A system and method for producing LNG and hydrogen products using coke oven gas as raw material

Abstract

The present invention discloses a system and method for producing LNG and hydrogen products using coke oven gas as raw material, which solves the technical problems that when coke oven gas is used to produce LNG and hydrogen products in the prior art, the adjustment range of the products is limited, the market demand cannot be flexibly adapted, CO2 in the device cannot be balanced, and the investment in the CO conversion process is relatively high. The system comprises a coke oven gas pretreatment unit (1), a methanation unit (2), a deep purification unit (3), a low temperature cold box 1 (4), a low temperature cold box 2 (9), a hydrogen purification and liquefaction unit (5), a CO conversion unit (6), a hydrogen recovery unit (7), and a methane conversion unit (8). The present invention has two operating modes, namely, producing LNG and producing hydrogen and liquid hydrogen. The product type can be flexibly adjusted according to market demand to improve the economic benefits of the device. The system can realize full recovery of effective components of coke oven gas, conform to the general trend of energy conservation and environmental protection, and has good economic benefits.

Description

Technical Field

[0001] The invention relates to a coke oven gas recovery and processing system and method, and in particular to a system and method for producing LNG and hydrogen products using coke oven gas as raw material. Background Art

[0002] Coke oven gas is a by-product of the coking process. Each ton of coke produced produces 380~420Nm 3 The main components of coke oven gas are hydrogen (50% to 70% by volume) and CH4 (18% to 30% by volume), as well as a small amount of CO, CO2 and nitrogen, among which hydrogen, CO and CH4 are all effective components that can be recycled. In recent years, the recycling of coke oven gas has mostly focused on the production of LNG, synthetic ammonia, methanol and ethylene glycol. Among them, chemical products such as synthetic ammonia, methanol and ethylene glycol are in a state of overproduction and fierce competition, and the price of LNG fluctuates greatly with the seasons. Therefore, the single product line is the main factor limiting the economic efficiency of coke oven gas recovery devices.

[0003] Hydrogen is an efficient and clean secondary energy source. It is an ideal energy carrier that can be obtained from a variety of channels and is one of the important bridges in the transition from fossil energy to renewable energy.

[0004] At the same time, in the existing coke oven gas treatment system, since the device only uses a cryogenic separation unit, the adjustment range of the product hydrogen and LNG is limited and cannot flexibly adapt to production needs. At the same time, the existing device lacks a methane conversion process, resulting in an unbalanced CO2 in the coke oven gas treatment system, and the investment in the full gas volume CO conversion process is high. Therefore, enriching the product line of comprehensive utilization of coke oven gas and flexibly adjusting the production mode according to market demand can not only improve the economy of the device, but also increase the energy utilization rate of coke oven gas. Summary of the invention

[0005] The purpose of the present invention is to provide a system and method for producing LNG and hydrogen products using coke oven gas as raw material, so as to solve the technical problems in the prior art of using coke oven gas to produce LNG and hydrogen products, such as limited product adjustment range, inability to flexibly adapt to market demand, inability to balance CO2 in the device, and high investment in CO conversion process.

[0006] To achieve the above object, the present invention provides the following technical solutions:

[0007] The present invention provides a system for producing LNG and hydrogen products using coke oven gas as raw material, comprising a coke oven gas pretreatment unit, a methanation unit, a deep purification unit, a low temperature cold box 1, a low temperature cold box 2, a hydrogen purification and liquefaction unit, a CO conversion unit, a hydrogen recovery unit and a methane conversion unit;

