CN114410344A

CN114410344A - Catalytic conversion method for inferior oil product

Info

Publication number: CN114410344A
Application number: CN202111606209.9A
Authority: CN
Inventors: 吴青; 范景新; 辛利; 臧甲忠; 靳凤英; 郭春垒; 陈博阳; 李滨; 李福双; 王银斌; 刘晗
Original assignee: China National Offshore Oil Corp CNOOC; CNOOC Tianjin Chemical Research and Design Institute Co Ltd
Current assignee: China National Offshore Oil Corp CNOOC; CNOOC Tianjin Chemical Research and Design Institute Co Ltd
Priority date: 2021-12-26
Filing date: 2021-12-26
Publication date: 2022-04-29
Anticipated expiration: 2041-12-26
Also published as: CN114410344B

Abstract

The invention provides a method for catalytic conversion of inferior oil products, which comprises the steps of enabling crude oil to contact and react with a catalyst in a first downer reactor, then introducing the crude oil into an expanding reactor, separating reaction products to obtain low-carbon olefin and aromatic hydrocarbon, introducing part of light components obtained by separation into a riser reactor, and after the light components contact and react with the catalyst, delivering a semi-spent catalyst into the expanding reactor. The method is suitable for producing low-carbon olefin and aromatic hydrocarbon products through catalytic conversion of crude oil, and has the characteristics of strong raw material adaptability and high yield of the low-carbon olefin and aromatic hydrocarbon products.

Description

Catalytic conversion method for inferior oil product

Technical Field

The invention relates to a catalytic conversion method for inferior oil products.

Background

Catalytic cracking is an important means for converting heavy oil into gasoline, diesel and liquefied gas, and the process is well known by oil refining technologists and widely reported in literature (yochumin, yangxin, petroleum refining engineering (fourth edition) [ M ]. oil industry publishers, 2009; jungwu, sanfu, catalytic cracking process and engineering (third edition) [ M ]. china petrochemical press, 2015.). On the basis of catalytic cracking, catalytic cracking processes have been developed in recent decades, and the processes aim to produce high-value low-carbon olefins such as propylene and butylene as much as possible.

Chinese patent CN110724551A proposes a method and system for catalytic cracking by using dilute phase transport bed and turbulent fluidized bed, in which preheated heavy oil and catalyst are transported to produce a first oil gas product and a semi-spent catalyst, and then the semi-spent catalyst and the first oil gas product are subjected to turbulent bed reaction. The method can improve the reaction depth of the heavy oil and the catalyst, and has the characteristics of low yield of dry gas and coke and good product distribution.

Chinese patent CN110724561A discloses a catalytic cracking method and system for producing propylene and light aromatic hydrocarbons, which teaches that a light raw material reacts with a catalyst under a dilute phase transport bed to produce a first reaction product and a semi-spent catalyst, and then the first reaction product and the semi-spent catalyst undergo a dense phase fluidized bed reaction; then the heavy oil is subjected to oil agent contact reaction in another fast fluidized bed, and finally the low-carbon olefin and the aromatic hydrocarbon are separated from the oil gas product obtained by the light heavy oil reaction.

Chinese patent CN200710120105 discloses a method for preparing low carbon olefin and light aromatic hydrocarbon, which can obtain higher yields of ethylene, propylene and light aromatic hydrocarbon by injecting into different parts of a reducing riser according to the original cracking difficulty.

U.S. 2002195373 discloses a method for producing low-carbon olefin by catalytic cracking with a downward reactor, which comprises subjecting raw oil to a rapid cracking reaction under the conditions of a low-hydrogen transfer activity catalyst at 550-650 ℃, a large catalyst-oil ratio (above 15) and a short retention time (below 0.5 s), and retaining intermediate products as much as possible, thereby obtaining a high yield of low-carbon olefin.

