Fischer-Tropsch synthesis tail gas treatment device

Abstract

The present invention provides a Fischer-Tropsch synthesis tail gas treatment device, comprising: a separation component having a gas inlet and a gas outlet; a main heat exchanger having a first heat exchange channel, a second heat exchange channel and a plurality of heat exchange paths, the inlet of the heat exchange path at the head end being connected to the gas outlet; a plurality of separation tanks, the inlets of which are connected to the outlets of the corresponding heat exchange paths, and the gas phase outlets being connected to the inlets of the heat exchange paths corresponding to the next-stage separation tanks; a mixed refrigerant compression system, the inlet of which is connected to the outlet of the first heat exchange channel, and the gas phase outlet being connected to the inlet of the first heat exchange channel; an LNG distillation tower and an LNG storage tank, the liquid phase outlet of the last-stage separation tank being connected to the liquid phase inlet of the LNG distillation tower, the liquid phase outlet of the LNG distillation tower being connected to the inlet of the second heat exchange path, and the outlet of the second heat exchange path being connected to the LNG storage tank. The technical solution provided by the present application can solve the problem of the relatively complex structure of the Fischer-Tropsch synthesis tail gas treatment device in the prior art.

Description

Technical Field

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

[0002] Fischer-Tropsch synthesis (FTS) is a method for indirectly synthesizing oil products using coal, natural gas, and other raw materials. It utilizes a catalyst to convert synthesis gas (H2 + CO) into heavy oil, light oil, wax, and low-carbon hydrocarbons. In addition to the aforementioned products, the FTS reaction also produces a significant amount of tail gas. This tail gas primarily consists of unreacted hydrogen, carbon monoxide, and nitrogen, as well as carbon dioxide and light hydrocarbon components generated by side reactions.

[0003] Currently, there are four main methods for treating Fischer-Tropsch synthesis tail gas: first, converting the tail gas into hydrogen-rich gas with a higher calorific value to generate electricity; second, recovering the hydrocarbons in the tail gas and sending it to a boiler to burn the by-product steam; third, discharging part of the tail gas, separating the low-carbon hydrocarbons from the remaining tail gas, and then converting the hydrocarbons in the tail gas into synthesis gas through conversion reactions, oxidation, etc., and returning it to the Fischer-Tropsch synthesis reactor; fourth, separating the low-carbon hydrocarbons in the tail gas through low-temperature distillation.

[0004] Among them, low-carbon hydrocarbons, hydrogen, and carbon monoxide are components with high added value. The first two treatment methods use them extensively as fuel, which is a poor treatment method with poor economic efficiency. The third solution cracks the hydrocarbons produced by the Fischer-Tropsch synthesis reaction into synthesis gas, which has low energy utilization. Therefore, in the existing technology, the fourth treatment method is generally adopted. It recovers hydrogen, methane, carbon monoxide, and low-carbon hydrocarbons from the Fischer-Tropsch synthesis tail gas through low-temperature fractionation. This will greatly increase the economic value of the Fischer-Tropsch synthesis tail gas and improve the comprehensive energy utilization efficiency of the entire coal indirect liquefaction unit.

[0005] In the existing technology, a low-temperature multi-tower distillation scheme is usually adopted to separate the effective components in the Fischer-Tropsch synthesis tail gas. The number of distillation towers used in the cryogenic separation unit is required to be at least 5, which leads to large equipment investment in the cryogenic separation unit and large differences in the overall cooling capacity demand of the process.

[0006] For example, patent application number 201910952440.X provides a Fischer-Tropsch synthesis tail gas recovery and utilization system process. The system purifies the tail gas through water washing, decarbonization, and alkaline washing, then feeds it into a cryogenic separation system. The purified tail gas is cooled and liquefied to recover C2, C3, and heavier components. Methane in the tail gas is condensed and liquefied to produce LNG products. Hydrogen and carbon monoxide are purified through a PSA unit, and the desorbed gas is pressurized and incorporated into the fuel gas pipeline network. Furthermore, the Fischer-Tropsch synthesis tail gas recovery and utilization system includes distillation towers such as a demethanizer, deethanizer, depropanizer, debutanizer, and denitrogenator, resulting in a complex structure, high equipment investment, and complicated equipment layout. Summary of the Invention

[0007] The present invention provides a Fischer-Tropsch synthesis tail gas treatment device to solve the problem of relatively complex structure of the Fischer-Tropsch synthesis tail gas treatment device in the prior art.

[0008] The present invention provides a Fischer-Tropsch synthesis tail gas treatment device, which includes: a separation component, the separation component having a gas inlet and a gas outlet, the gas inlet being used to transport raw gas, and the separation component being capable of removing non-condensable gas, CO2 and moisture in the raw gas; a main heat exchanger, the main heat exchanger having a first heat exchange channel, a second heat exchange channel and a plurality of heat exchange flow paths, the plurality of heat exchange flow paths, the first heat exchange channel and the second heat exchange channel being spaced apart along the extension direction of the main heat exchanger, the inlet of the heat exchange flow path at the head end being connected to the gas outlet, and the main heat exchanger being capable of cooling the raw gas in the heat exchange flow path; a plurality of separation tanks being arranged in one-to-one correspondence with the plurality of heat exchange flow paths, the inlet of the separation tank being connected to the gas outlet The outlet of the corresponding heat exchange flow path is connected, and the gas phase outlet of the separation tank is connected to the inlet of the heat exchange flow path corresponding to the next-stage separation tank; the mixed refrigerant compression system, the inlet of the mixed refrigerant compression system is connected to the outlet of the first heat exchange channel, and the gas phase outlet of the mixed refrigerant compression system is connected to the inlet of the first heat exchange channel, and the mixed refrigerant compression system can cool the main heat exchanger; LNG distillation tower and LNG storage tank, the liquid phase outlet of the last-stage separation tank is connected to the liquid phase inlet of the LNG distillation tower, the liquid phase outlet of the LNG distillation tower is connected to the inlet of the second heat exchange channel, and the outlet of the second heat exchange channel is connected to the LNG storage tank, and the main heat exchanger can cool the LNG product of the second heat exchange channel.

[0009] Furthermore, the main heat exchanger has a third heat exchange channel and a fourth heat exchange channel, which are arranged between the first heat exchange channel and the second heat exchange channel, the third heat exchange channel is arranged close to the first heat exchange channel, and the fourth heat exchange channel is arranged close to the second heat exchange channel. The Fischer-Tropsch synthesis tail gas treatment device also includes: a nitrogen compression system, the inlet of the nitrogen compression system is connected to the outlet of the third heat exchange channel, and the outlet of the nitrogen compression system is connected to the inlet of the fourth heat exchange channel, and the nitrogen compression system can cool the main heat exchanger and the LNG distillation tower; a first heat exchanger, the first heat exchanger has a first pipeline and a second pipeline, the inlet of the first pipeline is connected to the gas phase outlet of the LNG distillation tower, the liquid phase outlet of the first pipeline is connected to the reflux inlet of the LNG distillation tower, the inlet of the second pipeline is connected to the outlet of the fourth heat exchange channel, and there is a first connecting pipeline between the inlet of the second pipeline and the outlet of the fourth heat exchange channel, a first throttle valve is provided on the first connecting pipeline, and the outlet of the second pipeline is connected to the inlet of the third heat exchange channel.

[0010] Furthermore, the main heat exchanger also has a fifth heat exchange channel, which is arranged on the side of the heat exchange flow path away from the first heat exchange channel, and the inlet of the fifth heat exchange channel is connected to the gas outlet. The Fischer-Tropsch synthesis tail gas treatment device also includes: a heavy hydrocarbon washing tower, the gas phase inlet of the heavy hydrocarbon washing tower is connected to the outlet of the fifth heat exchange channel, and the gas phase outlet of the heavy hydrocarbon washing tower is connected to the inlet of the heat exchange flow path at the head end to remove the heavy hydrocarbon components in the raw gas.

