Anti-coking precipitator

Abstract

The application relates to a kind of precipitator, comprising: precipitator tank, primary separator and cyclone separator, primary separator is arranged outside the precipitator tank, wherein, primary separator includes separator body, air inlet, air outlet and downcomer, the outlet end of downcomer is located in the precipitator tank, and air outlet is communicated with separator body and cyclone separator. By arranging primary separator outside the precipitator, the probability of coking in the precipitator is greatly reduced.

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 preventing coking, belonging to the petrochemical field. Background Technology

[0002] Coking in catalytic cracking / pyrolysis units prevents continuous, long-term operation, causing significant economic losses for companies. The physical factors contributing to coking in settling tanks primarily involve the condensation of heavy components in the reactive oil and gas and their adhesion to the catalyst and internal components of the settling tank. Reducing the condensation of heavy components can effectively inhibit coking in the settling tank. If the temperature is below the dew point temperature at the partial pressure of the oil and gas, heavy components will condense and precipitate, adhering to the catalyst and being captured by the tank walls or internal components, thus forming coke. Generally, heavy components in the oil and gas are the root cause of coking. The flow conditions, temperature distribution, oil and gas residence time, and operating methods within the settling tank have a significant impact on coking.

[0003] 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.

[0004] 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.

[0005] 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.

[0006] Chinese patents ZL92112441.4 and ZL96103419.X, US patent US5158669, and European patent EP0593827A1, etc., directly connect a pre-stripping section to the lower part of the coarse cyclone separator at the end of the riser reactor, reducing the amount of oil and gas sprayed downward from the material leg of the coarse cyclone separator and shortening the residence time of the reaction oil and gas in the settling tank.

[0007] Chinese patents ZL201410613806.8, ZL201320042717.3, and ZL200910180443.2 address the condensation and coking problems of heavy oil and gas components at the top, middle, and bottom of the settling tank, respectively. They reduce coking in the catalytic cracking 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 settling tank.

[0008] However, these patents 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. They lack solutions 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.

[0009] Chinese patents ZL200310121301.1 and ZL200510017707.4 propose introducing a regenerated catalyst or a high-temperature, high-activity regenerator into the stripping section. By increasing the temperature and catalyst activity in the stripping section, an environment is created where the oil and gas (often heavy components prone to coking) entrained or adsorbed between or within catalyst particles react and transform into lighter oil and gas within the stripping section, thereby eliminating the inherent factors causing coking in the settling tank and reducing 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 reduce coking within the settling tank. By installing a primary separator outside the settling tank, coking within the settling tank is significantly reduced.

[0012] Another objective of this application is to remove the condensed oil and gas and the adhering catalyst from the wall of the settling tank by flushing the inner wall of the settling tank.

[0013] The settling device provided in this application includes: a settling tank, a primary separator, and a cyclone separator. The primary separator is located outside the settling tank. The primary separator includes a separator body, an air inlet, an air outlet, and a discharge inclined pipe. The outlet end of the discharge inclined pipe is located inside the settling tank, and the air outlet is connected to the separator body and the cyclone separator.

[0014] The oil and gas discharged from the reactor, along with the catalyst, enter the primary separator through the inlet. After gas-solid separation in the primary separator, some of the catalyst is discharged into the settling tank through the feed inclined pipe of the primary separator, which can reduce coking on the settling tank wall. Attached Figure Description

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

[0016] Figure 2 A schematic diagram of the fluidized bed reaction system used in Comparative Example 1. Detailed Implementation

[0017] The anti-coking settling device 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.

[0018] Unless the context otherwise requires, the terms “comprising” and “including” in the specification and claims shall be understood as open-ended and inclusive, meaning “including, but not limited to”.

[0019] 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.

[0020] 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.

[0021] 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.

[0022] 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.

