高碱煤含钠矿物沉积层的高温熔融及多相反应过程分析
|
摘要
采用纯矿物试剂模拟燃用高碱煤时炉内受热面典型的灰沉积层化学组成,利用热机械分析(TMA)、TG-DSC分析、高温煅烧实验结合XRD、SEM-EDS表征方法研究了不同Na_2SO_4含量灰沉积层的高温熔融过程及矿物间的多相反应机理。结果表明,掺混Na_2SO_4后沉积层熔化特征温度显著降低,Na_2SO_4的主要反应途径与掺混比例有关,当掺混比低于20%时,Na_2SO_4与SiO_2、CaO、Al_2O_3反应主要转变为CaSO_4和钠的硅铝酸盐;掺混比大于40%时则主要与CaSO_4生成低熔点的钠钙复合硫酸盐。富Na_2SO_4沉积层颗粒在800℃时开始黏结;900-950℃时,霞石、钠长石等钠的硅铝酸盐发生低温共熔,同时Na_2SO_4和CaSO_4生成的复合硫酸盐开始熔融,逐渐形成液相;1200-1250℃时,镁黄长石与含钙矿物发生强烈共熔,温度超过1300℃后矿物完全熔融成为自由液相。
The pure chemicals were used to simulate the composition of typical ash deposits on heat exchanger surfaces during high-alkali coal combustion,and the thermal mechanical analysis( TMA),TG-DSC analysis and high-temperature calcination were performed to investigate the high temperature melting characteristics of the deposits with varying content of Na2SO4. Subsequently,XRD and SEM-EDS techniques were applied to investigate the reaction products and detailed mechanism. The results indicate that the melting characteristic temperature of deposits decreases significantly after blending with Na2SO4,and the transformation of Na2SO4 is closely related to the blending ratio. When the blending ratio is below 20%( mass ratio),most Na2SO4 is converted to CaSO4 and sodium aluminosilicate,while Na2SO4 would react with CaSO4 and generate sulfate double salts when the blending ratio is over 40%. M oreover,the particles of Na2SO4 enriched deposits begin to adhere at 800 ℃. When the temperature is elevated to 900-950 ℃,the low-temperature eutectics are easily formed in the presence of nepheline and albite,and the eutectics and Na-Ca sulfate double salts are gradually molten. The large amount of co-melting of akermanite and Ca-bearing minerals was observed at temperatures of1200-1250 ℃,and the minerals are completely melted at temperatures over 1300 ℃.
The pure chemicals were used to simulate the composition of typical ash deposits on heat exchanger surfaces during high-alkali coal combustion,and the thermal mechanical analysis( TMA),TG-DSC analysis and high-temperature calcination were performed to investigate the high temperature melting characteristics of the deposits with varying content of Na2SO4. Subsequently,XRD and SEM-EDS techniques were applied to investigate the reaction products and detailed mechanism. The results indicate that the melting characteristic temperature of deposits decreases significantly after blending with Na2SO4,and the transformation of Na2SO4 is closely related to the blending ratio. When the blending ratio is below 20%( mass ratio),most Na2SO4 is converted to CaSO4 and sodium aluminosilicate,while Na2SO4 would react with CaSO4 and generate sulfate double salts when the blending ratio is over 40%. M oreover,the particles of Na2SO4 enriched deposits begin to adhere at 800 ℃. When the temperature is elevated to 900-950 ℃,the low-temperature eutectics are easily formed in the presence of nepheline and albite,and the eutectics and Na-Ca sulfate double salts are gradually molten. The large amount of co-melting of akermanite and Ca-bearing minerals was observed at temperatures of1200-1250 ℃,and the minerals are completely melted at temperatures over 1300 ℃.
引文
[1]ZHOU J B,ZHUANG X G,ALASTUEY A,QUEROL X,LI J H.Geochemistry and mineralogy of coal in the recently explored Zhundong large coal field in the Junggar basin,Xinjiang province,China[J].Int J Coal Geol,2010,82(1/2):51-67.
[2]张守玉,陈川,施大钟,吕俊复,王健,郭熙,董爱霞,熊绍武.高钠煤燃烧利用现状[J].中国电机工程学报,2013,33(5):1-12.(ZHANG Shou-yu,CHEN Chuan,SHI Da-zhong,LV Jun-fu,WANG Jian,GUO Xi,DONG Ai-xia,XiONG Shao-wu.Situation of combustion utilization of high sodium coal[J].Proc CSEE,2013,33(5):1-12.)
