Numerical investigation of NOx emission characteristics in air-staged combustion system fueled by premixed ammonia/methane

IF 5.6 2区 工程技术 Q2 ENERGY & FUELS
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Abstract

For the purpose of achieving global CO2 reduction, decarbonization at the source of fuels is a practical approach. The transition phase of blending fossil fuels with carbon-free fuels for combustion is a hot topic in the current carbon emission reduction process. In order to achieve efficient and low-pollution combustion of NH3/CH4, the combustion and emission characteristics of NH3/CH4 under single-stage and air-staged combustion methods were numerically investigated in this work. The emissions were compared for different equivalence ratios and different ammonia content conditions. Rate of production (ROP) and sensitivity analysis were performed for NOx, and the reaction path of NH3/CH4 was analyzed. The results indicate that the C-N interaction of the NH3/CH4 mixed combustion process is not significant and turns weaker in the lean flames. HNO intermediate is an important specie for NO generation, and HCN together with HCO intermediate, are essential species for CO generation. NH2 and NH almost dominate the promotion and inhibition of NO generation. Given the contrasting NOx and CO emission behavior of NH3/CH4 in rich and lean flames, the single-stage combustion approach is not suitable. Air-staged combustion achieves both, ensuring the complete burning of NH3 and CH4 while reducing NOx and CO emissions. Moreover, the results suggest that Φpri = 1.2/Φtotal = 0.6 is the optimal NH3/CH4 combustion staging method for controlling NOx emissions.
以预混氨/甲烷为燃料的空气分级燃烧系统中氮氧化物排放特性的数值研究
为了实现全球二氧化碳减排目标,从燃料源头进行脱碳是一种切实可行的方法。化石燃料与无碳燃料混合燃烧的过渡阶段是当前碳减排过程中的热点话题。为了实现 NH3/CH4 的高效低污染燃烧,本研究对 NH3/CH4 在单级燃烧和空气分级燃烧方式下的燃烧和排放特性进行了数值研究。比较了不同当量比和不同氨含量条件下的排放情况。对氮氧化物的生成率(ROP)和敏感性进行了分析,并分析了 NH3/CH4 的反应路径。结果表明,NH3/CH4 混合燃烧过程中的 C-N 相互作用并不明显,而且在贫焰中会变弱。HNO 中间体是生成 NO 的重要物质,HCN 和 HCO 中间体是生成 CO 的重要物质。NH2 和 NH 几乎主导了 NO 生成的促进和抑制作用。鉴于 NH3/CH4 在富焰和贫焰中的氮氧化物和一氧化碳排放行为截然不同,单级燃烧方法并不合适。空气分级燃烧可同时实现这两个目标,既能确保 NH3 和 CH4 的完全燃烧,又能减少 NOx 和 CO 的排放。此外,研究结果表明,Φpri = 1.2/Φtotal = 0.6 是控制氮氧化物排放的最佳 NH3/CH4 分级燃烧方法。
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来源期刊
Journal of The Energy Institute
Journal of The Energy Institute 工程技术-能源与燃料
CiteScore
10.60
自引率
5.30%
发文量
166
审稿时长
16 days
期刊介绍: The Journal of the Energy Institute provides peer reviewed coverage of original high quality research on energy, engineering and technology.The coverage is broad and the main areas of interest include: Combustion engineering and associated technologies; process heating; power generation; engines and propulsion; emissions and environmental pollution control; clean coal technologies; carbon abatement technologies Emissions and environmental pollution control; safety and hazards; Clean coal technologies; carbon abatement technologies, including carbon capture and storage, CCS; Petroleum engineering and fuel quality, including storage and transport Alternative energy sources; biomass utilisation and biomass conversion technologies; energy from waste, incineration and recycling Energy conversion, energy recovery and energy efficiency; space heating, fuel cells, heat pumps and cooling systems Energy storage The journal''s coverage reflects changes in energy technology that result from the transition to more efficient energy production and end use together with reduced carbon emission.
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