Method for producing chemicals from fuel oil

Abstract

The invention relates to a method for producing chemicals from fuel oil, and the method comprises the following steps: enabling pretreated fuel oil and a desorption agent to enter a simulated moving bed adsorption device to be in contact with an adsorbent for separation to obtain an extract and a raffinate; the desorption agent comprises non-aromatic raffinate oil and low-carbon aromatic hydrocarbon, and the non-aromatic raffinate oil and the low-carbon aromatic hydrocarbon come from an aromatic hydrocarbon combination device; the simulated moving bed adsorption device is provided with at least one stream of washing material, and the washing material comprises the non-aromatic raffinate oil. According to the method, desorption agent materials can be prevented from being purchased, and the cost is reduced; meanwhile, non-aromatic raffinate oil is adopted as a flushing material, the selective pore volume of the adsorbent is not occupied, the use cost of the desorption agent is reduced, the utilization efficiency of the adsorbent is improved, and the yield of aromatic hydrocarbon is further improved.

Description

Technical Field

[0001] The present disclosure relates to the technical field of aromatic hydrocarbon purification, and in particular, to a method for producing chemicals from fuel oil. Background Art

[0002] In recent years, with the rapid development of my country's new energy industry, the growth rate of refined oil consumption has gradually slowed down, especially the consumption of diesel has peaked, the overcapacity problem in the refining industry has become prominent, and the need for transformation is urgent. For fuel oil, gasoline fractions can choose chemical reforming to produce more aromatics; kerosene fractions will have a large demand in the future aviation fuel market. If there is a temporary overcapacity, they can also be transferred to the diesel pool or treated as diesel; diesel fractions can be converted into gasoline fractions or BTX by diesel hydro-modification technology, hydrocracking technology, etc. However, these technologies have problems such as harsh reaction conditions and high energy and material consumption. Unlike traditional fraction refining processes, component refining is an important development direction for the future refining industry. Especially for diesel, if the aromatic components and alkane components in diesel can be separated, and then the aromatic components can be used to produce BTX by hydrocracking or catalytic cracking, and the alkane components can be used to produce low-carbon olefins by thermal cracking, the high-value chemical utilization of the aromatic components and alkane components in the diesel fraction can be achieved, thereby effectively promoting the transformation and development of the refining industry.

[0003] CN111996029A, CN105542835A, CN106187666A, CN105349175A, and CN109022020A disclose some methods for separating aromatics and alkanes using a simulated moving bed process. A four-zone simulated moving bed process is used, and the adsorbent is mostly molecular sieve, silica, or alumina, and the desorbent is cyclohexane, methylcyclohexane, xylene, toluene, etc., to achieve separation of alkane and aromatic components in diesel.

[0004] CN106244225A discloses a simulated moving bed adsorption separation method for realizing efficient separation of heavy aromatics. The simulated moving bed process is used to realize the separation of aromatics and non-aromatics in C9+ aromatic feedstock. Through efficient matching of the adsorption bed, the separation of monocyclic aromatics and polycyclic aromatics, and the separation of paraffins and cycloparaffins can also be realized.

[0005] CN110938458A discloses a method for producing high-quality white oil. The method produces high-quality white oil through three process units: raw material pretreatment, simulated moving bed aromatic adsorption separation, and desorbent distillation recovery. The method uses a surface functionalized modified mesoporous silica adsorbent to produce high-quality white oil with an aromatic content of less than 5% by mass. This method not only broadens the aromatic content of the raw materials, but can also be applied to raw materials with low aromatic content and high aromatic content.

[0006] CN105368482A discloses a method for removing polycyclic aromatic hydrocarbons from diesel by multi-tower parallel adsorption. Activated carbon, oxides or metal-modified materials are used as adsorbents. The diesel after impurities are removed is passed into a multi-tower parallel adsorption device to adsorb and separate polycyclic aromatic hydrocarbons in the diesel. The removal rate of polycyclic aromatic hydrocarbons can reach 80%.

