Device for removing acid gas and recovering food-grade product gas
By designing a device including an absorption tower, a double-stage cooler, a double-stage liquid separation tank, a distillation tower, an adsorber and a flash evaporator, the problem of high carbon emissions in the low-temperature methanol washing method is solved, efficient carbon dioxide recovery and utilization is achieved, and energy consumption and investment are significantly reduced.
Patent Information
- Application Number
- CN202421203443.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-05-29
- Publication Date
- 2025-04-01
- Estimated Expiration
- 2034-05-29
AI Technical Summary
In the existing low-temperature methanol washing method, the by-product of low-concentration carbon dioxide product gas and nitrogen-containing carbon dioxide exhaust gas during methanol regeneration leads to high carbon emissions and is difficult to directly recover and utilize.
A device including an absorption tower, a double-stage cooler, a double-stage liquid separation tank, a distillation tower, an adsorber and a flash evaporation tower is designed. Through the combination of an absorption tower and a distillation tower, the carbon dioxide in the raw gas is liquefied and separated, and further purified by distillation and adsorber, high-purity and high-pressure food-grade carbon dioxide product gas is produced.
It significantly reduces carbon emissions, reduces the intake amount that needs further decarbonization, reduces the circulation of absorbents, reduces the energy consumption of the device, and realizes the recycling and utilization of high-purity carbon dioxide, improving economic value.
Smart Images
Figure CN222694353U_ABST
Abstract
Description
Technical Field
[0001] The utility model relates to the technical field of coal gas purification, in particular to a device for removing acidic gas and recovering food-grade product gas. Background Art
[0002] So far, coal is still an important source of energy. However, direct combustion of coal not only has a single utilization structure, but is also unfriendly to the environment. In recent years, technologies such as coal-to-methanol, coal-to-olefins, coal-to-natural gas, synthetic ammonia, coal-to-ethylene glycol, coal-to-oil, coal-to-aromatics, and low-rank coal fractionation have been booming. Among them, energy conservation, emission reduction, and low-carbon green have become new focuses in the new coal chemical industry.
[0003] The low-temperature methanol washing method for removing acidic gases utilizes the excellent solubility of methanol at low temperatures to effectively remove impurity gases and recover effective gases such as H2 and CO. It can be used to purify the crude synthesis gas of coal-to-gasification, effectively absorb and utilize the acidic components therein, and can also be used to remove acidic gases in natural gas. It has high practical value and is widely used. With the continuous application of this process, those skilled in the art have found that the conventional low-temperature methanol washing method for removing acidic gases has obvious problems. During the regeneration process of methanol that absorbs acidic gases such as carbon dioxide and hydrogen sulfide, low-concentration carbon dioxide product gas (concentration of about 98.5 mol%) and part of the carbon dioxide tail gas containing nitrogen will be produced as by-products. The tail gas pressure is extremely low, and the carbon dioxide therein is difficult to directly recover, so it is directly vented; the low-concentration carbon dioxide product gas has low pressure and low purity, and is difficult to directly utilize. If no downstream users are found, it will be directly discharged together with the generated tail gas, so the carbon emissions are relatively large. Utility Model Content
[0004] The purpose of the utility model is to overcome the problem of high carbon emissions in the existing low-temperature methanol washing method and provide a device for removing acidic gases and recovering food-grade product gas. The device described in the utility model can not only greatly reduce the carbon emissions of the device, but also recover food-grade carbon dioxide product gas.
[0005] In order to achieve the above-mentioned object, the first aspect of the utility model provides a device for removing acidic gas and recovering food-grade product gas, the device comprising an absorption tower, a secondary cooler, a secondary liquid separator, a rectification tower, an adsorber and a flash tower;
[0006] The absorption tower comprises a desulfurization section and a decarbonization section, and the gas phase outlet of the desulfurization section of the absorption tower is connected to the first inlet of the secondary cooler;
[0007] The first outlet of the secondary cooler is in communication with the inlet of the secondary liquid separation tank;
[0008] The gas phase outlet of the secondary liquid separator is connected to the gas phase inlet of the decarbonization section of the absorption tower;
[0009] The liquid phase outlet of the secondary liquid separator is connected to the inlet of the distillation tower;
[0010] The liquid phase outlet of the distillation tower is connected to the adsorber inlet;
[0011] The first liquid phase outlet of the flash tower is communicated with the second inlet of the secondary cooler.
