CN114410344B

CN114410344B - Catalytic conversion method for inferior oil

Info

Publication number: CN114410344B
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: 2023-05-09
Anticipated expiration: 2041-12-26
Also published as: CN114410344A

Abstract

The invention provides a catalytic conversion method of inferior oil products, which comprises the steps of carrying out contact reaction on crude oil and 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 separated light components into a riser reactor, carrying out contact reaction on the light components and the catalyst, and then introducing a semi-spent catalyst into the expanding reactor. The method is suitable for producing low-carbon olefin and aromatic hydrocarbon products by 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

Technical Field

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

Background

Catalytic cracking is an important means for lightening heavy oil, and the process is a main means for converting heavy oil into products such as gasoline, diesel oil, liquefied gas and the like by refineries, and the process is well known to general refinery science and technology workers and is widely reported in literature (Xu Chunming, yang Chao, fourth edition) petroleum refining engineering (fourth edition) [ M ]. Petroleum industry Press, 2009; chen Junwu, xu Youhao. Catalytic cracking process and engineering (third edition) [ M ]. Chinese petrochemical Press, 2015.). Based on catalytic cracking, a catalytic cracking process has been developed in recent decades, and the process aims at producing high-value low-carbon olefins such as propylene butene in a more-yield manner.

Chinese patent CN110724551a proposes a method and system for catalytic cracking using dilute phase transport bed and turbulent fluidized bed, in which preheated heavy oil is transported with catalyst to react once to generate first oil gas product and semi-spent catalyst, and then the semi-spent catalyst and the first oil gas product are reacted in turbulent bed. The method can improve the reaction depth of 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 process and system for producing propylene and light aromatic hydrocarbons, which states that light raw materials are reacted 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 are subjected to a dense phase fluidized bed reaction; and then carrying out oil contact reaction on heavy oil in another rapid fluidized bed, and finally separating oil-gas products obtained by the reaction of light heavy oil to obtain low-carbon olefin and aromatic hydrocarbon.

Chinese patent CN200710120105 discloses a process for preparing low-carbon olefine and light aromatic hydrocarbon, which is to inject the low-carbon olefine and light aromatic hydrocarbon into different parts of reducing riser according to the degree of difficulty in cracking.

US patent 2002195373 discloses a method for producing low-carbon olefins by catalytic pyrolysis using a downstream reactor, wherein the method comprises the steps of carrying out rapid pyrolysis reaction on raw oil under the condition of a low-hydrogen transfer active catalyst at 550-650 ℃, a large catalyst-to-oil ratio (more than 15) and a short residence time (less than 0.5 s), and retaining intermediate products as much as possible, thereby obtaining higher low-carbon olefin yield.

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

The catalytic cracking method has better effect in preparing the low-carbon olefin by cracking the heavy oil, but the existing catalytic cracking technology can only treat the oil products with higher hydrogen content and lower heavy metal content such as asphaltene, nickel vanadium and the like.

However, worldwide, paraffin-based crude oil yields are quite limited and resources are in shortage. At present, a large amount of crude oil is extracted into crude oil with low hydrogen content and intermediate property, and the intermediate property oil is not suitable for being used as a raw material for catalytic cracking (Chen Junwu, xu Youhao. Catalytic cracking process and engineering (third edition) [ M ]. China petrochemical Press, 2015; xu Youhao. China catalytic cracking process technology development [ J ]. China science: chemistry, 2014,44 (01): 13-24.).

Therefore, there is a need to develop a catalytic conversion process that can accommodate inferior intermediate base oils with higher asphaltene, heavy metal, carbon residue content, and lower hydrogen content.

Disclosure of Invention

The invention provides a catalytic conversion method of an inferior oil product aiming at the defects of the prior art, which can be suitable for the characteristics of low hydrogen content of the inferior intermediate base oil product and high contents of asphaltene, heavy metal and carbon residue. The method has the characteristics of high yield of low-carbon olefin and high yield of aromatic hydrocarbon when treating the inferior intermediate base oil product.

