Carbon dioxide-containing acid gas purification device

By adding a secondary cooler, liquid dispenser and distillation tower to the low-temperature methanol washing process, and combining a temperature variable adsorber, the problems of high energy consumption and low carbon dioxide purity in the low-temperature methanol washing process are solved, and high-efficiency and low-energy consumption acid gas purification and high-purity carbon dioxide production are achieved.

CN222605865UActive Publication Date: 2025-03-14SINOPEC NINGBO ENG +2
View PDF 0 Cites 0 Cited by

Patent Information

Application Number
CN202421201914.X
Authority / Receiving Office
CN · China
Patent Type
Utility models(China)
Current Assignee / Owner
Filing Date
2024-05-29
Publication Date
2025-03-14
Estimated Expiration
2034-05-29

AI Technical Summary

Technical Problem

The existing low-temperature methanol washing process purifies acidic gases containing carbon dioxide, and has a high energy consumption and a low purity of carbon dioxide.

Method used

A carbon dioxide-containing acid gas purification device was designed, a secondary cooler and a secondary liquid separator were added, and a distillation tower and a temperature-changing adsorber were coupled, which reduced the demeritization of the raw gas, thereby reducing the energy consumption of the device and improving the purity of the carbon dioxide.

Benefits of technology

Through the design of this device, the energy consumption and equipment investment of the purification device are significantly reduced, while the purity and pressure of carbon dioxide are increased, and high purity and high pressure of food-grade carbon dioxide product gas is obtained.

✦ Generated by Eureka AI based on patent content.

Smart Images

  • Figure CN222605865U_ABST
    Figure CN222605865U_ABST
Patent Text Reader

Abstract

The utility model relates to the technical field of acid gas purification, and discloses a carbon dioxide-containing acid gas purification device. The device comprises an absorption tower, a secondary cooler, a secondary liquid separation tank, a rectifying tower and a temperature swing adsorber which are communicated with one another through pipelines, the absorption tower comprises a desulfurization section and a decarbonization section; a gas phase outlet of the desulfurization section of the absorption tower is communicated with a first inlet of the secondary cooler; a first outlet of the second-stage cooler is communicated with a first inlet of the second-stage liquid separation tank; a gas phase outlet of the secondary liquid separation tank is communicated with a gas phase inlet of the decarbonization section of the absorption tower; a liquid phase outlet of the secondary liquid separation tank is communicated with a liquid phase inlet of the rectifying tower; a pressure reducing valve is arranged between the secondary liquid separation tank and the rectifying tower, and is connected with a pressure recoverer in parallel; and a liquid phase outlet of the rectifying tower is communicated with an inlet of the temperature swing adsorber. The device is additionally provided with a secondary cooling device coupling rectifying tower, so that the raw material gas amount is reduced and the energy consumption of the device is reduced; and a temperature swing adsorber is additionally arranged to obtain high-purity and high-pressure food-grade carbon dioxide product gas.
Need to check novelty before this filing date? Find Prior Art

Description

Technical Field

[0001] The utility model relates to the field of acid gas purification, in particular to a device for purifying acid gas containing carbon dioxide. Background Art

[0002] Coal gasification plays an important role in coal chemical industry. It is used to produce various gas fuels and is a clean energy source. Some impurity gases are inevitably produced in the process of coal-to-gas. Therefore, gas purification is an important part of the coal chemical industry. In the coal chemical industry, gas purification mainly separates CO2, H2S, COS, etc. from CO and H2 and recycles them. As a process that can achieve the goals of decarbonization and desulfurization at the same time, low-temperature methanol washing has the advantages of high efficiency and economy, and is widely used in the gas purification industry of coal chemical industry.