Chinese patent CN110724558A discloses a catalytic cracking method and system for producing propylene and high octane gasoline, in which raw oil is divided into high-quality heavy oil and low-quality heavy oil, the high-quality heavy oil is subjected to a series reaction of a dilute phase conveying bed and a dense phase fluidized bed, the heavy oil is introduced into another fast fluidized bed for reaction, the yield of coke and dry gas produced by catalytic cracking in the method and system is low, and the yield of low-carbon olefin and high octane gasoline is high.

The catalytic cracking method has a good effect on cracking heavy oil to prepare low-carbon olefin, but the current catalytic cracking technology can only treat oil products with high hydrogen content and low heavy metal content such as asphaltene, nickel, vanadium and the like.

However, worldwide, the production of paraffinic crude oil is quite limited and resources are in short supply. At present, a large amount of mined crude oil is intermediate base crude oil with lower hydrogen content, and the intermediate base oil is not suitable for being used as a raw material for catalytic cracking (Chenjun, Shang-friendly. catalytic cracking process and engineering (third edition) [ M ]. China petrochemical Press, 2015; Shang-friendly. China catalytic cracking process technical progress [ J ]. China science: chemistry, 2014,44(01): 13-24.).

Therefore, it is necessary to develop a catalytic conversion method suitable for inferior middle base oil products with high contents of asphaltene, heavy metal and carbon residue and low hydrogen content.

Disclosure of Invention

The invention provides a catalytic conversion method of inferior oil products aiming at the defects of the prior art, the method can adapt to the characteristics of lower hydrogen content and higher contents of asphaltene, heavy metal and carbon residue of inferior intermediate base oil products, and simultaneously, the method can omit the distillation process of intermediate base crude oil and realize the full-component catalytic conversion of the intermediate base oil products. The method has the characteristics of high yield of low-carbon olefin and high yield of aromatic hydrocarbon when treating the poor-quality intermediate base oil product.

In order to realize the purpose, the invention comprises the following technical scheme:

a catalytic conversion method for inferior oil products comprises the following steps:

1) preheating the inferior oil product to 100-320 ℃, spraying the inferior oil product into the top of a first downward reactor, contacting with a catalyst, and reacting at 480-600 ℃ in a solvent-oil ratio (4-20): 1 and a water-oil ratio (0.05-0.50): 1, carrying out a first reaction under the conditions that the reaction pressure is 0.10-0.70 MPa and the reaction time is 0.05-1.0 s; introducing the oil gas and the catalyst material flow into an expanding reactor connected with a first downstream reactor, and reacting at the temperature of 540-650 ℃, the catalyst-oil ratio (6-25): 1 and the water-oil ratio (0.08-0.55): 1, carrying out a second reaction under the conditions that the reaction pressure is 0.05-0.65 MPa and the reaction time is 1.0-5.0 s;

2) introducing oil gas and a catalyst in an expanding reactor into a second downstream bed reactor, and reacting at the temperature of 520-630 ℃, the catalyst-oil ratio (10-30): 1, and the water-oil ratio (0.10-0.60): 1, carrying out a third reaction under the conditions that the reaction pressure is 0.05-0.60 MPa and the reaction time is 0.2-1.0 s, introducing a quenching agent at the outlet of a second downer reactor, separating oil after the reaction is finished to obtain an oil-gas product and a coking and inactivating spent catalyst, feeding the oil-gas product into a fractionating tower, and recycling the regenerated catalyst of the spent catalyst;

3) sending any one or two mixed components of a first remilling component and a second remilling component obtained from a fractionating tower into a riser reactor, carrying out a fourth reaction under the conditions of reaction temperature of 550-670 ℃, agent-oil ratio (4-15): 1, water-oil ratio (0.06-0.30): 1, pressure of 0.15-0.50 MPa and reaction time of 1.2-4.0 s, separating oil after the reaction is finished, sending oil-gas products into the fractionating tower and a subsequent separation device for separation, and completely introducing a semi-deactivated catalyst into a diameter-expanding reactor; wherein the fraction with the initial boiling point of 120 ℃, preferably the fraction with the temperature of 40-75 ℃, 40-85% of the total amount is used as the first remix component, the fraction with the temperature of 150-290 ℃, preferably the fraction with the temperature of 175-245 ℃, and 40-75% of the total amount is used as the second remix component;

