System and method for concentrating carbon dioxide from catalytic cracking flue gas

Abstract

The invention relates to the field of catalytic cracking recycling, in particular to a system and a method for concentrating carbon dioxide from catalytic cracking flue gas. The system comprises a mixing part which comprises an oxygen production device, a main fan and a carbon dioxide-rich gas mixer, the oxygen production device is communicated with the carbon dioxide-rich gas mixer, and the main fan is communicated with the carbon dioxide-rich gas mixer; the regeneration part comprises a catalytic cracking regenerator, a separator, a flue gas turbine and a waste heat boiler, the catalytic cracking regenerator is communicated with the carbon dioxide-rich gas mixer and the separator, the separator is communicated with the flue gas turbine, and the flue gas turbine is communicated with the waste heat boiler; the flue gas treatment part sequentially comprises a flue gas cooler, a flue gas desulfurization and dust removal device and an overheating dehydration device; the overheating dehydration device is respectively communicated with the recycling part and the main fan; according to the system, the volume concentration of CO2 in (dry) flue gas can be increased to 96% or above.

Description

Technical Field

[0001] This application relates to the field of catalytic cracking cycle recycling, and particularly to a system and method for concentrating carbon dioxide from catalytic cracking flue gas. Background Art

[0002] The catalytic cracking unit is the largest carbon emission source in the refinery. A large amount of CO2 is generated during the catalyst burning process. Currently, the CO2 emissions of the catalytic cracking unit account for 20% - 35% of the refinery's carbon emissions, indicating that the catalytic cracking unit can be used as a single carbon emission point for catalytic cracking. Therefore, it is beneficial to implement carbon capture.

[0003] Currently, the main CO2 capture technologies include: chemical absorption, physical adsorption, chemical adsorption, and membrane separation, etc. However, due to the low CO2 concentration in the flue gas under conventional regeneration conditions, if the above methods are used for capture, there are high costs and great difficulties. A large amount of absorbent or adsorbent needs to be used, and waste liquid or solid waste needs to be discharged regularly, resulting in high operating costs for the overall method and being unfriendly to the environment. Summary of the Invention

[0004] This application provides a method for concentrating carbon dioxide from catalytic cracking flue gas to solve the disadvantages of high operating costs and environmental unfriendliness in the capture of CO2 in flue gas under conventional regeneration conditions in the prior art.

[0005] In a first aspect, this application provides a system for concentrating carbon dioxide from catalytic cracking flue gas, and the system includes:

[0006] A mixing section, the mixing section includes an oxygen generation device, a main blower, and a rich carbon dioxide gas mixer. The outlet of the oxygen generation device is connected to the inlet of the rich carbon dioxide gas mixer, and the outlet of the main blower is connected to the inlet of the rich carbon dioxide gas mixer;

[0007] A regeneration section, the regeneration section includes a catalytic cracking regenerator, a separator, a gas turbine, and a waste heat boiler. The feed port of the catalytic cracking regenerator is connected to the discharge port of the rich carbon dioxide gas mixer, the discharge port of the catalytic cracking regenerator is connected to the feed port of the separator, the discharge port of the separator is connected to the feed port of the gas turbine, and the discharge port of the gas turbine is connected to the feed port of the waste heat boiler;

[0008] A flue gas treatment section, the flue gas treatment section includes a flue gas cooler, a flue gas desulfurization and dust removal device, and a superheating and dehydration device. The feed port of the flue gas cooler is connected to the discharge port of the waste heat boiler, the discharge port of the flue gas cooler is connected to the feed port of the flue gas desulfurization and dust removal device, and the discharge port of the flue gas desulfurization and dust removal device is connected to the feed port of the superheating and dehydration device;

[0009] A recycling unit, the discharge port of the overheating dehydration device is respectively communicated with the feed port of the recycling unit and the feed port of the main blower.

[0010] Optionally, the overheating dehydration device includes a flue gas dehydrator and a flue gas superheater. The feed port of the flue gas dehydrator is communicated with the discharge port of the flue gas desulfurization and dust removal device. The discharge port of the flue gas dehydrator is communicated with the feed port of the flue gas superheater. The discharge port of the flue gas superheater is respectively communicated with the feed port of the recycling unit and the feed port of the main blower.

[0011] Optionally, the flue gas treatment unit further includes a hot water circulation pump. The liquid inlet of the hot water circulation pump is communicated with the liquid outlet of the flue gas superheater. The liquid outlet of the hot water circulation pump is communicated with the liquid inlet of the flue gas cooler. The liquid inlet of the flue gas superheater is communicated with the liquid outlet of the flue gas cooler.

[0012] Optionally, the recycling unit includes a chimney and a carbon dioxide recovery device. The feed port of the chimney, the feed port of the carbon dioxide recovery device and the feed port of the main blower are respectively communicated with the feed port of the flue gas superheater.

[0013] Optionally, the system further includes:

[0014] A valve pipeline group, the valve pipeline group includes an oxygen flow regulating valve group, a mixed gas flowmeter, a pressure control valve, a flue gas vent valve, a manual valve and an air inlet regulating valve. The oxygen flow regulating valve group is arranged at the air outlet of the oxygen generation device. The mixed gas flowmeter is arranged at the discharge port of the rich carbon dioxide gas mixer. The pressure control valve is arranged at the feed port of the carbon dioxide recovery device. The flue gas vent valve is arranged at the feed port of the chimney. The manual valve is arranged between the flue gas superheater and the main blower. The air inlet regulating valve is arranged at the air inlet of the main blower.

[0015] Optionally, the system further includes:

[0016] A control unit, the control unit includes a flue gas analyzer, a controller and a pressure gauge. The flue gas analyzer is arranged between the flue gas superheater and the main blower. The pressure gauge is arranged between the flue gas analyzer and the flue gas superheater. The controller is respectively connected with the main blower, the oxygen flow regulating valve group, the mixed gas flowmeter, the pressure control valve, the flue gas vent valve, the manual valve, the air inlet regulating valve, the flue gas analyzer and the pressure gauge through electric signals.

