Method and system for preparing negative hydrocarbon from urban natural gas based on electric gas production technology

Abstract

The invention belongs to the technical field of green hydrogen, and discloses a method and a system for preparing negative carbon hydrogen from urban natural gas based on an electric gas preparation technology. The system comprises a natural gas long-distance conveying pipe network used for conveying natural gas; the urban natural gas pipe network is connected with the natural gas long-distance transportation pipe network and provides fuel gas for cities; the gas mixing pry is used for uniformly mixing natural gas and hydrogen; the water electrolysis hydrogen production device is connected with the power generation device to perform water electrolysis hydrogen production, and the water electrolysis hydrogen production device is communicated with the gas mixing pry, the pure oxygen user and the methane synthesis device; hydrogen is provided for the gas mixing pry and the methane synthesis device; oxygen is provided for a pure oxygen user; the carbon capture device is communicated with a tail gas outlet of the urban industrial user utilizing the natural gas and is used for capturing carbon dioxide in gas generated after the urban industrial user utilizing the natural gas utilizes the natural gas of the urban natural gas pipeline network; a natural gas hydrogen production device; the device is communicated with an urban natural gas pipeline network to prepare hydrogen. According to the invention, energy storage and consumption of large-scale renewable energy sources can be realized, and realization of an urban carbon neutralization target is facilitated.

Description

Technical Field

[0001] The present invention relates to the field of green hydrogen technology, and in particular to a method and system for producing negative carbon hydrogen from urban natural gas based on electric gas generation technology. Background Art

[0002] The description of the background technology in the present invention belongs to the related technology related to the present invention, which is only used to illustrate and facilitate the understanding of the invention content of the present invention, and should not be understood as the applicant explicitly believes or inferred that the applicant believes that it is the prior art of the present invention on the filing date of the first application.

[0003] Cities play a vital role in achieving the goal of carbon neutrality. According to research, more than 70% of China's carbon emissions come from cities, mainly in the fields of electricity, heating and transportation. Natural gas is the main energy source for cities. Taking Beijing as an example, the total natural gas consumption in Beijing in 2022 will reach 19.91 billion m 3 The clean and efficient use of natural gas has greatly reduced carbon emissions, but low carbon does not mean zero carbon, and it is still difficult to achieve the goal of "dual carbon". my country's natural gas dependence on foreign countries exceeds 40%, but it has abundant renewable energy. Based on the electricity-to-gas technology, it can couple natural gas with renewable energy, realize the use of negative carbon hydrogen in cities, and achieve terminal carbon emission reduction.

[0004] Green hydrogen is the key direction of hydrogen energy development in the future, but cities lack renewable energy resources, and it is very costly to transport green hydrogen from other places to cities. Urban buildings and transportation are key areas for carbon emission reduction. Green hydrogen can be used for distributed energy supply of fixed hydrogen fuel cells in the construction field, and can be used for hydrogen refueling stations to refuel hydrogen fuel cell vehicles in the transportation field. Summary of the invention

[0005] The purpose of the embodiment of the present invention is to provide a method and system for producing negative carbon hydrogen from urban natural gas based on electric gas generation technology. Green hydrogen / green methane is mixed in the upstream of the natural gas pipeline network, and transported to the city's hydrogen use point through the natural gas pipeline. Then, the city's complete gas facilities are used to produce hydrogen in situ from natural gas, which can realize the storage and consumption of large-scale renewable energy and help achieve the city's carbon neutrality goal. .

[0006] The purpose of the embodiment of the present invention is achieved through the following technical solutions:

[0007] A system for producing negative carbon hydrogen from urban natural gas based on electric gas generation technology, comprising:

[0008] Natural gas long-distance pipeline network, used to transport natural gas;

[0009] The city natural gas pipeline network is connected to the natural gas long-distance pipeline network to provide gas for the city;

[0010] Gas mixing skid, used for evenly mixing natural gas and hydrogen;

[0011] The water electrolysis hydrogen production device is connected to the power generation device to produce hydrogen by water electrolysis. The water electrolysis hydrogen production device is connected to the gas mixing skid, the pure oxygen user and the methane synthesis device respectively; it provides hydrogen for the gas mixing skid and the methane synthesis device; and it provides oxygen for the pure oxygen user;

[0012] A carbon capture device is connected to the tail gas outlet of the urban industrial user utilizing natural gas, and is used to capture carbon dioxide in the gas generated by the urban industrial user utilizing natural gas after utilizing the natural gas from the urban natural gas pipeline network;

[0013] A natural gas hydrogen production device is connected to the city natural gas pipeline network to produce hydrogen.

