Separation device and separation process of Fischer-Tropsch synthesis tail gas

Abstract

The present invention provides a separation device and separation process for Fischer-Tropsch synthesis tail gas, which include a decarbonization tower, a dehydrogenation tower and a methane distillation tower connected in sequence. The separation device also includes: a first reboiler, having a first heat exchange channel and a second heat exchange channel, the first heat exchange channel being used for heat exchange with the second heat exchange channel, the first heat exchange channel being connected to the bottom of the methane distillation tower, the gas phase light component outlet of the second decarbonization tower being connected to the inlet of the second heat exchange channel to provide a heat source for the first reboiler; a first condenser, the inlet of the first condenser being connected to the top of the dehydrogenation tower; a second condenser, having a third heat exchange channel and a fourth heat exchange channel, the third heat exchange channel being used for heat exchange with the fourth heat exchange channel, the inlet of the third heat exchange channel being connected to the gas phase light component outlet of the methane distillation tower, the outlet of the first condenser being connected to the inlet of the fourth heat exchange channel to provide a cold source for the second condenser.

Description

Technical Field

[0001] The present invention relates to the technical field of Fischer-Tropsch synthesis tail gas treatment, and in particular to a Fischer-Tropsch synthesis tail gas separation device and separation process. Background Art

[0002] Fischer-Tropsch synthesis tail gas components primarily include hydrogen, carbon monoxide, and light hydrocarbons. Currently, distillation is commonly used to separate and recover this tail gas. However, existing distillation processes typically require the introduction of a cryogenic liquefaction unit, which requires numerous cryogenic heat exchangers, increasing process equipment investment and system operating energy consumption. Summary of the Invention

[0003] The present invention provides a separation device and separation process for Fischer-Tropsch synthesis tail gas to solve the problem in the prior art that the distillation process introduces a large number of cryogenic heat exchangers involved in the cryogenic liquefaction unit, which increases the investment in process equipment and the energy consumption of system operation.

[0004] According to one aspect of the present invention, a separation device for Fischer-Tropsch synthesis tail gas is provided, which includes a second decarbonization tower, a dehydrogenation tower and a methane distillation tower connected in sequence, and the separation device also includes: a first reboiler, having a first heat exchange channel and a second heat exchange channel, the first heat exchange channel being used for heat exchange with the second heat exchange channel, the first heat exchange channel being connected to the bottom of the methane distillation tower, the gas phase light component outlet of the second decarbonization tower being connected to the inlet of the second heat exchange channel to provide a heat source for the first reboiler; a first condenser, the inlet of the first condenser being connected to the top of the dehydrogenation tower; a second condenser, having a third heat exchange channel and a fourth heat exchange channel, the third heat exchange channel being used for heat exchange with the fourth heat exchange channel, the inlet of the third heat exchange channel being connected to the gas phase light component outlet of the methane distillation tower, and the outlet of the first condenser being connected to the inlet of the fourth heat exchange channel to provide a cold source for the second condenser.

[0005] Furthermore, a first reflux port is provided at the top of the second decarbonization tower, and the separation device also includes a third condenser and a first reflux tank connected in sequence, the inlet of the third condenser is connected to the gas phase light component outlet of the second decarbonization tower; the first connecting port of the first reflux tank is connected to the first reflux port to pass materials into the second decarbonization tower; the second connecting port of the first reflux tank is connected to the feed port of the dehydrogenation tower to pass materials into the dehydrogenation tower.

[0006] Furthermore, the outlet of the second heat exchange channel of the first reboiler is connected to the third connecting port of the first reflux tank so as to introduce materials into the first reflux tank.

[0007] Furthermore, the separation device further comprises a pressure swing adsorption unit; the outlet of the first condenser is communicated with the feed inlet of the pressure swing adsorption unit so as to feed the material into the pressure swing adsorption unit.

[0008] Furthermore, the outlet of the fourth heat exchange channel of the second condenser is communicated with the feed inlet of the pressure swing adsorption unit so as to feed the material into the pressure swing adsorption unit.

