(628e) Multi-Phase CFD Simulation of a Downdraft Biomass Gasifier

Authors: 
Boravelli, T., Missouri University of Science and Tech

A reliable, affordable clean energy supply is of primary importance for the economy and the environment and will prove to be pivotal in the 21st century. Biomass energy which is now accepted as a propitious alternative includes a widely available, sustainable and as a neutral CO2 resource, suited for modern applications for electricity generation, fuels and chemicals.

A 2D and 3D Mathematical model is developed to understand the configuration in a fixed bed biomass gasifier considering drying, pyrolysis, combustion and gasification reactions. The CFD simulation is based on the down draft biomass gasifier design run by Energy Research and Development center at Missouri University and Science and Technology, Rolla. A multi-phase Computational Fluid Dynamics model will be developed and verify against experimental setup. The flow model is based on an Eulerian –Eulerian description of the phases where the kinetic theory of granular flow forms the basis for the turbulence modelling in the solid phases and standard к-ε turbulence model for gas phase.

Influence of the air ratio on gasification performance, such as production of syn gas, amount of char produced, and cold gas efficiency is presented with regard to the gasifier. The gas temperature distribution and product gas composition will also be considered into account. A comparison between the simulation and experimental data will be shown to accurately identify the simulation, confirming the validity of the current model.