Light hydrocarbon separation system and method and light hydrocarbon preparation system

Abstract

The embodiment of the invention provides a light hydrocarbon separation system and method and a light hydrocarbon preparation system. The system comprises a demethanation unit, a decarburized light hydrocarbon unit, a low-temperature heat exchange unit, a first expansion unit and a second expansion unit, the decarburized light hydrocarbon unit is used for receiving the residual material conveyed by the demethanation unit and separating out the decarburized light hydrocarbon; the first expansion unit is used for receiving the methane hydrogen, performing expansion treatment on the methane hydrogen, and conveying the expanded methane hydrogen to the low-temperature heat exchange unit to serve as a refrigerant of the low-temperature heat exchange unit to provide cooling capacity; and the second expansion unit is used for receiving the gas-phase carbon disulfide hydrocarbon, carrying out expansion treatment on the gas-phase carbon disulfide hydrocarbon and conveying the expanded carbon disulfide hydrocarbon to the low-temperature heat exchange unit so as to serve as a refrigerant of the low-temperature heat exchange unit to provide cooling capacity. According to the system, the carbon disulfide light hydrocarbon in the separation process is conveyed to the low-temperature heat exchange unit to serve as a refrigerant to provide cooling capacity, and energy consumption of light hydrocarbon separation is remarkably reduced.

Description

Technical Field

[0001] This application relates to the field of chemical separation technology, and in particular to a light hydrocarbon separation system, method and light hydrocarbon preparation system. Background Technology

[0002] In the existing petrochemical industry, various chemical products and their derivatives prepared from crude oil have become necessities of modern life. With the diversification of light hydrocarbon feedstocks and light hydrocarbon preparation methods, the feed components in light hydrocarbon separation systems also change. In some specific scenarios, these materials mainly consist of one or more of the following: hydrogen, methane, C2 light hydrocarbons, propane, C4-C6 heavy components, and aromatics.

[0003] Traditional methods for separating light hydrocarbons typically involve a cold separation process centered around a demethanizer. The demethanizer is connected to a cooling system, which uses C2 refrigeration equipment with C2 light hydrocarbons at -100°C as the refrigerant. The separation of each light hydrocarbon is achieved by controlling the temperature and pressure.

[0004] However, C2 refrigeration systems that use C2 light hydrocarbons as refrigerants have high power requirements and need to be set up separately, resulting in high costs and high energy consumption for light hydrocarbon separation systems. Summary of the Invention

[0005] This application provides a light hydrocarbon separation system, method, and light hydrocarbon preparation system to solve the technical problems of high cost and high energy consumption in existing light hydrocarbon separation systems.

[0006] The first aspect of this application provides a light hydrocarbon separation system, the system comprising: a demethanizing unit, a decarbonizing light hydrocarbon unit, a low-temperature heat exchange unit, a first expansion unit, and a second expansion unit;

[0007] The low-temperature heat exchange unit, the demethanizing unit, and the decarbonized light hydrocarbon unit are connected in sequence by pipelines. The first expansion unit is connected to the low-temperature heat exchange unit and the demethanizing unit by pipelines, and the second expansion unit is connected to the low-temperature heat exchange unit and the decarbonized light hydrocarbon unit by pipelines.

[0008] The low-temperature heat exchange unit is used to cool the material;

[0009] The demethanizing unit is used to receive the material conveyed by the low-temperature heat exchange unit and separate the methane hydrogen.

[0010] The decarbonized light hydrocarbon unit is used to receive the remaining material conveyed by the demethanizing unit and separate out the C2 light hydrocarbons, wherein the C2 light hydrocarbons include gaseous C2 light hydrocarbons and liquid C2 light hydrocarbons.

[0011] The first expansion unit is used to receive the hydrogen methane and expand the hydrogen methane, and then transport the expanded hydrogen methane to the low-temperature heat exchange unit to provide cooling as a refrigerant for the low-temperature heat exchange unit.

[0012] The second expansion unit is used to receive the gaseous C2 light hydrocarbon and expand the gaseous C2 light hydrocarbon, and then transport the expanded C2 light hydrocarbon to the low-temperature heat exchange unit to provide cooling as a refrigerant for the low-temperature heat exchange unit.

[0013] In the system described above, the decarbonized light hydrocarbon unit is connected to the low-temperature heat exchange unit via pipeline;

[0014] The decarbonized light hydrocarbon unit is used to transport the liquid-phase C2 light hydrocarbon to the low-temperature heat exchange unit through pipelines to provide cooling capacity as a refrigerant for the low-temperature heat exchange unit.

[0015] In the system described above, the demethanizing unit includes a demethanizing tower and a condenser, wherein the condenser is located in the middle of the demethanizing tower;

[0016] The demethanizing tower is connected to the pipeline of the low-temperature heat exchange unit and is used to receive the material conveyed by the low-temperature heat exchange unit and separate the methane hydrogen.

[0017] The condenser is used to condense the gaseous material in the demethanizer.

[0018] In the system described above, the first expansion unit includes a first expander and a first compressor, wherein the first expander and the first compressor are coaxial devices;

[0019] The first expander is connected to the pipelines of the low-temperature heat exchange unit and the demethanizing unit, and the first compressor is connected to the pipeline of the low-temperature heat exchange unit.

[0020] The first expander is used to receive the methane hydrogen supplied by the demethanizing unit and expand the methane hydrogen, and then supply the expanded methane hydrogen to the low-temperature heat exchange unit to provide cooling capacity as a refrigerant for the low-temperature heat exchange unit.

[0021] The first compressor is used to receive C2 light hydrocarbons after the subcooling has been recovered by the low-temperature heat exchange unit, and to pressurize them.

[0022] In the system described above, the second expansion unit includes a second expander and a second compressor, wherein the second expander and the second compressor are coaxial devices;

[0023] The second expander is connected to the low-temperature heat exchange unit and the decarbonized light hydrocarbon unit pipelines respectively, and the second compressor is connected to the low-temperature heat exchange unit and the first compressor pipeline respectively;

[0024] The second expander is used to receive the gaseous C2 light hydrocarbon and expand the gaseous C2 light hydrocarbon, and then transport the expanded C2 light hydrocarbon to the low-temperature heat exchange unit to provide cooling capacity as a refrigerant for the low-temperature heat exchange unit.

[0025] The second compressor is used to receive the C2 light hydrocarbons after the subcooling is recovered by the low-temperature heat exchange unit and the C2 light hydrocarbons delivered by the first compressor, and then pressurize them before extraction.