[0003] Low-temperature methanol washing was first developed by Linde and Lurgi in Germany as an acid gas removal process. It is widely used in the production of synthetic ammonia, city gas, industrial hydrogen, synthetic methanol or other one-carbon chemical synthesis processes using coal, petroleum coke or residual oil as raw materials. In the related technology, the low-temperature methanol washing device includes an H2S absorption tower, a CO2 absorption tower, a medium-pressure flash tower, a reabsorption tower, a methanol thermal regeneration tower and a tail gas washing system. The low-temperature methanol washing process is as follows: the crude synthesis gas at about 40°C is cooled to -26°C to -10°C and then sent to the H2S absorption tower and the CO2 absorption tower for low-temperature methanol washing in turn to remove H2S and CO2 and obtain purified gas; the rich methanol that absorbs H2S and CO2 is sent to the medium-pressure flash tower, the reabsorption tower, the methanol thermal regeneration system and the tail gas washing system in turn, and the methanol is separated from the acid gas through processes such as decompression desorption, gas stripping, and heating regeneration, so that the methanol is regenerated and the tail gas is washed and the effective gas is separated.

[0004] Since the dissolution of gas in liquid is an exothermic process, as the solubility of acid gas in low-temperature methanol increases, the temperature of methanol gradually increases, while the absorption capacity of methanol for acid gas decreases with the increase in temperature. Therefore, in order to ensure the absorption capacity of methanol for acid gas and reduce the volume circulation, the methanol washing device must be maintained at low temperature. In the devices and processes of related technologies, it is common that the temperature of the raw synthesis gas entering the absorption tower is relatively high after being cooled, resulting in a large amount of methanol used in the absorption process; secondly, the heat exchange network is unreasonable and the cold recovery is insufficient. The method of maintaining the low-temperature operation of the methanol washing device is mainly to supplement the cold capacity into the system through the ice machine, resulting in a large external cold supply, a high load on the ice machine, and high energy consumption.

[0005] The low-temperature methanol washing process uses cold methanol as the absorption solvent and utilizes the excellent property of methanol's great solubility in acidic gases at low temperatures to remove acidic gases from the raw gas. It is a physical absorption method. The solubility of methanol for acidic gases depends on the partial pressure of the dissolved absorbent and the operating temperature of the absorbent. Under the same pressure, the lower the temperature, the greater the solubility of methanol for acidic gases. Therefore, in order to improve the absorption capacity of methanol for acidic gases and reduce the circulation volume of solvents, the methanol washing device must be operated at a lower temperature; and maintaining it at a low temperature will result in higher system energy consumption. Utility Model Content

[0006] The purpose of the utility model is to overcome the problems of high energy consumption and low purity of target product carbon dioxide in the low-temperature methanol washing process for purifying acidic gas containing carbon dioxide in the prior art, and to provide a device for purifying acidic gas containing carbon dioxide. The device adds a secondary cooler and a secondary liquid separator, and is coupled with a distillation tower to reduce the amount of raw gas to be decontaminated, thereby reducing the energy consumption of the device; at the same time, the addition of a temperature variable adsorption device can obtain high-purity and high-pressure food-grade carbon dioxide product gas.

[0007] In order to achieve the above-mentioned purpose, the utility model provides a purification device for acidic gas containing carbon dioxide, wherein the device includes an absorption tower, a secondary cooler, a secondary liquid separator, a distillation tower and a temperature-variable adsorber interconnected by pipelines; the absorption tower includes a desulfurization section and a decarbonization section; the gas phase outlet of the desulfurization section of the absorption tower is connected to the first inlet of the secondary cooler; the first outlet of the secondary cooler is connected to the first inlet of the secondary liquid separator; the gas phase outlet of the secondary liquid separator is connected to the gas phase inlet of the decarbonization section of the absorption tower; the liquid phase outlet of the secondary liquid separator is connected to the liquid phase inlet of the distillation tower; a pressure reducing valve is provided between the secondary liquid separator and the distillation tower, and a pressure recovery device is connected in parallel to the pressure reducing valve; the liquid phase outlet of the distillation tower is connected to the inlet of the temperature-variable adsorber.

[0008] The device provided by the utility model adds a secondary cooler, a secondary liquid separator, a distillation tower and a pressure recovery device to a traditional low-temperature methanol washing system. The reactors cooperate with each other and are particularly suitable for purifying acidic gases containing carbon dioxide. The raw gas is cooled and separated twice to achieve liquefied separation of carbon dioxide in the medium to be treated, reduce the amount of raw gas to be removed, and further reduce the steam consumption, gas stripping nitrogen consumption, electricity consumption and other public engineering consumption of the purification device, while reducing the specifications and sizes of the entire system equipment and pipelines, thereby significantly reducing the investment in the device.

