CA2183832A1

CA2183832A1 - Enhanced helium recovery

Info

Publication number: CA2183832A1
Application number: CA 2183832
Authority: CA
Inventors: Glenn C. Stoner; Herbert Edward Reinhold, Iii; Joseph S. D'amico; Kent S. Knaebel
Original assignee: Individual
Current assignee: Nitrotec Corp
Priority date: 1995-08-21
Filing date: 1996-08-21
Publication date: 1997-02-22

Abstract

The disclosed hybrid membrane and pressure swing adsorption process can recover helium from source streams of about 0.5 to 5 percent by volume helium and concentrate the helium to a concentration of greater than about 98 percent by volume.
The process comprises a membrane separation followed by two stages of pressure swing adsorption which are used in series. The source of the helium gas will be a natural gas source. The source gas will primarily contain hydrocarbons but will contain some nitrogen. The membrane unit will contain a semipermeable membrane which is permeably selective for helium and will to the extent feasible reject methane and hydrocarbons. The permeate gas will be increased in helium content by 2 to 10 times. Part of the residue gas is used in the regeneration of the adsorbent beds in the first stage of pressure swing adsorption. Each stage of pressure swing adsorption will contain a plurality of adsorbent beds, and preferably about four. In each stage the adsorbent beds will be cycled through multiple phases. In the first stage the adsorbent beds will sequentially undergo the phases of adsorption, recycle, depressurization, evacuation, helium pressurization and recycle feed pressurization.
The product gas from the first stage is flowed to the second stage and in the second stage sequentially will undergo the phases of adsorption, depressurization, evacuation, purge, and helium pressurization. The offgas from the evacuation and purge in the second stage is flowed to input to the first stage. The membrane/pressure swing process efficiently produces a product stream in a high volume with a helium content of more than 98 percent by volume.

Description

~ 8383~
ENHANC~I ) HET TUM RECOVERY

FTFT n OF TH~ INVENTION
Thi~ ap~l~c~tion i~ a cont~uation in part of U.S. A~lic~Lol~ Se.;al No.
0~J326,917 filed Octobcr 21, 1~9~.
( R Ch~ ~a~ C~ a~J5 a", ~4-.~ 7as~ c~.
This invention relates to processes for the recovery of~ ~)fromra natural gas) containing stream. More particularly, this invention relates to a combined membrane separation and pressure swing adsorption system and processes for the recovery of a ~ $7Rs (a~L~as ~e.~. ~
( a.~. heliu~from~ natural gas)containing stream using this membrane separation and 10 pressure swing adsorption system.
BACKGROUND OF TH~ T~VENTION
The principal source of helium is its separation from natural gas streams prior to the natural gas streams being used as a fuel or as a chemical feedstock. Natural gas streams can contain up to about 10 percent helium. It is economically feasible to 15 recover helium from a natural gas stream down to a con~ent of as low as about 0.1 ~ercent.
The economic feasibility depends on both the capital cost for a system and the ongoing operational cost. It is an objective of the present invention to set out a system where the economic efficiency of the system is maximized through the use of a 20 combined membrane and pressure swing adsorption system.
There is disclosed in U.S. application serial no. 08/326,917 an efficient pressure swing adsorption process for the recovery of helium from natural gas streams. This pressure swing adsorption system will take a typical natural gas which contains from about 1 to 6 percent helium and produce a helium stream which contains more than2S 99.9 ~elcent helium. This is a very high purity helium. This is done by solely using a pressure swing adsorption system.
One problem in the use of such pressure swing adsorption systems in the recovel ~ of helium from natural gas streams which contain low levels of helium is the voltllnes of gas that must pass through the adsorbent beds of the pressure swing 2 2 1 83~32 adsorption system to recover a given volume of helium. In order to accommodate large volumes of helium, the adsorbent containing columns and other equipment must be sized for this gas flow. However, as the volume of gas flow increases, the diameter and/or length of the adsorption columns is increased and the amount of 5 adsorbent needed is likewise increased. It is this capital equipment cost plus the operating cost that will determine if a natural gas stream with a particular helium conlent can be used as a source of helium.
The efficiency of recovering helium from lower helium content natural gas streams can be increased if there is a membrane partial separation of the helium from lO the natural gas with a permeate natural gas with an increased helium contellt being fed to a pressure swing adsorption system. The processes of this application aredirected to increasing the heliurn conlent of a natural gas stream from about two to ten times the initial concentration up to about 8 to 20 percent helium by volume in a membrane separation stage. When the helium content of the natural gas is doubled, 15 the amount of gas to be flowed through the pressure swing adsorption system to recover the same volume of helium is halved. If tripled, the volume is reduced to one third. And when the helium content is quadrupled the amount of natural gas to beflowed through the pressure swing adsorption system to recover the same volume of helium is reduced to a quarter. This has a significant effect on the capital cost of the 20 pressure swing adsorption system and its operating cost. There is a greater efficiency even though there is a capital cost and an operating cost for the membrane separation system. There is a net cost savings when the helium content in the natural gas stream is inaeased a given amount.
Using the present pressure swing adsorption system, There is no need to 25 increase the helium content to above about 20 percent by volume. This pressure swing adsorption system can very effectively increase the helium conlent in this lower range to more than 99.99 percent by volume. This is not feasible with the prior art helium recovery systems.

