WO2016094740A1

WO2016094740A1 - Helium extraction device

Info

Publication number: WO2016094740A1
Application number: PCT/US2015/065130
Authority: WO
Inventors: Thomas DARRAH; Robert POREDA
Original assignee: Darrah Thomas; Poreda Robert
Priority date: 2014-12-10
Filing date: 2015-12-10
Publication date: 2016-06-16

Abstract

Embodiments disclosed herein describe gas extraction devices and methods, and in particular disclose a helium extraction system. An example device includes a containment tank having an input portion and an output portion, wherein the input portion is configured to connect to a source gas transmission line for receiving a source gas stream and the output portion is configured to connect to the source gas transmission line for exhausting remaining components of the source gas stream after extraction of helium. The example device further includes a membrane that is permeable to helium and substantially impermeable to other gas components of the source gas stream, and a cooling system configured to modulate a temperature of the membrane. The device further includes a vacuum cell surrounding the membrane, and a compression system configured to reduce the pressure within the vacuum cell and extract gas from the vacuum cell, and a storage tank.

Description

HELIUM EXTRACTION DEVICE

FIELD OF THE INVENTION

Example embodiments of the present invention relate generally to natural resource production, and more particularly to the extraction of helium from a gas stream.

BACKGROUND

Global demand for helium has risen significantly over the past decade and continues to rise. Because this rise in demand began after passage of the Helium Privatization Act of 1996 (which mandated a drawdown of the U. S. Federal Helium Reserve), helium prices have not increased markedly until recently. The U. S. Federal Helium Reserve has in the past accounted for a large majority of global helium supply, but its contribution to satisfying demand has shrunk and will continue to shrink in the years to come. Already, many end-users have experienced helium shortages due to prioritization of helium distribution from the U.S. Federal Helium Reserve.

At the same time, the past decade has seen large increases in U. S. natural gas production following advances in horizontal drilling and hydraulic fracturing. These new sources of natural gas typically produce gas streams having significantly lower (typically by 1 to 3 orders of magnitude) concentrations of helium than measured in the Helium Reserve (which, by some measurements, ranges from 2 to 5% He).

Unfortunately, helium has only been harvested commercially from the very small subset of new wells that produce gas with exceptionally high concentration of helium comparable to the concentration in the Helium Reserve. This is primarily a result of the fact that commercial harvesting of helium is an energy intensive and expensive process using traditional methods.

A typical method of extracting helium from source gas involves cryogenically cooling the gas stream to liquefy components with higher boiling points than helium and produce a gas stream having a high concentration of helium. In many cases, this process involves several refrigeration steps, and the resulting helium-rich gas stream can be further refined using membrane separation technologies or pressure swing adsorption (PSA). Cryogenic cooling requires large and expensive cryogenic plants, and sequester the source gases during separation, and thus these methods are not cost- effective for helium lean (<1 %) gas streams.

Various PSA mechanisms have also been used to extract helium. Pressure swing adsorption works by placing an adsorbent material (e.g., activated carbon, silica gel, alumina or zeolite, or any other such porous material with a particular affinity for some gases over others) in a chamber, and then introducing a source gas. Upon increasing the pressure in the chamber (the so-called "pressure swing"), some gases will adsorb into the bed while others do not. Both sets of gases will be of higher purity. The non-adsorbed gases can be vented from the chamber while the adsorbed gases remain trapped. The adsorbed gas can subsequently be released by modulating the pressure and/or temperature. To extract helium, PSA mechanisms traditionally are designed to adsorb all components of a gas stream except helium, such that the non-adsorbed gas is helium-rich. Again, though, PSA methods require "wholesale" sequestration and processing of the source gas, a process that delays gas delivery and, at commercial scale, requires large tanks in order to process meaningful volumes.

A fundamental problem with both of the above techniques is that they do not extract helium in a pass-through manner. In other words, a gas stream coming from an active well cannot simply be piped through either a cryogenic helium separator or a PSA device and continue to a natural gas pipeline.

A third mechanism for helium extraction comprises the use of membrane separation technologies. Traditional membrane separation technologies have many inefficiencies that render them uneconomical for any gas stream that is not already helium-rich. For instance, existing technologies place a membrane in an orthogonal position with respect to a gas source, and accordingly are only capable of separating helium from the small percentage of flowing gas that passes along the membrane (e.g., they extract only a low percentage of total helium at production pressures and flow rates). Since gas flow through a membrane is driven by the diffusional gradient of the target gas (e.g., the larger the difference between the concentrations on each side of the membrane, the faster the target gas will diffuse through the membrane), maximizing exposure to a surface of the membrane maximizes the percentage of the target gas that can be extracted. Moreover, known helium separation technologies are used exclusively to purify a gas stream that is already helium-rich, and accordingly membranes have historically been considered only in the refinement of crude helium, rather than in its initial extraction from a source gas stream. Finally, because of deficiencies with traditional technology, reliable large-scale extraction of helium from source gas streams has never been successfully accomplished.

