Al_2O_3-SiO_2-CaO-FeO四元体系煤灰结构及流动性关系的实验和理论研究
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摘要
将分子动力学、热力学计算与实验结合研究了Al_2O_3-SiO_2-CaO-FeO四元体系灰渣黏度变化机理。在Al_2O_3-SiO_2-CaO-FeO四元体系中,钙铁质量比(简称钙铁比,下同)增加,黏度下降,黏温曲线类型由结晶渣转变为玻璃渣,钙铁比为2时为黏温特性转变的拐点。钙铁比小于2时,体系中的矿物质主要是结晶矿物质,体系中降温过程中生成晶体矿物较多,当钙铁比大于2时,体系以无定形矿物质为主;从微观角度分析,钙铁比增加导致体系中Al由六配位([AlO_6]~(9-))转变为四配位([AlO_4]~(5-)),钙铁两种原子对体系中六配位铝的影响存在竞争作用。体系中的桥氧含量降低,体系的聚合程度降低,稳定性降低。通过四元体系的氧键为桥梁,建立了碱性组分含量与黏度的函数关系。
The molecular dynamics simulation,thermal dynamic calculation and experimental investigation were combined to illustrate ash slag viscosity variation mechanism for Al_2O_3-SiO_2-CaO-FeO system. The viscosity declines and the viscosity curve is transformed from crystalline slag to glassy slag with increasing mass ratio( C/F) of calcium to ferrous oxide in Al_2O_3-SiO_2-CaO-FeO system. There is an inflexion point when the C/F is equal to 2. When the C/F is below 2,there are mainly crystalline minerals in the system. While the C/F is above2, there are mainly amorphous minerals in the system. With the increase of C/F, six-coordinated Al( [AlO_6]~(9-)) is transformed to four coordinated Al( [AlO_4]~(5-)) microscopically. Besides,the content of bridging oxygen decreases while that of non-bridging oxygen increases. Quantified function between base composition and viscosity are constructed based on the stability coefficients defined by oxygen bond species.
The molecular dynamics simulation,thermal dynamic calculation and experimental investigation were combined to illustrate ash slag viscosity variation mechanism for Al_2O_3-SiO_2-CaO-FeO system. The viscosity declines and the viscosity curve is transformed from crystalline slag to glassy slag with increasing mass ratio( C/F) of calcium to ferrous oxide in Al_2O_3-SiO_2-CaO-FeO system. There is an inflexion point when the C/F is equal to 2. When the C/F is below 2,there are mainly crystalline minerals in the system. While the C/F is above2, there are mainly amorphous minerals in the system. With the increase of C/F, six-coordinated Al( [AlO_6]~(9-)) is transformed to four coordinated Al( [AlO_4]~(5-)) microscopically. Besides,the content of bridging oxygen decreases while that of non-bridging oxygen increases. Quantified function between base composition and viscosity are constructed based on the stability coefficients defined by oxygen bond species.
引文
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[2]王辅臣.大规模高效气流床煤气化技术基础研究进展[J].中国基础科学,2008,10(3):4-13.(WANG Fu-chen.Progress on the large-scale and high-efficiency energy entrained flow coal gasification technology[J].China Basic Sci,2008,10(3):4-13.)
[3]王辅臣,于广锁,龚欣,刘海峰,王亦飞,梁钦峰,大型煤气化技术的研究与发展[J].化工进展,2009,28(2):173-180.(WANG Fu-chen,YU Guang-suo,GONG Xin,LIU Hai-feng,WANG Yi-fei,LIANG Qin-feng.Research and development of large-scale coal gasification technology[J].Chem Ind Eng Prog,2009,28(2):173-180.)
[4]宫经德,壳牌煤气化技术及其工程应用[J].化肥设计,2007,6:8-12+18.(GONG Jing-de.Shell coal gasification technology and its engineering application[J].Chem Fert Des,2007,6:8-12+18.)
[5]白进,李文,李保庆,高温弱还原气氛下煤中矿物质变化的研究[J].燃料化学学报,2006,34(3):292-297.(BAI Jin,LI Wen,LI Bao-qing.Mineral behavior in coal under reducing atmosphere at high temperature[J].J Fuel Chem Technol,2006,34(3):292-297.)
[6]廖敏,郭庆华,梁钦锋,袁海平,倪建军,于广锁,气化条件下煤灰高温物相变化及其对黏度的影响[J].中国电机工程学报,2010,30(17):45-50.(LIAO Min,GUO Qing-hua,LIANG QIN-feng,YUAN Hai-ping,NI Jian-jun,YU Guang-suo.Phase transformation of coal ash at high temperature under gasification conditions and its influence on viscosity[J].Proc CSEE,2010,30(17):45-50.)
