Helium recovery system and helium recovery method

Abstract

The invention provides a helium recovery system and a helium recovery method. The helium recovery system comprises a first-stage first-section membrane separator, a first-stage second-section membrane separator, a vacuum pump, a second-stage membrane separator, a third-stage membrane separator and a pressure swing adsorption unit, wherein the separation coefficient of the first-stage first-section membrane separator is lower than that of the first-stage second-section membrane separator. Two-stage membrane separation is arranged in the first-stage membrane separation unit, membrane separators with different properties are adopted, and the connection mode of the two-stage membrane separators is optimized, so that the recovery rate of helium is increased, high-purity helium is obtained, and the system is particularly suitable for treating natural gas with relatively low helium concentration; meanwhile, the device building cost and the process operation cost are greatly reduced, and the economic benefit of helium recovery is improved.

Description

Technical Field

[0001] This application relates to the field of gas separation technology, and more specifically, to a helium recovery system and a helium recovery method. Background Technology

[0002] Natural gas is an important clean energy source in the modern era, playing a significant role in production, daily life, energy conservation, and emission reduction. To ensure the qualified export of natural gas and its high-value-added products from gas fields, the gas well fluids must undergo processing, including gas-liquid separation, natural gas dehydration, desulfurization / decarbonization, condensate recovery, and helium extraction. Essentially, this is a gas purification process, removing impurities or recovering high-value-added components. Currently, natural gas processing mainly employs chemical reaction methods and distillation, requiring large external heat or cold supplies, resulting in high energy consumption, high operating costs, complex processes, and substantial initial investments. In recent years, membrane separation technology has been increasingly applied in the field of natural gas processing, demonstrating promising application prospects.

[0003] Membrane gas separation technology utilizes the difference in permeation rates of different gas components through a membrane material driven by a pressure difference to achieve gas separation. Taking helium extraction via membrane as an example, high-pressure helium-containing natural gas enters the membrane module as feed gas. Helium, being a fast gas, can pass through the membrane material at high speed, becoming the low-pressure product gas (permeate gas); methane and other gases, being slower gases, are enriched on the high-pressure permeate side (tail gas). Membrane separation can be used to achieve natural gas dehydration, desulfurization / decarbonization, condensate recovery, and helium extraction at room temperature. The entire process does not require heating and has advantages such as simple process, small equipment footprint, and low operating costs. In addition, membrane separation technology can also be used for separation processes such as flue gas carbon dioxide capture, biogas decarbonization and purification, and syngas carbon dioxide removal, making it one of the most promising new gas separation technologies currently available.

[0004] The driving force for gas permeation through the membrane is the partial pressure difference between the feed side and the permeate side. Currently, in engineering, this is mainly achieved by increasing the pressure on the feed gas side using a feed gas compressor to increase the pressure difference across the membrane. However, the pressure ratio between the feed and permeate sides is also a crucial factor affecting the membrane separation rate and efficiency. While increasing the feed gas pressure using a feed gas compressor can significantly increase the pressure difference across the membrane, the effect on increasing the pressure ratio is not significant, thus limiting the membrane separation efficiency to some extent. Summary of the Invention

[0005] To address the aforementioned technical problems, the present invention aims to provide a helium recovery system and a helium recovery method.

[0006] To achieve the above objectives, the present invention provides a helium recovery system, comprising a first-stage membrane separator, a first-stage second-stage membrane separator, a vacuum pump, a second-stage membrane separator, a third-stage membrane separator, and a pressure swing adsorption unit; wherein the separation coefficient of the first-stage membrane separator is lower than that of the first-stage second-stage membrane separator.

[0007] The first-stage membrane separator is provided with a feed gas inlet; the non-permeate gas outlet of the first-stage membrane separator is connected to the inlet of the second-stage membrane separator; the permeate gas outlet of the second-stage membrane separator is connected to the inlet of the vacuum pump; the permeate gas outlet of the first-stage membrane separator and the outlet of the vacuum pump are both connected to the inlet of the second-stage membrane separator.

