Normal-temperature natural gas helium extraction and purification system and purification method thereof

Abstract

The invention discloses a normal-temperature natural gas helium extraction and purification system and purification method. The system comprises a first-stage membrane separator, a second-stage membrane separator, a third-stage membrane separator, a pressure swing adsorption unit and the like, helium in natural gas is primarily concentrated through the first-stage membrane separator, after impurities are removed, the natural gas enters the third-stage membrane separator to be further concentrated, and permeated gas enters the second-stage first-section membrane separator to be concentrated to be high in concentration; the helium content in the impermeable gas is extremely low, and the impermeable gas returns to a pipe network; the permeated gas of the second-stage first-section membrane separator enters a fine dehydrogenation unit and a pressure swing adsorption unit, and then high-purity helium is produced; the impermeable gas of the second-stage first-section membrane separator enters the second-stage second-section membrane separator and then returns to the system for circulation; the impermeable gas of the second-stage second-section membrane separator returns to the third-stage membrane separator for recycling; and desorbed gas of the pressure swing adsorption unit returns to an outlet of the first-stage membrane separator for circulation. According to the system, helium in natural gas is purified by adopting very low energy consumption, helium in boil off gas (BOG) in the natural gas liquefaction process can also be purified, and a very good application effect is achieved.

Description

Technical Field

[0001] The invention relates to the field of gas separation, and in particular to a room-temperature natural gas helium extraction and purification system and a purification method thereof. Background Art

[0002] With the rapid development of modern science and technology, helium, as a non-renewable rare gas, is increasingly used in the fields of medicine, electronics, national defense, and military industry. The helium content in natural gas is very low, the conventional low-temperature extraction process consumes huge energy, and the removal of some impurities is difficult to control. Summary of the invention

[0003] In order to overcome the above defects, a room temperature natural gas helium extraction and purification system is provided, which uses very low energy consumption to purify helium in natural gas. It can also purify helium in flash gas (BOG) in the liquefied natural gas process, and has a good application effect.

[0004] The technical solution adopted by the present invention to achieve the above-mentioned purpose is: a room temperature natural gas helium extraction and purification system, comprising a primary membrane separator (1), a secondary first-stage membrane separator (7), a secondary second-stage membrane separator (8), a tertiary membrane separator (5) and a pressure swing adsorption unit (11); The permeate gas outlet of the first-stage membrane separator (1) is connected to the compressor (2) and then connected to the inlet of the third-stage membrane separator (5), and the non-permeate gas outlet of the first-stage membrane separator (1) is connected to the pipeline network to continue to transport natural gas to the outside; The permeate gas outlet of the three-stage membrane separator (5) is connected to the compressor (2) and then connected to the inlet of the second-stage membrane separator (7); the non-permeate gas outlet of the three-stage membrane separator (5) is connected to the compressor (2) and then connected to the pipeline network to continue to transport natural gas to the outside; The permeate gas outlet of the secondary first-stage membrane separator (7) is connected to a compressor (2) and then to a pressure swing adsorption unit (6) to obtain high-purity helium; the non-permeate gas outlet of the secondary first-stage membrane separator (7) is connected to an inlet of a secondary second-stage membrane separator (8); the permeate gas outlet of the secondary second-stage membrane separator (8) is connected to a compressor (2) and then to an inlet of the secondary first-stage membrane separator (7); the non-permeate gas outlet of the secondary second-stage membrane separator (8) is connected to an inlet of a tertiary membrane separator (5).

[0005] Furthermore, the permeate gas outlet of the first-stage membrane separator (1) is connected to the compressor (2), which is then connected to the dehydrogenation unit (3) and the decarbonization unit (4) for rough treatment, and then connected to the inlet of the third-stage membrane separator (5).

[0006] Furthermore, the permeate gas outlet of the secondary first stage membrane separator (7) is connected to the compressor (2) and then to the dehydrogenation unit (3) for fine treatment and then to the pressure swing adsorption unit (6).

[0007] Furthermore, the desorbed gas outlet of the decarbonization unit (4) is connected to a pipeline network to continue to transport natural gas to the outside.

[0008] Furthermore, the desorbed gas outlet of the pressure swing adsorption unit (6) is connected to the permeated gas outlet of the first-stage membrane separator (1) for circulation.