[0007] CN113372953A discloses a method for separating saturated hydrocarbons and unsaturated hydrocarbons by adsorption of FCC gasoline. The method separates FCC gasoline into an alkane-rich component and an aromatics-rich component by simulating a moving bed process, wherein the alkane component is a high-quality raw material for ethylene cracking, and the aromatics component is returned to the catalytic cracking unit to produce gasoline or to obtain BTX after hydrogenation and extraction.

[0008] The desorbent used in the above-mentioned adsorption separation process is mainly a compound of aromatic hydrocarbons and single-component or multi-component alkanes. As is well known, in the process of separating the desorbent in the extract tower and the residual liquid tower, a very small amount of desorbent components will be lost. In order to adjust the desorbent ratio, a single component needs to be supplemented in a targeted manner, resulting in an increase in separation costs. In addition, the existing process usually uses desorbent or extract as a flushing stream, and these components will occupy the selective pore volume of the adsorbent, the utilization rate of the adsorbent decreases, and the separation performance of the adsorbent decreases. Summary of the invention

[0009] The purpose of the present invention is to provide a method for producing chemical products from fuel oil. The method can avoid purchasing desorbent materials and reduce costs; at the same time, it improves the utilization efficiency of the adsorbent, increases the aromatic content in the extracted liquid, reduces the aromatic content in the residual liquid, and further improves the aromatic yield.

[0010] In order to achieve the above object, the present disclosure provides a method for producing chemicals from fuel oil, the method comprising the following steps:

[0011] The pretreated fuel oil and desorbent are allowed to enter the simulated moving bed adsorption device, contact with the adsorbent for separation, and obtain an extract and a raffinate;

[0012] The desorbent includes non-aromatic raffinate oil and low-carbon aromatic hydrocarbons, and the non-aromatic raffinate oil and the low-carbon aromatic hydrocarbons come from an aromatics complex;

[0013] The simulated moving bed adsorption device is provided with at least one flushing material, and the flushing material includes the non-aromatic raffinate oil.

[0014] Optionally, based on the weight of the non-aromatic raffinate oil, the non-aromatic raffinate oil comprises 15-30% normal alkanes, 50-80% cycloalkanes and 5-15% isoparaffins;

[0015] The low-carbon aromatic hydrocarbons are C6-C8 aromatic hydrocarbons selected from one or more of benzene, toluene and xylene.

[0016] Optionally, in the desorbent, the mass ratio of the low-carbon aromatic hydrocarbons to the non-aromatic raffinate oil is 0.3 to 3:1, preferably 0.5 to 1.5:1.

[0017] Optionally, the initial boiling point of the fuel oil is 90-110°C, and the final boiling point is 390-410°C;

[0018] The non-aromatic raffinate oil has an initial distillation point of 40 to 70°C, preferably 55 to 70°C, and a final distillation point of 110 to 160°C, preferably 110 to 130°C.

[0019] Optionally, the simulated moving bed adsorption device is a single adsorption tower, wherein 10 to 16 adsorption beds are arranged in the adsorption tower, and the inlet of the flushing material is arranged at 1 to 2 adsorption beds downstream of the extract; the adsorbent is filled in the adsorption tower, and the adsorbent is silica;

[0020] The BET specific surface area of ​​the silicon dioxide is 500 to 800 m 2 / g, a pore size of 1 to 10 nm, and a mass reduction of less than 5 mass % when the silicon dioxide is calcined at 600°C.

[0021] Optionally, the method further comprises: pre-treating the fuel oil to obtain pre-treated fuel oil;

[0022] The pretreatment is carried out in a fixed bed; the fixed bed is filled with a protective agent, and the protective agent is selected from one or more of silicon dioxide, metal oxides, molecular sieves, highly active clay and activated carbon.

[0023] Optionally, the pretreatment conditions include: operating pressure of 0.1-1 MPa, adsorption temperature of 50-150°C, and air velocity of 0.1-40 h -1 .