In order to achieve the purpose, the invention adopts the following technical scheme:

the catalytic conversion process of inferior oil product includes the following steps:

1) Preheating inferior oil to 100-320 deg.c, spraying into the top of the first downstream reactor to contact with catalyst at 480-600 deg.c, catalyst-oil ratio of 4-20 to 1 and water-oil ratio of 0.05-0.50: 1, under the condition of 0.10-0.70 MPa of reaction pressure and 0.05-1.0 s of reaction time, carrying out a first reaction; then the oil gas and catalyst material flow is introduced into a diameter-expanding reactor connected with a first descending reactor, and the catalyst-oil ratio (6-25) is 1, the water-oil ratio (0.08-0.55) is that at the reaction temperature of 540-650 ℃:1, under the condition that the reaction pressure is 0.05-0.65 MPa and the reaction time is 1.0-5.0 s, carrying out a second reaction;

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

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

4) Fractionating the oil gas product by a fractionating tower to obtain a gas product, light oil with different boiling point ranges and a heavy oil product, 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 matrix, a carrier, a binder and an active component. The carrier content is 20-50% based on dry basis, and is one or more of kaolin, diatomite, halloysite and hydrotalcite-like compound; the carrier content is 10-30%, which is one or more of alumina, silica gel and amorphous silicon-aluminum oxide, and the binder content is 5-25%, which is one or two of aluminum sol and silica sol; the active components are molecular sieve and metal oxide, wherein the molecular sieve content is 10-35%, which is one or two of MFI modified molecular sieve, FAU modified molecular sieve and BEA molecular sieve, and the metal oxide content is 1.0-20.0%, which is one or more of mixed oxide of iron, nickel, potassium, calcium, magnesium, sodium, vanadium, manganese, cerium and gallium.

The reaction temperature of the first reaction is preferably 520-550 ℃, the catalyst-to-oil ratio is preferably (10-15): 1, and the water-to-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 catalyst-to-oil ratio is preferably (15-22): 1, and the water-to-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 catalyst-oil ratio (15-25) is 1, and the water-oil ratio (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 catalyst-to-oil ratio (6-10) is 1, the water-to-oil ratio is (0.11-0.20) 1, and the pressure is 0.30-0.40 MPa.

Alternatively, the regenerated catalyst is fed to the expanding reactor at a catalyst temperature of 650-725 ℃, preferably 660-700 ℃, and suitable heat extraction may be performed to achieve the preferred temperature range before feeding the regenerated catalyst to the expanding reactor.

Preferably, the MFI modified molecular sieve is prepared by the steps of aluminum sulfate, ZSM-5 molecular sieve seed crystal, n-butylamine and water glass according to n (SiO ₂ )：n(Al ₂ O ₃ ): n (cetyl trimethylammonium bromide): n (NaOH): n (H2O) =1: 0.02 to 0.45:0.05 to 0.12:0.10 to 0.65:30 to 50, the added amount of ZSM-5 molecular sieve seed crystal is 5 to 20 percent of the added amount of added water glass by mass, the slurry is aged for 2 to 5 hours at 60 to 75 ℃, crystallized for 6 to 10 hours at 100 to 120 ℃, and then crystallized at 165 to 180 DEG CThe chemical modification is carried out on the molecular sieve for 10 to 14 hours by adopting Mo, P and Fe elements, wherein the content of the Mo is 0.2 to 1.0 percent based on oxide, the content of the P is 1.5 to 3.5 percent based on oxide, and the content of the Fe is 0.3 to 2.0 percent based on oxide.

Preferably, the FAU modified molecular sieve is modified by lanthanum, samarium, iron and phosphorus, lanthanum and samarium are soaked in the molecular sieve in the form of nitrate, the soaked molecular sieve is baked for 2.0-4.0 hours in the steam atmosphere with the content of 50-75% at 420-550 ℃ after being dried, then ferric nitrate and ammonium dihydrogen phosphate are used for soaking, and the soaked molecular sieve is baked for 2-5.5 hours at 450-600 ℃ in the air atmosphere after being dried. 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% calculated by dry basis based on oxide.

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

Preferably, the spent catalyst regeneration comprises: the method comprises the steps of eluting oil gas products remained on a catalyst to be regenerated through steam, and then introducing oxygen-containing gas at 650-900 ℃ for 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, turbulent bed, rapid bed or conveying bed regeneration.

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

the method adopts the characteristics that the first downer reactor has a catalyst and an oil-gas gravity field, has small back mixing degree of the catalyst, can ensure that fresh raw materials entering the reactor contact the catalyst with higher activity, strengthens the catalytic reaction of the raw materials, and obtains better product distribution; by adopting the expanded downlink bed reactor, the oil gas product rich in gasoline olefin generated in the first downlink bed reactor can be subjected to full secondary cracking reaction, and the high-temperature semi-spent regenerated catalyst is injected into the expanded reactor, so that the activity of the catalyst in the 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 can be further enhanced.