[0008] The outlet end of the coke oven gas pretreatment unit is connected to two branches, and the two branches are respectively connected to the methanation unit and the methane conversion unit. The outlet ends of the methanation unit and the methane conversion unit are both connected to the deep purification unit. The outlet end of the deep purification unit is connected to two branches, and the two branches are respectively connected to the low-temperature cold box one and the low-temperature cold box two; the low-temperature cold box one and the low-temperature cold box two are provided with a hydrogen-rich gas outlet end, and the hydrogen-rich gas outlet end is connected to the inlet of the hydrogen purification and liquefaction unit; the low-temperature cold box two is also provided with a CO-rich gas outlet end, and the CO-rich gas outlet end is connected to the CO conversion unit; the outlet end of the CO conversion unit is connected to the hydrogen recovery unit, and the outlet end of the hydrogen recovery unit is connected to the deep purification unit; the methanation unit, the methane conversion unit and the CO conversion unit are all connected to an external water supply unit; the methanation unit is also connected to an external CO2 supply unit;

[0009] The methanation unit is provided with a medium-pressure steam outlet, the deep purification unit is connected to a CO2 product outlet, the low-temperature cold box one is provided with a nitrogen-rich gas outlet one and an LNG product outlet one, the low-temperature cold box two is connected to an LNG product outlet two, the hydrogen recovery unit is provided with a nitrogen-rich gas outlet two, and the hydrogen purification and liquefaction unit is provided with a hydrogen product outlet.

[0010] Optionally or preferably, a valve V1A and a valve V1B are respectively provided on the connecting branches of the coke oven gas pretreatment unit and the methanation unit and the methane conversion unit;

[0011] The connecting branches between the deep purification unit and the low-temperature cold box 1 and the low-temperature cold box 2 are respectively provided with a valve V2A and a valve V2B.

[0012] Optionally or preferably, the external CO2 supply unit is connected to the CO2 product outlet, and a liquid or compressed CO2 storage tank is also provided on the connecting pipeline between the external CO2 supply unit and the CO2 product outlet.

[0013] The present invention provides a method for producing LNG and hydrogen products using coke oven gas as raw material, comprising the following steps:

[0014] S1. LNG production, the coke oven gas containing hydrogen, CH4, CO, nitrogen, heavy hydrocarbons and H2S impurities is transported to the coke oven gas pretreatment unit, the pretreated coke oven gas is sent to the gas side of the methanation unit together with the externally supplied CO2 through valve V1A, where hydrogen reacts with CO and CO2 under the action of a catalyst to generate CH4, and the externally supplied water takes away the reaction heat to obtain a medium-pressure steam product, the coke oven gas with increased CH4 content enters the deep purification unit, and the deeply purified coke oven gas enters the low-temperature cold box 1 through valve V2A, and obtains three products after low-temperature separation and distillation: the first product is LNG product A; the second product is hydrogen-rich gas A, which is sent to the hydrogen purification and liquefaction unit, where it is first purified by hydrogen to obtain a high-purity hydrogen product, and part or all of the high-purity hydrogen is then liquefied by hydrogen to obtain a liquid hydrogen product; the third product is nitrogen-rich gas A, which can be used as fuel gas for coke ovens or raw gas for synthetic ammonia;

[0015] S2. Hydrogen product production. Coke oven gas containing hydrogen, CH4, CO, nitrogen and a small amount of heavy hydrocarbons, H2S and other impurities enters the coke oven gas pretreatment unit. The pretreated coke oven gas enters the methane conversion unit through valve V1B, where methane reacts with external water to generate hydrogen, CO and CO2. The converted gas is mixed with the recovered hydrogen at the outlet of the hydrogen recovery unit and enters the deep purification unit for deep treatment. The removed CO2 is used as the CO2 product. The deeply purified coke oven gas enters the low-temperature cold box 2 through valve V2B, and three products are obtained after low-temperature separation and distillation: the first product is LNG product B; the second product is hydrogen-rich gas B, the hydrogen-rich gas B is sent to the hydrogen purification and liquefaction unit, where it is first purified by hydrogen to obtain a high-purity hydrogen product, and part or all of the high-purity hydrogen is then liquefied by hydrogen to obtain a liquid hydrogen product; the third product is CO-rich gas, which enters the CO conversion unit, where CO reacts with external water to produce hydrogen and CO2, and the conversion gas then enters the hydrogen recovery unit, and undergoes processes such as hydrogen separation and hydrogen recovery pressurization to obtain two products: the first product is nitrogen-rich gas B, which can be used as a fuel gas for a coke oven or a raw gas for synthetic ammonia; the second product is recovered hydrogen, which is mixed with the conversion gas at the outlet of the methane conversion unit and enters the deep purification unit together.