Accordingly, high concentration natural gas streams represent the primary source of helium in the world today and are a rapidly depleting resource. In the face of the historical failures to efficiently extract helium from alternative sources, there is a long-felt need for a cost-effective mechanism for extracting helium from low- concentration (<1 %) gas streams. SUMMARY

The inventors have discovered that, to ensure adoption by natural gas producers, any helium extraction technology that produces helium from low- to mid- concentration gas streams must additionally be capable of attachment to a gas pipeline without affecting the underlying flow of gas to its original destination. The inventors have developed helium extraction technology that answers these needs, and embodiments described herein efficiently extract helium from very low concentration gas streams.

In turn, the present invention enables access to many potential new sources of helium, such as low- to mid- helium concentration wells (e.g., wells producing from unconventional black shales reserves throughout U. S., Canada, and abroad), natural gas pipelines, and a wide variety of other helium sources that were previously thought to be economically unviable.

As shown below in greater detail, embodiments of the helium extraction device described herein utilize a containment tank, a cooling system, a membrane, and a vacuum cell. Through appropriate development and combinations of these constituent elements, the inventors have developed a helium extraction device that can efficiently extract helium within a flow-through design.

The above summary is provided merely for purposes of summarizing some example embodiments to provide a basic understanding of some aspects of the invention. Accordingly, it will be appreciated that the above-described embodiments are merely examples and should not be construed to narrow the scope or spirit of the invention in any way. It will be appreciated that the scope of the invention encompasses many embodiments in addition to those here summarized, some of which will be further described below.

BRIEF DESCRIPTION OF THE DRAWINGS

Having described some example embodiments in general terms, reference will now be made to the accompanying drawings, which are not necessarily drawn to scale, and wherein:

Figures 1A-1 C illustrate perspective views of containment tanks in accordance with some example embodiments;

Figures 2A-2E illustrate different views of a set of membranes used in connection with some example embodiments;

Figure 3A illustrates a face view of a blank-off gasket including cooling elements, in accordance with some example embodiments;

Figure 3B illustrates a perspective view of a blank-off gasket including cooling elements as situated within a helium extraction device, in accordance with some example embodiments;

Figure 4A illustrates a perspective view of an example vacuum cell situated within a helium extraction device, in accordance with some example embodiments;

Figure 4B illustrates a perspective view of another example vacuum cell situated within a helium extraction device, in accordance with some example embodiments;

Figure 4C illustrates a perspective view of set of example vacuum cells that may be used in conjunction within a helium extraction device, in accordance with some example embodiments;

Figure 5 illustrates a perspective view of an example helium extraction system employing some example embodiments of the present invention; and

Figure 6 illustrates a flowchart detailing operations for helium extraction utilizing example embodiments of the present invention. DETAILED DESCRIPTION

Some embodiments will now be described more fully hereinafter with reference to the accompanying drawings, in which some, but not all, embodiments are shown. Indeed, inventions described herein may be embodied in many different forms and should not be construed as limited to the embodiments explicitly set forth herein; rather, these embodiments are provided so that this disclosure will satisfy applicable legal requirements. Like numbers refer to like elements throughout.

As mentioned briefly above, embodiments of the helium extraction device described herein utilize a containment tank, a cooling system, a membrane, and a vacuum cell, examples of each of which are described in greater detail below.

Embodiments of the helium extraction device can efficiently extract helium from a source gas stream within a flow-through design, thereby minimizing the impact on alternative uses of the source gas.

Containment Tank

In some embodiments, the helium extraction device includes a containment tank that can be incorporated into (or otherwise attached to) a source pipeline. An example containment tank 100 is illustrated in Figure 1A, and other examples are illustrated in Figures IB and 1 C. The containment tank 100 may be a container, and may be made entirely of stainless steel, steel, steel alloys, copper, brass, aluminum, or another metal container that is predominantly impermeable to helium. The containment tank 100 includes an input portion 102 for receiving a feedstock source gas stream from a gas transmission source (e.g., a pipeline) and an output portion 104 for returning an exhausted (i.e., gas minus helium) gas stream to the gas transmission source. In this manner, a source gas can pass through the helium extraction device while helium is removed therefrom.

The input portion 102 comprises an opening at a first end of the containment tank 100 that includes a connection element 106 enabling a sealed connection with a gas transmission source 1 12 (e.g., a well head, transmission pipeline, processing pipeline, liquids separation tank, gas collection or pooling station, or the like). Figure 1 A provides a series of arrow indicating the portions of the gas transmission source 112 that connect to the connection element 106. As illustrated in Figure IB, the input portion 102 may include a pipe flange (e.g., American Society of Mechanical Engineers (ASME) B16.5, ASME B 16.47, or the like) that enables connection with a similar pipe flange of the gas transmission source 112 using a gasket and bolts. In other embodiments, however, the connection element 106 may simply be a welded piece that permanently attaches the input portion 102 to the gas transmission source. The output portion 104 comprises an opening at another end of the containment tank 100 for connection to a gas transmission destination 1 14. Output portion 104 includes a connection element 108 that is similar to connection element 106 for creating a sealed connection with the gas transmission destination 1 14. Figure 1 A provides a series of arrows indicating the portions of the gas transmission destination 1 14 that connect to the connection element 108. Notably, while connection elements 106 and 108 may both comprise pipe flanges or welded pieces, it should be understood that in some embodiments one of these connection elements may comprise a pipe flange while the other may be a welded piece permanently attached to its respective gas transmission source/destination.

