Combustion Science and Technology, Vol.159, 255-280, 2000
Controlling powdered fuel combustion at low temperature in a new entrained flow reactor
If low temperatures of 800-1000 degreesC are used for the combustion of powdered solid fuels (coal or waste) energy can be produced while at the same time emissions of atmospheric pollutants are minimised. We have developed and precisely characterised an apparatus to determine the kinetic parameters of the potentially limiting reactions (devolatilisation and solid residue oxidation) involved during high heating-rate combustion. The gas phase chemical composition, and structural changes in particles accompanying the combustion can also be followed. Calculation of characteristic time constants and simulation by Computational Fluid Dynamics were necessary to establish heat and mass transfer conditions in which intrinsic kinetic parameters can be assessed with a maximum accuracy. An experimental parametric study of a bituminous coal combustion then demonstrates die accuracy that could be reached. The individual effects of devolatilisation temperature, of atmosphere oxygen content and of particles diameter on the combustion progress are quantitatively characterised.