Apparent Kinetic Study Of Woods Pyrolysis And Combustion

Pyrolysis provides necessary volatile fuels for ignition and fire spread processes. For this reason, understanding the behavior and kinetics of pyrolysis is of key importance to model the ignition and fire spread processes.After a review of current researches on pyrolysis and kinetic model by the domestic and oversea researchers, this thesis covers the experimental and model researches.Firstly this thesis gives the experimental study on the pyrolysis of many kinds of biomass in a variety of surroundings with TG—FTIR analysis technique. The sample covers from log to cellulose , hemicellulose and lignin. The thermal degradation of woods shows one-step global reactivity in nitrogen atmosphere, while with two-stage reactivity in deficient oxygen atmosphere(variable oxygen concentration) and in carbon dioxide. Mechanism analysis of influence of oxygen concentration on apparent thermal gravity loss degradation wood combustion is thoroughly analysed from three aspects. They are energy supply , diffusibility of volatile and kinetics. Then model research is given. This thesis puts forward the rule that the activation energy of wood increases linearly with oxygen concentration, which is firstly proposed. The major cause is that oxygen accelerates the ordering process of char structure and promotes the bond energy. Lastly spectrograms of gas production from log and components pyrolysis is analysed. The results indicates that the main gas products are CO₂, CO, H₂O, CH₄&CH₃COOH etc, no matter what kinds of biomass is heated in nitrogen and carbon dioxide and variable oxygen surroundings. As a result, with the increase of oxygen concentration, the magnitude proportion of CO₂\CO gradually increases. And the mechanism analysis is given on influence of oxygen concentration on gas products from biomass.