太陽能高溫熱解鐵酸鹽制合成氣反應動力學研究
發(fā)布時間：2020-10-08 14:58
近年來,隨著溫室效應和環(huán)境污染問題的不斷加劇,太陽能光化學技術、太陽能電化學技術以及太陽能高溫熱化學技術受到了越來越廣泛的關注。目前,太陽能熱化學燃料轉換技術已成為最具吸引力的研究領域之一。該技術以CO_2為原料,將太陽能轉化為燃料,以實現(xiàn)CO_2的減排和回收利用�；谏鲜霰尘�,本文研究了以CO_2為原料制備氫氣和合成氣的太陽能熱化學反應系統(tǒng)。研究內容包括:H_2O/CO_2裂解制備H_2/CO的機理和動力學分析;太陽能熱化學反應器內傳熱傳質過程的強化研究;鐵基氧化物兩步氧化還原反應的循環(huán)重整分析。該研究主要通過數(shù)值模擬和相關實驗方法實現(xiàn)。H_2和CO是燃料電池的主要原料,也是合成其他燃料產(chǎn)品的重要原料(如太陽能烴燃料、甲醇和其他化學燃料),其品質的高低決定了燃料產(chǎn)品的最終質量。通過對H_2O/CO_2裂解和Fe_3O_4氧化還原循環(huán)過程的研究表明,壓力、溫度和H_2O/CO_2混合比例(?_g)等操作條件對合成氣的生產(chǎn)速率和最終成分影響很大。當?_g(28)2時,在1600 K的操作溫度和20 atm的壓力下,容易獲得高含氫量的合成氣。本文利用反應路徑圖形象地描述了H_2/CO的裂解形成過程,旨在更加深入地解釋模型內部的化學反應機理。研究發(fā)現(xiàn),H_2/CO的產(chǎn)量主要取決于氧原子的交換能力和存在時間很短的氧化鐵表面自由基物質(如H、O、C和OH)的活性。此外,氣體到FeO再到Fe的反應過程中物質活性會受到氧化還原速率的限制。在這一過程中,氧原子從鐵基氧化物的表面釋放,并在氣體裂解的過程中得到補充。由于氧向鐵的轉移過程受到限制,所以鐵的存在狀態(tài)主要以未被完全氧化的Fe_3O_4相態(tài)為主。此外,對具有較高表面溫度的氣固(Fe_3O_4和H_2O/CO_2)界面反應特性的研究結果表明,輻射傳熱和溫度分布是影響太陽能熱化學反應器中太陽能-化學能轉換效率的重要因素。本文基于輻射傳熱模型(包括P1近似、有限體積離散縱坐標法(fvDOM)、面對面輻射模型(S2S)和Rosseland近似),對太陽能熱化學反應器的熱性能和強化傳熱傳質強化策略進行了研究。實驗和數(shù)值模擬結果均表明,入射輻射強度分布直接影響了整個反應器腔內的溫度分布�？梢杂^察到,進入反應器內的熱通量越高,反應溫度也會隨之升高。此外,本文研究了影響太陽能反應器內換熱和流動特性的相關因素,包括質量流量、換熱系數(shù)、孔隙率、腔體內表面發(fā)射率、消光系數(shù)、石英玻璃物性和相關結構參數(shù)。研究結果表明,溫度顯著下降的主要原因是輻射、對流和熱傳遞過程中存在著一定的熱損失。本文研究對比了不同泡沫型RPC結構(包括SiC、CeO_2、FeAl_2O_4、NiFeAlO_3、Fe_3O_4/SiC和NiFe_2O_4/SiC)的輻射特性和換熱特性,發(fā)現(xiàn)質量流速和泡沫結構參數(shù)(包括滲透率、平均孔隙直徑和消光系數(shù))會顯著影響軸向溫度分布、壓降和流動換熱特性。太陽能反應器內的集成多孔結構可以十分有效地將氧化還原粉末與反應介質結合,同時減小壓降,提高熱化學反應系統(tǒng)的熱性能。當需要較強的熱通量和較高的軸向溫度分布時,建議使用SiC多孔介質材料。同時,為了提高太陽能熱化學反應系統(tǒng)熱性能,可以考慮將鐵基氧化物或其它包含氧載體的活性催化劑涂覆在Al_2O_3多孔介質的表面。