CN219128858U

CN219128858U - System for extracting and preparing high-purity helium from natural gas or BOG

Info

Publication number: CN219128858U
Application number: CN202223458705.7U
Authority: CN
Inventors: 杜国栋; 王璠; 马艳勋; 牛海宁
Original assignee: DALIAN EUROFILM INDUSTRIAL Ltd
Current assignee: DALIAN EUROFILM INDUSTRIAL Ltd
Priority date: 2022-12-23
Filing date: 2022-12-23
Publication date: 2023-06-06
Anticipated expiration: 2032-12-23

Abstract

The utility model discloses a system for extracting and preparing high-purity helium from natural gas or BOG, which comprises a primary membrane separation device, an interstage compression device, a secondary membrane separation device, a coarse helium compression device, a palladium membrane separation device, a catalytic oxidative dehydrogenation device, a catalytic deoxidization device, a dehydration decarburization device, an adsorption device and a pressurizing filling device which are sequentially arranged along the conveying direction of raw gas; the devices are connected in series through pipelines; the adsorption device comprises a pressure swing adsorption device and a low-temperature adsorption device, and when the pressure swing adsorption device works, the low-temperature adsorption device is in a non-working state; when the low-temperature adsorption device works, the pressure swing adsorption device is in a non-working state. The utility model firstly adopts membrane separation to remove more than 90 percent of methane and nitrogen, and then reduces the concentration of hydrogen to below 3 percent through palladium membrane separation, thereby greatly reducing the downstream dehydrogenation load; the method can realize that the product gas can meet the standard requirement of high-purity helium for the raw material gas containing neon with any concentration, and has wider application range.

Description

System for extracting and preparing high-purity helium from natural gas or BOG

Technical Field

The utility model relates to the technical field of helium purification, in particular to a system for extracting and preparing high-purity helium from natural gas or BOG.

Background

Helium is a scarce strategic resource and has very important applications in the aspects of aerospace, national defense, low-temperature superconducting research, semiconductor production, nuclear magnetic resonance imaging, special metal smelting, gas leakage detection and the like. With the development of national defense construction and high-tech research in China, the demand for helium is increasing. Helium is present in very little air, primarily in natural gas. Helium content in natural gas has been identified to be generally in the range of 0.024 to 7.5vol%, and thus helium extraction from natural gas, particularly from natural gas liquefaction flash (BOG), is the only important source of helium for industrial use today.

The current common recovery and purification methods of industrial helium mainly comprise a cryogenic method, a Pressure Swing Adsorption (PSA) method, a low-temperature adsorption method, a membrane permeation separation method and the like and coupling processes thereof. Because the content of hydrogen in natural gas is higher, the boiling point of the natural gas is close to that of helium, and the energy consumption for cryogenic separation of hydrogen is extremely high, catalytic oxidative dehydrogenation is usually adopted, namely, hydrogen is catalytically combusted into water by adding excessive oxygen, and then the water and the excessive oxygen are removed. In the prior art, first stage catalytic dehydrogenation is adopted to remove 99.5% of hydrogen, then membrane separation is adopted to remove more than 90% of methane and nitrogen, then second stage catalytic dehydrogenation is adopted to reach 0.5ppmv, and finally PSA is adopted to remove impurities such as water, oxygen and the like. The process has the defects that after dehydrogenation, helium and hydrogen are concentrated at the same side of the membrane, so that secondary dehydrogenation is needed after the membrane, the cost of the dehydrogenation process is overhigh, the hydrogen is used as a chemical raw material and an energy source with high demand, and the direct catalytic combustion also causes a certain degree of resource waste; oxygen is removed in the PSA process, but PSA is not ideal in removing efficiency of impurities such as oxygen, neon and the like, and the prepared high-purity helium product is not easy to meet the standard requirement.

