A systematically reduced reaction mechanism for sulphur oxidation

The recent renewal of interest in high temperature sulphur chemistry is driven by the necessity to limit noxious emissions and to optimize sulphur removal processes in the petroleum industry. Turbulent plumes from aircraft are of interest in the context of contrails. In chemically reacting flows deviating from the high Damkohler number limit, account must be taken of chemical kinetic effects, and their inclusion into multi-dimensional and/or turbulent calculation methods necessitates the development of simplified mechanisms. In the present work, detailed and systematically reduced mechanisms for sulphur oxidation are derived and validated against flow reactor, jet-stirred reactor, and laminar premixed flame data where sulphur-containing Compounds are used either as fuels or as seeding. Computations featuring a C/H/O/N/S mechanism suggest that C/S interactions are not strong in the cases studied and a 10 species and 51 reaction skeleton sub-mechanism is formulated. The latter is subsequently systematically reduced to 5-step mechanism featuring H2S, SO, SO2, SO3, and SH as independent scalars. A further reduction to a 4-step mechanism is also proposed through the elimination of SH as a solved species. Path analyses suggest that interactions between sulphur species and oxides of nitrogen are only important in a radical depleted environment. Computed results are in good agreement with experimental data and differences between the detailed and reduced mechanisms are small over a wide range of conditions. (c) 2004 The Combustion Institute. Published by Elsevier Inc. All rights reserved.