返回
类型 基础研究 预答辩日期 2017-12-04
开始(开题)日期 2014-01-24 论文结束日期 2017-11-06
地点 热能所一楼会议室 论文选题来源 973、863项目     论文字数 7 (万字)
题目 交互循环双流化床气固流动特性研究
主题词 双流化床,气固两相流,数值模拟,颗粒交互循环
摘要 双流化床是一种由两个流化床单元通过动力链接耦合而成的反应器,,由于此类反应器具有解耦热化学反应实现优化控制及产物分离等优势,近年来众多研究者对双流化床在燃料的高效利用和分级转化等方面应用进行了探索。然而,由于双流化床的物理结构与内部流动机理相对复杂,目前对其气固流动特性的掌握并不充分,尤其是对其颗粒循环与协调耦合机制的认识尚不能完全满足应用要求,因此亟需对交互循环双流化床气固流动特性进行系统的研究以指导设备的设计、运行和优化需求。 本文构建了由两个尺寸相同的快速流化床单元对称构成的交互循环双流化床冷态试验系统,每个快速流化床单元均由上升管、下降管、旋风分离器、Loop seal气动返料阀组成。通过在较宽工况条件范围内的试验研究,在流化床单元内实现了四种气固流动结构,包括湍动流动(Turbulent Flow/TF)、团聚流动(Cluster Flow/CF)、环核流动(Annular Flow/AF)和悬浮流动(Suspension Flow/SF),掌握了双流化床的耦合操作特性,并在此基础上成功构建了五类耦合运行模式(CF-CF、CF-TF、CF-AF、AF-AF以及AF-SF)。 通过采用对称参数及非对称参数两类操作方法,系统地分析了双流化床内压力分布、床层压降、颗粒浓度分布等气固流动特征参数随装置存料量、上升管流化风量、返料阀返料风量、返料阀返料风量等操作参数的变化规律,并基于试验数据构建了对称型交互循环双流化床的全场压力平衡模型。此外,通过处理时序压差数据分析了流化床单元上升管内的全高度颗粒浓度波动特性,揭示了各操作参数对双流化床反应器内动态颗粒浓度波动强度及运行稳定性的影响规律。 基于已有微波颗粒测量的相关研究基础,发展了一种适用于双流化床装置的在线、实时、非侵入性的微波动态质量流量测量系统,并借助此系统实现对所建立交互循环双流化床内的颗粒循环流量的高频率动态连续测量,通过对时序颗粒质量流量标准差及变异系数的分析,揭示了交互循环双流化床流化床单元间连续颗粒循环的波动强度及循环稳定性随操作参数的变化规律。 基于颗粒动理学理论,针对双流化床内的复杂气固流动过程构建了的三维欧拉-欧拉数值计算模型及模拟方法,随后以串行结构双流化床和并行结构双流化床为对象分别构建了三维物理模型,并实现了三维维度上的双流化床全场气固流动数值模拟,在此基础上对流动结构、颗粒分布、速度分布等重要流体动力学特性以及双流化耦合运行失稳机理等试验中难以观测的气固流动特性开展了研究。
英文题目 EXPERIMENTAL STUDY ON HYDRODYNAMIC CHARACTERISTICS OF AN INTERACTING DUAL FLUIDIZED BED
英文主题词 dual fluidized bed, gas-solid flow,computational simulation, solids circulation
英文摘要 Dual fluidized bed (DFB) is a reactor which consists of two fluidized bed units coupled by linking structures such as valve or some similar devices. In recent years, on count ofits advantages in decoupling thermo chemical reaction to realize optimization and products separation, many researchers have conducted investigations on the possibility of appling dual fluidized bed in step conversion and efficient utilization of fuels.However, due to the complex physical structure and internal flow mechanism, the understanding of gas solid flow characteristics in dual fluidzed bed is not sufficient. Especially the mechanism of solids circulation and coupling has not been well studied to meet the requirements of practical applications of dual fluidized bed reactors. Therefore, it is urgent to conduct systematic research on gas solid flow characteristics in dual fluidzed bed to guide the design, operation and optimization of similar devices. An interacting dual fluidized bed cold model with two same fast fluidized bed units was built in this work. Each fluidized bed unit consists of riser, downcomer, cyclone separator and loop seal valve. With experimental study in a relative wide range of operation parameters, four flow regimes were realized in this work, i.e. turbulent flow, cluster flow, annular flow and suspension flow. The coupling operation experience was also gained in the experimental study. And five coupling patterns are formed based on operation experiments(CF- CF, CF-TF, CF-AF, AF-AF, AF-SF). By applying symmetrical and non-symmetrial operation conditions, the effects of operatingparameters(solid inventory, riser aeration flow rate, loop seal aeration flow rate) on pressure distribution, pressure difference in bed, solids concentrations distribution and other gas solid flow characteristic parameters were investigated. The full loop pressure balance model was also developed with experimental pressure distribution data. By analyzing the time-series pressure difference data to investigate the solid concentration fluctuation in full height of risers, the influences of operation parameters on fluctuation strength and operation stability of solid concentration was revealed. Based on related researches about microwave flow rate monitoring, anon-line, real-time, non-intrusive microwave solids flow measurement system which is suitable for applications in dual fluidized bed was developed for the successive dynamic measurement of solids flow. By analyzing the average deviation and coefficient of variation of time-series solid circulation rates, the influences of operation parameters on fluctuation strength and circulation stability of solid interaction between fluidized bed units was revealed. The three dimensional Eulerian-Eulerian computational fluid dynamic (CFD) model and simulation method for dual fluidized bed simulation were developed based on kinetic theory of granular flow. Then, the physical model of dual fluidized beds were built and three dimensionalfull loop simulation of dual fluidized bed was realized for the first time. Baesd on the full loop simulation, Key gas-solid flow behaviors related to gas-solid circulation behaviors and instalibilty mechanism which are hard to be acquired in experimental study, e.g. the transient flow regime, solid velocity, solids distribution, circulation characteristics, were numerically investigated.
学术讨论
主办单位时间地点报告人报告主题
中国工程热物理学会 2014.11 西安 耿察民 双循环流化床颗粒分布特性的三维数值模拟
东南大学,Monash University 2014.12 苏州 耿察民 交互循环双流化床气固流动特性研究
哈尔滨工业大学 2015.7 哈尔滨 耿察民 Experimental and Simulation Study on an Interacting Dual Circulating Fluidized Bed
University of Nottinghanm 2016.6 Nottingham 耿察民 Development of microwave solids flow indicator for testing of Dynamic Solids Circulation rate in Fluidized Bed
东南大学 2017.3 南京 刘超群 DNS Study on Relation between Vorticity and Vortex
中国工程热物理学会 2016.12 成都 耿察民 Experimental Study of Dynamic Solids Circulation in a Dual Circulating Fluidized Bed with symmetrical structure
东南大学 2017.7 南京 刘浩 富氧燃烧及二氧化碳补集专题
东南大学 2016.10 南京 贲昊玺 Conversions of Biomass to Energies, Fuels, Chemicals and Materials: Unlocking the Secrets to a Sustainable Future
     
