Process integration of hydrolysis and hydrogen generation processes in the six-step Cu-Cl cycle for green hydrogen production

Abstract

The ICT-OEC six-step Cu-Cl cycle dissociates water thermochemically to produce hydrogen and oxygen. In the Cu-Cl cycle integrating the hydrolysis and hydrogen processes poses a crucial engineering challenge. Hydrolysis at 350-400 °C requires extra steam, resulting in the generation of dilute HCl instead of dry HCl gas, which must be recycled for hydrogen production. To address this, pressure swing distillation (PSD) is integrated into the hydrolysis and hydrogen generation reactions to separate HCl and water. The study examines operating parameters in PSD processes. A simulated process integration model includes an intermediate heat recovery steam generator (HRSG) with PSD to complete the overall conceptual design. The nuclear-based Cu-Cl cycle without PSD demonstrates a lower environmental impact when compared to the Cu-Cl cycle with PSD. The Cu-Cl cycle with a higher HCl concentration in PSD feed exhibits a minimum global warming potential (GWP) value of 2.53 kg of CO2 eq for 1 kmol/h hydrogen production.