Moving behavior of pellets in a pellet shaft furnace

The downward moving behavior of pellets in a 8 m2 pellet shaft furnace with an internal vertical air channel and a drying bed was studied by means of a visualized model (1:15) and a top model (1:1). The visualized model experiment shows that the downward movement of pellets can be regarded as plug flow approximately inside the furnace except for the lower region of cooling zone due to the influence of the drained hopper. The top model experiment reveals that the pellet sizes increase along the moving direction because of the percolation phenomenon, which results in a decrease of the resistance coefficient and an increase of the gas flow rate from the furnace wall toward the furnace center.