Urban gas field station pipe network differential pressure driven hydrogen extraction and reinjection integrated system and use method thereof

Abstract

The invention discloses an urban gas field station pipe network differential pressure driven hydrogen extraction and reinjection integrated system and a use method thereof, and belongs to the technical field of gas separation and hydrogen energy utilization. The problems that in the prior art, gas is additionally compressed, and residual gas is unreasonably utilized are solved. According to the technical key points, hydrogen-doped natural gas enters a membrane separator to generate permeated gas, the permeated gas flows out of a permeation end of the membrane separator, the permeated gas enters a sectional adsorption-regeneration tower, generated high-purity hydrogen flows into a gas diverter, regenerated gas flows into a gas mixer, and the hydrogen flows back to the sectional adsorption-regeneration tower by the gas diverter; the rest of hydrogen is injected into an urban pure hydrogen pipe network, the retentate gas flows into a gas mixer, and the retentate gas and the regenerated gas are mixed, subjected to pressure reduction metering and then flow into a field station output pipe network. According to the invention, two technologies of membrane separation and pressure swing adsorption are creatively integrated in the hydrogen extraction process of the urban gas station, and the characteristics of pressure difference and gas composition in the urban gas transmission and distribution process are fully utilized to realize the collaboration of various technologies in a specific scene.

Description

Technical Field

[0001] The present invention relates to the technical field of gas separation and hydrogen energy utilization, and specifically to an integrated system for extracting and re-injecting hydrogen driven by pressure difference in a town gas station pipeline network and a method for using the system. Background Art

[0002] With the development of the hydrogen energy industry, utilizing mature natural gas pipelines to transport hydrogen, followed by hydrogen purification technology to separate the hydrogen and supply it to hydrogen refueling stations and other users, has become an important method for hydrogen transportation and supply. Hydrogen purification within hydrogen-blended pipeline networks faces challenges such as the diverse sources of hydrogen, which may contain varying types and levels of impurities; high purification costs; hydrogen loss during the purification process; and incompatibility of purification equipment with existing pipeline systems.

[0003] Existing hydrogen-blending pipeline networks typically use pressure swing adsorption (PSA) and membrane separation methods for hydrogen purification. PSA can increase hydrogen purity to over 99.9%, simultaneously remove multiple impurities, and is highly adaptable to hydrogen-containing mixtures of varying compositions, allowing for flexible adjustment of product hydrogen flow and purity based on actual needs. Membrane separation is simple to operate, requiring no complex regeneration process. The equipment is compact, occupies a small footprint, and rapidly separates and purifies hydrogen. It can be operated continuously, resulting in relatively stable product hydrogen purity and flow.

[0004] At the same time, pressure swing adsorption and membrane separation methods also have many limitations. The pressure swing adsorption equipment structure is complex, including multiple adsorption towers and corresponding control systems, and the initial construction investment is large. The hydrogen recovery rate is limited, and some hydrogen is lost during processes such as adsorbent regeneration. It usually needs to operate at higher pressures, which requires high pressure resistance of the equipment. The selectivity and permeability of the membrane separation method are difficult to achieve ideal at the same time. There is a trade-off between the permeability and separation effect, and the membrane has a limited service life. The pretreatment requirements for the feed gas are strict. Under normal circumstances, the hydrogen obtained by the membrane separation method is difficult to achieve ultra-high purity requirements. The remaining gas without hydrogen extraction is directly discharged, resulting in resource waste and environmental pollution.

[0005] Therefore, it is urgent to propose an integrated system for hydrogen extraction and reinjection driven by pressure difference in urban gas station pipelines and its use method to solve the problems of excessive gas compression and irrational use of residual gas in the existing technology. Summary of the Invention

[0006] In view of the above facts, in order to solve the problems of excessive gas compression and irrational utilization of residual gas in the prior art, the present invention further designs an integrated system for hydrogen extraction and reinjection driven by pressure difference in the urban gas station pipeline network and its use method.

