Carbon dioxide treatment system for oil-displacing agent

Abstract

The invention relates to a carbon dioxide treatment system for an oil-displacing agent. The carbon dioxide treatment system comprises a dehydration skid and a purification skid, the dehydration sledge comprises a molecular sieve tower which is communicated with the communication pipeline, and carbon dioxide enters the molecular sieve tower through the communication pipeline to remove moisture. The purification skid comprises a heat exchange device, a purification tower and a reboiler; the heat exchange device is provided with a first heat exchange channel and a second heat exchange channel, an inlet of the first heat exchange channel is communicated with the dehydration skid through a communication pipeline, and dehydrated carbon dioxide enters the first heat exchange channel through the communication pipeline to be liquefied; a tower inlet in the upper part of the purifying tower is communicated with an outlet of the first heat exchange channel. The reboiler is located at the bottom of the purifying tower, and the liquid carbon dioxide separated by the purifying tower is conveyed to the reboiler for heating; a liquid outlet of the reboiler is communicated with the second heat exchange channel, and purified carbon dioxide is conveyed to the second heat exchange channel for cooling. According to the invention, a dehydration skid and a purification skid are integrated together, so that the integration degree of carbon dioxide industrial treatment is improved.

Description

Technical Field

[0001] The present disclosure relates to the technical field of carbon dioxide processing, and in particular to a carbon dioxide processing system for oil displacement agents. Background Art

[0002] In the field of petrochemicals, carbon dioxide is a commonly used oil displacement agent. After carbon dioxide is injected into the oil layer, it can be mixed with the underground crude oil under the conditions of appropriate pressure, temperature and crude oil composition. After carbon dioxide and crude oil become miscible liquids, they can form a single liquid phase, which can effectively displace the formation crude oil to the production well. In order to obtain pure carbon dioxide that can be used for production, the carbon dioxide gas needs to be purified.

[0003] At present, the commonly used methods for separating and purifying carbon dioxide are: chemical absorption, pressure swing adsorption, membrane separation and cryogenic separation. Among them, the recovery purity of the chemical absorption method is very high, but it has problems such as high equipment cost and high energy consumption. The pressure swing adsorption method has low energy consumption, low operating pressure and high gas purity, but the adsorption material is easy to deactivate and the subsequent maintenance workload is large. The membrane separation technology has a simple system, low energy consumption and small equipment footprint, but it cannot achieve large-scale production. The cryogenic separation method is not only simple to operate, but also can adapt to different load conditions, can achieve large-scale production, and has relatively low cost and great economic benefits.

[0004] Carbon dioxide contains water. In the low temperature environment of purification, it is easy to freeze the pipeline and cause damage to equipment and pipelines. Therefore, before the purification step, the carbon dioxide needs to be dehydrated. In industrial production processes, molecular sieves are often used to dehydrate water-containing gases. Molecular sieves are artificially synthesized hydrated aluminosilicates (zeolites) or natural zeolites that have the function of screening molecules. The pore size is large enough for gas molecules to pass through, but water molecules cannot pass through, and it has a very good dehydration effect. Summary of the invention

[0005] In order to solve the problems existing in the prior art, the present disclosure provides a carbon dioxide processing system for oil displacement agents.

[0006] According to a first aspect of the present disclosure, there is provided a carbon dioxide treatment system for oil displacement agents, comprising:

[0007] A dehydration skid, the dehydration skid comprising a molecular sieve tower, the molecular sieve tower being configured to be in communication with a connecting pipeline, and carbon dioxide being configured to enter the molecular sieve tower through the connecting pipeline to remove water from the carbon dioxide;

[0008] A purification skid, the purification skid comprising a heat exchange device, a purification tower and a reboiler;

[0009] The heat exchange device is provided with a first heat exchange channel and a second heat exchange channel; the inlet of the first heat exchange channel is configured to be connected to the dehydration skid through a connecting pipeline, and the carbon dioxide gas dehydrated by the molecular sieve tower is configured to enter the first heat exchange channel through the connecting pipeline for liquefaction;

[0010] The tower inlet at the top of the purification tower is configured to be connected to the outlet of the first heat exchange channel through a connecting pipeline; the liquid carbon dioxide is configured to flow downward after being fed into the purification tower, and the non-condensable gas in the liquid carbon dioxide is configured to flow upward and flow out from the tower outlet;

[0011] The reboiler is configured to be located at the bottom of the purification tower, and the liquid carbon dioxide separated by the purification tower is configured to be transported to the reboiler for heating; the liquid outlet of the reboiler is configured to be connected to the second heat exchange channel, and the purified carbon dioxide is configured to be transported to the second heat exchange channel for cooling.

[0012] In one embodiment of the present disclosure, the heat exchange device is provided with a third heat exchange channel; the outlet of the purification tower is constructed to be connected to the inlet of the third heat exchange channel through a connecting pipeline; the non-condensable gas obtained by separation and purification in the purification tower is configured to be transported to the third heat exchange channel for heating.

[0013] In one embodiment of the present disclosure, the heat exchange device is provided with a fifth heat exchange channel; the inlet of the fifth heat exchange channel is configured to be connected to the compressor through a connecting pipeline, and the carbon dioxide gas source flowing out of the compressor is configured to enter the fifth heat exchange channel through the connecting pipeline for cooling; the purification skid also includes a heavy hydrocarbon separator, and the inlet of the heavy hydrocarbon separator is configured to be connected to the outlet of the fifth heat exchange channel through a connecting pipeline; the cooled carbon dioxide is configured to be sent to the heavy hydrocarbon separator for separation and purification.

[0014] In one embodiment of the present disclosure, the heat exchange device is further provided with a sixth heat exchange channel; the gas outlet at the top of the heavy hydrocarbon separator is constructed to be connected to the sixth heat exchange channel, and the separated carbon dioxide gas is configured to be transported to the sixth heat exchange channel for heating; the outlet of the sixth heat exchange channel is constructed to be connected to the dehydration skid through a connecting pipeline, and the heated carbon dioxide gas is configured to be transported to the dehydration skid for dehydration.

[0015] In one embodiment of the present disclosure, a differential pressure gauge is provided between the inlet and outlet of the fifth heat exchange channel, and a hot blowing device is provided on the fifth heat exchange channel; when the differential pressure gauge shows that the pressure difference is greater than the normal value, the hot blowing device is started to eliminate the freezing blockage fault in the fifth heat exchange channel.

[0016] In one embodiment of the present disclosure, the molecular sieve towers are provided in two, wherein when one of the molecular sieve towers is dehydrating the carbon dioxide, the other molecular sieve tower is configured to regenerate the molecular sieve; the dehydration skid also includes a heating device, and the heating device is constructed to be connected to the two molecular sieve towers respectively, wherein part of the carbon dioxide dehydrated in one of the molecular sieve towers is configured to be heated by the heating device and then sent to the other molecular sieve tower to regenerate the other molecular sieve tower.

[0017] In one embodiment of the present disclosure, the molecular sieve tower includes a first opening and a second opening; the first opening is constructed to be connected to a connecting pipeline; external carbon dioxide is configured to enter the molecular sieve tower from the first opening through the connecting pipeline for dehydration, and the dehydrated carbon dioxide is configured to be discharged from the second opening.