4) fractionating the oil gas product into a gas product, light oil products with different boiling point ranges and a heavy oil product by a fractionating tower, separating the gas product to obtain a low-carbon olefin product, extracting the light oil product to obtain a light aromatic hydrocarbon product, and refining the heavy oil product to obtain a polycyclic aromatic hydrocarbon product;

the catalyst is a catalytic cracking catalyst or a mixed catalyst of the catalytic cracking catalyst and the catalytic cracking catalyst.

In the catalytic conversion method of the inferior oil product, the catalyst preferably comprises a substrate, a carrier, a binder and an active component. The carrier content is 20-50% calculated on a dry basis, and is one or more of kaolin, diatomite, halloysite and hydrotalcite-like compound; 10-30% of carrier, 5-25% of binder and one or more of alumina, silica gel and amorphous silicon-aluminum oxide; the active components comprise a molecular sieve and a metal oxide, wherein the content of the molecular sieve is 10-35%, the active components comprise an MFI modified molecular sieve and one or two of an FAU modified molecular sieve and a BEA molecular sieve, and the content of the metal oxide is 1.0-20.0%, and the active components comprise one or more mixed oxides of iron, nickel, potassium, calcium, magnesium, sodium, vanadium, manganese, cerium and gallium.

The reaction temperature of the first reaction is preferably 520-550 ℃, the agent-oil ratio is preferably (10-15): 1, and the water-oil ratio is preferably (0.08-0.20): 1, the reaction pressure is preferably 0.24-0.42 MPa, and the reaction time is 0.3-0.8 s; the reaction temperature of the second reaction is preferably 560-630 ℃, the agent-oil ratio is preferably (15-22): 1, and the water-oil ratio is preferably (0.15-0.22): 1, the reaction pressure is preferably 0.20-0.37 MPa, and the reaction time is 3.0-4.5 s.

The reaction temperature of the third reaction is 550-620 ℃, the ratio of catalyst to oil (15-25) is 1, and the ratio of water to oil (0.18-0.25): 1, the reaction pressure is 0.18-0.35 MPa, the reaction time is 0.3-0.5 s, the reaction temperature of the fourth reaction is preferably 580-650 ℃, the agent-oil ratio is (6-10): 1, the water-oil ratio is (0.11-0.20): 1, and the pressure is 0.30-0.40 MPa.

Optionally, the regenerated catalyst is conveyed into the expanding reactor, the temperature of the catalyst conveyed into the expanding reactor is 650-725 ℃, preferably 660-700 ℃, and the regenerated catalyst can be properly heated to reach the preferred temperature range before being conveyed into the expanding reactor.

Preferably, the MFI modified molecular sieve is prepared by using aluminum sulfate, ZSM-5 molecular sieve seed crystals, n-butylamine and water glass according to the formula n (SiO)₂)：n(Al₂O₃): n (hexadecyltrimethylammonium bromide): n (NaOH): n (H2O) ═ 1: 0.02-0.45: 0.05-0.12: 0.10-0.65: 30-50, by mass, the ZSM-5 molecular sieve seed crystal accounts for 5-20% of the added water glass, the slurry is aged for 2-5 h at 60-75 ℃, crystallized for 6-10 h at 100-120 ℃, then crystallized for 10-14 h at 165-180 ℃, and the molecular sieve is chemically modified by Mo, P and Fe, wherein the content of Mo is 0.2-1.0% by oxide, the content of P is 1.5-3.5% by oxide, and the content of Fe is 0.3-2.0% by oxide on a dry basis.

