Process and apparatus for the catalytic cracking of crude oil to produce light olefins

Abstract

A reaction method for preparing low carbon olefins by catalytic cracking of crude oil, comprising: passing the catalytic cracking reaction of the catalytic cracking of crude oil and the atomized crude oil into the reactor to contact each other, wherein, in the reactor, the catalyst is lifted by superheated steam above 500 DEG C and moves upward in the reactor, the outlet temperature of the reactor is controlled at 600-750 DEG C, the catalyst-oil amount and pressure drop can be reduced, and the yield of propylene and ethylene is increased. The superheated steam can be obtained by heat exchange between the heat exchanger provided in the regeneration settler of the reaction system and the flue gas, and the heat exchange process greatly reduces the temperature in the regeneration settler, avoiding the occurrence of tail combustion phenomenon. In addition, by arranging the heat exchanger in the draft tube in the reaction settler, or on this basis, additionally arranging a primary classifier, the problem of coking on the wall of the heat exchanger can be significantly solved, and the operation time of the reaction system is prolonged.

Description

TECHNICAL FIELD

[0001] The present application relates to a reaction system for catalytic cracking of crude oil, in particular, a method and device for preparing low-carbon olefins from catalytic cracking of crude oil, and belongs to the field of petroleum chemical industry. BACKGROUND

[0002] At present, the production of ethylene mainly relies on steam cracking of light hydrocarbons or naphtha. The light hydrocarbons and naphtha are mainly derived from the refining process. Generally, "ten million tons of refining can produce one million tons of ethylene", that is, ten million tons / year of refining capacity can provide the cracking raw materials needed for the production of one million tons / year of ethylene. These cracking raw materials depend on primary and secondary processing processes such as atmospheric and vacuum distillation, catalytic cracking, hydrocracking, delayed coking, and hydrofining, which have large investment, high energy consumption, and long process. If there is a shortage of finished oil, the production mode of refining + steam cracking, which combines oil products and chemical products, is reasonable, but now there is a serious surplus of finished oil, and building a refinery for ethylene production along this technical route will exacerbate the situation of surplus of finished oil.

[0003] Direct cracking of crude oil to produce low-carbon olefins no longer relies on the refining process to produce steam cracking raw materials, so the process is short, the investment is small, and the energy consumption is low. Compared with steam cracking combined with refining, direct cracking of crude oil to produce low-carbon olefins reduces the consumption of crude oil by more than 60% when producing the same amount of ethylene. The substantial reduction in the consumption of crude oil for olefin production will greatly alleviate the demand for crude oil.

[0004] Direct catalytic cracking of crude oil directly produces ethylene and propylene across the refining process, which has a short process, low energy consumption, and small investment and land occupation. The hydrocarbons generated by the catalytic cracking reaction of crude oil, except methane, ethylene, propylene, and aromatics, can be directly or hydrogenated and then recycled. However, direct catalytic cracking of crude oil has a series of problems, such as low yield of low-carbon olefins, and problems such as affecting the long-period operation of the entire system due to coking in the reaction system. SUMMARY

[0005] The first object of the present application is to improve the conversion rate of low-carbon olefins such as ethylene and propylene produced by catalytic cracking of crude oil and to improve the yield of ethylene and propylene.

[0006] The second object of the present application is to reduce or prevent coking in the settler and heat exchange device of the reaction system for producing low-carbon olefins by catalytic cracking of crude oil, thereby prolonging the operation period of the entire device.

[0007] The third object of the present application is to avoid tail combustion in the catalyst regenerator and to reduce the material requirements of the internals in the settler of the regenerator in the reaction system for producing low-carbon olefins by catalytic cracking of crude oil.

[0008] In one aspect,A reaction method for preparing low carbon olefins by catalytic cracking of crude oil, comprising: passing the catalytic cracking of crude oil and atomized crude oil into the reactor to contact each other, wherein, in the reactor, the catalyst is lifted by superheated steam above 500 DEG C in the reactor from bottom to top, and the outlet temperature of the reactor is controlled at 600-750 DEG C.

[0009] In the present application, since the catalyst in the reactor is lifted by superheated steam above 500 DEG C, under the conditions of the reactor outlet temperature, catalyst temperature, feed temperature and feed amount, the higher the temperature of the pre-lifted steam, the smaller the catalyst-oil ratio (the ratio of catalyst to crude oil), that is, the smaller the amount of catalyst circulating, and further, the smaller the pressure drop in the reaction process, thus improving the yield and selectivity of ethylene and propylene.

[0010] In another aspect A reaction system for preparing low carbon olefins by catalytic cracking of crude oil, comprising a reactor, a catalyst regenerator and a heat exchanger, wherein the reactor and the catalyst regenerator are connected by a pipeline, the catalyst regenerator comprises a regeneration reactor and a regeneration settler, the regeneration settler is located above the regeneration reactor, the heat exchanger is located in the dilute phase section of the regeneration settler, and low pressure steam is passed into the heat exchanger to exchange heat with the spent catalyst in the regeneration settler to become superheated steam, which is passed into the bottom of the reactor.

[0011] By arranging the heat exchanger in the dilute phase section of the regeneration settler, on the one hand, the high temperature regenerated catalyst in the dilute phase section exchanges heat with the low pressure steam in the heat exchanger, the low pressure steam becomes superheated steam, which is passed into the reactor for preparing low carbon olefins by catalytic cracking of crude oil, so as to reduce the catalyst-oil ratio and further improve the yield and selectivity of ethylene and propylene. On the other hand, in the dilute phase section of the regeneration settler, the high temperature flue gas and the catalyst exchange heat with the low pressure steam, so as to greatly reduce the temperature of the flue gas and avoid the tail combustion phenomenon in the regeneration settler.

[0012] In still another aspect A reaction system for preparing low carbon olefins by catalytic cracking of crude oil, comprising a reactor, a reaction settler and a heat exchanger, wherein the reaction settler is provided with a flow guide cylinder with upper and lower openings, and the heat exchanger is arranged in the flow guide cylinder in the reaction settler.

[0013] In the reaction system, the high temperature oil gas and spent catalyst discharged from the reactor enter the flow guide cylinder in the reaction settler, most of the spent catalyst loses the right downward driving force and settles, and the rest of the spent catalyst flows upward in the flow guide cylinder under the driving of the oil gas, passes through the heat exchanger, has a scouring effect on the side wall of the heat exchanger, reduces the coking of the oil gas on the side wall of the heat exchanger, and can also adsorb the condensed oil.