[0011] Furthermore, the liquid phase outlet of the separation tank is connected to the washing inlet of the heavy hydrocarbon washing tower to remove heavy hydrocarbon components in the raw gas, and the washing inlet of the heavy hydrocarbon washing tower is located above the gas phase inlet of the heavy hydrocarbon washing tower.

[0012] Furthermore, the Fischer-Tropsch synthesis tail gas treatment device also includes: a deethanizer, the liquid phase inlet of the deethanizer is connected to the liquid phase outlet of the heavy hydrocarbon washing tower to separate the C2 component in the raw gas.

[0013] Furthermore, the Fischer-Tropsch synthesis tail gas treatment device also includes: a second heat exchanger, the second heat exchanger has a third pipeline and a fourth pipeline, the inlet of the third pipeline is connected to the gas phase outlet of the deethanizer, the liquid phase outlet of the third pipeline is connected to the reflux inlet of the deethanizer, and the gas phase outlet of the third pipeline is used to discharge the C2 component; the inlet of the fourth pipeline is connected to the liquid phase outlet of the mixed refrigerant compression system, the outlet of the fourth pipeline is connected to the inlet of the mixed refrigerant compression system, and there is a second connecting pipeline between the inlet of the fourth pipeline and the liquid phase outlet of the mixed refrigerant compression system, and a second throttle valve is provided on the second connecting pipeline.

[0014] Furthermore, a third heat exchanger is provided between the first heat exchange channel and the liquid phase outlet of the LNG distillation tower to cool the mixed refrigerant in the first heat exchange channel.

[0015] Furthermore, the third heat exchanger has a fifth pipeline and a sixth pipeline, the inlet of the fifth pipeline is connected to the liquid phase outlet of the LNG distillation tower, and the outlet of the fifth pipeline is connected to the inlet of the second heat exchange channel. The first heat exchange channel includes: a first flow channel, the inlet of the first flow channel is connected to the gas phase outlet of the mixed refrigerant compression system, and the outlet of the first flow channel is connected to the inlet of the sixth pipeline; a second flow channel, the inlet of the second flow channel is connected to the outlet of the sixth pipeline; a third flow channel, the inlet of the third flow channel is connected to the outlet of the second flow channel, and a third connecting pipeline is provided between the inlet of the third flow channel and the outlet of the second flow channel, a third throttle valve is provided on the third connecting pipeline, and the outlet of the third flow channel is connected to the inlet of the mixed refrigerant compression system, and the first flow channel, the second flow channel and the third flow channel are spaced apart along the direction of the heat exchange flow channel and the second heat exchange channel.

[0016] Furthermore, the multiple heat exchange flow paths include a first heat exchange flow path, a second heat exchange flow path and a third heat exchange flow path, and the first heat exchange flow path, the second heat exchange flow path and the third heat exchange flow path are spaced apart in a direction close to the first heat exchange channel, and the inlet of the first heat exchange flow path is connected to the gas phase outlet of the heavy hydrocarbon washing tower; the multiple separation tanks include a first-stage separation tank, a second-stage separation tank and a third-stage separation tank, the inlet of the first-stage separation tank is connected to the outlet of the first heat exchange flow path, the gas phase outlet of the first-stage separation tank is connected to the inlet of the second heat exchange flow path, the inlet of the second-stage separation tank is connected to the outlet of the second heat exchange flow path, the gas phase outlet of the second-stage separation tank is connected to the outlet of the third heat exchange flow path, the inlet of the third-stage separation tank is connected to the outlet of the third heat exchange flow path, and the liquid phase outlet of the third-stage separation tank is connected to the liquid phase inlet of the LNG distillation tower.

[0017] Furthermore, the main heat exchanger has a sixth heat exchange channel, which is arranged on the side of the second heat exchange channel away from the first heat exchange channel, and the inlet of the sixth heat exchange channel is connected to the gas phase outlet of the first pipeline. The Fischer-Tropsch synthesis tail gas treatment device also includes: a CO adsorption unit, the inlet of the CO adsorption unit is connected to the outlet of the sixth heat exchange channel, and the first outlet of the CO adsorption unit is used to discharge CO; an H2 adsorption unit, the inlet of the H2 adsorption unit is connected to the second outlet of the CO adsorption unit, the first outlet of the H2 adsorption unit is used to discharge H2, and the second outlet of the H2 adsorption unit is used to communicate with the fuel system.

[0018] Furthermore, the main heat exchanger has a seventh heat exchange channel, which is arranged on the side of the sixth heat exchange channel away from the second heat exchange channel, and the outlet of the seventh heat exchange channel is connected to the inlet of the CO adsorption unit. The Fischer-Tropsch synthesis tail gas treatment device also includes: a dehydrogenation tower, the gas phase inlet of the dehydrogenation tower is connected to the gas phase outlet of the tertiary separation tank, the liquid phase outlet of the dehydrogenation tower is connected to the liquid phase inlet of the LNG distillation tower, and the gas phase outlet of the dehydrogenation tower is connected to the inlet of the seventh heat exchange channel.

[0019] Furthermore, the Fischer-Tropsch synthesis tail gas treatment device also includes: a fourth heat exchanger, the fourth heat exchanger has a seventh pipeline and an eighth pipeline, the inlet of the seventh pipeline is connected to the gas phase outlet of the dehydrogenation tower, the liquid phase outlet of the seventh pipeline is connected to the reflux inlet of the dehydrogenation tower, the gas phase outlet of the seventh pipeline is connected to the inlet of the seventh heat exchange channel, the inlet of the eighth pipeline is connected to the outlet of the fourth heat exchange channel, and there is a fourth connecting pipeline between the inlet of the eighth pipeline and the outlet of the fourth heat exchange channel, a fourth throttle valve is provided on the fourth connecting pipeline, the outlet of the eighth pipeline is connected to the inlet of the third heat exchange channel, and the nitrogen compression system can cool the dehydrogenation tower.

[0020] Furthermore, the separation component includes: a membrane separation structure, the membrane separation structure has a gas inlet, and the first outlet of the membrane separation structure is connected to the inlet of the CO adsorption unit to remove non-condensable gas in the raw gas; a deacidification tower, the inlet of the deacidification tower is connected to the second outlet of the membrane separation structure to remove CO2 in the raw gas; a precooler, the inlet of the precooler is connected to the outlet of the deacidification tower; a gas-liquid separation tank, the inlet of the gas-liquid separation tank is connected to the outlet of the precooler; an adsorption tower, the inlet of the adsorption tower is connected to the gas phase outlet of the gas-liquid separation tank to remove CO2 in the raw gas; a drying tower, the inlet of the drying tower is connected to the outlet of the adsorption tower, and the drying tower has a gas outlet to remove moisture in the raw gas.

[0021] By applying the technical solution of the present invention, the mixed refrigerant compression system is connected to the first heat exchange channel of the main heat exchanger. The mixed refrigerant compression system can cool the main heat exchanger. The raw gas passes through the separation component to remove non-condensable gas, CO2 and moisture, and then is input into the heat exchange flow path at the head end for cooling. The cooled raw gas enters the separation tank for gas-liquid separation, and the liquid phase components flow through the next heat exchange flow path and the separation tank for further separation until the liquid phase components flow to the last stage separation tank for gas-liquid separation. Then the liquid phase components of the last stage separation tank flow into the LNG distillation tower to separate the LNG product. The LNG product is cooled through the second heat exchange channel and then transported to the LNG storage tank for storage. Among them, since the multiple heat exchange paths and the first heat exchange channel are spaced apart along the extension direction of the main heat exchanger, the temperature of the heat exchange path at the head end is higher and the temperature of the heat exchange path at the end end is lower. Such an arrangement can make full use of the difference between the boiling points of the components for separation. Only a separation tank is needed, avoiding the use of multiple distillation towers, thereby simplifying the structure of the Fischer-Tropsch synthesis tail gas treatment device, and reducing the equipment investment cost of the Fischer-Tropsch synthesis tail gas treatment device, while reducing the energy consumption of the tail gas treatment process. At the same time, in the present application, non-condensable gas, CO2 and moisture are removed in advance to avoid non-condensable gas, CO2 and moisture from absorbing cold in the heat exchange path and the separation tank, thereby reducing the loss of cold, and further reducing the equipment investment cost of the Fischer-Tropsch synthesis tail gas treatment device. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] 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:

[0023] Figure 1 A schematic structural diagram of a Fischer-Tropsch synthesis tail gas treatment device provided according to an embodiment of the present invention is shown.

