A method and device for reducing the amount of aromatic hydrocarbons recycled in an aromatic hydrocarbon extraction process

Abstract

The present invention relates to the field of petrochemical technology, and discloses a method and device for reducing the amount of aromatic hydrocarbons recycled in an aromatic hydrocarbon extraction process, comprising: (1) contacting a raw oil with an extraction solvent for extraction to obtain a first rich agent and a raffinate; (2) distilling and separating the first rich agent to obtain a second rich agent and reflux aromatic hydrocarbons; (3) extracting the oil phase in the reflux aromatic hydrocarbons with an extractant in at least one combination consisting of a static mixer and a settling tank to obtain return aromatic hydrocarbons and a lean extraction agent; (4) returning the return aromatic hydrocarbons to step (1), and returning the lean extraction agent to step (2). The method of the present invention can reduce the aromatic hydrocarbon reflux ratio, reduce energy consumption, and improve the extraction capacity of the extraction tower.

Description

Technical Field

[0001] The present invention relates to the technical field of petrochemical industry, and in particular to a method and device for reducing the circulation amount of aromatic hydrocarbons in an aromatic hydrocarbon extraction process. Background Art

[0002] With the increasing number of cars in cities, automobile pollution has gradually become one of the major sources of urban air pollution. To reduce automobile emissions, countries around the world have enacted increasingly stringent regulations. In recent years, the Chinese government and oil companies have been working tirelessly to improve fuel quality and environmental standards. The National VI gasoline standard, Phase A, was implemented nationwide on January 1, 2019; the National VI gasoline standard, Phase B, will be implemented nationwide starting in 2023. The National VI gasoline standard introduces new quality indicators for benzene and aromatics content, posing new challenges to the production of clean fuels and my country's refining technology. Benzene, toluene, and xylene (BTX), collectively known as the "triphenylenes," are essential raw materials in the petrochemical industry. Their production and scale are second only to ethylene and propylene, the "trienes," and they play a crucial role in chemical production. BTX is a key chemical raw material for synthetic fibers, rubber, plastics, detergents, dyes, pharmaceuticals, fragrances, and other products. As one of the most important basic raw materials for the production of petrochemical products, BTX production indicates the level of industrialization. In order to obtain high-purity aromatic products, the fuel oil is enriched and purified through solvent extraction. That is, the difference in molecular polarity is used to make the solvent have different solubility or different effects on relative volatility of each hydrocarbon component, and aromatics are selectively enriched in the solvent from the mixed hydrocarbons to achieve separation and purification of aromatic components and alkane components.

[0003] Aromatics extraction processes can be categorized into liquid-liquid extraction and extractive distillation based on their extraction principles. Different aromatics extraction processes also employ different extractants and process flows. Typical liquid-liquid extraction processes include UOP's Sulfolane process and Udex process, and Union Carbide's Tetra process. The Sulfolane process, using sulfolane as a solvent, is the most widely used of its kind. The Udex process, using diethylene glycol and triethylene glycol as solvents, is rarely used anymore, but the Tetra process, using tetraethylene glycol as a solvent, is still used for aromatics extraction from reformate oil. Extractive distillation processes include Lurgi's Distapex process, Uhde's Morphylane process, GTC's GT-BTX process, the Research Institute of Petrochemical Science's SED process, and Jin Weihui Engineering's SUPER-SAE-II. Although aromatics extraction and separation technologies have achieved considerable maturity both domestically and internationally, they still face challenges such as low extractant selectivity, high solvent-to-oil ratios, high energy consumption, and reduced lean extract effectiveness due to the enrichment of heavy hydrocarbons in the solvent.

[0004] In current production, the liquid-liquid extraction process is more widely used. In the liquid-liquid extraction process, the non-aromatic and aromatic hydrocarbon mixture separated by the extractive distillation tower is generally returned to the extraction tower as reflux aromatics. However, a high reflux ratio of reflux aromatics (return aromatics / feed) means that the amount of non-aromatic and aromatic hydrocarbons separated from the extraction tower is too high. On the one hand, this will lead to an excessively high gas phase load on the extractive distillation tower, or even tower flushing; on the other hand, it will cause a large amount of aromatics to circulate continuously between the extraction tower and the extractive distillation tower, resulting in a decrease in the actual catalyst-to-oil ratio of the extraction tower, thereby affecting the extraction capacity of the aromatic extraction unit. It can be seen that an excessively high aromatics circulation rate is the key to restricting the aromatics extraction processing capacity and energy consumption. Therefore, it is urgent to provide a method for aromatics extraction to increase the aromatics circulation rate. Summary of the Invention

[0005] The purpose of the present invention is to overcome the problem of excessively high aromatics circulation volume in the prior art and to provide a method and apparatus for reducing the aromatics circulation volume in an aromatics extraction process. The method and apparatus can reduce the amount of refluxed aromatics, thereby reducing the aromatics circulation volume, while also reducing operating energy consumption and the extraction tower agent-oil ratio, thereby improving the extraction capacity of the aromatics extraction unit.

[0006] In order to achieve the above object, the present invention provides a method for reducing the amount of aromatic hydrocarbons recycled in an aromatic hydrocarbon extraction process, the method comprising:

[0007] (1) contacting the crude oil with an extraction solvent to extract the crude oil, thereby obtaining a first rich agent and a raffinate;

[0008] (2) distilling and separating the first rich agent to obtain a second rich agent and reflux aromatics;

[0009] (3) extracting and separating the oil phase in the reflux aromatics and the extractant in at least one combination of a static mixer and a settling tank to obtain reflux aromatics and a lean extractant;

[0010] (4) returning the returned aromatic hydrocarbons to step (1) and returning the lean extraction agent to step (2).

[0011] Preferably, the feedstock oil is selected from one or more of reformed gasoline, cracked hydrogenated gasoline, naphtha, straight-run gasoline, catalytic diesel and catalytic diesel hydrogenated reformed gasoline; and / or the content of aromatics in the feedstock oil is greater than 5wt%; and / or the extraction solvent is selected from one or more of triethylene glycol, tetraethylene glycol, 2-pyrrolidone, N-methylpyrrolidone, N-ethylpyrrolidone, dimethyl sulfoxide, N-methylformamide, N-methylbenzylamide, N-formylmorpholine, N,N-dimethylformamide, hydrazine hydrate, furfural, ethylene glycol, glycerol methylal, polyethylene glycol and polycarbonate.

[0012] Preferably, the method further comprises: before step (3), performing oil-water separation on the reflux aromatics in step (2) to obtain an oil phase in the reflux aromatics and a water phase in the reflux aromatics. Preferably, the method further comprises: contacting the second rich solvent separated in step (2) with stripping steam to perform stripping to obtain a lean solvent and aromatics.

[0013] Preferably, the method further comprises: separating water from the extracted solvent after condensation to obtain anhydrous aromatics; and / or dividing the lean solvent obtained by stripping into part A and part B, part A being returned as the extraction solvent S2 to the tower for extraction in step (1), and part B being returned to the static mixer in step (4) for extraction.

[0014] Preferably, the method further comprises: cooling the raffinate oil obtained in step (1) and contacting the raffinate oil with washing water for washing to obtain non-aromatic hydrocarbons and raffinate oil washing water.

[0015] A second aspect of the present invention provides a device for reducing the amount of aromatic hydrocarbon circulation in an aromatic hydrocarbon extraction process, the device comprising an extraction tower, a stripping tower, a reflux aromatic hydrocarbon oil-water separation unit, and an extraction unit;

[0016] The extraction tower is used to extract the crude oil to obtain the first rich agent and the raffinate oil;

[0017] The stripping tower is used to fractionate and separate the raffinate oil from the extraction tower to obtain a second rich agent and reflux aromatics;

[0018] The reflux aromatics oil-water separation unit is used to separate the reflux aromatics from the distillation tower into oil and water to obtain an oil phase in the reflux aromatics and a water phase in the reflux aromatics;

[0019] The extraction unit includes at least one combination of a static mixer and a settling tank, wherein the combination of the static mixer and the settling tank is used to extract and separate the oil phase in the reflux aromatics from the reflux aromatics storage tank under the action of an extractant to obtain return aromatics and a lean extraction agent;

[0020] The settling tanks in each group are connected in series downstream of the static mixer.