[0017] Optionally, the system satisfies:

[0018] m:n = 0 - 10%,

[0019] Wherein, m is the height of the discharge port of the carbon dioxide-rich gas mixer from the bottom of the catalytic cracking regenerator; n is the overall height of the catalytic cracking regenerator.

[0020] Optionally, the system further satisfies:

[0021] m:n = 40% - 60%,

[0022] Wherein, m is the height of the discharge port of the carbon dioxide-rich gas mixer from the bottom of the catalytic cracking regenerator; n is the overall height of the catalytic cracking regenerator.

[0023] In a second aspect, the present application provides a method for concentrating carbon dioxide from catalytic cracking flue gas. The method is adapted to the system described in the first aspect, and the method includes:

[0024] Mixing a combustion promoter and coke generated by catalytic cracking for combustion to obtain regenerated flue gas;

[0025] Separating dust, cooling, and desulfurizing and dust-removing the regenerated flue gas to obtain dust-removed regenerated flue gas;

[0026] Dehydrating and heating the dust-removed regenerated flue gas to obtain recycle gas and high-concentration carbon dioxide product gas respectively;

[0027] Wherein, the combustion promoter includes at least one of the following:

[0028] Air, oxygen, and recycle gas.

[0029] Optionally, the end temperature of the cooling is 110°C - 150°C, and the flue gas pressure drop during cooling is 0 - 1000 Pa.

[0030] Optionally, the end temperature of the dehydration is 10°C - 45°C, and the flue gas pressure drop during dehydration is 0 - 1000 Pa.

[0031] Optionally, the heating is carried out in a manner until it reaches the superheated state, and the end temperature of the heating is 20°C - 100°C.

[0032] The above technical solutions provided by the embodiments of the present application have the following advantages compared with the prior art:

[0033] A system for concentrating carbon dioxide from catalytic cracking flue gas provided by an embodiment of the present application, by introducing a mixing section including an oxygen production device, a main blower, and a rich carbon dioxide gas mixer, a regeneration section including a catalytic cracking regenerator, a separator, a flue gas turbine, and a waste heat boiler, a flue gas treatment section including a flue gas cooler, a flue gas desulfurization and dust removal device, and a superheating and dehydration device, and a recycling section. Oxygen can be introduced through the oxygen production device, and the main blower can introduce air or provide circulating power for the circulating gas, so that oxygen, air, or circulating gas can enter the rich carbon dioxide gas mixer for mixing to obtain a combustion-supporting agent. Then, through the catalytic cracking regenerator, the combustion-supporting agent reacts with the generated coke to obtain regenerated flue gas. Then, through the separator, part of the catalyst dust in the regenerated flue gas is removed from the regenerated flue gas. The gas kinetic energy generated is recovered by the flue gas turbine, and part of the heat energy of the regenerated flue gas is recovered by the waste heat boiler. Then, heat energy is further recovered through the flue gas cooler, and SO in the regenerated flue gas is removed through the flue gas desulfurization and dust removal device. x And catalyst dust, relatively pure carbon dioxide gas can be obtained. Finally, the moisture in the carbon dioxide gas is removed through the superheating and dehydration device, and the temperature of the carbon dioxide gas is increased, which facilitates the recovery of a part of the carbon dioxide gas through the recycling section, while most of the gas enters the system again through the main blower for enrichment, so that high-concentration carbon dioxide can be obtained; since the whole system can be sealed and circulated, it will not affect the environment to a certain extent, and the whole system can be locally modified based on the existing catalytic cracking device to obtain high-concentration carbon dioxide products, which can facilitate the downstream to capture carbon dioxide at a lower cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] The drawings here are incorporated into the specification and form a part of this specification, showing embodiments consistent with the present application, and are used together with the specification to explain the principles of the present application.

[0035] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, for those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0036] Figure 1 It is a schematic structural diagram of a system for concentrating carbon dioxide from catalytic cracking flue gas provided by an embodiment of the present application;

[0037] Figure 2 It is a schematic logical diagram of a system for concentrating carbon dioxide from catalytic cracking flue gas provided by an embodiment of the present application;

[0038] Figure 3Schematic flow diagram of a method for concentrating carbon dioxide from catalytic cracking flue gas provided by an embodiment of the present application;

[0039] Among them, 1 - oxygen generation device, 2 - main blower, 3 - rich carbon dioxide gas mixer, 4 - catalytic cracking regenerator, 5 - separator, 6 - gas turbine, 7 - waste heat boiler, 8 - flue gas cooler, 9 - flue gas desulfurization and dust removal device, 10 - superheating and dehydration device, 101 - flue gas dehydrator, 102 - flue gas superheater, 11 - hot water circulation pump, 12 - carbon dioxide recovery device, 13 - chimney, 14 - oxygen flow regulating valve group, 15 - mixed gas flowmeter, 16 - pressure control valve, 17 - flue gas vent valve, 18 - manual valve, 19 - air inlet regulating valve, 20 - flue gas analyzer, 21 - controller, 22 - pressure gauge. Detailed implementation manners

[0040] To make the objectives, technical solutions, and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are some, but not all, of the embodiments of the present application. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present application without creative efforts shall fall within the protection scope of the present application.

[0041] Unless otherwise specifically stated, all kinds of raw materials, reagents, instruments, and equipment used in the present application can be obtained through market purchases or can be prepared by existing methods.

