Influence of steam addition and elevated ambient conditions on NOx reduction in a staged premixed swirling NH3/H2 flame

Pugh, D.; Bowen, Philip John; Valera‐Medina, Agustin; Giles, Anthony; Runyon, Jon; Marsh, Richard

doi:10.1016/j.proci.2018.07.091

Cited by 153 publications

(132 citation statements)

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“…A numerical study was conducted to determine the exhaust gases obtained from the combustion of a 70-30 (mol%) ammonia-hydrogen blend under rich conditions (equivalence ratio of 1.2) and medium swirl (0.8), thus providing details for further thermodynamic analyses of a combustor previously evaluated using these settings [34,39]. Validation of the model was performed using the results from Valera-Medina et al [39] and Pugh et al [34]. Correlations were established between experimental and numerical concentrations of NOx, NH 3 , and H 2 emissions.…”

Section: Methodsmentioning

confidence: 99%

“…Unfortunately, one of the markers that scored the lowest for ammonia was the specific energy of the fuel (MJ/kg), whilst in comparison, hydrogen showed the highest. The approach applied by the group only briefly raised the potential of ammonia-hydrogen blends, which are well-known to be more efficient for combustion purposes whilst having higher specific energies and the potential of the production of hot, unburned hydrogen [34,39]. Simultaneously, hydrogen, a well-known substitute for many power applications, has the potential to generate clean power whilst ensuring the distribution and storage of large renewable energy sources.…”

Section: Work Performed Bymentioning

confidence: 99%

“…for the improvement of the combustion process. Results have led to the recognition of multi-stage combustors capable of reducing ammonia slip and NOx emissions by the recombination of species (i.e., NHx radicals, OH, and O/H pools) at high pressures and inlet temperatures representative of industrial combustion systems [23,34]. These works have preceded the development of new micro generation concepts that, through fueling of ammonia/methane, have controlled NOx emissions using advanced stabilization techniques [35].…”

Section: Introductionmentioning

confidence: 99%

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Numerical Predictions of a Swirl Combustor Using Complex Chemistry Fueled with Ammonia/Hydrogen Blends

et al. 2020

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Ammonia, a chemical that contains high hydrogen quantities, has been presented as a candidate for the production of clean power generation and aerospace propulsion. Although ammonia can deliver more hydrogen per unit volume than liquid hydrogen itself, the use of ammonia in combustion systems comes with the detrimental production of nitrogen oxides, which are emissions that have up to 300 times the greenhouse potential of carbon dioxide. This factor, combined with the lower energy density of ammonia, makes new studies crucial to enable the use of the molecule through methods that reduce emissions whilst ensuring that enough power is produced to support high-energy intensive applications. Thus, this paper presents a numerical study based on the use of novel reaction models employed to characterize ammonia combustion systems. The models are used to obtain Reynolds Averaged Navier-Stokes (RANS) simulations via Star-CCM+ with complex chemistry of a 70%–30% (mol) ammonia–hydrogen blend that is currently under investigations elsewhere. A fixed equivalence ratio (1.2), medium swirl (0.8), and confined conditions are employed to determine the flame and species propagation at various operating atmospheres and temperature inlet values. The study is then expanded to high inlet temperatures, high pressures, and high flowrates at different confinement boundary conditions. The results denote how the production of NOx emissions remains stable and under 400 ppm, whilst higher concentrations of both hydrogen and unreacted ammonia are found in the flue gases under high power conditions. The reduction of heat losses (thus higher temperature boundary conditions) has a crucial impact on further destruction of ammonia post-flame, with a raise in hydrogen, water, and nitrogen through the system, thus presenting an opportunity of combustion efficiency improvement of this blend by reducing heat losses. Final discussions are presented as a method to raise power whilst employing ammonia for gas turbine systems.

