Methods and systems for purifying primary products after crude oil separation and refining

Abstract

This invention relates to the field of crude oil separation and refining, specifically to a method and system for purifying primary products after crude oil separation and refining. The method includes: using carbon dioxide-containing feedstock to perform gas stripping on the primary products after crude oil separation and refining, causing the light components in the primary products to dissolve in carbon dioxide to form a carbon dioxide phase rich in light components, while the heavy components are enriched to obtain a purified oil phase. This invention utilizes the differences in the solubility of carbon dioxide in various components of crude oil, achieving the purification of primary crude oil products and the recovery and reuse of light components through gas stripping. This not only improves the economic value of carbon dioxide but also reduces energy consumption and enhances the environmental friendliness and safety of the production process.

Description

Technical Field

[0001] This invention relates to the field of crude oil separation and refining, and specifically to a method and system for purifying primary products after crude oil separation and refining. Background Technology

[0002] Crude oil extracted from reservoirs must undergo separation and refining to be converted into various chemical raw materials needed by downstream industries. Whether using traditional atmospheric and vacuum distillation or the latest CO2 separation technology, the primary products obtained, especially the heavy oil and residue at the bottom of various distillation towers, contain a certain amount of light components. These light components lower the flash point of the products and increase the risk of deflagration. Moreover, if these light components enter the next stage of industrial processes along with the primary products, it will not only reduce product purity and waste high-value-added light components, but also increase the corresponding pipeline transportation, heating, and separation costs. Therefore, in the crude oil separation and refining process, it is necessary to remove and recover the light components from the primary products. Currently, the commonly used technology is the side-stream stripping method, in which the side-stream products from the separation and refining are fed into a side-stream stripping tower. Superheated steam at 380-450℃ is introduced at the bottom of the tower, and the low-boiling-point light components are removed from the primary products by steam heating. The steam containing the light components is then reinjected into the separation tower, thereby achieving the purification of the primary products and the recovery and utilization of the light components. In this method, the amount of steam used is generally 2-5% of the crude oil mass. Therefore, although the method of using steam for light component stripping can purify primary crude oil products and recover light components, it has high energy consumption, generates a large amount of wastewater and carbon emissions, and the high-temperature operation will accelerate equipment corrosion and increase production and operation risks. Summary of the Invention

[0003] The purpose of this invention is to overcome the problems of high energy consumption, large amounts of wastewater and carbon emissions, equipment corrosion, and poor safety in existing technologies. It provides a method and system for purifying primary products after crude oil separation and refining. This method features low energy consumption, good environmental protection, and high safety. Carbon dioxide, at relatively low temperatures, can extract light components from the dissolved oil phase and effectively separate light and heavy components through density differences.

[0004] To achieve the above objectives, the first aspect of the present invention provides a method for purifying primary products after crude oil separation and refining. The method includes: using carbon dioxide-containing feedstock to perform gas stripping on the primary products after crude oil separation and refining, so that the light components in the primary products after crude oil separation and refining dissolve in carbon dioxide to form a carbon dioxide phase rich in light components, and enriching the heavy components to obtain a purified oil phase.

[0005] A second aspect of the present invention provides a purification system for primary products after crude oil separation and refining. The system includes a stripping unit for stripping the primary products after crude oil separation and refining from a carbon dioxide-containing feedstock, so that the light components in the primary products after crude oil separation and refining dissolve in carbon dioxide to form a carbon dioxide phase rich in light components, and the heavy components are enriched to obtain a purified oil phase; and a crude oil separation and refining unit connected to the stripping unit via a pipeline for providing the primary products after crude oil separation and refining.

[0006] This invention utilizes the differences in solubility of carbon dioxide in various components of crude oil to achieve the purification of primary crude oil products and the recovery and reuse of light components through gas stripping. Furthermore, an optimized scheme enables the recycling of carbon dioxide, not only increasing its economic value but also its utilization rate. This invention eliminates the need for superheated steam, leveraging the differences in solubility and extractability of carbon dioxide for light and heavy components in the oil phase. It can be carried out at lower temperatures and in a dry environment, effectively saving energy and water resources. It achieves the purification of primary products and the recovery and utilization of high-value-added light components, while reducing energy consumption, wastewater, and carbon emissions. It also improves carbon dioxide utilization and economic efficiency, and enhances the environmental friendliness and safety of the production process. Attached Figure Description

[0007] Figure 1 This is a diagram of a preferred embodiment of the air-lifting device (an air-lifting unit) of the present invention.

