Settler and its reaction device

Abstract

A kind of settler, comprising: settler tank, primary separator and cyclone separator, primary separator and cyclone separator are arranged in settler tank, primary separator includes bend pipe and the down pipe being communicated with bend pipe, the first end of bend pipe is connected with the exit of reactor side wall, the second end of bend pipe is connected with cyclone separator, bend pipe is bent upwards from the connection with reactor side wall.The oil gas and catalyst discharged from reactor enter the bend pipe of primary separator, most of catalyst is discharged through the down pipe of primary separator, and oil gas enters cyclone separator for further gas-solid separation.Oil gas directly into settler is greatly reduced, to avoid coking in settler, on the other hand, reduce the working load of cyclone separator, reduce the loss of catalyst.

Description

Technical Field

[0001] This application relates to a settling device, specifically a settling device for a catalytic dehydrogenation and cracking reaction unit, a settling device for reducing agent loss and preventing coking, belonging to the petrochemical field. Background Technology

[0002] During the start-up and shutdown of catalytic cracking / pyrolysis units, and when abnormal fluctuations occur in operating pressure or temperature, such as sudden interruption of feed, defluidization, or regenerator stalling, the cyclone separator operates poorly, easily leading to catalyst loss. Simultaneously, if coke deposits detach from the settler, they can block the catalyst circulation channels, causing poor or interrupted circulation, catalyst loss, and ultimately forcing the unit to shut down for decoking, resulting in significant economic losses for the company.

[0003] The physical factors contributing to coking in settling tanks are primarily the condensation of heavy components in the reactant oil and gas and their adhesion to the catalyst and internal components of the settling tank. Reducing the condensation of heavy components in the oil and gas can effectively inhibit coking in the settling tank. If the temperature is lower than the dew point temperature under the partial pressure of the oil and gas, the heavy components will condense and precipitate, adhering to the catalyst and being captured by the tank wall or internal components, thus forming coke.

[0004] Chinese patents such as ZL201410613806.8 address the issues of condensation and coking of heavy oil and gas components at the top, middle, and bottom of the settling tank. By installing one or more sets of anti-coking steam rings at different locations (top, middle, or bottom) of the settling tank, the anti-coking steam rings spray steam into the settling tank to block the oil and gas, thereby reducing coking in the catalytic cracking settling tank.

[0005] Because the settling tank has a relatively large space and low oil and gas flow velocity, the oil and gas remain in the settling space for a long time, and dead zones exist. This not only increases the secondary over-cracking reaction of the oil and gas but also increases the condensation of heavy components in the oil and gas, leading to an increase in the proportion of oil droplets and the possibility of coking. The resulting coke adheres to the inner wall of the settling tank and the outer surface of the equipment, continuously increasing in thickness, and over time becomes a serious hidden danger that threatens the long-term operation of the unit.

[0006] Chinese Patent ZL201010263125.5 describes a device and method for rapidly extracting oil and gas to inhibit coking in heavy oil catalytic converters. This method enables rapid separation of oil and gas from the catalyst, allowing the oil and gas to be quickly discharged as soon as they enter the converter space, preventing them from diffusing into the entire converter space. This eliminates coking caused by prolonged retention of oil and gas in the converter space and extends the unit's operating cycle.

[0007] Chinese patents ZL98102166.2 and ZL98204681.2 further modify the internal baffles of the pre-stripping section into a circulating sleeve and directly connect the riser pipe of the coarse cyclone separator to the inlet socket-type gas guide of the top cyclone separator. Chinese patents ZL96103478.5, ZL96103420.3, and ZL01228805.5 use several downwardly inclined arc-shaped bends at a certain angle at the end of the riser pipe as a rapid gas-solid separator, and add a sealed cover to the outside to achieve rapid extraction of oil and gas. Chinese patent ZL01100418.5 proposes a multi-stage series compact rapid gas-solid separation system for riser fluidized bed reaction systems, used for rapid separation of oil and gas from the catalyst after the riser reaction, reducing the average residence time of oil and gas in the settling tank to 3-4 seconds, thereby improving product distribution and reducing coking in the settling tank.

