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CN-122006408-A - Helium recovery system and helium recovery method

CN122006408ACN 122006408 ACN122006408 ACN 122006408ACN-122006408-A

Abstract

The invention provides a helium recovery system and a helium recovery method, wherein the helium recovery system comprises 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. According to the invention, the two-section membrane separation is arranged in the primary membrane separation unit, and the membrane separators with different properties are adopted, so that the connection mode of the two-section membrane separators is optimized, the recovery rate of helium is improved, high-purity helium is obtained, the method is particularly suitable for treating natural gas with low helium concentration, meanwhile, the device construction cost and the process operation cost are greatly reduced, and the economic benefit of helium recovery is improved.

Inventors

  • ZHANG ZHE
  • Liang Yuejiu
  • Chen Siding
  • HUANG JIAN
  • ZHANG LEI
  • WANG CHUNYAN

Assignees

  • 中国石油天然气集团有限公司

Dates

Publication Date
20260512
Application Date
20241112

Claims (18)

  1. 1. The helium recovery system comprises 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; The first-stage one-stage membrane separator is provided with a feed gas inlet, a non-permeate gas outlet of the first-stage one-stage membrane separator is connected with an inlet of the first-stage two-stage membrane separator, and a permeate gas outlet of the first-stage two-stage membrane separator is connected with an inlet of the vacuum pump; The permeate gas outlet of the secondary membrane separator is connected with the inlet of the tertiary membrane separator, the permeate gas outlet of the tertiary membrane separator is connected with the inlet of the pressure swing adsorption unit, and the pressure swing adsorption unit is provided with a product gas outlet.
  2. 2. The helium recovery system of claim 1, wherein said primary membrane separator has a higher permeability than said primary secondary membrane separator and a lower selectivity than said primary secondary membrane separator.
  3. 3. The helium recovery system of claim 1, wherein said primary, primary membrane separator is selected from polysulfone membrane separators and said primary, secondary membrane separator is selected from polyimide membrane separators.
  4. 4. The helium recovery system of claim 1, wherein a separation coefficient of a secondary membrane separator and a tertiary membrane separator is identical to a separation coefficient of a primary secondary membrane separator, said secondary membrane separator and said tertiary membrane separator being selected from polyimide membrane separators.
  5. 5. The helium recovery system of claim 1, further comprising a primary compressor, wherein the permeate outlet of the primary membrane separator and the outlet of the vacuum pump are connected to the primary compressor before being connected to the inlet of the secondary membrane separator.
  6. 6. The helium recovery system of claim 1, further comprising a secondary compressor, wherein a permeate outlet of the secondary membrane separator is connected to the secondary compressor and then to an inlet of the tertiary membrane separator.
  7. 7. The helium recovery system of claim 1, further comprising a three-stage compressor, wherein a permeate outlet of the three-stage membrane separator is connected to the three-stage compressor before being connected to an inlet of the pressure swing adsorption unit.
  8. 8. The helium recovery system of claim 1, wherein said primary two-stage membrane separator is provided with a non-permeate gas discharge outlet.
  9. 9. The helium recovery system of claim 1, wherein the non-permeate outlet of the secondary membrane separator and/or the non-permeate outlet of the tertiary membrane separator is connected to the inlet of the primary one-stage membrane separator.
  10. 10. The helium recovery system of claim 7, further comprising one or more of a dehydrogenation unit, a deoxygenation unit, and a temperature swing dehumidification unit, wherein an outlet of said three-stage compressor is sequentially connected to one or more of the dehydrogenation unit, the deoxygenation unit, and the temperature swing dehumidification unit before being connected to an inlet of said pressure swing adsorption unit.
  11. 11. A helium recovery method implemented with the helium recovery system of any one of claims 1-10, said helium recovery method comprising the steps of: The raw material gas containing helium enters a first-stage membrane separator for separation to obtain a first-stage permeation gas and a first-stage non-permeation gas; The first-stage non-permeate gas enters a first-stage second-stage membrane separator for separation to obtain a first-stage second-stage permeate gas and a first-stage second-stage non-permeate gas; Combining the depressurized first-stage second-stage permeation gas with the first-stage permeation gas, and entering a second-stage membrane separator to obtain a second-stage permeation gas and a second-stage non-permeation gas; The secondary permeate gas enters a tertiary membrane separator for separation to obtain tertiary permeate gas and tertiary non-permeate gas; and the three-stage permeation gas enters a pressure swing adsorption unit to be subjected to pressure swing adsorption, so that helium product gas is obtained.
  12. 12. The helium recovery method of claim 11, wherein said vacuum pump is configured to pump said primary two-stage permeate gas to a negative pressure of-0.1 to 0mpa.
  13. 13. The helium recovery method according to claim 11, wherein the mixed gas of the primary second-stage permeate gas and the primary first-stage permeate gas is compressed by a primary compressor to a pressure which is 0.1-0.2MPa higher than the pressure of the feed gas, and then enters a secondary membrane separator.
  14. 14. The helium recovery method of claim 11, wherein said secondary permeate gas is compressed by a compressor to a pressure between 0.1 and 0.2MPa above the inlet pressure of the primary membrane separator before entering said tertiary membrane separator.
  15. 15. The helium recovery method of claim 11, wherein said three-stage permeate stream is compressed by a compressor to a pressure of 1.8-2.5Mpa before entering the next unit.
  16. 16. The helium recovery method of claim 11, wherein an operating temperature of said helium recovery system is controlled between 40-80 ℃.
  17. 17. The helium recovery method of claim 11, wherein a volume fraction of helium in said feed gas is 0.0005-0.001%, said feed gas further comprising one or a combination of two or more of nitrogen, methane, ethane, propane, and hydrogen sulfide.
  18. 18. The helium recovery method according to claim 11, wherein the flow rate of the raw material gas is 50000-200000Nm 3 /h and the pressure is 5-10MPa.