[0009] Furthermore, a second reflux port is provided at the top of the dehydrogenation tower, and the separation device also includes a second reflux tank, which is provided between the first condenser and the dehydrogenation tower; the first connecting port of the second reflux tank is connected to the second reflux port to pass materials into the dehydrogenation tower; the second connecting port of the second reflux tank is connected to the inlet of the fourth heat exchange channel of the second condenser to pass materials into the fourth heat exchange channel of the second condenser; the second connecting port of the second reflux tank is connected to the feed port of the pressure swing adsorption unit to pass materials into the pressure swing adsorption unit; the outlet of the first condenser is connected to the third connecting port of the second reflux tank to pass materials into the second reflux tank.

[0010] Furthermore, a third reflux port is provided at the top of the methane distillation tower, and the separation device also includes a third reflux tank, which is arranged between the second condenser and the methane distillation tower, and the outlet of the third heat exchange channel of the second condenser is connected to the inlet of the third reflux tank; the first connecting port of the third reflux tank is connected to the third reflux port to pass materials into the methane distillation tower.

[0011] Furthermore, the separation device also includes a gas pipeline, and the second connecting port of the third reflux tank is connected to the gas pipeline to feed materials into the gas pipeline.

[0012] Furthermore, the separation device also includes three decarbonization towers and a fourth condenser and a fourth reflux tank connected in sequence. The inlet of the fourth condenser is connected to the gas phase light component outlet of the three decarbonization towers. The top of the three decarbonization towers is provided with a fourth reflux port. The first connecting port of the fourth reflux tank is connected to the fourth reflux port, and the second connecting port of the fourth reflux tank is connected to the feed port of the second decarbonization tower.

[0013] According to another aspect of the present invention, a process for separating Fischer-Tropsch synthesis tail gas is provided, which comprises the following steps:

[0014] Secondary decarbonization treatment: The Fischer-Tropsch synthesis tail gas is subjected to secondary decarbonization treatment through a secondary decarbonization tower to obtain a primary gaseous product and a primary liquid product;

[0015] Dehydrogenation treatment: The first stream of the primary gaseous product is condensed through the third condenser and then passed through the dehydrogenation tower for dehydrogenation treatment to obtain a secondary gaseous product and a secondary liquid product;

[0016] Methane distillation treatment: the secondary liquid product is subjected to methane distillation treatment through a methane distillation tower, the second stream of the primary gaseous product is heat exchanged with the material at the bottom of the methane distillation tower through a first reboiler, so that the material at the bottom of the methane distillation tower is heated by the second stream of the primary gaseous product to obtain a tertiary gaseous product and a tertiary liquid product; a part of the secondary gaseous product is heat exchanged with the tertiary gaseous product through a second condenser, so that the tertiary gaseous product is condensed by the secondary gaseous product; after the second stream of the primary gaseous product after heating the material at the bottom of the methane distillation tower is merged with the first stream of the condensed primary gaseous product in the first reflux tank, the liquid phase component enters the second decarbonization tower for the second decarbonization treatment, and the gas phase component enters the dehydrogenation tower for dehydrogenation treatment.

[0017] Furthermore, before the Fischer-Tropsch synthesis tail gas is subjected to the second decarbonization treatment through the second decarbonization tower, the Fischer-Tropsch synthesis tail gas is subjected to the third decarbonization treatment through the third decarbonization tower.

[0018] By applying the technical solution of the present invention, the outlet of the light gas component of the second decarbonization tower is connected to the inlet of the second heat exchange channel, which can provide a heat source for the first reboiler; the outlet of the first condenser is connected to the inlet of the fourth heat exchange channel of the second condenser, which can provide a cold source for the second condenser. Such an arrangement can reduce the number of cryogenic units in the separation device, reduce the cost and operating energy consumption of the separation device. The condenser and the reboiler at the bottom of the methane distillation tower in the prior art both require a large amount of mixed refrigerant to provide a cold source and a heat source. The present separation device can use the top gas phase component of the second decarbonization tower as the heat source of the first reboiler at the bottom of the methane distillation tower, and the condensed gas at the top of the dehydrogenation tower as the cold source of the second condenser at the top of the methane distillation tower, so that the heat at different temperatures is coupled, effectively reducing the consumption of the mixed refrigerant, maximizing the use of existing working conditions, reducing investment costs, and achieving the purpose of energy saving and consumption reduction, providing a basic guarantee for cost reduction and efficiency improvement of the device. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The accompanying drawings, which constitute part of this application, are intended to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are intended to explain the present invention and do not constitute an undue limitation of the present invention. In the accompanying drawings:

[0020] Figure 1 A schematic structural diagram of a Fischer-Tropsch synthesis tail gas separation device provided according to an embodiment of the present invention is shown.

