Fischer-Tropsch synthesis tail gas treatment device

Abstract

The invention provides a Fischer-Tropsch synthesis tail gas treatment device, which comprises: a separation assembly having a gas inlet and a gas outlet; the main heat exchanger is provided with a first heat exchange channel, a second heat exchange channel and a plurality of heat exchange flow paths, and an inlet of the heat exchange flow path at the head end communicates with the gas outlet; the inlets of the separation tanks are communicated with the outlets of the corresponding heat exchange flow paths, and the gas phase outlets of the separation tanks are communicated with the inlets of the heat exchange flow paths corresponding to the next-stage separation tanks; an inlet of the mixed refrigerant compression system communicates with an outlet of the first heat exchange channel, and a gas phase outlet communicates with an inlet of the first heat exchange channel; the liquid phase outlet of the last-stage separation tank is communicated with the liquid phase inlet of the LNG rectifying tower, the liquid phase outlet of the LNG rectifying tower is communicated with the inlet of the second heat exchange channel, and the outlet of the second heat exchange channel is communicated with the LNG storage tank. By means of the technical scheme, the problem that in the prior art, a Fischer-Tropsch synthesis tail gas treatment device is complex in structure can be solved.

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 is a method of indirectly synthesizing oil products using coal, natural gas, etc. as raw materials. It uses a catalyst to convert synthesis gas (H2+CO) into heavy oil, light oil, wax, low-carbon hydrocarbons, etc. During the Fischer-Tropsch synthesis reaction, in addition to the above products, a large amount of Fischer-Tropsch synthesis tail gas will also be produced. The Fischer-Tropsch synthesis tail gas mainly includes unreacted hydrogen, carbon monoxide, nitrogen, and 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, convert the tail gas into hydrogen-rich gas with a higher calorific value to generate electricity; second, recover the hydrocarbons in the tail gas and send it to a boiler to burn the by-product steam; third, discharge part of the tail gas, separate the low-carbon hydrocarbons from the remaining tail gas, and then convert the hydrocarbons in the tail gas into synthesis gas through conversion reactions, oxidation, etc., and return it to the Fischer-Tropsch synthesis reactor; fourth, separate 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 has poor economic efficiency. The third solution cracks the hydrocarbons generated by the Fischer-Tropsch synthesis reaction into synthesis gas, which has low energy utilization. Therefore, in the prior art, the fourth treatment method is usually used to recover hydrogen, methane, carbon monoxide, low-carbon hydrocarbons and other products from the Fischer-Tropsch synthesis tail gas by low-temperature fractionation, which will greatly improve the economic value of the Fischer-Tropsch synthesis tail gas and improve the comprehensive energy utilization efficiency of the entire coal indirect liquefaction device.

[0005] In the prior art, 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, the patent document with application number 201910952440.X provides a Fischer-Tropsch synthesis tail gas recovery and utilization system process, which first purifies the Fischer-Tropsch synthesis tail gas through water washing, decarbonization, alkali washing and other processes, and then sends it to a deep cold separation system to cool and liquefy the purified Fischer-Tropsch synthesis tail gas, recover carbon 2, carbon 3 and heavier components; condense and liquefy the methane in the tail gas to produce LNG products; purify hydrogen and carbon monoxide through a PSA device, and increase the pressure of the analyzed gas and merge it into the fuel gas pipeline network. In addition, the Fischer-Tropsch synthesis tail gas recovery and utilization system includes distillation towers such as a demethanizer, a deethanizer, a depropanizer, a debutanizer, and a denitrogenation tower, which results in a complex structure of the Fischer-Tropsch synthesis tail gas recovery and utilization system, large equipment investment and complex equipment layout. Summary of the invention