The containment tank 100 may additionally include one or more ports 110 (examples of which are illustrated in greater detail in Figure 2C). These ports 110 may enable access to within the containment tank 100 for, among other purposes: the measurement of pressure, temperature, gas compositional analysis, and pressure- release values; the extraction and/or compression of helium; or the modulation of the temperature or pressure within the containment tank, as will be described in greater detail below. The ports 1 10 may be vacuum welded to openings in the containment tank and may be sealable. Figures 1A and 2C illustrate example embodiments having five ports 110, but there may be additional or fewer ports of varying sizes and locations in other example embodiments.

Besides the input portion 102, the output portion 104, and the ports 1 10, the containment tank 100 may be entirely self-contained to maintain pressure, ensure safety, and to minimize the interruption of source gas distribution.

The containment tank 100 may be connected to a source gas stream in a number of ways. In some embodiments, the input portion of the containment tank natural gas may be transmitted directly from a well head into the input portion. In other embodiments, natural (source) gas may be transmitted directly from a collection station or a pipeline into the input portion of the helium extraction device. In yet further embodiments, a T-valve on a pipeline may direct all or a portion of a source gas stream into the helium extraction device, while another T-valve returns the exhaust gas stream from the helium extraction device back to the pipeline. In any case, the device may be connected to a gas transmission source 1 12 or gas transmission destination 114 through connection elements 106 and 108 of the containment tank 100 to enable transmission of a feedstock source gas stream, which will flow into the helium extraction device via input portion 102 and exit into the existing infrastructure (pipeline, storage tank, collection facility, etc.) via the output portion 104.

Membrane

Within the containment tank, the helium extraction device includes a pass through "membrane" into which the source gas flows before reaching the output port. The membrane has an intemal feed side and an extemal permeate side to allow helium to permeate from within the membrane (the feed side) to the exterior of the membrane (the permeate side) while substantially confining non-helium components from the source gas stream. In some embodiments, all of the source gas flows through the membrane, while in other embodiments, only a portion of the source gas may flow through the membrane. In yet further embodiments, the helium extraction device may include a metering portion that enables modulation of the amount of source gas that enters the membrane.

Turning now to Figure 2A, a profile view of an example membrane 200 is illustrated. In some embodiments, the material for the membrane 200 exhibits selectivity for helium. In this regard, the membrane 200 may include

polytetrafluoroethylene (PTFE). PTFE is a synthetic fluoropolymer of

tetrafluoroethylene that has numerous applications. Additionally or alternatively, the membrane 200 may include other materials (e.g., materials in the class of compounds similar to PTFE such as silicone, which may demonstrate increased selectivity for dihydrogen sulfide and its derivatives), provided that the membrane 200 provides selectivity for helium over other constitute components of a source gas stream under predefined conditions for temperature and pressure. In some embodiments, the membrane 200 may additionally or alternatively include ceramic elements, or may additionally or alternatively include one or more graphene layers designed to provide suitable porosity under the predefined conditions for temperature and pressure. In some embodiments, the physical composition of the membrane 200 may be selected to take advantage of the characteristics of the source gas stream (e.g., constituent components, pressure, temperature, and flow rate). In some embodiments, the source gas stream may enter into the membrane via blank-off gasket 202 and may exit the membrane via blank-off gasket 204 (which may also be referred to as a blank-off flange), as illustrated on either ends of membrane 200 in Figure 2A. Blank-off gaskets 202 and 204 may comprise machined metal (e.g., copper, aluminum, steel, stainless steel, or any other metal demonstrating physical strength and impermeability to helium) plates located to the interior of connection elements 106 and 108, respectively (connection elements 106 and 108 are not identified in Figure 2A).

The source gas may enter membrane 200 by passing through blank-off gasket 202. Figure 2B (another example of which is shown in Figure 2C) illustrates a front view of an example blank-off gasket (e.g., 202 or 204) and shows a series of one or more bulkhead connectors 206 that facilitating passage of the source gas into membrane 200. In the illustrated embodiment, seven bulkhead connectors 206 are shown, although there may be more or fewer bulkhead connectors 206 depending on the nature of the source gas stream (i.e., its constituent components, pressure, temperature, and flow rate). The one or more bulkhead connectors 206 may include ferruled elements or any other connecting mechanism that ensures a complete seal to prevent unwanted leaking of the source gas.

