A method, system and related applications for the separation of aromatics in diesel

Abstract

This invention discloses a method, system, and related applications for separating aromatics from diesel fuel. The method includes: adding diesel fuel through a diesel fuel inlet in the middle of the first chamber of a partition tower; adding an extraction solvent through an extraction solvent inlet at the top of the first chamber; and adding a back-extraction solvent through a back-extraction solvent inlet at the bottom of the second chamber. The diesel fuel contacts the extraction solvent in the first chamber to separate raffinate containing non-aromatics, which is output from the top raffinate outlet, while the extraction solvent is output from the bottom extraction solvent outlet. The diesel fuel then contacts the back-extraction solvent through a connecting area at the bottom of the first and second chambers to separate extract oil containing aromatics and the back-extraction solvent. This extract oil is output from the upper extract oil outlet to a solvent recovery tower for further separation. The back-extraction solvent is output from the top of the solvent recovery tower, and aromatics are output from the bottom aromatics outlet. This method can efficiently separate aromatics from diesel fuel, with a simple and short process flow, low energy consumption, and low equipment investment and cost.

Description

Technical Field

[0001] This invention relates to the field of diesel fuel processing technology, and in particular to a method, system, and related applications for separating aromatic hydrocarbons from diesel fuel. Background Technology

[0002] Diesel fractions mainly originate from atmospheric and vacuum distillation, catalytic cracking, and hydrocracking units. Diesel fractions primarily contain aromatic and non-aromatic components. Among the aromatic components, monocyclic and polycyclic aromatic hydrocarbons are unsuitable as diesel blending components, while non-aromatic hydrocarbons are suitable for diesel blending and as chemical feedstock components. With my country's refining and chemical transformation and high-quality development, the trend of diesel surplus is intensifying. Efficient, low-energy-consumption, and flexible production to fully utilize diesel blending components is an important path for the high-quality and sustainable development of petrochemical enterprises. Summary of the Invention

[0003] The inventors of this application have discovered that current diesel fraction separation generally employs 3-4 or even up to 6 traditional distillation columns for separation or simulated moving bed adsorption separation to obtain corresponding aromatic and non-aromatic products. These existing fraction separation methods for separating aromatics from diesel have long process flows, complex operations, large equipment investment, high energy consumption, low product yield, and high production costs.

[0004] In view of the above problems, the present invention is proposed to provide a method, system and related applications for separating aromatics from diesel fuel that overcomes or at least partially solves the above problems.

[0005] This invention provides a method for separating aromatics from diesel fuel, comprising:

[0006] Diesel fuel is added from the diesel fuel inlet in the middle of the first chamber of the adjacent tower, extraction solvent is added from the extraction solvent inlet at the top of the first chamber, and back-extraction solvent is added from the back-extraction solvent inlet at the bottom of the second chamber of the adjacent tower.

[0007] The diesel fuel is in contact with the extraction solvent in the first chamber to separate the raffinate containing non-aromatic hydrocarbons, which is then output from the raffinate outlet at the top of the first chamber, while the extraction solvent is output from the extraction solvent outlet at the bottom of the first chamber.

[0008] The diesel fuel comes into contact with the back-extraction solvent through the bottom connecting area of ​​the first and second chambers, separating the extracted oil containing aromatics and the back-extraction solvent. The extracted oil is then output from the extracted oil outlet in the upper part of the second chamber to the solvent recovery tower, where the extracted oil is separated. The back-extraction solvent is output from the back-extraction solvent outlet at the top of the solvent recovery tower, and the aromatics are output from the aromatics outlet at the bottom.

[0009] In some optional embodiments, the diesel fuel is contacted with an extraction solvent in a first chamber to separate a raffinate containing non-aromatic hydrocarbons, which is then output from a raffinate outlet at the top of the first chamber, including:

[0010] The diesel fuel is in contact with the extraction solvent in the first chamber and heated by the reboiler in the tower. Under the action of the extraction solvent, the non-aromatic hydrocarbons in the diesel fuel evaporate to the top. After being condensed by the top condenser, the raffinate containing non-aromatic hydrocarbons is output from the raffinate outlet at the top of the first chamber.

[0011] In some optional embodiments, the diesel fuel is contacted with the back-extraction solvent via a communication region at the bottom of the first and second chambers to separate extractable oil containing aromatics and the back-extraction solvent, which is then output from the extractable oil outlet in the upper part of the second chamber, including:

[0012] The diesel fuel is in contact with the back-extraction solvent in the bottom connecting area of ​​the first and second chambers or in the second chamber. It is heated by the reboiler in the tower bottom. Under the action of the back-extraction solvent, the remaining aromatics in the diesel fuel and the back-extraction solvent evaporate upward together. After being condensed by the condenser, the extracted oil containing aromatics and back-extraction solvent is output from the extracted oil outlet in the upper part of the second chamber.

[0013] In some optional embodiments, the separation of the extracted oil in the solvent recovery tower, with the back-extraction solvent being output from the top back-extraction solvent outlet and the aromatics being output from the bottom aromatics outlet, includes:

[0014] In the solvent recovery tower, the extracted oil is heated by the reboiler in the bottom of the tower to evaporate the back-extraction agent to the top. After being condensed by the condenser at the top, the back-extraction solvent is output from the top back-extraction solvent outlet, and the remaining aromatics are output from the bottom aromatics outlet.

[0015] In some optional embodiments, the ratio of the inner surface area of ​​the tower wall of the first cavity and the second cavity is 3:7 to 7:3.

[0016] In some optional embodiments, the above further includes: after the extraction solvent is discharged from the extraction solvent outlet at the bottom of the first chamber, it is conveyed to the extraction solvent inlet and added to the partition wall column; and / or

[0017] The back-extraction solvent output from the top of the solvent recovery tower is fed into the partition tower via the back-extraction solvent inlet.

[0018] In some optional embodiments, the mass ratio of the back-extractant to diesel oil is 0.5-6, and the mass ratio of the extractant to back-extractant is 0.01-2.