[0016] Optionally or preferably, the coke oven gas pretreatment unit includes detarring, desulfurization, naphthalene removal, deamination, debenzene removal and coke oven gas pressurization processes.

[0017] Optionally or preferably, the deep purification unit includes deep dehydration, CO2 removal, heavy hydrocarbon removal and mercury removal processes.

[0018] Optionally or preferably, the low temperature cold box 1 and the low temperature cold box 2 each include heat exchange, distillation and refrigeration cycle processes;

[0019] The distillation process adopts single-tower, double-tower or multi-tower distillation technology, and the refrigeration cycle adopts at least one of nitrogen cycle and mixed refrigerant cycle technology.

[0020] Optionally or preferably, the hydrogen purification and liquefaction unit includes hydrogen purification and hydrogen liquefaction processes;

[0021] The hydrogen purification adopts at least one of pressure swing adsorption, membrane separation and low temperature washing technology.

[0022] Optionally or preferably, the hydrogen recovery unit includes hydrogen separation and hydrogen recovery pressurization processes, wherein hydrogen separation adopts a combination of one or more technologies of pressure swing adsorption and membrane separation.

[0023] Optionally or preferably, the methane conversion unit adopts at least one of methane steam reforming, catalytic partial oxidation, non-catalytic partial oxidation and high temperature catalytic cracking technologies.

[0024] Based on the above technical solution, the embodiments of the present invention can at least produce the following technical effects:

[0025] (1) The system and method for producing LNG and hydrogen using coke oven gas as raw material provided by the present invention have two operating modes of producing hydrogen and liquid hydrogen while producing LNG products. The product adjustment range is large, and the product type can be flexibly adjusted according to market demand. The product production mode can be adjusted in time according to market demand, thereby improving the economic benefits of the system for producing LNG and hydrogen using coke oven gas.

[0026] (2) The system and method for producing LNG and hydrogen using coke oven gas as raw material provided by the present invention can realize the complete recovery of effective components of coke oven gas, fully recycle and utilize the components of coke oven gas, improve the recycling efficiency of products and improve the economic effect of products. At the same time, the system stores the product CO2 prepared by the product in a CO2 storage tank and reuses it, so as to achieve the CO2 balance of the system, avoid or reduce CO2 emissions, comply with the general trend of energy conservation and environmental protection, and bring good economic benefits to the operation of the system. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a schematic structural diagram of an embodiment of the present invention.

[0028] In the figure: 1. Coke oven gas pretreatment unit; 2. Methanation unit; 3. Deep purification unit; 4. Low temperature cold box 1; 5. Hydrogen purification and liquefaction unit; 6. CO conversion unit; 7. Hydrogen recovery unit; 8. Methane conversion unit; 9. Low temperature cold box 2. DETAILED DESCRIPTION

[0029] To make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be described in detail below. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other implementation methods obtained by ordinary technicians in this field without creative work belong to the scope of protection of the present invention.

[0030] Example 1

[0031] The present invention provides a system for producing LNG and hydrogen products using coke oven gas as raw material, comprising a coke oven gas pretreatment unit 1, a methanation unit 2, a deep purification unit 3, a low temperature cold box 1 4, a low temperature cold box 2 9, a hydrogen purification and liquefaction unit 5, a CO conversion unit 6, a hydrogen recovery unit 7 and a methane conversion unit 8;