[0021] The above drawings include the following reference numerals:

[0022] 10. Second decarbonization tower; 11. Third condenser; 12. First reflux tank; 13. Second reboiler;

[0023] 20. Dehydrogenation tower; 21. First condenser; 22. Second reflux tank;

[0024] 30. Methane distillation tower; 31. First reboiler; 32. Second condenser; 33. Third reflux tank;

[0025] 40. Pressure swing adsorption unit;

[0026] 50. Gas pipeline;

[0027] 60. Decarbonization tower three; 61. Fourth condenser; 62. Fourth reflux tank; 63. Third reboiler. DETAILED DESCRIPTION

[0028] The following will be combined with the accompanying drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, rather than all the embodiments. The following description of at least one exemplary embodiment is actually only illustrative and is in no way intended to limit the present invention and its application or use. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0029] like Figure 1 As shown, an embodiment of the present invention provides a Fischer-Tropsch synthesis tail gas separation device, which includes a second decarbonization tower 10, a dehydrogenation tower 20, and a methane distillation tower 30 connected in sequence. The separation device also includes a first reboiler 31, a first condenser 21, and a second condenser 32. The first reboiler 31 has a first heat exchange channel and a second heat exchange channel. The first heat exchange channel is used for heat exchange with the second heat exchange channel. The first heat exchange channel is connected to the bottom of the methane distillation tower 30. The gaseous light component outlet of the second decarbonization tower 10 is connected to the inlet of the second heat exchange channel to provide a heat source for the first reboiler 31. The inlet of the first condenser 21 is connected to the top of the dehydrogenation tower 20. The second condenser 32 has a third heat exchange channel and a fourth heat exchange channel. The third heat exchange channel is used for heat exchange with the fourth heat exchange channel. The inlet of the third heat exchange channel is connected to the gaseous light component outlet of the methane distillation tower 30. The outlet of the first condenser 21 is connected to the inlet of the fourth heat exchange channel to provide a cold source for the second condenser 32. In this embodiment, the pressure at the top of the second decarbonization tower 10, the pressure at the top of the dehydrogenation tower 20, and the pressure at the top of the methane distillation tower 30 decrease in sequence. In this embodiment, a second reboiler 13 is provided at the bottom of the second decarbonization tower 10.

[0030] By applying the technical solution of the present invention, the outlet of the gaseous light component of the second decarbonization tower 10 is connected to the inlet of the second heat exchange channel, which can provide a heat source for the first reboiler 31; the outlet of the first condenser 21 is connected to the inlet of the fourth heat exchange channel of the second condenser 32, which can provide a cold source for the second condenser 32. Such an arrangement can reduce the number of cryogenic units in the separation device, reducing the cost and operating energy consumption of the separation device. The condenser and the reboiler at the bottom of the methane distillation tower in the prior art both require a large amount of mixed refrigerant to provide a cold source and a heat source. The present separation device can use the top gas phase component of the second decarbonization tower 10 as the heat source of the first reboiler 31 at the bottom of the methane distillation tower 30, and the condensed gas at the top of the dehydrogenation tower 20 as the cold source of the second condenser 32 at the top of the methane distillation tower 30, so that the heat at different temperatures is coupled, effectively reducing the consumption of the mixed refrigerant, maximizing the use of existing working conditions, reducing investment costs, and achieving the purpose of energy saving and consumption reduction, providing a basic guarantee for cost reduction and efficiency improvement of the device.

