水蒸气对CO_2/H_2O气氛下煤焦结构的影响研究
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摘要
本文研究了水蒸气对富氧燃烧初始阶段煤焦结构的影响。在固定床上制取不同CO_2/H_2O气氛下煤焦,运用FT-IR/Raman对煤焦结构进行了表征。研究结果表明:水蒸气在富氧燃烧的初始阶段会增加煤焦的质量损失,但其影响程度有限,明显低于其单独存在下的影响;对于煤焦结构,水蒸气的加入会使富氧燃烧初始阶段煤焦芳香化程度明显增加,煤焦的结构更加有序;此外水蒸气的加入会使煤焦中含氧官能团先减少后增加。
This study investigated the effects of steam on the char structures in the initial stage of oxy-fuel combustion. Chars were prepared in the fixed bed reactor under different CO_2/H_2 O atmospheres, and characterized by FT-IR/Raman spectrometer. The results indicate that the existence of steam in the atmospheres increases the loss weight of the char in the initial stage of oxy-fuel combustion, but the influence extent is lower than that in the steam atmospheres individually.For the char structures, adding steam in CO_2 would increase the aromatization degree of the char significantly in the initial stage of oxy-fuel combustion. Besides the steam would first increase and then decrease the O-containing functional groups in the char under CO_2/H_2 O atmospheres.
This study investigated the effects of steam on the char structures in the initial stage of oxy-fuel combustion. Chars were prepared in the fixed bed reactor under different CO_2/H_2 O atmospheres, and characterized by FT-IR/Raman spectrometer. The results indicate that the existence of steam in the atmospheres increases the loss weight of the char in the initial stage of oxy-fuel combustion, but the influence extent is lower than that in the steam atmospheres individually.For the char structures, adding steam in CO_2 would increase the aromatization degree of the char significantly in the initial stage of oxy-fuel combustion. Besides the steam would first increase and then decrease the O-containing functional groups in the char under CO_2/H_2 O atmospheres.
引文
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[14]ZHANG Lei,LI Tinging,Quyun D M,et al.Structural Transformation of Nascent Char During the Fast Pyrolysis of Mallee Wood and Low-Rank Coals[J].Fuel Processing Technology,2015,138:390-396
[15]Gomez-Serrano V,Piriz-Almeida F,Duran-Valle C J,et al.Formation of Oxygen Structures by Air Activation.a Study by FT-IR Spectroscopy[J].Carbon,1999.37(10):1517-1528
[16]XU Jun,SU Sheng,SUN Zhijun,et al.Effects of Steam and CO_2 on the Characteristics of Chars During Devolatilization in Oxy-Steam Combustion Process[J].Applied Energy,2016,182:20-28
[17]XU Jun,SU Sheng,SUN Zhijun,et al.Effects of H_2O Gasification Reaction on the Characteristics of Chars Under Oxy-Fuel Combustion Conditions with Wet Recycle[J].Energy&Fuels,2016,30:9071-9079
[2]Scheffknecht G,Al-Makhadmeh L,Schnell U,et al.OxyFuel Coal Combustion-a Review of The Current State-of-the-Art[J].International Journal of Greenhouse Gas Control,2011,5:S16-S35
[3]Toftegaard M B,Brix J,Jensen P A,et al.Oxy-Fuel Combustion of Solid Fuels[J].Progress in Energy and Combustion Science,2010,36(5):581-625
[4]Dillon D J,Panesar R.S,Wall R A,et al.Oxy-Combustion Processes for CO_2 Capture from Advanced Supercritical PF and NGCC Power Plant[Z].Vancouver,Canada:2004
[5]YI Baojun,ZHANG Liiqi,HUANG Fang,et al.Effect of H_2O on The Combustion Characteristics of Pulverized Coal in O_2/CO_2 Atmosphere[J].Applied Energy,2014,132:349-357
[6]LIU Hao,SHAO Yingjuan.Predictions of The Impurities in the CO_2 Stream of an Oxy-Coal Combustion Plant[J].Applied Energy,2010,87(10):3162-3170
[7]LIU Xiaowei,XU Minghou,Si Junping,et al.Effect of Sodium on the Structure and Reactivity of the Chars Formed under N_2 and CO_2 Atmospheres[J].Energy&Fuels,2012,26(1):185-192
[8]SU Sheng,SONG Yao,WANG Yi,et al.Effects of CO_2and Heating Rate on the Characteristics of Chars Prepared in CO_2 and N_2 Atmospheres[J].Fuel,2015,142:243-249
[9]Borrego A G,Alvarez D.Comparison of Chars Obtained under Oxy-Fuel and Conventional Pulverized Coal Combustion Atmospheres[J].Energy&Fuels,2007,21(6):3171-3179
[10]Gil M V,Riaza J,Alvarez L,et al.Oxy-Fuel Combustion Kinetics and Morphology of Coal Chars Obtained in N_2and CO_2 Atmospheres in an Entrained Flow Reactor[J].Applied Energy,2012,91(1):67-74
[11]LI Xiaojing,LI Chunzhu.Volatilisation And Catalytic Effects of Alkali And Alkaline Earth Metallic Species During the Pyrolysis and Gasification of Victorian Brown Coal.PartⅧ.Catalysis and Changes in Char Structure During Gasification in Steam[J].Fuel,2006.85(10/11):1518-1525
[12]LI Tinging,ZHANG Lei,LI Dong,et al.Effects of Gasification Atmosphere and Temperature on Char Structural Evolution During the Gasification of Collie SubBituminous Coal[J].Fuel,2014,117:1190-1195
[13]Roberts D G,Harris D J.Char Gasification in Mixtures of CO_2 and H_2O:Competition and Inhibition[J].Fuel,2007,86(17-18):2672-2678
[14]ZHANG Lei,LI Tinging,Quyun D M,et al.Structural Transformation of Nascent Char During the Fast Pyrolysis of Mallee Wood and Low-Rank Coals[J].Fuel Processing Technology,2015,138:390-396
[15]Gomez-Serrano V,Piriz-Almeida F,Duran-Valle C J,et al.Formation of Oxygen Structures by Air Activation.a Study by FT-IR Spectroscopy[J].Carbon,1999.37(10):1517-1528
[16]XU Jun,SU Sheng,SUN Zhijun,et al.Effects of Steam and CO_2 on the Characteristics of Chars During Devolatilization in Oxy-Steam Combustion Process[J].Applied Energy,2016,182:20-28
[17]XU Jun,SU Sheng,SUN Zhijun,et al.Effects of H_2O Gasification Reaction on the Characteristics of Chars Under Oxy-Fuel Combustion Conditions with Wet Recycle[J].Energy&Fuels,2016,30:9071-9079