生物质与煤流化床共气化中混合湿颗粒的物性匹配与流化特性研究

Optimization and adjustment of energy structure, and development and utilization of new energy technology are two major strategic tasks faced by the energy system in our country. Aiming at the fluidization of wet biomass-coal blends for co-gasification process in the fluidized bed, the project systematically studies its physical properties matching and fluidization characteristics. Firstly, taking the granular flowability as the objective, the physical properties of biomass/coal and biomass-coal blends will be investigated. An empirical model will be developed to reflect the physical flowability of granular mixtures and to obtain the physical matching and regulatory mechanism for granular mixtures. Secondly, a cold state fluidization experimental device will be established. The dynamic process of granular mixtures under the gas-solid two phase flow condition in the fluidized bed will be investigated to analyze and obtain the fluidization characteristic. Based on the fluid dynamics and the interaction principles of gas-solid and particle-particle, a complex theoretical fluidization model describing the fluidization behavior of granular mixtures in the fluidized bed under the gas-solid two phase flow condition will be established by analyzing the fluidization behavior of granular mixtures, using discrete element method and computational fluid dynamics coupling method, and combining with the drag force model and liquid bridge force model. Finally, with the comparison of theoretical and experimental results, the model will be verified and amended to obtain the fluidization mixture theory of biomass/coal and biomass-coal blends. The results of the project will lay a solid theoretical basis for the co-gasification development of biomass-coal blends, as well as provide a powerful foundation for the new gasification technology in our energy structure. Therefore, the project is of important research value and strategic significance.

能源结构优化调整和新能源技术开发利用是我国能源体系面临的重大战略任务。针对生物质与煤混合含湿颗粒流化床共气化中的流化问题，本项目系统研究其物性匹配和流化特性。首先以流动特性为目标，对生物质和煤及其混合颗粒的物性进行研究，建立能反映颗粒混合流动特性的经验模型，获得颗粒混合物性匹配及调控规律；其次建立冷态流动床装置，通过研究流化床内气固两相流条件下颗粒混合的动态过程，分析获得其流化特性；在此基础上，基于流体动力学，气-固及颗粒-颗粒作用原理，分析混合颗粒流动行为，应用离散单元法与计算流体动力学耦合方法，结合曳力模型和液桥力模型，建立复杂气固两相流条件下流化床内混合颗粒流动行为的流化传输理论模型，并通过理论与实验对比，验证和修正模型，获得生物质和煤及其混合颗粒流化混合理论。项目研究将为生物质与煤共气化发展打下坚实的理论基础，为适应我国能源结构的新气化技术提供有力依据，具有重要的研究价值和战略意义。

本项目针对生物质与煤混合湿颗粒在流化床共气化过程中的物性匹配和流化问题开展了系统的研究工作，研究了颗粒在流化床中的流化行为和混合质量对流化床气化系统的稳定运行及气化效率的影响，以及混合颗粒的流动特性变化规律，探索其对流化床中的颗粒流化行为的影响。通过以锯屑和稻糠为生物质考察对象，研究了物性对其流动性的影响情况，对生物质的流动性与其粉体粒形、粒径及其颗粒分布、水分含量的关系进行了分析。对煤和锯屑组成的混合颗粒的流动性进行了研究，考察了锯屑的含量、粒径和水分含量对混合颗粒的流动性的影响。结合单独颗粒的流动特性研究，建立了能反映颗粒混合物性流动特性的经验模型，获得颗粒混合物性匹配及调控规律。此外，研究了循环流化床锅炉燃烧系统中诸因素的影响关系。在锅炉整体模型的基础上建立锅炉热效率软测量模型，应用实际数据对所建立软测量模型进行验证，并对主要的影响因素进行阶跃扰动实验，观测锅炉的阶跃响应变化，由此确定锅炉操作参数的可变范围，并可对之后所进行的参数优化进行指导。