Preferably, the FAU-type modified molecular sieve is modified by lanthanum, samarium, iron and phosphorus, the lanthanum and the samarium are impregnated in the molecular sieve in a nitrate form, the impregnated molecular sieve is dried and then roasted for 2.0 to 4.0 hours at the temperature of 420 to 550 ℃ in the atmosphere of water vapor with the content of 50 to 75 percent, then ferric nitrate and ammonium dihydrogen phosphate are used for impregnation, and the impregnated molecular sieve is dried and then roasted for 2 to 5.5 hours at the temperature of 450 to 600 ℃ in the atmosphere of air. Based on dry basis, the contents of lanthanum, samarium, iron and phosphorus are 1.5-3.5%, 1.8-5.5%, 0.5-2.0% and 0.5-1.8% in terms of oxides.

Preferably, in the catalyst molecular sieve component, the content of the MFI modified molecular sieve is 1.2-5.0 times of the sum of the contents of the rest molecular sieves on a dry basis.

Preferably, the regeneration of the spent catalyst comprises: after residual oil gas products on the catalyst to be regenerated are eluted by water vapor, oxygen-containing gas is introduced at the temperature of 650-900 ℃ for coke burning regeneration, wherein the oxygen-containing gas is one of air, oxygen-enriched air and oxygen, and the catalyst regeneration mode is one of single-stage regeneration, two-stage regeneration and regeneration of a turbulent bed, a fast bed or a transport bed.

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

the method adopts the first downstream bed reactor which has the characteristic that the catalyst and the oil gas are along the gravitational field, the back mixing degree of the catalyst is small, the catalyst with higher activity can be ensured to be contacted with the fresh raw materials entering the reactor, the catalytic reaction of the raw materials is strengthened, and better product distribution is obtained; the diameter-expanded descending bed reactor is adopted, so that the oil gas product rich in gasoline olefin generated in the first descending bed reactor can be subjected to sufficient secondary cracking reaction, a high-temperature semi-spent regenerated catalyst is injected into the diameter-expanded reactor, the activity of the catalyst in the diameter-expanded reactor and the reaction temperature in the reactor can be improved, and the cracking of the low-carbon olefin precursor into the low-carbon olefin is further enhanced.

In the invention, optionally, the high-temperature regenerated catalyst is independently supplemented into the expanding reactor, so that the reaction temperature and the activity of the catalyst in the expanding reactor can be further improved, and the cracking of the unreacted and sufficient raw oil in the first reactor into low-carbon olefin and aromatic hydrocarbon products is strengthened. The first and second recycle components contain a large amount of gasoline olefins, long side chain monocyclic aromatics, and unreactive light saturated hydrocarbons in the crude oil. In the invention, the first recycle component and the second recycle component are introduced into the riser to carry out a reaction with higher severity, so that the first recycle component and the second recycle component can be enhanced to be converted into low-carbon olefin and aromatic hydrocarbon, and the yield of the low-carbon olefin aromatic hydrocarbon is increased.

The catalyst used in the preferred scheme contains two active components, namely metal oxide and molecular sieve, the metal oxide component can adsorb heavy metal substances such as nickel, vanadium and the like in heavy oil molecules when cracking hydrocarbon molecules, and the metal oxide has strong nickel and vanadium pollution resistance, so that the poisoning effect of heavy metals on the active components of the catalyst can be greatly reduced; in addition, when the heavy oil is catalyzed by the metal oxide, the coking capability is low, and the inactivation of the catalyst caused by rapid coking of asphaltene and the like on the catalyst can be greatly avoided; meanwhile, the metal oxide has low hydrogen transfer activity, and can retain gasoline olefin products generated during heavy oil macromolecule cracking to the maximum extent; the molecular sieve component mainly comprises a high-silicon MFI modified molecular sieve with small pore diameter, has the characteristics of strong metal poisoning resistance and good low-carbon olefin selectivity, and can convert gasoline low-carbon olefin into a low-carbon olefin product to the maximum extent.