[0031] Specifically, a first reflux port is provided at the top of the second decarbonization tower 10, and the separation device further includes a third condenser 11 and a first reflux tank 12 connected in sequence. The inlet of the third condenser 11 is connected to the gaseous light component outlet of the second decarbonization tower 10; the first connecting port of the first reflux tank 12 is connected to the first reflux port to pass materials into the second decarbonization tower 10; and the second connecting port of the first reflux tank 12 is connected to the feed port of the dehydrogenation tower 20 to pass materials into the dehydrogenation tower 20. A primary gaseous product is produced at the top of the second decarbonization tower 10. The primary gaseous product mainly includes gases such as hydrogen and methane, and includes trace amounts of carbon-2 components such as ethane and ethylene. The first stream of the primary gaseous product is condensed by the third condenser 11 and enters the first reflux tank 12. The gaseous components flowing into the first reflux tank 12 are passed into the dehydrogenation tower 20 for dehydrogenation treatment, and the liquid components are refluxed into the second decarbonization tower 10 for further distillation to improve the purity of the product. The second stream of the primary gaseous product is introduced into the second heat exchange channel of the first reboiler 31 and thermally coupled with the material at the bottom of the methane distillation tower 30 .

[0032] Furthermore, the outlet of the second heat exchange channel of the first reboiler 31 is connected to the third connecting port of the first reflux drum 12, so that material can be introduced into the first reflux drum 12. This arrangement allows the second stream of the primary gaseous product, which has exchanged heat with the material at the bottom of the methane distillation column 30, to be re-introduced into the first reflux drum 12 after heat exchange. This arrangement maximizes resource utilization of this stream material and fully realizes its value. That is, after heat exchange, this stream material is returned to the first reflux drum 12 for subsequent processing without affecting the output of subsequent stages, thereby achieving energy conservation.

[0033] Furthermore, the separation device further includes a pressure swing adsorption unit 40; the outlet of the first condenser 21 is connected to the feed inlet of the pressure swing adsorption unit 40 to feed the material into the pressure swing adsorption unit 40. This arrangement can further ensure the purity of the separated hydrogen.

[0034] Furthermore, the outlet of the fourth heat exchange channel of the second condenser 32 is connected to the feed port of the pressure swing adsorption unit 40 to feed the material into the pressure swing adsorption unit 40. This arrangement allows the material stream to undergo heat exchange before flowing to the pressure swing adsorption unit 40 for subsequent processing, without affecting the output of subsequent stages. This maximizes resource utilization of the material stream and fully realizes the value of the material stream.

[0035] Furthermore, a second reflux port is provided at the top of the dehydrogenation tower 20, and the separation device also includes a second reflux tank 22, which is arranged between the first condenser 21 and the dehydrogenation tower 20; the outlet of the first condenser 21 is connected to the third connecting port of the second reflux tank 22 to pass materials into the second reflux tank 22; the first connecting port of the second reflux tank 22 is connected to the second reflux port to pass materials into the dehydrogenation tower 20; the setting of the second reflux tank 22 can enable the secondary gaseous products after dehydrogenation treatment to be condensed and then refluxed to the dehydrogenation tower 20 for further distillation treatment. Such a setting can further ensure the purity of the secondary gaseous products.

[0036] Furthermore, the second connecting port of the second reflux tank 22 is connected to the inlet of the fourth heat exchange channel of the second condenser 32 to pass materials into the fourth heat exchange channel of the second condenser 32; such an arrangement can enable part of the secondary gaseous products to serve as the cold source of the second condenser 32 after condensation, thereby ensuring the heat exchange effect with the material in the third heat exchange channel in the second condenser 32.

[0037] Furthermore, the second connecting port of the second reflux tank 22 is connected to the feed port of the pressure swing adsorption unit 40 to feed the material into the pressure swing adsorption unit 40. This configuration allows the remaining portion of the secondary gaseous product after condensation to be fed into the pressure swing adsorption unit, further ensuring the purity of the generated hydrogen.

[0038] Furthermore, a third reflux port is provided at the top of the methane distillation tower 30, and the separation device also includes a third reflux tank 33, which is arranged between the second condenser 32 and the methane distillation tower 30, and the outlet of the third heat exchange channel of the second condenser 32 is connected to the inlet of the third reflux tank 33; such a setting can enable the secondary gaseous product after heat exchange in the second condenser 32 to be reused without affecting the output of subsequent work sections, thereby maximizing the resource utilization of the stream material and giving full play to the value of the stream material.

[0039] Furthermore, the first connecting port of the third reflux tank 33 is connected to the third reflux port to feed materials into the methane rectification column 30. This arrangement can improve the distillation effect of the secondary gaseous product and ensure the purity of the prepared hydrogen.

