System for decarbonizing natural gas and co-producing helium

Abstract

The utility model discloses a system for decarburizing natural gas and co-producing helium. The system comprises a first-stage membrane separator, an interstage compressor, a pressure swing adsorber and a second-stage membrane separator which are connected in sequence, the primary membrane separator is used for enrichment of helium and carbon dioxide, the secondary membrane separator is used for enrichment of helium, and the pressure swing adsorber is used for separation of helium and carbon dioxide; a raw gas pipeline is connected with a feeding hole of the first-stage membrane separator, carbon dioxide separated by the pressure swing adsorber is discharged from a tail gas discharge hole of the pressure swing adsorber, and a second permeation side outlet of the second-stage membrane separator is connected with a crude helium product gas pipeline; a second interception side outlet of the second-stage membrane separator is connected with a feed gas pipeline in parallel through a pipeline and then is connected with a feeding hole of the first-stage membrane separator. The carbon dioxide in the natural gas is removed, and the helium is recycled at the same time.

Description

Technical Field

[0001] This utility model relates to the field of gas separation technology, and in particular to a system for decarbonizing natural gas and producing helium. Background Technology

[0002] With the continuous growth of global energy demand and increasing environmental awareness, achieving clean energy utilization has become a focus of attention for all sectors of society. Natural gas, as a relatively clean fossil fuel, has become an indispensable and important component of the energy structure of countries worldwide due to its high efficiency and low pollution characteristics. Normally, natural gas contains varying concentrations of carbon dioxide, which not only reduces its calorific value but also corrodes pipeline infrastructure, thus shortening its service life. Decarbonization treatment can significantly improve the purity and combustion efficiency of natural gas and effectively reduce equipment maintenance costs.

[0003] Helium, a rare and non-renewable resource, possesses unique physicochemical properties that make it valuable in numerous fields. Currently, natural gas is the sole source of industrial helium extraction. As a helium-poor country, my country faces a severe situation where helium demand is rising annually while its self-sufficiency rate is extremely low, with over 90% of its helium needs relying on imports. Extracting helium from natural gas can effectively alleviate my country's helium resource shortage and bring significant economic and environmental benefits. Natural gas decarbonization and helium extraction are two independent processes. Given the necessity of natural gas decarbonization and the high recovery value of helium from natural gas, developing a scientifically sound and rational natural gas decarbonization and helium co-production system is particularly urgent. Summary of the Invention

[0004] This invention provides a system for decarbonizing natural gas and co-producing helium, so as to achieve the recovery and utilization of helium while removing carbon dioxide from natural gas.

[0005] To achieve the above objectives, the technical solution of this utility model is as follows:

[0006] A system for natural gas decarbonization and helium co-production includes: a primary membrane separator, an interstage compressor, a pressure swing adsorber, and a secondary membrane separator connected in sequence;

[0007] The primary membrane separator is used for the enrichment of helium and carbon dioxide, the secondary membrane separator is used for the enrichment of helium, and the pressure swing adsorber is used for the separation of helium and carbon dioxide.

[0008] The feed gas pipeline is connected to the feed inlet of the first-stage membrane separator. The carbon dioxide separated by the pressure swing adsorber is discharged from the tail gas outlet of the pressure swing adsorber. The second permeate side outlet of the second-stage membrane separator is connected to the crude helium product gas pipeline. The second retrieval side outlet of the second-stage membrane separator is connected to the feed inlet of the first-stage membrane separator after being connected in parallel with the feed gas pipeline through a pipeline.

[0009] Furthermore, the CO2 / CH4 separation coefficient of the primary membrane separator is not less than 30.

[0010] Furthermore, the He / CH4 separation coefficient of the secondary membrane separator is not less than 200.

[0011] Furthermore, it also includes an exhaust gas pipeline, with the tail gas outlet of the pressure swing adsorber connected to the exhaust gas pipeline.

[0012] Furthermore, the first retardation side outlet of the primary membrane separator is connected to a natural gas pipeline.

[0013] Furthermore, the first permeate-side outlet of the primary membrane separator is connected to the feed inlet of the pressure swing adsorber.

[0014] Furthermore, the product-side outlet of the pressure swing adsorber is connected to the feed inlet of the secondary membrane separator.

[0015] Furthermore, the first permeate-side outlet of the primary membrane separator is connected to the inlet of the interstage compressor via a first pipeline, and the outlet of the interstage compressor is connected to the feed inlet of the pressure swing adsorber via a second pipeline.

[0016] Beneficial effects:

[0017] This invention provides a system for natural gas decarbonization and helium co-production. By setting up a primary membrane separator and a secondary membrane separator, and utilizing the high permeation rate of helium and carbon dioxide on the membrane material, the system effectively reduces the concentration of carbon dioxide in natural gas through membrane separation technology, while simultaneously performing preliminary extraction of helium. By setting up a pressure swing adsorption (PSA) unit, the system further achieves effective separation of helium and carbon dioxide using PSA technology, thereby realizing the recovery and reuse of helium while removing carbon dioxide from natural gas. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1This is a schematic diagram of the structure of a natural gas decarbonization and helium co-production system disclosed in this utility model.