[0023] In this application, the catalyst-oil-gas mixture after reactor reaction undergoes preliminary separation of the oil-gas and catalyst. The catalyst is then degassed before entering the settling tank. This reduces the proportion of oil-gas directly entering the settling tank and increases the removal rate of oil-gas carried by the catalyst. Simultaneously, the pre-separated catalyst adsorbs the oil-gas within the settling tank and washes away any small amounts of catalyst or coke deposited on the settling tank or its internal components. This increases the temperature of the settling tank and prevents coking of the oil-gas within it.

[0024] A settling device includes: a settling tank, a primary separator, and a cyclone separator. The primary separator is located outside the settling tank. The primary separator includes a separator body, an air inlet, an air outlet, and a discharge inclined pipe. The outlet end of the discharge inclined pipe is located inside the settling tank, and the air outlet is connected to the separator body and the cyclone separator.

[0025] The air inlet of the primary separator is connected to the separator body and the reactor. The oil and gas and catalyst in the reactor enter the primary separator through the air inlet.

[0026] In some embodiments, the feed slant of the primary separator extends into the settling tank through the tank wall, and the feed slant inside the settling tank is substantially perpendicular to the tank wall. The feed slant inside the settling tank is kept as short as possible, so that the catalyst discharged through the feed slant can provide a larger area of ​​scouring for the settling tank wall.

[0027] The catalyst entering the middle of the settling tank from the primary separator will fall from top to bottom to the bottom of the settling tank, thereby scouring the feed pipe of the cyclone separator and the walls of the settling tank, preventing the newly condensed oil and gas and the adhering catalyst from accumulating and coking over a long period of time. At the same time, it will also adsorb some of the coking components that are easily adsorbed and condensed in the settling tank.

[0028] In some embodiments, the separator body of the primary separator is a tank with a circular cross-section, and the ratio of the cross-sectional diameter of the separator body to the diameter of the reactor outlet is (1-8):1, preferably (2-5):1.

[0029] The amount of catalyst carried by the oil and gas from the separator outlet into the primary cyclone separator is controlled by adjusting the diameter and outlet size of the separator body.

[0030] The reactor can have various structures, such as a riser with a constant diameter or a riser with a variable diameter.

[0031] In some implementations, the outlet of the primary separator is connected to the inlet of the cyclone separator via a smoothly transitioning bend.

[0032] Preferably, the cross-section of the bend is circular and of uniform diameter, and the diameter ratio of the bend to the reactor outlet is (0.1-2):1, preferably (0.5-1.5):1.

[0033] The bend in the pipe ensures that the oil and gas flow smoothly into the cyclone separator, eliminating problems such as easy catalyst deposition. On the other hand, adjusting the oil and gas speed can adjust the proportion of catalyst deposited or the amount of catalyst carried by the oil and gas into the coarse cyclone.

[0034] The diameter of the separator body is larger than the outlet diameter of the primary separator.

[0035] In some embodiments, the feed slant of the primary separator includes a horizontal section and a vertical section. The horizontal section is located below the vertical section and is connected to the bottom of the separator body. The horizontal section extends at least partially into the settling tank. The horizontal section is substantially parallel to the horizontal plane, and the vertical section is a pipe for conveying the catalyst downward.

[0036] The settling tank includes an enlarged section and a stripping section, with the enlarged section located above the stripping section. The cross-section of the settling tank is preferably circular, and in a plane perpendicular to the central axis of the settling tank, the diameter of the enlarged section is larger than the diameter of the stripping section.

[0037] In some implementations, the feed duct of the primary separator extends into the settling tank through the wall of the expanded section of the settling tank.

[0038] Preferably, the height h of the horizontal section of the feed inclined tube of the primary separator and the lower edge of the expansion section of the settling tank is (0.1-0.9):1, more preferably (0.2-0.5):1.

[0039] The catalyst temperature entering the expansion section (middle of the settler) directly from the feed pipe of the primary separator is higher than the catalyst temperature exiting through the feed pipe of the cyclone separator inside the settler. Injecting this relatively high-temperature catalyst in the middle of the settler can increase the temperature inside the settler and prevent oil and gas from condensing and coking on the settler shell or the feed pipe of the cyclone separator.