[0008] However, existing technologies focus on the rapid separation of oil and gas from the catalyst at the end of the riser, reducing the amount of oil and gas discharged into the bottom stripping section of the settler, and rapidly expelling the oil and gas rising from the coarse cyclone separator's riser pipe from the settler. There is no solution for treating the oil and gas that is entrained by catalyst particles or adsorbed into the bottom of the settler and the stripping section. Although the amount of oil and gas stripped by steam in the stripping section is small, it is mostly heavier fractions and needs to pass through the entire settler space before entering the top cyclone separator and leaving the settler. Therefore, this portion of oil and gas has a long residence time, reaching tens or even hundreds of seconds, making it prone to coking. As the unit operates for longer periods, coking still occurs within the settler.

[0009] Regarding the oil and gas in the stripping section, Chinese patents ZL200310121301.1 and ZL200510017707.4 propose introducing a regenerated catalyst or a high-temperature, high-activity regenerating agent into the stripping section. By increasing the temperature and catalyst activity in the stripping section, an environment is created that allows the oil and gas (often heavy components prone to coking) entrained or adsorbed between or within catalyst particles to react and transform into lighter oil and gas within the stripping section. This eliminates the inherent factors causing coking in the settling tank and also reduces coking in subsequent systems. Clearly, this measure involves significant changes to the existing settling tank reaction process and equipment system structure, making it difficult to implement and carrying considerable risk.

[0010] Chinese patent ZL200420037425.1 proposes a device for rapid removal of stripped oil and gas from a reaction settling tank at the bottom, preventing coking. It includes a guide pipe connected to the riser pipe of the primary cyclone separator, with a guide hood at its lower part to rapidly remove oil and gas from the settling space, eliminating harmful oil and gas stagnation and preventing coking. While this patented solution can achieve rapid removal of stripped oil and gas from the bottom of the settling tank, it is prone to increasing the load on the secondary cyclone separator and causing issues with catalyst loss and increased solids content in the slurry. Summary of the Invention

[0011] The primary objective of this application is to perform preliminary separation of oil and gas and catalyst at high temperatures, with the catalyst being degassed before entering the settling tank. This reduces the proportion of oil and gas directly entering the settling tank, increases the removal rate of oil and gas carried in the catalyst, and avoids coking in the settling tank.

[0012] The second objective of this application is that most of the catalyst is separated through the primary separator, reducing the workload of the coarse vortex and avoiding the problem of catalyst runoff in the device.

[0013] The anti-coking settling device provided in this application includes: a settling tank, a primary separator, and a cyclone separator. The primary separator and the cyclone separator are located in the settling tank. The primary separator is configured to be connected to an outlet on the side wall of the reactor. The primary separator includes a bend and a feed pipe connected to the bend. The bend bends upward from the connection point with the side wall of the reactor.

[0014] The oil and gas discharged from the reactor, along with the catalyst, pass through the bend in the primary separator. Most of the catalyst is discharged through the feed pipe of the primary separator, while the oil and gas enter the cyclone separator for further gas-solid separation. This significantly reduces the amount of oil and gas directly entering the settling tank, preventing coking in the settling tank and reducing the workload of the cyclone separator. Attached Figure Description

[0015] Figure 1 A schematic diagram of one embodiment of a fluidized bed reaction system.

[0016] Figure 2 Cross-sectional view of the primary separator inside the settling tank.

[0017] 1. Pre-lifting medium, 2. Pre-lifting medium conveying pipe, 3. Pre-lifting section, 4. Dense phase conveying bed reactor, 5. Dilution medium, 6. Crude oil nozzle, 7. Lower regeneration inclined pipe, 8. Upper regeneration inclined pipe, 9. Conveying medium, 10. Reactor transition section, 11. Lifting pipe, 12. Reactor settling tank, 13. Oil-gas separation system, 14. Waiting inclined pipe, 15. Regenerator settling tank, 16. Flue gas, 17. Regenerator, 18. Conveying medium, 19. Air and fuel, 20. Gas-solid primary separator, 21. Gas-solid primary separator feed pipe, 22. Coarse cyclone separator, 23. High-efficiency cyclone separator, 24. Guide cone, 25. Gas-solid primary separator feed pipe air lift section, 26. Air lift medium, 27. Coarse cyclone separator material leg degassing section, 28. Coarse cyclone separator feed pipe Detailed Implementation

[0018] The anti-coking settling device method of the present invention is described in further detail below. This does not limit the scope of protection of this application, which is defined by the claims. Certain specific details disclosed provide a comprehensive understanding of the various disclosed embodiments. However, those skilled in the art will recognize that embodiments can be implemented using other materials, etc., without employing one or more of these specific details.