3 2 1 8383~
The efficiency of the pressure swing adsorption system also can be improved.
By the use of some of the high pressure residue gas from the membrane unit as the gas to aid in removing primarily nonadsorbed gas FROM the adsorbent bed that has completed an adsorption phase, the need for an ~itional compressor in the process 5 is obviated. This results in a savings in the capital cost of the pressure swing adsorption unit.
It is known to separate helium from natural gas by means of pressure swing adsorption. Such a process is disclosed in U.S. Patent 5,089,048. This patent ~ rloses a pressure swing adsorption system for helium enrichment. The process in this patent 10 can be used with helium streams which contain less than 10 percent helium. The ~rocess consists of a three step pressure build-up phase, an adsorption phase, a three step pressure relief phase, and an evacuation phase. In the pressure build-up phase, a cocurrent first depressurization gas is flowed cocurrently into an adsorbent bed which has been evacuated to increase the gas pressure in this bed. This is followed by a 1 5 countercurrent flow of a second cocurrent depressurization gas from another adsorbent bed which has completed an adsorption phase. This is then followed by a countercurrent flow of product gas to bring the bed up to the operating pressure. This process will produce a purified helium stream but at a lower efficiency. One problem is that there is a loss of product helium in the gases that are discharged as waste gases.
20 Since the amounts of helium in the waste gas are relatively high, their loss creates an the inPffi~i~ncy of the process. In the processes of the present invention, helium is maintained in the pressure swing adsorption system as a gas inventory and not removed as part of a waste gas or off-gas. In ~ lition the multi-step pressuri7~tion and depressuri_ation techniques are not used in the pressure swing adsorption 25 system.
European Patent 092,695 and U.S. Patent 3,636,679 also ~ rlose pressure swing adsorption systems for helium purification. However, in European Patent 092,695, the feed gas should contain about 50 to 95 percent by volume heli-lm It is not suitable for - - 2~3a32 gas streams containing less than about 50 percent helium, and is clearly not useful where the helium content of the gas stream is less than about 25 percent helium.It likewise is known to separate helium from other gases using a combination of membrane separation and pressure swing adsorption separation. However, it is 5 not known to take a helium source having a helium content of less than about 10 percent by volume helium and providing a product that is 99.99 percent by volumehelium. In U.S. Patent 4,701,187 the feed to the membrane has a helium concentration of 58.2 mole ~ercellt. This is a high feed concentration. In U.S. Patent 4,717,407, there is described a process for the recovery of helium where the feed stream is first treated 10 in a non-membrane unit and then in a membrane unit. The non-membrane unit canbe an adsorption unit. This is the reverse of the present process and would require a greater capital cost for the adsorption unit since làrge gas volumes have to be proresse~ in the adsorption unit. U.S. Patent 5,006,132 discloses a process for upgrading the main product in a pipeline by means of a membrane process. The main 1 5 product permeates through the membrane with contaminants rejected. The rejected gas is put back into the pipeline and the product gas is used. Helium can be one of the rejected gases. U.S. Patent 5,224,350 discloses a process for recovering helium from a hydrocarbon/nitrogen stream by first removing the hydrocarbons in a liquid extraction followed by a nitrogen/helium separation in a membrane unit. The helium 20 from the membrane unit that is in a concentration of more than 50 mole percent can be flowed to a pressure swing adsorption unit to increase the helium conle,lt to more than 99 mole percent. None of these processes is a highly efficient process. In the ~resellt system and processes, there is no need for a membrane unit to increase the helium content of a feed gas to 50 mole percent or more. The present membrane and 2 S pressure swing adsorption system and processes have a high efficiency at a feed to the pressure swing adsorption unit from the membrane unit of about 10 to 20 volume ~crcent helium.

2~ 3 2~ ~

Bl~F SUMMARY OF TH~ INVENTION
~ ,a b ~
It is an object of this invention to provide a process for h~liun~ which tili7~s at least one stage of membrane enrichment followed by at least two stages of c~ g~5 pressure swing adsorption. The membrane enrichment will increase the h~ u r~. ~ a ~ -~
S concentration of from about two to ten times the initiah~h~entration with the pressure swing adsorption stages increasing theCb~li~tration to 98 percent by ( 7~ ~ ~RS~ "a ~4~ Z~j----OO~
volurne or mo~he source of the helium containing stream can be a gas stream exiting a natural gas well, a natural gas pipeline or any other gaseous source containing helium.
When the gas source is a pipeline, or a wellhead gas that is to be flowed into apipeline, a non-permeate residue gas from the membrane stage is compressed to pipeline pressure and put into the pipeline. In this way there is a minimal loss of natural gas in the pipeline or of the natural gas being flowed to the pipeline. The off-gas from the first pressure swing stage can be used to power compressors or is flared.
As a pre~erLed embodiment, some residue gas from the membrane unit is fed to the stage I pressure swing adsorption process. This gas is used in phase II to flow a gas having an essentially feed gas composition from the adsorbent bed that is undergoing phase II processing in place of pressurizing a depressurization gas from phase m and using this pressurized gas for this purpose. There then is produced a 20 recycle feed gas from phase II that is used in phase VI to repressurize an adsorbent bed that is to go back onto a phase I adsorption step. By the use of residue gas to produce the recycle feed gas a compressor is not needed to pressurize part of the depressurization gas from phase m for use in phase II to produce the recycle feed gas.
Essentially any membrane that is permeation selective for helium versus 2 5 nitrogen, methane, carbon dioxide and hydrocarbons can be used. The feed pressure to the membrane module will be in the range of about 400 to 1200 psig. The helium enriched gas that permeates through the membrane will be at about 65 to 100 psiapressure, or at a lower pressure if a vacuum is drawn on the permeate side of the ~ 6 2 1 838~
membrane. If more than one stage of membrane separation is used this permeate gas will be pressurized to about 400 to 1200 psig and fed to the second stage. After the membrane enrichment of the gas stream the permeate gas as needed is pressurized to about 25 to 100 psia and fed to one or more stages of pressure swing adsorption to 5 increase the concentration of helium. In order to increase the helium concentration to 98 percent by volume or more, it is preferred to use two stages of pressure swing adsorption.
Although each stage of pressure swing adsorption also can be used alone without the other stage, it is the preferred embodiment to use two stages of pressure 10 swing adsorption. Only the first stage of pressure swing adsorption can be used where a helium gas in a purity of 75 to 95 percent by volume will be sufficient. Such a purity is sufficient for party balloons and advertising balloons. The second stage of pressure swing adsorption can be used alone where the helium gas has been concentrated to about 50 to 90 percent by volume using a membrane or cryogenic 15 technique but then must be increased to a purity of 98 percent by volume or more.
This second stage of pressure swing adsorption is very efficient in producing high purity helium gas streams.
The first pressure swing adsorption stage is comprised of a plurality of adsorbent beds with each adsorbent bed sequentially undergoing six pressure swing 20 adsorptionphases. Theseare:
- Adsorption II - Recycle m - Depressurization IV - Evacuation V - Helium Pressurization VI - Feed Recycle Pressurization The second pressure swing adsorption stage is comprised of a plurality of adsolbel~t beds with each adsorbent bed undergoing five phases. These are:

- Adsorption II - Depressurization m - Evacuation IV - Purge V - Helium Pressurization In the first stage pressure swing adsorption system the adsorbent bed enters a phase I adsorption phase and produces a crude helium product. Following the adsorption phase the adsorbent bed is regenerated. In regeneration the adsorbent bed first enters a phase II recycle phase where a recycle feed gas is produced. This is 10 produced by feeding a part of the residue gas from the membrane unit to this adsorbent bed. The recycle feed gas that is produced as it exits the adsorbent bed which has just completed an adsorption phase is flowed to an adsorbent bed about to go onto a phase I adsorption phase. In the phase II recycle phase the residue gas flows through the adsorbent bed pushing the gas in the void space (which has 15 approximately feed composition) to the exit of the bed. The phase m depressurization comprises countercurrently reducing the pressure in the adsorbent bed and recovering a depressurization gas that is combined with the Phase IV evacuation phase gas, compressed for use as energy to power plant equipment, or to the flare unit. At this point, the adsorbent bed undergoing phase m depressurization is at20 about ambient pressure and undergoes a phase IV evacuation phase to remove essentially all of the adsorbed components. The adsorbent bed on phase IV
evacuation is lowered in pressure to less than ambient pressure to countercurrently remove the adsorbed substances from the adsorbent bed. This gas is recovered andcompressed with the gas from phase m as described above. This gas primarily will be 2 S hydrocarbons and nitrogen. The adsorbent bed then undergoes a phase V heliumpressurization where an enriched helium gas from phase I adsorption is flowed counterc~urenlly into the adsorbent bed. In a final phase the adsorbent undergoes a phase VI recycle feed pressurization where recycle feed gas from phase II recycle is fed cocurrently into the adsorbent bed. The adsorbent bed then is at about input gas pressure and is in a condition for a phase I adsorption.
The crude helium from the first pressure swing adsorption stage is fed to the second pressure swing adsorption stage. In the second pressure swing adsorption 5 stage the adsorbent bed on phase I adsorption receives the enriched helium product from the first pressure swing adsorption phase. Upon the completion of the phase I
adsorption phase, the adsorbent bed undergoes a phase II depressurization phase.This consists of countercurrently reducing the pressure in the adsorbent bed to about ambient pressure. All of the depressurization gas produced in the depressurization 10 phase is compressed and flowed to the adsorbent bed on an adsorption phase. Upon the completion of the phase II depressurization phase, the adsorbent bed then undergoes a phase m evacuation phase. This consists of reducing the pressure to less than ambient pressure. The off-gas from this phase can be collected and in whole or in part flowed to the feed of the first pressure swing adsorption stage or fed to the input 15 to the membrane separation unit. It will be primarily nitrogen and some helium.
Prior to completion of the evacuation phase, the adsorbent bed is purged with anamount of helium product from this second pressure swing adsorption stage. This consists of flowing some of the product helium gas countercurrently into the adsorbent bed. This removes traces of non-helium gases from the adsorbent bed and 20 void space. The adsorbent bed then undergoes helium pressurization phase V which consists of flowing product helium gas countercurrently into the adsorbent bed. At this point the adsorbent bed has been regenerated and is ready for another adsorption phase.
Each pressure swing adsorption system is comprised of a plurality of adsorbent 25 beds. Usually there are about three to five adsorbent beds in each pressure swing adsorption stage and ~referably about four. Each adsorbent bed in each stage sequentially will undergo the noted phases. The number of adsorbent beds used will be an economic balance between the capital cost of the installation and operating -- - 2183~

costs. The timing of the phase in each stage will to a degree be dependent on the composition of the feed streams., the feed stream flow rates and the size of theadsorbent beds.

Brief Description of the Drawing~
Figure 1 is a schematic diagram of a hybrid membrane and pressure swing adsorption system for helium recovery.
Figure 2 is a schematic diagram of the pressure swing adsorption phases of the first stage of the pressure adsorption system section of the helium recovery yrocess.
Pigure 3 is a schematic diagram of the pressure swing adsorption phases of the second stage of the pressure swing adsorption section of the helium recovery process.
Figure 4 is a detailed schematic diagram of the first stage pressure swing adsorption system.
Figure S is a detailed schematic diagram of the second stage pressure swing adsorption system.
Figure 6 is a table which sets out the phase sequences by time for the first stage pressure swing adsorption system.
Figure 7 is a table which sets out the phase sequences by time for the second stage pressure swing adsorption system.
1 )etailed l:)escription of the Invention The present processes will be described in more detail with reference to the figures. The processes yrererably consist of at least one membrane separation stage and at least two stages of pressure swing adsorption. A feed gas is derived from a wellhead gas or from a natural gas pipeline. This gas will be at a pressure of about 25 psia to 1200 psia. This feed gas is fed to the membrane stage of the process at a pressure of about 400 to 1200 psia. The membrane stage produces a permeate stream and a non-permeate residue stream. The residue stream which is almost 100 percent non-helium containing gas is pressurized and fed back to the gas source while the 2 1 B38~

