Direct-fired supercritical carbon dioxide semi-closed energy storage and oxygen recovery system and method

Abstract

The invention provides a direct-fired supercritical carbon dioxide semi-closed energy storage and oxygen recovery system and method. The direct-fired supercritical carbon dioxide semi-closed energy storage and oxygen recovery system comprises a carbon dioxide multi-stage intercooling compression unit, a liquid carbon dioxide storage device, a regenerative heating device, a combustion chamber, a turbine, a condensing device and a gaseous carbon dioxide storage device which are circularly connected. The direct-fired supercritical carbon dioxide semi-closed energy storage and oxygen recovery system further comprises an oxygen multi-stage intercooling compression unit connected with the regenerative heating device. And the liquid carbon dioxide storage device is connected with the oxygen multi-stage intercooling compression unit through an oxygen recovery bypass pipeline. According to the system, the excessive oxygen in the flue gas generated by the oxygen-enriched combustion chamber is recycled, the oxygen recycling difficulty is reduced, and the stability and flexibility of the system are improved.

Description

Technical Field

[0001] This invention relates to the field of supercritical carbon dioxide energy storage technology, and in particular to a direct-fired supercritical carbon dioxide semi-closed energy storage and oxygen recovery system and method. Background Technology

[0002] To enhance the absorption capacity of renewable energy, thermal power units need to improve their regulation capabilities to support the construction of new power systems. However, conventional thermal power plants have high carbon emissions, far exceeding the near-zero emission levels of wind and solar power units, posing a primary obstacle to peak carbon emissions and carbon neutrality in the power system, thus creating significant pressure on the energy system to reduce carbon emissions. Carbon dioxide, as a natural working fluid, offers advantages in energy conversion, energy storage, and carbon capture, being highly efficient, economical, and flexible. The potential of applying carbon dioxide thermal systems to new energy systems is being gradually explored, and developing new thermal systems is of great significance for overcoming energy utilization bottlenecks.

[0003] Against this backdrop, the turbine-side oxy-fuel combustion semi-closed supercritical CO2 thermal system exhibits unique technological advantages, providing a highly promising solution for efficient and low-carbon power generation from fossil fuels. The semi-closed supercritical CO2 thermal system employs oxy-fuel combustion technology, a technique that uses pure oxygen or oxygen-enriched streams for combustion, virtually eliminating all nitrogen from the air and producing high-concentration carbon dioxide flue gas. Because no nitrogen is involved in the combustion process, this technology offers significant advantages in reducing nitrogen oxide emissions.

[0004] However, current oxygen-enriched combustion methods have the following drawbacks:

[0005] 1. For supercritical CO2 thermodynamic systems with oxygen-enriched combustion, the flue gas after combustion contains excess oxygen, which needs to be separated.

[0006] 2. High oxygen production cost: Oxygen-enriched combustion requires the separate production of oxygen, currently mainly through low-temperature air separation technology. This technology is energy-intensive, leading to increased oxygen production costs. For example, producing 95% pure oxygen requires approximately 200 kWh / ton of oxygen, making oxygen-enriched combustion an economically challenging endeavor.

[0007] 3. Reduced energy efficiency: Energy consumption during oxygen production reduces the net power generation efficiency of power plants, typically by about 7% to 10%. In addition, oxygen-enriched combustion may lead to a decrease in heat recovery efficiency, partially offsetting the energy-saving effects of oxygen enrichment.

[0008] 4. Equipment Corrosion and Wear: The furnace environment of oxygen-enriched combustion is highly corrosive, placing higher demands on the corrosion resistance of boiler materials. For example, in cement kilns, oxygen-enriched combustion may lead to a decrease in the enthalpy of secondary and tertiary air, an increase in the enthalpy carried away by the exhaust air of the cooler, and a decrease in heat recovery rate.

[0009] 5. Technical complexity: Oxygen-enriched combustion systems require the installation of additional equipment, such as air separation units (ASU), flue gas recirculation (FGR), and gas processing units (GPU), which increases the complexity of the system and investment costs.

[0010] 6. Limitations of oxygen removal technology: Current oxygen removal technologies (such as catalytic reduction) have difficulties in treating high concentrations of oxygen, and commercial catalysts or adsorbents are only suitable for trace amounts of oxygen (<1000 ppmv).

[0011] 7. Safety issues: There are inherent risks in the storage, production and use of oxygen, and appropriate safety studies are required.

[0012] These issues limit the large-scale application of oxygen-enriched combustion technology, necessitating further research and development of more efficient oxygen production technologies and more economical oxygen recovery methods to improve the safety and economy of thermal systems.

[0013] CN119756042A discloses a high-temperature energy storage and air separation system and method for s-CO2 cycle power generation under oxy-fuel combustion, including a heat storage and release and air separation subsystem and a cycle power generation system; the heat storage and release and air separation subsystem includes a heat storage reactor, a heat exchanger, an oxygen storage tank, a nitrogen storage tank, and a heat exchange and storage tank; the cycle power generation system includes an oxy-fuel combustion unit and a supercritical CO2 Brayton cycle power generation unit; the oxy-fuel combustion unit includes an oxygen storage tank, a combustion chamber, a denitrification device, a dust collector, a desulfurization device, a compression purification device, and a CO2 capture device; the supercritical CO2 Brayton cycle power generation unit includes a turbine unit, a regenerator, a generator, a condenser, and a compressor.

