Method for treating catalytic diesel oil and increasing yield of light aromatic hydrocarbons

Abstract

The invention relates to a method for treating catalytic diesel oil and increasing the yield of light aromatic hydrocarbons, which comprises the following steps: hydrotreating the catalytic diesel oil to obtain hydrogenated catalytic diesel oil, and carrying out non-hydrogen catalytic cracking reaction on the hydrogenated catalytic diesel oil to efficiently convert heavy aromatic hydrocarbons generated in the conversion process of the hydrogenated catalytic diesel oil into light aromatic hydrocarbons. The problems of high hydrogen consumption, harsh operation conditions and aromatic hydrocarbon loss caused by hydrotreating production of light aromatic hydrocarbon can be avoided; on the other hand, the problem that low-value heavy aromatics are difficult to utilize can be solved, and efficient utilization of resources is achieved. The obtained heavy gasoline is subjected to a reaction in a second cracking reactor, the second cracking reactor is a dense-phase fluidized bed reactor, the heavy gasoline can be further converted into light aromatic hydrocarbon, the yield of heavy aromatic hydrocarbon components can be reduced, and the yield of BTX products can be increased. In addition, by adopting the method disclosed by the invention, low-carbon olefin can be produced as a byproduct, and the utilization rate of the raw materials is further improved.

Description

Technical Field

[0001] The present disclosure relates to the field of petrochemical industry, and in particular, to a method for treating catalytic diesel and increasing the production of light aromatics. Background Art

[0002] BTX (benzene, toluene, xylene) is an important petrochemical basic product and an important raw material for a variety of chemical products such as synthetic rubber, synthetic fibers and synthetic resins. Toluene and xylene can also be used as gasoline octane additives.

[0003] CN200710043941.3 discloses a method for producing light aromatics and light alkanes using hydrocarbon raw materials. In this method, hydrocarbon raw materials with a boiling point of 30-250°C are reacted in the presence of a zeolite catalyst containing Pt or Pd, heavy aromatics in the hydrocarbon raw materials are dealkylated by hydrogenation and undergo an alkylation translocation reaction with light aromatics, light aromatics undergo an isomerization reaction to be converted into components rich in BTX (B is benzene, T is toluene, and X is xylene) light aromatics, and non-aromatics are converted into light alkanes by a hydrogenation cracking reaction. In a distillation tower, liquid products can be separated into benzene, toluene, xylene, and C9+ aromatics according to different boiling points, and light alkanes can be separated from gaseous products. This method solves the technical problems that the traditional separation process of hydrocarbon raw materials requires solvent extraction, the process is complicated, the cost is high, and the utilization value of heavy aromatics and non-aromatics after separation is low.

[0004] CN116496814A discloses a method for producing light aromatics from diesel, wherein diesel is hydrogenated and then catalytically cracked, the cracked products are separated to obtain light aromatic fractions and heavy aromatic fractions, the light aromatic fraction is subjected to aromatic extraction, and the heavy aromatic fraction is returned to the riser reactor for further reaction, wherein the heavy aromatic fraction and the hydrogenated diesel are fed in layers. However, this method only simply recycles the heavy aromatic fraction, and does not set a dedicated reaction zone and reaction environment that is most conducive to the reaction for the conversion of the heavy aromatic fraction, resulting in a low yield of light aromatics during the conversion process. Summary of the invention

[0005] The present invention provides a method for treating catalytic diesel and increasing the production of light aromatics, so as to solve the problems of high production and difficulty in utilization of low-value heavy aromatics and low yield of light aromatics in the prior art.

[0006] In order to achieve the above-mentioned object, the present disclosure provides a method for treating catalytic diesel and increasing the production of light aromatics, which method comprises: allowing the catalytic diesel to enter a hydrogenation reaction unit for hydrogenation treatment to obtain hydrogenated catalytic diesel, and allowing the hydrogenated catalytic diesel to enter a first cracking reactor of a cracking reaction unit for a first cracking reaction, and obtaining a cracking reaction product after gas-solid separation; allowing the cracking reaction product to undergo product separation treatment to obtain other products, a light gasoline component, a heavy gasoline component and a diesel component; allowing the diesel component to return to the hydrogenation reaction unit; allowing the heavy gasoline component to enter a second cracking reactor of the cracking reaction unit for a second cracking reaction, and allowing the obtained oil agent mixture to enter the first cracking reactor; allowing the light gasoline component to undergo aromatic separation treatment to obtain a benzene product, a toluene product and a xylene product; the second cracking reactor is a dense fluidized bed reactor, and the bed density of the dense fluidized bed reactor is 180-700 kg / m 3 ; The catalyst activity of the catalyst in the second cracking reactor is 50-99.

[0007] Optionally, the initial distillation point of the light gasoline component is 20-50°C; the distillation cut point between the light gasoline component and the heavy gasoline component is 120-150°C; the distillation cut point between the diesel component and the heavy gasoline component is 200-250°C.

[0008] Optionally, the initial distillation point of the hydrocatalytic diesel is 150-250°C, and the final distillation point is 300-380°C.

[0009] Optionally, the reaction conditions of the first cracking reaction include: reaction temperature of 520-680°C, preferably 560-600°C; reaction time of 1-15s, preferably 1-8s; catalyst-oil ratio of (1-100):1, preferably (1-30):1; the reaction conditions of the second cracking reaction include: reaction temperature of 555-720°C, preferably 580-660°C; catalyst-oil ratio of (1-100):1, preferably (5-30):1; catalyst activity of 60-90.

[0010] Optionally, the catalysts for the first cracking reaction and the second cracking reaction are the same or different, and each independently comprises zeolite, inorganic oxide and optional clay; based on the total weight of the catalyst, the content of the zeolite is 5-70 weight%, the content of the inorganic oxide is 1-95 weight%, and the content of the clay is 1-50 weight%.

[0011] Optionally, the zeolite comprises large-pore zeolite and optional medium-pore zeolite; based on the total weight of the zeolite, the content of the large-pore zeolite is 60-100% by weight, and the content of the medium-pore zeolite is 0-40% by weight.

[0012] Optionally, the medium-pore zeolite is selected from ZSM zeolite; the large-pore zeolite is selected from one or more of β zeolite and Y zeolite; the inorganic oxide includes silicon dioxide and / or aluminum oxide; and the clay is kaolin and / or halloysite.

[0013] Optionally, the catalyst contains a rare earth element. Preferably, the large-pore zeolite is a Y-type zeolite modified with a rare earth element.

