A carbon dioxide capture system for an oxy-combustion boiler coupled to an air separation unit

Abstract

The application discloses a kind of oxygen-enriched combustion boiler carbon dioxide collection systems coupled air separation unit, including flue gas treatment device, desublimator, subcooler, liquefied pressure chamber, heat exchanger and other equipment.The low-temperature oxygen prepared by air separation unit makes carbon dioxide desublime as easy-to-store dry ice, and the dry ice is used to obtain liquid carbon dioxide for transportation by sublimation;Condensed water is introduced to cool compressed air between stages, and dry ice, liquid oxygen and low-temperature nitrogen obtained by rectification are used to reduce the temperature of compressed air, so as to realize the coupling of boiler and air separation unit and reduce the energy consumption of air separation equipment;In addition, oxygen used for carbon dioxide desublimation is introduced into the refrigeration system to realize external cooling by using its residual cold energy.

Description

Technical Field

[0001] This invention relates to the field of industrial waste gas treatment technology, specifically to a carbon dioxide collection system for an oxygen-enriched combustion boiler coupled with an air separation device. Background Technology

[0002] The high cost of carbon dioxide collection is a major factor limiting the large-scale application of carbon dioxide collection technologies. Therefore, reducing the cost of carbon dioxide collection has become an important research direction for low-carbon production.

[0003] Oxygen-enriched combustion boilers use a mixture of oxygen and carbon dioxide as a combustion aid. Compared to traditional boilers, their exhaust gas has a very high concentration of carbon dioxide. Existing patents mainly use low-temperature sublimation / liquefaction methods to collect carbon dioxide, but few technologies apply the cooling capacity of oxygen to the carbon dioxide collection process. Patent 1—"An Oxygen-Enriched Combustion Exhaust Gas Treatment System Using Low-Temperature Sublimation"—utilizes low-temperature nitrogen gas prepared by an air separation unit to sublimate carbon dioxide into dry ice, which is then placed in a sealed chamber. The dry ice sublimates in the sealed chamber, increasing the pressure and thus obtaining liquid carbon dioxide. However, the opening and closing of the sealing plate will cause leakage in the sealed chamber, resulting in a decrease in the carbon dioxide liquefaction rate. In addition, air separation units typically use compressors to compress air and then refrigerate it to liquefy it, resulting in high energy consumption. Patent 2 – “A Low-Temperature Carbon Capture System and Working Method Based on Cold Energy Recovery from Dry Ice Melting” – improves upon Patent 1 by using low-temperature high-concentration brine, low-temperature refrigerant, and isopentane at a temperature not exceeding -80°C to dry, pre-cool, and sublimate the flue gas to obtain dry ice crystals. Liquid carbon dioxide is then obtained by sublimating the dry ice in a sealed chamber. However, this system has a complex structure, and the high-concentration brine can easily lead to scaling and corrosion of the equipment. Summary of the Invention

[0004] The purpose of this invention is to provide a carbon dioxide collection system for oxygen-enriched combustion boilers that is coupled with an air separation device.

[0005] This invention is achieved through the following technical solution:

[0006] A carbon dioxide collection system for an oxygen-enriched combustion boiler coupled with an air separation device includes a flue gas treatment device, a condenser, a recooler, a liquefaction booster chamber, a refrigerator, and a heat exchanger.

[0007] The outlet of the flue gas treatment device is connected to the first inlet of the flue gas condenser; the outlet of the flue gas condenser is connected to the first inlet of the primary flue gas precooler; the first outlet of the primary flue gas precooler is connected to the first inlet of the secondary flue gas precooler; the first outlet of the secondary flue gas precooler is connected to the first inlet of the gas-liquid separator, and the second outlet is connected to the third inlet of the primary flue gas precooler; the first outlet of the gas-liquid separator is connected to the first inlet of the condenser, and the second outlet is connected to the second inlet of the flue gas condenser; the first outlet of the condenser is connected to the inlet of the solid-liquid separator, and the second outlet is connected to the second inlet of the primary flue gas precooler via an extraction device; the first outlet of the recooler is connected to the second inlet of the condenser, and the second outlet is connected to the second inlet of the condenser; the first outlet of the solid-liquid separator is connected to the first inlet of the liquefaction booster chamber via a check valve. The second outlet is connected to the second inlet of the recooler; the second outlet of the liquefaction booster chamber merges into the main pipeline and is connected to the first inlet of the refrigerator; the first outlet of the heat exchanger is connected to the second inlet of the liquefaction booster chamber via a branch line, and then connected to the first inlet of the refrigerator via the main pipeline; the second outlet is connected to the second inlet of the interstage cooler; the first outlet of the refrigerator is connected to the inlet of the air liquefaction unit, and the second outlet is connected to the first inlet of the recooler; the outlet of the air liquefaction unit is connected to the inlet of the distillation column; the first outlet of the distillation column is connected to the second inlet of the refrigerator; the first inlet of the interstage cooler is connected to the outlet of the first-stage compressor, the first outlet is connected to the inlet of the second-stage compressor, and the second outlet is connected to the feedwater heater; the first outlet of the condenser is connected to the inlet of the evaporator, and the second outlet is connected to the second inlet of the flue gas secondary precooler.