[0019] In some optional embodiments, the extraction solvent is an organic solvent or an ionic liquid, wherein the organic solvent is at least one of N,N-dimethylformamide, dimethyl sulfoxide, N,N-diethylformamide, ethylene glycol methyl ether, furfural, or morpholine; the cation in the ionic liquid is one of imidazole cations and pyridine cations, and the anion in the ionic liquid is at least one of tetrafluoroborate anion, hexafluorophosphate anion, and bis(trifluoromethanesulfonate)imine anion.

[0020] In some optional embodiments, the cationic 1-methyl-3-ethylimidazolium cationic MEIM + 1-Heptyl-3-methylimidazolium cationic C7MIM + 1,3-Dimethylpyridine MMPY + At least one of the cations; the anion is tetrafluoroboric acid and BF4. -1 Anions and hexafluorophosphate with PF6 - At least one of the anions.

[0021] In some optional embodiments, the back-extraction solvent is at least one of C4-C10 alkanes and cycloalkanes.

[0022] In some optional embodiments, the back-extraction solvent is at least one selected from cyclohexane, n-heptane, n-octane, and n-hexane.

[0023] In some optional embodiments, the theoretical number of plates in the partition tower is 20-150, the operating pressure during use is 0.05-2 MPa, the top temperature is 20-120°C, and the bottom temperature is 50-150°C.

[0024] In some optional embodiments, the solvent recovery tower has a theoretical plate number of 5-40, and during use, the operating pressure is 10 kPa-0.2 MPa, the top temperature is 20-120°C, and the bottom temperature is 45-150°C.

[0025] This invention provides a separation system for aromatics in diesel fuel, comprising: a partition wall tower and a solvent recovery tower;

[0026] The partition tower has an internal partition wall that divides the tower body into a first inner cavity and a second inner cavity that are connected at the bottom. The bottom of the tower body has an extraction solvent outlet. The first cavity has a diesel inlet in the middle and an extraction solvent inlet and a raffinate outlet at the top. The upper half of the second cavity has an extractable oil outlet and a back-extraction solvent inlet at the bottom. The partition tower is used to allow diesel entering from the diesel inlet to contact with the extraction solvent entering from the extraction solvent inlet in the first cavity, separating raffinate oil containing non-aromatics and outputting it from the raffinate oil outlet. Diesel is then allowed to contact with back-extraction solvent entering from the back-extraction solvent inlet via the bottom connecting area of ​​the first cavity and the second cavity, separating extractable oil containing aromatics and back-extraction solvent and outputting it from the extractable oil outlet. The extraction solvent is output from the extraction solvent outlet.

[0027] The solvent recovery tower has an oil extraction inlet in the middle, an aromatics outlet at the bottom, and a back-extraction solvent outlet at the top. The oil extraction inlet is connected to the oil extraction outlet of the partition tower. The solvent recovery tower is used to separate aromatics from the oil extracted from the partition tower and output them from the aromatics outlet, and to separate the back-extraction solvent from the oil extracted from the partition tower and output them from the back-extraction solvent outlet.

[0028] In some alternative embodiments, the partition wall of the partition tower is an intermediate partition wall;

[0029] The adjacent tower is equipped with at least one reboiler and / or at least one condenser.

[0030] In some alternative embodiments, the solvent recovery tower is provided with at least one reboiler and / or at least one condenser.

[0031] In some optional embodiments, the ratio of the inner surface area of ​​the tower wall of the first cavity and the second cavity is 3:7 to 7:3.

[0032] In some optional embodiments, the extraction solvent outlet and extraction solvent inlet of the partition column are connected so that the extraction solvent output from the extraction solvent outlet is conveyed to the extraction solvent inlet and added into the partition column; and / or

[0033] The back-extractant outlet of the solvent recovery tower is connected to the back-extractant inlet of the partition tower, and is used to provide the back-extraction solvent output from the solvent recovery tower to the partition tower.

[0034] In some optional embodiments, the theoretical number of plates in the partition tower is 20-150, the operating pressure during use is 0.05-2 MPa, the top temperature is 20-120°C, and the bottom temperature is 50-150°C.

[0035] In some optional embodiments, the solvent recovery tower has a theoretical plate number of 5-40, and during use, the operating pressure is 10 kPa-0.2 MPa, the top temperature is 20-120°C, and the bottom temperature is 45-150°C.

[0036] This invention provides a partition tower, comprising: a hollow tower body;

[0037] The tower body is equipped with an isolation wall that divides the interior of the tower body into a first inner cavity and a second inner cavity that are connected at the bottom.

[0038] The bottom of the tower body is provided with an extraction solvent outlet;

[0039] The first chamber has a diesel inlet in the middle and an extraction solvent inlet and a raffinate outlet at the top;

[0040] The upper part of the second chamber is provided with an oil extraction outlet, and the bottom is provided with a back-extraction solvent inlet.

[0041] In some optional embodiments, the ratio of the inner surface area of ​​the tower wall of the first cavity and the second cavity is 3:7 to 7:3, and the number of theoretical plates is 20-150.

[0042] In some optional embodiments, the partition wall of the partition wall column is an intermediate partition wall; the bottom of the partition wall column is provided with a reboiler, and / or the top of the column is provided with at least one condenser.

[0043] This invention provides a method for separating aromatics from diesel fuel using the aforementioned diesel fuel aromatics separation system.

[0044] This invention provides an application of the above-mentioned method for separating aromatics from diesel fuel in the process of separating aromatics from diesel fuel.

[0045] The beneficial effects of the above-described technical solutions provided in the embodiments of the present invention include at least the following:

[0046] By employing a partition wall tower and a solvent recovery tower, along with the appropriate addition of extraction and back-extraction solvents, aromatics can be effectively separated from diesel fuel using only two towers: one partition wall tower and one recovery tower. Diesel fuel contacts the extraction solvent in one chamber of the partition wall tower, separating aromatics. It then enters the other chamber, where it contacts the back-extraction solvent, separating extract oil containing both the back-extraction solvent and aromatics. Finally, the back-extraction solvent is separated in the solvent recovery tower, yielding the aromatics. This method achieves efficient separation of aromatics from diesel fuel using only one partition wall tower and one solvent recovery tower. The process is simple, short, energy-efficient, requires minimal equipment investment, and is cost-effective.