[0042] As Figure 1 and Figure 2 shown, an embodiment of the present application provides a system for concentrating carbon dioxide from catalytic cracking flue gas, and the system includes:

[0043] A mixing section, the mixing section includes an oxygen generation device 1, a main blower 2, and a rich carbon dioxide gas mixer 3. The outlet of the oxygen generation device 1 is connected to the inlet of the rich carbon dioxide gas mixer 3, and the outlet of the main blower 2 is connected to the inlet of the rich carbon dioxide gas mixer 3;

[0044] A regeneration section, the regeneration section includes a catalytic cracking regenerator 4, a separator 5, a gas turbine 6, and a waste heat boiler 7. The feed port of the catalytic cracking regenerator 4 is connected to the discharge port of the rich carbon dioxide gas mixer 3, the discharge port of the catalytic cracking regenerator 4 is connected to the feed port of the separator 5, the discharge port of the separator 5 is connected to the feed port of the gas turbine 6, and the discharge port of the gas turbine 6 is connected to the feed port of the waste heat boiler 7;

[0045] Flue gas treatment section, the flue gas treatment section includes a flue gas cooler 8, a flue gas desulfurization and dust removal device 9, and a superheating and dehydration device 10. The feed port of the flue gas cooler 8 is connected to the discharge port of the waste heat boiler 7, the discharge port of the flue gas cooler 8 is connected to the feed port of the flue gas desulfurization and dust removal device 9, and the discharge port of the flue gas desulfurization and dust removal device 9 is connected to the feed port of the superheating and dehydration device 10;

[0046] Recycling section, the discharge port of the superheating and dehydration device 10 is respectively connected to the feed port of the recycling section and the feed port of the main blower 2.

[0047] It should be noted that a drainage package can be provided at the bottom of the flue gas cooler 8 to quickly discharge the cooling medium.

[0048] The flue gas cooler 8 can be a flue gas heat exchanger. When the flue gas flows through the equipment shell connected to the flue, the cooling medium or heating medium can exchange heat with the flue gas. At the same time, to improve the heat transfer coefficient, the flue gas heat exchanger can adopt a multi-tube bundle method, and a single group of heat exchange tubes can be disassembled and cut off.

[0049] To further improve the heat transfer coefficient, a plurality of fins are provided on the outer wall of each tube bundle of the multi-tube bundle.

[0050] The flue gas cooler 8 can adopt a pipe-inserted flue gas cooler 8, a plate flue gas cooler 8 or a shell-and-tube flue gas cooler 8.

[0051] When a pipe-inserted flue gas cooler 8 is adopted, the inserted heat exchange tubes can be smooth tubes, fin tubes or other extended surface tubes.

[0052] It should be noted that the separator 5 and the gas turbine 6 can be selected according to the specific model of the fluid catalytic cracking regenerator 4. Here, a common fluid catalytic cracking regenerator 4 is selected. Therefore, the separator 5 and the gas turbine 6 need to be matched to remove large particle catalyst dust in the regenerated flue gas by the separator 5, and then part of the kinetic energy recovered by using the regenerated flue gas to drive the gas turbine 6.

[0053] It should be noted that in order to completely remove large particle catalyst dust in the regenerated flue gas, the separator 5 can adopt a three-stage cyclone separator 5.

[0054] It should be noted that the flue gas desulfurization and dust removal device 9 can adopt a flue gas desulfurization and dust removal device 9 based on wet desulfurization and dust removal.

[0055] In some alternative embodiments, the overheating and dehydration device 10 includes a flue gas dehydrator 101 and a flue gas superheater 102. The feed inlet of the flue gas dehydrator 101 is connected to the discharge outlet of the flue gas desulfurization and dust removal device 9. The discharge outlet of the flue gas dehydrator 101 is connected to the feed inlet of the flue gas superheater 102. The discharge outlet of the flue gas superheater 102 is respectively connected to the feed inlet of the recycling and utilization section and the feed inlet of the main blower 2.

[0056] In the embodiments of the present application, by refining the composition of the overheating and dehydration device 10, the flue gas dehydrator 101 can be used to remove water vapor in the regenerated flue gas. At the same time, the flue gas superheater 102 is used to heat the regenerated flue gas, which can further make the temperature of the regenerated flue gas higher than the dew point, avoiding dew point corrosion of pipelines and equipment caused by the regenerated flue gas.

[0057] It should be noted that both the flue gas dehydrator 101 and the flue gas superheater 102 can adopt a flue gas heat exchanger. The flue gas heat exchanger can adopt a multi-tube bundle method, and a single group of heat exchange tubes is detachable and excisable. In order to improve the heat transfer coefficient, a plurality of fins can be arranged on the outer wall of each tube bundle of the multi-tube bundle.

[0058] The type of the flue gas superheater 102 can be a pipe insertion type, a plate type or a shell and tube type. When the pipe insertion type is adopted, the heat exchange tubes inserted in the flue gas dehydrator 101 can be smooth tubes, fin tubes or other extended surface tubes.

[0059] In some alternative embodiments, the flue gas treatment section further includes a hot water circulation pump 11. The liquid inlet of the hot water circulation pump 11 is connected to the liquid outlet of the flue gas superheater 102. The liquid outlet of the hot water circulation pump 11 is connected to the liquid inlet of the flue gas cooler 8. The liquid inlet of the flue gas superheater 102 is connected to the liquid outlet of the flue gas cooler 8.

[0060] In the embodiments of the present application, by designing the hot water circulation pump 11 and defining the connection method between the flue gas superheater 102 and the flue gas cooler 8, the hot water circulation pump 11 can be used to realize the hot water flow between the flue gas superheater 102 and the flue gas cooler 8. By connecting the water outlet of the flue gas cooler 8 to the water inlet of the flue gas superheater 102, the heat of the regenerated flue gas can be transferred to the flue gas superheater 102 through the flue gas cooler 8, and the dehydrated regenerated flue gas can be heated and raised in temperature. The heat-exchanged water can be used as a cooling medium and returned to the flue gas cooler 8 through the hot water circulation pump 11, thereby forming a closed loop of the hot water system and achieving the purpose of energy saving.

[0061] It should be noted that in order to ensure the tightness of the closed loop of the hot water system, the heat exchange tubes of the flue gas superheater 102 and the heat exchange tubes of the flue gas cooler 8 are directly butted.

[0062] To ensure the dehydration effect of the flue gas dehydrator 101, the inlet of the heat exchange tubes in the flue gas dehydrator 101 is connected to the external circulating cold water pipeline, and at the same time, the outlet of the heat exchange tubes is connected to the external circulating hot water pipeline.

