A methanol wash flash vapor purification device

Abstract

The utility model discloses a kind of methanol wash flash evaporation gas purification devices, first gas cooler, second gas cooler, first carbon dioxide liquefier, second carbon dioxide liquefier and liquid carbon dioxide separator.The utility model is through the design of first gas cooler, second gas cooler, first carbon dioxide liquefier, second carbon dioxide liquefier and liquid carbon dioxide separator, methanol wash flash evaporation gas exchanges cold quantity cooling after entering parallel first carbon dioxide liquefier and second carbon dioxide liquefier exchange cold quantity cooling again, the saturation vapor pressure of carbon dioxide drops, part of carbon dioxide in flash evaporation gas condenses into liquid carbon dioxide and forms gas-liquid mixture, gas-liquid mixture enters liquid carbon dioxide separator and separates out purification flash evaporation gas, flash evaporation gas is recycled after second gas cooler again, and purification step is completed, to carry out purification to flash evaporation gas.

Description

Technical Field

[0001] This utility model relates to the field of flash vapor purification technology, and in particular to a methanol washing flash vapor purification device. Background Technology

[0002] In the ammonia synthesis process, the methanol washing unit is a key step in removing carbon dioxide and hydrogen sulfide from the feed gas to achieve gas purification. During operation, this unit generates a large amount of flash vapor, which consists of approximately 20% hydrogen and carbon monoxide, essential gases for ammonia synthesis, and the remaining approximately 80% carbon dioxide. To recover these essential gases, existing processes typically use a compressor to pressurize the flash vapor and return it to the methanol washing system inlet for recirculation. However, the concentration of essential gases in the flash vapor after pressurization is not increased, resulting in the concentration remaining at the original level. Therefore, this proposal suggests a methanol washing flash vapor purification device to address the aforementioned problem. Utility Model Content

[0003] The purpose of this invention is to provide a methanol washing flash vapor purification device to solve the problems mentioned in the background art.

[0004] To achieve the above objectives, this utility model provides the following technical solution: a methanol washing flash vapor purification device, comprising: First gas heat exchanger; A first carbon dioxide liquefaction unit is located at the output end of a first gas cooler. The second carbon dioxide liquefaction unit is located at the output end of the first gas exchanger. A liquid carbon dioxide separator, wherein the liquid carbon dioxide separator is disposed at the output end of the first carbon dioxide liquefaction unit; The second gas cooler is located at the output end of the liquid carbon dioxide separator.

[0005] Preferably, the first input end of the first gas cooler is provided with a first flash vapor tube, the first output end of the first gas cooler is provided with a first purification flash vapor tube, the second output end of the first gas cooler is provided with a first liquid tube, and the first liquid tube is located at the first input end of the first carbon dioxide liquefaction unit.

[0006] Preferably, the first input end of the second gas cooler is provided with a second flash vapor tube, one end of the first flash vapor tube is located in the middle of the second flash vapor tube, the first output end of the second gas cooler is provided with a second purification flash vapor tube, and the second output end of the second gas cooler is provided with a second liquid tube, one end of the second liquid tube is located in the middle of the first liquid tube.

[0007] Preferably, the outlet end of the first carbon dioxide liquefier is provided with a third purification flash vapor tube, the third purification flash vapor tube is provided at the second input end of the first carbon dioxide liquefier, the output end of the first carbon dioxide liquefier is provided with a third liquid pipe, the third liquid pipe is provided at the input end of the liquid carbon dioxide separator.

[0008] Preferably, the second carbon dioxide liquefier includes a fourth liquid pipe disposed at the first output end of the second carbon dioxide liquefier, one end of the fourth liquid pipe being disposed in the middle of the third liquid pipe, a discharge pipe disposed at the second output end of the second carbon dioxide liquefier, a methanol pipe disposed at the first input end of the second carbon dioxide liquefier, a low-temperature methanol flow control valve disposed in the middle of the methanol pipe, and a parallel pipe disposed at the second input end of the second carbon dioxide liquefier, one end of the parallel pipe being disposed in the middle of the first liquid pipe.

