Catalyst cyclic replacement heat exchange method of catalytic cracking reaction system and reaction system

Abstract

The invention provides a catalyst cyclic replacement heat exchange method of a catalytic cracking reaction system and the reaction system. According to the method provided by the invention, the technical problems of large catalyst storage amount, long replacement period and further improvement of the flexible adjustment range of the catalytic cracking reaction of a large-scale catalytic device are solved, and flexible and rapid switching among different product schemes of maximum production of chemical materials, consideration of the chemical materials and oil products, maximum production of the oil products and the like is realized; the method is a novel catalytic cracking technology with flexibly adjustable product structure.

Description

Technical Field

[0001] This invention belongs to the field of petrochemicals, specifically relating to a catalyst circulation replacement heat exchange method and reaction system for a catalytic cracking reaction system. 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) Small range of heat load adjustment: In conventional upward external heat exchangers, the catalyst enters the external heat exchanger from a single inlet pipe. The catalyst flows upward in the form of a dense phase rapid bed, resulting in an uneven structure with a thin upper and dense lower phase. The heat load in the dense phase region is large, while the heat load in the dilute phase region is small, which limits the range of heat load adjustment and the heat extraction rate.

[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 method for catalyst circulation and heat exchange in a catalytic cracking reaction system, comprising:

[0011] The feedstock oil reacts with the catalytic cracking catalyst in the reactor under the action of fluidizing gas through back-mixing. The resulting oil and gas products are separated from the spent catalyst at the end of the reactor. The separated oil and gas products are led out of the reactor. The spent catalyst is stripped and then enters the regenerator for regeneration. The regenerated catalyst enters the external heat exchanger for heat exchange. The external heat exchanger is equipped with one or more sets of parallel heat exchange pipelines.

[0012] In a conventional cyclic reaction, the regenerated catalyst after heat exchange is returned to the regenerator and then enters the reactor for cyclic reaction through the regeneration inclined tube set at the bottom of the regenerator;

[0013] During catalyst replacement, 10%-90% of the cooled regenerated catalyst after heat exchange is discharged through the unloading pipe of the external heat exchanger. After unloading, the replacement catalyst is added to the heat exchanger for mixing and heat exchange. The mixed catalyst is then returned to the regenerator and then enters the reactor through the regeneration inclined tube at the bottom of the regenerator for recycling reaction.

[0014] According to the method of the first aspect, the reactor is a fluidized bed reactor, preferably one or more of a fast bed reactor, a riser reactor, and a descending bed reactor.

[0015] According to the method of the first aspect, the reaction conditions of the reactor are as follows:

[0016] The reaction temperature is 500-800℃;

[0017] The reaction pressure is 0.1-2.0 MPa;

[0018] The agent-to-oil ratio is 5-40;

[0019] The dwell time is 1.0-15.0 seconds.

[0020] According to the method of the first aspect, the external heat exchanger is an upward-type external heat exchanger, and the number of heat exchange pipelines is 1-10 sets.

[0021] Preferably, in the external heat exchanger, the fluidizing gas velocity is 0.5-2 m / s; and / or

[0022] Preferably, in the external heat exchanger, the catalyst density is 50-400 kg / m³. 3 .

[0023] According to the method of the first aspect, the heat extraction medium in the heat extraction pipeline is selected from one or more of the following: water, raw oil, and refrigerant;

[0024] Preferably, the heat extraction medium is hot water, and the temperature of the hot water is preferably 20-100℃;

[0025] More preferably, the hot water inlet velocity of the heat extraction pipeline is 1-10 m / s.

[0026] According to the method of the first aspect, the regeneration temperature of the regenerator is 550-850°C; and / or

[0027] The regenerated catalyst enters the reactor from the bottom through a regeneration inclined tube.

[0028] According to the method of the first aspect, the feedstock oil is selected from one or more of heavy distillate oil, gasoline, and diesel oil;

[0029] Preferably, the raw oil is preheated before entering the reactor, and the preheating temperature is preferably 100-300℃.

[0030] According to the method in the first aspect, the oil and gas obtained from the stripping of the catalyst and the separated oil and gas products are jointly introduced into the fractionation system.

[0031] A second aspect of the present invention provides a catalytic cracking reaction system, comprising:

[0032] The reactor is equipped with a feed oil inlet, a reactor fluidized medium inlet, a catalyst inlet, an oil-gas separation device, a product oil-gas outlet, and a catalyst outlet. The oil-gas separation device includes a settling tank, a cyclone separator, and a stripper.

[0033] A regenerator is used to regenerate the catalyst to be generated. It is equipped with a catalyst to be generated inlet, a regeneration medium inlet, a cyclone separator, a flue gas outlet, a regeneration catalyst heat exchange outlet, a regeneration catalyst heat exchange return inlet, and a regeneration catalyst outlet. The catalyst to be generated inlet is connected to the catalyst to be generated outlet of the reactor through a catalyst to be generated inclined tube, and the catalyst to be generated outlet is connected to the catalyst inlet of the reactor through a regeneration inclined tube.