[0063] In some alternative embodiments, the recycling unit includes a chimney 13 and a carbon dioxide recovery device 12. The feed inlet of the chimney 13, the feed inlet of the carbon dioxide recovery device 12, and the feed inlet of the main blower 2 are respectively connected to the feed inlet of the flue gas superheater 102.

[0064] In the embodiments of the present application, by refining the specific structure of the recycling unit, the venting of the gas in the entire system can be achieved through the chimney 13, and the oxygen in the oxygen production device 1 can gradually displace the air introduced by the main blower 2, while the high-concentration carbon dioxide can be fully recovered by the carbon dioxide recovery device 12.

[0065] In some alternative embodiments, the system further includes:

[0066] A valve pipeline group, which includes an oxygen flow regulating valve group 14, a mixed gas flow meter 15, a pressure control valve 16, a flue gas vent valve 17, a manual valve 18, and an air inlet regulating valve 19. The oxygen flow regulating valve group 14 is arranged at the outlet of the oxygen production device 1, the mixed gas flow meter 15 is arranged at the outlet of the carbon dioxide-rich gas mixer 3, the pressure control valve 16 is arranged at the feed inlet of the carbon dioxide recovery device 12, the flue gas vent valve 17 is arranged at the feed inlet of the chimney 13, the manual valve 18 is arranged between the flue gas superheater 102 and the main blower 2, and the air inlet regulating valve 19 is arranged at the air inlet of the main blower 2.

[0067] In the embodiments of the present application, by refining the specific composition of the valve pipeline group, first, the air inlet regulating valve 19 is used to enable the main blower 2 to suck in the air from the atmosphere, and enter the catalytic cracking regenerator 4 through the mixed gas flow meter 15 for reaction to generate regenerated flue gas. The energy of the regenerated flue gas is recovered through the flue gas turbine 6 and the waste heat boiler 7, and then the desulfurization, dust removal, and dehydration of the regenerated flue gas are realized through the flue gas treatment unit. The manual valve 18 and the pressure control valve 16 are closed, and the preliminarily circulated regenerated flue gas is discharged from the system through the flue gas vent valve 17. After the catalytic cracking regenerator 4 operates stably, the oxygen flow regulating valve group 14 and the manual valve 18 are opened wider and the air inlet regulating valve 19 is adjusted smaller. While reducing the air flow, the oxygen flow and the flue gas flow into the main blower 2 can be increased. When the air is slowly replaced by oxygen and the circulated regenerated flue gas, the carbon dioxide concentration at the outlet of the catalytic cracking regenerator 4 can be increased. At this time, the flue gas vent valve 17 is closed and the pressure control valve 16 is opened to enable the high-concentration carbon dioxide to enter the carbon dioxide recovery device 12.

[0068] In some alternative embodiments, the system further includes:

[0069] A control unit, which includes a flue gas analyzer 20, a controller 21, and a pressure gauge 22. The flue gas analyzer 20 is disposed between the flue gas superheater 102 and the main blower 2. The pressure gauge 22 is disposed between the flue gas analyzer 20 and the flue gas superheater 102. The controller 21 is electrically connected to the main blower 2, the oxygen flow regulating valve group 14, the mixed gas flowmeter 15, the pressure control valve 16, the flue gas vent valve 17, the manual valve 18, the air inlet regulating valve 19, the flue gas analyzer 20, and the pressure gauge 22 through electrical signals.

[0070] In the embodiments of the present application, by introducing the flue gas analyzer 20 into the system, the components of the regenerated flue gas can be specifically analyzed, and the analysis data of the regenerated flue gas is transmitted to the PLC of the controller 21 through electrical signals for processing. At the same time, the pressure gauge 22 collects the gas pressure data and transmits it to the PLC of the controller 21 through electrical signals for processing. The mixed gas flowmeter 15 can collect the specific flow data of the mixed gas and transmit it to the PLC of the controller 21 for processing, and the oxygen flow regulating valve group 14 can also collect the specific flow data of oxygen and transmit it to the PLC of the controller 21 for processing. The controller 21 adjusts the oxygen flow regulating valve group 14, the mixed gas flowmeter 15, the pressure control valve 16, the flue gas vent valve 17, and the air inlet regulating valve 19 in real time according to the collected data to ensure the automatic, safe, and efficient operation of the overall system.

[0071] It should be noted that the controller 21 can adopt a Siemens s7-300 type processor, and the flue gas analyzer 20 can be a Jukuang CEMS-2000 or Xuedilong SCS-900X type flue gas analyzer.

[0072] In some alternative embodiments, the system satisfies:

[0073] m:n = 0 to 10%,

[0074] where m is the height of the discharge port of the carbon dioxide-rich gas mixer 3 from the bottom of the catalytic cracking regenerator 4; n is the overall height of the catalytic cracking regenerator 4.

[0075] In the embodiments of the present application, the specific height ratio of the discharge port of the carbon dioxide-rich gas mixer 3 in the system is defined. Since this height ratio is in the bottom area relative to the catalytic cracking regenerator 4, the coke generated by catalytic cracking in the catalytic cracking regenerator 4 can be blown up by the mixed gas for reaction, so as to obtain enough regenerated flue gas.

[0076] In some alternative embodiments, the system further satisfies:

[0077] m:n = 40% to 60%,

[0078] wherein, m is the height of the outlet of the carbon dioxide-rich gas mixer 3 from the bottom of the catalytic cracking regenerator 4; n is the overall height of the catalytic cracking regenerator 4.

[0079] In the embodiments of the present application, the specific height ratio of the outlet of the carbon dioxide-rich gas mixer 3 in the system is defined. Since this height ratio is in the middle region relative to the catalytic cracking regenerator 4, the mixed gas can react with the coke generated by catalytic cracking in the catalytic cracking regenerator 4 to obtain sufficient regeneration flue gas.

