Cryogenic recovery of high purity hydrogen

A process for the cryogenic purification of two or more industrial by-product gas streams containing impure hydrogen in recoverable amounts, at least one of the by-product gas streams being substantially free of non-readily condensible impurities having boiling points below that of methane and containing only hydrocarbons, including methane, as impurities, and at least one of the by-product gas streams containing significant amounts of non-readily condensible impurities having boiling points below that of methane, comprising:

• separately passing the by-product gas streams substantially free of non-readily condensible impurities constituting a first feed stream, and the by-product gas streams containing significant amounts of non-readily condensible impurities constituting a second feed stream, through cooling and separation stages to separate, at each stage, a hydrogen containing gas stream overhead fraction from a condensed bottom fraction, the hydrogen containing gas stream overheads from said second feed stream also containing the non-readily condensible impurities,
• feeding the hydrogen containing gas stream overhead fraction of said second feed stream from the last of the separation stages to a methane absorber,
• feeding the first feed stream's bottom fraction from the last of the separation stages to the methane absorber, and
• recovering a purified overhead hydrogen gas stream from the methane absorber.