[0021] The method of the present invention can reduce the reflux ratio of aromatic hydrocarbons in the return tower, increase the processing capacity of the raw oil extraction device, reduce the tower pressure of the extractive distillation tower, and alleviate the tower flushing phenomenon of the extractive distillation tower. The present invention is applicable to different raw oils, provides a way to broaden the raw materials for aromatic hydrocarbon extraction, and is suitable for industrial promotion. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 1 is a flow diagram of a method for reducing the amount of aromatic hydrocarbon circulation in an aromatic hydrocarbon extraction process according to an embodiment of the present invention.

[0023] Description of Reference Numerals

[0024] 1. Extraction tower; 2. Distillation tower; 3. Stripping tower; 4. Water scrubber; 5. Water storage tank; 6. Stripping tower heat exchanger; 7. Stripping tower condenser; 8. Aromatics storage tank; 9. Distillation tower condenser; 10. Reflux aromatics storage tank; 11. Static mixer; 12. Settling tank; 13. Raffinate oil cooler;

[0025] S1, crude oil; S2, extraction solvent; S3, first rich solvent; S4, raffinate; S5, second rich solvent; S6, reflux aromatics; S61, anhydrous reflux aromatics; S8, stripping water vapor; S9, lean solvent; S91, part A; S92, part B; S10, solvent-oil mixture; S11, return aromatics; S12, extraction lean solvent; S13, aromatics; S1301, anhydrous aromatics; S14, wash water; S15, non-aromatics; S16, raffinate wash water. DETAILED DESCRIPTION

[0026] The following is a detailed description of the specific embodiments of the present invention. It should be understood that the specific embodiments described herein are only used to illustrate and explain the present invention and are not intended to limit the present invention.

[0027] The endpoints of the ranges and any values disclosed herein are not limited to the precise ranges or values, and these ranges or values should be understood to include values close to these ranges or values. For numerical ranges, the endpoints of each range, the endpoints of each range and individual point values, and the individual point values can be combined with each other to obtain one or more new numerical ranges, which should be considered to be specifically disclosed herein.

[0028] In a first aspect, the present invention provides a method for reducing the amount of aromatic hydrocarbons recycled in an aromatic hydrocarbon extraction process, the method comprising:

[0029] (1) contacting the crude oil with an extraction solvent to extract the crude oil, thereby obtaining a first rich agent and a raffinate;

[0030] (2) distilling and separating the first rich agent to obtain a second rich agent and reflux aromatics;

[0031] (3) extracting and separating the oil phase in the reflux aromatics and the extractant in at least one group (e.g., one group, two groups, three groups, etc.) of a static mixer and a settling tank to obtain reflux aromatics and a lean extractant;

[0032] (4) returning the returned aromatic hydrocarbons to step (1) and returning the lean extraction agent to step (2).

[0033] The method of the present invention extracts the reflux aromatics obtained by distillation separation in a combination of a static mixer and a settling tank, and returns the returned aromatics to the extraction step. This extraction step reduces the circulation amount of the returned aromatics. At the same time, the extracted lean agent is returned to the distillation separation step, and the aromatic components in the ascending gas phase in the tower during distillation separation can be condensed and extracted, thereby further reducing the aromatic content in the reflux aromatic material distilled from the top of the extractive distillation tower.

[0034] In the present invention, reflux aromatics refers to the material distilled during distillation separation. After the oil phase in the distilled material is subjected to extraction phase separation treatment, the final extract phase will be obtained as return aromatics, and the lower extraction phase is the lean extraction agent. The return aromatics will return (i.e., reflux to) the extraction step. Therefore, the material distilled during distillation separation is called reflux aromatics, and the material finally returned to the extraction step is called return aromatics.

[0035] In the method of the present invention, the oil phase in the reflux aromatics and the extractant are extracted in at least one combination consisting of a static mixer and a settling tank to obtain return aromatics and a lean extraction agent, the return aromatics are returned to step (1), and the lean extraction agent is returned to step (2). In the embodiment, different raw materials can be applied, providing a way to broaden the raw materials for aromatic extraction. As long as the purpose of the present invention can be achieved, there is no restriction on the type of raw material oil, and raw materials containing aromatics are applicable to the present invention. In some embodiments, the raw material oil is selected from one or more of reformed gasoline, cracked hydrogenated gasoline, naphtha, straight-run gasoline, catalytic diesel and catalytic diesel hydrogenated reformed gasoline; preferably, the content of aromatics in the raw material oil is greater than 5wt% (for example, greater than 8wt%, 10wt%, 20wt%, 30wt%, 50wt%, 60wt%, 70wt%, 80wt%, 90wt%, 95wt%), more preferably 25-80wt%; and even more preferably 40-65wt%.

[0036] In the present invention, as long as the purpose of the present invention can be achieved, there is no limitation on the extraction conditions. It should be understood by those skilled in the art that the extraction is carried out in an extraction tower, and the extraction conditions can be selected according to the physical properties of the raw oil and the feed amount and other characteristics.

[0037] In the present invention, as long as the purpose of the present invention can be achieved, the type of the extraction solvent is not limited. In some embodiments, the extraction solvent is selected from one or more of triethylene glycol, tetraethylene glycol, 2-pyrrolidone, N-methylpyrrolidone, N-ethylpyrrolidone, dimethyl sulfoxide, N-methylformamide, N-methylbenzylamide, N-formylmorpholine, N,N-dimethylformamide, hydrazine hydrate, furfural, ethylene glycol, glycerol methylal, polyethylene glycol, and polycarbonate; preferably, the extraction solvent is selected from one or more of tetraethylene glycol, dimethyl sulfoxide, cyclopentane, N-methylformamide, N-formylmorpholine, hydrazine hydrate, and polyethylene glycol.

[0038] In the method of the present invention, the feed method of supplying the raw oil to the extraction tower can be: feeding the raw oil alone from the middle of the extraction tower, or feeding the raw oil alone from the bottom of the extraction tower, or feeding the raw oil from the middle and bottom of the extraction tower at the same time, preferably feeding the raw oil alone from the middle of the extraction tower; the feed method of supplying the extraction solvent to the extraction tower can be: feeding the extraction solvent alone from the middle of the extraction tower, or feeding the extraction solvent alone from the top of the extraction tower, or feeding the extraction solvent from the middle and top of the extraction tower at the same time, preferably feeding the extraction solvent alone from the top of the extraction tower.

[0039] In the present invention, the purpose of distillation separation is to separate and obtain a second rich agent containing aromatics. In the process of distillation separation, reflux aromatics containing non-aromatic components and aromatic components will also be obtained. It should be understood by those skilled in the art that there is no particular limitation on the conditions for distillation separation in step (2). The second rich agent and reflux aromatics can be obtained by selective separation according to different raw oils and extraction solvents. The way in which the first rich agent enters the distillation separation can be any way. In some embodiments, the first rich agent is introduced separately from the top of the device for distillation separation, or separately from the middle of the device for distillation separation, or separately from the bottom of the device for distillation separation, or simultaneously introduced from the top, middle and bottom of the device for distillation separation; preferably, the first rich agent is introduced separately from the top of the device for distillation separation.

[0040] In the present invention, the second rich agent contains extraction solvent and aromatic hydrocarbons as main components; the temperature during distillation separation is high, and the distilled light components will contain some aromatic components, so the reflux aromatic hydrocarbons include non-aromatic components and aromatic components.

