阅读说明：本技术 一种用离子液体的催化柴油稠环芳烃多级逆流-错流组合抽提装置及方法 (Multi-stage countercurrent-cross-flow combined extraction device and method for catalyzing diesel polycyclic aromatic hydrocarbon by using ionic liquid ) 是由 雷志刚 李国选 刘清华 于 2021-09-26 设计创作，主要内容包括：一种用离子液体的催化柴油稠环芳烃多级逆流-错流组合抽提装置及方法,属于化工分离纯化技术领域。通过萃取剂多级逆流-错流组合抽提技术,包括待分离催化柴油芳烃从塔的中下部进入混合萃取塔(C1),萃取剂(A1)从塔顶进入混合萃取塔(C1),混合萃取塔(C1)顶部连接在混合萃取塔(C2)的底部,萃取剂(A2)从塔顶进入混合萃取塔(C2),混合萃取塔(C2)塔顶采出液进入萃取液闪蒸罐(S1)中部进行闪蒸分离,来自混合萃取塔(C1)和混合萃取塔(C2)塔底的采出物流连接到连接萃余液闪蒸罐(S2)中部进行闪蒸分离,萃取液闪蒸罐(S1)和萃余液闪蒸罐(S2)底部抽提溶剂出口连接在混合萃取塔(C1)和(C2)萃取剂进料口的萃取剂循环物流上。克服了溶剂与原料混溶的问题,提高油品产品的收率,分离后油品产品纯度高。(A multi-stage counter-current-cross-current combined extraction device and method for catalyzing diesel polycyclic aromatic hydrocarbons by using ionic liquid belong to the technical field of chemical separation and purification. The extraction technology comprises the steps that catalytic diesel aromatic hydrocarbon to be separated enters a mixed extraction tower (C1) from the middle lower part of the tower, an extracting agent (A1) enters the mixed extraction tower (C1) from the top of the tower, the top of the mixed extraction tower (C1) is connected to the bottom of the mixed extraction tower (C2), an extracting agent (A2) enters the mixed extraction tower (C2) from the top of the tower, a produced liquid at the top of the mixed extraction tower (C2) enters the middle of an extract flash tank (S1) for flash separation, produced liquid from the bottoms of the mixed extraction tower (C1) and the mixed extraction tower (C2) is connected to the middle of a raffinate flash tank (S2) for flash separation, and an extraction solvent outlet at the bottoms of the extract flash tank (S1) and a raffinate flash tank (S2) is connected to an extracting agent circulating stream at the feeding ports of the mixed extraction tower (C1) and the extracting agent (C2). The problem of mixing and dissolving of the solvent and the raw materials is solved, the yield of the oil product is improved, and the purity of the separated oil product is high.)

1. A multi-stage countercurrent-cross-flow combined extraction device for catalyzing diesel oil aromatic hydrocarbon by using ionic liquid is characterized by mainly comprising the following parts:

a first mixed extraction tower (C1), a second mixed extraction tower (C2), a raffinate flash tank (S1) and an extract flash tank (S2);

the method comprises the following steps that (1) catalytic cracking diesel oil aromatic hydrocarbon to be separated enters a first mixed extraction tower (C1) from the middle lower part of the tower, a first ionic liquid extractant (A1) enters the first mixed extraction tower (C1) from an extractant feed inlet at the top of the tower, the effluent at the top of the first mixed extraction tower (C1) is connected with the bottom of a second mixed extraction tower (C2), and a second ionic liquid extractant (A2) enters the second mixed extraction tower (C2) from the extractant feed inlet at the top of the tower;

the material flowing out of the top of the second mixed extraction tower (C2) is connected with the middle part of a raffinate flash tank (S1) for flash separation;

the extraction liquid flows from the bottoms of the first mixed extraction tower (C1) and the second mixed extraction tower (C2) are connected to the middle part of an extraction liquid flash tank (S2) for flash separation;

an extractant outlet at the bottom of the raffinate flash tank (S1) and the extract flash tank (S2) is connected to an extractant feed inlet of the first mixed extraction tower (C1) for extractant circulation; non-aromatic components (alkanes, alkenes, etc.) flow out of the top of the raffinate flash tank (S1), and aromatic components (including polycyclic aromatic hydrocarbons) flow out of the top of the extract flash tank (S2).

2. The multistage countercurrent-cross-flow combined extraction device for catalyzing diesel aromatics by using ionic liquid as claimed in claim 1, wherein a part of reflux pipelines are further arranged on the aromatic hydrocarbon components (including polycyclic aromatic hydrocarbons) flowing out of the top of the extract flash tank (S2) according to requirements and connected with the middle lower part of the first mixed extraction tower (C1) for carrying out partial reflux to form the multistage countercurrent-cross-flow-reflux combined extraction device.

