Low-carbon-emission aromatic hydrocarbon production device and method

Abstract

The invention relates to the technical field of aromatic hydrocarbon production, and particularly discloses a low-carbon-emission aromatic hydrocarbon production device and method.The device comprises an aromatic hydrocarbon production unit, a carbon dioxide capture unit, a hydrogen purification unit, a carbon-1 recovery unit and a carbon-based compound synthesis unit, the aromatic hydrocarbon production unit is respectively connected with the carbon dioxide capture unit and the hydrogen purification unit; the hydrogen recovery unit is connected with the carbon I recovery unit; the carbon-based compound synthesis unit is respectively connected with the carbon dioxide capture unit and the carbon-I recovery unit. According to the low-carbon-emission aromatic hydrocarbon production device, hydrogen-containing gas and waste gas generated by the aromatic hydrocarbon production unit are effectively separated, separated products are fully utilized, and near-zero emission of carbon dioxide is achieved.

Description

Technical Field

[0001] This invention relates to the field of aromatics production technology, and specifically to an aromatics production apparatus and method with low carbon emissions. Background Technology

[0002] Reforming technology includes semi-regenerative reforming and continuous reforming. Reforming is a crucial foundational process in the oil refining industry and a major source of aromatics such as benzene, toluene, and xylene. As of 2021, my country had over 110 continuous reforming units with an annual processing capacity of 140 million tons. Because reforming is an endothermic reaction, existing technologies all use heaters to heat the reaction. Reforming units consume large amounts of fuel gas, and the carbon dioxide emitted into the atmosphere through the heater flue gas accounts for 40-50% of the total carbon dioxide emissions from these units. Therefore, reducing carbon emissions from reforming units has become an urgent problem to solve.

[0003] In existing technologies, over 10% of the exhaust gas produced by heating furnaces is carbon dioxide, which is directly emitted into the atmosphere, causing adverse environmental impacts. Simultaneously, methane is produced through cracking reactions in hydrogenation and catalytic cracking processes within the equipment. Current technologies burn this as fuel gas, converting it back into carbon dioxide and releasing it into the atmosphere. This results in both resource waste and increased carbon emissions. Therefore, how to effectively utilize carbon dioxide and methane has become a research topic requiring further investigation.

[0004] Carbon-based compound synthesis converts carbon dioxide and methane into carbon monoxide and hydrogen, commonly known as syngas. These gases can undergo many valuable reactions, such as hydroformylation of olefins to produce alcohols or aldehydes. However, this reaction requires fuel heating, and using conventional fuel gases would result in carbon emissions. In contrast, aromatics production units such as reforming and light hydrocarbon aromatization can generate hydrogen, which serves as a clean fuel to provide heat for carbon-based compound synthesis reactions, thus solving the heating problem in these reactions.

[0005] Based on this technical background, the present invention studies a low-carbon emission aromatics production device and method. Summary of the Invention

[0006] To address the shortcomings of existing technologies, this invention proposes a low-carbon emission aromatics production device and method. This device effectively separates hydrogen-containing gases and waste gases generated by the aromatics production unit by rationally setting up an aromatics production unit, a carbon dioxide capture unit, a hydrogen purification unit, a C1 recovery unit, and a carbon-based compound synthesis unit, and makes full use of the separated products, thereby achieving near-zero carbon dioxide emissions.

[0007] To achieve the above objectives, a first aspect of the present invention provides a low-carbon emission aromatics production apparatus, comprising:

[0008] The aromatics production unit is equipped with a raw material feed pipeline, a reaction product oil extraction pipeline, a waste gas discharge pipeline, and a hydrogen-containing gas discharge pipeline.

[0009] A carbon dioxide capture unit is connected to the exhaust gas discharge pipeline and is equipped with a carbon dioxide discharge pipeline.

[0010] A hydrogen purification unit is connected to the hydrogen-containing gas discharge pipeline and is equipped with a purified hydrogen discharge pipeline and a hydrocarbon-containing gas discharge pipeline, respectively.