[0008] The permeate outlet of the secondary membrane separator is connected to the inlet of the tertiary membrane separator, and the permeate outlet of the tertiary membrane separator is connected to the inlet of the pressure swing adsorption unit. The pressure swing adsorption unit is provided with a product gas outlet.

[0009] In the above-mentioned helium recovery system, preferably, the permeability of the first-stage membrane separator is higher than that of the first-stage membrane separator, and the selectivity of the first-stage membrane separator is lower than that of the first-stage membrane separator.

[0010] In the aforementioned helium recovery system, preferably, the first-stage membrane separator is selected from a polysulfone membrane separator, and the second-stage membrane separator is selected from a polyimide membrane separator. The first-stage membrane separation unit of this invention employs both polysulfone and polyimide membrane separators. The polysulfone membrane separator is a high-permeability, low-separation-coefficient membrane separator, while the polyimide membrane separator is a low-permeability, high-separation-coefficient membrane separator.

[0011] Existing technologies use only one type of membrane separator, which cannot maximize the performance of different membrane separators. In the natural gas helium extraction process, if only a membrane separator with high permeability and low separation coefficient is used, there are many stages, high pressurization energy consumption, and a complex process. If only a membrane separator with high separation coefficient is used, although the number of stages can be reduced, the amount of membrane used in the membrane separator must be increased, the recovery rate of key components is relatively low, and the economic efficiency is poor.

[0012] This invention divides the membrane separation process of the primary membrane separation unit into two stages. The first stage uses a polysulfone membrane separator with high permeability and low separation coefficient to reduce the number of membranes used, increase the total yield of helium components, and improve the economy of the helium extraction process. The second stage uses a polyimide membrane separator with high separation coefficient to reduce the permeation of impurity gases.

[0013] In existing two-stage separation technologies, the permeate gas from the previous stage is separated in series in the latter stage. However, unlike existing technologies, the first-stage membrane separation unit of this invention sends the non-permeate gas from the first-stage membrane separator to the first-stage second-stage membrane separator, and then combines the permeate gas from the first-stage second-stage membrane separator with the permeate gas from the first-stage first-stage membrane separator into the next separation unit. This can maximize the helium yield even when the helium content is very low.

[0014] Furthermore, this invention not only employs two gas separation membranes with different performance characteristics, but also sets up a vacuum pump at the tail end of the first-stage two-stage membrane separator and uses permeate-side vacuum technology, which greatly reduces the number of membranes used and the permeation of slow gases such as methane and nitrogen, thereby reducing the energy consumption required for pressurization in the second-stage membrane separator, third-stage membrane separator, and other membrane separation processes.

[0015] In the above-mentioned helium recovery system, preferably, the separation coefficients of the secondary membrane separator and the tertiary membrane separator are consistent with the separation coefficients of the primary two-stage membrane separator; the secondary membrane separator and the tertiary membrane separator are selected from polyimide membrane separators.

[0016] In the above-mentioned helium recovery system, preferably, the helium recovery system further includes a primary compressor, and the permeate outlet of the primary membrane separator and the outlet of the vacuum pump are connected to the primary compressor and then connected to the inlet of the secondary membrane separator.

[0017] In the above-mentioned helium recovery system, preferably, the helium recovery system further includes a secondary compressor, and the permeate outlet of the secondary membrane separator is connected to the secondary compressor and then to the inlet of the tertiary membrane separator.

[0018] In the above-mentioned helium recovery system, preferably, the helium recovery system further includes a three-stage compressor, and the permeate outlet of the three-stage membrane separator is connected to the three-stage compressor and then to the inlet of the pressure swing adsorption unit.

[0019] In the above-mentioned helium recovery system, preferably, the first-stage two-stage membrane separator is provided with a non-permeable gas outlet.

[0020] In the above-mentioned helium recovery system, preferably, the non-permeable gas outlet of the secondary membrane separator is connected to the inlet of the primary membrane separator to further recover helium from the non-permeable gas of the secondary separation membrane.

[0021] In the above-mentioned helium recovery system, preferably, the non-permeable gas outlet of the three-stage membrane separator is connected to the inlet of the first-stage membrane separator to further recover helium from the non-permeable gas of the three-stage separation membrane.

