Fast pyrolysis and combustion characteristic of three different brown coals

Abstract

In this study, brown coals fast pyrolysis/combustion was carried out in a moving furnace coupled with a balance, and the mass change of sample and emission of hydrocarbon components were online recorded. On the basis of the experimental results, the pyrolysis/combustion kinetic parameters were calculated. In the fast pyrolysis process, the apparent activation energy of Loy Yang brown coal, Wara brown coal and Usibelli brown coal was 36.9, 33.1 and 28.1 kJ/mol respectively, which was far lower than that obtained under the slow pyrolysis process. The main light hydrocarbon gases evolved from brow coal fast pyrolysis were CH4, C2H6 and C3H8. At the same time, it was found that the reaction rate of brown coal fast pyrolysis was strongly influenced by the oxygen content of the raw coal. The high oxygen content of the raw coal was beneficial to pyrolytic reaction. The combustion process of the brown coal could be divided two stages: in the first stage, the evolution and combustion of volatile matter occurred simultaneously. In the secondary stage, only char combustion occurred. The apparent activation energy of char combustion was 2.3–20.8 kJ/mol.