3. The method for separating and catalyzing diesel fused ring aromatic hydrocarbon by solvent multistage countercurrent-cross flow combined extraction based on ionic liquid by adopting the device of claim 1 or 2 is characterized by mainly comprising the following steps:

(1) a first ionic liquid extractant enters a first mixed extraction tower (C1) from the top of the tower, catalytic diesel aromatic hydrocarbon to be separated enters the first mixed extraction tower (C1) from the middle lower part of the first mixed extraction tower (C1), high-efficiency separation is carried out, produced liquid at the top of the first mixed extraction tower (C1) enters the bottom of a second mixed extraction tower (C2), and produced liquid rich in ionic liquid at the bottom of the first mixed extraction tower (C1) enters the middle part of an extract liquid flash tank (S2);

(2) a second ionic liquid extractant enters a second mixed extraction tower (C2) from the top of the second mixed extraction tower (C2), a produced liquid at the bottom of the second mixed extraction tower (C2) enters the middle part of an extract flash tank (S2), and is efficiently separated by the extract flash tank (S2), aromatic hydrocarbons (including polycyclic aromatic hydrocarbons) are obtained at the top of the extract flash tank (S2), and the ionic liquid extractant is obtained at the bottom of the extract flash tank (S2);

(3) connecting the extract at the top of the second mixed extraction tower (C2) to the middle part of a raffinate flash tank (S1) for flash separation, efficiently separating through the raffinate flash tank (S1), obtaining non-aromatic hydrocarbons (alkane, olefin and the like) at the top of the raffinate flash tank (S1), and obtaining an ionic liquid extractant at the bottom of the raffinate flash tank (S1);

(4) ionic liquid extractant stream outlets obtained at the bottoms of the raffinate flash tank (S1) and the extract flash tank (S2) are mixed into a whole and then are respectively connected with top extractant feed inlets of a first mixed extraction tower (C1) and a second mixed extraction tower (C2) to recycle the ionic liquid extractant;

if the aromatic hydrocarbon components (including the polycyclic aromatic hydrocarbon) flowing out of the top of the extraction liquid flash tank (S2) partially reflux, the mass ratio of the refluxing aromatic hydrocarbon (including the polycyclic aromatic hydrocarbon) to the system produced aromatic hydrocarbon is 0.1-9.

4. The process according to claim 3, wherein the first mixed extraction column (C1) is operated at a pressure of 1 to 5atm, a theoretical plate number (N) of 3 to 15, preferably 5 to 10, and an operating temperature of 20 to 100 ℃, and the feed position of the catalytic diesel aromatic hydrocarbon in the first mixed extraction column (C1) is (N-1) th to N-th, the feed position of the extractant is 1 to 2 nd, and N is the last feed plate.

5. The method according to claim 3, characterized in that the second mixed extraction column (C2) is operated at a pressure of 1 to 5atm, a theoretical plate number (N) of 3 to 15, preferably 5 to 10, and an operating temperature of 20 to 100 ℃, the liquid produced at the top of the first mixed extraction column (C1) enters the second mixed extraction column (C2) at the bottom, the feeding positions are (N-1) to N, the feeding positions of the extractant are 1 to 2, and N is the last feeding plate.

6. The process according to claim 3, wherein the raffinate flash tank (S1) and the extract flash tank (S2) are operated at an operating pressure of 0.1 to 0.5atm and an operating temperature of 50 to 150 ℃.

7. A process according to claim 3, wherein the first ionic liquid extractant and the second ionic liquid extractant are the same and are each a single ionic liquid, a mixed ionic liquid or a mixture of an ionic liquid and a conventional organic solvent.

8. The process as claimed in claim 3, characterized in that the volume ratio of ionic liquid of each mixing column of the first mixing column (C1) and the second mixing column (C2) to diesel aromatics to be separated is from 0.5 to 3: 1.

9. The method as claimed in claim 3, wherein when the mass ratio of n-hexadecane to 1-methylnaphthalene in the diesel aromatic hydrocarbon is (7-9) to (1-3), the recovery rate of n-hexadecane after separation is 98.50-99.99%, and the recovery rate of 1-methylnaphthalene is 96-99.9%.

Technical Field

The invention relates to a multistage countercurrent-cross flow combined extraction device and method for catalyzing diesel polycyclic aromatic hydrocarbon by using ionic liquid. The ionic liquid extractant can be single ionic liquid, mixed ionic liquid, a mixture of the ionic liquid and a traditional organic solvent or functional ionic liquid; belongs to the technical field of chemical separation and purification.

