Analysis of Syngas Quality from Portuguese Biomasses: An Experimental and Numerical Study

A comprehensive two-dimensional multiphase model was developed to describe the gasification of three large available Portuguese biomasses in a pilot scale fluidized bed gasifier within the computational fluid dynamics Fluent framework. An Eulerian-Eulerian approach was implemented to handle both the gas and the dispersed phases. The kinetic theory of granular flows was used to evaluate the constitutive properties of the dispersed phase, and the gas-phase behavior was simulated employing the k-epsilon turbulent model. Devolatilization phenomenon was also modeled. Results from the numerical model were later compared with experimental data also gathered for the three Portuguese biomasses. The simulated syngas compositions are in good agreement with the experimental results with maximum deviations of 20% (considering all simulations and biomasses). The effect of the gasification temperature and steam-to-biomass ratio on the syngas composition was evaluated as well as the cold gas efficiency, H-2/CO ratio, CH4/H-2 ratio, and carbon conversion. From this analysis, it was possible to define which biomass has the greater potential to be used concerning the selected application. Among the three biomasses, it was concluded that coffee husks and vine-pruning residues show better H-2/CO ratios, while the higher CH4/H-2 ratios are obtained by using the forest residues. The highest cold gas efficiencies were obtained by using the vine-pruning residues. These data are crucial to describe scenarios concerning the potential use of biomass as a source of energy in Portugal.