[0009] The device provided by the utility model is further coupled with a temperature swing adsorber to perform temperature swing adsorption to remove impurities in the gas, so as to obtain high-purity and high-pressure food-grade carbon dioxide product gas. The food-grade carbon dioxide product gas can be directly sold to the outside, thereby reducing the carbon emissions of the device and having a high promotion value.

[0010] The device provided by the utility model is further coupled with a pressure recovery device to directly recover the pressure generated during the decompression process, thereby realizing further energy recovery and further reducing the energy consumption of the device. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 It is a schematic diagram of the device of the utility model.

[0012] Description of Reference Numerals

[0013] 1-Raw gas; 2-Mixture containing primary cooling raw gas and primary cooling liquid; 3-primary cooling of raw gas; 4-desulfurization of raw gas;

[0014] 5-contains secondary cooling feed gas and di-6-carbon dioxide recovery liquid;

[0015] a mixture of carbon oxide recovery liquid;

[0016] 7-secondary cooling of raw gas; 8-purification of raw gas;

[0017] 9- purify product gas; 10- distill carbon dioxide liquid;

[0018] 11- Carbon dioxide product gas; 12- Distillation impurity gas;

[0019] 13- high temperature heat source; 14- low temperature heat source;

[0020] 15-semi-lean methanol; 16-lean methanol;

[0021] 17- low purity carbon dioxide; 18- tail gas;

[0022] 19- low purity carbon dioxide product gas; 20- waste gas;

[0023] 21- primary condensate; 22- refrigerant inlet;

[0024] 23-refrigerant outlet; 24-carbon-rich methanol;

[0025] 25-sulfur-rich methanol; 26-food grade carbon dioxide product gas;

[0026] C1-absorption tower; C2-distillation tower;

[0027] E1-primary cooler; E2-secondary cooler;

[0028] E3-reboiler; S1-flash tower;

[0029] S2-methanol thermal regeneration tower; S3-temperature swing adsorber;

[0030] S4-pressure recovery device; V1-first-stage separation tank;

[0031] V2-Secondary separation tank. DETAILED DESCRIPTION

[0032] The specific implementation of the present invention is described in detail below in conjunction with the accompanying drawings. It should be understood that the specific implementation described here is only used to illustrate and explain the present invention, and is not used to limit the present invention.

[0033] The utility model provides a device for purifying acidic gas containing carbon dioxide, wherein the device comprises an absorption tower C1, a secondary cooler E2, a secondary liquid separation tank V2, a distillation tower C2 and a temperature-swing adsorber S3 which are interconnected through pipelines;

[0034] The absorption tower C1 includes a desulfurization section and a decarbonization section;

[0035] The gas phase outlet of the desulfurization section of the absorption tower C1 is connected to the first inlet of the secondary cooler E2;

[0036] The first outlet of the secondary cooler E2 is connected to the first inlet of the secondary liquid separation tank V2;

[0037] 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;

[0038] The liquid phase outlet of the secondary liquid separation tank V2 is connected to the liquid phase inlet of the distillation tower C2;

[0039] A pressure reducing valve is provided between the secondary liquid separation tank V2 and the distillation tower C2, and a pressure recovery device S4 is connected in parallel to the pressure reducing valve;

[0040] The liquid phase outlet of the distillation tower C2 is communicated with the inlet of the temperature swing adsorber S3.

[0041] The device provided by the utility model adds a secondary cooler, a secondary liquid separator, a distillation tower and a pressure recovery device to a traditional low-temperature methanol washing system. The reactors cooperate with each other and are particularly suitable for purifying acidic gases containing carbon dioxide. The raw gas is cooled and separated twice to achieve liquefied separation of carbon dioxide in the medium to be treated, reduce the amount of raw gas to be decontaminated, and thus reduce the steam consumption, gas stripping nitrogen consumption, electricity consumption and other public engineering consumption of the purification device, while reducing the specifications and sizes of the entire system equipment and pipelines, thereby significantly reducing the investment in the device.

