挥发性有机物的循环流化床吸咐净化
文献类型：学位论文
| 作者 | 宋文立 |
| 学位类别 | 博士 |
| 答辩日期 | 2003 |
| 授予单位 | 中国科学院过程工程研究所 |
| 授予地点 | 中国科学院过程工程研究所 |
| 导师 | 李静海 |
| 关键词 | 循环流化床 挥发性有机物 传质 吸附 |
| 其他题名 | Volatile Organic Compounds Emission Control by Circulating Fluidized Bed Adsorption |
| 中文摘要 | 挥发性有机物（Volatile Organic Compounds，VOCs）是石油、化工及其相关行业排放的最常见的空气污染物。目前，已有几种采用多层鼓泡流化床的低浓度VOCs吸附处理工艺进入工业应用，但还没有采用循环流化床进行吸附净化处理的报道。循环流化床（Circulating Fluidized Bed，CFB）通常操作在高气固通量的快速流态化状态下。循环流化床内的传热速率很高可以达到几乎等温的工况。相对于鼓泡流化床，循环流化床内的气固接触效率更好，操作气速也更高，所以循环流化床吸附工艺应该是VOCs污染控制的一条可选择的新途径。目前还没有循环流化床吸附过程得到工业应用。其主要原因是对于循环流化床内气固流动和传递过程缺乏了解，及因此造成的循环流化床反应器的设计、预测和评价的困难。本文对涉及VOCs的循环流化床吸附净化工艺的吸附等温线、循环流化床提升管内的流体动力学、气固之间的传质以及循环流化床内的吸附过程进行了研究。建立了间歇操作的CFB吸附实验装置，在不同条件下进行了CFB吸附实验。采用重量法测量了Ambersorb 600／甲苯体系的吸附等温线，在实验温度范围内它可以用Dubillin-Astalchov 方程描述。用修改的EMMS局部模型与Kunii和Levenspiel的夹带模型相结合，建立了描述循环流化床提升管内气固流动的一维模型。从而得到了描述床内各处聚团相与稀相具体结构的结构与流动参数，并讨论了操作条件的影响。在此基础上建立了EMMS传质模型用于计算气固间外传质系数。研究证明，循环流化床内聚团的存在是影响气固传质的主要因素。外部传质系数随表观气速的增加或固体循环速率的减小而提高。所建立的一维吸附模型可以较好的描述循环流化床提升管内的吸附过程。表观气速的增加将使吸附质浓度沿床高的下降速度减慢，而固体循环速率的增加将使吸附质浓度沿床高的下降速度加快；对于Ambersorb 600／甲苯体系，在气相效率为99％时，固相效率为56％；采用多级循环流化床吸附系统可以增加吸附器的固相效率，同时也可以降低吸附剂的再生循环流量，即再生器的负荷本文还讨论了循环流化床吸附器基本参数的设计步骤；并对循环流化床变温、变压吸附净化系统的设计进行了讨论。 |
| 英文摘要 | Volatile Organic Compounds (VOCs) are the most common air pollutants emitted from chemical, petrochemical and allied industries. Several adsorption systems employing multi-stage bubble fluidized bed have been developed and operated in practice for dilute VOCs emission control, but no such process with CFB reactors has been reported. The CFB are usually operated in the fast fluidization regime with high gas and solids throughput. The heat transfer inside the CFB is much faster and nearly isothermal conditions could be obtained. With improved gas-solid contacting and higher operation velocity than in a bubble fluidized bed, the CFB adsorption process is thus an alternative for emission reduction of dilute VOCs. Despite the advantages, the CFB reactor has not been used in industries for adsorption process until now. This mainly results from the lack of knowledge of hydrodynamics and transfer process involved in the CFB reactor, entailing difficulties in design, in extrapolation, in evaluation of performances. In this study, we discussed the adsorption isotherm of adsorbate/adsorbent system, the hydrodynamics of gas and solid adsorbent particles in CFB riser, the mass transfer between gas and solid particle and the adsorption process inside the riser. The adsorption experiments with CFB test unit were also conducted. The adsorption isotherm measurement for Ambersorb 600/toluene system has been conducted and the isotherm can be presented very well by Dubinin-Astakhov equation. A one-dimensional model for gas-solid two-phase flow in a CFB riser has been established by combining the modified Energy Minimization Multi-Scale (EMMS) model describing the local hydrodynamics and Kunii and Levenspiel's entrapment model for axial voidage distribution. This new model was then used to estimate variables such as solid volume fraction and size of clusters, gas and solid velocities, and slip velocities between gas and solid particles and between dilute and cluster phases. Based on this, the external mass transfer coefficient between gas and solid particles was obtained. The research results shows that, the formation of clusters has significant influence on the mass transfer process. Higher superficial gas velocity and lower solid circulating rate will result in higher external mass transfer coefficient between gas and solid particle The proposed one-dimensional adsorption model can be used to describe the adsorption process in CFB riser. The higher superficial gas velocity and lower solid circulating rate will result in slower VOCs concentration reduction along the riser. For Ambersorb 600/toluene system, the experimental results show that while maintaining gas phase efficiency at 99%, the solid phase efficiency could reach 56%. The multi-stage CFB adsorber will increase the solid phase efficiency, reducing the adsorbent regeneration re-circulating rate and also the load of regenerator. The design procedures for the CFB adsorber were discussed; the possible designs of CFB-PSA system and CFB-TSA system for emission control were also presented. |
| 语种 | 中文 |
| 公开日期 | 2013-09-16 |
| 页码 | 127 |
| 源URL | [http://ir.ipe.ac.cn/handle/122111/1402]  |
| 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 | 宋文立. 挥发性有机物的循环流化床吸咐净化[D]. 中国科学院过程工程研究所. 中国科学院过程工程研究所. 2003. |
入库方式： OAI收割
来源：过程工程研究所
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