Development and testing of a bubbling fluidized bed reactor for fast pyrolysis of biomass

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University of Dar es Salaam
Production of bio oil using pyrolysis of biomass has a comprehensive knowledge gap based on process optimization for the intended product and appropriate properties adequate for pyrolysis. To bridge this gap a study has been undertaken to establish parameters for the design and development of a bubbling fluidized bed for fast pyrolysis of biomass to produce bio oil. The study investigated pine sawdust material as a feedstock in a pyrolyzer. The feedstock material composition was analyzed by thermal, proximate and ultimate analyses. The thermal properties were determined using thermogravimetric analyzer (TGA). The combined proximate analysis and TGA test revealed the material to have volatile matter (VM) of about 90% at 500 oC. This value is considered to be adequate for fast pyrolysis and for the production of bio oil, since the recommended threshold of VM is 87%. These laboratory test results were then used to determine parameters needed to design, and manufacture a prototype pyrolyzer with a reactor of 76 mm internal diameter 940 mm length and with a capacity of 1 kg/h throughput of feedstock. The unit was tested five times under cold mode to ensure safe operation and gave satisfactory operation results that no leakages were observed. The major challenge encountered on the designed pyrolyzer is the need for accurate/precise flow control of fluidizing gas to facilitate fluidization and control of the leakage of the fluidizing gas through the screw housing. Future work should be done on the pyrolyzer to ensure it can operate adequately under hot mode, a condition necessary for bio oil production in situ.
Available in print form, East Africana Collection, Dr. Wilbert Chagula Library, Class Mark (THS EAF TP360.N3752)
Biomass conversion, Pyrolysis, Biomass energy
Ndalila, P (2013) Development and testing of a bubbling fluidized bed reactor for fast pyrolysis of biomass, Master dissertation, University of Dar es Salaam.