Disclosure of Invention

Aiming at the problems of excessive cost and energy waste in the dehydrogenation working procedure caused by secondary dehydrogenation after membrane separation and unsatisfactory removal efficiency of impurities such as oxygen, neon and the like in the prior art, the utility model provides a system for extracting and preparing high-purity helium from natural gas or BOG, which comprises the steps of firstly carrying out membrane separation to extract helium, then carrying out catalytic dehydrogenation, and then further purifying to prepare high-purity helium with the purity of more than or equal to 99.999vol percent, so that the standard requirement of the high-purity helium is met, and the recovery rate of the helium is more than 95 percent; and the application range is wider, and the dehydrogenation and purification loads are low.

In order to achieve the above purpose, the present utility model provides the following technical solutions: a system for extracting and preparing high-purity helium from natural gas or BOG comprises a primary membrane separation device, an interstage compression device, a secondary membrane separation device, a crude helium compression device, a palladium membrane separation device, a catalytic oxidative dehydrogenation device, a catalytic deoxidation device, a dehydration decarburization device, an adsorption device and a pressurizing filling device which are sequentially arranged along the conveying direction of raw gas; the devices are connected in series through pipelines;

the adsorption device comprises a pressure swing adsorption device and a low-temperature adsorption device, wherein the pressure swing adsorption device and the low-temperature adsorption device are connected in parallel and then connected with the pressurizing and filling device in series, and when the pressure swing adsorption device works, the low-temperature adsorption device is in a non-working state; when the low-temperature adsorption device works, the pressure swing adsorption device is in a non-working state.

Further, the primary membrane separation device and the secondary membrane separation device each comprise at least one membrane separator, and the membrane separator has preferential permeability to helium.

Further, the primary membrane separation device is provided with a permeate gas outlet and a trapped gas outlet, wherein the permeate gas outlet is connected with the interstage compression device, and the trapped gas outlet is connected with a fuel gas pipeline.

Further, a feed back pipeline is arranged on the secondary membrane separation device, and the feed back pipeline can convey gas generated on the interception side of the secondary membrane separation device to the primary membrane separation device.

Further, the device also comprises a raw gas pressurizing device, wherein the raw gas pressurizing device is used for pressurizing raw gas, and the raw gas pressurizing device is connected with the primary membrane separating device through a pipeline.

Further, desorption gas pipelines are respectively arranged on the pressure swing adsorption device and the low-temperature adsorption device, and the desorption gas pipelines are connected with the adsorption device and the interstage compression device.

In summary, the utility model has the following beneficial effects:

firstly, helium is extracted by membrane separation firstly and then catalytic dehydrogenation is carried out, more than 90% of methane and nitrogen are removed in the membrane process, and the loads of downstream dehydrogenation and purification processes are greatly reduced; meanwhile, the complex flow of secondary dehydrogenation is avoided in the prior art that hydrogen is concentrated in the membrane process after primary dehydrogenation, and one-step dehydrogenation is realized;

secondly, the palladium membrane separation process is adopted to reduce the hydrogen in the crude helium to below 3vol%, so that the cost of the downstream catalytic dehydrogenation process is saved, the byproduct ultra-pure hydrogen product is produced, and the economical efficiency of the whole system is improved;

thirdly, the recovery rate of helium in the method reaches more than 95%, and compared with the prior art, the product gas obtained by the method can reach the standard requirement of high-purity helium for the raw material gas containing neon with any concentration, and the application range is wider.

Drawings

In order to more clearly illustrate the embodiments of the present utility model or the technical solutions in the prior art, the drawings that are required in the embodiments or the description of the prior art will be briefly described, and it is obvious that the drawings in the following description are some embodiments of the present utility model, and other drawings may be obtained according to the drawings without inventive effort to a person skilled in the art.

FIG. 1 is a process flow diagram of a system for extracting and producing high purity helium from natural gas as disclosed in example 1 of the present utility model;

FIG. 2 is a process flow diagram of a system for extracting and producing high purity helium from BOG according to example 2 of the present utility model.

