The purification of recovery helium gas is a much annoyed problem for an operator of liquefier.
The purity of feed helium gas is one of the most important factors for a long-term stable running of liquefier. Accordingly much care is necessary for a purification process.
We previously made adsorption measurements and reported “The Problem of Separating Air from Recovery Helium Gas”. But the recovery helium gas generally contains Ar, CO
2, H
2, and Ne besides air as undesirable impurities. It seems we don't pay attention to the problem of separating such impurities, especially H
2, in a commercially available purifier. We shouldn't forget the air contains 100ppm volume of H
2, moreover the difficulty of separatingout H
2 in a purification process owing to the very low boiling and freezing point.
Actually we were confronted with a trouble of blocking JT-heat exchanger by traces of H
2. The traces of H
2 in feed helium gas concentrated on JT-cycle in a long-term running. Therefore we have made H
2-He gas adsorption measurements on charcoal, Molecular Sieves 13X, 5A, 4A and natural zeolite in the pressure range of 5-120atm and at liquid nitrogen temperature. The results show that the cocoanut shell charcoal adsorbs 100ml of H
2 per gram, the possibility of separating out 0.5 volume % of H
2 in recovery helium gas in a usual purifier with a help of small Deoxo unit.
抄録全体を表示