NUMERICAL SIMULATION OF BIOMASS DERIVED SYNGAS COMBUSTION IN A SWIRL FLAME COMBUSTOR

In this work a numerical investigation is carried out on a model combustor characterized by swirl flow conditions, fed with a biomass derived syngas fuel (which incorporates CH4, CO and H-2) and operated in laboratory at atmospheric pressure. The combustor internal aerodynamics and heat release in case of syngas combustion have been simulated in the framework of CFD-RANS techniques, by means of different available models and by adopting different levels of kinetic mechanism complexity. In particular, the applicability of reduced mechanisms involving CO and H-2 species and also of detailed kinetic mechanisms are assessed. The results obtained by means of the CFD simulations on the model combustor and a comparison with available experimental data on flow field and thermal field are presented in the paper. In the test-case of syngas-air swirled flames, the turbulent non premixed combustion "flamelet" model with detailed non-equilibrium chemistry, originally developed for methane-air combustion, provides encouraging results in terms of temperature distribution. Nevertheless, a simpler chemical path including the main fuel species integrated in a general purpose, widely used in industry, turbulent combustion model still provides acceptable results.