permeate stream, depending on its pressure, will be used at permeate pressure orpressurized to about 25 to 100 psia and fed to the first stage of pressure swingadsorption. In the first stage, a gas stream which contains up to about 20 percent by volume helium is enriched in helium to more than about 50 percent by volume, and5 ~rerelably to more than about 90 percent by volume helium. This is accomplished by ~rererenlially adsorbing the other gases that are present along with the helium and removing the other gases. Then in a second stage of pressure swing adsorption, depending on the helium content of the feed gas, the helium content of the gas stream is increased to more than 95 percent by volume, and preferably to more than about 99 10 ~ercent. At this concentration the helium is commercially usable.
A primary source of helium is from natural gas. This can be from the natural gas at the wellhead or from a natural gas in a pipeline. The present combined membrane and pressure swing adsorption system is economic to operate to recover helium present at low concentrations. The membrane separation will increase the 15 concentration of the helium and decrease the volume of the other gases that must be removed to recover the helium. This makes it economically viable to recover helium from gas streams having a low helium content.
The membrane section of the system can be any membrane device with some selectivity for helium over nitrogen, carbon dioxide, methane and higher 20 hydrocarbons. Each membrane section may consist of a single membrane device, or in the alternative, several membrane modules interconnected and operated in order to most efficiently produce a final permeate stream with a maximum helium content.
Each of the modules would contain a semipermeable membrane selective for the particular separation. Suitable semipermeable membranes include polysulfane, 25 cp~ lose acetate, polyimide, polyamide, silicone rubber and polyphenylene oxide membranes. These membranes will increase the content of the helium in the gas stream from two to ten times. These membranes ~refelably will be in the form of tubes having a very small diameter. This provides for a high gas/membrane contact 21 83~2 and a selective permeation of the helium through the membrane. The initial helium content of the feed gas will be about 0.5 to 5 percent by volume helium, visually about 0.5 to 2 percent by volume helium.
Each of the pressure swing adsorption systems uses an adsorbent which has no 5 affinity for helium. Essentially any adsorbent that has an affinity for nitrogen and hydrocarbons can be used. The ~refer~ed adsorbents are activated carbons.
Aluminosilicate and silica gel adsorbents also can also be used.
In Figure 1, there is shown a combined membrane and pressure swing adsorption system that gets a feed gas from conduit 13. This conduit 13 can be a gas 10 pipeline, such as an interstate gas pipeline, or a feed from a wellhead. Compressor 17 will boost the pressure to about 400 to 1200 psia with this gas being fed into membrane separation section 19. This compressor is not needed where the gas is at a pressure of greater than about 400 psia. In this membrane separation unit is a semipermeable membrane highly selective for helium with a low permeability for the 15 other components of the gas stream. The residue gas exits at conduit 23 and is boosted in pressure by compressor 27 prior to being fed back into pipeline 13.
Preferably, some of this residue gas is flowed to the pressure swing adsorption units through conduit 61. The permeate gas which is at a pressure of about 65 to 100 psia or lower flows to compressor 33 where it is increased in pressure to about 25 to 100 psia 20 as is needed and fed into the first stage of pressure swing adsorption 37. The gas is further enriched in helium and flows by conduit 39 to a second stage of pressureswing adsorption 41. There is produced a product gas which is more than 98 ~ercent by volume helium and a by-product gas that is rich in the other components, primArily nitrogen is fed, in whole or in part, back to any of the feed to the first stage 25 of pressure swing adsorption or to the feed to the membrane separation unit. This gas flows through conduit 43 to compressor 45 where it is boosted in pressure. Valve 49 which is in line 47 is a three way valve. This valve will direct the flow of gas to conduit 55 and the first stage of pressure swing adsorption, or to compressor 57 and 12 2 1 838~2 through line 59 to the input to the membrane separation stage. The non-helium containing gas from the first stage of pressure swing adsorption will be flowed through conduit 63 for use in providing power to the plant or flared. The membrane unit will be comprised of a section containing from 10 to 30 tubes of a polymer 5 selective for helium. These tubes will be about 8 to 16 in diameter and 3 to 6 ft. in length The pressure drop across the membrane unit is about 5 psid. The membrane unit processes a gas flow of about 350 to 3500 scfm. The output gas will have a helium conlent of about 4 to 20 percent by volume helium.
The first pressure swing adsorption stage consists of six phases which are set 10 out diagramatically in Fig. 2. In phase I, adsorption, an input gas stream is fed to the adsorbent bed. An enriched helium gas flows from this adsorbent bed with substantial quantities of the other gases being adsorbed in the adsorbent bed. Aportion of the enriched helium is used in phase V helium pressurization. After the adsorbent bed that is undergoing adsorption has become saturated with adsorbed 15 other gases, it enters recycle phase. This consists of flowing a residue gas from the membrane unit to this adsorbent bed on phase II recycle. This residue gas removes helium and feed gas that is in the void space in the adsorbent bed to produce a recycle feed gas. The recycle feed gas with the helium from the void space flows from this adsorbent bed and is fed to the adsorbent bed that is on a phase VI recycle feed20 press-~ri7~tion phase. This recycle feed gas may be supplemented with feed gas, i.e.
permP~te gas from the membrane unit.
Concurrently an adsorbent bed is undergoing a phase m depressurization phase. The phase m depressurization phase consists of decreasing the pressure in an adsorbent bed to about ambient pressure. The effluent gases which are hydrocarbons 2 S and nitrogen contain little or no helium and may have a high fuel value. They are used to power plant equipment or are flared. At the same time another adsorbent bed is undergoing a phase IV evacuation phase. The phase IV evacuation consists of drawing a vacuum on the adsorbent bed and countercurrently removing substantially all of the adsorbed gases from the adsorbent bed. These gases, like the phase m depressurization gas, usually are recompressed and fed back to the pipeline or other source. If not fed back to the pipeline or other source, they are used as a fuel in the plant or flared.
Simultaneously another adsorbent bed is undergoing a helium pressurization phase. In this phase enriched helium product from phase I adsorption is flowed into the adsorbent bed, preferably countercurrently. Immediately upon the completion of helium pressurization the adsorbent bed is further pressurized with recycle feed gas from phase II recycle and feed gas. Preferably this gas is flowed cocurrently into the adsorbent bed. This adsorbent bed then will be at about the pressure of the input gas.
The enriched helium gas from phase I that is not used in the stage I pressure swing adsorption process is flowed to the second stage pressure swing adsorptionprocess for additional enriching. The second stage pressure swing adsorption process is ~iPS. rihed in Fig. 3 This is a five phase process and is different from the first stage pressure swing adsorption process. The first phase of the second stage process is an adsorption phase and consists of passing the enriched helium gas from stage I into the adsorbent bed undergoing a second stage adsorption phase. A further enriched helium gas flows from the adsorbent bed on phase I adsorption with the non-helium other gases being adsorbed. A portion of this enriched helium is used in the phase IV
purge phase to countercurrently flow and purge the other gases from the void space and the adsorbent in the bed undergoing this phase. Another portion of the enriched helium is flowed to phase V helium pressurization. The adsorbent bed undergoing phase V pressurization is pressurized prior to undergoing a phase I adsorption phase.
Concurrently, there is an adsorbent bed undergoing a phase II
2 5 depressurization. This consists of countercurrently depressurizing the adsorbent bed which has completed the phase I adsorption phase to produce a recycle gas. The recycle gas from this phase II depressurization is pressurized to about the feed gas 2 i 83~3~