Background

Under the great trend of developing low-carbon circular economy and realizing sustainable development of the environment, the upgrading pace of the diesel oil quality is obviously accelerated, and especially the limits on the cetane number and the polycyclic aromatic hydrocarbon index are more and more strict. The crude oil in China is mostly heavy and lacks for producing light raw materials of aromatic hydrocarbon and olefin. Catalytic cracking is an important means for heavy oil conversion, has the advantages of strong raw material adaptability, high conversion rate, low cost and the like, and occupies a great position in the petroleum refining process. The process is characterized in that the paraffin and the cyclane in the feed are cracked, and the aromatic hydrocarbon has no damage capability basically. Therefore, catalytic diesel is usually enriched with a large amount of polycyclic aromatic hydrocarbons, and this disadvantage is more prominent when the residual oil content in the raw material is large. At present, the technology of FCC diesel oil hydro-upgrading in China is rapidly developed under the limitation of environmental protection requirements and the promotion of market demands, but the hydro-upgrading process has high operation cost and harsh operation conditions, so that the production cost of diesel oil is greatly increased. The solvent extraction technology can effectively separate non-aromatic hydrocarbon and aromatic hydrocarbon, and the process can be applied to various material flows in an oil refinery: gasoline, kerosene, diesel and heavy distillates. At present, various solvents are applied to an industrial device for extracting aromatic hydrocarbon worldwide, and triethylene glycol, tetraethylene glycol, sulfolane, dimethyl sulfoxide, N-methylpyrrolidone, N-formylmorpholine and the like are common (common extraction solvents are shown in Table 1). However, these solvents are not suitable for catalytic diesel aromatics extraction because their boiling point is within the distillation range of catalytic diesel (180-; on the other hand, although the boiling point of the solvent such as furfural and N, N-Dimethylformamide (DMF) used for the extraction of lubricating oil is not within the distillation range of catalytic diesel oil, the solvent cannot be recovered by a conventional distillation method because it forms an azeotrope with many components in catalytic diesel oil. The ionic liquid is used as a novel separating agent for catalyzing the extraction of the diesel polycyclic aromatic hydrocarbon instead of a conventional solvent which is difficult to recycle, a novel functional ionic liquid polycyclic aromatic hydrocarbon extraction technology is creatively provided, the application range of the ionic liquid in chemical separation is widened, and the extraction process of the polycyclic aromatic hydrocarbon is strengthened. Therefore, how to economically and efficiently treat and catalyze poor diesel oil, improve the cetane number and reduce the content of polycyclic aromatic hydrocarbon becomes an important technical challenge facing the construction of catalytic device enterprises.

Chinese patent CN102021024A discloses a system and method for preparing high quality diesel oil, the system includes an extraction device, a part of aromatic hydrocarbons in diesel oil are removed by solvent extraction, high quality diesel oil is obtained by hydrogenation treatment of raffinate oil, and the extracted aromatic hydrocarbons are discharged from the system. The raw materials processed by the method are diversified, can be various diesel oil, and the aromatic hydrocarbon is separated from the diesel oil, so that the cetane number of the diesel oil is greatly improved, and the condensation point of the diesel oil is reduced.

Chinese patent CN102443436A discloses a combined method of hydrotreatment, catalytic cracking and diesel oil aromatic extraction of residual oil. In the method, residual oil is hydrotreated in the presence of hydrogen and a hydrogenation catalyst, effluent is separated to obtain a gas-phase product and a liquid-phase product, the liquid-phase product directly enters a catalytic cracking device for reaction without fractionation, reaction effluent is separated to obtain dry gas, liquefied gas, catalytic cracking gasoline, catalytic cracking diesel and heavy distillate oil, the catalytic diesel is extracted by aromatic hydrocarbon, extract oil and catalytic cracking heavy distillate oil are recycled to the hydrotreating device after being filtered, and raffinate oil is discharged from the device to obtain the diesel with high cetane number. In the method, the hydrocracking reaction effluent directly enters the catalytic cracking device without fractionation, so that the load of the catalytic cracking device is increased undoubtedly, and the processing capacity of the device is influenced; secondly, the effluent of the hydrocracking reaction contains a certain amount of light components, and the light components enter a catalytic cracking device and then undergo secondary reaction, so that light distillate oil is reduced, the gas yield is increased, and certain economic loss is caused.

TABLE 1 Main physical Properties of conventional extractants

The invention realizes the high-efficiency separation of the catalytic diesel oil polycyclic aromatic hydrocarbon mixture by an extractant multi-stage countercurrent-cross flow combined extraction method and an extractant based on the ionic liquid, reduces the energy consumption of the device and simultaneously reduces the equipment cost.

Disclosure of Invention

The invention aims to provide a multistage countercurrent-cross-flow combined extraction device and method for catalyzing diesel polycyclic aromatic hydrocarbon by using ionic liquid. The solvent ratio can be reduced, the problem of mixing and dissolving of the solvent and the mixture to be separated is solved, the separation efficiency of the aromatic hydrocarbon in the diesel oil can be improved, and the quality of the diesel oil product with cetane number can be improved.

The invention is realized by the following technical scheme.

A multi-stage countercurrent-cross-flow combined extraction device for catalyzing diesel oil aromatic hydrocarbon by using ionic liquid is characterized by mainly comprising the following parts:

a first mixed extraction tower (C1), a second mixed extraction tower (C2), a raffinate flash tank (S1) and an extract flash tank (S2);

the method comprises the following steps that (1) catalytic cracking diesel oil aromatic hydrocarbon to be separated enters a first mixed extraction tower (C1) from the middle lower part of the tower, a first ionic liquid extractant (A1) enters the first mixed extraction tower (C1) from an extractant feed inlet at the top of the tower, the effluent at the top of the first mixed extraction tower (C1) is connected with the bottom of a second mixed extraction tower (C2), and a second ionic liquid extractant (A2) enters the second mixed extraction tower (C2) from the extractant feed inlet at the top of the tower;

the material flowing out of the top of the second mixed extraction tower (C2) is connected with the middle part of a raffinate flash tank (S1) for flash separation;

the extraction liquid flows from the bottoms of the first mixed extraction tower (C1) and the second mixed extraction tower (C2) are connected to the middle part of an extraction liquid flash tank (S2) for flash separation;

an extractant outlet at the bottom of the raffinate flash tank (S1) and the extract flash tank (S2) is connected to an extractant feed inlet of the first mixed extraction tower (C1) for extractant circulation; non-aromatic components (alkanes, alkenes, etc.) flow out of the top of the raffinate flash tank (S1), and aromatic components (including polycyclic aromatic hydrocarbons) flow out of the top of the extract flash tank (S2).

