Multiphase Flow Analysis of Hydraulic Conveying of Coal Reject from Pulverized Coal Combustion

A hydraulic conveying system utilizing a jet pump is commonly employed for the transportation of coal rejects from the PCCB (pulverized coal combustion boiler) unit. This study applies CFD (computational fluid dynamics) combined with the DEM (discrete element method) to simulate solid-liquid two-phase flow in the jet pump. The coal reject particles were modeled as perfect spheres with a diameter 55 mm a mass flow rate of 5 kg/s. The hydraulic jet pump was supplied with water at a pressure of 12 bar and a flow velocity of 3 m/s. The diameter of nozzle was varied at 26-, 36-, 46-, 56-, and 66 mm to evaluated the effects on particle velocity, residue buildup, and the flow characteristics. The simulation results indicate that increasing the nozzle diameter leads to lower particle velocities and decreases the amount of coal reject residue in the jet pump. The nozzle diameter also influences to the multiphase flow behaviors in the outlet pipe.