[0012] Through the above technical solution, the beneficial effects of the utility model include:
[0013] In the device provided by the utility model, a secondary cooler and a secondary liquid separator are introduced into the traditional low-temperature methanol washing device, and coupled with a distillation tower, and part of the carbon dioxide in the raw gas is first liquefied and separated through the absorption tower, the secondary cooler, and the secondary liquid separator, which can not only significantly reduce carbon emissions, but also reduce the intake volume that needs further decarbonization, thereby reducing the circulation volume of the absorbent used for decarbonization, thereby significantly reducing the energy consumption of the device, while reducing the specifications and dimensions of the entire device and pipelines, thereby significantly reducing the device investment; then it is recovered through the distillation tower to obtain a liquid phase carbon dioxide pure product; the gas phase carbon dioxide pure product obtained by heat exchange of the liquid phase carbon dioxide pure product is further purified through an adsorber to obtain a food-grade carbon dioxide product gas (high purity, high pressure) for direct external sale, realizing waste into treasure, improving economic value, and no compression is required, saving compression work of downstream devices. The device provided by the utility model has a high value of promotion and application.
[0014] In the device of the utility model, the cooling capacity required in the carbon dioxide liquefaction process is provided by the interior of the device of the utility model (flash tower), and the amount of crude liquid carbon dioxide obtained by condensation is increased compared with the condensation of external cooling capacity, which is more conducive to reducing carbon emissions and improving energy utilization efficiency; the cooling medium does not need to be supplied externally, reducing the processing cost. BRIEF DESCRIPTION OF THE DRAWINGS
[0015] Figure 1 It is a schematic diagram of the structure of a device for removing acidic gas and recovering food-grade product gas provided by the utility model.
[0016] Description of Reference Numerals
[0017] Figure 1 middle,
[0018] 1. Raw gas; 2. Material after primary cooling; 3. Raw gas after primary cooling;
[0019] 4. Desulfurized raw gas; 5. Secondary cooling material; 6. Liquid carbon dioxide crude product;
[0020] 7. Secondary cooling of raw gas; 8. Purification of synthesis gas; 9. Purification of synthesis gas after heat exchange;
[0021] 10. Pure liquid carbon dioxide; 11. Pure gaseous carbon dioxide; 12. Gas after distillation;
[0022] 13. Carbon-rich methanol; 14. Sulfur-rich methanol; 15. Semi-lean methanol;
[0023] 16. Lean methanol; 17. Low-purity carbon dioxide product gas; 18. Tail gas;
[0024] 19. Low-purity carbon dioxide product gas after heat exchange; 20. Tail gas after heat exchange; 21. Primary condensate;
[0025] 22. Food grade carbon dioxide product gas;
[0026] C1, absorption tower; C2, distillation tower; E1, primary cooler;
[0027] E2, secondary cooler; E3, distillation tower reboiler; S1, flash tower;
[0028] S2, thermal regeneration tower; S3, adsorber; V1, primary liquid separation tank;
[0029] V2, secondary separation tank. DETAILED DESCRIPTION
[0030] The specific implementation modes of the present invention are described in detail below. It should be understood that the specific implementation modes described herein are only used to illustrate and explain the present invention, and are not used to limit the present invention.
[0031] In the present utility model, unless otherwise specified, "first", "second" and "third" do not indicate a sequence of precedence or a limitation on each material or step, but are only used to distinguish that they are not the same material or step.
