项目名称: 气固下行循环流化床的增浓机制及调控方法研究
项目编号: No.21506253
项目类型: 青年科学基金项目
立项/批准年度: 2016
项目学科: 有机化学
项目作者: 王成秀
作者单位: 中国石油大学(北京)
项目金额: 21万元
中文摘要: 重质油高效转化和优化利用是国民经济发展的重大需求,具有十分重要的现实意义和战略意义。提升管催化裂化是重油轻质化的重要手段。提升管的不均匀环核结构及气固返混特性降低了重油转化率和产品选择性。相对于提升管,下行床具有近平推流流型及气固短停留时间的优点,处理重油具有潜在优势。下行床内颗粒浓度过低且气固初始接触较差限制其推广及应用。关于下行床内颗粒增浓的机制尚未清楚。本项目拟从下行床入口结构出发,深入研究其对实现下行床高密度操作的影响,明确其对提高颗粒浓度及实现气固均匀接触的贡献;进而着眼于整个循环系统,优化各单元间的匹配性,探索高密度下行床稳定运行的调控方法。综合上述研究结果,揭示下行床颗粒增浓机制,全面认识高密度下行床的气固整体流动及多尺度结构特性,建立准确描述高密度下行床流动特征的多尺度模型并揭示下行床反应器放大规律,从而为下行床催化裂化技术开发及高密度下行床应用推广提供基础数据和理论支持。
中文关键词: 气固下行循环床;高密度;调控方法;放大效应;计算流体力学
英文摘要: The efficient conversion and optimal utilization of heavy oil has great practical significance to the development of national economy. Fluid catalytic cracking (FCC) is a critical approach to deal with heavy oil. Riser, as the key part of the FCC unit, is characterized by the non-uniform “core-annuals” flow structure with relatively significant gas and solids backmixing which may result in low reactant conversion and product selectivity. Downer reactor, in which gas and solids move downward co-currently, has unique features such as the plug-flow reactor performance and relatively uniform gas-solids distribution compared to the riser reactor. Downer is therefore acknowledged as a novel multiphase flow reactor with great potential in dealing with heavy oil. However, low solids holdup and poor initial gas-solids contacting hinder the promotion and application of downer reactor. Mechanism of increasing solids holdup and approaching high density downer has not been well understood. This project will start from the entrance of the downer to in-deep investigate its effects on high density operating condition and to study the contributions of the downer entrance to accomplishing high solids holdup and good gas-solids contacting and in downer reactor. On the other hand, all parts of the entire circulation system will be optimized in order to develop a regulation and control method to obtain and maintain a stable operating of the high density downer. Based on the above work, the mechanism of achieving the high density downer will be demonstrated, a multi-scale computational model will be established to preciously describe the hydrodynamic characteristics and the scale-up of high density downer will be illustrated all of which will provide the fundamental data and basic theoretical support to develop a technology of downer catalytic cracking of heavy oils and extend the applications of high density downer reactors.
英文关键词: gas-solids CFB downer;high density;regulation-control method;scale up ;CFD