度燃烧条件下燃烧区中存在的反应性物种的直接夹带和快速混合的改善的分布式反应条件。
High intensity distributed combustion assists to provide substantial performance improvement for gas turbine applications for our quest to simultaneously seek improved pattern factor, ultra-low emission of NOxand CO, low noise, enhanced stability, fuel flexibility and higher efficiency. In such combustion method, controlled mixing between the injected air, fuel and hot reactive gases from within the combustor prior to mixture ignition must occur to achieve distributed reactions in the entire combustion chamber. Near zero emission of NO and CO has been achieved using methane as the fuel under distributed combustion conditions at high heat (energy) release intensity of 22–36 MW/m3atm. The conditions to form distributed reaction in the combustor are further investigated through variation of air injection velocity with the output parameters focused on pollutants emission and combustor performance. The isothermal flowfield is examined using particle image velocimetry (PIV) to determine key features associated with the flowfield and its effects on pollutants emission and stability. The results showed higher entrainment and turbulence at increased injection velocity. Increase in injection velocity decreased NO emissions by some 20–48% with minimal impact on CO emission under premixed fuel–air condition. Less than 4 ppm of NO was achieved at an injection velocity of 46 m/s at an equivalence ratio of 0.7 and heat (energy) release intensity of 31.5 MW/m3atm using normal temperature air. High injection velocity at the same operating condition decreased NO emission by some 20% to 3.2 ppm. Higher injection velocity under preheated inlet air condition further decreased NO to 2 ppm (48% reduction) at an equivalence ratio of 0.5. The results under non-premixed combustion conditions showed similar behavior. The reduction of NO with single injection parameter is attributed to improved distributed reaction condition from direct entrainment and rapid mixing of reactive species present in the combustion zone under high intensity combustion conditions.