Sébastien Pécate

HYDRODYNAMIC STUDY OF A CIRCULATING FLUIDIZED BED USED FOR BIOMASS GASIFICATION
BETWEEN 20 °C AND 900 °C
Sébastien PECATE, Université de Toulouse, INPT, Laboratoire de Génie Chimique de Toulouse, 4 allée Émile
Monso, 31432 Toulouse Cedex 4 - BP 84234
[email protected]
Mathieu MORIN, Mehrdji HEMATI, Université de Toulouse, INPT, Laboratoire de Génie Chimique de Toulouse,
4 allée Émile Monso, 31432 Toulouse Cedex 4 - BP 84234
Yilmaz KARA, Centre de Recherche et d’Innovation Gaz et Energies Nouvelles (CRIGEN), 361 avenue du
Président Wilson – BP33 – 93211 Saint Denis la Plaine CEDEX Groupe ENGIE
Sylvie VALIN, CEA, LITEN, 17 rue des Martyrs F-38054 Grenoble cedex 9, France
Key words: Circulating fluidized bed, hydrodynamic, high temperature, biomass, gasification
This work, carried out in the GAYA project frame and subsidized by ADEME, concerns the hydrodynamic study
of a 60 kWth circulating fluidized bed pilot plant constructed at the Laboratoire de Génie Chimique in Toulouse
for biomass gasification. In that process, biomass gasification and heating of fluidisation material (sand, olivine,
catalyst…) which also acts as heat transfer medium, are performed in two separate reactors: a dense fluidized
bed and a transported bed. Thermal energy, required in order to heat the fluidisation material, is supplied by the
partial combustion of the char produced in the gasification reactor. The hydrodynamic study carried out at
atmospheric pressure between 20 °C and 900 °C leads to the determination of the influence of the temperature
and media average particle size (olivine), the reactor geometric properties and the fluidization gas nature (air or
steam) on the media hydrodynamic parameters such as the minimum fluidization velocity and porosity, the bed
expansion and the solid transport velocity. Results have shown that the minimal fluidization and transport
velocity decrease with the bed temperature increase. However, the bed expansion is not affected by this factor.
Furthermore, the particles transport happens from the terminal falling velocity and increases with the gas
velocity. The fluidization gas nature has a significant effect on the minimal fluidization velocity, but not on the
bed expansion. Correlations are proposed in order to estimate the characteristic parameters of the olivine
hydrodynamic behavior depending on the temperature, the fluidization gas nature and the solid particle size.