[0014] CN119982136A discloses a staged pressurized oxy-fuel combustion boiler coupled with a supercritical carbon dioxide cycle thermal system, including an air molecule system for generating oxygen; and a combustion subsystem that stage-pressurizes and oxy-fuels the oxygen generated by the air molecule system to produce heat and flue gas. Part of the flue gas is used as reflux gas to blow pulverized coal, while the other part enters the supercritical carbon dioxide working medium to absorb the heat generated by the combustion subsystem for power generation. By coupling staged pressurized oxy-fuel combustion with a supercritical carbon dioxide cycle, a power generation efficiency of 49.08% can be achieved.

[0015] However, none of the above systems have solved the various problems brought about by oxygen-enriched combustion technology, nor have they achieved oxygen recovery and utilization. Summary of the Invention

[0016] In view of the problems existing in the prior art, the present invention provides a direct-fired supercritical carbon dioxide semi-closed energy storage and oxygen recovery system and method. For the excess oxygen in the flue gas after oxygen-enriched combustion in the combustion chamber, it is first compressed and cooled into a liquid carbon dioxide storage device, and then mixed with oxygen provided by the oxygen multi-stage intercooled compression unit through an oxygen recovery bypass pipeline. This realizes the recovery and utilization of excess oxygen, while reducing the power consumption of the compressor in the oxygen-assisted combustion pressurization section, reducing the difficulty of oxygen recovery, and improving the economic efficiency of unit operation.

[0017] To achieve this objective, the present invention adopts the following technical solution:

[0018] In a first aspect, the present invention provides a direct-fired supercritical carbon dioxide semi-closed energy storage and oxygen recovery system, the direct-fired supercritical carbon dioxide semi-closed energy storage and oxygen recovery system comprising a carbon dioxide multi-stage intercooling and compression unit, a liquid carbon dioxide storage device, a regenerative heating device, a combustion chamber, a turbine, a condensation device, and a gaseous carbon dioxide storage device connected in a cycle.

[0019] The direct-fired supercritical carbon dioxide semi-closed energy storage and oxygen recovery system also includes an oxygen multi-stage inter-stage cold compression unit connected to the regenerative heating device; the liquid carbon dioxide storage device is connected to the oxygen multi-stage cold compression unit via an oxygen recovery bypass pipeline.

[0020] The direct-fired supercritical carbon dioxide semi-closed energy storage and oxygen recovery system also includes a heat storage medium circulation unit located between the carbon dioxide multi-stage intercooling and compression unit and the regenerative heating device.

[0021] The direct-fired supercritical carbon dioxide semi-closed energy storage and oxygen recovery system of this invention includes a circulating multi-stage carbon dioxide intercooling and compression unit, a liquid carbon dioxide storage device, a regenerative heating device, a combustion chamber, a turbine, a condensation device, and a gaseous carbon dioxide storage device. The flue gas from oxygen-enriched combustion in the combustion chamber, along with the carbon dioxide, is compressed and cooled by the multi-stage carbon dioxide intercooling and compression unit before being sent to the liquid carbon dioxide storage device. At the liquid carbon dioxide storage device, the oxygen is in a gaseous state and easily separates from the liquid carbon dioxide, thus eliminating the need for additional deoxygenation equipment. The liquid carbon dioxide storage device is connected to the multi-stage oxygen intercooling and compression unit via an oxygen recovery bypass pipeline. The recovered oxygen is mixed with the oxygen from the multi-stage oxygen intercooling and compression unit through the oxygen recovery bypass pipeline and used as a combustion aid in the combustion chamber. This reduces the amount of oxygen required for combustion, lowers the compression power consumption of the multi-stage oxygen intercooling and compression unit, and reduces the power consumption of the oxygen source device, thereby improving the system's efficiency and economy. The direct-fired supercritical carbon dioxide semi-closed energy storage and oxygen recovery system of this invention recovers excess oxygen generated by oxygen-enriched combustion, reducing corrosion of corresponding equipment, lowering maintenance costs, and improving system safety. Oxygen recovery is achieved through an oxygen recovery bypass pipeline, which can adapt to different operating conditions and improve the stability and flexibility of the system.

[0022] Preferably, the multi-stage intercooled carbon dioxide compression unit includes a carbon dioxide compression device and a carbon dioxide cooling device connected in sequence.

[0023] Preferably, the number of carbon dioxide compression devices is at least 3 sets, for example, 3 sets, 4 sets, 5 sets or 6 sets, etc.

[0024] Preferably, the number of carbon dioxide cooling devices is at least 3 sets, for example, 3 sets, 4 sets, 5 sets or 6 sets, etc.

[0025] Preferably, the first carbon dioxide compression device is connected to an electric motor.

[0026] Preferably, a carbon dioxide capture device is also provided between the multi-stage intercooled compression unit and the liquid carbon dioxide storage device, which can capture and seal excess carbon dioxide working fluid.

[0027] Preferably, a first carbon dioxide pressurization device is provided between the liquid carbon dioxide storage device and the regenerative heating device.

[0028] Preferably, the first carbon dioxide pressurizing device is connected to the second carbon dioxide pressurizing device.

[0029] Preferably, the first carbon dioxide pressurization device is connected to the regenerative heating device via a first carbon dioxide delivery pipe, a second carbon dioxide delivery pipe, and a third carbon dioxide delivery pipe.

