Solar gasification of sugarcane bagasse : thermogravimetric analysis of the kinetics of pyrolysis and steam gasification

Solar steam gasification offers an efficient and economic path to provide gaseous, liquid and solid fuels, and prepare chemicals derived from biomass. The thermochemical conversion of the Brazilian sugarcane bagasse in solar-driven gasifiers, can offer an alternative to the sugarcane residue’s currently inefficient usage which is the electrical and thermal energy supply for the sugar and ethanol production. The steam gasification process encloses two consecutive reaction steps: Pyrolysis and steam gasification. Both were experimentally studied by thermogravimetric analysis in order to model their rate laws, which are of fundamental importance for the design of the solar reactor. Kinetic parameters for pyrolysis and steam gasification have been numerically derived: Pyrolysis reaction is modeled as a linear combination of three-pseudo-components following first order decomposition reactions. The model for the steam gasification reaction is based upon the “oxygen-exchange mechanism” type considering reversible sorption of gaseous species and irreversible reactions among adsorbed species and with molecules from the gas phase. Further, the grain distribution model represented by a linear dependency of the unreacted particles was used to account for the structural changes during reaction.