Open type carbon dioxide energy storage system and carbon dioxide energy storage method

Abstract

The invention relates to an open type carbon dioxide energy storage system and a carbon dioxide energy storage method. The open type carbon dioxide energy storage system comprises a gas compression device, a first expansion unit, a gas-liquid separation tank, a main cooler, a circulating compressor unit, a liquid storage tank, a regenerator and an energy release device. An inlet of the gas compression device is used for being communicated with an air discharging outlet of a coal chemical device, and an outlet of the gas compression device is communicated with an inlet of the first expansion unit and a hot side inlet of the main cooler. A hot side outlet of the main cooler is communicated with an inlet of the liquid storage tank; an outlet of the first expansion unit communicates with an inlet of the gas-liquid separation tank, and a gas outlet of the gas-liquid separation tank communicates with a cold side inlet of the main cooler. A cold side outlet of the main cooler communicates with an inlet of the circulating compressor unit, and an outlet of the circulating compressor unit communicates with an inlet of the gas compression device. The system and the method disclosed by the invention have relatively high energy storage efficiency and energy utilization rate.

Description

Technical Field

[0001] The present application relates to the field of energy storage, and in particular, to an open carbon dioxide energy storage system and a carbon dioxide energy storage method. Background Art

[0002] Carbon dioxide energy storage (CDES) is an emerging energy storage technology that is based on the principle of compressed gas energy storage, uses carbon dioxide (CO2) as the working medium, and achieves the storage and release of electrical energy through compression and expansion processes. The core principle of carbon dioxide energy storage technology is to use the physical phase change of CO2 at different pressures and temperatures to store and release energy.

[0003] This technology mainly includes two stages: energy storage process and energy release process. When the grid load is low and the electricity price is cheap, electricity is used to drive the compressor to extract CO2 from the low-pressure storage tank and compress it to a supercritical state or liquid state. The heat energy generated during the compression process is stored in the heat storage device through a heat exchanger. The compressed CO2 and the stored heat energy together constitute the stored energy. When the grid load is high and the electricity price is expensive, the CO2 in the high-pressure storage tank is released, and the CO2 is heated to a supercritical state through a reheater using the previously stored heat energy. Then, the supercritical CO2 expands through the turbine to do work, driving the generator to generate electricity, thereby converting the stored energy into electrical energy. Due to its unique advantages, carbon dioxide energy storage technology has broad application potential in many fields.

[0004] CN115142924A discloses a carbon dioxide energy storage system with a cold storage device, including: a liquid storage part for storing liquid carbon dioxide; a cold storage heat exchange part, whose hot side is connected to the inlet end of the liquid storage part, and whose cold side is connected to the outlet end of the liquid storage part; a compressor unit, whose outlet end is connected to the hot side of the cold storage heat exchange part, and a normal temperature cooler is installed between the compressor unit and the liquid storage part; an expansion unit, whose inlet end is connected to the cold side of the cold storage heat exchange part. By setting the cold storage heat exchange part, part of the cold energy is stored in the cold storage heat exchange part before the carbon dioxide enters the expansion unit, and the cold energy in the cold storage heat exchange part is absorbed before the carbon dioxide is stored in the liquid storage part to cool down, which can reduce the difficulty of the carbon dioxide expansion process and compression process, reduce the operating power of the expansion unit and the compressor unit, and improve the energy storage efficiency of the open carbon dioxide energy storage system. However, in this technical solution, part of the cooling capacity required for the CO2 liquefaction process is provided by the gasification of the stored liquid CO2, which causes energy waste and reduces the energy storage efficiency. Summary of the invention

[0005] The purpose of the present disclosure is to provide an open carbon dioxide energy storage system and a carbon dioxide energy storage method, which have high energy storage efficiency and energy utilization rate.

[0006] In order to achieve the above-mentioned object, the first aspect of the present disclosure provides an open carbon dioxide energy storage system, the system comprising a gas compression device, a first expansion unit, a gas-liquid separation tank, a main cooler, a circulation compressor unit, a liquid storage tank and an energy release device; The inlet of the gas compression device is used to communicate with the venting air outlet of the coal chemical device, and the outlet of the gas compression device is respectively communicated with the inlet of the first expansion unit and the hot side inlet of the main cooler; the hot side outlet of the main cooler is communicated with the inlet of the liquid storage tank; the outlet of the first expansion unit is communicated with the inlet of the gas-liquid separation tank, and the gas outlet of the gas-liquid separation tank is communicated with the cold side inlet of the main cooler; the cold side outlet of the main cooler is communicated with the inlet of the circulation compressor unit, and the outlet of the circulation compressor unit is communicated with the inlet of the gas compression device; An energy release device is used to release energy in the liquid carbon dioxide and provide cooling capacity for the main cooler.