[0024] The above drawings include the following reference numerals:

[0025] 10. Separate components;

[0026] 11. Membrane separation structure; 12. Deacidification tower; 13. Precooler; 14. Gas-liquid separation tank; 15. Adsorption tower; 16. Drying tower;

[0027] 20. Main heat exchanger;

[0028] 21. First heat exchange channel;

[0029] 211, first flow channel; 212, second flow channel; 213, third flow channel;

[0030] 22. Second heat exchange channel;

[0031] 231, first heat exchange flow path; 232, second heat exchange flow path; 233, third heat exchange flow path;

[0032] 24, third heat exchange channel; 25, fourth heat exchange channel; 26, fifth heat exchange channel; 27, sixth heat exchange channel; 28, seventh heat exchange channel;

[0033] 31. Primary separation tank; 32. Secondary separation tank; 33. Tertiary separation tank;

[0034] 41. Mixed refrigerant compression system; 42. Nitrogen compression system;

[0035] 51. LNG distillation tower; 52. LNG storage tank;

[0036] 61. First heat exchanger;

[0037] 62. First connecting pipeline; 621. First throttle valve;

[0038] 63. Second heat exchanger;

[0039] 64. Second connecting pipeline; 641. Second throttle valve;

[0040] 65. The third heat exchanger;

[0041] 66. Third connecting pipeline; 661. Third throttle valve;

[0042] 67. Fourth heat exchanger;

[0043] 68. Fourth connecting pipeline; 681. Fourth throttle valve;

[0044] 71. Heavy hydrocarbon scrubber; 72. Deethanizer; 73. Dehydrogenator;

[0045] 81. CO adsorption unit; 82. H2 adsorption unit. DETAILED DESCRIPTION

[0046] 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.

[0047] like Figure 1 As shown, the present application provides a Fischer-Tropsch synthesis tail gas treatment device, which includes a separation assembly 10, a main heat exchanger 20, multiple separation tanks, a mixed refrigerant compression system 41, an LNG distillation tower 51, and an LNG storage tank 52. The separation assembly 10 has a gas inlet and a gas outlet. The gas inlet is used to transport feed gas, and the separation assembly 10 is capable of removing non-condensable gases, CO2, and moisture from the feed gas. The main heat exchanger 20 has a first heat exchange channel 21, a second heat exchange channel 22, and multiple heat exchange paths. The multiple heat exchange paths, the first heat exchange channel 21, and the second heat exchange channel 22, are spaced apart along the extension direction of the main heat exchanger 20. The inlet of the heat exchange path at the head end is connected to the gas outlet. The main heat exchanger 20 is capable of cooling the feed gas in the heat exchange path. The multiple separation tanks are arranged in a one-to-one correspondence with the multiple heat exchange paths. The inlet of the separation tank is connected to the outlet of the corresponding heat exchange path, and the gas phase outlet of the separation tank is connected to the inlet of the corresponding heat exchange path of the next-stage separation tank 31. The inlet of the mixed refrigerant compression system 41 is connected to the outlet of the first heat exchange channel 21, and the gas phase outlet of the mixed refrigerant compression system 41 is connected to the inlet of the first heat exchange channel 21. The mixed refrigerant compression system 41 can cool the main heat exchanger 20. The liquid phase outlet of the final stage separation tank is connected to the liquid phase inlet of the LNG distillation column 51, and the liquid phase outlet of the LNG distillation column 51 is connected to the inlet of the second heat exchange channel 22. The outlet of the second heat exchange channel 22 is connected to the LNG storage tank 52. The main heat exchanger 20 can cool the LNG product in the second heat exchange channel 22.

[0048] Among them, in this application, non-condensable gases are mainly H2, CO and N2. The raw gas, that is, the tail gas of Fischer-Tropsch synthesis, mainly contains the following components: H2, CO, CO2, H2O, N2, CH4, C2H4, C2H6, C3H8, C3H6, C4H 10 、C4H8、C5H 12 、C5H 10 、C6H 14 、C6H 12 、C7H 16 、C7H 14 、C8H 18 、C8H 16 The boiling points of the components C1, C2, and C8 are different, and the boiling points are getting higher and higher. LNG products are liquefied natural gas.

[0049] By applying the technical solution of the present application, the mixed refrigerant compression system 41 is connected to the first heat exchange channel 21 of the main heat exchanger 20. The mixed refrigerant compression system 41 can cool the main heat exchanger 20. The raw gas passes through the separation component 10 to remove non-condensable gas, CO2 and moisture, and is then input into the heat exchange flow path at the head end for cooling. The cooled raw gas enters the separation tank for gas-liquid separation, and the liquid phase components flow through the next heat exchange flow path and the separation tank for further separation until the liquid phase components flow to the last stage separation tank for gas-liquid separation. Then the liquid phase components of the last stage separation tank flow into the LNG distillation tower 51 to separate the LNG product. The LNG product is cooled through the second heat exchange channel 22 and then transported to the LNG storage tank 52 for storage. Among them, since the multiple heat exchange paths and the first heat exchange channel 21 are spaced apart along the extension direction of the main heat exchanger 20, the temperature of the heat exchange path at the head end is higher and the temperature of the heat exchange path at the tail end is lower. Such an arrangement can make full use of the difference between the boiling points of the components for separation. Only a separation tank is required, avoiding the use of multiple distillation towers, thereby simplifying the structure of the Fischer-Tropsch synthesis tail gas treatment device, and reducing the equipment investment cost of the Fischer-Tropsch synthesis tail gas treatment device, while reducing the energy consumption of the tail gas treatment process. At the same time, in the present application, non-condensable gas, CO2 and moisture are removed in advance to avoid non-condensable gas, CO2 and moisture from absorbing cold in the heat exchange path and the separation tank, thereby reducing the loss of cold, and further reducing the equipment investment cost of the Fischer-Tropsch synthesis tail gas treatment device.

[0050] In this application, the top pressure of the LNG distillation tower 51 is controlled at 0.5 MPa to 1.0 MPa.

[0051] Specifically, in the present application, the mixed refrigerant in the mixed refrigerant compression system 41 includes nitrogen, methane, propane, ethylene, and isopentane.

[0052] Among them, the main heat exchanger 20 has a third heat exchange channel 24 and a fourth heat exchange channel 25, and the third heat exchange channel 24 and the fourth heat exchange channel 25 are arranged between the first heat exchange channel 21 and the second heat exchange channel 22. The third heat exchange channel 24 is arranged close to the first heat exchange channel 21, and the fourth heat exchange channel 25 is arranged close to the second heat exchange channel 22.

[0053] The Fischer-Tropsch synthesis tail gas treatment unit also includes a nitrogen compression system 42 and a first heat exchanger 61. The inlet of the nitrogen compression system 42 is connected to the outlet of the third heat exchange channel 24, and the outlet of the nitrogen compression system 42 is connected to the inlet of the fourth heat exchange channel 25. The nitrogen compression system 42 can cool the main heat exchanger 20 and the LNG distillation column 51. For ease of description, the heat exchange channels, flow channels, and heat exchange flow paths within the main heat exchanger 20 may all be referred to as streams.

[0054] In this application, other streams in the main heat exchanger 20 can cool the nitrogen in the fourth heat exchange channel 25 , and the nitrogen in the third heat exchange channel 24 can cool other streams in the main heat exchanger 20 .

