NO_x release in chemical looping combustion of biomass based on hematite

Nitrogen emission during chemical looping combustion (CLC) of rice husk based on hematite in a batch fixed bed reactor was studied. Different variables affecting the process, such as reduction temperature and steam content, were tested. The results show that higher reduction temperature results in a higher carbon conversion which reaches the highest value when the steam flow is 1.0 g/min. Furthermore, there are no NO₂ detected at all experiments. The rise of reduction temperature from 750 to 900 ℃ could contribute to the rise of NO, whereas the concentration of N₂O reaches the highest value at 850 ℃. Both N₂O and NO increase remarkably with the increase of steam flow. Nevertheless, the increasing rate of NO is faster than that of N₂O. Besides, KAlSi₃O₈ is detectable in the reduced oxygen carrier, attributing to the reaction of K in biomass with hematite.