[0008] A further improvement of the present invention is that a valve is provided on the branch connecting the first outlet of the heat exchanger to the second inlet of the liquefaction pressurization chamber.

[0009] A further improvement of the present invention is that the liquefaction pressurization chamber is used to store dry ice to obtain liquid carbon dioxide.

[0010] A further improvement of the present invention is that a one-way valve is used for the passage of dry ice and to prevent the passage of gas.

[0011] A further improvement of the present invention is that the solid-liquid separator is used to separate dry ice crystals and coolant, thereby realizing the collection and storage of carbon dioxide and the recycling and regeneration of coolant.

[0012] A further improvement of the present invention is that the recooler is used to achieve heat exchange between low-temperature oxygen and coolant to obtain low-temperature coolant.

[0013] A further improvement of the present invention is that the condenser is used to achieve heat exchange by mixing flue gas and cryogenic coolant.

[0014] A further improvement of the present invention is that the primary flue gas precooler and the secondary flue gas precooler are used to achieve heat exchange between oxygen and flue gas.

[0015] A further improvement of the present invention is that the refrigerator is used to cool the compressed air, and the low-temperature nitrogen and liquid oxygen obtained by the distillation process are used to further reduce the temperature of the compressed air.

[0016] A further improvement of the present invention is that the interstage cooler uses condensate to cool the compressed air, making the compression process close to isothermal compression.

[0017] The present invention has at least the following beneficial technical effects:

[0018] This invention targets oxygen-enriched combustion boilers, combines boiler operating characteristics with air separation equipment, and employs a low-temperature sublimation method to collect carbon dioxide. It has the following advantages:

[0019] First: Using condensate to cool the compressed air in stages makes the compression process closer to isothermal compression, reducing the energy consumption of the compressor. At the same time, using low-temperature nitrogen and liquid oxygen to further cool the compressed air can reduce the refrigeration energy consumption of the air separation equipment.

[0020] Second: The fully dried and pre-cooled flue gas mixes and exchanges heat with the low-temperature coolant in the sublimator. Carbon dioxide sublimates into dry ice, forming a slurry with dry ice crystals. The non-condensable gas is sent to the flue gas primary pre-cooler by the exhaust equipment to cool the flue gas, so as to make full use of the cold energy.

[0021] Third: The dry ice obtained by the solid-liquid separator enters the liquefaction and pressurization chamber through a one-way valve. Liquid carbon dioxide is obtained by sublimation of the dry ice and self-pressurization. The one-way valve can ensure the good sealing of the pressurization chamber and improve the carbon dioxide liquefaction rate. At the same time, a compressed air branch is provided, which can use compressed air to heat the dry ice and accelerate the liquefaction process.

[0022] Fourth: Low-temperature oxygen lowers the temperature of the coolant in the recooler, and then absorbs the waste heat of the flue gas through a two-stage flue gas precooler, which further reduces the temperature of the flue gas and makes full use of the oxygen cooling capacity. At the same time, the waste heat of the flue gas is recovered so that the oxygen can obtain a greater temperature rise, which is convenient for subsequent combustion and utilization.

