生物质燃烧过程的固态沉积特性
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摘要
生物质的清洁可再生优势使其具有广阔的发展前景。但由于其含有大量碱金属,在燃烧过程中容易出现积灰结渣、聚团和腐蚀等问题,制约着生物质燃料的大规模应用。本文采用理论与实验相结合的方法,利用灰成分分析、X-射线衍射(XRD)分析、扫描电镜能谱分析(SEM/EDS)及电子探针X射线显微分析(EPMA)等测试手段对三种生物质秸秆(玉米秸秆、燕麦秸秆和水稻秸秆)燃烧过程的固态沉积物进行研究,深入地探讨了生物质燃烧的固态沉积物特性,旨在探明沉积物的形成机理。
本文利用化学热力学平衡软件HSC对三种秸秆不同温度下燃烧的产物进行了预测,结果表明:K与Cl的反应先于Na;900℃后Cl可以从K_2SO_4和Na_2SO_4中获取碱金属增加气态物质总量;高的Na、Si含量会使温度低于800℃时得到的钠的生成物种类复杂,同时提高K的活性及产物复杂性;当硅含量相对较高时,在低于850℃的温度下固相中存在成较多碱金属硅铝酸盐。
在管式沉降炉上研究了三种秸秆在不同燃烧时间、温度下燃烧过程的固态沉积特性。结果表明:三种生物质的沉积物量与原料的灰分、燃烧时间及燃烧温度都有密切关系,水稻秸秆沉积物量受时间变化的增加最大,燕麦秸秆燃烧沉积物量受温度影响的增加程度最大,沉积物硬度依次是玉米秸秆>燕麦秸秆>水稻秸秆,致密程度同此顺序,三种生物质沉积物的灰成分分析结果均以SiO2、CaO为主,Al_2O_3、K2_O和Na_2O等含量的差异影响着沉积物中化合物的种类和多样性;生物质秸秆燃烧沉积物的形成过程分累积粘结、“桥接”聚团,“交错搭架”这三种,这与秸秆粉末中的颗粒大小分布有关,沉积物中钾长石是支撑结构,沉积物外表的光滑是通过含碱金属的低熔点化合物等融化来实现,气态物质逐渐挥发在沉积物表面形成孔洞或气泡。孔隙的填充使沉积物变得致密。灰色关联度分析结果表明除燃料的碱金属含量外,温度是决定沉积物结渣特性的关键因子。
Biomass have broad prospects due to its clean and renewable advantage. But the existence of alkali metals cause many problem during the biomass combustion. This paper combined the theory predict and experiment. Using chemical fractionation analysis, XRD, SEM/EDS and EPMA to analyse the characteristics of the solid phase deposition in different combustion temperature and time, which came from three different kinds biomass straws ( the straw of corn, oats and rice ). For a deep research on the mechanism of the deposition formation.
This paper predicted the effects of temperature on the compounds variety on the base of chemical thermal equilibrium calculation. The results show that: K will first react with Cl, Cl can get alkali metals from K2SO4 and Na2SO4 to add gas phase substance after 900℃; Low content Na will cause little Na2SO4 formation, when the content is high, it will make the compounds below 800℃more complex and increase the activities of K; There are many solid phase compounds of aluminum borosilicate with alkali metals, high content Si will cause appearence of these compounds below 850℃.
This investigation was carried out in the self-designed deposition furnace which examined the dynamic characteristics during three biomass straw combustion. The results showed that:The deposition weight was close connected with straw ash content, temperature and time, the increase of rice straw deposition weight was significantly affected by combustion time, and so did the combustion temperature on oat straw. The order of deposition hard is corn straw > oats straw > rice straw, the main part of chemical fractionation in all deposition are SiO2 and CaO, the content variety of other compounds like Al2O3, K2O and Na2O can effect crystalline forms and diversity in the deposition; there are three kinds process of deposition formation, agglutination, "bridge connection", "crisscross stand", respectively, and which of them was followed in the actual process depended on the particle size distribution in biomass fragments. Potassium feldspar is the supporting structure of deposition, and the oxide compounds of Al, Fe, Ca, Mg continued to fill the interspace and make the structure closed-grain. The formation process of compounds can be described as from simple to complex and part to whole, finally, elements evenly distributed.