[3]WANG X B,XU Z X,WEI B,ZHANG L,TAN H Z,YANG T,MIKULCIC H,DUIC N.The ash deposition mechanism in boilers burning Zhundong coal with high contents of sodium and calcium:A study from ash evaporating to condensing[J].Appl Therm Eng,2015,80:150-159.
[4]SONG G L,SONG W J,QI X B,LU Q G.Transformation characteristics of sodium of zhundong coal combustion/gasification in circulating fluidized bed[J].Energy Fuels,2016,30(4):3473-3478.
[5]TOMECZEK J,PALUGNIOK H,OCHMAN J.Modelling of deposits formation on heating tubes in pulverized coal boilers[J].Fuel,2004,83(2):213-221.
[6]GLARBORG P,MARSHALL P.Mechanism and modeling of the formation of gaseous alkali sulfates[J].Combust Flame,2005,141(1/2):22-39.
[7]ZHOU H,ZHOU B,ZHANG H,LI L,CEN K.Investigation of slagging characteristics in a 300 kW test furnace:Effect of deposition surface temperature[J].Ind Eng Chem Res,2014,53(17):7233-7246.
[8]WU X J,ZHANG X,YAN K,CHEN N,ZHANG J W,XU X Y,DAI B Q,ZHANG J,ZHANG L.Ash deposition and slagging behavior of Chinese Xinjiang high-alkali coal in 3 M W th pilot-scale combustion test[J].Fuel,2016,181:1191-1202.
[9]杨涛,李文广,吴莎,张兰,王学斌,谭厚章.新疆高钙钠煤燃烧设备结焦机理研究[J].燃料化学学报,2015,43(11):1320-1326.(YANG Tao,LI Wen-guang,WU Sha,ZHANG Lan,WANG Xue-bin,TAN Hou-zhang.Study on fouling mechanism in a boiler burning Xinjiang coal with high content of calcium and sodium[J].J Fuel Chem Technol,2015,43(11):1320-1326.)
[10]魏博,谭厚章,王学斌,胡中发,王毅斌,阮仁晖.准东煤灰沉积与无机元素迁徙特性研究[J].工程热物理学报,2016,37(8):1783-1788.(WEI Bo,TAN Hou-zhang,WANG Xue-bin,HU Zhong-fa,WANG Yi-bin,RUAN Ren-hui.Ash deposition and inorganic element transformation during zhundong coal combustion[J].J Eng Thermophys,2016,37(8):1783-1788.)
[11]WEI B,TAN H Z,WANG Y B,WANG X B,YANG T,RUAN R H.Investigation of characteristics and formation mechanisms of deposits on different positions in full-scale boiler burning high alkali coal[J].Appl Therm Eng,2017,119:449-458.
[12]LI G D,LI S Q,HUANG Q,YAO Q.Fine particulate formation and ash deposition during pulverized coal combustion of high-sodium lignite in a dow n-fired furnace[J].Fuel,2015,143(44):430-437.
[13]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 gasification condition[J].J Fuel Chem Technol,2016,44(3):263-272.)
[14]韩克鑫,黄镇宇,王智化,周俊虎.准东煤灰渣烧结熔融过程中钠基化合物作用机理研究[J].燃料化学学报,2015,43(1):22-26.(HAN Ke-xin,HUANG Zhen-yu,WANG Zhi-hua,ZHOU Jun-hu.Action mechanism of sodium compounds in Zhundong coal ash on the process of sintering and fusion[J].J Fuel Chem Technol,2015,43(1):22-26.)
[15]QI X B,SONG G L,SONG W J,LU Q G.Influence of sodium-based materials on the slagging characteristics of Zhundong coal[J].JEnergy Inst,2016,90(6):914-922.
[16]陈衡,王云刚,马海东,赵钦新.循环流化床锅炉燃用准东煤结渣、沾污分析[J].热能动力工程,2015,30(3):431-435.(CHEN Heng,WANG Yun-gang,MA Hai-dong,ZHAO Qin-xin.Analysis and Study of the Slagging and Contamination of a CFB Boiler Burning Zhundong-originated Coal[J].J Eng Therm Energy Power,2015,30(3):431-435.)