[0040] In some embodiments, the gas velocity at the outlet of the primary separator's feed duct into the settler is 2-50 m / s, preferably 3-30 m / s.

[0041] In a typical reaction system, at this gas velocity, the coke particles on the walls of the settling tank can be washed away without causing too much impact on the equipment.

[0042] The ratio of the diameter of the feed inclined tube of the primary separator to the diameter of the reactor outlet is (0.1-3):1, preferably (0.8-2):1.

[0043] The feed tube has a circular cross-section and is of constant diameter.

[0044] In some implementations, an anti-scorching net is provided in the expanded section of the settling device.

[0045] The anti-scorching mesh can be a sheet structure made of high-temperature resistant stainless steel or other materials. Preferably, the anti-scorching mesh is a sheet mesh, the shape of which is the same as the cross-section of the expanded diameter section of the settling tank.

[0046] Inside the settling tank, the anti-scorching mesh is located above the horizontal section of the feed inclined pipe of the primary separator.

[0047] The ratio of the distance between the anti-scorching net and the lower edge of the settling device's expansion section to the height of the settling device's expansion section is (0.2-0.9):1, preferably (0.2-0.6):1.

[0048] In some embodiments, at least a portion of the anti-scorching mesh has openings. Preferably, the ratio of the opening rate to the total area of ​​the anti-scorching mesh is (0.1-0.9):1, more preferably (0.2-0.6):1.

[0049] A slag-prevention net is installed in the upper part of the settling tank to prevent coke from falling to the bottom.

[0050] By installing an anti-coking screen, coke particles on the settling tank wall above the screen will not fall into the constricted section of the settling tank, thus not affecting the turbulent state of the catalyst at this point. Consequently, the catalyst can smoothly enter the regenerator, ensuring catalyst fluidization throughout the entire reaction-regeneration system.

[0051] In some embodiments, a gas distributor is disposed within the separator body of the primary separator. Preferably, the gas distributor is located within the separator body near the feed inclined tube.

[0052] The gas distributor can be a structure commonly used in the fields of petroleum catalytic cracking or catalytic decomposition, such as a ring tube with gas outlet holes evenly distributed on the tube wall.

[0053] The stripping medium enters the separator body through a gas distributor. After passing through the primary separator, the catalyst is degassed by the stripping medium to remove any carried oil and gas. The degassed catalyst then enters the feed inclined pipe. As a result, the amount of oil and gas carried in the catalyst discharged through the feed inclined pipe is greatly reduced.

[0054] The stripping medium includes nitrogen or water vapor.

[0055] Preferably, the outlet gas velocity of the stripping medium at the gas distributor is 0.5-50 m / s, more preferably 0.8-30 m / s.

[0056] This application involves installing a primary separator outside the settling tank, located between the reactor (e.g., a riser reactor) and the settling tank. Oil and gas from the reactor outlet, along with the catalyst, enter the primary separator. After initial separation, most of the oil and gas, carrying a small amount of catalyst, enters the cyclone separator inside the settling tank from the top of the primary separator. During its descent, most of the catalyst in the primary separator undergoes further stripping to remove the carried oil and gas before entering the settling tank. This reduces the concentration of oil and gas entering the settling tank, thus preventing coking in the settling tank.

[0057] In some embodiments, the cyclone separator of this application includes a primary cyclone separator and a secondary cyclone separator, with the outlet of the primary separator connected to the primary cyclone separator.

[0058] The primary 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.

[0059] A gas distributor is installed in the degassing section of the feed pipe of the primary cyclone separator.

[0060] The stripping medium enters the degassing section via a gas distributor. After being separated by the main body of the primary cyclone separator, the catalyst is degassed by the stripping medium to remove any carried oil and gas. The degassed catalyst then enters the feed pipe conveying section. As a result, the amount of oil and gas carried in the catalyst discharged through the feed pipe is greatly reduced.

