Simulation of Simplified Model for Reaction Kinetics in Biomass Gasification

Abstract

Due to complexity in interactions between solid particles and between particles and carrier fluid, modeling of biomass gasification kinetics has been shown to be very challenging. Some commercial packages such as Barracuda VR describe the process using a complicated Eulerian-Lagrangian approach of modeling gas - solid multiphase flow. Since chemical reactions play the major role in the gasification process, this paper focuses on a simplified model that describes the influence of reaction kinetics on the process in a bubbling fluidized bed reactor with circulating bed material. The developed model assumes that the system is ideally mixed with a constant bed temperature. Two different set of reaction rate constants are applied to test the model, and their results are compared with that from Barracuda. The model is used to study the effect of steam-biomass ratio on char conversion, and the results show that the conversion of char increases with steam-to-biomass ratio. Sensitivity analysis shows that the output of the model strongly depends on temperature and slightly depends on the bed material particles size.