For clarifying the aerodynamical behavior of unburnt coals in the cohesive zone in a blast furnace with high coal injection rate, two dimensional flow characteristics of powders in packed beds were analyzed by using a mathematical model. Following results were obtained.
(1)Unburnt coals tended to be concentrated at the lower part of cohesive zone. They deposited nearer the wall for reverse-V shaped cohesive zone compared to W shaped cohesive zone.
(2)As a results of the sedimentation of unburnt coals in the furnace, peripheral gas flow was suppressed in reverse-V profile and enhanced in W profile.
(3)Blockade occured in the lower part of cohesive zone and the shape of cohesive zone affected the pulverized coal injection rate at which blockade occured.