[0007] To achieve the above object, the present invention adopts the following technical solutions:

[0008] Option 1: An integrated system for hydrogen extraction and reinjection driven by differential pressure in the urban gas station network, including a membrane separator, a segmented adsorption-regeneration tower, a first mass flow controller, a second flow meter, a third flow meter, a fourth flow meter, a fifth mass flow meter, a gas splitter, a gas mixer, an online gas analyzer, a station gas inlet network, a station external transmission network, and an urban pure hydrogen network.

[0009] The station air inlet network is connected in sequence to the first mass flow controller and the air inlet end of the membrane separator;

[0010] The permeation end of the membrane separator is connected in sequence to a second flow meter, a segmented adsorption-regeneration tower, a gas splitter, a third flow meter, and a town pure hydrogen pipeline network;

[0011] The retentate end of the membrane separator is connected in sequence to a fourth flow meter, a gas mixer, an online gas analyzer, and a station external transmission pipeline network;

[0012] The regeneration gas end of the segmented adsorption-regeneration tower is connected to a gas mixer;

[0013] The reflux end of the gas splitter is connected to the segmented adsorption-regeneration tower through a reflux pipe, and the fifth mass flow meter is installed on the reflux pipe.

[0014] Furthermore, a heating steel jacket is provided on the outside of the alkane adsorption section at the bottom of the segmented adsorption-regeneration tower, and the heat source is connected to the heating steel jacket.

[0015] Furthermore: a first pressure regulating valve is installed between the station air inlet network and the first mass flow controller, a second back pressure valve is installed between the membrane separator and the second flow meter, a third gas control valve is installed between the segmented adsorption-regeneration tower and the gas diverter, a fourth pressure regulating valve is installed between the gas diverter and the third flow meter, a fifth gas control valve is installed between the gas diverter and the fifth mass flow meter, a sixth back pressure valve is installed between the segmented adsorption-regeneration tower and the gas mixer, and a seventh pressure regulating valve is installed between the gas mixer and the online gas analyzer.

[0016] Option 2: The method for using the integrated system for hydrogen extraction and reinjection driven by the pressure difference of the urban gas station network described in Option 1 is as follows:

[0017] Step 1: Driven by the pressure of the station's inlet pipe network, hydrogen-blended natural gas enters the membrane separator through the pipeline to achieve hydrogen enrichment. The hydrogen-rich gas flows out of the permeate end of the membrane separator as permeate gas, and the impurity gas flows out of the retentate end of the membrane separator as retentate gas.

[0018] Step 2: The permeate gas enters the segmented adsorption-regeneration tower when the permeate pressure is in the range of 1.5-1.7 MPa. The permeate gas is purified, impurities removed and regenerated in the segmented adsorption-regeneration tower. High-purity hydrogen flows into the inlet end of the gas splitter as the purified gas, and the regenerated gas flows into the gas mixer. The second flow meter monitors the permeate gas flow rate.

[0019] Step 3: The gas splitter refluxes 10%-15% of the hydrogen as purge gas to the segmented adsorption-regeneration tower, and the remaining hydrogen is injected into the town pure hydrogen network;

[0020] Step 4: The retentate gas flows into the gas mixer, where it is mixed with the regenerated gas. After being decompressed and metered, it flows into the external transmission pipeline of the station. The pressure range at this time is 0.01-0.02Mpa.

[0021] Furthermore, in step 1, the pressure range of the station air inlet network is 2-4 MPa, the first pressure regulating valve adjusts the station air inlet pressure to 2 MPa, and the first mass flow controller regulates the amount of gas to be separated in real time.

[0022] Furthermore: the first pressure regulating valve, the second back pressure valve, and the first mass flow controller jointly control the osmotic pressure difference to maintain it at 0.3-0.5 MPa.

[0023] Furthermore: the membrane separator is a hollow fiber membrane structure, and the membrane selection material is a high hydrogen selectivity material such as polyimide or carbon molecular sieve.

[0024] Furthermore: the adsorption pressure range of the membrane separator in step 1 is 1.5-1.7 MPa.