[0030] Preferably, the first carbon dioxide delivery pipeline is connected to the oxygen multi-stage cold compression unit, and the first carbon dioxide delivery pipeline is equipped with a carbon dioxide-oxygen mixed working fluid pressurization device to mix and pressurize part of the carbon dioxide with the oxygen from the oxygen multi-stage cold compression unit to form a combustion chamber accelerator.

[0031] Preferably, the second carbon dioxide delivery pipe is connected to the combustion chamber, and a portion of the carbon dioxide is introduced into the combustion chamber as a cooling medium to regulate the reaction temperature and prevent damage to the combustion chamber structure.

[0032] Preferably, the third carbon dioxide delivery pipe is connected to the turbine, and a portion of the carbon dioxide is used as a cooling medium to reduce the surface temperature of the turbine blades.

[0033] Preferably, the combustion chamber is connected to a gaseous fuel compression device.

[0034] Preferably, the turbine is connected to a generator.

[0035] Preferably, the oxygen recovery bypass pipeline is equipped with a flow metering device to count the bypass oxygen flow. Based on the bypass flow, the oxygen flow of the multi-stage oxygen cooling and compression unit is reduced, which can reduce the power consumption of the oxygen preparation device and the oxygen compression device and improve the economy of the system.

[0036] Preferably, the oxygen multi-stage intercooled compression unit includes an oxygen compression device and an oxygen cooling device connected in sequence.

[0037] Preferably, the number of oxygen compression devices is at least 3 sets, for example, 3 sets, 4 sets, 5 sets or 6 sets, etc.

[0038] Preferably, the number of oxygen cooling devices is at least 2 sets, for example, 2 sets, 4 sets, 5 sets or 6 sets, etc.

[0039] Preferably, the heat storage medium circulation unit includes a heat storage medium hot tank, a first transfer pump, a heat storage medium cold tank, and a second transfer pump that are connected in a circulating manner.

[0040] Preferably, the second delivery pump, the first carbon dioxide cooling device, and the heat storage medium tank are connected in sequence.

[0041] Preferably, the first delivery pump, the regenerative heating device, and the heat storage medium cold tank are connected in sequence.

[0042] Secondly, the present invention also provides a method for direct-fired supercritical carbon dioxide semi-closed energy storage and oxygen recovery, wherein the method employs the direct-fired supercritical carbon dioxide semi-closed energy storage and oxygen recovery system described in the first aspect; the method includes an energy storage process and an energy release process; oxygen recovery is performed during the energy storage process.

[0043] Preferably, the energy storage process includes: the gas in the gaseous carbon dioxide storage device enters the carbon dioxide multi-stage intercooling compression unit and is compressed, the carbon dioxide in the gas becomes liquid carbon dioxide and is stored in the lower part of the liquid carbon dioxide storage device, while the oxygen in the gas remains gaseous and is stored in the top of the liquid carbon dioxide storage device, thereby realizing oxygen recovery; the compression heat of the carbon dioxide multi-stage intercooling compression unit enters the heat storage medium circulation unit for storage.

[0044] Preferably, the process of the heat of compression from the multi-stage intercooled compression unit of carbon dioxide entering the heat storage medium circulation unit for storage includes: the heat storage medium cold tank enters the first carbon dioxide cooling device via the second delivery pump to absorb the heat of compression, and then enters the heat storage medium hot tank for storage.

[0045] Preferably, the energy release process includes: liquid carbon dioxide and oxygen in the liquid carbon dioxide storage device are mixed with high-temperature and high-pressure oxygen in the multi-stage cold compression unit, pressurized by the carbon dioxide-oxygen mixture pressurizing device, heated by the regenerative heating device, and then enter the combustion chamber for oxygen-enriched combustion. The resulting combustion flue gas enters the turbine to do work, and the turbine exhaust gas enters the regenerative heating device and the condensation device in sequence for heat exchange before entering the gaseous carbon dioxide storage device; the compression heat stored in the heat storage medium circulation unit is used to supplement the heat of the regenerative heating device.

[0046] Preferably, the temperature of the oxygen entering the regenerative heating device is 20-60°C, for example, it can be 20°C, 25°C, 30°C, 40°C, 50°C or 60°C.

[0047] Preferably, the pressure of the oxygen entering the regenerative heating device is 10-36.5 MPa, for example, it can be 10 MPa, 15 MPa, 20 MPa, 25 MPa, 30 MPa or 36.5 MPa, etc.

[0048] Preferably, the liquid carbon dioxide in the liquid carbon dioxide storage device enters the regenerative heating device specifically as follows: after being pressurized by a first carbon dioxide pressurizing device, the liquid carbon dioxide is mixed with high-temperature and high-pressure oxygen from a multi-stage intercooled compression unit via a first carbon dioxide conveying pipeline as a combustion aid; after being pressurized by a carbon dioxide-oxygen mixture pressurizing device, it enters the regenerative heating device for heating and then enters the combustion chamber for oxygen-enriched combustion; after being pressurized by a second carbon dioxide conveying pipeline into a second carbon dioxide pressurizing device and then heated in the regenerative heating device, it enters the combustion chamber as a cooling medium to regulate the temperature; after being pressurized by a third carbon dioxide conveying pipeline into a second carbon dioxide pressurizing device, it enters the turbine as a cooling medium to reduce the temperature of the turbine blades.

