Helium extn. from gas contg. hydrogen by pressure swing adsorption - and catalytic removal of hydrogen avoiding use of cryogenic temp.

摘要

Extn. of He from a feed gas (I) contg. moderate amts. of He and traces of N2 (sic; H2 elsewhere) involves (a) sepg. He from (I) by pressure swing adsorption (PSA); and (b) sepg. the H2 impurity in a catalytic bed. Pref. (I) contains (6-40%), N2, CH4, water vapour, Ar, higher hydrocarbons and H2 (under 1000 ppm). If (I) contains considerable amts. of N2, less than 5% CH4 and less than 1000 ppm CO2, stage (b) is carried out before (a). Stage (a) is carried out at an adsorption pressure of 25-150 psia and ambient temp.; and a sec. prod. regeneration stream, is used to keep He losses low and ensure the purity of the He prod. Ni catalyst is used in (b). This is regenerated periodically by passing a regenerative mixt. of an inert gas (Ar, N2 and/or He) and a regulated amt. of an oxidant (max. ca. 5000 vpm O2) over the spent catalyst, contg. adsorbed H2, under ambient conditions and continuing until the catalyst is free from chemisorbed H2; removing the water formed by passing an inert gas stream heating to ca. 200 deg.C; and cooling to ambient temp. with an inert gas. ADVANTAGE - Purified He contains less than 1 vpm H2. Technique is effective and economical and avoids the use of cryogenic temps. and thermal regeneration of the catalyst.