[17]王礼鹏,赵永椿,张军营,姚斌,郑楚光.准东煤沾污结渣特性研究[J].工程热物理学报,2015,36(6):1381-1385.(WANG Li-peng,ZHAO Yong-chun,ZHANG Jun-ying,YAO Bin,ZHENG Chu-guang.Research on the slagging and fouling characteristics of Zhundong coal[J].J Eng Thermophys,2015,36(6):1381-1385.)
[18]杨光,张彦威,寇希文,周志军,王智化,周俊虎,岑可法.燃用准东煤电站锅炉灰沉积形成过程中的矿物演变与热力学模拟[J].燃料化学学报,2015,43(10):1182-1187.(YANG Guang,ZHANG Yan-wei,KOU Xi-wen,ZHOU Zhi-jun,WANG Zhi-hui,ZHOU Jun-hu,CEN Ke-fa.Mineral conversion and thermodynamic simulation of ash deposition during Zhundong coal combustion in boiler of thermal power plant[J].J Fuel Chem Technol,2015,43(10):1182-1187.)
[19]王永贞,金晶,刘敦禹,杨浩然,翟中媛,李焕龙.330 MW燃准东煤电站锅炉烟气沿程灰沉积特性研究[J].中国电机工程学报,2017,37(21):6373-6380.(WANG Yong-zhen,JIN Jing,LIU Dun-yu,YANG Hao-ran,ZHAI Zhong-yuan,LI Huan-long.Characterization of ash deposits along the flue gas for Zhundong coal combustion in a 330mw boiler[J].Proc CSEE,2017,37(21):6373-6380.)
[20]杨少波,宋国良,宋维健,齐晓宾.不同反应气氛下准东高钠煤中钠的迁移转化与积灰特性[J].燃料化学学报,2016,44(9):1051-1058.(YANG Shao-bo,SONG Guo-liang,SONG Wei-jian,QI Xiao-bin.Transformation and deposition characteristics of sodium in Zhundong high sodium coal under different reaction atmospheres[J].J Fuel Chem Technol,2016,44(9):1051-1058.)
[21]LAWRENCE A,KUMAR R,NANDAKUMAR K,NARAYANAN K.A Novel tool for assessing slagging propensity of coals in PF boilers[J].Fuel,2008,87(6):946-950.
[22]GUPTA S K,WALL T F,CREELMAN R A,GUPTA R P.Ash fusion temperatures and the transformations of coal ash particles to slag[J].Fuel Process Technol,1998,56(1/2):33-43.
[23]YAN T G,KONG L X,BAI J,BAI Z Q,LI W.Thermomechanical analysis of coal ash fusion behavior[J].Chem Eng Sci,2016,147:74-82.
[24]KIM J H,KIM G B,JEON C H.Prediction of correlation between ash fusion temperature of ASTM and thermo-mechanical analysis[J].Appl Therm Eng,2017,75(9):1218-1228.
[25]QI X B,SONG G L,YANG S B,YANG Z,LYU Q G.Exploration of effective bed material for use as slagging/agglomeration preventatives in circulating fluidized bed gasification of high-sodium lignite[J].Fuel,2018,217:577-586.
[26]KYI S,CHADWICK B L.Screening of potential mineral additives for use as fouling preventatives in Victorian brown coal combustion[J].Fuel,1999,78(7):845-855.
[27]周永刚,范建勇,李培,王炳辉,赵虹.高碱金属准东煤灰熔融过程的矿物质衍变[J].浙江大学学报(工学版),2015,49(8):1559-1564.(ZHOU Yong-gang,FAN Jian-yong,LI Pei,WANG Bing-hui,ZHAO Hong.Mineral transmutation of high alkali Zhundong coal in ash melting process[J].J Zhejiang Univ(Eng Sci),2015,49(8):1559-1564.)
[28]WANG Y Z,JIN J,LIU D Y,YANG H R,LI S J.Understanding ash deposition for the combustion of Zhundong coal:Focusing on different additives effects[J].Energy Fuels,2018,32(6):7103-7111.
[29]FREYER D,VOIGT W,KOHNKE K.The phase diagram of the system Na2SO4-CaSO4[J].Eur J Sol State Inor,1998,35(s1/11):595-606.
[30]SONG G L,YANG S B,SONG W J,QI X B.Release and transformation behaviors of sodium during combustion of high alkali residual carbon[J].Appl Therm Eng,2017,122:285-296.