[0014] Optionally, the method further comprises regenerating the spent catalyst obtained from the first cracking reaction, and returning the obtained regenerated catalyst to the cracking reaction unit.

[0015] Optionally, the method further comprises adding a fresh agent into the second cracking reactor.

[0016] Optionally, the ratio of the weight of the fresh agent to the total weight of the catalyst in the cracking reaction unit is 0.2 or less.

[0017] Optionally, the cracking reaction unit also includes a regenerator; the method also includes allowing the catalyst to be regenerated to enter the regenerator for regeneration to obtain a regenerated catalyst; allowing the regenerated catalyst to return to the first cracking reactor through a first regeneration inclined tube, and to return to the second cracking reactor through a second regeneration inclined tube; optionally, a fresh agent inlet is provided on the second regeneration inclined tube.

[0018] Optionally, the dense phase fluidized bed reactor is an upward reactor or a downward reactor.

[0019] Optionally, the bed density of the dense phase fluidized bed reactor is 300-500 kg / m 3 , the bed linear speed is 0.4-2m / s.

[0020] Optionally, the first cracking reactor and the second cracking reactor are arranged in series and the first cracking reactor is arranged downstream of the second cracking reactor.

[0021] Optionally, the first cracking reactor and the second cracking reactor are coaxially arranged.

[0022] Optionally, the conditions of the hydrotreatment include: reaction temperature of 330-450°C, hydrogen partial pressure of 6-25 MPa, volume space velocity of 0.1-2 h -1 , hydrogen to oil volume ratio is 1000-2000Nm 3 / m 3 .

[0023] Optionally, the first cracking reactor is a dilute phase transport bed reactor and / or a dense phase fluidized bed reactor.

[0024] Optionally, the first cracking reactor is a cracking reactor for heavy oil feedstock;

[0025] Optionally, the hydrocatalytic diesel is contacted with the catalyst in the first cracking reactor before the heavy oil feedstock.

[0026] Through the above technical scheme, the catalytic diesel is first subjected to hydrotreatment to obtain hydrogenated catalytic diesel, and the hydrogenated catalytic diesel is subjected to a non-hydrogenated catalytic cracking reaction, so that the heavy aromatics produced during the conversion of the hydrogenated catalytic diesel can be efficiently converted into light aromatics. On the one hand, it can avoid the problems of high hydrogen consumption, harsh operating conditions and aromatic losses caused by the use of hydrotreatment to produce light aromatics; on the other hand, it can solve the problem of low-value heavy aromatics being difficult to utilize, and achieve efficient utilization of resources. The obtained heavy gasoline is recycled in the second cracking reactor, wherein the second cracking reactor is a dense phase fluidized bed reactor, which can further convert the heavy gasoline into light aromatics, thereby reducing the output of heavy aromatic components and increasing the yield of BTX products. In addition, the method disclosed in the present invention can also produce low-carbon olefins as a by-product, further improving the utilization rate of raw materials.

[0027] Other features and advantages of the present disclosure will be described in detail in the following detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] The accompanying drawings are used to provide a further understanding of the present disclosure and constitute a part of the specification. Together with the following specific embodiments, they are used to explain the present disclosure but do not constitute a limitation of the present disclosure. In the accompanying drawings:

[0029] Figure 1 The present invention is a schematic diagram of a method for treating catalytic diesel and increasing the production of light aromatics.

[0030] Figure 2 It is a schematic diagram of a specific embodiment of the cracking reaction unit used in the method of the present disclosure.

[0031] Figure 3 Schematic diagram of a second specific embodiment of a cracking reaction unit used in the method of the present disclosure.

[0032] Figure 4 It is a schematic diagram of the method for treating catalytic diesel and increasing the production of light aromatics in Comparative Example 1 of the present disclosure.

[0033] Description of Reference Numerals

[0034] 1 catalytic diesel; 2 hydrogenation reaction unit; 3 hydrogenation catalytic diesel; 4 cracking reaction unit; 5 cracking reaction product; 6 product separation unit; 7 light gasoline component; 8 heavy gasoline component; 9 diesel component; 10 other products; 11 aromatic separation unit; 12 benzene product; 13 toluene product; 14 xylene product; 15 second cracking reactor; 16 first cracking reactor; 17 settler; 18 inclined tube to be regenerated; 19 regenerator; 20 first regeneration inclined tube; 21 second regeneration inclined tube; 22 regenerated flue gas; 23 fresh agent; 24 fresh agent; 25 riser reactor. DETAILED DESCRIPTION

[0035] The specific implementation of the present disclosure is described in detail below in conjunction with the accompanying drawings. It should be understood that the specific implementation described herein is only used to illustrate and explain the present disclosure, and is not used to limit the present disclosure.

[0036] like Figure 1 As shown, the present disclosure provides a method for treating catalytic diesel and increasing the production of light aromatics, the method comprising: allowing catalytic diesel 1 to enter a hydrogenation reaction unit 2 for hydrogenation treatment to obtain hydrogenated catalytic diesel 3, and allowing the hydrogenated catalytic diesel 3 to enter a first cracking reactor 16 of a cracking reaction unit 4 for a first cracking reaction, and obtaining a cracking reaction product 5 after gas-solid separation; allowing the cracking reaction product 5 to undergo product separation treatment to obtain other products 10, a light gasoline component 7, a heavy gasoline component 8 and a diesel component 9; allowing the diesel component 9 to return to the hydrogenation reaction unit 2; allowing the heavy gasoline component 8 to enter a second cracking reactor 15 of the cracking reaction unit 4 for a second cracking reaction, and allowing the obtained oil agent mixture to enter the first cracking reactor 16; allowing the light gasoline component 7 to undergo aromatic separation treatment to obtain a benzene product 12, a toluene product 13 and a xylene product 14; the second cracking reactor 15 is a dense phase fluidized bed reactor, and the bed density of the dense phase fluidized bed reactor is 180-700 kg / m 3 ; The catalyst activity of the catalyst in the second cracking reactor is 50-99.

[0037] Through the above technical scheme, the catalytic diesel is first subjected to hydrotreatment to obtain hydrogenated catalytic diesel, and the hydrogenated catalytic diesel is subjected to a non-hydrogenated catalytic cracking reaction, so that the heavy aromatics produced during the conversion of the hydrogenated catalytic diesel can be efficiently converted into light aromatics. On the one hand, it can avoid the problems of high hydrogen consumption, harsh operating conditions and aromatic losses caused by the use of hydrotreatment to produce light aromatics; on the other hand, it can solve the problem of low-value heavy aromatics being difficult to utilize, and achieve efficient utilization of resources. The obtained heavy gasoline is recycled in the second cracking reactor, wherein the second cracking reactor is a dense phase fluidized bed reactor, which can further convert the heavy gasoline into light aromatics, thereby reducing the output of heavy aromatic components and increasing the yield of BTX products. In addition, the method disclosed in the present invention can also produce low-carbon olefins as a by-product, further improving the utilization rate of raw materials.

