Solving the microwave heating uniformity conundrum for scalable high-temperature processes via a toroidal fluidised-bed reactor

Rodriguez, Jose; Morona, Lorena; Erans, Maria; Buttress, Adam J.; Nicholls, Matt; Batchelor, Andrew R.; Duran-Jimenez, Gabriela; Kingman, Sam; Groszek, Daniel; Dodds, Chris

Abstract

Challenges exist to implementing high-temperature microwave processes with changing dielectric properties that achieve uniform processing. This paper presents a new high-temperature hybrid microwave processing system which overcomes these challenges in a robust, scalable way, integrating a slotted waveguide ring microwave feed into a toroidal fluidised bed reactor and maintaining its fluidisation behaviour. The prototype operates at a frequency of 2450 MHz with a maximum power of 10 kW and within a temperature range of 50-300°C, though it is scalable to industrial levels. Electromagnetic simulations of the system were experimentally validated using a range of agri-crop feedstocks. Hydrodynamic and thermodynamic reactor characterisation was performed, and treatment performance was quantified regarding surface bed temperature variation. Excellent treatment uniformities were found under microwave and hybrid regimes, with a temperature coefficient of variation (CoV) across the bed's surface below 2 %, an order of magnitude better than existing microwave processes, generally regarded as highly uniform with CoV of approximately 20 %. The integration of microwaves and toroidal fluidised beds, without exposed moving parts, potentially unlocks a range of applications previously inaccessible to microwave technology or fluidised bed technologies on their own. Future work involves process development, techno-economic studies, and large-scale pilot trials.

Citation

Rodriguez, J., Morona, L., Erans, M., Buttress, A. J., Nicholls, M., Batchelor, A. R., Duran-Jimenez, G., Kingman, S., Groszek, D., & Dodds, C. (2024). Solving the microwave heating uniformity conundrum for scalable high-temperature processes via a toroidal fluidised-bed reactor. Chemical Engineering and Processing: Process Intensification, 202, Article 109838. https://doi.org/10.1016/j.cep.2024.109838

• Journal Article Type: Article
• Acceptance Date: May 28, 2024
• Online Publication Date: May 29, 2024
• Publication Date: 2024-08
• Deposit Date: May 30, 2024
• Journal: Chemical Engineering and Processing - Process Intensification
• Print ISSN: 0255-2701
• Publisher: Elsevier
• Peer Reviewed: Peer Reviewed
• Volume: 202
• Article Number: 109838
• DOI: https://doi.org/10.1016/j.cep.2024.109838
• Keywords: Microwave heating, Hybrid heating, Fluidised bed, High temperature, Thermal processing, Electromagnetic modelling
• Public URL: https://nottingham-repository.worktribe.com/output/35437220
• Publisher URL: https://www.sciencedirect.com/science/article/pii/S0255270124001764?via%3Dihub