Conceptual design of the iodine–sulfur process flowsheet with more than 50% thermal efficiency for hydrogen production

A conceptual design of a practical large-scale plant of the thermochemical water splitting the iodine–sulfur (IS) process flowsheet was carried out as a heat application of Japan Atomic Energy Agency’s commercial Gas Turbine High Temperature Reactor 300 MW for Cogeneration (GTHTR300C) plant design. Innovative techniques proposed by JAEA were applied for improvement of hydrogen production thermal efficiency; depressurized flash concentration of H2SO4 using waste heat from Bunsen reaction, prevention of H2SO4 vaporization from a H2SO4 distillation column by introduction of H2SO4 solution from the 2nd flash bottom, and I2 condensation heat recovery by direct contact heat exchange in an HI distillation column. A simulation of material and heat balance was made using PRO/II, a commercial chemical process simulator. The result demonstrated that hydrogen of about 31,900 Nm3/h would be produced by 170 MW heat from the GTHTR300C. A process thermal efficiency of 50.2% would be achievable with incorporation of the innovative techniques and the following high performance components expected in future R&D; an electro-electrodialysis cell stack, a reverse osmosis membrane, a HI decomposition reactor incorporated with a H2 permselective membrane, and heat exchangers.