Numerical simulations reveal that the time required for rapid pyrolysis of cellulosic biopolymer particles (diameter d 0.5 mm) is composed of a heatup time th and a devolatilization time fd. Approximations of fh and td are given by the time required for radiative and convective heat transfer to rais
Numerical simulation of cellulose pyrolysis
โ Scribed by Colomba Di Blasi
- Publisher
- Elsevier Science
- Year
- 1994
- Tongue
- English
- Weight
- 303 KB
- Volume
- 7
- Category
- Article
- ISSN
- 0961-9534
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โฆ Synopsis
A mathematical model of transport phenomena and chemical processes of the thermal degradation of cellulose is presented. The kinetic model developed by Bradbury et al. (J. Appl. Polym. Sci. 23, 3271, 1979) for primary pyrolysis is extended to include secondary reactions of volatiles: kl k, kI /" Tar + Gas Cellulose --* Active cellulose 2 \ Char + Gas.
From the physical point of view, the model describes convective, conductive and radiative heat transfer, mass convection and diffusion and velocity and pressure variations interior to the porous solid (Darcy law). Furthermore, porosity, mass diffusivity, permeability and thermal conductivity vary with the composition of the reacting medium. Time and space evolution of the main variables, and reaction product distribution, are simulated by varying the reactor temperature and the reactor heating rate.
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