[0023] In summary, this invention proposes a carbon dioxide collection system for an oxygen-enriched combustion boiler coupled with an air separation device. This invention employs a one-way valve to ensure the sealing of the pressure boosting chamber. Simultaneously, it utilizes condensate water for interstage cooling of the compressed air and uses dry ice, liquid oxygen obtained through distillation, and low-temperature nitrogen to lower the temperature of the compressed air, thereby reducing the energy consumption of the air separation unit and overcoming the problems of easy leakage in the sealed chamber and high energy consumption of the air separation unit in Patent 1. This invention uses cooling water and residual oxygen cooling capacity to dry the tail gas, eliminating the need for a low-temperature, high-concentration brine drying system, solving the scaling and corrosion problems that may exist in Patent 2, and simplifying the system. Furthermore, this invention utilizes residual oxygen cooling capacity for external cooling to pre-cool the flue gas, fully utilizing the cooling capacity of oxygen, recovering waste heat from the tail gas, and improving energy efficiency. Attached Figure Description

[0024] Figure 1 This is a structural block diagram of a carbon dioxide collection system for an oxygen-enriched combustion boiler with a coupled air separation device according to the present invention.

[0025] Explanation of reference numerals in the attached figures:

[0026] 1. Flue gas treatment device; 2. Flue gas condenser; 3. Primary flue gas precooler; 4. Secondary flue gas precooler; 5. Gas-liquid separator; 6. Condenser; 7. Recooler; 8. Solid-liquid separator; 9. Check valve; 10. Liquefaction booster chamber; 11. Primary compressor; 12. Secondary compressor; 13. Heat exchanger; 14. Refrigerator; 15. Air liquefaction unit; 16. Distillation column; 17. Interstage cooler; 18. Feedwater heater; 19. Condenser; 20. Evaporator; 21. Exhaust equipment; 22. Valves. Detailed Implementation

[0027] Exemplary embodiments of the present disclosure will now be described in more detail with reference to the accompanying drawings. While exemplary embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure may be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided to enable a more thorough understanding of the present disclosure and to fully convey the scope of the disclosure to those skilled in the art. It should be noted that, unless otherwise specified, the embodiments and features described herein can be combined with each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0028] like Figure 1 As shown, the present invention provides a carbon dioxide collection system for an oxygen-enriched combustion boiler with a coupled air separation device, comprising the following steps:

[0029] Step 1: The air compression process of the air separation device is the most energy-consuming process. The compressed air is cooled between stages by using the condensate from the exhaust steam of the steam turbine, so that the compression process is close to the isothermal compression process, which can reduce the power consumption of the compressor. At the same time, the heat energy of the compressed air is recovered to raise the temperature of the condensate and improve the energy utilization rate.

[0030] Step 2 involves exchanging heat between the liquid oxygen and cryogenic nitrogen obtained from the distillation of the air separator and the compressed air. This utilizes part of the cooling capacity of the liquid oxygen and all of the cooling capacity of the nitrogen to lower the temperature of the compressed air, thereby reducing the refrigeration energy required for subsequent liquefaction of the air.

[0031] Step 3: When the temperature of the oxygen used to cool the compressed air rises to about -90°C, the oxygen is sent to the recooler 7 to exchange heat with the coolant (such as isopentane) to lower the temperature of the coolant to -80°C or lower. Then the oxygen is sent to the condenser 19 to condense the high-temperature refrigerant and provide external cooling. Finally, it passes through the secondary flue gas precooler 4 and the primary flue gas precooler 3 in sequence to exchange heat with the tail flue gas, reduce the flue gas temperature, and at the same time increase the oxygen temperature to facilitate subsequent combustion and utilization.

[0032] Step 4: After pretreatment (including desulfurization and dust removal), the tail flue gas is cooled by heat exchange with cooling water in the flue gas condenser 2. Water vapor is condensed and discharged, achieving initial drying of the flue gas. Then, it is cooled step by step through the primary flue gas precooler 3 and the secondary flue gas precooler 4. After passing through the gas-liquid separator 5, the moisture is further removed. Finally, it is introduced into the sublimator 6 to contact with the low-temperature coolant. Carbon dioxide is sublimated in the coolant to form dry ice crystals. The non-condensable gas is extracted by the extraction equipment 21 and sent to the primary flue gas precooler 3 to cool the flue gas, so as to make full use of the cold energy of the non-condensable gas.

[0033] In step 5, the slurry discharged from the sublimator 6 flows into the solid-liquid separator 8, and the separated dry ice crystals fall into the liquefaction and pressurization chamber 10 through the one-way valve 9. Specifically, compressed air can be introduced through a branch line to accelerate the sublimation of the dry ice. When the pressure and temperature of the carbon dioxide in the liquefaction and pressurization chamber 10 reach or exceed the parameters corresponding to the triple point (0.52 MPa, -56.6°C), liquid carbon dioxide can be obtained, and the separated coolant is sent to the recooler 7 for cooling, achieving recycling.