[0022] In the above-mentioned helium recovery system, preferably, the desorbed gas outlet of the pressure swing adsorption unit is connected to the inlet of the first-stage membrane separator.

[0023] In the aforementioned helium recovery system, preferably, the helium recovery system further includes one or more of a dehydrogenation unit, a deoxygenation unit, and a variable-temperature dehumidification unit; the outlet of the three-stage compressor is sequentially connected to one or more of the dehydrogenation unit, the deoxygenation unit, and the variable-temperature dehumidification unit, and then connected to the inlet of the pressure swing adsorption unit to remove hydrogen, oxygen, and moisture from the permeate gas of the three-stage separation membrane. Water is discharged outside the boundary, and dry gas then enters the pressure swing adsorption unit. More preferably, the dehydrogenation unit and the deoxygenation unit employ catalytic combustion, with manganese oxide as the catalyst.

[0024] According to a specific embodiment of the present invention, preferably, the above-mentioned helium recovery system includes a primary membrane separation unit, a secondary membrane separator, a tertiary membrane separator, a pressure swing adsorption unit, a primary compressor, a secondary compressor, and a tertiary compressor. The primary membrane separation unit includes a primary first-stage membrane separator, a primary second-stage membrane separator, and a vacuum pump. The separation coefficient of the primary first-stage membrane separator is lower than that of the primary second-stage membrane separator, and the separation coefficients of the secondary and tertiary membrane separators are consistent with those of the primary second-stage membrane separator. The primary first-stage membrane separator is selected from polysulfone membrane separators, and the primary second-stage, secondary, and tertiary membrane separators are selected from polyimide membrane separators.

[0025] The non-permeate outlet of the first-stage membrane separator is connected to the inlet of the first-stage second-stage membrane separator, and the permeate outlet of the first-stage second-stage membrane separator is connected to the inlet of the vacuum pump; both the permeate outlet of the first-stage membrane separator and the outlet of the vacuum pump are connected to the first-stage compressor and then to the inlet of the second-stage membrane separator.

[0026] The permeate outlet of the secondary membrane separator is connected to the secondary compressor and then to the inlet of the tertiary membrane separator. The permeate outlet of the tertiary membrane separator is connected to the tertiary compressor and then to the inlet of the pressure swing adsorption unit.

[0027] The present invention also provides a helium recovery method, which is implemented using the above-mentioned helium recovery system, and the helium recovery method includes the following steps:

[0028] The feed gas containing helium enters the first-stage membrane separator for separation, resulting in first-stage permeate gas and first-stage non-permeate gas;

[0029] The first-stage non-permeable gas enters the first-stage two-stage membrane separator for separation, resulting in first-stage two-stage permeable gas and first-stage two-stage non-permeable gas; simultaneously, a vacuum pump is used to reduce the pressure of the first-stage two-stage permeable gas.

[0030] The depressurized first-stage second-stage permeate gas is combined with the first-stage first-stage permeate gas and enters the second-stage membrane separator to obtain second-stage permeate gas and second-stage non-permeate gas;

[0031] The secondary permeate gas enters the tertiary membrane separator for separation, yielding tertiary permeate gas and tertiary non-permeate gas;

[0032] The three-stage permeation gas enters the pressure swing adsorption unit for pressure swing adsorption to obtain helium product gas.

[0033] In the above helium recovery method, preferably, the vacuum pump draws the first-stage second-stage permeation gas to a negative pressure of -0.1 to 0 MPa, more preferably -0.08 MPa.

[0034] This invention uses a vacuum pump to create negative pressure on the permeate side of the second-stage membrane separator in the primary membrane separation unit, reducing the partial pressure of helium on the permeate side and increasing the helium permeate ratio. This achieves a high helium recovery rate while reducing the permeation of impurity gases, thus ensuring a high helium recovery rate for the primary membrane, while also achieving a higher helium concentration and requiring fewer membranes.