Compared with the common catalytic cracking method using the paraffin-based raw material, the method of the invention can use the inferior oil product with higher contents of asphaltene, heavy metal and carbon residue as the catalytic conversion raw material, and has high yields of low-carbon olefin and aromatic hydrocarbon.

Drawings

FIG. 1 is a schematic process flow diagram of the catalytic conversion method for inferior oil products of the present invention.

In the figure:

1 poor oil product, 2 a first downer reactor, 3 an expanding reactor, 4 a horizontal cyclone separator, 5 a quenching agent, 6 reaction oil gas I, 7 a spent catalyst, 8a stripper, 9 a spent agent conveying inclined tube, 10 a regenerator, 11 oxygen-containing gas, 12 regeneration flue gas, 13 a regenerator lifting gas, 14 a regenerator conveying vertical tube, 15 a regenerator conveying inclined tube, 16 a back smelting component, 17 a riser reactor, 18 a cyclone separator, 19 reaction oil gas II, 20 a semi-spent catalyst, 21 a second downer reactor, 22 a regenerated catalyst

Detailed Description

The technical solution of the present invention is further described by the following specific examples.

Example 1

The catalyst used was prepared as follows. Mixing and pulping kaolin, halloysite and water, adding amorphous silicon-aluminum oxide, aluminum oxide and silica gel, uniformly stirring, adding aluminum sol, uniformly pulping, finally adding an MFI modified molecular sieve, an FAU modified molecular sieve and a BEA molecular sieve, uniformly stirring, adjusting the pH of the pulp to 3.5-4.0, then adding a mixed solution of ferric nitrate, magnesium nitrate, cerium nitrate and manganese nitrate, uniformly stirring, wherein the proportions of kaolin, halloysite, amorphous silicon-aluminum oxide, silicon dioxide, aluminum sol, MFI modified molecular sieve, FAU modified molecular sieve, BEA molecular sieve, ferric oxide, magnesium oxide, cerium oxide and manganese oxide are 30.0%, 6.4%, 8.5%, 3.5%, 5.0%, 24.0%, 6.5%, 5.4%, 4.0%, 1.6%, 3.0% and 2.1% on the basis of dry oxide, controlling the solid content to be 27%, and spray-molding the mixed pulp.

The preparation method of the MFI modified molecular sieve in the catalyst preparation process comprises the following steps of preparing aluminum sulfate, ZSM-5 molecular sieve seed crystals, n-butylamine and water glass according to the formula of n (SiO 2): n (Al2O 3): n (hexadecyltrimethylammonium bromide): n (NaOH): n (H2O) ═ 1: 0.12: 0.06: 0.25: 35, proportioning, wherein the adding amount of ZSM-5 molecular sieve seed crystals accounts for 6.5% of the adding amount of the water glass in mass percent, aging the slurry at 65 ℃ for 2.5h, crystallizing at 115 ℃ for 9h, then crystallizing at 175 ℃ for 12h, washing and drying the molecular sieve, impregnating and modifying the molecular sieve by adopting Mo, P and Fe elements, wherein the content of Mo is 0.5% in terms of oxide, the content of P is 2.5% in terms of oxide and the content of Fe is 0.8% in terms of oxide on a dry basis, and roasting the impregnated molecular sieve at 520 ℃ for 2h after drying.

The preparation method of the FAU type modified molecular sieve in the catalyst preparation process comprises the following steps: lanthanum, samarium, iron and phosphorus are used for modification, the lanthanum and the samarium are impregnated in a molecular sieve in a nitrate form, the impregnated molecular sieve is baked at 450 ℃ for 3.0h in the atmosphere of water vapor with the content of 55 percent, then ferric nitrate and ammonium dihydrogen phosphate are used for impregnation, and the impregnated molecular sieve is baked at 500 ℃ for 3h in the atmosphere of air after being baked. On a dry basis, lanthanum, samarium, iron, and phosphorus were present in amounts of 2.5%, 2.8%, 0.7%, and 1.5% as oxides.