[0047] Other features and advantages of the invention will be set forth in the description which follows, and will be apparent in part from the description, or may be learned by practicing the invention. The objects and other advantages of the invention may be realized and obtained by means of the structures particularly pointed out in the written description, claims, and drawings.

[0048] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0049] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used in conjunction with embodiments of the invention to explain the invention and do not constitute a limitation thereof. In the drawings:

[0050] Figure 1 This is a schematic diagram of the separation system for aromatics in diesel fuel in an embodiment of the present invention;

[0051] Figure 2 This is a schematic diagram of the structure of the partition tower with an intermediate partition in an embodiment of the present invention;

[0052] Figure 3 This is a flowchart of a method for separating aromatics from diesel fuel in an embodiment of the present invention. Detailed Implementation

[0053] Exemplary embodiments of the present disclosure will now be described in more detail with reference to the accompanying drawings. While exemplary embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure may be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art.

[0054] To address the problems of long process flow, complex operation, large equipment investment, high energy consumption, low product yield, and high production cost in the separation of aromatics from diesel fuel in existing technologies, this invention provides a method and system for separating aromatics from diesel fuel. This method achieves efficient separation of aromatics from diesel fuel using only a partition wall tower and a solvent recovery tower. The process is simple, short, energy-efficient, requires minimal equipment investment, and has low cost.

[0055] This invention provides a separation system for aromatics in diesel fuel, the structure of which is as follows: Figure 1 As shown, it includes: partition tower 6 and solvent recovery tower 8.

[0056] The partition tower 6 has an internal partition wall that divides the tower body into a first inner cavity and a second inner cavity that are connected at the bottom. The bottom of the tower body has an extraction solvent outlet. The middle of the first cavity has a diesel inlet, and the top has an extraction solvent inlet and a raffinate outlet. The upper half of the second cavity has an extractable oil outlet, and the bottom has a back-extraction solvent inlet. The partition tower is used to allow diesel entering from the diesel inlet to contact with the extraction solvent entering from the extraction solvent inlet in the first cavity, separating the raffinate oil containing non-aromatics and outputting it from the raffinate oil outlet. Diesel is then allowed to contact with the back-extraction solvent entering from the back-extraction solvent inlet through the bottom connecting area of ​​the first cavity and the second cavity, separating the extractable oil containing aromatics and back-extraction solvent and outputting it from the extractable oil outlet. The extraction solvent is output from the extraction solvent outlet.

[0057] Solvent recovery tower 8 has an oil extraction inlet in the middle, an aromatics outlet at the bottom, and a back-extraction solvent outlet at the top. The oil extraction inlet is connected to the oil extraction outlet of the adjacent tower. The solvent recovery tower is used to separate aromatics from the oil extracted from the adjacent tower and output them from the aromatics outlet, and to separate the back-extraction solvent from the back-extraction solvent outlet.

[0058] The oil extraction outlet in the upper part of the second chamber refers to the oil extraction outlet being located slightly above the middle of the second chamber, i.e., at a position greater than 1 / 2 of the total height of the adjacent tower. Preferably, the oil extraction outlet is not located at the very top, but rather at a position slightly above the middle, at 2 / 3 to 4 / 5 of the total height of the adjacent tower.

[0059] In some alternative embodiments, the partition wall column 6 may be a partition wall distillation column, and the partition wall of the partition wall column 6 is an intermediate partition wall. For example... Figure 2 The diagram shows a partition tower with a central partition wall, where the bottom and top are connected, separated by a partition wall in the middle. Alternatively, the partition tower can also be a partition tower structure with an upper partition wall, where only the bottom is connected, and the middle and top are separated by a partition wall.

[0060] Preferably, the raffinate outlet at the top of the first chamber of the adjacent tower is higher than the extraction solvent inlet; the back-extraction solvent inlet at the bottom of the second chamber is positioned slightly above the bottom, higher than the extraction and outlet.

[0061] The extraction solvent outlet and extraction solvent inlet of the adjacent column are connected so that the extraction solvent output from the extraction solvent outlet is conveyed to the extraction solvent inlet and added to the adjacent column, such as... Figure 1 As shown, the extraction solvent output from the extraction solvent outlet can be partially fed to the extraction solvent inlet and added to the partition column together with the new extraction solvent, and partially separated and recovered.

[0062] In the partition tower, the partition wall is not located in the middle, but rather offset to one side. For example, the ratio of the inner surface area of ​​the first and second chamber walls is 3:7 to 7:3, meaning the area ratio of the feed side to the product output side of the partition tower is within the range of 3:7 to 7:3. Multiple layers of plates are installed within the two chambers of the partition tower, dividing the internal space into multiple layers. Preferably, the theoretical number of plates in the partition tower is 20-150. During operation, the operating pressure is 0.05-2 MPa, the top temperature is 20-120℃, and the bottom temperature is 50-150℃.

[0063] The partition column is equipped with at least one reboiler and / or at least one condenser. Preferably, the partition column has at least one reboiler in the bottom and / or at least one condenser at the top. The bottom refers to the liquid-containing area at the lower end of the container, which is part of the container's volume; it is not the bottom of the column, but generally refers to the lower part of the column where the liquid phase evaporates. The condenser and reboiler in the partition column can have different combinations, including but not limited to the following: two condensers and one reboiler; one condenser and one reboiler; no condenser or one reboiler; two condensers and no reboiler; one condenser and no reboiler, etc. Optionally, the condenser and reboiler can also be located in the middle of the column.