[0020] In the picture:

[0021] 1. Primary membrane separator; 101. First permeate side outlet; 102. First retention side outlet;

[0022] 2. Interstage compressor;

[0023] 3. Pressure Swing Adsorption Unit; 301. Product-side Outlet; 302. Exhaust Gas Outlet;

[0024] 4. Secondary membrane separator; 401. Second permeate side outlet; 402. Second retention side outlet;

[0025] a. Raw material gas pipeline; b. Natural gas pipeline; c. First pipeline; d. Second pipeline; e. Third pipeline; f. Fourth pipeline; g. Crude helium product gas pipeline; h. Emission gas pipeline. Detailed Implementation

[0026] To make the objectives, technical solutions, and advantages of the embodiments of this utility model clearer, the technical solutions of the embodiments of this utility model will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this utility model, not all embodiments. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of this utility model.

[0027] This embodiment provides a system for natural gas decarbonization and helium co-production, such as... Figure 1 As shown, it includes: a primary membrane separator 1, an interstage compressor 2, a pressure swing adsorber 3, and a secondary membrane separator 4. The primary membrane separator 1 is used for the enrichment of helium and carbon dioxide, the secondary membrane separator 4 is used for the enrichment of helium, and the pressure swing adsorber 3 is used for the separation of helium and carbon dioxide.

[0028] The feed gas pipeline a is connected to the inlet of the first-stage membrane separator 1. The first retardation side outlet 102 of the first-stage membrane separator 1 is connected to the natural gas pipeline b. The first permeate side outlet 101 of the first-stage membrane separator 1 is connected to the inlet of the interstage compressor 2 via the first pipeline c. The outlet of the interstage compressor 2 is connected to the inlet of the pressure swing adsorber 3 via the second pipeline d. The tail gas outlet 302 of the pressure swing adsorber 3 is connected to the exhaust gas pipeline h. The carbon dioxide separated by the pressure swing adsorber 3 is sent from the tail gas outlet 302 of the pressure swing adsorber 3 into the exhaust gas pipeline h. The product side outlet 301 of the pressure swing adsorber 3 is connected to the inlet of the second-stage membrane separator 4 via the third pipeline e. The second permeate side outlet 401 of the second-stage membrane separator 4 is connected to the crude helium product gas pipeline g. The second retardation side outlet 402 of the second-stage membrane separator 4 is connected to the feed gas pipeline a via the fourth pipeline f and then connected to the inlet of the first-stage membrane separator 1.

[0029] This embodiment provides a system for natural gas decarbonization and helium co-production. By setting up a primary membrane separator 1 and a secondary membrane separator 4, the system utilizes the characteristics of helium and carbon dioxide having a relatively fast permeation rate on the membrane material to effectively reduce the concentration of carbon dioxide in natural gas through membrane separation technology, and simultaneously completes the initial extraction of helium. By setting up a pressure swing adsorber 3, the system further achieves effective separation of helium and carbon dioxide using pressure swing adsorption technology, thereby realizing the recovery and utilization of helium while removing carbon dioxide from natural gas.

[0030] In this embodiment, the CO2 / CH4 separation coefficient of the primary membrane separator 1 is not less than 30, and the He / CH4 separation coefficient of the secondary membrane separator 4 is not less than 200, so as to ensure efficiency and separation effect, that the carbon dioxide content of the gas discharged from the first retardation side outlet 102 of the primary membrane separator 1 is not higher than 3%, the methane loss rate of the gas discharged from the tail gas outlet 302 of the pressure swing adsorber 3 is not more than 1%, the carbon dioxide concentration of the gas discharged from the product side outlet 301 of the pressure swing adsorber 3 is not higher than 1%, and the helium recovery rate of the gas discharged from the second permeate side outlet 401 of the secondary membrane separator 4 is not less than 90%.

[0031] To better illustrate the effectiveness of the natural gas decarbonization and helium co-production system disclosed in this utility model, its specific process flow is described below:

[0032] The feedstock gas is natural gas, with a volume of 41667 Nm³. 3 / h, pressure is 4.0 MPaG, its composition is as follows:

[0033] Components He <![CDATA[H2]]> <![CDATA[CH4]]> <![CDATA[C 2+ ]]> <![CDATA[N2]]> <![CDATA[CO2]]> Composition (vol%) 0.10 0.01 86.39 1.50 2.00 10.00

[0034] The raw gas enters the first-stage membrane separator 1 through the raw gas pipeline a. The first interception side outlet 102 is connected to the natural gas pipeline b. The decarbonized natural gas obtained by the first-stage membrane separator 1 is sent into the natural gas pipeline b.

[0035] After helium and carbon dioxide are enriched on the permeate side of the first-stage membrane separator 1, they are discharged from the first permeate side outlet 101, sent to the interstage compressor 2 via the first pipeline c for pressurization, and then enter the pressure swing adsorber 2 via the second pipeline d. Through pressure swing adsorption, helium and carbon dioxide are enriched at the product side outlet 301 and the tail gas outlet 302, respectively. The enriched carbon dioxide is sent from the tail gas outlet 302 to the exhaust gas pipeline h, and the enriched helium is sent from the product side outlet 301 to the second-stage membrane separator 4 via the third pipeline e.