In the figure, 1, a primary membrane separation device; 11. a feed gas input line; 12. a fuel gas line; 2. an interstage compression device; 3. a secondary membrane separation device; 31. a feed back pipeline; 4. a coarse helium compressor; 5. a palladium membrane separation device; 6. a catalytic oxidative dehydrogenation unit; 61. an air supply line; 7. a catalytic deoxidizing device; 8. a dehydration and decarbonization device; 9. an adsorption device; 91. a pressure swing adsorption apparatus; 92. a low temperature adsorption device; 10. a product gas booster; 20. a desorption gas line; 30. and a raw material gas pressurizing device.

Detailed Description

For the purpose of making the objects, technical solutions and advantages of the embodiments of the present utility model more clear, the technical solutions of the embodiments of the present utility model will be clearly and completely described below with reference to fig. 1 to 2 in the embodiments of the present utility model, and it is apparent that the described embodiments are some embodiments of the present utility model, but not all embodiments of the present utility model. All other embodiments, which can be made by those skilled in the art based on the embodiments of the utility model without making any inventive effort, are intended to be within the scope of the utility model.

Example 1:

referring to fig. 1, a system for extracting and preparing high purity helium from natural gas is provided with a primary membrane separation device 1, an interstage compression device 2, a secondary membrane separation device 3, a crude helium compression device 4, a palladium membrane separation device 5, a catalytic oxidative dehydrogenation device 6, a catalytic deoxidization device 7, a dehydration decarburization device 8, an adsorption device 9 and a pressurizing filling device in sequence according to the conveying direction of raw gas; the devices are connected in series through pipelines.

The primary membrane separation device 1 comprises a primary membrane separator with preferential permeability to helium, and the input end of the primary membrane separator is connected with a feed gas input pipeline 11. The interstage compression device 2 comprises an interstage compressor capable of pressurizing an input gas. The permeate gas outlet of the primary membrane separator is connected with the input end of the interstage compressor through a pipeline, and the trapped gas outlet is connected with a fuel gas pipeline 12.

The secondary membrane separation device 3 comprises a secondary membrane separator with preferential permeability to helium, and the input end of the secondary membrane separator is connected with the output end of the interstage compressor. The permeate gas outlet of the secondary membrane separator is connected with a coarse helium compressor 4, and the coarse helium compressor 4 comprises a coarse helium compressor and can pressurize the input gas. The secondary membrane separator is provided with a feed back pipeline 31, one end of the feed back pipeline 31 is connected with a trapped gas outlet of the secondary membrane separator, and the other end is connected with an input end of the primary membrane separator.

The raw material gas enters the primary membrane separator through the raw material gas input pipeline 11, helium is preferentially concentrated on the permeation side through the primary membrane, and more than 90% of methane and nitrogen are trapped. The trapped gas outlet outputs methane-rich gas which can be directly used as fuel gas to be discharged through the fuel gas pipeline 12; the permeate gas output from the permeate gas outlet is pressurized by the interstage compressor and then enters the secondary membrane separator. Helium is preferentially permeated through the secondary membrane to be further enriched on the permeation side; the trapped gas output by the trapped gas outlet returns to the first-stage membrane separator and is mixed with the raw material gas to further improve the recovery rate of helium. The crude helium with hydrogen and hydrogen concentration of more than 90-95vol% is output from the permeate gas outlet, and is input into the palladium membrane separation device 5 after being pressurized by a crude helium compressor.