[0018] In one embodiment of the present disclosure, the dehydration skid also includes a regeneration pipeline connecting the second openings of the two molecular sieve towers, and the heating device is arranged in the regeneration pipeline; part of the carbon dioxide dehydrated in one of the molecular sieve towers is configured to be discharged through its second opening, heated by the heating device and sent to the second opening of another molecular sieve tower to regenerate the other molecular sieve tower.

[0019] In one embodiment of the present disclosure, the dehydration skid also includes an air cooler and a gas-liquid separator; the air cooler is constructed to be connected to the first opening of the molecular sieve tower, and the carbon dioxide entering the molecular sieve tower from the second opening is configured to flow to the air cooler through the first opening for cooling; the gas-liquid separator is constructed to be located downstream of the air cooler, and is constructed to perform gas-liquid separation on the carbon dioxide cooled by the air cooler.

[0020] In one embodiment of the present disclosure, the dehydration skid also includes a dust filter, which is constructed to be connected to the second opening of the molecular sieve tower through a connecting pipeline, and the carbon dioxide discharged from the second opening is configured to be filtered by the dust filter and then sent to the first heat exchange channel of the purification skid.

[0021] One beneficial effect of the present disclosure is that the present disclosure integrates the dehydration skid and the purification skid of carbon dioxide, so that the process of industrial treatment of carbon dioxide is no longer separated, and the degree of integration of industrial treatment of carbon dioxide is improved. It also realizes the dehydration step before carbon dioxide purification, thereby preventing carbon dioxide gas with excessive water content from freezing and blocking the connecting pipeline when cooling. The present disclosure realizes the heat exchange of multiple process flows in one heat exchange device by setting multiple heat exchange channels on the heat exchange device, thereby saving energy consumption of the purification system and reducing the purification cost.

[0022] Other features and advantages of the present disclosure will become apparent from the following detailed description of exemplary embodiments of the present disclosure with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate embodiments of the present disclosure and, together with the description, serve to explain the principles of the present disclosure.

[0024] Figure 1 is a schematic diagram of the structure of a purification skid in the processing system disclosed herein;

[0025] Figure 2 It is a schematic diagram of the structure of the dewatering skid in the processing system disclosed in the present invention.

[0026] Figure 1-2 The one-to-one correspondence between the component names and the reference numerals is as follows:

[0027] 10. Purification skid, 11. Dehydration skid, 12. Compressor, 13. Venting system, 14. Sewage system, 15. Propane refrigeration skid, 16. Storage and transportation unit, 17. Discharge pipeline, 18. Diversion port, 19. Bypass valve;

[0028] 2. heat exchange device, 21. first heat exchange channel, 22. second heat exchange channel, 23. third heat exchange channel, 24. fourth heat exchange channel, 25. fifth heat exchange channel, 26. sixth heat exchange channel;

[0029] 31. purification tower, 311. tower inlet, 312. tower outlet, 32. reboiler, 321. liquid outlet, 322. weir plate, 33. heavy hydrocarbon separator, 331. gas outlet, 332. heavy hydrocarbon outlet, 333. vent outlet, 34. differential pressure gauge;

[0030] 4. Molecular sieve tower, 41. First opening, 411. First dehydration valve, 412. First regeneration valve, 42. Second opening, 421. Second dehydration valve, 422. Second regeneration valve, 43. Drain port, 44. Vent port;

[0031] 51. dust filter, 52. heating device, 53. air cooler, 54. gas-liquid separator, 541. separation gas port, 542. separation liquid port. DETAILED DESCRIPTION

[0032] Various exemplary embodiments of the present disclosure will now be described in detail with reference to the accompanying drawings. It should be noted that the relative arrangement of components and steps, numerical expressions and numerical values ​​set forth in these embodiments do not limit the scope of the present disclosure unless otherwise specifically stated.

[0033] The following description of at least one exemplary embodiment is merely illustrative in nature and is in no way intended to limit the present disclosure, its application, or uses.

[0034] Technologies, methods, and equipment known to ordinary technicians in the relevant art may not be discussed in detail, but where appropriate, the technologies, methods, and equipment should be considered as part of the specification.

[0035] It should be noted that like reference numerals and letters refer to similar items in the following figures, and therefore, once an item is defined in one figure, it need not be further discussed in subsequent figures.

[0036] In this document, “upper”, “lower”, “front”, “back”, “left”, “right”, etc. are only used to indicate the relative position relationship between related parts, rather than to limit the absolute positions of these related parts.

[0037] In this article, "first", "second", etc. are only used to distinguish each other, and do not indicate the importance and order, or the premise of each other's existence.

[0038] In this document, “equal”, “same”, etc. are not strictly limited in a mathematical and / or geometric sense, but also include errors that can be understood by those skilled in the art and are allowed in manufacturing or use.

[0039] The present disclosure provides a carbon dioxide processing system for oil displacement agents, including a dehydration skid and a purification skid. Carbon dioxide used in industry generally comes from adjacent natural carbon dioxide gas reservoirs, natural gas extraction byproducts, surrounding factories, etc. These carbon dioxide gases have low purity and contain impurities such as methane, ethane, hydrogen sulfide, and heavy hydrocarbons. Such low-purity carbon dioxide cannot be used as an oil displacement agent. The carbon dioxide gas processed by the system of the present disclosure is relatively pure carbon dioxide after membrane adsorption. The carbon dioxide after membrane adsorption contains a small amount of liquid heavy hydrocarbons. As long as the heavy hydrocarbons are removed, the requirements for subsequent purification can be met. These carbon dioxides also have a high water content and are easy to freeze and block pipelines during the cooling and purification steps. Therefore, the carbon dioxide needs to be dehydrated first and then purified.

[0040] Specifically, the present disclosure uses a molecular sieve tower to dehydrate carbon dioxide. The dehydration skid includes a molecular sieve tower, which is configured to be connected to a connecting pipeline, and carbon dioxide is configured to enter the molecular sieve tower through the connecting pipeline to remove moisture from the carbon dioxide. The molecular sieve in the molecular sieve tower can use a 4A molecular sieve, that is, a molecular sieve with a pore size of 4A. The 4A molecular sieve can adsorb a large amount of water molecules, but will not adsorb carbon dioxide molecules, so it can be used for carbon dioxide dehydration. The dehydrated carbon dioxide dry gas can enter the purification skid through the connecting pipeline.

[0041] The purification skid includes a heat exchange device, a purification tower and a reboiler. The heat exchange device is provided with a first heat exchange channel and a second heat exchange channel, wherein the inlet of the first heat exchange channel is configured to be connected to the dehydration skid through a connecting pipeline, and the carbon dioxide flowing out of the dehydration skid is configured to enter the first heat exchange channel through the connecting pipeline for liquefaction. The dry gas from the dehydration skid is transported to the first heat exchange channel to be cooled to liquefaction. Specifically, before entering the first heat exchange channel, the carbon dioxide is about 5°C and is in a gaseous state; after cooling through the first heat exchange channel, the carbon dioxide is about -20°C and is in a liquid state.