[0034] An external heat exchanger is used for heat exchange and catalyst replacement of the regenerated catalyst. It is provided with a regenerated catalyst heat exchange inlet, a regenerated catalyst heat exchange return outlet, a regenerated catalyst discharge outlet, one or more sets of parallel heat exchange pipes, a heat exchanger fluidizing medium inlet, and a replacement catalyst inlet. The regenerated catalyst heat exchange inlet is connected to the regenerated catalyst heat exchange outlet of the regenerator through a regenerated catalyst heat exchange pipeline. The regenerated catalyst heat exchange return outlet is connected to the regenerated catalyst heat exchange return inlet of the regenerator through a regenerated catalyst heat exchange return pipeline. The heat exchange pipes are housed inside the external heat exchanger, and a heat exchange medium inlet and a heat exchange medium outlet are formed on the shell surface of the external heat exchanger. Both the heat exchange medium inlet and the heat exchange medium outlet are located above the regenerated catalyst heat exchange inlet.

[0035] The displacement catalyst inlet is located at the lower part of the external heat exchanger, and below the heat exchange medium inlet and outlet, for supplying the displacement catalyst to the external heat exchanger;

[0036] The fluidizing medium inlet of the heat exchanger is located at the bottom of the external heat exchanger and is used to introduce the fluidizing medium into the heat exchanger.

[0037] According to the reaction system of the second aspect, the external heat exchanger has two or more sets of parallel heat exchange pipes, and the vertical heights of the heat exchange pipes are different.

[0038] Preferably, the heat extraction pipe is in the shape of a serpentine coil.

[0039] According to the reaction system of the second aspect, the height of the heat exchange medium inlet of the heat exchange pipe from the bottom of the external heat exchanger is 10%-60% of the total height of the external heat exchanger; and / or

[0040] The volume of the serpentine coil accounts for 10%-50% of the total volume of the external heat exchanger;

[0041] Preferably, the heat exchange medium inlet and outlet of each heat exchange pipe are located at the same horizontal level.

[0042] Compared with the prior art, the present invention has the following technical effects:

[0043] (1) It has strong adaptability to raw materials. It is not only suitable for high-density, low-hydrogen-content inferior heavy raw materials, but also for deep catalytic cracking processes of light catalytic cracking raw materials such as hydrogenated LCO.

[0044] (2) Conventional upward-flow external heat exchangers have the disadvantage of uneven distribution of catalyst with a thin upper layer and a concentrated lower layer. In addition, hot water enters the heat exchange tube from a single inlet pipe, resulting in low heat exchange efficiency and slow heat extraction rate. It cannot be flexibly adjusted. The present invention adopts a parallel feeding method of hot water from inlet pipes at different heights, which can flexibly control the hot water feed rate, as well as the flow rate and temperature of each hot water pipeline, thereby flexibly adjusting the heat exchange efficiency and ensuring the stability of the temperature of the regeneration system.

[0045] (3) Compared with conventional regenerator addition methods, the present invention adopts an external heat exchanger addition method, which avoids the impact of rapid addition on the temperature fluctuation of the regenerator. On the other hand, the mixed contact heat exchange of cold new catalyst and hot regenerated catalyst is beneficial to preheating the new catalyst, thereby reducing the impact on the regenerator.

[0046] (4) 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 1A 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. Fluidizing medium; 2. Gas distribution plate; 3. Regeneration slide valve; 4. Oil inlet nozzle; 5. Fluidized bed reaction section; 6. Stripper internal components; 7. Reactor cyclone separator; 8. Settler; 9. Product oil and gas discharge pipeline; 10. Stripping medium; 11. Waiting slide valve; 12. Regenerator; 13. Regenerator cyclone separator; 14. Flue gas outlet pipeline; 15. Regeneration medium; 16. New catalyst addition pipeline; 17. Hot regenerator heat extraction slide valve; 18. External heat exchanger catalyst fluidizing medium; 19. External heat exchanger; 20. Hot water inlet; 21. Steam and water outlet; 22. Regenerated catalyst return pipeline slide valve; 23. Regenerated catalyst discharge pipeline slide valve. 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 method for catalyst circulation and heat exchange in a catalytic cracking reaction system, comprising:

[0057] The feedstock oil reacts with the catalytic cracking catalyst in the reactor under the action of fluidizing gas through back-mixing. The resulting oil and gas products are separated from the spent catalyst at the end of the reactor. The separated oil and gas products are led out of the reactor. The spent catalyst is stripped and then enters the regenerator for regeneration. The regenerated catalyst enters the external heat exchanger for heat exchange. The external heat exchanger is equipped with one or more sets of parallel heat exchange pipelines.

