Abstract:
The reactivity of using Fe
2O
3 as an oxygen carrier during chemical-looping combustion (CLC) of coal has been investigated experimentally at 800℃~950℃. The experiments were carried out in a fluidized bed, where the steam acted as the gasificationfluidization medium. The reactivity of Fe
2O
3 as a function of the reactor temperature, reaction time, and cyclic reduction number was discussed. The reactivity of Fe
2O
3 oxygen carriers was enhanced as temperature increased at 800℃~950℃. Moreover, the time of chemical reaction control between the oxygen carrier and coal gasification products decreased with increased reaction temperature. When the reaction temperature was above 900℃, the rate of carbon to form CO
2 was higher than 90%; however, it was lower than 75% below 850℃. At 900℃, the dry basis concentration of CO
2 decreased with increased cyclic reduction period, while that of CO and CH
4 increased. Moreover, the value of the CO concentration was less than that of CH
4. The performance of the reacted Fe
2O
3-based oxygen carriers was also evaluated using an X-ray diffractometer and a scanning electron microscope to characterize the solid residues of oxygen carrier. The results show that Fe
2O
3-based oxygen carriers are only reduced to Fe
3O
4. With the increase of cyclic reduction period, the oxygen carrier sinters gradually.