Gas-particle Flow Modeling: Beyond the Dilute Limit

The flow of pulverized fuel in a power plant is one example of gas-particle flows in the energy and process industries. Computational Fluid Dynamics (CFD) is a widely used trouble shooting and engineering design tool increasingly deployed within industry to predict the behavior of such flows. Despite wide use, traditional models are often inadequate for solving industrial problems. An example is the concentration of the particulate phase within a coal burner's fuel feed due to particle inertia and inter-particle collisions. This local concentration of the particles can be advantageous, but it is difficult to characterize the flow beyond the dilute limit (volume fraction of 0.001). To address this and other short comings a number of two-phase flow models have been investigated and their applicability and accuracy assessed by comparison with experiments in the literature for a vertical pipe flow with relatively high mass loadings of the discrete phase. The physics investigated includes: particle-wall collisions, particle-particle collisions and structure dependent drag. Models have been implemented in the commercial CFD software ANSYS FLUENT R. 14.5 for the Discrete Phase Model. The results show a significant improvement over industry best practice and provide an indication as to the key physics and the effects of scale on confined gas-particle flows. Furthermore, the modeling approach will be applicable in a number of other industrial areas, such as biomass conveying. This paper provides an overview of CFD models for the application to pulverized fuel flows within a coal fired power plant and discusses the gap between academic development and industrial adoption of advanced CFD models. Crown Copyright (C) 2015 The Authors. Published by Elsevier Ltd.