In some embodiments, blank-off gaskets 202 and 204 are identical, while in other embodiments there may be more bulkhead connectors 206 on one blank-off gasket than the other, there may be a different partem of bulkhead connectors 206 on each blank-off gasket, the bulkhead connectors 206 may be of different diameters and distances, and/or the blank-off gaskets 202 and 204 may not be identical in form. In addition, the blank-off gaskets 202 and 204 may also be of a larger diameter to accommodate more connectors. In an example embodiment, the membrane 200 may comprise one or more tubes 208 each of which conveys a portion of the source gas stream between blank-off gasket 202 and blank-off gasket 204 (as illustrated in Figure 2A and elsewhere, the one or more tubes 208 are shown in gray). In one such embodiment, the one or more tubes 208 may comprise roughly 200 meters in total length, although in other embodiments the total length of tubing may be based on the arrangement and/or geometry of the containment tank 100, the one or more tubes 208, and/or the locations of the blank-off gaskets 202 and 204. The one or more tubes 208 may have, for example, a 1/8" to 1/2" outside diameter (OD) that can connect to the bulkhead connectors 206 of both blank-off gasket 202 and blank-off gasket 204. Figure 2D illustrates an example of the one or more tubes 208. When deployed in a pass-through implementation such as a source gas transmission line, the relationship between the cross sectional area of the one or more tubes 208 and the cross sectional area of the source gas transmission line must be selected appropriately. In some such implementations, back pressure may develop if the cross-sectional area of the one or more tubes 208 is lower than the cross- sectional area of the source gas transmission line. To address this concern in such scenarios, the total diameter of the one or more tubes 208 can be designed to match the total diameter of the source gas transmission line. This can be done a number of ways. For instance, the total diameter of the helium extraction device can be enlarged, thus providing additional space for more tubes 208 within the membrane 200. Additionally or alternatively, the diameter of the tubes 208 may be enlarged (in combination with lengthening of each of the tubes) to achieve the larger cross- sectional area while maintaining extraction efficiency.

Turning now to Figure 3E, a diagram illustrating the movement of gas through the membrane 200 is disclosed. The one or more tubes 208 may simply run the length of the containment tank 100, or, as is indicated by the ellipses between blank-off gaskets 202 and 204, the one or more tubes may have different arrangements or geometries in between blank-off gaskets 202 and 204. For instance, the one or more tubes 208 may be coiled, twisted, packed, or in some other way manipulated in order to maximize the surface area of the membrane inside of the containment tank 100.

Because helium is naturally smaller and less reactive than other components of a gas stream, designing an ideal membrane porosity that selects only for helium is possible. Thus, in some embodiments, the membrane will be permeable to helium yet impermeable to all other gas components (e.g., nitrogen, methane, carbon dioxide, or the like). However, in other embodiments, the porosity of the membrane may preferably be permeable to non-helium gas components when extraction of a greater percentage of helium from the source gas stream is more important than maintaining purity of the permeate gas (for instance, this property is demonstrated by many silicone compounds). Additionally, as noted above, selection of the material of the membrane may be based on the characterization of the source gas stream, which, depending on the non-helium gas components of the source gas stream, may in some cases be suitable for a membrane made of higher porosity material.

To selectively permeate helium, the membrane 200 ideally comprises a high surface area pathway that conveys gas between the input portion of the tank and the output portion of the tank while maximizing contact of the feed side surface of the membrane to the gas extraction stream. The membrane 200 may comprise any of a number of different geometries ultimately designed to maximize this contact. While some specific embodiments (e.g., the one or more tubes 208 that may be coiled, twisted, packed, or in some other way manipulated in order to maximize surface area) are illustrated in Figures 2A-3D and described above, other alternative embodiments are contemplated in accordance with the present invention. It should be understood that the inventors have discovered that the most efficient design of the membrane will not only include a large surface area, but will include a large surface area given the constraints imposed by encapsulation of the membrane within the containment tank. In this regard, an important characteristic for an efficient membrane is its surface- area-to-volume ratio (SA:V). A high SA:V membrane will demonstrate both effective helium separation and will reduce the size of the helium extraction device and will have the smallest impact on the pressure change between the source gas stream and the exhaust gas stream (which is an important consideration for the economic production of natural gas).

Another consideration of the membrane 200 is its ability to withstand the harsh conditions of its deployment. Because many gas pipelines run at pressures well over 1000 pounds per square inch (psi) and the costs of slowing gas transit can be very large, strength and durability of the membrane are of paramount importance, and in some implementations this will be true even at the expense of helium extraction efficiency.

Cooling System

By cooling the gas stream upon entry into the helium extraction device, specifically to cryogenic temperatures (e.g., lower than -40°C), one can more efficiently separate helium from other gas constituents. This phenomenon stems from the fact that the diffusion of any constituent gas through a semi-permeable membrane is inherently a temperature-controlled process. Because of its small atomic radius, helium will continue to diffuse rapidly even at lower temperatures, while the diffusion of heavy atoms and molecules (e.g., argon, methane, nitrogen) will be preferentially retarded at lower temperatures and lead to more efficient helium extraction. An example cooling system is illustrated in Figures 3A and 3B.