[0025] Furthermore: in the step 2, the segmented adsorption-regeneration tower is provided with a four-layer adsorbent filling structure from bottom to top, the first layer is filled with activated carbon adsorbent to remove alkanes, the second layer is filled with 13X and its modified molecular sieves to selectively remove CO2, the third layer is filled with carbon molecular sieves to remove CH4, and the fourth layer is filled with 5A and its modified molecular sieves to remove N2.

[0026] Furthermore: in the step 2, the segmented adsorption-regeneration tower adopts hydrogen purging-high-temperature heating segmented regeneration, CO2, CH4, and N2 adsorption adopts 10%-15% hydrogen purging regeneration, and the alkane adsorption section is regenerated under hydrogen purging and 180±10℃ high-temperature heating. The fifth gas control valve and the sixth back pressure valve jointly control the purge pressure to keep it at 0.1-0.2Mpa.

[0027] The beneficial effects of the present invention are:

[0028] 1. This invention innovatively integrates membrane separation and pressure swing adsorption technologies into the hydrogen extraction process at urban gas stations. This process is embedded before the urban gas is pressure-regulated to users. This fully utilizes the pressure differences and gas composition characteristics of the urban gas transmission and distribution process, enabling the synergy of multiple technologies in specific scenarios.

[0029] 2. The present invention uses the pipeline pressure difference as the separation driving force. Through the integrated design of "membrane separation-segmented adsorption regeneration tower-gas reinjection and external transmission pipeline network", it achieves compression-free and zero emissions throughout the process, providing an efficient hydrogen energy comprehensive utilization solution for hydrogen-blended natural gas purification and urban gas stations.

[0030] 3. In the membrane separation link, the present invention controls the membrane separation feed pressure to be the pipeline gas pressure, and sets a back-pressure valve to maintain the pressure difference. It is optimized according to the characteristics of urban gas and helps to achieve efficient hydrogen enrichment.

[0031] 4. The hydrogen-rich gas of the present invention does not need to be compressed and directly enters the segmented adsorption-regeneration tower, using its own pressure to remove impurities in layers, fully considering the feed pressure range and the pressure connection with the preceding membrane separation link, reducing the compression link and lowering energy consumption.

[0032] 5. The present invention realizes the rational utilization of the remaining gas from which hydrogen is not extracted, avoids waste of resources and environmental pollution, and conforms to the concept of green environmental protection and efficient utilization of resources. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 It is a system flow chart of the present invention.

[0034] In the figure: 1-membrane separator, 2-segmented adsorption-regeneration tower, 3-heating steel jacket, 4-heat source, 5-first mass flow controller, 6-second flow meter, 7-third flow meter, 8-fourth flow meter, 9-fifth mass flow meter, 10-first pressure regulating valve, 11-second back pressure valve, 12-third gas control valve, 13-fourth pressure regulating valve, 14-fifth gas control valve, 15-sixth back pressure valve, 16-seventh pressure regulating valve, 17-gas splitter, 18-gas mixer, 19-online gas analyzer, 20-station air inlet network, 21-station external transmission network, 22-urban pure hydrogen network. DETAILED DESCRIPTION

[0035] In order to enable those skilled in the art to better understand the present invention, the following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the drawings 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 in the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts should fall within the scope of protection of this application.

[0036] The terms "disposed," "connected," and "fixed" should be interpreted broadly. For example, "connected" can mean a fixed connection, a removable connection, or an integral structure; it can be a mechanical connection, a direct connection, an indirect connection through an intermediary, or an internal communication between two devices, elements, or components. Those skilled in the art will understand the specific meanings of these terms in this application based on the specific circumstances.

