Hydrogen iodide processing section in a thermochemical water-splitting iodine-sulfur process using a multistage hydrogen iodide decomposer

Ohashi, Hirofumi ; Sakaba, Nariaki ; Imai, Yoshiyuki  ; Kubo, Shinji  ; Sato, Hiroyuki  ; Kato, Ryoma*; Tachibana, Yukio ; Kunitomi, Kazuhiko 

A multistage hydrogen iodide (HI) decomposer in a thermochemical water-splitting IS process for hydrogen production using the HTGR is numerically evaluated, especially on the flow rate of undecomposed HI and product iodine at the outlet of the decomposer in order to reduce regenerated heat by recuperates for the recycle of undecomposed HI and eliminate components for the separation. A suitable configuration of the multistage HI decomposer is countercurrent than co-current, and the HIx solution from an electro-electro dialysis at low-temperature is a favorable feed condition for the multistage HI decomposer. An alternative HI processing section using the multistage HI decomposer and eliminating some recuperators and components for the separation is proposed and evaluated. A quantity of regenerated heat by recuperate in the proposed HI processing section can be reduced less than about 1/3 compared with that in the conventional HI processing section.