[0032] The outlet end of the coke oven gas pretreatment unit is connected to two branches, and the two branches are connected to the methanation unit 2 and the methane conversion unit 8 respectively. The outlet end of the methanation unit 2 and the outlet end of the methane conversion unit 8 are both connected to the deep purification unit 3. The outlet end of the deep purification unit 3 is connected to two branches, and the two branches are respectively connected to the low-temperature cold box 1 4 and the low-temperature cold box 2 9; the low-temperature cold box 1 4 and the low-temperature cold box 2 9 are provided with a hydrogen-rich outlet end, and the hydrogen-rich outlet end is connected to the inlet of the hydrogen purification and liquefaction unit 5; the low-temperature cold box 2 9 is also provided with a CO-rich outlet end, and the CO-rich outlet end is connected to the CO conversion unit 6; the outlet end of the CO conversion unit 6 is connected to the hydrogen recovery unit 7, and the outlet end of the hydrogen recovery unit 7 is connected to the deep purification unit 3; the methanation unit 2, the methane conversion unit 8 and the CO conversion unit 6 are all connected to an external water supply unit; the methanation unit 2 is also connected to an external CO2 supply unit;

[0033] The methanation unit 2 is provided with a medium-pressure steam outlet, the deep purification unit 3 is connected to a CO2 product outlet, the low-temperature cold box 1 4 is respectively provided with a nitrogen-rich gas outlet 1 and an LNG product outlet 1, the low-temperature cold box 2 9 is connected to an LNG product outlet 2, the hydrogen recovery unit 7 is provided with a nitrogen-rich gas outlet 2, and the hydrogen purification and liquefaction unit 5 is provided with a hydrogen product outlet.

[0034] The coke oven gas pretreatment unit 1 provided by the present invention can perform detarring, desulfurization, naphthalene removal, deamination, debenzene removal and coke oven gas pressurization treatment; the deep purification unit 3 can perform deep dehydration, CO2 removal, heavy hydrocarbon removal and mercury removal treatment; the low-temperature cold box 1 4 and the low-temperature cold box 2 9 can respectively perform heat exchange, distillation and refrigeration cycle treatment, the distillation is a single-tower, double-tower or multi-tower distillation device, and the refrigeration cycle is at least one of a nitrogen cycle and a mixed refrigerant cycle unit; the hydrogen purification and liquefaction unit 5 can perform hydrogen purification and hydrogen liquefaction, and the hydrogen purification is achieved by at least one of pressure swing adsorption, membrane separation and low-temperature washing unit; the hydrogen recovery unit 7 can perform hydrogen separation and hydrogen recovery pressurization, wherein the hydrogen separation is processed by at least one of pressure swing adsorption and membrane separation; the methane conversion unit 8 can perform at least one step of methane steam conversion, catalytic partial oxidation, non-catalytic partial oxidation and high-temperature catalytic cracking.

[0035] The system provided by the present invention for producing LNG and hydrogen using coke oven gas as raw material has two operating modes for producing hydrogen and liquid hydrogen while producing LNG products. The product has a large adjustment range and can flexibly adjust the product type according to market demand. The product production mode can be adjusted in time according to market demand, thereby improving the economic benefits of the system for producing LNG and hydrogen using coke oven gas. In addition, the system provided by the present invention can also realize the complete recovery of effective components of coke oven gas, fully recover and utilize the components of coke oven gas, improve the recovery and utilization efficiency of products, and improve the economic benefits of products.

[0036] Example 2

[0037] like Figure 1 As shown:

[0038] Compared with the embodiment, the connecting branches of the coke oven gas pretreatment unit 1 and the methanation unit 2 and the methane conversion unit 8 in this embodiment are respectively provided with valves V1A and V1B;

[0039] The connecting branches between the deep purification unit 3 and the low-temperature cold box 1 4 and the low-temperature cold box 2 9 are respectively provided with a valve V2A and a valve V2B.

[0040] By setting valves on each connecting branch, it is convenient to control the distribution of incoming gas to be treated, and adjust the product treatment process and treatment route according to demand.

[0041] Example 3

[0042] Compared with Example 2, the external CO2 supply unit in this embodiment is connected to the CO2 product outlet, and a liquid or compressed CO2 storage tank is also provided on the connecting pipeline between the external CO2 supply unit and the CO2 product outlet.