[0037] It should be noted that, in the absence of conflict, the embodiments and features of the embodiments in this application can be combined with each other. The present application will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0038] Preferred embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0039] Example 1: The integrated system for hydrogen extraction and reinjection driven by pressure difference in the town gas station network of this embodiment includes a membrane separator 1, a segmented adsorption-regeneration tower 2, a first mass flow controller 5, a second flow meter 6, a third flow meter 7, a fourth flow meter 8, a fifth mass flow meter 9, a gas splitter 17, a gas mixer 18, an online gas analyzer 19, a station gas inlet network 20, a station external transmission network 21, and a town pure hydrogen network 22;

[0040] The station air inlet network 20 is connected in sequence to the first mass flow controller 5 and the air inlet end of the membrane separator 1;

[0041] The permeation end of the membrane separator 1 is connected in sequence to the second flow meter 6, the segmented adsorption-regeneration tower 2, the gas splitter 17, the third flow meter 7, and the urban pure hydrogen pipeline network 22;

[0042] The retentate end of the membrane separator 1 is connected in sequence to the fourth flow meter 8, the gas mixer 18, the online gas analyzer 19, and the station external transmission pipeline network 21;

[0043] The regeneration gas end of the segmented adsorption-regeneration tower 2 is connected to a gas mixer 18;

[0044] The reflux end of the gas splitter 17 is connected to the segmented adsorption-regeneration tower 2 through a reflux pipe, and the fifth mass flow meter 9 is installed on the reflux pipe.

[0045] More specifically, a heating steel jacket 3 is provided on the outside of the alkane adsorption section at the bottom of the segmented adsorption-regeneration tower 2 , and the heat source 4 is connected to the heating steel jacket 3 .

[0046] More specifically: a first pressure regulating valve 10 is installed between the station air inlet network 20 and the first mass flow controller 5, a second back pressure valve 11 is installed between the membrane separator 1 and the second flow meter 6, a third gas control valve 12 is installed between the segmented adsorption-regeneration tower 2 and the gas diverter 17, a fourth pressure regulating valve 13 is installed between the gas diverter 17 and the third flow meter 7, a fifth gas control valve 14 is installed between the gas diverter 17 and the fifth mass flow meter 9, a sixth back pressure valve 15 is installed between the segmented adsorption-regeneration tower 2 and the gas mixer 18, and a seventh pressure regulating valve 16 is installed between the gas mixer 18 and the online gas analyzer 19.

[0047] Example 2: A method for using the integrated system for hydrogen extraction and reinjection driven by pressure difference in the town gas station network described in Example 1 is as follows:

[0048] Step 1: Driven by the pressure of the station's inlet pipe network 20, hydrogen-enriched natural gas enters the membrane separator 1 through the pipeline to achieve hydrogen enrichment. The hydrogen-rich gas flows out of the permeate end of the membrane separator 1 as permeate gas, and the impurity gas flows out of the retentate end of the membrane separator 1 as retentate gas.

[0049] Step 2: The permeate gas enters the segmented adsorption-regeneration tower 2 when the permeate pressure is in the range of 1.5-1.7 MPa. The permeate gas is purified, impurities removed, and regenerated in the segmented adsorption-regeneration tower 2. High-purity hydrogen (>99.97%) flows into the inlet end of the gas splitter 17 as the purified gas, and the regenerated gas flows into the gas mixer 18. The second flow meter 6 monitors the permeate gas flow rate.

[0050] Step 3: The gas splitter 17 refluxes 10%-15% of the hydrogen as purge gas to the segmented adsorption-regeneration tower 2, and the remaining hydrogen is injected into the town pure hydrogen pipeline network 22;

[0051] Step 4: The retentate gas flows into the gas mixer 18, where it is mixed with the regeneration gas, and after being reduced in pressure and metered, flows into the station external transmission pipeline 21. At this time, the pressure range is 0.01-0.02 MPa.

[0052] More specifically: in the step 1, the pressure range of the station air inlet network 20 is 2-4 MPa, the first pressure regulating valve 10 adjusts the station air inlet pressure to 2 MPa (±0.2 MPa), and the first mass flow controller 5 controls the amount of gas to be separated in real time.

[0053] More specifically, the first pressure regulating valve 10 , the second back pressure valve 11 , and the first mass flow controller 5 jointly control the osmotic pressure difference to maintain it at 0.3-0.5 MPa.