[0055] With this arrangement, the nitrogen compression system 42 can further cool the main heat exchanger 20, further facilitating the separation of the components in the raw gas.

[0056] The first heat exchanger 61 has a first pipeline and a second pipeline. The inlet of the first pipeline is connected to the gas phase outlet of the LNG distillation tower 51, the liquid phase outlet of the first pipeline is connected to the reflux inlet of the LNG distillation tower 51, the inlet of the second pipeline is connected to the outlet of the fourth heat exchange channel 25, and there is a first connecting pipeline 62 between the inlet of the second pipeline and the outlet of the fourth heat exchange channel 25. A first throttle valve 621 is provided on the first connecting pipeline 62, and the outlet of the second pipeline is connected to the inlet of the third heat exchange channel 24.

[0057] With such arrangement, the nitrogen in the third heat exchange channel 24 is compressed by the nitrogen compression system 42 and then flows into the fourth heat exchange channel 25. The nitrogen in the fourth heat exchange channel 25 will be throttled by the first throttle valve 621, thereby gasifying and generating a large amount of cold energy. The throttled nitrogen at the top of the LNG distillation tower 51 is used as a cold source. The temperature at the top of the LNG distillation tower 51 is -180°C to -190°C. After cooling the LNG distillation tower 51, the nitrogen returns to the inlet of the nitrogen compression system 42 through the third heat exchange channel 24.

[0058] Furthermore, the main heat exchanger 20 further has a fifth heat exchange channel 26 , which is arranged on a side of the heat exchange path away from the first heat exchange channel 21 , and an inlet of the fifth heat exchange channel 26 is connected to the gas outlet.

[0059] The raw gas after removal of non-condensable gas, CO2 and moisture enters the fifth heat exchange channel 26, where it is pre-cooled to -45°C to -50°C by other streams in the main heat exchanger 20.

[0060] When the Fischer-Tropsch synthesis tail gas treatment device is started up, the mixed refrigerant compression system 41 can cool down the main heat exchanger 20 in advance.

[0061] The Fischer-Tropsch synthesis tail gas treatment device also includes a heavy hydrocarbon washing tower 71, the gas phase inlet of the heavy hydrocarbon washing tower 71 is connected to the outlet of the fifth heat exchange channel 26, and the gas phase outlet of the heavy hydrocarbon washing tower 71 is connected to the inlet of the heat exchange flow path at the head end to remove the heavy hydrocarbon components in the raw gas. Among them, in the present application, C4 and above components are heavy hydrocarbon components. The heavy hydrocarbon components will cause the main heat exchanger 20 or the separation tank to be frozen during operation. Therefore, the heavy hydrocarbon washing tower 71 can preferentially remove the heavy hydrocarbon components in the raw gas, avoid freezing of the main heat exchanger 20 or the separation tank, and effectively separate the components in the raw gas while ensuring the safety of the low-temperature fractionation process, thereby improving the utilization rate of the raw gas.

[0062] Specifically, the liquid phase outlet of the separation tank is connected to the washing inlet of the heavy hydrocarbon washing tower 71 to remove heavy hydrocarbon components in the raw gas, and the washing inlet of the heavy hydrocarbon washing tower 71 is located above the gas phase inlet of the heavy hydrocarbon washing tower 71. This arrangement can fully utilize the raw gas and avoid energy waste, while ensuring the washing effect of the gas in the heavy hydrocarbon washing tower 71.

[0063] Furthermore, the Fischer-Tropsch synthesis tail gas treatment unit also includes a deethanizer 72, the liquid phase inlet of which is connected to the liquid phase outlet of the heavy hydrocarbon scrubber 71 to separate the C2 component from the feed gas. This arrangement can recover the C2 component from the feed gas and avoid energy waste.

[0064] Among them, the Fischer-Tropsch synthesis tail gas treatment device also includes a second heat exchanger 63, the second heat exchanger 63 has a third pipeline and a fourth pipeline, the inlet of the third pipeline is connected to the gas phase outlet of the deethanizer 72, the liquid phase outlet of the third pipeline is connected to the reflux inlet of the deethanizer 72, and the gas phase outlet of the third pipeline is used to discharge the C2 component.

[0065] The inlet of the fourth pipeline is connected to the liquid phase outlet of the mixed refrigerant compression system 41, and the outlet of the fourth pipeline is connected to the inlet of the mixed refrigerant compression system 41, and there is a second connecting pipeline 64 between the inlet of the fourth pipeline and the liquid phase outlet of the mixed refrigerant compression system 41, and a second throttle valve 641 is provided on the second connecting pipeline 64.

[0066] In this arrangement, the top of the deethanizer 72 is the C2 component, the mixed refrigerant compression system 41 can pre-cool the mixed refrigerant, and the high-pressure liquid mixed refrigerant is discharged from the liquid phase outlet of the mixed refrigerant compression system 41. The second throttle valve 641 can throttle the high-pressure liquid mixed refrigerant to provide cooling capacity for the third pipeline. The liquid phase outlet of the third pipeline is connected to the reflux inlet of the deethanizer 72. The gas phase outlet of the third pipeline can obtain the gas phase C2 component, and the bottom of the deethanizer 72 can obtain the mixed hydrocarbon product.

[0067] Specifically, a third heat exchanger 65 is provided between the first heat exchange channel 21 and the liquid-phase outlet of the LNG distillation column 51 to cool the mixed refrigerant within the first heat exchange channel 21. Since the liquid-phase components of the LNG distillation column 51 are at a relatively low temperature after being cooled by the nitrogen compression system 42, this arrangement allows the liquid-phase components of the LNG distillation column 51 to cool the mixed refrigerant within the first heat exchange channel 21 through the third heat exchanger 65, fully utilizing the cooling capacity of the liquid-phase components of the LNG distillation column 51 and avoiding cooling capacity waste.

[0068] Furthermore, the third heat exchanger 65 has a fifth pipeline and a sixth pipeline. The inlet of the fifth pipeline is connected to the liquid phase outlet of the LNG distillation tower 51 , and the outlet of the fifth pipeline is connected to the inlet of the second heat exchange channel 22 .

[0069] The first heat exchange channel 21 includes a first flow channel 211 , a second flow channel 212 and a third flow channel 213 .

[0070] The inlet of first flow channel 211 is connected to the gas phase outlet of mixed refrigerant compression system 41, and the outlet of first flow channel 211 is connected to the inlet of the sixth pipeline. The inlet of second flow channel 212 is connected to the outlet of the sixth pipeline. The inlet of third flow channel 213 is connected to the outlet of second flow channel 212, and a third connecting pipeline 66 is provided between the inlet of third flow channel 213 and the outlet of second flow channel 212. Third connecting pipeline 66 is provided with a third throttle valve 661. The outlet of third flow channel 213 is connected to the inlet of mixed refrigerant compression system 41. First flow channel 211, second flow channel 212, and third flow channel 213 are spaced apart along the direction of heat exchange flow path and second heat exchange channel 22.

[0071] With this arrangement, when the mixed refrigerant in the mixed refrigerant compression system 41 circulates, the mixed refrigerant sequentially flows through the gas phase outlet of the mixed refrigerant compression system 41 into the first flow channel 211, the sixth pipeline, and the second flow channel 212, then passes through the third connecting pipeline 66 and the third throttle valve 661, and finally returns to the inlet of the mixed refrigerant compression system 41 through the third flow channel 213. With this arrangement, the liquid phase components of the LNG distillation tower 51 can condense the gas phase mixed refrigerant in the first flow channel 211 into liquid phase mixed refrigerant, thereby allowing the liquid phase mixed refrigerant in the second flow channel 212 to release cooling energy during the throttling process, thereby cooling other streams of the main heat exchanger 20.

[0072] In this application, the temperature of the third heat exchanger 65 is controlled at -170°C to -180°C.

[0073] With this arrangement, the liquid phase outlet at the bottom of the LNG distillation tower 51 obtains LNG product, namely CH4. CH4 is first heated through the fifth pipeline, then enters the second heat exchange channel 22 to be supercooled to -160°C, and then sent out of the main heat exchanger 20 to enter the LNG storage tank 52.

