CN115895722A - A system for producing light aromatics from heavy oil raw materials - Google Patents

Abstract

A heavy oil raw material prepares the light aromatic system, it is the reprocessing of the inferior diesel oil in the petroleum refining field, including double lift pipe catalytic cracking unit, main fractionating tower, vice fractionating tower, main cut fractionating tower and vice cut fractionating tower, heavy oil raw material is once catalytic cracking-fractionating in the main fractionating tower-cut in the main cut fractionating tower in the heavy oil lift pipe sequentially and form light fraction and heavy fraction, heavy fraction mix with light fraction and send into the second lift pipe to carry on the second catalytic cracking after the first hydrogenation in the main hydrogenation reactor, the gasohol component that the second cracking produces hydrogenates and enters the cut in the vice cut fractionating tower for the cut in the second hydrogenation, separate light component and heavy fraction, the heavy fraction is sent into the aromatic combination unit finally, separate three kinds of products; in the whole system, secondary catalytic cracking and secondary hydrogenation are required to be carried out on the poor-quality diesel oil, so that the hydrogenation pressure is reduced, the hydrogen consumption is obviously reduced, and the yield of C6-C9 aromatic hydrocarbons in a final product can reach over 50 wt%.

Description

A system for producing light aromatics from heavy oil raw materials

technical field

The invention relates to the reprocessing of heavy oil raw materials in the field of petroleum refining, in particular to a system for preparing light aromatics from heavy oil raw materials.

Background technique

Heavy oil raw materials refer to oils with a distillation range greater than 350°C. The existing treatment methods generally use catalytic cracking in a catalytic cracking unit to produce diesel. However, the market share of diesel has not changed much in recent years, resulting in diesel structure. Correspondingly, benzene, toluene, and xylene BTX in aromatic hydrocarbons are basic organic chemical raw materials in the petrochemical industry. They can be used to produce various chemical products such as synthetic rubber, synthetic fibers, and synthetic resins, and can also be used to produce a variety of fine Chemical products, the market demand for BTX is increasing.

The annual output of low-cetane low-quality diesel LCO in my country exceeds 10Mt, and it is becoming more and more difficult to use it as a vehicle diesel blending component. The investment in the hydro-upgrading unit is quite huge. How to use LCO to produce high value-added light aromatics and gasoline has certain development significance.

At present, research institutions at home and abroad mainly process low-quality diesel oil through hydrocracking, solvent extraction, hydrogenation-reforming and hydrogenation-catalysis to produce aromatics or gasoline:

CN 103214332 discloses a method for producing light aromatic hydrocarbons and high-quality oil products by catalytic cracking diesel oil, in which the catalytic cracking diesel oil is extracted with a solvent to obtain extracted oil rich in polycyclic aromatic hydrocarbons and raffinate oil rich in alkanes , the extracted oil is subjected to hydrorefining and hydrocracking under hydrogenation reaction conditions to produce light aromatics and high-octane gasoline fractions; this method can by-produce diesel oil with high cetane number while obtaining light aromatics and high-octane gasoline, but this method has low diesel utilization rate and low value of by-products.

CN 105542849 discloses a method for producing clean diesel oil and light aromatics from inferior diesel oil. In this method, sulfur nitrogen compounds, olefins and colloids are removed after medium and low pressure hydrogenation of inferior diesel oil to obtain hydrogenated refined diesel oil. The refined diesel oil is simulated Moving bed adsorption separation removes aromatics and sulfides to obtain clean diesel oil and heavy aromatics. Heavy aromatics enter the lightening reactor and undergo hydrogenation reaction at medium and low pressure to generate BTX light aromatics, gasoline components and a small amount of light hydrocarbons; The process of producing clean diesel and light aromatics from inferior diesel provided by the method can process catalytic cracking diesel and coked diesel, and the components of clean diesel and gasoline can meet the National V standard, and at the same time, BTX light aromatics will be produced by-product, but the process is relatively long. The depth of conversion is low.

CN106753551A discloses a method for producing high-octane gasoline by catalytic cracking diesel oil. In this method, after hydrogenation and refining of catalytic diesel oil, it is cut into fractions less than 280°C and fractions greater than 280°C. Fractions greater than 280°C are extracted by aromatics. The extracted raffinate is sent to the catalytic cracking unit together with the fraction below 280°C to produce high-octane gasoline, and the extracted oil rich in aromatics is used for aromatics utilization; in this method, HLCO contains a large amount of bicyclic and tricyclic aromatics without adding Utilize, directly produce device, overall economic benefit is relatively poor.