[0026] The system described above further includes a deweighting unit and a compression unit. The deweighting unit is connected to the compression unit and the decarbonized light hydrocarbon unit pipelines, respectively. The compression unit is connected to the low-temperature heat exchange unit pipeline.

[0027] The deweighting unit is used to separate the heavier components from the material. The heavier components are a small amount of C2 light hydrocarbons and components with a carbon element quantity greater than that of C2 light hydrocarbons, and the heavier components are transported to the decarbonized light hydrocarbon unit.

[0028] The decarbonized light hydrocarbon unit is used to separate the C2 light hydrocarbon from the heavier components;

[0029] The compression unit is used to receive the components other than the heavier components from the deweighting unit, compress the components other than the heavier components, and transport the compressed material to the low-temperature heat exchange unit.

[0030] The system as described above, wherein the system further includes a separation tank;

[0031] The separation tank is connected to the low-temperature heat exchange unit and the demethanizing unit via pipelines;

[0032] The separation tank is used to receive the material cooled by the low-temperature heat exchange unit, and to perform gas-liquid separation on the cooled material. The liquid phase material is transported to the demethanizing unit, and the gas phase material is transported to the low-temperature heat exchange unit to provide cooling capacity as a refrigerant for the low-temperature heat exchange unit.

[0033] A second aspect of this application provides a light hydrocarbon preparation system, which includes a light hydrocarbon reaction system and a light hydrocarbon separation system as described above.

[0034] A third aspect of this application provides a method for separating light hydrocarbons, the method being applied to the light hydrocarbon separation system described above, the method comprising:

[0035] The material is cooled using a low-temperature heat exchange unit;

[0036] A demethanizing unit is used to receive the material conveyed by the low-temperature heat exchange unit and separate the methane hydrogen.

[0037] A decarbonyl hydrocarbon removal unit receives the remaining material conveyed by the demethanizing unit and separates out the C2 hydrocarbons, wherein the C2 hydrocarbons include gaseous C2 hydrocarbons and liquid C2 hydrocarbons;

[0038] The first expansion unit receives the hydrogen methane and expands it, and then transports the expanded hydrogen methane to the low-temperature heat exchange unit to provide cooling as a refrigerant for the low-temperature heat exchange unit.

[0039] The second expansion unit receives the gaseous C2 light hydrocarbon and expands it. The expanded C2 light hydrocarbon is then transported to the low-temperature heat exchange unit to provide cooling as a refrigerant for the low-temperature heat exchange unit.

[0040] In an optional implementation, the method further includes:

[0041] The liquid-phase C2 light hydrocarbons are transported through pipelines to the low-temperature heat exchange unit using the decarbonized light hydrocarbon unit to provide cooling capacity as a refrigerant for the low-temperature heat exchange unit.

[0042] This application provides a light hydrocarbon separation system, method, and light hydrocarbon preparation system. By connecting a first expansion unit to a demethanizing unit and a second expansion unit to a decarbonyl light hydrocarbon removal unit, the expanded methane hydrogen and C2 light hydrocarbons are both supplied to a low-temperature heat exchange unit as refrigerants, reducing the energy consumption of the light hydrocarbon separation system by the low-temperature heat exchange unit from the C2 refrigeration system. The light hydrocarbon preparation system connects the light hydrocarbon separation system to the light hydrocarbon reaction system, allowing for direct separation of reactants after the light hydrocarbon reaction is complete, improving the efficiency of light hydrocarbon preparation and effectively reducing energy consumption during the light hydrocarbon separation process. The light hydrocarbon separation method uses the first and second expansion units to expand the methane hydrogen and C2 light hydrocarbons separated from the demethanizing and decarbonyl light hydrocarbon removal units, respectively. The expanded methane hydrogen and C2 light hydrocarbons are then supplied to a low-temperature heat exchange system as refrigerants, reducing the energy consumption of the light hydrocarbon separation system by the low-temperature heat exchange unit from the C2 refrigeration system. Attached Figure Description

[0043] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application.

[0044] Figure 1A schematic diagram (1) of a light hydrocarbon separation system provided in an embodiment of this application;

[0045] Figure 2 A schematic diagram (2) of a light hydrocarbon separation system provided in an embodiment of this application;

[0046] Figure 3 A schematic diagram (3) of a light hydrocarbon separation system provided in an embodiment of this application;

[0047] Figure 4 A schematic diagram (4) of a light hydrocarbon separation system provided in an embodiment of this application;

[0048] Figure 5 A schematic diagram (5) of a light hydrocarbon separation system provided in an embodiment of this application;

[0049] Figure 6 A schematic diagram (6) of a light hydrocarbon separation system provided in an embodiment of this application;

[0050] Figure 7 This is a schematic diagram of a light hydrocarbon preparation system provided in an embodiment of this application;

[0051] Figure 8 This is a flowchart of a light hydrocarbon separation method provided in an embodiment of this application.

[0052] Figure Labels

[0053] 101 - Demethanization unit; 102 - Decarbonization unit; 103 - Low-temperature heat exchange unit; 104 - First expansion unit; 105 - Second expansion unit;

[0054] 201a - Demethanizer; 201b - Condenser; 201c - Reflux tank;

[0055] 304a - First expander; 304b - First compressor;

[0056] 405a - Second expander; 405b - Second compressor; 405c - Expander outlet tank; 406 - Pressure reducing valve;

[0057] 502a - Decarbonization tower for light hydrocarbons; 502b - Separation tank; 502c - Cooler; 506 - Heavy hydrocarbon removal unit; 507 - Compression unit;

[0058] 602b - Container; 608a - First pressure reducing valve; 608b - Second pressure reducing valve; 609a - First separation tank; 609b - Second separation tank; 609c - Third separation tank;

[0059] 701 - Light hydrocarbon reaction system; 702 - Light hydrocarbon separation system.

[0060] The accompanying drawings illustrate specific embodiments of this application, which will be described in more detail below. These drawings and descriptions are not intended to limit the scope of the concept in any way, but rather to illustrate the concept of this application to those skilled in the art through reference to particular embodiments. Detailed Implementation

[0061] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0062] Figure 1 This is a schematic diagram of a light hydrocarbon separation system provided in an embodiment of this application, as shown below. Figure 1 As shown, the first aspect of this application provides a light hydrocarbon separation system, which includes a demethanizing unit 101, a decarbonized light hydrocarbon unit 102, a low-temperature heat exchange unit 103, a first expansion unit 104, and a second expansion unit 105.

