化学链燃烧双流化床反应器内流动与传热的数值模拟

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3.0 牛悦 2024-11-19 4 4 3.97MB 118 页 15积分
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摘 要
化学链燃烧技术(Chemical Looping Combustion, CLC)是一种新颖的燃烧技术，
由于具有较高的燃烧效率、彻底消除了NOX污染物的排放以及CO2内分离不需消耗
额外能量的特点而受到了国内外广泛的关注。目前，化学链燃烧能源动力系统已
成为世界能源与环境系统研究的重要方向，它的理论、实验研究及工程应用对于
减少NOX污染物的生成和CO2的排放以及燃料的高效燃烧具有重要的意义，是解决
节能与CO2减排主要发展的先进技术之一。
本课题基于 Linux 操作系统的联想深腾 1800 并行计算平台，运用计算流体力
学软件 Fluent6.3 软件，以欧拉-欧拉多相流模型、颗粒动力学理论和气固非均相化
学反应动力学为基础，对化学链燃烧反应装置—空气与燃料流化床内气固两相流
动、传热及化学反应过程进行 CFD 数值模拟与分析，相关结论将为化学链燃烧过
程中气固化学反应特性的研究提供参考依据。
本文首先通过查阅相关文献，确定了研究所需的化学链燃烧的实验装置，建
立了合理的气固流动、传热及化学反应动力学模型，并嵌入自行编写的气固非均
相化学反应、相间传质及反应放热的UDF（User Defined Model，用户自定义函数）
程序，通过CFD数值模拟计算了燃料反应器内流动与传热的过程，并与文献中的
实验数据进行了验证，结果表明与二者有着较好的一致性。
模拟计算与分析了甲烷进气速度为0.1m/s、颗粒进口速度为0.015m/s时燃料反
应器内流动、传热的情况，得到了燃料反应器内载氧剂颗粒体积分率的分布、气
固相速度矢量场、气固相温度、气固反应物及生成物浓度分布场等规律。
计算并对比分析了甲烷进气速度分别为0.075m/s、0.12m/s、0.15m/s，颗粒进
口速度为0.015m/s时燃烧反应器内流动与传热的情况，得到了甲烷进气速度对化学
链燃烧反应器内流动、传热、化学反应速率及燃烧效率的影响规律。
计算并对比分析了在甲烷进气速度为0.13m/s，颗粒进口速度为0.075m/s/时平
均粒径分别为0.00015m、0.00022m和0.00035m三种载氧剂颗粒对化学链燃烧气固
流动及化学反应速率的影响规律，分析了提高甲烷燃烧效率的方法。
模拟计算并分析了化学链燃烧空气反应器-快速流化床内载氧剂颗粒与空气
（氧气）进行气固相氧化反应的过程，得到了载氧剂颗粒体积分率的分布、气固
相速度矢量场、气固相温度、气固反应物及生成物浓度分布场等规律。
最后对化学链燃烧空气与燃料反应器的串行反应过程进行了数值模拟，这样
从理论上有机地将二者的流动与传热过程联系了起来，为以后化学链燃烧整个氧
化还原反应过程的实验研究和模拟计算提供理论依据。
关键词：化学链燃烧 流化床反应器 气固非均相反应 欧拉-欧拉多相
流模型 载氧剂颗粒 数值模拟
ABSTRACT
Chemical looping combustion (CLC) has been concerned world-widely, because it
is a novel combustion process with higher combustion efficiency, inherent CO2
separation without NOx and extra energy losses. Recently, the energy and power system
of chemical looping combustion has been one of the important research fields of the
world-wide power and environment system. Its theoretical, experimental researches and
engineering applications will be helpful to the elimination of emission of NOx
pollutions, the reduction of CO2emission and the higher fuel combustion efficiency, as
one of the key and advanced technologies for energy-saving and reduction of CO2
emission.
Choosing Computational fluid dynamics software Fluent 6.3 as the flow solver on
the Linux based Lenovo parallel computing system, the Eulerian-Eulerian multiphase
fluid model, kinetic theory of granular and the kinetic model of the gas-solid
heterogeneous chemical reactions were used to simulate and analyze the characteristics
of gas and solid flow, heat transfer and chemical reactions in the air and fuel reactors of
chemical looping combustion. The related conclusions will be used as the references for
the numerical study of gas-solid chemical reactions characteristics of the chemical
looping combustion process.