[2]张守玉,陈川,施大钟,吕俊复,王健,郭熙,董爱霞,熊绍武.高钠煤燃烧利用现状[J].中国电机工程学报,2013,33(5):1-12.(ZHANG Shou-yu,CHEN Chuan,SHI Da-zhong,LV Jun-fu,WANG Jian,GUO Xi,DONG Ai-xia,XiONG Shao-wu.Situation of combustion utilization of high sodium coal[J].Proc CSEE,2013,33(5):1-12.)
[3]WANG X B,XU Z X,WEI B,ZHANG L,TAN H Z,YANG T,MIKULCIC H,DUIC N.The ash deposition mechanism in boilers burning Zhundong coal with high contents of sodium and calcium:A study from ash evaporating to condensing[J].Appl Therm Eng,2015,80:150-159.
[4]SONG G L,SONG W J,QI X B,LU Q G.Transformation characteristics of sodium of zhundong coal combustion/gasification in circulating fluidized bed[J].Energy Fuels,2016,30(4):3473-3478.
[5]TOMECZEK J,PALUGNIOK H,OCHMAN J.Modelling of deposits formation on heating tubes in pulverized coal boilers[J].Fuel,2004,83(2):213-221.
[6]GLARBORG P,MARSHALL P.Mechanism and modeling of the formation of gaseous alkali sulfates[J].Combust Flame,2005,141(1/2):22-39.
[7]ZHOU H,ZHOU B,ZHANG H,LI L,CEN K.Investigation of slagging characteristics in a 300 kW test furnace:Effect of deposition surface temperature[J].Ind Eng Chem Res,2014,53(17):7233-7246.
[8]WU X J,ZHANG X,YAN K,CHEN N,ZHANG J W,XU X Y,DAI B Q,ZHANG J,ZHANG L.Ash deposition and slagging behavior of Chinese Xinjiang high-alkali coal in 3 M W th pilot-scale combustion test[J].Fuel,2016,181:1191-1202.
[9]杨涛,李文广,吴莎,张兰,王学斌,谭厚章.新疆高钙钠煤燃烧设备结焦机理研究[J].燃料化学学报,2015,43(11):1320-1326.(YANG Tao,LI Wen-guang,WU Sha,ZHANG Lan,WANG Xue-bin,TAN Hou-zhang.Study on fouling mechanism in a boiler burning Xinjiang coal with high content of calcium and sodium[J].J Fuel Chem Technol,2015,43(11):1320-1326.)
[10]魏博,谭厚章,王学斌,胡中发,王毅斌,阮仁晖.准东煤灰沉积与无机元素迁徙特性研究[J].工程热物理学报,2016,37(8):1783-1788.(WEI Bo,TAN Hou-zhang,WANG Xue-bin,HU Zhong-fa,WANG Yi-bin,RUAN Ren-hui.Ash deposition and inorganic element transformation during zhundong coal combustion[J].J Eng Thermophys,2016,37(8):1783-1788.)
[11]WEI B,TAN H Z,WANG Y B,WANG X B,YANG T,RUAN R H.Investigation of characteristics and formation mechanisms of deposits on different positions in full-scale boiler burning high alkali coal[J].Appl Therm Eng,2017,119:449-458.
[12]LI G D,LI S Q,HUANG Q,YAO Q.Fine particulate formation and ash deposition during pulverized coal combustion of high-sodium lignite in a dow n-fired furnace[J].Fuel,2015,143(44):430-437.
[13]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 gasification condition[J].J Fuel Chem Technol,2016,44(3):263-272.)
[14]韩克鑫,黄镇宇,王智化,周俊虎.准东煤灰渣烧结熔融过程中钠基化合物作用机理研究[J].燃料化学学报,2015,43(1):22-26.(HAN Ke-xin,HUANG Zhen-yu,WANG Zhi-hua,ZHOU Jun-hu.Action mechanism of sodium compounds in Zhundong coal ash on the process of sintering and fusion[J].J Fuel Chem Technol,2015,43(1):22-26.)
[15]QI X B,SONG G L,SONG W J,LU Q G.Influence of sodium-based materials on the slagging characteristics of Zhundong coal[J].JEnergy Inst,2016,90(6):914-922.
[16]陈衡,王云刚,马海东,赵钦新.循环流化床锅炉燃用准东煤结渣、沾污分析[J].热能动力工程,2015,30(3):431-435.(CHEN Heng,WANG Yun-gang,MA Hai-dong,ZHAO Qin-xin.Analysis and Study of the Slagging and Contamination of a CFB Boiler Burning Zhundong-originated Coal[J].J Eng Therm Energy Power,2015,30(3):431-435.)
