Catalytic cracking reaction system and catalyst replacement system method

Abstract

The invention provides a catalytic cracking reaction system and a catalyst replacement system method, and solves the technical problems that a large catalytic device is large in catalyst storage amount and long in replacement period, and the flexible adjustment range of a catalytic cracking reaction is further improved. According to the method provided by the invention, rapid and flexible switching among different product schemes such as maximum production of chemical materials, consideration of the chemical materials and oil products, maximum production of the oil products and the like is realized, and the method is a novel catalytic cracking technology for flexibly adjusting the product structure.

Description

Technical Field

[0001] This invention belongs to the field of petrochemicals, specifically relating to a catalytic cracking reaction system and a catalyst replacement system method. Background Technology

[0002] In recent years, global refining capacity has continued to grow, but the industry's development has been affected by factors such as the global economic downturn and geopolitical conflicts, resulting in a slowdown in overall demand growth. Product demand and production profits have shown an unprecedented trend of "oil refining being weak and chemical refining being weak." Currently, the refining industry is facing a situation of accelerating the "reduction of oil refining and increase of chemical and specialty products," with continuous optimization of product structure adjustments. How refineries can flexibly adjust their product structure to closely follow the market and respond quickly is key to the profitability of refining enterprises. Developing catalytic cracking technology that can adapt to the diversity of processing raw materials and flexibly adjust product structure can achieve flexible switching between different product models such as oil products and chemical products, and has good prospects for industrial application.

[0003] Some well-known international oil companies have proposed the concept of a gas-solid ultra-short contact downflow bed reactor, believing that shortening the residence time of oil and gas helps improve the selectivity of intermediate products such as propylene, and have begun to develop new downflow bed reactor catalytic cracking technologies. Patent CN1113659 discloses a flexible folded design using a riser-coupled downflow bed, capable of producing low-carbon olefins and clean gasoline. Patent US6656346B2 discloses a high-severity catalytic cracking process HS-FCC (High-Severity Fluid Catalytic Cracking), which uses a downflow bed reactor to conduct catalytic cracking reactions under high severity, achieving a propylene yield of over 20%, while maintaining lower yields of dry gas and coke. This technology has two operating modes: producing more light olefins and producing more high-octane gasoline.

[0004] Domestic catalytic cracking processes mainly employ riser reactors. Patent CN1237477A discloses a variable-diameter fluidized bed (MIP) technology, developed by the China Petroleum & Chemical Research Institute Co., Ltd., and is the most widely used catalytic cracking technology in China, primarily for producing high-octane, low-olefin gasoline. This technology is based on a dual-reaction-zone conversion concept, employing a fast-bed reactor in the second reaction zone to promote hydrogen transfer and achieve controllable reductions in gasoline olefin content. To flexibly change the product structure, relying on the MIP technology platform, the China Petroleum & Chemical Research Institute Co., Ltd. developed the CGP technology, which reduces gasoline olefin content while significantly increasing propylene yield. Patent CN112536001A discloses a catalytic cracking RTC technology that utilizes a fast-bed reactor to increase propylene production, achieving propylene yields of over 18%. Flexible adjustment of the product structure requires rapidly matching and adapting catalysts. Patent CN1267706A discloses a catalyst replacement method, but it does not consider the drastic disturbance to the thermal balance caused by large-scale catalyst replacement, making it difficult to achieve stable reaction operation.

[0005] The current chemical and refined oil markets are changing rapidly. As one of the main units for producing chemicals and gasoline / diesel, catalytic cracking needs to quickly switch its product structure to seize market opportunities, but the following problems exist:

[0006] (1) Long replacement cycle: With the increase in large-scale catalytic devices and the large amount of catalyst stored in the system, there is a problem that conventional replacement techniques for formulation catalysts have a long cycle. It takes at least 1 to 3 months for the replacement period to show a good product structure adjustment effect.

[0007] (2) Limited scope for product structure adjustment: Existing catalytic cracking units face technical challenges in adjusting their product structure, which limit the yield of target products and affect gasoline quality. Significantly increasing the content of selective molecular sieves in the catalyst results in limited increase in propylene yield and a decrease in heavy oil conversion rate. In the process of adjusting the product structure of existing catalytic cracking units, significantly reducing the reaction severity to increase gasoline production may result in gasoline quality that fails to meet the requirements of the blending tank.

[0008] Therefore, it is essential to develop new catalytic cracking technologies that allow for rapid and flexible adjustment of product structures. Summary of the Invention

[0009] The purpose of this invention is to solve the technical problems of large catalyst reserves, long replacement cycles, and further improve the flexibility of catalytic cracking reaction adjustment in large-scale catalytic devices.

[0010] A first aspect of the present invention provides a catalytic cracking reaction system, comprising:

[0011] The reactor is equipped with a reaction oil and gas inlet, a reactor fluidized medium inlet, a catalyst inlet, an oil and gas separation device, a product oil and gas outlet, and a catalyst outlet. The oil and gas separation device includes a cyclone separator and a stripper.

[0012] A regenerator is used to regenerate the catalyst to be generated. It is provided with a catalyst to be generated inlet, a regeneration medium inlet, a flue gas outlet, a regeneration catalyst heat exchange outlet, a regeneration catalyst heat exchange return inlet, a regeneration catalyst outlet, and a replacement catalyst inlet. The catalyst to be generated inlet is connected to the catalyst to be generated outlet of the reactor, and the catalyst outlet is connected to the catalyst inlet of the reactor through a regeneration catalyst pipeline.

[0013] An external heat exchanger is used to exchange heat on the regenerated catalyst. It is provided with a regenerated catalyst heat exchange inlet, a regenerated catalyst heat exchange return outlet, a regenerated catalyst unloading outlet, a heat exchange coil, and an external heat exchanger fluidizing medium inlet. The regenerated catalyst heat exchange inlet is connected to the regenerated catalyst heat exchange outlet of the regenerator, and the regenerated catalyst heat exchange return outlet is connected to the regenerated catalyst heat exchange return inlet of the regenerator. The heat exchange coil is housed inside the shell of the external heat exchanger and forms a heat exchange medium inlet and a heat exchange medium outlet on the surface of the shell of the external heat exchanger. The external heat exchanger fluidizing medium inlet, the regenerated catalyst unloading outlet, and the regenerated catalyst heat exchange inlet are located at the lower part of the external heat exchanger and are all located below the heat exchange coil.