[0008] Figure 2 This is a preferred embodiment of the present invention, a purification system for primary products after crude oil separation and refining.

[0009] Explanation of reference numerals in the attached figures

[0010] Figure 1 In the middle: 1. First stripping tower; 2. First tray or first packing; 3. First overflow plate; 4. First downcomer; 5. First primary product inlet; 6. First carbon dioxide-containing feed inlet; 7. First oil phase outlet; 8. First carbon dioxide phase outlet; 9. First compressor pump;

[0011] Figure 2 In the middle section: 21. Second stripping tower; 22. Second tray or second packing; 23. Second overflow plate; 24. Second downcomer; 25-28. Second primary product inlet; 29. ​​Second carbon dioxide-containing feed inlet; 10-13. Second oil phase outlet; 14-16. Reinjection gas outlet; 17. Tower top gas outlet; 18. Second compressor pump; 19. Oil separator. Detailed Implementation

[0012] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0013] This invention provides a method for purifying primary products after crude oil separation and refining. The method includes: using carbon dioxide-containing feedstock to perform gas stripping on the primary products after crude oil separation and refining, so that the light components in the primary products after crude oil separation and refining dissolve in carbon dioxide to form a carbon dioxide phase rich in light components, and enriching the heavy components to obtain a purified oil phase.

[0014] This invention utilizes the differences in solubility of carbon dioxide in various components of crude oil to achieve the purification of primary crude oil products and the recovery and reuse of light components in a gas stripping unit. This invention does not require the use of superheated steam. By utilizing the differences in solubility and extraction of light and heavy components in the oil phase by carbon dioxide, it can be carried out at lower temperatures and in a dry environment, effectively saving energy and water resources. It achieves the purification of primary products and the recovery and utilization of high-value-added light components, while reducing energy consumption, wastewater and carbon emissions, and improving carbon dioxide utilization and economic benefits, as well as enhancing the environmental friendliness and safety of the production process.

[0015] In this invention, the conditions for gas stripping can be any conventional selection in the art, as long as the objective of the invention can be achieved. According to a preferred embodiment of the invention, the conditions for gas stripping include: a ratio of the mass flow rate of the carbon dioxide-containing raw material (calculated as carbon dioxide) to the mass flow rate of the primary product of 10:1-1:100, preferably 5:1-1:50, and more preferably 1:1-1:30. By adopting the aforementioned preferred conditions, the carbon dioxide utilization rate can be further improved, the environmental friendliness and safety of the production process can be further enhanced, and energy consumption can be further reduced.

[0016] According to a preferred embodiment of the present invention, the conditions for air lifting include: an air lifting pressure of 0.1-30 MPa, preferably 0.1-15 MPa.

[0017] According to a preferred embodiment of the present invention, the conditions for air stripping include: an air stripping temperature of 0-200°C, preferably 20-100°C.

[0018] According to a preferred embodiment of the present invention, the method further includes: separating the carbon dioxide phase to obtain carbon dioxide, natural gas, and condensate oil. This preferred embodiment can improve the utilization rate of carbon dioxide and obtain high value-added products.

[0019] According to a preferred embodiment of the present invention, the method further includes: using the carbon dioxide for oil displacement. This preferred embodiment can improve the utilization rate of carbon dioxide and increase the efficiency of separating and refining crude oil.

[0020] According to a preferred embodiment of the present invention, the method further includes: using the carbon dioxide phase for the separation and refining of crude oil. This preferred embodiment can improve the utilization rate of carbon dioxide and reduce energy consumption.

[0021] According to a preferred embodiment of the present invention, the air stripping is performed in an air stripping apparatus.

[0022] The structure of the gas stripping device of the present invention can be a conventional choice in the art. According to a preferred embodiment of the present invention, the gas stripping device does not have or has at least one baffle, such that the cavity of the gas stripping device forms at least one gas stripping unit along the axial direction. Each gas unit is spaced apart and staggered along the axial direction with trays or packing. Each tray or packing edge is provided with an overflow plate to form a liquid phase enrichment zone for accumulating liquid phase. A downcomer is provided on the opposite side of the overflow plate to guide the liquid phase overflowing from the overflow plate to flow downward. The baffle is a tray or packing. The lower part of the gas stripping device is provided with at least one carbon dioxide-containing feed inlet. The gas stripping unit is provided with at least one primary product feed inlet, at least one carbon dioxide phase outlet and at least one oil phase outlet.

