A regenerator heat supplement system and heat supplement method based on molten salt heat supply

Abstract

The application discloses a regenerator heat supplement system and method based on molten salt heat supply, relates to the field of catalyst regenerator heat supplement, and comprises an external heater for supplementing heat to a regenerator, a molten salt fluidized bed and a gas generating system for delivering a heat source to the molten salt fluidized bed, wherein the external heater has a shell side and a tube side, the tube side of the external heater is communicated with the molten salt fluidized bed, and the shell side is communicated with the regenerator; a three-cyclone is connected to an exhaust pipe of the regenerator, two exhaust branch pipes are arranged at the end of an exhaust pipe of the three-cyclone, one of the exhaust branch pipes is connected with a flue gas turbine, and the other exhaust branch pipe is divided into two exhaust sub-branches after a fluidized flue gas compressor, one of the exhaust sub-branches is connected to a catalyst inlet of the regenerator, and the other exhaust sub-branch is connected to the shell side of the external heater. The application is used for solving the technical problem of insufficient heat in the catalyst regenerator during a light hydrocarbon catalytic cracking process.

Description

Technical Field

[0001] This invention relates to the field of catalyst regenerator reheating, specifically a regenerator reheating system and method based on molten salt heating. Background Technology

[0002] Low-carbon olefins are one of the important chemical materials for producing polymers (polyethylene and polypropylene) and are also one of the main products of the petrochemical industry. With the development of the chemical industry, the demand for low-carbon olefins has grown rapidly, and their production has become an important indicator of economic development. Currently, the domestic production of ethylene and propylene is insufficient, with a self-sufficiency rate of about 64% for ethylene and about 77% for propylene, still requiring large-scale imports. Previously, the production of ethylene and propylene mainly relied on steam cracking technology. In recent years, fluidized bed light hydrocarbon processing units have developed rapidly and have gradually become an important production process for chemical feedstocks such as propylene and ethylene. Fluidized bed light hydrocarbon processing units mainly include fluidized bed light hydrocarbon catalytic cracking units and propane dehydrogenation units. Among them, the light oil (light hydrocarbon) catalytic cracking process is a catalytic cracking process that uses naphtha or C4-C8 light hydrocarbons as processing feedstocks. In recent years, related technologies have developed rapidly, with representative processes including ACO, OCC, SuperflexTM, and K-COT processes. Because the feedstock oil is light and produces less coke, the heat from coke burning in the regenerator is insufficient to meet the heat required for the reaction. To maintain thermal balance, heat needs to be added to the regenerator.

[0003] Two methods are generally used to address the issue of supplementing the system with heat. One method is to increase the temperature of the reaction feedstock to supplement the heat required for the reaction. However, when the feedstock used in the light oil (light hydrocarbon) catalytic cracking process is lighter and the reaction conditions are more demanding, requiring more heat of reaction, an even higher feed temperature is needed. This can lead to thermal cracking side reactions, making the entire process ineffective. The other method is to inject fuel oil into the catalyst bed of the regenerator, allowing it to mix and burn with the main air in the regenerator, raising the catalyst temperature and thus providing the heat required for the reaction. Alternatively, an external heat exchanger can be added outside the unit. The catalyst is introduced from the regenerator into the heat exchanger, where fuel oil is injected. Under oxygen-deficient and low-temperature conditions, the fuel oil is converted into coke, which adheres to the catalyst. The catalyst carrying the coke then enters the regenerator for coking, raising the catalyst temperature and thus meeting the heat requirements for the reaction. However, the temperature of externally supplied fuel oil combustion is difficult to control, leading to localized overheating. Simultaneously, fuel oil combustion produces high-temperature water vapor, which increases the risk of catalyst breakage and deactivation, as well as hydrothermal deactivation, and also increases carbon dioxide emissions. Summary of the Invention

[0004] This invention provides a regenerator heating system and method based on molten salt heating to solve the technical problem of insufficient heat in the catalyst regenerator during light hydrocarbon catalytic cracking processes.

[0005] To achieve the above objectives, the specific solution adopted by the present invention is as follows: a regenerator heat supply system based on molten salt heating, including an external heat supply for supplying heat to the regenerator, a molten salt fluidized bed, and a gas generation system for supplying heat to the molten salt fluidized bed. The external heat supply has a shell side and a tube side. The tube side of the external heat supply is connected to the molten salt fluidized bed, and the shell side is connected to the regenerator.