[0014] The displacement catalyst heat exchanger, located outside the external heat exchanger, is used to exchange heat on the displacement catalyst. It is equipped with a heating medium inlet pipeline, a displacement catalyst inlet pipeline, a displacement catalyst outlet pipeline, and a heating medium outlet pipeline. The heating medium inlet pipeline is equipped with a heating medium inlet valve and is connected to the heat exchange medium outlet of the heat exchange coil, so that the heat exchange medium from the heat exchange coil enters the displacement catalyst heat exchanger through the heating medium inlet pipeline as the heating medium for heating the displacement catalyst. The displacement catalyst outlet pipeline is connected to the displacement catalyst inlet of the regenerator, so that the displacement catalyst enters the regenerator.

[0015] According to the reaction system of the first aspect, the reactor is one or more of a cascade reactor, a riser reactor, and a descending bed reactor, preferably a cascade reactor;

[0016] More preferably, the cascade reactor is a multi-stage variable-diameter fluidized bed reactor, consisting of a first-stage rapid bed reaction zone, a second-stage riser reaction zone, a third-stage rapid bed reaction zone, and a fourth-stage conveyor bed, from bottom to top.

[0017] According to the reaction system of the first aspect, the pipe diameter D1 of the primary rapid bed reaction zone, the pipe diameter D2 of the secondary riser reaction zone, the pipe diameter D3 of the tertiary rapid bed reaction zone, and the pipe diameter D4 of the quaternary conveying bed satisfy the following relationship:

[0018] D1 > D3 > D2 = D4.

[0019] According to the reaction system of the first aspect, the length L1 of the primary rapid bed reaction zone, the length L2 of the secondary riser reaction zone, the length L3 of the tertiary rapid bed reaction zone, and the length L4 of the quaternary conveyor bed satisfy the following relationship:

[0020] L4 > L1 > L2 > L3.

[0021] According to the reaction system of the first aspect, the height of the heat exchange medium inlet of the heat exchange pipe from the bottom of the external heat exchanger is 50%-90% of the total height of the external heat exchanger; and / or

[0022] The volume of the heat exchange coil accounts for 10%-50% of the total volume of the external heat exchanger.

[0023] A second aspect of the present invention provides a catalyst replacement method for a catalytic cracking reaction system, the method using the catalytic cracking reaction system of the first aspect.

[0024] According to the method of the second aspect, the method includes:

[0025] Fluidized gas flows into the reactor from the bottom. Catalytic cracking catalyst from the regenerator enters the reactor. Feed oil and gas and catalyst react in the reactor. The resulting oil and gas products and the spent catalyst are separated by an oil and gas separator. The spent catalyst after separation is stripped and then enters the regenerator for coking and regeneration. The hot regenerated catalyst enters the external heat exchanger and exchanges heat with the heat exchange medium in the heat exchange coil. After heat exchange, the cold regenerated catalyst returns to the regenerator and enters the reactor for a circulating reaction.

[0026] During catalyst replacement, after the regenerated catalyst enters the external heat exchanger for heat exchange, 10%-80% of the regenerated catalyst is discharged through the regenerated catalyst discharge outlet, and the remaining regenerated catalyst after heat exchange is returned to the regenerator. A portion of the superheated steam generated by the heat exchange medium in the heat exchange coil of the external heat exchanger enters the catalyst replacement heat exchanger through the superheated steam inlet pipeline to fluidize and heat the catalyst replacement in the catalyst replacement heat exchanger. The heated catalyst replacement enters the regenerator and mixes with the regenerated catalyst for a cyclic reaction.

[0027] According to the second method, the feedstock oil and gas and the catalyst are back-mixed and contacted in the first-stage fast bed reaction zone of the cascade reactor, then enter the second-stage transport bed reaction zone for rapid cracking, then enter the third-stage fast bed reaction zone for olefin reduction, and finally undergo oil and gas separation in the transport bed.

[0028] According to the method of the second aspect, the linear velocity of the primary rapid bed reaction zone is 1-3 m / s;

[0029] The linear velocity in the reaction zone of the secondary riser is 5-15 m / s;

[0030] The linear velocity of the three-stage rapid bed reaction zone is 1-3 m / s; and / or

[0031] The linear speed of the four-stage conveyor bed is 10-15 m / s.

[0032] According to the method of the second aspect, the reaction conditions of the reactor are:

[0033] The reaction temperature is 500-800℃;

[0034] The reaction pressure is 0.1-2.0 MPa;

[0035] The agent-to-oil ratio is 5-20;

[0036] The dwell time is 1.0-15.0 seconds.

[0037] According to the method of the second aspect, the feedstock oil and gas is selected from one or more of heavy distillate oil, gasoline, and diesel;

[0038] Preferably, the raw material oil and gas enter the reactor after preheating, and the preheating temperature is preferably 100-300℃.

[0039] According to the method of the second aspect, the regeneration temperature in the regenerator is 550-850℃; and / or

[0040] The regeneration medium is one or more of air and oxygen.

[0041] According to the method of the second aspect, the replacement catalyst is heated to 300-500°C and then enters the regenerator.

[0042] According to the method of the second aspect, the heat exchange medium is water at 0-100°C.

[0043] Compared with the prior art, the present invention has the following technical effects:

[0044] (1) It has strong adaptability to raw materials. It is not only suitable for light catalytic cracking raw materials such as hydrogenated LCO, but also for deep catalytic cracking of inferior heavy raw materials with high density and low hydrogen content.

[0045] (2) Compared with conventional riser reactors, the present invention adopts a stepped reactor, which on the one hand enhances the initial gas-solid contact efficiency and improves the conversion depth, and on the other hand can adapt to the flexible adjustment of different operating modes to ensure product yield.

[0046] (3) The present invention can realize rapid replacement of catalyst system in large-scale catalytic cracking unit. Compared with conventional replacement methods, the replacement rate can be increased by 2-10 times. Attached Figure Description

[0047] Figure 1 A schematic diagram of the process flow according to an embodiment of the present invention is shown.