To sum up, among the existing methods for processing low-quality diesel oil to obtain aromatics or gasoline, the hydrocracking process can produce high-quality catalytic reforming raw materials and improve the quality of diesel oil, but the investment is obviously large; the solvent extraction process can improve the properties of low-quality diesel oil , but the utilization of extracted aromatics needs to be further studied and discussed; the hydrogenation-reforming LCO-XTM combined process can only process a small amount of LCO light fractions, which is not suitable for large-scale processing; The effect is good, but if the hydrorefining LCO is blended when processing the catalytic raw material oil, it will obviously affect the cracking and treatment capacity of the raw material oil, and this operation mode cannot produce BTX products.

Contents of the invention

In order to solve the problem of high processing cost in the existing technology of using diesel oil to produce light aromatics, the present invention provides a system for producing light aromatics from heavy oil raw materials, which directly uses the existing catalytic cracking unit to directly produce light aromatics from heavy oil raw materials. The existing equipment is utilized to the greatest extent, while the production cost is reduced, the hydrogen consumption is greatly reduced, the yield of C6-C9 light aromatics is increased, and the yield of diesel oil is reduced.

The technical scheme adopted by the present invention in order to solve the above-mentioned technical problems is: a system for producing light aromatics from heavy oil raw materials, including a double riser catalytic cracking unit, a main fractionation tower, an auxiliary fractionation tower, a main cutting fractionation tower and an auxiliary cutting fractionation tower, The reaction oil gas produced by the heavy oil riser of the double riser catalytic cracking unit is sent to the main fractionation tower for fractionation through the reaction oil gas pipeline I, and the catalytic cracking diesel produced by the fractionation of the main fractionation tower is sent to the main cutting fractionation tower through the catalytic cracking diesel pipeline Cutting, the produced light fraction I is sent to the return pipeline through the light fraction main line, and the produced heavy fraction I is sent to the main hydrogenation reactor through the heavy fraction main line for primary hydrogenation, and the hydrogenated catalytic diesel produced is also sent to the main hydrogenation reactor. mixed with light fraction I and sent to the second riser of the double riser catalytic cracking unit for secondary cracking reaction;

The reaction oil gas produced by the secondary cracking reaction is sent to the sub-fractionator for secondary fractionation through the reaction oil gas pipeline II, and the gasoline component produced enters the main gasoline pipeline, and the rich gas and sewage are separated by the oil gas separator I and then sent to the Secondary hydrogenation in the auxiliary hydrogenation reactor, and then sent to the auxiliary cutting fractionation tower for cutting, the produced light fraction II is discharged through the light aromatics pipeline to the tank farm for blending gasoline, and the produced heavy fraction II is passed through the heavy fraction auxiliary pipeline It is sent to the aromatics complex to produce C6-C9 light aromatics products, raffinate gasoline products and heavy aromatics products.

As an optimization scheme for the above-mentioned system of producing light aromatics from heavy oil raw materials, the gasoline components produced by the fractionation of the main fractionation tower are passed into the oil-gas separator II, and after the rich gas and sewage are separated, they are sent to the absorption tower through the auxiliary gasoline pipeline .

As another optimization scheme for the above-mentioned heavy oil raw material production system of light aromatics, the diesel fraction produced by secondary fractionation in the secondary fractionator is sent to the main cutting fractionator after being combined with the diesel pipeline and catalytic cracking diesel pipeline.

As another optimization scheme for the above-mentioned heavy oil raw material production system of light aromatics, the heavy oil slurry produced by the fractionation of the main fractionation tower is divided into two paths through the circulation pipeline, one path is returned to the main fractionation tower, and the other path is passed through the heavy oil pipeline Ⅰ is sent to the auxiliary fractionation column.

As another optimization scheme for the above-mentioned heavy oil raw material production system of light aromatics, the heavy oil produced by secondary fractionation in the secondary fractionator is sent back to the circulation line of the main fractionator through the heavy oil pipeline II.

As another optimized scheme for the above-mentioned heavy oil raw material production system of light aromatics, the reaction temperature in the heavy oil riser is 480-530°C, the solvent-oil ratio is 4-8, the reaction pressure is 0.12-0.38MPa, and the reaction time is 2.2 ～4.5s, the atomized water vapor is 4～8wt% of the feed amount.