[0049] Preferably, the oxygen mole fraction in the oxygen-enriched combustion accelerator is 10 mol%-30 mol%, for example, it can be 10 mol%, 13 mol%, 15 mol%, 20 mol%, 25 mol%, 28 mol%, or 30 mol%.

[0050] Preferably, the turbine exhaust steam is condensed into liquid water and separated in a condensation unit.

[0051] Preferably, the process of using the compressed heat stored in the heat storage medium circulation unit to supplement the heat of the regenerative heating device includes: the heat storage medium in the heat storage medium hot tank is sent into the regenerative heating device by the first transfer pump to release heat, and then enters the heat storage medium cold tank for storage.

[0052] The direct-fired supercritical carbon dioxide semi-closed energy storage and oxygen recovery method of this invention compresses and cools oxygen and carbon dioxide together in the gaseous carbon dioxide storage device during the energy storage process, recovers and stores the oxygen at the top of the liquid carbon dioxide storage device, and then mixes the recovered oxygen with the high-temperature and high-pressure oxygen in the multi-stage cold compression unit during the energy release process, and uses them together as a combustion aid in the combustion chamber. This reduces the corrosion of equipment by oxygen, improves the safety of the system, reduces the compression power consumption of the multi-stage cold compression unit and the power consumption of the oxygen source device, and improves the efficiency and economy of the system.

[0053] As a preferred technical solution of the present invention, the direct-fired supercritical carbon dioxide semi-closed energy storage and oxygen recovery method includes an energy storage process and an energy release process; oxygen recovery is performed during the energy storage process.

[0054] The energy storage process includes: the gas in the gaseous carbon dioxide storage device enters the carbon dioxide multi-stage intercooling compression unit and is compressed, the carbon dioxide in the gas becomes liquid carbon dioxide and is stored in the lower part of the liquid carbon dioxide storage device, while the oxygen in the gas remains gaseous and is stored in the top of the liquid carbon dioxide storage device, thus realizing oxygen recovery; the heat of compression of the carbon dioxide multi-stage intercooling compression unit enters the heat storage medium circulation unit for storage, the process includes: the heat storage medium cold tank enters the first carbon dioxide cooling device through the second transfer pump to absorb the heat of compression, and then enters the heat storage medium hot tank for storage.

[0055] The energy release process includes: liquid carbon dioxide in the liquid carbon dioxide storage device is pressurized by a first carbon dioxide pressurizing device, then mixed with high-temperature and high-pressure oxygen from a multi-stage cold compression unit via a first carbon dioxide conveying pipeline as a combustion aid, pressurized by a carbon dioxide-oxygen mixture pressurizing device, heated by a regenerative heating device, and then enters the combustion chamber for oxygen-enriched combustion; it then enters a second carbon dioxide pressurizing device via a second carbon dioxide conveying pipeline, is heated by a regenerative heating device, and then enters the combustion chamber as a cooling medium to regulate the temperature; finally, it enters a second carbon dioxide pressurizing device via a third carbon dioxide conveying pipeline, is pressurized, and then enters the turbine as a cooling medium to reduce the temperature of the turbine blades.

[0056] The combustion flue gas produced by oxygen-enriched combustion enters the turbine to do work. The turbine exhaust gas then enters the regenerator and condenser for heat exchange before entering the gaseous carbon dioxide storage device. The oxygen mole fraction in the oxygen-enriched combustion oxidizer is 10 mol%-30 mol%. The temperature of the oxygen entering the regenerator is 20-60℃, and the pressure is 10-36.5 MPa.

[0057] The compressed heat stored in the heat storage medium circulation unit is used to supplement the heat of the regenerative heating device. The process includes: the heat storage medium in the heat storage medium hot tank is sent into the regenerative heating device by the first transfer pump to release heat, and then enters the heat storage medium cold tank for storage.

[0058] Compared with the prior art, the present invention has at least the following beneficial effects:

[0059] (1) The direct-fired supercritical carbon dioxide semi-closed energy storage and oxygen recovery system provided by the present invention recovers oxygen through an oxygen recovery bypass pipeline, which can separate excess oxygen in the flue gas after combustion of the direct-fired supercritical carbon dioxide semi-closed energy storage system based on oxygen-enriched combustion, reduce equipment corrosion, extend equipment service life, and reduce maintenance costs; and improve the stability and flexibility of the system.

[0060] (2) The combustion chamber of the direct-fired supercritical carbon dioxide semi-closed energy storage and oxygen recovery system provided by the present invention adopts oxygen-enriched combustion, which increases the carbon dioxide concentration in the flue gas. Moreover, the carbon dioxide in the flue gas can be utilized and treated without separation, thereby effectively reducing the emission of carbon dioxide generated by combustion into the atmosphere and optimizing the carbon collection process.

[0061] (3) The direct-fired supercritical carbon dioxide semi-closed energy storage and oxygen recovery system provided by the present invention uses an oxygen recovery bypass pipeline to separate the oxygen at the top of the liquid carbon dioxide storage device and enter the combustion chamber for use. The bypass is designed to the corresponding node of the oxygen multi-stage cold compression unit according to the oxygen pressure in the liquid carbon dioxide storage device, which reduces the oxygen flow rate of the oxygen multi-stage cold compression unit and reduces the total power consumption of oxygen preparation and compressor unit. Attached Figure Description

[0062] Figure 1 This is a schematic diagram of the direct-fired supercritical carbon dioxide semi-closed energy storage and oxygen recovery system in Embodiment 1 of the present invention.