[0048] Explanation of reference numerals in the attached figures:

[0049] 1. Reactor fluidizing medium; 2. Gas distribution plate; 3. Regeneration slide valve; 4. Oil inlet nozzle; 501. Primary rapid bed reaction zone; 502. Secondary riser reaction zone; 503. Tertiary rapid bed reaction zone; 504. Conveyor bed; 6. Cyclone separator; 7. Stripper; 8. Product oil and gas discharge pipeline; 9. Stripping medium; 10. Waiting slide valve; 11. Regenerator; 12. Regenerator cyclone separator; 13. Flue gas outlet pipeline; 4. Regeneration medium; 15. Hot regenerator replacement slide valve; 16. Cold regenerator replacement slide valve; 17. External heat exchanger; 18. Heat exchange coil; 19. Heat exchange medium inlet; 20. Heat exchange medium outlet; 21. Fluidizing medium of external heat exchanger; 22. Catalyst unloading pipeline; 23. Superheated steam inlet valve; 24. Replacement catalyst inlet pipeline; 25. Replacement catalyst outlet pipeline; 26. Steam exhaust pipeline; 27. Replacement catalyst heat exchanger. Detailed Implementation

[0050] The present application will now be described in further detail with reference to the accompanying drawings and embodiments. Through these descriptions, the features and advantages of the present application will become clearer and more apparent.

[0051] The term “exemplary” as used herein means “serving as an example, embodiment, or illustration.” Any embodiment illustrated herein as “exemplary” is not necessarily to be construed as superior to or better than other embodiments. Although various aspects of embodiments are shown in the accompanying drawings, the drawings are not necessarily drawn to scale unless specifically indicated otherwise.

[0052] Furthermore, the technical features involved in the different embodiments of this application described below can be combined with each other as long as they do not conflict with each other.

[0053] Any specific numerical values ​​disclosed herein (including the endpoints of numerical ranges) are not limited to their exact values, but should be understood to also include values ​​close to the exact value, such as all possible values ​​within ±5% of the exact value. Furthermore, with respect to the disclosed numerical ranges, one or more new numerical ranges can be obtained by arbitrarily combining the endpoint values ​​of the range, the endpoint values ​​with specific point values ​​within the range, and the specific point values ​​themselves; these new numerical ranges should also be considered as specifically disclosed herein.

[0054] In this application, the terms "upstream" and "downstream" refer to the direction of reaction material flow. For example, when the reaction material flows from bottom to top, "upstream" refers to the position at the bottom, while "downstream" refers to the position at the top.

[0055] Unless otherwise stated, the terms used herein have the same meaning as commonly understood by those skilled in the art, and if a term is defined herein and its definition differs from the common understanding in the art, the definition herein shall prevail.

[0056] This invention provides a catalytic cracking reaction system, comprising:

[0057] The reactor is equipped with a reaction oil and gas inlet, a reactor fluidized medium inlet, a catalyst inlet, an oil and gas separation device, a product oil and gas outlet, and a catalyst outlet. The oil and gas separation device includes a cyclone separator and a stripper.

[0058] A regenerator is used to regenerate the catalyst to be generated. It is provided with a catalyst to be generated inlet, a regeneration medium inlet, a flue gas outlet, a regeneration catalyst heat exchange outlet, a regeneration catalyst heat exchange return inlet, a regeneration catalyst outlet, and a replacement catalyst inlet. The catalyst to be generated inlet is connected to the catalyst to be generated outlet of the reactor, and the catalyst outlet is connected to the catalyst inlet of the reactor through a regeneration catalyst pipeline.

[0059] An external heat exchanger is used to exchange heat on the regenerated catalyst. It is provided with a regenerated catalyst heat exchange inlet, a regenerated catalyst heat exchange return outlet, a regenerated catalyst unloading outlet, a heat exchange coil, and an external heat exchanger fluidizing medium inlet. The regenerated catalyst heat exchange inlet is connected to the regenerated catalyst heat exchange outlet of the regenerator, and the regenerated catalyst heat exchange return outlet is connected to the regenerated catalyst heat exchange return inlet of the regenerator. The heat exchange coil forms a heat exchange medium inlet and a heat exchange medium outlet on the shell surface of the external heat exchanger. The external heat exchanger fluidizing medium inlet, the regenerated catalyst unloading outlet, and the regenerated catalyst heat exchange inlet are located in the lower part of the external heat exchanger and are all located below the heat exchange coil.

[0060] The displacement catalyst heat exchanger, located outside the external heat exchanger, is used to exchange heat on the displacement catalyst. It is equipped with a heating medium inlet pipeline, a displacement catalyst inlet pipeline, a displacement catalyst outlet pipeline, and a heating medium outlet pipeline. The heating medium inlet pipeline is equipped with a heating medium inlet valve and is connected to the heat exchange medium outlet of the heat exchange coil, so that the heat exchange medium from the heat exchange coil enters the displacement catalyst heat exchanger through the heating medium inlet pipeline as the heating medium for heating the displacement catalyst. The displacement catalyst outlet pipeline is connected to the displacement catalyst inlet of the regenerator, so that the displacement catalyst enters the regenerator.

[0061] In this invention, the fluidized medium inlet, regenerated catalyst unloading outlet, and regenerated catalyst heat exchange inlet of the external heat exchanger are located at the lower part of the external heat exchanger, and are all located below the heat exchange coil, thereby ensuring that the regenerated catalyst entering the catalyst heat exchange replacement device can fully exchange heat with the heat exchange coil. Simultaneously, the high fluidized bed density in this area facilitates rapid unloading.

[0062] In one embodiment, the reactor is one or more of a cascade reactor, a riser reactor, and a descending bed reactor, preferably a cascade reactor;

[0063] More preferably, the cascade reactor is a multi-stage variable-diameter fluidized bed reactor, consisting of a first-stage rapid bed reaction zone, a second-stage riser reaction zone, a third-stage rapid bed reaction zone, and a fourth-stage conveyor bed, from bottom to top.