[0038] In one embodiment, the initial boiling point of the hydrocatalytic diesel is 150-250°C, preferably 190-220°C; the final boiling point is 300-380°C, preferably 330-360°C.

[0039] In one embodiment, the catalysts for the first cracking reaction and the second cracking reaction are the same or different, and each independently comprises zeolite, inorganic oxide and optional clay; based on the total weight of the cracking catalyst, the content of the zeolite is 5-70% by weight, preferably 30-60% by weight; the content of the inorganic oxide is 1-95% by weight, preferably 30-70% by weight; the content of the clay is 1-50% by weight, preferably 5-40% by weight.

[0040] The zeolite includes large-pore zeolite and optional medium-pore zeolite; the medium-pore zeolite is preferably a ZSM series zeolite; the large-pore zeolite is preferably one or more of β zeolite and Y zeolite. Based on the total weight of the zeolite, the content of the large-pore zeolite is 60-100% by weight, preferably 70-90% by weight; the content of the medium-pore zeolite is 0-40% by weight, preferably 10-30% by weight.

[0041] Wherein, the inorganic oxide is silicon dioxide and / or aluminum oxide; and the clay is kaolin and / or halloysite.

[0042] Wherein, the catalyst also contains rare earth elements. The rare earth elements used in the present disclosure are conventionally selected in the art, and this application does not make special requirements. Preferably, the rare earth elements exist in the zeolite of the catalyst, and further preferably, the rare earth elements in the catalyst are mainly derived from Y-type zeolite modified with rare earth elements. In this embodiment, adding rare earth elements to the cracking catalyst can improve the catalytic activity of the cracking catalyst, which is beneficial to improve the activity of the catalytic cracking reaction.

[0043] In a specific embodiment, the method for rare earth modification of Y-type zeolite includes: contacting NaY molecular sieve with rare earth solution or a mixed solution of rare earth solution and ammonium salt, filtering, washing and drying, and then performing a first calcination treatment to obtain rare earth sodium Y molecular sieve; then slurrying the rare earth sodium Y molecular sieve and contacting it with an acid solution, filtering and then mixing it with a rare earth solution, and adjusting the pH value of the slurry to 5-6 with ammonia water, filtering or not filtering, drying, and performing a second calcination treatment to obtain a rare earth Y-type molecular sieve.

[0044] In one embodiment, the method for preparing a cracking catalyst comprises:

[0045] The inorganic oxide source, clay and decationized water are mixed and stirred to form a slurry, wherein the solid content of the slurry is 10-50% by weight; the pH of the above slurry is adjusted to 1-4 with an inorganic acid (such as hydrochloric acid, nitric acid, phosphoric acid or sulfuric acid, etc.), and an aging treatment is performed at this pH value, wherein the temperature of the aging treatment is 20-80°C and the time is 0-2h; then the inorganic oxide is added, stirred for 0.5-1.5 hours to form a colloid, and zeolite is added thereto to form a catalyst slurry, based on the total weight of the solid phase in the catalyst slurry, the content of zeolite is 5-70% by weight, the content of clay is 1-50% by weight, and the content of inorganic oxide is 1-95% by weight, wherein, based on the total weight of the zeolite, the content of large-pore zeolite in the zeolite is 40-100% by weight, and the content of medium-pore zeolite is 0-60% by weight; after continuing to stir, spray drying is performed to form a microsphere catalyst. The microsphere catalyst is then calcined at 400-600° C. for 0.5-2 hours, and then washed with ammonium sulfate at 30-80° C. until the sodium oxide content is less than 0.25% by weight, and then rinsed with deionized water and filtered, and then dried at 100-200° C. to obtain a cracking catalyst; wherein the weight of ammonium sulfate: the weight of the microsphere catalyst: the weight of water = (0.1-1): 1: (5-15).

[0046] In one embodiment, the cracking reaction unit 4 used in the present disclosure includes a first cracking reactor 16, a second cracking reactor 15, a regenerator 19 and a settler 17. The first cracking reactor 16 and the second cracking reactor 15 are arranged in series and the first cracking reactor 16 is arranged downstream of the second cracking reactor 15, so that the material passing through the second cracking reactor 15 can enter the first cracking reactor 16.

[0047] Among them, the second cracking reactor 15 is a dense phase fluidized bed reactor, and the reactor type of the first cracking reactor 16 is a dense phase fluidized bed reactor, a dilute phase transport bed reactor, and a composite reactor consisting of a dense phase fluidized bed reactor and a dilute phase transport bed reactor. The reactor type of the dense phase fluidized bed reactor used in the present disclosure is a bubbling bed reactor, a turbulent bed reactor, or a fast bed reactor; the dilute phase transport bed reactor is a riser reactor.

[0048] In a preferred embodiment, the cracking reaction unit 4 includes a dense fluidized bed reactor, and the dense fluidized bed reactor includes the first cracking reactor 16 and the second cracking reactor 15 , and the second cracking reactor 15 is located upstream of the first cracking reactor 16 .

[0049] The bed density of the dense phase fluidized bed reactor is preferably 300-500 kg / m 3 ; The bed linear velocity is 0.1-4m / s, preferably 0.4-2m / s.

[0050] Part of the first cracking reactor 16 is integrated inside the settler 17 so that the material obtained by the reaction in the first cracking reactor 16 can enter the settler 17. In addition, the first cracking reactor 16 and the settler 17 can also be coaxially arranged or separately arranged according to actual use. Preferably, the first cracking reactor 16 and the settler 17 are coaxially arranged.

[0051] According to actual production needs, the first cracking reactor 16 and the second cracking reactor 15 can be coaxially arranged or separately arranged. Preferably, the first cracking reactor 16 and the second cracking reactor 15 are coaxially arranged.

[0052] In one embodiment, the method further comprises regenerating the spent catalyst obtained from the first cracking reaction, and returning the obtained regenerated catalyst to the cracking reaction unit 4 , preferably, returning the obtained regenerated catalyst to the second cracking reactor 15 .

[0053] In one embodiment, using Figure 2 and Figure 3 The cracking reaction unit 4 performs a cracking reaction to regenerate the spent catalyst obtained by the first cracking reaction, and the obtained regenerated catalyst is returned to the first cracking reactor 16 and / or the second cracking reactor 15.