[0014] In the reaction system of the present application, by setting a heat exchanger on the dilute phase section of the regeneration settler, the tail combustion phenomenon in the regenerator can be avoided, and the excess heat of the regenerated catalyst can be used to heat the low-pressure steam into superheated steam. In the reactor, the superheated steam is used to lift the catalyst, or to atomize the crude oil feedstock, which can reduce the catalyst to oil ratio, and thus improve the selectivity and yield of ethylene and propylene.

[0015] On the other hand, the high-temperature oil gas and spent catalyst discharged from the reactor are introduced into the draft tube in the reaction riser, and part of the spent catalyst passes through the heat exchanger in the draft tube. The spent catalyst can not only adsorb the condensed liquid phase oil, but also rub against the wall of the heat exchanger, and timely wipe off the oil coking precursors or coke and other substances on the wall. Therefore, coking in the heat exchanger is effectively prevented, and the catalyst heat is reasonably utilized. BRIEF DESCRIPTION OF DRAWINGS

[0016] Figure 1 The structure schematic diagram of the first embodiment of the fluidized bed reaction system of the present application.

[0017] Figure 2 The structure schematic diagram of the second embodiment of the reactor of the fluidized bed reaction system of the present application.

[0018] Figure 3 The structure schematic diagram of the third embodiment of the fluidized bed reaction system of the present application. DETAILED DESCRIPTION

[0019] The fluidized bed reaction system for preventing coking in the catalytic cracking of crude oil to produce low-carbon olefins of the present application will be described in further detail below. The protection scope of the present application is not limited by the following detailed description, and is defined by the claims. Certain disclosed specific details provide a comprehensive understanding of each disclosed embodiment. However, it is known to those skilled in the relevant art that the embodiments can also be implemented without using one or more of these specific details, or using other materials, etc.

[0020] Unless otherwise required by the context, in the specification and claims, the terms "comprise", "comprising", "include", "including", "contain", "containing", "have", "having", "consist", "consisting", "consisting essentially of" should be understood as open, inclusive meanings, i.e. "including, but not limited to".

[0021] "an embodiment," "another embodiment," "certain embodiments," or the like, means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment. The appearances of the phrase "an embodiment," "another embodiment," "certain embodiments," or the like in various places in the specification are not necessarily all referring to the same embodiment. Furthermore, the particular features, structures, or characteristics can be combined in any suitable manner in one or more embodiments. Various features are described which can be used in

[0022] The application will be further described with reference to the following examples. It should be understood that these examples are for illustrative purposes only and are not meant to limit the scope of the application. Unless otherwise indicated, the experimental methods in the following examples were carried out according to conventional procedures or as recommended by the manufacturer. Unless otherwise indicated, all percentages, ratios, proportions, or parts are by weight.

[0023] The term "gas-solid separation efficiency" means the mass fraction of the total catalyst entering the separator that is separated out as a gas-solid separation.

[0024] "Light olefins" generally refer to olefins having 2 to 4 carbon atoms, such as ethylene, propylene, and butylene, and the like.

[0025] "Crude oil" generally refers to petroleum that has not been processed, and is a mixture of various liquid hydrocarbons, such as alkanes, cycloalkanes, and aromatic hydrocarbons, and the like. The main components are carbon and hydrogen, which account for 83 to 87% and 11 to 14%, respectively.

[0026] "Pressure drop" means a change in energy, and refers to the decrease in pressure of a fluid flowing in a pipe due to energy loss. It is manifested as a pressure difference before and after the fluid flows.

[0027] The term "catalyst-to-oil ratio" generally refers to the ratio of the amount of catalyst circulated per unit time to the amount of crude oil fed per unit time.

[0028] The term "water-to-oil ratio" generally refers to the mass ratio of water vapor to crude oil in the reactor.

[0029] The term "dilute phase section" of the regeneration settler generally refers to the space above the outlet of the regeneration reactor, and is defined as the space where the catalyst has a relatively low density. The regeneration settler has a cross-sectional area that is larger than that of the regeneration reactor, and the lower portion of the regeneration settler is connected to the upper portion of the regeneration reactor. The lower portion of the regeneration settler has a reverse conical structure, and the catalyst settled in the regeneration settler accumulates in the reverse conical structure of the lower portion of the regeneration settler.

[0030] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. Methods and materials similar or equivalent to those described herein can be used in the practice of the present application. The preferred materials and methods are described herein.

[0031] Direct catalytic cracking of crude oil to produce low carbon olefins such as ethylene and propylene, directly producing ethylene and propylene across the oil refining process, short process, low energy consumption, less investment and land occupation. The hydrocarbons generated by catalytic cracking of crude oil, except methane, ethylene, propylene and aromatic hydrocarbons, can be directly or hydrogenated after separation for back refining. However, there are still a series of problems in direct catalytic cracking of crude oil. On the one hand, the catalytic cracking reaction temperature of crude oil is high, the temperature difference between the regenerator and the reactor is small, the reaction heat and the water-oil ratio are high, which leads to high catalyst-oil ratio and large catalyst circulation amount, thereby causing large pressure drop in the riser reactor and high pressure in the critical reaction zone, reducing the conversion of crude oil and the yield of ethylene and propylene. On the other hand, the high-temperature oil gas heat exchange cooling will cause coking in the heat exchanger, affecting the long-period operation of the device. In addition, the catalyst regeneration temperature is about 800℃, which requires high material requirements for the internal components (such as the cyclone) of the regenerator.

[0032] In one aspect A reaction method for preparing low carbon olefins by catalytic cracking of crude oil, comprising: the catalyst and the atomized crude oil are introduced into the reactor to contact each other for catalytic cracking reaction, wherein in the reactor, the catalyst is lifted by superheated steam above 500℃ and moves upward in the reactor, and the outlet temperature of the reactor is controlled at 600-750℃.

[0033] In the reaction system for preparing low carbon olefins by catalytic cracking of crude oil, the temperature of the catalyst is 700-900℃. Preferably, 750-850℃.

[0034] In some embodiments, the catalyst is lifted by superheated steam above 600℃ and moves upward in the reactor.

[0035] Before entering the reactor, the crude oil is atomized by superheated steam with a temperature above 500℃ (preferably, superheated steam above 600℃).

[0036] The catalytic cracking of crude oil to produce low carbon olefins (e.g. ethylene and propylene) has the problems of high heat absorption, high thermal effect, small temperature difference between the reactor and regenerator (difference between the temperature of the regenerator and the outlet temperature of the riser reactor), high water / oil ratio, and high catalyst circulation rate and catalyst / oil ratio (usually greater than 30). The high catalyst / oil ratio results in high pressure drop in the reactor (riser reactor), which affects the cracking of the feedstock and the yield and selectivity of ethylene and propylene. The use of superheated steam at a temperature higher than 500°C as pre-lift steam and atomizing steam can reduce the catalyst circulation rate. This can reduce the catalyst / oil ratio and the pressure drop in the reactor (e.g. riser reactor), thereby increasing the yield of ethylene and propylene in the catalytic cracking of crude oil.