[0058] In a conventional cyclic reaction, the regenerated catalyst after heat exchange is returned to the regenerator and then enters the reactor for cyclic reaction through the regeneration inclined tube set at the bottom of the regenerator;

[0059] During catalyst replacement, 10%-90% of the cooled regenerated catalyst after heat exchange is discharged through the unloading pipe of the external heat exchanger. After unloading, the replacement catalyst is added to the heat exchanger for mixing and heat exchange. The mixed catalyst is then returned to the regenerator and then enters the reactor through the regeneration inclined tube at the bottom of the regenerator for recycling reaction.

[0060] To overcome the shortcomings of existing technologies, this invention provides a method for replacing catalytic cracking catalyst. The method includes: fluidizing gas flowing into a fluidized bed reactor from the bottom; and catalytic cracking catalyst from a regenerator entering the reactor from the upper part of a distribution plate. The fluidizing medium mixes with the flowing-down catalyst after passing through the distribution plate. The feedstock oil, after preheating, enters the bottom of the fluidized bed reactor through nozzles to mix and contact the catalyst in the reaction zone. The reacting oil and gas and the catalyst are rapidly separated at the end of the reactor. The separated catalyst is stripped and then enters the regenerator for coking and regeneration. Hot water, based on the number of heat exchange tubes required for heat exchange, enters the external heat exchanger from the corresponding heat exchange tube inlet. The steam after heat exchange flows out from the steam-water outlet. In conventional operation, the thermally regenerated catalyst enters the external heat exchanger for heat exchange and then returns to the regenerator. When switching operating modes, after the thermally regenerated catalyst exchanges heat through an external heat exchanger, 10%-90% of the cold catalyst is first discharged, and the remaining cold catalyst is returned to the regenerator. After the discharge is completed, new catalyst is added to the heat exchanger to mix and contact with the regenerated catalyst for heat exchange. After the heat exchange is completed, the mixed catalyst is returned to the regenerator for cyclic reaction. The rapid catalyst replacement method of this invention can achieve flexible adjustment of the product structure within a wide range.

[0061] Specifically, the process of the present invention may include the following steps:

[0062] (1) The catalyst from the regenerator enters the reactor from the bottom of the fluidized bed reactor.

[0063] (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.

[0064] (3) After the feed oil is preheated, it enters the fluidized bed reactor through the nozzle and mixes with the catalyst. The feed oil and the catalyst undergo catalytic cracking reaction under the action of the fluidized medium and flow upward.

[0065] (4) The reaction product oil and gas and the catalyst are separated at the top of the fluidized bed 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.

[0066] (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.

[0067] (6) Hot water: The number of hot water heat exchange tubes, hot water flow rate and hot water temperature are dynamically adjusted according to the heat exchange. Hot water enters the external heat exchanger from the hot water inlet of the corresponding heat exchange tube, and the steam after heat exchange flows out from the steam outlet.

[0068] (7) In the normal operation mode, the hot regenerated catalyst enters the external heat exchanger to exchange heat with hot water and recover excess heat. The catalyst after heat exchange is returned to the regenerator.

[0069] (8) When switching operating modes, after the hot regenerated catalyst is heated by the external heat exchanger, 10%-90% of the cold catalyst is first unloaded, and the remaining cold catalyst is returned to the regenerator. After the unloading is completed, the new catalyst is added to the external heat exchanger. The mixed catalyst is then heated and enters the regenerator for a cyclic reaction.

[0070] In one embodiment, the reactor is a fluidized bed reactor, preferably one or more of a fast bed reactor, a riser reactor, and a descending bed reactor.

[0071] In one embodiment, the reaction conditions of the reactor are:

[0072] The reaction temperature is 500-800℃;

[0073] The reaction pressure is 0.1-2.0 MPa;

[0074] The agent-to-oil ratio is 5-40;

[0075] The dwell time is 1.0-15.0 seconds.

[0076] In one embodiment, the external heat exchanger is an upward-moving external heat exchanger, and the number of heat exchange pipelines is 1-10 sets;

[0077] Preferably, in the external heat exchanger, the fluidizing gas velocity is 0.5-2 m / s; and / or

[0078] Preferably, in the external heat exchanger, the catalyst density is 50-400 kg / m³. 3 .

[0079] In one embodiment, the heat extraction medium in the heat extraction pipeline is selected from one or more of the following: water, raw oil, and refrigerant, wherein the refrigerant may be selected from ammonia refrigerants, hydrocarbon refrigerants, etc.

[0080] Preferably, the heat extraction medium is hot water, and the temperature of the hot water is preferably 20-100℃;

[0081] More preferably, the hot water inlet velocity of the heat extraction pipeline is 1-10 m / s.