At last, the clinkering index of deposition was analyzed by gray association degree theory in different combustion temperature, time and alkali metals content. The results show that apart from alkali metals content, the temperature is the most important element.
本文利用化学热力学平衡软件HSC对三种秸秆不同温度下燃烧的产物进行了预测,结果表明:K与Cl的反应先于Na;900℃后Cl可以从K_2SO_4和Na_2SO_4中获取碱金属增加气态物质总量;高的Na、Si含量会使温度低于800℃时得到的钠的生成物种类复杂,同时提高K的活性及产物复杂性;当硅含量相对较高时,在低于850℃的温度下固相中存在成较多碱金属硅铝酸盐。
在管式沉降炉上研究了三种秸秆在不同燃烧时间、温度下燃烧过程的固态沉积特性。结果表明:三种生物质的沉积物量与原料的灰分、燃烧时间及燃烧温度都有密切关系,水稻秸秆沉积物量受时间变化的增加最大,燕麦秸秆燃烧沉积物量受温度影响的增加程度最大,沉积物硬度依次是玉米秸秆>燕麦秸秆>水稻秸秆,致密程度同此顺序,三种生物质沉积物的灰成分分析结果均以SiO2、CaO为主,Al_2O_3、K2_O和Na_2O等含量的差异影响着沉积物中化合物的种类和多样性;生物质秸秆燃烧沉积物的形成过程分累积粘结、“桥接”聚团,“交错搭架”这三种,这与秸秆粉末中的颗粒大小分布有关,沉积物中钾长石是支撑结构,沉积物外表的光滑是通过含碱金属的低熔点化合物等融化来实现,气态物质逐渐挥发在沉积物表面形成孔洞或气泡。孔隙的填充使沉积物变得致密。灰色关联度分析结果表明除燃料的碱金属含量外,温度是决定沉积物结渣特性的关键因子。
Biomass have broad prospects due to its clean and renewable advantage. But the existence of alkali metals cause many problem during the biomass combustion. This paper combined the theory predict and experiment. Using chemical fractionation analysis, XRD, SEM/EDS and EPMA to analyse the characteristics of the solid phase deposition in different combustion temperature and time, which came from three different kinds biomass straws ( the straw of corn, oats and rice ). For a deep research on the mechanism of the deposition formation.
This paper predicted the effects of temperature on the compounds variety on the base of chemical thermal equilibrium calculation. The results show that: K will first react with Cl, Cl can get alkali metals from K2SO4 and Na2SO4 to add gas phase substance after 900℃; Low content Na will cause little Na2SO4 formation, when the content is high, it will make the compounds below 800℃more complex and increase the activities of K; There are many solid phase compounds of aluminum borosilicate with alkali metals, high content Si will cause appearence of these compounds below 850℃.
This investigation was carried out in the self-designed deposition furnace which examined the dynamic characteristics during three biomass straw combustion. The results showed that:The deposition weight was close connected with straw ash content, temperature and time, the increase of rice straw deposition weight was significantly affected by combustion time, and so did the combustion temperature on oat straw. The order of deposition hard is corn straw > oats straw > rice straw, the main part of chemical fractionation in all deposition are SiO2 and CaO, the content variety of other compounds like Al2O3, K2O and Na2O can effect crystalline forms and diversity in the deposition; there are three kinds process of deposition formation, agglutination, "bridge connection", "crisscross stand", respectively, and which of them was followed in the actual process depended on the particle size distribution in biomass fragments. Potassium feldspar is the supporting structure of deposition, and the oxide compounds of Al, Fe, Ca, Mg continued to fill the interspace and make the structure closed-grain. The formation process of compounds can be described as from simple to complex and part to whole, finally, elements evenly distributed.
At last, the clinkering index of deposition was analyzed by gray association degree theory in different combustion temperature, time and alkali metals content. The results show that apart from alkali metals content, the temperature is the most important element.
