Modelling of the combustion limit for methane combustion in a small-scale combustion chamber

1. Modelling of the combustion limit for methane combustion in a small-scale combustion chamber R.Hermansson, J Lindberg Division of Energy Engineering Reduction of emission of carbon monoxide (CO) and volatile organic compounds from small scale combustion furnaces has so far mainly been achieved by research based on trial-and-error methods. This work is both time consuming an costly and to accomplish further improvement a more detailed knowledge about the combustion process and the ability to control it is needed. The limit for sustaining combustion of methane has been studied experimentally in a small-scale combustion chamber. The experimental results have then been compared to Computational fluid dynamics (CFD) simulations with FLUENT 5. Combustion chemistry was described using a one step global reaction model, and the reaction rate calculated both as a function of kinetics and as a function of turbulent mixing. Then the rate of reaction that limits the calculation was used. The conclusion so far is that the reaction model imbedded in FLUENT is not sufficient to describe the combustion process. Studies to find the locations in the combustion chamber where the kinetic reaction rate limits the combustion process are being done. Further new kinetic constants will be developed from experiments and tested in FLUENT to see if it is possible to describe the combustion process using chemical kinetics. Rate of reaction kmolCH4/m3-s The combustion chamber without insulation The research is funded by the Swedish National Energy Administration.