[0009] A purification method for a room temperature natural gas helium extraction and purification system, wherein the helium content in the natural gas is very low, and after the helium is initially concentrated by a first-stage membrane separator (1), the natural gas enters a catalytic dehydrogenation unit (3) to remove hydrogen therein, and then enters a decarbonization unit (4) to remove carbon dioxide therein; the tail gas of the decarbonization unit (4) is pressurized by a compressor (2) and then returned to the pipeline network; the natural gas from which impurities have been removed enters a third-stage membrane separator (5) for further concentration, enters a compressor for pressurization, and then enters a second-stage membrane separator (7) for concentration to a higher concentration; the non-permeate gas of the third-stage membrane separator (5) has an extremely low helium content, and after being pressurized by a compressor, the gas enters a second-stage membrane separator (7) for concentration to a higher concentration; , and returns to the pipeline network; the helium concentration at the permeate outlet of the secondary first-stage membrane separator (7) is relatively high, and after being pressurized by the compressor, it enters the dehydrogenation unit (3) and the pressure swing adsorption unit (6) to produce pure helium; the non-permeate outlet of the secondary first-stage membrane separator (7) still contains a large amount of helium, and enters the secondary second-stage membrane separator (8) to recover this part of helium and return it to the system circulation; the helium content in the non-permeate outlet of the secondary second-stage membrane separator is still much higher than the original natural gas, and returns to the tertiary membrane separator for circulation and recovery; the helium content in the desorbed gas of the pressure swing adsorption unit (6) is very high but the pressure is relatively low, and returns to the outlet of the primary membrane separator (1) for circulation.

[0010] The beneficial effects of the present invention are as follows: the system solves the problem of high energy consumption in extracting and concentrating helium from flash gas (BOG) in natural gas and natural gas liquefaction process, and purifies helium through a process route at room temperature. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0012] Figure 1 This is a structural diagram of the system embodiment.

[0013] In the figure: 1. primary membrane separator; 2. compressor; 3. dehydrogenation unit; 4. decarbonization unit; 5. tertiary membrane separator; 6. pressure swing adsorption unit; 7. secondary first-stage membrane separator; 8. secondary second-stage membrane separator. DETAILED DESCRIPTION

[0014] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0015] like Figure 1 As shown, a normal temperature natural gas helium extraction and purification system comprises a primary membrane separator 1, a secondary first-stage membrane separator 7, a secondary second-stage membrane separator 8, a tertiary membrane separator 5 and a pressure swing adsorption unit 11; The permeate outlet of the first-stage membrane separator 1 is connected to the compressor 2, and then to the dehydrogenation unit 3 and the decarbonization unit 4 for rough treatment, and then to the inlet of the third-stage membrane separator 5. The non-permeate outlet of the first-stage membrane separator 1 is connected to the pipeline network to continue to transport natural gas outward; The permeate outlet of the three-stage membrane separator 5 is connected to the compressor 2 and then to the inlet of the second-stage membrane separator 7; the non-permeate outlet of the three-stage membrane separator 5 is connected to the compressor 2 and then to the pipeline network to continue to transport natural gas outward; The permeate gas outlet of the secondary first-stage membrane separator 7 is connected to the compressor 2 and then to the dehydrogenation unit 3 for fine treatment and then to the pressure swing adsorption unit 6 to obtain high-purity helium; the non-permeate gas outlet of the secondary first-stage membrane separator 7 is connected to the inlet of the secondary second-stage membrane separator 8; the permeate gas outlet of the secondary second-stage membrane separator 8 is connected to the compressor 2 and then to the inlet of the secondary first-stage membrane separator 7; the non-permeate gas outlet of the secondary second-stage membrane separator 8 is connected to the inlet of the tertiary membrane separator 5.

[0016] The desorbed gas outlet of the decarbonization unit 4 is connected to the pipeline network to continue to transport natural gas to the outside.

[0017] The desorbed gas outlet of the pressure swing adsorption unit 6 is connected to the permeated gas outlet of the primary membrane separator 1 for circulation.

[0018] The purification method of the room temperature natural gas helium extraction and purification system, the helium content in the natural gas is very low, after the helium is initially concentrated by the first-stage membrane separator 1, it enters the catalytic dehydrogenation unit 3 to remove the hydrogen therein, and then enters the decarbonization unit 4 to remove the carbon dioxide therein; the tail gas of the decarbonization unit 4 is pressurized by the compressor 2 and returned to the pipeline network; the natural gas with impurities removed enters the third-stage membrane separator 5 for further concentration, enters the compressor for pressurization, and then enters the second-stage membrane separator 7 for concentration to a higher concentration; the helium content in the non-permeate gas of the third-stage membrane separator 5 is extremely low, after being pressurized by the compressor, Return to the pipeline network; the helium concentration at the permeate outlet of the secondary first-stage membrane separator 7 is relatively high, and after being pressurized by the compressor, it enters the dehydrogenation unit 3 and the pressure swing adsorption unit 6 to produce pure helium; the non-permeate outlet of the secondary first-stage membrane separator 7 still contains a large amount of helium, which enters the secondary second-stage membrane separator 8 to recover this part of helium and return it to the system circulation; the helium content in the non-permeate outlet of the secondary second-stage membrane separator is still much higher than the original natural gas, and returns to the tertiary membrane separator for circulation and recovery; the helium content in the desorbed gas of the pressure swing adsorption unit 6 is very high but the pressure is low, and it returns to the outlet of the primary membrane separator 1 for circulation.

