我国煤炭资源与水资源呈逆向分布的特征，迫切需要开发高效的干法分选技术。研究干法重介流化床中气泡相与煤炭颗粒的运动行为特征，是揭示气固相间作用与煤炭密度离析行为的关键。电容层析成像系统 (ECT) 作为一种非侵入式三维成像测量手段，可以实现对气泡和煤炭颗粒的精准捕捉。利用电容层析成像技术，基于空气与介质颗粒间介电常数的差异，对气泡运动行为进行了精准捕捉，建立了气泡生长和运动速度的数学模型，揭示了床层中的气固两相分布特征。结合COMSOL仿真模拟证实了ECT对煤炭示踪的可行性，提出了一种可用于实时监测煤炭颗粒运动行为的技术方案，分析了操作条件及煤炭性质对运动行为的影响，实现了煤炭颗粒在径向和轴向的实时捕捉。结合上述气泡和煤炭运动行为的捕捉结果，分析了床层中气固两相分布特征，构建了适用于煤炭分选的密度模型，模型预测值与实验测量值的误差在20% 以内，能够分选密度的有效预测。通过将电容层析成像技术引入干法分选流化床分选领域，实现流化床分选行为的直接观测，解决了光纤探针、二维成像等技术对气固分选流化床中气泡运动行为捕捉的不足和煤炭分选过程可视化追踪的难题，为理解煤炭的分选机理提供了理论基础，并为流态化干法分选的精准调控提供了理论保障。

Due to the contradiction between the distribution of coal and water resources in China,it is of great significance to develop dry separation technologies for coal processing.Dry dense medium fluidized bed provides an effective way to solve the problem of coal separation in arid regions due to its high separation efficiency and low investment. Dry dense medium separation fluidized bed belongs to the research field of bubbling fluidization.The bed contains bubbles,medium particles and coal particles.It is very important to capture precisely the movement behavior of bubble phase and separating minerals.It is crucial to reveal the gas solid phase interaction and the density segregation of coal particles.The above capture is also beneficial for understanding the separation mechanism.  Electrical capacitance tomography(ECT),as a non embedded three dimensional imaging measurement method,can accurately capture the fluidization behavior without affecting the normal operation of the fluidized bed.The study firstly focused on the capture of bubble behavior by the ECT based on the difference of dielectric constant between air and dense medium.The mathematical models of bubble growth and velocity were established with high precision.The ECT was then used to explore the movement behavior of coal particles.The feasibility of tracing coal using the ECT was confirmed by the COMSOL simulation.The impacts,including operating conditions and coal properties,were further analyzed on the movement behavior. The research verified the reliability of the real time capture of coal particles in axial and radial directions.Through the capture of bubble phase and coal particles,the distribution of gas solid phases in the bed was analyzed for establishing separation density model.  According to the theoretical separation density model,the error is less than 20% between the predicted value and the experimental data,providing a theoretical basis for the precise density regulation of dry separation process.  The research realizes the non embedded imaging capture of bubbles in the dry dense medium separation fluidized bed,breaking the limitations of traditional methods,such as optical fiber probe and two dimensional imaging,solves the difficult problem of directly observing the separating process of coal and realizes the tracing of coal trajectory.  It provides a theoretical basis for further understanding the gas solid two phase distribution in fluidized bed. 

1 试验

2 研究原理及方法

   2.1 气泡特性测试方法

   2.2 煤炭示踪测试方法

   2.3 干法分选流化床分离机制研究方法

3 结果与讨论

   3.1 气泡运动行为

   3.2 煤颗粒运动行为

   3.3 分选密度模型的建立

4 结论