Eventos Anais de eventos
ENCIT 2022
19th Brazilian Congress of Thermal Sciences and Engineering
BOUDOUARD, REFORMING OF CHAR AND METHANATION REACTION EVALUATION BY CFD SIMULATIONS OF FLUIDIZED-BED REACTOR FOR GASIFICATION
Submission Author:
Vitor Alberto Lemes Monteiro , MG , Brazil
Co-Authors:
Vitor Alberto Lemes Monteiro, Alam Trovó, Marcelo Braga dos Santos, Solidônio Carvalho
Presenter: Solidônio Carvalho
doi://10.26678/ABCM.ENCIT2022.CIT22-0409
Abstract
The gasification in fluidized-bed reactor is an important subject related to Waste to Energy systems. There are still no ready solutions for fast and reliable simulations in designing or controlling such units. In this context, the objective of this work is to develop a model to evaluate some heterogeneous reactions among the subprocesses of the gasification operation. Such reactions are part of the thermal degradation of biomass and are quite especial due to its phase conversion, from solid to gas. The Eulerian-Eulerian approach was applied to a computational fluid dynamic system to simulate Boudouard, Reforming of Char and Methanation reactions. A bubbling fluidized-bed reactor containing silica sand as bed material was modelled with a determined gas injection (CO2, H2O and H2) for the simulation of the gasification process of a generic carbonaceous biomass. In this way, was possible to observe the conversion of solid phase and subsequent formation of the gaseous products of each reaction separately and in competing set. The mass balance of each specie was analysed with the outlet releases considered. The biomass consumption and conversion from the solid phase to gaseous products was modeled through a single step first-order Arrhenius reaction of char consumption rate. Reynolds-Averaged Navier-Stokes was used with k-ε turbulent modeling. The Ranz Marshal heat exchange model of between phases, Gidaspow drag model and Kinetic Theory of Granular Flows was implemented to the balance equations. All simulations were performed using OpenFOAM software. The reactor was maintained at 1093 K and all thermophysical properties were acquired by Sutherland’s Law and JANAF Thermochemical Tables. The results show quantitively consistent progression of thermal degradation process in terms of biomass solid phase transformations into gas. This detailed evaluation of such reactions is important for the authors research line studies, which includes a development of a large-scale reactor for gasification of municipal refuse-derived fuel in fluidized bed.
Keywords
devolatilization, heterogeneous reactions, renewable energy, Bubbling Fluidized Bed, multiphase flow