[0014] Furthermore, the natural gas hydrogen production device is connected to the city's pure hydrogen users.

[0015] Furthermore, the natural gas hydrogen production device is connected to a second carbon capture device, and the second carbon capture device is connected to the methane synthesis device.

[0016] Furthermore, the carbon capture device is connected to the methane synthesis device.

[0017] A method for producing negative carbon hydrogen from urban natural gas based on electric gas generation technology, using the above system, comprises the following steps:

[0018] Power generation equipment is arranged along the long-distance natural gas pipeline network entering the city. The power generation equipment generates electricity to electrolyze water to produce green hydrogen, and part of the green hydrogen is injected into the methane synthesis device to be converted into green methane;

[0019] Evaluate the long-distance natural gas pipeline network and natural gas end users to determine the acceptable natural gas-to-hydrogen volume ratio in the city;

[0020] The green hydrogen produced is mixed into the long-distance natural gas pipeline network. The hydrogen mixing ratio must be lower than the evaluation result. After reaching an acceptable hydrogen mixing ratio, the excess hydrogen is input into the methane synthesis unit for methane synthesis and injected into the long-distance natural gas pipeline network. The pure oxygen produced by the electrolysis of water to produce hydrogen and the synthesis of methane is collected and transported to pure oxygen users.

[0021] Arrange distributed natural gas hydrogen production equipment and capture the carbon dioxide produced in the natural gas hydrogen production process; the amount of hydrogen produced by natural gas should be consistent with the amount of hydrogen produced by water electrolysis;

[0022] The carbon dioxide captured by urban gas power plants / chemical industry / urban industrial users utilizing natural gas and the carbon dioxide produced by natural gas hydrogen production equipment are transported to the methane synthesis unit for synthesis of green methane with green hydrogen;

[0023] The negative carbon hydrogen produced from natural gas is delivered to pure hydrogen users.

[0024] Furthermore, the negative carbon hydrogen produced from natural gas will be delivered to pure hydrogen users: the negative carbon hydrogen produced from natural gas will be used in hydrogen refueling stations to refuel hydrogen fuel cell vehicles; the negative carbon hydrogen produced from natural gas will be used in fixed hydrogen fuel cells for distributed energy supply.

[0025] The embodiments of the present invention have the following beneficial effects:

[0026] This application involves blending green hydrogen / green methane upstream of the natural gas pipeline, transporting it to the city’s hydrogen usage points via pipelines, and then using the city’s complete gas facilities to produce hydrogen on-site from natural gas, which can not only achieve large-scale renewable energy storage and consumption, but also achieve the recycling of CO2.

[0027] This application can utilize green hydrogen produced from renewable energy on a large scale, realize large-scale hydrogen energy storage, and effectively solve the problem of large-scale renewable energy consumption, without transforming the natural gas pipeline network and end users.

[0028] This application can effectively solve the problem of mismatch between hydrogen supply and demand. This patent uses natural gas pipelines as carriers, green hydrogen and green methane as media, solves the problem of long-distance transportation of green hydrogen, and realizes the utilization of negative carbon hydrogen in cities.

[0029] This application will help achieve deep decarbonization in urban industrial users, transportation, construction and other fields that utilize natural gas in cities, and realize "hydrogen into thousands of homes." BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 This is a schematic structural diagram of a system for producing negative hydrocarbons from urban natural gas based on electric gas generation technology according to the present invention.

[0031] Figure 2 Schematic diagram of gas flow in the present invention. DETAILED DESCRIPTION

[0032] The present application is further described below in conjunction with embodiments.

[0033] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, in the following description, different "one embodiment" or "embodiment" does not necessarily refer to the same embodiment. Different embodiments can be replaced or combined, and for ordinary technicians in this field, other implementation methods can be obtained based on these embodiments without creative work.

[0034] The present invention uses the following system to produce negative carbon hydrogen from natural gas in cities:

[0035] Combined with Figure 1and 2 , a system for producing negative carbon hydrogen from urban natural gas based on electric gas generation technology, comprising:

[0036] Natural gas long-distance pipeline network 1, used for transporting natural gas;

[0037] The city natural gas pipeline network 5 is connected to the natural gas long-distance pipeline network 1 to provide gas for the city;

[0038] A gas mixing skid 2 is arranged on the natural gas long-distance pipeline network 1;

[0039] The water electrolysis hydrogen production device 8 is connected to the power generation device 11 to produce hydrogen by water electrolysis. The water electrolysis hydrogen production device 8 is respectively connected to the gas mixing skid 2, the pure oxygen user 7 and the methane synthesis device 12; it provides hydrogen to the gas mixing skid 2 and the methane synthesis device 12; and it provides oxygen to the pure oxygen user 7;

[0040] The carbon capture device 3 is connected to the tail gas outlet of the urban industrial user utilizing natural gas, and is used to capture carbon dioxide in the gas generated by the urban industrial user 9 utilizing natural gas after utilizing the natural gas from the urban natural gas pipeline network 5;

[0041] The main urban industrial users of natural gas are: gas boiler rooms, gas power plants, and chemical plants.

