Thermal efficiency evaluation of the thermochemical H2S splitting cycle for the hydrogen and sulfur production

A flowsheet of the thermochemical H2S splitting cycle was designed and simulated for hydrogen and sulfur production. The heat and mass balance, as well as the thermal efficiency of the process, were calculated. A thermal efficiency of 40.865% for hydrogen production was obtained by optimizing the heat exchangers and the EED cell considering waste heat recovery. The effects of five calculation parameters, namely, the sulfuric acid concentration, hydrogen iodide (HI) conversion ratio, molar flow rate of HIx phase, pressure, and reflux ratio at the distillation column, on thermal efficiency were evaluated. The results indicated that further research on the membrane reactor is needed. The optimized conditions for the over-azeotropic HI solution yield should be prioritized. Furthermore, an H2SO4 concentration system should be reasonably designed to reduce the complexity of the process and equipment settings, as well as to improve thermal efficiency.

► The thermochemical H2S splitting cycle flowsheet was designed and simulated.
► The heat and mass balance was calculated.
►  The optimal thermal efficiency is 40.865% considering waste heat recovery.
► The effects of the parameters on the thermal efficiency were evaluated.