[0042] The carbon dioxide cooled to a liquid state will be transported to the purification tower. Specifically, the tower inlet at the top of the purification tower is constructed to be connected to the outlet of the first heat exchange channel through a connecting pipeline. The liquid carbon dioxide is configured to flow downward after being sent into the purification tower, and the non-condensable gas in the liquid carbon dioxide is configured to flow upward and flow out from the tower outlet. The middle position of the purification tower is filled with fillers. The carbon dioxide liquid flowing out of the outlet of the first heat exchange channel contains a certain amount of non-condensable gas impurities. Under the filtering effect of the fillers, part of the non-condensable gas can be separated from the carbon dioxide. A low temperature environment must always be maintained in the purification tower to keep the carbon dioxide in a liquid state during the gas-liquid separation process.

[0043] The reboiler is configured to be located at the bottom of the purification tower, and the liquid carbon dioxide separated by the purification tower is configured to be transported to the reboiler for heating. It should be noted that the reboiler only slightly heats the carbon dioxide liquid. In a specific embodiment of the present disclosure, the reboiler heats the carbon dioxide from -20°C to -12°C, and the carbon dioxide remains in a liquid state after being heated in the reboiler. In this way, the non-condensable gas mixed in the carbon dioxide can be further removed, thereby purifying the carbon dioxide.

[0044] The liquid outlet of the reboiler is configured to communicate with the second heat exchange channel, and the purified carbon dioxide is configured to be transported to the second heat exchange channel for cooling. The liquid flowing out of the liquid outlet of the reboiler is the purified carbon dioxide, which needs to be transported to the storage and transportation unit for storage and transportation. The carbon dioxide in the storage and transportation unit remains in a liquefied state and needs to be maintained at a low temperature. Therefore, the carbon dioxide heated to -12°C after purification can be transported to the second heat exchange channel and cooled to -20°C again.

[0045] The present disclosure integrates the dehydration skid and the purification skid of carbon dioxide, so that the process of industrial treatment of carbon dioxide is no longer separated, and the degree of integration of industrial treatment of carbon dioxide is improved. It also realizes the dehydration step before carbon dioxide purification, thereby preventing carbon dioxide gas with excessive water content from freezing and blocking the connecting pipeline when cooling. The present disclosure realizes the heat exchange of multiple process flows in one heat exchange device by setting multiple heat exchange channels on the heat exchange device, thereby saving energy consumption of the purification system and reducing the purification cost.

[0046] The specific embodiments of the present disclosure are described below in conjunction with the accompanying drawings.

[0047] refer to Figure 1 and Figure 2 The present disclosure provides a carbon dioxide treatment system for oil displacement agents, comprising: Figure 2 The dewatering skid 11 shown, and Figure 1 The purification skid 10 is shown. The carbon dioxide used in industry generally comes from adjacent natural carbon dioxide reservoirs, natural gas extraction byproducts, surrounding factories, etc. The purity of these carbon dioxide gases is relatively low, and they contain impurities such as methane, ethane, hydrogen sulfide, and heavy hydrocarbons. Such low-purity carbon dioxide cannot be used as an oil displacement agent. The carbon dioxide gas processed by the system disclosed in the present invention is relatively pure carbon dioxide after membrane adsorption. The carbon dioxide after membrane adsorption contains a small amount of liquid heavy hydrocarbons. As long as the heavy hydrocarbons are removed, the requirements for subsequent purification can be met. These carbon dioxides also have a high water content, which is easy to freeze and block the pipeline during the cooling and purification step. Therefore, the carbon dioxide needs to be dehydrated first and then purified.

[0048] Specifically, Figure 2 As shown, the present disclosure uses a molecular sieve tower 4 to dehydrate carbon dioxide. The dehydration skid 11 includes a molecular sieve tower 4, which is configured to be connected to a connecting pipeline, and carbon dioxide is configured to enter the molecular sieve tower 4 through the connecting pipeline to remove moisture from the carbon dioxide. The molecular sieve in the molecular sieve tower 4 can be a 4A molecular sieve, that is, a molecular sieve with a pore size of 4A. The 4A molecular sieve can adsorb a large amount of water molecules, but will not adsorb carbon dioxide molecules, so it can be used for carbon dioxide dehydration. The dehydrated carbon dioxide dry gas can enter the purification skid 10 through the connecting pipeline.

[0049] like Figure 1 As shown, the purification skid 10 includes a heat exchange device 2, a purification tower 31 and a reboiler 32. The heat exchange device 2 is provided with a first heat exchange channel 21 and a second heat exchange channel 22, wherein the inlet of the first heat exchange channel 21 is configured to be connected to the dehydration skid 11 through a connecting pipeline, and the carbon dioxide flowing out of the dehydration skid 11 is configured to enter the first heat exchange channel 21 through a connecting pipeline for liquefaction. The dry gas from the dehydration skid 11 is transported to the first heat exchange channel 21 to be cooled to liquefaction. Specifically, before entering the first heat exchange channel, the carbon dioxide is about 5°C and is in a gaseous state; and after being cooled through the first heat exchange channel, the carbon dioxide is about -20°C and is in a liquid state.

[0050] The carbon dioxide cooled to a liquid state will be transported to the purification tower 31. Specifically, the tower inlet 311 above the purification tower 31 is constructed to be connected to the outlet of the first heat exchange channel 21 through a connecting pipeline. The liquid carbon dioxide is configured to flow downward after being sent into the purification tower 31, and the non-condensable gas in the liquid carbon dioxide is configured to flow upward and flow out from the tower outlet 312. The middle position of the purification tower 31 is filled with fillers. The carbon dioxide liquid flowing out of the outlet of the first heat exchange channel 21 contains a certain amount of non-condensable gas impurities. Under the filtering effect of the fillers, part of the non-condensable gas can be separated from the carbon dioxide. The purification tower 31 always needs to maintain a low temperature environment so that the carbon dioxide remains in a liquid state during the gas-liquid separation process.

[0051] The reboiler 32 is configured to be located at the bottom of the purification tower 31, and the liquid carbon dioxide separated by the purification tower 31 is configured to be transported to the reboiler 32 for heating. It should be noted that the reboiler 32 will only slightly heat the carbon dioxide liquid. In a specific embodiment of the present disclosure, the reboiler 32 heats the carbon dioxide from -20°C to -12°C, and the carbon dioxide remains in a liquid state after heating in the reboiler 32. In this way, the non-condensable gas mixed in the carbon dioxide can be further removed, thereby purifying the carbon dioxide. A weir plate 322 is provided in the reboiler 32. After the liquid carbon dioxide from which the non-condensable gas is removed reaches a certain liquid level, it can overflow from the weir plate 322, and the overflowed carbon dioxide liquid is discharged from the liquid outlet 321 of the reboiler 32.

[0052] The liquid outlet 321 of the reboiler 32 is constructed to be connected to the second heat exchange channel 22, and the purified carbon dioxide is configured to be transported to the second heat exchange channel 22 for cooling. The liquid flowing out of the liquid outlet 321 of the reboiler 32 is the purified carbon dioxide, and the purified carbon dioxide needs to be transported to the storage and transportation unit 16 for storage and transportation. The carbon dioxide in the storage and transportation unit 16 remains in a liquefied state and needs to maintain a relatively low temperature. Therefore, the carbon dioxide heated to -12°C after purification can be transported to the second heat exchange channel 22 and cooled to -20°C again. The purification rate of carbon dioxide after purification by the purification skid 10 of the present invention is greater than 99%, and it can be transported to the downstream mining process and used as an oil displacement agent. The high-purity carbon dioxide oil displacement agent can greatly improve the efficiency of mining.