[0037] In some embodiments, the apparent average residence time of the oil gas in the reactor is 2-5 seconds, preferably 3-4 seconds.

[0038] The outlet temperature of the riser reactor is preferably controlled at 620-700°C.

[0039] In some embodiments, the ratio of the total amount of pre-lift steam and atomizing steam introduced into the reactor to the mass of the feedstock (i.e. water / oil ratio) is controlled at 0.1-1.0, preferably 0.3-0.7.

[0040] The catalyst for the catalytic cracking of crude oil in the present application can be any catalyst known in the art that can catalyze the production of low carbon olefins. The main purpose of the present application is to significantly reduce the catalyst / oil ratio, reduce the pressure drop, and thereby increase the yield of low carbon olefins (e.g. propylene and ethylene) by using superheated steam at a temperature higher than 500°C as pre-lift steam and atomizing steam in the reaction process under the same other conditions.

[0041] The feedstock is crude oil, which contains high boiling point components. Steam is required to atomize the crude oil into small droplets before it enters the reactor.

[0042] Under the conditions of a constant reactor outlet temperature, catalyst temperature, feedstock temperature, and feedstock amount, the catalyst / oil ratio in the reaction process is reduced, and the yield of ethylene and propylene is increased.

[0043] The reaction pressure is controlled at 20-100 kPa (gauge), preferably 40-70 kPa (gauge), based on the pressure in the settler.

[0044] The reaction pressure in the present application refers to the gauge pressure (gauge).

[0045] The low-pressure steam (usually at about 200℃) can be heated to superheated steam with a temperature over 500℃ by any method. In this application, the low-pressure steam exchanges heat with the regenerated catalyst in the regenerator through the heat exchanger in the regenerator. The low-pressure steam is changed to superheated steam and the tail combustion in the regenerator is avoided.

[0046] In another aspect A reaction system for producing low-carbon olefins from catalytic cracking of hydrocarbons and crude oil, comprising a reactor, a catalyst regenerator and a heat exchanger, wherein the reactor is connected to the catalyst regenerator by a pipeline, the catalyst regenerator comprises a regeneration reactor and a regeneration settler, the regeneration settler is located above the regeneration reactor, the heat exchanger is located in the dilute phase section of the regeneration settler, low-pressure steam is introduced into the heat exchanger to exchange heat with the spent catalyst in the regeneration settler to become superheated steam, and the superheated steam is introduced into the bottom of the reactor.

[0047] In the reaction system for producing low-carbon olefins from catalytic cracking of hydrocarbons and crude oil, the coke generated in the reaction is not enough to maintain the heat balance of the reactor and the regenerator during the regeneration of the spent catalyst, and the regenerator needs to be supplemented with fuel. The supplemental fuel in the regenerator is easy to cause tail combustion, which damages the internal components (such as the cyclone). The low-pressure steam exchanges heat with the high-temperature flue gas in the dilute phase section of the regeneration settler, which greatly reduces the temperature of the dilute phase, the heat generated by the tail combustion is utilized, and the temperature of the dilute phase section cannot rise. Moreover, the temperature of the dilute phase section after heat exchange is greatly reduced from about 800℃ to about 650℃, which reduces the requirements for the material of the settler in the regenerator and reduces the construction cost.

[0048] In some embodiments, the heat exchanger is a shell-and-tube heat exchanger, which has heat exchange tubes and a shell. The heat exchange tubes are connected to a tube sheet and are fixed by the shell. The low-pressure steam can enter the heat exchanger through the shell side or the tube side, and preferably enters through the tube side.

[0049] The cyclone is arranged in the regeneration settler, and the cyclone comprises a cyclone body and a discharge leg below the cyclone body. The outlet of the discharge leg is located above the heat exchanger.

[0050] The heat exchanger is arranged below the cyclone. After the flue gas and a small amount of regenerated catalyst entering the heat exchanger exchange heat with the low-pressure steam, the temperature of the flue gas is greatly reduced, the temperature of the flue gas rising to the cyclone is low, the requirements for the material of the cyclone are reduced, and the tail combustion is prevented. Since the heat exchanger is arranged in the dilute phase section of the regeneration settler, most of the spent catalyst from the reactor settles in the dense phase section at the lower part of the regeneration settler, the temperature of the regenerated catalyst is maintained, and the normal reaction of the whole reaction system is not affected. On the other hand, the heat of most of the regenerated catalyst is not exchanged, which ensures the reaction temperature in the reactor.

[0051] In some embodiments, the heat exchanger is a shell-and-tube heat exchanger, the low-pressure steam goes through the tube side, and the flue gas goes through the shell side; the heat exchange tube of the heat exchanger comprises an inlet and an outlet, and the outlet of the heat exchange tube is connected to the pre-lifting tube arranged at the bottom of the reactor through a pipe.

[0052] Further, the outlet of the heat exchange tube is connected to the raw material feeder of the reactor through a pipe. The superheated steam discharged from the outlet of the heat exchanger atomizes the raw oil, and the atomized oil enters the reactor.

[0053] In the process of preparing low-carbon olefins by catalytic cracking of crude oil, the low-pressure steam is heat-exchanged into superheated steam in the heat exchanger, and then enters the pre-lifting tube of the reactor and the raw material feeder. Due to the high temperature of the steam, the catalyst / oil ratio can be reduced, the pressure drop in the reaction process is small, and thus the yield of ethylene and propylene is improved.

[0054] In some embodiments, the outlet of the regeneration reactor extends into the regeneration settler, and a gas-solid separation member with an opening downward is arranged above the regeneration reactor.

[0055] The gas-solid separation member has a cavity with an opening downward, and specifically, the cross section perpendicular to the opening is an arc, for example, a shape of an umbrella cap.

[0056] In the vertical direction, the opening of the gas-solid separation member can cover at least the outlet of the regeneration reactor.

[0057] In the reaction system for preparing low-carbon olefins by catalytic cracking of crude oil, the coking problem in the reaction settler and the coking problem of the heat exchanger seriously affect the long-period operation of the entire reaction system. The following scheme can ensure the long-period operation of the entire system.

