Evaluation of a self-sustaining ultra-rich H2-CO2-O2 premixed flame for potential application in CaCO3 hydrogenation

• An innovative method to reduce CO 2 based on the H 2 -CO 2 -O 2 premixed flame is proposed. • Ultra-rich H 2 -CO 2 -O 2 premixed flame feature is studied for the first time. • Conversion efficiency features of CO 2 at various operating conditions are studied. • Composition feature of the exhaust gas are investigated experimentally. • This work opens up new avenues for the efficient utilization of waste CO 2 emissions. Inorganic metallic carbonate (like CaCO 3 , MgCO 3 ) hydrogenation, i.e. , carbonate decomposition in a H 2 atmosphere, is emerging as a promising green route to address the high CO 2 emissions associated with traditional industrial processes, such as cement and refractory materials production. However, the substantial heat requirement in the carbonate hydrogenation process has been rarely explored. In this work, we propose introducing O 2 into the CaCO 3 hydrogenation system to enable autothermal operation. As the first step, we simplify the system by replacing CaCO 3 with CO 2 , focusing on the performance of a self-sustaining ultra-rich H 2 -CO 2 -O 2 premixed flame. The effects of volume percentages of CO 2 and O 2 ( X CO2 and X O2 ) on the flame behavior and conversion efficiency of CO 2 are investigated experimentally. It is observed that the stable cone-shaped flame height increases as the X CO2 value increases or the X O2 value decreases. The CO 2 conversion efficiency increases significantly as X O2 increases or X CO2 decreases. The volume percentage of CO in the dry exhaust gas increases when both X CO2 and X O2 values increase. In contrast, the volume percentage of H 2 increases when X CO2 decreases or X O2 increases. Overall, the results attained in this work can provide useful guidance for the application of ultra-rich H 2 flame in the carbonate hydrogenation process.