[0054] More specifically, the membrane separator 1 is a hollow fiber membrane structure, and the membrane selection material is a high hydrogen selectivity material such as polyimide or carbon molecular sieve.

[0055] More specifically: the adsorption pressure range of the membrane separator 1 in step 1 is 1.5-1.7 MPa.

[0056] More specifically: in the step 2, the segmented adsorption-regeneration tower 2 is provided with a four-layer adsorbent filling structure from bottom to top, the first layer is filled with activated carbon adsorbent to remove alkanes, the second layer is filled with 13X and its modified molecular sieves to selectively remove CO2, the third layer is filled with carbon molecular sieves (pore size 0.2-0.3nm) to remove CH4, and the fourth layer is filled with 5A and its modified molecular sieves to remove N2.

[0057] More specifically: in the step 2, the segmented adsorption-regeneration tower 2 adopts hydrogen purging-high-temperature heating segmented regeneration, CO2, CH4, and N2 adsorption adopts 10%-15% hydrogen purging regeneration, and the alkane adsorption section is regenerated under hydrogen purging and 180±10°C high-temperature heating. The fifth gas control valve 14 and the sixth back pressure valve 15 jointly control the purge pressure to keep it at 0.1-0.2Mpa.

[0058] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, the technical solutions described in the aforementioned embodiments can still be modified, or some or all of the technical features therein can be replaced by equivalents. As long as there is no structural conflict, the various features in the specific implementation methods disclosed in this application can be combined with each other in any way, and the essence of the corresponding technical solutions will not deviate from the scope of the technical solutions of the present invention.

[0059] In addition, it should be understood that although this specification is described in terms of implementation methods, not every implementation method contains only one independent technical solution. This narrative method of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment can also be appropriately combined to form other implementation methods that can be understood by those skilled in the art.

Claims

1. The integrated system of hydrogen extraction and reinjection driven by pressure difference in the pipe network of urban gas stations is characterized by: It comprises a membrane separator (1), a segmented adsorption-regeneration tower (2), a first mass flow controller (5), a second flow meter (6), a third flow meter (7), a fourth flow meter (8), a fifth mass flow meter (9), a gas splitter (17), a gas mixer (18), an online gas analyzer (19), a station gas inlet network (20), a station external transmission network (21), and a town pure hydrogen network (22); The station air inlet network (20) is connected in sequence to the first mass flow controller (5) and the air inlet end of the membrane separator (1); The permeation end of the membrane separator (1) is sequentially connected to a second flow meter (6), a segmented adsorption-regeneration tower (2), a gas splitter (17), a third flow meter (7), and a town pure hydrogen pipeline network (22); The retentate end of the membrane separator (1) is sequentially connected to a fourth flow meter (8), a gas mixer (18), an online gas analyzer (19), and a station external transmission pipeline network (21); The regeneration gas end of the segmented adsorption-regeneration tower (2) is connected to a gas mixer (18); The reflux end of the gas splitter (17) is connected to the segmented adsorption-regeneration tower (2) via a reflux pipe, and a fifth mass flow meter (9) is installed on the reflux pipe.

2. The integrated system for hydrogen extraction and reinjection driven by pressure difference in the town gas station pipeline network according to claim 1 is characterized by: A heating steel jacket (3) is provided on the outside of the alkane adsorption section at the bottom of the segmented adsorption-regeneration tower (2), and a heat source (4) is connected to the heating steel jacket (3).

3. The integrated system for hydrogen extraction and reinjection driven by pressure difference in the town gas station pipeline network according to claim 1 is characterized by: A first pressure regulating valve (10) is installed between the station air inlet network (20) and the first mass flow controller (5), a second back pressure valve (11) is installed between the membrane separator (1) and the second flow meter (6), a third gas control valve (12) is installed between the segmented adsorption-regeneration tower (2) and the gas diverter (17), a fourth pressure regulating valve (13) is installed between the gas diverter (17) and the third flow meter (7), a fifth gas control valve (14) is installed between the gas diverter (17) and the fifth mass flow meter (9), a sixth back pressure valve (15) is installed between the segmented adsorption-regeneration tower (2) and the gas mixer (18), and a seventh pressure regulating valve (16) is installed between the gas mixer (18) and the online gas analyzer (19).