[0006] The regenerator's flue gas discharge pipe is connected to a three-cyclone system. The exhaust pipe of the three-cyclone system is divided into two exhaust branches at the end. One exhaust branch is connected to the flue gas hood, and the other exhaust branch is divided into two exhaust branches after passing through the fluidized flue gas compressor. One exhaust branch is connected to the catalyst inlet of the regenerator, and the other exhaust branch is connected to the shell side of the external heatsink.

[0007] As a further optimization of the above technical solution: the gas generation system includes an oxygen generator, an oxygen compressor, a gas mixing and heating tank and an auxiliary combustion chamber connected in sequence, and the auxiliary combustion chamber is connected to a gas distributor pipeline installed in the molten salt fluidized bed.

[0008] As a further optimization of the above technical solution: the heating gas delivery pipeline of the gas mixing heating tank is divided into two delivery branches, one of which is connected to the auxiliary combustion chamber main air duct of the auxiliary combustion chamber, and the other delivery branch is connected to the regenerator main air duct of the regenerator.

[0009] As a further optimization of the above technical solution: the oxygen generating device is an air separation device or an electrolysis water device.

[0010] As a further optimization of the above technical solution: the molten salt fluidized bed is provided with a first molten salt outlet, a first molten salt circuit, a second molten salt outlet, a second molten salt circuit, and a molten salt fluidized bed flue gas discharge pipeline.

[0011] The first molten salt outlet is connected to the tube-side inlet of the external heat exchanger, and the tube-side outlet of the external heat exchanger is connected to the first molten salt circuit; the second molten salt outlet is connected to the feed inlet of the solar molten salt field, and the discharge outlet of the solar molten salt field is connected to the second molten salt circuit; the end of the molten salt fluidized bed flue gas discharge pipeline is connected to the exhaust pipeline of the three-cyclone system.

[0012] As a further optimization of the above technical solution: downstream of the flue gas machine, a waste heat boiler, a desulfurization and denitrification device, a flue gas dehydration device, and a carbon dioxide separation device are connected in sequence. The outlet of the carbon dioxide separation device is provided with two discharge branches, one of which is connected to the gas mixing and heating tank, and the other is connected to the carbon dioxide comprehensive utilization process.

[0013] As a further optimization of the above technical solution: a carbon dioxide compressor is installed on the discharge branch connecting the carbon dioxide separation device and the gas mixing heating tank.

[0014] As a further optimization of the above technical solution: a gas transmission pipeline is provided on the exhaust branch of the flue gas fan. The inlet end of the gas transmission pipeline is connected to the upstream of the flue gas fan, and the outlet end is connected to the waste heat boiler.

[0015] As a further optimization of the above technical solution: the regenerator is connected to a return pipe for the catalyst to return after reheating, one end of the return pipe extends into the regenerator and the other end is the catalyst inlet; the shell side of the external heatsink is connected to an outlet pipe for the catalyst to be discharged after reheating, and the discharge port of the outlet pipe is connected to the catalyst inlet.

[0016] As a further optimization of the above technical solution: a balance pipe is connected between the external heat supply unit and the regenerator.

[0017] A regenerator reheating method based on molten salt heating is disclosed. This method employs the aforementioned regenerator reheating system. Molten salt in the molten salt fluidized bed is transported to the tube side of an external heat exchanger, while the catalyst to be reheated in the regenerator is transported to the shell side of the external heat exchanger. The catalyst in the shell side of the external heat exchanger exchanges heat with the molten salt in the tube side and then returns to the regenerator. The regenerated flue gas from the regenerator enters a three-cyclone system for gas-solid separation. Part of the separated gas is used as fluidizing air to fluidize the catalyst in the shell side of the external heat exchanger, and another part is used as transport air to transport the heat-exchanged catalyst to the regenerator. The third part undergoes cooling, desulfurization and denitrification, flue gas dehydration, and carbon dioxide separation. A portion of the separated carbon dioxide is recycled to the gas generation system of the molten salt fluidized bed, while the other part enters the carbon dioxide comprehensive utilization process.

