太阳能高温热解铁酸盐制合成气反应动力学研究
发布时间：2020-10-08 14:58
近年来,随着温室效应和环境污染问题的不断加剧,太阳能光化学技术、太阳能电化学技术以及太阳能高温热化学技术受到了越来越广泛的关注。目前,太阳能热化学燃料转换技术已成为最具吸引力的研究领域之一。该技术以CO_2为原料,将太阳能转化为燃料,以实现CO_2的减排和回收利用。基于上述背景,本文研究了以CO_2为原料制备氢气和合成气的太阳能热化学反应系统。研究内容包括:H_2O/CO_2裂解制备H_2/CO的机理和动力学分析;太阳能热化学反应器内传热传质过程的强化研究;铁基氧化物两步氧化还原反应的循环重整分析。该研究主要通过数值模拟和相关实验方法实现。H_2和CO是燃料电池的主要原料,也是合成其他燃料产品的重要原料(如太阳能烃燃料、甲醇和其他化学燃料),其品质的高低决定了燃料产品的最终质量。通过对H_2O/CO_2裂解和Fe_3O_4氧化还原循环过程的研究表明,压力、温度和H_2O/CO_2混合比例(?_g)等操作条件对合成气的生产速率和最终成分影响很大。当?_g(28)2时,在1600 K的操作温度和20 atm的压力下,容易获得高含氢量的合成气。本文利用反应路径图形象地描述了H_2/CO的裂解形成过程,旨在更加深入地解释模型内部的化学反应机理。研究发现,H_2/CO的产量主要取决于氧原子的交换能力和存在时间很短的氧化铁表面自由基物质(如H、O、C和OH)的活性。此外,气体到FeO再到Fe的反应过程中物质活性会受到氧化还原速率的限制。在这一过程中,氧原子从铁基氧化物的表面释放,并在气体裂解的过程中得到补充。由于氧向铁的转移过程受到限制,所以铁的存在状态主要以未被完全氧化的Fe_3O_4相态为主。此外,对具有较高表面温度的气固(Fe_3O_4和H_2O/CO_2)界面反应特性的研究结果表明,辐射传热和温度分布是影响太阳能热化学反应器中太阳能-化学能转换效率的重要因素。本文基于辐射传热模型(包括P1近似、有限体积离散纵坐标法(fvDOM)、面对面辐射模型(S2S)和Rosseland近似),对太阳能热化学反应器的热性能和强化传热传质强化策略进行了研究。实验和数值模拟结果均表明,入射辐射强度分布直接影响了整个反应器腔内的温度分布。可以观察到,进入反应器内的热通量越高,反应温度也会随之升高。此外,本文研究了影响太阳能反应器内换热和流动特性的相关因素,包括质量流量、换热系数、孔隙率、腔体内表面发射率、消光系数、石英玻璃物性和相关结构参数。研究结果表明,温度显著下降的主要原因是辐射、对流和热传递过程中存在着一定的热损失。本文研究对比了不同泡沫型RPC结构(包括SiC、CeO_2、FeAl_2O_4、NiFeAlO_3、Fe_3O_4/SiC和NiFe_2O_4/SiC)的辐射特性和换热特性,发现质量流速和泡沫结构参数(包括渗透率、平均孔隙直径和消光系数)会显著影响轴向温度分布、压降和流动换热特性。太阳能反应器内的集成多孔结构可以十分有效地将氧化还原粉末与反应介质结合,同时减小压降,提高热化学反应系统的热性能。当需要较强的热通量和较高的轴向温度分布时,建议使用SiC多孔介质材料。同时,为了提高太阳能热化学反应系统热性能,可以考虑将铁基氧化物或其它包含氧载体的活性催化剂涂覆在Al_2O_3多孔介质的表面。本文对Fe_3O_4氧化还原两步循环反应进行了相关实验研究和数值模拟。结果发现,CH_4-Fe_3O_4氧化还原反应制备H_2/CO的关键在于甲烷和氧化剂(H_2O和CO_2)的转化效率。NiFe_2O_4催化与CH_4部分氧化相结合的太阳能热化学反应体系表明,FeO-Fe、Fe/Ni在反应过程中所体现的协同效应有着十分广阔的应用前景。该反应通过两步实现,首先,在H_2与CO的浓度配比为2.54的条件下产生45%的合成气,然后在437.69 kW/m~2的太阳辐照条件下以2.34的浓度配比产生另外55%的合成气。研究结果表明,氧化反应温度、操作压力和氧化物浓度也能够对氧化反应过程产生明显的影响。依托于二氧化碳捕集与封存技术(CCST)的不断发展,当前研究的重点应致力于开发先进的二氧化碳利用技术(CU),以实现二氧化碳的减排和利用。通过二氧化碳捕获和利用(CCU)技术,本文对CO_2裂解制备合成气(H_2/CO)的热化学反应过程进行了分析。研究发现,在741.31 kW/m~2的太阳辐照条件下,反应器可以利用60%的CO_2与40%CH_4的原料制备合成气(成分为72.9%H_2和27.1%CO)。此外,调节混合气体入口速度、操作压力和CO_2/CH_4浓度配比等条件也能够有效提高二氧化碳的转换效率。将CH_4/CO_2裂解重整为化学燃料,在CO_2回收利用技术邻域中极具发展前景。采用具有NiFeAlO_3网状多孔陶瓷结构(RPC)的氧化还原材料,能够有效地提高CO_2的转化效率。本文介绍了采用NiFeAlO_3 RPC结构的基础实验系统及其反应机理,研究了添加Fe-Ni双金属的氧化铝催化剂对CH_4协同催化CO_2反应过程的影响。通过减少碳沉积和促进CH_4的氧化程度,NiFeAlO_3催化剂孔隙中的晶格氧浓度有所提高,从而显著提高了合成气的生产速率。同时,NiFeAlO_3添加量、Ni/Fe配比和CO_2/CH_4浓度比是影响合成气产量的关键因素。在Ni/Fe配比为0.72,CO_2浓度为60%的条件下,能够获得更高的合成气产量,同时显著降低碳沉积量。将逆变换反应(RWGS)和Boudouard反应纳入考虑范围,CO的产生速率将进一步提高。此外,作为一种成本更低的氧化物替代材料,可以考虑将Ni-Fe-铝酸盐RPC用于CO_2的回收转化,使之变为液态烃燃料或高品质化学产品。研究结果对利用聚光太阳能的热量来驱动热化学循环的太阳能热化学燃料转换技术有十分重要的理论意义和实际应用价值。
【学位单位】：哈尔滨工业大学
【学位级别】：博士
【学位年份】：2018
【中图分类】：TE665.3
【文章目录】：
摘要
Abstract
Nomenclature
Chapter 1 Introduction
1.1 Objectives of the research
1.2 Introduction to syngas production technology
1.2.1 Overview of research on syngas and its utilization
1.2.2 Study on promising candidate materials
1.2.3 Effects of physical parameters on the solar thermochemical reactionsystem
2 and CO gases'> 1.2.4 Production mechanism of H2 and CO gases
1.2.5 Solar thermochemical advanced reactor system and the receiver thermalperformance
1.3 Thesis content
1.3.1 Research on operating conditions of synthetic gas production via two-stepsolar thermochemical process
1.3.2 Solar thermochemical reactor design and thermal performance analysis
