【作者】 孙立；

【导师】 陈冠益；

【作者基本信息】 天津大学 ， 热能工程， 2008， 博士

【摘要】 生物质制氢研究是可再生能源的重要方向之一,本文提出了由常压移动床热解、二次热裂解、水蒸气转化和变换反应组成的生物质热解制氢技术路线,通过实验和数学模拟计算,研究了生物质向富氢气体转化的基本规律。利用热重仪分析了农业残余物热解的规律和特征参数,获得了热解反应速率、反应时间和转化率的定量结果,不同原料呈现出一致的热解反应机制,表观动力学参数计算表明,可以用单段一级反应过程描述生物质热解反应。设计并建立了常压移动床连续热解制氢实验系统,对生物质热解过程的释氢现象进行了系统实验研究,研究表明高温有利于提高气体产率和氢气浓度,在不使用空气和氧等介质的条件下获得了品质较高的中热值富氢气体。将Gibbs自由能最小化方法和Miller模型相结合,对热解过程进行数值求解,从动力学和热力学平衡角度研究了热解过程,发现和分析了生物质向富氢气体转化的现象、反应规律和影响因素,预测了与实验吻合的产物组成。探讨了通过水蒸汽转化和变换反应对热解气进行重整的方案,进行了生物质热解制氢系统的能量平衡计算,分析了氧化钙参与热解对提高系统效率的作用,确定了优化的工艺参数,玉米秸和稻壳氢产率可分别达到48.18 mol/kg和45.85mol/kg,气体中氢气浓度达到74.78%和73.35%,理想能量转换率达到77.9%和83.4%。更多还原

【Abstract】 Biomass-to-hydrogen (BTH) is an important research direction in renewable energy field. In this thesis, a new route of biomass pyrolysis for hydrogen-rich gas production was proposed, which is composed of moving bed pyrolysis at atmospheric pressure, secondary thermal cracking, steaming reforming and shifting. The basic principles in BTH conversion were investigated with combination of experiments and simulating calculations.The systemic research on the pyrolysis character of agricultural residues was carried out by thermogravimetries, and the quantitative data of porolysis reaction rate, reaction time and conversion rate were obtaineded. The TG curves of different feedstocks showed accordant reaction mechanism. The calculation results of apparent kinetic revealed that the biomass pyrolysis can be approximately regarded as a one-order reaction.The moving bed reactor was designed adopted for continuous pyrolysis at atmospheric pressure. The phenomenon of hydrogen releasing in biomass pyrolysis were systemic investigated. The experiments proved that higher temperature was propitious to the yield of gas and hydrogen. The clean mid-Btu hydrogen-rich gas was generated without using any air and oxygen.The combination of the minimum principle of Gibbs free energy and Miller Model were applied to simulate the kinetics and thermodynamics equilibrium of the pyrolysis process. The BTH process, reaction trend, and influence factors were analyzed, and the products distribution according to experiments could be predicted.The steam reforming and shifting were proposed to join in the route, the energy balance calculation was carried out, the function of Calcium oxide participating in the pyrolysis was discussed, and the optimized process parameters were fixed on. Under the optimized condition, the hydrogen yield, from corn straw and rice husk, could reach 48.18 mol/kg and 45.85 mol/kg, with hydrogen concentration of 74.78% and 73.35%, and perfect energy efficiency of 77.9% and 83.4% respectively.更多还原