[0054] In a specific implementation manner, Figure 2 As shown, the first cracking reactor 16 and the second cracking reactor 15 are coaxially arranged and the second cracking reactor 15 is arranged upstream of the first cracking reactor 16. A catalyst outlet to be regenerated is arranged on the side wall of the settler 17; a catalyst inlet to be regenerated, a first regeneration agent outlet and a second regeneration agent outlet are arranged on the side wall of the regenerator 19; a first regeneration agent inlet and a hydrogenated catalytic diesel inlet are arranged on the first cracking reactor 16; a second regeneration agent inlet, a heavy gasoline inlet, a first fresh agent inlet and a pre-lifting medium inlet are arranged on the second cracking reactor 15. The outlet of the catalyst to be regenerated of the settler 17 is connected to the inlet of the catalyst to be regenerated of the regenerator 19 through the inclined tube 18; the first regeneration agent outlet of the regenerator 19 is connected to the first regeneration agent inlet of the first cracking reactor 16 through the first regeneration inclined tube 20, and the second regeneration agent outlet of the regenerator 19 is connected to the second regeneration agent inlet of the second cracking reactor 15 through the second regeneration inclined tube 21; in addition, the hydrogenated catalytic diesel inlet of the first cracking reactor 16 is connected to the hydrogenated catalytic diesel outlet of the hydrogenation reaction unit 2; the pre-lifting medium inlet of the second cracking reactor 15 is used to be connected to the pre-lifting medium source, and the first fresh agent inlet of the second cracking reactor 15 is used to be connected to the fresh agent source, so that the fresh agent 24 can enter the second cracking reactor 15 for reaction.

[0055] In a preferred embodiment, the heavy gasoline inlet is arranged downstream of the first fresh agent inlet, and the second regeneration agent inlet is arranged between the heavy gasoline inlet and the first fresh agent inlet.

[0056] In a preferred embodiment, a second fresh agent inlet is provided on the second regeneration inclined tube 21, and the fresh agent inlet is connected to a fresh agent source, so that the fresh agent 23 can enter the second cracking reactor 15 with the second regenerated catalyst.

[0057] In a preferred embodiment, in order to flexibly adjust the feed and discharge flow rates of the regenerator 19 , flow regulating valves are provided on the regenerated inclined pipe 18 , the first regeneration inclined pipe 20 , and the second regeneration inclined pipe 21 .

[0058] In one embodiment, the pre-lifting medium used in the present disclosure is a conventional choice in the art, and this application does not make any special requirements. For example, the pre-lifting medium may be water vapor and / or dry gas.

[0059] In one embodiment, a steam inlet is further provided at the outlet of the second cracking reactor 15 for communicating with a steam source so that the steam can enter the first cracking reactor 16 .

[0060] In one embodiment, the method further comprises adding a fresh agent into the second cracking reactor.

[0061] In this embodiment, by Figure 2 The cracking reaction unit carries out cracking reaction, so that the catalyst to be regenerated produced by the first cracking reactor 16 enters the regenerator 19 for regeneration to obtain a regenerated catalyst; the regenerated catalyst is returned to the first cracking reactor and the second cracking reactor respectively through the first regeneration inclined tube 20 and the second regeneration inclined tube 21; or, the regenerated catalyst is returned to the second cracking reactor 15 only through the second regeneration inclined tube 21.

[0062] In a specific implementation, using Figure 2The method for treating catalytic diesel to increase the production of light aromatics comprises: allowing the fresh catalyst 24, the second regenerated catalyst and the heavy gasoline component 8 to enter the second cracking reactor 15 under the action of the pre-lifting medium to carry out the second cracking reaction to obtain an oil-agent mixture; allowing the oil-agent mixture, the first regenerated catalyst and the hydrogenated catalytic diesel to enter the first cracking reactor 16 to carry out the first cracking reaction to obtain a mixture containing the cracking reaction product 5 and the catalyst to be regenerated. Allowing the mixture to enter the settler 17 for separation, most of the catalyst to be regenerated in the mixture moves downward under the action of gravity, and the cracking reaction product 5 and a small part of the catalyst to be regenerated in the mixture move upward and enter the cyclone separator for separation, so that a small part of the catalyst to be regenerated returns to the settler 17, and the cracking reaction product 5 exits the settler 17 through the gas collecting chamber. The catalyst to be regenerated is passed through the inclined tube 18 into the regenerator 19, and is regenerated under the action of the oxygen-containing gas to obtain a regenerated catalyst and a regenerated flue gas 22, and the regenerated flue gas 22 is discharged; the regenerated catalyst is divided into a first regenerated catalyst and a second regenerated catalyst, the first regenerated catalyst is returned to the first cracking reactor 16 through the first regeneration inclined tube 20, and the second regenerated catalyst is returned to the second cracking reactor 15 through the second regeneration inclined tube 21 and the fresh agent 23.

[0063] In another specific embodiment, Figure 3 As shown, the first cracking reactor 16 and the second cracking reactor 15 are separately arranged and the second cracking reactor 15 is arranged upstream of the first cracking reactor 16. A catalyst outlet to be regenerated is arranged on the side wall of the settler 17, a catalyst inlet to be regenerated, a first regeneration agent outlet and a second regeneration agent outlet are arranged on the side wall of the regenerator, a first regeneration agent inlet, an oil-agent mixture inlet, a hydrogenated catalytic diesel inlet and a pre-lifting medium inlet are arranged on the first cracking reactor 16; a second regeneration agent inlet, a heavy gasoline inlet, an oil-agent mixture outlet and a first fresh agent inlet are arranged on the second cracking reactor 15; the catalyst outlet to be regenerated of the settler 17 is connected to the catalyst inlet to be regenerated of the regenerator; the first regeneration agent outlet of the regenerator 19 is connected to the first regeneration agent outlet of the first cracking reactor 16 The inlet of the regenerator 19 is connected, the second regeneration agent outlet of the regenerator 19 is connected to the second regeneration agent inlet of the second cracking reactor 15; the oil-agent mixture outlet of the second cracking reactor 15 is connected to the oil-agent mixture inlet of the first cracking reactor 16; the hydrocatalytic diesel inlet of the first cracking reactor 16 is connected to the hydrocatalytic diesel outlet of the hydrogenation reaction unit 2; the pre-lifting medium inlet of the first cracking reactor 16 is connected to the pre-lifting medium source; the heavy gasoline inlet of the second cracking reactor 15 is connected to the heavy gasoline outlet of the product separation device 6; the first fresh agent inlet of the second cracking reactor 15 is used to be connected to the fresh agent source.