[0032] The first aspect of the utility model provides a device for continuously removing acidic gas and recovering food-grade product gas by methanol washing method, such as Figure 1 As shown, the device includes an absorption tower C1, a secondary cooler E2, a secondary liquid separator V2, a distillation tower C2, an adsorber S3 and a flash tower S1;
[0033] The absorption tower C1 includes a desulfurization section and a decarbonization section, and the gas phase outlet of the desulfurization section of the absorption tower C1 is connected to the first inlet of the secondary cooler E2;
[0034] The first outlet of the secondary cooler E2 is connected to the inlet of the secondary liquid separation tank V2;
[0035] The gas phase outlet of the secondary liquid separation tank V2 is connected to the gas phase inlet of the decarbonization section of the absorption tower C1;
[0036] The liquid phase outlet of the secondary liquid separator V2 is connected to the inlet of the distillation tower C2;
[0037] The liquid phase outlet of the distillation tower C2 is connected to the inlet of the adsorber S3;
[0038] The first liquid phase outlet of the flash tower S1 is communicated with the second inlet of the secondary cooler E2.
[0039] First, the raw gas is desulfurized by the desulfurization section of the absorption tower C1 to obtain desulfurized raw gas and sulfur-rich methanol. This preferred embodiment avoids the liquefaction of part of the H2S with the carbon dioxide in the secondary cooler, which makes it difficult to ensure the purity of the liquid CO2 obtained by subsequent distillation in the distillation tower.
[0040] Second, in the secondary cooler E2 and the secondary liquid separator V2, the carbon dioxide in the desulfurized raw gas is liquefied to obtain secondary cooled raw gas and liquid carbon dioxide crude product.
[0041] Third, in the distillation tower C2, the crude liquid carbon dioxide is distilled to obtain pure liquid carbon dioxide and distilled gas. This preferred embodiment realizes the recovery of carbon dioxide, thereby reducing carbon emissions.
[0042] Fourth, the absorption tower C1 decarbonization section decarbonizes the secondary cooled raw gas to obtain carbon-rich methanol and purified synthesis gas. With this preferred embodiment, the residual carbon dioxide in the secondary cooled raw gas is removed, which is more conducive to the removal of acidic gases in the raw gas.
[0043] Fifth, the liquid phase carbon dioxide pure product is further purified by adsorber S3, and finally food-grade carbon dioxide product gas (with a purity of not less than 99.9%) can be obtained. The food-grade carbon dioxide product gas can be directly sold to the outside, thus turning waste into treasure and improving economic value.
[0044] In the above process, the first liquid phase outlet of the flash tower S1 is connected to the secondary cooler E2, which is used to provide cooling medium for the secondary cooler E2 (it can be understood that the cooling medium is the cooling liquid obtained in the methanol regeneration process, and the specific composition is not particularly required by the present invention). In the present invention, the cooling capacity required in the carbon dioxide liquefaction process is provided by the inside of the device of the present invention (flash tower S1), and the amount of crude liquid carbon dioxide obtained by condensation is increased compared with the condensation of external cooling capacity, which is more conducive to reducing carbon emissions and improving energy utilization efficiency; the cooling medium does not need to be supplied externally, reducing processing costs.
[0045] The device provided by the utility model is particularly suitable for removing acidic gases by low-temperature methanol washing method, using methanol to absorb carbon dioxide and hydrogen sulfide in the raw gas to obtain purified synthesis gas, and the methanol that absorbs acidic gases such as carbon dioxide and hydrogen sulfide can be regenerated by conventional equipment in the field. In the utility model, the flash tower S1 and the following thermal regeneration tower S2 are used together to achieve the regeneration of methanol. First, part of the gas dissolved in the solution is analyzed in the flash tower S1, and then the methanol is further regenerated in the following thermal regeneration tower S2. The specific regeneration process can be carried out according to the conventional method in the field, and the utility model will not be described in detail here. According to a preferred embodiment of the utility model, the device also includes a thermal regeneration tower S2, and the thermal regeneration tower S2 is used for the regeneration of methanol.
[0046] The clean methanol (lean methanol) of the decarbonization section of the utility model is provided by the thermal regeneration tower S2. According to a preferred embodiment of the utility model, the clean methanol inlet of the decarbonization section of the absorption tower C1 is connected to the first liquid phase outlet of the thermal regeneration tower S2.
