Process and apparatus for the production of light olefins and aromatics from an aromatic-containing light crude oil

Abstract

The application provides a method and device for preparing low-carbon olefins and aromatic hydrocarbons from aromatic hydrocarbon-containing light crude oil, which comprises the following steps: pretreating the aromatic hydrocarbon-containing light crude oil to obtain pretreated crude oil, subjecting the pretreated crude oil to raw material fractionation treatment to obtain a cracking unit feed stream, subjecting the cracking unit feed stream to cracking treatment to obtain a cracking product stream and a first residual oil stream; discharging the first residual oil stream, subjecting the cracking product stream to product separation treatment to obtain a separation product stream and a cracking gasoline stream; subjecting the cracking gasoline stream to gasoline hydrogenation treatment to obtain a hydrogenated cracking gasoline stream, subjecting the hydrogenated cracking gasoline stream to aromatic hydrocarbon extraction treatment to obtain a fourth aromatic hydrocarbon-rich stream, and subjecting the fourth aromatic hydrocarbon-rich stream to aromatic hydrocarbon separation treatment to obtain an aromatic hydrocarbon separation product stream. Compared with a traditional refining and chemical integration process, the technical scheme of the application greatly shortens the processing flow and can maximize the yield of low-carbon olefins and aromatic hydrocarbons from the aromatic hydrocarbon-containing light crude oil.

Description

Technical Field

[0001] This invention relates to the field of preparing low-carbon olefins from aromatic light crude oil, and more specifically, to a method and apparatus for preparing low-carbon olefins and aromatics from aromatic light crude oil. Background Technology

[0002] Low-carbon olefins (including ethylene, propylene, butadiene, etc.) and aromatics (including benzene, toluene, xylene, etc.) are important petrochemical intermediates, widely used in the production of plastics, rubber, glass, pharmaceuticals, fragrances, dyes, and many other products. They are an important indicator of the development level of the petrochemical industry.

[0003] Tubular furnace steam cracking technology is the main method for producing low-carbon olefins, and the choice of feedstock directly affects the yield of low-carbon olefins. Generally speaking, the selection of light feedstocks such as naphtha, LPG, raffinate, and reformate topping oil can significantly improve the yield of low-carbon olefins, reduce the investment cost of the plant, and increase market competitiveness. In recent years, with the increase in the production of light crude oils such as shale oil and condensate, it has become possible to pre-treat (desalting, dehydrating) light crude oil and then directly crack it to produce olefins. Direct cracking of light crude oil to produce low-carbon olefins will greatly shorten the process flow, reduce construction investment, and greatly expand the feedstock options for the plant, with broad application prospects and great significance to the chemical industry.

[0004] On the other hand, light crude oil components can generally be divided into alkanes, alkenes, cycloalkanes, and aromatics. The content of alkanes is directly proportional to the yield of low-carbon olefins. However, aromatic components, due to the large bond energy of the benzene ring, are difficult to crack and prone to coking, which is detrimental to the production of low-carbon olefins and shortens the coking cycle. Therefore, it is necessary to reduce the aromatic content of crude oil used as feedstock for ethylene plants to a reasonable level in advance. Summary of the Invention

[0005] To address the aforementioned technical problems, the present invention aims to provide a method and apparatus for producing low-carbon olefins and aromatics from aromatic light crude oil. Compared with traditional integrated refining and chemical processes, the method of the present invention significantly shortens the processing flow while maximizing the yield of low-carbon olefins and aromatics from aromatic light crude oil.

[0006] To achieve the above objectives, in one aspect, the present invention provides a method for producing low-carbon olefins and aromatics from aromatic light crude oil, the method comprising the following steps:

[0007] 1) Pre-treat light crude oil containing aromatics to obtain pre-treated crude oil;

[0008] 2) The pretreated crude oil is subjected to feedstock fractionation to obtain the feed stream for the cracking unit, which includes the light component stream and the heavy component stream of the first crude oil.

[0009] 3) The first crude oil light component stream and the first crude oil heavy component stream are respectively subjected to cracking treatment to obtain cracking product stream and first residue oil stream, wherein the cracking product stream includes the first crude oil cracking product stream and the second crude oil cracking product stream, and the first residue oil stream is discharged externally.

[0010] 4) The first crude oil cracking product stream and the second crude oil cracking product stream are subjected to product separation treatment to obtain a separated product stream and a cracked gasoline stream.

[0011] 5) The cracked gasoline stream is subjected to gasoline hydrotreating to obtain a hydrotreated cracked gasoline stream;

[0012] 6) The hydrocracking gasoline stream was subjected to aromatic extraction treatment to obtain a fourth aromatic-rich stream;

[0013] 7) The fourth aromatic hydrocarbon stream is subjected to aromatic hydrocarbon separation treatment to obtain an aromatic hydrocarbon separation product stream.

[0014] According to a specific embodiment of the present invention, preferably, the method includes the following steps:

[0015] 1) Pre-treat light crude oil containing aromatics to obtain pre-treated crude oil;

[0016] 2) The pretreated crude oil is subjected to dearomatization treatment to obtain a second aromatics-lean stream and a third aromatics-rich stream;

[0017] 3) Perform aromatic hydrocarbon separation treatment on the third aromatic hydrocarbon-rich stream;

[0018] 4) The second lean aromatics stream is subjected to feedstock fractionation to obtain the feedstock of the cracking unit, which includes the light component stream of the first crude oil and the heavy component stream of the first crude oil.