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Section: Methodsmentioning

confidence: 99%

Section: Work Performed Bymentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Numerical Predictions of a Swirl Combustor Using Complex Chemistry Fueled with Ammonia/Hydrogen Blends

et al. 2020

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“…While most of gas fuels (e.g. natural gas) don't have much nitrogen in their composition, in the case of the use of N H 3 as a new fuel, N O x formation is feasible [13,14]. The advantages in transportation and storage versus H 2 , together with the existing infrastructure to supply N H 3 , and the fact that potentially can be fully turned into N 2 and H 2 O, make ammonia a desirable option among other fuels for combustion purposes.…”

Section: Introductionmentioning

confidence: 99%

“…However, apart from N O x emissions, there are still issues related to this fuel that need a further research in terms of combustion characteristics, being its high ignition energy and its low flamability some of the drawbacks to tackle [15]. In this sense, some studies have proposed the use of other fuels like H 2 blended with N H 3 (till 50:50 ratios), to improve its oxidation behavior [14,16]. Besides, N H 3 combustion is not completely understood and some experimental issues are still barriers or unresolved.…”

Section: Introductionmentioning

confidence: 99%

High pressure study of H oxidation and its interaction with NO

Colom-Díaz

Millera

Bilbao

et al. 2019

International Journal of Hydrogen Energy

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The present study deals with the oxidation of H 2 at high pressure and its interaction with N O. The high pressure behavior of the H 2 /N O x /O 2 system has been tested over a wide range of temperatures (500-1100 K) and different air excess ratios (λ= 0.5 -6.4). The experiments have been carried out in a tubular flow reactor at 10, 20 and 40 bar. N O has been found to promote H 2 oxidation under oxidizing conditions, reacting with HO 2 radicals to form the more active OH radical, which enhances the conversion of hydrogen. The onset temperature for hydrogen oxidation, when doped with N O, was approximately the same at all stoichiometries at high pressures (40 bar), and shifted to higher temperatures as the pressure decreases. The experimental results have been analyzed with an updated kinetic model. The reaction N O+N O+O 2 N O 2 +N O 2 has been found to be important at all conditions studied and its kinetic parameters have been modified, according to its activation energy uncertainty. Furthermore, the kinetic parameters of reaction HN O+H 2 N H+H 2 O have been estimated, in order to obtain a good prediction of the oxidation behavior of H 2 and N O conversion under reducing conditions. The kinetic model shows a good agreement between experimental results and model predictions over a wide range of conditions.

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Chemical kinetic analysis on influence of hydrogen enrichment on the combustion characteristics of ammonia air using newly proposed reaction model

Singh

Dash

Reddy

2021

Intl J of Energy Research

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Summary In recent years, ammonia has shown great potential for future green fuel. However, ammonia combustion is a challenging task due to its narrow flammability limit, low flame speed, and slow kinetics compared with conventional hydrocarbon fuels. The blending of ammonia with higher reactive fuel such as hydrogen seems a novel alternative to overcome these difficulties. So, a comprehensive study of NH3/H2/air combustion characteristics is necessary. In the literature, numerous ammonia reaction models can be found, but most of them failed to demonstrate good combustion characteristics with NH3/H2/air mixtures. A new NH3/H2/air reaction model is suggested or proposed in the present work by referring to the previously available literature. The newly proposed reaction model consists of 32 species and 259 reactions. Model validation for laminar flame speed and ignition delay time at different operating conditions are performed in this study using the newly proposed reaction mechanism. Also, an extensive chemical kinetic modeling for heat release rate, flame speed and OH sensitivity analysis, reaction pathway analysis, and NOx emission characteristics of NH3/H2/air mixture is studied. The results show that the proposed reaction model closely follows the experimental trends, and lesser inconsistency is observed than the other reaction models compared in this study. All referenced reaction models used in the present work for comparison shows large discrepancies with experimental results of NH3/H2/air combustion, especially more discrepancies are observed at higher hydrogen enrichment conditions. Hydrogen enrichment positively affects the heat release rate intensity and flame speed of NH3/air mixture. Through the addition of hydrogen, the burning velocity of ammonia can be increased up to the level of hydrocarbon fuels, and the combination of ammonia and hydrogen blend can be used as an effective industrial fuel.

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Influence of steam addition and elevated ambient conditions on NOx reduction in a staged premixed swirling NH3/H2 flame

Cited by 153 publications

References 22 publications

Numerical Predictions of a Swirl Combustor Using Complex Chemistry Fueled with Ammonia/Hydrogen Blends

Numerical Predictions of a Swirl Combustor Using Complex Chemistry Fueled with Ammonia/Hydrogen Blends

High pressure study of H oxidation and its interaction with NO

Chemical kinetic analysis on influence of hydrogen enrichment on the combustion characteristics of ammonia air using newly proposed reaction model

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