[0080] As Figure 3 shown, based on a general inventive concept, the embodiments of the present application provide a method for concentrating carbon dioxide from catalytic cracking flue gas. The method is adapted to the system, and the method includes:

[0081] S1. Mixing a combustion aid and the coke generated by catalytic cracking for combustion to obtain regeneration flue gas;

[0082] S2. Separating dust, cooling, and desulfurizing and dust-removing the regeneration flue gas to obtain dust-removed regeneration flue gas;

[0083] S3. Dehydrating and heating the dust-removed regeneration flue gas to obtain recycle gas and high-concentration carbon dioxide product gas respectively;

[0084] wherein, the combustion aid includes at least one of the following:

[0085] Air, oxygen, and recycle gas.

[0086] This method is implemented based on the above system. The specific structure of the system can refer to the above embodiments. Since this method adopts some or all of the technical solutions of the above embodiments, it at least has all the beneficial effects brought by the technical solutions of the above embodiments, which will not be elaborated herein one by one.

[0087] It should be noted that the combustion aid can be air, oxygen, or recycle gas, or a mixture of air and oxygen, or a mixture of air and recycle gas, or a mixture of oxygen and recycle gas, or a mixture of air, oxygen, and recycle gas. Considering the actual situation comprehensively, the best combination is a mixture of air, oxygen, and recycle gas or a mixture of oxygen and recycle gas.

[0088] In some alternative embodiments, the end temperature of the cooling is 110°C to 150°C, and the flue gas pressure drop during the cooling is 0 to 1000 Pa.

[0089] In the embodiments of the present application, by defining the specific end temperature and the specific flue gas pressure drop for cooling, the heat in the regenerated flue gas can be fully recovered, facilitating subsequent heating.

[0090] The end temperature of the cooling can be 110°C, 115°C, 120°C, 125°C, 130°C, 135°C, 140°C, 145°C or 150°C.

[0091] The flue gas pressure drop of the cooling can be 0 Pa, 100 Pa, 200 Pa, 300 Pa, 400 Pa, 500 Pa, 600 Pa, 700 Pa, 800 Pa, 900 Pa or 1000 Pa.

[0092] In some alternative embodiments, the end temperature of the dehydration is 10°C to 45°C, and the flue gas pressure drop of the dehydration is 0 to 1000 Pa.

[0093] In the embodiments of the present application, by defining the specific end temperature and the specific flue gas pressure drop for dehydration, the moisture in the regenerated flue gas can be fully removed, facilitating subsequent heating.

[0094] The end temperature of the dehydration can be 10°C, 15°C, 20°C, 25°C, 30°C, 35°C, 40°C or 45°C.

[0095] The flue gas pressure drop of the dehydration can be 0 Pa, 100 Pa, 200 Pa, 300 Pa, 400 Pa, 500 Pa, 600 Pa, 700 Pa, 800 Pa, 900 Pa or 1000 Pa.

[0096] In some alternative embodiments, the heating is performed in a manner that heats the regenerated flue gas to a superheated state, and the end temperature of the heating is 20°C to 100°C.

[0097] In the embodiments of the present application, by defining the specific heating method and the specific temperature of the heating, the regenerated flue gas can reach a relatively high temperature, which can not only prevent dew point corrosion of equipment and pipelines, but also facilitate the utilization of the subsequent recycled regenerated flue gas.

[0098] The end temperature of the heating can be 20°C, 25°C, 30°C, 35°C, 40°C, 45°C, 50°C, 55°C, 60°C, 65°C, 70°C, 75°C, 80°C, 85°C, 90°C, 95°C or 100°C.

[0099] The present application will be further described below in conjunction with specific embodiments. It should be understood that these embodiments are only used to illustrate the present application and not to limit the scope of the present application. The experimental methods without specific conditions noted in the following embodiments are generally determined according to industry standards. If there is no corresponding industry standard, they are carried out according to general international standards, conventional conditions, or the conditions recommended by the manufacturer.

[0100] Embodiment 1

[0101] As Figure 1 and Figure 2 shown, a system for concentrating carbon dioxide from catalytic cracking flue gas, the system includes:

[0102] A mixing section, the mixing section includes an oxygen production device 1, a main blower 2 and a rich carbon dioxide gas mixer 3. The outlet of the oxygen production device 1 is connected to the inlet of the rich carbon dioxide gas mixer 3, and the outlet of the main blower 2 is connected to the inlet of the rich carbon dioxide gas mixer 3;

[0103] A regeneration section, the regeneration section includes a catalytic cracking regenerator 4, a separator 5, a flue gas turbine 6 and a waste heat boiler 7. The feed port of the catalytic cracking regenerator 4 is connected to the discharge port of the rich carbon dioxide gas mixer 3, the discharge port of the catalytic cracking regenerator 3 is connected to the feed port of the separator 5, the discharge port of the separator 5 is connected to the feed port of the flue gas turbine 6, and the discharge port of the flue gas turbine 6 is connected to the feed port of the waste heat boiler 7;

[0104] A flue gas treatment section, the flue gas treatment section includes a flue gas cooler 8, a flue gas desulfurization and dust removal device 9 and a superheating and dehydration device 10. The feed port of the flue gas cooler 8 is connected to the discharge port of the waste heat boiler 7, the discharge port of the flue gas cooler 8 is connected to the feed port of the flue gas desulfurization and dust removal device 9, and the discharge port of the flue gas desulfurization and dust removal device 9 is connected to the feed port of the superheating and dehydration device 10;

[0105] A recycling section, the discharge port of the superheating and dehydration device 10 is respectively connected to the feed port of the recycling section and the feed port of the main blower 2.

[0106] The superheating and dehydration device 10 includes a flue gas dehydrator 101 and a flue gas superheater 102. The feed port of the flue gas dehydrator 101 is connected to the discharge port of the flue gas desulfurization and dust removal device 9, the discharge port of the flue gas dehydrator 101 is connected to the feed port of the flue gas superheater 102, and the discharge port of the flue gas superheater 102 is respectively connected to the feed port of the recycling section and the feed port of the main blower 2.

