Simulation Study on the Distillation of Hyper-Pseudoazeotropic HI–I2–H2O Mixture

Abstract

The iodine–sulfur thermochemical water splitting process (I–S process) is considered to be one of the most promising clean and large-scale hydrogen production approaches. In the I–S process, the HI distillation step is considerably energy intensive, the heat of which largely affects the overall efficiency of hydrogen production. The present study explored the efficient operating parameters of the distillation column by process simulation assuming the feed solution of hyper-pseudoazeotropic composition which was obtainable by electro–electrodialysis. The Environmental Simulation Program (ESP), the chemical simulation software, was used for the simulation. At first, the vapor–liquid equilibrium database was validated using experimental data reported so far. Then, sensitivity analyses of the operating parameters were carried out, comprised of the HI mole fraction in the distillate, number of stages, feed location of the column, operating pressure, and feed composition. On the basis of the results of the sensitivity analyses, the optimum operation conditions were discussed.