And further, as required, aromatic hydrocarbon components (including polycyclic aromatic hydrocarbon) flowing out of the top of the extract liquid flash tank (S2) are also provided with a part of reflux pipelines which are connected with the middle lower part of the first mixed extraction tower (C1) for carrying out partial reflux to form a multistage countercurrent-cross flow-reflux combined extraction device.

The method for separating and catalyzing diesel oil condensed ring aromatic hydrocarbon by adopting the device to carry out solvent multistage countercurrent-cross flow combined extraction based on ionic liquid mainly comprises the following steps:

(1) a first ionic liquid extractant enters a first mixed extraction tower (C1) from the top of the tower, catalytic diesel aromatic hydrocarbon to be separated enters the first mixed extraction tower (C1) from the middle lower part of the first mixed extraction tower (C1), high-efficiency separation is carried out, produced liquid at the top of the first mixed extraction tower (C1) enters the bottom of a second mixed extraction tower (C2), and produced liquid rich in ionic liquid at the bottom of the first mixed extraction tower (C1) enters the middle part of an extract liquid flash tank (S2);

(2) a second ionic liquid extractant enters a second mixed extraction tower (C2) from the top of the second mixed extraction tower (C2), a produced liquid at the bottom of the second mixed extraction tower (C2) enters the middle part of an extract flash tank (S2), and is efficiently separated by the extract flash tank (S2), aromatic hydrocarbons (including polycyclic aromatic hydrocarbons) are obtained at the top of the extract flash tank (S2), and the ionic liquid extractant is obtained at the bottom of the extract flash tank (S2);

(3) connecting the extract at the top of the second mixed extraction tower (C2) to the middle part of a raffinate flash tank (S1) for flash separation, efficiently separating through the raffinate flash tank (S1), obtaining non-aromatic hydrocarbons (alkane, olefin and the like) at the top of the raffinate flash tank (S1), and obtaining an ionic liquid extractant at the bottom of the raffinate flash tank (S1);

(4) the ionic liquid extractant stream outlets obtained at the bottoms of the raffinate flash tank (S1) and the extract flash tank (S2) are mixed into a whole and then are respectively connected with the top extractant feed inlets of the first mixed extraction tower (C1) and the second mixed extraction tower (C2) for recycling the ionic liquid extractant.

If the aromatic hydrocarbon components (including the polycyclic aromatic hydrocarbon) flowing out of the top of the extraction liquid flash tank (S2) partially reflux, the mass ratio of the refluxing aromatic hydrocarbon (including the polycyclic aromatic hydrocarbon) to the system produced aromatic hydrocarbon is 0.1-9.

According to another preferred embodiment of the invention, the operation pressure of the first mixed extraction tower (C1) is 1-5 atm, the theoretical plate number (N) is 3-15 blocks, preferably 5-10 blocks, the operation temperature is 20-100 ℃, the feeding position of the catalytic diesel aromatic hydrocarbon in the first mixed extraction tower (C1) is (N-1) -N blocks, the feeding position of the extracting agent is 1-2 blocks, and N is the last feeding plate;

the operating pressure of the second mixed extraction tower (C2) is 1-5 atm, the theoretical plate number (N) is 3-15 blocks, preferably 5-10 blocks, the operating temperature is 20-100 ℃, the produced liquid at the top of the first mixed extraction tower (C1) enters the second mixed extraction tower (C2) at the bottom of the tower, the feeding positions are (N-1) -N blocks, the feeding position of the extracting agent is 1-2 blocks, and N is the last feeding plate.

According to another preferred embodiment of the present invention, it is characterized in that the operating pressure of the raffinate flash tank (S1) and the extract flash tank (S2) is 0.1 to 0.5atm, and the operating temperature is 50 to 150 ℃.

According to another preferred embodiment of the invention, it is characterized in that said catalytic aromatic hydrocarbon mixture can be mixed in any ratio.

According to another preferred embodiment of the present invention, it is characterized in that the first ionic liquid extractant and the second ionic liquid extractant are the same and are each a single ionic liquid, a mixed ionic liquid or a mixture of an ionic liquid and a conventional organic solvent.

According to another preferred embodiment of the invention, the volume ratio of the ionic liquid of each mixing tower of the first mixing extraction tower (C1) and the second mixing extraction tower (C2) to the diesel aromatic hydrocarbon to be separated is 0.5-3: 1.

According to another preferred embodiment of the invention, when the mass ratio of the n-hexadecane to the 1-methylnaphthalene in the diesel aromatic hydrocarbon is (7-9) to (1-3), the recovery rate of the separated n-hexadecane is 98.50-99.99%, and the recovery rate of the 1-methylnaphthalene is 96-99.9%.