[0053] The present disclosure integrates the dehydration skid 11 of carbon dioxide with the purification skid 10, so that the process of industrial treatment of carbon dioxide is no longer separated, and the degree of integration of industrial treatment of carbon dioxide is improved. It also realizes the dehydration step before carbon dioxide purification, thereby preventing carbon dioxide gas with excessive water content from freezing and blocking the connecting pipeline when the temperature is lowered. The present disclosure realizes the heat exchange of multiple process flows in one heat exchange device 2 by setting multiple heat exchange channels on the heat exchange device 2, thereby saving energy consumption of the purification system and reducing the purification cost.

[0054] The specific structures of the purification skid 10 and the dewatering skid 11 will be described in turn below.

[0055] refer to Figure 1 In one embodiment of the present disclosure, the heat exchange device 2 is provided with a third heat exchange channel 23, and the outlet 312 of the purification tower 31 is constructed to be connected to the inlet of the third heat exchange channel 23 through a connecting pipeline. The non-condensable gas obtained by separation and purification in the purification tower 31 is configured to be transported to the third heat exchange channel 23 for heating. Non-condensable gas refers to a gas that cannot be liquefied in a condensing device under certain temperature and pressure conditions. Common non-condensable gases include nitrogen, methane, carbon monoxide, hydrogen and other alkanes. The separated non-condensable gas has a lower temperature, so the non-condensable gas can be transported to the third heat exchange channel 23 for heat exchange and heating, thereby effectively utilizing the cold. After the heated non-condensable gas is discharged from the outlet of the third heat exchange channel 23, it can be transported to the venting system 13 through a connecting pipeline, so that the non-condensable gas is discharged in a green and safe manner.

[0056] In one embodiment of the present disclosure, the purification skid 10 uses liquid propane as a cold source for the heat exchange device 2. The heat exchange device 2 is provided with a fourth heat exchange channel 24, the inlet of which is configured to be connected to the propane refrigeration skid 15 through a connecting pipeline, and the propane liquid flowing out of the propane refrigeration skid 15 is configured to enter the fourth heat exchange channel 24 through the connecting pipeline to serve as a cold source. The propane transported from the propane refrigeration skid 15 to the fourth heat exchange channel 24 is a liquid at approximately -36°C, and the extremely cold propane liquid can serve as the main cold source for the heat exchange device 2. The propane can be heated to 11°C in the fourth heat exchange channel 24, at which time the propane is partially vaporized, and the propane can absorb a large amount of heat during the vaporization process, thereby cooling other heat exchange channels. The vaporized propane needs to be transported back to the propane refrigeration skid 15 to be liquefied again.

[0057] Specifically, the outlet of the fourth heat exchange channel 24 is configured to be connected to the propane refrigeration skid 15 through a connecting pipeline, and the propane heated by the fourth heat exchange channel 24 is configured to be transported to the propane refrigeration skid 15 for re-liquefaction. Propane has the advantages of low price, natural environmental protection, high refrigeration efficiency, etc., and is suitable as a refrigerant in industrial production processes. The present disclosure can recycle propane without introducing a large amount of refrigerant from the outside, thereby saving the cost of refrigeration.

[0058] In one embodiment of the present disclosure, before the carbon dioxide is passed into the dehydration skid 11 for dehydration, it can also be treated to remove heavy hydrocarbons. The water-containing carbon dioxide is stored in the compressor 12. The gas entering the carbon dioxide processing system from the compressor 12 needs to enter the purification skid 10 to remove heavy hydrocarbons first, and then go to the dehydration skid 11 for dehydration.

[0059] Specifically, the heat exchange device 2 is provided with a fifth heat exchange channel 25, the inlet of which is configured to be connected to the compressor 12 through a connecting pipeline, and the carbon dioxide gas source flowing out of the compressor 12 is configured to enter the fifth heat exchange channel 25 through a connecting pipeline for cooling. The water-containing carbon dioxide gas entering the purification skid 10 from the compressor 12 first needs to enter the heat exchange device 2 for pre-cooling, so that the heavy hydrocarbons mixed therein are condensed into liquid, in preparation for the subsequent heavy hydrocarbon separation step. The water-containing carbon dioxide gas is transported to the fifth heat exchange channel 25 and cooled from 30-40°C to 0°C.

[0060] During the precooling process, if the incoming air contains too much free water, the fifth heat exchange channel 25 may be ice-blocked, resulting in a failure of the heat exchange device 2. In a specific embodiment of the present disclosure, a differential pressure gauge 34 is provided between the inlet and outlet of the fifth heat exchange channel 25, and a hot blowing device is provided on the fifth heat exchange channel 25. When the differential pressure gauge 34 shows that the pressure difference is greater than the normal value, the hot blowing device is started to eliminate the freezing blockage failure in the fifth heat exchange channel 25. The present disclosure provides that a differential pressure gauge 34 is provided between the inlet and outlet of the fifth heat exchange channel 25, and real-time monitoring is performed. Once ice blockage occurs in the fifth heat exchange channel 25, the gas cannot pass through the fifth heat exchange channel 25 smoothly, which will cause a large pressure difference between the outlet and the inlet of the fifth heat exchange channel 25. Therefore, when the pressure difference of the differential pressure gauge 34 is greater than the normal value, it means that an ice blockage failure has occurred in the fifth heat exchange channel 25, and the hot blowing device needs to be started in time. The hot blowing device can blow out hot steam, thereby relieving the ice blockage in the pipeline and eliminating the failure.

[0061] The purification skid 10 of the present disclosure also includes a heavy hydrocarbon separator 33, and the pre-cooled carbon dioxide gas can be transported to the heavy hydrocarbon separator 33 to remove heavy hydrocarbons. Specifically, the inlet of the heavy hydrocarbon separator 33 is constructed to be connected to the outlet of the fifth heat exchange channel 25 through a connecting pipeline; the cooled carbon dioxide is configured to be sent to the heavy hydrocarbon separator 33 for separation and purification, and the heavy hydrocarbon separator 33 can fully flash out the carbon dioxide gas and remove the liquid heavy hydrocarbons mixed in the carbon dioxide. When pre-cooled to 0°C, the heavy hydrocarbons mixed in the carbon dioxide gas condense into liquid. After the carbon dioxide mixed with heavy hydrocarbons is transported to the heavy hydrocarbon separator 33, gas-liquid separation can be carried out in the heavy hydrocarbon separator 33, thereby removing the heavy hydrocarbons. The carbon dioxide gas treated by the heavy hydrocarbon separator 33 still contains a large amount of free water, and cannot be directly purified. It needs to be transported to the molecular sieve tower 4 of the dehydration skid 11 for dehydration treatment.

[0062] In one embodiment of the present disclosure, the heavy hydrocarbon port 332 at the bottom of the heavy hydrocarbon separator 33 is constructed to be connected to the sewage system 14 through a connecting pipeline, and the separated heavy hydrocarbons are configured to be transported to the sewage system 14 for treatment. The sewage system 14 can centrally treat the collected waste liquid. The heavy hydrocarbon mixture may contain substances that can be further purified and utilized. The sewage system 14 can purify the waste liquid; the heavy hydrocarbon mixture may not contain substances that need to be further utilized. Since heavy hydrocarbons are harmful to the environment, they cannot be discharged directly. The sewage system 14 performs harmless treatment on them before they can be discharged to the outside. The sewage system 14 is set to ensure the normal operation of the system. Centralized treatment of wastewater can ensure the greenness of the system and will not pollute the environment.

