Effect of gas type on the fluidization and discharge characteristics of the pulverized coal

The influence of gas type (air, He, H2 and CO2) on the fluidization and discharge characteristics of the pulverized coal was investigated in this paper. It was concluded that the gas viscosity was dominant over the gas density in influencing the fluidization quality. The increase of gas viscosity improved the fluidization uniformity, delayed the visible bubbling and promoted the discharge stability. Compared with air, a higher proportion of H2 rises through the coal bed while a higher proportion of CO2 escapes through the hopper outlet during the discharge process. Experimental results show that the discharge rate increases with the addition of H2 in the whole experimental range and CO2 always corresponds to the minimum discharge rate. In spite of the very different effects produced by the various gases, the relationship between the discharge rate and the pressure difference does not change a lot. Neddermanʹs mode was used to predict the discharge rate, which agreed well with the experimental data with the error kept below 20% except individual points at low aeration rate.