[0042] The device provided by the utility model is further coupled with a temperature variable adsorber to perform temperature variable adsorption to remove impurities in the gas, thereby obtaining a high-purity and high-pressure food-grade carbon dioxide product gas. The food-grade carbon dioxide product gas can be directly sold, thereby reducing the carbon emissions of the device and having a high promotion value.

[0043] The device provided by the utility model is further coupled with a pressure recovery device to directly recover the pressure generated during the decompression process, thereby realizing further energy recovery and further reducing the energy consumption of the device.

[0044] In the present invention, preferably, the decarbonization section is located in the upper section of the absorption tower C1, and the desulfurization section is located in the lower section of the absorption tower C1. By arranging the desulfurization section below the decarbonization section, the medium to be treated (preferably the primary cooling raw gas 3) is controlled to contact the desulfurizer carbon-rich methanol 24 in reverse to first perform desulfurization, remove most of the hydrogen sulfide, and obtain the desulfurized raw gas 4; the desulfurized raw gas 4 enters the secondary cooler and / or the secondary liquid separator in turn for secondary cooling and liquid separation to obtain the secondary cooling raw gas 7, and the secondary cooling raw gas 7 enters the decarbonization section and the decarbonizer lean methanol 16, semi-lean methanol 15 for reverse contact and then decarbonization, and desulfurization and decarbonization are performed in stages, which is more conducive to obtaining qualified product gas.

[0045] In the present invention, preferably, the decarburization section is provided with a first decarburization agent inlet and a second decarburization agent inlet.

[0046] In the present invention, preferably, along the vertical direction, the first decarburizing agent inlet is higher than the second decarburizing agent inlet. The advantage of adopting the above preferred embodiment is that the medium to be treated can be decarburized in two stages, which is more conducive to improving the decarburization degree of the medium to be treated.

[0047] In the utility model, the specific structure and size of the absorption tower are not particularly limited, as long as the desulfurization and decarbonization of the medium to be treated can be achieved.

[0048] In the present invention, the required refrigerant is provided by an external refrigeration unit. Preferably, the secondary cooler E2 is provided with a refrigerant inlet 22 and a refrigerant outlet 23, the refrigerant inlet 22 is connected to the external refrigerant supply unit, and the refrigerant outlet 23 is connected to the external refrigerant recovery unit.

[0049] In the present invention, there is no particular limitation on the specific type of the secondary cooler, and all coolers conventionally defined in the art are applicable to the present invention, such as a shell and tube cooler, a tube-in-shell cooler, and the like.

[0050] In the present invention, preferably, the device further comprises a primary cooler E1, and the primary cooler E1 is arranged between the distillation tower C2 and the temperature swing adsorber S3.

[0051] In the present invention, preferably, the liquid phase inlet of the primary cooler E1 is connected to the liquid phase outlet of the distillation tower C2. The primary cooler is connected to the distillation tower C2 to recover the cooling capacity of the distilled carbon dioxide liquid obtained in the distillation process of the distillation tower to obtain the carbon dioxide product gas 11.

[0052] In the present invention, preferably, the first outlet of the primary cooler E1 is connected to the inlet of the temperature swing adsorber S3. The primary cooler is connected to the distillation tower C2, and the carbon dioxide product gas 11 is subjected to temperature swing adsorption to obtain food-grade carbon dioxide product gas 26.

[0053] In the present invention, there is no particular limitation on the specific type and size of the distillation tower. Any distillation tower conventionally defined in the art can be applied to the present invention, and those skilled in the art can make adjustments according to actual needs.

[0054] In the present invention, there is no particular limitation on the specific type of the temperature swing adsorber. As long as the re-adsorption of the medium to be treated can be achieved to obtain product-grade carbon dioxide product gas 26, any temperature swing adsorber conventionally defined in the art can be applicable to the present invention.

[0055] In the present invention, preferably, the first gas phase inlet of the primary cooler E1 is connected to the gas phase outlet of the decarburization section of the absorption tower C1. The purified raw gas 8 obtained by the decarburization section in this embodiment is transported to the primary cooler to recover cold energy to obtain purified product gas 9.