[0018] Compared with the prior art, the present invention has the following beneficial effects:

[0019] 1. This invention solves the technical problem of insufficient heat in the catalyst regenerator during light hydrocarbon catalytic cracking processes by using molten salt as a supplementary heating medium to heat the catalyst in the regenerator. The molten salt is fed into the tube side of an external heat exchanger to exchange heat with the catalyst entering the shell side. During this heat exchange, the catalyst and molten salt do not directly contact each other, thus preventing localized overheating and catalyst breakage / deactivation. Furthermore, the hot flue gas generated by the auxiliary combustion chamber is introduced into the molten salt fluidized bed to heat the molten salt. The high-temperature water vapor in the flue gas does not come into contact with the catalyst, preventing hydrothermal deactivation. The external heat exchanger supplements the catalyst's heating, ensuring the regenerated catalyst reaches the required process temperature. In addition, melting the salt in the molten salt fluidized bed before feeding it into the external heat exchanger allows for significant heat exchange with the catalyst even with a small heat exchange area, thanks to the high heat transfer coefficient of molten salt. This reduction in heat exchange area decreases heat loss and energy consumption, lowering the investment cost of the equipment.

[0020] 2. This invention uses a solar-powered molten salt field to assist in heating the molten salt. At startup, the salt can be melted by the solar-powered molten salt field and sent into the molten salt fluidized bed. When the system is running normally, it can assist in heating the molten salt, reducing the amount of heat exchange flue gas generated in the gas generation system, thereby reducing the energy consumption of the molten salt fluidized bed and reducing the amount of carbon dioxide generated in the entire supplementary heating system.

[0021] 3. The regenerated flue gas in the regenerator is recycled as fluidizing air and conveying air, eliminating the need to add additional gas to the external heat exchanger and regenerator as fluidizing air and conveying air. On the one hand, this can save gas consumption in the external heat exchanger and regenerator, and reduce the energy loss caused by heating the fluidizing air and conveying air when adding additional high-temperature fluidizing air and conveying air. On the other hand, without adding additional gas as fluidizing air or conveying air, the carbon dioxide concentration in the regenerated flue gas can be maintained, and the energy consumption of the subsequent carbon dioxide separation unit can be reduced.

[0022] 4. This invention adopts a carbon dioxide recycling and capture technology in flue gas. After the carbon dioxide in the flue gas is separated by a carbon dioxide separation device, part of it goes to the carbon dioxide comprehensive utilization process, and the other part of the carbon dioxide enters the gas mixing and heating tank to mix with oxygen and then circulate, thereby increasing the carbon dioxide concentration in the subsequent flue gas, and thus achieving carbon dioxide capture and zero carbon dioxide emissions in the entire process.

[0023] 5. This invention can be applied to the construction of new facilities, and it is also well applicable to old facilities with insufficient combustion capacity. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the regenerator reheating system in this invention;

[0025] Reference numerals: 1. Oxygen generator; 2. Oxygen compressor; 3. Gas mixing and heating tank; 301. Heating equipment; 302. Heating gas delivery pipeline; 4. Auxiliary combustion chamber; 401. Main air duct of auxiliary combustion chamber; 402. Fuel delivery pipeline; 5. Molten salt fluidized bed; 501. Gas distributor; 502. First molten salt outlet; 503. First molten salt circuit; 504. Flue gas discharge pipeline of molten salt fluidized bed; 505. Solar panel; 506. Second molten salt outlet; 507. Solar molten salt field; 508. Second molten salt circuit; 6. 601. External heat exchanger; 602. Balance tube; 603. Heat exchange tube bundle; 604. Inlet pipe; 605. Fluidized air duct; 606. Outlet pipe; 607. Slide valve; 708. Regenerator; 709. Catalyst distributor; 7000. Main air distributor; 701. Regenerator main air duct; 702. Return pipe; 703. Conveying air duct; 704. Triple cyclone; 705. Flue gas fan; 10. Waste heat boiler; 11. Desulfurization and denitrification device; 12. Flue gas dehydration device; 13. Carbon dioxide separation device; 14. Carbon dioxide compressor; 15. Fluidized flue gas compressor; 16. Gas transmission pipeline. Detailed Implementation

[0026] The technical solution of the present invention will be further described in detail below with reference to specific embodiments. Parts not described or disclosed in detail in the following embodiments of the present invention should be understood as prior art known or should be known by those skilled in the art, such as the specific structure of oxygen generating device, oxygen compressor, gas mixing heating tank, auxiliary combustion chamber, molten salt fluidized bed, external heat supply, slide valve, regenerator, catalyst distributor, main air distributor, return pipe, triple cyclone, flue gas fan, waste heat boiler, desulfurization and denitrification device, flue gas dehydration device, carbon dioxide separation device, carbon dioxide compressor, fluidized flue gas compressor, etc.