[0024] Optionally, the method further includes: sending the extract into an extract tower for separation to obtain an aromatic-rich component and a first regenerated desorbent; cracking the aromatic-rich component to obtain low-carbon aromatics; the cracking treatment includes one or more of catalytic cracking and hydrocracking processes; and returning the first regenerated desorbent to the simulated moving bed adsorption device for recycling as a desorbent.

[0025] Optionally, the method further includes: sending the raffinate into a raffinate tower for separation to obtain an alkane-rich component and a second regenerated desorbent; performing thermal cracking on the alkane-rich component to obtain light olefins; and returning the second regenerated desorbent to the simulated moving bed adsorption device for recycling as a desorbent.

[0026] Optionally, the operating conditions of the simulated moving bed include: adsorption and desorption temperatures of 70 to 120° C., raw material injection temperature of 70 to 120° C., desorbent injection temperature of 100 to 130° C., and step switching time of 240 to 480 s.

[0027] Through the above technical scheme, the method disclosed in the present invention uses the non-aromatic raffinate oil produced as a by-product of the aromatics complex as a desorbent to compound alkanes, thereby avoiding the need to purchase desorbent materials and reducing costs; at the same time, the non-aromatic raffinate oil is used as a flushing material, which does not occupy the selective pore volume of the adsorbent, thereby reducing the cost of using the desorbent and improving the utilization efficiency of the adsorbent, thereby increasing the aromatic content in the extracted liquid, reducing the aromatic content in the raffinate, and further improving the aromatic yield.

[0028] Other features and advantages of the present disclosure will be described in detail in the following detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] The accompanying drawings are used to provide a further understanding of the present disclosure and constitute a part of the specification. Together with the following specific embodiments, they are used to explain the present disclosure but do not constitute a limitation of the present disclosure. In the accompanying drawings:

[0030] Figure 1 The invention discloses a process diagram of a method for producing chemical products from fuel oil.

[0031] Figure 2 The present invention discloses a simplified diagram of the positions of material inlet and outlet of a simulated moving bed. DETAILED DESCRIPTION

[0032] The specific implementation of the present disclosure is described in detail below in conjunction with the accompanying drawings. It should be understood that the specific implementation described herein is only used to illustrate and explain the present disclosure, and is not used to limit the present disclosure.

[0033] The present disclosure provides a method for producing chemicals from fuel oil, the method comprising the following steps:

[0034] The pretreated fuel oil and desorbent are allowed to enter the simulated moving bed adsorption device, contact with the adsorbent for separation, and obtain an extract and a raffinate;

[0035] The desorbent includes non-aromatic raffinate oil and low-carbon aromatic hydrocarbons, and the non-aromatic raffinate oil and the low-carbon aromatic hydrocarbons come from an aromatics complex;

[0036] The simulated moving bed adsorption device is provided with at least one flushing material, and the flushing material includes the non-aromatic raffinate oil.

[0037] The method disclosed herein uses the non-aromatic raffinate oil produced as a byproduct of the aromatics complex as a desorbent to compound alkanes, thereby avoiding the need to purchase desorbent materials and reducing costs; at the same time, the non-aromatic raffinate oil is used as a flushing material, which does not occupy the selective pore volume of the adsorbent, thereby reducing the cost of using the desorbent and improving the utilization efficiency of the adsorbent, increasing the aromatic content in the extracted liquid, reducing the aromatic content in the raffinate, and further improving the aromatic yield. The method disclosed herein produces alkane components and aromatic components from fuel oil, which are used to increase the production of low-carbon olefins and low-carbon aromatics, respectively, and provides an optional technical path for realizing the transformation from oil refining to chemical industry.