In the invention, the high-temperature regenerated catalyst is optionally supplemented into the diameter-expanding reactor, so that the reaction temperature and the activity of the catalyst in the diameter-expanding reactor can be further improved, and the raw oil which is not fully reacted in the first reactor is strengthened to be cracked into low-carbon olefin and aromatic hydrocarbon products. The first recycle component and the second recycle component contain a large amount of gasoline olefin, long-side-chain monocyclic aromatic hydrocarbon and light saturated hydrocarbon which is difficult to react in crude oil. In the invention, the first recycling component and the second recycling component are introduced into the lifting pipe to carry out higher-severity reaction, so that the conversion of the first recycling component and the second recycling component into low-carbon olefin and aromatic hydrocarbon can be enhanced, and the yield of the low-carbon olefin aromatic hydrocarbon is increased.

The catalyst used in the preferred scheme contains two active components, namely a metal oxide and a molecular sieve, wherein 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 and can greatly reduce the poisoning effect of heavy metals on the active components of the catalyst; in addition, when the metal oxide catalyzes heavy oil, the coking capacity is lower, and the catalyst deactivation caused by rapid coking of asphaltene and the like on the catalyst can be avoided to a great extent; meanwhile, the metal oxide has low hydrogen transfer activity, so that gasoline olefin products generated during the cracking of heavy oil macromolecules can be reserved to the maximum extent; the molecular sieve component is mainly a high-silicon MFI modified molecular sieve with smaller pore diameter, has the characteristics of strong metal poisoning resistance and good low-carbon olefin selectivity, and can maximally convert the low-carbon olefin of the gasoline into a low-carbon olefin product.

Compared with the general catalytic cracking method using paraffin-based attribute raw materials, the method can use inferior oil products with higher asphaltene, heavy metal and carbon residue content as catalytic conversion raw materials, and has high low-carbon olefin and aromatic hydrocarbon yields.

Drawings

FIG. 1 is a schematic diagram of the process flow of the catalytic conversion method of the inferior oil product.

In the figure:

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

Detailed Description

The technical scheme of the invention is further described through specific embodiments.

Example 1

The catalyst used was prepared as follows. Mixing kaolin, halloysite and water, pulping, adding amorphous silicon aluminum oxide, aluminum oxide and silica gel, stirring uniformly, adding aluminum sol, pulping uniformly, finally adding MFI modified molecular sieve, FAU modified molecular sieve and BEA molecular sieve, stirring uniformly, adjusting the pH of slurry to 3.5-4.0, adding mixed solution of ferric nitrate, magnesium nitrate, cerium nitrate and manganese nitrate, stirring uniformly, and carrying out spray forming on the mixed slurry by controlling the solid content to 27% based on oxide dry basis, wherein the proportion of the 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 is 30.0%, 6.4%, 8.5%, 3.5%, 24.0%, 6.5%, 5.4%, 4%, 4.0%, 1.6%, 3.0% and the solid content is 27%.

The preparation method of the MFI modified molecular sieve in the catalyst preparation process comprises the steps of aluminum sulfate, ZSM-5 molecular sieve seed crystal, n-butylamine and water glass according to n (SiO 2): n (Al 2O 3): n (cetyl trimethylammonium bromide): n (NaOH): n (H2O) =1: 0.12:0.06:0.25:35, the adding amount of ZSM-5 molecular sieve seed crystal is 6.5% of the adding amount of water glass by mass, aging the slurry for 2.5h at 65 ℃, crystallizing for 9h at 115 ℃, crystallizing for 12h at 175 ℃, washing and drying the molecular sieve, carrying out impregnation modification on the molecular sieve by using Mo, P and Fe elements, wherein the content of Mo is 0.5% by oxide, the content of P is 2.5% by oxide, the content of Fe is 0.8% by oxide, and roasting for 2h at 520 ℃ after the impregnated molecular sieve is dried.

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 modified, lanthanum and samarium are soaked in a molecular sieve in a nitrate form, the soaked molecular sieve is baked for 3.0 hours at 450 ℃ in a steam atmosphere with 55% content, then ferric nitrate and ammonium dihydrogen phosphate are used for soaking, and the soaked molecular sieve is baked for 3 hours at 500 ℃ in an air atmosphere after being dried. Lanthanum, samarium, iron and phosphorus are divided into 2.5%, 2.8%, 0.7% and 1.5% on a dry basis in terms of oxide.