[0011] The C1 recovery unit is connected to the hydrocarbon gas discharge pipeline and is equipped with an optional dry gas feed pipeline containing C1-C4, an optional natural gas feed pipeline, a methane discharge pipeline, an ethane-rich gas extraction pipeline, and a recovered hydrogen discharge pipeline.

[0012] The carbon-based compound synthesis unit is connected to the carbon dioxide discharge pipeline and the methane discharge pipeline, respectively, and is equipped with a mixed gas extraction pipeline and a purified hydrogen inlet pipeline.

[0013] A hydrogen extraction pipeline connects to the purified hydrogen discharge pipeline and the recovered hydrogen discharge pipeline, with a branch of the purified hydrogen discharge pipeline serving as the purified hydrogen inlet unit pipeline.

[0014] A second aspect of the present invention provides a method for producing aromatics with low carbon emissions in the above-mentioned apparatus, the method comprising the following steps:

[0015] The raw materials are fed into the aromatics production unit for reforming or light hydrocarbon aromatization to obtain reaction products, hydrogen-containing gases and waste gases.

[0016] The waste gas is sent to a carbon dioxide capture unit for separation to obtain carbon dioxide.

[0017] The hydrogen-containing gas is fed into a hydrogen purification unit to purify it into purified hydrogen and hydrocarbon gas.

[0018] The hydrocarbon gas, optional dry gas containing C1-C4 from the entire plant, and optional natural gas are fed into the C1 recovery unit to recover methane, ethane-rich gas, and recovered hydrogen.

[0019] The carbon dioxide and methane are fed into a carbon-based compound synthesis unit, and a mixed gas is obtained by burning partially purified hydrogen for heating.

[0020] The effects of this invention are:

[0021] (1) The low-carbon emission aromatics production device proposed in this invention effectively separates the hydrogen-containing gas and waste gas generated by the aromatics production unit by rationally setting up the aromatics production unit, carbon dioxide capture unit, hydrogen purification unit, C1 recovery unit and carbon-based compound synthesis unit, and makes full use of the separated products, thus achieving near-zero carbon dioxide emissions.

[0022] (2) The low-carbon emission aromatics production device proposed in this invention is connected to the carbon dioxide capture unit and the hydrogen purification unit respectively through the aromatics production unit; the hydrogen recovery unit is connected to the C1 recovery unit; and the carbon-based compound synthesis unit is connected to the carbon dioxide capture unit and the C1 recovery unit respectively, so as to achieve near-zero carbon dioxide emission of the exhaust gas of the aromatics production unit, thereby significantly reducing the carbon emission of the aromatics production unit.

[0023] (3) The low-carbon emission aromatics production method proposed in this invention recovers carbon dioxide from waste gas through a carbon dioxide capture unit, and recovers methane, ethane-rich gas and hydrogen through a hydrogen purification unit and a C1 recovery unit. Methane and carbon dioxide are synthesized into carbon monoxide and hydrogen through carbon-based compound synthesis, making full use of the by-products generated by reforming and achieving near-zero carbon dioxide emissions.

[0024] (4) The low-carbon emission aromatics production method proposed in this invention utilizes the methane generated by the C1 recovery unit and the carbon dioxide generated by the carbon dioxide capture unit to synthesize carbon-based compounds to produce carbon monoxide and hydrogen. The insufficient methane is supplemented by optional dry gas containing C1-C4 throughout the plant, and optional natural gas is supplemented by recovering methane through the C1 recovery unit. The heat of reaction for the synthesis of carbon-based compounds is provided by the combustion of purified hydrogen generated by the hydrogen purification unit, thus realizing the efficient recycling of by-products generated by reforming.

[0025] (5) The low-carbon emission aromatics production method proposed in this invention uses organic amine absorption or air separation-flue gas recirculation to recover carbon dioxide, thereby improving the recovery efficiency.