As another optimization scheme for the above-mentioned heavy oil raw material production system of light aromatics, the feed temperature of the main fractionation tower is 480-530°C, the temperature at the bottom of the tower is 350-420°C, the temperature at the top of the tower is 80-150°C, and the pressure at the top of the tower is 0.01 ~0.3MPa.

As another optimization scheme for the above-mentioned heavy oil raw material to produce light aromatics system, in the main cutting fractionation tower, the feed temperature is 220-320°C, the tower bottom temperature is 100-350°C, the tower top temperature is 90-150°C, and the tower top The pressure is 0.01-1MPa, light fraction I is obtained from the top of the tower, and heavy fraction I is obtained from the bottom of the tower.

As another optimization scheme for the above-mentioned heavy oil raw material production system of light aromatics, in the main hydrogenation reactor, the reaction temperature of the primary hydrogenation is 320-390°C, the hydrogen partial pressure is 5.0-10.0MPa, and the volume space velocity is 0.5～1.5h-1, hydrogen/oil volume ratio is 300～800:1.

As another optimization scheme for the above-mentioned heavy oil raw material production system of light aromatics, the reaction temperature for the secondary cracking reaction in the second riser is 560-630°C, the solvent-to-oil ratio is 9-13, and the reaction pressure is 0.12-0.38 MPa, the reaction time is 2.2-4.5s, and the atomized water vapor accounts for 1.2-3.5wt% of the feed amount.

As another optimization scheme for the above-mentioned heavy oil raw material to produce light aromatics system, the feed temperature of the auxiliary fractionation column is 450-530°C, the bottom temperature is 250-350°C, the tower top temperature is 80-150°C, and the tower top pressure is 0.01 ~0.3 MPa.

As another optimization scheme for the above-mentioned heavy oil raw material to produce light aromatics system, in the secondary hydrogenation reactor, the reaction temperature of the secondary hydrogenation is 300-420°C, the hydrogen partial pressure is 2.5-3.5MPa, and the hydrogen/oil The volume ratio is 500-800:1, and the volume space velocity is 1.5-4h-1.

As another optimization scheme for the above-mentioned heavy oil raw material to produce light aromatics system, the feed temperature of the auxiliary cutting fractionation tower is 50-90°C, the bottom temperature is 100-150°C, the tower top temperature is 40-80°C, and the tower top pressure is 0.01～0.3MPa.

As another optimization scheme for the above-mentioned heavy oil raw material production system of light aromatics, in the aromatics complex, the temperature at the top of the extraction tower used for aromatics extraction is 130-190° C., and the pressure is 1.0-2.0 MPa.

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

1) The present invention maximizes the use of existing hydrogenation equipment and catalytic cracking units, reducing the investment and operating costs of the equipment. The heavy oil raw material is first catalytically cracked in the heavy oil riser, and then fractionated in the main fractionator to remove the gasoline fraction and Catalytic cracking diesel fraction, catalytic cracking diesel oil is cut in the main cutting fractionator to form light fraction and heavy fraction, and the heavy fraction is hydrogenated once in the main hydrogenation reactor, mixed with light fraction and sent to the second riser for secondary Catalytic cracking, at this time, the reaction oil gas is fractionated to gasoline and diesel in the sub-fractionator, the diesel component is returned to the main cutting fractionator to continue the reaction, and the gasoline component is hydrogenated after the secondary hydrogenation reaction in the sub-hydrogenation reactor. It enters the secondary cutting fractionation tower for cutting, and separates light fraction and heavy fraction. The heavy fraction is finally sent to the aromatics complex to separate three products: light aromatics, raffinate and heavy aromatics; in the whole system, it is necessary to catalyze heavy oil The diesel produced by cracking is subjected to secondary catalytic cracking and secondary hydrogenation, which not only reduces the pressure of hydrogenation, but also significantly reduces hydrogen consumption (compared with the technology of producing BTX raw materials by hydrocracking, the hydrogen consumption of this process can be reduced from more than 4wt% to 2.0wt%, while the hydrogenation pressure can be reduced from 12MPa to about 7MPa), and the yield of C6-C9 aromatics in the final product can reach more than 50wt%;

2) In the present invention, the low-quality diesel oil produced by catalytic cracking of heavy oil is separated into two parts: "saturated hydrocarbons + single-ring aromatics" and bicyclic and above aromatics, and bicyclic and above aromatics are produced by hydrogenation process to produce single-ring aromatics. Hydrocarbons and single-ring aromatics circulate in the hydrogenation unit, resulting in increased hydrogen consumption of the unit. On the other hand, the hydrogenation and saturation of bicyclic aromatics in inferior diesel oil are targeted to single-ring aromatics, which improves the hydrogenation efficiency and further reduces reduced hydrogen consumption;