Compared with the prior art, the invention mainly has the following beneficial effects:

(1) the method has simple process and convenient operation, successfully separates the catalytic diesel oil aromatic hydrocarbon mixture, improves the cetane number of the diesel oil product, and reduces the polycyclic aromatic hydrocarbon content in the oil product.

(2) The method adopts the extracting agent based on the ionic liquid, strengthens the separation effect of the extraction process, has simple extracting agent recovery process, reduces the energy consumption of the process and further reduces the process cost.

Drawings

FIG. 1 is a flow chart of a process unit for catalyzing multistage countercurrent-cross-flow combined extraction of diesel polycyclic aromatic hydrocarbons by using ionic liquid.

FIG. 2 is a flow chart of a process unit for multi-stage countercurrent-cross-flow-reflux combined extraction.

In the figure, C1-mixed extraction column; c2-mixed extraction tower; s1-raffinate flash tank; s2-extract liquid flash tank; f-catalytic cracking diesel aromatic hydrocarbon to be separated; a1-a second ionic liquid extractant, A2-a second ionic liquid extractant, L1-a produced liquid at the top of a first mixed extraction tower, L2-a produced liquid at the top of a second mixed extraction tower, R1-a produced liquid at the bottom of the top of the first mixed extraction tower, R2-a produced liquid at the bottom of the second mixed extraction tower, an R3-return pipe, IL 1-an ionic liquid extractant obtained at the bottom of a raffinate flash tank, and IL 2-an ionic liquid extractant obtained at the bottom of an extract flash tank.

Detailed Description

The present invention will be further described with reference to examples, but the present invention is not limited to the following examples, and various examples are included in the technical scope of the present invention without departing from the spirit of the invention described above.

In the following examples, the mixed extraction column (C1) and the mixed extraction column (C2) were operated under normal temperature and pressure. The raffinate flash drum (S1) and extract flash drum (S2) were operated at 0.5atm and 100 deg.C.

Example 1:

common ionic liquid (specifically BMIM) (BF 4) is adopted as an extracting agent.

The feed flow is 100kg/h, and the feed contains 70 percent of n-hexadecane (mass fraction) and 30 percent of 1-methylnaphthalene (mass fraction). The theoretical plate number of the mixed extraction tower (C1) is 6, the feeding position of the diesel-aromatic hydrocarbon mixture is 6, the feeding position of the single ionic liquid is 1, the produced liquid at the top of the mixed extraction tower (C1) enters the mixed extraction tower (C2) from the bottom of the tower, the single ionic liquid enters the mixed extraction tower (C2) from the top of the tower, the produced stream at the top of the mixed extraction tower (C2) is connected to the middle part of a raffinate flash tank (S1) for flash separation, the produced liquid from the bottoms of the mixed extraction tower (C1) and the mixed extraction tower (C2) enters the middle part of an extract flash tank (S2) for flash separation, the volume ratio of the single ionic liquid to the fed matter to be separated of the diesel-aromatic hydrocarbon in each stage of extraction process is 1:1, the recovery rate of the n-hexadecane is 99.60% after multi-stage separation, and the recovery rate of the 1-methylnaphthalene is 99.00%. The purity of n-hexadecane in the extract was 99.83% (mass fraction), and the purity of 1-methylnaphthalene in the raffinate was 98.69% (mass fraction).

Example 2:

mixed ionic liquid (specifically [ BMIM ] [ BF4] and [ EMIM ] [ BF4] in a volume ratio of 1:1) is adopted as an extracting agent.

The feed flow is 100kg/h, and the feed contains 80 percent (mass fraction) of n-hexadecane and 20 percent (mass fraction) of 1-methylnaphthalene. The theoretical plate number of a countercurrent mixed extraction tower (C1) is 5, the feeding position of a diesel-aromatic hydrocarbon mixture is 5, the feeding position of mixed ionic liquid is 2, produced liquid at the top of the mixed extraction tower (C1) enters the mixed extraction tower (C2) from the bottom of the tower, the mixed ionic liquid enters the mixed extraction tower (C2) from the top of the tower, extracted material flow at the top of the mixed extraction tower (C2) is connected to the middle part of a raffinate flash tank (S1) for flash separation, produced liquid from the bottoms of the mixed extraction tower (C1) and the mixed extraction tower (C2) enters the middle part of an extract flash tank (S2) for flash separation, the volume ratio of the mixed ionic liquid to the fed diesel-aromatic hydrocarbon to-be-separated material in each stage of extraction is 1:1, the recovery rate of n-hexadecane is 99.47% after multi-stage separation, and the recovery rate of 1-methylnaphthalene is 98.59%. The purity of n-hexadecane in the extract was 99.67% (mass fraction), and the purity of 1-methylnaphthalene in the raffinate was 98.38% (mass fraction).

Example 3:

a mixed solution of common ionic liquid (specifically [ BMIM ] [ BF4]) + organic solvent (specifically sulfolane) (the volume ratio of the ionic liquid to the organic solvent is 3:7) is adopted as an extracting agent.

