白石湖煤不同密度级组分热解特性
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摘要
高碱煤直接燃烧/气化过程呈现严重的沾污和结渣等问题限制了新疆地区高碱煤大规模利用。煤热解分质利用技术不具备发生沾污和结渣的高温与氧化气氛,应用前景广阔。如何提高热解油气的收率和品质是高碱煤分质利用研究的重要方向,通过分选可实现高油产率组分富集的同时降低钠钙等碱和碱土金属的不利影响。笔者利用有机重液对富镜质组白石湖煤进行浮沉-离心分离,采用傅里叶红外光谱对不同密度级组分表面官能团进行表征,利用热重分析仪和格金低温干馏试验装置研究了热解特征参数和动力学参数变化规律和热解产物分布规律。结果表明,白石湖煤不同密度级组分氢含量与H/C原子比均先降低后增加,氧含量和O/C原子比逐渐增加。—OH官能团主要为羧酸官能团和酚羟基,在中密度级相对富集。随密度级增加,最大质量变化速率和失重率均逐渐降低,活化能和指前因子均呈先降低后升高趋势;焦油产率先降低后升高:BS_(<1. 3)焦油产率高达25. 25%,BS_(>1. 6)焦油产率与BS_(1. 3-1. 4)相当,约为15%。黏土矿物结晶水析出导致BS_(>1. 6)具有最高的水产率。
The serious fouling and slagging derived from direct combustion or gasification of high-alkali-coal limit the large-scale utilization of high-alkali-coal in Xinjiang area.The technology of coal grading pyrolysis does not have the conditions of high temperature and oxidizing atmosphere to trigger fouling and slagging problems,so it has broad application prospects.How to improve the yield and quality of oil and gas during coal pyrolysis is an important direction of research on the utilization of high alkali coal.With coal separation,the components of high oil yield can be concentrated and the adverse effects of alkali and alkaline earth metals( such as sodium and calcium) can also be reduced.In the paper,the vitrinite-rich coal in Baishihu with different density grades was separated by flotation and centrifugation with heavy organic liquid.Fourier infrared spectrum was used to characterize the surface functional groups of different density-level components.In addition,the thermogravimetric analyzer and Gray assay were used to study the change rule of pyrolysis characteristic parameters and dynamics parameters,and the distribution of pyrolysis products.The results show that for the components of Baishihu coal with different density grades,the hydrogen content and the H/C atomic ratio decrease first and then increase,while the oxygen content and O/C atomic ratio increase gradually.The functional groups of —OH are mainly carboxylic acid functional groups and phenolic hydroxyl groups,which are relatively enriched at the medium density fractions.With the increase of density level,the maximum pyrolysis rate and the rate of weight loss decrease gradually,and the activation energy and pre-exponential factors decrease first and then increase.The tar yield first decreases and then increases: the tar yield of BS_(<1. 3) is as high as 25.25% and BS_(>1. 6) is equivalent to that of BS_(1. 3-1. 4),about 15%.The vaporization of crystal water in clay minerals results in the highest moisture yield for BS_(>1. 6).
The serious fouling and slagging derived from direct combustion or gasification of high-alkali-coal limit the large-scale utilization of high-alkali-coal in Xinjiang area.The technology of coal grading pyrolysis does not have the conditions of high temperature and oxidizing atmosphere to trigger fouling and slagging problems,so it has broad application prospects.How to improve the yield and quality of oil and gas during coal pyrolysis is an important direction of research on the utilization of high alkali coal.With coal separation,the components of high oil yield can be concentrated and the adverse effects of alkali and alkaline earth metals( such as sodium and calcium) can also be reduced.In the paper,the vitrinite-rich coal in Baishihu with different density grades was separated by flotation and centrifugation with heavy organic liquid.Fourier infrared spectrum was used to characterize the surface functional groups of different density-level components.In addition,the thermogravimetric analyzer and Gray assay were used to study the change rule of pyrolysis characteristic parameters and dynamics parameters,and the distribution of pyrolysis products.The results show that for the components of Baishihu coal with different density grades,the hydrogen content and the H/C atomic ratio decrease first and then increase,while the oxygen content and O/C atomic ratio increase gradually.The functional groups of —OH are mainly carboxylic acid functional groups and phenolic hydroxyl groups,which are relatively enriched at the medium density fractions.With the increase of density level,the maximum pyrolysis rate and the rate of weight loss decrease gradually,and the activation energy and pre-exponential factors decrease first and then increase.The tar yield first decreases and then increases: the tar yield of BS_(<1. 3) is as high as 25.25% and BS_(>1. 6) is equivalent to that of BS_(1. 3-1. 4),about 15%.The vaporization of crystal water in clay minerals results in the highest moisture yield for BS_(>1. 6).
引文
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[16]赵洪宇.难选铁矿石促进富油煤热解及铁矿物回收技术研究[D].北京:中国矿业大学(北京),2016.
[17] XU Ying,ZHANG Yongfa,ZHANG Guojie,et al.Low temperature pyrolysates distribution and kinetics of Zhaotong lignite[J].Energy Conversion and Management,2016,114:11-19.
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[19]赵云鹏.西部弱还原性煤热解特性研究[D].大连:大连理工大学,2010.