3) The present invention utilizes the second riser of the double-riser catalytic cracking device to crack hydrogenated catalytic diesel oil and light fraction, significantly reducing the operating cost of producing aromatics from diesel oil and improving process economy;

4) The present invention uses the existing diesel hydrogenation-catalytic cracking process as the basis, carries out process transformation on the basis of it, first cuts and then re-hydrogenates, and uses low-quality diesel to produce high value-added light aromatics products, improving economic benefits At the same time, it can solve the outlet problem of low-quality diesel oil in refineries, and the economic and social benefits are remarkable.

Description of drawings

Fig. 1 is the technological process schematic diagram of the present invention;

Fig. 2 is the technological process schematic diagram of comparative example 1;

Fig. 3 is the technological process schematic diagram of comparative example 2;

Reference signs: 1. Heavy oil riser, 2. Second riser, 3. Reaction oil gas pipeline I, 4. Main fractionator, 5. Catalytic cracking diesel pipeline, 6. Main cutting fractionator, 7. Heavy fraction main line , 8. Light distillate main pipeline, 9. Main hydrogenation reactor, 10. Return pipeline, 11. Reaction oil gas pipeline II, 12. Secondary fractionator, 13. Oil and gas separator I, 14. Main gasoline pipeline, 15. Secondary Hydrogenation reactor, 16, auxiliary cutting fractionation tower, 17, heavy fraction auxiliary pipeline, 18, aromatics complex, 19, light fraction auxiliary pipeline, 20, diesel pipeline, 21, oil-gas separator II, 22, auxiliary gasoline pipeline, 23. Heavy oil pipeline I, 24. Circulation pipeline, 25. Heavy oil pipeline II.

Detailed ways

The technical solution of the present invention will be described in further detail below in conjunction with specific examples. The parts that are not described in the following examples of the present invention are all prior art, such as the structure of catalyst selection and oil-gas separator used in catalytic cracking , the structure of the aromatics complex, the structure of the hydrogenation reactor, the structure of the cutting and splitting tower and the structure of the fractionating tower, etc.

Example 1

A system for producing light aromatics from low-quality diesel oil, as shown in Figure 1, includes a double-riser catalytic cracking unit, a main fractionation tower 4, an auxiliary fractionation tower 12, a main cutting fractionation tower 6 and an auxiliary cutting fractionation tower 16, and the raw material of inferior diesel oil enters In the heavy oil riser 1 of the double riser catalytic cracking device, a catalytic cracking reaction is carried out, the reaction temperature of the first catalytic cracking is 480-530 ° C, the agent-oil ratio is 4-8, and the reaction pressure is 0.12-0.38 MPa, The reaction time is 2.2-4.5s, the atomized water vapor accounts for 4-8wt% of the feed amount, and the reaction oil gas produced by the reaction is settled by the main settler and sent to the main fractionation tower 4 for fractionation through the reaction oil-gas pipeline I3. The feed temperature is 480-530°C, the tower bottom temperature is 350-420°C, the tower top temperature is 80-150°C, and the tower top pressure is 0.01-0.3MPa. Fractional distillation produces three parts, namely gasoline components, catalytic cracking diesel oil and heavy oil slurry Three parts, wherein, the catalytic cracking diesel produced by the fractionation of the main fractionation tower 4 is sent to the main cutting fractionation tower 6 for cutting through the catalytic cracking diesel pipeline 5. ~350°C, tower top temperature 90-150°C, tower top pressure 0.01-1MPa, light fraction I is obtained from the top of the tower, and heavy fraction I is obtained from the bottom of the tower; the light fraction I produced is sent to the reflux through the light fraction main line 8 In the pipeline 10, the produced heavy fraction I is sent to the main hydrogenation reactor 9 through the heavy fraction main line 7 for primary hydrogenation, the reaction temperature of the primary hydrogenation is 320-390°C, and the hydrogen partial pressure is 5.0-10.0MPa. The volumetric space velocity is 0.5-1.5h-1, and the hydrogen/oil volume ratio is 300-800:1; the hydrogenated catalytic diesel oil produced by the primary hydrogenation is also sent to the return line 10 to be mixed with the light fraction I, and then sent to The secondary cracking reaction is carried out in the second riser 2 of the double-riser catalytic cracking unit. The reaction temperature of the secondary cracking reaction is 560-630°C, the catalyst-oil ratio is 9-13, and the reaction pressure is 0.12-0.38MPa. The time is 2.2-4.5s, and the atomized water vapor accounts for 1.2-3.5wt% of the feed amount;