[0064] In a preferred embodiment, the pipe diameter D1 of the primary rapid bed reaction zone, the pipe diameter D2 of the secondary riser reaction zone, the pipe diameter D3 of the tertiary rapid bed reaction zone, and the pipe diameter D4 of the quaternary conveying bed satisfy the following relationship:

[0065] D1 > D3 > D2 = D4, and the pipe diameter is determined by the throughput to ensure that the linear velocity in each reaction zone is in the corresponding fluidization state.

[0066] The reactor of this invention is preferably a multi-stage variable-diameter fluidized bed reactor, wherein different pipe diameters are beneficial for achieving step-by-step optimization and control of different reaction zones. The first-stage rapid bed reaction zone has the largest pipe diameter, which improves gas-solid contact efficiency and enhances macromolecular cracking reaction through high bed density and strong backmixing. The second-stage riser reaction zone has a higher gas velocity and shorter residence time, which is conducive to the rapid completion of intermediate reaction processes. The third-stage rapid bed reaction zone has a higher bed density, which is conducive to reducing hydrogen transfer reaction and enhancing olefin reduction process. The fourth-stage conveyor bed avoids side reactions and suppresses dry gas generation through rapid conveying.

[0067] In a preferred embodiment, the lengths L1 of the primary rapid bed reaction zone, L2 of the secondary riser reaction zone, L3 of the tertiary rapid bed reaction zone, and L4 of the quaternary conveying bed satisfy the following relationship: L4 > L1 > L2 > L3, and the total length is determined by the reaction time.

[0068] The lengths of each section of the reactor in this invention satisfy the above relationship. The lengths of the first three reaction zones decrease accordingly, which conforms to the cracking process of macromolecules into small molecules, avoids excessive side reactions and over-cracking, and achieves precise control of the reaction. The conveying bed is the longest, which on the one hand needs to ensure that the gas velocity is accelerated to the gas velocity required by the cyclone separator, and on the other hand needs to ensure sufficient settling space.

[0069] In one embodiment, the height of the heat exchange medium inlet of the heat exchange pipe from the bottom of the external heat exchanger is 50%-90% of the total height of the external heat exchanger; and / or

[0070] The volume of the heat exchange coil accounts for 10%-50% of the total volume of the external heat exchanger.

[0071] The height of the heat exchange medium inlet of the heat exchange pipe of the present invention from the bottom of the external heat exchanger (e.g.) Figure 1 (as shown in h) occupies a portion of the total height of the external heat exchanger (e.g., Figure 1 The heat exchange efficiency of the catalyst above the height (as shown in H) is 50%-90%. When the height is less than 50%, the heat exchange efficiency of the catalyst above this height decreases. When the height is greater than 90%, the heat exchange efficiency of the catalyst in the top dilute phase region is low, and the utilization efficiency is not high.

[0072] The volume of the heat exchange coil in this invention accounts for 10%-50% of the total volume of the external heat exchanger. When the volume is greater than 50%, it will affect the flow of the catalyst in the external heat exchanger. When the volume is less than 10%, the heat exchange between the catalyst and the heat exchange medium is insufficient, and the ideal heat exchange effect cannot be achieved.

[0073] The heat extraction area of ​​the heat extraction pipe of this invention satisfies the following formula:

[0074]

[0075] in:

[0076] A is the heat exchanger area in meters (m²). 2 ;

[0077] Q is the amount of heat transferred, expressed in kW.

[0078] U is the heat transfer coefficient, W / m³ 2· ℃;

[0079] ΔT is the temperature difference of the fluid, in °C.

[0080] The catalytic cracking reactor of the present invention uses an external heat exchanger and a catalyst replacement heat exchanger to exchange and replace the catalyst outside the reaction system. It is preferably combined with a multi-stage fluidized bed device to reduce the thermal balance fluctuations in the regenerator, realize rapid catalyst replacement, and improve the efficiency of flexible adjustment of product structure.

[0081] The present invention also provides a catalyst replacement method for a catalytic cracking reaction system, the method using the aforementioned catalytic cracking reaction system.

[0082] In one embodiment, the method includes:

[0083] Fluidized gas flows into the reactor from the bottom. Catalytic cracking catalyst from the regenerator enters the reactor. Feed oil and gas and catalyst react in the reactor. The resulting oil and gas products and the spent catalyst are separated by an oil and gas separator. The spent catalyst after separation is stripped and then enters the regenerator for coking and regeneration. The hot regenerated catalyst enters the external heat exchanger and exchanges heat with the heat exchange medium in the heat exchange coil. After heat exchange, the cold regenerated catalyst returns to the regenerator and enters the reactor for a circulating reaction.

[0084] During catalyst replacement, after the regenerated catalyst enters the external heat exchanger for heat exchange, 10%-80% of the regenerated catalyst is discharged through the regenerated catalyst discharge outlet, and the remaining regenerated catalyst after heat exchange is returned to the regenerator. A portion of the superheated steam generated by the heat exchange medium in the heat exchange coil of the external heat exchanger enters the catalyst replacement heat exchanger through the superheated steam inlet pipeline to fluidize and heat the catalyst replacement in the catalyst replacement heat exchanger. The heated catalyst replacement enters the regenerator and mixes with the regenerated catalyst for a cyclic reaction.

[0085] This invention provides a catalytic cracking reactor and catalyst replacement system method: fluidizing gas flows into the reactor from the bottom of a stepped reactor, and catalytic cracking catalyst from the regenerator enters the reactor from the upper part of the distribution plate. The fluidizing medium mixes with the downstream catalyst after passing through the distribution plate. The feedstock, after preheating, enters the bottom of the stepped reactor through nozzles to mix and contact with the catalyst. After entering the first-stage fast bed reaction zone, the feedstock and catalyst undergo a strong backmixing contact reaction. Due to the high catalyst density in the bed, this enhances gas-solid contact efficiency and improves reaction conversion. After entering the second-stage riser reaction zone, the reactant gas and catalyst undergo a rapid cracking reaction, taking advantage of the short residence time in the riser reactor. After entering the third-stage fast bed reaction zone, the olefin reduction process is enhanced. In gasoline mode, this reaction zone promotes propylene yield; in propylene mode, it promotes hydrogen transfer and reduces gasoline olefins. Finally, the reactant gas and catalyst undergo rapid separation at the end of the conveying bed. The separated spent catalyst is stripped and then sent to the regenerator for coking regeneration. To achieve rapid switching between different modes, a catalyst that is compatible with the mode needs to be matched. By sending part of the original regenerated catalyst into an external heat exchanger for heat exchange, and using part of the generated superheated steam to heat the new catalyst, the heat of the hot catalyst can be recovered, the temperature of the new catalyst can be increased, the thermal balance fluctuations in the regenerator can be reduced, the catalyst can be rapidly replaced, and the efficiency of flexible adjustment of product structure can be improved.