[0035] In the above helium recovery method, preferably, the mixed gas after the first-stage second-stage permeate gas and the first-stage first-stage permeate gas are combined is compressed by the first-stage compressor to a pressure 0.1-0.2 MPa higher than the pressure of the feed gas (inlet of the first-stage membrane separator) before entering the second-stage membrane separator.

[0036] In the above-mentioned helium recovery method, preferably, the secondary permeate gas is compressed by a compressor (secondary compressor) to a pressure 0.1-0.2 MPa higher than the inlet pressure of the first-stage membrane separator, and then enters the tertiary membrane separator.

[0037] In the above-mentioned helium recovery method, preferably, the three-stage permeate gas is compressed by a compressor (three-stage compressor) to a pressure of 1.8-2.5 MPa before entering the next unit.

[0038] In the above-mentioned helium recovery method, preferably, the first-stage second-stage permeation gas is directly discharged.

[0039] In the above-mentioned helium recovery method, preferably, the operating temperature of the helium recovery system is controlled at 40-80℃, more preferably 60-70℃, and even more preferably 65℃.

[0040] In the above-mentioned helium recovery method, preferably, the volume fraction of helium in the raw material gas is 0.0005-0.001%; ​​the raw material gas also contains one or more of nitrogen, methane, ethane, propane, and hydrogen sulfide; more preferably, the volume fraction of methane in the raw material gas is 0.8-1%.

[0041] In the above-described helium recovery method, preferably, the flow rate of the raw material gas is 50,000-200,000 Nm³. 3The flow rate of the raw material gas is 100,000 Nm³ / h, and the pressure is 5-10 MPa; more preferably, the flow rate of the raw material gas is 100,000 Nm³ / h. 3 / h, pressure is 8MPa.

[0042] The technical solution provided by this invention has the following beneficial effects:

[0043] This invention improves helium recovery rate and obtains high-purity helium by setting up a two-stage membrane separation unit in the primary membrane separation unit and using membrane separators with different properties, and optimizing the connection method of the two membrane separators. It is especially suitable for processing natural gas with low helium concentration. At the same time, it significantly reduces the equipment construction cost and process operation cost, and improves the economic benefits of helium recovery. Attached Figure Description

[0044] Figure 1 This is a structural flowchart of the helium recovery system according to Embodiment 1 of the present invention;

[0045] Figure 2 The diagram shows the structural flow of the helium recovery system in Comparative Example 1.

[0046] Explanation of icon numbers:

[0047] 11. First-stage membrane separator; 12. First-stage membrane separator; 13. Vacuum pump; 2. Second-stage membrane separator; 3. Third-stage membrane separator; 4. Pressure swing adsorption unit; 5. First-stage compressor; 6. Second-stage compressor; 7. Third-stage compressor. Detailed Implementation

[0048] In order to provide a clearer understanding of the technical features, objectives and beneficial effects of the present invention, the technical solution of the present invention will now be described in detail below, but it should not be construed as limiting the scope of implementation of the present invention.

[0049] Example 1

[0050] This embodiment provides a helium recovery system, such as Figure 1 As shown, the helium recovery system includes a first-stage membrane separator 11, a first-stage second-stage membrane separator 12, a vacuum pump 13, a second-stage membrane separator 2, a third-stage membrane separator 3, a pressure swing adsorption unit 4, a first-stage compressor 5, a second-stage compressor 6, and a third-stage compressor 7.

[0051] The separation coefficient of the first-stage membrane separator 11 is lower than that of the first-stage membrane separator 12, while the separation coefficients of the second-stage membrane separator 2 and the third-stage membrane separator 3 are the same as those of the first-stage membrane separator 12. The first-stage membrane separator 11 is selected from a polysulfone membrane separator, and the first-stage membrane separator 12, the second-stage membrane separator 2, and the third-stage membrane separator 3 are selected from polyimide membrane separators.

[0052] The first-stage membrane separator 11 is provided with a feed gas inlet. The non-permeable gas outlet of the first-stage membrane separator 11 is connected to the inlet of the first-stage second-stage membrane separator 12. The permeable gas outlet of the first-stage second-stage membrane separator 12 is connected to the inlet of the vacuum pump 13. The first-stage second-stage membrane separator 12 is provided with a non-permeable gas outlet.