[0038] According to one embodiment of the present disclosure, based on the weight of the non-aromatic raffinate oil, the non-aromatic raffinate oil includes 15-30% of normal alkanes, 50-80% of cycloalkanes and 5-15% of isoparaffins, the normal alkanes may be one or more of normal hexane, normal heptane and normal octane, the cycloalkanes may be one or more of methylcyclopentane, cyclopentane, cyclohexane, methylcyclohexane, 1,2-dimethylcyclohexane and 1,3-dimethylcyclohexane, the isoparaffins may be one or more of isooctane, 2-methylpentane and 2,2-dimethylbutane; the low-carbon aromatics are C6-C8 aromatics selected from one or more of benzene, toluene and xylene.

[0039] According to an embodiment of the present disclosure, in the desorbent, the mass ratio of the low-carbon aromatic hydrocarbons to the non-aromatic raffinate oil is 0.3 to 3:1, preferably 0.5 to 1.5:1.

[0040] According to one embodiment of the present disclosure, the initial boiling point of the fuel oil is 90-110°C, and the final boiling point is 390-410°C;

[0041] The non-aromatic raffinate oil has an initial distillation point of 40 to 70°C, preferably 55 to 70°C, and a final distillation point of 110 to 160°C, preferably 110 to 130°C.

[0042] According to one embodiment of the present disclosure, the method further includes: pre-treating the fuel oil to obtain pre-treated fuel oil; the pre-treatment is carried out in a fixed bed; a protective agent is loaded in the fixed bed, and the protective agent is selected from one or more of silica, metal oxides, molecular sieves, highly active clay and activated carbon. In one embodiment, the fuel oil can be fuel oil from an atmospheric distillation tower, a vacuum distillation tower, or a fuel oil from a catalytic cracking unit, a reforming unit, a hydrocracking unit and a coking unit. The pre-treatment includes removing highly polar components in the fuel oil, such as one or more of water, colloid, condensed ring sulfur and condensed ring nitrogen impurities.

[0043] According to one embodiment of the present disclosure, the pretreatment conditions include: an operating pressure of 0.1 to 1 MPa, an adsorption temperature of 50 to 150°C, and an air velocity of 0.1 to 40 h -1 .

[0044] According to one embodiment of the present disclosure, the simulated moving bed adsorption device is a single adsorption tower, and 10 to 16 adsorption beds are arranged in the adsorption tower, preferably 11 to 14 adsorption beds, and an adsorbent is loaded in each of the adsorption beds; the adsorbent is loaded in the adsorption tower, and the adsorbent is silica.

[0045] According to one embodiment of the present disclosure, the BET specific surface area of ​​the silicon dioxide is 500 to 800 m 2 / g, preferably 600 to 700 m 2 / g; the pore diameter is 1 to 10 nm, preferably 1.5 to 6.5 nm, and the mass reduction of the silica is less than 5 mass% when calcined at 600°C.

[0046] According to one embodiment of the present disclosure, the simulated moving bed includes a desorption zone, a purification zone, an adsorption zone and a buffer zone; the raw material, desorbent, extract, and raffinate enter and exit the adsorption tower at specific positions, the desorption zone is between the desorbent introduction and the extract outlet, the purification zone is between the extract outlet and the raw material introduction, the adsorption zone is between the raw material introduction and the raffinate outlet, and the buffer zone is between the raffinate outlet and the desorbent introduction; the inlet of the flushing material is set at 1 to 2 adsorption beds downstream of the extract; the flushing flow includes non-aromatic raffinate oil. In one embodiment, the adsorption bed partitions can be set to 2 to 5 beds in the adsorption zone, 3 to 5 beds in the purification zone, 2 to 5 beds in the desorption zone, and 1 to 3 beds in the buffer zone. The present disclosure does not impose any special restrictions on the flushing ratio. For example, the flushing amount can be adjusted according to the purity requirements of the actual product. The above-mentioned implementation method is conducive to avoiding the influence of residual materials in the pipeline on the purity and yield of the aromatic hydrocarbon product, while not occupying the selective pore volume of the adsorbent, reducing the cost of using the desorbent, improving the utilization efficiency of the adsorbent, further increasing the aromatic hydrocarbon content in the extract, and reducing the aromatic hydrocarbon content in the residual liquid.

