CH4掺混H2的燃烧数值模拟及掺混比合理性分析

本工作针对天然气掺氢燃烧技术在燃气锅炉的最佳掺混比开展数值模拟研究,以小火焰燃烧器为研究对象,计算了在空气氛围、恒定过氧系数、不同甲烷掺混氢气比条件下,掺氢比对燃料燃烧温度、燃烧速率、主要污染物排放浓度的影响.其中燃烧机理采用GRI-MECH 3.0简化机理,该反应包含24个基元反应,涉及17种组分.计算结果表明,随掺...

Numerical simulation of combustion of CH4 mixed H2 and rationality analysis of premixed ratio

The hydrogen-blended combustion technology is a new technology that mixes a specific proportion of hydrogen, in the fuel, to improve combustion efficiency and reduce pollutant emissions. This technology is considered to be an effective method in improving the overall energy produced. The principle of “power to gas” technology is to take advantage of the intermittent nature of both wind-generated and solar energy, by using the surplus energy for the production of hydrogen by the electrolysis of water. The hydrogen can then be combined with carbon dioxide to produce methane, or by direct addition to natural gas in the pipeline network, thus enabling large-scale utilization of hydrogen energy. The rationality of the application of hydrogen-blended combustion technology in gas boilers is based on a simplified mechanism of GRI-MECH 3.0 of methane combustion. This reaction contains 24 elementary reactions involving 17 components. In this work, a numerical simulation experiment was designed, where atmospheric air was the oxidant, and the oxygen excess coefficient was maintained as a constant. A total of eleven groups of methane/hydrogen premixing ratios Rf (0~1) were considered and the effects of differing hydrogen blending ratios on fuel combustion temperature, combustion rate, and main pollutant emission concentrations were studied. The results showed that, by increasing the hydrogen blending ratio, both the combustion temperature and the reaction rate increased. Similarly, the concentration and the total emissions of soot and CO decreased, while the concentration of NOx increased, however, the total emissions decreased first then increased. The mechanisms relating to the effect of hydrogen mixing on the combustion process and the resultant pollutant formation were also analyzed, concerning China's urban fuel gas interchangeability regulations and industrial pollutant emission standards, the optimal hydrogen blending ratio was determined to be 23%.