[0019] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical solutions and concepts of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A room temperature natural gas helium extraction and purification system, characterized in that: It comprises a primary membrane separator (1), a secondary first-stage membrane separator (7), a secondary second-stage membrane separator (8), a tertiary membrane separator (5) and a pressure swing adsorption unit (11); The permeate gas outlet of the first-stage membrane separator (1) is connected to the compressor (2) and then connected to the inlet of the third-stage membrane separator (5), and the non-permeate gas outlet of the first-stage membrane separator (1) is connected to the pipeline network to continue to transport natural gas to the outside; The permeate gas outlet of the three-stage membrane separator (5) is connected to the compressor (2) and then connected to the inlet of the second-stage membrane separator (7); the non-permeate gas outlet of the three-stage membrane separator (5) is connected to the compressor (2) and then connected to the pipeline network to continue to transport natural gas to the outside; The permeate gas outlet of the secondary first-stage membrane separator (7) is connected to a compressor (2) and then to a pressure swing adsorption unit (6) to obtain high-purity helium; the non-permeate gas outlet of the secondary first-stage membrane separator (7) is connected to an inlet of a secondary second-stage membrane separator (8); the permeate gas outlet of the secondary second-stage membrane separator (8) is connected to a compressor (2) and then to an inlet of the secondary first-stage membrane separator (7); the non-permeate gas outlet of the secondary second-stage membrane separator (8) is connected to an inlet of a tertiary membrane separator (5).

2. The room temperature natural gas helium extraction and purification system according to claim 1, characterized in that: The permeate gas outlet of the first-stage membrane separator (1) is connected to a compressor (2), which is then connected to a dehydrogenation unit (3) and a decarbonization unit (4) for rough treatment, and then connected to an inlet of a third-stage membrane separator (5).

3. The room temperature natural gas helium extraction and purification system according to claim 2, characterized in that: The permeate gas outlet of the secondary first stage membrane separator (7) is connected to the compressor (2), which is then connected to the dehydrogenation unit (3) for fine treatment, and then connected to the pressure swing adsorption unit (6).

4. The room temperature natural gas helium extraction and purification system according to claim 3 is characterized in that: The desorbed gas outlet of the decarbonization unit (4) is connected to a pipeline network to continue to transport natural gas to the outside.

5. The room temperature natural gas helium extraction and purification system according to claim 4, characterized in that: The desorbed gas outlet of the pressure swing adsorption unit (6) is connected to the permeated gas outlet of the first-stage membrane separator (1) for circulation.

6. The purification method of the room temperature natural gas helium extraction and purification system according to claim 5, characterized in that: After the natural gas passes through the primary membrane separator (1) to initially concentrate the helium, it enters the catalytic dehydrogenation unit (3) to remove the hydrogen therein, and then enters the decarbonization unit (4) to remove the carbon dioxide therein; The tail gas of the decarbonization unit (4) is pressurized by the compressor (2) and then returned to the pipeline network; the natural gas from which impurities have been removed enters the third-stage membrane separator (5) for further concentration, enters the compressor for pressurization, and then enters the second-stage membrane separator (7) for concentration to a higher concentration; the helium content in the non-permeate gas of the third-stage membrane separator (5) is extremely low, and after being pressurized by the compressor, it returns to the pipeline network; the helium concentration at the outlet of the permeate gas of the second-stage membrane separator (7) is relatively high, and after being pressurized by the compressor, it enters the dehydrogenation unit (3) and the pressure swing adsorption unit (6) to produce pure helium; the non-permeate gas outlet of the second-stage membrane separator (7) still contains a large amount of helium, and enters the second-stage membrane separator (8) to recover this part of helium and return it to the system circulation; the helium content in the non-permeate outlet of the second-stage membrane separator is still much higher than the original natural gas, and returns to the third-stage membrane separator for circulation and recovery; the helium content in the desorbed gas of the pressure swing adsorption unit (6) is very high but the pressure is relatively low, and returns to the outlet of the first-stage membrane separator (1) for circulation.

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