Non-isothermal TGA study on the combustion reaction kinetics and mechanism of low-rank coal char

摘要

In this paper, the combustion reaction kinetics of pyrolysis char of low-rank coal is studied by thermal analysis technology. For the combustion process of the char at different heating rates, the reaction kinetic parameters were calculated by three common mode-free methods (FWO method, KAS method and Starink method); the reaction model was determined by Malek method and Popescu method. Research shows that activation energy E _( α ) of char combustion calculated by the three methods was 110.66–70.31 kJ mol ~(?1) , 104.35–59.60 kJ mol ~(?1) and 104.34–59.99 kJ mol ~(?1) , respectively, and the activation energy decreased with increasing conversion rates. There is a compensation effect between the activation energy and pre-exponential factor of char combustion. Results of the kinetic analysis by Malek method and Popescu method both indicated that the Avrami–Erofeev equation ( n = 3/2) ( f ( α ) = 3/2(1 ? α )[?ln(1 ? α )] ~(1/3) ) controlled by nucleation and nuclei growth models is the most probable reaction model of char combustion.