[0063] Figure 2 This is a schematic diagram of the direct-fired supercritical carbon dioxide semi-closed energy storage and oxygen recovery system in Embodiment 2 of the present invention.

[0064] Figure 3 This is a schematic diagram of the direct-fired supercritical carbon dioxide semi-closed energy storage and oxygen recovery system in Embodiment 3 of the present invention.

[0065] In the diagram: 1-Liquid carbon dioxide storage device; 2-Regenerative heating device; 3-Combustion chamber; 4-Turbine; 5-Condensation device; 6-Gaseous carbon dioxide storage device; 7-Oxygen recovery bypass pipeline; 8-First carbon dioxide compression device; 9-Second carbon dioxide compression device; 10-Third carbon dioxide compression device; 11-First carbon dioxide cooling device; 12-Second carbon dioxide cooling device; 13-Third carbon dioxide cooling device; 14-Electric motor; 15-Carbon dioxide capture device; 16-First carbon dioxide pressurization device; 17-Gaseous fuel compression device; 18-Generator; 19-First oxygen compression device; 20-Second oxygen compression device; 21-Third oxygen compression device; 22-First oxygen cooling device; 23-Second oxygen cooling device; 24-Heat storage medium hot tank; 25-First transfer pump; 26-Heat storage medium cold tank; 27-Second transfer pump; 28-Fourth carbon dioxide cooling device; 29-Second carbon dioxide pressurization device; 30-Carbon dioxide and oxygen mixed working fluid pressurization device. Detailed Implementation

[0066] The technical solution of the present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0067] The present invention will now be described in further detail. However, the examples described below are merely simplified examples of the present invention and do not represent or limit the scope of protection of the present invention. The scope of protection of the present invention is determined by the claims.

[0068] It should be understood that in the description of this invention, the terms "center," "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. These terms are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. Furthermore, the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined with "first," "second," etc., may explicitly or implicitly include one or more of that feature. In the description of this invention, unless otherwise stated, "a plurality of" means two or more.

[0069] It should be noted that, in the description of this invention, unless otherwise explicitly specified and limited, the terms "set," "connected," and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0070] Those skilled in the art should understand that the present invention necessarily includes the necessary pipelines, conventional valves and general pump equipment for achieving process integrity, but the above content is not the main inventive point of the present invention. Those skilled in the art can add layouts based on process flow and equipment structure selection, and the present invention does not make any special requirements or specific limitations in this regard.

[0071] Example 1

[0072] This embodiment provides a direct-fired supercritical carbon dioxide semi-closed energy storage and oxygen recovery system, the schematic diagram of which is shown below. Figure 1 As shown.

[0073] The direct-fired supercritical carbon dioxide semi-closed energy storage and oxygen recovery system includes a circulating multi-stage intercooled compression unit for carbon dioxide, a liquid carbon dioxide storage device 1, a regenerative heating device 2, a combustion chamber 3, a turbine 4, a condensation device 5, and a gaseous carbon dioxide storage device 6.

[0074] The direct-fired supercritical carbon dioxide semi-closed energy storage and oxygen recovery system also includes an oxygen multi-stage cold compression unit connected to the regenerative heating device 2; the liquid carbon dioxide storage device 1 is connected to the oxygen multi-stage cold compression unit via an oxygen recovery bypass pipe 7.

[0075] The direct-fired supercritical carbon dioxide semi-closed energy storage and oxygen recovery system also includes a heat storage medium circulation unit set between the carbon dioxide multi-stage intercooling and compression unit and the regenerative heating device 2.

[0076] The multi-stage intercooled carbon dioxide compression unit includes a carbon dioxide compression device and a carbon dioxide cooling device connected in sequence.

[0077] In this embodiment, there are three sets of carbon dioxide compression devices, which are named the first carbon dioxide compression device 8, the second carbon dioxide compression device 9, and the third carbon dioxide compression device 10, respectively.

[0078] In this embodiment, there are four sets of carbon dioxide cooling devices, which are named as first carbon dioxide cooling device 11, second carbon dioxide cooling device 12, third carbon dioxide cooling device 13 and fourth carbon dioxide cooling device 28, respectively.

[0079] The first carbon dioxide compression device 8, the first carbon dioxide cooling device 11, the second carbon dioxide compression device 9, the second carbon dioxide cooling device 12, the third carbon dioxide compression device 10, and the third carbon dioxide cooling device 13 are connected in sequence.

[0080] The first carbon dioxide compression device 8 is connected to the electric motor 14.

[0081] A carbon dioxide capture device 15 is also provided between the multi-stage intercooled compression unit for carbon dioxide and the liquid carbon dioxide storage device 1.

[0082] A first carbon dioxide pressurization device 16 is provided between the liquid carbon dioxide storage device 1 and the regenerative heating device 2;

[0083] The first carbon dioxide pressurizing device 16 is connected to the fourth carbon dioxide cooling device 28, and is connected to the regenerative heating device 2 via the first carbon dioxide conveying pipe, the second carbon dioxide conveying pipe, and the third carbon dioxide conveying pipe, respectively, via the second carbon dioxide pressurizing device 29 and the carbon dioxide-oxygen mixed working fluid pressurizing device 30.