[0107] The flue gas treatment section further includes a hot water circulation pump 11. The liquid inlet of the hot water circulation pump 11 is connected to the liquid outlet of the flue gas superheater 102, the liquid outlet of the hot water circulation pump 11 is connected to the liquid inlet of the flue gas cooler 8, and the liquid inlet of the flue gas superheater 102 is connected to the liquid outlet of the flue gas cooler 8.

[0108] The recycling unit includes a chimney 13 and a carbon dioxide recovery device 12. The feed inlet of the chimney 13, the feed inlet of the carbon dioxide recovery device 12, and the feed inlet of the main blower 2 are respectively connected to the feed inlet of the flue gas superheater 102.

[0109] The system further includes:

[0110] A valve pipeline group, which includes an oxygen flow regulating valve group 14, a mixed gas flowmeter 15, a pressure control valve 16, a flue gas vent valve 17, a manual valve 18, and an air inlet regulating valve 19. The oxygen flow regulating valve group 14 is arranged at the gas outlet of the oxygen production device 1. The mixed gas flowmeter 15 is arranged at the discharge port of the carbon dioxide-rich gas mixer 3. The pressure control valve 16 is arranged at the feed inlet of the carbon dioxide recovery device 12. The flue gas vent valve 17 is arranged at the feed inlet of the chimney 13. The manual valve 18 is arranged between the flue gas superheater 102 and the main blower 2. The air inlet regulating valve 19 is arranged at the air inlet of the main blower 2.

[0111] The system further includes:

[0112] A control unit, which includes a flue gas analyzer 20, a controller 21, and a pressure gauge 22. The flue gas analyzer 20 is arranged between the flue gas superheater 102 and the main blower 2. The pressure gauge 22 is arranged between the flue gas analyzer 20 and the flue gas superheater 102. The controller 21 is electrically connected to the main blower 2, the oxygen flow regulating valve group 14, the mixed gas flowmeter 15, the pressure control valve 16, the flue gas vent valve 17, the manual valve 18, the air inlet regulating valve 19, the flue gas analyzer 20, and the pressure gauge 22 respectively through electrical signals.

[0113] The system satisfies:

[0114] m:n = 0 - 10%,

[0115] where m is the height from the discharge port of the carbon dioxide-rich gas mixer 3 to the bottom of the catalytic cracking regenerator 4; n is the overall height of the catalytic cracking regenerator 4.

[0116] The system also satisfies:

[0117] m:n = 40% - 60%,

[0118] where m is the height from the discharge port of the carbon dioxide-rich gas mixer 3 to the bottom of the catalytic cracking regenerator 4; n is the overall height of the catalytic cracking regenerator 4.

[0119] In the above system, the oxygen outlet of the oxygen generation device 1 and the outlet of the main blower 2 are both connected to the inlet of the carbon dioxide-rich gas mixer 3, and the outlet of the carbon dioxide-rich gas mixer 3 is connected to the bottom or middle part of the catalytic cracking regenerator 4. An oxygen flow regulating valve group 14 is provided on the oxygen pipeline of the oxygen generation device 1. The flue gas outlet at the top of the catalytic cracking regenerator 4 is connected to the inlet of the three-stage cyclone separator 5, and the outlet of the three-stage cyclone separator 5 is connected to the inlet of the gas turbine 6. The outlet of the gas turbine 6, the waste heat boiler 7, the flue gas cooler 8, the wet flue gas desulfurization and dust removal device 9, the flue gas dehydrator 101, and the flue gas superheater 102 are connected in sequence. At the same time, the outlet of the flue gas superheater 102 is connected to the inlet of the main blower 2, the inlet of the chimney 13, and the downstream carbon dioxide recovery device 12 respectively.

[0120] The working process of this system is to return a part of the flue gas generated by the catalytic cracking regenerator 4 to the inlet of the main blower 2 after treatment, and use oxygen instead of air as the combustion aid to achieve the purpose of increasing the carbon dioxide concentration in the discharged flue gas. The specific process is as follows:

[0121] When the catalytic cracking regenerator 4 starts to operate, the main blower 2 is used to suck air from the atmosphere and use this air as the combustion aid. The air volume is controlled by the air inlet regulating valve 19. Combustion occurs in the catalytic cracking regenerator 4 to generate regenerated flue gas. First, part of the larger particle catalyst dust is removed by the three-stage cyclone separator 5, and then it enters the gas turbine 6, the waste heat boiler 7, and the flue gas cooler 8 to recover the pressure energy and heat energy of the regenerated flue gas respectively. Then, the SO x and catalyst dust in the flue gas are removed by the wet flue gas desulfurization-based flue gas desulfurization and dust removal device 9. The saturated regenerated flue gas passing through the flue gas desulfurization and dust removal device 9 is dehydrated and heated up by the flue gas dehydrator 101 and the flue gas superheater 102 respectively to prevent dew point corrosion of the equipment. Then, the regenerated flue gas is discharged to the chimney through the flue gas vent valve 17. At this time, both the pressure control valve 16 and the manual valve 18 are in the closed state.

[0122] After the catalytic cracking regenerator 4 operates stably, gradually close the air inlet regulating valve 19, and at the same time open the oxygen flow regulating valve group 14 on the oxygen pipeline and the manual valve 18 on the pipeline where the regenerated flue gas of the regeneration cycle enters the inlet of the main blower 2, so as to reduce the air flow while increasing the oxygen flow and the flow of the regenerated flue gas of the regeneration cycle entering the main blower 2; when the air is slowly replaced by oxygen and the regenerated flue gas of the regeneration cycle, the carbon dioxide concentration in the outlet flue gas of the catalytic cracking regenerator 4 is increased. At this time, close the flue gas vent valve 17 on the pipeline of the vent chimney 13, and open the pressure control valve 16 on the pipeline leading to the downstream carbon dioxide recovery device 12, so that a part of the regenerated flue gas with high-concentration carbon dioxide is sent to the downstream carbon dioxide recovery device 12, and most of the flue gas with high carbon dioxide concentration is recycled back to the inlet of the main blower 2, and after being mixed with oxygen through the carbon dioxide-rich gas mixer 3, it is used as the combustion-supporting agent of the catalytic cracking regenerator 4 again. Through this cycle, high-concentration carbon dioxide is finally obtained.