[0034] The present invention discloses a carbon dioxide collection system for an oxygen-enriched combustion boiler coupled with an air separation device, specifically comprising:

[0035] Interstage cooler 17 uses condensate to cool compressed air, making the compression process close to isothermal compression and reducing compressor energy consumption;

[0036] Heat exchanger 13 uses condensate to cool the compressed air, reducing the air temperature and facilitating subsequent liquefaction;

[0037] The refrigerator 14 is used to cool compressed air. It uses low-temperature nitrogen (around -180°C) and liquid oxygen obtained from the distillation process to further reduce the temperature of the compressed air and reduce the refrigeration energy consumption required for the air liquefaction process.

[0038] Flue gas condenser 2 is used to condense water vapor in flue gas, remove moisture from the flue gas, and improve the purity of carbon dioxide collection.

[0039] The primary flue gas precooler 3 and the secondary flue gas precooler 4 are used to achieve heat exchange between oxygen and flue gas. They utilize the residual cooling capacity of oxygen to cool the flue gas, while recovering the residual heat of the flue gas to heat the oxygen, which is convenient for subsequent combustion.

[0040] Gas-water separator 5 further separates and removes moisture from the flue gas;

[0041] The condenser 6 is used to achieve heat exchange between flue gas and low-temperature coolant (minus 80°C and below). Carbon dioxide condenses in the coolant to form small ice crystals. Non-condensable gas is drawn by the extraction equipment 21 to the flue gas primary precooler 3 to cool the flue gas.

[0042] Solid-liquid separator 8 is used to separate dry ice crystals and coolant, so as to realize the collection and storage of carbon dioxide and the recycling and regeneration of coolant;

[0043] Recooler 7 is used to achieve heat exchange between low-temperature oxygen (minus 90°C) and coolant to obtain low-temperature coolant;

[0044] The liquefaction pressurization chamber 10 is used to store dry ice and obtain liquid carbon dioxide. The pressure inside the sealed chamber is increased by the sublimation of the dry ice. Liquid carbon dioxide is obtained when both the pressure and temperature of the carbon dioxide reach or exceed the parameters corresponding to the triple point (0.52 MPa, -56.6°C). Specifically, a portion of compressed air can be introduced through a branch to heat the dry ice, thereby accelerating the carbon dioxide liquefaction process.

[0045] One-way valve 9 allows only dry ice to pass through, preventing gas from passing through, ensuring the sealing of liquefaction booster chamber 10, and improving carbon dioxide liquefaction rate.

[0046] like Figure 1As shown, the outlet of the flue gas treatment device 1 is connected to the first inlet of the flue gas condenser 2; the outlet of the flue gas condenser 2 is connected to the first inlet of the primary flue gas precooler 3; the first outlet of the primary flue gas precooler 3 is connected to the first inlet of the secondary flue gas precooler 4; the first outlet of the secondary flue gas precooler 4 is connected to the first inlet of the gas-liquid separator 5, and the second outlet is connected to the third inlet of the primary flue gas precooler 3; the first outlet of the gas-liquid separator 5 is connected to the first inlet of the condenser 6, and the second outlet is connected to the second inlet of the flue gas condenser 2; the first outlet of the condenser 6 is connected to the inlet of the solid-liquid separator 8, and the second outlet is connected to the second inlet of the primary flue gas precooler 3 via the extraction device 21; the first outlet of the recooler 7 is connected to the second inlet of the condenser 6, and the second outlet is connected to the second inlet of the condenser 19; the first outlet of the solid-liquid separator 8 is connected to the first inlet of the liquefaction booster chamber 10 via the check valve 9, and the second outlet is connected to the first inlet of the liquefaction booster chamber 10. The outlet is connected to the second inlet of the recooler 7; the second outlet of the liquefaction booster chamber 10 merges into the main pipeline and is connected to the first inlet of the refrigerator 14; the first outlet of the heat exchanger 13 is connected to the second inlet of the liquefaction booster chamber 10 via a branch, and is connected to the first inlet of the refrigerator 14 via the main pipeline, and the second outlet is connected to the second inlet of the interstage cooler 17; the first outlet of the refrigerator 14 is connected to the inlet of the air liquefaction unit 15, and the second outlet is connected to the first inlet of the recooler 7; the outlet of the air liquefaction unit 15 is connected to the inlet of the distillation column 16; the first outlet of the distillation column 16 is connected to the second inlet of the refrigerator 14; the first inlet of the interstage cooler 17 is connected to the outlet of the first stage compressor 11, the first outlet is connected to the inlet of the second stage compressor 12, and the second outlet is connected to the feedwater heater 18; the first outlet of the condenser 19 is connected to the inlet of the evaporator 20, and the second outlet is connected to the second inlet of the flue gas secondary precooler 4.