The reaction oil gas produced by the secondary cracking reaction is settled by the auxiliary settler and then sent to the auxiliary fractionation tower 12 for secondary fractionation through the reaction oil gas pipeline II11. The temperature at the top of the tower is 80-150°C and the pressure at the top of the tower is 0.01-0.3 MPa. Fractional distillation produces three parts, namely, gasoline components, diesel components and heavy oil slurry. Among them, the generated gasoline components enter the main gasoline pipeline 14 Inside, the rich gas and sewage are separated by the oil-gas separator I13, and then sent to the auxiliary hydrogenation reactor 15 for secondary hydrogenation. The reaction temperature of the secondary hydrogenation is 300-420°C, and the hydrogen partial pressure is 2.5-3.5MPa , the hydrogen/oil volume ratio is 500～800:1, and the volumetric space velocity is 1.5～4h-1; After the secondary hydrogenation, it is sent to the sub-cut fractionation tower 16 for cutting, and the feed temperature in the sub-cut fractionation tower 16 is 50～90℃, tower bottom temperature 100～150℃, tower top temperature 40～80℃, tower top pressure 0.01～0.3MPa, light fraction II and heavy fraction II are produced by cutting, and the light fraction II produced is mainly C5C6 alkanes, It is discharged to the tank farm to reconcile gasoline through the light fraction auxiliary pipeline 19, and the heavy fraction II produced is sent to the aromatics complex 18 through the heavy fraction secondary line 17. In the aromatics complex 18, the top of the extraction tower used for aromatics extraction The temperature is 130-190°C and the pressure is 1.0-2.0MPa to produce C6-C9 light aromatic products, raffinate gasoline products and heavy aromatic products respectively, and the raffinate gasoline and heavy aromatics are sent to the gasoline pool for gasoline blending.

The process route of this embodiment is that the raw material undergoes a catalytic cracking reaction in the heavy oil riser 1 of the double-riser catalytic cracking device, and the product reaction oil gas is entered into the main fractionation tower 4 through the first reaction oil gas pipeline 3 for fractionation , the catalytic cracking diesel produced by fractionation enters the main cutting fractionation tower 6 through the catalytic cracking diesel oil pipeline 5, after cutting and fractionating through the main cutting fractionation tower 6, the light fraction is sent into the return line 10 through the light fraction main line 8, and passes through the return line 10 returns to the second riser 2 of the double riser catalytic cracking unit, the heavy fraction is sent to the main hydrogenation reactor 9 through the heavy fraction main line 7 for hydrogenation once, and the hydrogenated catalytic diesel produced is returned to the main hydrogenation reactor 9 through the return line 10 The secondary cracking reaction is carried out in the second riser 2 of the double riser catalytic cracking unit;

The reaction oil gas produced in the second riser 2 enters the auxiliary fractionation tower 12 through the second reaction oil gas pipeline 11 for fractionation, and the gasoline component produced after the fractionation enters the auxiliary hydrogenation reactor 15 through the main gasoline pipeline 14. Secondary hydrogenation, then sent to the auxiliary cutting fractionation tower 16 for cutting and fractionating, the light fraction produced is discharged to the tank farm to blend gasoline through the light fraction auxiliary line 19, and the heavy fraction is sent to the aromatics complex 18 through the heavy fraction auxiliary line 17, Produce three products (C6-C9 light aromatics, raffinate and heavy aromatics);

The diesel oil produced by the sub-fractionator 12 fractionation enters in the main cutting fractionator 6 through the diesel pipeline 20;

The light fraction produced by the fractionation in the main fractionating tower 4 is gasoline components, which are sent to the absorption tower through the auxiliary gasoline pipeline 22.

Example 2

This embodiment is a kind of limited scheme done to embodiment 1, and its main structure is the same as embodiment 1, and the limited part is: the gasoline component produced by the fractionation of the main fractionating tower 4 is passed in the oil-gas separator II21, After the rich gas and sewage are separated, they are sent to the absorption tower through the auxiliary gasoline pipeline 22.

Example 3

The present embodiment is another kind of limitation scheme that embodiment 1 is done, and its main structure is the same as embodiment 1, and the limited part is: the diesel oil cut that secondary fractionation produces in the secondary fractionation column 12 passes through the diesel oil pipeline 20 and The catalytic cracking diesel pipelines 5 are combined and sent to the main cutting fractionation tower 6 together.