[0086] The specific process of the catalytic cracking method of the present invention may include:

[0087] (1) The catalyst from the regenerator enters the reactor from the bottom of the cascade reactor.

[0088] (2) After the fluidizing medium passes through the distribution plate, it mixes with the catalyst from the regenerator. The catalyst flows upward under the action of the fluidizing medium.

[0089] (3) After the feed oil is preheated, it enters the stepped reactor through the nozzle and mixes with the catalyst. Under the action of the fluidizing medium, the feed oil and the catalyst flow upward into the stepped reactor to carry out catalytic cracking reaction.

[0090] (4) The reaction product oil and gas and the catalyst are separated at the top of the riser by a cyclone separator. The separated product oil and gas enter the fractionation unit, and the catalyst separated by the cyclone separator enters the stripper for stripping.

[0091] (5) After the catalyst is stripped, it enters the regenerator through the regeneration slide valve to burn coke. The flue gas generated by burning coke is separated by the cyclone separator and discharged. The regenerated catalyst enters the stepped reactor through the waiting slide valve for the next cycle.

[0092] (6) When switching operating modes, the original regenerated catalyst enters the external heat exchanger for heat exchange, part of the regenerated catalyst returns to the regenerator, and 10%-80% of the original regenerated catalyst is unloaded. Part of the superheated steam generated by heat exchange is discharged and part of it enters the catalyst heat exchanger.

[0093] (7) The new catalyst is added to the catalyst heat exchanger and heated by hot steam fluidization. After the new catalyst is heated to 300-500℃, it enters the regenerator.

[0094] In one embodiment, the feedstock oil and gas and the catalyst undergo backmixing and contact reaction in the first-stage fast bed reaction zone of a cascade reactor, then enter the second-stage conveying bed reaction zone for rapid cracking reaction, then enter the third-stage fast bed reaction zone for olefin reduction, and finally undergo oil and gas separation in the conveying bed.

[0095] In one embodiment, the linear velocity of the primary rapid bed reaction zone is 1-3 m / s;

[0096] The linear velocity in the reaction zone of the secondary riser is 5-15 m / s;

[0097] The linear velocity of the three-stage rapid bed reaction zone is 1-3 m / s; and / or

[0098] The linear speed of the four-stage conveyor bed is 10-15 m / s.

[0099] In one embodiment, the reaction conditions of the reactor are:

[0100] The reaction temperature is 500-800℃;

[0101] The reaction pressure is 0.1-2.0 MPa;

[0102] The agent-to-oil ratio is 5-20;

[0103] The dwell time is 1.0-15.0 seconds.

[0104] In one embodiment, the feedstock oil and gas is selected from one or more of heavy distillate oil, gasoline, and diesel.

[0105] Preferably, the raw material oil and gas enter the reactor after preheating, and the preheating temperature is preferably 100-300℃.

[0106] In one embodiment, the regeneration temperature in the regenerator is 550-850°C; and / or

[0107] The regeneration medium is one or more of air and oxygen.

[0108] In one embodiment, the replacement catalyst is heated to 300-500°C and then introduced into the regenerator.

[0109] In one embodiment, the heat exchange medium is water at 0-100°C.

[0110] like Figure 1As shown, the catalyst enters the riser reactor 5 through the regeneration slide valve 3. After being fluidized by the gas distribution plate 2 in the fluidizing medium 1, it enters the bottom of the cascade reactor. The cascade reactor consists of a first-stage fast bed reaction zone 501, a second-stage riser reaction zone 502, a third-stage fast bed reaction zone 503, and a conveying bed 504 from bottom to top. The fluidizing medium drives the catalyst to flow upward. After preheating, the feed oil enters the bottom of the cascade reactor through the oil inlet nozzle 4 and mixes and reacts with the catalyst. The feed oil gas and catalyst flow upward into the reaction section of the cascade reactor for catalytic cracking. After strong backmixing and contact reaction in the first-stage fast bed reaction zone 501 of the cascade reactor, it enters the second-stage riser reaction zone 502 for rapid cracking reaction, and then enters the third-stage fast bed reaction zone 503 for enhanced olefin reduction process. Finally, it undergoes rapid separation at the end of the conveying bed 504. The reaction product oil and gas and the spent catalyst are separated at the top of the reactor by a cyclone separator 6. The separated product oil and gas are discharged from the fluidized bed reactor 5 through the product oil and gas discharge pipeline 8. The product oil and gas discharge pipeline 8 can be connected to further oil and gas treatment devices, such as entering a fractionation unit. The spent catalyst separated by the cyclone separator 6 enters the stripper 7 and is stripped by the stripping medium 9. The stripped spent catalyst enters the regenerator 11 through the spent catalyst slide valve 10, where it undergoes coking regeneration under the action of the regeneration medium 14. It is then separated and settled in the regenerator cyclone separator 12. The flue gas generated by regeneration is separated by the regenerator cyclone separator 12 and discharged from the flue gas outlet pipeline 13. The regenerated thermal catalyst enters the external heat exchanger 17 through the thermal regenerator displacement valve 15. Under the action of the fluidizing medium 21 in the external heat exchanger, the thermal catalyst flows upwards and exchanges heat with the heat exchange medium in the heat exchange coil 18. The heat exchange medium in the heat exchange coil enters through the heat exchange medium inlet 19, undergoes a phase change after heat exchange, and generates superheated steam, which is then drawn out from the heat exchange medium outlet 20. In normal operation, the cooled regenerator after heat exchange returns to the regenerator through the cold regenerator displacement valve 16 and settles to the bottom of the regenerator 11. It then enters the reactor through the regeneration valve 3 for the next cycle.

