Hydrogen production by high-temperature gas-cooled reactor; Conceptual design of advanced process heat exchangers of the HTTR-IS hydrogen production system

Sakaba, Nariaki ; Ohashi, Hirofumi ; Sato, Hiroyuki  ; Hara, Teruo; Kato, Ryoma; Kunitomi, Kazuhiko 

Nuclear hydrogen production is necessary in an anticipated hydrogen society that demands massive quantity of hydrogen without economic disadvantage. Japan Atomic Energy Agency (JAEA) has launched the conceptual design study of a hydrogen production system with a near-term plan to connect it to Japan's first high-temperature gas-cooled reactor HTTR. The candidate hydrogen production system is based on the thermochemical water-splitting iodine-sulphur (IS) process. The heat of 10 MW that approximately 900C, which can be provided by the secondary helium from the intermediate heat exchanger of the HTTR, is the energy input to the hydrogen production system. The paper describes the recent progresses made in the conceptual design of advanced process heat exchangers of the HTTR-IS hydrogen production system. A new concept of sulphuric acid decomposer is proposed that integrates three separate functions of sulphuric acid decomposer, sulphur trioxide decomposer and process heat exchanger in the previous design. A new mixer-settler type of Bunsen reactor is also designed that integrates three separate functions of Bunsen reactor, phase separator, and pump in the previous design. The new concepts are expected to result in improved economics through construction and operation cost reductions because the number of process equipment and complicated connections between the equipment has been substantially reduced.