[0058] In still another aspect, A reaction system for preparing low-carbon olefins by catalytic cracking of crude oil, comprising a reactor, a reaction settler, and a heat exchanger, wherein the reaction settler is provided with a flow guide cylinder with an upper opening and a lower opening, and the heat exchanger is arranged in the flow guide cylinder in the reaction settler.

[0059] In some embodiments, the heat exchanger is located above the outlet of the reactor, or preferably, directly above the outlet of the reactor.

[0060] Preferably, the outlet of the reactor extends into the flow guide cylinder and is located below the heat exchanger in the flow guide cylinder.

[0061] In this embodiment, the oil gas and catalyst flow into the flow guide cylinder from the lower opening of the flow guide cylinder, and flow out from the upper opening of the flow guide cylinder.

[0062] The diameter of the horizontal cross section of the draft tube can be adjusted to control the gas velocity of the oil gas and catalyst, so that 50-80% of the catalyst entering the draft tube settles due to the loss of upward pushing force and enters the stripping section of the settler, and the rest of the catalyst flows upward through the heat exchanger under the pushing force of the oil gas, converting water into high-pressure steam, and the oil gas and catalyst after temperature reduction and speed reduction leave the heat exchanger and the draft tube.

[0063] By adjusting the cross-sectional diameter of the draft tube, the superficial velocity in the draft tube is adjusted, and thus the proportion of the catalyst that settles before passing through the heat exchanger is controlled.

[0064] For example, the average superficial gas velocity of the reactor is 10 m / s, the superficial velocity of the fluid in the gap of the draft tube is controlled at 1-8 m / s, preferably 2-4 m / s, which can cause 50-80% of the catalyst to settle due to the loss of upward pushing force.

[0065] The "gap" mentioned above refers to the total gap on the horizontal cross section of the draft tube. Typically, the heat exchanger is composed of multiple heat exchange tubes, and there is a gap between adjacent heat exchange tubes and between the heat exchange tubes and the inner wall of the draft tube. The superficial velocity in the gap refers to the superficial velocity of the fluid passing through the gap of the draft tube.

[0066] Further, the flow rate of the oil gas and catalyst discharged from the opening of the draft tube decreases, the catalyst settles again, and the oil gas carries a small amount of catalyst into the cyclone, reducing the working load of the cyclone.

[0067] The superficial velocity of the fluid in the draft tube is lower than the outlet flow rate of the reactor, and most of the spent catalyst loses the upward pushing force and settles, and the rest of the spent catalyst flows upward through the heat exchanger in the draft tube under the pushing force of the oil gas. By using the scouring effect of the catalyst on the heat exchange tubes and the effect of the catalyst adsorbing condensed oil, the occurrence of internal coking in the heat exchanger can be effectively avoided.

[0068] In some embodiments, a primary separator for gas-solid separation is further provided in the reaction settler. The primary separator includes a separator body, an inlet, an outlet, and a discharge inclined pipe. The discharge inclined pipe is located below the separator body and connected to the lower end of the separator body. The outlet is connected to the upper opening of the draft tube, and the inlet is connected to the outlet of the reactor.

[0069] The inlet of the primary separator is located below the outlet. In this way, the oil gas flows upward and is discharged from the outlet of the primary separator.

[0070] The oil gas and spent catalyst discharged from the reactor first pass through the primary separator for gas-solid separation, and the separated oil gas carries part of the spent catalyst into the draft tube through the upper opening of the draft tube, and then passes through the heat exchanger for heat exchange to reduce the temperature.

[0071] If only high temperature oil gas or oil gas containing a small amount of catalyst into the heat exchanger for heat exchange, in the process of heat exchange, oil gas is easy to coking in the heat exchanger. The steam capacity is reduced, the pressure drop is increased, and even leads to the device unplanned shutdown. The application utilizes oil gas carrying spent catalyst through the heat exchanger, on the one hand, the use of catalyst adsorption oil gas cooling process of liquid phase, reduce even avoid the influence of heat transfer effect of attached to the heat transfer tube wall; On the other hand, the use of spent catalyst and the friction between the heat transfer tube wall, timely " wipe " the adsorption of oil, coking precursor and coke on the heat transfer tube wall. To ensure that the device can be long period operation.

[0072] In order to efficient, reasonable use of high temperature oil gas energy, reduce the energy consumption of regenerated catalyst, at the same time, reduce the coking in the heat exchanger and the settler and other components, control the primary separator outlet to exclude the high temperature oil gas containing the appropriate amount of catalyst.

[0073] In some embodiments, the total amount of catalyst contained in the high temperature oil gas separated by the primary separator is more than 10% of the total amount of catalyst carried by the oil gas at the outlet of the reactor, preferably between 15% and 25%. That is, in the primary separator, most of the catalyst (more than 60% of the total amount of catalyst carried by the oil gas at the outlet of the riser) can be naturally settled.

[0074] The proportion of the catalyst settled in the primary separator can be controlled by adjusting the pipe diameter above the inlet of the primary separator to control the linear velocity of the oil gas, which is required to be more than 5 m / s, preferably more than 8 m / s.

[0075] In some embodiments, the superficial gas velocity of the pipe above the inlet of the primary separator is more than 5 m / s, preferably more than 8 m / s. This ensures that the total amount of catalyst carried by the oil gas at the outlet of the primary separator is more than 10% of the total amount of catalyst carried by the oil gas at the outlet of the reactor, preferably between 15% and 25%.

[0076] In some embodiments, the opening on the draft tube is connected to the outlet of the primary separator through an elbow. For example, the elbow can be a smooth L-shaped pipe, and the two ends of the L-shaped elbow are connected to the outlet of the primary separator and the opening on the draft tube, respectively.

[0077] The oil gas and catalyst from the outlet of the reactor first enter the primary separator, and most of the catalyst flows downward into the settler by inertial separation, and a small amount of catalyst carried by the oil gas flows upward and enters the heat exchanger of the draft tube from top to bottom after turning through the L-shaped elbow. The amount of catalyst carried by the oil gas can be determined according to the linear velocity of the oil gas.

[0078] Regardless of the embodiment, the cyclone in the reaction settler is used for gas-solid separation of the oil gas and catalyst discharged from the draft tube.

[0079] The total amount of catalyst carried by the high temperature oil gas into the heat exchanger is preferably between 5-25% of the total amount of catalyst carried by the oil gas at the outlet of the reactor. Carrying a small amount of catalyst can avoid coking on the surface of the heat exchange tubes. If the oil gas and catalyst all pass through the heat exchanger, and the oil gas is cooled to the same temperature, the temperature of all the spent catalyst will be reduced, and more fuel will be needed to raise the temperature of the catalyst in the regenerator.