The properties of the oils of the used inferior oils are shown in Table 1.

TABLE 1

Item	Numerical value
		Density, 20 ℃, g/cm3	0.9301
Carbon residue, m%	3.3
		Carbon content, m%	86.18
Hydrogen content, m%	12.29
		Nitrogen content, m%	0.31
Sulfur content, m%	1.22
		Four components, m%
Saturated fraction	49.6
		Aromatic component	33.1
Glue	14.3
		Asphaltenes	3.0
Metal content,. mu.g/g
		Nickel (II)	12.5
Vanadium oxide	5.1
		Distillation range, deg.C
10％	194
		30％	268
50％	416
		70％	493
90％	624

Preheating the inferior oil product 1 to 210 ℃, spraying the inferior oil product into the top of a first downstream reactor 2, contacting with a catalyst, and reacting at a reaction temperature of 540 ℃, a catalyst-oil ratio of 8:1, a water-oil ratio of 0.13: 1, carrying out a first reaction under the conditions that the reaction pressure is 0.35MPa and the reaction time is 0.6 s; then introducing the oil gas and the catalyst material flow into an expanding reactor 3 connected with the first downstream reactor 2, and reacting at the temperature of 575 ℃, the ratio of agent to oil of 15:1, the ratio of water to oil of 0.18: 1, carrying out a second reaction under the conditions that the reaction pressure is 0.32MPa and the reaction time is 4.5 s; at the same time, the regenerated catalyst 22 heated to 669 ℃ is fed into the expanding reactor 3 to reach the reaction temperature required in the expanding reactor.

Introducing oil gas and a catalyst in the expanding reactor 3 into a second downer reactor 21, and reacting at a reaction temperature of 564 ℃, a catalyst-oil ratio of 15:1, a water-oil ratio of 0.19: 1, carrying out a third reaction under the conditions that the reaction pressure is 0.30MPa and the reaction time is 0.4s, introducing crude gasoline with the temperature of 35 ℃ as a quenching agent at the outlet of a second downer reactor 21, reducing the outlet temperature of the second downer reactor to 528 ℃, separating oil after the reaction is finished to obtain an oil gas product and a coked and deactivated spent catalyst, introducing the oil gas product I into a horizontal cyclone separator 4, stripping the spent catalyst 7 by a stripper 8, then delivering the stripped catalyst into a regenerator 10, introducing air to carry out two-stage scorching regeneration at 695 ℃, and recycling the regenerated catalyst;

sending oil gas obtained from the horizontal cyclone separator 4 into a fractionating tower, taking 65% of the total amount of initial boiling point-80 ℃ fractions obtained from the fractionating tower as a first recycling component, taking 55% of the total amount of 160-235 ℃ fractions as a second recycling component, sending a mixed component of the obtained first recycling component and the obtained second recycling component into a riser reactor 17, carrying out fourth reaction under the conditions of reaction temperature of 580 ℃, agent-oil ratio of 7:1, 0.16:1, pressure of 0.38MPa and reaction time of 2.2s, separating oil after the reaction is finished, sending an oil gas product II 19 into the fractionating tower and a subsequent separating device for separation, and completely introducing a semi-deactivated catalyst into a diameter expanding reactor.

The oil gas product is fractionated by a fractionating tower to obtain a gas product, light oil products with different boiling point ranges and a heavy oil product, the gas product is subjected to gas separation to obtain a low-carbon olefin product, the light oil product is extracted to obtain a light aromatic hydrocarbon product, and the heavy oil product is refined to obtain a polycyclic aromatic hydrocarbon product.

Table 2 shows the product distribution results.

TABLE 2

Example 2

In this example, the feed oil was used in the same manner as in example 1, and the catalyst used was a conventional catalytic cracking catalyst. Wherein the catalyst consists of kaolin, alumina sol binder and molecular sieve, and the proportion of Y molecular sieve and ZSM-5 contained in the catalyst is respectively 16.5 and 18.3 percent. The procedure was as in example 1. The results are shown in Table 2.