[0019] Unless the context requires otherwise, the terms "comprising" and "including" in the specification and claims shall be understood as open-ended and inclusive, meaning "including, but not limited to".

[0020] The terms "implementation," "an implementation," "another implementation," or "certain implementations" used in this specification refer to specific features, structures, or characteristics described in relation to the implementation, which are included in at least one implementation. Therefore, "implementation," "an implementation," "another implementation," or "certain implementations" do not necessarily all refer to the same implementation. Furthermore, specific features, structures, or characteristics can be combined in any way within one or more implementations. Each feature disclosed in this specification can be replaced by any alternative feature that provides the same, equivalent, or similar purpose. Therefore, unless otherwise specified, the disclosed features are merely general examples of equivalent or similar features.

[0021] The present invention will be further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Experimental methods in the following embodiments, unless otherwise specified, are generally performed under conventional conditions or as recommended by the manufacturer. Unless otherwise stated, all percentages, ratios, proportions, or parts are by weight.

[0022] The term "gas-solid separation efficiency" refers to the mass fraction of catalyst that is separated into gas and solid states from the total catalyst entering the separator.

[0023] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as are familiar to those skilled in the art. Furthermore, any methods and materials similar to or equivalent to those described herein may be applied to the methods of this invention. The preferred embodiments and materials described herein are for illustrative purposes only.

[0024] In fluidized bed catalytic cracking or catalytic pyrolysis, catalyst loss and coking in the settling tank are prone to occur during start-up, shutdown, abnormal operating conditions, or fluctuations in the unit. The anti-coking settling tank of this application improves the resistance to fluctuations of the catalytic cracking unit or pyrolysis unit, preventing catalyst loss and coking within the settling tank.

[0025] The anti-coking settling device of this application includes: a settling tank, a primary separator, and a cyclone separator. The primary separator and the cyclone separator are located in the settling tank. The primary separator includes a bend and a feed pipe connected to the bend. The first end of the bend is connected to an outlet on the side wall of the reactor, and the second end of the bend is connected to the cyclone separator. The bend bends upward from the connection with the side wall of the reactor. The feed pipe includes a feed pipe air-lift section and a feed pipe conveying section.

[0026] In some embodiments, the bend in the primary separator includes a smoothly transitioning curved section; from the first end to the second end of the bend, relative to the central axis of the reactor, the curved section first extends away from the central axis and then extends closer to the central axis.

[0027] The primary separator serves to initially separate the catalyst. When the catalyst and oil / gas enter the primary separator, they directly collide with the curved sidewalls, causing the catalyst to settle naturally. Most of the oil / gas and a small amount of catalyst enter the subsequent separation system of the cyclone separator. The settled catalyst, after stripping, enters the settling tank, thereby reducing the amount of oil / gas carried in the catalyst.

[0028] The catalyst separated by the primary separator reduces the separation load on the subsequent cyclone separator, preventing a large amount of catalyst from entering the cyclone separator during unit fluctuations and hindering catalyst separation. Simultaneously, the primary separator includes a stripping section to remove oil and gas from the catalyst, reducing the proportion of oil and gas carried by the catalyst. This allows for more efficient stripping of the catalyst in the settling tank, reducing coking in the settling tank.

[0029] Preferably, in the longitudinal section of the curved section, the side closest to the central axis of the reactor is arc-shaped with a central angle of 120° to 240°.

[0030] In some implementations, the side closest to the central axis of the reactor in the longitudinal section of the curved section is arc-shaped with a central angle of 180°.

[0031] In some implementations, the lower edge of the bend is connected to the upper end of the feed pipe in the longitudinal section of the bend, so that the feed pipe and the bend are in communication.