[0019] 5) The first crude oil light component stream and the first crude oil heavy component stream are respectively subjected to cracking treatment to obtain cracking product stream and first residue oil stream, wherein the cracking product stream includes the first crude oil cracking product stream and the second crude oil cracking product stream, and the first residue oil stream is discharged externally.

[0020] 6) The first crude oil cracking product stream and the second crude oil cracking product stream are subjected to product separation treatment to obtain a separated product stream and a cracked gasoline stream.

[0021] 7) The cracked gasoline stream is subjected to gasoline hydrotreating to obtain a hydrotreated cracked gasoline stream;

[0022] 8) The hydrocracking gasoline stream is subjected to aromatic extraction treatment to obtain a fourth aromatic-rich stream and a hydrocracking gasoline stream after aromatic removal, wherein the hydrocracking gasoline stream after aromatic removal is used as a cracking feedstock and fed into the cracking unit feed stream.

[0023] 9) The fourth aromatic hydrocarbon stream is subjected to aromatic hydrocarbon separation treatment to obtain an aromatic hydrocarbon separation product stream.

[0024] According to a specific embodiment of the present invention, preferably, the method includes the following steps:

[0025] 1) Pre-treat light crude oil containing aromatics to obtain pre-treated crude oil;

[0026] 2) The pretreated crude oil is subjected to dearomatization treatment to obtain a second aromatics-lean stream and a third aromatics-rich stream;

[0027] 3) Perform aromatic hydrocarbon separation treatment on the third aromatic hydrocarbon-rich stream;

[0028] 4) The second lean aromatics stream is subjected to feedstock fractionation to obtain the feedstock of the cracking unit, which includes the light component stream of the first crude oil and the heavy component stream of the first crude oil.

[0029] 5) The first crude oil light component stream and the first crude oil heavy component stream are respectively subjected to cracking treatment to obtain cracking product stream and first residue oil stream, wherein the cracking product stream includes the first crude oil cracking product stream and the second crude oil cracking product stream.

[0030] 6) The first crude oil cracking product stream and the second crude oil cracking product stream are subjected to product separation treatment to obtain a separated product stream and a cracked gasoline stream.

[0031] 7) The first residue oil stream is subjected to residue oil hydrotreating to obtain a residue oil hydrotreating unit product stream and a second residue oil stream. The residue oil hydrotreating unit product stream is incorporated into the cracking unit feed stream as cracking feedstock, while the second residue oil stream is discharged.

[0032] 8) The cracked gasoline stream is subjected to gasoline hydrotreating to obtain a hydrotreated cracked gasoline stream;

[0033] 9) The hydrocracking gasoline stream is subjected to aromatic extraction treatment to obtain a fourth aromatic-rich stream and a hydrocracking gasoline stream after aromatic removal, wherein the hydrocracking gasoline stream after aromatic removal is used as a cracking feedstock and fed into the cracking unit feed stream.

[0034] 10) The fourth aromatic hydrocarbon stream is subjected to aromatic hydrocarbon separation treatment to obtain an aromatic hydrocarbon separation product stream.

[0035] According to a specific embodiment of the present invention, preferably, the final boiling point of the aromatic light crude oil is less than or equal to 1000°C, and the aromatic content is less than 50 wt%, preferably, the aromatic content is 10-30 wt%.

[0036] According to a specific embodiment of the present invention, preferably, the pretreatment includes steps such as dehydration, demetallization, desalination and desulfurization. When performing the pretreatment, the temperature of the light crude oil containing aromatics is 80-150℃, preferably 80-100℃.

[0037] According to a specific embodiment of the present invention, preferably, in step 1), the pretreated crude oil has a desalination rate of 95.0-99.9 wt%, a dehydration rate of 95.0-99.0 wt%, and a sulfur content of less than 30 ppm.

[0038] According to a specific embodiment of the present invention, preferably, in step 2), the dearomatic treatment includes the following steps:

[0039] i) The pretreated crude oil is fed into the bottom of the aromatics extraction tower. Under the action of the crude oil dearomatization solvent, the raffinate at the top of the tower is the first lean aromatics crude oil stream, and the bottom of the tower is the first rich aromatics stream.

[0040] ii) The first lean aromatic crude oil stream is fed to the bottom of the water washing tower. After water washing, the second lean aromatic stream is obtained at the top of the tower and used as cracking feedstock for fractionation. The water at the bottom of the tower is sent to the solvent recovery tower.

[0041] iii) The first aromatic hydrocarbon-rich stream is fed to the bottom of the stripping tower, and the backwash stream is obtained at the top of the stripping tower. After condensation and water separation, the backwash stream is sent to the liquid-liquid extraction tower through the backwash stream pipeline. The separated water stream is sent to the solvent recovery tower. The second aromatic hydrocarbon-rich stream is obtained at the bottom of the stripping tower.

[0042] iv) The second aromatic hydrocarbon stream is fed into a solvent recovery tower;

[0043] v) A third aromatic-rich stream is obtained at the top of the solvent recovery tower, and a solvent stream with an aromatic content of less than 0.5 wt% is obtained at the bottom of the tower. The stream is then sent back to the top of the liquid-liquid extraction tower after heat exchange.

[0044] According to a specific embodiment of the present invention, preferably, the crude oil dearomatization solvent is selected from one or more combinations of methanol, acetonitrile, isopropanol, ethylene glycol, triethylene glycol, tetraethylene glycol, pentaethylene glycol, sulfolane, dimethyl sulfoxide, dimethylformamide, N-methylpyrrolidone, N-formylmorpholine, methylimidazolium, butylpyridine, furfural, ketone, water, and potassium thiocyanate.

