Unraveling the NO reduction mechanisms occurring during the combustion of NH3/CH4 mixtures

Alzueta, María U.; Abián, María; Elvira, I.; Mercader, Víctor D.; Sieso, L.

doi:10.1016/j.combustflame.2022.112531

Cited by 18 publications

(25 citation statements)

References 49 publications

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“…In all studied cases of NH 3 oxidation, NH 3 starts to be consumed by reaction (R2) as well known in the literature. 12,13,53 Figure 5 e,f, shows the repeatability of sets 17, 22 and 17R, 22R conditions, respectively. As for CH 4 , the reproducibility of the experiments is very good in all the temperature range considered.…”

Section: ■ Kinetic Modelingmentioning

confidence: 99%

“…At the same time, NH 3 could potentially be a future NO x -free fuel under specific operating conditions as Shu et al 11 conclude, since ammonia can interact under specific conditions (fuel-lean conditions) within the combustion chamber with NO, effectively minimizing its concentration through selective noncatalytic (SNCR) reactions. 10−14 In this way, ammonia can react with NO by the following mechanisms (NH 3 → NO → NNH → N 2 and NH 3 → NO → N 2 ) within the combustion chamber, as pointed out by Alzueta et al 12 through reactions (R2−R5):…”

Section: ■ Introductionmentioning

confidence: 99%

“…Under locally fuel-rich conditions within the combustion chamber, CH 4 also can reduce the NO concentration, mainly by reburn reactions. 12 In the NH 3 /CH 4 mixtures, the reburn reactions occur through the generation of hydrocarbon radicals at high temperatures and fuel-rich conditions, which are able to interact with NO, through reactions (R6,R7), 17 involving the methyl radical formed from methane (R8): The intermediate species HCN and H 2 CN formed will be converted to N 2 or NO within the combustor chamber under specific conditions. The combined use of ammonia and methane can be beneficial for NO x reduction through the two mechanisms described above, namely, SNCR and reburn.…”

Section: ■ Introductionmentioning

confidence: 99%

“…6,8,11,12,14,16,18,20−25,27−30,32,34−36,39−43 It is important to mention as well that some studies at atmospheric pressure focused on determining the effects of NO concentration on ammonia chemistry during NH 3 /CH 4 mixtures oxidation. 12,22,27,40 Also, the effects of CO/CO 2 are also studied on NH 3 oxidation in a flow reactor with the aim of addressing possible oxy-fuel combustion strategies. 18,27,44−46 From a practical point of view, pressure is an important variable since turbines and certain engines will operate under high pressure conditions.…”

Section: ■ Introductionmentioning

confidence: 99%

“…However, ammonia presents some challenges for its practical implementation associated with its poor combustion characteristics, such as its high ignition temperature and low flammability, , potential NO x emissions, and a low laminar burning velocity which is about five times lower compared to CH 4 /air flames . Thus, the addition of CH 4 can improve the combustion characteristics of ammonia, because it can provide a higher flame speed, and a higher thermal efficiency at the same time.…”

Section: Introductionmentioning

confidence: 99%

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Experimental and Modeling High-Pressure Study of Ammonia–Methane Oxidation in a Flow Reactor

García-Ruiz,

Salas,

Casanova

et al. 2024

Energy Fuels

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The present work deals with an experimental and modeling analysis of the oxidation of ammonia−methane mixtures at high pressure (up to 40 bar) in the 550−1250 K temperature range using a quartz tubular reactor and argon as a diluent. The impact of temperature, pressure, oxygen stoichiometry, and CH 4 / NH 3 ratio has been analyzed on the concentrations of NH 3 , NO 2 , N 2 O, NO, N 2 , HCN, CH 4 , CO, and CO 2 obtained as main products of the ammonia−methane mixture oxidation. The main results obtained indicate that increasing either the pressure, CH 4 /NH 3 ratio, or stoichiometry results in a shift of NH 3 and CH 4 conversion to lower temperatures. The effect of pressure is particularly significant in the low range of pressures studied. The main products of ammonia oxidation are N 2 , NO, and N 2 O while NO 2 concentrations are below the detection limit for all of the conditions considered. The N 2 O formation is favored by increasing the CH 4 / NH 3 ratio and stoichiometry. The experimental results are simulated and interpreted in terms of an updated detailed chemical kinetic mechanism, which, in general, is able to describe well the conversion of both NH 3 and CH 4 under almost all of the studied conditions. Nevertheless, some discrepancies are found between the experimental results and model calculations.

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Section: ■ Kinetic Modelingmentioning

confidence: 99%

Section: ■ Introductionmentioning

confidence: 99%