[0026] Other features and advantages of the present invention will be described in detail in the following detailed description section. Attached Figure Description

[0027] The above and other objects, features and advantages of the present invention will become more apparent from the more detailed description of exemplary embodiments of the invention in conjunction with the accompanying drawings, wherein the same reference numerals generally represent the same components in the exemplary embodiments of the invention.

[0028] Figure 1 This is a schematic diagram of the structure of the low-carbon emission aromatics production device proposed in this invention.

[0029] Explanation of reference numerals in the attached figures:

[0030] 1-Aromatic hydrocarbon production unit, 2-Carbon dioxide capture unit, 3-Hydrogen purification unit, 4-C1 recovery unit, 5-Carbon-based compound synthesis unit;

[0031] a-Raw material, b-Reaction-produced oil, c-Waste gas, d-Carbon dioxide, e-Hydrogen-containing gas, f-Purified hydrogen, g-Hydrocarbon-containing gas, h-Dry gas containing C1-C4 atoms from the entire plant, i-Natural gas, j-Ethane-rich gas, k-Recovered hydrogen, l-Methane, m-Mixed gas, n-Partially purified hydrogen. Detailed Implementation

[0032] Preferred embodiments of the invention will now be described in more detail. While preferred embodiments of the invention are described below, it should be understood that the invention can be implemented in various forms and should not be limited to the embodiments set forth herein.

[0033] In this disclosure, unless otherwise stated, directional terms such as "upper" and "lower" generally refer to the upper and lower positions of the device in its normal operating state, for example, as shown in the reference. Figure 1 In the drawing orientation, "inner" and "outer" refer to their relative to the outline of the device. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first," "second," or "third" may explicitly or implicitly include one or more of that feature. In the description of this disclosure, "a plurality of" means two or more, unless otherwise explicitly specified.

[0034] This invention provides a low-carbon emission aromatics production apparatus, such as... Figure 1 As shown, it includes:

[0035] Aromatics production unit 1 is equipped with a naphtha feed pipeline, a reaction product oil extraction pipeline, a waste gas discharge pipeline, and a hydrogen-containing gas discharge pipeline.

[0036] Carbon dioxide capture unit 2 is connected to the exhaust gas discharge pipeline and is equipped with a carbon dioxide discharge pipeline.

[0037] Hydrogen purification unit 3 is connected to a hydrogen-containing gas discharge pipeline and is equipped with a purified hydrogen discharge pipeline and a hydrocarbon-containing gas discharge pipeline, respectively.

[0038] C1 recovery unit 4 is connected to the hydrocarbon gas discharge pipeline and is equipped with an optional dry gas feed pipeline containing C1-C4, an optional natural gas feed pipeline, a methane discharge pipeline, an ethane-rich gas extraction pipeline, and a recovered hydrogen discharge pipeline.

[0039] The carbon-based compound synthesis unit 5 is connected to the carbon dioxide discharge pipeline and the methane discharge pipeline, and is also equipped with a mixed gas extraction pipeline and a purified hydrogen inlet pipeline.

[0040] The hydrogen extraction pipeline connects to the purified hydrogen discharge pipeline and the recovered hydrogen discharge pipeline. A branch of the purified hydrogen discharge pipeline serves as the purified hydrogen inlet pipeline.

[0041] In this invention, by rationally setting up the aromatics production unit 1, carbon dioxide capture unit 2, hydrogen purification unit 3, C1 recovery unit 4, and carbon-based compound synthesis unit 5, the hydrogen-containing gas e and waste gas c generated by the aromatics production unit 1 are effectively separated, and the separated products are fully utilized, achieving near-zero carbon dioxide emissions.

[0042] In this invention, the aromatics production unit 1 is connected to the carbon dioxide capture unit 2 and the hydrogen purification unit 3 respectively; the hydrogen recovery unit is connected to the C1 recovery unit 4; and the carbon-based compound synthesis unit 5 is connected to the carbon dioxide capture unit 2 and the C1 recovery unit 4 respectively, so as to achieve near-zero carbon dioxide emissions from the exhaust gas of the aromatics production unit 1, thereby significantly reducing the carbon emissions of the aromatics production unit 1.