[0111] When the operating mode is switched to catalyst replacement mode, part of the thermally regenerated catalyst enters the external heat exchanger 17 through the thermal regenerator replacement slide valve 15. The heat exchange medium enters the heat exchange coil 18 from the heat exchange medium inlet 19 to exchange heat with the thermal regenerator. The heat exchange medium generates superheated steam through the heat exchange medium outlet 20 and is discharged. Part of the superheated steam enters the catalyst replacement heat exchanger 27 through the superheated steam inlet valve 23 as the fluidizing medium for the catalyst replacement and heats the catalyst. New catalyst enters the catalyst replacement heat exchanger 27 from the catalyst replacement inlet pipeline 24, and after being heated by the hot steam, it is fluidized and enters the regenerator 11 through the catalyst replacement outlet pipeline 25. The remaining superheated steam is discharged from the steam outlet pipeline 26. The regenerated catalyst can be discharged through the catalyst unloading pipeline 23 to avoid disturbing the thermal balance of the regenerator.

[0112] The reaction conditions in the stepped reactor are as follows: reaction temperature 500-800℃, reaction pressure 0.1-2.0MPa, agent-to-oil ratio 5-20, and residence time 1.0-15.0 seconds.

[0113] The regeneration conditions inside the regenerator are: regeneration temperature of 550-850℃ and regeneration medium of air.

[0114] The properties of the hydrogenated catalytic converters used in the examples are shown in Table 1.

[0115] The catalysts used in the examples are commercial NTO and CGP catalysts.

[0116] The following Examples 1 and 2 both adopt the following... Figure 1 The apparatus shown has the following characteristics: the diameter D1 of the primary rapid bed reaction zone is 0.03m, the length L1 is 0.8m, and the linear velocity is 1.2m / s; the diameter D2 of the secondary riser reaction zone is 0.012m, the length L2 is 0.7m, and the linear velocity is 7.5m / s; the diameter D3 of the tertiary rapid bed reaction zone is 0.025m, the length L3 is 0.6m, and the linear velocity is 1.7m / s; and the diameter D4 of the quaternary conveyor bed is 0.012m, the length L4 is 1.0m, and the linear velocity is 7.5m / s.

[0117] The height h of the heat exchange medium inlet of the heat exchange pipeline from the bottom of the external heat exchanger accounts for 70% of the total height H of the external heat exchanger;

[0118] The volume of the heat exchange coil accounts for 40% of the total volume of the external heat exchanger.

[0119] Example 1

[0120] This embodiment follows Figure 1 The equipment and process were tested to achieve a multi-product chemical feedstock operation mode. The reaction was carried out in a small-scale cascade reactor, using the hydrotreated diesel oil in Table 1 as feedstock. The test was conducted on the cascade reactor, using NTO catalyst.

[0121] This embodiment uses a regeneration device with a volume of 1.2m³. 3 The catalyst loading is 10 kg.

[0122] The process conditions for reaction and regeneration are as follows: the preheating temperature of the hydrogenation catalytic converter is 200℃, the reaction outlet temperature is 600℃, the catalyst-to-oil ratio is 8, the reaction pressure is 0.2MPa, the residence time is 1.5s, the regenerator outlet temperature is 700℃, and the regenerator medium is air.

[0123] The NTO catalyst enters the cascade reactor via regeneration valve 3. Fluidizing medium 1, after being fluidized by gas distribution plate 2, enters the bottom of the cascade reactor, carrying the catalyst upwards. The feedstock oil, preheated to 200°C, enters the bottom of the cascade reactor through inlet nozzle 4 and mixes with the catalyst. The feedstock oil and catalyst flow upwards in parallel into each reaction section of the cascade reactor for catalytic cracking. The product oil and catalyst are separated at the top of the reactor by cyclone separator 6. The separated product oil and gas enter the fractionation unit through product oil and gas discharge pipeline 8. The catalyst separated by cyclone separator 6 enters stripper 7 and is stripped by stripping medium 9. The stripped catalyst enters regenerator 11 through regeneration valve 10 for coke burn regeneration. It is then separated and settled in regenerator cyclone separator 12. The generated flue gas is separated by regenerator cyclone separator 12 and discharged from flue gas outlet pipeline 13. The regenerated hot catalyst enters the external heat exchanger 17 through the hot regenerator displacement valve 15. Under the action of the fluidizing medium 21 in the external heat exchanger, the hot catalyst flows upwards and exchanges heat with the heat exchange medium (100°C water) in the heat exchange coil 18. The heat exchange medium in the heat exchange coil enters through the heat exchange medium inlet 19, undergoes a phase change after heat exchange, and generates superheated steam, which is then drawn out from the heat exchange medium outlet 20. The cooled regenerator returns to the regenerator through the cold regenerator displacement valve 16 and settles to the bottom of the regenerator 11. It then enters the reactor through the regeneration valve 3 for the next cycle. Operating conditions and product distribution are listed in Table 2.

[0124] Example 2

[0125] This embodiment follows Figure 1 The equipment and process were tested to achieve a high-gasoline production operation mode. The reaction was carried out in a small-scale cascade reactor, using the hydrotreated diesel fuel listed in Table 1 as feedstock. The test was conducted on the cascade reactor using CGP catalyst.

[0126] This embodiment uses a regeneration device with a volume of 1.2m³. 3 The catalyst loading is 10 kg.

[0127] The NTO catalyst was rapidly replaced by CGP catalyst, with a replacement rate of 100%.

[0128] The process conditions for reaction and regeneration are as follows: the preheating temperature of the hydrogenation catalytic converter is 200℃, the reaction outlet temperature is 520℃, the catalyst-to-oil ratio is 6, the reaction pressure is 0.2MPa, the residence time is 1.5s, the regenerator outlet temperature is 700℃, and the regenerator medium is air.

[0129] Under these conditions, after stable operation, when the CGP catalyst replacement rate reached 100%, the replacement time was measured to be 10 hours.

