【作者】 刘辉；

【导师】 刘亮；

【作者基本信息】 长沙理工大学 ， 动力机械及工程， 2008， 硕士

【摘要】 生物质能源的开发与利用对缓解我国能源和环境压力,促进社会经济的发展和生态环境的改善具有重大的意义。生物质热解技术是有效利用生物质能源的方法之一。本文综述了各国生物质能的利用现状和形势,结合我国生物质能利用的具体状况和研究形势给出了本文的研究方法和研究内容。从3个角度(生物质组成、物质能量传递和反应进程)分析了生物质热解反应机理,简要介绍了生物质热解反应的动力学理论。选取三种湖南省比较常见的天然生物质松树皮、稻秆和竹子为实验原料对生物质的热解进行了研究。分别对三种生物质试样进行了工业分析和热重分析。热解实验采用线性升温的方法,在氮气气氛下进行,并用高纯氮气作为保护气体,对不同升温速率、不同颗粒粒度和不同生物质组成的试样产生的TG和DTG曲线进行了分析,通过对影响生物质材料热解的各种因素的分析,进而得出了影响生物质材料热解的主要影响因素和一般规律。通过工业分析可以看出生物质具有挥发份含量高、灰份含量低、低发热量的特点。对TG和DTG曲线的分析结果表明:(1)生物质的热解行为可以分成两个明显的反应阶段;(2)升温速率影响试样热解的最大失重率以及热解的温度范围,升温速率的提高有利于生物质的热解反应;(3)颗粒粒度对热解的影响较小,颗粒粒度越小越有利于热解的进行;(4)生物质中的灰分越大,达到最大热解速率对应的温度越低,最终固体残余量越大;挥发分越大,最大热解速率越高;水分越大,第一阶段失重率越高。生物质的热解分为两个阶段,建立了生物质热解反应动力学模型,用Li Chung-Hsiung法将数据代入9种典型的固体热解机理函数中进行拟合,比较他们的相关系数和偏差,选出线性最好的几种机理函数,再用Malek来确定最有可能的机理函数。结果表明可以用R2模型和F1模型分别来描述松树皮两个阶段的反应机理,用R3模型和D3模型分别来描述稻秆两个阶段的反应机理,用R2模型来描述竹子两个阶段的反应机理,最后通过选出的最佳机理函数用积分法分别求出不同实验条件下的反应动力学参数,即反应活化能E和指前因子A。更多还原

【Abstract】 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.更多还原