Development of high-temperature joints for thermochemical hydrogen production by IS process; Applicability examination of the coned-disk springs assembly and seal performance test of candidate gaskets

Kanagawa, Akihiro*; Iwatsuki, Jin ; Ishikura, Shuichi; Onuki, Kaoru; Hino, Ryutaro

Thermo-chemical Iodine-Sulfur (IS) process can produce large amount of hydrogen effectively without emission of greenhouse effect gas such as carbon dioxide, where nuclear thermal energy of a high temperature gas-cooled reactor (HTGR) is adopted as a heat source. The IS process uses strong acids such as sulfuric acid and hydriodic acid in high temperature and pressure conditions. Therefore, it is necessary to develop large-size chemical reactors featuring materials that exhibit high temperature and corrosion resistance. A SO decomposer, which is one of key components of the IS process, consists of a pressure vessel for high temperature and high pressure helium gas and an internal structure for SO decomposition by the latent heat of the helium gas. Since joints of the internal structure will be heated up to 700C, we designed a high-temperature joint coupled with coned-disk springs and SiC bolts (coned-disk springs assembly) so as to keep seal performance under high temperature condition. This report presents applicability examination results of designed coned-disk springs assembly as well as seal performance test results of candidate gaskets.