The palladium membrane separation device 5 comprises a palladium membrane separator, the input end of the palladium membrane separator is connected with the output end of the coarse helium compressor through a pipeline, and the trapped gas outlet of the palladium membrane separator is connected with the catalytic oxidative dehydrogenation device 6. The palladium membrane separator is internally provided with a metal palladium membrane, hydrogen can be adsorbed on the surface of the metal palladium and dissociated into hydrogen atoms, the hydrogen atoms are dissolved and diffused in the membrane, and the hydrogen molecules are separated and coupled on the low-pressure permeation side, so that the metal palladium membrane has extremely high selective permeability to hydrogen, the hydrogen is easy to permeate the membrane, and other gases are impermeable. The pressurized crude helium enters a palladium membrane separator, and pure hydrogen with purity of more than 99.9999% is output from a permeate gas outlet and is output as a product; the trapped gas outlet outputs hydrogen-lean helium with the hydrogen concentration below 3vol% and inputs the hydrogen-lean helium into the catalytic oxidative dehydrogenation device 6 for purification.

The catalytic oxidative dehydrogenation unit 6 includes a catalytic oxidative dehydrogenation reactor in which a noble metal catalyst is disposed. The noble metal catalyst may be a noble metal such as palladium or platinum, and the noble metal palladium catalyst is exemplified in the present application. The input end of the catalytic oxidative dehydrogenation reactor is connected with the palladium membrane separator through a pipeline, the catalytic oxidative dehydrogenation reactor is also connected with a gas supplementing pipeline 61, and pure oxygen is input into the gas supplementing pipeline 61. Pure oxygen is taken as a supplement, and under the action of a palladium catalyst, the pure oxygen and hydrogen in the hydrogen-deficient helium gas undergo oxidation reaction, and the reaction principle is as follows: 2H (H) ₂ +O ₂ ＝2H ₂ O, thereby effecting dehydrogenation. The dehydrogenated gas is fed to the catalytic deoxidizing device 7 through a line.

The catalytic deoxidizing device 7 includes a catalytic deoxidizing reactor, in which a noble metal is disposed as a catalyst, and the noble metal catalyst may be noble metal such as palladium or platinum, and the present application takes a noble metal palladium catalyst as an example. The input end of the catalytic deoxidization reactor is connected with the output end of the catalytic oxidative dehydrogenation reactor through a pipeline. Under the action of palladium catalyst, a small amount of methane contained in dehydrogenated gas reacts with oxygen, and the reaction principle is as follows: CH (CH) ₄ +2O ₂ ＝CO ₂ +2H ₂ O, thereby realizing the removal of excessive oxygen. The deoxidized gas is fed into the dehydration and decarbonization device 8 through a pipeline.

The dehydration and decarbonization device 8 comprises a dehydration and decarbonization absorber, and the input end of the dehydration and decarbonization absorber is connected with the output end of the catalytic deoxidization reactor through a pipeline. The dehydration decarbonization absorber is internally provided with an adsorbent, and the adsorbent can be a molecular sieve, active carbon and the like, and the molecular sieve adsorbent is taken as an example in the application. The dehydrogenated and deoxidized gas enters a dehydration and decarbonization absorber, and water vapor and carbon dioxide in the gas can be removed at low temperature to obtain helium with the purity of 90-95vol percent, and the helium is input into an adsorption device 9 through a pipeline.

The adsorption device 9 comprises a pressure swing adsorption device 91 and a low-temperature adsorption device 92, and the pressure swing adsorption device 91 and the low-temperature adsorption device 92 are connected in parallel and then connected in series with the dehydration decarburization adsorber.

The pressure swing adsorption apparatus 91 includes a pressure swing adsorber with an adsorbent built therein, and the low temperature adsorption apparatus 92 includes a low temperature adsorber with an adsorbent built therein, and the adsorbent may be activated carbon, molecular sieve, or the like.

When the concentration of neon in the raw material gas is lower than 50ppmv, the pressure swing absorber works, the low-temperature absorber does not work, at the moment, the input end of the pressure swing absorber is connected with the output end of the dehydration decarburization absorber through a pipeline, and the input end of the low-temperature absorber is not connected with the dehydration decarburization absorber; the stripping gas outlet of the pressure swing adsorber is connected to the inlet of the interstage compressor via a stripping gas line 20. The dehydrated and decarbonized helium enters a pressure swing adsorber to remove residual trace methane, nitrogen and the like, so as to obtain high-purity helium with the purity of more than 99.999 vol%; the normal pressure stripping gas and the penetrating gas of the first-stage membrane separator are mixed and enter an interstage compressor, so that the helium recovery rate is further improved.

