Modelling the fast pyrolysis of cellulosic particles in fluid-bed reactors

A mathematical model for intra-particle transport phenomena and chemical re actions is coupled with an external heal transfer model, taking into accoun t fluid-bed hydrodynamics, to predict the fast pyrolysis characteristics of cellulosic fuels. Good agreement is obtained between predicted and measure d product yields as functions of the reactor temperature. For practical app lications aimed at liquid fuel production, particle size and external tempe ratures greatly affect the average particle heating rate (values roughly co mprised between 300 and I K/s), whereas the actual degradation temperature vary in a narrow range (600-725 K). Consequently, variations in the convers ion time are significantly larger than in product distribution and yields. Finally, comparisons are made with the Ranz-Marshall correlation and the li mit case of infinitely fast external heat transfer rates. (C) 2000 Elsevier Science Ltd. All rights reserved.