1.3.3 Thermochemical reaction performance analysis and research on advancedredox oxide materials
1.4 Methodology
1.5 Thesis organization
Chapter 2 Experimental Setup and Computational Modeling of SolarThermochemical Reacting System
2.1 Introduction
2.2 Schematic diagram of novel solar thermochemical reactor
2.3 Benchmark experimental setup of a laboratory-scale solar thermochemicalreacting system
2.4 Governing equations describing solar thermochemical reacting system for syngasproduction
2.4.1 Governing equations
2.4.2 Boundary conditions
2.4.3 Numerical solution methods
2 and CO production mechanisms and kinetics'> 2.5 Governing equations describing H2 and CO production mechanisms and kinetics
2.5.1 Governing equations
2.5.2 Boundary conditions
2.5.3 Numerical solution methods
2.6 Governing equations describing the thermal performance of porous mediumsolar thermochemical reactor
2.6.1 Governing equation
2.6.2 Boundary conditions
2.6.3 Numerical solution methods
2.7 Summary
2 and CO production bySimultaneous Splitting of H2O and CO2'>Chapter 3 Mechanism and Kinetic Analysis of H2 and CO production bySimultaneous Splitting of H2O and CO2
3.1 Introduction
2 and CO based on Fe3O4'> 3.2 Production mechanism and kinetic analysis of H2 and CO based on Fe3O4
3.2.1 Mechanism of H2 production
3.2.2 Mechanism of CO production
3.2.3 Syngas produced by the mechanism of iron oxide redox cycle
3.3 Analysis of high surface temperature gas-solid interfacial reaction characteristics
3.3.1 High-flux irradiation temperature distribution and chemical changes inthe high-flux thermal energy
2 and CO）production'> 3.3.2 Effects of surface temperature on syngas（H2 and CO）production
2O and CO2-splitting via Fe3O4 redox'> 3.4 Pressured syngas production by H2O and CO2-splitting via Fe3O4 redox
3O4）'> 3.4.1 Thermal reduction of iron oxide（Fe3O4）
2O and CO2'> 3.4.2 Reduced iron oxide oxidation with H2O and CO2
3.4.3 Parameters study
2 utilization into synthesis gas'> 3.5 Analysis of CO2 utilization into synthesis gas
2 and CO）yield'> 3.5.1 High flux thermal temperature distribution and（H2 and CO）yield
3.5.2 Thermal behavior of the reactor with direct heat transfer between gaseousreactant and products evolution
3.5.3 Effect of mixture gas inlet velocity on syngas production
2 utilization into syngasbased on CH4-reforming'> 3.5.4 Operating pressure effect on the process of CO2 utilization into syngasbased on CH4-reforming
2 and CH4 concentration on the process performance forCO2 utilization and syngas production'> 3.5.5 Effects of CO2 and CH4 concentration on the process performance forCO2 utilization and syngas production
2O3 on syngas production'> 3.5.6 Effect of catalyst Ni/Al2O3 on syngas production
3.6 Summary
Chapter 4 Heat and Mass Transfer Enhancement of Solar Thermochemical Reactor
4.1 Introduction
4.2 Thermal performance analysis of solar thermochemical reactor
4.2.1 Incident radiation intensity and radiation temperature distribution
4.2.2 Analysis of temperature distribution inside the reactor
4.2.3 Effects of operating pressure and carrier gas flow inlet velocity on thetemperature distribution
4.3 Analysis of the effects of radiation properties on the thermal performance