[0063] The low-temperature heat exchange unit 103, the demethanizing unit 101 and the decarbonized light hydrocarbon unit 102 are connected in sequence by pipelines. The first expansion unit 104 is connected to the low-temperature heat exchange unit 103 and the demethanizing unit 101 by pipelines respectively. The second expansion unit 105 is connected to the low-temperature heat exchange unit 103 and the decarbonized light hydrocarbon unit 102 by pipelines respectively.

[0064] The low-temperature heat exchange unit 103 is used to cool the material;

[0065] The demethanizing unit 101 is used to receive the material conveyed by the low-temperature heat exchange unit 103 and separate the methane hydrogen.

[0066] The decarbonyl hydrocarbon removal unit 102 is used to receive the remaining material conveyed by the demethanizing unit 101 and separate out the C2 hydrocarbons, wherein the C2 hydrocarbons include gaseous C2 hydrocarbons and liquid C2 hydrocarbons.

[0067] The first expansion unit 104 is used to receive methane hydrogen and expand the methane hydrogen, and then transport the expanded methane hydrogen to the low-temperature heat exchange unit 103 to provide cooling capacity as a refrigerant for the low-temperature heat exchange unit 103.

[0068] The second expansion unit 105 is used to receive gaseous C2 light hydrocarbons and expand them, and then transport the expanded C2 light hydrocarbons to the low-temperature heat exchange unit 103 to provide cooling as a refrigerant for the low-temperature heat exchange unit 103.

[0069] Among them, methane hydrogen is a mixture of at least two of methane, CO, hydrogen, nitrogen, and argon.

[0070] It should be noted that the low-temperature heat exchange unit 103 is equipped with multiple pipelines at different temperatures, which are used to connect to different units and receive different substances.

[0071] The low-temperature heat exchange unit 103 is also used to cool the methane hydrogen separated in the demethanizing unit 101.

[0072] The demethanizing unit 101 includes equipment for receiving materials and separating hydrogen methane, such as a demethanizing tower, and containers for receiving and separating hydrogen methane cooled by the cryogenic heat exchange unit 103, such as a demethanizing tower reflux tank. This embodiment does not limit these.

[0073] The decarbonized light hydrocarbon unit 102 includes equipment for receiving residual materials and separating light hydrocarbons, such as a decarbonized light hydrocarbon tower, equipment for cooling the separated light hydrocarbons, such as a condenser, which can be supplied with cooling capacity by a propylene refrigeration system, and containers for receiving and separating the light hydrocarbons cooled by the cooling equipment, such as a decarbonized light hydrocarbon tower reflux tank. This embodiment does not limit these.

[0074] In a specific implementation, after being cooled by the low-temperature heat exchange unit 103, the material enters the demethanizing unit 101 for the separation of methane hydrogen. The separated methane hydrogen is transported to the first expansion unit 104, where it is expanded. The expanded methane hydrogen is then transported to the low-temperature heat exchange unit 103 to provide cooling as a refrigerant. The methane hydrogen is then extracted. The remaining material in the demethanizing unit 101 is transported to the decarbonyl hydrocarbon removal unit 102. Upon receiving the remaining material, the decarbonyl hydrocarbon removal unit 102 separates the C2 hydrocarbons. The remaining material is transported to downstream devices. The separated gaseous C2 hydrocarbons are transported to the second expansion unit 105, where they are expanded and then transported to the low-temperature heat exchange unit 103 to provide cooling as a refrigerant.

[0075] Both the expanded methane hydrogen and C2 light hydrocarbons can be gas-liquid mixtures.

[0076] Optionally, a pressure reducing valve can be installed on the connecting pipeline between the second expansion unit 105 and the low-temperature heat exchange unit 103 to reduce the pressure of the C2 light hydrocarbons delivered from the second expansion unit 105, so that the reduced C2 light hydrocarbons can be cooled to a lower temperature, providing more cooling capacity to the low-temperature heat exchange unit 103.

[0077] Optionally, the liquid-phase C2 hydrocarbons separated from the decarbonized light hydrocarbon unit 102 can also be transported to the low-temperature heat exchange unit 103 as a supplementary refrigerant to provide cooling capacity to the low-temperature heat exchange unit 103.

[0078] It should be noted that the low-temperature heat exchange unit 103, the demethanizing unit 101, and the decarbonized light hydrocarbon unit 102 are connected by pipelines in sequence. The placement and connection of each unit can be determined according to the actual situation, as long as the connection can achieve the solution. This embodiment does not limit this.

[0079] The light hydrocarbon separation system provided in this embodiment connects the first expansion unit to the demethanizing unit and the second expansion unit to the decarbonyl light hydrocarbon unit. The expanded methane hydrogen and C2 light hydrocarbons are then transported to the low-temperature heat exchange unit as a refrigerant to provide cooling capacity. This reduces the amount of cooling capacity that the low-temperature heat exchange unit obtains from the C2 refrigeration system, thereby reducing the energy consumption of the light hydrocarbon separation system.

[0080] In some implementations, the decarbonized light hydrocarbon unit is connected to the low-temperature heat exchange unit pipeline;

[0081] The decarbonized light hydrocarbon unit is used to transport liquid-phase C2 light hydrocarbons through pipelines to the cryogenic heat exchange unit to provide cooling capacity as a refrigerant for the cryogenic heat exchange unit.

[0082] It is understandable that the C2 hydrocarbons separated from the decarbonyl hydrocarbon unit include gaseous C2 hydrocarbons and liquid C2 hydrocarbons, which can be extracted together or separately.

[0083] Specifically, the liquid C2 hydrocarbons separated from the decarbonized light hydrocarbon unit are transported through pipelines to the low-temperature heat exchange unit to provide cooling capacity as a refrigerant for the low-temperature heat exchange unit.

[0084] A pressure reducing valve can be installed on the connecting pipeline between the decarbonized light hydrocarbon unit and the low-temperature heat exchange unit to reduce the pressure of the liquid-phase light hydrocarbons transported from the decarbonized light hydrocarbon unit, so that the reduced liquid-phase light hydrocarbons can be cooled to a lower temperature, providing more cooling capacity to the low-temperature heat exchange unit.

[0085] Optionally, the low-temperature heat exchange unit can be connected to the bottom pipeline of the decarbonized light hydrocarbon unit to facilitate the delivery of liquid-phase C2 light hydrocarbons to the low-temperature heat exchange unit, or it can be connected to other pipelines of the decarbonized light hydrocarbon unit, as long as the delivery of liquid-phase C2 light hydrocarbons to the low-temperature heat exchange unit is guaranteed. This embodiment does not limit this.