[0123] In this system, the cold source of the flue gas dehydrator 101 is supplied by external circulating cooling water or other coolants. The heat source of the flue gas superheater 102 is supplied by the heat recovered by the flue gas cooler 8 through the hot water circulation pump 11 in a cycle.

[0124] The controller 21 processes the data signals from the mixed gas flowmeter 15, the flue gas analyzer 20, the pressure gauge 22 and each valve to ensure the automatic and safe operation of the concentration improvement system.

[0125] Example 2

[0126] Based on the system disclosed in Example 1, the operation method is as follows:

[0127] As Figure 3 shown, a method for concentrating carbon dioxide from catalytic cracking flue gas includes:

[0128] S1. Mix the combustion-supporting agent and the coke generated by catalytic cracking to carry out combustion to obtain regenerated flue gas;

[0129] S2. Separate dust, cool down and desulfurize and remove dust from the regenerated flue gas to obtain dust-removed regenerated flue gas;

[0130] S3. Dehydrate and heat the dust-removed regenerated flue gas to obtain circulating gas and high-concentration carbon dioxide product gas respectively;

[0131] Among them, the combustion-supporting agent includes at least one of the following:

[0132] Air, oxygen and circulating gas.

[0133] The end temperature of the cooling is 120 °C, and the pressure drop of the flue gas during cooling is 500 Pa.

[0134] The end temperature of dehydration is 35 °C, and the flue gas pressure drop during dehydration is 500 Pa.

[0135] Heating is carried out in such a way that it is heated to a superheated state, and the end temperature of heating is 50 °C.

[0136] Example 3

[0137] Comparing Example 3 with Example 2, the differences between Example 3 and Example 2 are as follows:

[0138] The end temperature of cooling is 110 °C, and the flue gas pressure drop during cooling is 10 Pa.

[0139] The end temperature of dehydration is 10 °C, and the flue gas pressure drop during dehydration is 10 Pa.

[0140] Heating is carried out in such a way that it is heated to a superheated state, and the end temperature of heating is 20 °C.

[0141] Example 4

[0142] Comparing Example 4 with Example 2, the differences between Example 4 and Example 2 are as follows:

[0143] The end temperature of cooling is 150 °C, and the flue gas pressure drop during cooling is 1000 Pa.

[0144] The end temperature of dehydration is 45 °C, and the flue gas pressure drop during dehydration is 1000 Pa.

[0145] Heating is carried out in such a way that it is heated to a superheated state, and the end temperature of heating is 100 °C.

[0146] Relevant experiments and effect data:

[0147] Through the system of Example 1, using the coke generated by catalytic cracking in the catalytic cracker regenerator 4, the obtained high-concentration carbon dioxide ≥ 96%.

[0148] The high-concentration carbon dioxide obtained in Example 2 ≥ 96.3%.

[0149] The high-concentration carbon dioxide obtained in Example 3 ≥ 97%.

[0150] In summary, a system for concentrating carbon dioxide from catalytic cracking flue gas provided by an embodiment of the present application introduces a mixing section including an oxygen production device 1, a main blower 2, and a rich carbon dioxide gas mixer 3, a regeneration section including a catalytic cracking regenerator 4, a separator 5, a gas turbine 6, and a waste heat boiler 7, a flue gas treatment section including a flue gas cooler 8, a flue gas desulfurization and dust removal device 9, and a superheating and dehydration device 10, and a recovery and utilization section, so that the regenerated flue gas generated by the catalytic cracking regenerator 4 is desulfurized, dust-removed, and water-treated and then recycled back to the regenerator 4, increasing the volume concentration of CO2 in the (dry) flue gas to more than 96%, and reducing the capture cost of CO2 downstream.

[0151] At the same time, the flue gas superheater 102 of the system utilizes heat with the flue gas cooler 8 through a closed hot water circulation system, reducing the overall operating energy consumption of the system.

[0152] And the system introduces a flue gas dehydrator 101 to remove some moisture in the recycled flue gas, so as to ensure that the water content of the flue gas in the catalytic cracking regenerator 4 is adjustable, preventing excessive water content in the flue gas from causing thermal collapse of the catalyst in the catalytic cracking regenerator 4 and resulting in catalyst loss.

[0153] Various embodiments of the present application may exist in the form of a range; it should be understood that the description in the form of a range is only for convenience and brevity and should not be construed as a rigid limitation on the scope of the present application; therefore, it should be considered that the described range description has specifically disclosed all possible sub-ranges and single values within that range. For example, it should be considered that the range description from 1 to 6 has specifically disclosed sub-ranges such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., and single numbers within the range, such as 1, 2, 3, 4, 5, and 6, which applies regardless of the range. Additionally, whenever a numerical range is indicated herein, it means including any cited number (fraction or integer) within the indicated range.

[0154] In this application, unless otherwise stated, the orientation terms such as "upper" and "lower" specifically refer to the drawing directions in the attached drawings. Additionally, in the description of the specification of this application, the terms "include", "comprise", etc. mean "include but not limited to". In this text, relational terms such as "first" and "second" are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. In this text, "and / or" describes the association relationship of associated objects and indicates that three relationships can exist. For example, A and / or B can mean: A exists alone, A and B exist simultaneously, and B exists alone. Where A and B can be singular or plural. In this text, "at least one" means one or more, and "a plurality" means two or more. "At least one kind", "at least one (item) of the following" or similar expressions refer to any combination of these items, including any combination of single item (s) or plural items (s). For example, "at least one (item) of a, b, or c", or, "at least one (item) of a, b, and c" can both mean: a, b, c, a - b (i.e., a and b), a - c, b - c, or a - b - c, where a, b, and c can be single or multiple respectively.

[0155] The above description is only the specific implementation manners of this application, enabling those skilled in the art to understand or implement this application. Various modifications to these embodiments will be obvious to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of this application. Therefore, this application will not be limited to these embodiments shown herein, but rather will conform to the broadest scope consistent with the principles and novel features claimed herein.

