Numerical modeling of the sugarcane bagasse gasification in a fast fluidized bed reactor

Abstract

This article presents results for Thermal Gravimetric Analysis (TGA) tests for sugarcane bagasse drying and devolatilization, for five experimental tests for the gasification of sugarcane pellets in a Circulating Fluidized Bed gasifier pilot plant and for a Computation Fluid Dynamics (CFD) modeling to describe the sugarcane bagasse gasification process. Initially, TGA tests were conducted to obtain kinetic parameters to describe the drying and devolatilization of sugarcane bagasse pellets, providing activation energies for sugarcane bagasse drying and devolatilization. Experimental tests were conducted for a bed temperature of 850 °C, equivalence ratio ranging from 0.25 to 0.29 and for a steam-to-biomass mass flow ratio of 1.0 and 1.2. The kinetic parameters for drying and devolatilization obtained in the TGA tests and a stoichiometric equation proposed here for sugarcane bagasse devolatilization are employed in a CFD code together with kinetic correlations from the literature for the remaining reactions occurring during the gasification process. The conditions of the experimental tests are simulated using a methodology based on a 3D CFD Euler–Euler model to describe the multiphase, multi species, heat, and mass transfer phenomena. Three gasification models are investigated and the predicted syngas composition from numerical simulation is compared with experimental data values. The gasification model with the smallest deviation with respect to the experimental values is used to simulate the other experimental tests and to evaluate the axial behavior quantities of interest.