[0047] The main washing methanol (semi-lean methanol) of the decarbonization section of the utility model is provided by the flash tower S1. According to a more preferred embodiment of the utility model, the main washing methanol inlet of the decarbonization section of the absorption tower C1 is connected to the second liquid phase outlet of the flash tower S1.
[0048] According to a preferred embodiment of the utility model, along the vertical direction, the fine wash methanol inlet is arranged above the main wash methanol inlet.
[0049] In the present invention, the carbon-rich methanol obtained by decarbonization of the absorber C1 decarbonization section is partially used for desulfurization of the absorber C1 desulfurization section. According to a preferred embodiment of the present invention, the liquid phase outlet of the absorber C1 decarbonization section is connected to the liquid phase inlet of the absorber C1 desulfurization section.
[0050] According to a more preferred embodiment of the utility model, the liquid phase outlet of the decarbonization section of the absorption tower C1 is connected to the liquid phase inlet of the desulfurization section of the absorption tower C1 and the second liquid phase inlet of the flash tower S1 respectively. According to this preferred embodiment, part of the carbon-rich methanol obtained by decarbonization in the decarbonization section of the absorption tower C1 is used for desulfurization in the desulfurization section of the absorption tower C1, and the remaining part is sent to the flash tower S1 to remove the acid gas in the carbon-rich methanol, thereby realizing the regeneration and reuse of the methanol.
[0051] The utility model has no special limitation on the absorption tower C1, which can be a conventional choice in the art.
[0052] According to a preferred embodiment of the present invention, the device further comprises a primary cooler E1, and the primary cooler E1 is arranged between the distillation tower C2 and the adsorber S3.
[0053] The utility model has no particular limitation on the specific type of the primary cooler, which can be a conventional choice in the art, as long as the purpose of removing methanol and water can be achieved.
[0054] The pure liquid carbon dioxide obtained at the bottom of the distillation tower C2 of the utility model is first heat exchanged to obtain pure gaseous carbon dioxide, and then the pure gaseous carbon dioxide is purified in the adsorber S3 to obtain food-grade carbon dioxide product gas, which is directly sold.
[0055] According to a preferred embodiment of the present invention, the liquid phase outlet of the distillation tower C2 is connected to the liquid phase pure carbon dioxide product inlet of the primary cooler E1.
[0056] According to a preferred embodiment of the present utility model, the pure gaseous carbon dioxide outlet of the primary cooler E1 is connected to the inlet of the adsorber S3.
[0057] The purified synthesis gas obtained by the decarbonization section of the absorption tower C1 of the utility model recovers cold energy and is sent to the downstream device. According to a preferred embodiment of the utility model, the gas phase outlet of the decarbonization section of the absorption tower C1 is connected to the purified synthesis gas inlet of the primary cooler E1.
[0058] According to a preferred embodiment of the present utility model, the device further comprises a primary liquid separation tank V1.
[0059] The utility model has no special limitation on the primary liquid separation tank, which can be a conventional liquid separation tank used for gas-liquid separation in the art.
[0060] According to a preferred embodiment of the present utility model, the outlet of the cooled material of the primary cooler E1 is communicated with the inlet of the primary liquid separation tank V1.
[0061] According to a preferred embodiment of the present utility model, the gas phase outlet of the primary liquid separator V1 is connected to the gas phase inlet of the desulfurization section of the absorption tower C1.
[0062] The methanol in the primary condensate of the utility model is regenerated and reused in the thermal regeneration tower S2. According to a preferred embodiment of the utility model, the liquid phase outlet of the primary liquid separation tank V1 is connected to the third liquid phase inlet of the thermal regeneration tower S2.
[0063] In the device provided by the utility model, before the raw gas is sent to the absorption tower C1 for desulfurization, it first enters the primary cooler and the primary liquid separator, performs primary cooling and primary liquid separation on the raw gas, discharges the primary condensate from the liquid phase outlet of the primary liquid separator, and discharges the primary cooled raw gas from the gas phase outlet. The adoption of this preferred embodiment is conducive to the effective removal of water in the raw gas to prevent the water in the raw gas from freezing and blocking the equipment during the primary cooling; and also removes the methanol carried in the raw gas from the methanol spray tower described below.
