REDUCTION OF HEAT INPUT TO IS (IODINE-SULFUR) PROCESS BY REMOVAL OF HI-I_2-H_2O MIXTURE PURIFICATION

摘要

In thermochemical hydrogen production IS (iodine-sulfur) process, purification of all of the HI-I_2-H_2O (HIx) mixture right after Bunsen reaction has been supposed to prevent negative influences of impurities on operation of following process components. An experimental investigation on electro-electrodialysis (EED) in Japan Atomic Energy Agency suggests possibility of removal of the purification of the HIx fed to the anode side of the EED cell. In this study, reduction of heat input to HI separation subsection by the removal of the HIx mixture purification was investigated by heat and mass flow calculation. The net heat input to the subsection was 66.8 kJ/mol-HI with removal of purification of the HIx fed to the EED anode side, which was considerably smaller than that of 153.2 kJ/mol-HI in the case of no purification removal. The main factor for the reduction of the heat input was elimination of the heat input for the anode side feed purification. The removal of the purification made the EED voltage smaller and reduced electricity input to the EED. The removal also changed feed composition to the HI distillation column and lowered heat input to the reboiler of the column. These side effects also reduced the net heat input. The removal of the purification of the HIx fed to the EED anode side was considerably effective to reduce the heat input to the HI separation subsection.