[0045] According to a specific embodiment of the present invention, preferably, the mass ratio of the crude oil dearomatization solvent to the pretreated crude oil in the liquid-liquid extraction tower is 1:(2-10), the operating pressure of the liquid-liquid extraction tower is 0.1MPa-1.2MPa, and the temperature is 25-100℃.

[0046] According to a specific embodiment of the present invention, preferably, in step 4), the fractionation equipment for the fractionation process is an atmospheric distillation tower and / or a flash tank.

[0047] According to a specific embodiment of the present invention, preferably, in step 4), the fractionation process is to separate the alkane stream with a final boiling point of less than 300°C to obtain the first crude oil light component stream, and the remaining components are the first crude oil heavy component stream.

[0048] According to a specific embodiment of the present invention, preferably, in step 5), the pyrolysis treatment includes steps such as preheating, stripping, mixing, separation, and steam pyrolysis.

[0049] According to a specific embodiment of the present invention, preferably, in step 5), the pyrolysis treatment equipment for the pyrolysis treatment includes one or more of the following: a light pyrolysis furnace, a heavy pyrolysis furnace, and a gas pyrolysis furnace.

[0050] According to a specific embodiment of the present invention, preferably, the pyrolysis equipment for the pyrolysis process includes a light pyrolysis furnace and a heavy pyrolysis furnace, wherein the first crude oil light component stream is fed into the light pyrolysis furnace; and the first crude oil heavy component stream is fed into the heavy pyrolysis furnace.

[0051] According to a specific embodiment of the present invention, preferably, after the first crude oil heavy fraction is preheated in a heavy cracking furnace, the fraction with a temperature above 450°C is separated and used as the first residue oil stream for residue hydrotreating, and the remainder is the second crude oil heavy fraction stream sent to the heavy cracking furnace as cracking feedstock.

[0052] According to a specific embodiment of the present invention, preferably, both the light pyrolysis furnace and the heavy pyrolysis furnace adopt the tubular high-temperature steam pyrolysis method; the outlet temperature of the light pyrolysis furnace is 800-870℃, the residence time is 0.2-0.3s, and the dilution steam ratio is 1:(0.3-0.6); the outlet temperature of the heavy pyrolysis furnace is 800-870℃, the residence time is 0.2-0.3s, and the dilution steam ratio is 1:(0.5-0.8).

[0053] According to a specific embodiment of the present invention, preferably, in step 6), the separated product stream and the cracked gasoline stream contain hydrogen, methane, ethylene, propylene, butadiene, cracked gasoline, and cracked tar.

[0054] According to a specific embodiment of the present invention, preferably, in step 6), the cracked gasoline obtained from the separation of the first crude oil cracking product stream and the cracked gasoline obtained from the separation of the second crude oil cracking product stream are mixed to obtain a cracked gasoline stream.

[0055] According to a specific embodiment of the present invention, preferably, one or more process units can be omitted or skipped based on the actual properties of the aromatic-containing light crude oil to achieve the best product yield.

[0056] On the other hand, the present invention provides an apparatus for producing low-carbon olefins and aromatics from light crude oil containing aromatics, wherein the apparatus comprises:

[0057] Pretreatment unit, aromatics removal unit, feedstock fractionation unit, cracking unit, separation unit, residue hydrotreating unit, gasoline hydrotreating unit, aromatics extraction unit, and aromatics separation unit; wherein:

[0058] The pretreatment unit is provided with a raw material inlet, and the outlet of the pretreatment unit is connected to the inlet of the dearomatic unit;

[0059] The first outlet and the second outlet of the dearomatic unit are respectively connected to the inlet of the raw material fractionation unit and the inlet of the aromatic separation unit;

[0060] The outlet of the raw material fractionation unit is connected to the inlet of the pyrolysis unit;

[0061] The first outlet and the second outlet of the pyrolysis unit are respectively connected to the inlet of the separation unit and the inlet of the residue hydrotreating unit;

[0062] The first outlet of the separation unit is connected to the inlet of the gasoline hydrogenation unit. The separation unit is also provided with a second outlet, which is used to output the separated product stream after separation treatment.

[0063] The first outlet of the residue hydrotreating unit is connected to the inlet of the cracking unit. The residue hydrotreating unit is also provided with a second outlet, which is used to output the second residue stream.

[0064] The outlet of the gasoline hydrogenation unit is connected to the inlet of the aromatics extraction unit;

[0065] The first outlet and the second outlet of the aromatic extraction unit are respectively connected to the inlet of the aromatic separation unit and the inlet of the pyrolysis unit;

[0066] The aromatic hydrocarbon separation unit is equipped with an outlet for aromatic hydrocarbon separation products.

[0067] This invention provides a concise route for the comprehensive utilization of light crude oil for chemical products (olefins and aromatics). It specifically integrates steam cracking technology, light and heavy fractionation of crude oil, and aromatics removal technology to maximize the utilization of light crude oil, reduce the coking impact of heavy components during cracking, and improve product yield and economic efficiency. The processing flow, which organically combines direct cracking of light crude oil with aromatics processes, can effectively improve the product yield of low-carbon olefins in tubular steam cracking units, providing an efficient and economical process solution for future light crude oil processing. Attached Figure Description

[0068] Figure 1This is a process flow diagram of the direct cracking of light crude oil to produce low-carbon olefins and aromatics provided by the present invention.