[0082] In one embodiment, the regeneration temperature of the regenerator is 550-850°C; and / or

[0083] The regenerated catalyst enters the reactor from the bottom through a regeneration inclined tube.

[0084] In one embodiment, the feedstock oil is selected from one or more of heavy distillate oil, gasoline, and diesel oil;

[0085] Preferably, the raw oil is preheated before entering the reactor, and the preheating temperature is preferably 100-300℃.

[0086] In one embodiment, the oil and gas obtained from the stripping of the catalyst and the separated oil and gas products are jointly fed into the fractionation system.

[0087] The present invention also provides a catalytic cracking reaction system, comprising:

[0088] The reactor is equipped with a feed oil inlet, a reactor fluidized medium inlet, a catalyst inlet, an oil-gas separation device, a product oil-gas outlet, and a catalyst outlet. The oil-gas separation device includes a settling tank, a cyclone separator, and a stripper.

[0089] A regenerator is used to regenerate the catalyst to be generated. It is equipped with a catalyst to be generated inlet, a regeneration medium inlet, a cyclone separator, a flue gas outlet, a regeneration catalyst heat exchange outlet, a regeneration catalyst heat exchange return inlet, and a regeneration catalyst outlet. The catalyst to be generated inlet is connected to the catalyst to be generated outlet of the reactor through a catalyst to be generated inclined tube, and the catalyst to be generated outlet is connected to the catalyst inlet of the reactor through a regeneration inclined tube.

[0090] An external heat exchanger is used for heat exchange and catalyst replacement of the regenerated catalyst. It is provided with a regenerated catalyst heat exchange inlet, a regenerated catalyst heat exchange return outlet, a regenerated catalyst discharge outlet, one or more sets of parallel heat exchange pipes, a heat exchanger fluidizing medium inlet, and a catalyst replacement pipeline. The regenerated catalyst heat exchange inlet is connected to the regenerated catalyst heat exchange outlet of the regenerator through a regenerated catalyst heat exchange pipeline, and the regenerated catalyst heat exchange return outlet is connected to the regenerated catalyst heat exchange return inlet of the regenerator through a regenerated catalyst heat exchange return pipeline. The heat exchange pipes are housed inside the external heat exchanger, and a heat exchange medium inlet and a heat exchange medium outlet are formed on the shell surface of the external heat exchanger. Both the heat exchange medium inlet and the heat exchange medium outlet are located above the regenerated catalyst heat exchange inlet.

[0091] The displacement catalyst inlet is located at the lower part of the external heat exchanger, and below the heat exchange medium inlet and outlet, for supplying the displacement catalyst to the external heat exchanger;

[0092] The regenerated catalyst heat exchange return outlet and the regenerated catalyst unloading outlet are located on the upper part of the external heat exchanger and are both located above one or more sets of heat exchange pipes.

[0093] The fluidizing medium inlet of the heat exchanger is located at the bottom of the external heat exchanger and is used to introduce the fluidizing medium into the heat exchanger.

[0094] In the external heat exchanger of this invention, the replacement catalyst inlet is located at the lower part of the external heat exchanger, below the heat exchange medium inlet and outlet. The regenerated catalyst heat exchange return outlet and regenerated catalyst discharge outlet are located at the upper part of the external heat exchanger, both above one or more sets of heat exchange pipes. This arrangement allows the regenerated catalyst to move upward under the action of the fluidizing medium, and during this upward movement, it can fully exchange heat with the heat exchange medium in one or more sets of heat exchange pipes within the external heat exchanger. Furthermore, the heat exchange efficiency of the heat exchange pipes can be optimized and controlled according to the required heat exchange capacity for different bed densities at different heights.

[0095] In one embodiment, the external heat exchanger has two or more sets of parallel heat exchange pipes, and the vertical heights of the heat exchange pipes are different.

[0096] Preferably, the heat extraction pipe is in the shape of a serpentine coil.

[0097] In the external heat exchanger of this invention, by setting multiple sets of heat exchange pipes at different vertical heights, the opening and closing of the heat exchange pipes can be easily adjusted according to the heat balance in the reaction system, thereby obtaining an ideal heat exchange effect. Preferably, the heat exchange medium pipes of this invention are distributed in the form of serpentine coils within the external heat exchanger, which can increase the contact area between the heat exchange medium and the regenerated catalyst.

[0098] 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 10%-60% of the total height of the external heat exchanger; and / or

[0099] The volume of the serpentine coil accounts for 10%-50% of the total volume of the external heat exchanger;

[0100] Preferably, the heat exchange medium inlet and outlet of each heat exchange pipe are located at the same horizontal level.

[0101] 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 h1, h2, h3) accounts for a portion of the total height of the external heat exchanger (e.g.) Figure 1 The heat exchange efficiency is 10%-60% (as shown in H). When the height of the heat exchanger pipe is greater than 60%, the bed is in the dilute phase region, resulting in low heat exchange efficiency. When the height of the heat exchanger pipe is less than 10%, it will affect the mixing and flow of the regenerated catalyst at the bottom of the external heat exchanger.