[0040] Furthermore, the separation device further includes a gas pipeline 50, and the second connecting port of the third reflux tank 33 is connected to the gas pipeline 50 to allow materials to be introduced into the gas pipeline 50. This arrangement can ensure the balance of the fuel gas system of the on-site kerosene production device.

[0041] Specifically, the temperature of the gas phase light component outlet at the top of the second decarbonization tower 10 is -60°C, and the temperature of the outlet of the first condenser 21 is -109°C; the temperature of the inlet of the first heat exchange channel of the first reboiler 31 is -112°C, and the temperature of the outlet of the first heat exchange channel of the first reboiler 31 is -108°C; the temperature of the inlet of the second heat exchange channel of the first reboiler 31 is -60°C, and the temperature of the outlet of the second heat exchange channel of the first reboiler 31 is -109°C; the temperature of the outlet of the first condenser 21 is -176°C, the temperature of the inlet of the fourth heat exchange channel of the second condenser 32 is -176°C, and the temperature of the outlet of the fourth heat exchange channel of the second condenser 32 is -161°C; the temperature of the inlet of the third heat exchange channel of the second condenser 32 is -156°C, and the temperature of the outlet of the third heat exchange channel of the second condenser 32 is -157°C.

[0042] Furthermore, the separation device also includes a decarbonization tower 3 60 and a fourth condenser 61 and a fourth reflux tank 62 connected in sequence. The inlet of the fourth condenser 61 is connected to the gas phase light component outlet of the decarbonization tower 3 60. The top of the decarbonization tower 3 60 is provided with a fourth reflux port. The first connecting port of the fourth reflux tank 62 is connected to the fourth reflux port, and the second connecting port of the fourth reflux tank 62 is connected to the feed port of the decarbonization tower 2 10. A third reboiler 63 is also provided at the bottom of the decarbonization tower 3 60. This configuration ensures the recovery of the three carbon products, wherein the three carbon products (LPG) mainly include propane and propylene.

[0043] The present invention also provides a process for separating tail gas from Fischer-Tropsch synthesis, which uses the above-mentioned separation device. The separation process comprises the following steps:

[0044] Secondary decarbonization treatment: The Fischer-Tropsch synthesis tail gas is subjected to secondary decarbonization treatment in the secondary decarbonization tower 10 to obtain a primary gaseous product and a primary liquid product (C2);

[0045] Dehydrogenation treatment: The first stream of the primary gaseous product is condensed by the third condenser 11 and then passed through the dehydrogenation tower 20 for dehydrogenation treatment to obtain a secondary gaseous product and a secondary liquid product;

[0046] Methane distillation treatment: The secondary liquid product is subjected to methane distillation treatment through a methane distillation tower 30, and the second stream of the primary gaseous product is heat-exchanged with the material at the bottom of the methane distillation tower 30 through a first reboiler 31, so that the material at the bottom of the methane distillation tower 30 is heated by the second stream of the primary gaseous product to obtain a tertiary gaseous product and a tertiary liquid product; a portion of the secondary gaseous product is heat-exchanged with the tertiary gaseous product through a second condenser 32, so that the tertiary gaseous product is condensed by the secondary gaseous product;

[0047] After the second stream of the first-level gaseous product after heating the material at the bottom of the methane distillation tower 30 is merged with the first stream of the first-level gaseous product after condensation in the first reflux tank 12, the liquid phase component enters the second decarbonization tower 10 for second decarbonization treatment, and the gas phase component enters the dehydrogenation tower 20 for dehydrogenation treatment.

[0048] Before the second decarbonization treatment, a third decarbonization treatment is performed through a third decarbonization tower 60 to obtain a third carbon product (LPG).

[0049] Such a setting can maximize the use of existing working conditions, rationally utilize the heat generated by each process, reduce investment costs, achieve the purpose of energy saving and consumption reduction, and ensure that the output of the final product is not affected.

[0050] Among them, the top pressure of the decarbonization tower 60 is set between 2.2 and 2.4 MPa; the top pressure of the decarbonization tower 10 is controlled between 2.0 and 2.2 MPa, the top pressure of the dehydrogenation tower 20 is controlled between 1.8 and 2.0 MPa; the top pressure of the methane distillation tower 30 is controlled between 0.5 and 1.8 MPa.