When the concentration of neon in the raw material gas is higher than 50ppmv, the low-temperature absorber works, the pressure swing absorber does not work, at the moment, the input end of the low-temperature absorber is connected with the output end of the dehydration decarburization absorber through a pipeline, and the input end of the pressure swing absorber is not connected with the dehydration decarburization absorber; the desorption gas outlet of the low-temperature adsorber and the inlet of the interstage compressor are connected by means of a desorption gas line 20. The dehydrated and decarbonized helium enters a low-temperature adsorber, and residual trace methane, nitrogen, trace neon and other impurities are removed by utilizing the large adsorption capacity of an active carbon adsorbent at low temperature, so that high-purity helium with the purity of more than 99.999vol% is obtained; the normal pressure stripping gas and the penetrating gas of the first-stage membrane separator are mixed and enter an interstage compressor, so that the helium recovery rate is further improved.

The pressurizing and charging device comprises a product gas supercharger 10, wherein when the concentration of neon in raw gas is lower than 50ppmv, the input end of the product gas supercharger 10 is connected with the output end of the pressure swing adsorber through a pipeline; when the concentration of neon in the feed gas is higher than 50ppmv, the input of the product gas booster 10 and the output of the cryogenic adsorber are connected by a pipeline. The high purity helium is pressurized by the product gas booster 10 to reach a gas pressure of 21Mpa, and is fed out of the boundary region after filling.

Example 2:

a system for extracting and preparing high purity helium from BOG, referring to fig. 2, a raw gas pressurizing device 30, a primary membrane separating device 1, an interstage compression device 2, a secondary membrane separating device 3, a crude helium compressing device 4, a palladium membrane separating device 5, a catalytic oxidative dehydrogenation device 6, a catalytic deoxidizing device 7, a dehydration decarburizing device 8, an adsorbing device 9 and a pressurizing and filling device are sequentially arranged according to the conveying direction of raw gas; the devices are connected in series through pipelines.

The raw gas pressurizing device 30 comprises a raw gas compressor, wherein an input end of the raw gas compressor is connected with the raw gas input pipeline 11, and the raw gas compressor is used for pressurizing the BOG raw gas under normal pressure to be more than 0.8 MPaG. The first-stage membrane separation device 1, the interstage compression device 2, the second-stage membrane separation device 3, the crude helium compression device 4, the palladium membrane separation device 5, the catalytic oxidative dehydrogenation device 6, the catalytic deoxidation device 7, the dehydration decarburization device 8, the adsorption device 9 and the pressurizing filling device are the same as those in the embodiment 1, and no description is repeated here.

Example 3:

in this example, the flow rate of the natural gas feed gas was 41667Nm ³ The composition is shown in Table 1 at a pressure of 5.0MPaG and a temperature of 25 ℃.

TABLE 1

Component (A)

CH ₄

N ₂

He

H ₂

CO ₂

Ne

C2-C4

Composition (vol%)

89.61

6.80

0.40

0.10

0.07

2×10 ^-5

3.02

A method for extracting and preparing high-purity helium from low-neon natural gas specifically comprises the following steps:

s1: helium gas concentration: inputting natural gas raw gas into a primary membrane separation device 1, removing more than 90% of methane and nitrogen, and obtaining methane-rich gas on the interception side, wherein the methane-rich gas is output as fuel gas; helium is enriched on the permeate side to obtain a first permeate gas, which is then fed into an interstage compression device 2 to be pressurized to 5.2MpaG, and then fed into a second membrane separation device 3. The helium is further enriched on the permeation side of the secondary membrane separation device 3 to obtain crude helium with the helium and hydrogen concentration of more than 90-95vol% and a small amount of methane and nitrogen, and the gas obtained on the interception side of the secondary membrane separation device 3 is returned to the primary membrane separation device 1 and mixed with the feed gas to improve the recovery rate of the helium;