[0086] The light hydrocarbon separation system provided in this embodiment connects the decarbonized light hydrocarbon unit to the low-temperature heat exchange unit pipeline, which allows the separated liquid-phase C2 light hydrocarbons to also enter the low-temperature heat exchange unit as supplementary refrigerant to provide cooling capacity, ensuring sufficient refrigerant in the low-temperature heat exchange unit and further reducing the energy consumption of the light hydrocarbon separation system.

[0087] Furthermore, a schematic diagram (2) of a light hydrocarbon separation system provided in one embodiment of this application is shown below. Figure 2 As shown, the demethanizing unit 101 includes a demethanizing tower 201a and a condenser 201b, with the condenser 201b located in the middle of the demethanizing tower 201a.

[0088] The demethanizer 201a is connected to the cryogenic heat exchange unit 103 via pipeline and is used to receive the material conveyed by the cryogenic heat exchange unit 103 and to separate the methane hydrogen.

[0089] Condenser 201b is used to condense the gaseous material in the demethanizer.

[0090] It should be noted that the demethanizer uses the temperature difference between the top and bottom of the column to separate methane hydrogen. The demethanizer pressure is 2.0~4.0 MPaA, the top temperature is -50~-100℃, and the bottom temperature is 0~40℃.

[0091] The condenser 201b can be cooled by a propylene refrigeration system, and the temperature can be set to -35°C, or other temperatures that can be adjusted according to actual conditions. This embodiment does not limit this.

[0092] The side of the demethanizer 201a is connected to the pipeline of the low-temperature heat exchange unit 103 to receive the material conveyed by the low-temperature heat exchange unit 103. The top of the demethanizer 201a is also connected to the pipeline of the low-temperature heat exchange unit 103 to transport the separated methane hydrogen to the low-temperature heat exchange unit 103 for cooling. Alternatively, other connection points may be used, as long as the implementation of this solution is possible. This embodiment does not limit the specific connection points.

[0093] Specifically, after being cooled by the low-temperature heat exchange unit 103, the material enters the demethanizer 201a for the separation of methane and hydrogen. Because the components in the material have different volatility under certain temperature and pressure, the more volatile components become gaseous, while the less volatile components remain in the liquid phase. A condenser is installed to allow the liquid phase to return, and a reboiler is installed to allow the gaseous phase to rise. Gas and liquid phases come into contact within the tower, ultimately achieving separation. A condenser 201b is installed in the middle of the demethanizer 201a to achieve intermediate condensation and reflux, thus achieving pre-separation. The gaseous material that has not yet been separated enters the low-temperature heat exchange unit 103 from the top of the tower for cooling, thereby reducing the mass of gaseous material entering the low-temperature heat exchange unit 103 for cooling. The remaining liquid material then enters the decarbonization unit 102 for further separation.

[0094] Optionally, the demethanizing unit 101 includes a container, such as a reflux tank, for receiving and separating the methane hydrogen cooled by the cryogenic heat exchange unit 103. This embodiment does not limit this.

[0095] For example, the reflux tank 201c receives the methane hydrogen delivered by the cryogenic heat exchange unit 103. The liquid methane hydrogen is refluxed back to the demethanizer 201a, and the gaseous methane hydrogen is transported to the first expansion unit 104 via pipeline. The first expansion unit 104 expands the methane hydrogen and then delivers the expanded methane hydrogen to the cryogenic heat exchange unit 103 to provide cooling as a refrigerant.

[0096] The light hydrocarbon separation system provided in this embodiment has a condenser 201b installed in the middle of the demethanizer 201a to cool the gas components with higher condensation points in the demethanizer 201a, thereby reducing the mass of the gas components cooled by the low-temperature heat exchange unit 103 and thus reducing the temperature of the low-temperature heat exchange unit 103.

[0097] In some embodiments, a schematic diagram (3) of a light hydrocarbon separation system provided in this application is shown, such as... Figure 3 As shown, the first expansion unit 104 includes a first expander 304a and a first compressor 304b, which are coaxial devices.

[0098] The first expander 304a is connected to the pipelines of the low-temperature heat exchange unit 103 and the demethanizing unit 101 respectively, and the first compressor 304b is connected to the pipeline of the low-temperature heat exchange unit 103.

[0099] The first expander 304a is used to receive the methane hydrogen supplied by the demethanizing unit 101 and expand the methane hydrogen, and then supply the expanded methane hydrogen to the low-temperature heat exchange unit 103 to provide cooling capacity as a refrigerant for the low-temperature heat exchange unit 103.

[0100] The first compressor 304b is used to receive C2 light hydrocarbons after the subcooling has been recovered by the cryogenic heat exchange unit 103, and to pressurize them.

[0101] The inlet pressure of the first expander 304a is 2.0~4.0 MPaA, the outlet pressure of the first expander 304a is 0.1~0.8 MPaA, the inlet pressure of the first compressor 304b is 0.1~0.3 MPaA, and the outlet pressure of the first compressor 304b is 0.3~0.5 MPaA.

[0102] Optionally, the first expander 304a can also be coaxial with the motor, and the motor can recover the output energy of the first expander 304a as its own driving energy for power generation.

[0103] Specifically, after being cooled by the low-temperature heat exchange unit 103, the material enters the demethanizing unit 101. The methane hydrogen separated by the demethanizing unit 101 is cooled by the low-temperature heat exchange unit 103, and the liquid phase methane hydrogen is returned to the demethanizing unit 101. The gaseous phase methane hydrogen enters the first expander 304a for expansion. The expanded methane hydrogen is then transported to the low-temperature heat exchange unit 103 to provide cooling as a refrigerant. The methane hydrogen after recovering the subcooled amount can be directly extracted. The remaining material in the demethanizing unit 101 is transported to the decarbonyl hydrocarbon removal unit 102 for the separation of C2 hydrocarbons. The separated C2 hydrocarbons are then expanded by the second expansion unit 105. The expanded C2 hydrocarbons are then transported via pipeline to the low-temperature heat exchange unit 103 to provide cooling as a refrigerant. The subcooled C2 hydrocarbons are then transported to the first compressor 304b for pressurization.