[0043] In this embodiment, the CO2 product produced by the product is recycled into the system, realizing the recycling of the device products and the added gas, reducing the cost requirements for producing LNG and hydrogen, and bringing good economic benefits to the operation of the system; at the same time, the product CO2 prepared by the product is stored in a CO2 storage tank and reused, which can avoid or reduce CO2 emissions and conform to the general trend of energy conservation and environmental protection.

[0044] Experimental example

[0045] The present invention provides a method for producing LNG and hydrogen products using coke oven gas as raw material, comprising the following steps:

[0046] S1. LNG production, the coke oven gas containing hydrogen, CH4, CO, nitrogen, heavy hydrocarbons and H2S impurities is transported to the coke oven gas pretreatment unit 1, the pretreated coke oven gas is sent to the gas side of the methanation unit 2 through valve V1A together with external CO2, wherein hydrogen reacts with CO and CO2 under the action of a catalyst to generate CH4, and the external water takes away the reaction heat to obtain a medium-pressure steam product, the coke oven gas with increased CH4 content enters the deep purification unit 3, and the deeply purified coke oven gas enters the low-temperature cold box 4 through valve V2A, and three products are obtained after low-temperature separation and distillation: the first product is LNG product A; the second product is hydrogen-rich gas A, which is sent to the hydrogen purification and liquefaction unit 5, wherein it is first purified by hydrogen to obtain a high-purity hydrogen product, and part or all of the high-purity hydrogen is then liquefied by hydrogen to obtain a liquid hydrogen product; the third product is nitrogen-rich gas A, which can be used as a fuel gas for a coke oven or a raw gas for synthetic ammonia;

[0047] S2. Hydrogen product production, coke oven gas containing hydrogen, CH4, CO, nitrogen and a small amount of heavy hydrocarbons, H2S and other impurities enters the coke oven gas pretreatment unit 1, and the pretreated coke oven gas enters the methane conversion unit 8 through valve V1B, where methane reacts with external water to generate hydrogen, CO and CO2, and the converted gas is mixed with the recovered hydrogen at the outlet of the hydrogen recovery unit 7, and enters the deep purification unit 3 together for deep treatment, and the removed CO2 is used as the CO2 product. The deeply purified coke oven gas enters the low-temperature cold box 2 9 through valve V2B, and three products are obtained after low-temperature separation and distillation: the first product is LNG product B; the second product is hydrogen-rich gas B, the hydrogen-rich gas B is sent to the hydrogen purification and liquefaction unit 5, in which it is first purified by hydrogen to obtain a high-purity hydrogen product, and part or all of the high-purity hydrogen is then liquefied by hydrogen to obtain a liquid hydrogen product; the third product is CO-rich gas, which enters the CO conversion unit 6, in which CO reacts with external water to produce hydrogen and CO2, and the conversion gas then enters the hydrogen recovery unit 7, and undergoes hydrogen separation, recovery hydrogen pressurization and other processes to obtain two products: the first product is nitrogen-rich gas B, which can be used as a fuel gas for a coke oven or a raw gas for synthetic ammonia; the second product is recovered hydrogen, which is mixed with the conversion gas at the outlet of the methane conversion unit 8 and enters the deep purification unit 3 together.

[0048] As an optional embodiment, the coke oven gas pretreatment unit 1 includes detarring, desulfurization, naphthalene removal, deamination, debenzene removal and coke oven gas pressurization processes.

[0049] As an optional embodiment, the deep purification unit 3 includes deep dehydration, CO2 removal, heavy hydrocarbon removal and mercury removal processes.

[0050] As an optional embodiment, the low temperature cold box 1 4 and the low temperature cold box 2 9 each include heat exchange, distillation and refrigeration cycle processes;

[0051] The distillation process adopts single-tower, double-tower or multi-tower distillation technology, and the refrigeration cycle adopts at least one of nitrogen cycle and mixed refrigerant cycle technology.

