鼓泡流化床异质颗粒混合特性微观研究

开发了一种基于电容探针的稠密气固两相流中异质颗粒混合特性测试新方法。研究了鼓泡流化床内异质颗粒混合过程中微观混合比的变化规律,分析了流化床一系列位置处对流与扩散机制对于混合过程的作用规律及其微观机理。结果表明:随着流化床床层高度的增加,对流机制对于颗粒混合的作用先增大后减小;壁面处微观混合比随着混合时间出现小幅波动,主要表现出扩散混合行为;不同高度处颗粒达到混合平衡所需时间无明显差异,而壁面处颗粒达到混合平衡所需时间是轴线处颗粒混合时间的2倍左右;混合平衡状态下最终微观混合指数相近。

Microstudy on mixing characteristics of dissimilar particles in bubbling fluidized beds

A novel method for measuring the mixing characteristics of dissimilar particles in dense gas-solid two-phase flow based on a capacitance probe was developed. In the mixing process, the variation in the micromixing ratio of dissimilar particles in a bubbling fluidized bed was studied. The influence of convection and diffusion on the mixing of particles at a series of locations in the bubbling fluidized bed and its micromechanism were analyzed. Results show that with increasing bed height, the influence of convective mixing on the mixing of particles first increases and then decreases. The mixing ratio near the wall fluctuates slightly with the mixing time and mainly shows diffusion mixing behavior. No considerable difference is observed in the time required for particles to reach mixing equilibrium at different bed heights, and the time required for particles to reach mixing equilibrium near the wall is approximately twice as long as that at the axial positions. However, the final micromixing indices are similar in the mixing equilibrium state.