(295e) Reaction Kinetics of Coal Gasification with the N2/O2/CO2 Mixture

The combustion characteristics of Datong coal in the different N2/O2/CO2 environments have been extensively studied by using thermo-gravimetric technique. The effects of combustion environment, oxygen and CO2 concentrations, particle size and different heating rates were considered. Results show that the coal pyrolysis in CO2 environment can be divided into three stages: moisture release, devolatilization and char gasification by CO2 at higher temperature zone. In the lower temperature zone, the mass loss rate of coal pyrolysis in CO2 environment is higher than that in N2 environment and the burning process of coal in O2/CO2 environment is almost same compared with that in O2/N2 environment for equivalent oxygen concentrations but slightly lesser than O2/N2 environment. With the increase of oxygen concentration, the burning rate of coal increases and burnout time is shortened. As the heating rate increases, coal particles are faster heated in a short period of time and burnt in a higher temperature region, but the increase in heating rate has almost no obvious effect on the combustion mechanism of coal. Applying different methods, values of the Arrhenius activation energy E and pre-exponentional factor A were estimated from the TGA data obtained via heating samples at different heating rates. A decrease of activation energy values were observed with the increase of different heating rates.