[0074] Specifically, the plurality of heat exchange flow paths include a first heat exchange flow path 231, a second heat exchange flow path 232, and a third heat exchange flow path 233. The first heat exchange flow path 231, the second heat exchange flow path 232, and the third heat exchange flow path 233 are spaced apart and distributed in a direction close to the first heat exchange channel 21. The inlet of the first heat exchange flow path 231 is connected to the gas phase outlet of the heavy hydrocarbon scrubber 71.

[0075] The multiple separation tanks include a primary separation tank 31, a secondary separation tank 32, and a tertiary separation tank 33. The inlet of the primary separation tank 31 is connected to the outlet of the first heat exchange flow path 231, and the gas phase outlet of the primary separation tank 31 is connected to the inlet of the second heat exchange flow path 232. That is, the gas phase components of the heavy hydrocarbon scrubber 71 enter the first heat exchange flow path 231 and are cooled before entering the primary separation tank 31. In the present application, the gas phase components of the heavy hydrocarbon scrubber 71 are cooled to -55°C to -60°C in the first heat exchange flow path 231. The pressure of the primary separation tank 31 is controlled at 3.4MPa to 3.8MPa.

[0076] The inlet of the secondary separator tank 32 is connected to the outlet of the second heat exchange flow path 232, and the gas phase outlet of the secondary separator tank 32 is connected to the inlet of the third heat exchange flow path 233. After the feed gas passes through the primary separator tank 31 for gas-liquid separation, the gaseous component enters the second heat exchange flow path 232, is cooled to -90°C to -100°C, and then enters the secondary separator tank 32 for gas-liquid separation. The pressure of the secondary separator tank 32 is controlled between 3.0 MPa and 3.4 MPa.

[0077] The inlet of the tertiary separator 33 is connected to the outlet of the third heat exchange flow path 233, and the liquid phase outlet of the tertiary separator 33 is connected to the liquid phase inlet of the LNG distillation column 51. The gaseous components obtained at the top of the secondary separator 32 enter the third heat exchange flow path 233 and are cooled to -120°C to -135°C before entering the tertiary separator 33. After entering the tertiary separator 33, the feed gas undergoes gas-liquid separation. The pressure of the tertiary separator 33 is controlled at 2.6 MPa to 3.0 MPa. The gas at the top of the tertiary separator 33 is primarily composed of H2, CO, N2, etc., while the liquid at the bottom is primarily composed of methane.

[0078] Specifically, in the present application, the primary separation tank 31 can separate the liquid phase C3 component and the liquid phase C4 component, and the secondary separation tank 32 can separate the liquid phase C2 component and the liquid phase C3 component.

[0079] Moreover, in the present application, the liquid phase outlet of the first separation tank 31 and the liquid phase outlet of the second separation tank 32 are connected to the washing inlet of the heavy hydrocarbon washing tower 71, so that C4 and above hydrocarbons and components such as benzene in the raw gas can be removed, ensuring the safe operation of the main heat exchanger 20 and the separation tank, and preventing the main heat exchanger 20 and the separation tank from freezing.

[0080] Furthermore, the above structure can fully utilize the differences in boiling points of the components in the raw gas, thereby improving the economic efficiency of the Fischer-Tropsch synthesis tail gas treatment process.

[0081] During the start-up process, that is, when the first-stage separation tank 31 and the second-stage separation tank 32 have not yet produced liquid components, the staff will enter LPG (liquefied petroleum gas) or isopentane through the washing inlet to wash the raw gas of the heavy hydrocarbon washing tower 71, thereby removing C4 and above hydrocarbons and benzene and other components in the raw gas.

[0082] Therefore, in the present application, since a heavy hydrocarbon washing process is used to remove hydrocarbons of C4 and above components carried in the Fischer-Tropsch synthesis tail gas, in the subsequent cryogenic separation part, the condensation separation of C2 and C3 components can be completed by relying on gravity using a traditional separation tank through temperature and pressure control, thereby obtaining CH4. Compared with the operation scheme of using a distillation tower to separate the C2 and C3 components, it will save more equipment investment and energy consumption.

[0083] Furthermore, the main heat exchanger 20 has a sixth heat exchange channel 27 , which is arranged on a side of the second heat exchange channel 22 away from the first heat exchange channel 21 , and an inlet of the sixth heat exchange channel 27 is connected to the gas phase outlet of the first pipeline.

[0084] The Fischer-Tropsch synthesis tail gas treatment device further includes a CO adsorption unit 81 and a H2 adsorption unit 82. In this application, the CO adsorption unit 81 can be referred to as PSA-CO, and the H2 adsorption unit 82 can be referred to as PSA-H2.

[0085] The inlet of the CO adsorption unit 81 is connected to the outlet of the sixth heat exchange channel 27. The first outlet of the CO adsorption unit 81 is used to discharge CO. The gaseous components in the first pipeline, after cooling, enter the sixth heat exchange channel 27, thereby cooling the other streams in the main heat exchanger 20. The gaseous components in the first pipeline enter the sixth heat exchange channel 27, recover their temperature, and are then delivered to the CO adsorption unit 81 to obtain the CO product.

[0086] The inlet of H2 adsorption unit 82 is connected to the second outlet of CO adsorption unit 81. The first outlet of H2 adsorption unit 82 is used to discharge H2, and the second outlet of H2 adsorption unit 82 is connected to the fuel system. The feed gas after CO removal by CO adsorption unit 81 enters H2 adsorption unit 82 to produce H2 product. The remaining desorbed gas is fed into the fuel system for fueling. This configuration fully utilizes the feed gas and avoids energy waste.

[0087] The main heat exchanger 20 has a seventh heat exchange channel 28 , which is disposed on a side of the sixth heat exchange channel 27 away from the second heat exchange channel 22 . The outlet of the seventh heat exchange channel 28 is connected to the inlet of the CO adsorption unit 81 .

[0088] The Fischer-Tropsch synthesis tail gas treatment unit also includes a dehydrogenation tower 73. The gas inlet of dehydrogenation tower 73 is connected to the gas outlet of the tertiary separator 33. The liquid outlet of dehydrogenation tower 73 is connected to the liquid inlet of the LNG distillation tower 51. The gas outlet of dehydrogenation tower 73 is also connected to the inlet of the seventh heat exchange channel 28. The gas from the top of the tertiary separator 33 is fed to dehydrogenation tower 73. The pressure at the top of dehydrogenation tower 73 is controlled between 2 MPa and 2.5 MPa, and the temperature at the top of dehydrogenation tower 73 is controlled between -165°C and -170°C. The gaseous components at the top of dehydrogenation tower 73 enter the seventh heat exchange channel 28, where they cool the other streams from the main heat exchanger 20. The gaseous components at the top of dehydrogenation tower 73 enter the seventh heat exchange channel 28 for reheating, and are then fed to the CO adsorption unit 81 to produce the CO product. The liquid phase outlet of the dehydrogenation tower 73 is connected to the liquid phase inlet of the LNG distillation tower 51. Such an arrangement can reduce energy waste.

[0089] Furthermore, the Fischer-Tropsch synthesis tail gas treatment device also includes a fourth heat exchanger 67, and the fourth heat exchanger 67 has a seventh pipeline and an eighth pipeline.

[0090] The inlet of the seventh pipeline is connected to the gas phase outlet of the dehydrogenation tower 73 , the liquid phase outlet of the seventh pipeline is connected to the reflux inlet of the dehydrogenation tower 73 , and the gas phase outlet of the seventh pipeline is connected to the inlet of the seventh heat exchange channel 28 .

[0091] The inlet of the eighth pipeline is connected to the outlet of the fourth heat exchange channel 25, and there is a fourth connecting pipeline 68 between the inlet of the eighth pipeline and the outlet of the fourth heat exchange channel 25. A fourth throttle valve 681 is provided on the fourth connecting pipeline 68. The outlet of the eighth pipeline is connected to the inlet of the third heat exchange channel 24. The nitrogen compression system 42 can cool the dehydrogenation tower 73.

