Numerical Simulation on Dune Flow in Pressurized Dense Phase Pneumatic Conveying of Pulverized Coal in Horizontal Pipe

Modifications were made for the frictional normal stresses model proposed by Johnson et al.and the frictional shear viscosity model proposed by Syamlal et al.Combining the modified model with the kinetic theory for granular flow,a 3-D multi-phase flow model was built up for gas-solid turbulent flow in pressurized dense phase pneumatic conveying.The model sufficiently took account of the collision and friction action among particles,and the interaction among gas phase and turbulent fluctuation of particles.The model was used to carry out the 3-D numerical simulation for the dune flow characteristics in pressurized dense phase pneumatic conveying in a horizontal pipe.The formation and motion process of the single dune and the continuous dunes were predicted.Results show that with the increase of apparent gas velocity,the concentration of pulverized coal decreases,and the pressure drop gradient decreases at first and then increases.On the cross section,the distribution of pulverized coal appears to be narrow on the upper part and broad on the lower part.Besides,there are coal particles deposited on the bottom of the pipe to form the dune.The simulated results agree well with the test results.