[0043] According to the present invention, the aromatics production unit 1 is a continuous reforming unit, or a semi-regenerative reforming unit, or a light hydrocarbon aromatization unit, preferably a continuous reforming unit.

[0044] The carbon dioxide capture unit 2 is an organic amine absorption unit or an air separation-flue gas recirculation unit, preferably an organic amine absorption unit;

[0045] Both aromatics production unit 1 and carbon-based compound synthesis unit 5 are equipped with their own independent heating furnaces;

[0046] The exhaust gas pipeline is connected to the heating furnace of aromatics production unit 1.

[0047] According to the present invention, the exhaust gas discharge pipeline, hydrogen-containing gas discharge pipeline, carbon dioxide discharge pipeline, hydrocarbon-containing gas discharge pipeline and methane discharge pipeline are each equipped with their own independent control valves, which are used to control the gas volume of the corresponding pipeline according to the changes in feed.

[0048] Each raw material feed pipeline, the dry gas feed pipeline containing C1-C4 throughout the plant, and the natural gas feed pipeline is equipped with its own independent flow valve. The independent flow valve is used to control the amount of material fed into the pipeline.

[0049] The present invention also provides a method for producing aromatics with low carbon emissions in the above-mentioned apparatus, the method comprising the following steps:

[0050] Raw material a is fed into aromatics production unit 1 for reforming or light hydrocarbon aromatization to obtain reaction product oil b, hydrogen-containing gas e and waste gas c.

[0051] Waste gas c is sent into carbon dioxide capture unit 2 for separation to obtain carbon dioxide d;

[0052] Hydrogen-containing gas e is fed into hydrogen purification unit 3 and purified to obtain purified hydrogen gas f and hydrocarbon gas g.

[0053] Hydrocarbon gas g, optional dry gas containing C1-C4 from the whole plant h, and optional natural gas i are fed into the C1 recovery unit 4 to recover methane 1, ethane-rich gas j, and recovered hydrogen k.

[0054] Carbon dioxide d and methane l are fed into carbon-based compound synthesis unit 5, and a mixed gas m is obtained by combustion heating using partially purified hydrogen n.

[0055] In this invention, carbon dioxide d in waste gas c is recovered through carbon dioxide capture unit 2, and hydrogen-containing gas e is recovered through hydrogen purification unit 3 and C1 recovery unit 4 to recover methane 1, ethane-rich gas j, and hydrogen. Methane 1 and carbon dioxide d are synthesized into carbon monoxide and hydrogen through carbon-based compound synthesis, making full use of the by-products generated by reforming and achieving near-zero carbon dioxide emissions.

[0056] According to the present invention, raw material a is at least one of naphtha, liquefied petroleum gas, and light hydrocarbons;

[0057] Waste gas c includes flue gas from the heating furnace of the aromatics production unit and emissions from catalyst regeneration;

[0058] The separation methods used are organic amine absorption or air separation-flue gas recirculation.

[0059] The purification method used is pressure swing adsorption or membrane separation.

[0060] The recovery method used is a combination of cryogenic separation and distillation, membrane separation, or pressure swing adsorption.

[0061] Hydrocarbon gases include at least one of methane, ethane, propane, and butane.

[0062] Preferably, when raw material a is naphtha, raw material a is subjected to continuous reforming or semi-regenerative reforming to obtain reaction product oil b, hydrogen-containing gas e and waste gas c;

[0063] When raw material a is at least one of liquefied gas and light hydrocarbons, light hydrocarbon aromatization of raw material a yields reaction product oil b, hydrogen-containing gas e, and waste gas c.

[0064] The separation method used was the organic amine absorption method.

[0065] According to the present invention, optional dry gas h containing C1-C4 from the entire plant, and optional natural gas i are used to supplement the methane l recovered from hydrocarbon gas g;

[0066] The gas mixture m includes carbon monoxide and hydrogen;

[0067] The percentage of partially purified hydrogen (n) to the total purified hydrogen (f) is 35-55%.

