双超声同步压缩制造纤维素燃料用生物质的机理研究

Cellulosic biofuels are regarded as an alternative to petroleum-based fuels, according to the problems of raw material's densification and pretreatment, the proposal presents "Dual-ultrasonic vibration-assisted pelleting (UV-A) of biomass". Densification and pretreatment are completed at the same step.Pre-feasibility study showed that density was 80% higher, and rate of sugar yield was 20% higher. The proposal includes the machining process model of UV-A pelleting, and the optimal matching parameters between ultrasonic vibration and prestress. Study the coupling characteristics and rules of dual-ultrasonic fields, and build the coupling model. Study the formation mechanism of micro porosity on biomass surface, and the relationship between rate of sugar yield and porosity, crystallinity, and degree of polymerization. Study the methods of measurement and control of the pelleting temperature. Study the mechanism of charring, and how to avoid from charring. Carry out FEM analysis using "hydro-variety theory". Finally, mathmatical-physical model is built for UV-A pelleting based on system experiments and theory analysis, and the best pellets are produced instructed by the above model. If the proposal sucesses, it is very important for increasing the rate of sugar yield cellulosic biomass, low-cost manufacturing of cellulosic biofuel.

纤维素燃料被认为是最具潜力的化石能源替代品之一，针对其制造过程中纤维素原料的致密化和预处理难题，本项目提出"双超声同步压缩新方法"，这是一种全新的思路，即在生物质压缩过程中同时进行预处理。前期研究显示，该方法使压块密度提高80%，出糖率提高20%。项目主要研究超声压缩的加工过程模型，探索超声振动与压缩的最佳匹配方式；研究双超声场的耦合特征与规律，并建立耦合模型；揭示生物质表面微孔的生成机理，以及孔隙度、结晶度、聚合度与出糖率之间的关系；研究压块温度场特征的提取与控制方法；研究"碳化"的发生机理，以及双超声消除"碳化现象"的方法；利用"流变学理论"进行有限元分析；最后，在系统工艺实验和理论分析的基础上，建立超声压缩过程的数学物理模型，以压缩模型为指导获得最佳质量的生物质压块。本项目的研究成功，将对提高纤维素生物质的出糖率，降低纤维素燃料的制造成本意义重大。

纤维素燃料被认为是最具潜力的化石能源替代品之一，针对其制造过程中纤维素原料的致密化和预处理难题，本项目提出“双超声同步压缩新方法”，即在生物质压缩过程中同时进行预处理，以提高成型效果和出糖率。. 首先，设计了双超声压缩生物质机床及其关键部件超声振子和超声电源，研究了双振子的等效电路模型及其匹配规律；其次，研究了生物质压块在压缩成型过程中力和压块内部各点温度变化规律，分析了压块成型机理和炭化现象；再次，研究了生物质压块的物理特性（包括密度、松弛密度和持久性等）和水解出糖率的影响因素，优化了工艺参数；项目证明了双超声压缩能显著提高压缩效率和出糖率，对生物质燃料的应用和推广具有重要意义。