Numerical Simulation of Flow Regime in Dense-Phase Pneumatic Conveying with Different Pulverized Coal Particle Sizes

The key problems of current numerical simulation of dense-phase pneumatic conveying were analyzed in this paper.To solve these problems,a new mathematical model for describing the contact force between particles was proposed,and the dense-phase gas-solid two-phase flow(even when the particles packed)could be simulated by the new model.Based on discrete particle modle(DEM),the new model used the solid phase volume concentration and the characteristics of particle motion to describe the contact force between particles to make sure that the new model can not only simulate dilute phase flow like dispersed flow regime but also dense gas-solid two-phase flow(even when the particles packed).The new model was used to numerically study the flow behaviors of dense phase pneumatic conveying at high pressure.The typical flow regimes,such as slug flow and dune flow which agreed well with experimental results,were obtained,and with the increase of particle size,the flow regime of pulverized coal in dense-phase pneumatic conveying changed into dune flow from sedimentation flow and then changed into slug flow from dune flow.The mean slug length decreased while the average solid concentration in horizontal pipe increased with the increase of particle size.