[0102] The volume of the serpentine coil of the present 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.

[0103] like Figure 1As shown, the catalyst enters the fluidized bed reactor 5 through the regeneration slide valve 3. After being fluidized by the gas distribution plate 2, the fluidizing medium 1 enters the bottom of the fluidized bed reactor 5, where it carries the catalyst upward. The feed oil, after preheating, enters the bottom of the fluidized bed reactor 5 through the oil inlet nozzle 4 and mixes with the catalyst. The feed oil gas and catalyst flow upward into the fluidized bed reaction section 5 for catalytic cracking reaction to obtain product oil gas and the spent catalyst. The product oil gas and spent catalyst are separated at the top of the fluidized bed reactor 5 by a cyclone separator 7. The separated product oil gas is discharged from the fluidized bed reactor 5 through the product oil gas discharge pipeline 9, which can be connected to further oil gas treatment equipment, such as entering a fractionation unit. The catalyst separated by the cyclone separator 7 enters the settling tank 8, and the stripping medium 10 is used to strip the spent catalyst in the stripper internal components 6. The stripped catalyst enters the regenerator 12 through the regenerator slide valve 11, where it undergoes coking regeneration under the action of the regeneration medium 15. It is then separated and settled in the regenerator cyclone separator 13. The generated flue gas is separated again by the regenerator cyclone separator 13 and discharged from the flue gas outlet pipeline 14. The regenerated hot catalyst enters the external heat exchanger 19 through the hot regenerator replacement slide valve 17. Under the action of the fluidizing medium 18, the hot catalyst flows upwards to the top of the external heat exchanger 19, where it exchanges heat with the heat exchange medium in the pipeline. The heat exchange medium enters from the heat exchange medium inlet 20 and exits from the external heat exchanger 19 through the heat exchange medium outlet 21. During the heat exchange process, the heat exchange medium may undergo a phase change; for example, when the heat exchange medium is water, it may vaporize to form steam, which is then exited from the heat exchange medium outlet 21. In normal operation mode, the cooled regenerator after heat exchange returns to the regenerator through the regenerator catalyst return pipeline slide valve 22 and settles to the bottom of the regenerator before entering the reactor through the regeneration slide valve 3 for the next cycle.

[0104] When the operation mode is switched to catalyst replacement mode, the hot water inlet 20 dynamically adjusts the number of openings and closings, the hot water flow rate, and the hot water temperature as needed.

[0105] The heat extraction area of ​​the heat extraction pipe of this invention satisfies the following formula:

[0106]

[0107] in:

[0108] A is the heat exchanger area in meters (m²). 2 ;

[0109] Q is the amount of heat transferred, expressed in kW.

[0110] U is the heat transfer coefficient, W / m³ 2· ℃;

[0111] ΔT is the temperature difference of the fluid. ℃。

[0112] After the hot regenerated catalyst enters the external heat exchanger 19, it flows upward under the action of the catalyst fluidizing medium 18 in the external heat exchanger. After flowing to the top of the external heat exchanger 19 and completing heat exchange, part of the regenerated catalyst from Erligang returns to the regenerator 12 through the regenerated catalyst return pipeline slide valve 22, and part of the catalyst is discharged from the external heat exchanger 19 through the regenerated catalyst discharge pipeline slide valve 23, thus completing the unloading. The heat exchange medium enters from the heat exchange medium inlet 20 and exits from the external heat exchanger 19 through the heat exchange medium outlet 21. After the unloading is completed, a new replacement catalyst is added to the external heat exchanger 19 through the pipeline 16. The hot regenerated catalyst enters the external heat exchanger 19 through the hot regenerated catalyst replacement slide valve 17 and mixes with the new replacement catalyst to form a mixed catalyst. The mixed catalyst flows upward under the action of the catalyst fluidizing medium 18 in the external heat exchanger. After flowing to the top of the external heat exchanger 19, it returns to the regenerator 12 and settles to the bottom of the regenerator, entering the fluidized bed reactor 5 through the regeneration slide valve 3 to participate in the reaction. The reaction conditions in the fluidized bed reactor are: reaction temperature of 500-800℃, reaction pressure of 0.1-2.0MPa, agent-to-oil ratio of 5-40, and residence time of 1.0-15.0 seconds. The regeneration conditions in the regenerator are: regeneration temperature of 550-850℃, and regeneration medium of air.

[0113] The properties of the raw material mixtures of heavy oil used in the examples and comparative examples are shown in Table 1.

[0114] The catalysts used in the examples are commercial FMMC catalysts and CGP catalysts.

