Thermogravimetric study on gasification kinetics of hydropyrolysis char derived from low rank coal

摘要

Hydropyrolysis char plays a very important role in the clean and comprehensive utilization of low rank coal. The gasification behaviors of four hydropyrolysis chars (HMC,SMTC,SMC,YYC) derived from low rank coal under CO2 atmosphere were studied using the thermogravimetric analysis method. The chemical components as well as the physical properties of the different samples were examined by scanning electron microscopy (SEM), N-2 adsorption and Raman spectroscopy. The results show that the gasification curves have similar tendencies in the case of all four hydropyrolysis chars. When the heating rate increases, the gasification curve moves to the high temperature zone and the peak value of the gasification rate increases. The gasification performance from good to bad is in the sequence of YYC, SMTC, SMC, HMC. Chemical contents and physical structure analyses show that the carbonaceous structure has a major impact upon the gasification performance of the hydropyrolysis chars. The Raman spectrum shows that the gasification performance improves with the increase of ID3-D4/I-G. The single-step glob model (SSGM) is applied to obtain the dependence of activation energy on conversion. SSGM can represent the hydropyrolysis behavior well. The activation energies for the hydropyrolysis chars lie in the range of 265.2-284.5 kJ/mol. (C) 2019 Elsevier Ltd. All rights reserved.