[0104] Optionally, the first compressor 304b can be connected to an upstream system pipeline to circulate the pressurized C2 light hydrocarbons as a refrigerant to the demethanizing unit 101 via the upstream system; or it can be connected to an ethylene distillation system pipeline; or the pipeline can be connected to other systems. This embodiment does not limit this. The ethylene distillation system can be an ethylene separation tower, a membrane separation device, etc. The first compressor 304b can also pressurize the methane hydrogen after the subcooled amount is recovered by the low-temperature heat exchange unit 103. This embodiment does not limit this.

[0105] It should be noted that the connection methods between the various units or devices provided in this embodiment are all exemplary, and the specific connection positions are not specifically limited, as long as the implementation of this solution is guaranteed.

[0106] The light hydrocarbon separation system provided in this embodiment is configured with a first expander 304a connected to a demethanizing unit 101 and a low-temperature heat exchange unit 103 via pipeline. This expander can then supply the expanded methane hydrogen to the low-temperature heat exchange unit 103 as a refrigerant, thereby reducing the energy consumption of the low-temperature heat exchange unit 103. The first expander 304a and the first compressor 304b are coaxial devices. The first compressor 304b can recover the output energy of the first expander 304a as driving energy. Connecting the first compressor 304b to the low-temperature heat exchange unit 103 allows for the compression of the recovered subcooled C2 light hydrocarbons, facilitating their subsequent applications.

[0107] In some embodiments, a schematic diagram (4) of a light hydrocarbon separation system provided in this application is shown, such as... Figure 4 As shown, the second expansion unit 105 includes a second expander 405a and a second compressor 405b, and the second expander 405a and the second compressor 405b are coaxial devices;

[0108] The second expander 405a is connected to the low-temperature heat exchange unit 103 and the decarbonized light hydrocarbon unit 102 pipelines respectively, and the second compressor 405b is connected to the low-temperature heat exchange unit 103 and the first compressor 304b pipelines respectively.

[0109] The second expander 405a is used to receive gaseous C2 light hydrocarbons and expand them, and then transport the expanded C2 light hydrocarbons to the low-temperature heat exchange unit 103 to provide cooling capacity as a refrigerant for the low-temperature heat exchange unit 103.

[0110] The second compressor 405b is used to receive the C2 light hydrocarbons after the subcooling is recovered by the low-temperature heat exchange unit 103 and the C2 light hydrocarbons conveyed by the first compressor 304b, and then pressurize them before extraction.

[0111] The inlet pressure of the second expander 405a is 1.0~2.5 MPaA, the outlet pressure of the second expander 405a is 0.1~0.8 MPaA, the inlet pressure of the second compressor 405b is 0.3~0.5 MPaA, and the outlet pressure of the second compressor 405b is 0.6~1.0 MPaA.

[0112] Optionally, the second expander 405a can also be coaxial with the motor, and the motor can recover the output energy of the second expander 405a as its own driving energy for power generation.

[0113] The second expansion unit 105 may also include a container for separating the C2 light hydrocarbons expanded by the second expander 405a, such as the expander outlet tank 405c. This embodiment does not limit this. The second expander 405a is connected to the low-temperature heat exchange unit 103 via the expander outlet tank 405c.

[0114] Specifically, after being cooled by the low-temperature heat exchange unit 103, the material enters the demethanizing unit 101. The methane hydrogen separated by the demethanizing unit 101 is cooled by the low-temperature heat exchange unit 103, and the liquid phase methane hydrogen is returned to the demethanizing unit 101. The gaseous phase methane hydrogen enters the first expander 304a for expansion. The expanded methane hydrogen is then transported to the low-temperature heat exchange unit 103 to provide cooling as a refrigerant. The methane hydrogen after recovering the supercooled amount can be directly extracted. The remaining material in the demethanizing unit 101 is transported to the decarbonyl hydrocarbon removal unit 102 for the separation of C2 hydrocarbons, and the separated C2 hydrocarbons are transported to the second expander 405a for further expansion. The expanded C2 light hydrocarbons are then transported to the expander outlet tank 405c. After gas-liquid separation, the liquid phase C2 light hydrocarbons are transported via pipeline to the low-temperature heat exchange unit 103 to provide cooling as a refrigerant. The subcooled C2 light hydrocarbons are recovered and transported to the first compressor 304b for pressurization, and then transported to the second compressor 405b. The gaseous C2 light hydrocarbons in the expander outlet tank 405c are also transported via pipeline to the low-temperature heat exchange unit 103 to provide cooling as a refrigerant. The subcooled C2 light hydrocarbons are recovered and transported to the second compressor 405b to be combined with the C2 light hydrocarbons received from the first compressor 304b and pressurized before being extracted.

[0115] A pressure reducing valve 406 can be installed on the connecting pipeline between the expander outlet tank 405c and the low-temperature heat exchange unit 103 to reduce the pressure of the liquid C2 light hydrocarbons transported from the expander outlet tank 405c, so that the reduced liquid C2 light hydrocarbons can be cooled to a lower temperature, providing more cooling capacity to the low-temperature heat exchange unit 103.

[0116] Optionally, the liquid-phase C2 light hydrocarbons separated from the expander outlet tank 405c can be fed to the second compressor 405b for pressurization after the cold energy is recovered by the low-temperature heat exchange unit 103; or the gaseous-phase C2 light hydrocarbons separated from the expander outlet tank 405c can be fed to the first compressor 304b for pressurization after the cold energy is recovered by the low-temperature heat exchange unit 103.

[0117] Optionally, the second compressor 405b can also be connected to an upstream system pipeline to circulate the pressurized C2 light hydrocarbons as a refrigerant to the demethanizing unit 101 via the upstream system; or it can be connected to an ethylene distillation system pipeline; or the pipeline can be connected to other systems. This embodiment does not limit this. The ethylene distillation system can be an ethylene separation tower, a membrane separation device, etc., and this embodiment does not limit this.

[0118] It should be noted that the connection methods between the various units or devices provided in this embodiment are all exemplary, and the specific connection positions are not specifically limited, as long as the implementation of this solution is guaranteed.

[0119] The light hydrocarbon separation system provided in this embodiment is equipped with a second expander 405a connected to the decarbonized light hydrocarbon unit 102 and the low-temperature heat exchange unit 103 via pipeline. It can expand the C2 light hydrocarbons and then deliver them to the low-temperature heat exchange unit 103 as a refrigerant to provide cooling, thereby reducing the energy consumption of the low-temperature heat exchange unit 103. The second expander 405a and the second compressor 405b are coaxial devices. The second compressor 405b can recover the output energy of the second expander 405a as driving energy. The second compressor 405b is connected to the low-temperature heat exchange unit 103 and the first compressor 304b via pipeline to compress the recovered subcooled C2 light hydrocarbons for subsequent applications.

