Determination of fluidized bed combustion kinetic and diffusive data of four wood chars from the central region of Portugal

Abstract

The fluidized bed reactor is suitable for the combustion of biomass solid fuels because of its advantages in terms of pollution control. At the same time it is a useful laboratory tool to determine kinetic and diffusive combustion data in operating conditions similar to those found in industrial systems. Because of the heterogeneous nature of biomass, available information on its combustion is still limited. During the combustion of ligneous biomass, the burning of the solid carbonaceous residues formed after the initial steps of drying and volatiles release is the time-consuming step. In the present work, kinetic and diffusive data from the fluidized bed combustion of chars produced from four Portuguese wood species-Quercus ilex (holm oak), Eucalyptus globulus (eucalyptus), Pinus pinaster (maritime pine), and Quercus suber (cork oak)-were obtained in the 750-900 degrees C temperature range. Subsequently, activation energies and pre-exponential factors were calculated from the Arrhenius plot of the kinetic data. The obtained activation energies from 38 to 121 kJ/mol are coherent with results obtained for other wood chars and demonstrate that the fluidized bed technology is a fruitful and reliable methodology to achieve a collection of results of real and industrial interest. The main goal of the present work is to widen the information on the kinetic and diffusive data of wood chars in order to better understand the mechanisms of ligneous biomass combustion, and the data now published increases the range of available kinetic data on wood char combustion.