Example 4

This embodiment is another kind of limited solution to Example 1, its main structure is the same as that of Example 1, and the limited part is: the heavy oil slurry produced by the fractionation of the main fractionating tower 4 is divided into There are two routes, one of which flows back to the main fractionating tower 4, and the other route is sent to the auxiliary fractionating tower 12 through the heavy oil pipeline I23.

Example 5

This embodiment is another kind of limited solution to Example 1, and its main structure is the same as that of Example 1. The limited part is: the heavy oil produced by secondary fractionation in the secondary fractionation tower 12 is processed by heavy oil Line II 25 is sent back to the recycle line 24 of the main fractionator 4.

In order to verify the advantages of the present invention compared with the prior art, the process equipment of the present invention is used to carry out the following detection tests and comparative experiments.

Detection experiment

The detection experiment adopts the equipment in Figure 1, and its specific process flow is as follows:

1) Pass the heavy oil raw material into the heavy oil riser 1 to carry out the catalytic cracking reaction, the reaction oil gas is sent to the main fractionation tower 4 for fractionation, the fractionated gasoline components are directly sent to the absorption tower, and the fractionated catalytic cracked diesel components ( Its component properties are shown in Table 1) into the main cutting fractionation tower 6, the feed temperature is 220°C, the temperature at the bottom of the tower is 300°C, the temperature at the top of the tower is 240°C, and the pressure at the top of the tower is 0.01MPa. Heavy fractions are obtained at the bottom;

2) sending the heavy fraction obtained in step 1) into the main hydrogenation reactor 9 for a hydrogenation reaction, so that the polycyclic aromatic hydrocarbons in the heavy fraction are saturated into single-ring aromatic hydrocarbons, and hydrogenated catalytic diesel oil is obtained;

The reaction temperature of a hydrogenation reaction is 390°C, the hydrogen partial pressure is 10.0MPa, the volume space velocity is 2.5h-1, the hydrogen/oil volume ratio is 800:1, the active metal in the catalyst used is nickel, and the active metal The mass accounts for 12% of the total mass of the catalyst;

3) Combine the hydrogenated catalytic diesel oil in step 2) with the light fraction obtained in step 1) and send them together into the second riser 2 for secondary cracking, and the reaction oil gas produced by the secondary cracking is sent to the secondary fractionator 12 Cracked gasoline and cracked diesel oil are distilled in the internal fractionation, and the cracked diesel oil is sent back to the main cutting fractionator 6;

The reaction temperature of the secondary cracking in the second riser 2 is 600°C, the agent-to-oil ratio is 14, the reaction pressure is 0.3Mpa, the reaction time is 4s, and the atomized water vapor accounts for 1wt% of the feed amount;

4) The cracked gasoline fractionated in step 3) is sent into the auxiliary hydrogenation reactor 15 for secondary hydrogenation reaction to obtain refined gasoline, and in the auxiliary cutting fractionation tower 16, cut fractionation is carried out with 75°C as the cut point, Obtain heavy fractions greater than the cut point and light aromatics less than the cut point, and the light fractions are used as gasoline blending products;

In this step, the reaction temperature of the secondary hydrogenation reaction is 420°C, the hydrogen partial pressure is 3.5MPa, the hydrogen/oil volume ratio is 500:1, the volume space velocity is 4h-1, and the catalyst is a cobalt-molybdenum catalyst. Its addition is 6wt%;

5) The heavy fraction in step 4) is sent to the aromatics complex 18, and the aromatics complex 18 carries out aromatics extraction and aromatics fractionation on the heavy fraction to obtain C6-C9 light aromatics products, raffinate gasoline and heavy aromatics components, Raffinated gasoline and heavy aromatic components are used as gasoline blending products;

In this step, when the aromatics are extracted, the extraction solvent is sulfolane, and the mass ratio of the extraction solvent to the heavy fraction is 8:1; the top temperature of the extraction tower used for the extraction of aromatics is 190°C, and the pressure is 2.0MPa .

The hydrogen consumption and product distribution of the whole process in this testing experiment are shown in Table 2.

