As found by Sreekanth and Kolar,22 particle shrinking core kinetic models have been widely used for wood pyrolysis with a weight loss of more than 70%. For torrefaction in a narrow and mild temperature range from 200 to 300 °C with a low particle heating rate, the hemicelluloses decomposition takes place quite uniformly across the particle, with the lignin and most celluloses remaining in the original wood structure. As a result, the torrefaction of biomass particles could be modeled as a nonshrinking process.2 For biomass torrefaction with a final weight loss of less than 40%, we can also reasonably assume that the diameter of particles does not change (nonshrinkage core) during the torrefaction. The previous analysis showed that there is expected to be negligible temperature gradient within particles, so that the particle can be treated as having a uniform temperature. By further assuming that the global reactions are first order reactions and the reaction is under a pseudo-steady-state with little change of vapor phase
As found by Sreekanth and Kolar,22 particle shrinking core kinetic models have been widely used for wood pyrolysis with a weight loss of more than 70%. For torrefaction in a narrow and mild temperature range from 200 to 300 °C with a low particle heating rate, the hemicelluloses decomposition takes place quite uniformly across the particle, with the lignin and most celluloses remaining in the original wood structure. As a result, the torrefaction of biomass particles could be modeled as a nonshrinking process.2 For biomass torrefaction with a final weight loss of less than 40%, we can also reasonably assume that the diameter of particles does not change (nonshrinkage core) during the torrefaction. The previous analysis showed that there is expected to be negligible temperature gradient within particles, so that the particle can be treated as having a uniform temperature. By further assuming that the global reactions are first order reactions and the reaction is under a pseudo-steady-state with little change of vapor phase
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