Experimental and theoretical study on hydrodynamic characteristics of tapered fluidized beds

• A novel bottom ash cooler was developed based on a modified tapered fluidized bed.
• Hydrodynamic characteristics of the tapered fluidized bed were studied.
• Effects of some parameters on critical velocities of regime transition were studied.
• A better theoretical model was proposed for the prediction of umf.
• An empirical correlation was developed to predict the umff with high precision.

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.

The hydrodynamic characteristics of a proposed modified tapered fluidized bed were studied. And the effects of some parameters on the critical superficial gas velocity umf and critical velocity for full fluidization umff of the bed were investigated. Furthermore, a theoretical model and an empirical correlation were proposed to predict the umf and umff, respectively.Figure optionsDownload as PowerPoint slide