In this paper, lots of related references of the chemical looping combustion have
been reviewed, and the chemical reaction reactors were found, the reasonable models of
the gas-solid flow, chemical reactions and heat transfer process were built, and the UDF
(User defined Function) programs on the chemical reactions kinetic model, the mass
and heat transfer between gas and solid phase were added in the Fluent 6.3, the
PC-SIMPLE method and the standard
k
dispersed turbulent model were adapted ,
the gas-solid flow process and chemical reactions of the chemical looping combustion
in the air and fuel reactors were modeled.
Simulation results were compared with the experimental data. The comparison
shows that the results of numerical simulation were in good agreement with
experiments. With the numerical simulation, the solid volume fraction distribution,
composition profiles of gas reactants and products, temperature distributions of gas and
solid phases and chemical reaction rates in the fuel reactor were obtained.
Firstly, the gas-solid flow and heat transfer processes in the fuel reactor were
simulated and analyzed under the following conditions: the inlet velocity of methane
was 0.1 m/s, and the inlet velocity of the particle was 0.015 m/s. The gas and solid
volume distribution, the gas-solid phase velocity magnitude and vector field, gas-solid
temperature, gas-solid concentration distribution of the reactants and the products were
obtained.
Then, the gas-solid flow and heat transfer processed were simulated and compared
under the following conditions: the inlet velocity of methane were 0.075 m/s, 0.12m/s,
0.15m/s, and the inlet velocity of particle was 0.015 m/s. The influences of methane gas
inlet velocities on gas-solid flow feature, heat transfer and chemical reaction rates were
analyzed and obtained.
Secondly, the gas-solid flow and heat transfer processes in the fuel reactor were
simulated and compared under the conditions: the inlet velocity of methane was 0.13
m/s, and the inlet velocity of particle was 0.075 m/s, and the average particle size were
0.00015m, 0.00022m and 0.00035m. The influences of different particle size on
gas-solid flow feature, heat transfer and chemical reaction rates were obtained, and how
to improve the methane combustion efficiency also was analyzed.
Thirdly, the gas-solid flow characteristics and heterogeneous oxidation reaction
process was simulated. The distribution of the oxygen carrier particle volume fraction,
gas-solid phase velocity magnitude and vector of field, gas-solid temperature, gas-solid
concentration distribution of reactants and the combustion efficiency were obtained.
Finally, the gas-solid flow and heat transfer processes of the chemical looping
combustion in the two interconnected beds, the air (the fast fluidized bed) and fuel
reactor (the spouted fluidized bed) were simulated. By this means, the characteristics of
flow, chemical reactions and heat transfer between the two separated reactors were
linked up organically by the theory. The related conclusions of the interconnected
chemical looping combustion will provide the theoretical guidances for the future
experimental and simulations researches of the whole oxidation-reduction reaction
process of chemical looping combustion.