s2: and (3) hydrogen purification: crude helium is input into a crude helium compression device 4 through a pipeline, the pressure is increased to 0.8MPaG, the gas after the pressure is increased enters a palladium membrane separation device 5, pure hydrogen with the purity of more than 99.9999vol% is obtained on the permeation side of the palladium membrane separation device 5, and the pure hydrogen is output as a product; the interception side of the palladium membrane separation device 5 obtains hydrogen-lean helium with the hydrogen concentration below 3 vol%;

s3: helium primary purification: the hydrogen-deficient helium is input into a catalytic oxidative dehydrogenation device 6 through a pipeline, pure oxygen is used as a supplement, and under the action of a palladium catalyst arranged in the catalytic oxidative dehydrogenation device 6, the oxygen and hydrogen in the hydrogen-deficient helium undergo oxidation reaction, so that the hydrogen concentration is reduced to below 1 ppmv;

the dehydrogenated gas is input into a catalytic deoxidizing device 7 through a pipeline, and a small amount of methane and excessive oxygen contained in the dehydrogenated gas react under the action of a palladium catalyst arranged in the catalytic deoxidizing device 7, so that the oxygen concentration is reduced to below 1 ppmv;

the deoxidized gas is input into a dehydration and decarbonization device 8 through a pipeline, contacts with a molecular sieve arranged in the dehydration and decarbonization device 8, reduces the concentration of water vapor in the deoxidized gas to be less than 1ppmv and the concentration of carbon dioxide to be less than 10ppmv at low temperature, and obtains helium with the purity of 90-95 vol%;

s4: helium secondary purification: helium is input into a pressure swing adsorption device 91 through a pipeline, and trace methane, nitrogen and the like remained in the helium are removed through activated carbon adsorption, so that high-purity helium with the purity of more than 99.999vol% is obtained; mixing normal pressure stripping gas containing 40-60vol% helium with the first-stage permeation gas, pressurizing the mixture in an interstage compression device 2, and then introducing the mixture into a second-stage membrane separation device 3 so as to further improve the recovery rate of the helium;

the high purity helium gas outputted from the pressure swing adsorption apparatus 91 is inputted into the product gas booster 10 through a pipeline, boosted to about 21Mpa, and then fed out of the boundary region after filling.

In the method of this embodiment, the gas flows, pressures, temperatures and compositions of the raw gas a, the fuel gas B, the first-stage permeation gas C, the pressurized raw helium gas D, the hydrogen-deficient helium gas E, the pure hydrogen gas F, the dehydrogenated gas G, the deoxidized gas H, the helium gas I, the high-purity helium gas J and the pressurized high-purity helium gas K are shown in table 2.

TABLE 2

As can be seen from table 2, for low neon natural gas, the helium recovery is up to 95.12% by the method of this example. The purity of the obtained helium reaches 99.9996vol%, and other impurities also meet the standard requirements of high-purity helium.

Example 4:

in this example, the flow rate of the BOG feed gas was 400Nm ³ And/hr, at 40deg.C, the normal pressure BOG was fed into the raw gas pressurizing device 30, and pressurized to 2.0MPaG, and the composition of the pressurized BOG raw gas was shown in Table 3.

