This thesis project investigates the granular flow of wood pellets inside a pilot-scale rotary kiln and its impact on the pyrolysis process. The study focuses on two key factors that must be determined to evaluate their effects on pyrolysis: the mass flow rate delivered by the feeding system at different motor frequencies and the mean residence time (MRT) of the wood pellets. The research is divided into two parts: the first characterizes granular flow without heat application, while the second examines the system behavior under high-temperature pyrolysis conditions. For the first part, the mass flow rate was assessed by measuring the emptying time of the feeding silo at different screw velocities. In contrast, the MRT was determinedwith two scenarios: (1) batches of different masses of wood pellets and (2) continuousfeed until a stable solid bed was formed that allowed tracer particle tracking. In the second part of the study, the drum’s rotational speed and fed mass flow rate were varied. Results indicated a direct proportionality between the mass flow rate delivered by the feeding systems and the screw motor frequency. Additionally, the MRT was found to follow an inverse relation with the drum’s rotational speed if the process was done in batches. In contrast, the MRT was 20 minutes at a feeding rate of 51 kg h-1 and a drum’s rotational speed of 0.36 rad s -1 with a continuous feeding process. Finally, the study concludes that the wood pellet feed rate and drum rotational speed significantly influence the pyrolysis process in the rotary kiln. The system remained stable for wood pellets inside the rotary drum, starting with a feeding rate of 8 kg h-1 and scaling up until a maximum of 21 kg h-1. This behavior is evidenced by the direct proportionality between the evolution of flue gas and pyrolysis gas temperatures over time and the necessity to adjust air supply to maintain system stability.
| Identifer | oai:union.ndltd.org:UPSALLA1/oai:DiVA.org:lnu-130709 |
| Date | January 2024 |
| Creators | Rivera Gómez, Enrique |
| Publisher | Linnéuniversitetet, Institutionen för byggd miljö och energiteknik (BET) |
| Source Sets | DiVA Archive at Upsalla University |
| Language | English |
| Detected Language | English |
| Type | Student thesis, info:eu-repo/semantics/bachelorThesis, text |
| Format | application/pdf |
| Rights | info:eu-repo/semantics/openAccess |
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