[0032] The lower edge of the bend between the first end of the bend and the feed pipe is arc-shaped, and the central angle of the arc is 0 to 90°. Preferably, the central angle of the arc is 5-80°.

[0033] The curved section structure of the primary separator in this application uses the curvature to block most of the catalyst from the oil and gas discharged from the reactor; to some extent, it can stabilize the oil and gas velocity, thereby reducing the amount of catalyst entering the coarse cyclone separator inlet, reducing the load on the cyclone separator, and thus reducing catalyst loss.

[0034] During start-up, shutdown, or abnormal operating conditions, catalyst circulation is often unstable, and gas velocity fluctuates. This prevents the cyclone separator from achieving its designed separation efficiency, resulting in the catalyst failing to separate properly and instead entering the subsequent fractionation system along with the oil and gas. Even during start-up, shutdown, or abnormal operating conditions, because the oil, gas, and catalyst pass through the primary separator described in this application before entering the cyclone separator, the catalyst and oil entering the cyclone separator can achieve excellent gas-solid separation, thereby reducing catalyst loss.

[0035] In some implementations, the cross-section of the bend first increases and then decreases from the first end to the second end.

[0036] The reactor is a riser reactor, and the ratio of the cross-sectional diameter of the primary separator bend to the riser diameter is (1-5):1. Preferably, the ratio of the cross-sectional diameter of the primary separator bend to the riser diameter is (1-3):1.

[0037] By setting the diameter ratio, the gas velocity entering the primary separator can be controlled, and the amount of catalyst deposited can be controlled.

[0038] In some embodiments, the feed pipe of the primary separator includes a feed pipe air lift section and a feed pipe conveying section. The upper end of the feed pipe air lift section is connected to the lower edge of the bend, and the lower end of the feed pipe air lift section is connected to the upper end of the feed pipe conveying section. A gas distributor is provided in the feed pipe air lift section.

[0039] The stripping medium enters the stripping section of the feed pipe via a gas distributor. The catalyst, after passing through the primary separator, also enters the stripping section of the feed pipe, where the stripping medium degasses the catalyst, removing any carried oil and gas. The degassed catalyst then enters the conveying section of the feed pipe. This significantly reduces the amount of oil and gas carried in the catalyst discharged through the feed pipe.

[0040] The stripping medium includes nitrogen or water vapor.

[0041] Preferably, the outlet gas velocity of the stripping medium at the gas distributor is 0.1-5 m / s, more preferably 0.5-3 m / s.

[0042] In some embodiments, the diameter ratio of the feed pipe conveying section to the feed pipe lift section in the primary separator is (0.1-1):1. Preferably, the diameter ratio of the feed pipe conveying section to the feed pipe lift section is (0.5-0.8):1.

[0043] The diameter of the feed pipe conveying section is smaller than that of the stripping section, which can reduce the downward speed of the catalyst and allow the oil and gas carried in the catalyst to be removed more completely.

[0044] In some embodiments, a guide cone is provided below the outlet of the feeding section conveying pipe. The guide cone is a conical structure with a cross-section that gradually increases from top to bottom, and the conical surface of the conical structure gradually bends away from the center line of the cone from the apex to the bottom edge.

[0045] Compared to the end with the largest cross-section of the guide cone, the end with the smallest cross-section of the guide cone is closer to the outlet of the feeding section conveying pipe.

[0046] The guide cone can be fixed below the outlet of the feed section conveying pipe using various methods available in the art. For example, it can be fixed to the wall of the settling tank using a support frame, or fixed to the primary separator. This application does not impose any limitations, as long as the fixing element does not substantially affect the movement of the catalyst.

[0047] The purpose of the guide cone is to buffer the force of the catalyst falling into the settler, reduce the impact on the catalyst, and prevent the catalyst from breaking due to impact. At the same time, it also serves to disperse the catalyst.

[0048] In some implementations, the ratio of the distance between the lower surface of the guide cone and the outlet of the primary separator feed pipe to the diameter of the feed port is (0.5-3):1.