[0061] The stripping medium includes nitrogen or water vapor.

[0062] Preferably, the outlet gas velocity of the stripping medium at the gas distributor is 0.5-50 m / s, more preferably 0.8-30 m / s.

[0063] To further improve gas-solid separation, the catalyst and oil / gas pass through a primary cyclone separator before entering a secondary cyclone separator.

[0064] The settling device of this application can be used as a settling device in a reactor for catalytic cracking or catalytic pyrolysis, or as a settling device in a catalyst regenerator. This includes, but is not limited to, settling devices in reactors for naphtha cracking, crude oil cracking, light hydrocarbon cracking, and olefin cracking.

[0065] The settling device of this application can be used in combination with all existing reactors, such as with conventional riser, double riser, or riser reactor structures with expanded diameter.

[0066] The settling device of this application is preferably suitable for catalytic cracking reaction equipment, wherein the mass ratio of catalyst to feed oil is 3-80, and the reaction temperature is 500-800℃.

[0067] The main technical advantages of this invention are as follows: By setting a primary separator between the riser and the settling tank, most of the high-temperature catalyst is separated from the oil and gas. During the descent, the catalyst undergoes another gas lift to remove any carried oil and gas before entering the middle of the settling tank. On one hand, the scouring of the settling tank wall and the discharge port of the cyclone separator within the settling tank significantly reduces coking on the settling tank wall. On the other hand, the increased proportion of condensed heavy components on the catalyst after separation by the primary separator reduces the proportion of heavy components that coke inside the settling tank. Furthermore, the relatively high-temperature catalyst (compared to the catalyst in the cyclone separator) entering the settling tank increases the settling tank temperature, significantly reducing the phenomenon of oil and gas condensing and coking on the settling tank and discharge pipe. Therefore, the settling tank of this application minimizes coking.

[0068] 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.

[0069] like Figure 1 As shown, the settling device in this experimental example is used in a riser reactor. The reactor in this embodiment includes a riser reactor 2 and a settling device 12 located outside the reactor. A primary separator 3 is installed outside the reactor settling device. The primary separator 3 is connected to both the riser reactor 2 and the settling device 12.

[0070] The reactor settling tank 12 includes an expansion section 12' and a stripping section 12'". The expansion section 12' is located above the stripping section 12'. In this embodiment, the cross-sections of the expansion section 12' and the stripping section 12' are circular and both are straight pipes, with the diameter of the expansion section 12' being larger than the diameter of the stripping section 12'. A primary cyclone separator 9 and a secondary cyclone separator 11 are installed inside the reactor settling tank 12. The main bodies of the primary and secondary cyclone separators are located within the expansion section of the settling tank, and the outlet of their feed pipes is located at the junction of the expansion section 12' and the stripping section 12', or within the stripping section.

[0071] The primary separator 3 includes a separator body 3', a feed inclined pipe 7, an air inlet, and an air outlet. The separator body 3' is a cylindrical tank. The feed inclined pipe 7 is located below and connected to the separator body 3'. An air inlet and an air outlet are located at the top of the separator body 3'. The air inlet is connected to the outlet of the riser reactor 2, through which the catalyst and oil / gas in the reactor enter the primary separator. The air outlet of the separator body 3' is connected to the first-stage cyclone separator 9 via a bend in the pipe. A gas distributor is installed inside the separator body 3'.

[0072] The feed incline 7, including the primary separator, comprises a horizontal section 15 and a vertical section 16. The horizontal section 15 is located below the vertical section 16 and is connected to the bottom of the separator body 3'. The horizontal section 15 extends at least partially into the settling tank. The horizontal section 15 is substantially parallel to the horizontal plane, and the vertical section 16 is a pipe for conveying the catalyst downwards. The height h of the lower edge of the horizontal section 15 of the primary separator feed incline 7 and the height of the settling tank expansion section 12' is (0.1-0.9):1, preferably (0.2-0.5):1.

