(236g) CFD-DEM Model for Predicting Producer Gas Contaminants during Biomass Gasification

Biomass gasification is valuable method for extracting energy in the form of producer gas from biomass. The presence of contaminants in producer gas however creates minor and severe downstream problems. We developed a quasi-3D CFD simulation of biomass gasification using Eulerian-Lagrangian concept in an open source C++ code (OpenFOAM). The particle-particle collisions were described using Hertz-Mindlin particle contact model. Navier-Stokes equation was utilized to resolved the gas flow field variables and turbulence was included through a standard κ-ε turbulence model. The pyrolysis, homogeneous and heterogeneous reactions in the gasifier were considered. Six case evaluating the effects of gasification temperature (790, 934, and 1078 °C) and equivalence ratio (0.15, 0.25, and 0.35) were simulated. The gas and particle flow field variables such as velocity, pressure, and void fractions inside the gasifier were obtained. Also, the concentration of permanent gases (CO, CO₂, H₂O, CH₄, and H₂O) and contaminant gases (NH₃, HCN, and H₂S) inside the gasifier and across the gasifier outlet were obtained. The simulation results were then compared with experimental data from a bench-scale bubbling fluidized bed gasifier.