[0049] In some implementations, the lower surface of the guide cone is circular, and the ratio of the diameter of the lower bottom surface of the guide cone to the diameter of the discharge port is (1-5):1.

[0050] In some implementations, the area of ​​the lower bottom of the guide cone is larger than the area of ​​the outlet.

[0051] The catalyst and oil gas discharged from the reactor outlet undergo gas-solid separation in the primary separator, achieving a gas-solid separation efficiency of 50-95%. The oil gas separated in the primary separator carries a small amount of catalyst into the cyclone separator, reducing the load on the cyclone separator.

[0052] In some embodiments, the cyclone separator of this application includes a coarse cyclone separator and a high-efficiency cyclone separator, with the outlet of the primary separator connected to the coarse cyclone separator.

[0053] The coarse cyclone separator includes a main body and a feed pipe. The feed pipe includes a degassing section and a conveying section. The upper end of the degassing section is connected to the lower end of the main body, and the lower end of the degassing section is connected to the upper end of the conveying section.

[0054] In the degassing section of the feed pipe of the coarse cyclone separator.

[0055] In some embodiments, a guide cone is provided below the outlet of the feed section of the coarse cyclone separator. The guide cone is a conical structure with a cross-section that gradually increases from top to bottom, and the conical surface of the conical structure gradually bends away from the center line of the cone from the apex to the bottom edge.

[0056] In some implementations, the ratio of the distance between the bottom surface of the guide cone and the outlet of the coarse cyclone separator discharge pipe to the discharge port diameter is (0.5-3):1.

[0057] To further improve gas-solid separation, the catalyst and oil gas pass through a coarse cyclone separator and then enter a high-efficiency cyclone separator. The coarse cyclone separator and the high-efficiency cyclone separator are connected by a straight pipe.

[0058] The settling device of this application can be used as a settling device in a reactor for catalytic cracking reaction or catalytic fission, or as a settling device in a catalyst regenerator.

[0059] The settler of this application is preferably suitable for catalytic cracking or cracking reaction units, wherein the mass ratio of catalyst to feedstock is 5-80, and the reaction temperature is 500-800℃.

[0060] The main technical advantages of this invention are as follows: By sequentially setting a gas-solid primary separator, a coarse cyclone separator, and a high-efficiency cyclone separator at the riser outlet, the gas-solid primary separator is used to perform preliminary separation of oil and gas and catalyst, separating most of the catalyst and reducing the load on the coarse cyclone separator, thereby avoiding catalyst runoff; at the same time, by setting stripping sections or degassing sections in the lower part of the gas-solid primary separator and the coarse cyclone separator, the oil and gas carried by the catalyst are removed, thereby avoiding coking in the settling tank and improving the unit's resistance to fluctuations.

[0061] On another front, a fluidized bed reactor includes a riser reactor and a settling tank, with the settling tank located above the riser reactor. The riser reactor has an outlet on the upper side wall of the riser pipe and is closed at the top. The settling tank includes a settling tank, a primary separator, and a cyclone separator, which are housed within the settling tank. The primary separator includes a bend and a feed pipe connected to the bend. The first end of the bend is connected to the outlet of the riser pipe, and the second end of the bend is connected to the cyclone separator. The bend bends upward from its connection to the side wall of the reactor. The feed pipe includes a feed pipe air-lift section and a feed pipe conveying section.

[0062] The riser reactor includes a dense phase reaction section and a dilute phase transport section, wherein multiple catalyst inlets are provided in the axial direction of the dense phase transport section.

[0063] By setting up multiple catalyst inlets, the temperature difference within the dense phase reaction section can be reduced, thereby improving the selectivity of the reaction.

[0064] The following describes the settling device of the present invention and the reaction system using the settling device in further detail with reference to specific embodiments.