[0051] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present application. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, they indicate the presence of features, steps, operations, devices, components and / or combinations thereof.

[0052] Unless otherwise specifically stated, the relative arrangement of the parts and steps, the numerical expressions and the numerical values ​​set forth in these embodiments do not limit the scope of the present invention. At the same time, it should be understood that, for ease of description, the sizes of the various parts shown in the drawings are not drawn according to the actual proportional relationship. The techniques, methods and equipment known to those of ordinary skill in the relevant art may not be discussed in detail, but where appropriate, the techniques, methods and equipment should be considered as part of the authorization specification. In all examples shown and discussed here, any specific values ​​should be interpreted as being merely exemplary and not as limiting. Therefore, other examples of the exemplary embodiments may have different values. It should be noted that similar numbers and letters represent similar items in the following figures, and therefore, once an item is defined in one figure, it does not need to be further discussed in subsequent figures.

[0053] In the description of the present invention, it should be understood that the directions or positional relationships indicated by directional words such as "front, back, up, down, left, right", "horizontal, vertical, perpendicular, horizontal" and "top, bottom" are usually based on the directions or positional relationships shown in the accompanying drawings. They are only for the convenience of describing the present invention and simplifying the description. Unless otherwise specified, these directional words do not indicate or imply that the system or element referred to must have a specific direction or be constructed and operated in a specific direction. Therefore, they cannot be understood as limiting the scope of protection of the present invention; the directional words "inside and outside" refer to the inside and outside relative to the outline of each component itself.

[0054] For ease of description, spatially relative terms such as "above", "above", "on the upper surface of", "above", etc. may be used herein to describe the spatial positional relationship of a device or feature to other devices or features as shown in the figures. It should be understood that spatially relative terms are intended to include different orientations of the device in use or operation in addition to the orientation described in the figures. For example, if the device in the drawings is inverted, the device described as "above other devices or structures" or "above other devices or structures" will be positioned as "below other devices or structures" or "below other devices or structures". Thus, the exemplary term "above" can include both "above" and "below". The device can also be positioned in other different ways (rotated 90 degrees or in other orientations), and the spatially relative descriptions used here are interpreted accordingly.

[0055] In addition, it should be noted that the use of terms such as "first" and "second" to limit components is only for the convenience of distinguishing the corresponding components. Unless otherwise stated, the above terms have no special meaning and therefore cannot be understood as limiting the scope of protection of the present invention.

[0056] The foregoing description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art will readily appreciate that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention are intended to be within the scope of protection of the present invention.

Claims

1. A Fischer-Tropsch synthesis tail gas separation device, characterized in that: The separation device comprises a second decarbonization tower (10), a dehydrogenation tower (20) and a methane distillation tower (30) connected in sequence, and further comprises: a first reboiler (31) having a first heat exchange channel and a second heat exchange channel, wherein the first heat exchange channel is used for heat exchange with the second heat exchange channel, the first heat exchange channel is connected to the bottom of the methane rectification tower (30), and the gas phase light component outlet of the second decarbonization tower (10) is connected to the inlet of the second heat exchange channel to provide a heat source for the first reboiler (31); a first condenser (21), wherein an inlet of the first condenser (21) is connected to the top of the dehydrogenation tower (20); A second condenser (32) has a third heat exchange channel and a fourth heat exchange channel, the third heat exchange channel is used for heat exchange with the fourth heat exchange channel, and the inlet of the third heat exchange channel is connected to the gas phase light component outlet of the methane distillation tower (30); The top of the second decarbonization tower (10) is provided with a first reflux port, and the separation device further comprises a third condenser (11) and a first reflux tank (12) connected in sequence, and the inlet of the third condenser (11) is communicated with the gas phase light component outlet of the second decarbonization tower (10); The first connecting port of the first reflux tank (12) is connected to the first reflux port to allow materials to be introduced into the second decarbonization tower (10); The second communication port of the first reflux tank (12) is connected to the feed port of the dehydrogenation tower (20) so as to feed materials into the dehydrogenation tower (20); The outlet of the second heat exchange channel of the first reboiler (31) is connected to the third connecting port of the first reflux tank (12) so as to allow materials to be introduced into the first reflux tank (12); The pressure at the top of the second decarbonization tower (10), the pressure at the top of the dehydrogenation tower (20), and the pressure at the top of the methane distillation tower (30) decrease in sequence; The top of the dehydrogenation tower (20) is provided with a second reflux port, and the separation device further comprises a second reflux tank (22), and the second reflux tank (22) is provided between the first condenser (21) and the dehydrogenation tower (20); The outlet of the first condenser (21) is connected to the third communication port of the second reflux tank (22) so as to allow materials to flow into the second reflux tank (22); The first communication port of the second reflux tank (22) is in communication with the second reflux port so as to introduce materials into the dehydrogenation tower (20); The second communication port of the second reflux tank (22) is communicated with the inlet of the fourth heat exchange channel of the second condenser (32) so as to allow material to flow into the fourth heat exchange channel of the second condenser (32); The top of the methane distillation tower (30) is provided with a third reflux port, and the separation device further comprises a third reflux tank (33), the third reflux tank (33) being provided between the second condenser (32) and the methane distillation tower (30), and the outlet of the third heat exchange channel of the second condenser (32) is communicated with the inlet of the third reflux tank (33); The first communication port of the third reflux tank (33) is in communication with the third reflux port to allow materials to be introduced into the methane distillation tower (30); The separation device further comprises a pressure swing adsorption unit (40); The second communication port of the second reflux tank (22) is connected to the feed port of the pressure swing adsorption unit (40) so as to feed material into the pressure swing adsorption unit (40).