[0023] like Figure 1 As shown, the first stripping tower 1 does not have a baffle, so that the cavity of the stripping device forms a stripping unit along the axial direction. Each gas unit is spaced apart and staggered along the axial direction with a first tower plate or a first packing 2. Each first tower plate or first packing 2 has a first overflow plate 3 at its edge to form a liquid phase enrichment zone for accumulating liquid phase. A first downcomer 4 is provided on the opposite side of the first overflow plate 3 to guide the liquid phase overflowing from the overflow plate to flow downward. The bottom of the first stripping tower is provided with a first carbon dioxide-containing raw material inlet 6. The stripping unit is provided with a first primary product inlet 5, a first carbon dioxide phase outlet 8 and a first oil phase outlet 7.

[0024] In this invention, there is no particular limitation on the height of the overflow plate as long as the objective of the invention can be achieved. According to a preferred embodiment of the invention, the height of the overflow plate is 1-30 cm, preferably 2-20 cm, and more preferably 5-10 cm. By adopting the aforementioned preferred embodiment, the carbon dioxide utilization rate can be further improved, the environmental protection and safety of the production process can be further improved, and energy consumption can be further reduced.

[0025] In this invention, there is no particular limitation on the number of primary product inlets in the air-lift unit. According to a preferred embodiment of this invention, the number of primary product inlets in the air-lift unit is 1-10, preferably 1-5.

[0026] There is no particular limitation on the number of carbon dioxide feed inlets in the stripping unit. According to a preferred embodiment of the present invention, the number of carbon dioxide feed inlets in the stripping unit is 1-5, preferably 1-3.

[0027] According to a preferred embodiment of the present invention, each feed line and / or discharge line of the air-lift device is equipped with a valve and / or a compression pump.

[0028] like Figure 1 The first stripping tower 1 is equipped with a first compression pump 9 for its carbon dioxide feed pipeline, primary product feed pipeline, carbon dioxide phase outlet pipeline, and oil phase outlet pipeline.

[0029] According to a preferred embodiment of the present invention, the operating pressure of each compression pump is 0.1-30 MPa, more preferably 0.1-15 MPa.

[0030] In this invention, as long as the objective of the invention can be achieved, there is no particular limitation on the number of stages of the trays or packing in the gas stripping device. According to a preferred embodiment of the invention, the number of stages of the trays or packing in the gas stripping device is 1-100 stages, preferably 2-60 stages, and more preferably 3-40 stages. By adopting the aforementioned preferred embodiments, the carbon dioxide utilization rate can be further improved, the environmental protection and safety of the production process can be further improved, and energy consumption can be further reduced.

[0031] In this invention, as long as the objective of the invention can be achieved, there is no particular limitation on the number of stages of trays or packing in the stripping unit. According to a preferred embodiment of the invention, the number of stages of trays or packing in each stripping unit is 1-50, preferably 2-20, and more preferably 3-15. By adopting the aforementioned preferred embodiments, the carbon dioxide utilization rate can be further improved, the environmental friendliness and safety of the production process can be further improved, and energy consumption can be further reduced.

[0032] According to a preferred embodiment of the present invention, the separation employs a separation unit, which includes at least one of a membrane separator, a cryogenic distillation separator, an adsorption separator, an absorption separator, and a liquefaction separator.

[0033] According to a preferred embodiment of the present invention, the primary product after crude oil separation and refining is selected from the oil phase product after crude oil carbon dioxide separation and refining and / or the oil phase product after crude oil is frequently distilled under reduced pressure.

[0034] A second aspect of the present invention provides a purification system for primary products after crude oil separation and refining. The system includes a stripping unit for stripping the primary products after crude oil separation and refining from a carbon dioxide-containing feedstock, so that the light components in the primary products after crude oil separation and refining dissolve in carbon dioxide to form a carbon dioxide phase rich in light components, and the heavy components are enriched to obtain a purified oil phase; and a crude oil separation and refining unit connected to the stripping unit via a pipeline for providing the primary products after crude oil separation and refining.