[0041] In the present invention, the oil phase in the reflux aromatics refers to anhydrous reflux aromatics. Preferably, the method further comprises: before step (3), performing oil-water separation on the reflux aromatics in step (2) to obtain the oil phase in the reflux aromatics (i.e., anhydrous reflux aromatics) and the water phase in the reflux aromatics. According to the method of the present invention, the oil phase in the reflux aromatics enters the static mixer, and the water phase in the reflux aromatics is sent to the water storage tank.

[0042] In step (3) of the method of the present invention, each group includes a static mixer and a settling tank, the oil phase in the reflux aromatics is added from the static mixer of the first group and extracted with the extractant in the static mixer to obtain an extractant-oil mixture, the extractant-oil mixture in the static mixer of each group enters the corresponding settling tank for stratification, the raffinate phase on the upper layer of the settling tank flows into the static mixer of the next group and continues to complete the extraction with the extractant in the static mixer, the raffinate phase on the upper layer of the settling tank of the last group is the return tower aromatics, and the extract phases on the lower layers of the settling tanks of all groups are combined to form the lean extractant.

[0043] In the present invention, "agent-oil mixture" refers to the mixture of the extractant and the oil phase in the reflux aromatics in the static mixer of the first group or the mixture of the extractant and the raffinate phase in the static mixers of other groups (the remaining groups except the first group).

[0044] In step (3) of the present invention, as long as the purpose of the present invention can be achieved, the number of groups of the combination of static mixers and sedimentation tanks is not limited. In some embodiments of the present invention, the oil phase in the reflux aromatics and the extractant complete extraction and stratification in a group of combinations consisting of a static mixer and a sedimentation tank, the oil phase in the reflux aromatics and the extractant are extracted in the static mixer to obtain an agent-oil mixture that enters the sedimentation tank for stratification to obtain return tower aromatics and extracted lean agent; in other embodiments of the present invention, the oil phase in the reflux aromatics and the extractant complete extraction and phase separation in two groups of combinations consisting of static mixers and sedimentation tanks, the oil phase in the reflux aromatics and the extractant are extracted in the static mixer of the first group to obtain an agent-oil mixture that enters the sedimentation tank in the first group for stratification, and after stratification, the raffinate phase on the upper layer flows into the static mixer of the second group and is mixed with the extractant in the static mixer of the second group to obtain an agent-oil mixture that flows into the corresponding sedimentation tank for stratification, the raffinate phase on the upper layer of the second group of sedimentation tanks is return tower aromatics, and the extract phases on the lower layer of the sedimentation tanks in the first and second groups are combined to form an extracted lean agent.

[0045] In the method of the present invention, as long as the purpose of the present invention can be achieved, the ratio of the oil phase or the raffinate phase in the reflux aromatics in the static mixer to the corresponding extractant is not limited. In some preferred embodiments, the agent-oil mass ratio in the static mixer is higher than 0.05:1 (for example, higher than 0.05:1, higher than 0.1:1, higher than 0.2:1, higher than 0.4:1, higher than 0.8:1, higher than 1.2:1, higher than 1.8:1, higher than 2:1, etc.); further preferably, the agent-oil mass ratio in the static mixer is 0.1-2:1; further preferably, the agent-oil mass ratio in the static mixer is 0.5-2:1. The above-mentioned embodiment can better reduce the circulation amount of aromatics, thereby reducing the aromatics reflux ratio, reducing the operating energy consumption and the agent-oil ratio of the extraction tower, thereby improving the extraction capacity of the aromatics extraction device.

[0046] In the present invention, the agent-oil ratio refers to the mass ratio of the extractant in the static mixer to the oil phase or raffinate phase in the reflux aromatics.

[0047] In the method of the present invention, as long as the purpose of the present invention can be achieved, the extraction conditions in the static mixer are not limited. In some preferred embodiments, in step (3), the extraction temperature in the static mixer is higher than room temperature (e.g., higher than 10°C, higher than 20°C, higher than 30°C, higher than 40°C, higher than 50°C, higher than 70°C, higher than 80°C); further preferably, the extraction temperature in the static mixer is 20-80°C. The above embodiment can better reduce the content of aromatics in the return aromatics, making the present invention applicable to different feedstock oils, and providing a way to broaden the raw materials for aromatic extraction.

[0048] In some preferred embodiments, the operating pressure of the extraction in the static mixer in step (3) is normal pressure.

[0049] In the present invention, normal temperature refers to 15-30°C.

[0050] In some preferred embodiments of the present invention, in step (4), the return aromatics are returned to step (1) by introducing the return aromatics into the bottom of the extraction column from which extraction is performed in step (1); and / or the lean extractant is returned to step (2) by introducing the lean extractant into the top of the distillation column from which distillation separation is performed in step (2). The aforementioned embodiments can better reduce the amount of reflux aromatics produced, thereby lowering the aromatics reflux ratio, reducing energy consumption, and improving the extraction capacity of the extraction column.

[0051] In the method of the present invention, as long as the purpose of the present invention can be achieved, the method of introducing the extracting agent into the top of the distillation tower for distillation separation in step (2) is not limited. In some preferred embodiments, the extracting agent is introduced into the top of the distillation tower for distillation separation in step (2) by atomizing the extracting agent into small droplets and spraying them into the distillation tower from the top of the distillation tower. The above embodiment can achieve the technical effect of fully extracting the aromatic components in the gas phase at the top of the distillation tower to reduce the circulating amount of reflux aromatics.

[0052] In the method of the present invention, in step (4), the reflux ratio of the returned aromatic hydrocarbons is (0.4-1.3):1 (for example, 0.4:1, 0.6:1, 1:1, etc.), preferably (0.4-1):1.

[0053] In the present invention, the reflux ratio of the return aromatics refers to the ratio of the flow rate of the return aromatics to the flow rate of the feed oil at the same time.

[0054] The method of the present invention further comprises contacting the second rich solvent separated in step (2) with stripping steam to perform stripping to obtain a lean solvent and aromatic hydrocarbons.

[0055] In some embodiments, the stripping method is: the second rich solvent separated in step (2) is introduced into a stripping tower and contacted with stripping steam in the stripping tower for stripping, the lean solvent is produced from the bottom of the stripping tower, and the aromatic hydrocarbons are produced from the top of the stripping tower.

[0056] As long as the purpose of the present invention can be achieved, there is no limitation on the manner in which the second rich agent and the stripping water vapor are introduced into the stripping tower. In some embodiments, the second rich agent and the stripping water vapor are introduced into the stripping tower as follows: the second rich agent and the stripping water vapor are independently introduced from the top, middle or bottom of the stripping tower. Preferably, the second rich agent is introduced into the stripping tower from the top of the stripping tower, and the stripping water vapor is introduced into the stripping tower from the bottom of the stripping tower.

[0057] In the method of the present invention, those skilled in the art should understand that, as long as the lean solvent and aromatic hydrocarbons can be separated, the operating conditions of the stripping tower are not limited.

[0058] In the method of the present invention, in order to remove moisture from the obtained aromatic hydrocarbons, in some preferred embodiments, the method of the present invention further comprises condensing the produced aromatic hydrocarbons and separating water to obtain anhydrous aromatic hydrocarbons; and the water separated after the condensation of the aromatic hydrocarbons is sent to a water storage tank.

[0059] In some preferred embodiments, the anhydrous aromatic hydrocarbons are produced as products; in other preferred embodiments, the anhydrous aromatic hydrocarbons enter a separation section to separate components such as benzene, toluene, and xylene.

[0060] In some embodiments, the method of the present invention further comprises dividing the lean solvent obtained by stripping into part A and part B, wherein part A is returned as the extraction solvent to the tower for extraction in step (1), and part B is returned to the static mixer in step (3) for extraction.

[0061] There is no requirement for the specific ratio of Part A to Part B, and the ratio can be selected as needed.

[0062] In the method of the present invention, the extractant in step (3) is fresh extractant and / or the B portion of the lean solvent.