[0080] The defined superficial gas velocity at various locations in the primary separator in this application is based on the physical and mechanical properties of the catalysts commonly used in the catalytic cracking process for producing low carbon olefins. That is, most of the catalysts can be separated from the oil gas at the proposed superficial gas velocity range.

[0081] In some embodiments, the outlet end of the downcomer of the primary separator is located below the draft tube in the reaction settler in the vertical direction.

[0082] In some embodiments, a slide valve is provided on the downcomer of the primary separator, and the amount of catalyst carried by the oil gas into the draft tube can be adjusted by controlling the opening of the valve.

[0083] Increasing the opening of the slide valve and the amount of the conveying medium will cause the dilute-dense phase interface in the primary separator to move downward, and the proportion of catalyst carried by the oil gas into the heat exchanger in the draft tube will decrease, and vice versa. When the slide valve is closed, all the catalyst will enter the heat exchanger in the draft tube with the oil gas.

[0084] The reactor can have various configurations, such as a constant diameter riser, or a variable diameter riser, etc.

[0085] The outlet of the riser reactor is connected to the inlet of the primary separator. A pre-riser and a feedstock feeder are provided in the lower part of the riser reactor.

[0086] In a catalytic cracking reaction system of crude oil, the crude oil feedstock is sprayed into the riser reactor through the nozzle of the feedstock feeder under the action of atomizing steam. The atomized feedstock is contacted, mixed, and cracked with the high temperature catalyst flowing upward under the push of pre-riser steam. More than 80% of the cracking reaction mainly occurs in the instant of contact with the catalyst, and the pressure in this region has a great influence on the distribution of the reaction products. In order to reduce the pressure in this region, the superficial velocity of the fluid (catalyst and steam) before the catalyst contacts and reacts with the feedstock needs to be increased to more than 5 m / s, preferably more than 10 m / s, by using pre-riser steam. The reactor can be a constant diameter riser, or a variable diameter riser as shown in FIG. 2. Figure 2

[0087] ​After the catalyst contacts with the raw material, the volume expands sharply due to vaporization, temperature rise and cracking reaction. In order to avoid the sharp rise of pressure, a variable-diameter riser is preferably used so that the flow rate of the fluid (catalyst, steam, raw material and cracking product) remains at about 10 m / s after the feeding.

[0088] In some embodiments, the cross-sectional area of the separator body is a circular tank, and the diameter of the separator body is greater than the diameter of the outlet of the primary reactor.

[0089] By adjusting the diameter of the separator body and the diameter of the elbow pipe, the amount of catalyst carried by the oil gas from the outlet of the primary separator into the primary cyclone separator is controlled.

[0090] The settler tank comprises a diameter-expanding section and a stripping section, and the diameter-expanding section is located above the stripping section. The cross-sectional area of the settler tank is preferably circular, and the diameter of the diameter-expanding section is greater than the diameter of the stripping section in a plane perpendicular to the central axis of the settler tank.

[0091] The downcomer is circular in cross-section and has a constant diameter.

[0092] In some embodiments, a gas distributor is arranged in the separator body of the primary separator. Preferably, the gas distributor is arranged near the downcomer in the separator body.

[0093] The gas distributor can have a structure commonly used in the field of petroleum catalytic cracking or catalytic cracking, such as an annular pipe with gas holes uniformly arranged on the pipe wall.

[0094] The stripping medium enters the separator body through the gas distributor, and the catalyst after the primary separation is degassed by the stripping medium to remove the carried oil gas, and the degassed catalyst enters the downcomer. Thus, the oil gas carried by the catalyst discharged through the downcomer conveying pipe is greatly reduced.

[0095] The stripping medium comprises dry gas, nitrogen or water vapor. Preferably, water vapor is used.

[0096] In order to improve the stripping effect, a plurality of baffles are arranged in the separator body of the primary separator. The baffles are located above the gas distributor.

[0097] The present application sets a primary separator in the tank of the reaction settler, and the oil gas and catalyst at the outlet of the reactor enter the primary separator. After the primary separation, most of the oil gas carries a small amount of catalyst into the flow guide cylinder from the upper opening at the upper part of the primary separator. Most of the catalyst in the primary separator is stripped again during the falling process, and then enters the settler after removing the carried oil gas, thereby reducing the oil gas concentration in the settler and achieving the purpose of preventing the coking of the settler.

[0098] In some embodiments, the cyclone of the application comprises a primary cyclone and a secondary cyclone, and the oil gas and catalyst discharged from the draft tube enter the primary cyclone.

[0099] The primary cyclone comprises a main body and a downcomer, the downcomer comprising a downcomer degassing section and a downcomer conveying section, the upper end of the downcomer degassing section being connected to the lower end of the main body, and the lower end of the downcomer degassing section being connected to the upper end of the downcomer conveying section.

[0100] A gas distributor is arranged in the downcomer degassing section of the primary cyclone.

[0101] The stripping medium enters the degassing section through the gas distributor, and the catalyst separated by the main body of the primary cyclone is degassed by the stripping medium to remove the oil gas carried by the catalyst, and the degassed catalyst enters the downcomer conveying section. Thus, the oil gas carried by the catalyst discharged from the downcomer conveying pipe is greatly reduced.

[0102] The stripping medium comprises nitrogen or water vapor.

[0103] In order to further improve the gas-solid separation, the catalyst and oil gas enter the secondary cyclone after passing through the primary cyclone, and a straight pipe is used to connect the primary cyclone and the secondary cyclone.

[0104] The primary cyclone and the secondary cyclone each comprise a cyclone body and a downcomer leg arranged below the cyclone body.

[0105] The oil gas and catalyst cooled by the heat exchanger in the draft tube enter the primary cyclone. Since most of the catalyst has been separated in the primary cyclone and directly enters the settler, only a small amount of catalyst enters the primary cyclone, thus greatly reducing the load of the primary cyclone, which is conducive to reducing the concentration of catalyst in the oil gas entering the secondary cyclone and reducing the loss of catalyst during system fluctuations.

[0106] The reactor of the application can be a common riser, a double riser, or a riser reactor with an expanded diameter.

[0107] The main technical advantage of the application is that the heat exchanger in the regenerator or reactor utilizes heat exchange, fully utilizes high-temperature heat, and converts low-pressure steam into high-pressure steam. On the other hand, the heat exchanger in the reaction settler utilizes the scouring effect of an appropriate amount of catalyst to prevent coking of the heat exchanger and ensure long-term operation of the device. The flue gas flowing upward in the regeneration settler significantly decreases in temperature due to heat exchange, which avoids tail combustion and reduces the material requirements for internal components such as cyclones in the settler.