[0035] According to a preferred embodiment of the present invention, the crude oil separation and refining unit is a carbon dioxide separation and refining crude oil unit. The carbon dioxide phase outlet of the gas stripping unit is connected to the carbon dioxide feed inlet of the carbon dioxide separation and refining crude oil unit, for injecting the carbon dioxide phase into the carbon dioxide separation and refining crude oil unit as carbon dioxide feedstock; and / or the carbon dioxide phase outlet of the gas stripping unit is connected to a separation unit, for separating the carbon dioxide phase to obtain carbon dioxide, natural gas and condensate oil; and / or the carbon dioxide phase outlet of the gas stripping unit is connected to an oil reservoir well, for using the carbon dioxide phase for oil displacement.

[0036] According to a preferred embodiment of the present invention, the crude oil separation and refining unit is an atmospheric and vacuum distillation separation and refining unit for crude oil, wherein the carbon dioxide phase outlet of the gas stripping unit is connected to the separation unit for separating the carbon dioxide phase to obtain carbon dioxide, natural gas and condensate oil; and / or the carbon dioxide phase outlet of the gas stripping unit is connected to the reservoir well for using the carbon dioxide phase for oil displacement.

[0037] like Figure 2As shown, this invention provides a purification system for primary products after crude oil separation and refining. The system includes a second stripping tower 21, which has three baffles (second trays or second packing) forming four stripping units along the axial direction. Each stripping unit has second trays or second packing 22 spaced apart and staggered along the axial direction. Each second tray or packing 22 has a second overflow plate 23 at its edge, forming a liquid phase enrichment zone for accumulating liquid phase. A second downcomer 24 is provided on the opposite side of the second overflow plate 23 to guide the liquid phase overflowing from the second overflow plate downwards. A second carbon dioxide-containing feed inlet 29 is provided at the bottom of the second stripping tower. The second stripping tower also has four second primary product inlets 25-28 and four second carbon dioxide phase outlets (i.e., reinjection gas outlets 14-16 and top gas outlets). The gas stripping unit is equipped with one primary product inlet, one carbon dioxide phase outlet, and one oil phase outlet. It is connected to the second gas stripping tower via pipeline to a carbon dioxide separation and refining crude oil tower, which is used to provide the primary products after crude oil separation and refining, namely the side 1-3 line oil and the bottom oil. The carbon dioxide separation and refining crude oil tower is equipped with one crude oil inlet and four carbon dioxide inlets (including one tower bottom carbon dioxide inlet and three side line carbon dioxide inlets) and one top gas outlet of the oil separator. The carbon dioxide phase outlet (reinjection gas outlet 14-16) of the gas stripping tower is connected to the side line carbon dioxide inlet of the carbon dioxide separation and refining crude oil tower, and is used to inject the carbon dioxide phase into the carbon dioxide separation and refining crude oil tower as carbon dioxide feedstock.

[0038] According to a preferred embodiment of the present invention, the carbon dioxide phase outlet of the second stripping tower 21 is connected to a separation unit (not shown in the figure) for separating the carbon dioxide phase to obtain carbon dioxide, natural gas and condensate oil.

[0039] According to a preferred embodiment of the present invention, the carbon dioxide phase outlet of the second gas lift tower 21 is connected to the reservoir well (not shown in the figure), and the carbon dioxide phase is used for oil displacement.

[0040] Specifically, the stripping tower is equipped with floating valve trays, for example, 36 floating valve trays divided into four groups (four stripping units). Except for three trays, such as trays 10, 19, and 28, the remaining trays are equipped with overflow weirs and downcomers on their sides, installed opposite each other. The stripping tower has a bottom oil inlet on the side, for example, located between trays 5 and 6; a first-line side oil inlet, for example, located between trays 14 and 15; a second-line side oil inlet, for example, located between trays 23 and 24; and a third-line side oil inlet, for example, located between trays 32 and 33. The carbon dioxide-containing feedstock inlet is below the first tray. The purified bottom oil outlet is located at the bottom of the tower. The purified side-first oil outlet is installed on the side of the stripping tower, for example, between trays 10 and 11. The purified side-second oil outlet is installed on the side of the stripping tower, for example, between trays 19 and 20. The purified side-third oil outlet is installed on the side of the stripping tower, for example, between trays 28 and 29. The reinjection gas a containing light components outlet is installed on the side of the stripping tower, for example, between trays 9 and 10. The reinjection gas b containing light components outlet is installed on the side of the stripping tower, for example, between trays 18 and 19. The reinjection gas c containing light components outlet is installed on the side of the stripping tower, for example, between trays 27 and 28. The top gas outlet of the stripping tower containing light components is located at the top of the stripping tower.

