Combustion chemistry and fuel-nitrogen conversion in a laminar premixed flame of morpholine as a model biofuel

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• 作者：Arnas Lucassen^a ; ¹ ; Nicole Labbe^b ; ¹ ; Phillip R. Westmoreland^c ; ^{phil.westmoreland@ncsu.edu"" rel=""nofollow} ; Katharina Kohse-H&#xf6 ; inghaus^a ; ^{kkh@pc1.uni-bielefeld.de"" rel=""nofollow}
• 关键词：Fuel-nitrogen conversion ; Biofuel ; Premixed flame ; Molecular-beam mass spectrometry
• 刊名：Combustion and Flame
• 出版年：2011
• 出版时间：September 2011
• 年：2011
• 卷：158
• 期：9
• 页码：1647-1666
• 全文大小：2383 K

文摘

The present study has been motivated by the need to understand and predict fuel-nitrogen conversion in the combustion of biomass-derived fuels. Within that broader context, an earlier related publication (Lucassen et al., Proc. Combust. Inst. 32 (2009) 1269–1276) has investigated morpholine (C₄H₉NO, 1-oxa-4-aza-cyclohexane) as a model oxygen- and nitrogen-containing biofuel, and species identification was presented for a slightly fuel-rich Φ = 1.3 (C/O = 0.41) laminar premixed morpholine-oxygen-argon flame at 40 mbar. To attempt a more detailed insight into the flame structure and combustion mechanism, the present contribution has now combined photoionization (PI) and electron ionization (EI) molecular-beam mass spectrometry (MBMS) to determine absolute mole-fraction profiles of numerous major and intermediate species with up to 6 heavy atoms. In general, PI-MBMS and EI-MBMS results were found in good agreement. The results reveal formation of a number of intermediates that may contribute to harmful emissions, including aldehydes and several nitrogen-containing compounds in percent-level concentrations. Both NH₃ and HCN pathways are seen to contribute to NO formation.

To identify reaction pathways for this detailed experimental analysis, development of a flame model was started, considering a combustion mechanism for cyclohexane and analogous fuel-breakdown reactions for morpholine by addition of necessary thermodynamic, transport and kinetic parameters. The present model captures relevant features of the morpholine flame quite well, including HCN, N₂, and NO, and it can serve as a nucleus for further development of detailed combustion models for fuel-nitrogen conversion from model biofuel compounds.