[0064] In a preferred embodiment, the hydrocatalytic diesel inlet is arranged downstream of the first regeneration agent inlet and the oil-agent mixture inlet; the first regeneration agent inlet is arranged downstream of the oil-agent mixture inlet.

[0065] In a preferred embodiment, a second fresh agent inlet is provided on the second regeneration inclined tube 21 of the second cracking reactor 15 , and the fresh agent inlet is connected to a fresh agent source so that the fresh agent can be mixed with the second regenerated catalyst and enter the second cracking reactor 15 .

[0066] In a preferred embodiment, in order to flexibly adjust the feed and discharge flow rates of the regenerator 19, flow regulating valves are provided on the regenerated inclined pipe 18, the first regeneration inclined pipe 20, the second regeneration inclined pipe 21 and the mixed material outlet pipeline.

[0067] In this embodiment, by Figure 3 The cracking reaction unit performs cracking reaction, so that the catalyst to be regenerated produced by the first cracking reactor 16 enters the regenerator 19 for regeneration to obtain a regenerated catalyst; the regenerated catalyst is returned to the first cracking reactor 16 and the second cracking reactor 15 through the first regeneration inclined tube 20 and the second regeneration inclined tube 21 respectively, and the reaction materials in the second cracking reactor enter the first cracking reactor.

[0068] In another specific implementation, using Figure 3 The method for treating catalytic diesel to increase the production of light aromatics by the device comprises: the oil mixture at the outlet of the second cracking reactor, the first regenerated catalyst and the hydrogenated catalytic diesel enter the first cracking reactor 16 under the action of the pre-lifting medium to carry out the first cracking reaction, and obtain a mixture containing the cracking reaction product 5 and the catalyst to be regenerated; the mixture enters the settler 17 for separation, most of the catalyst to be regenerated in the mixture moves downward under the action of gravity, the cracking reaction product 5 and a small part of the catalyst to be regenerated in the mixture move upward and enter the cyclone separator for separation, so that the small part of the catalyst to be regenerated returns to the settler 17, and the cracking reaction product exits the settler 17 through the 5 gas collecting chamber. The catalyst to be regenerated is passed through the inclined tube 18 into the regenerator 19, and is regenerated under the action of oxygen-containing gas to obtain a regenerated catalyst and a regenerated flue gas 22; the regenerated flue gas 22 is discharged to separate the regenerated catalyst into a first regenerated catalyst and a second regenerated catalyst, and the first regenerated catalyst is returned to the first cracking reactor 16 through the first regeneration inclined tube 20; the second regenerated catalyst is passed through the second regeneration inclined tube 21 into the second cracking reactor 15 to contact with the heavy gasoline component 8 and the fresh catalyst to carry out a second cracking reaction, and the obtained oil-agent mixture is returned to the first cracking reactor 16.

[0069] In one embodiment, the first cracking reactor 16 and the second cracking reactor 15 may also be independently provided with gas-solid separation equipment and regeneration equipment, wherein the gas-solid separation equipment may be a settler, and the regeneration equipment may be a regenerator, so that the products of the first cracking reactor 16 and the second cracking reactor 15 can be independently separated into spent catalyst and cracking reaction products, and the spent catalyst can be independently regenerated.

[0070] In one embodiment, in order to further improve the separation effect, a cyclone separator is provided on the upper part of the settler 17 and the regenerator 19. The cyclone separator used in the present disclosure is a conventional choice in the art, and this application does not make any requirements. As for the number of cyclone separators, it can be flexibly selected according to actual production needs. Preferably, the number of cyclone separators is 2.

[0071] Among them, a gas collecting chamber is provided at the top of the settler 17, the inlet of the gas collecting chamber is connected with the cracking reaction product outlet of the cyclone separator, and the outlet of the gas collecting chamber is used to be connected with the cracking reaction product outlet, so that the cracking reaction products can be buffered by the gas collecting chamber and then leave the system through the cracking reaction product outlet.

[0072] An oxygen-containing gas distributor is also provided inside the regenerator 19, and the inlet of the oxygen-containing gas distributor extends to the outside of the regenerator 19 to form an oxygen-containing gas inlet.

[0073] In the above embodiment, the catalyst refers to a cracking catalyst; the fresh catalyst is a fresh cracking catalyst; the spent catalyst refers to a cracking catalyst obtained after the first cracking reaction and / or the second cracking reaction; and the regenerated catalyst refers to a spent catalyst obtained after regeneration treatment.

[0074] In one embodiment, the catalyst used in the second cracking reactor 15 includes a second regenerated catalyst and a fresh catalyst, wherein the ratio of the weight of the fresh catalyst to the total weight of the catalyst in the cracking reaction unit 4 is less than 0.2, preferably 0.02-0.18, and more preferably 0.05-0.12.

[0075] In one embodiment, the reaction conditions of the first cracking reaction include: reaction temperature of 520-680°C, reaction time of 1-15s, reaction pressure of 130-450kPa, and catalyst-oil ratio of (1-100):1; preferred reaction conditions include: reaction temperature of 560-600°C, reaction time of 1-8s, reaction pressure of 150-300kPa, and catalyst-oil ratio of (1-30):1; catalyst activity of 40-90, preferably 50-80.

[0076] In one embodiment, the reaction conditions of the second cracking reaction include: reaction temperature of 555-720°C, reaction time of 1-20s, reaction pressure of 130-450kPa, and catalyst-oil ratio of (1-100):1; preferred reaction conditions include: reaction temperature of 580-660°C, reaction time of 3-15s, reaction pressure of 150-300kPa, and catalyst-oil ratio of (5-30):1; catalyst activity is preferably 60-90.

[0077] In one embodiment, the catalyst activity disclosed herein refers to the micro-reaction activity index measured by the method of NB / SH / T 0952-2017.

[0078] In one embodiment, the product separation and processing device and method described in the present disclosure are conventionally selected in the art, and this application does not make any requirements. It only needs to be able to separate the cracking reaction products into other products, light gasoline components, heavy gasoline components and diesel components.

[0079] Among them, the main components of other products include H 2 -C4 gas components, diesel and heavy oil fractions; light gasoline components are mainly composed of C6-C8 components; heavy gasoline components are mainly composed of C9-C12 components.

[0080] The initial boiling point of the light gasoline component is 20-50°C; the distillation cut point of the light gasoline component and the heavy gasoline component is 120-150°C; and the distillation cut point of the diesel component and the heavy gasoline component is 200-250°C.