[0041] The process includes: the bottom oil, side line one oil, side line two oil, and side line three oil flowing out of the carbon dioxide separator are injected into the stripping tower after passing through a throttling valve; carbon dioxide is injected into the stripping tower under the action of a compressor pump. The purified bottom oil, side line one oil, side line two oil, and side line three oil are output from the stripping tower through a compressor pump; the top gas of the stripping tower containing light components is output from the stripping tower under the action of a compressor pump and enters a cryogenic distillation tower for cooling, separating high-value-added condensate oil products. The remaining reinjection gas (ac) is reinjected into the carbon dioxide separator for crude oil separation and refining, thereby realizing the recycling of carbon dioxide. The invention will be described in detail below through examples. In the following examples, the mass fraction parameters of each component were measured by liquid chromatography and mass spectrometry.

[0042] Example 1

[0043] The primary crude oil product used in this embodiment is bottom oil A flowing from the carbon dioxide separator. This bottom oil A has not undergone degassing treatment, and its composition is shown in Table 1.

[0044] Table 1

[0045]

[0046] The first air-lift tower used in this embodiment is as follows: Figure 1 As shown.

[0047] The first stripping tower operates at a temperature of 50℃ and a pressure of 0.12MPa. It contains nine first floating valve trays. Nine sets of overflow weirs and first downcomers are installed on opposite sides of the trays, with the overflow weirs 5cm higher than the first tray. A first primary product inlet is located between the fifth and sixth first trays, and a first carbon dioxide-containing feed inlet is below the first first tray. A purified product outlet is located at the bottom of the tower, and a gas phase outlet containing light components is located at the top. A first inlet compressor pump injects bottom oil and CO2 into the first stripping tower at 0.12MPa, with flow rates of 200t / h and 20t / h, respectively. A first outlet compressor pump discharges the purified product and the CO2 phase containing light components from the first stripping tower at 0.12MPa, with flow rates of 97.0t / h and 123.0t / h, respectively. The composition and change rate of the purified bottom oil are shown in Table 2. The removal rate of C1-C4 and CO2 components is greater than 95%, and the purity of medium and heavy components (C>12) is increased by more than 100%. The purified bottom oil is used as feedstock in the next stage of crude oil refining processes, such as vacuum distillation. The CO2 phase containing light components is cooled to 10°C in a cryogenic distillation tower to separate high-value-added condensate oil products, the composition of which is shown in Table 2. The remaining gas phase is reinjected into a CO2 separator for crude oil separation and refining, thereby achieving CO2 recycling. Therefore, this embodiment achieves the purification of bottom oil, the recovery of light components, and high CO2 utilization.

[0048] Table 2

[0049]

[0050] Example 2

[0051] In this embodiment, the stripping tower is used to purify the oil phase product of the CO2 separation tower, including bottom oil, side first-line oil, side second-line oil, and side third-line oil, recovering light components and realizing the recycling of CO2. The second stripping tower in this embodiment is as follows... Figure 2 As shown.

[0052] The second stripping tower operates at a temperature of 50℃ and a pressure of 0.12MPa. It contains 36 second-stage valve trays, divided into four groups. Except for trays 10, 19, and 28, all other second-stage trays have overflow weirs and second downcomers installed on their sides, mounted opposite each other. The overflow weirs are 5cm higher than the second-stage trays. The bottom oil inlet is located between the fifth and sixth second-stage trays; the first side oil inlet is located between the 14th and 15th second-stage trays; the second side oil inlet is located between the 23rd and 24th second-stage trays; and the third side oil inlet is located between the 32nd and 33rd second-stage trays. The second carbon dioxide-containing feed inlet is located below the first second-stage tray. The purified bottom oil outlet is located at the bottom of the tower. The purified side-first oil outlet is installed between the 10th and 11th second trays, the purified side-second oil outlet is installed between the 19th and 20th second trays, and the purified side-third oil outlet is installed between the 28th and 29th second trays. The reinjection gas a containing light components outlet is between the 9th and 10th second trays, the reinjection gas b containing light components outlet is between the 18th and 19th second trays, the reinjection gas c containing light components outlet is between the 27th and 28th second trays, and the stripping tower top gas outlet containing light components is at the top of the second stripping tower.