[0047] According to one embodiment of the present disclosure, the method further includes: sending the extract to an extract tower for separation to obtain an aromatic-rich component and a first regenerated desorbent; cracking the aromatic-rich component to obtain low-carbon aromatics; the cracking treatment includes one or more of catalytic cracking and hydrocracking processes; and returning the first regenerated desorbent to the simulated moving bed adsorption device for recycling as a desorbent.

[0048] According to one embodiment of the present disclosure, the method further includes: sending the raffinate into a raffinate tower for separation to obtain an alkane-rich component and a second regenerated desorbent; performing thermal cracking treatment on the alkane-rich component to obtain light olefins; and returning the second regenerated desorbent to the simulated moving bed adsorption device for recycling as a desorbent.

[0049] According to one embodiment of the present disclosure, the first regenerated desorbent and the second regenerated desorbent are added to a desorbent buffer tank, and then low-carbon aromatic hydrocarbons or non-aromatic raffinate oil are added for recycling.

[0050] According to one embodiment of the present disclosure, the operating conditions of the simulated moving bed include: adsorption and desorption temperatures of 70 to 120°C, preferably 90 to 110°C; raw material injection temperature of 70 to 120°C, preferably 80 to 100°C; desorbent injection temperature of 100 to 130°C, preferably 100 to 120°C; step switching time of 240 to 480s, preferably 300 to 360s.

[0051] The method of the present invention is further described with the following examples, but the present invention is not limited thereto.

[0052] In the present disclosure, the components of the extract and the raffinate are determined using the NB / SH / T 0606 method.

[0053] Comparative Example 1

[0054] The fuel oil raw material processed is a typical diesel fraction of a refinery, and the composition is shown in Table 1. The aromatic content is 20.6% by mass. The raw material first enters a fixed bed protection tower, which is filled with molecular sieve adsorbent. The operating pressure of the fixed bed protection tower is 0.8 MPa, the operating temperature is 60°C, and the air velocity is 1h -1 , and obtain the pretreated fuel oil.

[0055] like Figure 1 As shown, fuel oil enters the simulated moving bed in the fourth zone, and a desorbent is introduced. The desorbent used is a mixture of toluene and methylcyclohexane, with a toluene mass fraction of 50%. The flushing material used is the desorbent. The raw material processing capacity is 438g / h, the desorbent feed rate is 780g / h, the extraction liquid flow rate is 334g / h, the flushing flow rate is 18g / h, and the residual liquid is calculated by material balance, which is about 902g / h.

[0056] After the diesel raw material is separated by adsorption, an extract E rich in aromatic components and a raffinate R rich in alkane components are obtained. The extract E and the raffinate R are recycled after passing through a distillation tower and the desorbent is separated. The four-zone simulated moving bed contains 12 beds, which are divided into a desorption zone, a purification zone, an adsorption zone and a buffer zone. The bed configuration of each zone is 3-4-3-2. Each bed is evenly loaded with silica adsorbent. The adsorption and desorption temperature is 100°C, the raw material injection temperature is 90°C, the desorbent injection temperature is 110°C, and the step switching time is 320s. The mass composition of hydrocarbons in the extract and the raffinate is shown in Table 1.

[0057] Aromatic purity = mass of aromatics in the extract / total mass of the extract × 100%;

[0058] Aromatic yield = mass of aromatics in the extract / mass of aromatics in the feed × 100% = X E (X F -X R ) / (X F (X E -X R )).

[0059] Example 1

[0060] The alkanes and aromatics in diesel were separated according to the method of Comparative Example 1, except that the desorbent used was a mixture of toluene and non-aromatic raffinate oil, and the flushing stream used was non-aromatic raffinate oil; the mass ratio of toluene and non-aromatic raffinate oil was 1:1, toluene and non-aromatic raffinate oil came from an aromatics complex, the composition of non-aromatic raffinate oil is shown in Table 2, and the mass composition of hydrocarbons in the extract and raffinate is shown in Table 1.

