Process and apparatus for recovering hydrocarbons from inert gas-hydrocarbon vapor mixtures

Claim 2

A process for recovering hydrocarbons from an inlet inert gas-hydrocarbon vapor mixture comprising: flowing said inlet mixture through a first bed (12) of solid adsorbent having an affinity for hydrocarbons whereby hydrocarbons are adsorbed on said bed (12) and a residue gas stream comprised of substantially hydrocarbon-free inert gas is produced; removing said substantially hydrocarbon-free inert gas from said bed (12) of adsorbent; evacuating a second bed (14) of solid adsorbent having hydrocarbons and inert gas adsorbed thereon by vacuum pumping with a vacuum pump (80) having attached thereto a cooling jacket for cooling said pump and fluids pumped thereby,whereby a major portion of said hydrocarbons are desorbed from said bed (14) and a hydrocarbon-rich inert gas-hydrocarbon mixture is produced; separating from said mixture,prior to pumping said mixture with said vacuum pump,hydrocarbons which condense from said inert gas-hydrocarbon mixture; passing a cooling medium through said cooling jacket of said vacuum pump thereby to cool said pump and said inert gas-hydrocarbon mixture pumped thereby; contacting the inert gas-hydrocarbon mixture, produced in said evacuation desorption step and pumped by said vacuum pump, in an absorber with a lean liquid absorbent having an affinity for hydrocarbons whereby a major portion of the hydrocarbons are removed therefrom,thereby producing a hydrocarbon-rich liquid absorbent stream and a residue gas stream comprised of inert gas and a minor portion of hydrocarbons; combining said residue gas stream produced in said contacting step with said inlet inert gas-hydrocarbon mixture to said first absorbent bed (12) whereby hydrocarbons contained therein are adsorbed on said first bed (12) of solid adsorbent; and periodically changing the flow patterns of said inlet inert gas-hydrocarbon mixture and changing the bed (12 or 14) of solid adsorbent being evacuated, whereby when a said bed (12) through which the inlet inert gas-hydrocarbon mixture is flowing becomes loaded with adsorbed hydrocarbons, the inlet inert gas-hydrocarbon mixture is caused to flow through the bed (14) which has just been regenerated by said evacuation desorption.

Claim 3

A process according to claim 1, further including the step of cooling said beds (12, 14) of solid adsorbent by flowing a cooling medium through heat transfer coils (21, 23) disposed in said beds of solid adsorbent thereby to prevent said beds from over-heating.

Claim 4

A process according to claim 2, wherein the cooling of said beds (12, 14) of solid adsorbent is carried out at least while said inert gas-hydrocarbon vapour mixture is flowing therethrough.

Claim 5

A process according to any one of claims 1 to 3, further including the step of introducing a quantity of hydrocarbon-free inert gas into said second bed (14) while evacuating said bed whereby additional hydrocarbons are stripped from said bed (14) and additional inert gas-hydrocarbon mixture is produced.

Claim 6

A process according to claim 4, wherein said hydrocarbon-free inert gas is heated prior to introducing it into said beds.

Claim 7

A process according to claim 4 or 5, wherein said inert gas is air, said inlet air-hydrocarbon mixture comprises vaporised gasoline light ends, and said solid adsorbent is granular activated carbon.

Claim 8

A process according to claim 6, wherein said liquid absorbent is gasoline.

Claim 9

Apparatus for recovering hydrocarbons from an inert gas-hydrocarbon vapor mixture comprising: a pair of adsorbers (12, 14) containing beds of solid adsorbent having an affinity for hydrocarbons and having inlet connections (16, 20) and outlet connections (18, 22) on opposite sides of the respective said beds; a first conduit system (24, 26, 28, 30) connected to the inlet connections (16, 20) of said adsorbers (12, 14) for conducting said inert gas-hydrocarbon vapor mixture to said absorbers (12, 14) and for evacuating said adsorbers (12, 14); valving (32, 34) disposed in said first conduit system for selectively causing said inert gas-hydrocarbon vapor mixture to flow through one or the other of said adsorbers (12, 14); a second conduit system (46, 48) connected to the outlet connections (18, 22) of said adsorbers (12, 14) for conveying residue gas from said adsorbers; second valving (50, 52) disposed in said second conduit system for selectively causing residue gas to be withdrawn from one or the other of said adsorbers; a vacuum pump (80) having a suction connection (82) and a discharge connection (1 0 8) and having attached thereto a cooling jacket for cooling said pump and the fluids pumped thereby, said cooling jacket having a cooling medium inlet connection (86) and a cooling medium outlet connection (144); means (116, 118, 120) connected to the cooling medium inlet connection (86) and cooling medium outlet connection (144) of said vacuum pump cooling jacket for circulating a cooling medium therethrough; a third conduit system (36, 42, 78) connected between the suction connection (82) of said vacuum pump (80) and said first conduit system; third valving (38, 40) disposed in said third conduit system for selectively communicating one or other of said adsorbers with the suction connection (82) of said vacuum pump; liquid knockout means (72) disposed in said third conduit system; an absorber (90), for contacting an inert gas-hydrocarbon vapor mixture with a liquid absorbent, having an inert gas-hydrocarbon vapor mixture inlet connection (98), a residue gas outlet connection (96), a lean liquid absorbent inlet connection (94) and a rich liquid absorbent outlet connection (100); a fourth conduit system (108) connected between the inert gas-hydrocarbon vapor mixture inlet connection (98) of said absorber (90) and the discharge connection (84) of said vacuum pump (80); and a fifth conduit system (125) connected between the residue gas outlet connection (96) of said absorber (90) and said first conduit system (26, 28, 30).

