Recovery of hydrogen

Claim 1

The method according to claim 1 wherein said petroleum crude oil feedstock is admixed with makeup hydrogen prior to passing to said catalytic hydroprocessing zone.

Claim 4

A method for the recovery of hydrogen from a normally liquid hydrocarbon fraction produced by the catalytic hydroprocessing of a petroleum crude oil feedstock which comprises the steps of: a. introducing said feedstock into a catalytic hydroprocessing zone maintained under catalytic hydroprocessing conditions including the presence of hydrogen sufficient to produce an effluent stream containing unreacted hydrogen gas, normally gaseous components, normally gaseous hydrocarbons, and normally liquid hydrocarbons; b. passing said effluent stream into a first separation zone wherein said stream is separated at a temperature form about 700* F. to about 750* F. and at substantially the catalytic hydroprocessing zone operating pressure into an unreacted hydrogen gas fraction, normally gaseous components, a normally gaseous hydrocarbon fraction, and a normally liquid hydrocarbon fraction; c. introducing a portion of said normally liquid hydrocarbon fraction into a stripping zone maintained under stripping conditions and therein passing said fraction in countercurrent contact with a separate stream of high pressure superheated steam to preferentially strip hydrogen from said fraction; d. passing said hydrogen of Step (c) in admixture with said unreacted hydrogen fraction, said normally gaseous components, and said normally gaseous hydrocarbon fraction of Step (b) to a second separation zone maintained at a temperature below about 700* F. and at substantially the catalytic hydroprocessing zone operating pressure wherein a hydrogen-rich gas fraction is separated from said normally gaseous components and said normally gaseous hydrocarbon fraction; e. passing said hydrogen-rich gas fraction of Step (d) to admix with the remaining portion of said normally liquid hydrocarbon fraction of Step (b) and returning the resultant mixture to said catalytic hydroprocessing zone of step (a); f. passing said normally gaseous components and normally gaseous hydrocarbon fraction of Step (d) to a flash zone maintained at a substantially reduced pressure wherein said normally gaseous components are separated from said normally gaseous hydrocarbons; g. passing a substantially hydrogen-free normally liquid hydrocarbon fraction from Step (c) to a second flash zone maintained at a substantially reduced pressure and then to a fractionation zone; and, h. recovering the normally liquid hydrocarbons of Step (a).