[0063] In one embodiment of the present disclosure, the cold capacity of the carbon dioxide gas can also be utilized before it is sent to the dehydration. The heat exchange device 2 is also provided with a sixth heat exchange channel 26, and the gas outlet 331 at the top of the heavy hydrocarbon separator 33 is constructed to be connected to the sixth heat exchange channel 26, and the separated carbon dioxide gas is configured to be transported to the sixth heat exchange channel 26 for heating. The 0°C carbon dioxide gas separated in the heavy hydrocarbon separation 33 is sent from the gas outlet 331 to the sixth heat exchange channel 26, and is heated to about 20°C in the sixth heat exchange channel 26. This ensures that the cold capacity in the system is not wasted, thereby saving energy and reducing refrigeration costs.

[0064] The outlet of the sixth heat exchange channel 26 is configured to be connected to the molecular sieve tower 4 in the dehydration skid 11 through a connecting pipeline, and the heated carbon dioxide gas is configured to be sent to the molecular sieve tower 4 of the dehydration skid 11 for dehydration. The carbon dioxide gas raised to room temperature needs to be dehydrated before the purification step can be carried out. The carbon dioxide dry gas after dehydration in the dehydration skid 11 is re-input into the heat exchange device 2 of the purification skid 10, and is transported to the first heat exchange channel 21 and the subsequent purification tower 31 and reboiler 32 for purification.

[0065] The heat exchange device 2 provided by the present disclosure is provided with a total of six heat exchange channels, which effectively concentrates most of the heat exchange processes in the purification system to the same heat exchange device 2. Specifically, among the six heat exchange channels, the first heat exchange channel 21, the second heat exchange channel 22 and the fifth heat exchange channel 25 are cooling channels. After the material passes through the above three heat exchange channels along the flow direction, the temperature will decrease; the third heat exchange channel 23, the fourth heat exchange channel 24 and the sixth heat exchange channel are heating channels. After the material passes through the above three heat exchange channels along the flow direction, the temperature will increase. The present disclosure concentrates the heat exchange of multiple process flows to one place, which can make full use of the cold capacity, reduce the energy consumption of the purification skid 10, and reduce the purification cost. Moreover, such a centralized setting can also save the floor space of the purification system and is more convenient for standardized construction. In practical applications, compared with setting up multiple heat exchange equipment scattered throughout the system, the heat exchange device 2 that can perform heat exchange in a centralized manner in the present disclosure can shorten the purification process, reduce equipment costs, have high heat exchange efficiency, and low operating energy consumption.

[0066] In one embodiment of the present disclosure, the carbon dioxide processing system also includes a venting system 13, which can be connected to the equipment that needs to be vented in the purification skid 10 and the dehydration skid 11 to ensure that the pressure of each equipment in the system is normal. For the purification skid 10, the venting system 13 is constructed to be connected to the vent outlet 333 of the heavy hydrocarbon separator 33 to adjust the pressure in the heavy hydrocarbon separator 33. The gas pressure in the heavy hydrocarbon separator 33 needs to be maintained at a certain level to work normally. When too much gas is introduced into the heavy hydrocarbon separator 33 per unit time, the internal pressure of the heavy hydrocarbon separator 33 will be too high, and a venting operation is required at this time. The vent outlet 333 of the heavy hydrocarbon separator 33 is opened, and the gas is discharged to the venting system 13 until the internal pressure of the heavy hydrocarbon separator 33 returns to normal.

[0067] In addition to the heavy hydrocarbon separator 33, the connecting pipelines at some locations in the purification skid 10 also need to be emptied. Figure 1As shown, the carbon dioxide purification system also includes a discharge pipeline 17, one end of which is connected to the venting system 13, and the other end is connected to the connecting pipeline. Specifically, this section of the connecting pipeline is connected to the dehydration skid 11. Carbon dioxide dry gas enters the purification skid 10 from the dehydration skid 11. When too much incoming gas is introduced per unit time, the processing efficiency of the purification tower 31 may not be able to meet the incoming gas, which will cause too much gas to accumulate in the connecting pipeline, and then cause the air pressure in the connecting pipeline to be too high. In order to ensure the normal operation of the system, a discharge pipeline 17 can be connected to the position where the gas enters the skid, and a vent valve is provided on the discharge pipeline 17. When the internal air pressure of the system is too high, the vent valve can be opened to discharge the gas in the system to the venting system 13, thereby adjusting the air pressure in the system. The venting system 13 can ensure that the air pressure in the system is normal, and the system can monitor and adjust the air pressure in real time, thereby ensuring the normal operation of the system and improving the safety of the system.

[0068] The above embodiments describe the structure of the purification skid 10 in detail. Figure 2 For reference, the structure and working process of the dewatering skid 11 are described in detail.

[0069] The carbon dioxide gas after heavy hydrocarbons are removed in the purification skid 10 and the cold energy is utilized in the sixth heat exchange channel 26 is sent to the dehydration skid 11 for dehydration. At the entry skid, an instrument for detecting the water content of the gas is provided. In most cases, the water content of the incoming gas is higher than the standard and needs to be sent to the molecular sieve tower 4 for dehydration. However, the water content of the incoming gas may be directly qualified. In this case, there is no need to perform the dehydration step and the carbon dioxide can be directly sent to the purification skid 10.

[0070] In one embodiment of the present disclosure, Figure 1 As shown, the dehydration skid 11 includes a bypass line, one end of which is configured to be connected to a connecting line located upstream of the molecular sieve tower 4, and the other end is configured to be connected to the purification skid 10. When the water content of the incoming carbon dioxide gas is qualified, the carbon dioxide is configured to be passed into the bypass line. The water content of carbon dioxide will be tested when it enters the station. In most cases, the water content of the gas will exceed the qualified standard and needs to be dehydrated before it can be transported to the purification skid 10 for purification. However, when the water content of the incoming gas is qualified, it is no longer necessary to dehydrate it. In order to save process and cost, the system disclosed in the present invention is provided with a bypass line, and a bypass valve 19 is provided on the bypass line. When the water content of the incoming gas is qualified, the bypass valve 19 is opened, and the carbon dioxide is directly transported to the purification skid 10 for purification.

[0071] When the water content of the incoming gas is unqualified, the carbon dioxide needs to be dehydrated by a molecular sieve tower 4. The molecular sieve tower 4 is configured to be connected to a connecting pipeline, and the external carbon dioxide is configured to enter the molecular sieve tower 4 through the connecting pipeline to remove the water in the carbon dioxide to prevent freezing and blocking of the pipeline in subsequent steps.