学术会议
会议名称时间地点本人报告本人报告题目
中国工程热物理学会 2014.11 西安 双循环流化床颗粒分布特性的三维数值模拟
中国工程热物理学会 2016.12 成都 Experimental Study of Dynamic Solids Circulation in a Dual Circulating Fluidized Bed with symmetrical structure
哈尔滨工业大学 2015.7 哈尔滨 Experimental and Simulation Study on an Interacting Dual Circulating Fluidized Bed
University of Nottinghanm 2016.6 Nottingham Development of microwave solids flow indicator for testing of Dynamic Solids Circulation rate in Fluidized Bed
     
代表作
论文名称
Computational study of solid circulation in chemical-looping combustion reactor model
Experiments on particles flow in a dual circulating fluidized bed with symmetrical structure
双循环流化床颗粒分布特性的三维数值模拟
 
答辩委员会组成信息
姓名职称导师类别工作单位是否主席备注
章名耀 正高 教授 博导 东南大学能源与环境学院
刘德彰 正高 教授 博导 南京航空与航天大学能源与动力学院
肖睿 正高 教授 博导 东南大学能源与环境学院 东南大学能源与环境学院院长
卢平 正高 教授 博导 南京师范大学能源与机械工程学院 南京师范大学能源与机械工程学院院长
袁竹林 正高 教授 博导 东南大学能源与环境学院
      
答辩秘书信息
姓名职称工作单位备注
王沛 其他 讲师 东南大学能源与环境学院