【作者】 尤占平；

【导师】 由世俊；

【作者基本信息】 天津大学 ， 供热、供燃气、通风及空调工程， 2010， 博士

【摘要】 生物质能的利用是解决能源问题的重要途径,气化技术是生物质利用的最有效的技术,气化气内焦油含量高是生物质气化技术大范围推广的技术瓶颈。生物质炭是生物质热解过程的产物,采用生物质炭作为焦油裂解催化剂具有潜在的优势。水蒸汽在高温下对焦油具有重整作用。将生物质炭催化裂解技术和水蒸汽重整技术结合起来是降低焦油含量的有效手段。第一、本文综述了国内外关于焦油催化裂解和蒸汽重整研究的进展,主要包括各种催化剂的性能、操作条件对催化性能的影响、催化剂积炭和再生、蒸汽的重整作用和催化重整机理等,提出了采用生物质炭作为焦油的催化剂并结合焦油水蒸汽重整的技术路线。第二、在实验室规模的实验台上,研究了焦油的催化重整性能。通过对焦油转化率、热解产物和热解气组分进行的研究可知:焦油的催化重整技术能促进可凝结相产量的降低和气相产量的增加,焦油转化率最高时可达96.1%。热解气组分的变化表现可燃成分的增加。氢气含量变化最明显,最高可以达到热解气体积的50.2%。从实验结果可知:催化裂解温度和S/C对催化性能影响较大,氮气流量的影响相对较小,催化裂解区长度和蒸汽加入方式也具有一定的影响;不同实验条件下生物质炭的微观结构也发生了变化。第三、通过实验方法对两种生物质炭的气化性能进行了研究,包括生物质炭的气化率和气化气组分随温度的变化。实验结果表明:气化温度对炭气化率具有重要影响,随着气化温度的升高,炭气化率升高,但上升趋势不断变缓。在实验温度条件下,炭气化率最高不超过30.0%。生物质炭气化的气体产量也会随着温度的升高而增加,气化气组分也有较大变化。经过计算可知,炭气化反应的产气量一般为生物质热解总产气量的20.0%左右。第四、在实验的基础上,对焦油催化重整反应和生物质炭气化反应的动力学进行了研究,通过回归方法得到了反应的一阶整体动力学模型,并通过模拟数据和实验数据的对比,对模型的正确性进行了验证。在此基础上,给出焦油催化重整过程的整体动力学模型,并对不同条件下的催化重整过程进行模拟。第五、在实验和理论分析的基础上,提出了以焦油的生物质炭催化重整为基础的新型生物质气化系统,从理论上对该系统的质能平衡进行了研究,尤其探讨了此系统的炭平衡和余热利用问题。更多还原

【Abstract】 The use of biomass energy is an important way in solving the energy problem and gasification technology is the most effective technology at present. The high tar concentration in pyrolysis gas is the bottleneck of biomass gasification technology for large-scale extension. Biomass char is a product of the pyrolysis process of biomass and can be used as catalyst in tar cracking. Steam at high temperature has the function of tar reforming. The combination of biomass char catalytic cracking technology with steam reforming technology is an effective technical means in eliminating tar.Firstly, the progress of catalytic cracking and steam reforming of tar nowadays were reviewed, including the performances of various catalysts, the effects of operating conditions on catalytic performance, catalyst coking and regeneration, the effect of steam reforming and mechanism of catalytic reforming. On the basis, the technical route was proposed, combining biomass char catalyst technology with steam reforming technology in tar degradation.Secondly, by laboratory-scale experiment, the catalytic reforming performances of tar were studied. And from the studies of tar conversion rate, pyrolysis products and pyrolysis gas composition, it was known that the reforming technology would promote production of condensed phase reduced and gas production increased, with maximum tar conversion rate up to 96.1%. The combustible components increased in pyrolysis gas, in which change of hydrogen content was the most significant, up to 50.2% of pyrolysis gas volume. From the results of experiments, it was known that catalytic cracking temperature and S/C had greater impact on the catalytic properties while that of nitrogen flow was relatively small. The length of catalytic cracking zone and steam addition method also had a certain effect. And under different experimental conditions, the microstructure of biomass char also changed.Thirdly, the gasification performances of two kinds of biomass char by experiment method were studied, including conversion rate and gasification gas component with temperature. And experimental results showed that gasification temperature had important effect on the conversion rate. With the increasing of gasification temperature, carbon conversion rate increased, but the trend slowed down. In the range of experimental temperature, char conversion rate was no more than 30.0%. The gas yields of biomass char gasification increased with the increasing of temperature and gas component were also changed significantly. In addition, experimental results also indicated that gas output of char gasification was about 20.0% of general gas output.Fourthly, on the basis of experiment, the kinetics of tar catalytic reforming and biomass char gasification were studied and the first order kinetic model was obtained by regression method. Through the comparison of simulation data and experimental data, the model was proved to be correct. So, the general kinetic model of tar catalytic reforming was proposed to simulate the tar catalytic reforming process under different conditions.Finally, on the basis of experimental and theoretical analysis, the new biomass gasification system of combination biomass carbon catalyst and tar steam reforming was put forward. And the mass and energy balance of system were analyzed, especially the carbon balance and waste heat utilization of the system was studied.更多还原