Rates of pyrolysis and combustion of bark by thermogravimetric analysis
- Univ. of Mississippi, University, MS (United States)
Bark has been considered a viable renewable energy resource. This paper focuses on our experimental and modeling efforts on the bark combustion kinetics. Combustion and pyrolysis experiments have been conducted by lowering a sample-containing basket into a preheated, 2.5{double_prime} fluidized sand bed. This fluidized bed provides both rapid heating and quenching to the samples. Fluidized sand bed provides a very effective heat transfer medium between the gas (air or nitrogen) and the sand. Rapid quenching has been accomplished by raising the basket into a water-cooled, reversed-nitrogen flow section. The basket is made of a 40 mesh stainless steel screen. Combustion and pyrolysis of 10 mm diameter bark particles have been performed in the temperature ranges 500 to 800{degrees}C, and 750 to 850{degrees}C, respectively. The gas velocity has been in the range of 5.4 to 10.8 cm/s. Weight loss of bark after the experiments has been used as an index of conversion in the kinetic study. The combustion/pyrolysis model contains three dynamic equations: bark pyrolysis, char combustion, and heat transfer to bark particles. It has been assumed that the volatiles disengagement from char is governed by temperature-dependent desorption in an exponential form. By fitting the model to the experimental data, the seven parameters in the model have been recovered. These parameters include the four Arrhenius parameters for pyrolysis and combustion, total volatile at infinite temperature and temperature sensitivity in the volatile desorption equation, and heat of pyrolysis. Good agreement with the experimental data for pyrolysis and combustion demonstrates that the present model is capable of depicting the bark weight remaining in the bed at any time during combustion or pyrolysis. In addition, the kinetic parameters for the pyrolysis and heat of pyrolysis are in good accord with those in the literature.
- OSTI ID:
- 370288
- Report Number(s):
- CONF-960376-; TRN: 96:003805-0339
- Resource Relation:
- Conference: Spring national meeting of the American Chemical Society (ACS), New Orleans, LA (United States), 24-28 Mar 1996; Other Information: PBD: 1996; Related Information: Is Part Of 211th ACS national meeting; PB: 2284 p.
- Country of Publication:
- United States
- Language:
- English
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