The Study on Bunsen Reaction Process for Iodine-Sulfur Thermochemical Hydrogen Production

For highly efficient operation of a Bunsen process section in an iodine-sulfur thermochemical hydrogen production cycle using nuclear heat, the process characteristics of H2SO4 -HI-H2O-I-2 mixture system for separating into two liquid phases (H2SO4-rich phase and HIx-rich phase) and the distribution of H2O to each phase were investigated. The experiments for process variables were carried out in the temperature range, from 298 to 353 K, and in the H2SO4/HI/H2O/I-2, molar ratio of 1/2/14 similar to 20/0.5 similar to 8.0. As the results, for the SO2-I-2 -H2O Bunsen reaction system, the ranges between the starting point and the saturation point for two liquid phases separation were determined by calculation. The best result for the minimization of impurities (HI and I-2 in H2SO4 phase and H2SO4 in HIx phase) in each phase was obtained in an optimum condition with the highest temperature of 353 K and the highest I-2 molar composition. In this condition, the HI/H2SO4 molar ratio in the H2SO4 -rich phase and the H2SO4/HIx molar ratio in the HIx-rich phase were 0.024 and 0.028, respectively. For the distribution of H2O to each phase, it is appeared that the affinity between HI, and H2O was more superior to that between H2SO4 and H2O. The affinity between HIx and H2O was decreased with increasing temperature but increased with increasing I-2 molar composition.