[0056] In the present invention, there is no particular limitation on the specific type of the primary cooler, as long as it can cool the raw gas to remove methanol and water in the raw gas and realize the heat exchange function. Preferably, the primary cooler E1 is provided with multiple tube passes; more preferably, the primary cooler E1 is a coil heat exchanger cooler.

[0057] In the present invention, preferably, the raw gas 1 as the medium to be treated enters the primary cooler E1 for primary cooling to obtain a mixture 2 containing the primary cooled raw gas and the primary cooling liquid.

[0058] In the present invention, preferably, the device further comprises a primary liquid separator V1, the inlet of the primary liquid separator V1 is connected to the second outlet of the primary cooler E1. The primary liquid separator V1 is connected to the primary cooler through the primary liquid separator, and is used to separate the mixture 2 containing the primary cooling raw gas and the primary cooling liquid into the primary liquid separator to obtain the primary cooling raw gas 3 and the primary cooling liquid 21.

[0059] In the present invention, preferably, the gas phase outlet of the first-stage liquid separator V1 is connected to the gas phase inlet of the desulfurization section of the absorption tower C1. The first-stage liquid separator is connected to the desulfurization section of the absorption tower, and the first-stage cooling raw gas 3 obtained by the first-stage liquid separator enters the desulfurization section of the absorption tower and contacts the desulfurizer carbon-rich methanol 24 in reverse to perform desulfurization, removing most of the hydrogen sulfide in the first-stage cooling raw gas 3, and obtaining the desulfurized raw gas 4 and sulfur-rich methanol 25.

[0060] In the present invention, preferably, the device further comprises a flash tower S1, the gas phase inlet of the flash tower S1 is connected to the gas phase outlet of the distillation tower C2. The flash tower is connected to the distillation tower through the flash tower, and the flash tower is used to flash the distillation impurity gas 12 obtained by the distillation reaction of the distillation tower to recover the effective gas carbon monoxide and hydrogen.

[0061] In the present invention, there is no particular limitation on the specific type of the flash tower, and any tower kettle that can achieve flash evaporation as conventionally defined in the art is applicable to the present invention.

[0062] In the present invention, preferably, the first gas phase outlet of the flash tower S1 is connected to the second gas phase inlet of the primary cooler E1. The flash tower is connected to the primary cooler to transport the low-purity carbon dioxide 17 generated in the flash evaporation process of the flash tower to the primary cooler to recover cold energy, thereby obtaining low-purity carbon dioxide gas 19, and the low-purity carbon dioxide product gas 19 is directly sent to the downstream device.

[0063] In the present invention, preferably, the second gas phase outlet of the flash tower S1 is connected to the third gas phase inlet of the primary cooler E1. The flash tower is connected to the primary cooler to transport the tail gas 18 generated during the flash evaporation process of the flash tower to the primary cooler to recover cold energy, thereby obtaining the waste gas 20, which can be directly discharged after removing methanol.

[0064] In the present invention, preferably, the first liquid phase inlet of the flash tower S1 is connected to the liquid phase outlet of the desulfurization section of the absorber C1. The desulfurization section of the absorber is connected to the flash tower to transport the sulfur-rich methanol 25 obtained by desulfurization to the flash tower to recover the methanol in the sulfur-rich methanol 25 for recycling.

[0065] In the present invention, preferably, the first liquid phase outlet of the flash tower S1 is connected to the second decarbonizing agent inlet of the decarbonizing section of the absorber C1. The flash tower and the decarbonizing section of the absorber are connected to provide decarbonizing agent semi-lean methanol 15 for the decarbonization performed by the absorber.

[0066] In the present invention, preferably, the liquid phase outlet of the decarbonization section of the absorption tower C1 is connected to the desulfurization agent inlet of the desulfurization section of the absorption tower C1 and / or the second liquid phase inlet of the flash tower S1. The decarbonization section is connected with the desulfurization section to transport the carbon-rich methanol 24 produced in the decarbonization section to the desulfurization section for cyclic desulfurization; the decarbonization section is connected with the flash tower to transport the carbon-rich methanol 24 produced in the decarbonization section to the flash tower to analyze part of the CO2 dissolved in the methanol.

