The Discharge of Pulverized Coal from a Pressurized Aerated Hopper

An aerated discharge system was established in this paper to investigate the discharge of pulverized coal from a pressurized aerated hopper. Two opposite effects of aerated gas on solid were first revealed. "Fluidized pressurization", which effectively fluidized the solid and improved the subsequent hopper discharge, was then developed. The effect of hopper pressure on the discharge of pulverized coal was studied. Our experimental results showed that the gas volumetric flow rate increased and the gas superficial velocity decreased with the increase of the hopper pressure in the range of 0-1800 kPa. It was confirmed that more energy was needed; the uncertainty and instability was increased to discharge pulverized coal at higher pressures. Gas momentum flux was defined and used to describe the effect of aeration. The optimum gas momentum flux, which was independent of the hopper pressure, was obtained on the basis of the experimental data. The optimum gas volumetric flow rates and the optimum gas superficial velocities corresponding to the maximum solid discharge rates were further predicted, which agreed well with the experimental data. On the other hand, the hopper pressure also showed a positive effect on the solid discharge, as the maximum solid discharge rate increased gradually with the hopper pressure until a limit value of about 8000 kg/h was reached at 800 kPa.