Reduction of heat input to IS (iodine-sulfur) process by removal of HI-I-HO mixture purification

Kasahara, Seiji  ; Kubo, Shinji  ; Tanaka, Nobuyuki ; Yan, X. ; Onuki, Kaoru

In thermochemical hydrogen production IS process, purification of all of the HI-I-HO (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 JAEA suggests possibility of removal of the purification of the HIx fed to anode side of the EED cell. In this study, reduction of heat input to IS process by removal of HIx mixture purification was investigated by process flow calculation. The net heat input to the HI separation subsection was 143.1 kJ/mol-HI with removal of purification of the HIx fed to EED anode side, which was considerably smaller than that of 278.9 kJ/mol-HI in the case of no purification removal. The main factor for the reduction was elimination of the heat input for the anode side feed purification. The removal of the purification lowered EED voltage and reduced electricity input to the EED. The removal also decreased feed rate to the HI distillation column and decreased heat input to the reboiler of the column. These side effects also reduced the net heat input.