pressure or higher and flowed along with feed gas into the adsorbent bed on phase I
adsorption.
At the same time, an adsorbent bed is undergoing a phase m evacuation. This consists of reducing the pressure from ambient to more than 20 inches of Hg v~clll.m, 5 and ~referably to more than about 28 inches of Hg vacuum. This removes substantially all of the non-helium other gases from the adsorbent bed. This gas from the evacuation phase is usually recycled to stage I input gas since it can contain up to 50 percent or more by volume helium.
These are the pressure swing adsorption phases that are used in stage I and in 10 stage II. Each adsorbent bed undergoing the pressure swing adsorption process in each stage sequentially goes through the respective phases for stage I and for stage II.
The timing for the phases in each stage varies with the composition of the input gas stream, gas flow rates and the size of the adsorbent beds. The timing will be governed also by the time that it takes an adsorbent bed on an adsorption phase to reach 1 5 breakthrough. The input to the adsorbent bed on an adsorption phase will cease just prior to the adsorbed gases exiting (breaking through) the end of the adsorbent bed.
This then will govern the timing of the other phases.
The stage I process will be described with particular referellce to Fig. 4. The input gas stream is fed through conduit 10 and valve 12 into conduit 14 which delivers 20 the input gas stream to the adsorbent beds. Since adsorbent bed A is on an adsorption phase inlet valve 32 is open as is exit valve 38. Valves 30, 34 and 36 are closed as are inlet valves 44, 56 and 68 for the other adsorbent beds. Valve 24 also is closed. An enriched helium product exits adsorbent bed A and flows through conduits 21 and 23 to stage II. Throttle valve 28 controls the pressure in conduits 21 and 23 and enriched 25 helium storage tank 26 which stores some of the enriched helium product from this stage I. The stored enriched helium gas is used in stage I.
Upon the completion of the adsorption phase adsorption bed A enters a recycle phase. In the recycle phase, part of the residue gas from the membrane unit and 2 1 838;32 residue gas from storage tank 25 is fed to adsorbent bed A from conduit 22. During this time valve 32 is closed and valve 30 is opened. On the exit end of adsorbent bed A valve 38 is closed and valve 40 is open. A recycle feed gas flows from adsorbent bed A through conduit 20 to storage tank 16 during this phase. This recyde feed gas S will be used to pressurize adsorbent bed B which concurrently is undergoing a phase VI recycle feed pressurization. In order to flow this gas to adsorbent bed B valve 12 is dosed and valve 24 opened. Input valves 32, 68 and 56 on the other adsorbent beds are closed and valve 44 opened. The residue gas during the recycle phase removes a helium gas having a content of about the input gas from the void space in adsorbent 10 bedA.
While adsorbent bed A is on an adsorption phase and a recycle phase, adsorbent bed D has been on a phase m depressurization phase. In this phase, outlet valves 74 and 76 are closed as are inlet valves 66, 68 and 72. Depressurization gas flows from adsorbent bed D through valve 70 and into conduit 18. This 1 5 depressurization can be used as a fuel in the plant or flared.
While adsorbent bed A is on an adsorption phase and a recycle phase, and adsorbent bed D on a depressurization phase, adsorbent bed C is on a phase IV
evacuation phase. In this phase outlet valves 62 and 64 and inlet valves 54, 56 and 58 of adsorbent bed C are closed. Valve 60 is opened. Evacuation gas, which is 20 substantially the more highly adsorbed non-helium gases, flows through vacuumpump 35 and is flowed for further use. Upon the completion of the evacuation phase, adsorbent bed C is substantially clean of the non-helium more highly adsorbed gases.
Concurrently with these operations, adsorbent bed B has been on re~ressllri7~tion. The first part of re~ress lrization consists of the phase V helium 25 pressurization phase. In this phase, all of the inlet valves to adsorbent bed B, valves 42, 44, 46 and 48, are closed. Outlet valve 52 also is closed. However, outlet valve 50 is opened so that enriched helium gas will flow countercurrently into adsorbent bed B.
Upon the completion of helium pressurization, valve 50 is closed and inlet valve 44 is ~ ~~ 16 2 1 83832 opened. At this time inlet valve 12 is closed and recycle valve 24 is opened. This allows a recycle feed gas to flow into adsorbent bed B through conduit 14 from storage tank 16. This will repressurize adsorbent bed B to about the input feed gas pressure.
A ~refe~red option is to incorporate a short input gas repressurization just prior 5 to the adsorption phase. In this mode up to about half of the recycle feed repressurization time is transferred to an input gas repressurization time. In this ~refelled option it only is required that valve 24 be closed and valve 12 opened. Since adsorbent bed B will be entering an adsorption phase in the next sequence, Ws will remain the position of these valves. During an input gas pressurization of adsorbent 10 bed B outlet valves 50 and 52 remain closed. When adsorbent bed B enters the adsorption phase it then will be necessary only to open valve 50.
This describes a full sequence of the operation of the stage I pressure swing adsorption system. This produces an enriched helium which contains more than about 7S volume percent helium, and preferably more than about 90 volume percent15 helium. The adsorbent beds then sequentially go through the phase sequences as set out in Fig. 6. A useful timing for a full cycle is 480 seconds. However, timing is dependent on input gas stream composition, pressure and flow rates as well as adsorbent bed size. If a feed pressurization step is used in the repressurization of the adsorbent beds this usually will be for a period of about 40 seconds. This timing is for 20 adsorbent beds which contain about 18,000 pounds of adsorbent, a feed gas pressure of about 50 psia and a flow rate of about 1000 to 3000 cubic feet per minute, and ~,eferably about 2000 cubic feet per minute. Table 1 gives the valve position versus time during a cycle of the stage I pressure swing adsorption system. The full operation of the stage I process is fully described with reference to Fig. 2, Fig. 4, Pig. 6 25 and Table 1.

Valve ~ 0-120 sec. 120-240 sec. 240-360 sec. 360-480 sec.
12 1 O/C(l) I O/C(l) I O/C(l) I O/C(l) 24 C/O(2) C/O(2) C/O(2) C/O(2) C/0(4) C C C
32 0/C(3) C C C/0(5) 38 0/C(3) C C O/C(6) C/o(4) C C C
42 C C/0(4) 44 C/O(s) o/C(3) C C

O/C(6) 0/C(3) C C
52 C C/0(4) C C
54 C C C/0(4) C
56 C c/o(5) 0/C(3) C

O C C C
62 C O/C(6) 0/C(3) C
64 C C C/O(4) C
66 C C C C/O(4) 68 C C C/0(5) 0/C(3) O C C C
n c o c c 74 C C O/C(6) 0/C(3) 76 C C C C/O(4) 78 C/O(~ C/O(~ C/O(~ C/O(~

- 2 1 83~32 (1) Open during adsorption and closed during recycle feed pressurization (2) Closed during adsorption and open during recycle feed pressurization (3) Open during adsorption and closed during recycle (4) Closed during adsorption and open during recycle 5 (5) aosed during helium pressurization and open during recycle feed pressurlzahon (6) Open during helium pressurization and closed during recycle feed pressurization (7) Closed during the first part of depressurization.