Table 1 Properties of FCC diesel oil

Table 2 Hydrogen consumption and product distribution of the whole process

Comparative example 1

The catalytic cracking diesel used in this comparative example was obtained from the diesel produced by the catalytic cracking of heavy oil raw materials in the testing experiment, as shown in Table 1, and the process flow shown in Figure 2 was adopted. The difference from the detection experiment is that the catalytic diesel oil that has been catalytically cracked in the heavy oil riser 1 does not go through the fractionation of the main fractionation tower 4 and the cutting of the main cutting fractionation tower 6, and all enter the main hydrogenation reactor 9 for hydrofining, and then enter Secondary cracking in the second riser 2, the reaction oil gas is not fractionated by the auxiliary fractionation tower 12, directly sent to the auxiliary hydrogenation reactor 15 for secondary hydrogenation, and then passes through the auxiliary cutting fractionation tower 16 for cutting fractionation and aromatics combined device 18 extraction and fractionation to obtain the product;

The reaction conditions of the main hydrogenation reactor 9 are the same as the detection experiment, the reaction parameters of the cracking of the second riser 2 are also the same as the detection experiment, the reaction parameters of the auxiliary hydrogenation reactor 15 are also the same as the detection experiment, and the auxiliary cutting fractionation tower 16 The parameters of the combined aromatics unit 18 are also the same as those in the detection experiment. The hydrogen consumption and product distribution of the whole process are shown in Table 2.

Comparative example 2

The catalytic cracking diesel used in this comparative example was obtained from the diesel produced by the catalytic cracking of heavy oil raw materials in the testing experiment, as shown in Table 1, and the technological process shown in Figure 3 was adopted. The difference from the detection experiment is that the catalytic diesel oil that has undergone catalytic cracking in the heavy oil riser 1 is directly passed into the secondary hydrogenation reactor 15 for hydrogenation, and then the cutting and fractionation in the secondary cutting fractionation tower 16 and the aromatics complex 18 are carried out. Aromatics were extracted and fractionated to obtain products. Among them, the reaction parameters of the secondary hydrogenation reactor 15, the secondary cutting fractionation tower 16 and the aromatics complex 18 were the same as those in the detection experiment. The hydrogen consumption and product distribution of the whole process are shown in Table 2.

As can be seen from the data comparison in Table 2, the hydrogen consumption in the detection experiment can be reduced to below 2wt%, and the total yield of benzene, toluene, xylene, and trimethylbenzene can reach more than 50wt%, and the hydrogen consumption in Comparative Example 1 is 4.16wt%. The hydrogen consumption of ratio 2 is 4.20wt%, that is to say, the process of the present invention not only reduces the hydrogenation pressure, but also significantly reduces the hydrogen consumption.

Although the specific embodiments of the present invention have been described above, those skilled in the art should understand that these are only examples, and various changes and modifications can be made to the embodiments without departing from the principle and essence of the invention. The scope is limited only by the appended claims.

Claims (14)