2. The separation device according to claim 1, characterized in that The outlet of the fourth heat exchange channel of the second condenser (32) is communicated with the feed inlet of the pressure swing adsorption unit (40) so as to allow material to be introduced into the pressure swing adsorption unit (40).

3. The separation device according to claim 1, characterized in that The separation device further comprises a gas pipeline (50), and the second communication port of the third reflux tank (33) is in communication with the gas pipeline (50) so as to allow materials to flow into the gas pipeline (50).

4. The separation device according to claim 1, characterized in that The separation device also includes a decarbonization tower (60) and a fourth condenser (61) and a fourth reflux tank (62) connected in sequence, the inlet of the fourth condenser (61) is connected to the gas phase light component outlet of the decarbonization tower (60), the top of the decarbonization tower (60) is provided with a fourth reflux port, the first connecting port of the fourth reflux tank (62) is connected to the fourth reflux port, and the second connecting port of the fourth reflux tank (62) is connected to the feed port of the decarbonization tower (10).

5. A process for separating tail gas from Fischer-Tropsch synthesis, characterized in that: Using the separation device according to any one of claims 1 to 4, the separation process of the Fischer-Tropsch synthesis tail gas comprises the following steps: Secondary decarbonization treatment: The Fischer-Tropsch synthesis tail gas is subjected to secondary decarbonization treatment via a secondary decarbonization tower (10) to obtain a primary gaseous product and a primary liquid product; Dehydrogenation treatment: condensing the first stream of the primary gaseous product through a third condenser (11) and then passing it through a dehydrogenation tower (20) for dehydrogenation treatment to obtain a secondary gaseous product and a secondary liquid product; Methane distillation treatment: the secondary liquid product is subjected to methane distillation treatment through a methane distillation tower (30), the second stream of the primary gaseous product is subjected to heat exchange with the material at the bottom of the methane distillation tower (30) through a first reboiler (31), so that the material at the bottom of the methane distillation tower (30) is heated by the second stream of the primary gaseous product to obtain a tertiary gaseous product and a tertiary liquid product; a portion of the secondary gaseous product is subjected to heat exchange with the tertiary gaseous product through a second condenser (32), so that the tertiary gaseous product is condensed by the secondary gaseous product; After the second stream of the first-stage gaseous product after the material at the bottom of the methane distillation tower (30) is heated and the first stream of the first-stage gaseous product after condensation is merged in the first reflux tank (12), the liquid phase component enters the second decarbonization tower (10) for second decarbonization treatment, and the gas phase component enters the dehydrogenation tower (20) for dehydrogenation treatment.

6. The separation process according to claim 5, characterized in that Before the Fischer-Tropsch synthesis tail gas is subjected to the second decarbonization treatment through the second decarbonization tower (10), the Fischer-Tropsch synthesis tail gas is subjected to the third decarbonization treatment through the third decarbonization tower (60).

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