TABLE 3 Table 3

Component (A)	CH ₄	N ₂	He	H ₂	Ne
						Composition (vol%)	81.00	12.00	5.00	2.00	0.002

A method for extracting and preparing high-purity helium from low-neon-containing BOG specifically comprises the following steps:

s1: helium gas concentration: inputting the supercharged BOG raw material gas into a primary membrane separation device 1, removing more than 90% of methane and nitrogen, obtaining methane-rich gas on the interception side, and outputting the methane-rich gas as fuel gas; helium is enriched on the permeate side to obtain a first permeate gas, which is then fed into an interstage compression device 2 to be pressurized to 2.2MPaG, and then fed into a second membrane separation device 3. The helium is further enriched on the permeation side of the secondary membrane separation device 3 to obtain crude helium with the helium and hydrogen concentration of more than 90-95vol% and a small amount of methane and nitrogen, and the gas obtained on the interception side of the secondary membrane separation device 3 is returned to the primary membrane separation device 1 and mixed with the feed gas to improve the recovery rate of the helium;

s2: and (3) hydrogen purification: same as in example 3;

s3: helium primary purification: same as in example 3;

s4: helium secondary purification: same as in example 3.

In the method of this embodiment, the gas flows, pressures, temperatures and compositions of the raw gas a, the fuel gas B, the first-stage permeation gas C, the pressurized raw helium gas D, the hydrogen-deficient helium gas E, the pure hydrogen gas F, the dehydrogenated gas G, the deoxidized gas H, the helium gas I, the high-purity helium gas J and the pressurized high-purity helium gas K are shown in table 4.

TABLE 4 Table 4

As can be seen from Table 4, for the low neon-containing BOG, the helium recovery is 96.96% by the method of this example. The purity of the obtained helium reaches 99.9996vol%, and other impurities also meet the standard requirements of high-purity helium.

Example 5:

in this example, the flow rate of the BOG feed gas was 400Nm ³ And/hr, at 40deg.C, the normal pressure BOG was fed into the raw gas pressurizing device 30, and pressurized to 2.0MPaG, and the composition of the pressurized BOG raw gas was shown in Table 5.

TABLE 5

Component (A)	CH ₄	N ₂	He	H ₂	Ne
						Composition (vol%)	80.00	10.00	7.00	3.00	0.0055

A method for extracting and preparing high-purity helium from high-neon-content BOG specifically comprises the following steps:

s1: helium gas concentration: same as in example 4;

s2: and (3) hydrogen purification: same as in example 4;

s3: helium primary purification: same as in example 4;

s4: helium secondary purification: helium is input into a low-temperature adsorption device 92 through a pipeline, and trace methane, nitrogen and trace neon impurities and the like remained in the helium are removed through the adsorption of active carbon at low temperature, so that high-purity helium with the purity of more than 99.999vol% is obtained; mixing normal pressure stripping gas containing 40-60vol% helium with the first-stage permeation gas, pressurizing the mixture in an interstage compression device 2, and then introducing the mixture into a second-stage membrane separation device 3 so as to further improve the recovery rate of the helium;

the high purity helium gas outputted from the cryogenic adsorption device 92 is fed into the product gas booster 10 through a pipeline, boosted to about 21Mpa, filled and then fed out of the boundary region.

In the method of this embodiment, the gas flows, pressures, temperatures and compositions of the raw gas a, the fuel gas B, the first-stage permeation gas C, the pressurized raw helium gas D, the hydrogen-deficient helium gas E, the pure hydrogen gas F, the dehydrogenated gas G, the deoxidized gas H, the helium gas I, the high-purity helium gas J and the pressurized high-purity helium gas K are shown in table 6.

TABLE 6

As can be seen from Table 6, for the high neon-containing BOG, the helium recovery is 96.44% by the method of this example. The purity of the obtained helium reaches 99.9997vol%, the Ne content is 2ppmv, and other impurities also meet the standard requirements of high-purity helium.