[0067] In the present invention, preferably, the device further comprises a methanol thermal regeneration tower S2, and the methanol thermal regeneration tower S2 is used for regenerating methanol. In the present invention, there is no particular limitation on the specific type of the methanol thermal regeneration tower, as long as the regeneration of methanol can be achieved.

[0068] In the present invention, preferably, the second liquid phase inlet of the methanol thermal regeneration tower S2 is connected to the second liquid phase outlet of the flash tower S1. By connecting the flash tower with the methanol thermal regeneration tower, the methanol-containing solution generated during the flash evaporation process of the flash tower is transported to the methanol thermal regeneration tower for methanol regeneration.

[0069] In the present invention, preferably, the second liquid phase outlet of the methanol thermal regeneration tower S2 is connected to the first decarbonizing agent inlet of the decarbonizing section of the absorber C1. The methanol thermal regeneration tower is connected to the decarbonizing section of the absorber to provide the required decarbonizing agent lean methanol 16 to the decarbonizing section of the absorber.

[0070] In the present invention, preferably, the third liquid phase inlet of the methanol thermal regeneration tower S2 is connected to the liquid phase outlet of the primary liquid separation tank V1. The methanol thermal regeneration tower is connected to the primary liquid separation tank, and the primary condensate 21 in the primary liquid separation tank is transported to the methanol thermal regeneration tower to recover the methanol in the primary condensate.

[0071] In the present invention, preferably, the distillation tower C2 is provided with a reboiler E3.

[0072] In the present invention, the specific type of the reboiler is also not particularly limited. The reboiler is a reboiler that is conventionally defined in the art and is matched with a distillation tower, as long as it can achieve the heat exchange function.

[0073] In the present invention, preferably, the first liquid phase inlet of the methanol thermal regeneration tower S2 is connected to the outlet of the reboiler E3, and the first liquid phase outlet of the methanol thermal regeneration tower S2 is connected to the inlet of the reboiler E3. The methanol thermal regeneration tower is connected to the reboiler to provide a high-temperature heat source 13 for the reboiler; at the same time, the low-temperature heat source 14 after heat exchange in the reboiler returns to the thermal regenerator for repeated regeneration and recycling. The reboiler does not need to introduce additional heating medium and directly takes heat from the system, thereby reducing the energy consumption of the device.

[0074] In the present invention, preferably, the pressure reducing valve is arranged on the pipeline between the secondary liquid separation tank V2 and the distillation tower C2. The carbon dioxide recovery liquid 6 obtained by the secondary liquid separation of the secondary liquid separation tank enters the distillation tower for distillation after being decompressed by the pressure reducing valve.

[0075] In the present invention, there is no particular limitation on the specific type of the pressure recovery device, as long as it can realize the recovery of the pressure generated during the pressure reducing process of the pressure reducing valve, and those skilled in the art can adjust it according to actual needs.

[0076] The embodiment is used to illustrate the implementation principle of the device provided by the utility model.

[0077] Use Figure 1 The device shown purifies the acidic gas containing carbon dioxide to obtain high-purity and high-pressure food-grade carbon dioxide product gas. Specifically:

[0078] (1) The raw gas 1 (the raw gas 1 contains carbon dioxide and hydrogen sulfide) from an external upstream device enters the primary cooler E1 for primary cooling after being sprayed with methanol, thereby obtaining a mixture 2 containing the primary cooled raw gas and the primary condensate. The mixture 2 containing the primary cooled raw gas and the primary condensate enters the primary liquid separation tank V1 for primary liquid separation, thereby obtaining a primary cooled raw gas 3 and a primary condensate 21. The primary condensate 21 is transported to the methanol thermal regeneration tower S2 for methanol thermal regeneration to recover the methanol in the primary condensate 21.

