【作者】 王强；

【导师】 蒲舸；

【作者基本信息】 重庆大学 ， 动力工程及工程热物理， 2014， 硕士

【摘要】 化学链燃烧是一种新颖的CO2捕集与收集技术，与传统燃烧技术相比，不但效率高，而且能耗低。化学链燃烧系统包括空气反应器和燃料反应器，载氧体在空气反应器与燃料反应器之间循环传递氧，燃料反应器中的燃烧产物经冷凝处理后得到高浓度的CO2，而化学链氧解耦燃烧是适用于固体燃料的化学链燃烧。要实现化学链燃烧性能良好的载氧体是关键，由于锰基载氧体熔点较高且价格较便宜，因此本文选择锰基载氧体进行实验研究。本文首先在热重分析仪上考察Mn2O3在不同条件下的释氧特性，然后考察其释氧后产物Mn3O4的吸氧特性、循环稳定性及炉渣和飞灰对其循环稳定性的影响，并得到了锰基载氧体的动力学参数。在此基础上考察了惰性载体对锰基载氧体特性的影响，还考察了浸渍法和石墨成孔法对载氧体的影响，之后选取性能较好的Mn75Al25与Mn2O3和煤在固定床上进行化学链氧解耦燃烧循环稳定性测试，并借助XRD和SEM对相关载氧体进行物相分析和微观形貌分析。最后以硝酸盐浸渍方式制备锰铜复合载氧体，以同样的方法对其载氧体释氧特性及循环稳定性展开实验研究。研究结果表明，Mn2O3随着氧气浓度的增加，初始释氧温度逐渐增加，活化能大幅度增加；随反应温度的升高，其释氧时间减少；随升温速率的提高，释氧活化能小幅度增加。Mn3O4随着反应温度的升高，氧化时间增加；随氧气浓度的降低，吸氧所需的势差越来越小，Mn3O4不易氧化；Mn3O4在20次吸氧释氧过程中表现出较好的稳定性。炉渣对载氧体的循环稳定性具有一定的影响；而飞灰对Mn3O4的循环稳定性没有什么影响。惰性载体改性锰基载氧体的研究结果表明，在相同反应温度下，Al2O3处理的Mn75Al25释氧时间比Mn2O3少；TiO2对锰基载氧体的热力学氧平衡分压改变最为突出；Mn75Al25的循环稳定性最好，Mn75Zr25不适合作为化学链氧解耦燃烧的载氧体。浸渍法制备的Mn75Al25载氧体略微优于石墨成孔法制备的Mn75(Al9C1)25载氧体；Mn75Al25和Mn2O3不宜作为煤化学链氧解耦燃烧的载氧体。锰铜复合载氧体的实验研究表明，在相同的反应温度下，(Mn75Cu25)3Al1的释氧时间比Mn75Cu25少；两种载氧体在无氧时的释氧量比有氧气氛下多；当反应温度一定时，粒径大小对载氧体的释氧特性没有什么影响；Mn75Cu25和(Mn75Cu25)3Al1的循环稳定性均较好，但(Mn75Cu25)3Al1的释氧量随着循环次数的增加相对较稳定；与煤化学链燃烧循环过程中，随着循环次数的增加，Mn75Cu25颗粒逐渐增大，而(Mn75Cu25)3Al1颗粒粒径变化较小；与煤化学链燃烧之后的循环稳定性测试表明，随着循环次数的增加，(Mn75Cu25)3Al1每次的释氧量波动较小，优于Mn75Cu25载氧体。更多还原

【Abstract】 Chemical-looping combustion (CLC) is a novel CO2caputure and collectiointechniques. It’s not only high efficiency, but also low energy consumption, comparedwith traditional. CLC system includes air reactor and fuel reactor. Oxygen carrierscirculate between the two reactors to transfer oxygen. High concentration of CO2isobtained in the fuel reactor after combustion products are condensated. And chemicallooping with oxygen uncoupling (CLOU) is suitable for solid fuels. The most critical ofCLC is the need for a good performance oxygen carrier. Mn-based oxygen carriers werestudied because of it’s relatively high melting point and low price.Oxygen release characteristics of Mn2O3under different conditions wereinvestigated in the thermogravimetric analysis (TGA) firstly. Then the oxygenabsorption characteristics of Mn3O4, which is the product of Mn2O3after oxygen release,were investigated. It’s cycle stability and the effect on that by slag and fly ash wastested. Kinetic parameters of Mn-based oxygen carriers were obtained, too. Based onthe study, the effect of inert carriers on Mn-based oxygen carriers was examined, andthe effect of impregnation method and pore-forming using graphite on the oxygencarriers was also tested. Then better performance Mn75Al25and Mn2O3were selectedto test the cycle stability of CLOU with coal on fixed bed. XRD and SEM were appliedto study the phase analysis and microstructure analysis of oxygen carriers. Finally, theoxygen release characteristics and the cycle stability of composite oxygen carriersprepared by nitrate impregnation were also investigated using the same way.According to the experimental results, it’s found that the initial oxygen releasetemperature of Mn2O3is gradually increased and the activation energy is increasedsignificantly with the increasing of oxygen concentration. The time of oxygen release isdecreased with reaction temperature increasing. When the hating rate in improved, theactivation energy has a slight increase. The time of Mn3O4oxidation is improved withthe reaction temperature increasing. With decreasing of oxygen concentration, potentialdifference of oxidation required is smaller, and Mn3O4is easily oxidized. Mn3O4exhibits good stability in20circulation. Slag has some influence on it’s cycle stability,while fly ash has no effect on that.Investigation of modified Mn-based oxygen carriers by inert carriers shows that thetime of oxygen release of Mn75Al25is less than Mn2O3at the same reaction temperature. TiO2has most prominent change on equilibrium partial pressure ofMn-based oxygen carriers. Mn75Al25has the best cycle stability, and Mn75Zr25is notsuitable as oxygen carriers for CLOU. Mn75Al25prepared by impreganation has bettercharacteristic than Mn75(Al9C1)25prepared by pore-forming using graphite. Mn75Aland Mn2O3are not suitable as oxygen carriers for CLOU with coal.Experimental study of Mn-Cu composite oxygen carriers shows that oxygenrelease time of (Mn75Cu25)3Al1is less than Mn75Cu25at the same reactiontemperature. Oxygen release of them under anaerobic is more than aerobic conditions,while the particle size has no effect on oxygen release characteristics at the sametemperature. Both of them have good cycle stability. But oxygen release of(Mn75Cu25)3Al1is relatively stable with the number of cycles increasing. During theCLOU with coal, particle size of Mn75Cu25increses gradually with the number ofcycles increasing, but (Mn75Cu25)3Al1has only small changes. Cycle stability test ofoxygen carriers after CLOU with coal shows that every oxygen release of(Mn75Cu25)3Al1undulates smaller than Mn75Cu25with the number of cyclesincreasing.更多还原