Fluidized catalytic conversion process and system with two-stage downflow tubes in series

Abstract

The application discloses a fluidized catalytic conversion method and system of two-stage down-flow pipe series connection. The system comprises a higher-stage down-flow pipe reactor and a lower-stage down-flow pipe reactor, gas-solid separation devices are arranged at the outlets of each down-flow pipe reactor, one or two regenerators are arranged, the upper portions of the higher-stage down-flow pipe reactor and the lower-stage down-flow pipe reactor are communicated with a regeneration inclined pipe, a catalyst regulating valve is arranged on the regeneration inclined pipe, and the regulating valve is interlocked with the outlet temperature of the down-flow pipe reactor. The reaction temperature of the higher-stage down-flow pipe reactor and the lower-stage down-flow pipe reactor can be independently controlled by the method and the system, and the method and the 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 fluid catalytic cracking / cracking process and system, which can be used for preparing petrochemicals, such as olefins and aromatic hydrocarbons. BACKGROUND

[0002] Catalytic cracking / cracking is an important means of lightening heavy oil, and "reducing oil and increasing hydrocarbon" 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 hydrocarbon is 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 hydrocarbon" that is highly expected at present.

[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 gravity 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, which is particularly suitable for catalytic conversion reactions with ultra-short contact (reaction) time (usually 1-3 times shorter than the riser) and ultra-large catalyst to oil ratio (usually 1-3 times larger than the riser), such as deep catalytic conversion of residual oil, catalytic thermal cracking, catalytic cracking of gasoline to produce olefins, etc., which 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 problems of long reaction time and excessive cracking causing 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 to 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 the first catalytic cracking catalyst from the top of the first downflow tube reactor and performing the first catalytic cracking reaction from top to bottom; b, feeding light feedstock into the upper part of the second downflow tube reactor and contacting the second catalytic cracking catalyst from the top of the second downflow tube reactor and performing the 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 the third catalytic cracking catalyst and performing the third catalytic cracking reaction to obtain the third product and the 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 present application aims to overcome the deficiency that the reaction temperature of each downflow tube in the existing multi-stage downflow tube cannot be independently controlled, and provides a two-stage downflow tube in series fluidized catalytic conversion method and system, the reaction temperature of the two-stage downflow tube of the method and system can be independently controlled.

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

[0012] A, the raw material is injected from the top of the lower downer reactor, the regenerator is communicated with the lower downer reactor through a lower regeneration inclined pipe, the raw material is contacted with the catalyst from the regenerator and the upper gas-solid separation device in the lower downer reactor to react, the product enters the lower gas-solid separation device to be separated, and the first catalyst and the first oil gas are obtained;

[0013] B, the first catalyst enters the regenerator through the standby inclined pipe and the conveying pipe to be regenerated, all or part of the first oil gas enters the top of the upper downer reactor through an oil gas pipeline, the regenerator is communicated with the upper downer reactor through an upper regeneration inclined pipe, the first oil gas is contacted with the regenerator from the regenerator in the upper downer reactor to react again, the product enters the upper gas-solid separation device to be separated, and the second catalyst and the oil gas product are obtained, the second catalyst is input into the top of the lower downer reactor to be contacted with the raw material to react, and the oil gas product is output from the upper gas-solid separation device;

[0014]

[0015] The two-stage downer series fluidized catalytic conversion method of the application, the upper downer reactor and the lower downer reactor include but are not limited to a tubular reactor, the inner diameter includes but is not limited to 0.5-5 meters, and the height includes but is not limited to 5-50 meters.

[0016] The two-stage downer series fluidized catalytic conversion method of the application, the upper gas-solid separation device can be at least one of a gas-solid quick separation device and a stripper, and the lower gas-solid separation device is a stripper or a stripper and a gas-solid quick separation device.

[0017] The two-stage downer series fluidized catalytic conversion method of the application, the opening degree of the first regulating valve is 10-80%.

[0018] The two-stage downer series fluidized catalytic conversion method of the application, the opening degree of the second regulating valve is 10-80%.

[0019] The raw material heavy petroleum hydrocarbon can be reacted under the condition of lower temperature and catalyst containing carbon, and the product after reaction of the lower downer reactor can be contacted with the high-temperature regenerator from the regenerator to react again.

[0020] ​The two-stage down-flow tube series fluidized catalytic conversion method of the present application, the regenerators can be 1 or 2, the regeneration temperature of the regenerators is 650-780℃, the regenerators can provide different temperatures or different carbon contents of the regenerators for the upper-stage down-flow tube reactor and the lower-stage down-flow tube reactor.