[0007] Optionally, the gas compression device includes a main compressor unit and a gas booster unit; The inlet of the main compressor unit is used to communicate with the venting air outlet of the coal chemical plant, the outlet of the main compressor unit is communicated with the inlet of the gas booster unit, the outlet of the gas booster unit is communicated with the inlet of the first expansion unit and the hot side inlet of the main cooler, the outlet of the first expansion unit is communicated with the inlet of the gas-liquid separation tank, the gas outlet of the gas-liquid separation tank is communicated with the cold side inlet of the main cooler; the cold side outlet of the main cooler is communicated with the inlet of the circulation compressor unit, and the outlet of the circulation compressor unit is communicated with the inlet of the gas booster unit; The first expansion unit performs work to drive the gas booster unit.

[0008] Optionally, the energy release device includes a vaporizer, a first heater and a second expansion unit; The gas outlet of the liquid storage tank is communicated with the cold side inlet of the main cooler, the liquid outlet of the liquid storage tank is communicated with the inlet of the vaporizer, the gas outlet of the vaporizer is communicated with the inlet of the first heater, and the outlet of the first heater is communicated with the inlet of the second expansion unit; The cold storage device is used to recover the cold energy of the carbon dioxide liquid gasification process and provide cold energy for the main cooler; Preferably, the cold side outlet of the main cooler is communicated with the inlet of the first heater, and the gas outlet of the second expansion unit is vented or used to communicate with the inlet of the carbon dioxide concentration device.

[0009] Optionally, the system further comprises a third expander unit and a second heater; The inlet of the second heater is communicated with the cold side outlet of the main cooler, the outlet of the second heater is communicated with the inlet of the third expansion unit, and the gas outlet of the third expansion unit is vented.

[0010] Optionally, the system further comprises a heat accumulator, which is used to store compression heat generated by the main compressor unit, the gas booster unit and the circulating compressor unit, and supply heat to the first heater and / or the second heater; Preferably, coolers are respectively provided at the outlets of each compressor stage of the gas compression device and the circulation compressor unit, and all compression heat of the coolers is stored in the heat accumulator.

[0011] Optionally, the liquid outlet of the gas-liquid separation tank is communicated with the cold side inlet of the main cooler.

[0012] The second aspect of the present disclosure provides a method for storing carbon dioxide energy using the system provided in the first aspect of the present disclosure, the method comprising an energy storage process and an energy release process; In the energy storage process, the carbon dioxide-rich gas from the coal chemical plant is introduced into the gas compression device for pressurization to obtain pressurized carbon dioxide-rich gas; Introducing part of the pressurized carbon dioxide-rich gas into the first expansion unit for expansion refrigeration and then into the gas-liquid separation tank for gas-liquid separation, introducing the carbon dioxide gas obtained by gas-liquid separation into the cold side of the main cooler as a cooling medium to release cold energy, and introducing the carbon dioxide gas after cold release into the circulation compressor unit for pressurization and then returning to the gas compression device; Directly introducing the remaining portion of the pressurized carbon dioxide-rich gas into the hot side of the main cooler for cooling and liquefaction, and introducing the obtained low-temperature carbon dioxide liquid into the liquid storage tank for storage; In the energy release process, the energy in the liquid carbon dioxide is released through the energy release device, and provides cooling capacity for the main cooler.

[0013] Optionally, the gas compression device includes a main compressor unit and a gas booster unit, and the energy storage process further includes: Introducing the carbon dioxide-rich gas from the coal chemical plant into the main compressor unit and the gas booster unit in sequence for pressurization to obtain the pressurized carbon dioxide-rich gas; The carbon dioxide gas after cooling is sequentially introduced into the circulating compressor unit for pressurization and then returned to the gas booster unit; Preferably, the energy consumption of the main compressor unit and the circulating compressor unit is provided by green electricity, and the first expansion unit performs work to drive the gas booster unit.