In some embodiments, cooling can be accomplished by adding a number of thermoelectrically-cooled cryogenic Peltier plates 304 to the exterior surface of a blank-off gasket 202 that encloses/separates the input portion 102 from the membrane 200 (although in other embodiments these Peltier plates 304 may be located elsewhere on the blank-off gasket 202 or on blank-off gasket 204, or in other embodiments these Peltier plates 304 may be located anywhere inside the containment tank 100). Figure 4A illustrates an example blank-off gasket 302 that is similar to blank-off gasket 202, but which also includes four Peltier plates to cool the source gas stream upon its entry to the membrane 200. Each Peltier plate is electrically powered, and thus cabling 306 connects each Peltier plate to a power source (for clarity, cabling 306 has only been illustrated that connects to one of the Peltier plates 304). It should be noted that although four Peltier plates are used in the example shown in Figure 4A, fewer or more may be chosen without departing from the spirit or scope of the invention. The number of Peltier plates chosen will depend on the geometry of the blank-off gasket 202 and the desired temperature modulation capability. By using two-stage Peltier plates, example embodiments can reduce the temperature of the environment into which the source gas enters the membrane 100 to ~-60°C, which field use suggests can increase the helium extraction efficiency by approximately 10%.

The Peltier plates 304 may be powered and controlled from an external source via an insulated auxiliary port drilled through the containment tank 100 that allows cabling 306 (including, for instance, an electrical connection and a K-type thermocouple wire) through the blank-off gasket 302 to the stem of each Peltier plate 304. The cabling 306, in turn, enables measurement of the temperature within the containment tank 100, and enables control of each Peltier plate by an external cooling system controller 308 located separately from the helium extraction device. As shown in Figure 4B, in which the membrane 200 and blank-off gaskets are illustrated within the containment tank 100, the cabling 306 may exit the containment tank 100 via a port 1 10 located on the containment tank 100. The temperature can thereafter be programmed externally from 100°C to -60°C using extemal temperature controls that are monitored via a K-type thermocouple wire.

By reducing the temperature of the source gas stream upon entry into the membrane 200, these example embodiments increase the preferential diffusion of helium out of the source gas stream and into the vacuum cell (described below), and subsequently into an exceedingly high helium stock or alternatively through a multistage system that concentrates helium for commercial production. While cooling the source gas as it enters the membrane 200 produces substantially better selection of helium, heating the source gas progressively can allow neon, argon, or even some other gases to permeate through the membrane 200. Accordingly, it should be understood that while the cooling system is described herein as a mechanism for reducing the temperature of the source gas stream to maximize helium permeation, the ability to modulate the temperature of the source gas stream substantially improves the flexibility and utility of the helium extraction device, by enabling extraction of other component gases of a source gas stream without the need to physically modify any of the constituent portions of the helium extraction device.

Vacuum Cell

External to the membrane 200 within the containment tank is a vacuum cell. One embodiment comprises vacuum cell 400, illustrated in Figure 4A, and which constitutes the entirety of the volume of physical space inside the containment tank 100 and outside the membrane. This vacuum cell 400, in other words, is simply the remaining volume of space within the containment tank 100. However, other designs are contemplated as well.

For instance, in some embodiments, the vacuum cell 400 may comprise a smaller portion within the containment tank 100 that includes its own separate walls. See, for example, vacuum cell 402 as illustrated in Figure 4B (in which, for clarity, the elements of membrane 200 are not shown). Sequestering the vacuum cell 402 within its own exterior walls inside of the containment tank 100 provides additional space for other elements to be located within the containment tank 100. In one such embodiment, elements of the cooling system (e.g., Peltier plates) may be

advantageously placed within the containment tank 100 and against an extemal surface of the vacuum cell 402 (providing another way to modulate the temperature of membrane 200), which may reduce the energy necessary to cool the source gas stream and maximize helium fractionation. It should be understood that many variations of the geometry of vacuum cell 402 are contemplated herein. For instance, if the membrane comprises a tube structure, the vacuum cell 402 may have a similar, but larger, tube structure that fully encases the membrane while providing a pocket of free space into which helium may diffuse (not shown in Figures 4A-4C). In some cases, the exterior of the vacuum cell 402 may be separated from the walls of the containment tank 100 to provide an additional layer of insulation between the gas stream and the outside environment or to include other components within the containment tank 200. In this regard, one additional component that may be included in some embodiments is a PSA mechanism that can assist in the purification of gases permeated into the vacuum cell (e.g., helium or argon). In this regard, the PSA may further be used to extract.

