Two-stage downflow catalytic conversion process and system

Abstract

The application discloses a two-stage down-flow pipe fluidized catalytic conversion method and system. The system comprises a high-stage down-flow pipe reactor and a low-stage down-flow pipe reactor, and gas-solid separation devices are arranged at the outlets of the high-stage down-flow pipe reactor and the low-stage down-flow pipe reactor; one or two regenerators are arranged; the upper portions of the two-stage down-flow pipe reactors are communicated with a regenerative inclined pipe; a catalyst regulating valve is arranged on the regenerative inclined pipe; and the regulating valve is interlocked with the outlet temperature of the down-flow pipe reactor. The reaction temperatures of the high-stage down-flow pipe reactor and the low-stage down-flow pipe reactor can be independently controlled, and the method and system are especially suitable for catalytic cracking / cracking processes with short reaction time and large oil dosage, and can produce more low-carbon olefins.

Description

TECHNICAL FIELD

[0001] The present application relates to a downflow bed fluidized catalytic cracking / cracking process and system for producing petrochemicals, such as olefins and aromatics. BACKGROUND

[0002] Catalytic cracking / cracking is an important means of lightening heavy oil, and "reducing oil and increasing aromatics" is a general trend of refinery transformation. Increasing the reaction depth of catalytic cracking feedstock to produce more low-carbon olefins is an inevitable requirement to achieve this goal. Increasing the catalyst to oil ratio and the reaction temperature is a common means to achieve the above requirements. Although high reaction temperature can increase the conversion depth of the feedstock, it can also cause the intensification of thermal cracking reaction, resulting in rapid increase of dry gas and coke yield, although the oil is reduced, but the aromatics are not increased. The operating conditions of low temperature, large catalyst to oil ratio and short reaction time are the way to achieve the purpose of "reducing oil and increasing aromatics".

[0003] The current catalytic cracking unit is basically an "upward pipe" reactor in which oil and catalyst contact at the bottom of the riser pipe and move upward. It is difficult to achieve the operating conditions of large catalyst to oil ratio and short reaction time due to the constraints of gravity and actual engineering conditions. The downflow bed reactor is gas-solid co-current flow against the gravitational field, the radial flow is more uniform, there is no axial back mixing of catalyst, and the radial distribution of particle concentration and velocity is obviously improved compared with the upward riser pipe. It is particularly suitable for catalytic conversion reactions with ultra-short contact (reaction) time (usually 1-3 times shorter than the riser pipe) and ultra-large catalyst to oil ratio (usually 1-3 times larger than the riser pipe), such as deep catalytic conversion of residual oil, catalytic thermal cracking, catalytic cracking of gasoline to produce olefins, etc. It can fully utilize the initial activity of the catalyst, improve the light oil yield, and reduce the generation of dry gas and coke.

[0004] Patent CN 108753356A discloses a multi-stage countercurrent catalytic cracking / cracking system and method. In this method, the feedstock enters from the bottommost downflow pipe reactor, the oil gas separated from each stage is returned to the upper downflow pipe reactor, and the product flows out from the gas-solid separation device of the topmost downflow pipe reactor. The regenerant enters from the topmost downflow pipe reactor, the catalyst separated from each stage enters the next downflow pipe reactor, and the catalyst enters the stripper from the gas-solid separation device of the bottommost downflow pipe reactor. In this scheme, only one regeneration inclined pipe is provided, which can only supply one way of regenerant to the reaction system, and can only control one temperature point, and the reaction temperature of each downflow pipe cannot be independently controlled, while different hydrocarbon compositions have their own appropriate reaction temperature.

[0005] CN112538372A discloses an integrated method and device for catalytic cracking of heavy oil and co-production of synthesis gas. The method uses a cracking-gasification coupled reactor with internal cracking and gasification sections as the reactor; heavy oil feedstock enters the cracking section at the top of the coupled reactor and contacts the fluidized bed material containing cracking catalyst to undergo catalytic cracking reaction, producing light oil gas and coke, which is carried down by the bed material into the gasification section at the bottom of the coupled reactor to undergo gasification reaction and generate synthesis gas; the synthesis gas rises into the cracking section and combines with the light oil gas to exit the coupled reactor into a gas-solid separation system, at least a first stage of gas-solid separation is performed, the separated bed material particles are collected and divided into two parts, which are returned to the cracking section and the gasification section respectively to form a primary and secondary circulation; the purified oil gas output from the gas-solid separation system is subjected to oil gas fractionation to collect light oil and synthesis gas products. This scheme is mainly used for the production of synthesis gas and light oil products.

