NUMERICAL SIMULATION OF DENSE PNEUMATIC CONVEYING IN VERTICAL PIPE AT HIGH PRESSURE

摘要

A two fluid model based on the kinetic theory of granular flow was used to study three dimensional steady state flow behaviors of dense phase pneumatic conveying of pulverized coal in vertical pipe, where the average solid concentration ranges from 11% to 30% and the transport pressure ranges from 2.6Mpa to 3.3Mpa. For the solid concentration is rather high, a k-ε-kp-εp model which considers the turbulence interaction between gas phase and particle phase, was incorporated into the two fluid model. The simulation results including profiles of gas and particle phase axial velocity, profiles of solid concentration, profiles of the turbulence intensity of particle phase, as well as the value of pressure gradient were reported. Then, the influences of solid concentration and transport pressure on the flow behaviors were discussed. The experiment was also carried out to validate the accuracy of the simulation results, which showed that the predictions of pressure gradient were in good agreement with the experimental data. The simulation results indicate that the location of maximal solid concentration deviates from the pipe center and the deviation becomes more obvious with the solid concentration increasing. Besides, pressure gradient declines as the transport pressure decreases, which is validated by experiment carried out in the paper. Moreover, the analysis indicates that it is necessary to consider the turbulence of particles for the simulation of dense phase pneumatic conveying.