[0027] Example 1

[0028] Please see Figure 1This invention discloses a regenerator reheating system based on molten salt heating, comprising an external heat exchanger 6, a molten salt fluidized bed 5, and a gas generating system for supplying heat to the molten salt fluidized bed 5. The external heat exchanger 6 is a tubular heat exchanger, including a shell and a heat exchange tube bundle 602 disposed within the shell. The pipes of the heat exchange tube bundle 602 constitute the tube side of the external heat exchanger 6, and the space between the shell and the heat exchange tube bundle 602 constitutes the shell side of the external heat exchanger 6. The gas generating system supplies hot flue gas to the molten salt fluidized bed 5 as a heat source. The salt absorbs heat and melts into molten salt within the molten salt fluidized bed 5. The molten salt fluidized bed 5 is connected to the tube side of the external heat exchanger 6 to supply molten salt to the tube side. The shell side of the external heat exchanger 6 is used to supply the catalyst to be reheated in the regenerator 7. The catalyst in the shell side exchanges heat with the molten salt in the tube side, and the reheated catalyst returns to the regenerator 7 to achieve reheating of the reaction in the regenerator 7. Among them, salts that can absorb heat and melt into molten salts include, but are not limited to, one or more of nitrates, carbonates, chlorides, ceramic-based and metal-based composite materials, such as Na2SO4 / SiO2 and K2CO3 / Li.

[0029] The gas generation system includes an oxygen generator 1, an oxygen compressor 2, a gas mixing and heating tank 3, and an auxiliary combustion chamber 4 connected in sequence. The auxiliary combustion chamber 4 is connected to a gas distributor 501 installed in the molten salt fluidized bed 5 so that the hot flue gas generated by the combustion in the auxiliary combustion chamber 4 can be distributed to the molten salt fluidized bed 5 through the gas distributor 501 as a heat source for heating the molten salt fluidized bed 5.

[0030] Oxygen generator 1 is either an air separator or a water electrolysis device. If an air separator is used, oxygen and nitrogen are separated. The oxygen enters the gas mixing and heating tank 3 via the oxygen compressor 2, while the nitrogen can go to the external ammonia synthesis unit (not shown in the figure). If a water electrolysis device is used, oxygen and hydrogen are separated. The oxygen enters the gas mixing and heating tank 3 via the oxygen compressor 2, while the hydrogen can be used as fuel in the auxiliary combustion chamber 4 to mix and burn with the gas discharged from the gas mixing and heating tank 3.

[0031] A heating device 301 is installed inside the gas mixing and heating tank 3. A heating gas delivery pipeline 302 is connected to the tank body of the gas mixing and heating tank 3. The gas entering the gas mixing and heating tank 3 is heated by the heating device 301 and then discharged through the heating gas delivery pipeline 302. The heating gas delivery pipeline 302 is divided into two delivery branches. One delivery branch is connected to the auxiliary combustion chamber main air duct 401 of the auxiliary combustion chamber 4. The gas in this delivery branch enters the auxiliary combustion chamber 4 as the main air. The other delivery branch is connected to the regenerator main air duct 703 of the regenerator 7. The gas in this delivery branch is used as the main air of the regenerator 7. A main air distributor 702 connected to the regenerator main air duct 703 is installed inside the regenerator 7. The auxiliary combustion chamber 4 is also connected to a fuel delivery pipe 402 for delivering fuel into it. The fuel is fuel oil or green fuel. The hydrogen obtained from the water electrolysis device and the ammonia synthesized from the nitrogen separated by the air separation device can be delivered to the auxiliary combustion chamber 4 through the fuel delivery pipe 402. Using hydrogen or ammonia as fuel can reduce the greenhouse gas emissions of the system.