[0064] According to a preferred embodiment of the present utility model, the device further comprises a methanol spray tower.
[0065] According to a preferred embodiment of the utility model, the outlet of the methanol spray tower is connected to the raw gas inlet of the primary cooler E1. This preferred embodiment is used to spray the raw gas, which is beneficial to prevent the water in the raw gas from freezing during the primary cooling process.
[0066] The utility model has no particular limitation on the specific type of the methanol spray tower, and it can be any conventional methanol spray tower in the art that can realize the methanol spray function.
[0067] It should be noted that the methanol spray tower Figure 1 Not shown in .
[0068] The cooling medium in the secondary cooler E2 of the utility model is provided by the flash tower S1, and the heat exchanged cooling medium returns to the flash tower S1. According to a preferred embodiment of the utility model, the second outlet of the secondary cooler E2 is connected to the third liquid phase inlet of the flash tower S1.
[0069] The utility model has no particular limitation on the type of the secondary cooler E2, and it can be any cooler that can achieve the carbon dioxide liquefaction requirements of the utility model. According to a preferred embodiment of the utility model, the secondary cooler E2 is a cryogenic cooler.
[0070] The utility model has no special limitation on the secondary liquid separation tank, which can be a conventional liquid separation tank used for gas-liquid separation in the art.
[0071] The present invention has no particular limitation on the distillation tower C2, which may be any distillation tower conventionally used in the art.
[0072] In the art, the distillation tower C2 is usually equipped with a distillation tower reboiler E3, which is well known to those skilled in the art. The heat source required by the distillation tower reboiler E3 comes from the thermal regeneration tower S2, and returns to the thermal regeneration tower S2 after heat exchange. With this preferred embodiment, the distillation tower reboiler does not need to introduce additional heating medium, and directly takes heat from the device, thereby reducing the energy consumption of the device.
[0073] According to a preferred embodiment of the present invention, the second liquid phase outlet of the thermal regeneration tower S2 is connected to the distillation tower reboiler E3.
[0074] According to a preferred embodiment of the present invention, the second liquid phase inlet of the thermal regeneration tower S2 is connected to the distillation tower reboiler E3.
[0075] Part of the effective gas (CO, H2) in the gas phase discharge from the top of the distillation tower C2 (gas after distillation) can be recycled. According to a preferred embodiment of the present invention, the gas phase outlet of the distillation tower C2 is connected to the gas phase inlet of the flash tower S1.
[0076] The adsorber S3 of the present invention may be a pressure swing adsorber or a temperature swing adsorber. According to a preferred embodiment of the present invention, the adsorber S3 is a temperature swing adsorber.
[0077] The utility model has no special limitation on the temperature-variable adsorber, which can be a conventional arrangement in the art.
[0078] The sulfur-rich methanol obtained by desulfurization in the desulfurization section of the utility model is returned to the flash tower S1. According to a preferred embodiment of the utility model, the first liquid phase inlet of the flash tower S1 is connected to the liquid phase outlet of the desulfurization section of the absorption tower C1.
[0079] The tail gas of the utility model is directly discharged after recovering cold and removing methanol through the primary cooler. According to a preferred embodiment of the utility model, the second gas phase outlet of the flash tower S1 is connected to the tail gas inlet of the primary cooler E1.
[0080] The low-purity carbon dioxide product gas of the utility model can be sent to downstream users after the primary cooler recovers the cold, or it can be directly discharged after further removing methanol together with the tail gas. According to a preferred embodiment of the utility model, the first gas phase outlet of the flash tower S1 is connected to the low-purity carbon dioxide product gas inlet of the primary cooler E1.
[0081] The utility model has no particular limitation on the above-mentioned methanol removal process, and the removal can be carried out with reference to conventional devices in the art, and the utility model does not make any particular requirements here.
[0082] According to a preferred embodiment of the present invention, the first liquid phase inlet of the thermal regeneration tower S2 is communicated with the first liquid phase inlet of the flash tower S1.