[0009] Preferably, the first output end of the liquid carbon dioxide separator is provided with a reflux pipe, the reflux pipe is provided at the second input end of the first carbon dioxide liquefaction unit, the second output end of the liquid carbon dioxide separator is provided with a fourth purification flash vapor pipe, the fourth purification flash vapor pipe is provided at the second input end of the second gas exchanger, and a separator level control valve is provided in the middle of the fourth purification flash vapor pipe.

[0010] The technical effects and advantages of this utility model are as follows: This invention utilizes a design comprising a first gas cooler, a second gas cooler, a first carbon dioxide liquefier, a second carbon dioxide liquefier, and a liquid carbon dioxide separator. Methanol flash vapor undergoes cooling by exchanging cooling energy with the first and second gas coolers connected in parallel. It then enters the first and second carbon dioxide liquefiers in parallel for further cooling. Due to the saturated vapor pressure drop of carbon dioxide, some of the carbon dioxide in the flash vapor condenses into liquid carbon dioxide, forming a gas-liquid mixture. This mixture enters the liquid carbon dioxide separator to separate the purified flash vapor. The flash vapor then passes through the second gas cooler to recover its cooling energy, completing the purification process and thus purifying the flash vapor. Attached Figure Description

[0011] Figure 1 This is a schematic diagram of the present invention.

[0012] In the diagram: 1. First gas cooler; 101. First flash vapor tube; 102. First purification flash vapor tube; 103. First liquid tube; 2. Second gas cooler; 201. Second flash vapor tube; 202. Second purification flash vapor tube; 203. Second liquid tube; 3. First carbon dioxide liquefaction unit; 301. Third purification flash vapor tube; 302. Third liquid tube; 4. Second carbon dioxide liquefaction unit; 401. Fourth liquid tube; 402. Methanol tube; 403. Discharge tube; 404. Low-temperature methanol flow control valve; 5. Liquid carbon dioxide separator; 501. Reflux tube; 502. Fourth purification flash vapor tube; 503. Separator level control valve; 6. Parallel tubes. Detailed Implementation

[0013] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0014] This utility model provides, for example Figure 1 The methanol flash vapor purification apparatus shown includes: First gas cooler 1; The first carbon dioxide liquefaction unit 3 is located at the output end of the first gas exchanger 1. The second carbon dioxide liquefaction unit 4 is located at the output end of the first gas cooler 1. Liquid carbon dioxide separator 5 is located at the output end of the first carbon dioxide liquefier 3. The second gas cooler 2 is located at the output end of the liquid carbon dioxide separator 5.

[0015] It should be noted that the first gas heat exchanger 1 and the second gas heat exchanger 2 are existing heat exchange cooling devices. The core principle of a gas heat exchanger is the transfer and recovery of heat. It achieves cooling of the gas by establishing an insulated but thermally conductive wall between two fluids with a temperature difference. The first carbon dioxide liquefaction unit 3 and the second carbon dioxide liquefaction unit 4 are existing devices. The core principle of a carbon dioxide liquefaction unit is to convert gaseous carbon dioxide into liquid by cooling and pressurizing it. Typically, it first uses a compressor to pressurize the carbon dioxide gas, raising its liquefaction temperature. Then, the high-pressure carbon dioxide gas enters the condenser and is cooled to a temperature lower than the liquefaction temperature corresponding to its current pressure through heat exchange with the cooling medium. In this process, the carbon dioxide releases a large amount of latent heat, thus condensing from a gaseous state into a high-density liquid state. Specifically, the first input end of the first gas cooler 1 is provided with a first flash vapor tube 101, the first output end of the first gas cooler 1 is provided with a first purification flash vapor tube 102, the second output end of the first gas cooler 1 is provided with a first liquid tube 103, and the first liquid tube 103 is located at the first input end of the first carbon dioxide liquefaction unit 3.