Another variation of the vacuum cell may include a multi-stage vacuum cell 404, which has multiple sub-cells (e.g., sub-cells 406, 408, and 410) within the containment tank 100, as illustrated in Figure 4C. Although three sub-cells are illustrated in Figure 4C, any number of these sub-cells may be contemplated in embodiments of the multi-stage vacuum cell 404. Each of these sub-cells may be separated (e.g., by additional blank-off gaskets, such as blank-off gaskets 424 and 426 shown in Figure 4C) such that a first sub-cell (e.g., 406) provides a different environment (e.g., temperature and pressure) from other sub-cells, and thus each sub- cell promotes predefined gas diffusion characteristics. For example, a first sub-cell 406 may have an extremely low temperature to maximize diffusion of helium through membrane 200, while a second sub-cell 408 may have a higher temperature or a lower pressure (or both) or different membrane porosity, to promote the diffusion of another gas component (e.g., neon) or less selective gas mixtures, while yet another sub-cell 410 is designed to promote the diffusion of still other gas components (e.g., argon, dihydrogen sulfide, or even some other gases). For instance, many gas streams have high concentrations of Argon-40, which is valuable for scientific and medical purposes, and thus example embodiments may select for both helium and argon using different sub-cells, or even argon alone, in a single vacuum cell embodiment. In any event, it should be noted that the environment may be designed to select for gases other than helium. It should be understood that in some embodiments employing a multi-stage vacuum cell 404, membrane 200 may itself comprise multiple elements, such that the porosity of the portion of the portion of the membrane within a particular sub-cell is different than the porosity of the portion of the membrane within another sub-cell.

Regardless of the particular geometry of the vacuum cell (e.g., vacuum cell

400, vacuum cell 402, vacuum cell 404, or any other variation thereof), the helium extraction device will diffuse gas components (e.g., helium) from within membrane 200 into the vacuum cell, while other gas components (e.g., CH4, CO2, N₂, or the like) remain inside of the membrane coil and ultimately exit through output portion 104 of the containment tank 100 into the existing infrastructure (a pipeline, collection station, storage tank, or the like).

As noted previously, the containment tank 100 may include one or more ports 110. One such port 110 shown in Figures 4A4C comprises a vacuum port 412, from which gases may be extracted from vacuum cell 400. Similarly, Figure 4B illustrates another vacuum port 414 from which gases may be extracted from vacuum cell 402. Notably, because vacuum cell 402 is not simply the interior volume of the

containment tank 100, a separate connection must be established from vacuum cell 402 to vacuum port 414. Figure 4C illustrates the same architecture for vacuum port 414, although in Figure 4C, vacuum port 414 only extracts gases from a single sub- cell (vacuum ports 416 and 418 perform similar functions from the other sub-cells illustrated in Figure 4C). To extract gas from a vacuum cell, a compression system or similar device imparts a lower pressure which causes evacuation of the helium (and any other gases) through the vacuum port. The compression system may

subsequently compress the helium into one or more storage tanks.

Other ports 110 provided on the containment tank 100 may not be vacuum ports (in that they do not apply a lower pressure), and may have different

configurations enabling different functions. For instance, a port 420, shown in Figure 4A and of which there may be many, may comprise a sensor port, and may not be permeable to gas from within the vacuum cell, but may enable measurement of, for example, temperature or pressure within the containment tank 100. Yet another port 422 may be designed for extraction of small samples of gas from within the vacuum cell and may have fail-safe features designed to prevent large-scale evacuation of gas from within the vacuum cell or entrance of gases into the vacuum cell from the outside environment. The samples may be used for gas compositional analysis and may enable such analysis without causing undue environmental changes within the vacuum cell. Yet other ports may comprise a temperature port or a pressure port, which may be used to modify the environment within the vacuum cell or a sub-cell thereof (in embodiments in which the cooling system is not located within the containment tank 100 itself. In some embodiments, a port may be used to connect to a helium monitoring device located within the containment tank 200. In this regard, the helium monitoring device, which may essentially comprise an ion pump connected to a quartz glass flange (or other permeable membrane), can measure helium efficiency via an ion current of helium that passes through the flange.

By continually evacuating the vacuum cell (or sub-cells), the pressure outside of the membrane 200 remains low, which promotes diffusion of helium through the membrane 200 and into the vacuum cell (or sub-cells). Accordingly, the vacuum cells are designed to withstand a strong pressure and concentration gradient, which maximizes the diffusion of helium out of the source gas stream via the membrane.

Helium Removal and Storage

Turning now to Figure 5, a system for helium removal and storage is illustrated. When helium is extracted using any of the example embodiments contemplated above, that helium may be captured in a vacuum cell. Subsequently, the helium may be removed from the vacuum cell using a compression system 502 and one or more storage tanks 504. In some embodiments, the compression system 502 includes a compressor, while in other embodiments, it may also include a turbo pump to increase the pressure of helium and improve the effectiveness of the compressor.

When connected to a vacuum port, the compression system 502 reduces the pressure in the vacuum cell (which in turn reduces the pressure on the back or helium extraction device side of the pump) and then compresses and causes transfer of the extracted gas to a storage tank 504 (similar procedures are used commonly to make commercially available compressed gas cylinders). The helium in the storage tank may thus be pressurized to reduce its volume and promote more efficient helium transportation. This storage tank 504 may in some embodiments comprise a gas storage tank (such as a torpedo or the like), although one or more other gas storage chambers of varying size could be used, and may be selected based on the throughput with which helium is removed from the vacuum cell. In many embodiments, the storage tanks may comprise helium gas cylinders that are DOT rated to 3000psi.

