Influence of CO₂ Injection on Biomass Gasification

Abstract

The impact of CO 2 cofeed (0−50% by volume) on steam gasification of biomass was investigated via thermogravimetric analysis−gas chromatography (TGA-GC). H 2, CO 2, CO, and CH 4 gas evolution as a function of temperature were quantified for various S/C and CO 2 /C ratios. CO evolution enhancement became significant at temperatures above 700 °C for all woods and grasses studied. H 2 evolution began at temperatures above 450 °C and began to decline above 700 °C. All samples had similar mass decay curves that were completed by 900−1000 °C and were independent of the amount of CO 2 injection. Improved char conversion was observed when CO 2 was present. The biomass fuels and their ash residue were analyzed using atomic absorption spectroscopy (AAS) and scanning electron microscopy/energy dispersive X-ray analysis (SEM/EDX). A significant amount of highly corrosive ash residues were observed with no CO 2, yet much smaller volumes were observed when CO 2 was present. Finally, the experimental data was compared to ASPEN simulations to understand the influence of CO 2 recycle for carbon based fuels, and they showed good agreement.