The helium enriched gas from stage I is fed as the feed gas to the stage II
pressure swing adsorption system as shown in Fig. 5. This feed gas flows from conduit 23 of stage I through valve 112 and into conduit 114. With adsorbent bed E on a phase I adsorption phase, outlet valve 136 is open as is inlet valve 130. Valve 102 is 1 S dosed. Valves 132 and 134 of adsorbent bed E are closed, as are inlet valves 138, 146 arld 154 to adsorbent beds F, G and H respectively. The feed gas flows into adsorbent bed E as also does a recycle gas from adsorbent bed H which is on a phase II
depressurization phase. Optionally some of the recycle gas can be stored in tank 121.
This depressurization phase recycle gas flows through conduit 118 to compressor 122 20 where its pressure is increased up to about that of the feed gas or higher. A purified heliurn product flows through valve 136 and through conduit 124 to a product outlet with some purified helium held in storage tank 126. Throttle valve 128 regulates the pressure in conduit 124 and tank 126. Part of this purified helium will be used in the purge phase and in the phase V helium pressurization phase. The remainder is 25 productgas.
While adsorbent bed E has been on a phase I adsorption phase, adsorbent bed H has been on a phase II depressurization phase. In this phase, outlet valve 160 and 110 are closed, as are inlet valves 154 and 156. The depressurization recycle gas flows through valve 158 and conduit 118 to compressor 122. Pressurized to about feed gas pressure or higher, the recycle gas flows through conduit 120 to conduit 114. In this part of the sequence, this recycle gas will be fed to adsorbent bed E.
Concurrently adsorbent bed G is on a phase III evacuation phase and a phase IV purge phase. In the evacuation phase outlet valve 152 and 108 are closed as are inlet valves 146 and 150. A vacuum is drawn on conduit 116 by vacuum pump 135.
T~is decreases the pressure in adsorbent bed G to more than about 20 inches of Hg vacuum and ~refelably to more than about 28 inches of Hg vacuum, which substantially removes all of the more highly adsorbed gases from this adsorbent bed G. For the phase IV helium purge phase which takes place at the end of the evacuation phase, valve 108is opened to allow purified helium to enter adsorbent bed G and to flow countercurrently down into adsorbent bed G. Valve 148 remains openand adsorbent bed G is under a vacuum. This serves to remove the more highly adsorbed gases from the void space and the adsorbent in adsorbent bed G. The gases 1 S flowing from adsorbent bed G are compressed in compressor 45 and flowed to the input to stage I through conduits 47 and 55 as a part of the stage I input gas or to the feed to the membrane unit through conduits 47 and 59. If flowed to the membrane unit it will be compressed to the membrane unit pressure by compressor 57.
Additionally concurrently adsorbent bed F has been in repressurization. This first consists of a phase V helium pressurization phase. In this phase inlet valves 138, 140 and 142 are closed. Outlet valve 144 is open so that purified heliurn gas which is at a pressure about that of the feed gas flows countercurrently into adsorbent bed F to increase the pressure of adsorbent bed F to about that of the feed gas. Valve 106 is dosed.
A preferred option is to also incorporate a feed gas pressurization into the sequence. This entails the closing of valve 106 about half to three fourths of the time through the helium pressurization phase, and preferably about two thirds of the time, and opening valve 138. This permits a repressurization to full feed gas pressure by the use of feed gas prior to valve 144 being opened and an adsorption phase initiated.
When this adsorbent bed enters an adsorption phase it only will be rle-~essAry to open valve 144.
Valves 100, 104, 107 and 111 are throttle valves which are open through all 5 phase sequences. These valves are interconnected to line 124 and the adsorbent bed exits via conduits 101, 103, 105 and 109 respectively. The flow of helium gas as a purge gas is controlled by the respective companion valve to each of these throttle valves.
This completes an operating sequence for the stage II pressure swing system.
10 Each of the adsorbent beds sequentially goes through each of the phases. Thissequence versus time is set out in Fig. 7. This is shown for a 360 second cycle which is a ~ref~l~ed timing. However, as with stage I, the timing is dependent on feed gas composition, feed gas pressure and flow rate and on the adsorbent bed size. In this stage each adsorbent bed contains about 1600 pounds of adsorbent.
Table 2 describes the position of each valve during a cycle of Fig. 7 using the pressure swing adsorption system of Fig. 5 and the phase sequence of Fig. 3.

21 8383~

Valve # 0-90 sec. 90-180 sec. 180-270 sec. 270-360 sec.
102 C C C/O(l) C
106 C C C C/O(l) 108 C/O(l) C C C
110 C C/O(l) C C
130 O C C C/O(2) 136 C C O/C(3) 138 C/O(2) O C C

144 O/C(3) O C C
146 C C/O(2) O C

152 C O/C(3) O C
154 C C C/O(2) O

160 C C O/C(3) O

(1) Closed during evacuation and open during purge S (2) Closed during helium pressurization and open during an optional feed gas pressurization of 15 seconds (3) Open during helium pressurization and closed during an optional feed gas pressurization 22 2~838~
This valve position sequence is for a preferred operation of the present processas is the phase and cycle timing. The valve position sequence and the phase and cycle tin~ing can be modified and yet remain within the scope of the present processes.
The two position valves that are used are valves which are either open or S closed usually are butterfly valves. Valves 28 and 128 are throttle valves that remain open in a constricted condition.
The combined stage I and stage II pressure swing systems will produce a h~ gas product of more than about 90 percent by volume helium, and ~rererably more than about 98 percent by volume helium. The pressure swing system can be 10 fully automated with a central processor controlling all of the flows and valve sequencing. The valves are rated for the pressures of the systems. The tanks andconduits likewise must be rated for the operating pressures.
This description sets out the preferied operation of the stage I and stage II
pressure swing systems to produce a highly énriched product. The full scope of the 15 invention is more particularly set out and described in the appended claims.
As noted above the first stage of pressure swing adsorption or the second stage of pressure swing adsorption can be used alone; however, it is ~refelred that they be used together in tandem as ~esrriked. The first stage will produce a helium product stream of about 75 to 90 percent by volume helium from a gas stream of less than20 about 20 percent by volume. Such a helium product can be used in balloons anddirigibles. The second stage of pressure swing adsorption will bring this heliumstream up to a helium content of 98 percent by volume or more.
A factor in the increased efficiency of the present pressure swing adsorption ~rocPssPs is the inventory of gas that is maintained within each of pressure swing 25 adsorption stage. The only gases that are discharged from stage I is the product enriched helium gas and the adsorbed gases which primarily are hydrocarbons and nitrogen. These will contain trace amounts at most of helium. In stage I the only non-product gas that leaves the system is the gas from the evacuation phase which is only 23 2 ~ 8~8~
adsorbed gases and has essentially no helium content and the depressurization gas that has essentially no helium content. The effluent gas from the recycle phase flows to a recycle feed pressurization phase. The gas in the first stage of pressure swing adsorption functions as an inventory gas until it is essentially devoid of helium and 5 then is vented or flared.
The second stage of pressure swing adsorption likewise maintains a high il~V~ntCl,y of gas. When used in combination with the first stage of pressure swing adsorption the gas from the evacuation phase and from the helium purge phase is flowed to the input gas to stage I pressure swing adsorption. In this way no helium 10 leaves the system. A high inventory of gas is maintained in stage II through the flow of all of the depressurization gas into the adsorbent bed in an adsorption phase.
The ~rere~led embodiments of the present helium enrichment proress~s have been rlicclosed in this specification. However various modiffcations can be made to the processes and yet comprise the present concepts. Such modifications are 1 5 co~ci~lered to be within the present discoveries.
EX~MPT ~
An input gas containing 1.6 percent helium by volume, 26 percent hydrocarbons by volume and 72.4 percent nitrogen by volume is flowed to membraneunit 19 at a pressure of 925 psig and 5250 scfm. The permeate stream which contains 4 20 ~ercent by volume helium exits at 65 psia and flows through conduit 9 to the first stage pressure swing adsorption 37. Since the permeate stream is already at a pressure of 65 psia, compressor 33 is not needed. The residue stream exits the membrane unit at 920 psia through conduit 23, is compressed by compressor 27 to the source pressure and flowed back to the source. This residue stream will contain less 25 than 0.05 percent helium.
The membrane unit consists of 16 modules containing a polyimide. The polyimide membrane is in the form of hollow fibers. Each module is 10 inches in diameter and 4 feet in length.

