循环流化床中颗粒团聚物对颗粒停留时间分布影响的CFD研究

项目名称： 循环流化床中颗粒团聚物对颗粒停留时间分布影响的CFD研究

项目编号： No.21306202

项目类型： 青年科学基金项目

立项/批准年度： 2014

项目学科： 化学工业

项目作者： 华蕾娜

作者单位： 中国科学院过程工程研究所

项目金额： 25万元

中文摘要： 作为衡量循环流化床颗粒宏观混合程度的主要指标，颗粒停留时间分布(RTD)的优化在提高产品选择性和转化率等方面起着重要的作用。循环流化床中颗粒团聚物不断地形成和破碎，造成了颗粒返混严重。因此颗粒RTD具有较长的停留时间和较宽的区间分布，表现出双峰和长拖尾等特点。虽然CFD方法在气固流动方面获得了广泛地应用，但在颗粒RTD方面的研究却较少。本项目拟建立一个适用于工业规模装置的计算颗粒RTD的CFD模型，并通过多尺度分析方法修正气固相间曳力和示踪剂扩散系数，以考虑颗粒团聚物对气固流动特性和颗粒RTD的影响。具体而言，我们首先利用双流体模型获得气固流动特性；然后再将少量示踪剂以脉冲方式注入床内，求解组分输运方程监测示踪剂浓度的变化，得到颗粒RTD；最后通过系统分析操作条件、颗粒物性和设备结构等对颗粒RTD的影响，确定出关键因素，为工业规模反应器的设计、优化和放大提供理论指导和技术支持。

中文关键词： 循环流化床；颗粒团聚物；颗粒停留时间分布；计算流体力学；

英文摘要： As a main indicator of solids mixing in CFB, solids residence time distribution (RTD) plays an important role in the enhancement of the production. In fast fluidization, clusters are forming and breaking up constantly, which results in serious solids mixing. Therefore solids RTD has a longer residence time and wider distribution form, which is charaterized by a two-peak and long tail. CFD has been used widely in gas-solids hydrdynamic simulation, but less in solids RTD field. This study will establish a CFD model suitable for industrial devices, which considers the influence of particle clusters on gas-solid and tracer flow behaviour through modifying gas-solid drag force and tracer diffusive coefficient by the multi-scale method. Firstly, two-fluid model is used to describe the hydrodynamic property of gas-solid, and species transport equation is solved to obtain solids RTD; and then several factors,including operating conditions, particle properties, and equipment structures, are investigated to provide theoretical and technical guides for the design, optimization and scale-up of industrial reactors.

英文关键词： Circulating fluidized bed；particle cluster；particle residence time distribution；Computational fluid dynamics；