[0069] Explanation of reference numerals in the attached figures:

[0070] 1. Pretreatment unit; 2. De-aromatization unit; 3. Feed fractionation unit; 4. Cracking unit; 5. Separation unit; 6. Residue hydrotreating unit; 7. Gasoline hydrotreating unit; 8. Aromatics extraction unit; 9. Aromatics separation unit; 10. Light crude oil stream; 11. Pretreatment crude oil stream; 12. Second lean aromatics stream; 13. Cracking unit feed stream; 14. Cracking product stream; 15. Separation product stream; 16. Third rich aromatics stream; 17. De-aromatized and hydrocracked gasoline stream; 18. Residue hydrotreating unit product stream; 19. Second residue stream; 20. Cracking gasoline stream; 21. Hydrocracked gasoline stream; 22. Fourth rich aromatics stream; 23. Aromatics separation product stream; 24. First residue stream. Detailed Implementation

[0071] The following provides a detailed description of specific embodiments of the present invention. It should be understood that the specific embodiments described herein are for illustrative and explanatory purposes only and are not intended to limit the scope of the invention.

[0072] This invention provides an apparatus for directly producing low-carbon olefins and aromatics through steam cracking of light crude oil, the structure of which is as follows: Figure 1 As shown. The device includes:

[0073] Pretreatment unit 1, Aromatics removal unit 2, Feed fractionation unit 3, Cracking unit 4, Separation unit 5, Residue hydrogenation unit 6, Gasoline hydrogenation unit 7, Aromatics extraction unit 8, Aromatics separation unit 9; wherein:

[0074] The pretreatment unit 1 is provided with a raw material inlet, and the outlet of the pretreatment unit 1 is connected to the inlet of the dearomatic unit 2;

[0075] The first outlet and the second outlet of the dearomatics removal unit 2 are respectively connected to the inlet of the raw material fractionation unit 3 and the inlet of the aromatics separation unit 9;

[0076] The outlet of the raw material fractionation unit 3 is connected to the inlet of the pyrolysis unit 4;

[0077] The first outlet and the second outlet of the pyrolysis unit 4 are respectively connected to the inlet of the separation unit 5 and the inlet of the residue hydrotreating unit 6;

[0078] The first outlet of the separation unit 5 is connected to the inlet of the gasoline hydrogenation unit 7. The separation unit 5 is also provided with a second outlet, which is used to output the separation product stream 15 after separation treatment.

[0079] The first outlet of the residue hydrotreating unit 6 is connected to the inlet of the cracking unit 4. The residue hydrotreating unit 6 is also provided with a second outlet, which is used to output the second residue stream 19 for discharge.

[0080] The outlet of the gasoline hydrogenation unit 7 is connected to the inlet of the aromatics extraction unit 8;

[0081] The first outlet and the second outlet of the aromatic extraction unit 8 are respectively connected to the inlet of the aromatic separation unit 9 and the inlet of the cracking unit 4;

[0082] The aromatic hydrocarbon separation unit 9 is equipped with an outlet for aromatic hydrocarbon separation products.

[0083] The present invention will be described in detail through the following embodiments.

[0084] The crude oil properties used in the examples and comparative examples are shown in Table 1 below. It should be understood that the steps and crude oil properties described below do not limit the choice of process flow and light crude oil.

[0085] Table 1. Physical Properties of Light Crude Oil

[0086] <![CDATA[Density (20 °C), kg / m 3 > 863.2 Testing items ASTM D2887 Initial boiling point 91.48 5% distillation temperature 148.3 10% distillation temperature 187.9 30% distillation temperature 261.0 50% distillation temperature 332.8 70% distillation temperature 420.5 90% distillation temperature 535.6 Final boiling point 815.9 Aromatic hydrocarbon content (wt%) 27.72

[0087] Example 1

[0088] This embodiment provides a method for producing low-carbon olefins and aromatics through steam cracking of light crude oil as feedstock. The process flow is as follows: Figure 1 As shown, the specific steps include:

[0089] 1. Light crude oil stream 10 enters pretreatment unit 1 and undergoes pretreatment of dehydration, demetallization, desalination and desulfurization to obtain pretreated crude oil stream 11, which has a water content of less than 0.2%, a salt content of less than 3 mg / L and a sulfur content of less than 30 ppm.

[0090] 2. The pretreated crude oil stream 11 enters the feed fractionation unit 3, and after fractionation, it obtains the cracking unit feed stream 13, which contains the first crude oil light component stream and the first crude oil heavy component stream. The first crude oil light component stream contains alkane stream with a final boiling point of less than 200°C, and the rest is the first crude oil heavy component stream.

[0091] 3. The feed stream 13 of the cracking unit, which includes the first light component stream and the first heavy component stream of crude oil, enters the cracking unit 4. The first light component stream in the feed stream 13 enters the light cracking furnace and is used as the cracking feedstock for the light cracking furnace. The first heavy component stream in the feed stream 13 enters the heavy cracking furnace for cracking. Specifically, after the first heavy component stream is preheated in the feedstock preheating section of the heavy cracking furnace, the residue oil components with a final boiling point of above 540°C are separated by a separator to obtain the first residue oil stream 24, which is sent out of the boundary. The remainder is the second heavy component stream of crude oil, which is used as the cracking feedstock for the heavy cracking furnace.

[0092] 4. The cracked product stream 14 obtained from the cracking unit 4 enters the separation unit 5 for separation, resulting in the separated product stream 15 and the cracked gasoline stream 20.