[0084] The first carbon dioxide delivery pipeline is connected to the multi-stage oxygen cold compression unit;

[0085] The second carbon dioxide delivery pipe is connected to the combustion chamber 3;

[0086] The third carbon dioxide delivery pipeline is connected to turbine 4.

[0087] The combustion chamber 3 is connected to the gas fuel compression device 17;

[0088] The turbine 4 is connected to the generator 18;

[0089] The oxygen multi-stage intercooled compression unit includes an oxygen compression device and an oxygen cooling device connected in sequence.

[0090] In this embodiment, there are three sets of oxygen compression devices, which are named the first oxygen compression device 19, the second oxygen compression device 20, and the third oxygen compression device 21, respectively.

[0091] In this embodiment, there are two sets of oxygen cooling devices, which are named the first oxygen cooling device 22 and the second oxygen cooling device 23, respectively.

[0092] The first oxygen compression device 19, the first oxygen cooling device 22, the second oxygen compression device 20, the second oxygen cooling device 23, and the third oxygen compression device 21 are connected in sequence.

[0093] The oxygen recovery bypass pipe 7 described in this embodiment is connected to the outlet of the third oxygen compression device 21 because the oxygen pressure at the top of the liquid carbon dioxide storage device 1 is 7 MPa, which is close to the outlet oxygen pressure of the third oxygen compression device 21.

[0094] The heat storage medium circulation unit includes a heat storage medium hot tank 24, a first delivery pump 25, a heat storage medium cold tank 26, and a second delivery pump 27, which are connected in a circulation manner.

[0095] The second delivery pump 27, the first carbon dioxide cooling device 11, and the heat storage medium tank 24 are connected in sequence;

[0096] The first delivery pump 25, the regenerative heating device 2, and the heat storage medium cold tank 26 are connected in sequence.

[0097] This embodiment also provides a method for direct-fired supercritical carbon dioxide semi-closed energy storage and oxygen recovery. The method employs the direct-fired supercritical carbon dioxide semi-closed energy storage and oxygen recovery system described in the first aspect. The method includes an energy storage process and an energy release process. Oxygen recovery is performed during the energy storage process.

[0098] The energy storage process includes: the gas in the gaseous carbon dioxide storage device 6 is sequentially compressed by the first carbon dioxide compression device 8, the first carbon dioxide cooling device 11, the second carbon dioxide compression device 9, the second carbon dioxide cooling device 12, the third carbon dioxide compression device 10, and the third carbon dioxide cooling device 13, and the carbon dioxide in the gas becomes liquid carbon dioxide, which is stored in the lower part of the liquid carbon dioxide storage device 1. The oxygen in the gas remains gaseous and is stored in the top of the liquid carbon dioxide storage device 1, thus realizing oxygen recovery. The heat of compression from the multi-stage inter-stage carbon dioxide cooling compression unit is stored in the heat storage medium circulation unit. The process includes: the heat storage medium cold tank 26 enters the first carbon dioxide cooling device 11 via the second transfer pump 27 to absorb the heat of compression, and then enters the heat storage medium hot tank 24 for storage. The first carbon dioxide compression device 8 is powered by the electric motor 14. The outlet of the third carbon dioxide cooling device 13 is also connected to the carbon dioxide capture device 15 for carbon capture.

[0099] The energy release process includes: liquid carbon dioxide in the liquid carbon dioxide storage device 1 is pressurized by the first carbon dioxide pressurizing device 16 and cooled by the fourth carbon dioxide cooling device 28; it is then mixed with high-temperature and high-pressure oxygen from the multi-stage cold compression unit via the first carbon dioxide conveying pipeline as a combustion aid; after being pressurized by the carbon dioxide-oxygen mixture pressurizing device 30, it enters the regenerative heating device 2 for heating and then enters the combustion chamber 3 for oxygen-enriched combustion; after being pressurized by the second carbon dioxide conveying pipeline into the second carbon dioxide pressurizing device 29 and heated by the regenerative heating device 2, it enters the combustion chamber 3 as a cooling medium to regulate the temperature; and after being pressurized by the third carbon dioxide conveying pipeline into the second carbon dioxide pressurizing device 29, it enters the turbine 4 as a cooling medium to reduce the temperature of the turbine 4 blades.

[0100] At the oxygen multi-stage cold compression unit, external oxygen sequentially enters the first oxygen compression device 19, the first oxygen cooling device 22, the second oxygen compression device 20, the second oxygen cooling device 23, the third oxygen compression device 21, and the carbon dioxide oxygen mixed working medium pressurization device 30, and is transformed into high-temperature and high-pressure oxygen with a temperature of 20°C and a pressure of 13.15MPa, which then enters the regenerating heating device 2.

[0101] The combustion flue gas generated by oxygen-enriched combustion enters turbine 4 to do work. The exhaust gas from turbine 4 enters the regenerating heating device 2 and the condensing device 5 for heat exchange, and then enters the gaseous carbon dioxide storage device 6. The molar fraction of oxygen in the oxygen-enriched combustion oxidizer is 30 mol%. The exhaust gas from turbine 4 condenses water vapor into liquid water in the condensing device 5 and separates it. The compression heat stored in the heat storage medium circulation unit is used to supplement the heat of the regenerating heating device 2. The process includes: the heat storage medium in the heat storage medium hot tank 24 is sent to the regenerating heating device 2 by the first transfer pump 25 to release heat, and then enters the heat storage medium cold tank 26 for storage.