[0032] The molten salt fluidized bed 5 is provided with a first molten salt outlet 502, a first molten salt circuit 503, a second molten salt outlet 506, a second molten salt circuit 508, and a molten salt fluidized bed flue gas discharge pipe 504. The first molten salt outlet 502 is connected to the tube-side inlet of the external heatsink 6, the tube-side outlet of the external heatsink 6 is connected to the first molten salt circuit 503, the second molten salt outlet 506 is connected to the feed inlet of the solar molten salt field 507, and the discharge outlet of the solar molten salt field 507 is connected to the second molten salt circuit 508. The hot flue gas generated in the auxiliary combustion chamber 4 enters the gas distributor 501 of the molten salt fluidized bed 5 and exchanges heat with the molten salt in the molten salt fluidized bed 5. A portion of the molten salt in the molten salt fluidized bed 5 enters the solar molten salt field 507 through the second molten salt outlet 506. The solar energy generated by the sun 505 is used to heat the molten salt. The heated molten salt enters the molten salt fluidized bed 5 through the second molten salt circuit 508. The molten salt that reaches the required temperature enters the external heat exchanger 6 through the first molten salt outlet 502. After heat exchange in the external heat exchanger 6, the molten salt returns to the molten salt fluidized bed 5 through the first molten salt circuit 503. This invention employs a solar-powered molten salt field 507 to assist in heating the molten salt. In the initial stage of the system, the salt can be melted by the solar-powered molten salt field 507 and then fed into the molten salt fluidized bed 5. When the system is operating normally, the molten salt enters the external heat exchanger 6 to exchange heat with the catalyst, resulting in a large heat consumption. The solar-powered molten salt alone is insufficient to maintain the normal operation of the system. Hot flue gas generated by the gas generation system is used as a heat source to heat the molten salt. Solar-assisted heating of the molten salt not only ensures the normal operation of the system but also reduces the energy consumption of the molten salt fluidized bed 5 and lowers the carbon dioxide production of the system.

[0033] An inlet pipe 603 connects the shell-side inlet of the external heater 6 and the regenerator 7 to transport the catalyst to be reheated in the regenerator 7 to the shell side of the external heater 6. An outlet pipe 605 connects to the shell-side outlet of the external heater 6 to discharge the reheated catalyst. A slide valve 606 is installed on the pipe body of the outlet pipe 605. A return pipe 704 is connected to the regenerator 7 to return the reheated catalyst. One end of the return pipe 704 extends into the regenerator and is connected to the catalyst distributor 701 installed in the regenerator 7. The other end is the catalyst inlet, which is connected to the discharge port of the outlet pipe 605. The catalyst inlet is also connected to a conveying air pipe 705 to introduce conveying air into the return pipe 704, so as to transport the catalyst into the regenerator 7 by conveying air.

[0034] The regenerator 7 has a three-swirl 8 connected to its flue gas discharge pipe. The exhaust pipe of the three-swirl 8 has two exhaust branches at its end. One exhaust branch is connected to a flue gas fan 9 to send the gas from the exhaust branch to the flue gas fan 9 to do work. The other exhaust branch is connected to a fluidized flue gas compressor 15. After passing through the fluidized flue gas compressor 15, there are two exhaust branches. One exhaust branch is connected to the catalyst inlet of the regenerator 7. Specifically, this exhaust branch is the conveying air duct 705, or the exhaust branch is connected to the air inlet of the conveying air duct 705. The gas in this exhaust branch is used as conveying air to the return pipe 704, and then the catalyst in the return pipe 704 is conveyed to the regenerator 7. The other exhaust branch is connected to the shell side of the external heat exchanger 6. This exhaust branch is the fluidized air duct 604, or the exhaust branch is connected to the fluidized air duct 604 connected to the shell side of the external heat exchanger 6 to input fluidized air into the shell side to fluidize the catalyst in the shell side.

[0035] The flue gas discharge pipe 504 of the molten salt fluidized bed is connected to the exhaust pipe of the three-swirl 8. This is because the flue gas discharged from the molten salt fluidized bed 5 does not contain solid particles and can directly enter the flue gas machine 9 to do work. This connection method can reduce the load on the three-swirl 8, reduce the size of the three-swirl 8 and save investment costs, and reduce the loss of flue gas pressure energy and improve the working efficiency of the flue gas machine 9.