[0130] Specific replacement methods include:

[0131] The catalyst enters the cascade reactor via regeneration valve 3. Fluidizing medium 1, after being fluidized by gas distribution plate 2, enters the bottom of the cascade reactor, carrying the catalyst upwards. The feedstock oil, preheated to 200°C, enters the bottom of the cascade reactor through inlet nozzle 4 and mixes with the catalyst. The feedstock oil and catalyst flow upwards in parallel into each reaction section of the cascade reactor for catalytic cracking. The product oil and catalyst are separated at the top of the reactor by reactor cyclone separator 6. The separated product oil and gas enter the fractionation unit through product oil and gas discharge pipeline 8. The catalyst separated by reactor cyclone separator 6 enters stripper 7 and is stripped by stripping medium 9. The stripped catalyst enters regenerator 11 through regeneration valve 10 for coke burn regeneration. It is then separated and settled in regenerator cyclone separator 12. The generated flue gas is separated by regenerator cyclone separator 12 and discharged from flue gas outlet pipeline 13. The regenerated hot catalyst enters the external heat exchanger 17 via the hot regenerator displacement valve 15. The heat exchange medium (100°C water) enters the heat exchange coil 18 through the heat exchange medium inlet 19 to exchange heat with the hot regenerator. The heat exchange medium generates superheated steam, which is discharged through the heat exchange medium outlet 20. Part of the superheated steam enters the displacement catalyst heat exchanger 27 through the superheated steam inlet valve 23 as the fluidizing medium for the displacement catalyst and heats it. New displacement catalyst CGP enters the displacement catalyst heat exchanger 27 through the displacement catalyst inlet line 24. After being heated by the hot steam, its fluidization temperature reaches 200°C, and it enters the regenerator 11 through the displacement catalyst outlet line 25. The remaining superheated steam is discharged through the steam outlet line 26. The regenerated catalyst is discharged through the catalyst unloading line 23 to avoid disturbing the thermal balance of the regenerator. The displacement catalyst entering the regenerator 11 is mixed with the regenerated catalyst and then enters the reactor through the regeneration valve 3 for the next cycle. Operating conditions and product distribution are listed in Table 2.

[0132] As shown in Table 2, in Example 2, the dry gas yield was 2.56 wt%, the liquefied petroleum gas yield was 13.52 wt%, the gasoline yield was 48.93 wt%, the diesel yield was 32.62 wt%, the oil slurry yield was 1.22 wt%, the coke yield was 1.15 wt%, the triene yield was 7.88 wt%, the BTX yield was 11.25 wt%, and the triene + BTX + gasoline yield was 68.06 wt%.

[0133] Comparative Example 1

[0134] This comparative example uses the existing conventional riser catalytic cracking process, and the reaction is carried out in a small riser reactor. NTO balancer is used, and the feed oil is the same as in Example 1. The operating conditions and product distribution are listed in Table 2.

[0135] The comparative example uses a regeneration device with a volume of 1.2m³. 3 The catalyst loading is 10 kg.

[0136] The process conditions for reaction and regeneration are as follows: preheating temperature of the hydrocatalytic converter is 200℃, reaction outlet temperature is 600℃, catalyst-to-oil ratio is 8, reaction pressure is 0.2MPa, residence time is 1.5s, regenerator outlet temperature is 700℃, and the regeneration medium is air. The operating conditions and product distribution are listed in Table 2.

[0137] Comparative Example 2

[0138] This comparative example uses the existing conventional riser catalytic cracking process, and the reaction is carried out in a small riser reactor. CGP balancer is used, and the feed oil is the same as in Example 1. The operating conditions and product distribution are listed in Table 2.

[0139] The comparative example uses a device with a volume of 1.2m³. 3 The catalyst loading is 10 kg.

[0140] The reaction and regeneration process conditions are as follows: hydrogenation catalytic converter preheating temperature is 200℃, reaction outlet temperature is 520℃, catalyst-to-oil ratio is 6, reaction pressure is 0.2MPa, residence time is 1.5s, regenerator outlet temperature is 700℃, and the regenerator medium is air. Catalyst replacement is performed using conventional methods. Part of the NTO catalyst is unloaded from the regenerator. After unloading, once the temperature stabilizes, a portion of the CGP catalyst is added back to the regenerator. The addition and unloading processes should not be too rapid to ensure thermal balance during the reaction and stable operation of the subsequent fractionation process, avoiding drastic fluctuations in the unit. Catalyst replacement is carried out gradually through small-scale unloading and addition.

[0141] Under these conditions, after stable operation, the replacement time was measured to be 60 hours when the CGP catalyst replacement rate reached 100%. Operating conditions and product distribution are listed in Table 2.

[0142] Table 1

[0143]

[0144] Table 2

[0145]

[0146]

[0147] *Trienes refer to ethylene, propylene, and butadiene. The triene yield refers to the yield of trienes obtained after further separation of the product.

[0148] **BTX refers to light aromatic hydrocarbons, namely a mixture of benzene, toluene, and xylene. The BTX yield refers to the yield of light aromatic hydrocarbons (BTX) obtained after further separation of the product.

[0149] As shown in Table 2, under the multi-product chemical mode, Example 1 produces more chemical products compared to Comparative Example 1, and the yield of triene + BTX + gasoline is higher. Under the multi-product gasoline mode, Example 2 has a higher gasoline yield compared to Comparative Example 2, and the yield of triene + BTX + gasoline is also higher, thus increasing both gasoline and chemical product production. Furthermore, the catalyst replacement rate of Example 2 is 6 times that of Comparative Example 2. Therefore, the rapid catalyst replacement device can achieve rapid catalyst replacement, enhance gas-solid contact efficiency through a stepped reactor, fully utilize the advantages of high tolerance, increase product selectivity, and achieve the goal of rapid and flexible adjustment of product structure.

[0150] The present application has been described above with reference to preferred embodiments; however, these embodiments are merely exemplary and illustrative. Various substitutions and modifications can be made to the present application based on these embodiments, all of which fall within the protection scope of the present application.