[0072] In one embodiment of the present disclosure, two molecular sieve towers 4 are provided, and when one molecular sieve tower 4 is dehydrating carbon dioxide, the other molecular sieve tower 4 is configured to regenerate the molecular sieve. After a period of adsorption, the molecular sieve will reduce its adsorption capacity, which will lead to a low dehydration efficiency. At this time, it is necessary to remove the water molecules in the sieve holes to regenerate the molecular sieve. The water-containing molecular sieve can be dehydrated when heated, so high-temperature gas can be used to blow out the moisture in the molecular sieve to achieve regeneration. The present disclosure sets two molecular sieve towers 4, and when one of the molecular sieve towers 4 is dehydrating carbon dioxide, the other molecular sieve tower 4 is regenerated. In this way, it can be ensured that the carbon dioxide dehydration system can operate continuously, and there is always a molecular sieve tower 4 available for dehydration, and there is no situation where all molecular sieve towers 4 are being regenerated and cannot be used for dehydration.

[0073] The present disclosure heats part of the dehydrated carbon dioxide and blows the heated carbon dioxide directly into the molecular sieve tower 4 that needs to be regenerated, thereby regenerating the molecular sieve. Specifically, the dehydration skid 11 also includes a heating device 52, and the heating device 52 is constructed to be connected to two molecular sieve towers 4 respectively, wherein part of the carbon dioxide dehydrated in one molecular sieve tower 4 is configured to be heated by the heating device 52 and then sent to another molecular sieve tower 4 to regenerate the other molecular sieve tower 4. The molecular sieve regeneration process does not require an additional gas source from the outside, but directly recycles a small amount of carbon dioxide in the system, which not only saves the regeneration cost, but also ensures that the gas in the system is pure and will not be contaminated by external gas sources.

[0074] The present disclosure sets two molecular sieve towers 4, and when one molecular sieve tower 4 dehydrates carbon dioxide, the other molecular sieve tower 4 uses partially dehydrated carbon dioxide gas to regenerate the molecular sieve, thereby directly using carbon dioxide inside the system to regenerate the molecular sieve, without introducing other equipment such as a blower, saving regeneration costs. Moreover, the two molecular sieve towers 4 can alternately perform dehydration work, and dehydration will not be suspended due to the molecular sieve regeneration step, which enables the dehydration skid 11 to operate continuously and improves production efficiency.

[0075] In one embodiment of the present disclosure, the molecular sieve tower 4 includes a first opening 41 and a second opening 42, and both molecular sieve towers 4 are provided with completely identical first openings 41 and second openings 42. The first opening 41 and the second opening 42 can both serve as an inlet for carbon dioxide to enter the molecular sieve tower 4 and as an outlet for flowing out of the molecular sieve tower 4. Specifically, when the molecular sieve tower 4 in the present disclosure is dehydrating carbon dioxide, the first opening 41 is the inlet and the second opening 42 is the outlet; when the molecular sieve is regenerated, the second opening 42 is the inlet and the first opening 41 is the outlet. The specific processes of dehydration and regeneration of the molecular sieve tower 4 will be introduced below.

[0076] When the molecular sieve tower 4 is dehydrating carbon dioxide, the first opening 41 is constructed to be connected to the connecting pipeline, and the external carbon dioxide is configured to enter the molecular sieve tower 4 from the first opening 41 through the connecting pipeline for dehydration, and the dehydrated carbon dioxide is configured to be discharged from the second opening 42. Specifically, a first dehydration valve 411 is provided on the connecting pipeline at the upstream position of the molecular sieve tower 4, and two first dehydration valves 411 can be provided, respectively corresponding to the two molecular sieve towers 4. When one of the first dehydration valves 411 is opened, carbon dioxide can enter the molecular sieve tower 4 corresponding to the valve for dehydration. At this time, the other first dehydration valve 411 is closed, thereby ensuring that carbon dioxide does not flow from the purification skid 10 to the first opening 41 of another molecular sieve tower 4.

[0077] A second dehydration valve 421 is also provided on the connecting pipeline at the downstream position of the molecular sieve tower 4. Two second dehydration valves 421 may be provided, which are respectively provided corresponding to the two molecular sieve towers 4. When one of the second dehydration valves 421 is opened, the carbon dioxide discharged from the second opening 42 of the corresponding molecular sieve tower 4 can continue to be transported to the downstream. When a molecular sieve tower 4 is dehydrating carbon dioxide, its corresponding first dehydration valve 411 and second dehydration valve 421 need to be opened at the same time to ensure that the dehydration process can run smoothly. The first dehydration valve 411 and the second dehydration valve 421 corresponding to the other molecular sieve tower 4 for regeneration should be closed at the same time.

[0078] In one embodiment of the present disclosure, the dehydration skid 11 further includes a dust filter 51, which is configured to be connected to the second opening 42 through a connecting pipeline, and the carbon dioxide discharged from the second opening 42 is configured to be filtered by the dust filter 51 and then sent to the first heat exchange channel 21 of the purification skid 10. The carbon dioxide dry gas that has been dehydrated in the molecular sieve tower 4 may be mixed with certain dust impurities. This is because when carbon dioxide passes through the molecular sieve, it may bring out solid powder therein. Therefore, before the gas is transported to the purification skid 10, it is necessary to filter it with a dust filter 51 to remove the solid powder in the gas.

[0079] The molecular sieve regeneration process of the molecular sieve tower 4 will be described below.

[0080] In one embodiment of the present disclosure, the dehydration skid 11 further includes a regeneration pipeline connecting the second openings 42 of the two molecular sieve towers 4, and the heating device 52 is disposed in the regeneration pipeline. It should be noted that the regeneration pipeline, the connecting pipeline, and the discharge pipeline 17 mentioned above are all pipelines in the system of the present disclosure, and the materials and structures of the various pipelines are not substantially different, and are only functionally distinguished. Among them, the pipeline used for the molecular sieve regeneration process is named the regeneration pipeline.

[0081] The dehydrated carbon dioxide in one molecular sieve tower 4 is configured to be discharged through its second opening 42, heated by the heating device 52 and sent to the second opening 42 of another molecular sieve tower 4 to regenerate the other molecular sieve tower 4. Figure 2 As shown, a diversion port 18 is provided at the intersection of the connecting pipeline and the regeneration pipeline. The dehydrated carbon dioxide gas is transported in the connecting pipeline. Most of the gas will flow along the connecting pipeline to the dust filter 51 and the subsequent purification skid 10. A small part of the gas will flow into the regeneration pipeline at the diversion port 18 and be sent to the heating device 52 by the regeneration pipeline for molecular sieve regeneration. The carbon dioxide flowing into the regeneration pipeline at the diversion port 18 is only a small part of the total gas volume, about 80Nm 3 / h.

[0082] A second regeneration valve 422 is provided on the regeneration pipeline connecting the second openings 42 of the two molecular sieve towers 4. Two second regeneration valves 422 are provided, which are respectively provided corresponding to the two molecular sieve towers 4. When one of the molecular sieve towers 4 is dehydrated, the second regeneration valve 422 corresponding to the other molecular sieve tower 4 is opened to allow part of the heated carbon dioxide gas to enter from the second opening 42 of the molecular sieve tower 4, thereby regenerating the molecular sieve. At this time, the second regeneration valve 422 corresponding to the molecular sieve tower 4 that is dehydrated is closed to prevent carbon dioxide from flowing back to the second opening 42 of the dehydration tower.

