Numerical Simulation of Gas-solid Two-phase Flows and Ash Deposition in a Wastewater Incineration Heat Recovery Steam Generator

Numerical study of characteristics of ash deposition and distribution in an industrial wastewater incineration heat recovery steam generator was performed using Eulerian-Lagrangian gas-solid two-phase flow model coupled with the deposition model.The Realizable k-e model was used to calculate turbulent flow and radiative heat transfer including the ash particle effect was modeled by discrete ordinates model.Based on viscosity-based empirical model and critical momentum theory,a numerical deposition model combined with discrete random walk model was developed to predict ash sticking/rebounding and detachment of deposited particles from the surface.The results show that particle size plays important role in particle deposition and distribution on different tube surfaces.Large particles subjected to inertial impaction mainly deposit on the windward side of tube surface,while small particles can deposit on both windward and leeward sides.Strong deposition propensity of large particles on the windward side should be responsible for the formation of serious fouling deposits near the entrance of the furnace.In addition,rate of deposition of ash particles increases with increased tube-surface temperature.The results are in good agreement with the experimental data.