As can be seen from Table 2, when the method provided by the invention is used, when the inferior intermediate heavy oil with 12.29% of hydrogen, 3.0% of asphaltene, 12.5 μ g/g of nickel and vanadium and 5.1 μ g/g of nickel and vanadium is used as the raw material, the total yield of the low carbon olefin and the aromatic hydrocarbon in example 2 also reaches 50.7%, the yield of the low carbon olefin in example 1 reaches 31.2%, the total yield of the low carbon olefin and the aromatic hydrocarbon reaches 72.0%, and the coke yield is only 8.2%. Specifically, as in example 2, the use of a specific catalyst in combination can achieve a more excellent effect.

Claims

1. A method for catalytic conversion of inferior oil products is characterized by comprising the following steps:

1) preheating the inferior oil product to 100-320 ℃, spraying the inferior oil product into the top of a first downward reactor, contacting with a catalyst, and reacting at 480-600 ℃ in a solvent-oil ratio (4-20): 1 and a water-oil ratio (0.05-0.50): 1, carrying out a first reaction under the conditions that the reaction pressure is 0.10-0.70 MPa and the reaction time is 0.05-1.0 s; introducing the oil gas and the catalyst material flow into an expanding reactor connected with a first downstream reactor, and reacting at the temperature of 520-650 ℃, the catalyst-oil ratio (6-25): 1, and the water-oil ratio (0.08-0.55): 1, carrying out a second reaction under the conditions that the reaction pressure is 0.05-0.65 MPa and the reaction time is 1.0-5.0 s;

2) introducing oil gas and a catalyst in an expanding reactor into a second downstream bed reactor, and reacting at the temperature of 520-630 ℃, the catalyst-oil ratio (10-30): 1, and the water-oil ratio (0.10-0.60): 1, carrying out a third reaction under the conditions that the reaction pressure is 0.05-0.60 MPa and the reaction time is 0.2-1.0 s, introducing a quenching agent at the outlet of a second downer reactor, separating oil after the reaction is finished to obtain an oil-gas product and a coking and inactivating spent catalyst, and introducing the oil-gas product into a fractionating tower for recycling the spent catalyst after regeneration;

3) sending any one or two mixed components of a first remilling component and a second remilling component obtained from a fractionating tower into a riser reactor, carrying out a fourth reaction under the conditions of reaction temperature of 550-670 ℃, agent-oil ratio (4-15): 1, water-oil ratio (0.06-0.30): 1, pressure of 0.15-0.50 MPa and reaction time of 1.2-4.0 s, separating oil after the reaction is finished, sending oil-gas products into the fractionating tower and a subsequent separation device for separation, and completely introducing a semi-deactivated catalyst into a diameter-expanding reactor; the first remilling component is a fraction with an initial boiling point of 40-85% of the total amount and a temperature of 120 ℃, and the second remilling component is a fraction with a temperature of 150-290% of the total amount and a temperature of 40-75%;

2. The method of claim 1, wherein the catalyst comprises 20-50% of a substrate, 10-30% of a carrier, 5-25% of a binder, 10-35% of a molecular sieve, and 1.0-20% of a metal oxide on a dry basis; wherein the matrix is one or more of kaolin, diatomite, halloysite and hydrotalcite-like compound; the carrier is one or more of alumina, silica gel and amorphous silicon-aluminum oxide; the binder is one or two of aluminum sol and silica sol; the molecular sieve and the metal oxide are active components, wherein the molecular sieve is an MFI modified molecular sieve and one or two of an FAU modified molecular sieve and a BEA molecular sieve; the metal oxide is one or more mixed oxides of iron, nickel, potassium, calcium, magnesium, sodium, vanadium, manganese, cerium and gallium.