[0063] The fresh extractant is selected from one or more of triethylene glycol, tetraethylene glycol, 2-pyrrolidone, N-methylpyrrolidone, N-ethylpyrrolidone, dimethyl sulfoxide, N-methylformamide, N-methylbenzylamide, N-formylmorpholine, N,N-dimethylformamide, hydrazine hydrate, furfural, ethylene glycol, glycerol methylal, polyethylene glycol, and polycarbonate; preferably, the extraction solvent is selected from one or more of tetraethylene glycol, dimethyl sulfoxide, sulfolane, N-methylformamide, N-formylmorpholine, hydrazine hydrate, and polyethylene glycol; preferably, the fresh extractant is selected from one or more of tetraethylene glycol, dimethyl sulfoxide, sulfolane, N-methylformamide, N-formylmorpholine, hydrazine hydrate, and polyethylene glycol.

[0064] In some embodiments, the method of the present invention further comprises cooling the raffinate oil obtained in step (1) and contacting the raffinate oil with washing water for washing to obtain non-aromatic hydrocarbons and raffinate oil washing water.

[0065] As long as the purpose of the present invention can be achieved, the method of water washing is not limited. In some preferred embodiments, the water washing step is: the cooled raffinate oil is introduced into the water washing tower from the bottom of the water washing tower, and the washing water is introduced into the water washing tower from the top of the water washing tower. The cooled raffinate oil and the washing water are contacted in the water washing tower for water washing to obtain non-aromatic hydrocarbons and raffinate oil washing water; the non-aromatic hydrocarbons are extracted as products.

[0066] According to the present invention, in order to make full use of various heat, in the present invention, the feeding or discharging of each material can achieve heat exchange through pipes, heat exchangers or condensers. The present invention has no special requirements for this and will not be described in detail here.

[0067] In accordance with the method of the present invention, a second aspect of the present invention provides a device for reducing the amount of aromatic hydrocarbons recycled in an aromatic hydrocarbon extraction process, the device comprising an extraction tower, a stripping tower, a reflux aromatic hydrocarbon oil-water separation unit, and an extraction unit.

[0068] The extraction tower is used to extract the crude oil to obtain the first rich agent and the raffinate oil;

[0069] The stripping tower is used to distill and separate the first rich agent from the extraction tower to obtain a second rich agent and reflux aromatics;

[0070] The reflux aromatics oil-water separation unit is used to separate the reflux aromatics from the distillation tower into oil and water to obtain an oil phase in the reflux aromatics and a water phase in the reflux aromatics;

[0071] The extraction unit includes at least one combination of a static mixer and a settling tank, and the combination of the static mixer and the settling tank is used to extract the oil phase in the reflux aromatics under the action of an extractant to obtain return aromatics and a lean extraction agent.

[0072] The settling tanks in each group are connected in series to the static mixers in the next group.

[0073] Specifically, the present invention provides a device for reducing the amount of aromatic hydrocarbon circulation in an aromatic hydrocarbon extraction process, the device comprising an extraction tower, a stripping tower, a reflux aromatic hydrocarbon oil-water separation unit, and an extraction unit;

[0074] The extraction tower is used to extract the crude oil in the presence of an extraction solvent to perform preliminary separation of aromatic and non-aromatic components in the crude oil, obtain raffinate at the top of the extraction tower, and obtain the first rich solvent at the bottom of the extraction tower;

[0075] The stripping tower is used to distill and separate the first rich agent obtained by extraction, so that the aromatic hydrocarbons, non-aromatic hydrocarbons and extraction solvent components in the first rich agent are further separated, and the reflux aromatic hydrocarbons are obtained at the top of the stripping tower and the second rich agent is obtained at the bottom of the stripping tower;

[0076] The reflux aromatics oil-water separation unit is used to separate the reflux aromatics from the distillation tower into oil and water, and the outlets respectively obtain the oil phase and the water phase of the reflux aromatics;

[0077] An extraction unit, which is used to include the extraction unit in a combination of at least one group consisting of a static mixer and a settling tank, wherein the settling tank in each group is connected in series downstream of the static mixer, and is used to add anhydrous reflux aromatics from the static mixer of the first group and mix with the extractant in the static mixer to obtain an agent-oil mixture, and the agent-oil mixture in the static mixer of each group enters the corresponding settling tank for stratification, and the raffinate phase on the upper layer of the settling tank flows into the static mixer of the next group to continue extraction with the extractant in the static mixer, and the raffinate phase on the upper layer of the settling tank of the last group is return tower aromatics, and the extraction phases on the lower layers of the settling tanks in all groups are combined to form a lean extraction agent. According to the present invention, preferably, the extraction tower includes a feed oil inlet arranged on the side wall, an extraction solvent inlet on the side wall, a first rich agent outlet at the bottom, a raffinate oil outlet at the top, and a return tower aromatics inlet on the side wall; and / or

[0078] The stripping tower comprises a first rich agent inlet arranged on the side wall, a second rich agent outlet at the bottom, a reflux aromatics outlet at the top, and an extraction lean agent inlet at the side wall; and / or

[0079] The reflux aromatics oil-water separation unit is a reflux aromatics storage tank, which includes a reflux aromatics inlet at the top, a water phase outlet at the bottom, and a water-free reflux aromatics oil phase outlet on the side wall; and / or

[0080] The at least one group of static mixers and settling tanks is connected in series with each other, the static mixer in each group includes an inlet for the material to be extracted provided on the side wall, an inlet for the extractant provided on the top, and an outlet for the agent-oil mixture provided on the side wall, and the settling tank includes an inlet for the agent-oil mixture provided on the side wall, an outlet for the raffinate phase provided on the side wall, and an outlet for the extracted phase provided on the side wall; and / or

[0081] The first rich agent outlet is connected to the first rich agent inlet, the reflux aromatic hydrocarbon outlet is connected to the reflux aromatic hydrocarbon inlet, the anhydrous reflux aromatic hydrocarbon oil phase outlet is connected to the material to be extracted inlet of the static mixer in the first group, the agent-oil mixture outlet is connected to the agent-oil mixture inlet, the raffinate phase outlet of the upper group is connected to the material to be extracted inlet of the next group, the extraction phase outlet of the last group is connected to the extraction lean agent inlet, and the raffinate phase outlet is connected to the return tower aromatic hydrocarbon inlet.

[0082] According to the present invention, preferably, the device further comprises: a stripping tower for contacting the second rich solvent obtained by distillation separation with water vapor for stripping, producing lean solvent from the bottom of the stripping tower and producing aromatic hydrocarbons from the top of the stripping tower.

[0083] According to the present invention, preferably, the device further comprises: an aromatic hydrocarbon oil-water separation unit for separating the aromatic hydrocarbons produced from the top of the stripping tower into oil and water to obtain anhydrous aromatic hydrocarbons and water.

[0084] According to the present invention, preferably, the device further comprises: a water washing tower for washing the raffinate oil obtained by extraction with washing water to obtain non-aromatic hydrocarbons and raffinate oil washing water.

[0085] According to the present invention, preferably, the device further comprises a water storage tank for storing water obtained in the process and / or providing water for the process.

[0086] According to the present invention, preferably, the water obtained in the storage process includes the water separated by the reflux aromatic oil-water separation unit and the water separated in the aromatic oil-water separation unit; and / or the water provided for the process includes the wash water provided for the water washing tower and the stripping water vapor provided for the stripping tower.

