Study On Pyrolysis Experiment And Kinetics Of Biomass

Utilization and development of biomass energy sources have great significance for alleviating the environmental and energy sources pressure of our country and promoting the development of society economy and improvement of ecological environment.Pyrolysis technology of biomass is one of the methods that efficiently using biomass energy sources. In this paper, the present utilizing present status and position in many countries were summarized, and then the research method and content were presented by combining the present utilizing present status and position in our own country and the pyrolysis characteristics of biomass were comparatively roundly researched by investigating the pyrolysis reaction kinetics. Experiment raw materials were selected in HuNan province, pine bark, rice straw and bamboo, which are comparatively common to be seen as crude biomass. The pyrolysis experiment adopts the way of linear heating up at nitrogen atmosphere, and uses high pure nitrogen gas as protection gas. TG and DTG curves which were obtained at different heating velocity, grain granularity and biomass constitute were analyzed and then the primary influencing factor and general rule were obtained which could affect the pyrolysis of the biomass by analyzing the factors which could affect the pyrolysis of the biomass. The analysis results of TG and DTG curves show that (1) Pyrolysis behavior of biomass can be divided into two obvious reaction stages. (2) Heating velocity affects the maximum weight loss rate and temperature range of samples, and the increasing of heating velocity is propitious to the pyrolysis reaction. (3) Grain granularity has less effect on pyrolysis, though the smaller the grain granularity is, it is in favor of the pyrolysis reaction. (4) Moisture, ash and volatile matter in biomass raw materials also have some effect on pyrolysis reaction.Pyrolysis of biomass was divided into two stages, and pyrolysis reaction kinetics model was founded. The datum were put into 9 kinds of typical solid pyrolysis mechanism functions for fitting by the method of Li Chung-Hsiung and then the correlation coefficient and deviation were compared. Some kinds of mechanism functions which linearity were best were selected for ascertain the most capable mechanism function by the method of Malek. The results show that it is very well to use R2 and F1 models for depicting the reaction mechanism of the two stages of pine bark, and use R3 and D3 models for depicting the reaction mechanism of the two stages of rice straw, besides use R2 models for depicting the reaction mechanism of the two stages of bamboo. Finally, the reaction kinetic parameters, activation energy E and pre-exponential factor A at different experimental conditions were calculated.