[0016] It should be noted that the first purification flash vapor pipe 102 is used to discharge the flash vapor purified by the first gas cooler 1 from the first gas cooler 1. Specifically, the first input end of the second gas cooler 2 is provided with a second flash vapor tube 201, one end of the first flash vapor tube 101 is located in the middle of the second flash vapor tube 201, the first output end of the second gas cooler 2 is provided with a second purification flash vapor tube 202, the second output end of the second gas cooler 2 is provided with a second liquid tube 203, one end of the second liquid tube 203 is located in the middle of the first liquid tube 103, and the second input end of the second carbon dioxide liquefier 4 is provided with a parallel pipe 6, one end of the parallel pipe 6 is located in the middle of the first liquid tube 103.

[0017] It should be noted that the first flash vapor pipe 101 and the second flash vapor pipe 201 are connected, which allows the first gas cooler 1 and the second gas cooler 2 to be connected in parallel. The second purification flash vapor pipe 202 is used to discharge the flash vapor purified by the second gas cooler 2. The second liquid pipe 203 and the parallel pipe 6 are both connected to the first liquid pipe 103. This design allows the gas output from the first gas cooler 1 and the second gas cooler 2 to enter the interior of the first carbon dioxide liquefier 3 and the second carbon dioxide liquefier 4.

[0018] Specifically, the outlet end of the first carbon dioxide liquefier 3 is provided with a third purification flash vapor pipe 301, which is located at the second input end of the first carbon dioxide liquefier 3. The output end of the first carbon dioxide liquefier 3 is provided with a third liquid pipe 302, which is located at the input end of the liquid carbon dioxide separator 5.

[0019] Specifically, the second carbon dioxide liquefaction unit 4 includes a fourth liquid pipe 401 disposed at the first output end of the second carbon dioxide liquefaction unit 4, one end of the fourth liquid pipe 401 being disposed in the middle of the third liquid pipe 302, a discharge pipe 403 disposed at the second output end of the second carbon dioxide liquefaction unit 4, a methanol pipe 402 disposed at the first input end of the second carbon dioxide liquefaction unit 4, and a low-temperature methanol flow control valve 404 disposed in the middle of the methanol pipe 402.

[0020] It should be noted that the low-temperature methanol flow control valve 404 is an existing ball valve. During use, the flow rate and circulation inside the methanol pipe 402 are controlled by the low-temperature methanol flow control valve 404.

[0021] Specifically, the first output end of the liquid carbon dioxide separator 5 is provided with a return pipe 501, the return pipe 501 is provided at the second input end of the first carbon dioxide liquefaction unit 3, the second output end of the liquid carbon dioxide separator 5 is provided with a fourth purification flash vapor pipe 502, the fourth purification flash vapor pipe 502 is provided at the second input end of the second gas exchanger 2, and a separator level control valve 503 is provided in the middle of the fourth purification flash vapor pipe 502.

[0022] It should be noted that the separator level control valve 503 is an existing ball valve, which is used to control the flow and circulation inside the fourth purification flash vapor tube 502.

[0023] Furthermore, the methanol flash vapor has a pressure of 1.0 MPa and a temperature of -26°C. After passing through the first gas cooler 1 and the second gas cooler 2 in parallel, it is cooled to -50°C. Then, it enters the first carbon dioxide liquefaction unit 3 and the second carbon dioxide liquefaction unit 4 in parallel to exchange cooling energy and cool down to -60°C. The saturated vapor pressure of carbon dioxide drops to 0.32 MPa. Some of the carbon dioxide in the flash vapor condenses into liquid carbon dioxide and forms a gas-liquid mixture. The gas-liquid mixture enters the liquid carbon dioxide separator 5 to separate the purified flash vapor, in which the carbon dioxide content is reduced from 80% to 35% and the effective gas content is increased from 20% to 65%. The flash vapor then passes through the second gas cooler 2 to recover the cooling energy and complete the purification step. The liquid carbon dioxide separated by the liquid carbon dioxide separator 5 first passes through the separator level control valve 503, and then sequentially passes through the first carbon dioxide liquefaction unit 3 and the first gas exchanger 1 to recover the cooling capacity. The liquid carbon dioxide is vaporized into high-purity carbon dioxide gas. When the flash evaporation purification unit is operating normally, the cooling capacity for carbon dioxide liquefaction and flash evaporation purification is mostly self-circulated. That is, the cooling capacity required for carbon dioxide liquefaction is provided by the vaporization of liquid carbon dioxide. Since the amount of liquefied carbon dioxide is equal to the amount of vaporized carbon dioxide, theoretically the flash evaporation purification unit does not consume energy or cooling capacity during operation. However, there is cooling loss in the equipment and pipelines, and there is end difference loss in the process of the exchanger. Therefore, it is necessary to supplement the cooling capacity loss of the flash evaporation purification unit to maintain the balanced operation of the unit. This cooling capacity supplementation is completed by the second carbon dioxide liquefaction unit 4. The cooling capacity source is the low-temperature methanol provided by the methanol wash in this position. The flow rate is controlled by the low-temperature methanol flow control valve 404, thereby adjusting the amount of cooling capacity supplementation.

