文献类型：会议论文

英文题名：Methane production by hydrogenation of low-rank coal in a fixed-bed reactor

作者：Zhang, Jie[1]; Ding, Haoran[1]; Wang, Jie[1]

机构：[1] Department of Chemical Engineering for Energy, Key Laboratory of Coal Gasification and Energy Chemical Engineering, East China University of Science and Technology, 130 # Meilong Road, Shanghai 200237, China

会议论文集：30th Annual International Pittsburgh Coal Conference 2013, PCC 2013

会议日期：September 15, 2013 - September 18, 2013

会议地点：Beijing, China

语种：英文

外文关键词：Carbon dioxide - Tar - Bituminous coal - Hydrogenation - Lignite - Chemical reactors - Hydrogen - Economic and social effects

摘要：The aim of this paper is to investigate the hydrogasification characteristics of three low rank coals in a fixed-bed reactor, focusing on the production of methane. Coal hydrogasification experiments were carried out at a heating rate of 15 °C/min up to 700 °C with a holding time of 1 hour under various hydrogen pressures up to 5 MPa. It was observed that the coal hydrogasification was clearly characteristic of a two-stage process, volatile matter hydrogenation occurring in the heat-up stage and char hydrogasification occurring mainly in the isothermal stage. The accumulated yields of methane obtained under hydrogen of 5 MPa were 4.7, 4.0 and 1.4 times as much as those under that of 0.1 MPa, respectively, for YX lignite, ZD subbituminous coal, and XD lignite. An elevation in hydrogen pressure not only facilitated the char hydrogasification but also the volatile matter hydrogenation reactions. The promoted hydrogenation reactions by pressure were also due to the significantly increased residence time of volatile matter in the reactor. Analysis of the tar composition indicated that the tar obtained at ambient hydrogen pressure contained more of long alkyl chain hydrocarbons and larger polyaromatics, whereas that obtained at 5 MPa was enriched with benzene, toluene, and xylene (BTX), reflective of the facilitated decomposition of volatile matter under pressure. The formation of CO decreased with hydrogen pressure increasing, indicating its hydrogenation reaction to turn to carbon or CH4. The change of CO2 with pressure was not a monotonous trend, implying the trade-offs of some competition reactions. The char hydrogasification rate was essentially proportional to the hydrogen pressure, but depending on coals. ZD sub-bituminous coal demonstrated a higher rate of char hydrogasification. Elemental analysis of the char collected after gasification showed that the char obtained at 5 MPa had a higher H/C molar ratio and a lower N/C molar ratio than that obtained at ambient pressure. The kinetics of hydrogenated chars showed increased pressure and long solid residence time would decrease the char reactivity towards CO2.