1. A system for preparing light aromatics from heavy oil raw materials, comprising a double riser catalytic cracking unit, a main fractionator (4), an auxiliary fractionator (12), a main cut fractionator (6) and an auxiliary cut fractionator (16), It is characterized in that: the reaction oil gas produced by the heavy oil riser (1) of the double riser catalytic cracking unit is sent to the main fractionation tower (4) for fractionation through the reaction oil gas pipeline I (3), and the main fractionation tower (4) generates fractionation The catalytically cracked diesel oil is sent to the main cutting fractionator (6) for cutting through the catalytic cracking diesel oil pipeline (5), and the light fraction I produced is sent to the return pipeline (10) through the light fraction main pipeline (8), and the heavy fraction produced is Fraction I is sent to the main hydrogenation reactor (9) through the main line of heavy fraction (7) for hydrogenation once, and the hydrogenated catalytic diesel oil produced is also sent to the return line (10) to be mixed with light fraction I and sent to the double reactor. A secondary cracking reaction is carried out in the second riser (2) of the riser catalytic cracking unit; The reaction oil gas produced by the secondary cracking reaction is sent to the auxiliary fractionation tower (12) for secondary fractionation through the reaction oil gas pipeline II (11), and the gasoline component produced enters the main gasoline pipeline (14) and passes through the oil gas separator I ( 13) After the rich gas and sewage are separated, they are sent to the auxiliary hydrogenation reactor (15) for secondary hydrogenation, and then sent to the auxiliary cutting fractionation tower (16) for cutting, and the light fraction II produced is passed through the light fraction auxiliary The pipeline (19) is discharged to the tank farm to reconcile gasoline for use, and the heavy fraction II produced is sent to the aromatics complex (18) through the heavy fraction sub-pipeline (17) to produce C6-C9 light aromatic products, raffinate gasoline products and Heavy aromatic products. 2. A system for preparing light aromatics from heavy oil raw materials according to claim 1, characterized in that: the gasoline components produced by the fractionation of the main fractionator (4) are passed into the oil-gas separator II (21) to separate out After the rich gas and sewage are sent to the absorption tower through the auxiliary gasoline pipeline (22). 3. A system for producing light aromatics from heavy oil raw materials according to claim 1, characterized in that: the diesel fraction produced by secondary fractionation in the secondary fractionator (12) passes through the diesel pipeline (20) and the catalytic cracking diesel pipeline (5) Commonly send into the main cutting fractionation tower (6) after merging. 4. A system for producing light aromatics from heavy oil raw materials according to claim 1, characterized in that: the heavy oil slurry produced by the fractionation of the main fractionator (4) is divided into two paths through the circulation pipeline (24), one path Return to the main fractionation tower (4), and the other way is sent to the auxiliary fractionation tower (12) through the heavy oil pipeline I (23). 5. A system for preparing light aromatics from heavy oil raw materials according to claim 1, characterized in that: the heavy oil produced by secondary fractionation in the auxiliary fractionation column (12) is sent to the heavy oil pipeline II (25) Get back in the circulation line (24) of main fractionation column (4). 6. A system for preparing light aromatics from heavy oil raw materials according to claim 1, characterized in that: the reaction temperature in the heavy oil riser (1) is 480-530°C, the solvent-to-oil ratio is 4-8, and the reaction The pressure is 0.12-0.38MPa, the reaction time is 2.2-4.5s, and the atomized water vapor is 4-8wt% of the feed amount. 7. A system for preparing light aromatics from heavy oil raw materials according to claim 1, characterized in that: the feed temperature of the main fractionation tower (4) is 480-530°C, the temperature at the bottom of the tower is 350-420°C, and the temperature at the top of the tower is The temperature is 80-150°C, and the pressure at the top of the tower is 0.01-0.3 MPa. 8. A system for preparing light aromatics from heavy oil raw materials according to claim 1, characterized in that: in the main cutting fractionation tower (6), the feed temperature is 220-320°C, the tower bottom temperature is 100-350°C, The temperature at the top of the tower is 90-150°C, and the pressure at the top of the tower is 0.01-1MPa. Light fraction I is obtained from the top of the tower, and heavy fraction I is obtained from the bottom of the tower. 9. A system for preparing light aromatics from heavy oil raw materials according to claim 1, characterized in that: in the main hydrogenation reactor (9), the reaction temperature of primary hydrogenation is 320-390°C, and the partial pressure of hydrogen 5.0~10.0MPa, volume space velocity 0.5~1.5h ^-1 , hydrogen/oil volume ratio 300~800:1. 10. A system for preparing light aromatics from heavy oil raw materials according to claim 1, characterized in that: the reaction temperature for the secondary cracking reaction in the second riser (2) is 560-630°C, and the solvent-to-oil ratio 9-13, the reaction pressure is 0.12-0.38MPa, the reaction time is 2.2-4.5s, and the atomized water vapor accounts for 1.2-3.5wt% of the feed amount. 11. A system for preparing light aromatics from heavy oil raw materials according to claim 1, characterized in that: the feed temperature of the auxiliary fractionation column (12) is 450-530°C, the temperature at the bottom of the tower is 250-350°C, and the temperature at the top of the tower is The temperature is 80-150°C, and the pressure at the top of the tower is 0.01-0.3 MPa. 12. A system for preparing light aromatics from heavy oil raw materials according to claim 1, characterized in that: in the secondary hydrogenation reactor (15), the reaction temperature of the secondary hydrogenation is 300-420°C, and the hydrogen separation The pressure is 2.5-3.5MPa, the hydrogen/oil volume ratio is 500-800:1, and the volume space velocity is 1.5-4h ^-1 . 13. A system for preparing light aromatics from heavy oil raw materials according to claim 1, characterized in that: the feed temperature of the auxiliary cutting fractionation tower (16) is 50-90°C, the bottom temperature is 100-150°C, and the tower bottom temperature is 100-150°C. The top temperature is 40-80°C and the tower top pressure is 0.01-0.3MPa. 14. A system for producing light aromatics from heavy oil raw materials according to claim 1, characterized in that: in the aromatics complex (18), the temperature at the top of the extraction tower used for the extraction of aromatics is 130-190°C, The pressure is 1.0-2.0MPa.

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