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

[0008] The present invention provides a Fischer-Tropsch synthesis tail gas treatment device, which comprises: 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, which are arranged one-to-one corresponding to the plurality of heat exchange flow paths, and the inlet of the separation tanks 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; a 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] Further, 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 a first connecting pipeline is provided 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 a side of the heat exchange 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 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 feed 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, and 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 a second connecting pipeline is provided between the inlet of the fourth pipeline and the liquid phase outlet of the mixed refrigerant compression system, and a second throttle valve is arranged 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, and 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 in 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, 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 a 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 three-stage 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 a fourth connecting pipeline is provided 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, and 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 set of heat exchange flow paths and separation tanks for separation again until the liquid phase components flow to the last stage separation tank for gas-liquid separation, and 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 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 is lower. Such an arrangement can make full use of the difference between the boiling points of each component for separation, and 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, and at the same time 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 drawings constituting a part of the present application are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the 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. A 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. The 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. The fourth heat exchanger;

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

[0044] 71. Heavy hydrocarbon washing tower; 72. Deethanizer; 73. Dehydrogenation tower;

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

[0046] The following will be combined with the 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 described embodiments 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 by no means 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 creative work 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 component 10, a main heat exchanger 20, a plurality of separation tanks, a mixed refrigerant compression system 41, an LNG distillation tower 51 and an LNG storage tank 52. The separation component 10 has a gas inlet and a gas outlet, the gas inlet is used to transport the raw gas, and the separation component 10 can remove non-condensable gas, CO2 and moisture in the raw gas. The main heat exchanger 20 has a first heat exchange channel 21, a second heat exchange channel 22 and a plurality of heat exchange flow paths, and the plurality of heat exchange flow paths, the first heat exchange channel 21 and the second heat exchange channel 22 are spaced and distributed along the extension direction of the main heat exchanger 20, and the inlet of the heat exchange flow path at the head end is connected to the gas outlet, and the main heat exchanger 20 can cool the raw gas of the heat exchange flow path. Multiple separation tanks are arranged in a one-to-one correspondence with multiple 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 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 last stage separation tank is connected to the liquid phase inlet of the LNG distillation tower 51, and 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 can cool the LNG product of the second heat exchange channel 22.

[0048] Among them, in this application, non-condensable gases are mainly H2, CO and N2. The raw gas, i.e. 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 , C1, C2 to C8 have different boiling points, 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, and 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 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 set of heat exchange flow paths and separation tanks for separation again until the liquid phase components flow to the last stage separation tank for gas-liquid separation, and 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 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 end is lower. Such an arrangement can make full use of the difference between the boiling points of each component for separation, and 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, and at the same time 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] Among them, in the present 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 device 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 tower 51. For the convenience of description, the heat exchange channels, flow channels, and heat exchange flow paths in the main heat exchanger 20 can all be referred to as streams.

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

[0055] With such 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, and 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 top of the LNG distillation tower 51 uses the throttled nitrogen 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 also has a fifth heat exchange channel 26 , which is disposed on a side of the heat exchange flow path away from the first heat exchange channel 21 , and an inlet of the fifth heat exchange channel 26 is connected to a gas outlet.

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

[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 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. Such an arrangement can make full use of the raw gas, avoid energy waste, and at the same time ensure the washing effect of the gas in the heavy hydrocarbon washing tower 71.

[0063] Furthermore, the Fischer-Tropsch synthesis tail gas treatment device further includes a deethanizer 72, 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. In this way, the C2 component in the raw gas can be recovered to 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, 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 arranged on the second connecting pipeline 64.

[0066] With such arrangement, the top of the deethanizer 72 is the C2 component, the mixed refrigerant compression system 41 can pre-cool the mixed refrigerant, 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 a 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 tower 51 to cool the mixed refrigerant in the first heat exchange channel 21. Since the temperature of the liquid phase component of the LNG distillation tower 51 after cooling by the nitrogen compression system 42 is relatively low, in this configuration, the liquid phase component of the LNG distillation tower 51 can cool the mixed refrigerant in the first heat exchange channel 21 through the third heat exchanger 65, and the cooling capacity of the liquid phase component of the LNG distillation tower 51 can be fully utilized to avoid the waste of cooling capacity.

[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 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. The inlet of the second flow channel 212 is connected to the outlet of the sixth pipeline. The inlet of the third flow channel 213 is connected to the outlet of the second flow channel 212, and there is a third connecting pipeline 66 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 path and the second heat exchange channel 22.