[0014] Optionally, the energy release device includes a vaporizer, a first heater and a second expansion unit; The releasing of energy in the liquid carbon dioxide by the energy release device comprises: introducing the carbon dioxide liquid in the liquid storage tank into a vaporizer for gasification, introducing the high-pressure carbon dioxide gas obtained by gasification into a first heater for heating, and introducing the high-temperature and high-pressure carbon dioxide gas obtained by heating into a second expansion unit for performing work and outputting electrical energy to obtain concentrated carbon dioxide gas; The cold storage device collects cold energy in the gasifier; wherein the cold energy of the cold storage device provides cold energy for the main cooler during the energy storage process; Preferably, the non-condensable gas at the top of the liquid storage tank enters the cold side of the main cooler to release cold energy, and then merges with the high-pressure carbon dioxide gas at the outlet of the gasifier to enter the first heater together; Preferably, the pressure of the liquid storage tank is 4.0-9.0 MPa, and the temperature is -40°C to 25°C; more preferably, the pressure is 6-7 MPa, and the temperature is -10°C to 0°C.

[0015] Optionally, the energy release device further includes a second heater and a second expansion unit; The energy release process also includes: introducing the non-condensable gas in the liquid storage tank into the cold side of the main cooler as a cooling medium to release cold energy, introducing the non-condensable gas after the release of cold energy into the second heater for heating, introducing the high-temperature non-condensable gas obtained by heating into the second expansion unit to perform work and output electrical energy, and venting the outlet gas of the second expansion unit.

[0016] Optionally, the energy storage process further comprises: introducing the low-pressure carbon dioxide liquid obtained by gas-liquid separation in the gas-liquid separation tank as a cooling medium into the cold side of the main cooler, and introducing the circulating compressor unit after releasing the cooling; Preferably, the pressure of the gas-liquid separation tank is 0.5-1.0 MPa, and the cooling temperature is -56°C to -40°C; more preferably, the pressure is 0.8-1.0 MPa, and the cooling temperature is -45°C to -40°C.

[0017] Optionally, the method further includes: a cooler is provided at the outlet of each compressor stage of the gas compression device and the circulation compressor unit, and compression heat is stored through a heat accumulator, and the heat accumulator provides heat for the first heater and / or the second heater.

[0018] Through the above technical scheme, in the system disclosed in the present invention, an expansion refrigeration cycle is arranged before the main cooler, part of the high-pressure carbon dioxide gas is introduced into the expansion refrigeration cycle and then into the main cooler, and the other part is directly introduced into the main cooler, thereby improving the energy storage efficiency and energy utilization rate.

[0019] Other features and advantages of the present disclosure will be described in detail in the following detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The accompanying drawings are used to provide a further understanding of the present disclosure and constitute a part of the specification. Together with the following specific embodiments, they are used to explain the present disclosure but do not constitute a limitation of the present disclosure. In the accompanying drawings: Figure 1 It is a structural schematic diagram of a specific implementation of the open carbon dioxide energy storage system disclosed in the present invention; Figure 2 It is a structural schematic diagram of another specific implementation of the open carbon dioxide energy storage system disclosed in the present invention; Figure 3 It is a structural schematic diagram of another specific implementation of the open carbon dioxide energy storage system disclosed in the present invention; Figure 4 This is a schematic diagram of the structure of a traditional carbon dioxide energy storage system.

[0021] Description of Reference Numerals DETAILED DESCRIPTION

[0022] The specific implementation of the present disclosure is described in detail below in conjunction with the accompanying drawings. It should be understood that the specific implementation described herein is only used to illustrate and explain the present disclosure, and is not used to limit the present disclosure.

[0023] like Figure 1-Figure 3 As shown, the present disclosure provides an open carbon dioxide energy storage system, which includes a gas compression device, a first expansion unit 5, a gas-liquid separation tank 6, a main cooler 7, a circulating compressor unit 9, a liquid storage tank 8, a cold storage device 11 and an energy release device; the inlet of the gas compression device is used to communicate with the venting air outlet of the coal chemical device, and the outlet of the gas compression device is respectively communicated with the inlet of the first expansion unit 5 and the hot side inlet of the main cooler 7; the hot side outlet of the main cooler 7 is communicated with the inlet of the liquid storage tank 8; the outlet of the first expansion unit 5 is communicated with the inlet of the gas-liquid separation tank 6, and the gas outlet of the gas-liquid separation tank 6 is communicated with the cold side inlet of the main cooler 7; the cold side outlet of the main cooler 7 is communicated with the inlet of the circulating compressor unit 9, and the outlet of the circulating compressor unit 9 is communicated with the inlet of the gas compression device; the energy release device is used to release energy in liquid carbon dioxide, and the cold storage device collects the cold energy generated by the energy release device and provides cold energy for the main cooler 7.

