Effects of fuel-staging and reburning on NOx emissions from NH3/CH4/air swirling flames

IF 6.2 2区工程技术 Q2 ENERGY & FUELS

Combustion and Flame Pub Date : 2026-04-01 Epub Date: 2026-02-01 DOI:10.1016/j.combustflame.2026.114816

Shixing Wang , Jingye Chen , Ayman M. Elbaz , Zhihua Wang , William L. Roberts

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引用次数: 0

Abstract

Advanced reburning (AR) is a method utilizes the fuel-staging and thermal de-NO_x to reduce the NO_x emissions in modern coal fired boilers or gas turbines. Ammonia (NH₃) is considered a promising carbon-free fuel in the context of carbon neutrality. However, the emission characteristics of NH₃ swirling flames respond strongly to the influence of reburning and fuel staging. This study investigated the NO_x and unburnt ammonia emissions of NH₃/CH₄/air mixtures in a fuel-staging swirling combustor. The ammonia mole fractions range from X_NH3 = 0.3, 0.6 to 1.0, with the overall equivalence ratios ranging from ϕ = 0.6 to 1.0. Secondary fuel injection ratio, η ranges from 0 to the X_NH3 until the blow-off of primary flame. Three different secondary fuel injection locations (H1/D = 1.7, H2/D = 2.5 and H3/D = 3.4 where D is diamter of burner exit) were adopted to represent different flame temperatures. The secondary fuel injection prevails with a thermal de-NO_x effect for X_NH3 = 0.3 for all η while at X_NH3 = 0.6, secondary fuel injection first reduces NO emissions and then increases the NO emissions η as increases. As the fuel injection height increases, NO reduction is more favored while N₂O emissions and unburnt ammonia gradually appears due to the lower flame temperature and shorter residence time. The comparison of fuel-staging by methane and ammonia is also conducted which shows ammonia-staging is more efficient in reducing NO emissions. NO-PLIF measurements shows a first decrease then increase trend at the highest injection location which is consistent with NO emission measurements. Chemical reactor networks (CRN) analyses indicate that increasing the residence time in the primary reaction zone and decrease the temperature in the secondary reaction zone can efficiently reduce the NO and N₂O emissions. But too low secondary reaction zone temperature can breed large amount of N₂O emission and unburnt ammonia slip. Combining fuel-staging and reburning may be a promising way to achieve very low NO_x and unburnt ammonia emissions in the future.

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燃料分级和再燃烧对NH3/CH4/空气旋流火焰NOx排放的影响

先进再燃（AR）是现代燃煤锅炉或燃气轮机利用燃料分级和热力脱硝来减少NOx排放的一种方法。在碳中和的背景下，氨（NH3）被认为是一种很有前途的无碳燃料。然而，NH3旋转火焰的排放特性受再燃和燃料分级的影响较大。研究了分级旋转燃烧室中NH3/CH4/空气混合物的NOx和未燃氨排放。氨摩尔分数范围为XNH3 = 0.3, 0.6 ~ 1.0，总等效比范围为φ = 0.6 ~ 1.0。二次喷油比，η值为0 ~ XNH3，直至一次火焰熄灭。采用三种不同的二次喷油位置（H1/D = 1.7, H2/D = 2.5, H3/D = 3.4，其中D为燃烧器出口直径）来表示不同的火焰温度。当XNH3 = 0.3时，二次燃油喷射对所有η都有热脱硝作用，而当XNH3 = 0.6时，二次燃油喷射先降低NO排放，然后随着NO排放η的增加而增加。随着喷油高度的增加，NO的还原更有利，而由于火焰温度的降低和停留时间的缩短，N2O的排放和未燃烧的氨逐渐出现。对比了甲烷和氨的燃料分期，发现氨分期在减少NO排放方面更有效。NO- plif测量结果显示，在最高注入位置先降低后增加，这与NO排放测量结果一致。化学反应器网络（CRN）分析表明，增加主反应区停留时间和降低二次反应区温度可以有效减少NO和N2O的排放。但过低的二次反应区温度会产生大量的N2O排放和未燃氨滑。结合燃料分级和再燃烧可能是未来实现极低氮氧化物和未燃烧氨排放的有希望的方法。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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来源期刊

Combustion and Flame 工程技术-工程：化工

CiteScore

9.50

自引率

20.50%

发文量

631

审稿时长

3.8 months

期刊介绍： The mission of the journal is to publish high quality work from experimental, theoretical, and computational investigations on the fundamentals of combustion phenomena and closely allied matters. While submissions in all pertinent areas are welcomed, past and recent focus of the journal has been on: Development and validation of reaction kinetics, reduction of reaction mechanisms and modeling of combustion systems, including: Conventional, alternative and surrogate fuels; Pollutants; Particulate and aerosol formation and abatement; Heterogeneous processes. Experimental, theoretical, and computational studies of laminar and turbulent combustion phenomena, including: Premixed and non-premixed flames; Ignition and extinction phenomena; Flame propagation; Flame structure; Instabilities and swirl; Flame spread; Multi-phase reactants. Advances in diagnostic and computational methods in combustion, including: Measurement and simulation of scalar and vector properties; Novel techniques; State-of-the art applications. Fundamental investigations of combustion technologies and systems, including: Internal combustion engines; Gas turbines; Small- and large-scale stationary combustion and power generation; Catalytic combustion; Combustion synthesis; Combustion under extreme conditions; New concepts.