[0065] like Figure 1 As shown, the settling device in this experimental example is used in a riser reactor. The circulating fluidized bed reactor system in this embodiment includes a reactor and a catalyst regeneration device. The reactor includes a reactor and a settling device located above the reactor. The reactor includes a pre-lifting section 3, a dense phase conveying bed reactor section 4, a reactor transition section 10, and a riser 11, which are connected and communicated from top to bottom. The pre-lifting medium conveying pipe 3 is placed inside the pre-lifting pipe 3. The reactor settling device 12 is equipped with a primary separator 20, a coarse cyclone separator 22, and a high-efficiency cyclone separator 23. The riser 11 can extend into the reactor settling device 12 or be located outside the reactor settling device 12. However, regardless of the arrangement of the riser 11, the sidewall of the riser 11 is connected to the first end of the primary separator 20, the second end of the primary separator 20 is connected to the coarse cyclone separator 22, and the coarse cyclone separator 22 is connected to the high-efficiency cyclone separator 23.

[0066] The catalyst regeneration unit includes a regenerator 17 and a regenerator settling tank 15. The regenerator settling tank 15 is connected to the reactor transition section 10 via an upper regeneration inclined tube 8 and to the pre-lifting tube 3 via a lower regeneration inclined tube 7. The reactor regenerator 12 is connected to the regenerator 17 via a waiting-to-regenerate inclined tube 14.

[0067] Combined as attached Figure 2 The structure of the primary separator and the coarse cyclone separator is further described in detail.

[0068] The primary separator 20 is connected to the side wall of the riser pipe 11. The primary separator 20 includes a bend and a feed pipe connected to the bend. The first end of the bend of the primary separator 20 is connected to the riser pipe 11, and the bend bends upward. The second end of the bend is connected to the coarse cyclone separator 22. In the longitudinal section of the bend, the side closest to the central axis of the riser pipe 11 (the upper edge) is semi-circular, and the side furthest from the central axis of the riser pipe 11 (the lower edge) is arc-shaped, with a central angle of 80°.

[0069] The primary separator 20's feed pipe includes a feed pipe conveying section 21 and a feed pipe air lift section 25. The feed pipe air lift section 25 is located above the feed pipe conveying section 21, and its upper end is connected to and communicates with the lower edge of the bend. A guide cone 24 is provided below the feed pipe conveying section 21. The diameter of the primary separator's feed pipe air lift section 25 is three times the diameter of the lift pipe 3 and three times the diameter of the feed pipe conveying section 21. The length ratio of the primary separator's feed pipe air lift section to the feed pipe conveying section is 1:2. The distance between the guide cone 24 and the lower opening of the primary separator's feed pipe conveying section 21 is 0.3m.

[0070] After the oil and gas pass through the primary gas-solid separator, 80% of the catalyst enters the gas lift section 25 of the primary gas-solid separator feed pipe. The gas lift medium, water vapor 16, enters the gas lift section of the primary gas-solid separator feed pipe through the distribution pipe to remove part of the oil and gas. The catalyst passes through the conveying section 21 of the primary gas-solid separator feed pipe downwards, and after passing through the guide cone 24, it is redistributed and enters the settling tank.

[0071] In this embodiment, the reaction process of the reactor includes: the regenerated catalyst enters the pre-lifting section 3 through the lower regeneration inclined pipe 7, and the pre-lifting medium 1 is introduced from the lower end of the pre-lifting section 3. The pre-lifting medium 1 carries the regenerated catalyst upward into the dense phase conveying reaction section 4. In the dense phase conveying reaction section 4, the dilution medium 5 and crude oil 6 are introduced. In the dense phase conveying reaction section 4, the raw materials undergo a catalytic reaction as the catalyst flows upward, and enter the reactor transition section 10. The regenerated catalyst conveyed by the upper regeneration inclined pipe is carried into the transition section 10 by the conveying medium 9. The catalyst, oil and gas from the dense phase reaction section 4, and the newly input regenerated catalyst flow upward together into the riser pipe 11. The catalyst and oil and gas discharged from the outlet of the riser pipe 11 enter the primary separator 20, the coarse cyclone separator 22, and the high-efficiency cyclone separator 23 in the settling tank for gas-solid separation. The separated oil and gas enter the oil and gas separation system 13.

[0072] The separated catalyst is carried into the regenerator 17 via the inclined tube 14 and the conveying medium 18. In the regenerator settling tank of the regeneration unit, the stripping medium 26 is introduced to further remove the adsorbed gas from the gas-solid separated regenerated catalyst.