[0006] CN113897216A discloses a catalytic cracking method and system. The catalytic cracking method includes a combined process of catalytic cracking, hydro-upgrading and aromatic extraction. The process can maximize the production of low-carbon olefins while co-producing benzene, toluene and xylene, optimizing product distribution.a. Heavy feedstock is sent to the upper part of the downflow reactor (2) to contact the first catalytic cracking catalyst from the top of the downflow reactor (2) and undergo a first catalytic cracking reaction from top to bottom, producing a first product and a first spent catalyst;b. The first product and the first spent catalyst obtained in step a are sent to the bottom of the fluidized bed reactor (3);c. Light feedstock and hydro-upgraded oil are sent to the lower part of the riser reactor (9) to contact the second catalytic cracking catalyst from the bottom of the riser reactor (9) and undergo a second catalytic cracking reaction from bottom to top, producing a second product and a second spent catalyst;d. The second product and the second spent catalyst obtained in step c are sent to the fluidized bed reactor to mix with the first product and the first spent catalyst, and contact the third catalytic cracking catalyst and undergo a third catalytic cracking reaction, producing a third product and a third spent catalyst, which is sent to the regenerator (7) for regeneration to obtain regenerated catalyst, etc. This scheme combines downflow bed and conventional upflow fluidized bed for catalytic cracking, which may cause long reaction time and excessive cracking, resulting in high dry gas and coke yield.

[0007] CN113897215A discloses a method and system for catalytic cracking of heavy feedstock, which comprises catalytic cracking of heavy feedstock in a catalytic cracking reaction system, the catalytic cracking reaction system comprising a main downflow tube reactor, an auxiliary downflow tube reactor and a fluidized bed reactor, wherein the material outlets of the main downflow tube reactor and the auxiliary downflow tube reactor are both connected with the fluidized bed reactor. The method of the present application also combines hydro-upgrading and aromatic extraction, which can maximize the conversion of heavy oil feedstock into low-carbon olefins rich in propylene and ethylene, while co-producing benzene, toluene and xylene and other chemical raw materials. The first product, the first semi-catalyst, the second product and the second semi-catalyst need to be sent to the fluidized bed reactor for the third catalytic cracking reaction. The scheme is a combination of downflow bed and conventional fluidized bed, which may cause the problem of long reaction time and excessive cracking to cause high dry gas and coke yield.

[0008] CN 110540860 A discloses a process and system for catalytic cracking using double downflow tubes, which relates to a process and system for catalytic cracking using double downflow tubes, which comprises: a, feeding heavy feedstock into the upper part of the first downflow tube reactor and contacting with the first catalytic cracking catalyst from the top of the first downflow tube reactor and performing first catalytic cracking reaction from top to bottom; b, feeding light feedstock into the upper part of the second downflow tube reactor and contacting with the second catalytic cracking catalyst from the top of the second downflow tube reactor and performing second catalytic cracking reaction from top to bottom; c, feeding the first product and the first semi-catalyst obtained in step a and the second product and the second semi-catalyst obtained in step b into the fluidized bed reactor and contacting with the third catalytic cracking catalyst and performing third catalytic cracking reaction to obtain third product and catalyst. The scheme is a combination of downflow bed and conventional fluidized bed, which may cause the problem of long reaction time and excessive cracking to cause high dry gas and coke yield.

[0009] Although various catalytic conversion methods and systems exist in the prior art, there are still various deficiencies in these methods and systems. Therefore, it is urgent to provide a new catalytic conversion method and system. SUMMARY

[0010] The purpose of the present application is to overcome the deficiency that the reaction temperature of each downflow tube in the existing multi-stage downflow tube cannot be independently controlled, and to provide a two-stage downflow tube fluidized catalytic conversion method and system, in which the reaction temperatures of the two-stage downflow tubes can be independently controlled.