引文
[1]许向路.新农村建设与生物质能开发利用[J].天津科技, 2007(2) :12-13
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[3] P.Abreu, C.Casaca, M.Costa. Ash deposition during the co-firing of bituminous coal with pine sawdust and olive stones in a laboratory furnace[J]. Fuel, 2010, 89: 4040-4048
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[5]米铁,陈汉平,吴正舜,等.生物质灰化学特性的研究[J].太阳能学报, 2004, 25(2): 236-241
[6]肖瑞瑞,陈雪莉,王辅,等.不同生物质灰的理化特性[J].太阳能学报,2011,32(3):364-369
[7]唐艳玲.稻秸热解过程中碱金属析出的实验研究[D].杭州:浙江大学, 2004
[8]孙巍,马增益,严建华,等.垃圾焚烧炉尾部受热面积灰及其抑制方法分析[J].能源与环境, 2006, 1: 46-49
[9] Huanpeng Liu, Shaohua Wu, Dunyu Liu. The role of ash particles in the bed agglomeration during the fluidized bed combustion of rice straw[J]. Bioresource Technology, 2009, 100: 6505–6513
[10] Kalpit V. Shah, Mariusz K. Cieplik , Christine I. Betrand, etal. Correlating the effects of ash elements and their association in the fuel matrix with the ash release during pulverized fuel combustion, Fuel Processing Technology, 91(2010): 531–545
[11]张军,盛昌栋,魏启东.生物质燃烧过程中受热面的腐蚀性机理和防范措施[J].能源技术, 2005, 26(5): 124-127
[12] Gottwald U, Monkhouse P, Wulgaris N, etal. In study of the effect of operating conditions and additives on alkali emissions in ?uidised bed combustion[J]. Fuel Process Technol, 2002, 75: 215-226
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[16]赵莹,刘晓明,李敏,等.煤中氯在燃烧和热解中释放特性及脱除方法研究进展[J].山东科技大学学报(自然科学版), 2004, 23(2): 108-111
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[18] L.Fryda, C.Sobrino, M.Cieplik, et al. Study on ash deposition under oxyfuel combustion of coal/biomass blends[J]. Fuel, 2010, 89: 1889–1902
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[21] A.L.Elled, K.O.Davidsson, L.E.Amand. Sewage sludge as a deposit inhibitor when co-fired with high potassium fuels[J]. Biomass and Bioenergy, 2010, 34: 1546-1554
[22] C.Bartolomé, et al. Ash deposition behavior of cynara–coal blends in a PF pilot furnace[J]. FuelProcessing Technology, 2010, 91:1576–1584
[23] H.Haykiri-Acma, S.Yaman, S.Kucukbayrak. Effect of biomass on temperatures of sintering and initial deformation of lignite ash[J]. Fuel, 2010, 89: 3063–3068
[24] Baxter L. L., Miles T. R., Miles T. R., etal. The behavior of inorganic material in biomass ?red power boilers: ?eld and laboratory experiences[J]. Fuel Process Technology, 2002, 54: 47-78
[25] Gottwald U., Monkhouse P., Bonn B.. Biomass combustion in fluidized bed boilers: Potential problems and remedies[J]. Fuel, 2001, 80: 78-93
[26] Aho M., Ferrer E.. Preventing chlorine deposition on heat transfer surfaces with aluminium-silicon rich biomass residue and additives[J]. Fuel, 2004, 83: 1299-1305
[27]马孝琴,骆仲泱,方梦祥,等.添加剂对秸秆燃烧过程中碱金属行为的影响[J].浙江大学学报(工学版), 2006, 4(40): 599-604
[28] D.Vamvuka, M.Pitharoulis, G.Alevizos, et al. Ash effects during combustion of lignite/biomass blends in fluidized bed[J]. Renewable Energy, 2009, 34: 2662-2671
[29] Andrea Johnson, Lionel J.J. Catalan, Stephen D. Kinrade. Characterization and evaluation of ?y-ash from co-combustion of ligniteand wood pellets for use as cement admixture[J]. Fuel, 89(2010): 3042–3050
[30]张艳平,金保升,生物质热化学转化过程中碱金属问题的相关研究[J].能源研究与利用, 2007, 3: 27-31
[31]李勇,肖军,章名耀.燃煤过程中碱金属赋存迁移规律的模拟研究[J].动力工程, 2005, 25(Sup): 97-105
[32] Jacob N. K., Peter A. J., and Kim D. J.. Transformation and Release to the Gas Phase of Cl, K, and S during Combustion of Annual Biomass[J]. Energy & Fuels, 2004,18(5): 1385-1399
[33] H. Oleschko, A. Schimrosczyk, H. Lippert, M. Muller. In?uence of coal compositionon the release of Na-, K-, Cl-, and S-species during the combustion of brown coal, Fuel 86 (2007): 2275–2282.