[0108] In addition, by using pre-lifted superheated steam (temperature exceeding 500℃) to accelerate the catalyst to over 10m / s, and then injecting the feedstock into the riser, the catalyst-to-oil ratio is reduced, effectively reducing the pressure at the moment of contact between the feedstock and the catalyst, thereby increasing the yield of ethylene and propylene.

[0109] The heat exchangers or primary separators installed in the regeneration settling tank or the reaction settling tank of this application are all fixed to the tank wall by existing connection methods.

[0110] The method for preventing coking in the crude oil catalytic cracking to low-carbon olefins reaction system of this application can be carried out in any of the following reaction devices.

[0111] The reaction system for preparing olefins from crude oil catalytic cracking according to the present invention is further illustrated below with reference to specific embodiments.

[0112] like Figure 1 As shown, the reaction system for the catalytic cracking of crude oil to produce low-carbon olefins includes a reactor and a regenerator. The reactor includes a riser reactor 1, a reaction settling tank 3, a flow guide tube 6, and a first heat exchanger 5. The flow guide tube 6 and the heat exchanger 5 are located inside the reaction settling tank 3, and the heat exchanger 5 is located inside the flow guide tube 6. The heat exchanger 5 is a shell-and-tube heat exchanger, and the two ends of the heat exchange tubes of the heat exchanger 5 pass through the side walls of the flow guide tube 6 and the reaction settling tank, allowing fluid to enter or exit the heat exchanger.

[0113] The guide tube 6 is a cylindrical tube with openings at both the top and bottom. The outlet of the riser reactor 1 extends into the reaction settling tank 3. The outlet of the riser reactor 1 extends from the lower opening of the guide tube 6 into the guide tube 6 and is located below the first heat exchanger 5.

[0114] In one embodiment, the riser reactor 1 is a pipe of constant diameter.

[0115] like Figure 1 As shown, the regenerator includes a regeneration reactor 2 and a regeneration settling tank 4, with the outlet of the regeneration reactor 2 extending into the regeneration settling tank 4. A second heat exchanger 7 is installed in the dilute phase section of the regeneration settling tank 4.

[0116] The regeneration reactor 2 includes a dense phase section and a dilute phase conveying section 19. The cross-section of the dilute phase conveying section 19 is smaller than that of the dense phase section. The dilute phase conveying section 19 is located within the regeneration settling tank 4. A gas-solid rapid separator 20 is installed above the outlet of the dilute phase conveying section 19. The gas-solid rapid separator is a downward-opening spherical cap structure used for rapid gas-solid separation of the flue gas discharged from the reactor and the regeneration catalyst. Most of the regeneration catalyst falls into the dense phase section of the regeneration settling tank 4. Figure 1 As shown, the dense phase section of the regenerator 4 refers to the inverted conical structure in the lower part. The space above the outlet of the dilute phase conveying section 19 is the dilute phase section of the regenerator 4.

[0117] At least one set of first cyclone 22 and second cyclone 23 are arranged in the dilute phase section of the regeneration settler 4, the first cyclone 22 is connected with the second cyclone 23, the first and second cyclones respectively include a cyclone body and a lower discharge leg below the cyclone body, the lower discharge legs of the first and second cyclones are located above the second heat exchanger 7.

[0118] Like the first heat exchanger, the second heat exchanger 7 is a tube heat exchanger, the two ends of the heat exchange tube respectively pass through the wall of the regeneration settler 4 for the inlet and outlet of fluid.

[0119] The catalyst external circulation pipe 16 is arranged outside the regeneration reactor 2 and the regeneration settler 4, one end of the catalyst external circulation pipe 16 is connected with the lower part of the regeneration reactor 3, and the other end of the catalyst external circulation pipe 16 is connected with the dense phase section of the regeneration settler 4. The catalyst in the dense phase section can return to the regeneration reactor 2 through the catalyst external circulation pipe 16 for combustion.

[0120] The main air distribution pipe 14 and the fuel gas distribution pipe 15 are arranged in the lower part of the regeneration reactor 2. The main air distribution pipe 14 and the fuel gas distribution pipe 15 respectively adopt the existing structure of the gas distribution pipe, which will not be described here.

[0121] The lower part of the reaction settler 3 is connected with the regeneration reactor 2 through the spent catalyst inclined pipe 8, and the spent catalyst is transported into the regeneration reactor 8 for regeneration. The lower part of the regeneration settler 4 is connected with the riser reactor 1 through the regenerated catalyst inclined pipe 9, and the regenerated catalyst is transported into the riser reactor 1 for catalytic cracking reaction.

[0122] Referring to the accompanying drawings Figure 1 The process for preparing low-carbon olefins by catalytic cracking of crude oil includes: superheated steam as a stripping medium is introduced into the pre-riser 11 and into the riser reactor 1, the raw oil and the superheated steam are sprayed into the riser reactor 1 through the raw material feeding pipe 10, and the regenerated catalyst enters the riser reactor 1 from the bottom of the riser reactor, in the riser reactor 1, the catalyst, the raw oil and the superheated steam are driven to flow upward to contact and perform catalytic cracking reaction.

[0123] The high-temperature oil and gas discharged from the outlet of riser reactor 1, along with the catalyst awaiting generation, enters the guide tube 6. Inside the guide tube 6, the gas velocity decreases, and most of the catalyst loses its upward thrust and settles. The high-temperature oil and gas, carrying another portion of the catalyst awaiting generation, moves upward through the first heat exchanger 5. The catalyst awaiting generation has a scouring effect on the outside of the first heat exchanger 5. Low-pressure steam enters the tube side of the first heat exchanger 5 and exchanges heat with the high-temperature oil and gas and the other portion of the catalyst awaiting generation. After heat exchange, the low-pressure steam becomes superheated steam. After the cooled oil and gas and the catalyst awaiting generation are discharged from the upper opening of the guide tube 6, the gas velocity rapidly drops below 0.5 m / s, and the catalyst settles naturally. The oil and gas, carrying a small amount of catalyst, enters the cyclone separator of the reaction settling tank 3. The oil and gas after separating the catalyst exits the reaction settling tank 3 through outlet 18 and enters the subsequent separation system through the oil and gas pipeline. The catalyst separated by the cyclone separator, along with the naturally settled catalyst, enters the stripping section. The catalyst stripped by stripping steam 21 is returned to regeneration reactor 2 via a waiting inclined tube for coke regeneration. (Separated)

[0124] The regenerated catalyst and flue gas from combustion in regeneration reactor 2 are discharged through the outlet of dilute phase conveying section 19. After being blocked by gas-solid rapid separator 20, most of the regenerated catalyst settles into the lower dense phase section of regeneration settling tank 4. A small portion of the regenerated catalyst and flue gas passes through second heat exchanger 7, where they exchange heat with low-pressure steam 12 entering the tube side of second heat exchanger 7. After heat exchange, the low-pressure steam becomes superheated steam 13, which flows through pipe into pre-lift pipe 11 and / or raw material feed pipe 10. The superheated steam enters the riser reactor 1, pushing the raw material and catalyst upward. The heat-exchanged flue gas and catalyst move upward and enter the first cyclone separator 22 and the second cyclone separator 23 for gas-solid separation. The separated flue gas is discharged from regeneration settling tank 4 through outlet 17.