[17]王礼鹏,赵永椿,张军营,姚斌,郑楚光.准东煤沾污结渣特性研究[J].工程热物理学报,2015,36(6):1381-1385.(WANG Li-peng,ZHAO Yong-chun,ZHANG Jun-ying,YAO Bin,ZHENG Chu-guang.Research on the slagging and fouling characteristics of Zhundong coal[J].J Eng Thermophys,2015,36(6):1381-1385.)
[18]杨光,张彦威,寇希文,周志军,王智化,周俊虎,岑可法.燃用准东煤电站锅炉灰沉积形成过程中的矿物演变与热力学模拟[J].燃料化学学报,2015,43(10):1182-1187.(YANG Guang,ZHANG Yan-wei,KOU Xi-wen,ZHOU Zhi-jun,WANG Zhi-hui,ZHOU Jun-hu,CEN Ke-fa.Mineral conversion and thermodynamic simulation of ash deposition during Zhundong coal combustion in boiler of thermal power plant[J].J Fuel Chem Technol,2015,43(10):1182-1187.)
[19]王永贞,金晶,刘敦禹,杨浩然,翟中媛,李焕龙.330 MW燃准东煤电站锅炉烟气沿程灰沉积特性研究[J].中国电机工程学报,2017,37(21):6373-6380.(WANG Yong-zhen,JIN Jing,LIU Dun-yu,YANG Hao-ran,ZHAI Zhong-yuan,LI Huan-long.Characterization of ash deposits along the flue gas for Zhundong coal combustion in a 330mw boiler[J].Proc CSEE,2017,37(21):6373-6380.)
[20]杨少波,宋国良,宋维健,齐晓宾.不同反应气氛下准东高钠煤中钠的迁移转化与积灰特性[J].燃料化学学报,2016,44(9):1051-1058.(YANG Shao-bo,SONG Guo-liang,SONG Wei-jian,QI Xiao-bin.Transformation and deposition characteristics of sodium in Zhundong high sodium coal under different reaction atmospheres[J].J Fuel Chem Technol,2016,44(9):1051-1058.)
[21]LAWRENCE A,KUMAR R,NANDAKUMAR K,NARAYANAN K.A Novel tool for assessing slagging propensity of coals in PF boilers[J].Fuel,2008,87(6):946-950.
[22]GUPTA S K,WALL T F,CREELMAN R A,GUPTA R P.Ash fusion temperatures and the transformations of coal ash particles to slag[J].Fuel Process Technol,1998,56(1/2):33-43.
[23]YAN T G,KONG L X,BAI J,BAI Z Q,LI W.Thermomechanical analysis of coal ash fusion behavior[J].Chem Eng Sci,2016,147:74-82.
[24]KIM J H,KIM G B,JEON C H.Prediction of correlation between ash fusion temperature of ASTM and thermo-mechanical analysis[J].Appl Therm Eng,2017,75(9):1218-1228.
[25]QI X B,SONG G L,YANG S B,YANG Z,LYU Q G.Exploration of effective bed material for use as slagging/agglomeration preventatives in circulating fluidized bed gasification of high-sodium lignite[J].Fuel,2018,217:577-586.
[26]KYI S,CHADWICK B L.Screening of potential mineral additives for use as fouling preventatives in Victorian brown coal combustion[J].Fuel,1999,78(7):845-855.
[27]周永刚,范建勇,李培,王炳辉,赵虹.高碱金属准东煤灰熔融过程的矿物质衍变[J].浙江大学学报(工学版),2015,49(8):1559-1564.(ZHOU Yong-gang,FAN Jian-yong,LI Pei,WANG Bing-hui,ZHAO Hong.Mineral transmutation of high alkali Zhundong coal in ash melting process[J].J Zhejiang Univ(Eng Sci),2015,49(8):1559-1564.)
[28]WANG Y Z,JIN J,LIU D Y,YANG H R,LI S J.Understanding ash deposition for the combustion of Zhundong coal:Focusing on different additives effects[J].Energy Fuels,2018,32(6):7103-7111.
[29]FREYER D,VOIGT W,KOHNKE K.The phase diagram of the system Na2SO4-CaSO4[J].Eur J Sol State Inor,1998,35(s1/11):595-606.
[30]SONG G L,YANG S B,SONG W J,QI X B.Release and transformation behaviors of sodium during combustion of high alkali residual carbon[J].Appl Therm Eng,2017,122:285-296.