- _ 24 218~32 The permeate stream is flowed to a two stage pressure swing adsorption plant which consists of four adsorbent beds as shown in Figures 4 and 5. Each adsorbent bed in stage I contains 11 cubic meters of an activated carbon adsorbent and each adsorbent bed in stage II contains 1 cubic meter of activated carbon adsorbent. The S input gas is fed at a pressure of 65 psia and a flow rate of 2100 scfm to the stage I
adsorbent beds. The phases of stage I are as set out in Figure 6 and the phases of stage II are set out in Figure 7. The valves are on a time cycle as described in Table 1 for stage I and Table 2 for stage II. An enriched helium gas stream having a helium gas colltel~t of 90 percent helium flows through conduit 23 at 127 scfm to stage II
10 adsorbent beds. This enriched helium gas is further purified in stage II to a product helium gas having a helium content of 99.999 percent helium. This is produced at a flow rate of 80 scfm.
The gas from the adsorbent bed in the stage II evacuation phase and the gas from the stag II purge phase is recycled to the input gas to stage I. This gas has a 15 helium content of 73 percent and flows at a rate of 47 scfm. The depressurization gas and the evacuation gas from stage I pressure swing adsorption is compressed and fed to the residue gas stream.
The process is operated continuously until a general maintenance is required.

Claims

WHAT IS CLAIMED IS:

1. A method for the separation of helium from an input gas stream containing helium and other gases comprising feeding said input gas from a source to a membrane separation unit at an elevated pressure, flowing a residue stream from said membrane separation unit, a first portion of said residue stream being flowed to the source of said input gas and flowing a permeate gas stream from said membrane separation unit enriched in helium to a first stage of a first stage and a second stage pressure swing adsorption process and after processing said permeate gas in said first stage of pressure swing adsorption flowing the non-adsorbed portion of said permeate gas to said second stage of pressure swing adsorption, each stage containing a plurality of interconnected adsorbent beds, the first stage of pressure swing adsorption concentrating the helium in said gas stream to greater than about 50 percent helium by volume and in a second stage of pressure swing adsorption concentrating said gas stream to greater than about 95 percent helium by volume, a second portion of said residue gas stream being fed to said first stage of pressure swing adsorption as a processing gas.

2. A method for the separation of helium as in claim 1 wherein in said first stage of pressure swing adsorption there are six phases, each interconnected adsorbent bed undergoing said six phases for each complete cycle, said six phases comprising in sequence an adsorption phase, a recycle phase, a depressurization phase, an evacuation phase, a helium pressurization phase and a recycle feed pressurization phase, said second portion of said residue gas from said membraneseparation unit being flowed to an adsorbent bed on said recycle phase with an effluent recycle feed gas enriched in helium flowing therefrom, said recycle feed gas being flowed to an adsorbent bed that is to enter said adsorption phase to pressurize said adsorbent bed to about the operating pressure of said first stage of pressure swing adsorption.

3. A method for the separation of helium as in claim 2 wherein there are at least four adsorbent beds, feeding said input gas stream to the input end of a first adsorbent bed of said first stage entering on said adsorption phase and selectively adsorbing said other gases, collecting a gas enriched in helium flowing from said first adsorbent bed of said first stage and flowing a portion thereof to said second stage pressure swing adsorption and a portion thereof to a second adsorbent bed of said first stage that has completed said evacuation phase and that has entered said helium pressurization phase, concurrently depressurizing a fourth adsorbent bed of said first stage and producing an effluent gas, flowing said second portion of said residue gas to said first adsorbent bed, upon the completion of said adsorption phase and the initiation of said recycle phase, flowing the effluent from said first adsorbent bed of said first stage during said recycle phase to a second adsorbent bed of said first stage upon the completion of said helium pressurization phase and that is to enter said adsorption phase to pressurize said second adsorbent bed of said first stage to about input gas stream pressure, and concurrently evacuating a third adsorbent bed of said first stage that has completed said depressurization phase to remove said other gases therefrom.

4. A method for the separation of helium as in claim 2 wherein in said second stage of pressure swing adsorption there are five phases, each interconnected adsorbent bed undergoing said five phases for each complete cycle said five phases comprising in sequence an adsorption phase, a depressurization phase, an evacuation phase, a purge phase and a helium pressurization phase, flowing a feed gas enriched in helium from said first stage to an adsorbent bed in said second stage undergoing said adsorption phase with a further enriched helium gas effluent flowing therefrom, flowing a first portion of said further enriched helium gas to purge other gases from an adsorbent bed in said purge phase, flowing a second portion of said enriched helium gas to an adsorbent bed that has completed said purge phase and which is to enter said adsorption phase to pressurize said adsorbent bed, and flowing a third portion of said further enriched helium to product.

5. A method for the separation of helium as in claim 4 wherein there are at least four adsorbent beds in said second stage of pressure swing adsorption, feeding said gas from said first stage as a feed gas to a first adsorbent bed in said second stage and collecting three portions of a further enriched helium gas therefrom, concurrently depressurizing a fourth adsorbent bed of said second stage which has completed the production of said further enriched helium and which contains substantial amounts of said other gases, recovering an effluent second stage recycle gas from said fourth adsorbent bed of said second stage and pressurizing said second stage recycle gas to about the pressure of said feed gas to said second stage and flowing said second stage recycle gas to said first adsorbent bed of said second stage, concurrently reducing the pressure in a third adsorbent bed of said second stage to less than about ambient pressure and removing a portion of said other gases therefrom, concurrently flowing a first portion of further enriched helium from said first adsorbent bed of said second stage to a third adsorbent bed of said second stage which has completed said evacuation phase as a purge gas and further removing said other gases therefrom, and concurrently flowing a second portion of said further enriched helium to a second adsorbent bed of said second stage to increase the pressure within said second adsorbent bed of said second stage.