[0011] To achieve the above purpose, the present application provides a two-stage downflow tube fluidized catalytic conversion method, which comprises the following steps:

[0012] A. Raw material A is injected from the top of the lower-stage downflow reactor. The regenerator is connected to the lower-stage downflow reactor through a lower regeneration inclined pipe. Raw material A reacts with the catalyst from the regenerator and the upper-stage gas-solid separation unit in the lower-stage downflow reactor. The product enters the lower-stage gas-solid separation unit for separation to obtain the first catalyst and the first oil and gas. The first oil and gas output system enters the fractionation tower, and the first catalyst enters the regenerator for regeneration through the waiting inclined pipe and the conveying pipe.

[0013] B. Raw material B enters the top of the upper downflow reactor. The regenerator is connected to the upper downflow reactor through the upper regeneration inclined pipe. Raw material B and the regenerator from the regenerator react in the upper downflow reactor. The product enters the upper gas-solid separation device for separation, and the second catalyst and the second oil and gas are obtained. The second catalyst is input into the top of the lower downflow reactor and reacts with raw material A. The second oil and gas output system enters the fractionation tower.

[0014] The upper regeneration inclined tube is equipped with a first regulating valve, the opening degree of which controls the temperature at the outlet of the upper-stage downflow reactor; the lower regeneration inclined tube is equipped with a second regulating valve, the opening degree of which controls the temperature at the outlet of the lower-stage downflow reactor; the catalyst in the upper regeneration inclined tube contains more carbon deposits than the catalyst in the lower regeneration inclined tube.

[0015] The two-stage downflow fluidized bed catalytic conversion method of the present invention includes, but is not limited to, tubular reactors, with an inner diameter of 0.5-5 meters and a height of 5-50 meters.

[0016] In the two-stage downflow fluidized bed catalytic conversion method of the present invention, the upper-stage gas-solid separation device and the lower-stage gas-solid separation device can be at least one of a gas-solid rapid separation device and a stripper; the upper-stage gas-solid separation device is preferably a gas-solid rapid separation device, and the lower-stage gas-solid separation device is preferably a riser catalytic cracking device using a stripper.

[0017] In the two-stage downflow catalytic conversion method of the present invention, the opening degree of the first regulating valve is 10-80%.

[0018] In the two-stage downflow catalytic conversion method of the present invention, the opening degree of the second regulating valve is 10-80%.

[0019] The two-stage downflow fluidized bed catalytic conversion method of the present invention includes one or two regenerators, with a regeneration temperature of 650-780°C. The regenerators can provide regenerators with different temperatures or carbon contents to the upper and lower downflow reactors.

[0020] When the number of the regenerators is 1, the upper regenerative inclined pipe is communicated with the middle part of the regenerator, the lower regenerative inclined pipe is communicated with the bottom of the regenerator, and the regenerants of the upper and lower downer reactors come from different positions of the regenerator. The carbon content of the regenerant can be adjusted by adjusting the flow of the main air of the regenerator, and the carbon content of the catalyst in the upper and lower regenerative inclined pipes is controlled to be 0-1wt% by adjusting the main air. The flow of the main air is not particularly limited in the present application, and can be adjusted according to the carbon content of the catalyst.

[0021] When the number of the regenerators is 2, one of the regenerators is communicated with the lower regenerative inclined pipe, and the other of the regenerators is communicated with the upper regenerative inclined pipe; the two regenerators are communicated through a two-regenerator communication pipeline, and a third adjusting valve is arranged on the two-regenerator communication pipeline. The two regenerators can be arranged in a coaxial and stacked manner or independently. When two regenerators are used, the temperature and carbon content of the regenerants supplied by the upper and lower regenerative inclined pipes can be independently adjusted. The carbon content of the regenerant can be adjusted by adjusting the flow of the main air of the regenerator, and the carbon content of the catalyst in the upper and lower regenerative inclined pipes is controlled to be 0-1wt% by adjusting the main air. The flow of the main air is not particularly limited in the present application, and can be adjusted according to the carbon content of the catalyst.

[0022] In the two-stage downer fluidized catalytic conversion method of the present application, the temperature of the outlet of the upper downer reactor is 480-750℃, the temperature of the outlet of the lower downer reactor is 480-650℃, the operating pressure of the upper and lower downer reactors is 0.1-0.4MPa (gauge pressure), the reaction time of the upper and lower downer reactors is 0.1-2s, and the catalyst / oil ratio is 4-40.