[0102] Example 2

[0103] This embodiment provides a direct-fired supercritical carbon dioxide semi-closed energy storage and oxygen recovery system, the schematic diagram of which is shown below. Figure 2 As shown. The direct-fired supercritical carbon dioxide semi-closed energy storage and oxygen recovery system is the same as in Example 1, except that the oxygen recovery bypass pipeline 7 is connected to the outlet of the second oxygen compression device 20.

[0104] In this embodiment, the oxygen recovery bypass pipe 7 is connected to the outlet of the second oxygen compression device 20 because the oxygen pressure at the top of the liquid carbon dioxide storage device 1 is 7 MPa, which is close to the outlet oxygen pressure of the second oxygen compression device 20.

[0105] In this embodiment, the temperature of the oxygen entering the regenerative heating device is 49.5°C, and the pressure is 34.2 MPa.

[0106] Example 3

[0107] This embodiment provides a direct-fired supercritical carbon dioxide semi-closed energy storage and oxygen recovery system, the schematic diagram of which is shown below. Figure 3 As shown. The direct-fired supercritical carbon dioxide semi-closed energy storage and oxygen recovery system is the same as in Example 1, except that the oxygen recovery bypass pipeline 7 is connected to the outlet of the first oxygen compression device 19.

[0108] In this embodiment, the oxygen recovery bypass pipe 7 is connected to the outlet of the first oxygen compression device 19 because the oxygen pressure at the top of the liquid carbon dioxide storage device 1 is 7 MPa, which is close to the outlet oxygen pressure of the first oxygen compression device 19.

[0109] In this embodiment, the temperature of the oxygen entering the regenerative heating device is 54°C, and the pressure is 36.5 MPa.

[0110] As can be seen from Examples 1-3, the direct-fired supercritical carbon dioxide semi-closed energy storage and oxygen recovery system provided by this invention realizes the recovery and utilization of excess oxygen in the flue gas generated by the oxygen-enriched combustion chamber, solving the problem of equipment corrosion caused by excess oxygen, extending the service life of the equipment, and reducing maintenance costs. Furthermore, the recovered oxygen is used as a combustion aid, reducing the oxygen flow rate in the multi-stage oxygen compression unit and decreasing the total power consumption of the oxygen preparation and compressor units. In addition, by connecting the oxygen recovery bypass pipeline to different oxygen compression devices in the multi-stage oxygen compression unit according to the pressure of the recovered oxygen in the liquid carbon dioxide storage device, the stability and flexibility of the system are improved.

[0111] The applicant declares that the detailed structural features of the present invention are illustrated through the above embodiments, but the present invention is not limited to the above detailed structural features, that is, it does not mean that the present invention must rely on the above detailed structural features to be implemented. Those skilled in the art should understand that any improvements to the present invention, equivalent substitutions for the components selected in the present invention, additions of auxiliary components, selection of specific methods, etc., all fall within the protection scope and disclosure scope of the present invention.

[0112] The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited to the specific details in the above embodiments. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solution of the present invention, and these simple modifications all fall within the protection scope of the present invention.

Claims

1. A direct-fired supercritical carbon dioxide semi-closed energy storage and oxygen recovery system, characterized in that, The direct-fired supercritical carbon dioxide semi-closed energy storage and oxygen recovery system includes a circulating multi-stage intercooled compression unit for carbon dioxide, a liquid carbon dioxide storage device, a regenerative heating device, a combustion chamber, a turbine, a condensation device, and a gaseous carbon dioxide storage device. The direct-fired supercritical carbon dioxide semi-closed energy storage and oxygen recovery system also includes an oxygen multi-stage inter-stage cold compression unit connected to the regenerative heating device; the liquid carbon dioxide storage device is connected to the oxygen multi-stage cold compression unit via an oxygen recovery bypass pipeline. The direct-fired supercritical carbon dioxide semi-closed energy storage and oxygen recovery system also includes a heat storage medium circulation unit located between the carbon dioxide multi-stage intercooling and compression unit and the regenerative heating device.

2. The direct-fired supercritical carbon dioxide semi-closed energy storage and oxygen recovery system according to claim 1, characterized in that, The multi-stage inter-stage carbon dioxide cold compression unit includes a carbon dioxide compression device and a carbon dioxide cooling device connected in sequence. The number of carbon dioxide compression devices is at least 3 sets; The number of carbon dioxide cooling devices is at least 3 sets; The first carbon dioxide compression device is connected to the electric motor.

3. The direct-fired supercritical carbon dioxide semi-closed energy storage and oxygen recovery system according to claim 1, characterized in that, A carbon dioxide capture device is also provided between the multi-stage intercooled compression unit for carbon dioxide and the liquid carbon dioxide storage device. A first carbon dioxide pressurization device is provided between the liquid carbon dioxide storage device and the regenerative heating device; The first carbon dioxide pressurizing device is connected to the second carbon dioxide pressurizing device; The first carbon dioxide pressurization device is connected to the regenerative heating device via the first carbon dioxide delivery pipeline, the second carbon dioxide delivery pipeline, and the third carbon dioxide delivery pipeline; The first carbon dioxide delivery pipeline is connected to the multi-stage oxygen cold compression unit; The first carbon dioxide delivery pipeline is equipped with a carbon dioxide-oxygen mixed working fluid pressurization device; The second carbon dioxide delivery pipe is connected to the combustion chamber; The third carbon dioxide delivery pipeline is connected to the turbine.

