| Biomass pyrolysis achieves efficient utilization of biomass through thermochemical conversion process, and has huge development potential. Biomass pyrolysis kinetics analysis aims to obtain accurate kinetic parameters, and then determine the pyrolysis reaction mechanism, to provide theoretical guidance for the pyrolysis reactor design and optimization of the pyrolysis conditions. The determination of real pyrolysis mechanism depends on the correct kinetic parameters, only on the basis of getting to know the kinetic analysis error, can it be possible to choose the best kinetic analysis methods and improve the accuracy of kinetic parameters. Starting from the basic theory of reaction kinetics, the thesis firstly researched the error of non-isothermal and isothermal kinetic analysis from the perspective of absolute error; combining thermogravimetric experiment and theory analysis to investigate the accuracy of the commonly used non-isothermal and isothermal kinetic analysis methods, and got the data of larch wood pyrolysis kinetics.The main results are as followed:(1) Proposed the idea that error of the kinetic analysis was codetermined by the kinetic analysis method and the real kinetic parameters of the reaction.(2) Proposed a stage classification method which divides the main pyrolysis phrase into three stages with corresponding temperature of the first derivative of DTG curve’s maximum peak and DTG curve’s maximum peak respectively as the cut-off points. The activation energy calculation results showed that the activation energy changed suddenly at the first derivative of DTG curve’s maximum peak point. Three phases’pyrolysis kinetic equations are in good agreement with the experimental data curves.(3) Single-curve approach-and multi-curve approach of non-isothermal method both could get nearly ideal activation energy. Isothermal method could obtain nearly ideal activation energy and frequency factor.The frequency factor is sensitive to the changes of reaction order. If the reaction order fluctuated within a narrow range, the frequency factor may have order of magnitude’s error under the single-curve approach of non-isothermal method and several ten times’error in the isothermal method. The activation energy is not very sensitive to the changes of reaction order. If the reaction order fluctuated within a narrow range, the activation energy may change slightly under single-curve approach of non-isothermal method and is almost constant in the isothermal method.(4) Phased study of pyrolysis process is superior to overall study of pyrolysis process. Model-fitting method is better than Coats-Redfern method’s direct determination. |