[0036] A balance pipe 601 is connected between the external heat supply 6 and the regenerator 7 to maintain pressure balance between the external heat supply 6 and the regenerator 7.

[0037] Downstream of the flue gas generator 9, a waste heat boiler 10, a desulfurization and denitrification device 11, a flue gas dehydration device 12, and a carbon dioxide separator 13 are connected in sequence via pipelines. The regenerated flue gas that enters the flue gas generator 9 to perform work is discharged from the generator and then enters the waste heat boiler 10 for waste heat recovery, resulting in low-temperature flue gas. After being discharged from the waste heat boiler 10, the low-temperature flue gas enters the desulfurization and denitrification device 11 to remove sulfides and nitrates, thus purifying the flue gas. The purified flue gas then enters the flue gas dehydration device 12 to remove water. The dehydrated flue gas then enters the carbon dioxide separator 13 for separation. The outlet of the carbon dioxide separator 13 has two discharge branches, one of which connects to the gas mixing and heating tank 3, and the other connects to an external integrated utilization process (not shown in the figure).

[0038] The exhaust branch of the flue gas fan 9 is also equipped with a gas transmission pipeline 16. A control valve is installed on the gas transmission pipeline 16. The inlet end of the gas transmission pipeline 16 is connected to the upstream of the flue gas fan 9, and the outlet end is connected to the waste heat boiler 10. When no work is required on the flue gas fan 9, the regenerated flue gas purified by the three-cyclone 8 can be directly transported to the waste heat boiler 10 for waste heat recovery through the gas transmission pipeline 16.

[0039] Example 2

[0040] This invention also discloses a regenerator reheating method based on molten salt heating. This method is based on the regenerator reheating system of Example 1, and the specific method is as follows:

[0041] Salt is melted by the solar-powered molten salt field 507 and then fed into the molten salt fluidized bed 5.

[0042] Reactant raw materials are introduced into oxygen generator 1. When oxygen generator 1 is an air separator, the reactant raw material is air. The oxygen generated by the air separation is sent to oxygen compressor 2 for compression, and the nitrogen generated by the separation is sent to the ammonia synthesis unit. When oxygen generator 1 is a water electrolysis unit, the reactant raw material is water. The oxygen generated by the water electrolysis is sent to oxygen compressor 2 for compression, and the hydrogen generated by the water electrolysis is sent as fuel to auxiliary combustion chamber 4. The oxygen compressed by oxygen compressor 2 is sent to gas mixing and heating tank 3. After being heated by gas mixing and heating tank 3, it is divided into two parts. One part is sent to auxiliary combustion chamber 4 as the main air of auxiliary combustion chamber 4, and the other part is sent to regenerator 7 as the main air of regenerator 7. The hot flue gas generated by combustion in auxiliary combustion chamber 4 is sent to gas distributor 501 of molten salt fluidized bed 5 to exchange heat with molten salt in molten salt fluidized bed 5, thereby heating molten salt. Molten salt that reaches the required temperature is sent from the first molten salt outlet 502 to the tube side of external heat exchanger 6. The catalyst enters the shell side of the external heat exchanger 6 through the inlet pipe 603 and exchanges heat with the molten salt in the tube side. After heat exchange, the catalyst flows out through the outlet pipe 605 to the return pipe 704 and returns to the regenerator 7. The molten salt in the tube side of the external heat exchanger 6 returns to the molten salt fluidized bed 5 through the first molten salt loop. During this process, a portion of the molten salt to be heated in the molten salt fluidized bed 5 enters the solar molten salt field 507 through the second molten salt outlet 506, where solar energy is used to heat the molten salt. The heated molten salt then returns to the molten salt fluidized bed 5.