[0092] With this arrangement, the nitrogen in the third heat exchange channel 24 is compressed by the nitrogen compression system 42 and then flows into the fourth heat exchange channel 25. The nitrogen in the fourth heat exchange channel 25 will be throttled by the first throttle valve 621, thereby gasifying and generating a large amount of cold energy. The throttled nitrogen at the top of the dehydrogenation tower 73 serves as a cold source, thereby cooling the gaseous components in the dehydrogenation tower 73, so that part of the gaseous components in the dehydrogenation tower 73 are liquefied into liquid components, reducing the waste of effective components. The gaseous components flowing out of the gas phase outlet of the seventh pipeline enter the seventh heat exchange channel 28 for reheating and are then sent to the CO adsorption unit 81 to obtain CO products.

[0093] Specifically, the separation assembly 10 includes a membrane separation structure 11 , a deacidification tower 12 , a precooler 13 , a gas-liquid separation tank 14 , an adsorption tower 15 and a drying tower 16 .

[0094] Membrane separation structure 11 has a gas inlet, and its first outlet communicates with the inlet of CO adsorption unit 81 to remove non-condensable gases from the feed gas. Feed gas from upstream is fed into membrane separation structure 11, where the differences in molecular permeability of the selected modules are utilized to achieve initial separation of the components, minimizing the amount of non-condensable gases such as H₂, CO, and N₂ entering the knockout tank and main heat exchanger 20. The cooling capacity required to liquefy the non-condensable gases is greater than that required for CH₄. This configuration reduces the load on the Fischer-Tropsch synthesis tail gas treatment unit.

[0095] Specifically, in the present application, the pressure of the membrane separation structure 11 is controlled at 5.0 MPa to 6.0 MPa, and the temperature is controlled at 55° C. to 65° C. The permeate gas separated by the membrane separation structure 11 is sent to the CO adsorption unit 81 .

[0096] The inlet of deacidification tower 12 is connected to the second outlet of membrane separation structure 11 to remove CO2 from the feed gas. Non-permeate gas separated by membrane separation structure 11 is transported to deacidification tower 12, where the pressure is controlled at 4.5 MPa to 5.0 MPa. Methods used include low-temperature methanol scrubbing, MDEA, NHD, and hot methyl alkali decarbonization to remove CO2 from the feed gas, reducing the CO2 concentration to below 20 ppm.

[0097] The inlet of the precooler 13 is connected to the outlet of the deacidification tower 12. The raw gas passes through the deacidification tower 12 and enters the precooler 13 where it is precooled to 10°C to 20°C. The pressure of the precooler 13 is controlled at 4.3MPa to 4.4MPa, so that most of the saturated water and some heavy hydrocarbons can be condensed.

[0098] The inlet of the gas-liquid separator 14 is connected to the outlet of the precooler 13. The precooled raw gas enters the gas-liquid separator 14 for gas-liquid separation, and the liquid component is transported to the deethanizer 72.

[0099] The inlet of adsorption tower 15 is connected to the gas phase outlet of gas-liquid separator 14 to remove CO2 from the feed gas. The gas phase components separated by gas-liquid separator 14 are transported to adsorption tower 15. The pressure of adsorption tower 15 is controlled at 4.0MPa to 4.3MPa, and CO2 is removed to 5ppm.

[0100] The inlet of drying tower 16 is connected to the outlet of adsorption tower 15. Drying tower 16 has a gas outlet to remove moisture from the feed gas. The pressure in drying tower 16 is controlled at 3.8 MPa to 4.0 MPa, removing water to 1 ppm. This arrangement facilitates the feed gas's entry into the main heat exchanger 20 and separation tank.

[0101] In order to better understand the present application, the Fischer-Tropsch synthesis tail gas treatment process using the Fischer-Tropsch synthesis tail gas treatment device is as follows:

[0102] The raw gas enters the membrane separation structure 11 through the gas inlet to separate the non-condensable gas in the raw gas;

[0103] The non-condensable gas in the feed gas enters the CO adsorption unit 81 through the first outlet of the membrane separation structure 11 to obtain the CO product;

[0104] The raw gas from which the non-condensable gas has been removed enters the deacidification tower 12 through the second outlet of the membrane separation structure 11 to remove CO2 from the raw gas;

[0105] The raw gas from which CO2 has been removed enters the precooler 13 through the outlet of the deacidification tower 12 for precooling;

[0106] The pre-cooled raw gas enters the gas-liquid separation tank 14 through the outlet of the pre-cooler 13 for gas-liquid separation;

[0107] The liquid components in the gas-liquid separation tank 14 enter the deethanizer 72 through the liquid phase outlet of the gas-liquid separation tank 14;

[0108] The gas phase components in the gas-liquid separation tank 14 enter the adsorption tower 15 through the gas phase outlet of the gas-liquid separation tank 14 and the inlet of the adsorption tower 15 to remove CO2 in the raw gas;

[0109] The raw gas from the adsorption tower 15 enters the drying tower 16 through the outlet of the adsorption tower 15 and the inlet of the drying tower 16 to remove moisture from the raw gas;

[0110] The gaseous components of the drying tower 16 enter the fifth heat exchange channel 26 through the gas outlet of the drying tower 16 for cooling;

[0111] The raw gas in the fifth heat exchange channel 26 enters the heavy hydrocarbon washing tower 71 through the outlet of the fifth heat exchange channel 26 and the gas phase inlet of the heavy hydrocarbon washing tower 71;

[0112] The liquid components in the heavy hydrocarbon washing tower 71 enter the deethanizer 72 through the liquid phase outlet of the heavy hydrocarbon washing tower 71 and the liquid phase inlet of the deethanizer 72 to obtain gas phase C2 and mixed hydrocarbon products;

[0113] The gaseous components in the heavy hydrocarbon scrubber 71 enter the first heat exchange flow path 231 through the gas phase outlet of the heavy hydrocarbon scrubber 71 and the inlet of the first heat exchange flow path 231. Other streams in the main heat exchanger 20 cool the feed gas in the first heat exchange flow path 231.

[0114] The raw gas from the first heat exchange flow path 231 enters the primary separation tank 31 for gas-liquid separation;

[0115] The liquid components in the primary separation tank 31 enter the heavy hydrocarbon washing tower 71 to wash the raw gas in the heavy hydrocarbon washing tower 71;

[0116] The gaseous components in the primary separation tank 31 enter the second heat exchange flow path 232 for cooling;

[0117] The raw gas in the second heat exchange flow path 232 enters the secondary separation tank 32 for gas-liquid separation;

[0118] The liquid components in the secondary separation tank 32 enter the heavy hydrocarbon washing tower 71 to wash the raw gas in the heavy hydrocarbon washing tower 71;

[0119] The gaseous components in the secondary separation tank 32 enter the third heat exchange flow path 233 for cooling;

[0120] The raw gas in the third heat exchange flow path 233 enters the third-stage separation tank 33 for gas-liquid separation;

[0121] The gas phase components in the tertiary separation tank 33 enter the dehydrogenation tower 73 for gas-liquid separation;

[0122] The liquid components in the tertiary separation tank 33 enter the LNG distillation tower 51 to obtain liquid CH4;

[0123] Liquid CH4 enters the fifth pipeline of the third heat exchanger 65 and the second heat exchange channel 22 and flows into the LNG storage tank 52;

[0124] The mixed refrigerant sequentially flows through the gas phase outlet of the mixed refrigerant compression system 41 into the first flow channel 211, the sixth pipeline of the third heat exchanger 65, the second flow channel 212, then passes through the third connecting pipeline 66 and the third throttle valve 661, and finally returns to the inlet of the mixed refrigerant compression system 41 through the third flow channel 213;

[0125] The gaseous components in the LNG distillation tower 51 are passed into the first pipeline of the first heat exchanger 61 for cooling;

[0126] The gaseous components in the first pipeline of the first heat exchanger 61 enter the sixth heat exchange channel 27 and then flow into the CO adsorption unit 81 after being restored to normal temperature.

