Abstract
The Solid-oxide fuel cell is a highly efficient prime mover for biogas conversion, but a part of biogas needs to be reformulated externally to facilitate the electrochemical conversion, easy control of reforming conditions, and thermal management of the stack. Carbon deposition and external mineralcarrying water should be avoided to ensure the durability of the fuel processor and stack catalysts. This paper investigates four plant layouts with different anode off-gas recirculation schemes and biogas reforming methods: (1) pre-reforming with hot recirculation (HR), (2) pre-reforming with cold recirculation (CR), (3) no pre-reforming and hot recirculation (NR), (4) partial oxidation with hot recirculation (PO). All the schemes feature an electrolyte supported SOFC working at 860°C and 0.23 A/cm2 current density. A sensitivity analysis of the plant efficiency as a function of the Recirculation Ratio (RR) and the Reformer Temperature (RT) is performed. The results show that HR and CR schemes achieve the highest efficiency (58-63%). The HR scheme benefits from the recirculated water and does not require external water for RR > 50% and RT > 600°C; the CR scheme achieves the same result for RR > 80% and RT > 700°C. The optimal RR is within 50 – 80% for the highest system efficiency, as a trade-off between the overall fuel utilization and electrochemistry performance. The RT should be between 600 and 700°C. The HR scheme is the overall best performing if the re-circulator and stack designs do not limit the flow rates at a high RR.
Highlights
SOFCs (Solid Oxide Fuel Cells) have high electrical efficiency [1] compared to traditional systems with low emissions and high fuel flexibility [2,3,4]
The carbon deposition can be eliminated with a feasible operating window extended to a low Reformer Temperature (RT) and Recirculation Ratio (RR)
Four schemes of the biogas fed SOFC plants with different types of anode off-gas recirculation and reformer were compared in this paper with a sensitivity analysis of plant efficiency on the reforming temperature and recirculation ratio
Summary
SOFCs (Solid Oxide Fuel Cells) have high electrical efficiency [1] compared to traditional systems with low emissions and high fuel flexibility [2,3,4]. Biogas-fed SOFC system can produce clean electricity and heat at potentially low costs, boosting the biogas production sites potential. Two factors affect the performance and the durability of biogas SOFC plants: external water supply for biogas reforming, (2) carbon deposition. The minerals in externally supplied water and the carbon formed can deposit reducing catalysts activity and increasing the mass diffusion resistance. A proper system design aims to reduce the dependency on external water while avoiding carbon deposition
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