[0042] A natural gas hydrogen production device 10 is connected to the city natural gas pipeline network 5 to prepare hydrogen. A natural gas gate station 4 is provided between the natural gas long-distance pipeline network 1 and the city natural gas pipeline network 5, and the terminal of the city natural gas pipeline network 5 is connected to a natural gas user 6. The power generation device can be a photovoltaic power generation device or a wind power generation device. In the above embodiment, green hydrogen / green methane is mixed upstream of the natural gas pipeline network, and transported to the city hydrogen use point by pipeline, and then the city's complete gas facilities are used to produce hydrogen in situ from natural gas, which can not only realize the storage and consumption of large-scale renewable energy, but also realize the recycling of CO2.

[0043] In some embodiments of the present invention, the natural gas hydrogen production device 10 is connected to a city pure hydrogen user.

[0044] In some embodiments of the present invention, the natural gas hydrogen production device 10 is connected to a second carbon capture device 13 , and the second carbon capture device 13 is in communication with the methane synthesis device 12 .

[0045] In some embodiments of the present invention, the carbon capture device 3 is connected to the methane synthesis device 12 .

[0046] A method for producing negative carbon hydrogen from urban natural gas based on electric gas generation technology, using the above system, comprises the following steps:

[0047] A power generation device 11 is arranged on the natural gas long-distance pipeline 1 entering the city. The power generation device 11 generates electricity to electrolyze water to produce green hydrogen, and part of the green hydrogen is injected into the methane synthesis device 12 to be converted into green methane; wherein: the water electrolysis hydrogen production technology includes alkaline water electrolysis, proton exchange membrane water electrolysis and solid oxide water electrolysis; the methane synthesis technology uses SOEC (Solid Oxide Electrolysis Cell) methanation, that is, water and carbon dioxide are simultaneously electrolyzed in a solid oxide electrolysis cell (co-electrolysis), and the generated hydrogen and carbon monoxide are used to produce methane.

[0048] By the end of 2022, China has planned more than 300 renewable energy hydrogen production projects, with a cumulative renewable hydrogen production capacity of about 56,000 tons / year. In March 2022, the state issued the "Medium- and Long-Term Plan for the Development of the Hydrogen Energy Industry (2021-2035)", proposing that by 2025, renewable energy hydrogen production will reach 100,000-200,000 tons / year, becoming an important part of new hydrogen energy consumption. In 2022, China's electrolyzer production capacity exceeded 8 gigawatts, and shipments reached 800 megawatts. Among them, the price of alkaline electrolyzer systems has been reduced to 1,400 yuan / kilowatt, and products with a capacity of 1,000 standard cubic meters / hour can be mass-produced.

[0049] Japan has taken the lead in successfully producing synthetic methane worldwide. Tokyo Gas Co., Ltd. of Japan began conducting empirical tests on methanation in March 2022; Osaka Gas Co., Ltd. plans to start the world's largest synthetic methane equipment in the second half of 2024. The Japanese government has also proposed to convert 90% of city gas into synthetic methane by 2050 to achieve the goal of decarbonizing city gas.

[0050] Evaluate the long-distance natural gas pipeline network 1 and natural gas end users to clarify the acceptable natural gas hydrogen blending volume ratio in the city; the evaluation process includes gas quality evaluation, natural gas pipeline network evaluation, equipment hydrogen blending evaluation to determine the theoretical hydrogen blending ratio, and hydrogen blending engineering verification;

[0051] Gas quality assessment: It includes three items: hydrogen quality assessment, green methane quality assessment, and hydrogen-blended natural gas quality assessment:

[0052] Quality requirements for hydrogen entering the natural gas pipeline network: It is necessary to comply with the group standard "Technical Specifications for Natural Gas Hydrogen Blending Stations" T / CAS 590-2022.

[0053] The quality requirements for green methane and hydrogen-blended natural gas entering the natural gas pipeline network must comply with national standards GB55009 "Gas Engineering Project Specifications" and GB 17820 "Natural Gas".