The feed flow rate was 100kg/h, and the feed contained 75 mass% of n-hexadecane and 25 mass% of 1-methylnaphthalene. The theoretical plate number of a countercurrent mixed extraction tower (C1) is 6, the feeding position of a diesel-aromatic hydrocarbon mixture is 6, the feeding position of a mixed extracting agent is 1, a produced liquid at the top of the mixed extraction tower (C1) enters the mixed extraction tower (C2) from the bottom of the tower, the mixed extracting agent enters the mixed extraction tower (C2) from the top of the tower, an extracted material flow at the top of the mixed extraction tower (C2) is connected to the middle part of a raffinate flash tank (S1) for flash separation, produced liquids from the bottoms of the mixed extraction tower (C1) and the mixed extraction tower (C2) enter an extract flash tank (S2) for flash separation, the volume ratio of the mixed extracting agent to the fed diesel-aromatic hydrocarbon to-be-separated in each stage of extraction is 1.5:1, the recovery rate of n-hexadecane is 99.82% and the recovery rate of 1-methylnaphthalene is 99.21% after multi-stage separation. The purity of n-hexadecane in the extract was 99.87% (mass fraction), and the purity of 1-methylnaphthalene in the raffinate was 98.79% (mass fraction).

Example 4:

hydroxyl functionalized ionic liquid (particularly HOCMIM ] [ PF 6) is adopted as an extracting agent.

The feed flow is 100kg/h, and the feed contains 70 percent of n-hexadecane (mass fraction) and 30 percent of 1-methylnaphthalene (mass fraction). The theoretical plate number of the mixed extraction tower (C1) is 6, the feeding position of a diesel-aromatic hydrocarbon mixture is 6, the feeding position of hydroxyl functionalized ionic liquid is 1, the produced liquid at the top of the mixed extraction tower (C1) enters the mixed extraction tower (C2) from the bottom of the tower, the hydroxyl functionalized ionic liquid enters the mixed extraction tower (C2) from the top of the tower, the produced liquid at the top of the mixed extraction tower (C2) is connected to the middle part of a raffinate flash tank (S1) for flash separation, the produced liquid at the bottom of the mixed extraction tower (C1) and the mixed extraction tower (C2) enters the middle part of the flash tank (S2) for flash separation, the volume ratio of the hydroxyl functionalized ionic liquid to the feed of the diesel-aromatic hydrocarbon to-be-separated in the extraction process of each stage is 1:1, the recovery rate of n-hexadecane is 99.90%, and the recovery rate of 1-methylnaphthalene is 99.60% after multi-stage separation. The purity of n-hexadecane in the extract was 99.85% (mass fraction), and the purity of 1-methylnaphthalene in the raffinate was 99.7% (mass fraction).

Example 5:

amino functionalized ionic liquid (specifically [ HNC2MIM ] [ PF6]) is used as an extracting agent.

The feed flow is 100kg/h, and the feed contains 70 percent of n-hexadecane (mass fraction) and 30 percent of 1-methylnaphthalene (mass fraction). The theoretical plate number of the mixed extraction tower (C1) is 6, the feeding position of a diesel-aromatic hydrocarbon mixture is 6, the feeding position of amino functionalized ionic liquid is 1, the produced liquid at the top of the mixed extraction tower (C1) enters the mixed extraction tower (C2) from the bottom of the tower, the amino functionalized ionic liquid enters the mixed extraction tower (C2) from the top of the tower, the produced liquid at the top of the mixed extraction tower (C2) is connected to the middle part of a raffinate flash tank (S1) for flash separation, the produced liquid at the bottom of the mixed extraction tower (C1) and the mixed extraction tower (C2) enters the middle part of the flash tank (S2) for flash separation, the volume ratio of the amino functionalized ionic liquid to the feed of the diesel-aromatic hydrocarbon to-be-separated in the extraction process of each stage is 1:1, the recovery rate of n-hexadecane is 99.90% and the recovery rate of 1-methylnaphthalene is 99.55% after multi-stage separation. The purity of n-hexadecane in the extract was 99.86% (mass fraction), and the purity of 1-methylnaphthalene in the raffinate was 99.65% (mass fraction).

Example 6:

aryl functionalized ionic liquid (particularly BuPhIm BF 4) is adopted as an extracting agent.

The feed flow is 100kg/h, and the feed contains 70 percent of n-hexadecane (mass fraction) and 30 percent of 1-methylnaphthalene (mass fraction). The theoretical plate number of the mixed extraction tower (C1) is 6, the feeding position of a diesel oil aromatic hydrocarbon mixture is 6, the feeding position of the choline group functionalized ionic liquid is 1, the produced liquid at the top of the mixed extraction tower (C1) enters the mixed extraction tower (C2) from the bottom of the tower, the choline group functionalized ionic liquid enters the mixed extraction tower (C2) from the top of the tower, the produced stream at the top of the mixed extraction tower (C2) is connected to the middle part of a raffinate flash tank (S1) for flash separation, the produced liquid at the bottoms of the mixed extraction tower (C1) and the mixed extraction tower (C2) enters the middle part of an extract flash tank (S2) for flash separation, the volume ratio of the choline group functionalized ionic liquid to the diesel oil aromatic hydrocarbon to-be-separated material in the extraction process of each stage is 1:1, the recovery rate of n-hexadecane is 99.9%, and the recovery rate of 1-methylnaphthalene is 99.55%. The purity of n-hexadecane in the extract was 99.86% (mass fraction), and the purity of 1-methylnaphthalene in the raffinate was 99.6% (mass fraction).