6. A membrane separation unit as in claim 5 wherein at least some of said other gases from said third adsorbent bed of said second stage are fed to the input to said membrane separation unit.

7. A membrane separation unit as in claim 5 wherein at least some of said other gases from said third adsorbent bed of said second stage are fed to the input to said first stage of pressure swing adsorption.

8. A method for the separation of helium as in claim 3 wherein some of said effluent gas from depressurizing said fourth adsorbent bed and said other gases from said third adsorbent bed which has undergone said evacuation phase are pressurized and flowed for use as an energy source in the operation of said separation method.

9. A method for the separation of helium as in claim 2 wherein the adsorbent within each of said adsorbent beds is an activated carbon.

10. A method for the separation of helium as in claim 3 wherein said second adsorbent bed of said first stage is further pressurized with input gas prior to entering an adsorption phase.

11. A method for the separation of helium as in claim 4 wherein the adsorbent within each of said adsorbent beds is an activated carbon.

12. A method as in claim 1 wherein the source of said input gas is a natural gas pipeline.

13. A method for the separation of helium from an input gas stream containing helium and other gases comprising feeding said input gas from a source to a membrane separation unit at an elevated pressure, flowing a first portion of aresidue gas stream from said membrane separation unit to the source of said input gas and flowing a permeate gas stream to a first stage of a first stage and second stage of pressure swing adsorption, each stage containing a plurality of interconnected adsorbent beds, said first stage of pressure swing adsorption concentrating the helium in said gas stream to greater than about 75 percent helium by volume and in saidsecond stage of pressure swing adsorption concentrating said gas stream to greater than about 95 percent helium by volume, at least some of an off gas from the evacuation of an adsorbent bed in said second stage to below about ambient pressure being fed along with said input gas stream to the input of the first stage of pressure swing adsorption, said first stage consisting of at least four interconnected adsorbent beds, each adsorbent bed undergoing six phases for each complete cycle of pressure swing adsorption, said six phases comprising in sequence an adsorption phase, a recycle phase, a depressurization phase, an evacuation phase, a helium pressurization phase and a recycle feed pressurization phase, feeding said input gas stream to the input end of a first adsorbent bed of said first stage entering on said adsorption phase and selectively adsorbing said other gases, collecting a gas enriched in helium flowing from said first adsorbent bed of said first stage and flowing a portion thereof to a second adsorbent bed of said first stage that has completed said evacuation phase and that has entered said helium pressurization phase, concurrently depressurizing afourth adsorbent bed of said first stage and collecting a first effluent gas, flowing a second portion of said residue gas to said first adsorbent bed of said first stage upon the completion of said adsorption phase and the initiation of said recycle phase, flowing the effluent from said first adsorbent bed of said first stage during said recylce phase to a second adsorbent bed of said first stage upon the completion of said helium pressurization phase and that is to enter said adsorption phase to pressurize said second adsorbent bed of said first stage to about input gas stream pressure, concurrently evacuating a third adsorbent bed of said first stage that has completed said depressurization phase to remove said other gases therefrom and to collect a second effluent gas, flowing another portion of said gas enriched in helium to asecond stage of pressure swing adsorption which consists of at least four interconnected adsorbent beds, each such adsorbent bed undergoing five phases for each complete cycle of pressure swing adsorption, said five phases comprising insequence an adsorption phase, a depressurization phase, an evacuation phase, a purge phase and a helium pressurization phase, feeding said enriched helium gas from said first stage as a feed gas to a first adsorbent bed in said second stage and collecting three portions of a further enriched helium gas therefrom, concurrently depressurizing a fourth adsorbent bed of said second stage which has completed the production of said further enriched helium and which contains substantial amounts of said other gases, depressurizing and recovering an effluent second stage recycle gas from said fourth adsorbent bed of said second stage and pressurizing said secondstage recycle gas to about the pressure of said feed gas to said second stage and flowing said second stage recycle gas to said first adsorbent bed of said second stage, concurrently reducing the pressure in a third adsorbent bed of said second stage to less than about ambient pressure and removing a portion of said other gases therefrom, concurrently flowing a first portion of further enriched helium from said first adsorbent bed of said second stage to a third adsorbent bed of said second stage which has completed said evacuation phase as a purge gas and further removing said other gases therefrom, concurrently flowing a second portion of said further enriched helium to a second adsorbent bed of said second stage to increase the pressure within such adsorbent bed, and flowing some of said other gases from said third adsorbent bed of said second stage to at least one of said first adsorbent bed in said first stage and the input gas to said membrane separation unit.

14. A method for the separation of helium as in claim 10 wherein the adsorbent in each adsorbent bed is an activated carbon adsorbent.

15. A method for the separation of helium as in claim 10 wherein said second adsorbent bed of said first stage is further pressurized with input gas prior to entering an adsorption phase.

16. A method for the separation of a component gas from an input gas stream containing said component gas and other gases comprising feeding said input gas from a source to a membrane separation unit at an elevated pressure, flowing a residue gas stream from said membrane separation unit, flowing a permeate gas stream from said membrane separation unit to a pressure swing adsorption separation unit, and flowing a portion of said residue gas to said pressure swing adsorption unit for use in regenerating said pressure swing adsorption unit.

17. A method for the separation of a component gas as in claim 16 wherein there are at least two interconnected stages of pressure swing adsorption, said portion of said residue gas being flowed to said first stage of pressure swing adsorption for use in regenerating said first stage of pressure swing adsorption.

18. A method for the separation of a component gas as in claim 17 wherein in said second stage of pressure swing adsorption there is produced a gas stream rich in said component gas and a gas stream substantially depleted in said component gas, at least a portion of said gas stream substantially depleted in said component gas flowed to the input gas stream to said membrane separation unit.

19 A method for the separation of a component gas as in Claim 17 wherein in said second stage of pressure swing adsorption there is produced a gas stream rich in said component gas and a gas stream substantially depleted in said component gas, at least a portion of said gas stream substantially depleted in said component gas flowed to the permeate gas for input to said first stage pressure swing adsorption unit.

20. A method for the separation gas as in claim 16 wherein said component gas is helium.