4. The direct-fired supercritical carbon dioxide semi-closed energy storage and oxygen recovery system according to claim 1, characterized in that, The combustion chamber is connected to a gas fuel compression device; The turbine is connected to the generator; The oxygen recovery bypass pipeline is equipped with a flow metering device. The oxygen multi-stage intercooled compression unit includes an oxygen compression device and an oxygen cooling device connected in sequence. The number of oxygen compression devices is at least 3 sets; The number of oxygen cooling devices is at least two sets.

5. The direct-fired supercritical carbon dioxide semi-closed energy storage and oxygen recovery system according to claim 1, characterized in that, The heat storage medium circulation unit includes a heat storage medium hot tank, a first delivery pump, a heat storage medium cold tank, and a second delivery pump that are connected in a circulation manner. The second delivery pump, the first carbon dioxide cooling device, and the heat storage medium tank are connected in sequence; The first delivery pump, the regenerative heating device, and the heat storage medium cold tank are connected in sequence.

6. A method for direct-fired supercritical carbon dioxide semi-closed energy storage and oxygen recovery, characterized in that, The direct-fired supercritical carbon dioxide semi-closed energy storage and oxygen recovery method is carried out using the direct-fired supercritical carbon dioxide semi-closed energy storage and oxygen recovery system according to any one of claims 1 to 5; the direct-fired supercritical carbon dioxide semi-closed energy storage and oxygen recovery method includes an energy storage process and an energy release process; oxygen recovery is carried out during the energy storage process.

7. The direct-fired supercritical carbon dioxide semi-closed energy storage and oxygen recovery method according to claim 6, characterized in that, The energy storage process includes: the gas in the gaseous carbon dioxide storage device enters the carbon dioxide multi-stage intercooling compression unit and is compressed, the carbon dioxide in the gas becomes liquid carbon dioxide and is stored in the lower part of the liquid carbon dioxide storage device, while the oxygen in the gas remains gaseous and is stored in the top of the liquid carbon dioxide storage device, thus realizing oxygen recovery; the heat of compression of the carbon dioxide multi-stage intercooling compression unit enters the heat storage medium circulation unit for storage.

8. The direct-fired supercritical carbon dioxide semi-closed energy storage and oxygen recovery method according to claim 7, characterized in that, The process by which the heat of compression from the multi-stage intercooled carbon dioxide compression unit enters the heat storage medium circulation unit for storage includes: the heat storage medium cold tank enters the first carbon dioxide cooling device via the second delivery pump to absorb the heat of compression, and then enters the heat storage medium hot tank for storage.

9. The method for direct-fired supercritical carbon dioxide semi-closed energy storage and oxygen recovery according to claim 6, characterized in that, The energy release process includes: liquid carbon dioxide and oxygen in the liquid carbon dioxide storage device are mixed with high-temperature and high-pressure oxygen in the multi-stage cold compression unit, then pressurized by the carbon dioxide-oxygen mixture pressurizing device, heated by the regenerative heating device, and then enter the combustion chamber for oxygen-enriched combustion. The resulting combustion flue gas enters the turbine to do work, and the turbine exhaust gas enters the regenerative heating device and the condensation device in sequence for heat exchange before entering the gaseous carbon dioxide storage device; the compression heat stored in the heat storage medium circulation unit is used to supplement the heat of the regenerative heating device. The temperature of the oxygen entering the regenerative heating device is 20-60℃; The pressure of the oxygen entering the regenerative heating device is 10-36.5 MPa.

10. The method for direct-fired supercritical carbon dioxide semi-closed energy storage and oxygen recovery according to claim 9, characterized in that, The liquid carbon dioxide in the liquid carbon dioxide storage device enters the regenerative heating device specifically in the following ways: after being pressurized by a first carbon dioxide pressurizing device, the liquid carbon dioxide is mixed with high-temperature and high-pressure oxygen from a multi-stage intercooled compression unit via a first carbon dioxide conveying pipeline as a combustion aid. After being pressurized by a carbon dioxide-oxygen mixed working fluid pressurizing device, it enters the regenerative heating device for heating and then enters the combustion chamber for oxygen-enriched combustion. After being pressurized by a second carbon dioxide conveying pipeline into a second carbon dioxide pressurizing device and then heated in the regenerative heating device, it enters the combustion chamber as a cooling medium to regulate the temperature. Finally, after being pressurized by a third carbon dioxide conveying pipeline into a second carbon dioxide pressurizing device, it enters the turbine as a cooling medium to reduce the temperature of the turbine blades. The oxygen mole fraction in the oxygen-enriched combustion accelerator is 10 mol%-30 mol%. The turbine exhaust steam condenses water vapor into liquid water in a condensation unit and then separates it. The process of using the compressed heat stored in the heat storage medium circulation unit to supplement the heat of the regenerative heating device includes: the heat storage medium in the heat storage medium hot tank is sent into the regenerative heating device by the first transfer pump to release heat, and then enters the heat storage medium cold tank for storage.

Images