[0064] In some optional embodiments, the back-extractant outlet of the solvent recovery tower is connected to the back-extractant inlet of the partition tower, so as to provide the back-extraction solvent output from the solvent recovery tower to the partition tower, so that the separated back-extraction solvent and the new back-extraction solvent can be added to the partition tower for reuse, and part of the back-extraction solvent can be recovered.

[0065] The solvent recovery tower is equipped with multiple plates to divide the internal space into multiple spaces. Preferably, the theoretical number of plates in the solvent recovery tower is 5-40. During use, the operating pressure is 10 kPa-0.2 MPa, the top temperature is 20-120℃, and the bottom temperature is 45-150℃.

[0066] The solvent recovery column is equipped with at least one reboiler and at least one condenser. Preferably, the solvent recovery column has at least one reboiler at the bottom and at least one condenser at the top. The solvent recovery column can be a conventional distillation column; optionally, the condenser and reboiler can also be located in the middle of the column.

[0067] The aforementioned partition tower and solvent recovery tower are equipped with necessary auxiliary equipment such as pumps and heat exchangers, which will not be described in detail in this application.

[0068] This invention also provides a partition tower, comprising: a hollow tower body;

[0069] The tower body is equipped with an isolation wall that divides the interior of the tower body into a first inner cavity and a second inner cavity that are connected at the bottom; the bottom of the tower body is equipped with an extraction solvent outlet; the middle of the first cavity is equipped with a diesel inlet, and the top is equipped with an extraction solvent inlet and a raffinate oil outlet; the upper half of the second cavity is equipped with an extracted oil outlet, and the bottom is equipped with a back-extraction solvent inlet.

[0070] The partition wall inside the partition tower is a partition plate, which divides the partition tower into two sides. For the upper partition tower, the partition plate extends to the top of the partition tower, so that the two sides at the top are not connected. There is a gap between the lower end of the partition plate and the bottom of the partition tower, so that the two sides are connected in the bottom section of the tower. Diesel and extraction solvent enter from the top and bottom of the same side, respectively. The back-extraction solvent enters from the bottom of the other side. The raffinate oil is separated from the diesel feed side at the top of the tower, and the extracted oil is separated from the back-extraction solvent feed side at the top of the tower and enters the solvent recovery tower. The extraction solvent is discharged from the bottom of the partition tower.

[0071] The ratio of the inner surface area of ​​the tower walls of the first and second cavities is 3:7 to 7:3, and the theoretical number of plates is 20-150.

[0072] The partition wall of the partition column is an upper partition wall or an intermediate partition wall; the bottom of the partition column is equipped with a reboiler, and / or the top of the column is equipped with at least one condenser.

[0073] The above-mentioned aromatic hydrocarbon separation system for diesel fuel has a simple process flow. In practical applications, the extraction solvent and back-extraction solvent can be new, or they can be the extraction solvent recovered from the adjacent tower, the back-extraction solvent recovered from the recovery tower, or a mixture of new and recovered solvents. The following explanation uses a mixture as an example. See [link to documentation]. Figure 1As shown, the system mainly includes a partition column 6 and a solvent recovery column 8. The partition column 6 separates the aromatic fraction, non-aromatic fraction, and extraction solvent in the diesel fuel. The solvent recovery column 8 separates the back-extraction solvent from the aromatics. Ultimately, this achieves efficient utilization of the aromatic and non-aromatic fractions in the diesel fuel. Diesel fuel 1 enters from the middle of the partition column 6. The new extraction solvent 2 and the extraction solvent 14 returned from the bottom of the partition column 6 are mixed to form extraction solvent 4, which enters from the upper part of the same side of the partition column along with diesel fuel 1. Residual oil 5, mainly non-aromatics, is separated from the side where diesel fuel and extraction solvent enter from the top of the partition column. The back-extraction solvent 12 (including the new back-extraction solvent 11 and the back-extraction solvent 15 returned from the solvent recovery column) enters from the bottom of the other side of the partition column 6. Extracted oil 7, mainly back-extraction solvent and aromatics, is extracted from the top of the partition column 6 on the side where the back-extraction solvent enters. The extract solvent 3 distilled from the bottom of the adjacent column 6 enters the solvent recovery column 8 and is divided into two parts. One part, extract solvent 14, is mixed with fresh extract solvent 2 and returned to the adjacent column 6 for recycling. The other part, extract solvent 13, can be discharged from the column for recovery. The extracted oil 7 from the adjacent column 6 enters the solvent recovery column 8 and is separated from the top of the column into back-extraction solvent 9. The back-extraction solvent 9 can be divided into two parts. One part, back-extraction solvent 15, is mixed with fresh back-extraction solvent 11 and returned to the adjacent column 6 for recycling. The other part, back-extraction solvent 16, can be discharged from the column for recovery.

[0074] Based on the same inventive concept, embodiments of the present invention provide a method for separating aromatics from diesel fuel, the process of which is as follows: Figure 3 As shown, it includes the following steps:

[0075] Step S101: Add diesel fuel from the diesel fuel inlet in the middle of the first chamber of the adjacent tower, add extraction solvent from the extraction solvent inlet at the top of the first chamber, and add back-extraction solvent from the back-extraction solvent inlet at the bottom of the second chamber of the adjacent tower.

[0076] Diesel fuel, extraction solvent, and back-extraction solvent enter the adjacent column. The amount of each solvent can be adjusted as needed. Preferably, the mass ratio of back-extraction agent to diesel fuel is 0.5-6, and the mass ratio of extraction agent to back-extraction agent is 0.01-2.

[0077] Step S102: Diesel fuel comes into contact with the extraction solvent in the first chamber, separating the raffinate containing non-aromatic hydrocarbons. The raffinate is output from the raffinate outlet at the top of the first chamber, and the extraction solvent is output from the extraction solvent outlet at the bottom of the first chamber.