[0021] When the number of the regenerators is 1, the upper regenerative inclined tube is communicated with the middle part of the regenerator, the lower regenerative inclined tube is communicated with the bottom of the regenerator, and the regenerants of the upper-stage down-flow tube reactor and the lower-stage down-flow tube reactor come from different positions of the regenerator. The carbon content of the regenerant can be adjusted by adjusting the flow of the main air input into the regenerator, and the carbon content of the catalyst in the upper regenerative inclined tube and the lower regenerative inclined tube is controlled to be 0-1wt% respectively by adjusting the main air. The flow of the main air is not particularly limited in the present application, and can be adjusted adaptively according to the carbon content of the catalyst.

[0022] When the number of the regenerators is 2, one of the regenerators is communicated with the lower regenerative inclined tube, and the other of the regenerators is communicated with the upper regenerative inclined tube; 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 the carbon content of the regenerants supplied by the upper regenerative inclined tube and the lower regenerative inclined tube can be independently adjusted. The carbon content of the regenerant can be adjusted by adjusting the flow of the main air input into the two regenerators, and the carbon content of the catalyst in the upper regenerative inclined tube and the lower regenerative inclined tube is controlled to be 0-1wt% respectively by adjusting the main air. The flow of the main air is not particularly limited in the present application, and can be adjusted adaptively according to the carbon content of the catalyst.

[0023] The two-stage down-flow tube series fluidized catalytic conversion method of the present application, the temperature of the outlet of the upper-stage down-flow tube reactor is 480℃-750℃, the outlet temperature of the lower-stage down-flow tube reactor is 480℃-650℃, the operating pressure of the upper-stage down-flow tube reactor and the lower-stage down-flow tube reactor is 0.1-0.4MPa (gauge pressure), the reaction time of the upper-stage down-flow tube reactor and the lower-stage down-flow tube reactor is 0.1-2s, and the catalyst-oil ratio is 4-40.

[0024] The two-stage down-flow tube series fluidized catalytic conversion method of the present application, the raw material is high-boiling-point petroleum hydrocarbon with a mass fraction of more than 90% of distillate with a true boiling point of 200℃ or above, 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-stage down-flow tube reactor.

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

[0026] upper downer reactor;

[0027] upper gas-solid separation device, top of which is communicated with bottom of the upper downer reactor;

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

[0029] lower gas-solid separation device, bottom of which is communicated with the lower downer reactor, top of which is communicated with the upper downer reactor through oil-gas pipeline; and

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

[0031] The method and system of the present application, raw materials enter top of the lower downer reactor and react with catalysts, the catalysts after reaction enter the regenerator to be regenerated to obtain regenerated catalysts which then re-enter the upper downer reactor or the lower downer reactor to react, realizing recycling use of the catalysts; the oil-gas after reaction enters the upper downer reactor through the oil-gas pipeline to react with the high-temperature regenerated catalysts from the regenerator, the method and system of the present application are provided with two regenerative inclined pipes: upper regenerative inclined pipe and 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 top of the upper downer reactor, the upper regenerative inclined pipe provides the regenerated catalysts for the upper downer reactor. The inlet of the lower regenerative inclined pipe is communicated with the regenerator, the outlet of the lower regenerative inclined pipe is communicated with top of the lower downer reactor, the lower regenerative inclined pipe provides the regenerated catalysts for the lower downer reactor. The upper regenerative inclined pipe is provided with a first regulating valve, the first regulating valve is interlocked with outlet temperature of the upper downer reactor, the lower regenerative inclined pipe is provided with a second regulating valve, the second regulating valve is interlocked with 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. The method and system of the present application adopt the reactor type of two-stage downer, can realize the operating conditions of large catalyst-oil ratio and short reaction time, the regenerator can be provided with one or two regenerators, the upper downer reactor and the lower downer reactor are supplied 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.

[0032] The method and system of the present application, the oil gas separated by the lower gas-solid separation device enters the upper downpipe reactor for secondary reaction, which can effectively improve the product distribution of catalytic cracking / cracking, increase the yield of gasoline and reduce the yield of dry gas and coke, and increase the yield of low-carbon olefins.

[0033] 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 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.

[0034] 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 adjusting valve and the second adjusting 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

[0035] Figure 1 The schematic diagram of the two-stage downpipe series fluidized catalytic conversion system provided with one regenerator (single regenerator) of the present application.

[0036] Figure 2 The schematic diagram of the two-stage downpipe series fluidized catalytic conversion system provided with two regenerators (double regenerators) of the present application.