[0043] The regenerated flue gas from regenerator 7 is fed to the three-cyclone 8 for gas-solid separation. Part of the separated gas is used as fluidizing air to fluidize the catalyst entering the shell side of the external heat exchanger 6. Another part is used as transport air to transport the catalyst in the return pipe 704 back to regenerator 7. The third part undergoes cooling, desulfurization and denitrification, flue gas dehydration, and carbon dioxide separation. A portion of the separated carbon dioxide is recycled to the gas mixing and heating tank 3. Specifically, the regenerated flue gas from regenerator 7 is fed into the three-cyclone 8 for gas-solid separation. The separated regenerated flue gas is divided into two paths. One path is sent to the fluidizing flue gas compressor 15 for compression. The compressed regenerated flue gas is used as both fluidizing air and transport air. The fluidizing air enters the shell side of the external heat exchanger 6 to mix and fluidize the catalyst in the shell side, and then mixes with the tube side... The molten salt inside the tube exchanges heat, and the conveying air enters the return pipe 704, which sends the catalyst in the return pipe 704 into the regenerator 7. The regenerated flue gas after gas-solid separation by the three-swirl 8 enters the flue gas fan 9 to do work. The flue gas from the flue gas fan 9 enters the waste heat boiler 10 for waste heat recovery to obtain low-temperature flue gas. After exiting the waste heat boiler 10, the low-temperature flue gas enters the desulfurization and denitrification device 11. After the desulfurization and denitrification device 11 removes sulfides and nitrates from the flue gas, it enters the flue gas dehydration device 12 to remove water from the flue gas. The dehydrated flue gas enters the carbon dioxide separation device 13 to separate the carbon dioxide from the flue gas. Part of the carbon dioxide enters the gas mixing and heating tank 3 through the carbon dioxide compressor 14, and the other part goes to the carbon dioxide comprehensive utilization process.

[0044] Furthermore, in the initial stage of operation of the heating method and heating system described in this invention, if the amount of regenerated flue gas used as fluidizing air and conveying air is insufficient to maintain the operation of the system, external gas (such as water vapor) can be added as additional fluidizing air and conveying air. As the system operates, the amount of additional fluidizing air and conveying air added is gradually reduced. When the regenerated flue gas can fully meet the requirements of regenerated air and conveying air, the addition of additional fluidizing air and conveying air is stopped.

[0045] In the heat replenishment method of the present invention, the distribution ratio of the regenerated flue gas after separation by the three-swirl 8 into the fluidized flue gas compressor 15 and the flue gas fan 9, the distribution ratio of the regenerated flue gas discharged from the fluidized flue gas compressor 15 as the conveying air and fluidizing air, the distribution ratio of oxygen and carbon dioxide heated by the gas mixing heating tank 3 as the auxiliary combustion chamber main air and the regenerator main air, and the distribution ratio of carbon dioxide separated by the carbon dioxide separation device into the gas mixing heating tank 3 and the carbon dioxide comprehensive utilization process are not limited. It is only necessary to ensure that the corresponding fluidization, conveying, auxiliary combustion and other functions can be maintained and the normal operation of the system can be maintained.

[0046] In the heat exchange system provided by this invention, the molten salt and catalyst are indirectly heated through an external heat exchanger 6. During the heat exchange process, the catalyst and molten salt do not come into direct contact, so the entire process will not produce local overheating and the catalyst will not break down or become deactivated. The hot flue gas generated by combustion in the auxiliary combustion chamber 4 is introduced into the molten salt fluidized bed to heat the molten salt. The high-temperature water vapor contained in the hot flue gas will not come into contact with the catalyst and cause hydrothermal deactivation of the catalyst. After the catalyst is heated by the external heat exchanger 6, the temperature of the regenerated catalyst can reach the process requirements. At the same time, a portion of the separated carbon dioxide is sent to the gas mixing and heating tank 3. The carbon dioxide circulation and capture technology can increase the carbon dioxide concentration in the flue gas and achieve zero carbon dioxide emissions in the entire process. This invention can be applied to the construction of new plants, and it is also well applicable to old plants with insufficient combustion capacity.

[0047] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A regenerator supplementary heating system based on molten salt heating, characterized in that: It includes an external heat supply device (6) for supplementing heat to the regenerator (7), a molten salt fluidized bed (5), and a gas generation system for supplying heat to the molten salt fluidized bed (5). The external heat supply device (6) has a shell side and a tube side. The tube side of the external heat supply device (6) is connected to the molten salt fluidized bed (5), and the shell side is connected to the regenerator (7). The flue gas discharge pipe of the regenerator (7) is connected to a three-swirl (8). The exhaust pipe of the three-swirl (8) is divided into two exhaust branches at the end. One exhaust branch is connected to the flue gas fan (9). The other exhaust branch is divided into two exhaust branches after passing through the fluidized flue gas compressor (15). One exhaust branch is connected to the catalyst inlet of the regenerator (7), and the other exhaust branch is connected to the shell side of the external heat exchanger (6).