3. The method according to claim 1, wherein the reaction temperature of the first reaction is 540-550 ℃, the agent-oil ratio is (10-15): 1, and the water-oil ratio is (0.08-0.20): 1, the reaction pressure is 0.24-0.42 MPa, and the reaction time is 0.3-0.8 s; the reaction temperature of the second reaction is 560-630 ℃, the agent-oil ratio is (15-22): 1, and the water-oil ratio is (0.15-0.22): 1, the reaction pressure is 0.20-0.37 MPa, and the reaction time is 3.0-4.5 s.

4. The method according to claim 1, wherein the reaction temperature of the third reaction is 550-620 ℃, the ratio of catalyst to oil is (15-25) to 1, and the ratio of water to oil is (0.18-0.25): 1, the reaction pressure is 0.18-0.35 MPa, the reaction time is 0.3-0.5 s, the reaction temperature of the fourth reaction is 580-650 ℃, the agent-oil ratio is (6-10): 1, the water-oil ratio is (0.11-0.20): 1, and the pressure is 0.30-0.40 MPa.

5. The method according to claim 1, wherein the first remill component is a 40-75% total fraction having a primary boiling point of 120 ℃ and the second remill component is a 40-75% total fraction having a temperature of 175-245 ℃.

6. The method according to claim 1, wherein the spent catalyst is recycled after regeneration, and the regenerated catalyst is fed into the expanding reactor, wherein the temperature of the regenerated catalyst fed into the expanding reactor is 650-725 ℃, preferably 660-700 ℃.

7. The method of claim 2, wherein the MFI modified molecular sieve is prepared by aluminum sulfate, ZSM-5 molecular sieve seed crystals, n-butylamine, and water glass as n (SiO)₂)：n(Al₂O₃): n (hexadecyltrimethylammonium bromide): n (NaOH): n (H)₂O) ═ 1: 0.02-0.45: 0.05-0.12: 0.10-0.65: 30-50, wherein the addition amount of ZSM-5 molecular sieve crystal seeds accounts for the addition amount of water glass by mass5-20%, aging the slurry at 60-75 ℃ for 2-5 h, crystallizing at 100-120 ℃ for 6-10 h, crystallizing at 165-180 ℃ for 10-14 h, and chemically modifying the molecular sieve by using Mo, P and Fe, wherein the content of Mo is 0.2-1.0% in terms of oxide, the content of P is 1.5-3.5% in terms of oxide, and the content of Fe is 0.3-2.0% in terms of oxide on a dry basis.

8. The method according to claim 2, wherein the FAU-type modified molecular sieve is modified with lanthanum, samarium, iron and phosphorus, the lanthanum and samarium are impregnated in the molecular sieve in the form of nitrate, the impregnated molecular sieve is dried and then calcined at 420-550 ℃ in an atmosphere of 50-75% water vapor for 2.0-4.0 hours, then impregnated with ferric nitrate and ammonium dihydrogen phosphate, and the impregnated molecular sieve is dried and then calcined at 450-600 ℃ in an atmosphere of air for 2-5.5 hours. Based on dry basis, the contents of lanthanum, samarium, iron and phosphorus are 1.5-3.5%, 1.8-5.5%, 0.5-2.0% and 0.5-1.8% in terms of oxides.

9. The method of claim 2, wherein the MFI-modified molecular sieve content of the catalyst molecular sieve component is 1.2 to 5.0 times the sum of the remaining molecular sieve contents on a dry basis.

10. The method of claim 1, wherein the spent catalyst regeneration comprises: after residual oil gas products on the catalyst to be regenerated are eluted by water vapor, oxygen-containing gas is introduced at the temperature of 650-900 ℃ for coke burning regeneration, wherein the oxygen-containing gas is one of air, oxygen-enriched air and oxygen, and the regeneration mode is one of single-stage regeneration, two-stage regeneration and regeneration of a turbulent bed, a fast bed or a conveying bed.