[0053] The permeate outlet of the first-stage membrane separator 11 and the outlet of the vacuum pump 13 are both connected to the first-stage compressor 5 and then to the inlet of the second-stage membrane separator 2.

[0054] The permeate outlet of the secondary membrane separator 2 is connected to the secondary compressor 6 and then to the inlet of the tertiary membrane separator 3. The non-permeate outlet of the secondary membrane separator 2 is connected to the inlet of the primary membrane separator 11.

[0055] The permeate outlet of the three-stage membrane separator 3 is connected to the three-stage compressor 7 and then to the inlet of the pressure swing adsorption unit 4; the non-permeate outlet of the three-stage membrane separator 3 is connected to the inlet of the first-stage membrane separator 11.

[0056] The pressure swing adsorption unit 4 is provided with a product gas outlet, and the desorption gas outlet of the pressure swing adsorption unit 4 is connected to the permeate gas outlet of the first-stage membrane separator 11.

[0057] Example 2

[0058] This embodiment provides a helium recovery system, which is the same as that in Embodiment 1, except that the helium recovery system in this embodiment also includes a dehydrogenation unit, a deoxygenation unit, and a variable temperature dehumidification unit; wherein, the permeate outlet of the three-stage membrane separator 3 is connected to the three-stage compressor 7 and then sequentially connected to the dehydrogenation unit, the deoxygenation unit, and the variable temperature dehumidification unit for processing before being connected to the inlet of the pressure swing adsorption unit 4.

[0059] Example 3

[0060] This embodiment provides a helium recovery method, which is implemented using the helium recovery system of Embodiment 1. The feed gas processed in this embodiment is natural gas, and the composition of the natural gas is: helium gas fraction 0.05% (concentration 500ppm) and methane volume fraction 0.9995%.

[0061] The helium recovery method in this embodiment includes the following steps:

[0062] The flow rate of the raw gas is controlled at 100,000 Nm. 3 The feed gas is separated into a first-stage membrane separator 11 at a pressure of 8 MPa and a temperature of 40°C to obtain first-stage permeate gas and first-stage non-permeate gas. After the feed gas enters the helium recovery system, the operating temperature of the helium recovery system is 65°C.

[0063] The non-permeable gas from the first stage enters the first-stage-second-stage membrane separator 12 for separation, resulting in first-stage-second-stage permeable gas and first-stage-second-stage non-permeable gas. The first-stage-second-stage permeable gas is discharged. At the same time, a vacuum pump is used to draw the first-stage-second-stage permeable gas to a negative pressure of -0.08MPa.

[0064] The first-stage second-stage permeate gas, which is drawn under negative pressure, is combined with the first-stage first-stage permeate gas. The combined gas mixture is compressed to a pressure of 8.1 MPa by the first-stage compressor 5, and then enters the second-stage membrane separator 2 to obtain second-stage permeate gas and second-stage non-permeate gas. The second-stage non-permeate gas is combined with the feed gas and reused.

[0065] The secondary permeate gas is compressed to a pressure of 8.1 MPa by the secondary compressor 6, and then enters the tertiary membrane separator 3 for separation to obtain tertiary permeate gas and tertiary non-permeate gas; the tertiary non-permeate gas is combined with the primary permeate gas and reused.

[0066] The third-stage permeate gas is compressed to a pressure of 1.8 MPa by the third-stage compressor 7, and then enters the pressure swing adsorption unit 4 for pressure swing adsorption to obtain helium product gas and desorption gas. The desorption gas is combined with the first-stage permeate gas and reused.

[0067] Comparative Example 1

[0068] This comparative example provides a helium recovery system and method, such as Figure 2 As shown, the helium recovery system includes: a primary membrane separator, a secondary membrane separator, a tertiary membrane separator, a quaternary membrane separator, and a pressure swing adsorption unit connected in series; the permeate outlet of each membrane separator is connected to the inlet of the next membrane separator after passing through a compressor, and the permeate outlet of the quaternary membrane separator is connected to the pressure swing adsorption (purification) unit after passing through a compressor; all membrane separators are polyimide membrane separators.