[0078] Residual oil 5, mainly composed of non-aromatic hydrocarbons, is separated from the diesel feed side at the top of adjacent column 6. Extraction solvent 3 is separated from the bottom of adjacent column 6. Specifically, diesel fuel comes into contact with the extraction solvent in the first chamber and is heated by the reboiler in the bottom of the column. Under the action of the extraction solvent, the non-aromatic hydrocarbons in the diesel fuel evaporate to the top. After condensation by the top condenser, residual oil containing non-aromatic hydrocarbons is output from the residual oil outlet at the top of the first chamber.

[0079] Step S103: Diesel fuel comes into contact with the back-extraction solvent through the bottom connecting area of ​​the first chamber and the second chamber, separating the extracted oil containing aromatics and the back-extraction solvent, and outputting it from the extracted oil outlet in the upper part of the second chamber to the solvent recovery tower.

[0080] The extracted oil 7, mainly composed of aromatics and back-extraction solvent, is separated from the feed side of the back-extraction solvent at the top of the adjacent tower 6 and enters the solvent recovery tower 8. Specifically, diesel oil comes into contact with the back-extraction solvent in the bottom connecting area of ​​the first and second chambers or in the second chamber. It is heated by the reboiler in the tower bottom. Under the action of the back-extraction solvent, the remaining aromatics and back-extraction solvent in the diesel oil evaporate upward together. After being condensed by the condenser, the extracted oil containing aromatics and back-extraction solvent is output from the extracted oil outlet in the upper part of the second chamber.

[0081] Step S104: Separate the extracted oil in the solvent recovery tower, output the back-extraction solvent from the top back-extraction solvent outlet of the solvent recovery tower, and output the aromatics from the bottom aromatics outlet.

[0082] In solvent recovery tower 8, the back-extraction solvent is separated at the top and aromatics are separated at the bottom. Specifically, in the solvent recovery tower, the extracted oil is heated by the reboiler in the bottom of the tower to evaporate the back-extraction agent to the top. After being condensed by the condenser at the top, the back-extraction solvent is discharged from the top back-extraction solvent outlet, and the remaining aromatics are discharged from the bottom aromatics outlet.

[0083] Optionally, the above method further includes the extraction solvent being discharged from the extraction solvent outlet at the bottom of the first chamber and then conveyed to the extraction solvent inlet to be added to the partition column, thereby realizing the recovery and reuse of the extraction solvent. That is, the extraction solvent 3 separated from the bottom of the partition column 6 is partially recycled and partially recovered.

[0084] Optionally, the above method further includes discharging the back-extraction solvent from the top outlet of the solvent recovery tower and feeding it into the back-extraction solvent inlet of the adjacent tower, thereby achieving the recovery and reuse of the back-extraction solvent. That is, the back-extraction solvent is separated at the top of solvent recovery tower 8, with part being recycled and part being recovered from the tower.

[0085] In the above method, the extraction solvent is an organic solvent or an ionic liquid, wherein:

[0086] The organic solvent is at least one of N,N-dimethylformamide, dimethyl sulfoxide, N,N-diethylformamide, ethylene glycol methyl ether, furfural, or morpholine.

[0087] Ionic liquids consist of cations and anions. The cations in ionic liquids are either imidazole cations or pyridine cations, and the anions are at least one of tetrafluoroborate anion, hexafluorophosphate anion, and bis(trifluoromethanesulfonate)imine anion.

[0088] Preferably, the cation is 1-methyl-3-ethylimidazolium cation (MEIM). + ), 1-heptyl-3-methylimidazolium cation (C7MIM) + ), 1,3-dimethylpyridine (MMPY) + At least one of the cations; the anion is tetrafluoroboronic acid (BF4). -1 Anions and hexafluorophosphate (PF6) - At least one of the anions.

[0089] The back-extraction solvent is at least one of C4-C10 alkanes and cycloalkanes. Preferably, the back-extraction solvent is at least one of cyclohexane, n-heptane, n-octane, and n-hexane.

[0090] In the above method, the preferred range for the theoretical plate number of the partition column is 20-150. During operation, the operating pressure is 0.05-2 MPa, the top temperature is maintained at 20-120℃, and the bottom temperature is maintained at 50-150℃. The preferred range for the theoretical plate number of the solvent recovery column is 5-40. During operation, the operating pressure is 10 kPa-0.2 MPa, the top temperature is maintained at 20-120℃, and the bottom temperature is maintained at 45-150℃. This is to effectively separate aromatics and non-aromatics from diesel fuel, and to recover the extraction solvent and back-extraction solvent.

[0091] The method described in this embodiment is a high-efficiency, short-process, low-energy-consumption, and low-investment method for producing aromatics and non-aromatics from diesel fuel. By using a partitioned column instead of a traditional distillation column, it achieves efficient separation and fractional utilization of aromatics and non-aromatics, reduces the number of distillation columns and other equipment, shortens the recovery process, and lowers energy consumption and investment. This method enables efficient, energy-saving, and flexible utilization of diesel fuel, achieving high-value utilization of diesel fractions. It can separate aromatics and non-aromatics from diesel fuel, providing high-quality raw materials for downstream high-value utilization.

[0092] Based on the same inventive concept, embodiments of the present invention also provide a method for separating aromatics from diesel fuel using the above-described separation system for aromatics in diesel fuel.

[0093] Based on the same inventive concept, this embodiment of the invention also provides an application of the above-described method for separating aromatics in diesel fuel during the process of separating aromatics in diesel fuel.

[0094] The methods and systems for separating aromatics from diesel fuel in the above embodiments have been described in part, and will not be elaborated in detail in another part.

[0095] The following is a detailed explanation using specific examples.

[0096] Diesel fractions mainly contain aromatic hydrocarbons, including monocyclic, bicyclic, and polycyclic aromatic hydrocarbons, as well as non-aromatic hydrocarbons such as alkanes and cycloalkanes. They primarily originate from atmospheric and vacuum distillation diesel, catalytic cracking diesel, hydrocracking diesel, and coking diesel, but are not limited to these sources. Typical atmospheric and vacuum distillation diesel (also known as straight-run diesel) composition is shown in Table 1, and typical catalytic cracking diesel composition is shown in Table 2.