[0093] 5. The cracked gasoline stream 20 obtained from the separation unit enters the gasoline hydrogenation unit 7 for hydrogenation treatment to obtain hydrogenated cracked gasoline stream 21. The hydrogenated cracked gasoline stream 21 is then subjected to aromatic extraction treatment in the aromatic extraction unit 8 to obtain the fourth aromatic-rich stream 22. The fourth aromatic-rich stream 22 enters the aromatic separation unit 9 for aromatic separation treatment to finally obtain the aromatic separation product stream 23.

[0094] The yields of low-carbon olefins in Example 1 are detailed in Table 2, and the yields of aromatics are detailed in Table 3.

[0095] Example 2

[0096] This embodiment provides a method for producing low-carbon olefins and aromatics through steam cracking of light crude oil as feedstock. The process flow is as follows: Figure 1 As shown, the specific steps include:

[0097] 1. Light crude oil stream 10 enters pretreatment unit 1 and undergoes pretreatment of dehydration, demetallization, desalination and desulfurization to obtain pretreated crude oil stream 11, which has a water content of less than 0.2%, a salt content of less than 3 mg / L and a sulfur content of less than 30 ppm.

[0098] 2. Pre-treated crude oil stream 11 enters the dearomatization unit 2 for dearomatization treatment. The dearomatization treatment includes the following steps:

[0099] i) The pretreated crude oil stream 11 is fed into the bottom of the aromatics extraction tower. Under the action of the crude oil dearomatization solvents sulfolane and dimethyl sulfoxide, the raffinate at the top of the tower is obtained as the first lean aromatics crude oil stream, and the bottom of the tower is obtained as the first rich aromatics stream. The mass ratio of sulfolane to dimethyl sulfoxide is 9:1, and the mass ratio of pretreated crude oil to crude oil dearomatization solvent is 1:8.

[0100] ii) The first lean aromatic crude oil stream is fed to the bottom of the water washing tower. After water washing, the second lean aromatic stream 12 is obtained at the top of the tower and used as a cracking feedstock for fractionation. The water at the bottom of the tower is sent to the solvent recovery tower.

[0101] iii) The first aromatic hydrocarbon-rich stream is fed to the bottom of the stripping tower, and the backwash stream is obtained at the top of the stripping tower. After condensation and water separation, it is sent to the liquid-liquid extraction tower through the backwash stream pipeline. The separated water stream is sent to the solvent recovery tower. The second aromatic hydrocarbon-rich stream is obtained at the bottom of the stripping tower. The operating pressure of the liquid-liquid extraction tower is 0.12 MPa, and the temperature is 25-50℃.

[0102] iv) The second aromatic hydrocarbon stream is fed into the solvent recovery tower.

[0103] v) A third aromatic-rich stream 16 is obtained at the top of the solvent recovery tower, and a solvent stream with an aromatic content of less than 0.5 wt% is obtained at the bottom of the tower. The stream is then sent back to the top of the liquid-liquid extraction tower after heat exchange.

[0104] After dearomatization, a second aromatic-lean stream 12 and a third aromatic-rich stream 16 are obtained; the aromatic content of the second aromatic-lean stream 12 is reduced from 27.72 wt% to 1.23%. The remaining components are incorporated into the fourth aromatic-rich stream 22 as the third aromatic-rich stream 16 and then enter the aromatic separation unit 9 for aromatic separation.

[0105] 3. The second lean aromatics stream 12 enters the feed fractionation unit 3, and through fractionation, the cracking unit feed stream 13 is obtained, which contains the first crude oil light component stream and the first crude oil heavy component stream. The first crude oil light component stream contains alkane stream with a final boiling point of less than 200°C, and the remainder is the first crude oil heavy component stream.

[0106] 4. Feed stream 13, comprising the first crude oil light component stream and the first crude oil heavy component stream, enters cracking unit 4. The first crude oil light component stream in feed stream 13 enters the light cracking furnace for cracking, serving as the feedstock for the light cracking furnace. The first crude oil heavy component stream in feed stream 13 enters the heavy cracking furnace for cracking. Specifically, after preheating in the feedstock preheating section of the heavy cracking furnace, the first crude oil heavy component stream is separated by a separator to obtain the first residue oil stream 24, which is discharged outside the furnace. The remainder is the second crude oil heavy component stream, which serves as the feedstock for the heavy cracking furnace.

[0107] 5. The pyrolysis product stream 14 obtained from the pyrolysis unit 4 enters the separation unit 5 for product separation.

[0108] 6. The cracked gasoline stream 20 obtained from the separation unit 5 enters the gasoline hydrogenation unit 7 for hydrogenation to obtain the hydrogenated cracked gasoline stream 21. The hydrogenated cracked gasoline stream 21 is subjected to aromatic extraction treatment in the aromatic extraction unit 8 to obtain the fourth aromatic-rich stream 22 and the dearomatized hydrogenated cracked gasoline stream 17. The dearomatized hydrogenated cracked gasoline stream 17 is used as cracking feedstock and is incorporated into the feed stream 13 of the cracking unit. The fourth aromatic-rich stream 22 enters the aromatic separation unit 9 for aromatic separation treatment to finally obtain the aromatic separation product stream 23.

[0109] The yields of low-carbon olefins in Example 2 are detailed in Table 2, and the yields of aromatics are detailed in Table 3.

[0110] Example 3

[0111] This embodiment provides a method for producing low-carbon olefins and aromatics through steam cracking of light crude oil as feedstock. The process flow is as follows: Figure 1 As shown, the specific steps include:

[0112] 1. Light crude oil stream 10 enters pretreatment unit 1 and undergoes pretreatment of dehydration, demetallization, desalination and desulfurization to obtain pretreated crude oil stream 11, which has a water content of less than 0.2%, a salt content of less than 3 mg / L and a sulfur content of less than 30 ppm.