[0081] In one embodiment, the apparatus and method for separation and treatment of aromatics are conventionally selected in the art, and the present application does not make any requirements. It only needs to be able to separate the light fraction of gasoline into benzene products, toluene products and xylene products. For example, the present application uses aromatic extraction technology for separation, and the aromatic residue oil can be returned to the catalytic cracking reactor to continue the reaction, and its refining position can be the same as that of the hydrogenated catalytic diesel.

[0082] In one embodiment, if the feedstock of the first cracking reaction includes a heavy oil feedstock, the first cracking reactor 16 may be a cracking reactor for the heavy oil feedstock; the method further includes allowing the hydrocatalytic diesel and the heavy oil feedstock to enter the first cracking reactor 16 for the first cracking reaction. The hydrocatalytic diesel contacts the catalyst for reaction before the heavy oil feedstock. In this embodiment, in order to allow the hydrocatalytic diesel to contact the catalyst for reaction before the heavy oil feedstock, a heavy oil feedstock inlet may be provided above the hydrocatalytic diesel inlet of the first cracking reactor, and a first regenerated catalyst inlet may be provided below the hydrocatalytic diesel inlet, or a first regenerated catalyst inlet may be provided between the hydrocatalytic diesel inlet and the heavy oil feedstock inlet.

[0083] The following examples will further illustrate the present invention, but are not intended to limit the present invention. The properties of the hydrogenated catalytic diesel obtained by hydrogenation treatment in the examples and comparative examples are shown in Table 1. The heavy oil raw material used in the examples is heavy oil, and the properties of the heavy oil are shown in Table 2.

[0084] Table 1 Properties of Hydrogenated Catalytic Diesel

[0085]

[0086]

[0087] Table 2 Properties of heavy oil feedstock

[0088]

[0089] Preparation Example 1

[0090] The preparation method of rare earth Y type molecular sieve (REY) comprises: contacting NaY molecular sieve with rare earth solution or a mixed solution of rare earth solution and ammonium salt, filtering, washing with water, drying, and then performing a first roasting treatment to obtain rare earth sodium Y molecular sieve; then slurrying the rare earth sodium Y molecular sieve and contacting it with an acid solution, filtering and then mixing it with a rare earth solution, and adjusting the pH value of the slurry to 6 with ammonia water, filtering or not filtering, drying, and performing a second roasting treatment to obtain rare earth Y type molecular sieve (REY).

[0091] The method for preparing cracking catalyst C1 comprises: mixing aluminum sol and kaolin, and preparing them into a slurry with a solid content of 40% by weight with decationized water, stirring evenly, adjusting the pH of the slurry to 4 with an inorganic acid (such as hydrochloric acid, nitric acid, phosphoric acid or sulfuric acid), maintaining the pH value, adding aluminum sol after standing and aging for 1 hour at 60°C, stirring for 1 hour to form a colloid, adding rare earth Y molecular sieve (REY) to form a catalyst slurry (solid content of 35% by weight), wherein the weight of REY: the weight of kaolin: the weight of aluminum sol = 50:34:16, continuing to stir and spray drying to form a microsphere catalyst. Then, the microsphere catalyst is roasted at 500°C for 1 hour, and then washed with ammonium sulfate at 60°C (wherein the weight of ammonium sulfate: the weight of microsphere catalyst: the weight of water = 0.5:1:10) until the sodium oxide content is less than 0.25% by weight, followed by rinsing with deionized water and filtering, and then drying at 110°C to obtain cracking catalyst C1.

[0092] Preparation Example 2

[0093] The preparation method of rare earth Y-type molecular sieve (REY) is the same as that of Preparation Example 1;

[0094] The method for preparing cracking catalyst C2 includes: mixing aluminum sol and kaolin, and preparing them into a slurry with a solid content of 40% by weight with decationized water, stirring evenly, adjusting the pH of the slurry to 4 with an inorganic acid (such as hydrochloric acid, nitric acid, phosphoric acid or sulfuric acid), maintaining the pH value, adding aluminum sol after standing and aging at 60°C for 1 hour, stirring for 1 hour to form a colloid, adding ZSM-5 and REY to form a catalyst slurry (solid content is 35% by weight), wherein the weight of ZSM-5 molecular sieve: the weight of REY: the weight of kaolin: the weight of aluminum sol = 15:35:34:16, and continuing to stir and spray drying to form a microsphere catalyst. The microsphere catalyst was then calcined at 500°C for 1 hour, and then washed with ammonium sulfate at 60°C (wherein the weight of ammonium sulfate: the weight of microsphere catalyst: the weight of water = 0.5:1:10) until the sodium oxide content was less than 0.25% by weight, followed by rinsing with deionized water and filtering, and then drying at 110°C to obtain cracking catalyst C2.

[0095] Test Example 1

[0096] The test is carried out according to the 460°C micro-reaction activity index determination method in NB / SH / T 0952-2017, and the obtained micro-reaction activity index is the catalytic activity of the cracking catalyst.

[0097] Example 1

[0098] use Figure 1 systems and Figure 2 The method for increasing the production of light aromatics by treating catalytic diesel in the cracking reaction unit 4 comprises:

[0099] The catalytic diesel 1 and hydrogen enter the hydrogenation reaction unit 2 for hydrogenation treatment to obtain hydrogenated catalytic diesel 3, wherein the conditions for the hydrogenation treatment include a reaction temperature of 380°C, a hydrogen partial pressure of 10 MPa, and a volume space velocity of 1 h -1 , hydrogen to oil volume ratio is 1200Nm 3 / m 3 .