In summary, the system for extracting and preparing high purity helium provided by the present application has the following inventive aspects compared with the prior art:

firstly, helium is concentrated by adopting two-stage membrane separation, and then catalytic dehydrogenation is carried out, more than 90% of methane and nitrogen are removed in the process of membrane separation helium extraction, and the loads in the downstream dehydrogenation and purification processes are greatly reduced; meanwhile, the complex flow of secondary dehydrogenation is avoided in the prior art that hydrogen is concentrated in the membrane process after primary dehydrogenation, and one-step dehydrogenation is realized.

Secondly, a hydrogen purification step is arranged, the concentration of hydrogen entering the catalytic dehydrogenation process is reduced to be lower than 3vol% through palladium membrane separation, the dehydrogenation cost is further reduced, and the byproduct of ultra-pure hydrogen product is produced, so that the economy of the whole system is improved.

The third helium purification step sets two paths. If the neon content of the raw material gas is not high, the concentration before adsorption can reach the standard, and only pressure swing adsorption is adopted at the moment, so that the energy consumption of the system can be reduced; if the neon content of the raw material gas is higher, the neon concentration cannot reach the standard through pressure swing adsorption, and then the low-temperature adsorption is adopted to replace the pressure swing adsorption. Corresponding adsorption paths are respectively arranged aiming at the working conditions of high neon and low neon, so that the product gas obtained by the utility model can reach the standard requirement of high-purity helium for the raw material gas containing neon with any concentration, and the application range is wider.

Finally, it should be noted that: the above embodiments are only for illustrating the technical solution of the present utility model, and not for limiting the same; although the utility model has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical scheme described in the foregoing embodiments can be modified or some or all of the technical features thereof can be replaced by equivalents; such modifications and substitutions do not depart from the spirit of the utility model.

Claims

1. The system for extracting and preparing the high-purity helium from the natural gas or the BOG is characterized by comprising a primary membrane separation device (1), an interstage compression device (2), a secondary membrane separation device (3), a crude helium compression device (4), a palladium membrane separation device (5), a catalytic oxidative dehydrogenation device (6), a catalytic deoxidization device (7), a dehydration decarburization device (8), an adsorption device (9) and a pressurizing filling device which are sequentially arranged along the conveying direction of the raw gas; the devices are connected in series through pipelines;

the adsorption device (9) comprises a pressure swing adsorption device (91) and a low-temperature adsorption device (92), wherein the pressure swing adsorption device (91) and the low-temperature adsorption device (92) are connected in parallel and then connected in series with the pressurizing filling device, and when the pressure swing adsorption device (91) works, the low-temperature adsorption device (92) is in a non-working state; when the low-temperature adsorption device (92) works, the pressure swing adsorption device (91) is in a non-working state.

2. A system for the extraction of high purity helium from natural gas or BOG according to claim 1, wherein the primary membrane separation device (1) and the secondary membrane separation device (3) each comprise at least one membrane separator having preferential permeability to helium.

3. A system for the extraction of high purity helium from natural gas or BOG according to claim 1, wherein the primary membrane separation device (1) is provided with a permeate outlet and a retentate outlet, wherein the permeate outlet is connected to the interstage compression device (2), and the retentate outlet is connected to a fuel gas line (12).

4. The system for extracting and preparing high-purity helium from natural gas or BOG according to claim 1, wherein a feed back pipeline (31) is arranged on the secondary membrane separation device (3), and the feed back pipeline (31) can convey gas generated on the interception side of the secondary membrane separation device (3) to the primary membrane separation device (1).

5. The system for extracting and preparing high-purity helium from natural gas or BOG according to claim 1, further comprising a raw gas pressurizing device (30), wherein the raw gas pressurizing device (30) is used for pressurizing the raw gas, and the raw gas pressurizing device (30) and the primary membrane separating device (1) are connected through a pipeline.

6. The system for extracting and preparing high-purity helium from natural gas or BOG according to claim 1, wherein a desorption gas pipeline (20) is arranged on the pressure swing adsorption device (91) and the low-temperature adsorption device (92), and the desorption gas pipeline (20) is connected with the adsorption device and the interstage compression device (2).