[0071] With such arrangement, when the mixed refrigerant of the mixed refrigerant compression system 41 is circulated, the mixed refrigerant sequentially flows into the first flow channel 211, the sixth pipeline, the second flow channel 212 through the gas phase outlet of the mixed refrigerant compression system 41, 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 such arrangement, the liquid phase component of the LNG distillation tower 51 can condense the gas phase mixed refrigerant in the first flow channel 211 into a liquid phase mixed refrigerant, so that the liquid phase mixed refrigerant in the second flow channel 212 releases cold energy during the throttling process, so that the other streams of the main heat exchanger 20 can be cooled.

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

[0073] With such arrangement, the liquid phase outlet at the bottom of the LNG distillation tower 51 obtains the LNG product, namely CH4. The CH4 is first heated by the fifth pipeline, then enters the second heat exchange channel 22 to be supercooled to -160°C, and then is sent out of the main heat exchanger 20 and enters 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, which are spaced apart 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 washing tower 71.

[0075] The plurality of 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 component of the heavy hydrocarbon washing tower 71 enters the first heat exchange flow path 231 and is cooled before entering the primary separation tank 31. In the present application, the gas phase component of the heavy hydrocarbon washing tower 71 is 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 separation tank 32 is connected to the outlet of the second heat exchange flow path 232, and the gas phase outlet of the secondary separation tank 32 is connected to the inlet of the third heat exchange flow path 233. After the raw gas passes through the primary separation tank 31 for gas-liquid separation, the gas phase component enters the second heat exchange flow path 232 and is cooled to -90°C to -100°C before entering the secondary separation tank 32 for gas-liquid separation. The pressure of the secondary separation tank 32 is controlled at 3.0MPa to 3.4MPa.

[0077] The inlet of the tertiary separation tank 33 is connected to the outlet of the third heat exchange flow path 233, and the liquid phase outlet of the tertiary separation tank 33 is connected to the liquid phase inlet of the LNG distillation tower 51. The gas phase component obtained at the top of the secondary separation tank 32 enters the third heat exchange flow path 233 and is cooled to -120°C to -135°C before entering the tertiary separation tank 33. After the raw gas enters the tertiary separation tank 33, gas-liquid separation is performed. The pressure of the tertiary separation tank 33 is controlled at 2.6MPa to 3.0MPa. The main components of the gas at the top of the tertiary separation tank 33 are H2, CO, N2, etc., and the main component of the liquid at the bottom is 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 difference in boiling points of various 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 separation tank 31 and the second 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 the heavy hydrocarbon washing process is used to remove the C4 and above hydrocarbons carried in the Fischer-Tropsch synthesis tail gas, the temperature and pressure can be controlled in the subsequent deep cold separation part by using a traditional separation tank to rely on gravity to complete the condensation separation of the C2 and C3 components, thereby obtaining CH4. Compared with the operation scheme of using a distillation tower to separate the C2 and C3 components, it will save equipment investment and energy consumption.

[0083] Furthermore, the main heat exchanger 20 has a sixth heat exchange channel 27 , which is disposed 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 a gas phase outlet of the first pipeline.

[0084] The Fischer-Tropsch synthesis tail gas treatment device also 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, and the first outlet of the CO adsorption unit 81 is used to discharge CO. The gas phase components after cooling in the first pipeline enter the sixth heat exchange channel 27, so that other streams of the main heat exchanger 20 can be cooled. The gas phase components of the first pipeline enter the sixth heat exchange channel 27 and are reheated and then sent to the CO adsorption unit 81 to obtain CO products.

[0086] The inlet of the H2 adsorption unit 82 is connected to the second outlet of the CO adsorption unit 81. The first outlet of the H2 adsorption unit 82 is used to discharge H2, and the second outlet of the H2 adsorption unit 82 is used to communicate with the fuel system. The raw gas after CO is removed by the CO adsorption unit 81 enters the H2 adsorption unit 82 to obtain H2 products, and the remaining analytical gas is sent to the fuel system for fuel. Such a setting can make full use of the raw gas and avoid 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 , and an outlet of the seventh heat exchange channel 28 is connected to an inlet of the CO adsorption unit 81 .