It should be understood that although the description above relates to extraction of helium or other gas components from a source gas stream, the inventors also contemplate the extraction of helium from other resource extraction sources. For instance, helium may also be extracted from oil using the helium extraction device described above. To do this, a source oil stream may be routed into a gas-liquid separator to separate gas components from the oil stream. The oil emerging from the gas-liquid separator may continue to its destination, while the separated gas components constitute the source gas stream described above.

Operations for Extracting Helium from a Source Gas Stream Turning now to Figure 6, example operations are illustrated that may be performed by an embodiment of the helium extraction device to extract helium from a source gas stream.

In operation 602, the helium extraction device may include means, such as input portion 102 of containment tank 100, for connecting to and receiving a source gas stream from a transmission line. It should be understood that in some

embodiments, the source gas stream may be pretreated in some fashion to improve the resilience of the membrane 200. For instance, a dehydration element may be added between the transmission line and the containment tank 100 to remove water from the gas stream before exposing the stream to membrane 20. This dehydration element may comprise a glycol dehydrator, a membrane-dehydrator (e.g., a graphene oxide membrane permeable only to water), or any other such dehydration element as may be understood by one having ordinary skill in the art. While the dehydration element may be located outside the helium extraction device (thus dehydrating source gas before it enters the containment tank 100), in some embodiments the dehydration element may comprise an initial stage of the helium extraction device itself. In yet other embodiments, the helium extraction device may be connected to a transmission line located downstream of a preexisting dehydrator utilized added to the transmission line for another purpose (e.g., to mitigate damage to a compression station).

In operation 604, the helium extraction device may include means, such as blank-off gasket 302, for conveying the source gas stream into a membrane housed within the containment tank of the helium extraction device, wherein the membrane is permeable to helium and substantially impermeable to other gas components of the source gas stream. In some embodiments, the temperature of the membrane may be maintained or manipulated by the cooling system (e.g., using Peltier plates).

In operation 606, the helium extraction device may include means, such as compression system 502, for applying a lower pressure to a vacuum cell surrounding the membrane 200. In some embodiments, the combination of the permeability and temperature of the membrane and the pressure differential between the vacuum cell and the membrane, coupled with the pressure differential between the vacuum cell and the membrane, may cause fractionation of the source gas stream and permeation of helium from the source gas stream through the membrane 200 into the vacuum cell. In other embodiments, this effect may be caused with a subset of these precursors (e.g., merely one or more of porosity, temperature, and pressure need be modulated to achieve the desired effect in some circumstances). In some embodiments, the helium extraction device may further include means, such as a PSA mechanism that can be valved off, configured to extract argon (e.g., argon-40) from the permeate gas.

In operation 608, the helium extraction device may include means, such as a vacuum port 412 and/or compression system 502, for evacuating helium from the vacuum cell into a storage tank (e.g., storage tank 504). In some embodiments, the helium in the storage tank may be compressed and sold to helium distributors (e.g., Air Liquide, Air Gas, Praxair, or the like). In other embodiments, the helium in the storage tank may be further refined and sold directly to end users. It should be understood that while some applications using helium require highly purified helium others (e.g., helium balloons) do not, so even crude helium may be sold directly to some end users.

In operation 610, the helium extraction device may include means, such as output portion 104 of the containment tank 100, for exhausting the remaining components of the source gas stream to the transmission line.

Accordingly, embodiments of the helium extraction device disclosed herein can efficiently extract helium within a flow-through design. Moreover, because the transmission line is the membrane itself, these embodiments can theoretically process 100% of the natural gas (depending on blank-off gasket and containment tank geometry). This provides the ability to develop large economic supplies of helium from low helium concentration wells, pipelines, or gas-storage fields. Moreover, the cooling system provides the fundamental benefits of cryogenic and membrane technologies, but without the economic or efficiency barriers of full cryogenic freezing, as required by other helium extraction technologies.

Many modifications and other embodiments of the inventions set forth herein will come to mind to one skilled in the art to which these inventions pertain having the benefit of the teachings presented in the foregoing descriptions and the associated drawings. Therefore, it is to be understood that the inventions are not to be limited to the specific embodiments disclosed and that modifications and other embodiments are intended to be included within the scope of the appended claims. Moreover, although the foregoing descriptions and the associated drawings describe example

embodiments in the context of certain combinations of elements and/or functions, it should be appreciated that different combinations of elements and/or functions may be provided by alternative embodiments without departing from the scope of the appended claims. In this regard, for example, different combinations of elements and/or functions than those explicitly described above are also contemplated as may be set forth in some of the appended claims. Although specific terms are employed herein, they are used in a generic and descriptive sense only and not for purposes of limitation.