[0073] An anti-scorching mesh 13 is installed within the expanded section 12' of the settling tank. The anti-scorching mesh 13 is a sheet-like mesh, the shape of which is the same as the cross-section of the expanded section of the settling tank. Inside the settling tank, the anti-scorching mesh is located above the horizontal section of the feed inclined tube of the primary separator. The ratio of the distance between the anti-scorching mesh and the lower edge of the expanded section to the height of the expanded section is (0.2-0.9):1, preferably (0.2-0.6):1. The ratio of the open area to the total area of ​​the anti-scorching mesh is (0.1-0.9):1, preferably (0.2-0.6):1.

[0074] In this embodiment, the reaction process of the reaction device includes the reaction of oil and gas and catalyst 1 moving upward in the riser 2. After the reaction, the catalyst and oil and gas enter the main body through the inlet of the primary separator 3. After gas-solid separation, the separated catalyst is injected into the settling tank 12 under the thrust of the conveying medium 8 passing through the horizontal section 15 of the feed inclined pipe 7. The oil and gas enter the first-stage cyclone separator 9 through the bend pipe 4 for gas-solid separation. The oil and gas from the first-stage cyclone separator 9 enters the second-stage cyclone separator 11 for further gas-solid separation; the separated catalyst enters the degassing section 6, where a gas distributor is installed. After being stripped by the stripping medium, the catalyst enters the settling tank through the feed pipe 10. The oil and gas separated by the first and second-stage cyclone separators are discharged from the settling tank through the oil and gas outlet.

[0075] Example 1

[0076] The present invention is used as follows Figure 1 The settling device structure shown is as follows: The feedstock is Zhongyuan crude oil, and the cracking catalyst prepared according to Example 8 of patent CN202010022024.2 is used. When the mass ratio of catalyst to feedstock reaches 50, the reaction temperature is controlled at approximately 700℃, and the unit operates continuously for 6 months without significant coking.

[0077] The ratio of the diameter of the primary separator's main body section to the riser pipe diameter is 3:1; the ratio of the diameter of the primary separator's outlet bend to the riser pipe diameter is 1.3:1; the ratio of the height h of the horizontal section of the primary separator's feed inclined pipe to the lower edge of the settling tank's expansion section to the height of the expansion section is 0.4:1; the ratio of the diameter of the primary separator's feed inclined pipe to the riser pipe diameter is 0.9:1. The gas velocity at the outlet of the primary separator's feed inclined pipe into the settling tank is 10 m / s. An anti-scorching screen is installed inside the settling tank, located above the horizontal section of the primary separator's feed inclined pipe. The ratio of the distance between the anti-scorching screen and the lower edge of the settling tank's expansion section to the height of the expansion section is 0.5:1; the ratio of the anti-scorching screen's opening ratio to its total area is 0.4:1.

[0078] Table 1 Properties of Crude Oil

[0079]

[0080] Comparative Example

[0081] The comparative example differs from Example 1 in all process conditions except for the configuration of the separator in the reactor settling tank. (See attached...) Figure 2 As shown in the comparative example, the primary separator and anti-coking screen of this application are not installed. Instead, a conventional two-stage cyclone separator is installed in the settling tank: a primary cyclone separator followed by a secondary separator. The riser outlet is connected to the primary cyclone separator, and the outlet of the primary cyclone separator is connected to the inlet of the secondary separator. The gas-solid separation process is as follows: high-temperature oil gas and catalyst directly enter the primary cyclone separator, and then enter the secondary separator. The oil gas is then transported to the bottom of the fractionation tower via an oil gas pipeline for fractionation. The separated catalyst is discharged from the wing valves at the bottom of the primary and secondary cyclone separators, reaches the bottom of the settling tank, and enters the regenerator for coking via the waiting inclined pipe.