[0023] In the two-stage downer fluidized catalytic conversion method of the present application, the raw material A is a high-boiling petroleum hydrocarbon with a mass fraction of distillate with a true boiling point of 200℃ or higher of more than 90%, such as atmospheric heavy oil, vacuum residue, hydrocracked wax oil, etc., or a mixture of several thereof, which is used as the feed of the lower downer reactor.

[0024] The raw material B is one or more of low-boiling petroleum hydrocarbons with a mass fraction of distillate with a true boiling point of 360℃ or lower of more than 90%, including one or more of propane, C4 components, naphtha components, gasoline components, and diesel components, which is used as the feed of the upper downer reactor.

[0025] The present application also provides a two-stage downer fluidized catalytic conversion system, which comprises:

[0026] an upper downer reactor;

[0027] a top portion of the upper downer reactor;

[0028] a lower downer reactor, a top portion of which is communicated with a bottom portion of the upper gas-solid separation device;

[0029] a lower gas-solid separation device, a bottom portion of which is communicated with the lower downer reactor; and

[0030] a regenerator, which is communicated with the upper downer reactor, the lower downer reactor and the lower gas-solid separation device respectively; the regenerator is communicated with the top portion of the upper downer reactor through an upper regenerative inclined pipe, the regenerator is communicated with the lower downer reactor through a lower regenerative inclined pipe, and the regenerator is communicated with the bottom portion of the lower gas-solid separation device through a standby regenerative inclined pipe.

[0031] The method and system of the present application are provided with two downer reactors, i.e. an upper downer reactor and a lower downer reactor, raw material A is introduced into the top portion of the lower downer reactor and reacts with catalysts, the reacted catalysts are introduced into the regenerator to be regenerated to obtain regenerated catalysts which are then introduced into the upper downer reactor or the lower downer reactor to react, thereby realizing the recycling of the catalysts; raw material B is introduced into the upper downer reactor to react with the high-temperature regenerated catalysts from the regenerator. The oil and gas products reacted from raw material A and raw material B are introduced into a fractionating device together. The method and system of the present application are provided with two regenerative inclined pipes, i.e. an upper regenerative inclined pipe and a lower regenerative inclined pipe. The inlet of the upper regenerative inclined pipe is communicated with the regenerator, the outlet of the upper regenerative inclined pipe is communicated with the top portion of the upper downer reactor, and the upper regenerative inclined pipe provides the upper downer reactor with regenerated catalysts. The inlet of the lower regenerative inclined pipe is communicated with the regenerator, the outlet of the lower regenerative inclined pipe is communicated with the top portion of the lower downer reactor, and the lower regenerative inclined pipe provides the lower downer reactor with regenerated catalysts. A first regulating valve is arranged on the upper regenerative inclined pipe, the first regulating valve is interlocked with the outlet temperature of the upper downer reactor, a second regulating valve is arranged on the lower regenerative inclined pipe, and the second regulating valve is interlocked with the outlet temperature of the lower downer reactor, so that the reaction temperatures of the upper downer reactor and the lower downer reactor can be independently controlled.

[0032] The method and system of the present application adopt the reactor type of two-stage downer, can realize the operating conditions of large oil dosage and short reaction time, and the regenerator can be provided with one or two regenerators to supply the upper downer reactor and the lower downer reactor with regenerated catalysts with different carbon contents, and the reaction temperatures of the upper downer reactor and the lower downer reactor can be independently controlled.

[0033] The method and system of the present application can effectively improve the product distribution of catalytic cracking / cleavage, increase the oil and hydrogen, make full use of the short reaction time of downpipe reactor and the two-stage catalyst reaction relay advantage, reduce the yield of dry gas and coke, and increase the yield of low-carbon olefins.

[0034] In the method and system of the present application, the catalysts in the upper downpipe reactor and the lower downpipe reactor come from different positions of the regenerator or from different regenerators, the carbon deposition content attached to the catalysts is different, and the carbon deposition content can be adjusted by adjusting the flow of the main air of the regenerator, and a certain carbon deposition content can produce beneficial cracking effect on light distillate.