Claims

WHAT IS CLAIMED IS:

1. A helium extraction device comprising:

a containment tank having an input portion and an output portion, wherein the input portion is configured to connect to a source gas transmission line for receiving a source gas stream and the output portion is configured to connect to the source gas transmission line for exhausting remaining components of the source gas stream after extraction of helium;

a membrane housed entirely within the containment tank, the membrane permeable to helium and substantially impermeable to other gas components of the source gas stream;

a cooling system configured to modulate a temperature of the membrane;

a vacuum cell surrounding the membrane;

a compression system configured to reduce the pressure within the vacuum cell and extract gas from the vacuum cell; and

a storage tank connected to the vacuum cell and configured to receive the extracted gas.

2. The helium extraction device of claim 1 , wherein the membrane comprises one or more tubes connecting a first blank-off gasket and a second blank- off gasket, wherein the first blank-off gasket is adjacent to the input portion and the second blank-off gasket is adjacent to the output portion.

3. The helium extraction device of claim 2, further comprising one or more bulkhead connectors disposed within the first blank-off gasket, wherein the bulkhead connectors are configured to convey source gas from the input portion into the membrane.

4. The helium extraction device of claim 2, further comprising one or more bulkhead connectors disposed within the second blank-off gasket, wherein the bulkhead connectors are configured to exhaust gas from the membrane to the output portion.

5. The helium extraction device of claim 2, wherein the one or more tubes are coiled, twisted, or packed to increase a surface to volume ratio of the membrane.

6. The helium extraction device of any of claims 1 to 5, wherein the cooling system includes one or more Peltier plates.

7. The helium extraction device of claim 6, wherein the cooling system further includes a cooling system controller.

8. The helium extraction device of claim 7, wherein the cooling system controller is disposed outside the containment tank.

9. The helium extraction device of claim 6, wherein the cooling system further includes a thermocouple.

10. The helium extraction device of any of claims 1 to 9, wherein the vacuum cell comprises a volume defined by interior surfaces of the containment tank and exterior surfaces of the membrane.

1 1. The helium extraction device of claim 10, further comprising:

a port via which the compression system removes the gases from the vacuum cell.

12. The helium extraction device of any of claims 1 to 1 1, wherein the vacuum cell comprises a self-contained tank within the containment tank.

13. The helium extraction device of claim 12, wherein the containment tank further includes a pressure-swing adsorption (PSA) mechanism configured to remove additional gases or further purify helium.

14. The helium extraction device of any of claims 1 to 13, wherein the vacuum cell comprises a plurality of sub-cells.

15. The helium extraction device of claim 14, wherein the plurality of sub- cells include respective membrane portions.

16. The helium extraction device of claim 14, wherein the plurality of sub- cells include respective ports via which the compression system removes gases.

17. The helium extraction device of any of claims 1 to 16, wherein the compression system includes a compressor and a turbopump.

18. A gas extraction device comprising:

a containment tank having an input portion and an output portion, wherein the input portion is configured to connect to a source gas transmission line for receiving a source gas stream and the output portion is configured to connect to the source gas transmission line for exhausting remaining components of the source gas stream after extraction of a first gas;

a membrane housed entirely within the containment tank, the membrane permeable to the first gas and substantially impermeable to other gas components of the source gas stream;

a cooling system configured to modulate a temperature of the membrane;

a vacuum cell surrounding the membrane;

19. A method for extracting helium from a source gas stream using a helium extraction device, the method comprising: receiving, by the helium extraction device, a source gas stream from a transmission line connected to an input portion of a containment tank of the helium extraction device;

conveying the source gas stream into a membrane housed within the containment tank of the helium extraction device, wherein the membrane is permeable to helium and substantially impermeable to other gas components of the source gas stream.

reducing a pressure in a vacuum cell surrounding the membrane, wherein the combination of the permeability of the membrane, the temperature of the membrane, and the pressure differential between the vacuum cell and the membrane cause fractionation of the source gas stream and permeation of helium from the source gas stream through the membrane into the vacuum cell;

evacuating the vacuum cell to transfer permeated helium into a storage tank; and

exhausting remaining components of the source gas stream to the transmission line via an output portion of the containment tank.

20. The method of claim 19, further comprising:

reducing, by a cooling system, the temperature of the membrane to increase selectivity of the helium extraction device for helium.

21. The method of either of claims 19 or 20, further comprising:

modulating, by a cooling system, the temperature of the membrane to increase selectivity of the helium extraction device for other gas components.

22. The method of any of claims 19 to 21, further comprising:

reducing, by a compression system, pressure in the vacuum cell to increase selectivity of the helium extraction device for helium.

23. The method of any of claims 19 to 22, further comprising:

concentrating, by a pressure swing adsorption (PSA) mechanism, permeated gas components. The method of any of claims 19 to 23, further comprising:

receiving an oil stream; and

removing, by an gas-liquid separator, gas components from the oil wherein the source gas stream comprises the removed gas components.