Influence of Biofuel Blending on Inorganic Constituent Behavior and Impact in Fluidized-Bed Gasification.

Abstract

A promising technology for producing carbon-neutral fuels is fluidized-bed gasification of biomass. In combination with chemical looping gasification (CLG), the process becomes even more efficient. However, using biomass-based fuels can lead to significant ash-related issues, including bed agglomeration, fouling, deposition, slagging, and high-temperature corrosion. To address these issues, several biomass upgrading approaches are used to improve the quality of the feedstock for gasification. These approaches include torrefaction, water leaching, and blending with different additives. This study focuses on the influence of additives and biomass co-blending with low-cost biofuels on the behavior of inorganic constituents and under gasification-like conditions at 950 °C and the corresponding impact in fluidized-bed gasification. For example, blending (upgraded) barley straw with 2 wt % CaCO₃ resulted in a decrease in slag and a corresponding increase in the proportion of solid oxides. This indicates that thermal stability can be expected at operating temperatures up to 950 °C. Similarly, adding Ca/Si-rich biowaste components increases the ash softening point of herbaceous biofuels. Furthermore, the results show that adding Ca-based or woody biofuel components has a chemical effect on the fate of volatile inorganics. For example, increasing the concentration of calcium in the fuel significantly reduces the release of HCl and partially reduces the release of sulfur species, thus reducing the corrosion risk. These results contribute to the development of more efficient and cleaner biomass gasification processes for producing carbon-neutral fuels.