[0052] As an optional embodiment, the hydrogen purification and liquefaction unit 5 includes hydrogen purification and hydrogen liquefaction processes;

[0053] The hydrogen purification adopts at least one of pressure swing adsorption, membrane separation and low temperature washing technology.

[0054] As an optional embodiment, the hydrogen recovery unit 7 includes a hydrogen separation and a recovered hydrogen pressurization process, wherein the hydrogen separation adopts a combination of one or more technologies of pressure swing adsorption and membrane separation.

[0055] As an optional embodiment, the methane conversion unit 8 adopts at least one of methane steam reforming, catalytic partial oxidation, non-catalytic partial oxidation and high-temperature catalytic cracking technologies.

[0056] As an optional implementation, the operating pressure of the purified coke oven gas is between 1.5 and 5.0 MPa.G, the hydrogen content can vary between 5% and 90%, and the methane content can vary between 95% and 2%.

[0057] As an optional embodiment, the heat exchanger, distillation tower and refrigeration cycle in the cryogenic cold box 1 4 and the cryogenic cold box 2 9 may be independently configured or integrated into one cryogenic cold box.

[0058] The above is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art can easily think of changes or substitutions within the technical scope disclosed by the present invention, which should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims

1. A system for producing LNG and hydrogen products using coke oven gas as raw material, characterized in that: It comprises a coke oven gas pretreatment unit (1), a methanation unit (2), a deep purification unit (3), a low temperature cold box 1 (4), a low temperature cold box 2 (9), a hydrogen purification and liquefaction unit (5), a CO conversion unit (6), a hydrogen recovery unit (7) and a methane conversion unit (8); the coke oven gas pretreatment unit (1) comprises a detarring, a desulfurizing, a naphthalene removing, ammonia removing, a benzene removing and a coke oven gas pressurizing process; The outlet end of the coke oven gas pretreatment unit is connected to two branches, and the two branches are respectively connected to the methanation unit (2) and the methane conversion unit (8); the outlet end of the methanation unit (2) and the outlet end of the methane conversion unit (8) are both connected to the deep purification unit (3); the outlet end of the deep purification unit (3) is connected to two branches, and the two branches are respectively connected to the low-temperature cold box 1 (4) and the low-temperature cold box 2 (9); the low-temperature cold box 1 (4) and the low-temperature cold box 2 (9) are provided with hydrogen-rich gas outlet ends, and the hydrogen-rich gas outlet ends are connected to the deep purification unit (3); The inlet of the hydrogen purification and liquefaction unit (5) is connected; the low-temperature cold box (9) is also provided with a CO2-rich gas outlet, and the CO2-rich gas outlet is connected to the CO2 conversion unit (6); the outlet of the CO2 conversion unit (6) is connected to the hydrogen recovery unit (7), and the outlet of the hydrogen recovery unit (7) is connected to the deep purification unit (3); the methanation unit (2), the methane conversion unit (8) and the CO2 conversion unit (6) are all connected to an external water supply unit; the methanation unit (2) is also connected to an external CO2 supply unit; The methanation unit (2) is provided with a medium-pressure steam outlet, the deep purification unit (3) is connected to a CO2 product outlet, the low-temperature cold box (4) is provided with a nitrogen-rich gas outlet (1) and an LNG product outlet (1), the low-temperature cold box (9) is connected to an LNG product outlet (2), the hydrogen recovery unit (7) is provided with a nitrogen-rich gas outlet (2), and the hydrogen purification and liquefaction unit (5) is provided with a hydrogen product outlet; The deep purification unit (3) includes deep dehydration, CO2 removal, heavy hydrocarbon removal and mercury removal processes; The cryogenic cold box 1 (4) and the cryogenic cold box 2 (9) respectively include heat exchange, distillation and refrigeration cycle processes; The distillation adopts single-tower, double-tower or multi-tower distillation technology, and the refrigeration cycle adopts at least one of nitrogen cycle and mixed refrigerant cycle technology; The hydrogen purification and liquefaction unit (5) includes hydrogen purification and hydrogen liquefaction processes; The hydrogen purification adopts at least one of pressure swing adsorption, membrane separation and low temperature washing technology; The hydrogen recovery unit (7) includes a hydrogen separation and a recovered hydrogen pressurization process, wherein the hydrogen separation adopts a combination of one or more technologies selected from pressure swing adsorption and membrane separation; The methane conversion unit (8) adopts at least one of methane steam reforming, catalytic partial oxidation, non-catalytic partial oxidation and high-temperature catalytic cracking technologies.

