Numerical Modeling and Correlations on The Coal-Conveying Gas Flow in Straight and Curved Pipes
CFD modeling and simulations are made on the key flow elements, vertical, horizontal and elbow pipes used in pneumatic coal-transport system. The coal-particle laden gas flow inside the flow elements are modeled by combining the Reynolds-stress averaged Navier-Stokes equations solver (RANS), k-ε turbulence model and discrete phase model(DPM) of the ANSYS Fluent code. Using the present coal-gas flow analysis model, computations are carried out to investigate the gas flow path, the coal particle behavior and the pressure loss characteristics of flow elements at various coal/gas loading ratio and coal mass flux. The present prediction results show the coal-gas flow behavior of each flow element is changed from dilute-flow to dense-flow pattern at specific coal/gas loading ratio, and this flow pattern transition results in abrupt the increase of pressure loss. The present numerical results also give the correlations for the pressure losses in horizontal, vertical and elbow pipes, from which limiting coal/gas loading conditions to secure stable coal feeding can be obtained.
Keywords: Pneumatic Coal-Transport; Coal-Gas Flow, Dense Phase Flow; Dilute Phase Flow