[0097] Table 1

[0098]

[0099] Table 2

[0100]

[0101] The table above is just one example of the component content in diesel fuel. In reality, the component content of diesel fuel is highly dependent on its source, but this does not affect the applicability of the invention.

[0102] The following are examples of experiments and related experimental data on the separation of aromatics from diesel fuel using the separation system and method provided in the embodiments of the present invention.

[0103] Example 1

[0104] The raw material is diesel oil with the component contents listed in Table 1, with a feed pressure of 0.3 MPa and a feed temperature of 35°C. Divider tower 6 uses a middle partition wall design with 20 theoretical plates, operating at an operating pressure of 0.1 MPa, a top temperature of 25°C, a bottom temperature of 50°C, and a side area ratio of 4:6. Solvent recovery tower 8 has 5 theoretical plates, operating at an operating pressure of 50 kPa, a top temperature of 60°C, and a bottom temperature of 80°C. In this embodiment, the extraction solvent is an ionic liquid, wherein the cation is 1-methyl-3-ethylimidazolium (MEIM+), and the anion is tetrafluoroborate (BF4-1). The back-extraction solvent is cyclohexane; the mass ratio of back-extractant to diesel oil is 0.5, and the mass ratio of extractant to back-extractant is 0.1. The extracted oil contains more than 95% aromatic hydrocarbons; the raffinate contains more than 85% non-aromatic hydrocarbons.

[0105] Example 2

[0106] The raw material is diesel oil with the component contents listed in Table 2, with a feed pressure of 0.3 MPa and a feed temperature of 40°C. Divider tower 6 uses a middle partition wall design with 150 theoretical plates. Its operating conditions are: operating pressure 0.3 MPa, top temperature 20°C, bottom temperature 50°C, and a side area ratio of 6:4. Solvent recovery tower 8 has 20 theoretical plates and operates under the following conditions: operating pressure 20 kPa, top temperature 53°C, and bottom temperature 75°C. In this embodiment, the extraction solvent is an ionic liquid, wherein the cation is 1-heptyl-3-methylimidazolium (C7MIM+) and the anion is hexafluorophosphate (PF6-). The back-extraction solvent is n-heptane. The mass ratio of back-extractant to diesel oil is 1, and the mass ratio of extractant to back-extractant is 0.05. The extracted oil contains more than 90% aromatic hydrocarbons, and the raffinate contains more than 80% non-aromatic hydrocarbons.

[0107] Example 3

[0108] The raw material is diesel fuel with the component contents listed in Table 1, with a feed pressure of 0.4 MPa and a feed temperature of 40°C. Divider tower 6 uses a middle partition wall design with 90 theoretical plates. Its operating conditions are: operating pressure 0.2 MPa, top temperature 50°C, bottom temperature 80°C, and a side area ratio of 5:5. Solvent recovery tower 8 has 30 theoretical plates and operates under the following conditions: operating pressure 10 kPa, top temperature 50°C, and bottom temperature 70°C. In this embodiment, the extraction solvent is an ionic liquid, wherein the ionic liquid cation is 1-methyl-3-ethylimidazolium (MEIM). + The anion is tetrafluoroboronic acid ion (BF4). -1 The back-extraction solvent is n-hexane; the mass ratio of back-extraction agent to diesel oil is 0.5, and the mass ratio of extractant to back-extraction agent is 0.01. The extracted oil contains more than 85% aromatic hydrocarbons; the raffinate contains more than 75% non-aromatic hydrocarbons.

[0109] Example 4

[0110] The raw material is diesel oil with the component contents listed in Table 1, with a feed pressure of 0.3 MPa and a feed temperature of 30°C. Divider tower 6 uses a middle partition wall design with 50 theoretical plates. Its operating conditions are: operating pressure 0.05 MPa, top temperature 80°C, bottom temperature 110°C, and a side area ratio of 3:7. Solvent recovery tower 8 has 40 theoretical plates and operates under the following conditions: operating pressure 100 kPa, top temperature 20°C, and bottom temperature 45°C. In this embodiment, the extraction solvent is an ionic liquid, wherein the cation is 1,3-dimethylpyridine (MMPY+) and the anion is tetrafluoroborate (BF4-1); the back-extraction agent is cyclohexane. The mass ratio of back-extraction agent to diesel oil is 6, and the mass ratio of extractant to back-extraction agent is 2. The extracted oil contains more than 85% aromatic hydrocarbons, and the raffinate contains more than 75% non-aromatic hydrocarbons.

[0111] Example 5

[0112] The raw material is diesel fuel with the component contents listed in Table 2, with a feed pressure of 0.4 MPa and a feed temperature of 40°C. Divider tower 6 uses a middle partition wall design with 120 theoretical plates. Its operating conditions are: operating pressure 1 MPa, top temperature 100°C, bottom temperature 130°C, and a side area ratio of 7:3. Solvent recovery tower 8 has 10 theoretical plates and operates under the following conditions: operating pressure 150 kPa, top temperature 100°C, and bottom temperature 130°C. In this embodiment, the extraction solvent is an ionic liquid, wherein the ionic liquid cation is 1-heptyl-3-methylpyridine (C7MPY). + The anion is hexafluorophosphate (PF6). - The organic solvent is dimethyl sulfoxide, and the back-extraction agent is n-heptane; the mass ratio of back-extraction agent to diesel oil is 2, and the mass ratio of extractant to back-extraction agent is 0.05. The extracted oil contains more than 85% aromatic hydrocarbons by mass; the raffinate oil contains more than 80% non-aromatic hydrocarbons by mass.

[0113] Based on the experimental process described in the above embodiments, the experimental data using ionic solutions as extractants are shown in Table 3 below, including examples and comparative examples.

[0114] Table 3

[0115]

[0116]

[0117] Based on the experimental process described in the above embodiments, the experimental data using organic solvents as extractants are shown in Table 4 below, including examples and comparative examples.

