American Nuclear Society

Home / Publications / Journals / Fusion Science and Technology / Volume 50 / Number 1

Rates of Methane Decomposition and Hydrogen Permeation in Catalytic-Permeable Ni Tube Reactor

Satoshi Fukada, Shigeki Ono, Shigenori Suemori

Fusion Science and Technology / Volume 50 / Number 1 / July 2006 / Pages 99-106

Technical Paper /

The overall mass-transfer process of methane decomposition on Ni surfaces and hydrogen permeation through a Ni tube was experimentally investigated to design a catalytic-permeable Ni tube reactor. This is a basic study of an impurity detritiation system to decompose tritiated methane and continuously recover tritium in a gas mixture exhausted from fusion plasma. The mass-transfer process was comparatively studied under the two conditions of an open Ni tube without any packing and a Ni tube packed with 200-240 mesh Ni particles. Results were discussed in terms of a CH4 decomposition ratio decomp and a H2 permeation ratio perm. The decomp values depended on temperature and were almost independent of the flow rate. The decomp value was correlated to the first-order reaction-rate constant. On the contrary, the perm values were in reverse proportion to the flow rate and were almost independent of temperature. The perm value was related to diffusion through a H2 concentration boundary layer formed in the vicinity of the Ni tube wall. The degradation of catalytic performance due to carbon deposition on Ni was discussed based on our experiments.

Questions or comments about the site? Contact the ANS Webmaster.