4.3.1 Temperature distribution with different radiation heat transfer models.
4.3.2 Incident radiation flux and irradiance distribution along the reactor
4.3.3 Effects of radiation properties and inlet velocity of carrier gas flow on thethermal performance of the reactor
4.4 Heat transfer and fluid flow analysis of porous-medium filled solarthermochemical reactor
4.4.1 Experimental setup and model validation
4.4.2 Reactor temperature distribution and radiation in participating media
4.4.3 Effect of heat transfer coefficient on the surface of the cooling system ofthe reactor
4.4.4 Effect of mass flow rate on heat transfer and fluid flow performance
4.4.5 Effect of quartz glass and inner cavity wall surface emissivity on thereactor thermal performance
4.4.6 Effects of porosity and extinction coefficient on the reactor thermalperformance
4.5 Radiative heat transfer and thermal characteristics of Fe-based oxides coated SiCand Alumina RPC structures
4.5.1 Thermal characteristics of porous media solar receiver as a function ofintegrated porous structures
4.5.2 Coupled radiative and heat transfer in participating media
4.5.3 Effects of mass flow rate and permeability on the pressure drop and fluidflow performance
4.5.4 Effect of pore mean cell size and extinction coefficients on heat transferand fluid flow
4.6 Summary
Chapter 5 Analysis of Two-step Solar Thermochemical Looping Reforming ofFe-based Oxide Redox Cycles
5.1 Introduction
3O4 redox cycles'> 5.2 Two-step solar thermochemical looping reforming of Fe3O4 redox cycles
5.2.1 Experiment and reaction mechanism
4-Fe3O4'> 5.2.2 Thermal reduction of CH4-Fe3O4
5.2.3 Effects of operating conditions on the thermal reduction
2 O and CO2-splitting'> 5.2.4 Oxidation of oxygen carriers via H2O and CO2-splitting
5.2.5 Effects of oxidation temperature and operating pressures
2O/CO2 and mixture gas flow rate on H2 and CO production'> 5.2.6 Effects of the concentration of H2O/CO2 and mixture gas flow rate on H2 and CO production
2 and CO production of the solar thermochemical reacting systemof NiFe2O4 redox cycles combined with CH4 partial oxidation'> 5.3 Analysis of H2 and CO production of the solar thermochemical reacting systemof NiFe2O4 redox cycles combined with CH4 partial oxidation
2O4 in CH4 atmosphere'> 5.3.1 Thermal reduction analysis of NiFe2O4 in CH4 atmosphere
4 concentration on the thermal reduction reaction'> 5.3.2 Effect of CH4 concentration on the thermal reduction reaction
2O and CO2-splitting'> 5.3.3 Reduced species oxidation via H2O and CO2-splitting
2and CO production'> 5.3.4 Effect of oxidation temperature and oxidizing gas concentration on H2and CO production
2 utilization'> 5.4 Alumina supported Fe-Ni bimetallic catalysts based material for CO2 utilization
3 RPC based redox oxide material'> 5.4.1 NiFeAlO3 RPC based redox oxide material
5.4.2 Reaction mechanism
4 decomposition during Ni/Fe/Al2O3 catalysts thermal heating'> 5.4.3 CH4 decomposition during Ni/Fe/Al2O3 catalysts thermal heating
2 utilization'> 5.4.4 Isothermal CO2 utilization
2/CH4,and RWGS on CO2 utilization'> 5.4.5 Effects of Ni/Fe,CO2/CH4,and RWGS on CO2 utilization
5.5 Summary
Conclusion& Remark
Conclusion
