Thermogravimetric-gas chromatographic study on effects of hydrogen pressure on coal hydrogenation
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摘要: 采用加压热重分析仪和气相色谱仪联用的方法研究了府谷烟煤和海拉尔褐煤加氢反应过程中的失重规律和主要气体产物析出规律,升温速率15℃/min,压力0.1~5.0MPa,反应终温1000℃。实验结果表明,煤粉加氢反应主要分为初始干燥脱气、热分解及挥发分加氢,半焦加氢气化和焦炭加氢气化四个阶段。氢气压力的提高促进了挥发分自由基的加氢反应,抑制了含氧官能团脱除形成碳氧化物。在热分解及挥发分加氢阶段,府谷烟煤失重速率随氢气压力的升高而减小,氢气压力对海拉尔褐煤失重速率的影响不大。在半焦加氢气化阶段,CH4生成速率随氢气压力的升高而增大,当氢气压力较高时(3~5MPa),海拉尔褐煤CH4生成速率随氢气压力的升高不再增大。海拉尔褐煤Odaf较高,其半焦中含氧官能团提供的活性位较多。府谷烟煤H/C原子比较高,能提供更多的内部氢。府谷烟煤和海拉尔褐煤焦炭加氢反应动力学参数分别为k0=2.38×107 (min-1·MPa-1),E=231kJ/mol,n=1和k0=2.64×103 (min-1·MPa-0.736),E=127kJ/mol,n=0.736。Abstract: Thermogravimetric characteristics and evolution of main gaseous products during hydrogenation of two coals were studied in a thermogravimetry-gas chromatography combined system at 15℃/min, 0.1~5MPa and a final temperature of 1000℃. The results show that the hydrogenation process occurs in four stages: drying and degassing, hydropyrolysis, rapid hydrogasification, and slow hydrogasification. With increasing hydrogen pressure, hydrogenation of volatile radicals is promoted and decomposition of oxygen-containing functional groups forming carbon oxides is inhibited. During hydropyrolysis stage, the weight loss rate increases with hydrogen pressure for FG coal, while the hydrogen pressure has little influence on that for HLE coal. During the rapid hydrogasification stage, the evolution rate of CH4 increases with hydrogen pressure; for HLE coal the evolution rate of CH4 doesn't increase with hydrogen pressure any more at high pressures (3~5MPa). The HLE coal with higher oxygen content contains more active sites provided by the oxygen-containing groups in the semi-char. The FG coal with higher H/C atomic ratio is able to provide more hydrogen by itself during hydrogenation reactions. The kinetic data of the slow hydrogasification stage is k0=2.38×107 (min-1·MPa-1), E=231kJ/mol, n=1 for the FG coal and k0=2.64×103 (min-1·MPa-0.736), E=127kJ/mol, n=0.736 for the HLE coal.
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Key words:
- hydropyrolysis /
- hydrogasification /
- pressure /
- thermogravimetric analysis
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STEINBERG M. Process for conversion of coal to substitute natural gas (SNG). New York: HCE, LLC, 2005. ANTHONY D B, HOWARD J B. Coal devolatilization and hydrogasification[J]. AIChE J, 1976, 22(4): 625-656. JUNTGEN H. Review of the kinetics of pyrolysis and hydropyrolysis in relation to the chemical constitution of coal[J]. Fuel, 1984, 63(6): 731-737. 李保庆. 煤加氢热解研究Ⅰ.宁夏灵武煤加氢热解的研究[J]. 燃料化学学报, 1995, 23(1): 57-61. (LI Bao-qing. Hydropyrolysis of Chinese coals I. Hydropyrolysis of lingwu bituminous coal[J]. J Fuel Chem Technol, 1995, 23(1): 57-61.) BLACKWOOD J D. The reaction of carbon with hydrogen at high pressure[J]. Aust J Chem, 1959, 12(1): 14-28. MISIRLIOGLU Z, CANEL M, SINAG A. Hydrogasification of chars under high pressures[J]. Energy Convers Manage, 2007, 48(1): 52-58. 陈皓侃, 李保庆, 张碧江. 反应条件对煤加氢热解产物分布的影响[J]. 燃料化学学报, 1997, 25(1): 50-55. (CHEN Hao-kan, LI Bao-qing, ZHANG Bi-jiang. Effects of reaction parameters on product yields during coal hydropyrolysis[J]. J Fuel Chem Technol, 1997, 25(1): 50-55.) XU W C, MATSUOKA K, AKIHO H, KUMAGAI M, TOMITA A. High pressure hydropyrolysis of coals by using a continuous free-fall reactor[J]. Fuel, 2003, 82(6): 677-685. GUELL A J, KANDIYOTI R. Development of a gas-sweep facility for the direct capture of pyrolysis tars in a variable heating rate high-pressure wire-mesh reactor[J]. Energy Fuels, 1993, 7(6): 943-952. 虞继舜. 煤化学[M]. 北京: 冶金工业出版社, 2000. (YU Ji-shun. Coal chemistry[M]. Beijing: Metallurgical Industry Press, 2000.) YU J, LUCAS J A, WALL T F. Formation of the structure of chars during devolatilization of pulverized coal and its thermoproperties: A review[J]. Prog Energy Combust Sci, 2007, 33(2): 135-170. DING X, ZHANG Y, ZHANG T, TANG J, XU Y, ZHANG J. Effect of operational variables on the hydrogasification of inner mongolian lignite semicoke[J]. Energy Fuels, 2013, 27(8): 4589-4597. XU W C, KUMAGAI M. Nitrogen evolution during rapid hydropyrolysis of coal[J]. Fuel, 2002, 81(18): 2325-2334. XU W C, KUMAGAI M. Sulfur transformation during rapid hydropyrolysis of coal under high pressure by using a continuous free fall pyrolyzer[J]. Fuel, 2003, 82(3): 245-254. ZHANG J, WANG X, WANG F, WANG J. Investigation of hydrogasification of low-rank coals to produce methane and light aromatics in a fixed-bed reactor[J]. Fuel Process Technol, 2014, 127(0): 124-132. GARDNER N, SAMUELS E, WILKS K. Catalyzed hydrogasification of coal chars[J]. Adv Chem Ser, 1974, 131: 217-236. TOMITA A, MAHAJAN O P, WALKER JR P L. Reactivity of heat-treated coals in hydrogen[J]. Fuel, 1977, 56(2): 137-144. LI S, SUN R. Kinetic studies of a lignite char pressurized gasification with CO2, H2 and steam[J]. Fuel, 1994, 73(3): 413-416. GONZALEZ J F, RAMIRO A, SABIO E, ENCINAR J M, GONZALEZ C M. Hydrogasification of almond shell chars. Influence of operating variables and kinetic study[J]. Ind Eng Chem Res, 2002, 41(15): 3557-3565.
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