[20]孙庆雷,李文,李保庆.神木煤显微组分热解特性和热解动力学[J].化工学报,2002,53(11):1122-1127.SUN Qinglei,LI Wen,LI Baoqing.Pyrolysis of Shenmu coal macerals and kinetics analysis[J]. CIESC Journal,2002,53(11):1122-1127.
[2] LI J,ZHAUNG X,QUEROL X,et al.High quality of Jurassic coals in the Southern and Eastern Junggar coalfields,Xinjiang,NW China:Geochemical and mineralogical characteristics[J].International Journal of Coal Geology,2012,99:1-15.
[3] WANG J,CHEN F,ZHAO B,et al.Volatilisation and transformation behavior of sodium species at high temperature and its influence on ash fusion temperatures[J]. Fuel Processing Technology,2017,155:209-215.
[4] YANG Y,LIN X,CCHEN X,et al.The formation of deposits and their evolutionary characteristics during pressurized gasification of Zhundong coal char[J].Fuel,2018,224:469-480.
[5] STRUGNELL B,PATRICK J W. Rapid hydropyrolysis studies on coal and maceral concentrates[J].Fuel,1996,75:300-306.
[6]赵伟,张晓欠,周安宁,等.神府煤煤岩显微组分的浮选分离及富集物的低温热解产物特性研究[J].燃料化学学报,2014,42(5):527-532.ZHAO Wei,ZHANG Xiaoqian,ZHOU Anning,et al.Flotation separation of Shenfu coal macerals and low temperature pyrolys is characteristics of different maceral concentrate[J]. Journal of Fuel Chemistry and Technology,2014,42(5):527-532.
[7]朱川,曲思建,张凝凝,等.新疆白石湖富镜质组高碱煤热解特性[J].煤炭学报,2017,42(10):2725-2732.ZHU Chuan,QU Sijian,ZHANG Ningning,et al. Pyrolysis characteristics of Xinjiang Baishihu vitrinite-rich coal[J].Journal of China Coal Society,2017,42(10):2725-2732.
[8] ZHAO Yunpeng,HU Haoquan,JIN Lijun,et al.Pyrolysis behavior of vitrinite and inertinite from Chinese Pingshuo coal by TG-MS and in a fixed bed reactor[J]. Fuel Processing Technology,2011,92:780-786.
[9]林雄超,杨远平,徐荣声,等.新疆高碱煤分选组分中碱性矿物赋存及差异演化研究[J].燃料化学学报,2017,45(02):157-164.LIN Xiongchao,YANG Yuanping,XU Rongsheng,et al.Occurrence and transformation behavior of AAEMs in the flotation fraction of a typical Xinjiang coal[J].Journal of Fuel Chemistry and Technology,2017,45(2):157-164.
[10] LIU Z,GUO X,SHI Lei,et al.Reaction of volatiles-A crucial step in pyrolysis of coals[J].Fuel,2015,154:361-369.
[11] LEON Roets,CHRISTIEN A Strydom,JOHN R Bunta,et al.The effect of acid washing on the pyrolysis products derived from a vitrinite-rich bituminous coal[J].Journal of Analytical and Applied Pyrolysis,2015,116:142-151.
[12] SUN X,WANG G.A study of the kinetic parameters of individual macerals from Upper Permian coals in South China via opensystem pyrolysis[J].Int.J.Coal Geol.,2000,44:293-303.
[13]丁华,姜英,李文华.煤及其显微组分热解特性研究[J].煤质技术,2009,156(S1):1-5.DING Hua,JIANG Ying,LI Wenhua.Study on pyrolysis characteristics of coal and macerals[J]. Coal Quality Technology,2009,156(S1):1-5.
[14] ZHANG S,ZHU F,BAI C,et al.Thermal behavior and kinetics of the pyrolysis of the coal used in the COREX process[J]. Journal of Analytical and Applied Pyrolysis,2013,104:660-666.
[15]张军,袁建伟,徐益谦.低加热速度下显微组分的热解机理[J].燃料化学学报,1998,26(1):46-50.ZHANG Jun,YUAN Jianwei,XU Yiqian. Pyrolysis mechanism of macerals at a low heating rate[J]. Journal of Fuel Chemistry and Technology,1998,26(1):46-50.
[16]赵洪宇.难选铁矿石促进富油煤热解及铁矿物回收技术研究[D].北京:中国矿业大学(北京),2016.
[17] XU Ying,ZHANG Yongfa,ZHANG Guojie,et al.Low temperature pyrolysates distribution and kinetics of Zhaotong lignite[J].Energy Conversion and Management,2016,114:11-19.
[18] HIRSCHFELEDER J O.Semi-Empirical calculations of activation energies[J].The Journal of Chemical Physics,1941,9(8):645-654.
[19]赵云鹏.西部弱还原性煤热解特性研究[D].大连:大连理工大学,2010.
[20]孙庆雷,李文,李保庆.神木煤显微组分热解特性和热解动力学[J].化工学报,2002,53(11):1122-1127.SUN Qinglei,LI Wen,LI Baoqing.Pyrolysis of Shenmu coal macerals and kinetics analysis[J]. CIESC Journal,2002,53(11):1122-1127.