[0069] The helium recovery method in this comparative example is achieved through... Figure 2 An embodiment of the helium recovery system shown includes the following steps:

[0070] The flow rate of the raw gas is controlled at 100,000 Nm. 3The feed gas is separated at a pressure of 8 MPa and a temperature of 40°C into a primary membrane separator to obtain primary permeate and primary non-permeate gas. The primary non-permeate gas is discharged, and the primary permeate gas is compressed to 8.1 MPa by a compressor before entering a secondary membrane separator to obtain secondary permeate and secondary non-permeate gas. The secondary non-permeate gas is combined with the feed gas and reused. The secondary permeate gas is compressed to 1.8 MPa by a compressor before entering a tertiary membrane separator to obtain tertiary permeate and tertiary non-permeate gas. The tertiary non-permeate gas is combined with the primary permeate gas and reused. The tertiary permeate gas is compressed to 1.8 MPa by a compressor before entering a quaternary membrane separator to obtain quaternary permeate and quaternary non-permeate gas. The quaternary non-permeate gas is combined with the primary permeate gas and reused. The quaternary permeate gas is compressed to 1.8 MPa by a compressor before entering a pressure swing adsorption unit to obtain helium product gas and desorption gas. The desorption gas is combined with the primary permeate gas and reused.

[0071] The process material list for Example 3 is shown in Table 1, and the process material list for Comparative Example 1 is shown in Table 2.

[0072] Table 1. Process Material List for Example 3

[0073]

[0074]

[0075] Table 2. Process Material List for Comparative Example 1

[0076]

[0077] Table 3 shows the cost of the helium recovery system of Example 1 and Comparative Example 1.

[0078] Table 3 Cost of Helium Recovery System

[0079]

[0080]

[0081] As shown in Table 1, the helium recovery system of this application can achieve a helium recovery rate of over 98% for helium-containing natural gas with a helium concentration of 500 ppm or higher. As shown in Table 3, under the same operating conditions, the recovery system of this invention, when applied to helium extraction from low-concentration helium-containing natural gas, can reduce initial engineering investment by over 40%, reduce energy consumption during device operation by over 20%, and lower the cost of current helium extraction devices from 250 yuan / cubic meter to 200 yuan / cubic meter, resulting in significant economic benefits.

[0082] As can be seen from the above results, the helium recovery system of the present invention sets two stages in the first-stage membrane separation unit. The first stage uses a highly permeable membrane to permeate helium to the permeate side of the membrane with as few membranes as possible. The second stage uses a highly selective membrane to permeate helium to the permeate side as much as possible when the helium concentration is low. A vacuum pump is set in the permeate side of the first and second stages to better realize helium permeation and retain impurity gases.

Claims

1. A helium recovery system, comprising a first-stage membrane separator, a second-stage membrane separator, a vacuum pump, a second-stage membrane separator, a third-stage membrane separator, and a pressure swing adsorption (PSA) unit; wherein, The separation coefficient of the first-stage membrane separator is lower than that of the first-stage membrane separator. The first-stage membrane separator is provided with a feed gas inlet; the non-permeate gas outlet of the first-stage membrane separator is connected to the inlet of the second-stage membrane separator; the permeate gas outlet of the second-stage membrane separator is connected to the inlet of the vacuum pump; the permeate gas outlet of the first-stage membrane separator and the outlet of the vacuum pump are both connected to the inlet of the second-stage membrane separator. The permeate outlet of the secondary membrane separator is connected to the inlet of the tertiary membrane separator, and the permeate outlet of the tertiary membrane separator is connected to the inlet of the pressure swing adsorption unit. The pressure swing adsorption unit is provided with a product gas outlet.

2. The helium recovery system according to claim 1, wherein, The permeability of the first-stage membrane separator is higher than that of the first-stage membrane separator, while the selectivity of the first-stage membrane separator is lower than that of the first-stage membrane separator.

