Influence of the initial HI on the multiphase Bunsen reaction in the sulfur–iodine thermochemical cycle

In the sulfur–iodine cycle flowsheet, HI may exist in the feeds of Bunsen reaction. The effects of the initial HI and the operating temperature on the kinetic process and thermodynamic equilibrium of the multiphase Bunsen reaction were investigated. Increasing initial HI concentration (HI/H2O = 0–1/18) or temperature (303 K–358 K) amplified the reaction kinetic rate, and led to the earlier appearance of liquid–liquid separation and less time to reach the thermodynamic equilibrium. But the separation became difficult for further increase of the initial HI content. The liquid–liquid equilibrium (LLE) phase separation was enhanced with rising temperature. An increase in the initial HI content slightly weakened the LLE phase separation at a lower temperature, while at 345 K and 358 K, the LLE phase separation characteristics showed little variation in the HI/H2O molar ratio range of 0–1/18. A hyper-azeotropic HI concentration in the HIx phase was obtained with feeding HI. The conversion of SO2 lowered as the initial HI content and the temperature increased.