[0068] According to the present invention, the number of moles of carbon dioxide d is greater than or equal to the number of moles of methane 1.

[0069] Preferably, when the number of moles of carbon dioxide d is greater than the number of moles of methane l, the amount of optional dry gas h containing C1-C4 from the whole plant and optional natural gas i is increased so that the number of moles of methane l obtained by the C1 recovery unit 4 is equal to the number of moles of carbon dioxide d.

[0070] Preferably, when the number of moles of carbon dioxide d is greater than the number of moles of methane 1, the amount of optional natural gas i added is increased so that the number of moles of methane 1 obtained by the C1 recovery unit 4 is equal to the number of moles of carbon dioxide d.

[0071] In this invention, methane l produced by C1 recovery unit 4 and carbon dioxide d produced by carbon dioxide capture unit 2 are used to synthesize carbon-based compounds to generate carbon monoxide and hydrogen. If there is insufficient methane l, it is supplemented by dry gas h containing C1-C4 from the entire plant and natural gas i after recovering methane l through C1 recovery unit 4. The heat of reaction for carbon-based compound synthesis is provided by the combustion of purified hydrogen f generated by hydrogen purification unit 3, thus realizing the efficient recycling of by-products generated by reforming.

[0072] In this invention, carbon dioxide d is recovered by using an organic amine absorption method or an air separation-flue gas recirculation method, which improves the recovery efficiency.

[0073] The present invention will now be described in more detail through a specific embodiment.

[0074] Example 1

[0075] like Figure 1 As shown, this embodiment provides a low-carbon emission aromatics production apparatus, comprising:

[0076] Aromatics production unit 1 is equipped with a naphtha feed pipeline, a reaction product oil extraction pipeline, a waste gas discharge pipeline, and a hydrogen-containing gas discharge pipeline.

[0077] Carbon dioxide capture unit 2 is connected to the exhaust gas discharge pipeline and is equipped with a carbon dioxide discharge pipeline.

[0078] Hydrogen purification unit 3 is connected to a hydrogen-containing gas discharge pipeline and is equipped with a purified hydrogen discharge pipeline and a hydrocarbon-containing gas discharge pipeline, respectively.

[0079] C1 recovery unit 4 is connected to the hydrocarbon gas discharge pipeline and is equipped with dry gas feed pipeline containing C1-C4, natural gas feed pipeline, methane discharge pipeline, ethane-rich gas extraction pipeline and recovered hydrogen discharge pipeline.

[0080] The carbon-based compound synthesis unit 5 is connected to the carbon dioxide discharge pipeline and the methane discharge pipeline, and is also equipped with a mixed gas extraction pipeline and a purified hydrogen inlet pipeline.

[0081] The hydrogen extraction pipeline connects to the purified hydrogen discharge pipeline and the recovered hydrogen discharge pipeline. A branch of the purified hydrogen discharge pipeline is used as the purified hydrogen inlet pipeline.

[0082] Aromatics production unit 1 is a continuous reforming unit;

[0083] Carbon dioxide capture unit 2 is an organic amine absorption unit;

[0084] Both aromatics production unit 1 and carbon-based compound synthesis unit 5 are equipped with their own independent heating furnaces;

[0085] The exhaust gas pipeline is connected to the heating furnace of aromatics production unit 1.

[0086] Each of the exhaust gas discharge pipeline, hydrogen-containing gas discharge pipeline, carbon dioxide discharge pipeline, hydrocarbon-containing gas discharge pipeline, and methane discharge pipeline is equipped with its own independent control valve. The independent control valve is used to control the gas volume of the corresponding pipeline according to the changes in the feed.

[0087] Each raw material feed pipeline, the dry gas feed pipeline containing C1-C4 throughout the plant, and the natural gas feed pipeline is equipped with its own independent flow valve. The independent flow valve is used to control the amount of material fed into the pipeline.

