DETAILED MODELING OF THE FLASH HYDROLYSIS OF ALGAE FOR BIOFUEL PRODUCTION

Abstract

DETAILED MODELING OF THE FLASH HYDROLYSIS OF ALGAE FOR BIOFUEL -PRODUCTION IN COMSOL MULTIPHYSICS Noah Joseph LeGrand Old Dominion University, 2020 Director: Dr. Orlando M. Ayala Algae-derived biofuels are being commercialized as an important renewable energy source. Like any new technology, conversion improvements are desired, including reductions in process complexity and better utilization of the entire microalgae feedstock. The Old Dominion Biomass Laboratory has focused on flash hydrolysis for algae biofuel production. That process involves rapidly heating algae and water mixed as a slurry to a subcritical state. Results from small-scale bench tests are promising, but process scale up is a challenge. Currently there exists a pilot laboratory scale system utilizing induction heating in order to reach controlled reaction temperatures with a reaction duration of 10 seconds or less. However, the influence of the induction heating process on the resulting reactions had not been examined. That is the focus of this thesis. The pilot flash hydrolysis reactor system has been simulated utilizing COMSOL Multiphysics 5.1. The COMSOL model assumed fully developed laminar slurry flow with an electromagnetic field, rate sensitive chemical reactions, and diffusive transport of dilute species. Mesh refinement analysis, mass and energy balances, and experimental verification have been utilized to validate the model. This study has shown that industrial scale up challenges will include sensitivity to feedstock channel size, induction coil pitch, length and excitation frequency, process residence time, and algae concentration. Furthermore, process efficiency improvement may be possible by thermal management of the rapid heating and subsequent quenching process.