[0083] The heating device 52 can heat the carbon dioxide gas to about 250°C, and the heated carbon dioxide enters from the second opening 42 of the molecular sieve tower 4, and the high-temperature gas can blow out the water in the molecular sieve. The high-temperature water-containing carbon dioxide gas can be blown out of the molecular sieve tower 4 from the first opening 41 and continue to be transported downstream. A first regeneration valve 412 is also provided on the regeneration pipeline connected to the first opening 41, and two first regeneration valves 412 are provided, which correspond to the two molecular sieve towers 4 respectively. The first regeneration valve 412 and the second regeneration valve 422 corresponding to the molecular sieve tower 4 for molecular sieve regeneration should be opened synchronously to ensure that the regeneration process can proceed smoothly; the first regeneration valve 412 and the second regeneration valve 422 corresponding to the molecular sieve tower 4 for dehydration process should be closed synchronously.

[0084] The system provided by the present disclosure can control the flow direction of carbon dioxide and control the two molecular sieve towers 4 to alternately dehydrate and regenerate by controlling the opening and closing of the above eight valves. For example, the two molecular sieve towers 4 are tower A and tower B. When it is necessary to control tower A to dehydrate carbon dioxide and tower B to regenerate molecular sieves, it is necessary to open the first dehydration valve 411 and the second dehydration valve 421 corresponding to tower A, and open the first regeneration valve 412 and the second regeneration valve 422 corresponding to tower B. In this way, the direction of carbon dioxide can be controlled at any time by opening and closing the valves, thereby completing carbon dioxide dehydration and molecular sieve regeneration at the same time, improving production efficiency, and no other external gas sources need to be introduced during the regeneration process, saving regeneration costs.

[0085] In one embodiment of the present disclosure, when both second regeneration valves 422 are closed, that is, when neither of the two molecular sieve towers 4 performs the molecular sieve regeneration process, part of the carbon dioxide gas flowing into the regeneration pipeline at the diversion port 18 cannot enter the second opening 42 of any molecular sieve tower 4. Therefore, a discharge pipeline 17 is also provided in the dehydration skid 11, and one end of the discharge pipeline 17 is configured to be connected to the regeneration pipeline at a downstream position of the heating device 52, and the other end is configured to be connected to the regeneration pipeline at a downstream position of the first opening 41 of the molecular sieve tower 4. The carbon dioxide gas that cannot enter the molecular sieve tower 4 after heating can enter the discharge pipeline 17, bypass the molecular sieve tower 4, and be directly transported to the downstream position of the molecular sieve tower 4. The provision of the discharge pipeline 17 ensures that the system can operate normally even when both second regeneration valves 422 are closed.

[0086] In one embodiment of the present disclosure, the dehydration skid 11 also includes an air cooler 53 connected to the first opening 41 of the molecular sieve tower 4, and the carbon dioxide entering the molecular sieve tower 4 from the second opening 42 is configured to flow to the air cooler 53 through the first opening 41 for cooling. The carbon dioxide gas heated to about 250°C in the heating device 52 becomes a high-temperature mixed gas containing a large amount of water after removing the water in the molecular sieve tower 4. Therefore, it is necessary to initially separate the water in the mixed gas before the carbon dioxide can be transported to the subsequent process. Before separation, the gas needs to be cooled first to condense the water. The present disclosure uses an air cooler 53 to cool the gas. The air cooler 53 is the abbreviation of an air cooler, which is the most widely used heat exchange equipment for condensation and cooling in petrochemical and oil and gas processing production. The high-temperature mixed gas is passed into the air cooler 53 for heat exchange with the air, and the temperature is reduced to about 50°C, and a large amount of water is condensed.

[0087] In one embodiment of the present disclosure, the dehydration skid 11 further includes a gas-liquid separator 54, which is configured to be located downstream of the air cooler 53 and is configured to perform gas-liquid separation on the carbon dioxide cooled by the air cooler 53. Figure 2As shown, the gas-liquid separator 54 includes a separation gas port 541 and a separation liquid port 542. The carbon dioxide gas obtained by gas-liquid separation is configured to be transported from the separation gas port 541 to the compressor 12 through a regeneration pipeline; the liquid obtained by gas-liquid separation is configured to be transported from the separation liquid port 542 to the sewage system 14 through a regeneration pipeline.

[0088] The mixture cooled to about 50°C in the air cooler 53 is transported to the gas-liquid separator 54 for gas-liquid separation, wherein the separated liquid phase is mainly water and also includes some hydrocarbon impurities; the separated gas phase is carbon dioxide gas. The carbon dioxide gas obtained by gas-liquid separation still contains water and does not meet the standards for purification. This part of carbon dioxide needs to be recollected to the compressor 12 for subsequent treatment. The separation gas port 541 is located at the top of the gas-liquid separator 54, and the separation liquid port 542 is located at the bottom of the gas-liquid separator 54. The separated liquid is transported to the sewage system 14 via the regeneration pipeline for subsequent treatment.

[0089] In the dehydration skid 11, in addition to the liquid separated by the gas-liquid separator 54, which will be sent to the sewage system 14, the molecular sieve tower 4 that performs the carbon dioxide dehydration process will also produce some waste liquid, and these waste liquids will also be discharged to the sewage system 14. Specifically, in one embodiment of the present disclosure, a sewage outlet 43 is provided at the bottom of the molecular sieve tower 4, and the waste liquid generated during the dehydration process is configured to be transported from the sewage outlet 43 to the sewage system 14. The bottoms of the two molecular sieve towers 4 are both provided with sewage outlets 43, and the sewage outlets 43 are connected to the sewage system 14 through a connecting pipeline. The waste liquid generated in various places in the dehydration skid 11 and the purification skid 10 can be discharged to the sewage system 14 for centralized treatment, and each device can discharge waste in time, ensuring the normal operation of the carbon dioxide treatment system. In addition, centralized treatment of wastewater can also ensure the green environmental protection of the system and will not pollute the environment.

[0090] In one embodiment of the present disclosure, the venting system 13 is configured to communicate with the connecting pipeline and the top of the two molecular sieve towers 4 to adjust the pressure in the dehydration skid 11 and the molecular sieve tower 4. Specifically, Figure 2As shown, a vent 44 is provided at the top of the molecular sieve tower 4, and a vent 44 is provided at the top of the two molecular sieve towers 4. The two vents 44 are respectively connected to the vent system 13 through a connecting pipeline. When the air pressure in the molecular sieve tower 4 is too high, the vent 44 can be opened, and part of the gas is discharged to the vent system 13 until the air pressure in the molecular sieve tower 4 returns to normal. The connecting pipeline can be connected to the vent system 13 through a vent valve. When the air pressure in the second dehydration skid 11 is too high, for example: too much incoming gas is introduced per unit time, and the processing efficiency of the molecular sieve tower 4 cannot meet the incoming gas demand, it may cause too much gas to accumulate in the connecting pipeline, thereby causing the air pressure in the connecting pipeline to be too high; at this time, the vent valve can be opened to discharge the gas in the connecting pipeline directly to the vent system 13, thereby adjusting the air pressure in the system. Setting the vent system 13 can ensure that the air pressure in the carbon dioxide treatment system is normal, and the system can monitor and adjust the air pressure in real time, thereby ensuring the normal operation of the system and improving the safety of the system.