[0035] In the method and system of the present application, two regeneration inclined pipes are arranged, the upper downpipe reactor and the lower downpipe reactor can independently obtain regenerated catalyst from the regenerator, and the catalyst with appropriate activity can be provided for each downpipe reactor; the outlet temperatures of the upper downpipe reactor and the lower downpipe reactor are respectively linked with the first regulating valve and the second regulating valve of the respective regeneration inclined pipe, and the outlet temperatures of each downpipe reactor can be independently and flexibly adjusted. BRIEF DESCRIPTION OF DRAWINGS

[0036] Figure 1 The schematic diagram of the two-stage downpipe fluidized catalytic conversion system provided with one regenerator (single regenerator) of the present application.

[0037] Figure 2 The schematic diagram of the two-stage downpipe fluidized catalytic conversion system provided with two regenerators (double regenerators) of the present application.

[0038] In the drawings, the reference signs are as follows:

[0039] 1-1—upper downpipe reactor;

[0040] 1-2—upper gas-solid separation device;

[0041] 1-3—second oil gas;

[0042] 1-5—raw material B;

[0043] 2-1—lower downpipe reactor;

[0044] 2-2—lower gas-solid separation device;

[0045] 2-3—raw material A;

[0046] 2-4—to-be-regenerated inclined pipe;

[0047] 2-5—fourth regulating valve;

[0048] 2-6—first oil gas;

[0049] 3-1—regenerator;

[0050] 3-2—Upper regeneration inclined tube;

[0051] 3-3—Lower regeneration inclined tube;

[0052] 3-4—First regulating valve;

[0053] 3-5—Second regulating valve;

[0054] 3-6 Catalyst delivery pipe;

[0055] 3-7—Regenerated flue gas;

[0056] 3-8—Transporting medium;

[0057] 3-9—Main wind;

[0058] 3-10—Second prevailing wind;

[0059] 3-11—Second regenerator;

[0060] 3-12—Connecting pipeline between the two regenerators;

[0061] 3-13—Third regulating valve. Detailed Implementation

[0062] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments. The drawings and specific embodiments do not limit the scope of protection claimed by the present invention.

[0063] like Figure 1 The diagram shown is a schematic of a two-stage downflow fluidized bed catalytic conversion system with one regenerator (single regenerator) according to the present invention.

[0064] Raw material A2-3, preheated to 200℃~350℃, is injected through the top inlet of the lower-stage downflow reactor 2-1, contacting the catalyst from regenerator 3-1 and the upper-stage gas-solid separation unit 1-2. They move downwards together into the lower-stage gas-solid separation unit 2-2, where the first catalyst and the first oil-gas 2-6 are separated. The first catalyst enters regenerator 3-1 for regeneration via the waiting inclined tube 2-4 and the conveying pipe. Main air 3-9 enters regenerator 3-1 from the bottom for coke burn regeneration. The first oil-gas 2-6... 6 flows out from the lower gas-solid separation unit 2-2 and is output from the system; after the raw material B1-5 is preheated to 200℃~350℃, it is injected into the upper downflow pipe reactor 1-1, where it comes into contact with the regenerator from the regenerator 3-1 and moves downward together into the upper gas-solid separation unit 1-2, where the second catalyst and the second oil-gas 1-3 are separated. The catalyst enters the top of the lower downflow pipe reactor 2-1, and the second oil-gas 1-3 is separated from the upper gas-solid separation unit 1-2 and mixed with the first oil-gas 2-6 before being output from the system.

[0065] like Figure 2The diagram shown is a schematic of a two-stage downflow fluidized bed catalytic conversion system with two regenerators (dual regenerators) according to the present invention.

