Kinetics of coal combustion under oxyfuel conditions

A very large number of papers have been carried out to measure the rate of char conversion under combustion and gasification conditions, involving a variety of coal and char types, as well as different experimental techniques, ranging from TGA to wire mesh reactor and drop tube furnaces. For sake of simplicity power law kinetic expressions have often been used to describe the kinetics of carbon gasification with O2, CO2, H2O and H2, although it has been clarified that some features can be explained only by more complex kinetic schemes. In the present paper the rate of carbon conversion in O2/CO2 mixtures typical of oxyfuel conditions is investigated by conventional as well as innovative experimental techniques, namely isothermal and non isothermal thermogravimetric analysis and reaction in an aerodynamic levitated particle reactor (ALPR), a particular apparatus that is able to suspend fine coal particles in a upward flow of gas of given temperature and composition. Results obtained by the different experimental techniques are compared and analysed in the frame of a series-parallel reaction network and the possibility to obtain reliable kinetic rate expressions for oxyfuel combustion of coal char is discussed