[0088] This embodiment provides a method for producing aromatics with low carbon emissions, the method comprising the following steps:

[0089] 310 t / h naphtha a is fed into aromatics production unit 1 for reforming or light hydrocarbon aromatization to obtain 261 t / h reaction product oil b, 33.9 t / h hydrogen-containing gas e and waste gas c;

[0090] Waste gas c is sent to carbon dioxide capture unit 2 for separation to obtain 391 kmol / h carbon dioxide d;

[0091] 23.9 t / h of hydrogen-containing gas e is fed into hydrogen purification unit 3, and the remaining hydrogen-containing gas e is used as fuel for aromatics production unit 1. After purification, 4415 kmol / h of purified hydrogen f and 15.1 t / h of hydrocarbon gas g are obtained.

[0092] Hydrocarbon gas g, 270 kmol / h of dry gas containing C1-C4 from the whole plant h, and 252 kmol / h of natural gas i are fed into the C1 recovery unit 4 to recover 391 kmol / h of methane 1, ethane-rich gas j and 623 kmol / h of recovered hydrogen k.

[0093] Carbon dioxide d and methane l are fed into carbon-based compound synthesis unit 5, and partially purified hydrogen n is used for combustion heating to obtain a mixed gas m with a flow rate of 566 kmol / h.

[0094] Waste gas c includes flue gas from the heating furnace of the aromatics production unit and emissions from catalyst regeneration;

[0095] The separation method used was the organic amine absorption method;

[0096] The purification method used was pressure swing adsorption;

[0097] The recovery method used is a combination of cryogenic separation and distillation;

[0098] Hydrocarbon gases include methane, ethane, propane, and butane;

[0099] Natural gas i is used to supplement the methane l recovered from hydrocarbon gas g;

[0100] The gas mixture m includes carbon monoxide and hydrogen;

[0101] The percentage of partially purified hydrogen (n) to the total purified hydrogen (f) is 35-55%.

[0102] In this embodiment, the number of moles of carbon dioxide d is greater than or equal to the number of moles of methane 1. By increasing the amount of natural gas i added, the number of moles of methane 1 obtained by the carbon-1 recovery unit 4 is equal to the number of moles of carbon dioxide d.

[0103] In this embodiment, after adopting the above-described apparatus and method, the carbon dioxide emissions from the waste gas of the 2.6 million tons / year reforming unit's reaction heating furnace are zero. Compared with existing processes, carbon dioxide emissions are reduced by 372,000 tons annually. With a carbon dioxide trading price of 40 yuan / ton and a hydrogen price of 16,390 yuan / ton, the production method of this embodiment can increase annual profits by 14.68 million yuan.

[0104] The various embodiments of the present invention have been described above. These descriptions are exemplary and not exhaustive, nor are they limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments.

Claims

1. A low-carbon emission aromatics production apparatus, characterized in that, include: The aromatics production unit is equipped with a raw material feed pipeline, a reaction product oil extraction pipeline, a waste gas discharge pipeline, and a hydrogen-containing gas discharge pipeline. A carbon dioxide capture unit is connected to the exhaust gas discharge pipeline and is equipped with a carbon dioxide discharge pipeline. A hydrogen purification unit is connected to the hydrogen-containing gas discharge pipeline and is equipped with a purified hydrogen discharge pipeline and a hydrocarbon-containing gas discharge pipeline, respectively. The C1 recovery unit is connected to the hydrocarbon gas discharge pipeline and is equipped with an optional dry gas feed pipeline containing C1-C4, an optional natural gas feed pipeline, a methane discharge pipeline, an ethane-rich gas extraction pipeline, and a recovered hydrogen discharge pipeline. The carbon-based compound synthesis unit is connected to the carbon dioxide discharge pipeline and the methane discharge pipeline, respectively, and is equipped with a mixed gas extraction pipeline and a purified hydrogen inlet pipeline. A hydrogen extraction pipeline connects to the purified hydrogen discharge pipeline and the recovered hydrogen discharge pipeline, with a branch of the purified hydrogen discharge pipeline serving as the purified hydrogen inlet unit pipeline.