Claim 10

Apparatus for recovering hydrocarbons from an inert gas-hydrocarbon vapor mixture comprising: a pair of adsorbers (12, 14) containing beds of solid adsorbent having an affinity for hydrocarbons and having inlet connections (16, 20) and outlet connections (18, 22) on opposite sides of the respective said beds; a first conduit system (24, 26, 28, 30) connected to the inlet connections (16, 20) of said adsorbers (12, 14) for conducting said inert gas-hydrocarbon vapor mixture to said absorbers (12, 14) and for evacuating said adsorbers (12, 14); valving (32, 34) disposed in said first conduit system for selectively causing said inert gas-hydrocarbon vapor mixture to flow through one or the other of said adsorbers (12, 14); a second conduit system (46, 48) connected to the outlet connections (18, 22) of said adsorbers (12, 14) for conveying residue gas from said adsorbers; second valving (50, 52) disposed in said second conduit system for selectively causing residue gas to be withdrawn from one or the other of said adsorbers; a vacuum pump (80) having a suction connection (82) and a discharge connection (1 0 8) and having attached thereto a cooling jacket for cooling said pump and the fluids pumped thereby, said cooling jacket having a cooling medium inlet connection (86) and a cooling medium outlet connection (144); means (116, 118, 120) connected to the cooling medium inlet connection (86) and cooling medium outlet connection (144) of said vacuum pump cooling jacket for circulating a cooling medium therethrough; a third conduit system (36, 42, 78) connected between the suction connection (82) of said vacuum pump (80) and said first conduit system; third valving (38, 40) disposed in said third conduit system for selectively communicating one or other of said adsorbers with the suction connection (82) of said vacuum pump; liquid knockout means (72) disposed in said third conduit system; an absorber (90), for contacting an inert gas-hydrocarbon vapor mixture with a liquid absorbent, having an inert gas-hydrocarbon vapor mixture inlet connection (98), a residue gas outlet connection (96), a lean liquid absorbent inlet connection (94) and a rich liquid absorbent outlet connection (100); a fourth conduit system (108) connected between the inert gas-hydrocarbon vapor mixture inlet connection (98) of said absorber (90) and the discharge connection (84) of said vacuum pump (80); and a fifth conduit system (125) connected between the residue gas outlet connection (96) of said absorber (90) and said first conduit system (26, 28, 30).

Claim 11

Apparatus according to claim 8, wherein said means for circulating a cooling medium through said vacuum pump cooling jacket comprises: a sixth conduit system (116, 120, 134, 136) connected between said rich liquid absorbent outlet connection (100) of said absorber (90) and storage facilities therefor; a rich liquid absorbent pump (118) disposed in said sixth conduit system; a seventh conduit system (140) connecting said sixth conduit system downstream of said pump (118) with said cooling medium inlet connection (86) of said vacuum pump cooling jacket; and an eighth conduit system (144) connected between said cooling medium outlet connection (88) of said vacuum pump cooling jacket and a rich liquid absorbent inlet connection (102) of the absorber.

Claim 12

Apparatus according to claim 8, further including: a pair of heat transfer coil assemblies (21; 23) each disposed in a respective one of said adsorbers (12, 14) for cooling said beds of solid adsorbent therein and having cooling medium inlet connections (25, 27) and outlet connections (29, 31); and means (110, 112, 114, 116, 118, 120, 130, 134, 136) connected to the cooling medium inlet connections (25, 27) and outlet connections (29, 31) of said heat transfer coil assemblies (21, 23) for circulating a cooling medium therethrough.

Claim 13

Apparatus according to claim 10, wherein said means connected to the inlets and outlets of said heat transfer coil assemblies for circulating a cooling medium comprises: a cooling medium pump (118) having a suction connection and a discharge connection; a sixth conduit system (110, 112, 114, 116) connected between the suction connection of said cooling medium pump (118) and a source of cooling medium; a seventh conduit system (120, 130) connected between the discharge connection of said cooling medium pump (l18) and the inlet connections (25, 27) of said heat transfer coils; and an eighth conduit system connected between the discharge connections (29, 31) of said heat transfer coil assemblies (21, 23) and storage facilities for said cooling medium.

Claim 14

Apparatus according to claim 11, wherein said source of cooling medium is rich liquid absorbent, said sixth conduit system is connected between said suction connection of said cooling medium pump (118) and said rich liquid absorbent outlet connection (100) of said absorber (90), and said eighth conduit system is connected between said discharge connections (29, 31) of said heat transfer coil assemblies (21, 23) and rich liquid absorbent storage facilities.

Claim 15

Apparatus according to claim 10, wherein said means connected to the inlet connection (82) and outlet connection (84) of said vacuum pump cooling jacket and said means connected to the inlet connections (25, 27) and outlet connections(29, 31) of said heat transfer coil assemblies for circulating cooling medium therethrough comprise: a sixth conduit system (116, 120, 130) connected between said rich liquid absorbent outlet connection (100) of said absorber (90) and said cooling medium inlet connections (25, 27) of said heat transfer coil assemblies (21, 23),a rich liquid absorbent pump (118) disposed in said sixth conduit system; a seventh conduit system (140) connecting said sixth conduit system downstream of said pump (l18) with said cooling medium inlet connection (86) of said vacuum pump cooling jacket; an eighth conduit system (144) connected between said cooling medium outlet connection (84) of said vacuum pump heat exchanger and a rich liquid absorbent inlet connection (102) of said absorber (90); and a ninth conduit system (134, 136) connected between said outlet connections (29, 31) of said heat transfer coil assemblies (21, 23) and rich liquid absorbent storage facilities.