KINETICS OF CALCINATION OF OIL COKE IN NEUTRAL AND OXIDIZING ATMOSPHERES

A devolatilization kinetic study of oil coke samples under conditions close to those of industrial calcination furnace is presented. The effects of the surrounding conditions (neutral or oxydizing medium), the heating rate and the percentage of oxygen in an oxydizing environment are analyzed. Experiments are carried out in an induction oven and involved thermogravimetric and chromatographic analyses. Results show that, under certain conditions, the nature of the environment influence the devolatilization process. A slow heating rate and a low content in volatiles promote the coke degradation by oxygen in an oxydizing medium. The reactive schemes are derived by tracking the concentration of CH4, H-2, CO and CO2. In regions where the coke is not degraded, a kinetic model is used to compare the parameters describing the develotilization phenomena in the two media (neutral and oxydizing), i.e.: the reaction order, the activation energy and the pre-exponential factor. It is shown that the oxydizing medium promotes an increase in the activation energy.