[34]蒋旭光,徐旭,严建华,等.煤燃烧过程中氯析出特性的实验研究[J].煤炭学报, 2002, 27(4): 398-401
[35] Awassada Phongphiphat, Changkook Ryu. Investigation into high-temperature corrosion in a large-scale municipal waste-to-energy plant[J]. Corrosion Science, 2010, 52: 3861-3874.
[36]吕仲明,钟用禄,李长佶,等.燃煤过程中重金属形态的热力平衡分析[J].江西电力, 2003, 26(2): 8-11
[37]苏正军,关立友,石爱丽,等.环境扫描电子显微镜工作原理及其气象学应用[J].气象科技, 2010, 38(2): 259-262
[38]秦建光,余春江,聂虎等.秸秆燃烧中温度对钾转化与释放的影响[J].太阳能学报, 2010, 3(5): 540-544
[39] X.G.Xu,S.Q.Li,G.D.Li,et al.Effect of Co-firing Straw with Two Coals on the Ash Deposition Behavior in a Down-Fired Pulverized Coal Combustor[J].Energy Fuels,2010,21:241-249
[40] B.J.Skrifvar,M.Westén-Karlsson,M.Hupa.Corrosion of super-heater steel materials under alkali salt deposits.Part 2:SEM analyses of different steel materials[J]. Corrosion Science,2010,52:1011-1019
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[2]钱能志,尹国平,陈卓.欧洲生物质能源开发利用现状和经验[J].中外能源, 2007, 12(3) :11-12
[3] P.Abreu, C.Casaca, M.Costa. Ash deposition during the co-firing of bituminous coal with pine sawdust and olive stones in a laboratory furnace[J]. Fuel, 2010, 89: 4040-4048
[4]王革华.能源与可持续发展[M].北京:化学工业出版社, 2005, 1
[5]米铁,陈汉平,吴正舜,等.生物质灰化学特性的研究[J].太阳能学报, 2004, 25(2): 236-241
[6]肖瑞瑞,陈雪莉,王辅,等.不同生物质灰的理化特性[J].太阳能学报,2011,32(3):364-369
[7]唐艳玲.稻秸热解过程中碱金属析出的实验研究[D].杭州:浙江大学, 2004
[8]孙巍,马增益,严建华,等.垃圾焚烧炉尾部受热面积灰及其抑制方法分析[J].能源与环境, 2006, 1: 46-49
[9] Huanpeng Liu, Shaohua Wu, Dunyu Liu. The role of ash particles in the bed agglomeration during the fluidized bed combustion of rice straw[J]. Bioresource Technology, 2009, 100: 6505–6513
[10] Kalpit V. Shah, Mariusz K. Cieplik , Christine I. Betrand, etal. Correlating the effects of ash elements and their association in the fuel matrix with the ash release during pulverized fuel combustion, Fuel Processing Technology, 91(2010): 531–545
[11]张军,盛昌栋,魏启东.生物质燃烧过程中受热面的腐蚀性机理和防范措施[J].能源技术, 2005, 26(5): 124-127
[12] Gottwald U, Monkhouse P, Wulgaris N, etal. In study of the effect of operating conditions and additives on alkali emissions in ?uidised bed combustion[J]. Fuel Process Technol, 2002, 75: 215-226
[13]段菁春,肖军,王杰林,等.生物质与煤共燃研究[J].电站系统工程,2004,20(1):1-4
[14] Dayton D. C., Belle-Oudry D., Release of K, Cl, and S Species during Co-combustion of Coal and Straw[J]. Energy & Fuels, 2006, 20: 1444-1449
[15] Lee S. H. D., Teats F. G., Swift W. M., etal. Chlorine emission and dechlorination in co-?ring coal and the residue from hydrochloric acid hydrolysis of Discorea zingiberensis[J]. Science Technology, 2006, 85: 2035-2040
[16]赵莹,刘晓明,李敏,等.煤中氯在燃烧和热解中释放特性及脱除方法研究进展[J].山东科技大学学报(自然科学版), 2004, 23(2): 108-111
[17] H. Oleschko, A. Schimrosczyk, H. Lippert, M. Muller, In?uence of coal compositionon the release of Na-, K-, Cl-, and S-species during the combustion of brown coal, Fuel 86(2007): 2275–2282