[0061] Table 2

[0062] Components of non-aromatic raffinate oil Mass content / % n-Hexane 27.89 Methylcyclopentane 32.32 Cyclopentane 11.38 Cyclohexane 8.15 Methylcyclohexane 9.37 Isooctane 10.88 total 100

[0063] Example 2

[0064] The alkanes and aromatics in diesel were separated according to the method of Comparative Example 1, except that the desorbent used was a mixture of toluene and non-aromatic raffinate oil in a mass ratio of 3:7, and the flushing stream used was non-aromatic raffinate oil. The mass composition of hydrocarbons in the extract and the raffinate is shown in Table 1.

[0065] Example 3

[0066] The alkanes and aromatics in diesel were separated according to the method of Comparative Example 1, except that the desorbent used was a mixture of toluene and non-aromatic raffinate oil in a mass ratio of 2:1, and the flushing stream used was non-aromatic raffinate oil. The mass composition of hydrocarbons in the extract and the raffinate is shown in Table 1.

[0067] Table 1

[0068]

[0069]

[0070] According to the data in Table 1, by comparing Example 1 with Comparative Example 1, it can be known that, relative to Comparative Example 1, toluene and methylcyclohexane are used as desorbents and desorbents are used as flushing materials, Example 1 uses low-carbon aromatics and non-aromatic raffinate oil as desorbents and non-aromatic raffinate oil as flushing materials. Under similar operating conditions, the aromatic content in the extract increases slightly from 98.1% to 98.4%, the aromatic content in the raffinate decreases significantly from 5.5% to 3.0%, and the aromatic yield increases from 77.65% to 88.12%. It is shown that the desorbent uses composite non-aromatic raffinate oil and low-carbon aromatics to improve the desorption capacity of the desorbent, and the use of non-aromatic raffinate oil for flushing reduces the total aromatic content in the adsorption tower relative to the use of desorbent, increases the utilization efficiency of the adsorbent, and further improves the aromatic yield. By comparing Example 1 and Example 3, it can be seen that within the preferred mass ratio range of low-carbon aromatics to the non-aromatic raffinate oil disclosed in the present invention, the desorption capacity of the desorbent can be further improved, the utilization efficiency of the adsorbent can be increased, and the yield of aromatics can be improved.

[0071] Comparative Example 2

[0072] The diesel feedstock in Comparative Example 1 was directly fed into the thermal cracking device, the cracking temperature was 750°C, the feed pipe pressure of the cracking furnace was 0.02MPa, the feed rate was 30g / h, the steam rate was 15g / h, the single-pass operation time of the cracking furnace was 6h, and the product distribution is shown in Table 3.

[0073] Example 4

[0074] The raffinate oil in Example 1 was sent to a thermal cracking device, and the thermal cracking operating conditions were the same as those in Comparative Example 2. The product distribution is shown in Table 3.

[0075] Table 3

[0076] Components Comparative Example 2 / wt% Example 4 / wt% hydrogen 0.69 0.81 Methane 9.66 10.88 Ethylene 24.52 31.55 Propylene 14.12 15.55 Mixed C4 11.12 11.1 other 39.89 30.11 sum 100 100

[0077] According to the data in Table 3, by comparing Comparative Example 2 with Example 4, it can be seen that after the diesel feedstock is separated by adsorption, the alkane component is sent to the thermal cracking device. Compared with the diesel feedstock directly sent to the thermal cracking device, the proportion of ethylene in the cracking product is increased by about 7%. This shows that the method disclosed in the present invention can further improve the ethylene yield by separating the alkane component in the diesel and sending it to the ethylene thermal cracking device.

[0078] The preferred embodiments of the present disclosure are described in detail above in conjunction with the accompanying drawings; however, the present disclosure is not limited to the specific details in the above embodiments. Within the technical concept of the present disclosure, a variety of simple modifications can be made to the technical solution of the present disclosure, and these simple modifications all fall within the protection scope of the present disclosure.