Claims

1. A catalytic cracking reaction system, comprising: The reactor is equipped with a reaction oil and gas inlet, a reactor fluidized medium inlet, a catalyst inlet, an oil and gas separation device, a product oil and gas outlet, and a catalyst outlet. The oil and gas separation device includes a cyclone separator and a stripper. A regenerator is used to regenerate the catalyst to be generated. It is provided with a catalyst to be generated inlet, a regeneration medium inlet, a flue gas outlet, a regeneration catalyst heat exchange outlet, a regeneration catalyst heat exchange return inlet, a regeneration catalyst outlet, and a replacement catalyst inlet. The catalyst to be generated inlet is connected to the catalyst to be generated outlet of the reactor, and the catalyst outlet is connected to the catalyst inlet of the reactor through a regeneration catalyst pipeline. An external heat exchanger is used to exchange heat on the regenerated catalyst. It is provided with a regenerated catalyst heat exchange inlet, a regenerated catalyst heat exchange return outlet, a regenerated catalyst unloading outlet, a heat exchange coil, and an external heat exchanger fluidizing medium inlet. The regenerated catalyst heat exchange inlet is connected to the regenerated catalyst heat exchange outlet of the regenerator, and the regenerated catalyst heat exchange return outlet is connected to the regenerated catalyst heat exchange return inlet of the regenerator. The heat exchange coil is housed inside the shell of the external heat exchanger and forms a heat exchange medium inlet and a heat exchange medium outlet on the surface of the shell of the external heat exchanger. The external heat exchanger fluidizing medium inlet, the regenerated catalyst unloading outlet, and the regenerated catalyst heat exchange inlet are located at the lower part of the external heat exchanger and are all located below the heat exchange coil. The displacement catalyst heat exchanger, located outside the external heat exchanger, is used to exchange heat on the displacement catalyst. It is equipped with a heating medium inlet pipeline, a displacement catalyst inlet pipeline, a displacement catalyst outlet pipeline, and a heating medium outlet pipeline. The heating medium inlet pipeline is equipped with a heating medium inlet valve and is connected to the heat exchange medium outlet of the heat exchange coil, so that the heat exchange medium from the heat exchange coil enters the displacement catalyst heat exchanger through the heating medium inlet pipeline as the heating medium for heating the displacement catalyst. The displacement catalyst outlet pipeline is connected to the displacement catalyst inlet of the regenerator, so that the displacement catalyst enters the regenerator.

2. The reaction system according to claim 1, characterized in that, The reactor is one or more of a cascade reactor, a riser reactor, and a descending bed reactor, preferably a cascade reactor; More preferably, the cascade reactor is a multi-stage variable-diameter fluidized bed reactor, consisting of a first-stage rapid bed reaction zone, a second-stage riser reaction zone, a third-stage rapid bed reaction zone, and a fourth-stage conveyor bed, from bottom to top.

3. The reaction system according to claim 2, characterized in that, The pipe diameters D1 of the primary rapid bed reaction zone, D2 of the secondary riser reaction zone, D3 of the tertiary rapid bed reaction zone, and D4 of the quaternary conveyor bed satisfy the following relationship: D1 > D3 > D2 = D4.

4. The reaction system according to claim 2, characterized in that, The lengths L1 of the primary rapid bed reaction zone, L2 of the secondary riser reaction zone, L3 of the tertiary rapid bed reaction zone, and L4 of the quaternary conveyor bed satisfy the following relationship: L4 > L1 > L2 > L3.

5. The reaction system according to claim 1, characterized in that, The height of the heat exchange medium inlet of the heat exchange pipe from the bottom of the external heat exchanger is 50%-90% of the total height of the external heat exchanger; and / or The volume of the heat exchange coil accounts for 10%-50% of the total volume of the external heat exchanger.

6. A method for catalyst replacement in a catalytic cracking reaction system, characterized in that, The method uses the catalytic cracking reaction system according to any one of claims 1 to 5.

7. The method according to claim 6, characterized in that, The method includes: Fluidized gas flows into the reactor from the bottom. Catalytic cracking catalyst from the regenerator enters the reactor. Feed oil and gas and catalyst react in the reactor. The resulting oil and gas products and the spent catalyst are separated by an oil and gas separator. The spent catalyst after separation is stripped and then enters the regenerator for coking and regeneration. The hot regenerated catalyst enters the external heat exchanger and exchanges heat with the heat exchange medium in the heat exchange coil. After heat exchange, the cold regenerated catalyst returns to the regenerator and enters the reactor for a circulating reaction. During catalyst replacement, after the regenerated catalyst enters the external heat exchanger for heat exchange, 10%-80% of the regenerated catalyst is discharged through the regenerated catalyst discharge outlet, and the remaining regenerated catalyst after heat exchange is returned to the regenerator. A portion of the superheated steam generated by the heat exchange medium in the heat exchange coil of the external heat exchanger enters the catalyst replacement heat exchanger through the superheated steam inlet pipeline to fluidize and heat the catalyst replacement in the catalyst replacement heat exchanger. The heated catalyst replacement enters the regenerator and mixes with the regenerated catalyst for a cyclic reaction.

8. The method according to claim 7, characterized in that, Feedstock oil and gas and catalyst undergo backmixing and contact reaction in the first-stage fast bed reaction zone of the cascade reactor, then enter the second-stage transport bed reaction zone for rapid cracking reaction, then enter the third-stage fast bed reaction zone for olefin reduction, and finally undergo oil and gas separation in the transport bed.

9. The method according to claim 8, characterized in that, The linear velocity in the primary rapid bed reaction zone is 1-3 m / s; The linear velocity in the reaction zone of the secondary riser is 5-15 m / s; The linear velocity of the three-stage rapid bed reaction zone is 1-3 m / s; and / or The linear speed of the four-stage conveyor bed is 10-15 m / s.

10. The method according to claim 7, characterized in that, The reaction conditions of the reactor are as follows: The reaction temperature is 500-800℃; The reaction pressure is 0.1-2.0 MPa; The agent-to-oil ratio is 5-20; The dwell time is 1.0-15.0 seconds.

11. The method according to claim 7, characterized in that, The feedstock oil and gas are selected from one or more of heavy distillate oil, gasoline, and diesel; Preferably, the raw material oil and gas enter the reactor after preheating, and the preheating temperature is preferably 100-300℃.

12. The method according to claim 7, characterized in that, The regeneration temperature in the regenerator is 550-850℃; and / or The regeneration medium is one or more of air and oxygen.

13. The method according to claim 7, characterized in that, The replacement catalyst is heated to 300-500°C and then enters the regenerator.

14. The method according to claim 7, characterized in that, The heat exchange medium is water at 0-100℃.

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