Adiabatic Reverse Combustion in a Packed Bed
نویسندگان
چکیده
Downward propagation of a combustion front in a packed bed of wood particles, with air supply from below, is examined theoretically and experimentally. Using a single-step reaction, with a kinetic model of char oxidation as the dominant mechanism, and assuming local thermal equilibrium, but allowing a local chemical nonequilibrium between the solid and gas phases, the front speed u F, the adiabatic temperature T r, and the extent of solid consumption ( p ) 7 / ( p )s are determined as functions of the entering air pole-velocity (u)n s. Both oxygen-limited and fuel-limited regimes, with the boundary marked by the stoichiometric burning, are examined. In the oxygen-limited regime, T,., u F, ( p) ,S/( p),s, and the thickness of the front 6F all increase with (u),, g. In the fuel-limited regime, the reverse occurs and the extinction at high (u),, g is predicted. In the oxygen-limited regime, where the bed is not yet fluidized, the experimental results are in good agreement with the predictions.
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