ROLE OF FUEL REACTIVITY IN FLUIDIZED-BED COMBUSTION

This paper reports the use of the two-phase bubbling fluidized-bed model for calculations of the conditions in fluidized-bed combustors. The model takes account of the sequential steps of oxygen transport from bubble to dense phases, transport through the dense phase, and finally reaction with the fuel particle. At 1200 K, for practical conditions of pressure, fluidizing velocity, particle size, bed voidage and bubble size, fuel reactivity was sufficiently high, and bubble-to-dense phase transport sufficiently rapid, to ensure that neither of these steps had a notable rate-controlling effect. Transport through the dense phase was of most influence. However, some effect of reactivity was shown at 1000 K, and a strong effect occurred at 800 K. The model proved to be markedly sensitive to the carbon concentration in the bed, bubble size, and particle size. © 1979.