草木灰水溶液改性的天然贫铁矿载氧体的反应性能

doi:10.16085/j.issn.1000-6613.2017-0293

摘要/Abstract

摘要： 化学链燃烧是一种基于CO₂零排放理念的无焰燃烧技术，能够提高CO₂捕集效率。本文选用一种天然贫铁矿作为载氧体，在热重分析仪上采用CO作为还原气考察了其反应特性。为了减轻载氧体表面的烧结情况，本文提出了采用草木灰水溶液对天然贫铁矿载氧体进行改性，并对改性后载氧体进行短时间、多次数氧化还原循环实验研究；考察了反应器温度对改性前后的载氧体反应特性影响。实验结果表明：天然贫铁矿在15次氧化还原循环反应中展现了一定的循环稳定性，但载氧体的还原程度和反应速率较低；改性后的载氧体还原程度更深、反应速率更快，且保持了良好的反应活性。载氧体在100次的氧化还原循环中出现粉化团聚现象，导致轻微的质量损失。XRD和SEM的分析结果表明生物质灰中的K元素在反应中与铁矿石中的物质生成了新的化合物，增大了载氧体的比表面积，提高了载氧体的还原反应活性。载氧体表面没有出现明显的烧结团聚现象。

关键词: 二氧化碳捕集, 天然贫铁矿, 载氧体, 水溶液, 活化

Abstract: Chemical looping combustion is a new combustion mode with zero CO₂ emission,which can improve the efficiency of the CO₂ capture. A lean iron ore was employed as the oxygen carrier in this study. The CO was selected as the reducing gas. The plant-ash aqueous water was used to modify the lean iron ore. A series of chemical-looping combustion(CLC)tests were conducted in a thermogravimetric analysis reactor. The CO aeration time was reduced to 60 seconds. Consecutive reduction-oxidation cycles were first carried out in the TGA at various temperatures. The results indicated that the reduction reactivity of lean iron ore remained stable in 15 cycles. The cyclic stability of the modified oxygen carrier remained well in 100 cycles. The reduction condition and the chemical reaction rate of the modified oxygen carrier were better than those of the lean iron ore. The analysis of the XRD and SEM experiments showed the alkali mental K abundant in the plant ash combined with the contents of the lean iron ore through complicated reactions,which resulted in the expansion of the specific surface area of the modified oxygen carrier. The reduction reactivity of the modified oxygen carrier was enhanced without serious sintering on the surface.

Key words: CO₂ capture, lean iron ore, oxygen carrier, aqueous water, activation

中图分类号:

TK546

胡晓雨, 金保昇, 王晓佳, 王旭东, 朱小明. 草木灰水溶液改性的天然贫铁矿载氧体的反应性能[J]. 化工进展, 2017, 36(11): 4022-4029.

HU Xiaoyu, JIN Baosheng, WANG Xiaojia, WANG Xudong, ZHU Xiaoming. Experimental study on plant-ash-water modified lean iron ore oxygen carrier in chemical looping combustion[J]. Chemical Industry and Engineering Progress, 2017, 36(11): 4022-4029.