[0037] Among them, the reference signs are:

[0038] 1-1—upper downpipe reactor;

[0039] 1-2—upper gas-solid separation device;

[0040] 1-3—oil gas product;

[0041] 1-4—oil gas pipeline;

[0042] 2-1—lower downpipe reactor;

[0043] 2-2—lower gas-solid separation device;

[0044] 2-3—raw material;

[0045] 2-4—to-be-regenerated inclined pipe;

[0046] 2-5—fourth adjusting valve;

[0047] 3-1—regenerator;

[0048] 3-2—Upper regeneration inclined tube;

[0049] 3-3—Lower regeneration inclined tube;

[0050] 3-4—First regulating valve;

[0051] 3-5—Second regulating valve;

[0052] 3-6 Catalyst delivery pipe;

[0053] 3-7—Regenerated flue gas;

[0054] 3-8—Transporting medium;

[0055] 3-9—Main wind;

[0056] 3-10—Second prevailing wind;

[0057] 3-11—Second regenerator;

[0058] 3-12—Connecting pipeline between the two regenerators;

[0059] 3-13—Third regulating valve. Detailed Implementation

[0060] 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.

[0061] like Figure 1 The diagram shown is a schematic of a fluidized catalytic conversion system with two-stage downpipes connected in series, featuring one regenerator (single regenerator) according to the present invention.

[0062] Raw material 2-3 is preheated to 200℃~350℃ and then injected into the top inlet of the lower-stage downflow reactor 2-1. It comes into contact with the catalyst from regenerator 3-1 and upper-stage gas-solid separation device 1-2, and moves downward together into the lower-stage gas-solid separation device 2-2, where the first catalyst and the first oil and gas are separated. The first catalyst enters the regenerator 3-1 for regeneration through the waiting inclined tube 2-4 and the conveying pipe. The main air 3-9 enters the regenerator 3-1 from the bottom for coking regeneration. The first oil and gas enters the top of the upper-stage downflow reactor 1-1 through the oil and gas pipeline 1-4, where it comes into contact with the regenerator from regenerator 3-1 and moves downward together into the upper-stage gas-solid separation device 1-2, where the second catalyst and oil and gas product 1-3 are separated. The second catalyst enters the top of the lower-stage downflow reactor 2-1, and the oil and gas product 1-3 is output from the system for subsequent processing.

[0063] like Figure 2 The diagram shown is a schematic of a fluidized catalytic conversion system with two regenerators (dual regenerators) connected in series in two-stage downpipes according to the present invention.

[0064] The raw material 2-3 is preheated to 200-350°C and injected from the top inlet of the lower downer reactor 2-1, contacted with the catalyst from the second regenerator 3-11 and the upper gas-solid separation device 1-2, and moved downward together into the lower gas-solid separation device 2-2, from which the first catalyst and the first oil gas are separated, the first catalyst enters the regenerator 3-1 through the spent catalyst inclined pipe 2-4 and the conveying pipe, part of the first catalyst in the regenerator 3-1 enters the second regenerator 3-11 through the two-regenerator connecting pipe 3-12, the main air 3-9 and the main air 3-10 enter the second regenerator 3-11 and the regenerator 3-1 from the bottom respectively for coking regeneration, the first oil gas enters the top of the upper downer reactor 1-1 through the oil gas pipe 1-4, contacted with the regenerated catalyst from the regenerator 3-1, and moved downward together into the upper gas-solid separation device 1-2, from which the second catalyst and the oil gas product 1-3 are separated, the second catalyst enters the top of the lower downer reactor 2-1, and the oil gas product 1-3 is output from the system for subsequent processing.

[0065] The application is further illustrated by the following examples, but the following examples do not limit the scope of the application claimed.

[0066] Example 1

[0067] This example is carried out on the system shown in Figure 1 Table 1, the catalyst is LIP-300 produced by Lanzhou Catalyst Factory and treated by 800°C and 100% hydrothermal deactivation. The inner diameter of the upper downer reactor is 2.5 meters, the height is 40 meters, the reaction temperature is 480°C, the inner diameter of the lower downer reactor is 2.8 meters, the height is 6 meters, the reaction temperature is 650°C, the regeneration temperature is 780°C, the preheating temperature of the raw material is 220°C, the reaction pressure is 0.1 MPa (gauge pressure), the catalyst / oil ratio is 35, the reaction time of the upper downer reactor is 2.0 s, the reaction time of the lower downer reactor is 0.25 s, the upper gas-solid separation device is a gas-solid quick separation device, and the lower gas-solid separation device is a stripper. The product distribution results are shown in Table 2.