[0087] According to the present invention, preferably, the stripping tower comprises a second rich solvent inlet arranged on the side wall, a stripping water vapor inlet on the side wall, an aromatic hydrocarbon outlet at the top, and a lean solvent outlet at the bottom; and / or

[0088] The aromatic oil-water separation unit is an aromatic storage tank, which includes an aromatic inlet arranged at the top, an anhydrous aromatic outlet on the side wall, and a water outlet at the bottom; and / or

[0089] The water scrubber comprises a raffinate inlet provided on the side wall, a water inlet provided on the side wall, a non-aromatic hydrocarbon outlet provided on the top, and a water outlet provided on the bottom; and / or

[0090] The water storage tank comprises a process water inlet and a process water outlet at the bottom; and / or

[0091] The second rich solvent inlet is connected to the second rich solvent outlet, the stripping water vapor inlet is connected to the process water outlet, the aromatics outlet is connected to the aromatics inlet, and the lean solvent outlet, extractant inlet and feed oil inlet are independently connected; and / or

[0092] The anhydrous aromatics outlet is used to produce anhydrous aromatics products or anhydrous aromatics flow out to the separation section, and the water outlet is connected to the process water inlet; and / or

[0093] The raffinate oil inlet is communicated with the raffinate oil outlet, the water inlet is communicated with the process water outlet, the non-aromatic hydrocarbon outlet is used to produce non-aromatic hydrocarbons, and the water outlet is communicated with the process water inlet.

[0094] In the device of the present invention, there is no particular limitation on the specific structures of the extraction tower, distillation tower, steam stripping tower, water scrubber, water storage tank, aromatics storage tank, static mixer, and sedimentation tank. They can be various extraction towers, distillation towers, steam stripping towers, water scrubbers, water storage tanks, aromatics storage tanks, static mixers, and sedimentation tanks commonly used in the art, which are well known to those skilled in the art and will not be described in detail here.

[0095] In order to make full use of various heat, the various material inlets or material outlets in the present invention can be cross-connected to achieve heat exchange through pipes, heat exchangers or condensers. The present invention has no special requirements for this and will not be elaborated here.

[0096] According to one embodiment of the present invention, Figure 1 As shown, the equipment for implementing the method of reducing the aromatic hydrocarbon circulation amount in the aromatic hydrocarbon extraction process mainly includes: an extraction tower 1, a distillation tower 2, a steam stripping tower 3, a water washing tower 4, a water storage tank 5, an aromatic hydrocarbon storage tank 8, and a reflux aromatic hydrocarbon storage tank 10.

[0097] Specifically, the method for reducing the amount of aromatic hydrocarbon circulation in the aromatic hydrocarbon extraction process includes: introducing a raw material oil such as reformed gasoline S1 into the extraction tower 1 from the middle of the extraction tower 1, introducing an extraction solvent S2 into the extraction tower from the top of the extraction tower 1, the raw material oil such as reformed gasoline S1 and the extraction solvent S2 contacting in the extraction tower 1 for extraction, producing a first rich agent S3 from the bottom of the extraction tower 1, and producing a raffinate oil S4 from the top of the extraction tower 1;

[0098] The first rich agent S3 is introduced into the stripping tower from the top of the stripping tower for distillation separation, the second rich agent S5 is produced from the bottom of the stripping tower, and the reflux aromatics S6 is produced from the top of the stripping tower; the reflux aromatics S6 is first cooled by the stripping tower condenser 9 and introduced into the reflux aromatics storage tank 10 to separate the water and send it to the water storage tank 5, and then the anhydrous reflux aromatics S61 in the reflux aromatics storage tank 10 is introduced into the static mixer 11 and mixed with the extractant in the static mixer 11 to obtain the agent-oil mixture S10;

[0099] The agent-oil mixture S10 is introduced into the sedimentation tank 12. After separation, the upper raffinate phase is the return aromatics S11, and the lower extract phase is the lean agent S12.

[0100] The above-mentioned return aromatic hydrocarbons S11 are extracted from the bottom of the extraction tower 1, and the extraction agent S12 is atomized into small droplets and sprayed into the distillation tower 2 from the top of the distillation tower 2 for distillation separation;

[0101] The second rich agent S5 is introduced into the stripping tower 3 from the middle of the stripping tower 3. The water in the water storage tank is passed through the stripping heat exchanger to obtain stripping steam S8. The stripping steam S8 is introduced into the stripping tower 3 from the bottom of the stripping tower 3. The second rich agent S5 and the stripping steam S8 are in contact with each other in the stripping tower 3 to perform stripping. The lean solvent S9 is produced from the bottom of the stripping tower 3, and the aromatic hydrocarbons S13 are produced from the top of the stripping tower 3.

[0102] The produced aromatics S13 are condensed in the stripping tower condenser 7 and then introduced into the aromatics storage tank 8. Water is separated from the aromatics storage tank 8 to obtain anhydrous aromatics S1301 as the product; the water separated from the aromatics storage tank 8 is sent to the water storage tank;

[0103] The extracted lean solvent S9 is divided into part A S91 and part B S92. Part A is used as the extraction solvent S2 for extraction in the extraction tower 1, and part B S92 is returned to the static mixer 11 for extraction;

[0104] The raffinate oil S4 is cooled in the raffinate oil cooler 13 and then introduced into the water scrubber 4 from the bottom thereof. The washing water S14 from the water storage tank 5 is introduced into the water scrubber 4 from the top thereof. The raffinate oil S4 and the washing water S14 are contacted in the water scrubber 4 for washing. Non-aromatic hydrocarbons S15 are extracted from the top of the water scrubber 4, and raffinate oil washing water S16 is extracted from the bottom of the water scrubber. The obtained non-aromatic hydrocarbons S15 are extracted as products, and the obtained raffinate oil washing water S16 is returned to the water storage tank for recycling.

[0105] The present invention will be described in detail below by way of examples.

[0106] The reduction amount of aromatics in the return tower = the content of aromatics in the anhydrous reflux aromatics S61 - the content of aromatics in the return tower aromatics S11; the aromatics removal rate = the reduction amount of aromatics in the return tower / the aromatics content in the anhydrous reflux aromatics S61 * 100%.

[0107] Example 1

[0108] like Figure 1 As shown, a method for reducing the amount of aromatic hydrocarbons recycled in an aromatic hydrocarbon extraction process comprises:

[0109] The raw oil S1 is introduced into the extraction tower 1 from the middle part, and the extraction solvent S2 is introduced into the extraction tower from the top part of the extraction tower 1. The raw oil S1 and the extraction solvent S2 are contacted in the extraction tower 1 for extraction. The first rich agent S3 is extracted from the bottom of the extraction tower 1, and the raffinate oil S4 is extracted from the top part of the extraction tower 1.

[0110] The first rich agent S3 is introduced into the stripping tower 2 from the top of the stripping tower 2 for distillation separation, the second rich agent S5 is produced from the bottom of the stripping tower 2, and the reflux aromatics S6 is produced from the top of the stripping tower 2; the reflux aromatics S6 is first cooled by the stripping tower condenser 9 and introduced into the reflux aromatics storage tank 10 to separate the water and send it to the water storage tank 5, and then the anhydrous reflux aromatics S61 in the reflux aromatics storage tank 10 is introduced into the static mixer 11 and mixed with the extractant in the static mixer 11 to obtain the agent-oil mixture S10;

[0111] The agent-oil mixture S10 is introduced into the sedimentation tank 12. After separation, the upper raffinate phase is the return aromatics S11, and the lower extract phase is the lean agent S12.

[0112] The above-mentioned return aromatic hydrocarbons S11 are extracted from the bottom of the extraction tower 1, and the extraction agent S12 is atomized into small droplets and sprayed into the distillation tower 2 from the top of the distillation tower 2 for distillation separation;

[0113] The second rich agent S5 is introduced into the stripping tower 3 from the middle of the stripping tower 3. The water in the water storage tank is passed through the stripping heat exchanger to obtain stripping steam S8. The stripping steam S8 is introduced into the stripping tower 3 from the bottom of the stripping tower 3. The second rich agent S5 and the stripping steam S8 are in contact with each other in the stripping tower 3 to perform stripping. The lean solvent S9 is produced from the bottom of the stripping tower 3, and the aromatic hydrocarbons S13 are produced from the top of the stripping tower 3.

