高效煤气转换过程多尺度气固流动在线诊断与控制

In China, more than 70% of electric power is generated by directly burning of coal, which is a main source of PM2.5 and CO2 pollution. One way to reduce pollution from coal is gasifying it. The current bottle-neck of the coal-gasifying technology is that the gas-coal mixing process cannot be monitored online as well as the inability to make necessary measurements of the performance of the gas/solids fluidized bed reactor. Consequently, to maintain high gasifying efficiency is a difficult task. We propose to develop an innovative coal-gasifying facility, which combines hydrodynamic modelling, CFD simulation, existing ECT and other available online measurement technologies (such as microwave Doppler) with process modelling and simulation verification. Therefore, the aim of this project is to develop a new generation of cleaner and more efficient coal-gasifying facility with advanced online measurement. Electrical capacitance tomography (ECT) and microwave technology combined with optical and pressure probes will be used to measure the solids distribution and flux in the complex region in the bubbling and circulating fluidized bed. Microwave doppler will be applied to measure the particle velocity for on-line process control. The bubbles and particles clusters characteristics will be given and analysis based on the combined signals. Process optimum design for super-pressure CFB design will be formulated based on the measurement and CFD-CPFD simulation results. Hydrodynamic modelling, CFD simulation and "cold tests" will be carried out. "Hot tests" with a high-temperature high-pressure (HTHP) ECT sensor, which presents great challenges, will be performed. The success of the proposed work for clean use of coal, will contribute to the wealth, new jobs and reducing pollution, and hence health as well.

发展具有广泛燃料适应性的洁净煤气化燃烧技术是我国能源发展战略的重要方向。但煤粉气化燃烧过程是一个复杂的多尺度气固流动过程，为了保证系统安全、稳定和高效运行，要对反应器内部气固两相多尺度流动特性进行深入的机理研究，组织合理的颗粒浓度分布，使煤粉颗粒和空气或氧气之间有良好的接触面积和反应时间，以便提高系统运行效率和对过程进行调控。本项目将基于层析成像测量和多尺度计算流体力学方法，研究煤粉气化过程反应器及气固分离系统内部气固两相多尺度流动特征。数值计算基于CFD-CPFD方法，嵌入EMMS曳力模型，模拟气固宏观-微观-介尺度运动特性；实验研究通过电容层析成像，结合微波多普勒、压力和光纤信号，为反应器不同区域提供固体颗粒浓度、速度、压力分布信息，分析煤粉气化过程多尺度流动特征，研究复杂流动结构下反应器之间固体颗粒质量分配规律，为煤粉气化过程设计和大型化提供在线监测工具、理论依据和实验数据库。

煤炭清洁高效利用是我国能源战略发展的重要方向，其中加压循环流化床煤气化作为一种国际上正在研发示范的先进气化技术，具有良好的应用发展前景。气化反应器，特别是双床反应器的设计优化、性能预报和大型化，依赖于对其内部复杂气固流动特性的理解。项目基于非介入式电容层析成像技术和多尺度计算流体力学方法，对加压循环流化床气固流动特性展开实验测量和数值模拟研究，揭示临界流化速度、气泡动态行为、颗粒沿床层不同位置的浓度与速度分布、气固流型转变以及颗粒循环流率等关键流动特性随操作压力的变化规律，为加压流化床反应器的设计和大型化提供理论依据和实验数据支持。数值计算基于MP-PIC方法，嵌入EMMS非均匀曳力模型，对加压循环床以及双床结构的反应器开展三维全回路CPFD数值模拟。实验基于电容层析成像技术和高频压力测量，在加压循环流化床试验台上开展了鼓泡流态化至快速流态化流型转变过程以及双床系统压力的实验研究。通过图像重建、测量信号统计分析，揭示了操作压力对各临界流型转变速度的影响，以及气泡特征在同压力和流化数下的变化规律。通过本项目开展的上述研究，实现了加压循环流化床非介入式电容层析成像测量和CPFD全循环回路的数值计算，揭示了复杂的多尺度非线性气固流动特性及操作压力的影响规律，为加压流化床反应器的设计运行和过程调控提供了理论依据和实验数据支持。本项目部分研究研究成果荣获2020年中国科学院杰出科技成就奖，项目负责人王海刚荣获英国皇家学会牛顿高级基金；发表SCI论文12篇，其中包括本领域顶级期刊邀请综述论文2篇；本领域国际会议邀请报告2次；培养博士生2名，硕士生1名；荣获中国计量测试学会多相流会议优秀论文奖1次，中英颗粒国际论坛优秀海报奖1次。