KINETIC STUDY OF DIRECT COAL LIQUEFACTION

摘要

Direct coal liquefaction is an advantageous approach for coal utilization cleanly and effectively. And it was usually carried out at a temperature higher than 400 ℃ and high pressure. The kinetics study of coal liquefaction plays an important role for reactor design and process optimization, but it is very complex due to different rank, different petrographic composition, as well as different mineral components of coal. Govlndan et.al. found that several kinetic models can predict concentration-time profiles satisfactorily through studying the kinetics of Illinois No. 6 coal liquefaction in a batch reactor under non-isothermal conditions[1]. Ikeda et.al. have investigated the procedure of coal liquefaction in a flow reactor of 1 t/d Process Supporting Unit (PSU) for the NEDOL process, and a reaction kinetic model of coal liquefaction with retrogressive reaction was established and the mechanism was elucidated[2]. Ding et.al. [3] have made a kinetic study of thermal and catalytic (Fe impregnated on coal) liquefaction of DECS-6 coal with plastic-derived liquids (PDL) as solvent. It was found that direct coal liquefaction was predominant for both thermal and catalytic effect with PDL as solvent, although the catalyst promotes consecutive reactions to a larger extent. Generally, different rank, different petrographic composition and different mineral components of coal means different kinetic modal and mechanism at the same liquefaction condition [4]. In this work, Shenhua bituminous coal, loaded with iron catalyst, was liquefied in a 500 ml autoclave with cycle oil as solvent, the kinetic models were developed at heating and isothermal stages respectively, and the reaction rate constants at two stages were estimated.