Kinetic Analysis of Low-Rank Coal Pyrolysis by Model-Free and Model-Fitting Methods

Abstract

Coal SJC, coal WJG, coal ZJM, and coal HCG were selected to investigate the pyrolysis kinetics of northern Shaanxi coals. TG and DSC experiments of four coals were carried out with a synchronous thermal analyzer at heating rates 5, 10, 15, and 20 C/min, respectively. The pyrolysis characteristics were described by thermogravimetric data, and the kinetic parameters were calculated by Flynn–Wall–Ozawa (FWO), Kissinger, general integration, and MacCallum–Tanner methods. The results show that coal SJC, coal ZJM, and coal HCG all conform to the reaction series equation, the thermal decomposition reaction rate is controlled by chemical reaction, and coal WJG conforms to Avrami–Erofeev equation. The activation energies of the four coals are 177.53 kJ/mol, 200.34 kJ/mol, 158.59 kJ/mol, and 240.47 kJ/mol, respectively.