[0047] The specific process of this invention is as follows:

[0048] 1. Empty molecule system

[0049] The air molecule system includes a primary compressor 11, a secondary compressor 12, an interstage cooler 17, a heat exchanger 13, a refrigerator 14, an air liquefaction unit 15, and a distillation column 16.

[0050] The first-stage compressor 11 increases the pressure and temperature of the air, and uses condensate to cool the compressed air in the interstage cooler 17, making the compression process approximately isothermal and reducing compressor energy consumption. After the second-stage compressor 12, condensate is used to cool the compressed air in the heat exchanger 13, facilitating subsequent air liquefaction. Specifically, a portion of the compressed air can be drawn out by valve 22 and sent to the liquefaction booster chamber 10 via a branch line to heat the dry ice inside, accelerating the carbon dioxide liquefaction process. Valve 22 can be adjusted to control the branch air flow according to the requirements. Subsequently, the branch air is mixed with the main flow and sent to the refrigerator 14, where low-temperature nitrogen and liquid oxygen exchange heat with the compressed air, lowering the air temperature and facilitating subsequent liquefaction, thus reducing refrigeration energy consumption. The nitrogen is discharged after its cooling capacity is fully utilized, while the oxygen is sent to the recooler 7 after its temperature rises to about -90°C. The air liquefaction unit 15 liquefies the compressed air, and then sends the liquefied air to the distillation column 16 for separation to obtain low-temperature nitrogen and liquid oxygen.

[0051] 2. Deposition Subsystem

[0052] The condensation subsystem includes a flue gas condenser 2, a primary flue gas precooler 3, a secondary flue gas precooler 4, a gas-liquid separator 5, a recooler 7, a condenser 6, a solid-liquid separator 8, and a liquefaction pressurization chamber 10.

[0053] After desulfurization and dust removal, the flue gas exchanges heat with cooling water in flue gas condenser 2, where water vapor condenses and is discharged to complete pre-dehydration and drying. Subsequently, it exchanges heat with oxygen in the primary flue gas precooler 3 and the secondary flue gas precooler 4, gradually cooling down and further condensing the water vapor. The flue gas is then further dried in the gas-liquid separator 5. Specifically, the condensate obtained in the gas-liquid separator 5 is introduced into the flue gas condenser 2 to condense the flue gas. Low-temperature oxygen exchanges heat with coolant in recooler 7. The low-temperature coolant at the outlet of recooler 7 is passed into sublimator 6 to mix and exchange heat with the dried flue gas at the outlet of gas-liquid separator 5. Carbon dioxide sublimates into dry ice crystals in the coolant. The resulting slurry is separated by solid-liquid separator 8. The dry ice crystals enter the liquefaction booster chamber 10 through one-way valve 9, while the coolant returns to recooler 7 for cooling, thus completing the cycle. Specifically, the coolant should be selected as a non-corrosive working fluid with a low freezing point and low carbon dioxide absorption rate, meeting production requirements. Dry ice sublimates in the pressure-boosting chamber 10, raising the pressure in the sealed chamber to 0.52 MPa or higher to obtain liquid carbon dioxide. Specifically, compressed air can be introduced into the liquefaction pressure-boosting chamber 10 via valve 22 to accelerate the liquefaction process; the opening degree of valve 22 can vary with the load. Specifically, the one-way valve 9 allows only the passage of dry ice crystals in one direction, preventing the passage of gas, thus ensuring the airtightness of the pressure-boosting chamber. Specifically, the non-condensable gas in the condenser 6 is extracted by the extraction device 21 and sent to the primary flue gas precooler 3 to cool the flue gas, achieving full utilization of cold energy.

[0054] 3. Oxygen waste cooling utilization subsystem

[0055] The oxygen waste cooling utilization subsystem includes condenser 19, primary flue gas precooler 3, and secondary flue gas precooler 4.

