循环流化床中的气固传质
文献类型：学位论文
| 作者 | 李杰 |
| 学位类别 | 博士 |
| 答辩日期 | 1998-12-02 |
| 授予单位 | 中国科学院研究生院 |
| 导师 | 李静海 |
| 关键词 | 气固传质 循环流化床 团聚体 在线质谱 |
| 其他题名 | Gas-Solid Mass Transfer in Cirdulating Fluidized Beds |
| 学位专业 | 流态化工程 |
| 中文摘要 | 通过采用对非均匀流动结构进行分解的方法，本论文从颗粒微尺度、团聚体宏尺度和非均匀气固两相流的宇尺度的三个尺度研究了气固两相流中气固传质过程。首先，分析均匀体系中颗粒与周围流体间传递特性，提出了沿流域的三段传质模型，给出了解析表达式。然后通过设计人工模拟颗粒团聚体并进行传质实验，给出了团聚体的自身特性（包括：团聚体大小，形状，内部空隙率和气固滑移速度）以及体系特性（空隙率，聚团大小以及聚团的空间分布）对气固传质速率的影响规律，阐明了颗粒的动态效应在气固传质中的主导地位。最后，通过实验研究循环流化床中的流动结构及气固传递过程，给出了传质速率随流域和空间位置的变化规律，并说明非均匀体系中的气固传质速率不仅与局部空隙率和气固滑移速度有关，而且在很大程度上由非均匀流动结构以及动态效应所控制。论文结尾提出了动态多尺度气固传质数学模型。 |
| 英文摘要 | This work is devoted to understanding the gas-solid mass transfer processes in circulating fluidized beds with respect to three scales: micro scale of particle, meso-scale of cluster and macro-scale of unit. First of all, gas-solid mass transfer in three different regimes of homogeneous gas-solid flow is quantified by analyzing the transport behavior around a single particle and making necessary modifications. Then, mass transfer experiments between specially designed artificial cluster(s) and air were carried out to quantitatively understand the effect the cluster properties, including cluster size, internal voidage, shape and cluster-air slip velocity, on the gas-cluster mass transfer rate and the effect of system properties, including cluster size, system voidage and spatial distribution, on total gas-solid mass transfer rate. Afterwards, by comparing mass transfer rates of the static artificial cluster system with that of the real gas-solid system, the contribution of the dynamic formation and dissolution of clusters in gas-solid mass transfer was estimated, which is dominant for the overall mass transfer rate. Finally, experiments of hydrodynamics for determining flow regimes and flow structures, and of gas-solid mass transfer were conducted in a circulating fluidized bed to understand gas-solid mass transfer in heterogeneous two-phase flow. It is indicated that 1) heterogeneous flow structure reduces the efficient gas-solid mass transfer rate, 2) there exists uneven gas-solid mass transfer rate distribution in circulating fluidized bed, displaying an "ε" distribution along the bed height and inverse "U" distribution across the radial direction. 3) mass transfer rate in heterogeneous two-phase flow is related not only to local voidage and gas-solid slip velocity as the case in homogeneous two-phase flow, but also to its heterogeneous flow structures and dynamic behaviors. Accordingly, a Multi-scale Dynamic Gas-solid Mass Transfer Model, which includes both heterogeneity and dynamic property for the heterogeneous two-phase flow system was proposed. |
| 语种 | 中文 |
| 公开日期 | 2013-09-27 |
| 页码 | 228 |
| 源URL | [http://ir.ipe.ac.cn/handle/122111/2020]  |
| 专题 | 过程工程研究所_研究所（批量导入） |
| 推荐引用方式 GB/T 7714 | 李杰. 循环流化床中的气固传质[D]. 中国科学院研究生院. 1998. |
入库方式： OAI收割
来源：过程工程研究所
浏览0
下载0
收藏0
其他版本
除非特别说明，本系统中所有内容都受版权保护，并保留所有权利。