Claims

1. A system for concentrating carbon dioxide from catalytic cracking flue gas, characterized in that, The system includes: A mixing section, the mixing section includes an oxygen generation device (1), a main blower (2) and a rich carbon dioxide gas mixer (3). The outlet of the oxygen generation device (1) is connected to the inlet of the rich carbon dioxide gas mixer (3), and the outlet of the main blower (2) is connected to the inlet of the rich carbon dioxide gas mixer (3); A regeneration section, the regeneration section includes a catalytic cracking regenerator (4), a separator (5), a gas turbine (6) and a waste heat boiler (7). The feed inlet of the catalytic cracking regenerator (4) is connected to the discharge outlet of the rich carbon dioxide gas mixer (3), the discharge outlet of the catalytic cracking regenerator (4) is connected to the feed inlet of the separator (5), the discharge outlet of the separator (5) is connected to the feed inlet of the gas turbine (6), and the discharge outlet of the gas turbine (6) is connected to the feed inlet of the waste heat boiler (7); A flue gas treatment section, the flue gas treatment section includes a flue gas cooler (8), a flue gas desulfurization and dust removal device (9) and a superheating and dehydration device (10). The feed inlet of the flue gas cooler (8) is connected to the discharge outlet of the waste heat boiler (7), the discharge outlet of the flue gas cooler (8) is connected to the feed inlet of the flue gas desulfurization and dust removal device (9), and the discharge outlet of the flue gas desulfurization and dust removal device (9) is connected to the feed inlet of the superheating and dehydration device (10); A recycling section, the discharge outlet of the superheating and dehydration device (10) is respectively connected to the feed inlet of the recycling section and the feed inlet of the main blower (2).

2. The system according to claim 1, wherein The superheating and dehydration device (10) includes a flue gas dehydrator (101) and a flue gas superheater (102). The feed inlet of the flue gas dehydrator (101) is connected to the discharge outlet of the flue gas desulfurization and dust removal device (9), the discharge outlet of the flue gas dehydrator (101) is connected to the feed inlet of the flue gas superheater (102), and the discharge outlet of the flue gas superheater (102) is respectively connected to the feed inlet of the recycling section and the feed inlet of the main blower (2).

3. The system according to claim 2, wherein The flue gas treatment section further includes a hot water circulation pump (11). The liquid inlet of the hot water circulation pump (11) is connected to the liquid outlet of the flue gas superheater (102), the liquid outlet of the hot water circulation pump (11) is connected to the liquid inlet of the flue gas cooler (8), and the liquid inlet of the flue gas superheater (102) is connected to the liquid outlet of the flue gas cooler (8).

4. The system according to claim 2, wherein The recycling section includes a chimney (13) and a carbon dioxide recovery device (12). The feed inlet of the chimney (13), the feed inlet of the carbon dioxide recovery device (12) and the feed inlet of the main blower (2) are respectively connected to the feed inlet of the flue gas superheater (102).

5. The system according to claim 4, characterized in that, The system further includes: Valve pipeline group, the valve pipeline group includes an oxygen flow regulating valve group (14), a mixed gas flow meter (15), a pressure control valve (16), a flue gas vent valve (17), a manual valve (18) and an air inlet regulating valve (19). The oxygen flow regulating valve group (14) is arranged at the outlet of the oxygen generation device (1). The mixed gas flow meter (15) is arranged at the outlet of the rich carbon dioxide gas mixer (3). The pressure control valve (16) is arranged at the inlet of the carbon dioxide recovery device (12). The flue gas vent valve (17) is arranged at the inlet of the chimney (13). The manual valve (18) is arranged between the flue gas superheater (102) and the main blower (2). The air inlet regulating valve (19) is arranged at the inlet of the main blower (2).

6. The system according to claim 5, wherein The system further includes: A control unit, the control unit includes a flue gas analyzer (20), a controller (21) and a pressure gauge (22). The flue gas analyzer (20) is arranged between the flue gas superheater (102) and the main blower (2). The pressure gauge (22) is arranged between the flue gas analyzer (20) and the flue gas superheater (102). The controller (21) is electrically connected to the main blower (2), the oxygen flow regulating valve group (14), the mixed gas flow meter (15), the pressure control valve (16), the flue gas vent valve (17), the manual valve (18), the air inlet regulating valve (19), the flue gas analyzer (20) and the pressure gauge (22) respectively through electrical signals.

7. The system according to claim 1, characterized in that, The system satisfies: m:n = 0 - 10%, wherein, m is the bottom height of the catalytic cracking regenerator (4) from the outlet of the rich carbon dioxide gas mixer (3); n is the overall height of the catalytic cracking regenerator (4).

8. The system according to claim 1, characterized in that, The system also satisfies: m:n = 40% - 60%, wherein, m is the bottom height of the catalytic cracking regenerator (4) from the outlet of the rich carbon dioxide gas mixer (3); n is the overall height of the catalytic cracking regenerator (4).

9. A method for concentrating carbon dioxide from catalytic cracking flue gas, characterized in that, The method is adapted to the system according to any one of claims 1 - 8. The method includes: Mixing a combustion improver and coke generated by catalytic cracking for combustion to obtain regenerated flue gas; Separating dust, cooling and desulfurizing and dust removing the regenerated flue gas to obtain dust-removed regenerated flue gas; Dehydrating and heating the dust-removed regenerated flue gas to obtain recycle gas and high-concentration carbon dioxide product gas respectively; Wherein, the combustion improver includes at least one of the following: Air, oxygen and recycle gas.

10. The method according to claim 9, wherein The end temperature of the cooling is 110°C - 150°C, and the flue gas pressure drop during cooling is 0 - 1000 Pa.

11. The method according to claim 9, wherein The end temperature of the dehydration is 10°C - 45°C, and the flue gas pressure drop during dehydration is 0 - 1000 Pa.

12. The method according to claim 9, wherein The heating is carried out in a way to heat to the superheated state, and the end temperature of the heating is 20°C - 100°C.

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