[0056] The oxygen at the outlet of recooler 7 enters condenser 19 to exchange heat with the refrigerant, causing it to condense and providing cooling to the outside. The oxygen at the outlet of condenser 19 exchanges heat with the flue gas through a two-stage flue gas precooler, achieving precooling of the flue gas. At the same time, the waste heat of the flue gas is recovered to raise the oxygen temperature, which is convenient for subsequent combustion and utilization.

[0057] Although the present invention has been described in detail above with general descriptions and specific embodiments, modifications or improvements can be made to it, which will be obvious to those skilled in the art. Therefore, all such modifications or improvements made without departing from the spirit of the present invention fall within the scope of protection claimed by the present invention.

Claims

1. A carbon dioxide collection system for an oxygen-enriched combustion boiler coupled with an air separation device, characterized in that, It includes a flue gas treatment device (1), a condenser (6), a recooler (7), a liquefaction booster chamber (10), a refrigerator (14), and a heat exchanger (13). The outlet of the flue gas treatment device (1) is connected to the first inlet of the flue gas condenser (2); the outlet of the flue gas condenser (2) is connected to the first inlet of the primary flue gas precooler (3); the first outlet of the primary flue gas precooler (3) is connected to the first inlet of the secondary flue gas precooler (4); the first outlet of the secondary flue gas precooler (4) is connected to the first inlet of the gas-liquid separator (5), and the second outlet is connected to the third inlet of the primary flue gas precooler (3); the first outlet of the gas-liquid separator (5) is connected to the first inlet of the condenser (6). The first outlet of the condenser (6) is connected to the inlet of the solid-liquid separator (8), and the second outlet is connected to the second inlet of the primary precooler (3) of the flue gas via the extraction device (21); the first outlet of the recooler (7) is connected to the second inlet of the condenser (6), and the second outlet is connected to the second inlet of the condenser (19); the first outlet of the solid-liquid separator (8) is connected to the first inlet of the liquefaction booster chamber (10) via the check valve (9), and the second outlet is connected to the second inlet of the condenser (19). The second outlet of the recooler (7) is connected to the second inlet of the recooler (7); the second outlet of the liquefaction booster chamber (10) merges into the main pipeline and is connected to the first inlet of the refrigerator (14); the first outlet of the heat exchanger (13) is connected to the second inlet of the liquefaction booster chamber (10) via a branch, and is connected to the first inlet of the refrigerator (14) via the main pipeline, and the second outlet is connected to the second inlet of the interstage cooler (17); the first outlet of the refrigerator (14) is connected to the inlet of the air liquefaction unit (15), and the second outlet is connected to the first inlet of the recooler (7). The outlet of the air liquefaction unit (15) is connected to the inlet of the distillation column (16); the first outlet of the distillation column (16) is connected to the second inlet of the refrigerator (14); the first inlet of the interstage cooler (17) is connected to the outlet of the first stage compressor (11), the first outlet is connected to the inlet of the second stage compressor (12), and the second outlet is connected to the feedwater heater (18); the first outlet of the condenser (19) is connected to the inlet of the evaporator (20), and the second outlet is connected to the second inlet of the flue gas secondary precooler (4); The liquefaction pressurization chamber (10) is used to store dry ice and obtain liquid carbon dioxide; The solid-liquid separator (8) is used to separate dry ice crystals and coolant, so as to realize the collection and storage of carbon dioxide and the recycling and regeneration of coolant; The recooler (7) is used to achieve heat exchange between low-temperature oxygen and coolant to obtain low-temperature coolant; The condenser (6) is used to achieve heat exchange by mixing flue gas and low-temperature coolant; The primary precooler (3) and the secondary precooler (4) are used to achieve heat exchange between oxygen and flue gas; The refrigerator (14) is used to cool compressed air and further reduce the temperature of compressed air by using low-temperature nitrogen and liquid oxygen obtained from the distillation process; The interstage cooler (17) uses condensate to cool the compressed air, making the compression process close to isothermal compression.

2. The oxygen-enriched combustion boiler carbon dioxide collection system with coupled air separation device according to claim 1, characterized in that, A valve (22) is installed on the branch connecting the first outlet of the heat exchanger (13) to the second inlet of the liquefaction booster chamber (10).

3. The oxygen-enriched combustion boiler carbon dioxide collection system with coupled air separation device according to claim 1, characterized in that, A one-way valve (9) is used for dry ice passage and prevents gas passage.

Images