[0127] The liquid phase components in the first pipeline of the first heat exchanger 61 flow back into the LNG distillation tower 51;

[0128] The nitrogen in the nitrogen compression system 42 passes through the outlet of the nitrogen compression system 42, the fourth heat exchange channel 25, the second pipeline of the first heat exchanger 61, then passes through the first connecting pipeline 62 and the first throttle valve 621, and finally returns to the inlet of the nitrogen compression system 42 through the third heat exchange channel 24;

[0129] The liquid components in the dehydrogenation tower 73 enter the LNG distillation tower 51;

[0130] The gaseous components in the dehydrogenation tower 73 enter the seventh pipeline of the fourth heat exchanger 67 for cooling;

[0131] The liquid components in the seventh pipeline of the fourth heat exchanger 67 are refluxed into the dehydrogenation tower 73;

[0132] The gaseous components in the seventh pipeline of the fourth heat exchanger 67 enter the seventh heat exchange channel 28 and then flow into the CO adsorption unit 81 after being reheated.

[0133] The nitrogen in the nitrogen compression system 42 passes through the outlet of the nitrogen compression system 42, the fourth heat exchange channel 25, the eighth pipeline of the fourth heat exchanger 67, then passes through the fourth connecting pipeline 68 and the fourth throttle valve 681, and finally returns to the inlet of the nitrogen compression system 42 through the third heat exchange channel 24;

[0134] The gaseous components from the deethanizer 72 flow into the third pipeline of the second heat exchanger 63 for cooling;

[0135] The liquid components in the third pipeline are refluxed into the deethanizer 72;

[0136] The gas phase components in the third pipeline are discharged to C2;

[0137] The liquid phase component of the mixed refrigerant compression system 41 enters the fourth pipeline of the second heat exchanger 63 through the second connecting pipeline 64 and the second throttle valve 641;

[0138] The gaseous mixed refrigerant in the fourth pipeline flows back to the inlet of the mixed refrigerant compression system 41;

[0139] The gases other than CO in the CO adsorption unit 81 enter the H2 adsorption unit 82 to obtain H2 product;

[0140] The gases other than H 2 in the H 2 adsorption unit 82 enter the fuel system for combustion.

[0141] 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.

[0142] Unless otherwise specifically stated, the relative arrangement of the parts and steps, numerical expressions and 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 accompanying drawings are not drawn according to actual proportional relationships. The technology, methods and equipment known to those of ordinary skill in the relevant art may not be discussed in detail, but in appropriate cases, the technology, methods and equipment should be considered as a part of the specification. In all examples shown and discussed here, any specific value should be interpreted as being merely exemplary, rather than as a limitation. Therefore, other examples of the exemplary embodiments can have different values. It should be noted that similar numbers and letters represent similar items in the following drawings, and therefore, once an item is defined in an accompanying drawing, it does not need to be further discussed in subsequent drawings.

[0143] 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 device 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.

[0144] 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.

[0145] 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.

[0146] 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 shall be included within the scope of protection of the present invention.

Claims

1. A Fischer-Tropsch synthesis tail gas treatment device, characterized in that: The Fischer-Tropsch synthesis tail gas treatment device comprises: A separation component (10), wherein the separation component (10) has a gas inlet and a gas outlet, the gas inlet is used to transport raw gas, and the separation component (10) is capable of removing non-condensable gas, CO2 and moisture in the raw gas; A main heat exchanger (20), the main heat exchanger (20) having a first heat exchange channel (21), a second heat exchange channel (22) and a plurality of heat exchange flow paths, the plurality of heat exchange flow paths, the first heat exchange channel (21) and the second heat exchange channel (22) being spaced apart along the extension direction of the main heat exchanger (20), the inlet of the heat exchange flow path at the head end being connected to the gas outlet, and the main heat exchanger (20) being capable of cooling the raw gas in the heat exchange flow path; A plurality of separation tanks are provided in a one-to-one correspondence with the plurality of heat exchange flow paths, the inlet of the separation tank is connected to the outlet of the corresponding heat exchange flow path, and the gas phase outlet of the separation tank is connected to the inlet of the heat exchange flow path corresponding to the separation tank of the next stage; a mixed refrigerant compression system (41), wherein the inlet of the mixed refrigerant compression system (41) is communicated with the outlet of the first heat exchange channel (21), and the gas phase outlet of the mixed refrigerant compression system (41) is communicated with the inlet of the first heat exchange channel (21), and the mixed refrigerant compression system (41) is capable of cooling the main heat exchanger (20); An LNG distillation tower (51) and an LNG storage tank (52) are provided, wherein the liquid phase outlet of the last stage separation tank is connected to the liquid phase inlet of the LNG distillation tower (51), the liquid phase outlet of the LNG distillation tower (51) is connected to the inlet of the second heat exchange channel (22), the outlet of the second heat exchange channel (22) is connected to the LNG storage tank (52), and the main heat exchanger (20) is capable of cooling the LNG product in the second heat exchange channel (22).

2. The Fischer-Tropsch synthesis tail gas treatment device according to claim 1, characterized in that: The main heat exchanger (20) has a third heat exchange channel (24) and a fourth heat exchange channel (25), the third heat exchange channel (24) and the fourth heat exchange channel (25) are arranged between the first heat exchange channel (21) and the second heat exchange channel (22), the third heat exchange channel (24) is arranged close to the first heat exchange channel (21), and the fourth heat exchange channel (25) is arranged close to the second heat exchange channel (22), and the Fischer-Tropsch synthesis tail gas treatment device further includes: a nitrogen compression system (42), wherein the inlet of the nitrogen compression system (42) is in communication with the outlet of the third heat exchange channel (24), and the outlet of the nitrogen compression system (42) is in communication with the inlet of the fourth heat exchange channel (25), and the nitrogen compression system (42) is capable of cooling the main heat exchanger (20) and the LNG distillation column (51); A first heat exchanger (61), the first heat exchanger (61) having a first pipeline and a second pipeline, the inlet of the first pipeline being connected to the gas phase outlet of the LNG distillation tower (51), the liquid phase outlet of the first pipeline being connected to the reflux inlet of the LNG distillation tower (51), the inlet of the second pipeline being connected to the outlet of the fourth heat exchange channel (25), and a first connecting pipeline (62) being provided between the inlet of the second pipeline and the outlet of the fourth heat exchange channel (25), the first connecting pipeline (62) being provided with a first throttle valve (621), and the outlet of the second pipeline being connected to the inlet of the third heat exchange channel (24).

3. The Fischer-Tropsch synthesis tail gas treatment device according to claim 2, characterized in that: The main heat exchanger (20) further comprises a fifth heat exchange channel (26), the fifth heat exchange channel (26) being arranged on a side of the heat exchange flow path away from the first heat exchange channel (21), the inlet of the fifth heat exchange channel (26) being in communication with the gas outlet, and the Fischer-Tropsch synthesis tail gas treatment device further comprising: A heavy hydrocarbon washing tower (71), the gas phase inlet of the heavy hydrocarbon washing tower (71) is connected to the outlet of the fifth heat exchange channel (26), and the gas phase outlet of the heavy hydrocarbon washing tower (71) is connected to the inlet of the heat exchange flow path at the head end to remove heavy hydrocarbon components in the raw gas.

4. The Fischer-Tropsch synthesis tail gas treatment device according to claim 3, characterized in that: The liquid phase outlet of the separation tank is connected to the washing inlet of the heavy hydrocarbon washing tower (71) to remove the heavy hydrocarbon components in the raw gas, and the washing inlet of the heavy hydrocarbon washing tower (71) is located above the gas phase inlet of the heavy hydrocarbon washing tower (71).