[18] L.Fryda, C.Sobrino, M.Cieplik, et al. Study on ash deposition under oxyfuel combustion of coal/biomass blends[J]. Fuel, 2010, 89: 1889–1902
[19] Y. Zheng, P.A. Jensen, A.D. Jensen, B. Sander, Helle J.B., Ash transformation during co-?ring coal and straw, Fuel, 86 (2007): 1008–1020
[20] Johan Werkelin, Bengt-Johan Skrifvars, Maria Zevenhoven, etal. Chemical forms of ash-forming elements in woody biomass fuels, Fuel, 89(2010): 481–493
[21] A.L.Elled, K.O.Davidsson, L.E.Amand. Sewage sludge as a deposit inhibitor when co-fired with high potassium fuels[J]. Biomass and Bioenergy, 2010, 34: 1546-1554
[22] C.Bartolomé, et al. Ash deposition behavior of cynara–coal blends in a PF pilot furnace[J]. FuelProcessing Technology, 2010, 91:1576–1584
[23] H.Haykiri-Acma, S.Yaman, S.Kucukbayrak. Effect of biomass on temperatures of sintering and initial deformation of lignite ash[J]. Fuel, 2010, 89: 3063–3068
[24] Baxter L. L., Miles T. R., Miles T. R., etal. The behavior of inorganic material in biomass ?red power boilers: ?eld and laboratory experiences[J]. Fuel Process Technology, 2002, 54: 47-78
[25] Gottwald U., Monkhouse P., Bonn B.. Biomass combustion in fluidized bed boilers: Potential problems and remedies[J]. Fuel, 2001, 80: 78-93
[26] Aho M., Ferrer E.. Preventing chlorine deposition on heat transfer surfaces with aluminium-silicon rich biomass residue and additives[J]. Fuel, 2004, 83: 1299-1305
[27]马孝琴,骆仲泱,方梦祥,等.添加剂对秸秆燃烧过程中碱金属行为的影响[J].浙江大学学报(工学版), 2006, 4(40): 599-604
[28] D.Vamvuka, M.Pitharoulis, G.Alevizos, et al. Ash effects during combustion of lignite/biomass blends in fluidized bed[J]. Renewable Energy, 2009, 34: 2662-2671
[29] Andrea Johnson, Lionel J.J. Catalan, Stephen D. Kinrade. Characterization and evaluation of ?y-ash from co-combustion of ligniteand wood pellets for use as cement admixture[J]. Fuel, 89(2010): 3042–3050
[30]张艳平,金保升,生物质热化学转化过程中碱金属问题的相关研究[J].能源研究与利用, 2007, 3: 27-31
[31]李勇,肖军,章名耀.燃煤过程中碱金属赋存迁移规律的模拟研究[J].动力工程, 2005, 25(Sup): 97-105
[32] Jacob N. K., Peter A. J., and Kim D. J.. Transformation and Release to the Gas Phase of Cl, K, and S during Combustion of Annual Biomass[J]. Energy & Fuels, 2004,18(5): 1385-1399
[33] H. Oleschko, A. Schimrosczyk, H. Lippert, M. Muller. In?uence of coal compositionon the release of Na-, K-, Cl-, and S-species during the combustion of brown coal, Fuel 86 (2007): 2275–2282.
[34]蒋旭光,徐旭,严建华,等.煤燃烧过程中氯析出特性的实验研究[J].煤炭学报, 2002, 27(4): 398-401
[35] Awassada Phongphiphat, Changkook Ryu. Investigation into high-temperature corrosion in a large-scale municipal waste-to-energy plant[J]. Corrosion Science, 2010, 52: 3861-3874.
[36]吕仲明,钟用禄,李长佶,等.燃煤过程中重金属形态的热力平衡分析[J].江西电力, 2003, 26(2): 8-11
[37]苏正军,关立友,石爱丽,等.环境扫描电子显微镜工作原理及其气象学应用[J].气象科技, 2010, 38(2): 259-262
[38]秦建光,余春江,聂虎等.秸秆燃烧中温度对钾转化与释放的影响[J].太阳能学报, 2010, 3(5): 540-544
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