[0125] The regenerated catalyst settled in the regenerator 4 is transported to the riser reactor 1 via the regenerated inclined tube 9 for catalytic cracking reaction.

[0126] Appendix Figure 1 The equal-diameter riser reactor 1 can also be an attached... Figure 2 The variable-diameter riser reactor shown includes at least an expansion section and a dilute phase transport section. The expansion section is located below the dilute phase transport section, and the cross-sectional area of ​​the expansion section is larger than that of the dilute phase transport section.

[0127] Another embodiment of the reactor is shown in the attached diagram. Figure 3 As shown.

[0128] The structure of the regenerator is similar to that of the attached... Figure 1 This will not be elaborated upon further here. (Appendix) Figure 1 The differences between the implementation methods shown are as follows.

[0129] The reactor includes a riser reactor 1, a reaction settling tank 3, a primary separator 24, a flow guide tube 6, and a first heat exchanger 5. The primary separator 24 is connected to the upper openings of the riser reactor 1 and the flow guide tube 6.

[0130] The primary separator 24 includes a separator body, a feed inclined pipe located below the separator body, an inlet, and an outlet. The outlet of the primary separator 24 is connected to the opening on the guide tube 6 via a smoothly transitioned L-shaped pipe. The oil and gas separated by the primary separator 24, carrying a portion of the catalyst, enter the first heat exchanger 5 of the guide tube 6. The inlet of the primary separator is connected to the outlet of the riser reactor 1. The catalyst and oil and gas in the riser reactor enter the primary separator through this inlet.

[0131] The separator body is a cylindrical tank. The feed inclined pipe is located below the separator body and connected to it.

[0132] In a preferred embodiment, a baffle shape is provided inside the separator body. Each baffle includes two plates, with the side of one plate connected to the side of the other plate at a certain angle, or one plate is bent to form a baffle with the opening facing downward.

[0133] like Figure 1 As shown in Figure 3, the discharge leg inside the primary cyclone separator is equipped with a stripping section.

[0134] Example 1

[0135] Catalytic cracking of paraffin-based crude oil was carried out using the cracking catalyst prepared in Example 8 of patent CN202010022024.2. The catalytic cracking reaction of paraffin-based crude oil was conducted in a riser reactor, as shown in the attached diagram. Figure 2 The variable diameter reactor shown.

[0136] Low-pressure steam at 200℃ is used as pre-lifting steam to raise the catalyst within the riser reactor to an apparent linear velocity of 10 m / s. The crude oil is then atomized by this 200℃ low-pressure steam and injected into the riser reactor along with the crude oil through a nozzle. After the reactor's diameter expands, the linear velocity of the injected crude oil remains around 10 m / s. The average residence time of the oil and gas from the crude oil nozzle to the riser reactor outlet is approximately 3 seconds.

[0137] Reaction conditions: The mass ratio of pre-lift steam + atomized steam to crude oil feed is 0.5:1, where the mass ratio of atomized steam to crude oil is 0.1, and the remainder is pre-lift steam. The catalyst regeneration temperature is 800℃ (regenerator catalyst bed temperature 800℃, settler dilute phase temperature 815℃), and the riser reactor outlet temperature is 700℃. The settler pressure is 0.16 MPa(a). The catalyst-to-oil ratio (catalyst circulation rate per unit time / crude oil feed rate per unit time) is 35.

[0138] Results: The single-pass methane yield was 15.5%, the ethylene + propylene yield was 33.4%, and the coke yield was 7.3%.

[0139] Example 2

[0140] Compared to Example 1, under otherwise unchanged conditions, 200°C low-pressure steam, used as pre-lift steam and atomized water vapor, is passed through (see attached...). Figure 1 and 3 (As shown) The regenerator's dilute phase heat exchanger exchanges heat with the flue gas, superheating it to 550°C, while the dilute phase temperature of the regenerator's settling tank drops to 620°C. Superheated steam is used as the pre-lifting and atomization medium. Results show that the agent-to-oil ratio decreased from 35 in Example 1 (using 200°C low-pressure steam as the pre-lifting and atomization medium) to 31, with corresponding reductions in methane and coke to 14.7% and 6.9%, respectively, and an increase in the ethylene + propylene yield to 34.1%.

[0141] Example 3

[0142] Using the same operating conditions as in Example 2, and in accordance with Appendix Figure 1 The proposed scheme cools the high-temperature oil and gas. The apparent linear velocity in the pipe gap above the riser outlet, calculated based on the diameter of the guide tube, is 3 m / s. With a constant influent flow rate, the generated steam temperature is 480℃. The temperature in the settling tank stripping section of the reactor is 640℃, and the temperature at the inlet of the cyclone separator is 570℃ with a density of 4.8 kg / m³. 3 The unit ran continuously for 7 days. Upon inspection, the high-temperature oil-gas heat exchanger showed no signs of wear or coking.

[0143] Example 4

[0144] Using the same operating conditions as in Example 2, and in accordance with Appendix Figure 3 The illustrated scheme cools the high-temperature oil and gas. After the upper diameter reduction of the primary separator, the linear velocity is 10 m / s, carrying approximately 20% of the total circulating catalyst. The apparent linear velocity before entering the heat exchange tubes is approximately 3 m / s. With the same influent flow rate as in Example 3, the temperature of the generated steam is 450°C, indicating that the amount of catalyst carried by the oil and gas into the heat exchanger is less. The temperature of the settling stripping section of the reactor is 655°C, indicating that more catalyst is separated by the primary separator than naturally settled in Example 3. The temperature at the inlet of the cyclone separator is 540°C, and the density is 3.2 kg / m³. 3 This indicates that in Example 3, some oil and gas entered the settler from the lower part of the guide tube, while a relatively large amount of catalyst was "thrown" up from the upper part of the high-temperature oil and gas heat exchanger. The device also ran continuously for 7 days, and upon inspection, no wear or coking was found in the high-temperature oil and gas heat exchanger.

