Camera-probe fuel tracking under industrial fluidized-bed conditions

This work presents direct fuel tracking measurements with a camera probe in an indirect fluidized-bed gasifier with a cross-flow of solids operating at 800°C. From the measurements a lateral dispersion coefficient for fuel is determined to be in the order of 10-2 m2/s at the conditions applied (0.2 m/s), which is consistent with the few previous literature data from industrial units. The camera probe used in this work is cooled by several cooling circuits and the temperature was maintained at a level so that condensation on the front lens was avoided. The direct tracking method yields dynamic data on the location of individual fuel particles but the method is obviously limited by the fact that fuel particles can only be tracked when they are at the bed surface. The effect of devolatilizing particles releasing gases which cause them to float at the dense bed surface previously reported in literature is only observed at the lowest fluidization velocity (0.1 m/s) investigated, but is not evident at the higher velocity (0.2 m/s)