[0120] In some embodiments, a schematic diagram (5) of a light hydrocarbon separation system provided in this application is shown, such as... Figure 5 As shown, the system also includes a de-weighting unit 506 and a compression unit 507. The de-weighting unit 506 is connected to the compression unit 507 and the decarbonized light hydrocarbon unit 102 pipelines respectively. The compression unit 507 is connected to the low-temperature heat exchange unit 103 pipeline.

[0121] The deweighting unit 506 is used to separate the heavier components in the material. The heavier components are a small amount of C2 light hydrocarbons and components with a carbon element quantity greater than that of C2 light hydrocarbons. The heavier components are then transported to the decarbonized light hydrocarbons unit 102.

[0122] The decarbonyl light hydrocarbon unit 102 is used to separate C2 light hydrocarbons from heavier components;

[0123] The compression unit 507 is used to receive the components other than the heavier components conveyed by the deweighting unit 506, compress the components other than the heavier components, and convey the compressed material to the low-temperature heat exchange unit 103.

[0124] It is understandable that the materials used for light hydrocarbon separation include a variety of components, such as methane, hydrogen, nitrogen, C2 light hydrocarbons, C3 light hydrocarbons, and hydrocarbon compounds with more than 4 carbon atoms.

[0125] The pressure of the deweight removal unit 506 is 0.2~3.2 MPaA.

[0126] Optionally, the decarbonyl light hydrocarbon unit 102 includes equipment for receiving materials conveyed by the demethanizing unit and the de-heavy hydrocarbon unit and separating C2 light hydrocarbons, such as a decarbonyl light hydrocarbon tower, and containers for receiving and separating C2 light hydrocarbons, such as separation tanks, etc. This embodiment does not limit this.

[0127] Specifically, before entering the low-temperature heat exchange unit 103 for cooling, the material can be fed into the de-heavy component unit 506. The heavier components are directly transported to the decarbonization light hydrocarbon tower 502a via pipeline, while the remaining components enter the compression unit 507 for compression. The compressed material then enters the low-temperature heat exchange unit 103 for cooling. After cooling, the material enters the demethanizing unit 101 for methane hydrogen separation. The methane hydrogen separated from the demethanizing unit 101 is cooled by the low-temperature heat exchange unit 103, and the liquid methane hydrogen is returned to the demethanizing unit 101. The gaseous methane hydrogen is transported to the first expansion unit 104 for expansion. The expanded methane hydrogen is then... Methane hydrogen is supplied to the cryogenic heat exchange unit 103 to provide cooling as a refrigerant; the remaining material in the demethanizing unit 101 is supplied to the decarbonization light hydrocarbon tower 502a, where it is combined with the heavier components supplied by the deweighting unit 506 for the separation of C2 light hydrocarbons. The separated C2 light hydrocarbons are cooled by the cooler 502c and then enter the separation tank 502b. The gaseous C2 light hydrocarbons are supplied to the second expansion unit 105 for expansion treatment, and the expanded C2 light hydrocarbons are supplied to the cryogenic heat exchange unit 103 to provide cooling as a refrigerant. The liquid C2 light hydrocarbons in the separation tank 502b are also supplied to the cryogenic heat exchange unit 103 after being depressurized by the pressure reducing valve 406, and are also supplied to the cryogenic heat exchange unit 103 to provide cooling as a refrigerant.

[0128] It should be noted that the connection methods between the various units or devices provided in this embodiment are all exemplary, and the specific connection positions are not specifically limited, as long as the implementation of this solution is guaranteed.

[0129] The light hydrocarbon separation system provided in this embodiment is equipped with a deweighting unit 506 that separates out heavier components before compression, which can reduce the power consumption of the compression unit 507. The compression unit 507 compresses the material, keeping it within a suitable pressure range, which can improve the purity of the light hydrocarbon separation product.

[0130] In some embodiments, a schematic diagram (6) of a light hydrocarbon separation system provided in this application is shown, such as... Figure 6 As shown, the system also includes a separation tank;

[0131] The separator is connected to the cryogenic heat exchange unit 103 and the demethanizing unit 101 via pipelines;

[0132] The separator is used to receive the material cooled by the low-temperature heat exchange unit 103 and to perform gas-liquid separation on the cooled material. The liquid phase material is transported to the demethanizing unit 101, and the gas phase material is transported to the low-temperature heat exchange unit 103 to provide cooling capacity as a refrigerant for the low-temperature heat exchange unit 103.

[0133] Optionally, the number of separation tanks can be set according to the actual situation, such as 1, 3, 5, etc. This embodiment does not limit this.

[0134] It is understandable that when multiple separation tanks are installed, the temperature in the pipelines connecting each separation tank to the low-temperature heat exchange unit gradually decreases.

[0135] For example, taking a system with three separation tanks, the material first enters the heavy component removal unit 506, where the heavier components are separated and directly transported via pipeline to the decarbonization light hydrocarbon tower 502a. The remaining components enter the compression unit 507 for compression. The compressed material then enters the low-temperature heat exchange unit 103 for cooling. After cooling, the material first enters the first separation tank 609a for gas-liquid separation. The liquid phase material enters the demethanizing unit 101 via pipeline, while the gaseous phase material returns to the low-temperature heat exchange unit 103 via pipeline for further cooling before entering the second separation tank 609b for gas-liquid separation. The liquid phase material enters the demethanizing unit 101 via pipeline, while the gaseous phase material returns to the low-temperature heat exchange unit 103 via pipeline for further cooling before entering the third separation tank 609c for gas-liquid separation. At this point, the gaseous phase material is hydrogen, which is transported to the low-temperature heat exchange unit 103 as a refrigerant to provide cooling. The liquid phase material is methane, which can be depressurized via the second pressure reducing valve 608b before being transported to the low-temperature heat exchange unit 103. It can be used as a refrigerant to provide cooling, or it can be transported to the demethanizing unit 101 to be combined with the above materials for methane separation. The separated methane enters the low-temperature heat exchange unit 103 through a pipeline for cooling, and the liquid phase methane hydrogen is refluxed to the demethanizing unit 101. The gaseous phase methane hydrogen is transported to the first expansion unit 104 for expansion treatment, and then the expanded methane is transported to the low-temperature heat exchange unit 103 to provide cooling as a refrigerant. The remaining material in the demethanizing unit 101 is transported to the decarbonization light hydrocarbon tower 502a. The heavier components transported by the de-heavy unit 506 are combined and separated into C2 light hydrocarbons. The separated C2 light hydrocarbons are cooled by the cooler 502c and then enter the container 602b. The gaseous C2 light hydrocarbons are transported to the second expansion unit 105 for expansion treatment. The expanded C2 light hydrocarbons are then transported to the low-temperature heat exchange unit 103 to provide cooling as a refrigerant. The liquid C2 light hydrocarbons in the container 602b are also transported to the low-temperature heat exchange unit 103 after being depressurized by the first pressure reducing valve 608a, and are also used as a refrigerant to provide cooling.