[0100] The oil mixture, the first regenerated catalyst and the hydrogenated catalytic diesel 3 from the second cracking reactor 15 are introduced into the first cracking reactor 16 for the first cracking reaction to obtain a mixture containing the cracking reaction product 5 and the catalyst to be regenerated. The mixture is introduced into the settler 17 for separation, and most of the catalyst to be regenerated in the mixture moves downward under the action of gravity, and the cracking reaction product 5 and a small part of the catalyst to be regenerated in the mixture move upward and enter the cyclone separator for separation, so that a small part of the catalyst to be regenerated returns to the settler 17, and the cracking reaction product 5 exits the settler 17 through the gas collecting chamber. The catalyst to be regenerated enters the regenerator 19 through the inclined tube to be regenerated 18, and is regenerated under the action of oxygen-containing gas to obtain a regenerated catalyst and a regenerated flue gas 22, and the regenerated flue gas 22 is discharged; the regenerated catalyst is divided into the first regenerated catalyst and the second regenerated catalyst, and the first regenerated catalyst is returned to the first cracking reactor 16 through the first regeneration inclined tube 20, and the second regenerated catalyst is returned to the second cracking reactor 15 through the second regeneration inclined tube 21;

[0101] The cracking reaction product 5 is made to enter the product separation device 6 for the first separation to obtain other products 10, light gasoline component 7, heavy gasoline component 8 and diesel component 9; the fresh agent, the second regenerated catalyst and the heavy gasoline component 8 are made to enter the second cracking reactor 15 under the action of the pre-lifting medium (steam) for the second cracking reaction to obtain the oil agent mixture; the initial distillation of the light gasoline component 7 is 40°C, the cut point of the light gasoline component 7 and the diesel component 9 is 150°C, and the cut point of the heavy gasoline component 8 and the diesel component 9 is 210°C; the light gasoline component 7 is made to enter the aromatic separation device 11 for the second separation to obtain a benzene product 12, a toluene product 13 and a xylene product 14; the diesel component 9 is returned to the hydrogenation reaction unit, and the ratio of the weight of the fresh agent to the total weight of the catalyst of the cracking reaction unit 4 is 0.18:1; the other products are further separated to obtain dry gas, ethylene, liquefied petroleum gas, propylene and gasoline. The conditions and product properties of the cracking reaction are shown in Table 3.

[0102] Example 2

[0103] The method for treating catalytic diesel and increasing the production of light aromatics is the same as in Example 1, except that the reaction temperature of the second cracking reaction is 620° C. The conditions of the cracking reaction and the properties of the products are shown in Table 3.

[0104] Example 3

[0105] The method for treating catalytic diesel and increasing the production of light aromatics is the same as in Example 1, except that the catalyst-to-oil ratio of the second cracking reaction is 15:1. The conditions of the cracking reaction and the properties of the products are shown in Table 3.

[0106] Example 4

[0107] The method for treating catalytic diesel and increasing the production of light aromatics is the same as in Example 1, except that: Figure 1 A system is used for cracking reaction, wherein the first cracking reactor and the second cracking reactor in the cracking reaction unit 4 are independently provided with gas-solid separation equipment and regeneration equipment, so that the source of the catalyst for the first cracking reaction is the regenerated catalyst, wherein the ratio of the weight of the fresh catalyst to the total weight of the catalyst in the cracking reaction unit 4 is 0.02:1; the conditions of the cracking reaction and the properties of the products are shown in Table 3.

[0108] Example 5

[0109] The method for treating catalytic diesel and increasing the production of light aromatics is the same as that of Example 1, except that the first regeneration inclined tube 20 is closed so that the source of the catalyst for the first cracking reaction is the catalyst to be regenerated produced by the second cracking reaction, wherein the weight of the fresh catalyst is 0.02:1 to the total weight of the catalyst in the cracking reaction unit 4. The conditions of the cracking reaction and the properties of the products are shown in Table 3.

[0110] Example 6

[0111] The method for treating catalytic diesel and increasing the production of light aromatics is the same as in Example 1, except that the cracking catalyst C1 is replaced by an equal weight of the cracking catalyst C2, wherein the ratio of the weight of the fresh catalyst to the total weight of the catalyst in the cracking reaction unit 4 is 0.02:1. The conditions of the cracking reaction and the properties of the products are shown in Table 3.

[0112] Example 7

[0113] The method for treating catalytic diesel to increase the production of light aromatics is the same as in Example 1, except that the bed density of the second cracking reactor is 250 kg / m 3 The cracking reaction conditions and product properties are shown in Table 3.

[0114] Example 8

[0115] The method for treating catalytic diesel and increasing the production of light aromatics is the same as in Example 1, except that the first cracking reactor is a cracking reactor for heavy oil feedstock, and the hydrogenated catalytic diesel is contacted with the catalyst before the heavy oil. The conditions of the cracking reaction and the properties of the products are shown in Table 3.

[0116] Example 9

[0117] The method for treating catalytic diesel and increasing the production of light aromatics is the same as in Example 1, except that the reaction conditions of the first cracking reaction are different. The reaction conditions and product properties are shown in Table 4.

[0118] Example 10

[0119] The method for treating catalytic diesel and increasing the production of light aromatics is the same as that in Example 1, except that the ratio of the weight of the fresh agent to the total weight of the catalyst in the cracking reaction unit 4 is 0.02:1. The reaction conditions and product properties are shown in Table 4.

[0120] Embodiment 11

[0121] The method for treating catalytic diesel and increasing the production of light aromatics is the same as in Example 1, except that no fresh agent is added during the second cracking reaction in the second cracking reactor 15. The reaction conditions and product properties are shown in Table 4.

[0122] Comparative Example 1

[0123] use Figure 1 The method for increasing the production of light aromatics by treating catalytic diesel with a system is the same as that in Example 1, except that Figure 4 The cracking reaction unit 4 is used for cracking reaction, that is, the reactor composed of dense phase fluidized bed reactor and riser reactor connected in series is replaced by riser reactor 25. The conditions of the cracking reaction and the properties of the products are shown in Table 4.

[0124] Comparative Example 2

[0125] The method for treating catalytic diesel to increase the production of light aromatics is the same as in Example 5, except that the cracking catalyst C1 is replaced by an equal weight of cracking catalyst CDOS. The conditions of the cracking reaction and the properties of the products are shown in Table 4.

[0126] Comparative Example 3

[0127] The method for treating catalytic diesel to increase the production of light aromatics is the same as in Example 1, except that the heavy gasoline component is directly discharged. The cracking reaction conditions and product properties are shown in Table 4.

[0128] Table 3 Cracking reaction conditions and product properties in the examples

[0129]

[0130]

[0131] Table 4 Cracking reaction conditions and product properties in comparative examples

[0132]

[0133]

[0134] As can be seen from the table, according to the comparison of the data of Examples 1-11 and Comparative Examples 1-3, it can be seen that the technical solution of the present disclosure can avoid the problems of high hydrogen consumption, harsh operating conditions and aromatics loss caused by the production of light aromatics by hydroprocessing. According to the comparison of the data in Example 1, Example 2 and Example 3, the second cracking reaction of the present application performs non-hydrogen catalytic cracking of the heavy gasoline component under the conditions of a temperature of 580-660°C and a catalyst-oil ratio of (15-25):1, and can obtain a higher BTX yield; according to the comparison of the data in Example 1, Example 6 and Comparative Example 2, it can be seen that when the catalytic activity of the catalyst in the second cracking reactor meets 50-99, a higher BTX yield can be obtained; according to the comparison of the data in Example 1, Example 7 and Comparative Example 1, it can be seen that the bed density of the second cracking reactor is 180-700kg / m 3 , a higher BTX yield can be obtained, and the bed density of the dense phase fluidized bed reactor is 300-500kg / m 3 , which can further improve the yield of BTX; according to the comparison of the data in Example 1, Example 10 and Example 11, it can be seen that by adding a fresh agent in the second cracking reactor, a higher yield of BTX can be obtained; according to the comparison of the data in Example 1 and Comparative Example 3, it can be seen that by allowing the heavy fraction to react in the second cracking reactor first and then enter the first cracking reactor for further reaction, a higher yield of BTX can be obtained.