本文對Fe_3O_4氧化還原兩步循環(huán)反應進行了相關實驗研究和數(shù)值模擬。結果發(fā)現(xiàn),CH_4-Fe_3O_4氧化還原反應制備H_2/CO的關鍵在于甲烷和氧化劑(H_2O和CO_2)的轉化效率。NiFe_2O_4催化與CH_4部分氧化相結合的太陽能熱化學反應體系表明,FeO-Fe、Fe/Ni在反應過程中所體現(xiàn)的協(xié)同效應有著十分廣闊的應用前景。該反應通過兩步實現(xiàn),首先,在H_2與CO的濃度配比為2.54的條件下產(chǎn)生45%的合成氣,然后在437.69 kW/m~2的太陽輻照條件下以2.34的濃度配比產(chǎn)生另外55%的合成氣。研究結果表明,氧化反應溫度、操作壓力和氧化物濃度也能夠對氧化反應過程產(chǎn)生明顯的影響。依托于二氧化碳捕集與封存技術(CCST)的不斷發(fā)展,當前研究的重點應致力于開發(fā)先進的二氧化碳利用技術(CU),以實現(xiàn)二氧化碳的減排和利用。通過二氧化碳捕獲和利用(CCU)技術,本文對CO_2裂解制備合成氣(H_2/CO)的熱化學反應過程進行了分析。研究發(fā)現(xiàn),在741.31 kW/m~2的太陽輻照條件下,反應器可以利用60%的CO_2與40%CH_4的原料制備合成氣(成分為72.9%H_2和27.1%CO)。此外,調節(jié)混合氣體入口速度、操作壓力和CO_2/CH_4濃度配比等條件也能夠有效提高二氧化碳的轉換效率。將CH_4/CO_2裂解重整為化學燃料,在CO_2回收利用技術鄰域中極具發(fā)展前景。采用具有NiFeAlO_3網(wǎng)狀多孔陶瓷結構(RPC)的氧化還原材料,能夠有效地提高CO_2的轉化效率。本文介紹了采用NiFeAlO_3 RPC結構的基礎實驗系統(tǒng)及其反應機理,研究了添加Fe-Ni雙金屬的氧化鋁催化劑對CH_4協(xié)同催化CO_2反應過程的影響。通過減少碳沉積和促進CH_4的氧化程度,NiFeAlO_3催化劑孔隙中的晶格氧濃度有所提高,從而顯著提高了合成氣的生產(chǎn)速率。同時,NiFeAlO_3添加量、Ni/Fe配比和CO_2/CH_4濃度比是影響合成氣產(chǎn)量的關鍵因素。在Ni/Fe配比為0.72,CO_2濃度為60%的條件下,能夠獲得更高的合成氣產(chǎn)量,同時顯著降低碳沉積量。將逆變換反應(RWGS)和Boudouard反應納入考慮范圍,CO的產(chǎn)生速率將進一步提高。此外,作為一種成本更低的氧化物替代材料,可以考慮將Ni-Fe-鋁酸鹽RPC用于CO_2的回收轉化,使之變?yōu)橐簯B(tài)烴燃料或高品質化學產(chǎn)品。研究結果對利用聚光太陽能的熱量來驅動熱化學循環(huán)的太陽能熱化學燃料轉換技術有十分重要的理論意義和實際應用價值。
【學位單位】：哈爾濱工業(yè)大學
【學位級別】：博士
【學位年份】：2018
【中圖分類】：TE665.3
【文章目錄】：
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
本文編號：2832372
【學位單位】：哈爾濱工業(yè)大學
【學位級別】：博士
【學位年份】：2018
【中圖分類】：TE665.3
【文章目錄】：
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
本文編號：2832372
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