4. The method for using the integrated system for hydrogen extraction and reinjection driven by pressure difference in the town gas station network according to claim 1, characterized in that: Specifically: Step 1: Under the pressure of the station gas inlet network (20), the hydrogen-enriched natural gas enters the membrane separator (1) through the pipeline to achieve hydrogen enrichment, the hydrogen-enriched gas flows out of the permeate end of the membrane separator (1) as permeate gas, and the impurity gas flows out of the retentate end of the membrane separator (1) as retentate gas; Step 2: The permeate gas enters the segmented adsorption-regeneration tower (2) when the permeate pressure is in the range of 1.5-1.7 MPa. The permeate gas is purified, impurities removed, and regenerated in the segmented adsorption-regeneration tower (2). High-purity hydrogen flows into the inlet end of the gas splitter (17) as the purified gas, and the regenerated gas flows into the gas mixer (18). The second flow meter (6) monitors the permeate gas flow rate. Step 3: 10%-15% of the hydrogen is refluxed from the gas splitter (17) as purge gas to the segmented adsorption-regeneration tower (2), and the remaining hydrogen is injected into the town pure hydrogen network (22); Step 4: The retentate gas flows into the gas mixer (18), the retentate gas and the regeneration gas are mixed through the gas mixer (18), and after decompression and metering, it flows into the station external transmission pipeline (21). At this time, the pressure range is 0.01-0.02Mpa.

5. The method for using the integrated system for hydrogen extraction and reinjection driven by pressure difference in a town gas station network according to claim 4 is characterized in that: In the step 1, the pressure range of the station air inlet network (20) is 2-4 MPa, the first pressure regulating valve (10) adjusts the station air inlet pressure to 2 MPa, and the first mass flow controller (5) controls the amount of the gas to be separated in real time.

6. The method for using the integrated system for hydrogen extraction and reinjection driven by pressure difference in a town gas station network according to claim 4 is characterized by: The first pressure regulating valve (10), the second back pressure valve (11) and the first mass flow controller (5) jointly control the osmotic pressure difference to maintain it at 0.3-0.5 MPa.

7. The method for using the integrated system for hydrogen extraction and reinjection driven by pressure difference in a town gas station network according to claim 4, characterized in that: The membrane separator (1) is a hollow fiber membrane structure, and the membrane selection material is a high hydrogen selectivity material such as polyimide or carbon molecular sieve.

8. The method for using the integrated system for hydrogen extraction and reinjection driven by pressure difference in a town gas station network according to claim 4, characterized in that: The adsorption pressure range of the membrane separator (1) in step 1 is 1.5-1.7 MPa.

9. The method for using the integrated system for hydrogen extraction and reinjection driven by pressure difference in a town gas station network according to claim 4, characterized in that: In the step 2, the segmented adsorption-regeneration tower (2) is provided with a four-layer adsorbent filling structure from bottom to top, wherein the first layer is filled with activated carbon adsorbent to remove alkanes, the second layer is filled with 13X and its modified molecular sieves to selectively remove CO2, the third layer is filled with carbon molecular sieves to remove CH4, and the fourth layer is filled with 5A and its modified molecular sieves to remove N2.

10. The method for using the integrated system for hydrogen extraction and reinjection driven by pressure difference in a town gas station network according to claim 4, characterized in that: In the step 2, the segmented adsorption-regeneration tower (2) adopts hydrogen purging-high-temperature heating segmented regeneration, CO2, CH4, and N2 adsorption adopts 10%-15% hydrogen purging regeneration, and the alkane adsorption section is regenerated under hydrogen purging and 180±10°C high-temperature heating. The fifth gas control valve (14) and the sixth back pressure valve (15) jointly control the purge pressure to keep it at 0.1-0.2Mpa.

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