[0024] Finally, it should be noted that the above description is only a preferred embodiment of the present utility model and is not intended to limit the present utility model. Although the present utility model has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present utility model should be included within the protection scope of the present utility model.

Claims

1. A methanol flash vapor purification apparatus, characterized in that, include: First gas cooler (1); The first carbon dioxide liquefaction unit (3) is located at the output end of the first gas cooler (1). The second carbon dioxide liquefaction unit (4) is located at the output end of the first gas cooler (1); A liquid carbon dioxide separator (5) is provided at the output end of the first carbon dioxide liquefier (3). The second gas cooler (2) is located at the output end of the liquid carbon dioxide separator (5).

2. The methanol flash vapor purification apparatus according to claim 1, characterized in that, The first gas cooler (1) is provided with a first flash vapor tube (101) at its first input end, a first purification flash vapor tube (102) at its first output end, a first liquid tube (103) at its second output end, and the first liquid tube (103) at its first input end of the first carbon dioxide liquefaction unit (3).

3. The methanol flash vapor purification apparatus according to claim 2, characterized in that, The second gas cooler (2) is provided with a second flash vapor tube (201) at its first input end, and one end of the first flash vapor tube (101) is located in the middle of the second flash vapor tube (201). The second gas cooler (2) is provided with a second purification flash vapor tube (202) at its first output end, and a second liquid tube (203) is provided at its second output end, and one end of the second liquid tube (203) is located in the middle of the first liquid tube (103).

4. The methanol flash vapor purification apparatus according to claim 1, characterized in that, The first carbon dioxide liquefaction unit (3) is provided with a third purification flash vapor tube (301) at the outlet end. The third purification flash vapor tube (301) is provided at the second input end of the first carbon dioxide liquefaction unit (3). The first carbon dioxide liquefaction unit (3) is provided with a third liquid tube (302) at the output end. The third liquid tube (302) is provided at the input end of the liquid carbon dioxide separator (5).

5. The methanol flash vapor purification apparatus according to claim 4, characterized in that, The second carbon dioxide liquefaction unit (4) includes a fourth liquid pipe (401) disposed at the first output end of the second carbon dioxide liquefaction unit (4), one end of the fourth liquid pipe (401) being disposed in the middle of the third liquid pipe (302), a discharge pipe (403) being disposed at the second output end of the second carbon dioxide liquefaction unit (4), a methanol pipe (402) being disposed at the first input end of the second carbon dioxide liquefaction unit (4), a low-temperature methanol flow control valve (404) being disposed in the middle of the methanol pipe (402), and a parallel pipe (6) being disposed at the second input end of the second carbon dioxide liquefaction unit (4), one end of the parallel pipe (6) being disposed in the middle of the first liquid pipe (103).

6. The methanol flash vapor purification apparatus according to claim 2, characterized in that, The first output end of the liquid carbon dioxide separator (5) is provided with a reflux pipe (501), the reflux pipe (501) is provided with the second input end of the first carbon dioxide liquefaction unit (3), the second output end of the liquid carbon dioxide separator (5) is provided with a fourth purification flash vapor pipe (502), the fourth purification flash vapor pipe (502) is provided with the second input end of the second gas exchanger (2), and a separator level control valve (503) is provided in the middle of the fourth purification flash vapor pipe (502).

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