[0073] Example 2

[0074] Based on Example 1, this example further defines the structure of the coarse cyclone separator.

[0075] The oil, gas and catalyst that have been initially separated by the primary separator 20 enter the coarse cyclone separator 22 for further separation.

[0076] The upper part of the primary separator is bent and connected to the side wall of the coarse cyclone separator in an arc shape. On the longitudinal section of the bend, the side away from the central axis of the riser 11 is a smooth surface. That is, there are no further restrictions on the degree of bending on the side away from the central axis of the riser 11 between the feed pipe and the inlet of the coarse cyclone separator, and the ratio of the cross section of each part of the bend to the diameter of the riser pipe should satisfy (1-5):1.

[0077] The coarse cyclone separator includes a main body, a degassing section 27 of the coarse cyclone separator's feed pipe, and a conveying section 28 of the feed pipe, connected sequentially from top to bottom. A flow cone 24 is installed below the outlet of the conveying section 28. After the gas is degassed in the degassing section 27 of the feed pipe, it enters the coarse cyclone separator's feed pipe 28 and is then dispersed into the settling tank by the flow cone 24.

[0078] Preferably, the length ratio of the main body of the coarse cyclone separator 22 to the degassing section 27 of the coarse cyclone separator discharge pipe is 1:1, and the ratio of the diameter of the necking point between the two to the diameter of the coarse cyclone separator 22 is 0.5:1. The diameter ratio of the conveying section 28 of the coarse cyclone separator discharge pipe to the degassing section 27 of the coarse cyclone separator discharge pipe is 0.5:1, and the length ratio is 2:1.

[0079] After entering the coarse cyclone separator, the oil and gas and the catalyst enter the high-efficiency cyclone separator 23. The catalyst after the oil and gas are removed enters the settling tank through the feed pipe. Together with the catalyst separated by the gas-solid primary separator and the coarse cyclone separator, it enters the regenerator for coking through the waiting inclined tube.

[0080] The reactor configuration using the settling tank structure of Example 2 was employed. The reaction conditions were as follows: feedstock was Daqing crude oil; catalyst was MMC-2 catalytic cracking catalyst; the mass ratio of catalyst to feedstock was 30; and the reaction temperature was controlled at approximately 500°C. After reaction, the mixture was separated by a settling tank, with catalyst loss of only 1%. This indicates low catalyst loss and strong resistance to fluctuations in the reactor's performance.

[0081] Comparative Example

[0082] The comparative example differs from Example 2 only in the configuration of the cyclone separator in the reactor settling tank; all other process conditions are the same. In this comparative example, the primary separator of this application is not used; instead, a conventional two-stage cyclone separator is used: a primary cyclone separator and an inlet top cyclone separator. The riser outlet is connected to the primary cyclone separator, and the primary cyclone separator outlet is connected to the top cyclone separator inlet. The gas-solid separation process is as follows: high-temperature oil gas and catalyst directly enter the primary cyclone separator, then the top cyclone separator. The oil gas enters the gas collection chamber and is transported via oil gas pipeline to the bottom of the fractionation tower for fractionation. The separated catalyst is discharged from the wing valves at the bottom of the primary and top cyclone separators, reaches the bottom of the settling tank, and enters the regenerator for coking via the waiting inclined pipe.

[0083] The reactor configuration using this comparative settling device is as described in Example 2, with other reaction conditions as shown in Example 2. The difference is that the mass ratio of catalyst to feed oil reaches 10, and after the reaction, the catalyst is separated by the settling device, resulting in a catalyst loss of 10%.

Claims

1. A circulating fluidized bed reactor for crude oil catalytic cracking, comprising: The riser reactor and the settling tank located above the riser reactor have an outlet on the upper side wall of the riser tube and are closed at the top. The settling device includes: a settling tank, a primary separator and a cyclone separator disposed within the settling tank. The primary separator includes a bend and a feed pipe connected to the bend. The first end of the bend is connected to the outlet of the riser, and the second end of the bend is connected to the cyclone separator. The bend bends upward from its connection with the side wall of the riser reactor. The feed pipe of the primary separator includes a feed pipe air-lift section and a feed pipe conveying section. The bend includes a smoothly transitioning curved section. From the first end to the second end of the bend, relative to the reactor's central axis, the curved section first extends away from the central axis and then towards it. In the longitudinal section of the bend, the side closest to the reactor's central axis is an arc, with a central angle of 120° to 240°. From the first end to the second end of the bend, the cross-section of the bend first increases and then decreases.