[0114] The produced aromatics S13 are condensed in the stripping tower condenser 7 and then introduced into the aromatics storage tank 8, water is separated from the aromatics storage tank 8, and anhydrous aromatics S1301 are obtained as the product;

[0115] The extracted lean solvent S9 is divided into part A S91 and part B S92. Part A is used as the extraction solvent S2 for extraction in the extraction tower 1, and part B S92 is returned to the static mixer 11 for extraction;

[0116] The raffinate oil S4 is cooled in the raffinate oil cooler 13 and then introduced into the water scrubber 4 from the bottom thereof. Washing water S14 from the water storage tank 5 is introduced into the water scrubber 4 from the top thereof. The raffinate oil S4 and the washing water S14 are contacted in the water scrubber 4 for washing. Non-aromatic hydrocarbons S15 are extracted from the top of the water scrubber 4. Raffinate oil washing water S16 is extracted from the bottom of the water scrubber. The obtained non-aromatic hydrocarbons S15 are extracted as products. The obtained raffinate oil washing water S16 is returned to the water storage tank for recycling.

[0117] in:

[0118] The raw oil S1 is a simulated oil with an aromatic content of 65 wt%, the feed rate of the raw oil S1 is 30 t / h, the extraction solvent S2 is tetraethylene glycol, and the feed rate of the extraction solvent S2 is 150 t / h; the temperature of the extraction tower 1 is 120°C and the pressure is 0.6 MPa;

[0119] The flow rate of the first rich agent S3 entering the distillation tower 2 is 200t / h, the temperature of the distillation tower 2 is 120℃, and the pressure is 0.1MPa;

[0120] The extractant-to-oil ratio of the extractant to the anhydrous reflux aromatic hydrocarbon S61 is 2:1, the operating temperature and pressure in the static mixer 11 are normal temperature and normal pressure; the reflux ratio of the return aromatic hydrocarbon S11 is 1:1;

[0121] The flow rate of the second rich agent S5 entering the stripping tower 3 is 170 t / h, the flow rate of the stripping steam S8 entering the stripping tower 3 is 6 t / h, and the operating conditions of the stripping tower 3 are: temperature 150°C, pressure 0.1 MPa;

[0122] The extractant is Part B S92;

[0123] The operating conditions of the water washing tower 4 are: temperature 30° C. and pressure 0.2 MPa.

[0124] When the aromatic content in the anhydrous reflux aromatics S61 is 70 wt%, the return aromatics reduction and aromatics removal rate are tested, and the results are shown in Table 1.

[0125] Example 2

[0126] The rest is the same as Example 1, except that the agent-to-oil ratio of the extractant to the anhydrous reflux aromatic hydrocarbon S61 is 1.5:1.

[0127] When the aromatic content in the anhydrous reflux aromatics S61 is 70 wt%, the return aromatics reduction and aromatics removal rate are tested, and the results are shown in Table 1.

[0128] Example 3

[0129] Other aspects are the same as in Example 1, except that the agent-to-oil ratio of the extractant to the anhydrous reflux aromatic hydrocarbon S61 is 1:1.

[0130] When the aromatic content in the anhydrous reflux aromatics S61 is 70 wt%, the return aromatics reduction and aromatics removal rate are tested, and the results are shown in Table 1.

[0131] Example 4

[0132] Other aspects are the same as in Example 1, except that the agent-to-oil ratio of the extractant to the anhydrous reflux aromatic hydrocarbon S61 is 0.75:1.

[0133] When the aromatic content in the anhydrous reflux aromatics S61 is 70 wt%, the return aromatics reduction and aromatics removal rate are tested, and the results are shown in Table 1.

[0134] Example 5

[0135] The other steps are the same as those in Example 1, except that the agent-to-oil ratio of the extractant to the anhydrous reflux aromatic hydrocarbon S61 is 0.5:1.

[0136] When the aromatic content in the anhydrous reflux aromatics S61 is 70 wt%, the return aromatics reduction and aromatics removal rate are tested, and the results are shown in Table 1.

[0137] Example 6

[0138] Other aspects are the same as in Example 1, except that the agent-to-oil ratio of the extractant to the anhydrous reflux aromatic hydrocarbon S61 is 0.25:1.

[0139] When the aromatic content in the anhydrous reflux aromatics S61 is 70 wt%, the return aromatics reduction and aromatics removal rate are tested, and the results are shown in Table 1.

[0140] Example 7

[0141] The rest is the same as in Example 1, except that:

[0142] The extraction solvent S2 is sulfolane, the temperature of the extraction column 1 is 90°C, and the pressure is 0.5 MPa;

[0143] The reflux ratio of the return aromatics S11 is 0.4:1;

[0144] The flow rate of the first rich agent S3 entering the distillation tower 2 is 185t / h;

[0145] The operating conditions of stripping tower 3 are: temperature 150°C, pressure 0.1 MPa;

[0146] The extraction solvent S2 is sulfolane.

[0147] When the aromatic content in the anhydrous reflux aromatics S61 is 70 wt%, the return aromatics reduction and aromatics removal rate are tested, and the results are shown in Table 1.

[0148] Example 8

[0149] The rest is the same as Example 7, except that the agent-to-oil ratio of the extractant to the anhydrous reflux aromatic hydrocarbon S61 is 1.5:1.

[0150] When the aromatic content in the anhydrous reflux aromatics S61 is 70 wt%, the return aromatics reduction and aromatics removal rate are tested, and the results are shown in Table 1.

[0151] Example 9

[0152] The rest is the same as Example 7, except that the agent-to-oil ratio of the extractant to the anhydrous reflux aromatic hydrocarbon S61 is 1:1.

[0153] When the aromatic content in the anhydrous reflux aromatics S61 is 70 wt%, the return aromatics reduction and aromatics removal rate are tested, and the results are shown in Table 1.

[0154] Example 10

[0155] The rest is the same as Example 7, except that the agent-to-oil ratio of the extractant to the anhydrous reflux aromatic hydrocarbon S61 is 0.75:1.

[0156] When the aromatic content in the anhydrous reflux aromatics S61 is 70 wt%, the return aromatics reduction and aromatics removal rate are tested, and the results are shown in Table 1.

[0157] Example 11

[0158] The rest is the same as Example 7, except that the agent-to-oil ratio of the extractant to the anhydrous reflux aromatic hydrocarbon S61 is 0.5:1.

[0159] When the aromatic content in the anhydrous reflux aromatics S61 is 70 wt%, the return aromatics reduction and aromatics removal rate are tested, and the results are shown in Table 1.

[0160] Example 12

[0161] The rest is the same as Example 7, except that the agent-to-oil ratio of the extractant to the anhydrous reflux aromatic hydrocarbon S61 is 0.25:1.

[0162] When the aromatic content in the anhydrous reflux aromatics S61 is 70 wt%, the return aromatics reduction and aromatics removal rate are tested, and the results are shown in Table 1.

[0163] Example 13

[0164] The rest is the same as Example 7, except that:

[0165] The feedstock oil S1 is a simulated oil with an aromatic content of 45 wt%.

[0166] When the aromatic content in the anhydrous reflux aromatics S61 is 50 wt%, the return aromatics reduction and aromatics removal rate are tested, and the results are shown in Table 1.

[0167] Example 14

[0168] The rest is the same as Example 13, except that the agent-to-oil ratio of the extractant to the anhydrous reflux aromatic hydrocarbon S61 is 1.5:1.

[0169] When the aromatic content in the anhydrous reflux aromatics S61 is 50 wt%, the return aromatics reduction and aromatics removal rate are tested, and the results are shown in Table 1.

[0170] Example 15

[0171] The rest is the same as Example 13, except that the agent-to-oil ratio of the extractant to the anhydrous reflux aromatic hydrocarbon S61 is 1:1.

[0172] When the aromatic content in the anhydrous reflux aromatics S61 is 50 wt%, the return aromatics reduction and aromatics removal rate are tested, and the results are shown in Table 1.

[0173] Example 16

[0174] The rest is the same as Example 13, except that the agent-to-oil ratio of the extractant to the anhydrous reflux aromatic hydrocarbon S61 is 0.75:1.

