加压多段分级转化流化床气化过程中介尺度演变机理及调控机制研究

Efficient and environmentally friendly utilization of low-rank coal has become an important aspect of clean coal technology development. Based on the staged conversion concept of coal pyrolysis and gasification, a pressurized multi-stage conversion fluid-bed gasifier is developed by Institute of Coal Chemistry, Chinese Academy of Sciences, which couples an ash agglomerated fluidized bed with riser. However, enough knowledge is still lack in the formation mechanism and evolution behavior of bubbles and clusters formed in the pressurized fluidized bed. And the study of pressurized coal gasification under mixed atmosphere can not be understood completely. These have being limited the development of pressurized multi-stage conversion fluid-bed gasifier. In this project, the effect of pressure on the fundamental characteristics in fluidization, the evolution mechanism and stability conditions of bubbles and complex gas-solid flow characteristics of wide size ranges of particles is systematically studied utilizing a high-pressure fluidization cold model facility, in order to clarify the quantitative relationship between the parameters of pressurized fluidized bed and perfect the theory of two-phase flow at high pressure. In addition, the dynamic behavior of clusters between the riser and a single particle also will be researched in a pressurized riser experimental platform, and then the formation and evolution mechanism of aggregation will be investigated. Furthermore, the characteristics of low-rank coal char gasification with multiple gases at elevated pressures will be investigated and the kinetic model of low-rank coal char gasification will be found. By the study of pressurized bubbles and cluster and coal gasification reactivity under mixed atmosphere, the understanding in the interaction mechanism between the pressurized micro-scale particles - meso-scale bubbles (or cluster) - macro scale reactor can be further enhanced. And it also can provide a complete data base for scale-up and design of multi-stage conversion fluid-bed gasifier.

低阶煤的清洁高效利用正成为洁净煤技术的重要发展方向，基于煤炭分级转化理念，实现低阶煤气化与热解的耦合,开发了耦合灰熔聚技术和提升管技术的加压多段分级转化流化床气化炉。然而目前对加压下浓相流化床内气泡和提升管内团聚体的形成机制和演变规律以及加压混合气氛下低阶煤气化的反应特性还缺乏足够的认识，限制了多段分级转化流化床气化炉的发展。本申请将在加压流化床实验平台上，研究流化床中宽粒径分布物料的介尺度气泡的演化机制；研究提升管内局部结构上聚团行为的发展机制和整体结构上关键参数的轴径向不均匀分布规律；在煤热解/气化平台上，研究加压混合气氛下低阶煤焦的气化反应特性；构建加压流化床的气固动力学模型和低阶煤焦的气化动力学模型。通过本项目对加压气泡、团聚体和气化动力学的研究，可进一步加深对加压下微尺度颗粒-介尺度气泡（或团聚体）-宏尺度反应器之间相互作用机理的认识，为工业设计和放大过程提供一定的理论指导。

针对加压下浓相流化床内气泡和提升管内团聚体的形成机制和演变规律以及加压混合气氛下低阶煤气化的反应特性还缺乏足够的认识，限制了多段分级转化流化床气化炉的发展。申请人在加压浓相流化床介尺度气泡行为和颗粒行为、加压提升管内整体流动结构和局部流动结构（介尺度颗粒聚团行为）和加压混合气氛下煤焦气化反应动力学等三方面的开展了系列研究。研究了加压浓相流化床内气泡演化规律和稳定性条件，揭示了固体颗粒浓度和速度随压力的变化机制，建立了宽粒径分布物料的加压流化床内气固流动数学模型；阐明了加压下提升管内聚团行为的发展机制；获得了加压混合气氛下低阶煤焦表界面时空尺度和材料结构对煤焦气化特性的影响规律。获2018年中国颗粒学会科技进步二等奖，申请人排名第二；研究成果为加压多段分级转化流化床气化炉高压运性提供了理论支撑， 实现了Ф800mm多段分级转化流化床气化炉2.8MPa高压运行。