[0079] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, the present disclosure will not further describe various possible combinations.

[0080] In addition, various embodiments of the present disclosure may be arbitrarily combined, and as long as they do not violate the concept of the present disclosure, they should also be regarded as the contents disclosed by the present disclosure.

Claims

1. A method for producing chemicals from fuel oil, characterized in that: The method comprises the following steps: The pretreated fuel oil and desorbent are allowed to enter the simulated moving bed adsorption device, contact with the adsorbent for separation, and obtain an extract and a raffinate; The desorbent includes non-aromatic raffinate oil and low-carbon aromatic hydrocarbons, and the non-aromatic raffinate oil and the low-carbon aromatic hydrocarbons come from an aromatics complex; The simulated moving bed adsorption device is provided with at least one flushing material, and the flushing material includes the non-aromatic raffinate oil.

2. The method according to claim 1, wherein: Based on the weight of the non-aromatic raffinate oil, the non-aromatic raffinate oil comprises 15-30% normal alkanes, 50-80% cycloalkanes and 5-15% isoparaffins; The low-carbon aromatic hydrocarbons are C6-C8 aromatic hydrocarbons selected from one or more of benzene, toluene and xylene.

3. The method according to claim 1, wherein: In the desorbent, the mass ratio of the low-carbon aromatic hydrocarbons to the non-aromatic raffinate oil is 0.3 to 3:1, preferably 0.5 to 1.5:

1.

4. The method according to claim 1, wherein: The initial boiling point of the fuel oil is 90-110°C, and the final boiling point is 390-410°C; The non-aromatic raffinate oil has an initial distillation point of 40 to 70°C, preferably 55 to 70°C, and a final distillation point of 110 to 160°C, preferably 110 to 130°C.

5. The method according to claim 1, wherein: The simulated moving bed adsorption device is a single adsorption tower, which is provided with 10 to 16 adsorption beds, and the inlet of the flushing material is arranged at 1 to 2 adsorption beds downstream of the extract; the adsorbent is filled in the adsorption tower, and the adsorbent is silicon dioxide; The BET specific surface area of ​​the silicon dioxide is 500 to 800 m 2 / g, a pore size of 1 to 10 nm, and a mass reduction of less than 5 mass % when the silicon dioxide is calcined at 600°C.

6. The method according to claim 1, wherein: The method further comprises: pre-treating the fuel oil to obtain pre-treated fuel oil; The pretreatment is carried out in a fixed bed; the fixed bed is filled with a protective agent, and the protective agent is selected from one or more of silicon dioxide, metal oxides, molecular sieves, highly active clay and activated carbon.

7. The method according to claim 6, wherein: The pretreatment conditions include: operating pressure of 0.1-1 MPa, adsorption temperature of 50-150°C, space velocity of 0.1-40 h -1 .

8. The method according to claim 1, wherein: The method also includes: sending the extract to an extract tower for separation to obtain an aromatic-rich component and a first regenerated desorbent; cracking the aromatic-rich component to obtain low-carbon aromatics; the cracking treatment includes one or more of catalytic cracking and hydrocracking processes; and returning the first regenerated desorbent to the simulated moving bed adsorption device for recycling as a desorbent.

9. The method according to claim 1, wherein: The method further comprises: sending the raffinate into a raffinate tower for separation to obtain an alkane-rich component and a second regenerated desorbent; performing thermal cracking treatment on the alkane-rich component to obtain light olefins; and returning the second regenerated desorbent to the simulated moving bed adsorption device for recycling as a desorbent.

10. The method according to claim 1, wherein: The operating conditions of the simulated moving bed include: adsorption and desorption temperatures of 70 to 120° C., raw material injection temperature of 70 to 120° C., desorbent injection temperature of 100 to 130° C., and step switching time of 240 to 480 seconds.

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