Example 7:

common ionic liquid (specifically BMIM) (BF 4) is used as an extracting agent with reflux.

The feed flow is 100kg/h, and the feed contains 70 percent of n-hexadecane (mass fraction) and 30 percent of 1-methylnaphthalene (mass fraction). The theoretical plate number of the mixed extraction tower (C1) is 6, the feeding position of a diesel-aromatic hydrocarbon mixture is 3, the feeding position of single ionic liquid is 1, the produced liquid at the top of the mixed extraction tower (C1) enters the mixed extraction tower (C2) from the bottom of the tower, the single ionic liquid enters the mixed extraction tower (C2) from the top of the tower, the produced stream at the top of the mixed extraction tower (C2) is connected to the middle part of a raffinate flash tank (S1) for flash separation, the produced liquid from the bottom of the mixed extraction tower (C1) and the mixed extraction tower (C2) enters the middle part of an extract flash tank (S2) for flash separation, the volume ratio of the single ionic liquid to the feed of diesel-aromatic hydrocarbon to be separated in each stage of extraction process is 1:1, the mass ratio of return aromatic hydrocarbon (including fused ring aromatic hydrocarbon) to the produced system aromatic hydrocarbon in the produced liquid at the top of the extract flash tank (S2) is 0.45, and the reflux position is 5, the recovery rate of the n-hexadecane after multi-stage separation is 99.72%, and the recovery rate of the 1-methylnaphthalene is 99.21%. The purity of n-hexadecane in the extract was 99.83% (mass fraction), and the purity of 1-methylnaphthalene in the raffinate was 98.70% (mass fraction).

Example 8:

mixed ionic liquid (specifically [ BMIM ] [ BF4] and [ EMIM ] [ BF4] in a volume ratio of 1:1) is adopted as an extracting agent, and reflux is carried out.

The feed flow is 100kg/h, and the feed contains 80 percent (mass fraction) of n-hexadecane and 20 percent (mass fraction) of 1-methylnaphthalene. The theoretical plate number of a countercurrent mixed extraction tower (C1) is 5, the feeding position of a diesel-aromatic hydrocarbon mixture is 3, the feeding position of mixed ionic liquid is 2, produced liquid at the top of the mixed extraction tower (C1) enters a mixed extraction tower (C2) from the bottom of the tower, the mixed ionic liquid enters the mixed extraction tower (C2) from the top of the tower, extracted material flow at the top of the mixed extraction tower (C2) is connected to the middle part of a raffinate flash tank (S1) for flash separation, produced liquid from the bottoms of the mixed extraction tower (C1) and the mixed extraction tower (C2) enters an extract flash tank (S2) for flash separation, the volume ratio of the ionic liquid to the diesel-aromatic hydrocarbon to-be-separated material in each stage of extraction process is 1:1, the mass ratio of return aromatic hydrocarbon (including fused ring aromatic hydrocarbon) to produced system aromatic hydrocarbon in the produced liquid at the top of the extract flash tank (S2) is 0.25, and the reflux position is 4, the recovery rate of the n-hexadecane after multi-stage separation is 99.8 percent, and the recovery rate of the 1-methylnaphthalene is 99.0 percent. The purity of n-hexadecane in the extract was 99.85% (mass fraction), and the purity of 1-methylnaphthalene in the raffinate was 98.70% (mass fraction).

Example 9:

a mixed solution of common ionic liquid (specifically [ BMIM ] [ BF4]) + organic solvent (specifically sulfolane) (the volume ratio of the ionic liquid to the organic solvent is 3:7) is adopted as an extracting agent, and reflux is carried out.

The feed flow rate was 100kg/h, and the feed contained 75 mass% of n-hexadecane and 25 mass% of 1-methylnaphthalene. The theoretical plate number of a countercurrent mixed extraction tower (C1) is 6, the feeding position of a diesel oil aromatic hydrocarbon mixture is 3, the feeding position of a mixed extracting agent is 1, the produced liquid at the top of the mixed extraction tower (C1) enters the mixed extraction tower (C2) from the bottom of the tower, the mixed extracting agent enters the mixed extraction tower (C2) from the top of the tower, the extracted material flow at the top of the mixed extraction tower (C2) is connected to the middle part of a raffinate flash tank (S1) for flash separation, the produced liquid from the bottoms of the mixed extraction tower (C1) and the mixed extraction tower (C2) enters an extract flash tank (S2) for flash separation, the volume ratio of the mixed extracting agent to the diesel oil aromatic hydrocarbon to be separated in each stage of extraction process is 1.5:1, the mass ratio of reflux aromatic hydrocarbon to the extracted system aromatic hydrocarbon in the produced liquid at the top of the flash tank (S2) is 0.55, the reflux position is 5, the recovery rate of n-hexadecane after multi-stage separation is 99.86%, the recovery rate of 1-methylnaphthalene was 99.25%. The purity of n-hexadecane in the extract was 99.85% (mass fraction), and the purity of 1-methylnaphthalene in the raffinate was 98.95% (mass fraction).

