Abstract Residence time distribution (RTD) is a key issue of many chemical reactors, and the degree of back-mixing determines the reaction conversion and selectivity. In the present study, the relationship between time-average solids fraction and back-mixing behavior has been carefully investigated by experimental and model study. A 2-D dispersion model is introduced to describe RTD and the back-mixing in a gas-solid fluidized bed is quantitatively expressed by axial and radial Peclet Numbers. Both the axial and radial Peclet numbers are obtained via tracer techniques, and solid fractions, as the indicator of gas solids interaction, is also quantified by an optical detector. Furthermore, a relationship between solid fraction and Peclet Number is developed via Einstein equation and concept of potential energy barrier. The results indicate that dense solid phase can decrease the potential energy barrier of back-ward jump against main flow.

中文翻译：

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流化床固相率与返混关系模型及实验研究

摘要 停留时间分布（RTD）是许多化学反应器的关键问题，返混程度决定了反应的转化率和选择性。在本研究中，时间平均固体分数与返混行为之间的关系已通过实验和模型研究进行了仔细研究。引入二维弥散模型来描述RTD，气固流化床中的返混用轴向和径向Peclet数定量表示。轴向和径向 Peclet 数都是通过示踪技术获得的，作为气固相互作用指标的固体分数也由光学检测器量化。此外，固体分数和佩克莱数之间的关系是通过爱因斯坦方程和势能势垒的概念发展起来的。