Pyrolysis is coming online as a viable pathway for converting solid biomass to renewable biofuels and materials to replace fossil-based sources. The scientific literature emphasizes small-scale conversion of biomasses. Currently, we have limited knowledge on how pyrolysis yields and products change when pyrolysis is moved from benchtop to pilot to industrial scale. This study investigates the impact of scaling on the pyrolysis of rice husks from laboratory reactors to a pilot-scale kiln to understand how to adapt academic findings to industry-scale conversions. Rice husk was pyrolyzed to generate biochar at three different scales: (1) in a thermogravimetric analyzer (TGA) at mg scale; (2) in a fixed bed furnace at g scale; (3) a pyrolysis kiln in kg/hr scale. Proximate analysis was used to compare the composition of volatile matter, fixed carbon, and ash of each biochar to understand the degree to which scale impacts overall devolatilization behavior. The biochar yield was negatively correlated with the increase in pyrolysis scale, indicating that the smaller scales benefited from more rapid heat transfer. The smaller-scale experiments benefited from efficient vapor removal, preventing secondary reactions and tar recondensation. The decreased biochar yield at smaller scales was a direct result of a lower volatile matter fraction (as the biochar has a higher fixed-carbon and ash content). These data suggest that, despite scaling the gas sweep flow rates proportionally across systems, that scale-up may require higher gas flow rates to maximize biochar properties. On-going work is exploring the surface chemistry via FTIR and the BET surface area to probe how scaling impacts pyrolysis chemistry and porosity development.

Impact of upscaling on Pyrolysis Biochar yield and characteristics using rice husk as a case study

Fall 2022 abstracts, posters, and presentations will launch in mid-September.

ACS Fall 2022

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.