[0136] The light hydrocarbon separation system provided in this embodiment, by connecting the separation tank with the low-temperature heat exchange unit 103 and the demethanizing unit 101 pipeline, can make reasonable use of the different temperatures of the refrigerant in the low-temperature heat exchange unit 103 to condense different components in the material in stages. The condensed liquid components enter different feed positions of the demethanizing tower according to their different temperatures, thereby maximizing the utilization of the refrigerant's cooling capacity, reducing the energy consumption of the entire light hydrocarbon separation system, and allowing components lighter than methane, such as hydrogen, to be separated in advance for subsequent applications.

[0137] Figure 7 This is a schematic diagram of a light hydrocarbon preparation system provided in an embodiment of this application, as shown below. Figure 7As shown, a second aspect of this application provides a light hydrocarbon preparation system, which includes a light hydrocarbon reaction system 701 and a light hydrocarbon separation system 702 as described in the first aspect.

[0138] Specifically, when preparing light hydrocarbon compounds, a light hydrocarbon separation system 702 can be directly connected after the light hydrocarbon reaction system 701 to receive the reacted material for light hydrocarbon separation.

[0139] The light hydrocarbon preparation system provided in this embodiment connects the light hydrocarbon separation system with the light hydrocarbon reaction system. It can directly separate the reactants after the light hydrocarbon reaction is completed, which improves the efficiency of light hydrocarbon preparation and can effectively reduce the energy consumption in the light hydrocarbon separation process.

[0140] Figure 8 A flowchart of a light hydrocarbon separation method provided in an embodiment of this application is shown below. Figure 8 As shown, the main body for implementing this method is the light hydrocarbon separation system as described in the first aspect, and it specifically includes the following steps:

[0141] S801, uses a low-temperature heat exchange unit to cool the material.

[0142] Specifically, the material enters a low-temperature heat exchange unit for cooling, so that the material can be easily separated in the subsequent process.

[0143] S802. A demethanizing unit is used to receive the material conveyed by the low-temperature heat exchange unit and separate the methane hydrogen.

[0144] Specifically, the material cooled by the low-temperature heat exchange unit is fed into the demethanizing unit, where the methane hydrogen in the material is separated.

[0145] S803. The decarbonyl hydrocarbon unit receives the remaining material conveyed by the demethanizing unit and separates the C2 light hydrocarbons, wherein the C2 light hydrocarbons include gaseous C2 light hydrocarbons and liquid C2 light hydrocarbons.

[0146] Specifically, the remaining material after the methane hydrogen is removed by the demethanizing unit is transported to the decarbonyl hydrocarbon removal unit. After receiving the remaining material, the decarbonyl hydrocarbon removal unit separates the C2 hydrocarbons, which include liquid-phase C2 hydrocarbons and gas-phase C2 hydrocarbons.

[0147] S804. The first expansion unit receives methane hydrogen and expands it, and then transports the expanded methane hydrogen to the low-temperature heat exchange unit to provide cooling as a refrigerant for the low-temperature heat exchange unit.

[0148] Specifically, after the demethanizing unit separates the methane hydrogen, the methane hydrogen enters the low-temperature heat exchange unit for cooling. Then, the first expansion unit expands the methane hydrogen and transports the expanded methane hydrogen to the low-temperature heat exchange unit to provide cooling as a refrigerant.

[0149] Optionally, the recovered supercooled methane hydrogen can be extracted directly or used for other purposes; this embodiment does not limit this.

[0150] S805. The second expansion unit receives gaseous C2 light hydrocarbons and expands them, and then transports the expanded C2 light hydrocarbons to the low-temperature heat exchange unit to provide cooling capacity as a refrigerant for the low-temperature heat exchange unit.

[0151] Specifically, the gaseous C2 light hydrocarbons separated by the decarbonization unit enter the second expansion unit for expansion treatment, and the expanded C2 light hydrocarbons are transported to the low-temperature heat exchange unit to provide cooling capacity as a refrigerant for the low-temperature heat exchange unit.

[0152] Optionally, the recovered subcooled C2 light hydrocarbons can be directly extracted or pressurized and then transported to the demethanizing unit for continued recycling as a refrigerant in the light hydrocarbon separation system. This embodiment does not limit this.

[0153] The light hydrocarbon separation method provided in this embodiment uses a first expansion unit and a second expansion unit to expand the methane hydrogen and C2 light hydrocarbons separated by the demethanizing unit and the decarbonyl light hydrocarbon unit, respectively. The expanded methane hydrogen and C2 light hydrocarbons are then transported to a low-temperature heat exchange system as refrigerants to provide cooling capacity, thereby reducing the amount of cooling capacity that the low-temperature heat exchange unit obtains from the C2 refrigeration system and thus reducing the energy consumption of the light hydrocarbon separation system.

[0154] In an optional implementation, the method further includes:

[0155] A decarbonized light hydrocarbon unit is used to transport liquid-phase C2 light hydrocarbons through pipelines to a low-temperature heat exchange unit to provide cooling capacity as a refrigerant for the low-temperature heat exchange unit.

[0156] Specifically, the C2 light hydrocarbons separated by the decarbonization unit also include liquid C2 light hydrocarbons, which are transported to the low-temperature heat exchange unit through pipelines to provide cooling as a refrigerant.

[0157] The light hydrocarbon separation method provided in this embodiment also transports the separated liquid C2 light hydrocarbons to the low-temperature heat exchange unit as supplementary refrigerant to provide cooling capacity, ensuring sufficient refrigerant in the low-temperature heat exchange unit and further reducing the energy consumption of the light hydrocarbon separation system.

[0158] The various embodiments in this specification are described in a related manner. Similar or identical parts between embodiments can be referred to interchangeably. Each embodiment focuses on its differences from other embodiments. The above are merely preferred embodiments of the present invention and are not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention are included within the scope of protection of the present invention.