[0068] Comparative Example 1

[0069] The main difference between Comparative Example 1 and Example 1 is that the carbon content of the regenerated catalyst in the regenerator 3-1 is not adjusted, that is, the carbon content of the catalyst in the upper and lower regenerated catalyst inclined pipes is the same, and the other conditions are the same as those in Example 1. The product distribution results are shown in Table 2.

[0070] Example 2

[0071] This example is carried out on the system shown in Figure 2The reaction was carried out on the system shown. The main properties of the raw materials used 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 4.8 meters, the height was 8 meters, and the reaction temperature was 720℃. The inner diameter of the lower-stage downflow reactor was 0.75 meters, the height was 48 meters, the reaction temperature was 490℃, the regeneration temperature was 660℃, the raw material preheating temperature was 220℃, the reaction pressure was 0.4 MPa (gauge pressure), the catalyst-to-oil ratio was 5, the reaction time of the upper-stage downflow reactor was 0.2 s, and the reaction time of the lower-stage downflow reactor was 2.0 s. The upper-stage gas-solid separation unit was a stripper, and the lower-stage gas-solid separation unit was a stripper and a rapid gas-solid separator. The product distribution results are listed in Table 3.

[0072] Comparative Example 2

[0073] The main difference between Comparative Example 2 and Example 2 is that the carbon content of the regenerant in regenerator 3-1 and the second regenerator 3-11 was adjusted so that the amount of carbon deposited in the catalyst in the upper and lower regeneration inclined tubes was the same. The other conditions were the same as in Example 2. The product distribution results are listed in Table 3.

[0074] Example 3

[0075] This embodiment is in Figure 2 The reaction was carried out on the system shown. The main properties of the raw materials used 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 0.6 meters, the height was 28 meters, and the reaction temperature was 620℃. The inner diameter of the lower-stage downflow reactor was 4.3 meters, the height was 22 meters, the reaction temperature was 570℃, the regeneration temperature was 720℃, the raw material preheating temperature was 220℃, the reaction pressure was 0.26 MPa (gauge pressure), the catalyst-to-oil ratio was 22, the reaction time of the upper-stage downflow reactor was 1.5 s, and the reaction time of the lower-stage downflow reactor was 1.1 s. The upper-stage gas-solid separation unit was a stripper, and the lower-stage gas-solid separation unit was a stripper and a rapid gas-solid separator. The product distribution results are listed in Table 4.

[0076] Comparative Example 3

[0077] The main difference between Comparative Example 3 and Example 3 is that the carbon content of the regenerant in regenerator 3-1 is lower than that of the regenerant in the second regenerator 3-11, that is, the carbon deposits in the catalyst in the upper regeneration inclined tube are lower than those in the catalyst in the lower regeneration inclined tube. The other conditions are the same as in Example 3. The product distribution results are listed in Table 4.

[0078] Table 1 Properties of Raw Materials

[0079]

[0080]

[0081] Table 2 Material Balance

[0082]

[0083] Table 3 Material Balance

[0084]

[0085]

[0086] Table 4 Material Balance

[0087]

[0088] 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 downer, can realize the operating conditions of large oil ratio and short reaction time, the regenerator is provided with one or two regenerators to supply the upper-stage downer reactor and the lower-stage downer reactor with regenerants with different carbon contents, and the reaction temperatures of the upper-stage downer reactor and the lower-stage downer reactor can be independently controlled. The method and system of the present application, the oil gas separated by the lower-stage gas-solid separation device enters the upper-stage downer reactor for secondary reaction, which can effectively improve the product distribution of catalytic cracking / cracking, increase the yield of gasoline and reduce the yield of dry gas and coke, and increase the yield of low-carbon olefins. The catalysts in the upper-stage downer reactor and the lower-stage downer reactor of the method and system of the present application come from different positions of the regenerator or from different regenerators, the carbon content of the catalysts attached to the catalysts is different and can be adjusted by adjusting the flow of the main air of the regenerator, and a certain carbon content can produce beneficial cracking effect on light distillates. The method and system of the present application are provided with two regeneration inclined pipes, the upper-stage downer reactor and the lower-stage downer reactor can independently obtain the supplement of regenerants from the regenerator, and can provide each stage of downer reactor with catalysts with appropriate activity; the outlet temperatures of the upper-stage downer reactor and the lower-stage downer reactor are respectively linked with the first regulating valve and the second regulating valve of the respective regeneration inclined pipes, and the outlet temperatures of each stage of downer reactor can be independently and flexibly adjusted.

