Heat transfer and kinetics in the low temperature pyrolysis of solids

✍ Scribed by D.L. Pyle; C.A. Zaror

• Publisher: Elsevier Science
• Year: 1984
• Tongue: English
• Weight: 1012 KB
• Volume: 39
• Category: Article
• ISSN: 0009-2509
• DOI: 10.1016/0009-2509(84)80140-2

✦ Synopsis

New theory is developed to define the parameters controlling the pyrolysis rate of single particles. It is shown that the relative importance of internal and external heat transfer and of the, intrinsic (first order) pyrolysis kinetics can be determined from the Biot number (hR/K) and, depending on the value of the Biot number, one of two Pyrolysis numbers defined by Py = (X/kpc,J?) or Py' = (hlkpc,R). On the basis of these groups four regions are defined, and appropriate and simple models of the kinetics of primary pyrolysis outlined. The models are tested against measurements of decomposition and temperature distributions in pyrolysing wood cylinders with diameters in the range 03%2.2cm and at temperatures from 380 to 500°C. Good agreement with theory is found and it is concluded that, under these conditions, internal convection is unimportant and that with suitably large or small values of Bi, Py and Py' very simple models are adequate. Some implications for reactor design are briefly discussed.