[0054] Natural gas pipeline network assessment: At present, the hydrogen blending ratio of natural gas studied by various countries is generally 5% to 30%. On the premise of not significantly changing the pipeline and terminal combustion equipment, 20% is the highest hydrogen blending ratio of natural gas pipeline network accepted by most countries. X70 and X80 steel grade natural gas pipelines can be blended with hydrogen by volume ratio of 3% and 2% respectively; X52 and below steel grade urban gas pipelines can be blended with hydrogen by volume ratio of 10%.

[0055] Equipment hydrogen blending assessment determines the theoretical hydrogen blending ratio: The addition of hydrogen will affect the use characteristics of natural gas, but through the adaptability evaluation of different application terminals, combined with demonstration operation data, and optimization of safety management technology and emergency repair plans, the feasibility of hydrogen-blended natural gas in diversified scenarios such as civil, commercial, and urban industrial users using natural gas can be guaranteed. It is safe and feasible for the terminal to use equipment with a hydrogen blending ratio of 10%.

[0056] Hydrogen blending engineering verification: A progressive method is used to evaluate the pipeline network and end users at hydrogen blending ratios of 3%, 5%, 10%, 15%, and 20%. The hydrogen blending ratios of 3% and 5% are continuously operated for more than 3 months, and the hydrogen blending ratios of 10%, 15%, and 20% are continuously operated for more than 1 month.

[0057] The green hydrogen produced is mixed into the long-distance natural gas pipeline network 1, and the hydrogen mixing ratio needs to be lower than the evaluation result. After reaching an acceptable hydrogen mixing ratio, the excess hydrogen is input into the methane synthesis device 12 for synthesizing methane and injected into the long-distance natural gas pipeline network 1; the pure oxygen produced by the process of hydrogen production and methane synthesis by electrolysis of water is collected and transported to the pure oxygen user 7;

[0058] At each hydrogen-using point in the city, a distributed natural gas hydrogen production device 10 is arranged, and the carbon dioxide generated in the natural gas hydrogen production process is captured; the amount of hydrogen produced by natural gas should be consistent with the amount of hydrogen produced by electrolysis of water; wherein, natural gas hydrogen production adopts natural gas steam reforming hydrogen production technology;

[0059] For example: Here, hydrogen production by water electrolysis and hydrogen production by natural gas are an operating unit. Carbon emission indicators are obtained when hydrogen is produced by water electrolysis, and the indicators are used for hydrogen production by natural gas.

[0060] For example, a natural gas hydrogen production and hydrogenation integrated station has started trial operation in a certain place in Guangdong Province. The station includes a set of natural gas reforming hydrogen production equipment with a design capacity of 500m / h, and adopts natural gas steam reforming hydrogen production technology.

[0061] The carbon dioxide captured by the city gas power plant / chemical industry / city industrial users utilizing natural gas and the carbon dioxide produced by the natural gas hydrogen production device 10 are transported to the methane synthesis device 12 for synthesizing green methane with green hydrogen;

[0062] The negative carbon hydrogen produced from natural gas is delivered to pure hydrogen users. Urban pure hydrogen users include hydrogen refueling stations 14, fixed hydrogen fuel cells 15, etc. Pure hydrogen users include: hydrogen refueling stations (for hydrogen fuel cell vehicles), fixed hydrogen fuel cells (distributed energy supply of hydrogen fuel cells). The two are in parallel relationship.

[0063] Distributed energy supply, such as 12,000 fuel cell cogeneration systems in a certain place, providing energy and heating for household life. The country's first hydrogen energy into thousands of homes smart energy demonstration community project has been put into operation in Foshan City, with 4 440KW commercial fuel cell cogeneration equipment and 394 household fuel cell cogeneration equipment installed.

[0064] When fuel cells are used for distributed energy supply, the overall efficiency can reach 95%, and they have the advantages of high energy conversion efficiency, rapid start-up at low temperatures, low heat radiation, environmental friendliness, low noise, and adaptability to different power requirements.

[0065] In some embodiments of the present invention, negative carbon hydrogen produced from natural gas is delivered to pure hydrogen users by: using the negative carbon hydrogen produced from natural gas in a hydrogen refueling station 14 to refuel hydrogen fuel cell vehicles; and using the negative carbon hydrogen produced from natural gas in a fixed hydrogen fuel cell 15 for distributed energy supply.

[0066] This application can utilize green hydrogen produced from renewable energy on a large scale, realize large-scale hydrogen energy storage, and effectively solve the problem of large-scale renewable energy consumption, without transforming the natural gas pipeline network and end users.

