Journal article
Effect of ammonia addition on suppressing soot formation in methane co-flow diffusion flames
Due to issues surrounding carbon dioxide emissions from carbon-containing fuels, there is growing interest in ammonia (NH 3 ) as an alternative combustion fuel. One attractive method of burning NH3 is to co-fire it with hydrocarbons, such as natural gas, and in this case soot formation is possible. To begin understanding the influence of NH3 on soot formation when co-fired with hydrocarbons, soot volume fractions and mole fractions of gas-phase species were computationally and experimentally interrogated for CH4 flames with up to 40% NH3 by volumetric fuel fraction.
Mole fractions of gas-phase species, including C 2 H 2 and C 6 H 6 , were measured with on-line electron impact mass spectrometry, and soot volume fractions were obtained via color-ratio pyrometry. The simulations employed a detailed chemical mechanism developed for capturing nitrogen interactions with hydrocarbons during combustion.
The results are compared to findings in N 2 -CH 4 flames, in order to separate thermal and dilution effects from the chemical influence of NH3 on soot formation. Experimentally, C 2 H 2 concentrations were found to decrease slightly for the NH 3 -CH4 flames relative to N 2 -CH4 flames, and a stronger suppression of C 6 H 6 was found for NH3 relative to N 2 additions.
The measured results show a strong suppression of soot with the addition of NH3 , with soot concentrations reduced by over a factor of 10 with addition of up to 20% or more NH3 by mole fraction. The model satisfactorily captured relative differences in maximum centerline C 2 H 2 , C 6 H 6 , and soot concentrations with addition of N 2 , but was unable to match measured differences in NH3 -CH4 flames.
These results highlight the need for an improved understanding of fuel-nitrogen interactions with higher hydrocarbons to enable accurate models for predicting particulate emissions from NH3 /hydrocarbon combustion.
Language: | English |
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Year: | 2021 |
Pages: | 2497-2505 |
ISSN: | 18732704 and 15407489 |
Types: | Journal article |
DOI: | 10.1016/j.proci.2020.06.094 |
ORCIDs: | 0000-0002-9307-2139 , 0000-0001-6534-6051 , 0000-0002-6820-921X and Dreyer, Jochen A.H. |