3. The helium recovery system according to claim 1, wherein, The first-stage membrane separator is selected from polysulfone membrane separators, and the second-stage membrane separator is selected from polyimide membrane separators.

4. The helium recovery system according to claim 1, wherein, The separation coefficients of the secondary and tertiary membrane separators are consistent with those of the primary two-stage membrane separator; the secondary and tertiary membrane separators are selected from polyimide membrane separators.

5. The helium recovery system according to claim 1, wherein, The helium recovery system also includes a primary compressor. The permeate outlet of the primary membrane separator and the outlet of the vacuum pump are connected to the primary compressor and then to the inlet of the secondary membrane separator.

6. The helium recovery system according to claim 1, wherein, The helium recovery system also includes a secondary compressor, and the permeate outlet of the secondary membrane separator is connected to the secondary compressor and then to the inlet of the tertiary membrane separator.

7. The helium recovery system according to claim 1, wherein, The helium recovery system also includes a three-stage compressor, and the permeate outlet of the three-stage membrane separator is connected to the three-stage compressor and then to the inlet of the pressure swing adsorption unit.

8. The helium recovery system according to claim 1, wherein, The first-stage two-stage membrane separator is equipped with a non-permeable gas outlet.

9. The helium recovery system according to claim 1, wherein, The non-permeable gas outlet of the secondary membrane separator and / or the non-permeable gas outlet of the tertiary membrane separator are connected to the inlet of the primary membrane separator.

10. The helium recovery system according to claim 7, wherein, The helium recovery system further includes one or more of a dehydrogenation unit, a deoxygenation unit, and a variable temperature dehumidification unit; the outlet of the three-stage compressor is connected in sequence to one or more of the dehydrogenation unit, the deoxygenation unit, and the variable temperature dehumidification unit, and then connected to the inlet of the pressure swing adsorption unit.

11. A helium recovery method, implemented using the helium recovery system according to any one of claims 1-10, the helium recovery method comprising the following steps: The feed gas containing helium enters the first-stage membrane separator for separation, resulting in first-stage permeate gas and first-stage non-permeate gas; The first-stage non-permeable gas enters the first-stage two-stage membrane separator for separation, resulting in first-stage two-stage permeable gas and first-stage two-stage non-permeable gas; simultaneously, a vacuum pump is used to reduce the pressure of the first-stage two-stage permeable gas. The depressurized first-stage second-stage permeate gas is combined with the first-stage first-stage permeate gas and enters the second-stage membrane separator to obtain second-stage permeate gas and second-stage non-permeate gas; The secondary permeate gas enters the tertiary membrane separator for separation, yielding tertiary permeate gas and tertiary non-permeate gas; The three-stage permeation gas enters the pressure swing adsorption unit for pressure swing adsorption to obtain helium product gas.

12. The helium recovery method according to claim 11, wherein, The vacuum pump draws the first-stage, second-stage permeation gas to a negative pressure of -0.1 to 0 MPa.

13. The helium recovery method according to claim 11, wherein, The mixed gas, formed by combining the first-stage second-stage permeate gas and the first-stage first-stage permeate gas, is compressed by the first-stage compressor to a pressure 0.1-0.2 MPa higher than the feed gas pressure before entering the second-stage membrane separator.

14. The helium recovery method according to claim 11, wherein, The secondary permeate gas is compressed by a compressor to a pressure 0.1-0.2 MPa higher than the inlet pressure of the first-stage membrane separator before entering the tertiary membrane separator.

15. The helium recovery method according to claim 11, wherein, The three-stage permeate gas is compressed by a compressor to a pressure of 1.8-2.5 MPa before entering the next unit.

16. The helium recovery method according to claim 11, wherein, The operating temperature of the helium recovery system is controlled between 40-80℃.

17. The helium recovery method according to claim 11, wherein, The volume fraction of helium in the raw material gas is 0.0005-0.001%; ​​the raw material gas also contains one or more of nitrogen, methane, ethane, propane, and hydrogen sulfide.

18. The helium recovery method according to claim 11, wherein, The flow rate of the raw gas is 50,000-200,000 Nm³. 3 / h, pressure is 5-10MPa.

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