[0088] The Fischer-Tropsch synthesis tail gas treatment device also includes a dehydrogenation tower 73, 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. The gas phase at the top of the tertiary separation tank 33 is sent to the dehydrogenation tower 73, the pressure at the top of the dehydrogenation tower 73 is controlled at 2MPa to 2.5MPa, and the temperature at the top of the dehydrogenation tower 73 is controlled at -165°C to -170°C. The gas phase components at the top of the dehydrogenation tower 73 enter the seventh heat exchange channel 28, and the gas phase components at the top of the dehydrogenation tower 73 can cool down other streams of the main heat exchanger 20. The gas phase components at the top of the dehydrogenation tower 73 enter the seventh heat exchange channel 28 for reheating and are sent to the CO adsorption unit 81 to obtain CO products. 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, and 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, and the nitrogen compression system 42 can cool the dehydrogenation tower 73.

[0092] In 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, so that it is gasified to generate a large amount of cold. The top of the dehydrogenation tower 73 uses the throttled nitrogen as a cold source, so that the gas phase components in the dehydrogenation tower 73 can be cooled, so that part of the gas phase components in the dehydrogenation tower 73 are liquefied into liquid phase components, reducing the waste of effective components. The gas phase components flowing out of the gas phase outlet of the seventh pipeline enter the seventh heat exchange channel 28 for reheating and are sent to the CO adsorption unit 81 to obtain CO products.

[0093] Specifically, the separation component 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] The membrane separation structure 11 has a gas inlet, and the 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. The upstream raw gas is sent to the membrane separation structure 11, and the difference in the permeability of each molecule of the selected module is used to achieve the initial separation of the components, and the amount of non-condensable gases such as H2, CO, and N2 entering the separation tank and the main heat exchanger 20 is minimized. The cooling capacity required for the liquefaction of non-condensable gas is greater than the cooling capacity required for CH4. Such an arrangement can reduce the load of the Fischer-Tropsch synthesis tail gas treatment device.

[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 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 the deacidification tower 12 is connected to the second outlet of the membrane separation structure 11 to remove CO2 in the raw gas. The non-permeate gas separated by the membrane separation structure 11 is transported to the deacidification tower 12, and the pressure of the deacidification tower 12 is controlled at 4.5MPa to 5.0MPa. The selected methods include low-temperature methanol washing, MDEA, NHD, hot methyl alkali decarbonization, etc., to remove CO2 in the raw gas, so that the CO2 concentration is less than 20ppm.

[0097] The inlet of the precooler 13 is connected to the outlet of the deacidification tower 12. The raw gas enters the precooler 13 through the deacidification tower 12 and 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 separation tank 14 is connected to the outlet of the precooler 13. The precooled raw gas enters the gas-liquid separation tank 14 for gas-liquid separation, and the liquid component is transported to the deethanizer 72.

[0099] 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. The gas phase components separated by the gas-liquid separation tank 14 are transported to the adsorption tower 15, and the pressure of the adsorption tower 15 is controlled at 4.0MPa to 4.3MPa to remove CO2 to 5ppm.

[0100] The inlet of the drying tower 16 is connected to the outlet of the adsorption tower 15, and the drying tower 16 has a gas outlet to remove moisture from the raw gas. The pressure of the drying tower 16 is controlled at 3.8MPa to 4.0MPa to remove water to 1ppm. This arrangement facilitates the raw gas to enter the main heat exchanger 20 and the separation tank for separation.

[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:

[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 is removed enters the deacidification tower 12 through the second outlet of the membrane separation structure 11 to remove CO2 in 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 gas phase components of the drying tower 16 enter the fifth heat exchange channel 26 through the gas outlet of the drying tower 16 to be cooled;

[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 phase 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 gas phase components in the heavy hydrocarbon washing tower 71 enter the first heat exchange flow path 231 through the gas phase outlet of the heavy hydrocarbon washing tower 71 and the inlet of the first heat exchange flow path 231, and other streams in the main heat exchanger 20 cool down the feed gas in the first heat exchange flow path 231;

[0114] The raw gas of 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 gas phase 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 gas phase 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 third-stage separation tank 33 enter the dehydrogenation tower 73 for gas-liquid separation;

[0122] The liquid components in the third-stage 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 flows sequentially 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 gas phase components in the LNG distillation tower 51 are passed into the first pipeline of the first heat exchanger 61 for cooling;

[0126] The gas phase components in the first pipeline of the first heat exchanger 61 enter the sixth heat exchange channel 27 for reheating and then flow into the CO adsorption unit 81;

[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, and 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 gas phase 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 gas phase 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, and 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 gas phase components of the deethanizer 72 flow into the third pipeline of the second heat exchanger 63 to be cooled;

[0135] The liquid phase 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 gas phase 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 products;

[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, it indicates the presence of features, steps, operations, devices, components and / or combinations thereof.