Novelty and Contribution
Future work
References
List of Publications
Acknowledgements
Resume
本文编号：2832372
【学位单位】：哈尔滨工业大学
【学位级别】：博士
【学位年份】：2018
【中图分类】：TE665.3
【文章目录】：
摘要
Abstract
Nomenclature
Chapter 1 Introduction
1.1 Objectives of the research
1.2 Introduction to syngas production technology
1.2.1 Overview of research on syngas and its utilization
1.2.2 Study on promising candidate materials
1.2.3 Effects of physical parameters on the solar thermochemical reactionsystem
2 and CO gases'> 1.2.4 Production mechanism of H2 and CO gases
1.2.5 Solar thermochemical advanced reactor system and the receiver thermalperformance
1.3 Thesis content
1.3.1 Research on operating conditions of synthetic gas production via two-stepsolar thermochemical process
1.3.2 Solar thermochemical reactor design and thermal performance analysis
1.3.3 Thermochemical reaction performance analysis and research on advancedredox oxide materials
1.4 Methodology
1.5 Thesis organization
Chapter 2 Experimental Setup and Computational Modeling of SolarThermochemical Reacting System
2.1 Introduction
2.2 Schematic diagram of novel solar thermochemical reactor
2.3 Benchmark experimental setup of a laboratory-scale solar thermochemicalreacting system
2.4 Governing equations describing solar thermochemical reacting system for syngasproduction
2.4.1 Governing equations
2.4.2 Boundary conditions
2.4.3 Numerical solution methods
2 and CO production mechanisms and kinetics'> 2.5 Governing equations describing H2 and CO production mechanisms and kinetics
2.5.1 Governing equations
2.5.2 Boundary conditions
2.5.3 Numerical solution methods
2.6 Governing equations describing the thermal performance of porous mediumsolar thermochemical reactor
2.6.1 Governing equation
2.6.2 Boundary conditions
2.6.3 Numerical solution methods
2.7 Summary
2 and CO production bySimultaneous Splitting of H2O and CO2'>Chapter 3 Mechanism and Kinetic Analysis of H2 and CO production bySimultaneous Splitting of H2O and CO2
2
3.2.2 Mechanism of CO production
3.2.3 Syngas produced by the mechanism of iron oxide redox cycle
3.3 Analysis of high surface temperature gas-solid interfacial reaction characteristics
3.3.1 High-flux irradiation temperature distribution and chemical changes inthe high-flux thermal energy
2
2O and CO2-splitting via Fe3O4 redox'> 3.4 Pressured syngas production by H2O and CO2-splitting via Fe3O4 redox
3O4）'> 3.4.1 Thermal reduction of iron oxide（Fe3O4）
2O and CO2'> 3.4.2 Reduced iron oxide oxidation with H2O and CO2
2
2 and CO）yield'> 3.5.1 High flux thermal temperature distribution and（H2 and CO）yield
3.5.2 Thermal behavior of the reactor with direct heat transfer between gaseousreactant and products evolution
3.5.3 Effect of mixture gas inlet velocity on syngas production
2 utilization into syngasbased on CH4-reforming'> 3.5.4 Operating pressure effect on the process of CO2 utilization into syngasbased on CH4-reforming
2 and CH4 concentration on the process performance forCO2 utilization and syngas production'> 3.5.5 Effects of CO2 and CH4 concentration on the process performance forCO2 utilization and syngas production
2O3 on syngas production'> 3.5.6 Effect of catalyst Ni/Al2O3 on syngas production
