A thesis submitted in partial fulfillment of the requirements for the degree of Master of Engineering, School of Environment, Resources and Development

Thesis (M.Eng.) - Asian Institute of Technology, 1986

In this study, a review of the available literature on kinetics of wood pyrolysis has been made. Available literature shows wood pyrolysis is a complex process and need to be studied further experimentally, to develop a fairly realistic theoretical model for pyrolysis zone of a wood gasifier. Since no data are available on pyrolysis product distribution in fixed bed wood gasifier, an attempt was made to estimate the pyrolysis product distribution theoretically assuming pyrolysis reactions to be autothermic. Thermal Analysis was carried out to analyze the kinetics of pyrolysis process qualitatively. The results show that heat of reaction of pyrolysis process is different at different temperatures. Major weight loss occurred in the .temperature range of 280 to 450 C. A steady state model for a downdraft wood gasifier has been developed based on kinetics and mechanisms of chemical reactions, mass and heat transfer and conservation of mass and energy. Wood gasifier model is subjected to constraints such as pyrolysis product composition. Parametric studies were made on wood and air flow rates, reaction multiplier and particle diameter. Also, an attempt has been made to incorporate porosity effect, in the model developed by BASAK(1985) for charcoal gasifier. Incorporation of porosity effect was found to improve the reaction rates .