[0083] According to a preferred embodiment of the utility model, a pressure reducing valve is further provided between the secondary liquid separation tank V2 and the distillation tower C2. This preferred embodiment is used to reduce the pressure of the crude liquid carbon dioxide product.
[0084] According to a specific implementation of the present utility model, reference can be made to Figure 1 The raw gas 1 is sent to a methanol spray tower for washing with methanol and then sent to a primary cooler E1 for primary cooling (methanol and water are cooled) to obtain a primary cooled material 2. The primary cooled material 2 is sent to a primary liquid separation tank V1 for primary liquid separation to obtain a primary cooled raw gas 3 and a primary condensate 21 (mainly containing methanol and water);
[0085] The primary condensate 21 is sent to the thermal regeneration tower S2 for methanol regeneration;
[0086] The primary cooled raw gas 3 is sent to the desulfurization section of the absorption tower C1 for desulfurization treatment with carbon-rich methanol 13 to obtain desulfurized raw gas 4 and sulfur-rich methanol 14; the sulfur-rich methanol 14 is sent to the flash tower S1 for methanol regeneration;
[0087] The desulfurized raw gas 4 is first sent to the secondary cooler E2 (deep cooler) to liquefy the carbon dioxide to obtain the secondary cooled material 5; the secondary cooled material 5 is sent to the secondary liquid separator V2 to separate the carbon dioxide to obtain the secondary cooled raw gas 7 and the liquid carbon dioxide crude product 6; wherein the cooling medium required for the secondary cooler E2 is provided by the flash tower S1, and is returned to the flash tower S1 after heat exchange;
[0088] The secondary cooled raw gas 7 is sent to the decarbonization section of the absorption tower C1, and firstly contacts with the main washing methanol (semi-lean methanol 15) from the flash tower S1 in reverse direction for the first decarbonization, and then contacts with the fine washing methanol (lean methanol 16) from the thermal regeneration tower S2 in reverse direction for the second decarbonization, so as to obtain the purified synthesis gas 8. At the same time, carbon-rich methanol 13 is obtained after decarbonization in the decarbonization section. Part of the carbon-rich methanol 13 is returned to the desulfurization section for desulfurization, and the remaining part is sent to the flash tower S1 for methanol regeneration; the purified synthesis gas 8 is sent to the primary cooler E1 to recover the cold, and the purified synthesis gas 9 after heat exchange is obtained and sent to the downstream device;
[0089] The crude liquid carbon dioxide product 6 is depressurized by a pressure reducing valve and then sent to a distillation tower C2 for distillation, and a pure liquid carbon dioxide product 10 is obtained at the bottom of the tower and a distilled gas 12 is obtained at the top of the tower, wherein the heat source required for the distillation tower reboiler E3 is provided by the thermal regeneration tower S2, and is returned to the thermal regeneration tower S2 after heat exchange; the distilled gas 12 is sent to a flash tower S1 to recover the effective gas (CO and H2) therein;
[0090] The liquid phase pure carbon dioxide product 10 is sent to the primary cooler E1 to recover cold to obtain a gas phase pure carbon dioxide product 11, and the gas phase pure carbon dioxide product 11 is sent to the adsorber S3 (temperature swing adsorber) for purification to obtain a food grade carbon dioxide product gas 22 which is directly sold;
[0091] The tail gas 18 is drawn out from the second gas phase outlet of the flash tower S1, and then recovered through the primary cooler E1 to obtain the tail gas 20 after heat exchange, and the tail gas 20 after heat exchange is further de-methanoled and then directly discharged;
[0092] A low-purity carbon dioxide product gas 17 is drawn out from the first gas phase outlet of the flash tower S1, and then the cooling energy is recovered by the primary cooler E1 to obtain a low-purity carbon dioxide product gas 19 after heat exchange. The low-purity carbon dioxide product gas 19 after heat exchange is further de-methanoled and then supplied to downstream customers or directly discharged;
[0093] The sulfur-rich methanol solution flowing out of the flash tower S1 is sent to the thermal regeneration tower S2 to continue the regeneration of methanol.
