Experimental study of a low pressure stoichiometric premixed methane, methane/ethane, methane/ethane/propane and synthetic natural gas flames

Abstract

This study reports the structure analysis of four laminar stoichiometric premixed CH 4/O 2/Ar, CH 4/C 2H 6/O 2/Ar, CH 4/C 2H 6/C 3H 8/O 2/Ar and CH 4/C 2H 6/C 3H 8/ n-C 4H 10/ i-C 4H 10/ n-C 5H 12/ i-C 5H 12/ n-C 6H 14/O 2/Ar flames. The flames have been stabilized on a flat flame burner at low pressure (40 Torr). Experimental mole fraction profiles of stable and reactive species have been obtained by coupling molecular-beam/mass spectrometry (MB/MS) with gas chromatography/mass spectrometry (GC/MS) analyses. Temperature profiles were measured with a coated thermocouple in the sampling conditions. This work provides a detailed experimental data on the nature and concentrations of the stable and reactive species produced by oxidation of various representative natural gas mixtures. In addition to reactants and major products, the mole fractions of stable intermediate and reactive species have been measured. The experimental results show that ethane and propane, increase significantly intermediate species mole fractions especially olefins. On the other hand, the higher alkanes play a minor role in the oxidation of the natural gas. It appears therefore, that the combustion of methane/ethane/propane mixture represents appropriately natural gas combustion. A qualitative explanation of the experimental observations, based on the current literature mechanisms of alkanes combustion, is reported.