[0053] The bottom oil, side line one, side line two, and side line three oil flowing out of the CO2 separator are injected into the second stripping tower at a rate of 113.0 t / h, 90.7 t / h, 22.6 t / h, and 13.0 t / h respectively at 0.12 MPa after passing through a throttling valve. Their compositions are shown in Table 3. CO2 is injected into the second stripping tower at a rate of 11.3 t / h at 0.12 MPa by a second compressor pump. The purified bottom oil, side line one, side line two, and side line three oil are discharged from the second stripping tower by a compressor pump at flow rates of 49.8 t / h, 45.0 t / h, 8.3 t / h, and 4.8 t / h respectively. Their compositions are shown in Table 4. The removal rates of C1-C4 and CO2 components are greater than 95%, and the purity of the corresponding main components is increased by more than 100%. Reinjected gases a, b, and c, containing light components, are reinjected into the CO2 separator at rates of 12.6 t / h, 19.2 t / h, and 18.3 t / h, respectively, by the second compressor pump. The stripper top gas, also containing light components, is output from the stripper at a rate of 81.2 t / h by the second compressor pump and then cooled to 10°C in a cryogenic distillation column to separate high-value-added condensate oil, the composition of which is shown in Table 4. The remaining gas phase is reinjected into the CO2 separator for crude oil separation and refining, thus achieving CO2 recycling. Therefore, this embodiment achieves the purification of the bottom oil, side-line oil, side-line oil, and side-line oil produced by the CO2 separator, the recovery of light components, and high CO2 utilization.

[0054] Table 3

[0055]

[0056] Table 4

[0057]

[0058] Table 4 (continued)

[0059]

[0060] Example 3

[0061] The primary crude oil product used in this embodiment is atmospheric bottom oil B after atmospheric distillation of crude oil, and its composition is shown in Table 5.

[0062] Table 5

[0063]

[0064] The first air-lift tower used in this embodiment is as follows: Figure 1 (Same as the embodiment) shown.

[0065] The working temperature of this stripping tower is 80℃ and the working pressure is 0.12MPa.

[0066] The first outlet compressor pump is used to output the purified product and the CO2 phase containing light components to the first stripping tower at 0.12 MPa, with flow rates of 197.2 t / h and 22.8 t / h, respectively. The composition and change rate of the purified atmospheric bottom oil are shown in Table 6, with a removal rate of C1-C4 light components greater than 88%. The purified atmospheric bottom oil is used as feedstock in the next stage vacuum distillation tower. The CO2 phase containing light components is cooled to 10°C in a cryogenic distillation tower, where a high-value-added condensate product is separated, the composition of which is shown in Table 6. The remaining gas phase is separated by a CO2 / methane membrane to recover the natural gas product, and the remaining CO2 is reinjected into the first CO2 stripping tower for reuse. Therefore, this embodiment achieves the purification of atmospheric bottom oil, the recovery of light components, and a high utilization rate of CO2.

[0067] Table 6

[0068]

[0069] Example 4

[0070] The process conditions are the same as in Example 1. The first tray in the first stripping tower is replaced with a structured first packing with the same theoretical number of trays, while the rest of the apparatus remains unchanged. The flow rates and compositions of the purified bottom oil and condensate remain unchanged, as shown in Table 2. Therefore, by using the first packing instead of the first tray, it is still possible to achieve bottom oil purification, light component recovery, and high CO2 utilization.

[0071] Example 5

[0072] The process conditions and equipment are the same as in Example 3. After the CO2 phase containing light components is separated into condensate oil in a cryogenic distillation tower, CO2 / methane separation is not performed again; instead, it is reinjected into the CO2-driven oil displacement injection well. Because this gas phase contains a certain amount of light hydrocarbon components in addition to CO2, it can effectively reduce the minimum miscibility pressure between CO2 and crude oil, thereby improving the CO2-driven oil displacement efficiency. Therefore, this example can improve crude oil extraction efficiency while achieving bottom oil purification, light component recovery, and high CO2 utilization.

