REACTION RATE OF MICROWAVE PYROLYSIS OF COAL IN CHAR BED

A subbituminous coal mixed with mild gasification char was pyrolyzed in a microwave reactor of 2.4 5 GHz and power input varying from 4 50 to 650 W. Gas evolution was observed immediately after microwave energy was applied to the mixture. Data obtained from the tests are analyzed to estimate coal pyrolysis kinetic parameters. A reaction order of 1.75 was found to best fit the experimental data. Both an activation energy and reaction rate constant are found to be essentially dependent on the amount of coal content in the mixture. There is a clear trend of an activation energy increase and reaction rate constant decrease with the change of coal concentration in mixtures from 30 to 60 %, Due to the presence char, an activation energy of coal pyrolysis in the microwave reactor was reduced from one-third to one-fourth of that known for the conventional method. This reduction in activation energy is one of the major reasons for the enhancement of coal pyrolysis by microwave energy.