Flow Characteristics of Dense Phase Pneumatic Conveying of Pulverized Coal through the Bend

Experiments on dense phase pneumatic conveying of pulverized coal were carried out in the self-built pneumatic conveying facility with an industrial pipe diameter of 50 mm. The gas-solid two-phase flow characteristics through the bend were studied. With the help of Enick and Klinzing model, the entrance length of gas-solid two-phase flow in a bend outlet was calculated. It was found that the fluid flow to the electrical capacitance tomography (ECT) was not fully developed, and the fluid was affected by the bend. The flow patterns of the outlet section of the bend were analyzed in the means of ECT, and it was found that the flow pattern changed from the packed bed flow to the unstable/stable plug flow with the increase of the superficial gas velocity. Due to the influence of inertial force and centrifugal force, there was an obvious radial distribution in the concentration of the pipe section when the pulverized coal flowed through the bend, while the coal concentration on lateral wall surface was relatively high. Regression analysis of experimental data was carried out using pressure drop model and dimensional analysis method, a pressure drop model of pulverized coal dense phase pneumatic conveying bend was established by providing errors most smaller than ±10%. Finally, based on micro element analysis and pressure drop distribution along the bend, the distribution characteristics of pulverized coal concentration along the bend were obtained. This work may provide important guiding significance in reducing the wear of bend.