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

TABLE 1

Project	Numerical value
		Density, g/cm3 at 20 DEG C	0.9301
Carbon residue, m%	3.3
		Carbon content, m%	86.18
Hydrogen content, m%	12.29
		Nitrogen content, m%	0.31
Sulfur contentThe amount, m%	1.22
		Four components, m%
Saturated portion	49.6
		Aromatic components	33.1
Colloid	14.3
		Asphaltenes	3.0
Metal content, μg/g
		Nickel (Ni)	12.5
Vanadium (V)	5.1
		Distillation range, DEG C
10％	194
		30％	268
50％	416
		70％	493
90％	624

Preheating inferior oil 1 to 210 ℃, spraying into the top of a first downlink reactor 2, contacting with a catalyst, and carrying out reaction at 540 ℃, wherein the catalyst-to-oil ratio is 8:1, and the water-to-oil ratio is 0.13:1, under the condition of 0.35MPa of reaction pressure and 0.6s of reaction time, carrying out a first reaction; then the oil gas and catalyst material flow is introduced into a diameter-expanding reactor 3 connected with a first descending reactor 2, and the reaction temperature is 575 ℃, the catalyst-oil ratio is 15:1, and the water-oil ratio is 0.18:1, under the condition of the reaction pressure of 0.32MPa and the reaction time of 4.5s, carrying out a second reaction; and simultaneously, the regenerated catalyst 22 with the temperature of 669 ℃ after heat extraction is sent into the expanding reactor 3 to reach the reaction temperature required in the expanding reactor.

Introducing the oil gas and the catalyst in the expanding reactor 3 into a second downer reactor 21, wherein the catalyst-oil ratio is 15:1, and the water-oil ratio is 0.19 at the reaction temperature of 564 ℃): 1, under the conditions of reaction pressure of 0.30MPa and reaction time of 0.4s, carrying out a third reaction, introducing crude gasoline at 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 and gas after the reaction is finished to obtain an oil gas product and a coking deactivated spent catalyst, introducing the oil gas product I into a horizontal cyclone separator 4, stripping the spent catalyst 7 by a stripper 8, introducing air into a regenerator 10, carrying out two-stage coking regeneration at 695 ℃, and recycling the regenerated catalyst;

the oil gas obtained from the horizontal cyclone separator 4 is sent into a fractionating tower, 65% of the total amount of the fraction with the initial distillation point of 80 ℃ obtained in the fractionating tower is used as the first recycling component, 55% of the total amount of the fraction with the temperature of 160-235 ℃ is used as the second recycling component, the obtained mixed components of the first recycling component and the second recycling component are sent into a riser reactor 17, and under the conditions of the reaction temperature of 580 ℃, the catalyst-oil ratio of 7:1,0.16:1, the pressure of 0.38MPa and the reaction time of 2.2s, the fourth reaction occurs, after the reaction is finished, the oil gas product II 19 enters the fractionating tower and the subsequent separation device for separation through oil separation, and the semi-deactivated catalyst is fully introduced into the expanding reactor.

The oil gas product is fractionated by a fractionating tower to obtain a gas product, light oil with different boiling point ranges and a heavy oil product, the gas product is separated 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 results of the product distribution.

TABLE 2

Example 2

The raw oil is used in this example as in example 1, and the catalyst used is a conventional catalytic cracking catalyst. The catalyst consists of kaolin, alumina sol binder and molecular sieve, and the proportion of Y molecular sieve and ZSM-5 in the catalyst is 16.5% and 18.3% respectively. The procedure is as in example 1. The effect of the implementation is shown in Table 2.

As can be seen from Table 2, when the method provided by the invention is used for taking inferior intermediate heavy oil with 12.29% of hydrogen, 3.0% of asphaltene, 12.5 mug/g of nickel and vanadium and 5.1 mug/g as raw materials, the total yield of the low-carbon olefin and the aromatic hydrocarbon in the embodiment 2 is 50.7%, the total yield of the low-carbon olefin in the embodiment 1 is 31.2%, the total yield of the low-carbon olefin and the aromatic hydrocarbon is 72.0%, and the coke yield is only 8.2%, and the two embodiments show that the method provided by the invention is suitable for catalytic conversion of the inferior intermediate crude oil and has the characteristics of high yield of the low-carbon olefin and the aromatic hydrocarbon. In particular, as in example 2, the combination of a specific catalyst can achieve more preferable effects.