[0091] In one embodiment of the present disclosure, each pipeline in the carbon dioxide treatment system needs to be made of acid-resistant corrosion materials. Each pipeline may include the connecting pipeline, regeneration pipeline, bypass pipeline and discharge pipeline 17 mentioned above, and may also include other unnamed pipelines. Since the system provided by the present disclosure is mainly used for carbon dioxide treatment, specifically including carbon dioxide dehydration and purification, and carbon dioxide reacts with water to generate carbonic acid, the pipelines in the system will be in an acidic environment for a long time. The present disclosure can use stainless steel to make each pipeline. Stainless steel is a metal material with excellent corrosion resistance. It can be used for a long time in acidic media such as sulfuric acid, hydrochloric acid, nitric acid, hydrofluoric acid, etc. with a concentration of less than 50%, and can also be used for a long time in a carbonic acid environment. In addition, stainless steel also has good wear resistance and high temperature resistance, and is suitable for use in the carbon dioxide dehydration system provided by the present disclosure.

[0092] The embodiments of the present disclosure have been described above, and the above description is exemplary, not exhaustive, and is not limited to the disclosed embodiments. Many modifications and changes will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the described embodiments. The choice of terms used herein is intended to best explain the principles of the embodiments, practical applications, or technical improvements in the marketplace, or to enable other persons of ordinary skill in the art to understand the embodiments disclosed herein. The scope of the present disclosure is defined by the appended claims.

Claims

1. A carbon dioxide treatment system for oil displacement agent, characterized in that: include: A dehydration skid (11), the dehydration skid (11) comprising a molecular sieve tower (4), the molecular sieve tower (4) being configured to be in communication with a connecting pipeline, and carbon dioxide being configured to enter the molecular sieve tower (4) through the connecting pipeline to remove water from the carbon dioxide; A purification skid (10), wherein the purification skid (10) comprises a heat exchange device (2), a purification tower (31) and a reboiler (32); The heat exchange device (2) is provided with a first heat exchange channel (21) and a second heat exchange channel (22); the inlet of the first heat exchange channel (21) is configured to be connected to the dehydration skid (11) through a connecting pipeline, and the carbon dioxide gas dehydrated by the molecular sieve tower (4) is configured to enter the first heat exchange channel (21) through the connecting pipeline for liquefaction; The tower inlet (311) at the top of the purification tower (31) is configured to be connected to the outlet of the first heat exchange channel (21) through a connecting pipeline; the liquid carbon dioxide is configured to flow downward after being fed into the purification tower (31), and the non-condensable gas in the liquid carbon dioxide is configured to flow upward and flow out from the tower outlet (312); The reboiler (32) is configured to be located at the bottom of the purification tower (31), and the liquid carbon dioxide separated by the purification tower (31) is configured to be transported to the reboiler (32) for heating; the liquid outlet (321) of the reboiler (32) is configured to be connected to the second heat exchange channel (22), and the purified carbon dioxide is configured to be transported to the second heat exchange channel (22) for cooling.

2. The processing system according to claim 1, characterized in that The heat exchange device (2) is provided with a third heat exchange channel (23); the outlet (312) of the purification tower (31) is configured to be connected to the inlet of the third heat exchange channel (23) through a connecting pipeline; the non-condensable gas obtained by separation and purification in the purification tower (31) is configured to be transported to the third heat exchange channel (23) for heating.

3. The processing system according to claim 1, characterized in that The heat exchange device (2) is provided with a fifth heat exchange channel (25); the inlet of the fifth heat exchange channel (25) is configured to be connected to the compressor (12) through a connecting pipeline, and the carbon dioxide gas source flowing out of the compressor (12) is configured to enter the fifth heat exchange channel (25) through the connecting pipeline for cooling; the purification skid (10) also includes a heavy hydrocarbon separator (33), the inlet of the heavy hydrocarbon separator (33) is configured to be connected to the outlet of the fifth heat exchange channel (25) through a connecting pipeline; the cooled carbon dioxide is configured to be sent to the heavy hydrocarbon separator (33) for separation and purification.

4. The processing system according to claim 3, characterized in that The heat exchange device (2) is also provided with a sixth heat exchange channel (26); the gas outlet (331) at the top of the heavy hydrocarbon separator (33) is configured to be in communication with the sixth heat exchange channel (26), and the separated carbon dioxide gas is configured to be transported to the sixth heat exchange channel (26) for heating; the outlet of the sixth heat exchange channel (26) is configured to be in communication with the dehydration skid (11) through a connecting pipeline, and the heated carbon dioxide gas is configured to be transported to the dehydration skid (11) for dehydration.

5. The processing system according to claim 3, characterized in that A differential pressure gauge (34) is provided between the inlet and outlet of the fifth heat exchange channel (25), and a heat blowing device is provided on the fifth heat exchange channel (25); when the differential pressure gauge (34) shows that the pressure difference is greater than a normal value, the heat blowing device is started to eliminate the freezing blockage fault in the fifth heat exchange channel (25).

6. The processing system according to claim 1, characterized in that The molecular sieve towers (4) are provided in two configurations, wherein when one molecular sieve tower (4) performs dehydration treatment on carbon dioxide, the other molecular sieve tower (4) is configured to perform molecular sieve regeneration; the dehydration skid (11) further comprises a heating device (52), wherein the heating device (52) is configured to be connected to the two molecular sieve towers (4) respectively, wherein part of the carbon dioxide dehydrated in one molecular sieve tower (4) is configured to be heated by the heating device (52) and then sent to the other molecular sieve tower (4) to regenerate the other molecular sieve tower (4).

7. The processing system according to claim 6, characterized in that The molecular sieve tower (4) comprises a first opening (41) and a second opening (42); the first opening (41) is configured to be connected to a connecting pipeline; external carbon dioxide is configured to enter the molecular sieve tower (4) from the first opening (41) through the connecting pipeline for dehydration, and the dehydrated carbon dioxide is configured to be discharged from the second opening (42).

8. The processing system according to claim 7, characterized in that The dehydration skid (11) further comprises a regeneration pipeline connected to the second openings (42) of the two molecular sieve towers (4), and the heating device (52) is arranged in the regeneration pipeline; part of the carbon dioxide after dehydration in one of the molecular sieve towers (4) is configured to be discharged through its second opening (42), heated by the heating device (52) and sent to the second opening (42) of another molecular sieve tower (4) to regenerate the other molecular sieve tower (4).

9. The processing system according to claim 8, characterized in that The dewatering skid (11) further comprises an air cooler (53) and a gas-liquid separator (54); the air cooler (53) is configured to be in communication with the first opening (41) of the molecular sieve tower (4), and the carbon dioxide entering the molecular sieve tower (4) from the second opening (42) is configured to flow to the air cooler (53) through the first opening (41) for cooling; the gas-liquid separator (54) is configured to be located downstream of the air cooler (53), and is configured to perform gas-liquid separation on the carbon dioxide cooled by the air cooler (53).

10. The processing system according to claim 7, characterized in that The dehydration skid (11) further comprises a dust filter (51), wherein the dust filter (51) is configured to be connected to the second opening (42) of the molecular sieve tower (4) through a connecting pipeline, and the carbon dioxide discharged from the second opening (42) is configured to be filtered by the dust filter (51) and then sent to the first heat exchange channel (21) of the purification skid (10).

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