Key words: chemical looping combustion, fluidized bed reactor,
gas-solid heterogeneous chemical reactions, Eulerian-Eulerian
multiphase flow model, oxygen-carrier particles, numerical simulation
目 录
中文摘要
ABSTRACT
第一章 前 言 ...................................................................................................................1
第二章 文献综述 .............................................................................................................3
§2.1 引言 ...................................................................................................................3
§2.2 化学链燃烧技术 ...............................................................................................3
§2.2.1 化学链燃烧技术简介 .............................................................................3
§2.2.2 化学链燃烧气固反应流程 .....................................................................5
§2.2.3 化学链燃烧的研究热点 .......................................................................10
§2.3 流态化技术基础 .............................................................................................11
§2.3.1 流态化现象 ...........................................................................................11
§2.3.2 颗粒的分类方法 ...................................................................................12
§2.3.3 流化床中的气泡及其对流化质量的影响 ...........................................14
§2.3.4 流态化技术的优点 ...............................................................................14
§2.4 本课题的研究意义和主要工作 .....................................................................15
第三章 化学链燃烧的数值模拟方法 ...........................................................................17
§3.1 计算流体力学在气固两相流研究中的应用 .................................................17
§3.2 气固两相流模型 .............................................................................................18
§3.2.1 欧拉-拉格朗日法 ................................................................................. 18
§3.2.2 欧拉-欧拉法 ......................................................................................... 18
§3.3 气固两相流动力学方程 .................................................................................19
§3.4 化学反应机理 .................................................................................................24
§3.5 数值模拟方法 .................................................................................................26
§3.6 本章小结 .........................................................................................................27
第四章 燃料反应器内流动与传热的数值模拟 ...........................................................28
§4.1 引言 .................................................................................................................28
§4.2 燃料反应器的几何结构及计算参数 .............................................................28
§4.2.1 燃料反应器流化床几何结构 ...............................................................28
§4.2.2 模拟参数设定 .......................................................................................29
§4.3 计算模型验证 .................................................................................................30
§4.4 计算结果与讨论 .............................................................................................31
§4.4.1 甲烷进气速度为 0.1m/s 时的计算结果及讨论 .................................. 31
§4.4.2 甲烷进气速度对化学链燃烧效率的影响 ...........................................38
§4.4.3 颗粒粒径大小对化学链燃烧效率的影响 ...........................................42
§4.5 本章小结 .........................................................................................................49
第五章 空气反应器内流动与传热特性的数值分析 ...................................................52
§5.1 引言 .................................................................................................................52
§5.2 空气反应器的几何结构及操作条件 .............................................................53
§5.2.1 空气反应器流化床几何结构 ...............................................................53
§5.2.2 模拟参数设定 .......................................................................................54
§5.3 计算结果及讨论 .............................................................................................55
§5.3.1 颗粒体积分率分布规律 ........................................................................55
§5.3.2 气固速度分布规律 ................................................................................57
§5.3.3 气固温度分布规律 ................................................................................60
§5.3.4 气固化学反应速率及内热源项的分布 ................................................61
§5.3.5 气体组分的分布规律 ............................................................................62
§5.3.6 空气反应器轴向压力变化规律 ...........................................................64
§5.4 本章小结 .........................................................................................................64
第六章 燃料与空气反应器串行过程的数值模拟 .......................................................66
§6.1 引言 .................................................................................................................66
§6.2 空气与燃料反应器的几何结构及网格划分 .................................................66
§6.3 计算参数设置 .................................................................................................68
§6.4 计算结果与分析 .............................................................................................70
§6.4.1 空气与燃料反应器内颗粒分布情况 ...................................................70
§6.4.2 空气与燃料反应器内速度分布情况 ...................................................72
§6.4.3 空气与燃料反应器内温度分布情况 ...................................................74
§6.4.4 空气与燃料反应器内化学反应速率分布情况 ...................................75
§6.4.5 空气与燃料反应器内反应组分分布情况 ...........................................77
§6.4.6 空气与燃料反应器内反应气体氧化与还原程度的分布 ...................78
§6.5 本章小结 .........................................................................................................79
第七章 结 论 .................................................................................................................80
§7.1 本文总结 .........................................................................................................80
§7.2 工作不足与展望 .............................................................................................82
摘要：

摘要化学链燃烧技术(ChemicalLoopingCombustion,CLC)是一种新颖的燃烧技术，由于具有较高的燃烧效率、彻底消除了NOX污染物的排放以及CO2内分离不需消耗额外能量的特点而受到了国内外广泛的关注。目前，化学链燃烧能源动力系统已成为世界能源与环境系统研究的重要方向，它的理论、实验研究及工程应用对于减少NOX污染物的生成和CO2的排放以及燃料的高效燃烧具有重要的意义，是解决节能与CO2减排主要发展的先进技术之一。本课题基于Linux操作系统的联想深腾1800并行计算平台，运用计算流体力学软件Fluent6.3软件，以欧拉-欧拉多相流模型、颗粒动力学理论和气固非均相化学反应动力...

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作者：牛悦 分类：高等教育资料 价格：15积分 属性：118 页 大小：3.97MB 格式：PDF 时间：2024-11-19

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