[0145] In addition, other conditions are as in Example 2, according to AppendixFigure 1 The scheme shown in the above patent is different in that, without the flow guide, the outer wall of the heat exchanger is coked in one or two days, and the temperature of the spent catalyst is greatly reduced.

Claims

1. A process for the catalytic cracking of crude oil to produce lower olefins comprising: The catalyst and the atomized crude oil are contacted in the reactor to perform catalytic cracking reaction, wherein the catalyst is lifted by superheated steam above 500 DEG C and moves upward in the reactor, and the outlet temperature of the reactor is controlled at 600-750 DEG C; The reactor is connected with the catalyst regenerator through a pipeline, the catalyst regenerator comprises a regeneration reactor and a regeneration settler, the regeneration settler is located above the regeneration reactor, and the second heat exchanger is located in the dilute phase section of the regeneration settler. The low-pressure steam exchanges heat with the regenerated catalyst in the second heat exchanger and the regeneration settler to become superheated steam.

2. The reaction process according to claim 1, characterized in that, The catalyst is lifted by superheated steam above 600 DEG C and moves upward in the reactor.

3. The reaction process of claim 1, wherein, The pressure in the reaction settler located above the reactor is controlled at 20-100 kPa.

4. The reaction process of claim 1, wherein, The pressure in the reaction settler located above the reactor is controlled at 40-70 kPa.

5. The reaction process of claim 1 wherein, The reaction settler of the reactor is provided with a flow guide cylinder with upper and lower openings, and the first heat exchanger is arranged in the flow guide cylinder in the reaction settler, The first heat exchanger is located above the outlet of the reactor.

6. The reaction method according to claim 5, wherein The outlet of the reactor extends into the flow guide cylinder and is located below the first heat exchanger in the flow guide cylinder.

7. The reaction method according to claim 5, wherein The reaction settler is further provided with a primary separator for gas-solid separation, the primary separator comprises a separator body, an inlet, an outlet and a discharge inclined pipe, the discharge inclined pipe is located below the separator body and connected with the lower end of the separator body, the outlet is connected with the upper opening of the flow guide cylinder, and the inlet is connected with the outlet of the reactor. The inlet of the primary separator is located below the outlet.

8. The reaction method according to claim 7, characterized by, The total amount of catalyst contained in the high-temperature oil gas separated by the primary separator accounts for more than 10% of the total amount of catalyst carried by the oil gas at the outlet of the reactor.

9. The reaction method according to claim 7, wherein The total amount of catalyst contained in the high-temperature oil gas separated by the primary separator accounts for 15-25% of the total amount of catalyst carried by the oil gas at the outlet of the reactor.

10. The reaction method according to claim 7, wherein The superficial gas velocity of the pipeline above the inlet of the primary separator is more than 5 m / s.

11. The reaction method according to claim 7, wherein The superficial gas velocity of the pipeline above the inlet of the primary separator is more than 8 m / s.

12. A reaction system for use in a process for the catalytic cracking of a crude oil to produce lower olefins according to any one of claims 1 to 11, comprising a reactor, a catalyst regenerator and a second heat exchanger, wherein, The reactor is connected with the catalyst regenerator through a pipeline, the catalyst regenerator comprises a regeneration reactor and a regeneration settler, the regeneration settler is located above the regeneration reactor, and the second heat exchanger is located in the dilute phase section of the regeneration settler; The low-pressure steam exchanges heat with the regenerated catalyst in the second heat exchanger and the regeneration settler to become superheated steam, and the superheated steam is introduced into the bottom of the reactor. The cyclone separator is arranged in the regeneration settler, and the cyclone separator comprises a cyclone separator body and a discharge leg below the cyclone separator body, and the outlet of the discharge leg is located above the second heat exchanger.

13. The reaction system of claim 12, wherein, The second heat exchanger is a tubular heat exchanger, which has heat exchange tubes and a shell, the low-pressure steam enters the tube side of the second heat exchanger, and the flue gas passes through the shell side.

14. The reaction system of claim 13, wherein, The second heat exchanger is a tubular heat exchanger, the low-pressure steam passes through the tube side, the flue gas passes through the shell side, and the heat exchange tubes of the second heat exchanger comprise an inlet and an outlet, and the outlet of the heat exchange tubes is connected with a pre-lifting pipe arranged at the bottom of the reactor through a pipeline.

15. The reaction system of claim 14, wherein, The outlet of the heat exchange tubes is connected with a raw material feeder of the reactor through a pipeline.

16. The reaction system of claim 12, wherein, The outlet of the heat exchange tubes is connected with a raw material feeder of the reactor through a pipeline. The gas-solid separation part is a downwardly open cavity with an arc-shaped cross section.

17. The reaction system of claim 16, wherein, The gas-solid separation part is a downwardly open spherical cap, and the opening of the gas-solid separation part covers at least the outlet of the regenerative reactor in the vertical direction.

18. The reaction system of claim 12, wherein, The reactor, the reaction settler and the first heat exchanger are included, the reaction settler is provided with an upper and lower opening draft tube, and the first heat exchanger is arranged in the draft tube of the reaction settler. The first heat exchanger is located above the outlet of the reactor.

19. The reaction system of claim 18, wherein, The outlet of the reactor extends into the draft tube and is below the first heat exchanger in the draft tube.

20. The reaction system of claim 18, wherein, The reaction settler is further provided with a primary separator for gas-solid separation, the primary separator includes a separator body, an inlet, an outlet and a discharge inclined pipe, the discharge inclined pipe is located below the separator body and connected with the lower end of the separator body, the outlet is connected with the upper opening of the draft tube, and the inlet is connected with the outlet of the reactor. The inlet of the primary separator is below the outlet.

21. The reaction system of claim 20, wherein, The upper opening of the draft tube and the outlet of the primary separator are connected through an elbow pipe.

22. The reaction system of claim 21, wherein, The elbow pipe is a smooth L-shaped pipe, and the two ends of the L-shaped elbow pipe are connected with the outlet of the primary separator and the upper opening of the draft tube respectively.

23. The reaction system of claim 20, wherein, In the vertical direction, the outlet end of the discharge inclined pipe of the primary separator is below the draft tube in the reaction settler. A slide valve is arranged on the discharge inclined pipe of the primary separator, and the amount of catalyst carried in the oil gas entering the draft tube is adjusted by adjusting the opening of the valve.

24. The reaction system of claim 20, wherein, The cross section of the separator body is a circular tank, and the diameter of the separator body is greater than the diameter of the outlet of the primary reactor.

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