Description

Helium recovery system and helium recovery method Technical Field The application relates to the technical field of gas separation, in particular to a helium recovery system and a helium recovery method. Background Natural gas is an important clean energy source in the current age, and has important significance in the aspects of living generation, energy conservation and emission reduction. In order to realize the qualified output of natural gas and high value-added products produced by a gas field, gas well streams are required to be treated, and the gas well streams comprise various links such as gas-liquid separation, natural gas dehydration, desulfurization/decarbonization, condensate recovery, natural gas helium stripping and the like, and the essence of the gas process is a gas purification process, namely impurity removal or high value-added component recovery. At present, the natural gas processing mainly adopts a chemical reaction method and a rectification method, a large amount of heat or cold is required to be supplied, the energy consumption is high, the operation cost is high, the flow is complex, and the one-time investment is high. In recent years, the membrane separation technology is gradually applied to the field of natural gas treatment and processing, and has good application prospect. The membrane gas separation technology utilizes the difference of permeation rates of different gas components through membrane materials under the drive of pressure difference to realize gas separation. Taking the helium extraction process of the membrane as an example, high-pressure helium-containing natural gas is taken as raw material gas to enter the membrane assembly, helium belongs to fast gas, can pass through membrane materials at high speed to become low-pressure product gas (permeate gas), and other gases such as methane belong to slow gas and are enriched (tail gas) on the high-pressure permeation residual side. The membrane separation can be used for realizing the treatment processes of natural gas dehydration, desulfurization/decarbonization, condensate recovery, natural gas helium extraction and the like at normal temperature, and the whole process does not need heating, and has the advantages of simple flow, small equipment occupation area, low operation cost and the like. In addition, the membrane separation technology can also be used for the separation processes of flue gas carbon dioxide capture, biogas decarburization purification, synthesis gas carbon dioxide removal and the like, and is a novel gas separation technology with the most development prospect at present. The driving force of the gas permeation membrane is the gas partial pressure difference between the raw material side and the permeation side, and the pressure difference between the two sides of the membrane is mainly increased by increasing the pressure of the raw material gas side through a raw material gas compressor in the current engineering. In fact, the pressure ratio on the feed side and permeate side is also an important factor affecting the membrane separation rate and effectiveness. The pressure difference of the two sides of the membrane can be greatly increased by increasing the pressure of the raw material through the raw material gas compressor, but the effect of increasing the pressure ratio is not obvious, and the effect of membrane separation is limited to a certain extent. Disclosure of Invention In order to solve the technical problems, the invention aims to provide a helium recovery system and a helium recovery method. In order to achieve the aim, the invention provides a helium recovery system, which comprises a primary first-stage membrane separator, a primary second-stage membrane separator, a vacuum pump, a secondary membrane separator, a tertiary membrane separator and a pressure swing adsorption unit, wherein the separation coefficient of the primary first-stage membrane separator is lower than that of the primary second-stage membrane separator; The first-stage one-stage membrane separator is provided with a feed gas inlet, a non-permeate gas outlet of the first-stage one-stage membrane separator is connected with an inlet of the first-stage two-stage membrane separator, and a permeate gas outlet of the first-stage two-stage membrane separator is connected with an inlet of the vacuum pump; The permeate gas outlet of the secondary membrane separator is connected with the inlet of the tertiary membrane separator, the permeate gas outlet of the tertiary membrane separator is connected with the inlet of the pressure swing adsorption unit, and the pressure swing adsorption unit is provided with a product gas outlet. In the helium recovery system, preferably, the first-stage membrane separator has higher permeability than the first-stage second-stage membrane separator, and the first-stage membrane separator has lower selectivity than the first-stage second-stage membrane separator. In the helium