高温还原性气氛下钙镁助熔剂对莫来石熔融性的影响
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摘要
以莫来石为研究对象,向其中添加单助熔剂CaO,MgO和钙镁复配助熔剂,在模拟煤高温还原性气氛下,利用X-射线衍射仪研究了钙镁复合助熔剂对矿物转化的影响,借助FactSage热力学软件分析了添加钙镁复配助熔剂后灰渣在高温下的相平衡组成及矿物的组成含量变化,结合量子化学软件Material Studio 7.0对莫来石的建模优化,从分子水平揭示了钙镁复配助熔剂的助熔机理。结果表明:添加质量为莫来石质量20%的钙镁复配助熔剂(mCaO/mMgO=1)后,可将流动温度降至1 426℃,且助熔效果优于单助熔剂的助熔效果;莫来石熔融过程中,Ca~(2+)和Mg~(2+)易从莫来石晶格中的Al(6)—O(8)和Al(5)—O(7)两处进入铝氧八面体,引起硅酸盐结构重组,生成的低熔点长石类矿物和镁质矿物是钙镁复合助熔剂显著降低熔融温度的主要原因。
Taking mullite as the research object,adding single fluxes CaO,MgO and calcium-magnesium compound flux to study the mineral transformation of calcium-magnesium compound flux by X-ray diffraction spectroscopy in simulated high temperature reducing atmosphere of coal,with the help of thermodynamic software FactSage,the phase equilibrium composition and mineral composition change of ash at high temperature after adding calcium-magnesium compound flux were analyzed,combined with quantum chemistry software Material Studio 7.0 to optimize the modeling of mullite,from molecular level the fluxing mechanism of the calcium-magnesium compound flux was revealed.The results show that the addition of 20%calcium-magnesium compound flux(mCaO/mMgO=1)can reduce the flow temperature to 1 426℃,and the fluxing effect is better than that of single flux;during the mullite melting process,Ca~(2+)and Mg~(2+)are easy to enter the silicon oxide and aluminum oxide tetrahedron,and the aluminum oxide octahedron causes the silicate structure to recombine.The low-melting feldspar minerals and magnesia minerals produced by the calcium-magnesium compound flux are the main reasons for the significant reduction of the melting temperature.
Taking mullite as the research object,adding single fluxes CaO,MgO and calcium-magnesium compound flux to study the mineral transformation of calcium-magnesium compound flux by X-ray diffraction spectroscopy in simulated high temperature reducing atmosphere of coal,with the help of thermodynamic software FactSage,the phase equilibrium composition and mineral composition change of ash at high temperature after adding calcium-magnesium compound flux were analyzed,combined with quantum chemistry software Material Studio 7.0 to optimize the modeling of mullite,from molecular level the fluxing mechanism of the calcium-magnesium compound flux was revealed.The results show that the addition of 20%calcium-magnesium compound flux(mCaO/mMgO=1)can reduce the flow temperature to 1 426℃,and the fluxing effect is better than that of single flux;during the mullite melting process,Ca~(2+)and Mg~(2+)are easy to enter the silicon oxide and aluminum oxide tetrahedron,and the aluminum oxide octahedron causes the silicate structure to recombine.The low-melting feldspar minerals and magnesia minerals produced by the calcium-magnesium compound flux are the main reasons for the significant reduction of the melting temperature.
引文
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[2]ZHANG Xiaohan,WINCHESTER N,ZHANG Xiliang.The Future of Coal in China[J].Energy Policy,2017,110:644-652.
[3]龚欣,郭晓镭,代正华,等.新型气流床粉煤加压气化技术[J].现代化工,2005,25(3):51-52.GONG Xin,GUO Xiaolei,DAI Zhenghua,et al.Newtype Gasification Technology of Pressurized Entrained-flow for Pulverized Coal[J].Modern Chemical Industry,2005,25(3):51-52.
[4]QIN Ke,LIN Weigang,JENSEN P A,et al.High-temperature Entrained Flow Gasification of Biomass[J].Fuel,2012,93:589-600.
[5]LI Zhenzhu,LI Fenghai,MA Mingjie,et al.Review on Controllable Adjustment of Coal Ash Melting Characteristics with High Ash Melting Point[J].Chemical Engineering,2015,43(3):60-63.
