Controlling powdered fuel combustion at low temperature in a new entrainedflow reactor

If low temperatures of 800-1000 degreesC are used for the combustion of pow dered solid fuels (coal or waste) energy can be produced while at the same time emissions of atmospheric pollutants are minimised. We have developed a nd 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 chem ical composition, and structural changes in particles accompanying the comb ustion can also be followed. Calculation of characteristic time constants a nd simulation by Computational Fluid Dynamics were necessary to establish h eat 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 rea ched. The individual effects of devolatilisation temperature, of atmosphere oxygen content and of particles diameter on the combustion progress are qu antitatively characterised.