3.6 Summary
Chapter 4 Heat and Mass Transfer Enhancement of Solar Thermochemical Reactor
4.1 Introduction
4.2 Thermal performance analysis of solar thermochemical reactor
4.2.1 Incident radiation intensity and radiation temperature distribution
4.2.2 Analysis of temperature distribution inside the reactor
4.2.3 Effects of operating pressure and carrier gas flow inlet velocity on thetemperature distribution
4.3 Analysis of the effects of radiation properties on the thermal performance
4.3.1 Temperature distribution with different radiation heat transfer models.
4.3.2 Incident radiation flux and irradiance distribution along the reactor
4.3.3 Effects of radiation properties and inlet velocity of carrier gas flow on thethermal performance of the reactor
4.4 Heat transfer and fluid flow analysis of porous-medium filled solarthermochemical reactor
4.4.1 Experimental setup and model validation
4.4.2 Reactor temperature distribution and radiation in participating media
4.4.3 Effect of heat transfer coefficient on the surface of the cooling system ofthe reactor
4.4.4 Effect of mass flow rate on heat transfer and fluid flow performance
4.4.5 Effect of quartz glass and inner cavity wall surface emissivity on thereactor thermal performance
4.4.6 Effects of porosity and extinction coefficient on the reactor thermalperformance
4.5 Radiative heat transfer and thermal characteristics of Fe-based oxides coated SiCand Alumina RPC structures
4.5.1 Thermal characteristics of porous media solar receiver as a function ofintegrated porous structures
4.5.2 Coupled radiative and heat transfer in participating media
4.5.3 Effects of mass flow rate and permeability on the pressure drop and fluidflow performance
4.5.4 Effect of pore mean cell size and extinction coefficients on heat transferand fluid flow
4.6 Summary
Chapter 5 Analysis of Two-step Solar Thermochemical Looping Reforming ofFe-based Oxide Redox Cycles
5.1 Introduction
3O4 redox cycles'> 5.2 Two-step solar thermochemical looping reforming of Fe3O4 redox cycles
5.2.1 Experiment and reaction mechanism
4-Fe3O4'> 5.2.2 Thermal reduction of CH4-Fe3O4
2
5.2.5 Effects of oxidation temperature and operating pressures
2O/CO2 and mixture gas flow rate on H2 and CO production'> 5.2.6 Effects of the concentration of H2O/CO2 and mixture gas flow rate on H2 and CO production
2 and CO production of the solar thermochemical reacting systemof NiFe2O4 redox cycles combined with CH4 partial oxidation'> 5.3 Analysis of H2 and CO production of the solar thermochemical reacting systemof NiFe2O4 redox cycles combined with CH4 partial oxidation
2O4 in CH4 atmosphere'> 5.3.1 Thermal reduction analysis of NiFe2O4 in CH4 atmosphere
4 concentration on the thermal reduction reaction'> 5.3.2 Effect of CH4 concentration on the thermal reduction reaction
2O and CO2-splitting'> 5.3.3 Reduced species oxidation via H2O and CO2-splitting
2and CO production'> 5.3.4 Effect of oxidation temperature and oxidizing gas concentration on H2and CO production
2 utilization'> 5.4 Alumina supported Fe-Ni bimetallic catalysts based material for CO2 utilization
3 RPC based redox oxide material'> 5.4.1 NiFeAlO3 RPC based redox oxide material
5.4.2 Reaction mechanism
4 decomposition during Ni/Fe/Al2O3 catalysts thermal heating'> 5.4.3 CH4 decomposition during Ni/Fe/Al2O3 catalysts thermal heating
2 utilization'> 5.4.4 Isothermal CO2 utilization
2/CH4,and RWGS on CO2 utilization'> 5.4.5 Effects of Ni/Fe,CO2/CH4,and RWGS on CO2 utilization
5.5 Summary
Conclusion& Remark
Conclusion
Novelty and Contribution
Future work
References
List of Publications
Acknowledgements
Resume
本文编号：2832372
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