Effect of properties of pulverized coal on dense phase pneumatic conveying at high pressure

Experiments of dense-phase pneumatic conveying of pulverized coal using nitrogen were carried out in an experimental test facility with the conveying pressure up to 4 MPa. The relationship between mass flow rate of pulverized coal with different mean particle size and gas injecting velocity were investigated. Also, the characteristics of pressure drop in the horizontal pipe, vertical pipe and bend with different mean particle size of pulverized coal were analyzed. Test results indicate that, with the increase in total gas flow rate enters into the feeding hopper, the mass flow rate of fine coals reach the peak value earlier than that of coarse coals, but the optimum injecting velocity is lower than that of coarse coals. In addition, it is showed that the pressure drop for coarse coals is higher than that of fine coals with the same mass flow rate, and when the coal concentration in the pipe is higher enough, the conveying pressure drop for fine coal is close to that of coarse coal. The pressure drop in vertical pipe is higher than that in horizontal pipe, and the pressure drop in horizontal pipe is lower than that in horizontal bend with the same mass flow rate.