[0115] The following Examples 1 and 2 both adopt the following... Figure 1 The device shown has 4 sets of heat extraction pipes.

[0116] The catalyst density in the external heat exchanger is 350 kg / m³. 3 ;

[0117] The height of the heat exchange medium inlet of each heat exchange pipe from the bottom of the external heat exchanger accounts for 15%, 25%, 35%, and 45% of the total height of the external heat exchanger, respectively.

[0118] The volume of the serpentine 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 riser reactor, using the mixed heavy oil in Table 1 as feedstock and FMMC catalyst.

[0121] The device used in this embodiment has a volume of 1m³. 3The catalyst loading is 8 kg.

[0122] The process conditions for reaction and regeneration are as follows: the preheating temperature of the mixed heavy oil is 200℃, the reaction outlet temperature is 530℃, the agent-to-oil ratio is 6, the reaction pressure is 0.2MPa, the residence time is 2s, the regenerator outlet temperature is 700℃, and the regenerator medium is air.

[0123] Two sets of heat exchange tubes are open, the heat exchange medium is hot water, the hot water flow rate is 1m / s, and the hot water temperature is 50℃.

[0124] The catalyst enters the fluidized bed reactor 5 through the regeneration slide valve 3. The fluidizing medium 1, after being fluidized by the gas distribution plate 2, enters the bottom of the fluidized bed reactor 5, carrying the catalyst upwards. The feed oil, preheated to 200°C, enters the bottom of the fluidized bed reactor 5 through the inlet nozzle 4 and mixes with the catalyst. The feed oil gas and catalyst flow upwards in parallel into the reaction section for catalytic cracking. The reaction product oil gas and catalyst are separated at the top of the reactor by a cyclone separator 7. The separated product oil gas enters the fractionation unit through the product oil gas discharge pipeline 9. The catalyst separated by the cyclone separator 7 enters the stripper and is stripped by the stripping medium 10 (in this embodiment, the stripping medium is steam). The stripped catalyst enters the regenerator 12 through the regeneration slide valve 11 for coke burn regeneration. It is then separated and settled in the regenerator cyclone separator 13. The generated flue gas is separated by the regenerator cyclone separator 13 and discharged from the flue gas outlet pipeline 14. The regenerated thermal catalyst enters the external heat exchanger 19 through the thermal regenerator replacement valve 17. Under the action of the fluidizing medium 18, the thermal catalyst flows upward and reaches the top of the external heat exchanger 19, where it exchanges heat with the hot water in the two sets of heat exchange pipes. After heat exchange, the cooled regenerator returns to the regenerator through the regenerator return pipeline valve 22 and settles to the bottom of the regenerator before entering the reactor through the regeneration valve 3 for the next cycle.

[0125] When switching operating modes, the FMMC catalyst flows into the external heat exchanger 19 via the regenerator replacement valve 17. Under the action of the catalyst fluidizing medium 18 in the external heat exchanger, it flows upward. After flowing above the external heat exchanger 19, part of the catalyst returns to the regenerator 12 via the regenerator return pipeline valve 22, and part of the catalyst is discharged from the external heat exchanger 19 via the regenerator discharge pipeline valve 23, completing the unloading. Hot water enters through two sets of heat exchange medium inlets 20, and the generated steam flows out through the heat exchange medium outlet 21. After unloading, the catalyst is added. The CGP catalyst is added to the external heat exchanger 19 through the new catalyst addition pipeline 16. It mixes with the regenerated hot FMMC catalyst flowing into the external heat exchanger 19 through the hot regenerator replacement valve 17 and completes heat exchange. The mixed catalyst (FMMC+CGP) flows upward under the action of the fluidizing medium. After flowing above the external heat exchanger 19, it returns to the regenerator 12 and then enters the fluidized bed reactor through the regeneration valve 3 for reaction.

[0126] Under these conditions, after stable operation, when the replacement rate of the new catalyst reaches 40%, the replacement time is measured to be 6 hours.

[0127] Example 2

[0128] 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 riser reactor, using the mixed heavy oil in Table 1 as feedstock and FMMC catalyst.

[0129] The device used in this embodiment has a volume of 1m³. 3 The catalyst loading is 8 kg.

[0130] The process conditions for reaction and regeneration are as follows: the preheating temperature of the mixed heavy oil is 200℃, the reaction outlet temperature is 530℃, the agent-to-oil ratio is 6, the reaction pressure is 0.2MPa, the residence time is 2s, the regenerator outlet temperature is 700℃, and the regenerator medium is air.

[0131] The number of heat pipes is 4, the hot water flow rate is 1m / s, and the hot water temperature is 50℃.