Example 10:

hydroxyl functionalized ionic liquid (particularly HOCMIM ] [ PF 6) is used as an extractant, and reflux is carried out.

The feed flow is 100kg/h, and the feed contains 70 percent of n-hexadecane (mass fraction) and 30 percent of 1-methylnaphthalene (mass fraction). The theoretical plate number of the mixed extraction tower (C1) is 6, the feeding position of a diesel-aromatic hydrocarbon mixture is 3, the feeding position of hydroxyl functionalized ionic liquid is 1, the produced liquid at the top of the mixed extraction tower (C1) enters the mixed extraction tower (C2) from the bottom of the tower, the hydroxyl functionalized ionic liquid enters the mixed extraction tower (C2) from the top of the tower, the produced stream at the top of the mixed extraction tower (C2) is connected to the middle part of a raffinate flash tank (S1) for flash separation, the produced liquid from the bottoms of the mixed extraction tower (C1) and the mixed extraction tower (C2) enters the middle part of the flash tank (S2) for flash separation, the volume ratio of the hydroxyl functionalized ionic liquid to the diesel-aromatic hydrocarbon to-be-separated material in the extraction process of each stage is 1:1, the mass ratio of return aromatic hydrocarbon (including condensed ring aromatic hydrocarbon) in the produced liquid at the top of the flash tank (S2) to the produced system is 0.45, the reflux position is the 5 th block, the recovery rate of the n-hexadecane after multi-stage separation is 99.9 percent, and the recovery rate of the 1-methylnaphthalene is 99.65 percent. The purity of n-hexadecane in the extract was 99.9% (mass fraction), and the purity of 1-methylnaphthalene in the raffinate was 99.55% (mass fraction).

Example 11:

amino functionalized ionic liquid (specifically [ HNC2MIM ] [ PF6]) is used as an extracting agent and is refluxed.

The feed flow is 100kg/h, and the feed contains 70 percent of n-hexadecane (mass fraction) and 30 percent of 1-methylnaphthalene (mass fraction). The theoretical plate number of the mixed extraction tower (C1) is 6, the feeding position of a diesel-aromatic hydrocarbon mixture is 3, the feeding position of amino functionalized ionic liquid is 1, the produced liquid at the top of the mixed extraction tower (C1) enters the mixed extraction tower (C2) from the bottom of the tower, the amino functionalized ionic liquid enters the mixed extraction tower (C2) from the top of the tower, the produced liquid at the top of the mixed extraction tower (C2) is connected to the middle part of a raffinate flash tank (S1) for flash separation, the produced liquid at the bottom of the mixed extraction tower (C1) and the mixed extraction tower (C2) enters the middle part of the flash tank (S2) for flash separation, the volume ratio of the amino functionalized ionic liquid to the diesel-aromatic hydrocarbon to-be-separated material in the extraction process of each stage is 1:1, the mass ratio of return aromatic hydrocarbon in the produced liquid at the top of the flash tank (S2) to the aromatic hydrocarbon in the extraction system is 0.45, and the return position is 5, the recovery rate of the n-hexadecane after multi-stage separation is 99.9 percent, and the recovery rate of the 1-methylnaphthalene is 99.55 percent. The purity of n-hexadecane in the extract was 99.85% (mass fraction), and the purity of 1-methylnaphthalene in the raffinate was 99.4% (mass fraction).

Example 12:

aryl functionalized ionic liquid (particularly BuPhIm BF 4) is used as an extracting agent and is refluxed.

The feed flow is 100kg/h, and the feed contains 70 percent of n-hexadecane (mass fraction) and 30 percent of 1-methylnaphthalene (mass fraction). The theoretical plate number of the mixed extraction tower (C1) is 6, the feeding position of the diesel aromatic hydrocarbon mixture is 3, the feeding position of the choline base functionalized ionic liquid is 1, the produced liquid at the top of the mixed extraction tower (C1) enters the mixed extraction tower (C2) from the bottom of the tower, the choline base functionalized ionic liquid enters the mixed extraction tower (C2) from the top of the tower, the produced stream at the top of the mixed extraction tower (C2) is connected to the middle part of a raffinate flash tank (S1) for flash separation, the produced liquid from the bottoms of the mixed extraction tower (C1) and the mixed extraction tower (C2) enters the middle part of an extract flash tank (S2) for flash separation, the volume ratio of the choline base functionalized ionic liquid to the diesel aromatic hydrocarbon to-be-separated material in each stage of extraction process is 1:1, the mass ratio of the reflux aromatic hydrocarbon to the produced system in the top of the extract flash tank (S2) is 0.45, the reflux position is the 5 th block, the recovery rate of the n-hexadecane after multi-stage separation is 99.9 percent, and the recovery rate of the 1-methylnaphthalene is 99.45 percent. The purity of n-hexadecane in the extract was 99.9% (mass fraction), and the purity of 1-methylnaphthalene in the raffinate was 99.5% (mass fraction).

The data show that the product separated by the method has high purity and high recovery rate, and the cetane number of the diesel oil product is greatly improved. The obtained high-purity aromatic hydrocarbon can be used for downstream production.