参考文献

[1] MENDIARA T,PEREZ R,ABAD A,et al. Low-cost Fe-based图8循环前后改性载氧体颗粒不同放大倍数的SEM图oxygen carrier materials for the iG-CLC process with coal[J]. Industrial & Engineering Chemistry Research,2012,51(50):16216-16229.
[2] MENDIARA T,DIEGO L F D,GARCIA-LABIANO F,et al. On the use of a highly reactive iron ore in chemical looping combustion of different coals[J]. Fuel,2014,126(12):239-249..
[3] SONG T,SHEN T,SHEN L,et al. Evaluation of hematite oxygen carrier in chemical-looping combustion of coal[J]. Fuel,2013,104(2):244-252
[4] SONG T,WU J,ZHANG H,et al. Characterization of an Australia hematite oxygen carrier in chemical looping combustion with coal[J]. International Journal of Greenhouse Gas Control,2012,11(6):326-336.
[5] 顾海明,沈来宏,吴家桦,等. 基于赤铁矿载氧体的煤化学链燃烧试验[J]. 化工学报,2011,62(1):180-185. GU H M,SHEN L H,WU J H,et al. Experiments on chemical looping combustion of coal with hematite as oxygen carrier[J]. CIESC Journal,2011,62(1):180-185.
[6] 顾海明,沈来宏,吴家桦,等.基于赤铁矿载氧体的串行流化床煤化学链燃烧试验[J]. 中国电机工程学报,2010(17):51-56. GU H M,SHEN L H,WU J H,et al. Experiments on chemical looping combustion of coal in interconnected fluidized bed using hematite as oxygen carrier[J]. Proceedings o f the CSEE,2010(17):51-56.
[7] XIAO R,SONG Q,SONG M,et al. Pressurized chemical-looping combustion of coal with an iron ore-based oxygen carrier[J]. Combustion and Flame,2010,157(6):1140-1153.
[8] XIAO R,SONG Q,ZHANG S,et al. Pressurized chemical-looping combustion of Chinese bituminous coal:cyclic performance and characterization of iron ore-based oxygen carrier[J]. Energy & Fuels,2010,24(2):1449-1463.
[9] XIAO R,CHEN L,SAHA C,et al. Pressurized chemical-looping combustion of coal using an iron ore as oxygen carrier in a pilot-scale unit[J]. International Journal of Greenhouse Gas Control,2012,10(5):363-373.
[10] 顾海明,沈来宏,肖军,等. 基于钾基修饰铁矿石载氧体的煤化学链燃烧循环实验[J]. 燃料化学学报,2012,40(8):927-934. GU H M,SHEN L H,XIAO J,et al. Cycle experiments on chemical looping combustion of coal using potassium-improved iron ore as oxygen carrier[J]. Journal of Fuel Chemistry and Technology,2012,40(8):927-934.
[11] 张思文,沈来宏,顾海明,等. 钠修饰铁矿石载氧体的串行流化床煤化学链燃烧试验[J]. 化工学报,2013,64(11):4187-4195. ZHANG S W,SHEN L H,GU H M,et al. Chemical-looping combustion of coal in interconnected fluidized bed using Na-loaded iron ore as oxygen carrier[J]. CIESC Journal,2013,64(11):4187-4195.
[12] 周玉飞,沈来宏,顾海明,等. 生物质灰对铁矿石载氧体性能的影响[J]. 东南大学学报(自然科学版),2015,45(3):503-508. ZHOU Y F,SHEN L H,GU H M,et al. Effect of biomass ash on performance of iron ore as oxygen carrier in chemical looping combustion[J]. Journal of Southeast University (Natural Science Edition),2015,45(3):503-508.
[13] WANG X,LIU H,JIN B,et al. Experimental evaluation of a chinese sulfur-containing lean iron ore as the oxygen carrier for chemical-looping combustion[J]. Industrial & Engineering Chemistry Research,2016,55(2):428-435.
[14] LIU S,LEE D,LIU M,et al. Selection and application of binders for CaSO₄ oxygen carrier in chemical-looping combustion[J]. Energy & Fuels,2010,24(12):6675-6681.
[15] VAN EVKP J,ASHMAN P J,NATHAN G J. Mechanism and kinetics of sodium release from brown coal char particles during combustion[J]. Combustion and Flame,2011,158(12):2512-2523.
[16] SCHURMANN H,MONKHOUSE P B,UNTERBERGER S,et al. In situ parametric study of alkali release in pulverized coal combustion:effects of operating conditions and gas composition[J]. Proceedings of the Combustion Institute,2007,31(2):1913-1920.
[17] LINDERHOLM C,SCHMITZ M,KNUTSSON P,et al. Use of low-volatile solid fuels in a 100kW chemical-looping combustor[J]. Energy & Fuels,2014,28(9):5942-5952.
[18] KIM H R,WANG D,ZENG L,et al. Coal direct chemical looping combustion process:design and operation of a 25kW th,sub-pilot unit[J]. Fuel,2013,108(11):370-384.
[19] XIAO R,CHEN L,SAHA C,et al. Pressurized chemical-looping combustion of coal using an iron ore as oxygen carrier in a pilot-scale unit[J]. International Journal of Greenhouse Gas Control,2012,10(5):363-373.
[20] 牛欣,沈来宏,肖军,等. 基于水泥修饰的赤铁矿载氧体污泥化学链燃烧特性研究[J]. 燃料化学学报,2015,43(11):1402-1408. NU X,SHEN L H,XIAO J,et al. Chemical looping combustion of sewage sludge with oxygen carrier of cement-modified hematite[J]. Journal of Fuel Chemistry and Technology,2015,43(11):1402-1408.
[21] ADANEZ J,CUADRAT A,ABAD A,et al. Ilmenite activation during consecutive redox cycles in chemical-looping combustion[J]. Energy & Fuels,2010,24(2):1402-1413.
[22] ABAD A,ADANEZ J,García-Labiano F,et al. Mapping of the range of operational conditions for Cu-,Fe-,and Ni-based oxygen carriers in chemical looping combustion[J]. Chemical Engineering Science,2007,62(1):533-549.
[23] ABAD A,GARCIA-LABIANO F,DE DIEGO L F,et al. Reduction kinetics of Cu-,Ni-,and Fe-based oxygen carriers using syngas (CO+ H₂) for chemical-looping combustion[J]. Energy & Fuels,2007,21(4):1843-1853.
[24] ADANEZ J,CUADRAT A,ABAD A,et al. Ilmenite activation during consecutive redox cycles in chemical-looping combustion[J]. Energy & Fuels,2010,24(2):1402-1413.
[25] 王煜茜. 基于铁矿石载氧体的气体燃料化学链燃烧特性与气固流动模拟研究[D]. 南京:东南大学,2015. WANG Y X. Chemical looping combustion of gaseous fuel based on iron ore oxygen carrier and hydrodynamics in interconnected fluidized beds[D]. Nanjing:Southeast University,2015.
[26] 顾海明. 基于铁矿石载氧体的化学链燃烧特性研究[D]. 南京:东南大学,2014. GU H M. The characteristic of chemical looping combustion suing iron ore as oxygen carrier[D]. Nanjing:Southeast University,2014.
[27] 王润平,毛树红,池永庆,等. 费托合成铁基催化剂助剂的研究概述[J]. 天津化工,2008,22(1):17-19. WANG R P,MAO S H,CHI Y Q,et al. The research review of Fischer-Tropsch catalysts promoter based on iron ore[J]. Tianjin Chemical Industry,2008,22(1):17-19.
[28] 刘浪,刘清才,孟飞,等. 化学链燃烧过程中铁基烧结返矿载氧体反应活性及结构研究[J]. 燃料化学学报,2016,44(10):1177-1184. LIU L,LIU Q C,MENG F,et al. Reaction activity and structural characterizations of sintered return fine oxygen carriers in chemical-looping combustion[J]. Journal of Fuel Chemistry and Technology,2016,44(10):1177-1184.
[29] 高正平,黄启龙,顾海明,等. 基于草木灰修饰铁矿石的串行流化床化学链燃烧[J]. 热科学与技术,2016,15(5):397-405. GAO Z P,HUANG Q L,GU H M,et al. Chemical-looping combustion in interconnected fluidized bed using oxygen carrier of biomass-ash-modified iron ore[J]. Journal of Thermal Science and Technology,2016,15(5):397-405.