[7]陈晓东,孔令学,白进,白宗庆,李文.高温气化条件下Na2O对煤灰中矿物质演化行为的影响[J].燃料化学学报,2016,44(3):263-272.(CHEN Xiao-dong,KONG Ling-xue,BAI Jin,BAI Zong-qing,LI Wen.Effect of Na2O on mineral transformation of coal ash under high temperature gasificaiton condition[J].J Fuel Chem Technol,2006,44(3):263-272.)
[8]KONG L X,BAI J,LI W,WEN X D,LI X,BAI Z Q,GUO Z X,LI H Z.The internal and external factor on coal ash slag viscosity at high temperatures,Part 3:Effect of CaO on the pattern of viscosity-temperature curves of slag[J].Fuel,2016,179:10-16.
[9]KONG L X,BAI J,LI W,WEN X D,LI X,BAI Z Q,GUO Z X,LI H Z.The internal and external factor on coal ash slag viscosity at high temperatures,Part 1:Effect of cooling rate on slag viscosity,measured continuously[J].Fuel,2015,158:968-975.
[10]KONG L X,BAI J,LI W,WEN X D,LI X,BAI Z Q,GUO Z X,LI H Z.The internal and external factor on coal ash slag viscosity at high temperatures,Part 2:Effect of residual carbon on slag viscosity[J].Fuel,2015,158:976-982.
[11]XUAN W W,WHITTY K J,GUAN Q L,BI D P,ZHAN Z,ZHANG J S.Influence of CaO on crystallization characteristics of synthetic coal slags[J].Energy Fuels,2014,28(10):6627-6634.
[12]DAI X,BAI J,HUANG Q,LIU Z,BAI X J,CAO R G,WEN X D,LI W,DU S Y.Viscosity temperature properties from molecular dynamics simulation:The role of calcium oxide,sodium oxide and ferrous oxide[J].Fuel,2019,237:163-169.
[13]WU T,WANG Q,YU C F,HE S P.Structural and viscosity properties of CaO-SiO2-Al2O3-FeO slags based on molecular dynamic simulation[J].J Non-Cryst Solids,2016,450:23-31.
[14]李洁,杜梅芳,闫博,张忠孝.添加硼砂助熔剂煤灰熔融性的量子化学与实验研究[J].燃料化学学报,2008,36(5):519-523.(LI Jie,DU Mei-fang,YAN Bo,ZHANG Zhong-xiao.Quantum and experimental study on coal ash fusion with borax fluxing agent[J].JFuel Chem Technol,2008,36(5):519-523.)
[15]陈玉爽,张忠孝,乌晓江,李洁,管嵘清,闫博.配煤对煤灰熔融特性影响的实验与量化研究[J].燃料化学学报,2009,37(5):521-526.(CHEN Yu-shuang,ZHANG Zhong-xiao,WU Xiao-jiang,LI Jie,GUAN Rong-qing,YAN Bo.Quantum chemistry calculation and experimental study on coal ash fusion characeristics of blend coal[J].J Fuel Chem Technol,2009,37(5):521-526.)
[16]GUILLOT B,SATOR N.A computer simulation study of natural silicate melts.Part II:High pressure properties[J].Geochim Cosmochim Acta,2007,71(5):4538-4556.
[17]GUILLOT B,SATOR N.A computer simulation study of natural silicate melts.Part I:Low pressure properties[J].Geochim Cosmochim Acta,2007,71(5):1249-1265.
[18]BALE C W,BELISLE E,CHARTRAND P,DE CTEROV S A,ERIKSSON G,GHERIBI A E,HACK K,JUNG I H,KANG Y B,MELANCON J,PELTON A D,PETERSEN S,ROBELIN C,SANGSTER J,SPENCER P,VAN ENDE M A.FactSage thermochemical software and databases,2010-2016,CALPHAD[J].2016,54:35-53.
[19]BALE C W,BELISLE E,CHARTRAND P,DECTEROV S A,ERIKSSON G,HACK K,JUNG I H,KANG Y B,MELANCON J,PELTON A D,ROBELIN C,PETERSEN S.FactSage thermochemical software and databases-recent developments[J].Calphad,2009,33:295-311.
[20]BALE C W,CHARTRAND P,BELISLE E,DECTEROV S A,ERIKSSON G,HACK K,MAHFOUD R J,PELTON A D,PETERSEN S.Factsage thermochemical software and databases[J].Calphad,2002,26:189-228.
[21]SONG W J,TANG L H,ZHU X D,WU Y Q,ZHU Z B,KOYAMA S.Effect of coal ash composition on ash fusion temperatures[J].Energy Fuels,2010,24(1):182-189.