Numerical study of a low emission gas turbine like combustor for turbulent ammonia/air premixed swirl flames with a secondary air injection at high pressure

Somarathne, Kapuruge Don Kunkuma Amila; Hatakeyama, Sotaro; Hayakawa, Akihiro; Kobayashi, Haruo

doi:10.1016/j.ijhydene.2017.09.089

Cited by 195 publications

(81 citation statements)

References 27 publications

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“…With a small amount of NH 3 (10% in volume), NO emissions grow considerably (from 159 to 827 ppm for ϕ 0.8), reaching a peak between 50% and 60% NH 3 of 3,500 ppm. Moreover, results suggest that the stoichiometry has a major impact on NO formation, confirming literature outcomes from Somarathne et al (2017) and Sorrentino et al (2019). As expected, the minimum NO emission levels were obtained close to stoichiometric conditions.…”

Section: Resultssupporting

confidence: 87%

On the Influence of Kinetic Uncertainties on the Accuracy of Numerical Modeling of an Industrial Flameless Furnace Fired With NH3/H2 Blends: A Numerical and Experimental Study

et al. 2020

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Ammonia/hydrogen-fueled combustion represents a very promising solution for the future energy scenario. This study aims to shed light and understand the behavior of ammonia/hydrogen blends under flameless conditions. A first-of-its-kind experimental campaign was conducted to test fuel flexibility for different ammonia/hydrogen blends in a flameless burner, varying the air injector and the equivalence ratio. NO emissions increased drastically after injecting a small amount of NH3 in pure hydrogen (10% by volume). An optimum trade-off between NOx emission and ammonia slip was found when working sufficiently close to stoichiometric conditions (ϕ = 0.95). In general, a larger air injector (ID25) reduces the emissions, especially at ϕ = 0.8. A well-stirred reactor network with exhaust recirculation was developed exchanging information with computational fluid dynamics (CFD) simulations, to model chemistry in diluted conditions. Such a simplified system was then used in two ways: 1) to explain the experimental trends of NOx emissions varying the ammonia molar fraction within the fuel blend and 2) to perform an uncertainty quantification study. A sensitivity study coupled with latin hypercube sampling (LHS) was used to evaluate the impact of kinetic uncertainties on NOx prediction in a well-stirred reactor network model. The influence of the identified uncertainties was then tested in more complex numerical models, such as Reynolds-averaged Navier–Stokes (RANS) simulations of the furnace. The major over-predictions of existing kinetic scheme was then alleviated significantly, confirming the crucial role of detailed kinetic mechanisms for accurate predictive simulations of NH3/H2 mixtures in flameless regime.

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Section: Resultssupporting

confidence: 87%

On the Influence of Kinetic Uncertainties on the Accuracy of Numerical Modeling of an Industrial Flameless Furnace Fired With NH3/H2 Blends: A Numerical and Experimental Study

et al. 2020

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“…Diffusion combustion has been employed in the prototype bi-fuel combustor due to its flame stability and it has been demonstrated that the equipment can be run using ammonia-kerosene blends at different concentrations [9][10]. FREA and universities leading this research are now at the brink of showing the potential of pure ammonia gas turbine combustion via studies that range from numerical simulations [11] to demonstration studies [12].…”

mentioning

confidence: 99%

Premixed ammonia/hydrogen swirl combustion under rich fuel conditions for gas turbines operation

Valera‐Medina

Guteša²,

Xiao

et al. 2019

International Journal of Hydrogen Energy

205

107

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Energy storage is one of the highest priority challenges in transitioning to a low-carbon economy.Fluctuating, intermittent primary renewable sources such as wind and solar require low-carbon storage options to enable effective load matching, ensuring security of supply. Chemical storage is one such option, with low or zero carbon fuels such as hydrogen, alcohols and ammonia having been proposed.Ammonia provides zero-carbon hydrogen storage whilst offering liquefaction at relatively low pressures and atmospheric temperatures, enabling ease of transportation in a pre-existing infrastructure. Ammonia can also be used directly as a fuel in power plants such as gas turbines to avoid complete conversion back to hydrogen. It is a relatively unreactive fuel, and so it is of interest to explore the potential utilisation of ammonia/hydrogen mixtures. Hence, the goal of this paper is to provide a first assessment of the suitability of a chosen 70%NH3-30%H2 (%vol) blend for utilisation within a gas turbine environment, based on primary combustion diagnostics including combustion stabilityvia OH chemiluminescence -and emissions (NOx and NH3). An established optical generic swirl-burner enabled studies of the influence of equivalence ratio (φ >1), ambient temperature (<484±10 K) and bypass air, with a focus on NOx reduction, one of the main challenges for ammonia combustion. A numerical GT cycle model is developed alongside the experimental investigation. The results demonstrate that the blend has considerable potential as a fuel substitute with reasonable combustion stability and significant reduction of emissions for the cases without bypass air, due to increased chemical reactivity of unburned ammonia. However, emissions are still above those recommended for gas turbine cycles, with a theoretical cycle that still produces low efficiencies compared to DLN methane, highlighting the requirement for new injection techniques to reduce NOx/unburned NH3 in the flue gases whilst ensuring increased power outputs.

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“…Regarding one perspective of clean propulsion that could potentially circumvent some of the challenges discussed above, discussions include hydrogen-rich energy vectors such as, for example, ammonia [127][128][129][130][131][132]. Briefly, among other options for a future hydrogen economy, ammonia -as a carbon-free small moleculerepresents a versatile chemical for flexible use as a fuel in internal combustion engines and fuel cells as well as a thermochemical working fluid as, e.g.…”

Section: Perspectivesmentioning

confidence: 99%

“…Since ammonia also acts as a coolant, it can furthermore contribute to a favorable engine heat management and associated efficiency gains [127]. Combustion of ammonia has been described to be a potential option for power generation [133] as well as air transportation [132], but its performance remains to be seen in comparison to existing technologies [135].…”

Section: Perspectivesmentioning

confidence: 99%

A new era for combustion research

Kohse‐Höinghaus

2019

Pure and Applied Chemistry

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Current topics in combustion chemistry include aspects of a changing fuel spectrum with a focus on reducing emissions and increasing efficiency. This article is intended to provide an overview of selected recent work in combustion chemistry, especially addressing reaction pathways from fuel decomposition to emissions. The role of the molecular fuel structure will be emphasized for the formation of certain regulated and unregulated species from individual fuels and their mixtures, exemplarily including fuel compounds such as alkanes, alkenes, ethers, alcohols, ketones, esters, and furan derivatives. Depending on the combustion conditions, different temperature regimes are important and can lead to different reaction classes. Laboratory reactors and flames are prime sources and targets from which such detailed chemical information can be obtained and verified with a number of advanced diagnostic techniques, often supported by theoretical work and simulation with combustion models developed to transfer relevant details of chemical mechanisms into practical applications. Regarding the need for cleaner combustion processes, some related background and perspectives will be provided regarding the context for future chemistry research in combustion energy science.

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Numerical study of a low emission gas turbine like combustor for turbulent ammonia/air premixed swirl flames with a secondary air injection at high pressure

Cited by 195 publications

References 27 publications

On the Influence of Kinetic Uncertainties on the Accuracy of Numerical Modeling of an Industrial Flameless Furnace Fired With NH3/H2 Blends: A Numerical and Experimental Study

On the Influence of Kinetic Uncertainties on the Accuracy of Numerical Modeling of an Industrial Flameless Furnace Fired With NH3/H2 Blends: A Numerical and Experimental Study

Premixed ammonia/hydrogen swirl combustion under rich fuel conditions for gas turbines operation

A new era for combustion research

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