[0135] The preferred embodiments of the present disclosure are described in detail above in conjunction with the accompanying drawings; however, the present disclosure is not limited to the specific details in the above embodiments. Within the technical concept of the present disclosure, a variety of simple modifications can be made to the technical solution of the present disclosure, and these simple modifications all fall within the protection scope of the present disclosure.

[0136] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, the present disclosure will not further describe various possible combinations.

[0137] In addition, various embodiments of the present disclosure may be arbitrarily combined, and as long as they do not violate the concept of the present disclosure, they should also be regarded as the contents disclosed by the present disclosure.

Claims

1. A method for treating catalytic diesel and increasing the production of light aromatics, characterized in that: The method includes: The catalytic diesel is fed into a hydrogenation reaction unit for hydrogenation treatment to obtain hydrogenated catalytic diesel, and the hydrogenated catalytic diesel is fed into a first cracking reactor of a cracking reaction unit for a first cracking reaction, and a cracking reaction product is obtained after gas-solid separation; Subjecting the cracking reaction product to product separation treatment to obtain other products, a light gasoline component, a heavy gasoline component and a diesel component; returning the diesel component to the hydrogenation reaction unit; Allowing the heavy gasoline component to enter the second cracking reactor of the cracking reaction unit to perform a second cracking reaction, and allowing the resulting oil-agent mixture to enter the first cracking reactor; Subjecting the light gasoline component to an aromatics separation process to obtain a benzene product, a toluene product and a xylene product; The second cracking reactor is a dense phase fluidized bed reactor, and the bed density of the dense phase fluidized bed reactor is 180-700 kg / m 3 ; The catalyst activity of the catalyst in the second cracking reactor is 50-99.

2. The method according to claim 1, characterized in that The initial distillation point of the light gasoline component is 20-50°C; the distillation cut point of the light gasoline component and the heavy gasoline component is 120-150°C; the distillation cut point of the diesel component and the heavy gasoline component is 200-250°C.

3. The method according to claim 1, characterized in that The initial distillation point of the hydrogenated catalytic diesel is 150-250°C, and the final distillation point is 300-380°C.

4. The method according to claim 1, characterized in that: The reaction conditions of the first cracking reaction include: reaction temperature of 520-680°C, preferably 560-600°C; reaction time of 1-15s, preferably 1-8s; catalyst-oil ratio of (1-100):1, preferably (1-30):1; The reaction conditions of the second cracking reaction include: reaction temperature of 555-720°C, preferably 580-660°C; catalyst-oil ratio of (1-100):1, preferably (5-30):1; catalyst activity of 60-90.

5. The method according to claim 1, characterized in that The catalysts for the first cracking reaction and the second cracking reaction are the same or different, and each independently comprises a zeolite, an inorganic oxide, and optionally clay; Based on the total weight of the catalyst, the content of the zeolite is 5-70% by weight, the content of the inorganic oxide is 1-95% by weight, and the content of the clay is 1-50% by weight.

6. The method according to claim 5, characterized in that The zeolite includes large pore zeolite and optionally medium pore zeolite; Based on the total weight of the zeolite, the content of the large-pore zeolite is 60-100% by weight, and the content of the medium-pore zeolite is 0-40% by weight.

7. The method according to claim 6, characterized in that The medium-pore zeolite is selected from ZSM zeolite; the large-pore zeolite is selected from one or more of β zeolite and Y zeolite; The inorganic oxide includes silicon dioxide and / or aluminum oxide; The clay is kaolin and / or halloysite.

8. The method according to claim 7, characterized in that The catalyst contains rare earth elements. Preferably, the large-pore zeolite is Y-type zeolite modified by rare earth elements.

9. The method according to claim 1, characterized in that: The method further comprises regenerating the spent catalyst obtained from the first cracking reaction, and returning the obtained regenerated catalyst to the cracking reaction unit.

10. The method according to claim 1, characterized in that The method further includes adding a fresh agent to the second cracking reactor.

11. The method according to claim 10, characterized in that The ratio of the weight of the fresh agent to the total weight of the catalyst in the cracking reaction unit is 0.2 or less.

12. The method according to claim 9, characterized in that The cracking reaction unit also includes a regenerator; The method further includes allowing the catalyst to be regenerated to enter the regenerator for regeneration to obtain a regenerated catalyst; allowing the regenerated catalyst to return to the first cracking reactor through a first regeneration inclined tube and to return to the second cracking reactor through a second regeneration inclined tube; Optionally, a fresh agent inlet is provided on the second regeneration inclined tube.

13. The method according to claim 1, characterized in that The dense phase fluidized bed reactor is an upward reactor or a downward reactor.

14. The method according to claim 1, characterized in that The bed density of the dense phase fluidized bed reactor is 300-500 kg / m 3 , the bed linear speed is 0.4-2m / s.

15. The method according to claim 1, characterized in that The first cracking reactor and the second cracking reactor are arranged in series and the first cracking reactor is arranged downstream of the second cracking reactor.

16. The method according to claim 15, characterized in that The first cracking reactor and the second cracking reactor are coaxially arranged.

17. The method according to claim 1, characterized in that The conditions of the hydrotreatment include: reaction temperature of 330-450°C, hydrogen partial pressure of 6-25 MPa, volume space velocity of 0.1-2 h -1 , hydrogen to oil volume ratio is 1000-2000Nm 3 / m 3 .

18. The method according to claim 1, characterized in that The first cracking reactor is a dilute phase transport bed reactor and / or a dense phase fluidized bed reactor.

19. The method according to claim 1, characterized in that The first cracking reactor is a cracking reactor for heavy oil feedstock; Optionally, the hydrocatalytic diesel is contacted with the catalyst in the first cracking reactor before the heavy oil feedstock.

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