2. The circulating fluidized bed reactor according to claim 1, characterized in that, In the longitudinal section of the bend, the lower edge of the bend is connected to the upper end of the feed pipe, so that the feed pipe and the bend are connected.

3. The circulating fluidized bed reactor according to claim 2, characterized in that, The lower edge of the bend between the first end of the bend and the feed pipe is arc-shaped, and the central angle of the arc is between 0 and 90 degrees. o .

4. The circulating fluidized bed reactor according to claim 2, characterized in that, The lower edge of the bend between the first end of the bend and the feed pipe is arc-shaped, with a central angle of 5-80 degrees. o .

5. The circulating fluidized bed reactor according to any one of claims 1-4, characterized in that, The ratio of the cross-sectional diameter of the primary separator bend to the diameter of the riser pipe is (1-5):

1.

6. The circulating fluidized bed reactor according to any one of claims 1-4, characterized in that, The ratio of the cross-sectional diameter of the primary separator bend to the diameter of the riser pipe is (1-3):

1.

7. The circulating fluidized bed reactor according to any one of claims 1-4, characterized in that, The upper end of the air-lift section of the feed pipe is connected to the lower edge of the bend, and the lower end of the air-lift section of the feed pipe is connected to the upper end of the feed pipe conveying section. A gas distributor is installed inside the air-lift section of the feed pipe.

8. The circulating fluidized bed reactor according to claim 7, characterized in that, The stripping medium enters the stripping section of the feed pipe via a gas distributor. The catalyst after passing through the primary separator also enters the stripping section of the feed pipe. The stripping medium includes nitrogen or water vapor.

9. The circulating fluidized bed reactor according to claim 8, characterized in that, The gas velocity of the stripping medium at the outlet of the gas distributor is 0.1-5 m / s.

10. The circulating fluidized bed reactor according to claim 8, characterized in that, The gas velocity of the stripping medium at the outlet of the gas distributor is 0.5-3 m / s.

11. The circulating fluidized bed reactor according to claim 7, characterized in that, In the feed pipe of the primary separator, the diameter ratio of the feed pipe conveying section to the feed pipe air-lifting section is (0.1-1):

1.

12. The circulating fluidized bed reactor according to claim 7, characterized in that, In the feed pipe of the primary separator, the diameter ratio of the feed pipe conveying section to the feed pipe air-lifting section is (0.5-0.8):

1.

13. The circulating fluidized bed reactor according to any one of claims 1-4, characterized in that, A guide cone is installed below the outlet of the feed pipe of the primary separator or cyclone separator.

14. The circulating fluidized bed reactor according to claim 13, characterized in that, The guide cone is a cone-shaped structure with a cross-section that gradually increases from top to bottom. The cone-shaped surface of the cone structure gradually bends away from the cone's center line from the cone's apex to its base.

15. The circulating fluidized bed reactor according to claim 14, characterized in that, The ratio of the distance between the lower bottom surface of the guide cone and the discharge pipe outlet of the primary separator or cyclone separator to the discharge port diameter is (0.5-3):

1.

16. The circulating fluidized bed reactor according to claim 14, characterized in that, The ratio of the bottom surface of the guide cone to the diameter of the discharge port is (1-5):

1.

17. The circulating fluidized bed reactor according to any one of claims 1-4, characterized in that, The cyclone separator includes a coarse cyclone separator and a high-efficiency cyclone separator, with the outlet of the primary separator connected to the coarse cyclone separator.

18. The circulating fluidized bed reactor according to claim 17, characterized in that, The coarse cyclone separator includes a main body and a feed pipe. The feed pipe includes a feed pipe air lift section and a feed pipe conveying section. The upper end of the feed pipe air lift section is connected to the lower end of the main body, and the lower end of the feed pipe air lift section is connected to the upper end of the feed pipe conveying section.

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