2. A system for producing LNG and hydrogen products using coke oven gas as raw material according to claim 1, characterized in that: The connecting branches between the coke oven gas pretreatment unit (1) and the methanation unit (2) and the methane conversion unit (8) are respectively provided with valves V1A and V1B; A valve V2A and a valve V2B are respectively provided on the connecting branches between the deep purification unit (3) and the low-temperature cold box 1 (4) and the low-temperature cold box 2 (9).

3. A system for producing LNG and hydrogen products using coke oven gas as raw material according to claim 1, characterized in that: The external CO2 supply unit is connected to the CO2 product outlet, and a liquid or compressed CO2 storage tank is also provided on the connecting pipeline between the external CO2 supply unit and the CO2 product outlet.

4. The application method of the system for producing LNG and hydrogen products using coke oven gas as raw material according to any one of claims 1 to 3, characterized in that: The following steps are involved: S1. LNG production, coke oven gas containing hydrogen, CH4, CO, nitrogen, heavy hydrocarbons and H2S impurities is transported to the coke oven gas pretreatment unit (1), the pretreated coke oven gas is sent to the gas side of the methanation unit (2) through valve V1A together with externally supplied CO2, wherein hydrogen reacts with CO and CO2 under the action of a catalyst to generate CH4, and the reaction heat is taken away by externally supplied water to obtain a medium-pressure steam product, the coke oven gas with increased CH4 content enters the deep purification unit (3), the deeply purified coke oven gas enters the low-temperature cold box 1 (4) through valve V2A, and three products are obtained after low-temperature separation and distillation: the first product is LNG product A; the second product is hydrogen-rich gas A, which is sent to the hydrogen purification and liquefaction unit (5), wherein it is first purified by hydrogen to obtain a high-purity hydrogen product, and part or all of the high-purity hydrogen is then liquefied by hydrogen to obtain a liquid hydrogen product; the third product is nitrogen-rich gas A, which is used as fuel gas for the coke oven or raw gas for synthetic ammonia; S2. Hydrogen product production, coke oven gas containing hydrogen, CH4, CO, nitrogen and a small amount of heavy hydrocarbons and H2S impurities enters the coke oven gas pretreatment unit (1), and the coke oven gas after pretreatment enters the methane conversion unit (8) through valve V1B, where methane reacts with external water to generate hydrogen, CO and CO2, and the converted gas is mixed with the recovered hydrogen at the outlet of the hydrogen recovery unit (7) and enters the deep purification unit (3) for deep treatment. The removed CO2 is used as the CO2 product. The deeply purified coke oven gas enters the low-temperature cold box II (9) through valve V2B, and after low-temperature separation and distillation, three products are obtained: the first product is LNG product B; the second product is hydrogen-rich product B; The hydrogen-rich gas B is sent to the hydrogen purification and liquefaction unit (5), where it is first purified by hydrogen to obtain a high-purity hydrogen product, and part or all of the high-purity hydrogen is then liquefied by hydrogen to obtain a liquid hydrogen product; the third product is CO-rich gas, which enters the CO conversion unit (6), where CO reacts with external water to produce hydrogen and CO2, and the converted gas then enters the hydrogen recovery unit (7), and undergoes hydrogen separation and hydrogen recovery and pressurization processes to obtain two products: the first product is nitrogen-rich gas B, which is used as fuel gas for coke ovens or raw gas for synthetic ammonia; the second product is recovered hydrogen, which is mixed with the conversion gas at the outlet of the methane conversion unit (8) and enters the deep purification unit (3) together.

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