[0175] When the aromatic content in the anhydrous reflux aromatics S61 is 50 wt%, the return aromatics reduction and aromatics removal rate are tested, and the results are shown in Table 1.

[0176] Example 17

[0177] The rest is the same as Example 13, except that the agent-to-oil ratio of the extractant to the anhydrous reflux aromatic hydrocarbon S61 is 0.5:1.

[0178] When the aromatic content in the anhydrous reflux aromatics S61 is 50 wt%, the return aromatics reduction and aromatics removal rate are tested, and the results are shown in Table 1.

[0179] Example 18

[0180] The rest is the same as Example 13, except that the agent-to-oil ratio of the extractant to the anhydrous reflux aromatic hydrocarbon S61 is 0.25:1.

[0181] When the aromatic content in the anhydrous reflux aromatics S61 is 50 wt%, the return aromatics reduction and aromatics removal rate are tested, and the results are shown in Table 1.

[0182] Example 19

[0183] Other aspects are the same as those of Example 7, except that the feedstock S1 is a simulated oil with an aromatic content of 40 w%.

[0184] When the aromatic content in the anhydrous reflux aromatics S61 is 30 wt%, the return aromatics reduction and aromatics removal rate are tested, and the results are shown in Table 1.

[0185] Example 20

[0186] The rest is the same as Example 19, except that the agent-to-oil ratio of the extractant to the anhydrous reflux aromatic hydrocarbon S61 is 1.5:1.

[0187] When the aromatic content in the anhydrous reflux aromatics S61 is 30 wt%, the return aromatics reduction and aromatics removal rate are tested, and the results are shown in Table 1.

[0188] Example 21

[0189] The rest is the same as Example 19, except that the agent-to-oil ratio of the extractant to the anhydrous reflux aromatic hydrocarbon S61 is 1:1.

[0190] When the aromatic content in the anhydrous reflux aromatics S61 is 30 wt%, the return aromatics reduction and aromatics removal rate are tested, and the results are shown in Table 1.

[0191] Example 22

[0192] The rest is the same as Example 19, except that the agent-to-oil ratio of the extractant to the anhydrous reflux aromatic hydrocarbon S61 is 0.75:1.

[0193] When the aromatic content in the anhydrous reflux aromatics S61 is 30 wt%, the return aromatics reduction and aromatics removal rate are tested, and the results are shown in Table 1.

[0194] Example 23

[0195] The rest is the same as Example 19, except that the agent-to-oil ratio of the extractant to the anhydrous reflux aromatic hydrocarbon S61 is 0.5:1.

[0196] When the aromatic content in the anhydrous reflux aromatics S61 is 30 wt%, the return aromatics reduction and aromatics removal rate are tested, and the results are shown in Table 1.

[0197] Example 24

[0198] The rest is the same as Example 19, except that the agent-to-oil ratio of the extractant to the anhydrous reflux aromatic hydrocarbon S61 is 0.25:1.

[0199] When the aromatic content in the anhydrous reflux aromatics S61 is 30 wt%, the return aromatics reduction and aromatics removal rate are tested, and the results are shown in Table 1.

[0200] Example 25

[0201] Other aspects are the same as in Example 7, except that the feedstock oil S1 is a simulated oil with an aromatic content of 25 wt%;

[0202] When the aromatic content in the anhydrous reflux aromatics S61 is 20 wt%, the return aromatics reduction and aromatics removal rate are tested, and the results are shown in Table 1.

[0203] Example 26

[0204] The rest is the same as Example 25, except that the agent-to-oil ratio of the extractant to the anhydrous reflux aromatic hydrocarbon S61 is 1.5:1.

[0205] When the aromatic content in the anhydrous reflux aromatics S61 is 20 wt%, the return aromatics reduction and aromatics removal rate are tested, and the results are shown in Table 1.

[0206] Example 27

[0207] The rest is the same as Example 25, except that the agent-to-oil ratio of the extractant to the anhydrous reflux aromatic hydrocarbon S61 is 1:1.

[0208] When the aromatic content in the anhydrous reflux aromatics S61 is 20 wt%, the return aromatics reduction and aromatics removal rate are tested, and the results are shown in Table 1.

[0209] Example 28

[0210] The rest is the same as Example 25, except that the agent-to-oil ratio of the extractant to the anhydrous reflux aromatic hydrocarbon S61 is 0.75:1.

[0211] When the aromatic content in the anhydrous reflux aromatics S61 is 20 wt%, the return aromatics reduction and aromatics removal rate are tested, and the results are shown in Table 1.

[0212] Example 29

[0213] Other Example 25, except that the agent-to-oil ratio of the extractant to the anhydrous reflux aromatic hydrocarbon S61 is 0.5:1.

[0214] When the aromatic content in the anhydrous reflux aromatics S61 is 20 wt%, the return aromatics reduction and aromatics removal rate are tested, and the results are shown in Table 1.

[0215] Example 30

[0216] The rest is the same as Example 25, except that the agent-to-oil ratio of the extractant to the anhydrous reflux aromatic hydrocarbon S61 is 0.25:1.

[0217] When the aromatic content in the anhydrous reflux aromatics S61 is 20 wt%, the return aromatics reduction and aromatics removal rate are tested, and the results are shown in Table 1.

[0218] Example 31

[0219] Other aspects are the same as in Example 7, except that the agent-to-oil ratio of the extractant to the anhydrous reflux aromatic hydrocarbon S61 is 1:1, and the operating temperature in the static mixer 11 is 20°C.

[0220] When the aromatic content in the anhydrous reflux aromatics S61 is 70 wt%, the return aromatics reduction and aromatics removal rate are tested, and the results are shown in Table 1.

[0221] Example 32

[0222] The rest is the same as Example 31, except that the operating temperature in the static mixer 11 is 40°C.

[0223] When the aromatic content in the anhydrous reflux aromatics S61 is 70 wt%, the return aromatics reduction and aromatics removal rate are tested, and the results are shown in Table 1.

[0224] Example 33

[0225] The rest is the same as Example 31, except that the operating temperature in the static mixer 11 is 60°C.

[0226] When the aromatic content in the anhydrous reflux aromatics S61 is 70 wt%, the return aromatics reduction and aromatics removal rate are tested, and the results are shown in Table 1.

[0227] Example 34

[0228] The rest is the same as Example 31, except that the operating temperature in the static mixer 11 is 80°C.

[0229] When the aromatic content in the anhydrous reflux aromatics S61 is 70 wt%, the return aromatics reduction and aromatics removal rate are tested, and the results are shown in Table 1.

[0230] Example 35

[0231] Other aspects are the same as in Example 1, except that the lean extractant S12 is directly introduced from the top of the distillation tower 2 and is not atomized into small droplets for spraying.

[0232] When the aromatic content in the anhydrous reflux aromatics S61 is 70 wt%, the return aromatics reduction and aromatics removal rate are tested, and the results are shown in Table 1.

[0233] Example 36

[0234] The rest is the same as Example 1, except that the lean extractant S12 is directly withdrawn without being sprayed into the distillation tower 2.

[0235] When the aromatic content in the anhydrous reflux aromatics S61 is 70 wt%, the return aromatics reduction and aromatics removal rate are tested, and the results are shown in Table 1.

[0236] Comparative Example 1

[0237] The rest is the same as Example 1, except that the anhydrous reflux aromatics S61 is directly introduced as return aromatics into the bottom of the extraction tower 1 for extraction, and the anhydrous reflux aromatics S61 in the reflux aromatics storage tank 10 is not introduced into the static mixer 11 to be mixed with the extractant in the static mixer 11 to obtain the agent-oil mixture S10; the agent-oil mixture S10 is introduced into the settling tank 12, and after stratification, the upper extract phase is the return aromatics S11, and the lower extraction phase is the lean extraction agent S12, and the lean extraction agent S12 is atomized into small droplets and sprayed into the distillation tower 2 from the top of the distillation tower 2 for the distillation separation step.

