Resistance characteristics of dense-phase pneumatic conveying pulverized coal with various particle size under high pressure

Dense-phase pneumatic conveying experiments of pulverized coal with various particle sizes were carried out at the experimental facility. Based on analyzing the stability and accuracy of experimental system, the influences of the conveying pressure, the coal particle sizes and the conveying velocity on pressure drops of different pipe sections, local pressure drop characteristics and quality of conveying gas were investigated. The results indicate that pressure drops of different pipe sections increase first and then decrease with the increase in conveying velocity. Under a constant mass flow rate and conveying pressure, the larger the mean coal particle sizes are, the greater the pressure drops are. Gas conveying capacity rises but pressure drops and ΔPv-ΔPh decreases with the increase in conveying pressure at the constant solid-gas ratio and conveying velocity. Local pressure drop of bend pipe reduces first and then remains nearly flat with the increase in superficial velocity. There are positive correlations between coal particle size and local pressure drop. The bend equivalent coefficient K which does not relate to the conveying velocity and the solid-gas ratio is affected by the coal particle size and the conveying pressure. The bend equivalent coefficient K increases first and then decreases with the increase in coal particle size.