Influence of carbonaceous powders on flow characteristics of dense-phase pneumatic conveying at high pressure

Experiments of carbonaceous powders are carried out to study flow characteristics using a shear tester and conveying facility with pressure up to 4.0 MPa. The effects of powder categories and particle sizes on shear properties, discharge behaviors of feeding hopper and conveying characteristics are investigated. Results indicate that flow property of lignite is the best, followed by bituminous coal, anthracite and petroleum coke are the worst. Flow functions rise with increasing particle size for the same category powder. Mass flow rates increase at first and then decrease with increasing the fluidization number. The optimum fluidization numbers in the feeding hopper distribute at around 4 for the six kinds of conveying powders at high pressure. The influences of fluidization number and particle size on discharge stability of the feeding hopper are analyzed. Pressure drop of the lignite is the least, followed by the bituminous coal, the anthracite and petroleum coke are the largest. Economic velocities distribute at 6-8 m/s for the six kinds of powders at high pressure. The economic velocity of the larger particle is lower than that of the smaller particle. The flow characteristics of the different powders offer the theoretical support for design, control and operation of dense-phase pneumatic conveying at high pressure. (C) 2014 Elsevier Inc. All rights reserved.