Pd-alloy membrane tubes are used for hydrogen isotopes separation in the fusion fuel cycle. The efficiency of these separation processes has been significantly increased by the adoption of thin-walled self-supported membrane tubes that exhibit high permeance and infinite selectivity to hydrogen. A critical aspect in the realization of Pd-based membrane devices (both separators and membrane reactors) is related to the joining of the thin-walled tubes to the membrane module. In this work, an innovative fitting of thin-walled tubes has been obtained by coupling two special stainless steel joints (a weld adapter and a sealing insert) that tighten the flared edge of the tube. In particular, the design of the compression fitting relies on the elastic deformation reserve of the conical edge of the sealing insert that is capable: i) to ensure the sealing of the joining also in presence of the expansion/contraction of the Pd-Ag alloy during the hydrogenation cycling, and ii) to compensate small irregularities of the thin-walled tube (thickness, circularity, etc.). The effectiveness of the new joining technique in terms of both hydrogen perm-selectivity and stability has been verified in preliminary permeations tests.
All Science Journal Classification (ASJC) codes
- Civil and Structural Engineering
- Nuclear Energy and Engineering
- Materials Science(all)
- Mechanical Engineering