[0132] The catalyst enters the fluidized bed reactor 5 through the regeneration slide valve 3. The fluidizing medium 1, after being fluidized by the gas distribution plate 2, enters the bottom of the fluidized bed reactor 5, carrying the catalyst upwards. The feed oil, preheated to 200°C, enters the bottom of the fluidized bed reactor 5 through the inlet nozzle 4 and mixes with the catalyst. The feed oil gas and catalyst flow upwards in parallel into the reaction section for catalytic cracking. The reaction product oil gas and catalyst are separated at the top of the reactor by a cyclone separator 7. The separated product oil gas enters the fractionation unit through the product oil gas discharge pipeline 9. The catalyst separated by the cyclone separator 7 enters the stripper and is stripped by the stripping medium 10 (in this embodiment, the stripping medium is steam). The stripped catalyst enters the regenerator 12 through the regeneration slide valve 11 for coke burn regeneration. It is then separated and settled in the regenerator cyclone separator 13. The generated flue gas is separated by the regenerator cyclone separator 13 and discharged from the flue gas outlet pipeline 14. The regenerated thermal catalyst enters the external heat exchanger 19 through the thermal regenerator replacement valve 17. Under the action of the fluidizing medium 18, the thermal catalyst flows upward and reaches the top of the external heat exchanger 19, where it exchanges heat with the hot water in the two sets of heat exchange pipes. After heat exchange, the cooled regenerator returns to the regenerator through the regenerator return pipeline valve 22 and settles to the bottom of the regenerator before entering the reactor through the regeneration valve 3 for the next cycle.

[0133] When switching operating modes, the FMMC catalyst flows into the external heat exchanger 19 via the hot regenerator displacement valve 17. Under the action of the catalyst fluidizing medium 18 in the external heat exchanger, it flows upward. After flowing above the external heat exchanger 19, part of the catalyst returns to the regenerator 12 via the regenerated catalyst return pipeline valve 22, and part of the catalyst is discharged from the external heat exchanger 19 via the regenerated catalyst discharge pipeline valve 23. Hot water enters through four sets of heat exchange medium inlets 20, and the generated steam flows out through the heat exchange medium outlet 21. After the unloading is completed, the catalyst is added. The CGP catalyst is added to the external heat exchanger 19 through the new catalyst addition pipeline 16. It mixes with the regenerated hot FMMC catalyst that flows into the external heat exchanger 19 via the hot regenerator displacement valve 17 and completes the heat exchange. The mixed catalyst (FMMC+CGP) flows upward under the action of the fluidizing medium. After flowing above the external heat exchanger 19, it returns to the regenerator 12 and then enters the fluidized bed reactor through the regeneration valve 3 to react.

[0134] Under these conditions, after stable operation, when the replacement rate of the new catalyst reaches 40%, the replacement time is measured to be 4.5 hours.

[0135] Comparative Example 1

[0136] This comparative example uses the existing conventional riser catalytic cracking process, and the reaction is carried out in a small riser reactor. FMMC catalyst is used, and the feed oil is the same as in Example 1. The operating conditions and product distribution are listed in Table 2.

[0137] The comparative example uses a device with a volume of 1m³. 3 The catalyst loading is 8 kg.

[0138] The reaction and regeneration process conditions are as follows: mixed heavy oil preheating temperature is 200℃, reaction outlet temperature is 530℃, catalyst-to-oil ratio is 6, reaction pressure is 0.2MPa, residence time is 2s, regenerator outlet temperature is 700℃, regenerator medium is air, and the weight ratio of steam to total feedstock is 0.2. Catalyst replacement is performed using conventional methods. Part of the FMMC 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.

[0139] Under these conditions, after stable operation, when the replacement rate of the new catalyst reached 40%, the replacement time was measured to be 24 hours. This replacement time is 4 times and 5.33 times that of Examples 1 and 2, respectively, indicating a longer replacement time.

[0140] Using the apparatus of Comparative Example 1, Example 1, and Example 2, the catalyst replacement ratio and product distribution after simultaneous replacement for 6 hours are shown in Table 2. As can be seen from the table, the replacement methods used in Example 1 and Example 2 have a faster replacement rate, allowing for quicker adjustment of the product structure, and are particularly suitable for flexible adjustments in large-scale plants.

[0141] Table 1

[0142]

[0143]

[0144] Table 2

[0145]

[0146] *Propylene yield refers to the yield of propylene further separated from the product.

[0147] 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 method for catalyst circulation and heat exchange in a catalytic cracking reaction system, comprising: The feedstock oil reacts with the catalytic cracking catalyst in the reactor under the action of fluidizing gas through back-mixing. The resulting oil and gas products are separated from the spent catalyst at the end of the reactor. The separated oil and gas products are led out of the reactor. The spent catalyst is stripped and then enters the regenerator for regeneration. The regenerated catalyst enters the external heat exchanger for heat exchange. The external heat exchanger is equipped with one or more sets of parallel heat exchange pipelines. In a conventional cyclic reaction, the regenerated catalyst after heat exchange is returned to the regenerator and then enters the reactor for cyclic reaction through the regeneration inclined tube set at the bottom of the regenerator; During catalyst replacement, 10%-90% of the cooled regenerated catalyst after heat exchange is discharged through the unloading pipe of the external heat exchanger. After unloading, the replacement catalyst is added to the heat exchanger for mixing and heat exchange. The mixed catalyst is then returned to the regenerator and then enters the reactor through the regeneration inclined tube at the bottom of the regenerator for recycling reaction.

