Hydrogen and electricity co-production plant integrating steam-iron process and chemical looping combustion

In this paper, steam-iron process (Fe looping) and NiO-based chemical looping combustion (Ni looping) are integrated for hydrogen production with inherent separation of CO₂. An integrated combined cycle based on the Fe and Ni loopings is proposed and modeled using Aspen Plus software. The simulation results show that at Fe-SR 815 °C, Fe-FR 815 °C, Ni-FR 900 °C and Ni-AR 1050 °C without supplementary firing, the co-production plant has a net power efficiency 14.12%, hydrogen efficiency 33.61% and an equivalent efficiency 57.95% without CO₂ emission. At a supplementary firing temperature of 1350 °C, the net power efficiency, hydrogen efficiency and the equivalent efficiency are 27.47%, 23.39% and 70.75%, respectively; the CO₂ emission is 365.36 g/kWh. The plant is attractive because of high-energy conversion efficiency and relatively low CO₂ emission; moreover, the hydrogen/electricity ratio can be varied in response to demand. The influences of iron oxide recycle rate, supplementary firing temperature, inert support addition and other parameters on the system performance are also investigated in the sensitive analyses.