[0066] Raw material A2-3, preheated to 200℃~350℃, is injected from the top inlet of the lower-stage downflow reactor 2-1, where it comes into contact with the catalyst from the second regenerator 3-11 and the upper-stage gas-solid separation unit 1-2. They move downwards together into the lower-stage gas-solid separation unit 2-2, where the first catalyst and the first oil-gas 2-6 are separated. The first catalyst enters the regenerator 3-1 via the waiting inclined pipe 2-4 and the conveying pipe. A portion of the first catalyst in the regenerator 3-1 enters the second regenerator 3-11 through the two-regenerator connecting pipeline 3-12. The main air 3-9 and the main... Air 3-10 enters the second regenerator 3-11 and regenerator 3-1 from the bottom for coking regeneration. Raw material B1-5 is preheated to 200℃~350℃ and then enters the top of the upper downpipe 1-1, where it comes into contact with the regenerator from regenerator 3-1 and moves downward together into the upper gas-solid separation device 1-2, where the second catalyst and the second oil-gas 1-3 are separated. The second catalyst enters the top of the lower downpipe reactor 2-1, and the second oil-gas 1-3 is separated from the upper gas-solid separation device 1-2 and mixed with the first oil-gas 2-6 before being output from the system.

[0067] The present invention is further illustrated by the following embodiments, but the following embodiments do not limit the scope of protection claimed by the present invention.

[0068] Example 1

[0069] This embodiment is in Figure 1 The experiment was conducted on the system shown. The main properties of the heavy feedstock A and light feedstock B used in the experiment are listed in Table 1. The catalyst was LIP-300 produced by Lanzhou Catalyst Plant, which underwent 100% hydrothermal deactivation treatment at 800℃. The inner diameter of the upper-stage downflow reactor was 0.5 meters, the height was 45 meters, and the reaction temperature was 650℃. The inner diameter of the lower-stage downflow reactor was 4.5 meters, the height was 45 meters, the reaction temperature was 480℃, the regeneration temperature was 650℃, the preheating temperature of feedstock A was 220℃, the preheating temperature of feedstock B was 350℃, the reaction pressure was 0.1 MPa (gauge pressure), the catalyst-to-oil ratio was 6, the reaction time of the upper-stage downflow reactor was 2.0 s, and the reaction time of the lower-stage downflow reactor was 0.2 s. The upper-stage gas-solid separation device was a rapid gas-solid separator, and the lower-stage gas-solid separation device was a stripper. The product distribution results are listed in Table 2.

[0070] Comparative Example 1

[0071] The main difference between Comparative Example 1 and Example 1 is that the carbon content of the regenerant in regenerator 3-1 is not adjusted, meaning that the amount of carbon deposited in the catalyst in the upper and lower regeneration inclined tubes is the same. All other conditions are the same as in Example 1. The product distribution results are listed in Table 2.

[0072] Example 2

[0073] This example was carried out on the system shown in Figure 2 Table 1, and the catalyst was LIP-300 produced by Lanzhou Catalyst Factory and treated by 800°C, 100% hydrothermal deactivation. The inner diameter of the upper downer reactor was 4.5 meters, the height was 8 meters, the reaction temperature was 720°C, the inner diameter of the lower downer reactor was 0.5 meters, the height was 42 meters, the reaction temperature was 590°C, the regeneration temperature was 750°C, the preheating temperature of the feedstock A was 220°C, the preheating temperature of the feedstock B was 350°C, the reaction pressure was 0.4 MPa (gauge pressure), the catalyst to oil ratio was 35, the reaction time of the upper downer reactor was 0.3 s, the reaction time of the lower downer reactor was 1.8 s, the gas-solid separation device of the upper downer reactor was a stripper, and the gas-solid separation device of the lower downer reactor was a stripper and a gas-solid quick separation device. The product distribution results are shown in Table 3.

[0074] Comparative Example 2

[0075] The main difference between Comparative Example 2 and Example 2 was that the carbon content of the regenerant in the regenerator 3-1 and the second regenerator 3-11 was adjusted so that the amount of coke contained in the catalyst in the upper regeneration inclined pipe was the same as the amount of coke contained in the catalyst in the lower regeneration inclined pipe, and the other conditions were the same as in Example 2. The product distribution results are shown in Table 3.