[0082] The reactor configuration using this comparative settling device, with other reaction conditions as described in the example, resulted in coking after 30 days of operation.

Claims

1. A settling device, comprising: The settling tank, the primary separator, and the cyclone separator located inside the settling tank are all included. The primary separator is located outside the settling tank. The settling tank includes an expansion section and a stripping section. The expansion section is located above the stripping section. The primary separator includes a separator body, an air inlet, an air outlet, and a discharge inclined pipe. The outlet end of the discharge inclined pipe is located inside the settling tank, and the air outlet is connected to the separator body and the cyclone separator. The feed incline of the primary separator has a horizontal section and a vertical section. The horizontal section is located below the vertical section and is connected to the bottom of the separator body. The horizontal section extends at least partially into the settling tank. The horizontal section is basically parallel to the horizontal plane, and the vertical section is a pipe for conveying the catalyst downward. The ratio of the height h of the horizontal section of the feed inclined tube of the primary separator to the height of the expansion section of the settling tank is (0.2-0.5):1; An anti-scorching screen is installed in the expanded section of the settling tank. At least a portion of the anti-scorching screen has openings, and the anti-scorching screen is located above the horizontal section of the feed inclined tube of the primary separator.

2. The settling device according to claim 1, characterized in that, The primary separator is configured to be connected to the reactor outlet, and the ratio of the cross-sectional diameter of the primary separator body to the diameter of the reactor outlet is (1-8):

1.

3. The settling device according to claim 1, characterized in that, The primary separator is configured to be connected to the reactor outlet, and the ratio of the cross-sectional diameter of the primary separator body to the diameter of the reactor outlet is (2-5):

1.

4. The settling device according to any one of claims 1-3, characterized in that, The outlet of the primary separator and the inlet of the cyclone separator are connected by a smoothly transitioning bend.

5. The settling device according to claim 4, characterized in that, The cross-sectional diameter of the separator body of the primary separator is larger than the diameter of the outlet of the primary separator.

6. The settling device according to claim 4, characterized in that, The primary separator is configured to connect to the reactor outlet, with the diameter ratio of the bend to the reactor outlet being (0.1-2):

1.

7. The settling device according to claim 6, characterized in that, The diameter ratio of the bend to the reactor outlet is (0.5-1.5):

1.

8. The settling device according to any one of claims 1-3, characterized in that, The gas velocity at the outlet of the settling tank through the feed inclined tube of the primary separator is 2-50 m / s.

9. The settling device according to any one of claims 1-3, characterized in that, The gas velocity at the outlet of the settling tank through the feed inclined tube of the primary separator is 3-30 m / s.

10. The settling device according to any one of claims 1-3, characterized in that, The feed incline is circular in cross-section, and the ratio of the diameter of the feed incline to the diameter of the riser in the primary separator is (0.1-3):

1.

11. The settling device according to any one of claims 1-3, characterized in that, The feed incline is circular in cross-section, and the ratio of the diameter of the feed incline to the diameter of the riser in the primary separator is (0.8-2):

1.

12. The settling device according to any one of claims 1-3, characterized in that, The anti-scorching mesh is a sheet-like mesh, the shape of which is the same as the cross-section of the expanded section of the settling tank.

13. The settling device according to claim 12, characterized in that, The ratio of the distance between the anti-scorching net and the lower edge of the expanded section of the settling device to the height of the expanded section of the settling device is (0.2-0.9):

1.

14. The settling device according to claim 12, characterized in that, The ratio of the distance between the anti-scorching net and the lower edge of the expanded section of the settling device to the height of the expanded section of the settling device is (0.2-0.6):

1.

15. The settling device according to claim 1, characterized in that, The ratio of the opening rate of the anti-scorching mesh to the total area of ​​the anti-scorching mesh is (0.1-0.9):

1.

16. The settling device according to claim 1, characterized in that, The ratio of the opening rate of the anti-scorching mesh to the total area of ​​the anti-scorching mesh is (0.2-0.6):1.

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