Application of Pressure Swing Adsorption to Water Detritiation Process

Abstract

Pressure swing adsorption (PSA) has been studied as a new water processing technique, detritiation of tritiated water, for a future fusion power plant. It will be a new tritium removal method having an additional function of isotope separation and quick dehydration, and it is expected to become the first stage of the system processing a large amount of tritiated water generated in a fusion plant. A series of the adsorption and dehydration experiments was carried out for a typical adsorbent of NaX zeolite as fundamental investigation to realize HTO/H2O separation system by PSA. It was clearly observed that break through time differs in H2O and HTO concerning the isotope separation function of NaX zeolite. It is certain that NaX zeolite can separate into the tritium concentrated water and the tritium reduced water by this difference of the break through time. The quick dehydration is attained by decompression and purge gas flowing. It was observed that a part of amount of the water released by the decompression was transferred by the purge gas, and the rest of water was adsorbed on the adsorbent again. After the re-adsorption phenomenon, the rest of water was gradually released by the diffusion. It is demonstrated that enlargement of pressure difference between adsorption and dehydration is effective to obtain high dehydration ratio. Furthermore, it was also verified that enough vapor removal capacity of purge gas is quite necessary to obtain high dehydration ratio.