[0079] (2) The primary cooling feed gas 3 and the carbon-rich methanol 24 are in reverse contact and desulfurized in the desulfurization section of the absorption tower C1 to obtain the desulfurized feed gas 4 and the sulfur-rich methanol 25. The sulfur-rich methanol 25 is transported to the flash tower S1 for flash evaporation to recover the methanol in the sulfur-rich methanol 25;

[0080] (3) The desulfurized raw gas 4 enters the secondary cooler E2 and is subjected to secondary cooling in the presence of a refrigerant (the refrigerant is provided by an external refrigerant supply unit and enters the secondary cooler E2 through the refrigerant inlet 22, and flows out through the refrigerant outlet 23 after the secondary cooling is completed) to obtain a mixture 5 containing the secondary cooled raw gas and the carbon dioxide recovery liquid. The mixture 5 containing the secondary cooled raw gas and the carbon dioxide recovery liquid enters the secondary liquid separation tank V2 for secondary liquid separation to obtain a secondary cooled raw gas 7 and the carbon dioxide recovery liquid 6;

[0081] (4) The secondary cooling raw gas 7 is reversely contacted with the semi-lean methanol 15 provided by the flash tower S1 and the lean methanol 16 provided by the methanol thermal regeneration tower S2, and is decarbonized in the decarbonization section of the absorption tower C1 to obtain a purified raw gas 8 and a carbon-rich methanol 24. The purified raw gas 8 is transported to the primary cooler E1 to recover the cold to obtain a purified product gas 9, at least part of the carbon-rich methanol 24 is transported to the flash tower S1 for flash evaporation to recover methanol for repeated use, and at least part of the carbon-rich methanol 24 is transported to the desulfurization section of the absorption tower C1 for desulfurization and repeated use;

[0082] (5) The carbon dioxide recovery liquid 6 is decompressed by a pressure reducing valve to obtain a decompressed carbon dioxide recovery liquid. The pressure obtained during the decompression process is recovered through a pressure recovery device S4 to recover energy;

[0083] (6) The decompressed carbon dioxide recovery liquid enters the distillation tower C2 for distillation to remove impurities, and obtains distilled carbon dioxide liquid 10 and distilled impurity gas 12. The distilled carbon dioxide liquid 10 is transported to the primary cooler E1 to recover the cold and obtain the carbon dioxide product gas 11. The distilled impurity gas 12 is transported to the flash tower S1 for flash evaporation to recover the effective gas (H2 and CO) in the distilled impurity gas 12 to obtain low-purity carbon dioxide 17. The low-purity carbon dioxide 17 recovers the cold and obtains the low-purity carbon dioxide product gas 19. The low-purity carbon dioxide product gas is directly sent to the downstream device. During the distillation process, the heat source of the reboiler E3 is provided by the high-temperature heat source 13 of the methanol thermal regeneration tower S2, and the low-temperature heat source 14 after heat exchange in the reboiler E3 is returned to the methanol thermal regeneration tower S2 for repeated regeneration; during the whole process, the tail gas 18 generated in the flash tower S1 can be directly transported to the primary cooler E1 to recover the cold and then discharged as waste gas 20;

[0084] (7) The carbon dioxide product gas 11 is transported to the temperature swing adsorber S3 for temperature swing adsorption to obtain food-grade carbon dioxide product gas 26.

[0085] The device provided by the utility model adds a secondary cooler, a secondary liquid separator, a distillation tower and a pressure recovery device to a traditional low-temperature methanol washing system. The reactors cooperate with each other and are particularly suitable for purifying acidic gases containing carbon dioxide. The raw gas is cooled and separated twice to achieve liquefied separation of carbon dioxide in the medium to be treated, reduce the amount of raw gas to be decontaminated, and thus reduce the steam consumption, gas stripping nitrogen consumption, electricity consumption and other public engineering consumption of the purification device, while reducing the specifications and sizes of the entire system equipment and pipelines, thereby significantly reducing the investment in the device.

[0086] The device provided by the utility model is further coupled with a temperature variable adsorber to perform temperature variable adsorption to remove impurities in the gas, thereby obtaining a high-purity and high-pressure food-grade carbon dioxide product gas. The food-grade carbon dioxide product gas can be directly sold, thereby reducing the carbon emissions of the device and having a high promotion value.

[0087] The device provided by the utility model is further coupled with a pressure recovery device to directly recover the pressure generated in the decompression process of the carbon dioxide recovery liquid, thereby realizing further energy recovery and further reducing the energy consumption of the device, and has a very high industrial promotion value.

