| Abstract | Oxy-fuel combustion technology has become one of the most likely CCUS technologies to achieve large-scale commercial promotion and industrial application because of its remarkable energy-saving effect, low relative economic cost, easy industrialization and many other advantages. Different from traditional air combustion, oxy-fuel combustion technology uses pure oxygen and circulating flue gas as combustion-supporting medium to increase the volume concentration of CO₂ in the exhaust gas to over 90%, which can be directly condensed and compressed to obtain liquid CO₂, thus avoiding expensive separation process, so as to realize the permanent storage or resource utilization of CO₂. In order to optimize the oxy-fuel combustion technology, a humidified oxygenated combustion technology combined with the oxy-steam combustion technology is proposed, which can significantly improve the combustion rate, combustion efficiency and the cycle thermal efficiency, promote the complete combustion reaction, and effectively reduce the emission level of pollutants (NOx and soot). In this work, the combustion characteristics and the generation of main pollutants of steam premixed CH₄ in O₂/CO₂ atmosphere were analyzed by numerical simulation. A new clean combustion method was proposed to study the effects of single variable steam premixed ratio Rf (values 0, 0.1, 0.2, 0.3, 0.4 and 0.5) on the combustion flow field distribution, combustion components distribution and pollutant concentration distribution, by changing the mass fraction of water vapor at mass-flow-inlet while ensuring the methane mass flow rate was fixed. The results showed that with the increase of Rf, combustion reaction rate and combustion reaction efficiency increased and the pollutant emissions decreased, which fully reflected the superiority of steam injection combustion. Based on the simulation results, the optimum atmosphere of methane premixed water vapor was 81% CH₄/19% H2O. Efficient and energy-saving steam premixed CH₄ combustion in O₂/CO₂ atmosphere and flue gas waste heat deep cascade utilization process was proposed, which provided a new idea for the future development of combustion technology.
对O₂/CO₂气氛中甲烷预混水蒸气燃烧特性及主要污染物生成进行了数值模拟研究，在加湿燃烧的基础上提出一种全新的清洁燃烧方式，即在保证甲烷流量一定时，通过改变入口处水蒸气的质量分数，研究水蒸气预混比Rf(0, 0.1, 0.2, 0.3, 0.4和0.5)对燃烧流场、燃烧组分和污染物浓度的影响。结果表明，随Rf增大，燃烧反应速率上升、燃烧效率提高且污染物排放量降低。模拟所得甲烷预混水蒸气的最优气氛为81%CH₄/19%H2O，提出了一种高效节能的O₂/CO₂气氛下水蒸气预混CH₄燃烧与烟气余热梯级利用方案。 |
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