[0113] 2. Pre-treated crude oil stream 11 enters the dearomatization unit 2 for dearomatization treatment. The dearomatization treatment includes the following steps:

[0114] i) The pretreated crude oil stream 11 is fed into the bottom of the aromatics extraction tower. Under the action of the crude oil dearomatization solvents sulfolane and dimethyl sulfoxide, the raffinate at the top of the tower is obtained as the first lean aromatics crude oil stream, and the bottom of the tower is obtained as the first rich aromatics stream. The mass ratio of sulfolane to dimethyl sulfoxide is 9:1, and the mass ratio of pretreated crude oil to crude oil dearomatization solvent is 1:8.

[0115] ii) The first lean aromatic crude oil stream is fed to the bottom of the water washing tower. After water washing, the second lean aromatic stream 12 is obtained at the top of the tower and used as a cracking feedstock for fractionation. The water at the bottom of the tower is sent to the solvent recovery tower.

[0116] iii) The first aromatic hydrocarbon-rich stream is fed to the bottom of the stripping tower, and the backwash stream is obtained at the top of the stripping tower. After condensation and water separation, it is sent to the liquid-liquid extraction tower through the backwash stream pipeline. The separated water stream is sent to the solvent recovery tower. The second aromatic hydrocarbon-rich stream is obtained at the bottom of the stripping tower. The operating pressure of the liquid-liquid extraction tower is 0.12 MPa, and the temperature is 25-50℃.

[0117] iv) The second aromatic hydrocarbon stream is fed into the solvent recovery tower.

[0118] v) A third aromatic-rich stream 16 is obtained at the top of the solvent recovery tower, and a solvent stream with an aromatic content of less than 0.5 wt% is obtained at the bottom of the tower. The stream is then sent back to the top of the liquid-liquid extraction tower after heat exchange.

[0119] After dearomatization, a second aromatic-lean stream 12 and a third aromatic-rich stream 16 are obtained. The aromatic content of the second aromatic-lean stream 12 is reduced from 26.42 wt% to 1.44%. The remaining components are incorporated into the fourth aromatic-rich stream 22 from the third aromatic-rich stream 16 and then enter the aromatic separation unit 9 for aromatic separation.

[0120] 3. The second lean aromatics stream 12 enters the feed fractionation unit 3, and through fractionation, the cracking unit feed stream 13 is obtained, which contains the first crude oil light component stream and the first crude oil heavy component stream. The first crude oil light component stream contains alkane stream with a final boiling point of less than 200°C (accounting for about 19.8 wt% of crude oil), and the remainder is the first crude oil heavy component stream.

[0121] 4. The feed stream 13 of the cracking unit, containing the light component and heavy component of the first crude oil, enters the cracking unit 4. The light component of the first crude oil in the feed stream 13 enters the light cracking furnace for cracking, serving as the feedstock for the light cracking furnace. The heavy component of the first crude oil in the feed stream 13 enters the heavy cracking furnace for cracking. Specifically, after preheating in the feed preheating section of the heavy cracking furnace, the heavy component of the first crude oil is separated by a separator to obtain the first residue oil stream 24, which has a final boiling point above 540°C. The remainder is the second heavy component of the second crude oil, which serves as the feedstock for the heavy cracking furnace.

[0122] 5. The first residue oil stream 24 enters the residue oil hydrotreating unit 6 for hydrotreating, and the resulting residue oil hydrotreating unit product stream 18 is used as a cracking feedstock and incorporated into the cracking unit feed stream 13. The remaining products of the residue oil hydrotreating unit 6 are sent out as the second residue oil stream 19.

[0123] 6. The pyrolysis product stream 14 obtained from the pyrolysis unit 4 enters the separation unit 5 for product separation.

[0124] 7. The cracked gasoline stream 20 obtained from the separation unit 5 enters the gasoline hydrogenation unit 7 for hydrogenation treatment to obtain the hydrogenated cracked gasoline stream 21. The hydrogenated cracked gasoline stream 21 is then subjected to aromatic extraction treatment in the aromatic extraction unit 8 to obtain the fourth aromatic-rich stream 22 and the dearomatized hydrogenated cracked gasoline stream 17. The dearomatized hydrogenated cracked gasoline stream 17 is used as a cracking feedstock and is incorporated into the feed stream 13 of the cracking unit. The fourth aromatic-rich stream 22 enters the aromatic separation unit 9 for aromatic separation treatment to finally obtain the aromatic separation product stream 23.

[0125] The yields of low-carbon olefins in Example 3 are detailed in Table 2, and the yields of aromatics are detailed in Table 3.

[0126] Table 2. Low-carbon olefin yields of light crude oil cracking unit feedstocks in the examples.

[0127]

[0128] Table 3. Aromatics yield of light crude oil in the examples

[0129]

[0130] As shown in Table 2, the yield of low-carbon olefins in Example 2 is significantly higher than that in Example 1. Therefore, using aromatic-containing light crude oil to remove aromatics through an aromatics process before using it as cracking feedstock will benefit the yield of low-carbon olefins under light crude oil operating conditions. Example 3 provides a relatively high-quality cracking feedstock by separating the residue from the light crude oil and then hydrogenating it, further increasing the yield of low-carbon olefins. Meanwhile, Examples 2 and 3 significantly improved the operating cycle of the cracking furnace after aromatics pre-separation, demonstrating the importance of the aromatics pre-separation process for the direct cracking of aromatic-containing light crude oil.