[0067] This application can effectively solve the problem of mismatch between hydrogen supply and demand. This patent uses natural gas pipelines as carriers, green hydrogen and green methane as media, solves the problem of long-distance transportation of green hydrogen, and realizes the utilization of negative carbon hydrogen in cities.

[0068] This application will help achieve deep decarbonization in urban industries, transportation, construction and other fields that use natural gas in cities, and realize "hydrogen into thousands of homes".

[0069] Benefits achieved: (1) Large-scale utilization of renewable energy, large-scale hydrogen energy storage, and effective solution to the problem of large-scale renewable energy consumption. (2) Carbon emission reduction for urban gas end users can be achieved through the use of green hydrogen and green methane; (3) Pure hydrogen can be used in urban transportation and construction fields by arranging distributed natural gas hydrogen production devices in cities. (4) Hydrogen and green methane, as a type of fuel gas, are effective supplements to natural gas resources and help ease the pressure on natural gas supply.

[0070] It should be noted that the above embodiments can be freely combined as needed. The above description is only the preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention can have various changes and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A system for producing negative carbon hydrogen from urban natural gas based on electric gas generation technology, characterized in that: include: Natural gas long-distance pipeline network, used to transport natural gas; The city natural gas pipeline network is connected to the natural gas long-distance pipeline network to provide gas for the city; Gas mixing skid, used for uniform mixing of natural gas and hydrogen; The water electrolysis hydrogen production device is connected to the power generation device to produce hydrogen by water electrolysis. The water electrolysis hydrogen production device is connected to the gas mixing skid, the pure oxygen user and the methane synthesis device respectively; it provides hydrogen for the gas mixing skid and the methane synthesis device; and it provides oxygen for the pure oxygen user; A carbon capture device is connected to the tail gas outlet of the urban industrial user utilizing natural gas, and is used to capture carbon dioxide in the gas generated by the urban industrial user utilizing natural gas after utilizing the natural gas from the urban natural gas pipeline network; A natural gas hydrogen production device is connected to the city natural gas pipeline network to produce hydrogen.

2. The system for producing negative hydrocarbons from urban natural gas based on electric gas generation technology according to claim 1 is characterized in that: The natural gas hydrogen production device is connected to the urban pure hydrogen users.

3. The system for producing negative hydrocarbons from urban natural gas based on electric gas generation technology according to claim 1 is characterized in that: The natural gas hydrogen production device is connected to a second carbon capture device, and the second carbon capture device is communicated with the methane synthesis device.

4. The system for producing negative hydrocarbons from urban natural gas based on electric gas generation technology according to claim 1 is characterized in that: The carbon capture device is connected to the methane synthesis device.

5. A method for producing negative hydrocarbons from urban natural gas based on electric gas generation technology, characterized in that: The method is implemented by using the system according to any one of claims 1 to 4, comprising the following steps: Power generation equipment is arranged along the long-distance natural gas pipeline network entering the city. The power generation equipment generates electricity to electrolyze water to produce green hydrogen, and part of the green hydrogen is injected into the methane synthesis device to be converted into green methane; Evaluate the long-distance natural gas pipeline network and natural gas end users to determine the acceptable natural gas-to-hydrogen volume ratio in the city; The green hydrogen produced is mixed into the long-distance natural gas pipeline network. The hydrogen mixing ratio must be lower than the evaluation result. After reaching an acceptable hydrogen mixing ratio, the excess hydrogen is input into the methane synthesis unit for methane synthesis and injected into the long-distance natural gas pipeline network. The pure oxygen produced by the process of water electrolysis to produce hydrogen and synthesize methane is collected and transported to pure oxygen users; Arrange distributed natural gas hydrogen production equipment and capture the carbon dioxide produced in the natural gas hydrogen production process; the amount of hydrogen produced by natural gas should be consistent with the amount of hydrogen produced by water electrolysis; The carbon dioxide captured by urban industrial users of city gas and the carbon dioxide produced by the natural gas hydrogen production unit are transported to the methane synthesis unit for synthesis of green methane with green hydrogen; The negative carbon hydrogen produced from natural gas is delivered to pure hydrogen users.

6. The method for producing negative hydrocarbons from urban natural gas based on electric gas generation technology according to claim 5, characterized in that: The negative carbon hydrogen produced from natural gas is transported to pure hydrogen users. The pure hydrogen users are: using the negative carbon hydrogen produced from natural gas in hydrogen refueling stations to refuel hydrogen fuel cell vehicles; using the negative carbon hydrogen produced from natural gas in fixed hydrogen fuel cells for distributed energy supply.

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