[0118] Table 4

[0119]

[0120]

[0121] As can be seen from Tables 3 and 4 above, the method for separating aromatics from diesel fuel provided in this embodiment of the invention, using a partitioned tower with intermediate partitions, can effectively separate aromatics and non-aromatics, achieving an aromatics mass fraction of over 85% in the extracted oil and a non-aromatics mass fraction of over 70% in the residual oil. In contrast, the comparative examples show that without the method of this invention, the separation of aromatics and non-aromatics from diesel fuel cannot be effectively achieved.

[0122] Unless otherwise specifically stated, terms such as processing, calculation, operation, determination, display, etc., may refer to the actions and / or processes of one or more processing or computing systems or similar devices that represent the manipulation and conversion of data representing physical (e.g., electronic) quantities within the registers or memory of the processing system into other data similarly representing physical quantities within the memory, registers, or other such information storage, transmission, or display devices of the processing system. Information and signals can be represented using any of a variety of different techniques and methods. For example, data, instructions, commands, information, signals, bits, symbols, and chips mentioned throughout the above description can be represented by voltage, current, electromagnetic waves, magnetic fields or particles, light fields or particles, or any combination thereof.

[0123] It should be understood that the specific order or hierarchy of steps in the disclosed process is an example of an exemplary method. Based on design preferences, it should be understood that the specific order or hierarchy of steps in the process may be rearranged without departing from the scope of this disclosure. The appended method claims provide elements of various steps in an exemplary order and are not intended to limit the scope to the specific order or hierarchy described.

[0124] In the detailed description above, various features are combined together in a single embodiment to simplify this disclosure. This approach to disclosure should not be construed as reflecting an intention that embodiments of the claimed subject matter require more features than are explicitly stated in each claim. Rather, as reflected in the appended claims, the invention is presented with fewer features than all of the features in a single disclosed embodiment. Therefore, the appended claims are hereby explicitly incorporated into the detailed description, with each claim representing a separate preferred embodiment of the invention.

[0125] Those skilled in the art will also understand that the various illustrative logic blocks, modules, circuits, and algorithm steps described in conjunction with the embodiments herein can be implemented as electronic hardware, computer software, or a combination thereof. To clearly illustrate the interchangeability between hardware and software, the various illustrative components, blocks, modules, circuits, and steps described above are generally described in terms of their functionality. Whether such functionality is implemented as hardware or software depends on the specific application and the design constraints imposed on the overall system. Those skilled in the art can implement the described functionality in alternative ways for each specific application; however, such implementation decisions should not be construed as departing from the scope of this disclosure.

[0126] The steps of the methods or algorithms described in conjunction with the embodiments herein can be directly embodied in hardware, software modules executed by a processor, or a combination thereof. The software modules can reside in RAM memory, flash memory, ROM memory, EPROM memory, EEPROM memory, registers, hard disks, removable disks, CD-ROMs, or any other form of storage medium well known in the art. An exemplary storage medium is connected to the processor, enabling the processor to read information from and write information to the storage medium. Of course, the storage medium can also be a component of the processor. The processor and storage medium can reside in an ASIC. The ASIC can reside in a user terminal. Alternatively, the processor and storage medium can exist as discrete components in the user terminal.

[0127] For software implementation, the techniques described in this application can be implemented using modules (e.g., procedures, functions, etc.) that perform the functions described in this application. This software code can be stored in memory units and executed by a processor. The memory units can be implemented within the processor or outside the processor; in the latter case, they are communicatively coupled to the processor via various means, as is well known in the art.

[0128] The foregoing description includes examples of one or more embodiments. It is certainly impossible to describe all possible combinations of components or methods in order to describe the above embodiments, but those skilled in the art will recognize that further combinations and arrangements of the various embodiments are possible. Therefore, the embodiments described herein are intended to cover all such changes, modifications, and variations that fall within the scope of the appended claims. Furthermore, the term "comprising" as used in the specification or claims is interpreted in a manner similar to the term "including," as interpreted when used as a conjunction in the claims. Additionally, the use of any term "or" in the specification of the claims is intended to mean "non-exclusive or."

Claims

1. A method for separating aromatics from diesel fuel, characterized in that, include: Diesel fuel is added through the diesel inlet in the middle of the first chamber of the partition tower; extraction solvent is added through the extraction solvent inlet at the top of the first chamber; and back-extraction solvent is added through the back-extraction solvent inlet at the bottom of the second chamber of the partition tower. The extraction solvent is an organic solvent or an ionic liquid, wherein the organic solvent is at least one of N,N-dimethylformamide, dimethyl sulfoxide, N,N-diethylformamide, ethylene glycol methyl ether, furfural, or morpholine; the cation in the ionic liquid is one of imidazole cations and pyridine cations; and the anion in the ionic liquid is at least one of tetrafluoroborate anion, hexafluorophosphate anion, and bis(trifluoromethanesulfonate)imine anion; the back-extraction solvent is at least one of C4-C10 alkanes and cycloalkanes. The diesel fuel is in contact with the extraction solvent in the first chamber to separate raffinate containing non-aromatic hydrocarbons. The raffinate is discharged from the raffinate outlet at the top of the first chamber, and the extraction solvent is discharged from the extraction solvent outlet at the bottom of the first chamber. The raffinate outlet is higher than the extraction solvent inlet, and the back-extraction solvent inlet is higher than the extraction solvent outlet. The diesel fuel comes into contact with the back-extraction solvent via the bottom connecting area of ​​the first and second chambers, separating the extracted oil containing aromatics and the back-extraction solvent. The extracted oil is then output from the extracted oil outlet in the upper part of the second chamber to the solvent recovery tower, where the extracted oil is separated. The back-extraction solvent is output from the top outlet of the solvent recovery tower, and the aromatics are output from the bottom outlet. The theoretical plate number of the partition tower is 20-150. During use, the operating pressure is 0.05-2 MPa, the top temperature is 20-120°C, and the bottom temperature is 50-150°C.