[0131] As shown in Table 3, compared to Example 1, Example 2, through the dearomatization process, can effectively improve the yield of aromatics while increasing the yield of low-carbon olefins. Meanwhile, Example 3, through residue hydrotreating, improves the utilization rate of light crude oil, increases the total feedstock of the cracking unit, and improves the yield of low-carbon olefins and aromatics, maximizing the utilization rate of aromatic-containing light crude oil.

[0132] Therefore, this raw material processing scheme can maximize the yield of aromatic light crude oil as raw material and extend the operating cycle of crude oil processing.

Claims

1. A method for producing low-carbon olefins and aromatics from light crude oil containing aromatics, characterized in that, The method includes the following steps: 1) Pre-treat light crude oil containing aromatics to obtain pre-treated crude oil; 2) The pretreated crude oil is subjected to feedstock fractionation to obtain the feed stream (13) of the cracking unit, which includes the light component stream of the first crude oil and the heavy component stream of the first crude oil; The fractionation process involves separating the alkane stream with a final boiling point of less than 300°C to obtain the first crude oil light component stream, while the remaining components are the first crude oil heavy component stream. 3) The first crude oil light component stream and the first crude oil heavy component stream are respectively subjected to cracking treatment to obtain cracking product stream (14) and first residue oil stream (24). The first crude oil light component stream is sent to a light cracking furnace and the first crude oil heavy component stream is sent to a heavy cracking furnace. Both the light cracking furnace and the heavy cracking furnace adopt the tubular high-temperature steam cracking method. The outlet temperature of the light cracking furnace is 800-870 ℃, the residence time is 0.2-0.3 s, and the dilution steam ratio is 1:(0.3-0.6). The outlet temperature of the heavy cracking furnace is 800-870 ℃, the residence time is 0.2-0.3 s, and the dilution steam ratio is 1:(0.5-0.8). The cracking product stream (14) includes the first crude oil cracking product stream and the second crude oil cracking product stream. The first residue oil stream (24) is discharged externally. 4) The first crude oil cracking product stream and the second crude oil cracking product stream are subjected to product separation treatment to obtain the separated product stream (15) and the cracked gasoline stream (20). 5) The cracked gasoline stream (20) is subjected to gasoline hydrogenation treatment to obtain hydrogenated cracked gasoline stream (21); 6) The hydrocracking gasoline stream (21) was subjected to aromatic extraction treatment to obtain the fourth aromatic-rich stream (22). 7) The fourth aromatic hydrocarbon stream (22) is subjected to aromatic hydrocarbon separation treatment to obtain aromatic hydrocarbon separation product stream (23).

2. The method according to claim 1, characterized in that, The method includes the following steps: 1) Pre-treat light crude oil containing aromatics to obtain pre-treated crude oil; 2) The pretreated crude oil is subjected to dearomatic treatment to obtain a second aromatic-lean stream (12) and a third aromatic-rich stream (16). 3) Perform aromatic separation treatment on the third aromatic hydrocarbon-rich stream (16); 4) The second lean aromatics stream (12) is subjected to feedstock fractionation to obtain the cracking unit feedstock (13), which includes the first crude oil light component stream and the first crude oil heavy component stream; 5) The first crude oil light component stream and the first crude oil heavy component stream are respectively subjected to cracking treatment to obtain cracking product stream (14) and first residue stream (24), wherein the cracking product stream (14) includes the first crude oil cracking product stream and the second crude oil cracking product stream, and the first residue stream (24) is discharged. 6) The first crude oil cracking product stream and the second crude oil cracking product stream are subjected to product separation treatment to obtain the separated product stream (15) and the cracked gasoline stream (20). 7) The cracked gasoline stream (20) is subjected to gasoline hydrogenation treatment to obtain hydrogenated cracked gasoline stream (21); 8) The hydrocracking gasoline stream (21) is subjected to aromatic extraction treatment to obtain a fourth aromatic-rich stream (22) and a hydrocracking gasoline stream (17) after aromatic removal. The hydrocracking gasoline stream (17) after aromatic removal is used as a cracking feedstock and fed into the cracking unit feed stream (13). 9) The fourth aromatic hydrocarbon stream (22) is subjected to aromatic hydrocarbon separation treatment to obtain the aromatic hydrocarbon separation product stream (23).

3. The method according to claim 1, characterized in that, The method includes the following steps: 1) Pre-treat light crude oil containing aromatics to obtain pre-treated crude oil; 2) The pretreated crude oil is subjected to dearomatic treatment to obtain a second aromatic-lean stream (12) and a third aromatic-rich stream (16). 3) Perform aromatic separation treatment on the third aromatic hydrocarbon-rich stream (16); 4) The second lean aromatics stream (12) is subjected to feedstock fractionation to obtain the cracking unit feedstock (13), which includes the first crude oil light component stream and the first crude oil heavy component stream; 5) The first crude oil light component stream and the first crude oil heavy component stream are respectively subjected to cracking treatment to obtain cracking product stream (14) and first residue oil stream (24), wherein the cracking product stream (14) includes the first crude oil cracking product stream and the second crude oil cracking product stream. 6) The first crude oil cracking product stream and the second crude oil cracking product stream are subjected to product separation treatment to obtain the separated product stream (15) and the cracked gasoline stream (20). 7) The first residue oil stream (24) is subjected to residue oil hydrotreating to obtain residue oil hydrotreating unit product stream (18) and second residue oil stream (19). The residue oil hydrotreating unit product stream (18) is incorporated into the cracking unit feed stream (13) as cracking feedstock, and the second residue oil stream (19) is discharged. 8) The cracked gasoline stream (20) is subjected to gasoline hydrotreating to obtain hydrotreated cracked gasoline stream (21); 9) The hydrocracking gasoline stream (21) is subjected to aromatic extraction treatment to obtain a fourth aromatic-rich stream (22) and a hydrocracking gasoline stream (17) after aromatic removal. The hydrocracking gasoline stream (17) after aromatic removal is used as a cracking feedstock and fed into the cracking unit feed stream (13). 10) The fourth aromatic hydrocarbon stream (22) was subjected to aromatic hydrocarbon separation treatment to obtain the aromatic hydrocarbon separation product stream (23).