[0089] 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 fluidized catalytic conversion process in which two downflow reactors are connected in series, characterized in that, The method comprises the following steps: A, the raw material (2-3) is injected from the top of the lower downer reactor (2-1), the regenerator is communicated with the lower downer reactor (2-1) through the lower regeneration inclined pipe (3-3), the raw material (2-3) is contacted with the catalyst from the regenerator and the upper gas-solid separation device (1-2) in the lower downer reactor (2-1) to react, the product is separated in the lower gas-solid separation device (2-2) to obtain the first catalyst and the first oil gas; B, the first catalyst enters the regenerator for regeneration through the spent inclined pipe (2-4) and the conveying pipe, all or part of the first oil gas enters the top of the upper downer reactor (1-1) through the oil gas pipeline (1-4), the regenerator is communicated with the upper downer reactor (1-1) through the upper regeneration inclined pipe (3-2), the first oil gas is contacted with the regenerant from the regenerator in the upper downer reactor (1-1) to react again, the product is separated in the upper gas-solid separation device (1-2) to obtain the second catalyst and the oil gas product, the second catalyst is input into the top of the lower downer reactor (2-1) to contact with the raw material (2-3) to react, and the oil gas product (1-3) is output from the upper gas-solid separation device (1-2); Wherein, the upper regeneration inclined pipe (3-2) is provided with a first regulating valve (3-4), the opening degree of the first regulating valve (3-4) controls the temperature of the outlet of the upper downer reactor (1-1); the lower regeneration inclined pipe (3-3) is provided with a second regulating valve (3-5), the opening degree of the second regulating valve (3-5) controls the temperature of the outlet of the lower downer reactor (2-1); the catalyst contained in the upper regeneration inclined pipe (3-2) contains more coke than the catalyst contained in the lower regeneration inclined pipe (3-3).

2. The method of claim 1, wherein, The upper downer reactor (1-1) and the lower downer reactor (2-1) are tubular reactors, the inner diameter is 0.5-5 meters, and the height is 5-50 meters.

3. The method of claim 1, wherein, The upper gas-solid separation device (1-2) is at least one of a gas-solid quick separation device and a stripper; the lower gas-solid separation device (2-2) is a stripper or a stripper and a gas-solid quick separation device.

4. The method of claim 1, wherein, The opening degree of the first regulating valve (3-4) is 10-80%.

5. The method of claim 1, wherein, The opening degree of the second regulating valve (3-5) is 10-80%.

6. The method of claim 1, wherein, The number of the regenerators is 1 or 2, and the regeneration temperature of the regenerators is 650-780℃.

7. The method of claim 6, wherein, The number of the regenerators is 1, the upper regeneration inclined pipe (3-2) is communicated with the middle part of the regenerator, the lower regeneration inclined pipe (3-3) is communicated with the bottom of the regenerator, and the regenerants of the upper downer reactor (1-1) and the lower downer reactor (2-1) come from different positions of the regenerator; the main air (3-9) is input into the regenerator, and the coke content contained in the catalysts in the upper regeneration inclined pipe (3-2) and the lower regeneration inclined pipe (3-3) is controlled to be 0-1wt% by adjusting the main air (3-9).

8. The method of claim 6, wherein, When the number of the regenerators is 2, one of the regenerators is communicated with the lower regenerative inclined pipe (3-3), and the other of the regenerators is communicated with the upper regenerative inclined pipe (3-2); the two regenerators are communicated through two regenerator communication pipelines (3-12), and the two regenerator communication pipelines (3-12) are provided with third regulating valves (3-13); the main air (3-9) is input into the two regenerators, and the carbon content contained in the catalyst in the upper regenerative inclined pipe (3-2) and the lower regenerative inclined pipe (3-3) is controlled to be 0-1wt% by adjusting the main air (3-9).

9. The method of claim 1, wherein, The temperature at the outlet of the upper downflow tube reactor (1-1) is 480-750℃, the temperature at the outlet of the lower downflow tube reactor (2-1) is 480-650℃, the operating pressure of the upper downflow tube reactor (1-1) and the lower downflow tube reactor (2-1) is 0.1-0.4MPa (gauge pressure), and the reaction time of the upper downflow tube reactor (1-1) and the lower downflow tube reactor (2-1) is 0.1-2s, and the catalyst to oil ratio is 4-40.

10. The method of claim 1, wherein, The raw material (2-3) is high-boiling petroleum hydrocarbon with the mass fraction of the fraction with the true boiling point of 200℃ or above being more than 90%.

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