[0076] Example 3

[0077] This example was carried out on the system shown in Figure 2 Table 1, and the catalyst was LIP-300 produced by Lanzhou Catalyst Factory and treated by 800°C, 100% hydrothermal deactivation. The inner diameter of the upper downer reactor was 4.5 meters, the height was 8 meters, the reaction temperature was 720°C, the inner diameter of the lower downer reactor was 0.5 meters, the height was 42 meters, the reaction temperature was 590°C, the regeneration temperature was 750°C, the preheating temperature of the feedstock A was 220°C, the preheating temperature of the feedstock B was 350°C, the reaction pressure was 0.4 MPa (gauge pressure), the catalyst to oil ratio was 35, the reaction time of the upper downer reactor was 0.3 s, the reaction time of the lower downer reactor was 1.8 s, the gas-solid separation device of the upper downer reactor was a stripper, and the gas-solid separation device of the lower downer reactor was a stripper and a gas-solid quick separation device. The product distribution results are shown in Table 3.

[0078] Comparative Example 3

[0079] The main difference between Comparative Example 3 and Example 3 was that the carbon content of the regenerant in the regenerator 3-1 was lower than the carbon content of the regenerant in the second regenerator 3-11, i.e., the amount of coke contained in the catalyst in the upper regeneration inclined pipe was lower than the amount of coke contained in the catalyst in the lower regeneration inclined pipe, and the other conditions were the same as in Example 3. The product distribution results are shown in Table 4.

[0080] Table 1 Raw material properties

[0081] Item Feedstock A Feedstock B Density (20°C), g / cm 3 ]] 0.91 0.71 Sulfur content, pg / g 1600 257 Nickel, pg / g 5.8 0.8 Vanadium, pg / g 1.0 / Carbon residue, W% 3.6 0.75 H content, W% 12.9 / Crude oil category Paraffinic /

[0082] Table 2 Material balance

[0083]

[0084] Table 3 Material balance

[0085]

[0086]

[0087] Table 4 Material balance

[0088]

[0089] From the results of the above examples and comparative examples, the method and system of the present application, using the reactor type of two-stage downflow tubes, can realize the operating conditions of large oil ratio and short reaction time, and the regenerators are provided with one or two regenerators to supply the regenerated agents with different carbon contents to the upper-stage downflow tube reactor and the lower-stage downflow tube reactor, and the reaction temperatures of the upper-stage downflow tube reactor and the lower-stage downflow tube reactor can be independently controlled. The method and system of the present application can effectively improve the product distribution of catalytic cracking / catalytic cracking, increase the hydrogenation, fully utilize the short reaction time of the downflow tube reactor and the two-stage catalyst reaction relay advantage, reduce the yield of dry gas and coke, and increase the yield of low-carbon olefins. In the method and system of the present application, the catalysts in the upper-stage downflow tube reactor and the lower-stage downflow tube reactor come from different positions of the regenerators or from different regenerators, and the carbon deposition contents attached to the catalysts are different, which can be adjusted by adjusting the flow of the main air of the regenerators, and a certain carbon deposition content can produce beneficial cracking effect on light distillates. In the method and system of the present application, two regenerative inclined pipes are provided, and the upper-stage downflow tube reactor and the lower-stage downflow tube reactor can independently obtain the regenerated agent from the regenerators, and can provide the catalyst with appropriate activity for each stage of the downflow tube reactor; the outlet temperatures of the upper-stage downflow tube reactor and the lower-stage downflow tube reactor are respectively linked with the first regulating valve and the second regulating valve of the respective regenerative inclined pipes, and the outlet temperatures of each stage of the downflow tube reactor can be independently and flexibly adjusted.

[0090] Of course, the present application can have other various embodiments and deformations, and those skilled in the art can make various corresponding changes and deformations according to the present application without departing from the spirit and essence of the present application, but these corresponding changes and deformations should belong to the protection scope of the claims of the present application.

