生物质热解气分级冷凝机理与目标产物富集机制研究

In this research project, the complex composition of pyrolysis vapors from various typical lignocellulosic biomasses will be thoroughly investigated and determined by using pyrolysis-gas chromatography/mass spectrometry (Py/GC-MS), solid-pyrolysis/synchrotron vacuum ultraviolet photoionization mass spectrometry (Solid-Py/SVUV-PIMS)and other instruments, and combining with the now available related results. In addition, the percentage and evolvement of the non-condensable and condensable gases, lignin oligomers, fine char particles and aerosol will be studied. A model system of the key components of pyrolysis vapors will be established according to their fractional condensation characteristics, and the thermophysical parameters of the key components will be determined. Besides, theoretical models of thermo-physical property and phase equilibrium of the key components of pyrolysis vapors and mathematical models of pyrolysis vapors fractional condensation will be developed using pseudo-component method and continuous thermodynamics method, and heat and mass transfer mechanism andgoal products enrichment rule during the condensation process will be studied through numerical simulation. An experimental device for pyrolysis vapors fractional condensation with first stage and other stages using spray condensation and falling film condensation respectively will be constructed. Moreover, through numerical simulation and experimental investigation, the velocity change law in all condensers and precipitation of phase change latent heat will be understood, and the heat and mass transfer mechanism during pyrolysis vapo rfractional condensation, and the enrichment rule and controlling method of goal products in different condensation stages will be revealed.

项目拟通过Py/GC-MS和固体热解/同步辐射真空紫外光电离质谱等实验平台和分析仪器，结合国内外关于生物质热解气成分分析的文献报道，全面考察并确定在我国具有代表性的若干种农林废弃物热解气的复杂组成体系，揭示不凝性气、可凝性气、木质素热解低聚物、微细炭粉颗粒和气溶胶等在体系中的组成与变化规律；根据分级冷凝制备多品级生物油的特点，基于对热解气各组分含量、热物性和价值的综合考虑，从中筛选出40-50种对冷凝有较大影响的关键组分，构建其特征组成体系；基于虚拟组分法和连续热力学方法，建立生物质热解气特征组成体系热物性、相平衡理论和分级冷凝数学模型；改造完善已有生物质热解气分级冷凝实验装置，通过对其分级冷凝过程进行数值模拟和实验研究，全面掌握各级冷凝器中流场变化、冷凝传热系数和相变潜热析出规律等，深刻揭示生物质热解气分级冷凝传热传质机理和不同品级生物油中目标产物富集机制与调控方法。

生物质热解液化技术主要由生物质快速热解析出热解气和热解气快速淬冷得到生物油两个核心过程组成。在冷凝过程中根据热解气各组分间冷凝能力的差异进行分级冷凝，可以实现生物油复杂成分的在线分离。.本项目通过分析生物质热解气复杂成分、构建热解气全面特征组成体系、进行特征体系相平衡数值计算、开展热解气选择性冷凝实验、改进生物质热解分级冷凝制油平台，最终掌握生物质热解气分级冷凝机理与目标产物富集机制。采用快速热解/气相色谱-质谱联用仪、气相色谱-热导检测器、卡尔费休水分分析仪等设备全面考察稻壳、核桃壳、毛竹、马尾松针、玉米芯等常见生物质原料热解气可冷凝组分和不可凝组分的构成配比；结合文献计算热解气可检测组分常用热物理性质，综合提出29组分生物质热解气特征组成体系，开展不同压力下生物油蒸馏实验以获得蒸馏特性曲线；采用固体热解/同步辐射真空紫外光电离质谱仪分析生物质热解气组分冷凝性能的演化规律，开展生物质热解气模型化合物在管壳式换热器内的相平衡核算，通过固定床小试平台和移动床/流化床中试平台实验研究冷凝器壁面温度、不凝气比重、喷雾冷凝工质等影响因素对生物油产率、组分和性能的影响。.系统总结生物质热解气可冷凝组分在分级冷凝系统内的演化规律和选择性冷凝调节机制，归纳冷凝可控因素对生物油组分分离富集的作用规律，分析多品级生物油理化性能和应用前景。为解决热解气在冷凝演化过程数值计算偏差较大的问题，提出基于生物油分段回收冷凝管的实验研究生物质热解气在接换热冷凝液化过程可冷凝组分蒸气演变的创新方法；通过分级冷凝调控，水或乙酸等严重降低生物油品质的组分最多可减少90%以上，愈创木酚及其衍生物等高附加值组分最高可提升500%；热解低聚物聚集于第一级冷凝器内，大部分水和乙酸分离于第三级冷凝器中，酚类物质富集在第二级冷凝器中。以本项目为第一资助累计发表25篇高水平学术论文，项目在研期间培养6人获得博士学位、7人获得硕士学位。