An efficient low-carbon hydrogen production system based on novel staged gasification coupling with chemical looping technology

Efficient hydrogen production and decarbonization through coal gasification still suffers from significant challenges. In this work, a novel and efficient low-carbon hydrogen production method via coal staged gasification coupling chemical looping technology was innovatively proposed, the method exhibits potential advantages in improving hydrogen production efficiency and achieving near-zero energy CO2 capture. Moreover, the chemical recuperation method that efficiently recovers the exhaust heat of the system is also employed to further enhance the gasification efficiency. Thermodynamic analysis results indicate that the cold gas efficiency of staged coal gasification, composed of coal pyrolysis and coke-CO2 gasification, reaches 85.04 %. By coupling chemical looping technology using FeO/Fe3O4 as an oxygen carrier, the corresponding hydrogen production efficiency achieves 65.32 %, with CO2 enrichment concentration reaching 92.14 %, thereby enabling zero-energy CO2 capture. Additionally, thermodynamic exergy balance analysis shows that the exergy efficiency of the new method for hydrogen production reaches approximately 64.51 %. The staged gasification, chemical looping, and heat exchange processes are identified as key contributors to exergy destruction. The energy utilization diagram methodology is used to further elucidate the mechanism of exergy destruction from the perspective of the level difference between the energy donor and the energy acceptor. Moreover, the new method is also compared with conventional coal-to-hydrogen gasification technology. This work can serve as significant guidance for the development of novel low-carbon coal gasification hydrogen production technologies.