[0088] The preferred embodiments of the present invention are described in detail above in conjunction with the accompanying drawings, but the present invention is not limited thereto. Within the technical concept of the present invention, the technical solution of the present invention can be subjected to a variety of simple modifications, including the combination of various specific technical features in any suitable manner. In order to avoid unnecessary repetition, the present invention will not further describe various possible combinations. However, these simple modifications and combinations should also be regarded as the contents disclosed by the present invention and belong to the protection scope of the present invention.

Claims

1. A device for purifying acidic gas containing carbon dioxide, characterized in that: The device comprises an absorption tower (C1), a secondary cooler (E2), a secondary liquid separation tank (V2), a distillation tower (C2) and a temperature swing adsorber (S3) which are interconnected through pipelines; The absorption tower (C1) includes a desulfurization section and a decarbonization section; 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 in communication with the first 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 liquid phase inlet of the distillation tower (C2); A pressure reducing valve is provided between the secondary liquid separation tank (V2) and the distillation tower (C2), and a pressure recovery device (S4) is connected in parallel to the pressure reducing valve; The liquid phase outlet of the distillation tower (C2) is connected to the inlet of the temperature swing adsorber (S3).

2. The device according to claim 1, wherein: The decarbonization section is located at the upper section of the absorption tower (C1), and the desulfurization section is located at the lower section of the absorption tower (C1).

3. The device according to claim 2, wherein: The decarburization section is provided with a first decarburization agent inlet and a second decarburization agent inlet. In the vertical direction, the first decarburization agent inlet is higher than the second decarburization agent inlet.

4. The device according to any one of claims 1 to 3, wherein: The secondary cooler (E2) is provided with a refrigerant inlet (22) and a refrigerant outlet (23), the refrigerant inlet (22) is connected to an external refrigerant supply unit, and the refrigerant outlet (23) is connected to an external refrigerant recovery unit.

5. The device according to any one of claims 1 to 3, 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 temperature swing adsorber (S3); and / or, the liquid phase inlet of the primary cooler (E1) is connected to the liquid phase outlet of the distillation tower (C2); and / or, the first outlet of the primary cooler (E1) is connected to the inlet of the temperature swing adsorber (S3); And / or, the first gas phase inlet of the primary cooler (E1) is connected to the gas phase outlet of the decarbonization section of the absorption tower (C1).

6. The device according to claim 5, characterized in that The device further comprises a primary liquid separation tank (V1), the inlet of the primary liquid separation tank (V1) being in communication with the second outlet of the primary cooler (E1); And / or, 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).

7. The device according to claim 6, characterized in that The device further comprises a flash tower (S1), a gas phase inlet of the flash tower (S1) being connected to a gas phase outlet of the rectification tower (C2).

8. The device according to claim 7, characterized in that The first gas phase outlet of the flash tower (S1) is connected to the second gas phase inlet of the primary cooler (E1); and / or, the second gas phase outlet of the flash tower (S1) is connected to the third gas phase inlet of the primary cooler (E1); 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); and / or, the first liquid phase outlet of the flash tower (S1) is connected to the second decarburizing agent inlet of the decarburizing section of the absorption tower (C1); And / or, the liquid phase outlet of the decarbonization section of the absorption tower (C1) is connected to the desulfurization agent inlet of the desulfurization section of the absorption tower (C1) and / or the second liquid phase inlet of the flash tower (S1).

9. The device according to claim 8, characterized in that The device also includes a methanol thermal regeneration tower (S2), and the methanol thermal regeneration tower (S2) is used for regenerating methanol.

10. The device according to claim 9, characterized in that The second liquid phase inlet of the methanol thermal regeneration tower (S2) is connected to the second liquid phase outlet of the flash tower (S1); and / or, the second liquid phase outlet of the methanol thermal regeneration tower (S2) is connected to the first decarbonizing agent inlet of the decarbonizing section of the absorption tower (C1); And / or, the third liquid phase inlet of the methanol thermal regeneration tower (S2) is connected to the liquid phase outlet of the primary liquid separation tank (V1).