2. The method according to claim 1, characterized in that, The reactor is a fluidized bed reactor, preferably one or more of a rapid bed reactor, a riser reactor, and a descending bed reactor.

3. The method according to claim 1, 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 5-40; The dwell time is 1.0-15.0 seconds.

4. The method according to claim 1, characterized in that, The external heat exchanger is an upward-moving external heat exchanger, and the number of heat exchange pipelines is 1-10 sets. Preferably, in the external heat exchanger, the fluidizing gas velocity is 0.5-2 m / s; and / or Preferably, in the external heat exchanger, the catalyst density is 50-400 kg / m³. 3 .

5. The method according to claim 1, characterized in that, The heat extraction medium in the heat extraction pipeline is selected from one or more of the following: water, raw oil, and refrigerant; Preferably, the heat extraction medium is hot water, and the temperature of the hot water is preferably 20-100℃; More preferably, the hot water inlet velocity of the heat extraction pipeline is 1-10 m / s.

6. The method according to claim 1, characterized in that, The regeneration temperature of the regenerator is 550-850℃; and / or The regenerated catalyst enters the reactor from the bottom through a regeneration inclined tube.

7. The method according to claim 1, characterized in that, The feedstock oil is selected from one or more of heavy distillate oil, gasoline, and diesel oil; Preferably, the raw oil is preheated before entering the reactor, and the preheating temperature is preferably 100-300℃.

8. The method according to claim 1, characterized in that, The oil and gas obtained from the stripping of the catalyst and the separated oil and gas products enter the fractionation system together.

9. A catalytic cracking reaction system, comprising: The reactor is equipped with a feed oil inlet, a reactor fluidized medium inlet, a catalyst inlet, an oil-gas separation device, a product oil-gas outlet, and a catalyst outlet. The oil-gas separation device includes a settling tank, a cyclone separator, and a stripper. A regenerator is used to regenerate the catalyst to be generated. It is equipped with a catalyst to be generated inlet, a regeneration medium inlet, a cyclone separator, a flue gas outlet, a regeneration catalyst heat exchange outlet, a regeneration catalyst heat exchange return inlet, and a regeneration catalyst outlet. The catalyst to be generated inlet is connected to the catalyst to be generated outlet of the reactor through a catalyst to be generated inclined tube, and the catalyst to be generated outlet is connected to the catalyst inlet of the reactor through a regeneration inclined tube. An external heat exchanger is used for heat exchange and catalyst replacement of the regenerated catalyst. It is provided with a regenerated catalyst heat exchange inlet, a regenerated catalyst heat exchange return outlet, a regenerated catalyst discharge outlet, one or more sets of parallel heat exchange pipes, a heat exchanger fluidizing medium inlet, and a replacement catalyst inlet. The regenerated catalyst heat exchange inlet is connected to the regenerated catalyst heat exchange outlet of the regenerator through a regenerated catalyst heat exchange pipeline. The regenerated catalyst heat exchange return outlet is connected to the regenerated catalyst heat exchange return inlet of the regenerator through a regenerated catalyst heat exchange return pipeline. The heat exchange pipes are housed inside the external heat exchanger, and a heat exchange medium inlet and a heat exchange medium outlet are formed on the shell surface of the external heat exchanger. Both the heat exchange medium inlet and the heat exchange medium outlet are located above the regenerated catalyst heat exchange inlet. The displacement catalyst inlet is located at the lower part of the external heat exchanger, and below the heat exchange medium inlet and outlet, for supplying the displacement catalyst to the external heat exchanger; The fluidizing medium inlet of the heat exchanger is located at the bottom of the external heat exchanger and is used to introduce the fluidizing medium into the heat exchanger.

10. The reaction system according to claim 9, characterized in that, The external heat exchanger has two or more sets of parallel heat exchange pipes, and the vertical heights of the heat exchange pipes are different. Preferably, the heat extraction pipe is in the shape of a serpentine coil.

11. The reaction system according to claim 10, characterized in that, The height of the heat exchange medium inlet of the heat exchange pipe from the bottom of the external heat exchanger accounts for 10%-60% of the total height of the external heat exchanger; and / or the volume of the serpentine coil accounts for 10%-50% of the total volume of the external heat exchanger. Preferably, the heat exchange medium inlet and outlet of each heat exchange pipe are located at the same horizontal level.

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