[6]袁海平,梁钦锋,刘海峰,等.CaCO3对煤熔融特性和黏温特性影响的研究[J].中国电机工程学报,2012,32(20):49-55.YUAN Haiping,LIANG Qinfeng,LIU Haifeng,et al.Effect of CaCO3on the Fusion Characteristics and Viscosity-temperature Behaviour of Coal Ashes[J].Proceedings of the CSEE,2012,32(20):49-55.
[7]LI Jie,DU Meifang,ZHANG Zhongxiao,et al.Selection of Fluxing Agent for Coal Ash and Investigation of Fusion Mechanism:a First-principles Study[J].Energy and Fuels,2009,23(2):704-709.
[8]KONG Lingxue,BAI Jin,BAI Zongqing,et al.Effects of CaCO3on Slag Flow Properties at High Temperatures[J].Fuel,2013,109(7):76-85.
[9]范立明,陈杰2),田晓莉,等.石灰石添加量对黄陵煤灰熔融特性的影响[J].煤化工,2007(2):61-63.FAN Liming,CHEN Jierong,TIAN Xiaoli,et al.Study of Optimum Amount of Limestone Addition in Preparation of Coal Water Slurry[J].Coal Chemical Industry,2007(2):61-63.
[10]闫博,张忠孝,陈龙.高温气化过程中降低煤灰熔点的实验研究[J].洁净煤技术,2007(5):71-74.YAN Bo,ZHANG Zhongxiao,CHEN Long.The Experiment Study of Reducing Coal Ash Melting Point During High Temperature Gasified[J].Clean Coal Technology,2007(5):71-74.
[11]段锦,李寒旭,郝华东,等.钙镁复合助熔剂对长平煤灰熔融特性影响研究[J].硅酸盐通报,2016,35(12):3936-3941.DUAN Jin,LI Hanxu,HAO Huadong,et al.Effect of Calcium and Magnesium Compound Flux on Changping Coal Ash Fusibility[J].Bulletin of the Chinese Ceramic Society,2016,35(12):3936-3941.
[12]王大川,梁钦锋,龚欣,等.添加助熔剂后朱集西煤灰熔融特性规律研究[J].燃料化学学报,2015,43(2):153-159.WANG Dachuan,LIANG Qinfeng,GONG Xin,et al.Fusion Properties of Zhujixi Washed Coal Ash Adding Flux[J].Journal of Fuel Chemistry and Technology,2015,43(2):153-159.
[13]CHAKRAVARTY S,MOHANTY A,BANERJEE A,et al.Composition,Mineral Matter Characteristics and Ash Fusion Behavior of Some Indian Coals[J].Fuel,2015,150:96-101.
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[15]LI Fenghai,FANG Yitian.Ash Fusion Characteristics of a High Aluminum Coal and Its Modification[J].Energy and Fuels,2016,30(4):2925-2931.
[16]WU Xiaojiang,ZHANG Zhongxiao,CHEN Yushuang,et al.Main Mineral Melting Behavior and Mineral Reaction Mechanism at Molecular Level of Blended Coal Ash Under Gasification Condition[J].Fuel Processing Technology,2010,91(11):1591-1600.
[17]WU Chengli,WANG Beibei,ZHENG Jiuqiang,et al.Flux Mechanism of Compound Flux on Ash and Slag of Coal with High Ash Melting Temperature[J].Chinese Journal of Chemical Engineering,2018.
[18]范浩杰,何柯佳,刘俊杰,等.镁基助熔剂对高灰熔点煤灰熔融影响的机理[J].动力工程学报,2015,35(1):19-24.FAN Haojie,HE Kejia,LIU Junjie,et al.Mechanism of Effect of Magnesium Based Flux on the Fusibility of Coal Ash with High Fusion Point[J].Journal of Chinese Society of Power Engineering,2015,35(1):19-24.
[19]李继炳,沈本贤,赵基钢,等.钙基助熔剂对皖北刘桥二矿混煤的灰熔融特性影响[J].华东理工大学学报(自然科学版),2009,35(4):511-515.LI Jibing,SHEN Benxian,ZHAO Jigang,et al.Effect of Calcium-based Flux on the Melting Characteristics of Coal Ash from Coal Blends Using Liuqiao No.2Coal Mine in Northern Anhui[J].Journal of East China University of Science and Technology,2009,35(4):511-515.
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