Influence of Selected Gasification Parameters on Syngas Composition From Biomass Gasification

Abstract

In this study, the syngas composition exiting a biomass gasifier is investigated to determine the effect of varying selected gasification parameters. The gasification parameters considered are the mass flow rate of steam, the gasification agent, the mass flow rate of oxygen, the gasification oxidant, and the type of biomass. The syngas composition is represented by its hydrogen, carbon monoxide, carbon dioxide, and water fractions. The oxygen fed to the gasifier is produced using a cryogenic air separation unit (CASU). The gasifier and the air separation unit are modeled and simulated with aspenplus, where the gasification reactions are carried out based on the Gibbs free energy minimization approach. Finally, the syngas composition for the different types of biomass as well as the different compositions of the three types of the biomass considered are compared in terms of chemical composition. It was found that for each type of biomass and at a specified steam flow rate there is an air to the air separation unit where the gasification of the biomass ends and biomass combustion starts and as the volatile matter in the biomass increases the further the shifting point occur, meaning at higher air flow rate. It was found for the three considered biomass types and their four mixtures that, as the volatile matter in the biomass increases, more hydrogen is observed in the syngas. An optimum biomass mixture can be achieved by determining the right amount of each type of biomass based on the reported sensitivity analysis.