5. The Fischer-Tropsch synthesis tail gas treatment device according to claim 3, characterized in that: The Fischer-Tropsch synthesis tail gas treatment device also includes: A deethanizer (72), wherein the liquid phase inlet of the deethanizer (72) is connected to the liquid phase outlet of the heavy hydrocarbon washing tower (71) to separate the C2 component in the raw gas.

6. The Fischer-Tropsch synthesis tail gas treatment device according to claim 5, characterized in that: The Fischer-Tropsch synthesis tail gas treatment device also includes: A second heat exchanger (63), wherein the second heat exchanger (63) has a third pipeline and a fourth pipeline, wherein the inlet of the third pipeline is connected to the gas phase outlet of the deethanizer (72), and the liquid phase outlet of the third pipeline is connected to the reflux inlet of the deethanizer (72), and the gas phase outlet of the third pipeline is used to discharge the C2 component; the inlet of the fourth pipeline is connected to the liquid phase outlet of the mixed refrigerant compression system (41), and the outlet of the fourth pipeline is connected to the inlet of the mixed refrigerant compression system (41), and a second connecting pipeline (64) is provided between the inlet of the fourth pipeline and the liquid phase outlet of the mixed refrigerant compression system (41), and a second throttle valve (641) is provided on the second connecting pipeline (64).

7. The Fischer-Tropsch synthesis tail gas treatment device according to claim 1, characterized in that: A third heat exchanger (65) is provided between the first heat exchange channel (21) and the liquid phase outlet of the LNG distillation tower (51) to cool the mixed refrigerant in the first heat exchange channel (21).

8. The Fischer-Tropsch synthesis tail gas treatment device according to claim 7, characterized in that: The third heat exchanger (65) has a fifth pipeline and a sixth pipeline, the inlet of the fifth pipeline is connected to the liquid phase outlet of the LNG distillation column (51), the outlet of the fifth pipeline is connected to the inlet of the second heat exchange channel (22), and the first heat exchange channel (21) includes: a first flow channel (211), wherein the inlet of the first flow channel (211) is connected to the gas phase outlet of the mixed refrigerant compression system (41), and the outlet of the first flow channel (211) is connected to the inlet of the sixth pipeline; a second flow channel (212), the inlet of the second flow channel (212) being in communication with the outlet of the sixth pipeline; A third flow channel (213), the inlet of the third flow channel (213) is connected to the outlet of the second flow channel (212), and a third connecting pipeline (66) is provided between the inlet of the third flow channel (213) and the outlet of the second flow channel (212), and a third throttle valve (661) is provided on the third connecting pipeline (66), the outlet of the third flow channel (213) is connected to the inlet of the mixed refrigerant compression system (41), and the first flow channel (211), the second flow channel (212) and the third flow channel (213) are spaced apart and distributed along the direction of the heat exchange flow channel and the second heat exchange channel (22).

9. The Fischer-Tropsch synthesis tail gas treatment device according to claim 3, characterized in that: The plurality of heat exchange flow paths include a first heat exchange flow path (231), a second heat exchange flow path (232), and a third heat exchange flow path (233); the first heat exchange flow path (231), the second heat exchange flow path (232), and the third heat exchange flow path (233) are spaced apart in a direction close to the first heat exchange channel (21); and the inlet of the first heat exchange flow path (231) is connected to the gas phase outlet of the heavy hydrocarbon washing tower (71); The plurality of separation tanks include a first-stage separation tank (31), a second-stage separation tank (32) and a third-stage separation tank (33), wherein the inlet of the first-stage separation tank (31) is connected to the outlet of the first heat exchange flow path (231), the gas phase outlet of the first-stage separation tank (31) is connected to the inlet of the second heat exchange flow path (232), the inlet of the second-stage separation tank (32) is connected to the outlet of the second heat exchange flow path (232), the gas phase outlet of the second-stage separation tank (32) is connected to the inlet of the third heat exchange flow path (233), the inlet of the third-stage separation tank (33) is connected to the outlet of the third heat exchange flow path (233), and the liquid phase outlet of the third-stage separation tank (33) is connected to the liquid phase inlet of the LNG distillation tower (51).

10. The Fischer-Tropsch synthesis tail gas treatment device according to claim 9, characterized in that: The main heat exchanger (20) has a sixth heat exchange channel (27), the sixth heat exchange channel (27) is arranged on a side of the second heat exchange channel (22) away from the first heat exchange channel (21), the inlet of the sixth heat exchange channel (27) is connected to the gas phase outlet of the first pipeline, and the Fischer-Tropsch synthesis tail gas treatment device further includes: a CO adsorption unit (81), wherein the inlet of the CO adsorption unit (81) is in communication with the outlet of the sixth heat exchange channel (27), and the first outlet of the CO adsorption unit (81) is used to discharge CO; An H2 adsorption unit (82) has an inlet connected to the second outlet of the CO adsorption unit (81), a first outlet of the H2 adsorption unit (82) for discharging H2, and a second outlet of the H2 adsorption unit (82) for communicating with a fuel system.

11. The Fischer-Tropsch synthesis tail gas treatment device according to claim 10, characterized in that: The main heat exchanger (20) has a seventh heat exchange channel (28), the seventh heat exchange channel (28) is arranged on a side of the sixth heat exchange channel (27) away from the second heat exchange channel (22), the outlet of the seventh heat exchange channel (28) is connected to the inlet of the CO adsorption unit (81), and the Fischer-Tropsch synthesis tail gas treatment device further includes: A dehydrogenation tower (73), wherein the gas phase inlet of the dehydrogenation tower (73) is connected to the gas phase outlet of the tertiary separation tank (33), the liquid phase outlet of the dehydrogenation tower (73) is connected to the liquid phase inlet of the LNG distillation tower (51), and the gas phase outlet of the dehydrogenation tower (73) is connected to the inlet of the seventh heat exchange channel (28).

12. The Fischer-Tropsch synthesis tail gas treatment device according to claim 11, characterized in that: The Fischer-Tropsch synthesis tail gas treatment device also includes: A fourth heat exchanger (67), the fourth heat exchanger (67) having a seventh pipeline and an eighth pipeline, the inlet of the seventh pipeline being connected to the gas phase outlet of the dehydrogenation tower (73), the liquid phase outlet of the seventh pipeline being connected to the reflux inlet of the dehydrogenation tower (73), the gas phase outlet of the seventh pipeline being connected to the inlet of the seventh heat exchange channel (28), the inlet of the eighth pipeline being connected to the outlet of the fourth heat exchange channel (25), and a fourth connecting pipeline (68) being provided between the inlet of the eighth pipeline and the outlet of the fourth heat exchange channel (25), the fourth connecting pipeline (68) being provided with a fourth throttle valve (681), the outlet of the eighth pipeline being connected to the inlet of the third heat exchange channel (24), and the nitrogen compression system (42) being capable of cooling the dehydrogenation tower (73).

13. The Fischer-Tropsch synthesis tail gas treatment device according to claim 10, characterized in that: The separation assembly (10) comprises: A membrane separation structure (11), wherein the membrane separation structure (11) has the gas inlet, and a first outlet of the membrane separation structure (11) is connected to the inlet of the CO adsorption unit (81) to remove non-condensable gas in the raw gas; an acid removal tower (12), wherein the inlet of the acid removal tower (12) is connected to the second outlet of the membrane separation structure (11) to remove CO2 in the feed gas; a precooler (13), wherein the inlet of the precooler (13) is connected to the outlet of the deacidification tower (12); a gas-liquid separation tank (14), wherein the inlet of the gas-liquid separation tank (14) is in communication with the outlet of the precooler (13); an adsorption tower (15), wherein the inlet of the adsorption tower (15) is connected to the gas phase outlet of the gas-liquid separation tank (14) to remove CO2 in the raw gas; A drying tower (16), wherein the inlet of the drying tower (16) is connected to the outlet of the adsorption tower (15), and the drying tower (16) has the gas outlet to remove moisture in the raw gas.

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