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

Abstract

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 , 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) controlled by nucleation and nuclei growth models is the most probable reaction model of char combustion.

Kinetic study on the CO2 gasification of biochar derived from Miscanthus at different processing conditions

“…The determination of E was a function of x, without assuming the reaction model. As the most common iso-conversional method, Fitlun-Wall-Ozawa (FWO) was used to derive the E value of the x from 0.1 to 0.9 [31]:…”

Comparative study of historical woods from XIX century by thermogravimetry coupled with FTIR spectroscopy

“…Among the integral isoconversional procedures, the Kissinger−Akahira−Sunose (KAS) method was selected. Literature reports that the KAS method is suitable to investigate the wood pyrolysis (Slopiecka et al 2012;Azizi et al 2017), the combustion reaction of low-rank coal char (Hu et al 2018) and the thermal decomposition of natural polymers (Makaremi et al 2017;Bertolino et al 2018). The KAS method can be expressed as ln(T 2 ) = ln(AR/Eag()) -Ea/RT 3where A and R are the pre-exponential factor and gas constant, respectively, while g(α) represents the integral conversion function.…”

Inhibiting effect of CO2 on the oxidative combustion thermodynamics of coal

“…But previous publications have focused on the characteristics of coal oxidation and combustion, and relevant experimental techniques such as thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) have been increasingly used. [10][11][12] Rotaru et al 13 discovered that different types of coal demonstrated different apparent activation energies in the process of spontaneous combustion. Deng et al 14 determined that a large difference in activation energy existed between the oxidation and combustion stages.…”