[0094] The device and method provided by the utility model can not only significantly reduce carbon emissions, but also reduce the intake volume that needs further decarbonization, thereby reducing the circulation volume of the methanol absorbent used for further decarbonization, thereby significantly reducing the energy consumption of the device, while reducing the specifications and dimensions of the entire device equipment and pipelines, thereby significantly reducing the device investment; then it is recovered through the distillation tower and adsorber, and the obtained food-grade carbon dioxide product gas (high purity and high pressure) can be directly sold to the outside, realizing waste into treasure, improving economic value, and no compression is required, saving compression work of downstream devices. The device provided by the utility model has a high value of promotion and application.
[0095] It should be noted that the present application is not limited to the above-mentioned embodiments. The above-mentioned embodiments are only examples, and the embodiments having the same structure as the technical idea and exerting the same effect within the scope of the technical solution of the present application are all included in the technical scope of the present application. In addition, without departing from the scope of the main purpose of the present application, various modifications that can be thought of by those skilled in the art to the embodiments and other methods of combining some of the constituent elements in the embodiments are also included in the scope of the present application.
Claims
1. A device for removing acidic gases and recovering food-grade product gas, characterized in that: The device comprises an absorption tower (C1), a secondary cooler (E2), a secondary liquid separator (V2), a rectification tower (C2), an adsorber (S3) and a flash tower (S1); The absorption tower (C1) comprises a desulfurization section and a decarbonization section, and the gas phase outlet of the desulfurization section of the absorption tower (C1) is connected to the first inlet of the secondary cooler (E2); The first outlet of the secondary cooler (E2) is connected to the inlet of the secondary liquid separation tank (V2); The gas phase outlet of the secondary liquid separation tank (V2) is connected to the gas phase inlet of the decarbonization section of the absorption tower (C1); The liquid phase outlet of the secondary liquid separation tank (V2) is connected to the inlet of the distillation tower (C2); The liquid phase outlet of the distillation tower (C2) is connected to the inlet of the adsorber (S3); The first liquid phase outlet of the flash tower (S1) is communicated with the second inlet of the secondary cooler (E2).
2. The device according to claim 1, characterized in that The device further comprises a thermal regeneration tower (S2), and the thermal regeneration tower (S2) is used for regenerating methanol.
3. The device according to claim 2, characterized in that The cleansing methanol inlet of the decarbonization section of the absorption tower (C1) is connected to the first liquid phase outlet of the thermal regeneration tower (S2).
4. The device according to claim 3, characterized in that The main washing methanol inlet of the decarbonization section of the absorption tower (C1) is connected to the second liquid phase outlet of the flash tower (S1); And / or, in the vertical direction, the fine wash methanol inlet is arranged above the main wash methanol inlet.
5. The device according to claim 1, characterized in that The liquid phase outlet of the decarbonization section of the absorption tower (C1) is communicated with the liquid phase inlet of the desulfurization section of the absorption tower (C1).
6. The device according to any one of claims 1 to 5, characterized in that The device further comprises a primary cooler (E1), wherein the primary cooler (E1) is arranged between the distillation tower (C2) and the adsorber (S3).
7. The device according to claim 6, characterized in that The device further comprises a primary liquid separator (V1), and the outlet of the cooled material of the primary cooler (E1) is connected to the inlet of the primary liquid separator (V1).
8. The device according to claim 7, characterized in that The gas phase outlet of the first-stage liquid separation tank (V1) is connected to the gas phase inlet of the desulfurization section of the absorption tower (C1); And / or, the liquid phase outlet of the primary liquid separation tank (V1) is connected to the third liquid phase inlet of the thermal regeneration tower (S2).
9. The device according to any one of claims 1 to 5, characterized in that The second outlet of the secondary cooler (E2) is communicated with the third liquid phase inlet of the flash tower (S1).
10. The device according to any one of claims 1 to 5, characterized in that The gas phase outlet of the distillation tower (C2) is connected to the gas phase inlet of the flash tower (S1); And / or, the first liquid phase inlet of the flash tower (S1) is connected to the liquid phase outlet of the desulfurization section of the absorption tower (C1).