Claims

1. A two-stage downflow tubular catalytic conversion method, characterized in that, Includes the following steps: A. Raw material A (2-3) is injected from the top of the lower-level downflow reactor (2-1). The regenerator is connected to the lower-level downflow reactor (2-1) through the lower regeneration inclined pipe (3-3). Raw material A (2-3) reacts with the catalyst from the regenerator and the upper-level gas-solid separation unit (1-2) in the lower-level downflow reactor (2-1). The product enters the lower-level gas-solid separation unit (2-2) for separation to obtain the first catalyst and the first oil and gas (2-6). The first oil and gas (2-6) is output into the fractionation tower through the output system. The first catalyst enters the regenerator for regeneration through the waiting inclined pipe (2-4) and the conveying pipe. B. Raw material B (1-5) enters the top of the upper downflow tube reactor (1-1). The regenerator is connected to the upper downflow tube reactor (1-1) through the upper regeneration inclined tube (3-2). Raw material B (1-5) reacts with the regenerator from the regenerator in the upper downflow tube reactor (1-1). The product enters the upper gas-solid separation device (1-2) for separation, and the separation yields the second catalyst and the second oil and gas (1-3). The second catalyst is input into the top of the lower downflow tube reactor (2-1) to react with raw material A (2-3). The second oil and gas (1-3) is output into the fractionation tower. The upper regeneration inclined tube (3-2) is equipped with a first regulating valve (3-4), the opening degree of which controls the temperature at the outlet of the upper downflow reactor (1-1); the lower regeneration inclined tube (3-3) is equipped with a second regulating valve (3-5), the opening degree of which controls the temperature at the outlet of the lower downflow reactor (2-1); the catalyst in the upper regeneration inclined tube (3-2) contains more carbon deposits than the catalyst in the lower regeneration inclined tube (3-3).

2. The method according to claim 1, characterized in that, The upper-level downflow tube reactor (1-1) and the lower-level downflow tube reactor (2-1) are tubular reactors with an inner diameter of 0.5-5 meters and a height of 5-50 meters.

3. The method according to claim 1, characterized in that, The upper-level gas-solid separation device (1-2) and the lower-level gas-solid separation device (2-2) are at least one of a gas-solid rapid separation device and a stripper.

4. The method according to claim 1, characterized in that, The upper-level gas-solid separation device (1-2) is a gas-solid rapid separation device.

5. The method according to claim 1, characterized in that, The lower-level gas-solid separation device (2-2) is a stripper.

6. The method according to claim 1, characterized in that, The opening degree of the first regulating valve (3-4) is 10-80%.

7. The method according to claim 1, characterized in that, The opening degree of the second regulating valve (3-5) is 10-80%.

8. The method according to claim 1, characterized in that, The number of regenerators is one or two, and the regeneration temperature of the regenerators is 650-780℃.

9. The method according to claim 8, characterized in that, The number of regenerators is 1. The upper regeneration inclined tube (3-2) is connected to the middle of the regenerator, and the lower regeneration inclined tube (3-3) is connected to the bottom of the regenerator. The regenerants of the upper downflow tube reactor (1-1) and the lower downflow tube reactor (2-1) come from different positions of the regenerator. The main air (3-9) is input into the regenerator, and the carbon content of the catalyst in the upper regeneration inclined tube (3-2) and the lower regeneration inclined tube (3-3) is controlled to be 0-1 wt% by adjusting the main air (3-9).

10. The method according to claim 8, characterized in that, The number of regenerators is two, one of which is connected to the lower regeneration inclined tube (3-3), and the other is connected to the upper regeneration inclined tube (3-2). The two regenerators are connected by a two-regenerator connecting pipeline (3-12), and a third regulating valve (3-13) is provided on the two-regenerator connecting pipeline (3-12). The two regenerators are arranged coaxially stacked or independently. Main air (3-9) is input into both regenerators, and the carbon content of the catalyst in the upper regeneration inclined tube (3-2) and the lower regeneration inclined tube (3-3) is controlled to be 0-1 wt% by adjusting the main air (3-9).

11. The method according to claim 1, characterized in that, The outlet temperature of the upper-stage downflow reactor (1-1) is 480℃-750℃, the outlet temperature of the lower-stage downflow reactor (2-1) is 480℃-650℃, the operating pressure of the upper-stage downflow reactor (1-1) and the lower-stage downflow reactor (2-1) is 0.1-0.4MPa (gauge pressure), the reaction time of the upper-stage downflow reactor (1-1) and the lower-stage downflow reactor (2-1) is 0.1-2s, and the agent-to-oil ratio is 4-40.

12. The method according to claim 1, characterized in that, The raw material A (2-3) is a high-boiling-point petroleum hydrocarbon with a fraction mass of more than 90% having a true boiling point of 200℃ or higher.

13. The method according to claim 1, characterized in that, The raw material B (1-5) is one or more low-boiling-point petroleum hydrocarbons with a fraction mass ratio of more than 90% that has a true boiling point below 360℃.

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