[0036] Helium is enriched on the permeate side of the secondary membrane separator 4 for further concentration, and then sent to the crude helium product gas pipeline g through the second permeate side outlet 401. The remaining gas containing some helium is discharged from the second interception side outlet 402 and returned to the raw material gas pipeline a through the fourth pipeline f, thus realizing the recovery and utilization of the gas.

[0037] The amount of decarbonized natural gas obtained after passing through the first-stage membrane separator 1 is 38082 Nm³. 3 / h is composed of the following:

[0038] Components He <![CDATA[H2]]> <![CDATA[CH4]]> <![CDATA[C 2+ ]]> <![CDATA[N2]]> <![CDATA[CO2]]> Composition (vol%) 0.00 0.00 93.54 1.63 2.16 2.66

[0039] The crude helium product gas obtained after passing through the secondary membrane separator 3 has a flow rate of 78 Nm³. 3 / h is composed of the following:

[0040] Components He <![CDATA[H2]]> <![CDATA[CH4]]> <![CDATA[C 2+ ]]> <![CDATA[N2]]> <![CDATA[CO2]]> Composition (vol%) 49.99 5.02 38.53 0.03 1.82 4.61

[0041] The amount of decarbonized gas discharged through pressure swing adsorber 2 is 3507 Nm³. 3 / h is composed of the following:

[0042] Components He <![CDATA[H2]]> <![CDATA[CH4]]> <![CDATA[C 2+ ]]> <![CDATA[N2]]> <![CDATA[CO2]]> Composition (vol%) 0.07 0.01 9.86 0.08 0.21 89.76

[0043] Through a two-stage membrane separation coupled with pressure swing adsorption (PSA) process, the carbon dioxide concentration of natural gas was reduced from 10% to 2.66%, the methane loss rate in the decarbonized emissions was 0.96%, the helium product gas concentration was 49.99%, and the helium yield was 93.16%. The economic benefits are significant, requiring fewer pieces of equipment, occupying less land, with low investment costs, low energy consumption, and no pollution emissions. By using two-stage membrane separation coupled with PSA technology, carbon dioxide in natural gas is efficiently removed while most of the helium is recovered, achieving natural gas decarbonization and helium production.

[0044] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this utility model, and are not intended to limit it. Although the utility model has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this utility model.

Claims

1. A system for natural gas decarbonization and helium co-production, characterized in that, include: A primary membrane separator (1), an interstage compressor (2), a pressure swing adsorber (3), and a secondary membrane separator (4) are connected in sequence. The primary membrane separator (1) is used for the enrichment of helium and carbon dioxide, the secondary membrane separator (4) is used for the enrichment of helium, and the pressure swing adsorber (3) is used for the separation of helium and carbon dioxide. The feed gas pipeline (a) is connected to the feed inlet of the first-stage membrane separator (1). The carbon dioxide separated by the pressure swing adsorber (3) is discharged from the tail gas outlet (302) of the pressure swing adsorber (3). The second permeate side outlet (401) of the second-stage membrane separator (4) is connected to the crude helium product gas pipeline (g). The second retrieval side outlet (402) of the second-stage membrane separator (4) is connected to the feed gas pipeline (a) via a pipeline and then connected to the feed inlet of the first-stage membrane separator (1).

2. The system for natural gas decarbonization and helium co-production according to claim 1, characterized in that, The CO2 / CH4 separation coefficient of the primary membrane separator (1) is not less than 30.

3. The system for natural gas decarbonization and helium co-production according to claim 1, characterized in that, The He / CH4 separation coefficient of the secondary membrane separator (4) is not less than 200.

4. A system for natural gas decarbonization and helium co-production according to claim 1, characterized in that, It also includes an exhaust gas line (h), the tail gas outlet (302) of the pressure swing adsorber (3) is connected to the exhaust gas line (h).

5. A system for natural gas decarbonization and helium co-production according to claim 1, characterized in that, The first retardation side outlet (102) of the primary membrane separator (1) is connected to the natural gas pipeline (b).

6. A system for natural gas decarbonization and helium co-production according to claim 1, characterized in that, The first permeate side outlet (101) of the primary membrane separator (1) is connected to the feed inlet of the pressure swing adsorber (3).

7. A system for natural gas decarbonization and helium co-production according to claim 1, characterized in that, The product-side outlet (301) of the pressure swing adsorber (3) is connected to the feed inlet of the secondary membrane separator (4).

8. A system for natural gas decarbonization and helium co-production according to claim 1, characterized in that, The first permeate side outlet (101) of the primary membrane separator (1) is connected to the inlet of the interstage compressor (2) via a first pipeline (c), and the outlet of the interstage compressor (2) is connected to the feed inlet of the pressure swing adsorber (3) via a second pipeline (d).

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