Claims

1. The catalytic conversion method of the inferior oil product is characterized by comprising the following steps of:

1) Preheating an inferior oil product to 100-320 ℃, spraying the inferior oil product into the top of a first downlink reactor, contacting with a catalyst, and performing a reaction at 480-600 ℃, wherein the catalyst-to-oil ratio is 1, and the water-to-oil ratio is 0.05-0.50: 1, under the condition that the reaction pressure is 0.10-0.70 MPa and the reaction time is 0.05-1.0 s, carrying out a first reaction; then introducing the oil gas and catalyst material flow into a diameter-expanding reactor connected with a first downlink reactor, wherein the catalyst-oil ratio (6-25) is 1, and the water-oil ratio (0.08-0.55) is that: 1, under the condition that the reaction pressure is 0.05-0.65 MPa and the reaction time is 1.0-5.0 s, performing a second reaction;

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

3) Feeding any one or two mixed components of the first and second recycling components obtained from the fractionating tower into a riser reactor, carrying out a fourth reaction under the conditions that the reaction temperature is 550-670 ℃, the catalyst-to-oil ratio (4-15) is 1, the water-to-oil ratio (0.06-0.30) is 1, the pressure is 0.15-0.50 MPa and the reaction time is 1.2-4.0 s, separating oil and gas products by an oil agent, separating the oil and gas products by a fractionating tower and a subsequent separating device, and introducing the semi-deactivated catalyst into the diameter-expanding reactor; the first recycling component accounts for 40-85% of the total distillate at the initial distillation point-120 ℃, and the second recycling component accounts for 40-75% of the total distillate at the temperature of 150-290 ℃;

2. The method according to claim 1, wherein the catalyst comprises 20-50% of a matrix, 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 one or two of an MFI modified molecular sieve, an FAU modified molecular sieve and a BEA molecular sieve; the metal oxide is one or more of mixed oxides of iron, nickel, potassium, calcium, magnesium, sodium, vanadium, manganese, cerium and gallium.

3. The method of claim 1, wherein the reaction temperature of the first reaction is 540-550 ℃, the catalyst to oil ratio is (10-15): 1, and the water to 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 catalyst-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 catalyst-to-oil ratio is (15-25): 1, and the water-to-oil ratio is (0.18-0.25): 1, a reaction pressure of 0.18-0.35 MPa, a reaction time of 0.3-0.5 s, a reaction temperature of 580-650 ℃, a catalyst-to-oil ratio of (6-10): 1, a water-to-oil ratio of (0.11-0.20): 1, and a pressure of 0.30-0.40 MPa.

5. The method of claim 1, wherein the first recycling component is 40-85% of the total amount of the fraction at the initial distillation point to 120 ℃, and the second recycling component is 40-75% of the total amount of the fraction at 150-245 ℃.

6. The method according to claim 1, wherein the catalyst to be regenerated is recycled after regeneration, and the regenerated catalyst is fed into the diameter-enlarging reactor, wherein the temperature of the regenerated catalyst fed into the diameter-enlarging reactor is 650-725 ℃.

7. The method according to claim 1, wherein the catalyst to be regenerated is recycled after regeneration, and the regenerated catalyst is fed into the diameter-enlarging reactor, wherein the temperature of the regenerated catalyst fed into the diameter-enlarging reactor is 660-700 ℃.

8. The method according to claim 2, wherein the FAU-modified molecular sieve is modified with lanthanum, samarium, iron and phosphorus, wherein lanthanum and samarium are impregnated in the molecular sieve in the form of nitrate, the impregnated molecular sieve is baked at 420-550 ℃ in a steam atmosphere with a content of 50-75% for 2.0-4.0 hours, then is impregnated with ferric nitrate and ammonium dihydrogen phosphate, the impregnated molecular sieve is baked at 450-600 ℃ in an air atmosphere for 2-5.5 hours, and 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 oxide on a dry basis.

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: the method comprises the steps of eluting oil gas products remained on a catalyst to be regenerated through steam, and then introducing oxygen-containing gas at 650-900 ℃ for 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 turbulent bed, rapid bed or conveying bed regeneration.