[0238] Table 1

[0239]

[0240]

[0241] From the results in Table 1, it can be seen that the technology of the present invention is used to complete the extraction and phase separation of the oil phase in the reflux aromatics and the extractant in at least one combination consisting of a static mixer and a settling tank, which can increase the raw oil processing capacity of the extraction tower.

[0242] The preferred embodiments of the present invention have been described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, various simple variations of the technical solution of the present invention may be made, including combining the various technical features in any other appropriate manner. These simple variations and combinations should also be regarded as disclosed in the present invention and fall within the scope of protection of the present invention.

Claims

1. A method for reducing the amount of aromatic hydrocarbons recycled in an aromatic hydrocarbon extraction process, characterized in that: The method includes: (1) The crude oil is brought into contact with an extraction solvent for extraction to obtain a first rich agent and a raffinate; (2) distilling and separating the first rich agent to obtain a second rich agent and reflux aromatics; (3) extracting and separating the oil phase in the reflux aromatics and the extractant in at least one combination of a static mixer and a settling tank to obtain reflux aromatics and a lean extractant; (4) returning the returned aromatic hydrocarbons to step (1) and returning the lean extraction agent to step (2); The method further comprises: before step (3), performing oil-water separation on the reflux aromatics in step (2) to obtain an oil phase in the reflux aromatics and a water phase in the reflux aromatics; Each group includes a static mixer and a settling tank. The oil phase in the reflux aromatics is added from the static mixer of the first group and extracted with the extractant in the static mixer to obtain an extractant-oil mixture. The extractant-oil mixture in the static mixer of each group enters the corresponding settling tank for stratification. The raffinate phase on the upper layer of the settling tank flows into the static mixer of the next group to continue extraction with the extractant in the static mixer. The raffinate phase on the upper layer of the settling tank of the last group is the return aromatics. The extract phases on the lower layers of the settling tanks of all groups are combined to form the lean extractant. The agent-oil mass ratio in the static mixer is higher than 0.05:1; The extraction temperature in the static mixer is higher than room temperature; The operating pressure of the extraction in the static mixer is atmospheric pressure.

2. The method according to claim 1, wherein The raw oil is selected from one or more of reformed gasoline, cracked hydrogenated gasoline, naphtha, straight-run gasoline, and catalytic diesel; and / or The content of aromatics in the feed oil is greater than 5 wt%; and / or The extraction solvent is selected from one or more of triethylene glycol, tetraethylene glycol, 2-pyrrolidone, N-methylpyrrolidone, N-ethylpyrrolidone, dimethyl sulfoxide, N-methylformamide, N-methylbenzylamide, N-formylmorpholine, N,N-dimethylformamide, hydrazine hydrate, furfural, ethylene glycol, glycerol formal, polyethylene glycol, and polycarbonate.

3. The method according to claim 2, wherein: The content of aromatics in the raw oil is 10-80 wt%.

4. The method according to claim 1, wherein The mass ratio of agent to oil in the static mixer is 0.1-2:1; and / or The extraction temperature in the static mixer is 20-80°C.

5. The method according to claim 1, wherein In step (4), the method of returning the returned aromatic hydrocarbons to step (1) is: introducing the returned aromatic hydrocarbons into the bottom of the extraction tower extracted in step (1); and / or The method of returning the lean extract to step (2) is as follows: the lean extract is introduced into the top of the distillation tower for distillation separation in step (2).

6. The method according to claim 5, wherein: The method of introducing the lean extractant into the top of the distillation tower for distillation separation in step (2) is: atomizing the lean extractant into small droplets and spraying the droplets into the distillation tower from the top of the distillation tower.

7. The method according to claim 1, wherein The reflux ratio of the return aromatics (0.4-1.3): 1; and / or The method further comprises: contacting the second rich solvent separated in step (2) with stripping steam to perform stripping to obtain a lean solvent and aromatic hydrocarbons.

8. The method according to claim 7, wherein: The reflux ratio of the aromatic hydrocarbons in the return column is (0.4-1):1; and / or The stripping method is as follows: the second rich solvent separated in step (2) is introduced into a stripping tower and brought into contact with stripping steam in the stripping tower for stripping, the lean solvent is produced from the bottom of the stripping tower, and the aromatic hydrocarbons are produced from the top of the stripping tower.

9. The method according to claim 8, wherein The method further comprises: condensing the produced aromatic hydrocarbons and separating water to obtain anhydrous aromatic hydrocarbons; and / or The lean solvent obtained at the bottom of the stripping tower is divided into part A and part B. Part A is returned to the tower for extraction in step (1) as the extraction solvent S2 for extraction, and part B is returned to the static mixer in step (3) for extraction.

10. The method according to claim 9, wherein: The method further comprises: cooling the raffinate oil obtained in step (1) and contacting the raffinate oil with washing water for washing to obtain non-aromatic hydrocarbons and raffinate oil washing water.

11. The method according to claim 10, wherein: The water washing step comprises: introducing the cooled raffinate oil into the water washing tower from the bottom of the water washing tower, introducing the washing water into the water washing tower from the top of the water washing tower, contacting the cooled raffinate oil and the washing water in the water washing tower for washing, and obtaining non-aromatic hydrocarbons and raffinate oil washing water; and the non-aromatic hydrocarbons are extracted as products.

12. A device for reducing the amount of aromatic hydrocarbons recycled in an aromatic hydrocarbon extraction process, characterized in that: The device includes an extraction tower, a stripping tower, a reflux aromatics oil-water separation unit, and an extraction unit; The extraction tower is used to extract the crude oil to obtain the first rich agent and the raffinate oil; The stripping tower is used to distill and separate the first rich agent from the extraction tower to obtain a second rich agent and reflux aromatics; The reflux aromatics oil-water separation unit is used to separate the reflux aromatics from the distillation tower into oil and water to obtain an oil phase in the reflux aromatics and a water phase in the reflux aromatics; The extraction unit comprises at least one combination of a static mixer and a settling tank, wherein the combination of the static mixer and the settling tank is used to extract and separate the oil phase in the reflux aromatic hydrocarbons under the action of an extractant to obtain return aromatic hydrocarbons and a lean extraction agent; The settling tank in each group is connected in series to the static mixer of the next group; The extraction tower comprises a feed oil inlet arranged on the side wall, an extraction solvent inlet on the side wall, a first rich agent outlet at the bottom, a raffinate oil outlet at the top, and a return aromatics inlet on the side wall; The stripping tower comprises a first rich agent inlet arranged on the side wall, a second rich agent outlet at the bottom, a reflux aromatics outlet at the top, and an extraction lean agent inlet at the side wall; The reflux aromatics oil-water separation unit is a reflux aromatics storage tank, which includes a reflux aromatics inlet at the top, a water phase outlet at the bottom, and an anhydrous reflux aromatics oil phase outlet on the side wall; In the combination of at least one group of static mixers and sedimentation tanks, each combination is connected in series in sequence, and the static mixer in each group includes an inlet for the material to be extracted arranged on the side wall, an extractant inlet on the top, and an agent-oil mixture outlet on the side wall; the sedimentation tank includes an inlet for the agent-oil mixture arranged on the side wall, an extract phase outlet on the side wall, and an extraction phase outlet on the side wall.

13. The device according to claim 12, wherein The device further comprises: a stripping tower for contacting the second rich solvent obtained by distillation separation with water vapor for stripping, producing lean solvent from the bottom of the stripping tower and producing aromatic hydrocarbons from the top of the stripping tower; and / or The device also includes: an aromatic hydrocarbon oil-water separation unit for separating the aromatic hydrocarbons produced from the top of the stripping tower into oil and water to obtain anhydrous aromatic hydrocarbons and water; and / or The device further comprises: a water washing tower for washing the raffinate oil obtained by extraction with water to obtain non-aromatic hydrocarbons and raffinate oil washing water; and / or The apparatus further comprises a water storage tank for storing the obtained water and / or providing water for the process.

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