2. The method as described in claim 1, characterized in that, The diesel fuel is contacted with an extraction solvent in the first chamber to separate raffinate containing non-aromatic hydrocarbons, which is then output from the raffinate outlet at the top of the first chamber, including: The diesel fuel is in contact with the extraction solvent in the first chamber and heated by the reboiler in the tower. Under the action of the extraction solvent, the non-aromatic hydrocarbons in the diesel fuel evaporate to the top. After being condensed by the top condenser, the raffinate containing non-aromatic hydrocarbons is output from the raffinate outlet at the top of the first chamber.

3. The method as described in claim 1, characterized in that, The diesel fuel comes into contact with the back-extraction solvent via a connection between the bottom of the first and second chambers, separating an extractable oil containing aromatics and the back-extraction solvent. This oil is then output from the extractable oil outlet in the upper part of the second chamber, comprising: The diesel fuel comes into contact with the back-extraction solvent through the bottom connecting area of ​​the first and second chambers, and is heated by the reboiler in the tower. Under the action of the back-extraction solvent, the remaining aromatics in the diesel fuel and the back-extraction solvent evaporate upward together. After being condensed by the condenser, the extracted oil containing aromatics and back-extraction solvent is output from the extracted oil outlet in the upper part of the second chamber.

4. The method as described in claim 1, characterized in that, The separation of the extracted oil in the solvent recovery tower, with the back-extraction solvent output from the top of the tower and the aromatics output from the bottom, includes: In the solvent recovery tower, the extracted oil is heated by the reboiler in the bottom of the tower to evaporate the back-extraction solvent to the top. After being condensed by the condenser at the top, the back-extraction solvent is output from the top back-extraction solvent outlet, and the remaining aromatics are output from the bottom aromatics outlet.

5. The method as described in claim 1, characterized in that, The ratio of the inner surface area of ​​the tower wall of the first cavity and the second cavity is 3:7 to 7:

3.

6. The method as described in claim 1, characterized in that, Also includes: After the extraction solvent is output from the extraction solvent outlet at the bottom of the first chamber, it is conveyed to the extraction solvent inlet and added to the partition tower; and / or The back-extraction solvent output from the top of the solvent recovery tower is fed into the partition tower via the back-extraction solvent inlet.

7. The method as described in claim 1, characterized in that, The mass ratio of the back-extraction solvent to diesel oil is 0.5-6, and the mass ratio of the extraction solvent to the back-extraction solvent is 0.01-2.

8. The method as described in claim 1, characterized in that, The cation is 1-methyl-3-ethylimidazolium cation MEIM. + 1-Heptyl-3-methylimidazolium cationic C7MIM + 1,3-Dimethylpyridine MMPY + One of the cations; the anion is tetrafluoroborate (BF4). -1 Anion and hexafluorophosphate PF6 - At least one of the anions.

9. The method as described in claim 1, characterized in that, The back-extraction solvent is at least one selected from cyclohexane, n-heptane, n-octane, and n-hexane.

10. The method according to any one of claims 1-9, characterized in that, The solvent recovery tower has a theoretical plate number of 5-40. During use, the operating pressure is 10 kPa-0.2 MPa, the top temperature is 20-120°C, and the bottom temperature is 45-150°C.

11. The method according to any one of claims 1-9, characterized in that, The separation system for aromatics in the diesel fuel used includes: a partition wall tower and a solvent recovery tower; The partition tower is internally divided into a first chamber and a second chamber, which are connected at the bottom by a partition wall. The bottom of the tower has an extraction solvent outlet. The first chamber has a diesel inlet in the middle and an extraction solvent inlet and a raffinate outlet at the top. The upper half of the second chamber has an extractable oil outlet and a back-extraction solvent inlet at the bottom. The partition tower is used to allow diesel entering through the diesel inlet to contact with the extraction solvent entering through the extraction solvent inlet in the first chamber, separating raffinate containing non-aromatics, which is output from the raffinate oil outlet. Diesel is then allowed to contact with back-extraction solvent entering through the back-extraction solvent inlet via the bottom connecting area of ​​the first and second chambers, separating raffinate containing aromatics and back-extraction solvent, which is output from the raffinate oil outlet. The extraction solvent is output from the extraction solvent outlet. The raffinate oil outlet is higher than the extraction solvent inlet, and the back-extraction solvent inlet is higher than the extraction solvent outlet. The partition tower has a theoretical plate number of 20-150. During operation, the operating pressure is 0.05-2 MPa, the top temperature is 20-120°C, and the bottom temperature is 50-150°C. The solvent recovery tower has an oil extraction inlet in the middle, an aromatics outlet at the bottom, and a back-extraction solvent outlet at the top. The oil extraction inlet is connected to the oil extraction outlet of the partition tower. The solvent recovery tower is used to separate aromatics from the oil extracted from the partition tower and output them from the aromatics outlet, and to separate the back-extraction solvent from the oil extracted from the partition tower and output them from the back-extraction solvent outlet.

12. The method as described in claim 11, characterized in that, The partition wall of the partition tower is an intermediate partition wall; The adjacent tower is equipped with at least one reboiler and / or at least one condenser.

13. The method as described in claim 11, characterized in that, The solvent recovery tower is equipped with at least one reboiler and / or at least one condenser.

14. The method as described in claim 11, characterized in that, The ratio of the inner surface area of ​​the tower wall of the first cavity and the second cavity is 4:6 to 6:

4.

15. The method as described in claim 11, characterized in that, The theoretical number of plates in the adjacent tower is 20-150. During use, the operating pressure is 0.1-2 MPa, the top temperature is 25-120℃, and the bottom temperature is 50-150℃.

16. The method as described in claim 11, characterized in that, The solvent recovery tower has a theoretical plate number of 10-40. During use, the operating pressure is 20 kPa-0.2 MPa, the top temperature is 20-120°C, and the bottom temperature is 45-150°C.

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