4. The method according to claim 1, characterized in that, The aromatic light crude oil has a final boiling point of less than or equal to 1000℃ and an aromatic content of less than 50 wt%.

5. The method according to claim 4, characterized in that, The aromatic hydrocarbon content is 10-30 wt%.

6. The method according to claim 1, characterized in that, In step 1), the pretreated crude oil has a desalination rate of 95.0-99.9 wt%, a dehydration rate of 95.0-99.0 wt%, and a sulfur content of less than 30 ppm.

7. The method according to claim 2, characterized in that, In step 2), the dearomatic treatment includes the following steps: i) The pretreated crude oil is fed into the bottom of the aromatics extraction tower. Under the action of the crude oil dearomatization solvent, the raffinate at the top of the tower is the first lean aromatics crude oil stream, and the bottom of the tower is the first rich aromatics stream. ii) The first lean aromatic crude oil stream is sent to the bottom of the water washing tower. After water washing, the second lean aromatic stream (12) is obtained at the top of the tower and used as a cracking feedstock for fractionation. The water at the bottom of the tower is sent to the solvent recovery tower. iii) The first aromatic hydrocarbon-rich stream is fed to the bottom of the stripping tower, and the backwash stream is obtained at the top of the stripping tower. After condensation and water separation, the backwash stream is sent to the liquid-liquid extraction tower through the backwash stream pipeline. The separated water stream is sent to the solvent recovery tower. The second aromatic hydrocarbon-rich stream is obtained at the bottom of the stripping tower. iv) The second aromatic hydrocarbon-rich stream is fed into a solvent recovery tower; v) A third aromatic-rich stream (16) is obtained at the top of the solvent recovery tower, and a solvent stream with an aromatic content of less than 0.5 wt% is obtained at the bottom of the tower. The stream is then sent back to the top of the liquid-liquid extraction tower after heat exchange.

8. The method according to claim 7, characterized in that, The crude oil dearomatization solvent is selected from one or more combinations of methanol, acetonitrile, isopropanol, ethylene glycol, triethylene glycol, tetraethylene glycol, pentaethylene glycol, sulfolane, dimethyl sulfoxide, dimethylformamide, N-methylpyrrolidone, N-formylmorpholine, methylimidazolium, butylpyridine, furfural, ketone, water, and potassium thiocyanate.

9. The method according to claim 7, characterized in that, The mass ratio of the crude oil dearomatization solvent to the pretreated crude oil in the liquid-liquid extraction tower is 1:(2-10). The operating pressure of the liquid-liquid extraction tower is 0.1 MPa - 1.2 MPa, and the temperature is 25-100 ℃.

10. The method according to claim 1, characterized in that, After the first crude oil heavy fraction is preheated in the heavy cracking furnace, the fraction is separated into residue oil components at 450°C or above as the first residue oil stream (24) for residue oil hydrogenation treatment, and the remainder is the second crude oil heavy fraction stream sent to the heavy cracking furnace as cracking feedstock.

11. The method according to claim 1, characterized in that, In step 6), the separated product stream (15) and the cracked gasoline stream (20) contain hydrogen, methane, ethylene, propylene, butadiene, cracked gasoline, and cracked tar.

12. An apparatus for producing low-carbon olefins and aromatics from aromatic light crude oil according to claim 3, characterized in that, The device includes: Pretreatment unit (1), Aromatics removal unit (2), Feed fractionation unit (3), Cracking unit (4), Separation unit (5), Residue hydrogenation unit (6), Gasoline hydrogenation unit (7), Aromatics extraction unit (8), Aromatics separation unit (9); Wherein: The pretreatment unit (1) is provided with a raw material inlet, and the outlet of the pretreatment unit (1) is connected to the inlet of the dearomatic unit (2); The first outlet and the second outlet of the dearomatic unit (2) are respectively connected to the inlet of the raw material fractionation unit (3) and the aromatic separation unit (9); The outlet of the raw material fractionation unit (3) is connected to the inlet of the cracking unit (4); The first outlet and the second outlet of the pyrolysis unit (4) are respectively connected to the inlet of the separation unit (5) and the inlet of the residue hydrotreating unit (6); The first outlet of the separation unit (5) is connected to the inlet of the gasoline hydrogenation unit (7), and the separation unit (5) is also provided with a second outlet; The first outlet of the residue hydrotreating unit (6) is connected to the inlet of the cracking unit (4), and the residue hydrotreating unit (6) is also provided with a second outlet; The outlet of the gasoline hydrogenation unit (7) is connected to the inlet of the aromatics extraction unit (8); The first outlet and the second outlet of the aromatic extraction unit (8) are respectively connected to the inlet of the aromatic separation unit (9) and the inlet of the cracking unit (4); The aromatic hydrocarbon separation unit (9) is provided with an outlet for aromatic hydrocarbon separation products.

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