2. The regenerator supplementary heating system based on molten salt heating as described in claim 1, characterized in that: The gas generation system includes an oxygen generator (1), an oxygen compressor (2), a gas mixing and heating tank (3), and an auxiliary combustion chamber (4) connected in sequence. The auxiliary combustion chamber (4) is connected to a gas distributor (501) installed in the molten salt fluidized bed (5).

3. A regenerator supplementary heating system based on molten salt heating as described in claim 2, characterized in that: The heating gas delivery pipeline (302) of the gas mixing heating tank (3) is divided into two delivery branches. One delivery branch is connected to the auxiliary combustion chamber main air duct (401) of the auxiliary combustion chamber (4), and the other delivery branch is connected to the regenerator main air duct (703) of the regenerator (7).

4. A regenerator supplementary heating system based on molten salt heating as described in claim 1, characterized in that: The molten salt fluidized bed (5) is provided with a first molten salt outlet (502), a first molten salt circuit (503), a second molten salt outlet (506), a second molten salt circuit (508), and a molten salt fluidized bed flue gas discharge pipeline (504); The first molten salt outlet (502) is connected to the tube inlet of the external heatsink (6), and the tube outlet of the external heatsink (6) is connected to the first molten salt circuit (503); the second molten salt outlet (506) is connected to the feed inlet of the solar molten salt field (507), and the discharge outlet of the solar molten salt field (507) is connected to the second molten salt circuit (508); the end of the molten salt fluidized bed flue gas discharge pipeline (504) is connected to the exhaust pipeline of the three-swirl (8).

5. A regenerator supplementary heating system based on molten salt heating as described in claim 1, characterized in that: Downstream of the flue gas machine (9) are connected in sequence a waste heat boiler (10), a desulfurization and denitrification device (11), a flue gas dehydration device (12), and a carbon dioxide separation device (13). The outlet of the carbon dioxide separation device (13) is provided with two discharge branches, one of which is connected to the gas mixing heating tank (3), and the other is connected to the carbon dioxide comprehensive utilization process.

6. A regenerator supplementary heating system based on molten salt heating as described in claim 5, characterized in that: A carbon dioxide compressor (14) is installed on the discharge branch connecting the carbon dioxide separator (13) and the gas mixing and heating tank (3).

7. A regenerator supplementary heating system based on molten salt heating as described in claim 5, characterized in that: The exhaust branch of the flue gas machine (9) is provided with a gas transmission pipeline (16). The gas transmission pipeline (16) is connected to the upstream of the flue gas machine (9) and the gas outlet is connected to the waste heat boiler (10).

8. A regenerator supplementary heating system based on molten salt heating as described in claim 1, characterized in that: The regenerator (7) is connected to a return pipe (704) for the catalyst to return after reheating. One end of the return pipe (704) extends into the regenerator (7), and the other end is the catalyst inlet. The shell side of the external heatsink (6) is connected to an outlet pipe (605) for the catalyst to be discharged after reheating. The discharge port of the outlet pipe (605) is connected to the catalyst inlet.

9. A regenerator supplementary heating system based on molten salt heating as described in claim 1, characterized in that: A balance pipe (601) is connected between the external heat supply (6) and the regenerator (7).

10. A regenerator reheating method based on molten salt heating, characterized in that: This method employs the regenerator reheating system described in any one of claims 1-9: The molten salt in the molten salt fluidized bed (5) is transported to the tube side of the external heat exchanger (6), and the catalyst to be reheated in the regenerator (7) is transported to the shell side of the external heat exchanger (6). The catalyst in the shell side of the external heat exchanger (6) and the molten salt in the tube side exchange heat and then return to the regenerator (7). The regenerated flue gas from the regenerator (7) enters the three-cyclone (8) for gas-solid separation. Part of the separated gas is used as fluidizing air to fluidize the catalyst in the shell side of the external heat exchanger (6), and part of it is used as transport air to transport the heat-exchanged catalyst to the regenerator (7). After the third part is cooled, desulfurized and denitrified, dehydrated and separated by carbon dioxide, part of the separated carbon dioxide is recycled to the gas generation system of the molten salt fluidized bed (5), and the other part enters the carbon dioxide comprehensive utilization process.

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