[0073] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A method for purifying primary products after crude oil separation and refining, characterized in that, The method includes: using carbon dioxide-containing feedstock to perform gas stripping on the primary product after crude oil separation and refining, so that the light components in the primary product after crude oil separation and refining dissolve in carbon dioxide to form a carbon dioxide phase rich in light components, and the heavy components are enriched to obtain a purified oil phase. The method further includes: The carbon dioxide phase is separated to obtain carbon dioxide, natural gas, and condensate oil; The primary products obtained after crude oil separation and refining are selected from the oil phase products obtained after crude oil carbon dioxide separation and refining; The gas stripping is carried out in a gas stripping device, which has no or at least one baffle plate, such that the cavity of the gas stripping device forms at least one gas stripping unit along the axial direction. Each gas stripping unit is provided with trays or packing materials spaced apart and staggered along the axial direction. Each tray or packing material has an overflow plate at its edge to form a liquid phase enrichment zone for accumulating liquid phase. A downcomer is provided on the opposite side of the overflow plate to guide the liquid phase overflowing from the overflow plate downward. The height of the overflow plate is 5-10 cm. The number of stages of trays or packing materials in the gas stripping device is 3-40. The number of stages of trays or packing materials in each gas stripping unit is 3-15. The partition plate is a tray or packing; the lower part of the stripping device is provided with at least one carbon dioxide feed inlet; the stripping unit is provided with 1-5 primary product feed inlets, at least one carbon dioxide phase outlet and at least one oil phase outlet.

2. The purification method according to claim 1, wherein, The conditions for the air stripping include: The ratio of the mass flow rate of the carbon dioxide-containing feedstock (measured as carbon dioxide) to the mass flow rate of the primary product is 10:1 to 1:100; and / or The air lifting pressure is 0.1-30 MPa; and / or The air stripping temperature is 0-200℃.

3. The purification method according to claim 2, wherein, The conditions for the air stripping include: The ratio of the mass flow rate of the carbon dioxide-containing feedstock (measured as carbon dioxide) to the mass flow rate of the primary product is 5:1 to 1:50; and / or The air lifting pressure is 0.1-15 MPa; and / or The air-lift temperature is 20-100℃.

4. The purification method according to claim 2, wherein, The conditions for the air stripping include: The ratio of the mass flow rate of the carbon dioxide-containing feedstock (measured as carbon dioxide) to the mass flow rate of the primary product is 1:1 to 1:

30.

5. The purification method according to claim 1, wherein, The method further includes: The carbon dioxide phase is used for carbon dioxide flooding; and / or The carbon dioxide phase is used for the separation and refining of crude oil.

6. The purification method according to claim 1, wherein, The number of carbon dioxide feed inlets in the stripping unit is 1-5; and / or Each feed line and / or discharge line of the air-lift device is equipped with a valve and / or a compression pump.

7. The purification method according to claim 6, wherein, The number of carbon dioxide feed inlets in the stripping unit is 1-3; and / or The operating pressure of each compression pump is 0.1-30MPa.

8. The purification method according to claim 7, wherein, The operating pressure of each compression pump is 0.1-15 MPa.

9. The purification method according to claim 1, wherein, The separation employs a separation unit, which includes at least one of a membrane separator, a cryogenic distillation separator, an adsorption separator, an absorption separator, and a liquefaction separator.

10. A purification system for primary products after crude oil separation and refining, characterized in that, The system includes: The gas stripping unit is used to strip the primary products of crude oil after separation and refining from carbon dioxide feedstock. This allows the light components in the primary products of crude oil after separation and refining to dissolve in carbon dioxide to form a carbon dioxide phase rich in light components, while the heavy components are enriched to obtain a purified oil phase. A crude oil separation and refining unit connected to the stripping unit via pipeline is used to provide primary products after crude oil separation and refining. The crude oil separation and refining unit is a carbon dioxide separation and refining unit. The carbon dioxide phase outlet of the stripping unit is connected to the carbon dioxide inlet of the carbon dioxide separation and refining unit, and is used to inject the carbon dioxide phase into the carbon dioxide separation and refining unit as carbon dioxide feedstock. The carbon dioxide phase outlet of the stripping unit is connected to the separation unit, and is used to separate the carbon dioxide phase to obtain carbon dioxide, natural gas and condensate.

11. The purification system according to claim 10, wherein, The carbon dioxide phase outlet of the gas stripping unit is connected to the reservoir well, and the carbon dioxide phase is used for oil displacement.

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