Appeal No. 1998-2624
Application No. 08/696,578
to Mehra, the absorber overhead stream is fed to a methane
absorber which recovers a hydrogen product stream as overhead
and produces a rich solvent stream as bottoms. Mehra’s abstract
further teaches:
When recovering up to 50% of the incoming
hydrogen, this rich solvent stream from the methane
absorber is fed to the demethanizing absorber, but
when recovering from 20% to 100% of the incoming
hydrogen, this rich solvent stream is recycled in part
to the demethanizing absorber and in part is fed to a
methane stripper which sends its bottoms to the
methane absorber and its overhead to an auto
refrigerated recovery unit which removes H2, CH4, and
CO as a fuel gas product and produces an ethylene and
heavier stream. The rich solvent stream from the
demethanizing absorber is separated in a solvent
regenerator into an overhead stream of ethylene and
heavier hydrocarbons and a bottom lean solvent stream
for recycle to the methane absorber and then to the
demethanizing absorber. The bottom stream of the
recovery unit and the overhead stream of the solvent
regenerator are combined to form an ethylene and
heavier product stream.
By contrast, Dunlop’s teachings are directed to an entirely
different purpose. Specifically, Dunlop teaches various
separation processes including the recovery of monoolefins from
paraffins using various metal salts. (Column 1, lines 20-47.)
From our perspective, neither Mehra nor Dunlop provides any
evidence that one of ordinary skill in the art would have
considered the separation process described in Dunlop to be
interchangeable with, much less desirable over, the
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