Experimental analysis and empirical correlations for the devolatilization times of wood particles in a fluidized-bed reactor

The thermal history undergone by cylindrical beech wood particles, injected in a sand bed fluidized by nitrogen, has been recorded. Experiments have been carried out by varying particle diameter and bed temperature. The rate of volatile release becomes significant for temperatures above 625-650K and is always completed for temperatures below 675-825K. Devolatilization causes a strong reduction in the heating rate which, at the particle center and for the most intense reaction activity, is comprised between 0-25K/s. For the conditions typical of fast pyrolysis, the yields of char are 10-18% and the devolatilization times 18-45s. In qualitative agreement with previous analyses carried out for coal particles, these are well predicted by an empirical power-law relation: tv=0.8 e1525/Trd1.2s.