Claims

1. A light hydrocarbon separation system, characterized in that, The system includes: a demethanizing unit, a decarbonizing unit for light hydrocarbons, a cryogenic heat exchange unit, a first expansion unit, and a second expansion unit; The low-temperature heat exchange unit, the demethanizing unit, and the decarbonized light hydrocarbon unit are connected in sequence by pipelines. The first expansion unit is connected to the low-temperature heat exchange unit and the demethanizing unit by pipelines, and the second expansion unit is connected to the low-temperature heat exchange unit and the decarbonized light hydrocarbon unit by pipelines. The low-temperature heat exchange unit is used to cool the material; The demethanizing unit is used to receive the material conveyed by the low-temperature heat exchange unit and separate the methane hydrogen. The decarbonized light hydrocarbon unit is used to receive the remaining material conveyed by the demethanizing unit and separate out the C2 light hydrocarbons, wherein the C2 light hydrocarbons include gaseous C2 light hydrocarbons and liquid C2 light hydrocarbons. The first expansion unit is used to receive the hydrogen methane and expand the hydrogen methane, and then transport the expanded hydrogen methane to the low-temperature heat exchange unit to provide cooling as a refrigerant for the low-temperature heat exchange unit. The second expansion unit is used to receive the gaseous C2 light hydrocarbon and expand the gaseous C2 light hydrocarbon, and then transport the expanded C2 light hydrocarbon to the low-temperature heat exchange unit to provide cooling as a refrigerant for the low-temperature heat exchange unit.

2. The system according to claim 1, characterized in that, The decarbonized light hydrocarbon unit is connected to the low-temperature heat exchange unit via pipeline; The decarbonized light hydrocarbon unit is used to transport the liquid-phase C2 light hydrocarbon to the low-temperature heat exchange unit through pipelines to provide cooling capacity as a refrigerant for the low-temperature heat exchange unit.

3. The system according to claim 1 or 2, characterized in that, The demethanizing unit includes a demethanizing tower and a condenser, with the condenser located in the middle of the demethanizing tower; The demethanizing tower is connected to the pipeline of the low-temperature heat exchange unit and is used to receive the material conveyed by the low-temperature heat exchange unit and separate the methane hydrogen. The condenser is used to condense the gaseous material in the demethanizer.

4. The system according to claim 1, characterized in that, The first expansion unit includes a first expander and a first compressor, wherein the first expander and the first compressor are coaxial devices; The first expander is connected to the pipelines of the low-temperature heat exchange unit and the demethanizing unit, and the first compressor is connected to the pipeline of the low-temperature heat exchange unit. The first expander is used to receive the methane hydrogen supplied by the demethanizing unit and expand the methane hydrogen, and then supply the expanded methane hydrogen to the low-temperature heat exchange unit to provide cooling capacity as a refrigerant for the low-temperature heat exchange unit. The first compressor is used to receive C2 light hydrocarbons after the subcooling has been recovered by the low-temperature heat exchange unit, and to pressurize them.

5. The system according to claim 4, characterized in that, The second expansion unit includes a second expander and a second compressor, which are coaxial devices; The second expander is connected to the low-temperature heat exchange unit and the decarbonized light hydrocarbon unit pipelines respectively, and the second compressor is connected to the low-temperature heat exchange unit and the first compressor pipeline respectively; The second expander is used to receive the gaseous C2 light hydrocarbon and expand the gaseous C2 light hydrocarbon, and then transport the expanded C2 light hydrocarbon to the low-temperature heat exchange unit to provide cooling capacity as a refrigerant for the low-temperature heat exchange unit. The second compressor is used to receive the C2 light hydrocarbons after the subcooling is recovered by the low-temperature heat exchange unit and the C2 light hydrocarbons delivered by the first compressor, and then pressurize them before extraction.

6. The system according to claim 1, characterized in that, The system also includes a deweighting unit and a compression unit. The deweighting unit is connected to the compression unit and the decarbonized light hydrocarbon unit pipelines, respectively. The compression unit is connected to the low-temperature heat exchange unit pipeline. The deweighting unit is used to separate the heavier components from the material. The heavier components are a small amount of C2 light hydrocarbons and components with a carbon element quantity greater than that of C2 light hydrocarbons, and the heavier components are transported to the decarbonized light hydrocarbon unit. The decarbonized light hydrocarbon unit is used to separate the C2 light hydrocarbon from the heavier components; The compression unit is used to receive the components other than the heavier components from the deweighting unit, compress the components other than the heavier components, and transport the compressed material to the low-temperature heat exchange unit.

7. The system according to claim 6, characterized in that, The system also includes a separation tank; The separation tank is connected to the low-temperature heat exchange unit and the demethanizing unit via pipelines; The separation tank is used to receive the material cooled by the low-temperature heat exchange unit, and to perform gas-liquid separation on the cooled material. The liquid phase material is transported to the demethanizing unit, and the gas phase material is transported to the low-temperature heat exchange unit to provide cooling capacity as a refrigerant for the low-temperature heat exchange unit.

8. A light hydrocarbon preparation system, characterized in that, The light hydrocarbon preparation system includes a light hydrocarbon reaction system and a light hydrocarbon separation system as described in claims 1-7.

9. A method for separating light hydrocarbons, characterized in that, The method is applied to the light hydrocarbon separation system according to any one of claims 1-7, and the method comprises: The material is cooled using a low-temperature heat exchange unit; A demethanizing unit is used to receive the material conveyed by the low-temperature heat exchange unit and separate the methane hydrogen. A decarbonization unit receives the remaining material from the demethanization unit and separates out the C2 light hydrocarbons, wherein the C2 light hydrocarbons include gaseous C2 light hydrocarbons and liquid C2 light hydrocarbons. The first expansion unit receives the hydrogen methane and expands it, and then transports the expanded hydrogen methane to the low-temperature heat exchange unit to provide cooling as a refrigerant for the low-temperature heat exchange unit. The second expansion unit receives the gaseous C2 light hydrocarbon and expands it. The expanded C2 light hydrocarbon is then transported to the low-temperature heat exchange unit to provide cooling as a refrigerant for the low-temperature heat exchange unit.

10. The method according to claim 9, characterized in that, The method further includes: The liquid-phase C2 light hydrocarbons are transported through pipelines to the low-temperature heat exchange unit using the decarbonized light hydrocarbon unit to provide cooling capacity as a refrigerant for the low-temperature heat exchange unit.

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