[0142] Unless otherwise specifically stated, the relative arrangement, numerical expressions and numerical values ​​of the parts and steps set forth in these embodiments do not limit the scope of the present invention. Meanwhile, 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 the actual proportional relationship. The technology, method and equipment known to those of ordinary skill in the relevant art may not be discussed in detail, but in appropriate cases, the technology, method 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 exemplary embodiments may have different values. It should be noted that similar reference numerals and letters represent similar items in the following drawings, and therefore, once a certain 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 is necessary to understand that the directions or positional relationships indicated by directional words such as "front, back, up, down, left, right", "lateral, vertical, perpendicular, horizontal" and "top, bottom" are usually based on the directions or positional relationships shown in the 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 devices or elements 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 contours 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 here to describe the spatial positional relationship between a device or feature and other devices or features as shown in the figure. 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 figure. For example, if the device in the accompanying 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. If not 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 above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope 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, wherein the gas inlet is used to transport the raw gas, and the separation component (10) is capable of removing non-condensable gas, CO2 and moisture from the raw gas; A main heat exchanger (20), the main heat exchanger (20) comprising 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 an extension direction of the main heat exchanger (20), an inlet of the heat exchange flow path at a 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 arranged in 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 next-stage separation tank; a mixed refrigerant compression system (41), wherein the inlet of the mixed refrigerant compression system (41) is connected to the outlet of the first heat exchange channel (21), the gas phase outlet of the mixed refrigerant compression system (41) is connected to 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), 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 of 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), wherein 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), wherein 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 comprises: 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 tower (51); A first heat exchanger (61), the first heat exchanger (61) comprising 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 communicated with the gas outlet, and the Fischer-Tropsch synthesis tail gas treatment device further comprising: A heavy hydrocarbon washing tower (71), wherein 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.

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 tower (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 an inlet of the first flow channel (211) is communicated with a gas phase outlet of the mixed refrigerant compression system (41), and an outlet of the first flow channel (211) is communicated with an 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); an inlet of the first heat exchange flow path (231) is connected to a gas phase outlet of the heavy hydrocarbon washing tower (71); 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); the gas phase outlet of the primary separation tank (31) is connected to the inlet of the second heat exchange flow path (232); the inlet of the secondary separation tank (32) is connected to the outlet of the second heat exchange flow path (232); the gas phase outlet of the secondary separation tank (32) is connected to the inlet of the third heat exchange flow path (233); the inlet of the tertiary separation tank (33) is connected to the outlet of the third heat exchange flow path (233); and the liquid phase outlet of the tertiary 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 also 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), wherein the inlet of the H2 adsorption unit (82) is communicated with the second outlet of the CO adsorption unit (81), the first outlet of the H2 adsorption unit (82) is used to discharge H2, and the second outlet of the H2 adsorption unit (82) is used to communicate 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 also 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), wherein the fourth heat exchanger (67) 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 (73), the liquid phase outlet of the seventh pipeline is connected to the reflux inlet of the dehydrogenation tower (73), the gas phase outlet of the seventh pipeline is connected to the inlet of the seventh heat exchange channel (28), the inlet of the eighth pipeline is connected to the outlet of the fourth heat exchange channel (25), and a fourth connecting pipeline (68) is provided between the inlet of the eighth pipeline and the outlet of the fourth heat exchange channel (25), the fourth connecting pipeline (68) is provided with a fourth throttle valve (681), the outlet of the eighth pipeline is connected to the inlet of the third heat exchange channel (24), and the nitrogen compression system (42) is 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 raw 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 connected to 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 from the raw gas.

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