2. The apparatus according to claim 1, characterized in that, The aromatics production unit is a continuous reforming unit, a semi-regenerative reforming unit, or a light hydrocarbon aromatization unit, preferably a continuous reforming unit. The carbon dioxide capture unit is an organic amine absorption unit or an air separation-flue gas recirculation unit, preferably an organic amine absorption unit; Both the aromatic hydrocarbon production unit and the carbon-based compound synthesis unit are equipped with their own independent heating furnaces. The exhaust gas discharge pipeline is connected to the heating furnace of the aromatics production unit.

3. The apparatus according to claim 1, characterized in that, Each of the exhaust gas discharge pipeline, hydrogen-containing gas discharge pipeline, carbon dioxide discharge pipeline, hydrocarbon-containing gas discharge pipeline, and methane discharge pipeline is equipped with its own independent control valve. The independent control valve is used to control the gas volume of the corresponding pipeline according to the changes in the feed. Each of the raw material feed pipelines, the dry gas feed pipelines containing C1-C4, and the natural gas feed pipelines is equipped with its own independent flow valve, which is used to control the amount of material fed into the pipeline.

4. A method for producing aromatics with low carbon emissions using the apparatus described in any one of claims 1-3, characterized in that, The method includes the following steps: The raw materials are fed into the aromatics production unit for reforming or light hydrocarbon aromatization to obtain reaction products, hydrogen-containing gases and waste gases. The waste gas is sent to a carbon dioxide capture unit for separation to obtain carbon dioxide. The hydrogen-containing gas is fed into a hydrogen purification unit to purify it into purified hydrogen and hydrocarbon gas. The hydrocarbon gas, optional dry gas containing C1-C4 from the entire plant, and optional natural gas are fed into the C1 recovery unit to recover methane, ethane-rich gas, and recovered hydrogen. The carbon dioxide and methane are fed into a carbon-based compound synthesis unit, and a mixed gas is obtained by burning partially purified hydrogen for heating.

5. The method according to claim 4, characterized in that, The raw material is at least one of naphtha, liquefied petroleum gas, and light hydrocarbons; The exhaust gas includes the flue gas from the heating furnace of the aromatics production unit and the exhaust gas from catalyst regeneration; The separation method used is either organic amine absorption or air separation-flue gas recirculation. The purification method used is pressure swing adsorption or membrane separation. The recovery method is a combination of cryogenic separation and distillation, membrane separation or pressure swing adsorption. The hydrocarbon gas includes at least one of methane, ethane, propane, and butane.

6. The method according to claim 5, characterized in that, When the raw material is naphtha, the raw material is continuously reformed or semi-regeneratively reformed to obtain reaction product oil, hydrogen-containing gas and waste gas; When the raw material is at least one of liquefied petroleum gas and light hydrocarbons, the raw material is subjected to light hydrocarbon aromatization to obtain reaction product oil, hydrogen-containing gas and waste gas; The separation method used is the organic amine absorption method.

7. The method according to claim 4, characterized in that, The optional dry gas containing C1-C4 from the entire plant, and the optional natural gas, are used to supplement the methane obtained from the recovery of the hydrocarbon gases; The mixed gas includes carbon monoxide and hydrogen; The purified hydrogen accounts for 35-55% of the total purified hydrogen.

8. The method according to claim 4, characterized in that, The number of moles of carbon dioxide is greater than or equal to the number of moles of methane.

9. The method according to claim 8, characterized in that, When the number of moles of carbon dioxide is greater than the number of moles of methane, the moles of methane obtained by the C1 recovery unit are equal to the number of moles of carbon dioxide by increasing the amount of optional dry gas containing C1-C4 and optional natural gas added throughout the plant.

10. The method according to claim 9, characterized in that, When the number of moles of carbon dioxide is greater than the number of moles of methane, the C1 recovery unit can be made to obtain a number of moles of methane equal to the number of moles of carbon dioxide by increasing the optional amount of natural gas added.

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