Experimental and theoretical study on hydrodynamic characteristics of tapered fluidized beds

Abstract

A novel fluidized bed ash cooler was developed for circulating fluidized bed boilers based on a proposed modified tapered fluidized bed. A cold model was built to study the hydrodynamic characteristics of the modified tapered fluidized bed, and its critical superficial gas velocity umf and critical velocity for full fluidization umff were particularly studied. The effects of taper angle α, static bed height H, air inlet section width δ and particle size dp on the umf and umff were experimentally investigated. Furthermore, a theoretical model and an empirical correlation have been proposed to predict the umf and umff, respectively. The predicting capabilities of the model and correlation have been experimentally discussed. And the predicting capability of the model has also been compared with that of an existing representative model. It is found that both the umf and umff increase with the increase of taper angle α, static bed height H and particle size dp, but decrease with the increase of air inlet section width δ, respectively. Additionally, the predicted values of umf and umff compare well with the experimental data, and the model has a better capability than the existing representative model in predicting the umf of the modified bed.