[0024] During the energy storage and release process of the disclosed system, the exogenous carbon dioxide-rich gas is mixed with the circulating carbon dioxide gas from the circulating compressor unit 9 and pressurized by the gas compression device, and then the gas is divided into two paths. One path of gas directly enters the hot side of the main cooler 7, and enters the gas-liquid separation tank 6 after being cooled and liquefied; the other path of gas enters the first expansion unit 5 for expansion and cooling before entering the gas-liquid separation tank 6. The gas at the top of the gas-liquid separation tank 6 enters the cold side of the main cooler 7 to release cold energy, which can provide cold energy for the carbon dioxide liquefaction process and improve the energy storage efficiency. The gas at the outlet of the cold side of the main cooler enters the circulating compressor unit 9 for re-pressurization and enters the next cycle; the carbon dioxide-rich liquid at the outlet of the cold side of the main cooler enters the energy release device for energy storage. During the energy release process, the carbon dioxide-rich liquid expands in the energy release device to do work and becomes carbon dioxide-rich gas. The work done by the carbon dioxide-rich gas can be used to drive an external generator to generate electricity.

[0025] In the system disclosed in the present invention, an expansion refrigeration cycle is arranged before the main cooler, and part of the high-pressure carbon dioxide gas is introduced into the expansion refrigeration cycle and then introduced into the main cooler, so that the cold released by the expansion and cooling of the part of the high-pressure carbon dioxide gas can be used as one of the sources of cold for the main cooler, so as to provide cold for the carbon dioxide liquefaction process, thereby avoiding the energy waste caused by using the stored liquid carbon dioxide gasification refrigeration to provide cold for CO2 liquefaction, and at the same time, the remaining part of the high-pressure carbon dioxide gas is directly introduced into the main cooler, thereby improving the energy storage efficiency and energy utilization rate. In addition, in this embodiment, no low-pressure gas storage is required, which significantly reduces the area of ​​the energy storage system.

[0026] The present disclosure does not limit the specific type of the main cooler, for example, it can be a plate type, a shell and tube type, a falling film type or an immersion bath type.

[0027] In a specific embodiment of the present disclosure, the gas compression device includes a main compressor unit 1 and a gas booster unit 3; the inlet of the main compressor unit 1 is used to communicate with the venting air outlet of the coal chemical plant, the outlet of the main compressor unit 1 is communicated with the inlet of the gas booster unit 3, the outlet of the gas booster unit 3 is communicated with the inlet of the first expansion unit 5 and the hot side inlet of the main cooler 7, the outlet of the first expansion unit 5 is communicated with the inlet of the gas-liquid separation tank 6, the gas outlet of the gas-liquid separation tank 6 is communicated with the cold side inlet of the main cooler 7; the cold side outlet of the main cooler 7 is communicated with the inlet of the circulation compressor unit 9, and the outlet of the circulation compressor unit 9 is communicated with the inlet of the gas booster unit 3. In this embodiment, during the energy storage and release process of the system of the present disclosure, the exogenous carbon dioxide-rich gas is compressed by the main compressor unit 1 and mixed with the circulating carbon dioxide gas from the circulating compressor unit 9, and after entering the gas booster unit 3 for re-pressurization, the gas is divided into two paths. This implementation method improves compression efficiency and saves energy consumption by pressurizing the exogenous carbon dioxide-rich gas twice and compressing the circulating carbon dioxide gas once.

[0028] In a specific embodiment of the present disclosure, the first expansion unit 5 performs work to drive the gas booster unit 3, which can further improve energy utilization.

[0029] In a specific embodiment of the present disclosure, the energy release device includes a gasifier 12, a first heater 14 and a second expansion unit 17; the gas outlet of the liquid storage tank 8 is connected to the cold side inlet of the main cooler 7, the cold side outlet of the main cooler 7 is also connected to the inlet of the first heater 14, the liquid outlet of the liquid storage tank 8 is connected to the inlet of the gasifier 12, the gas outlet of the gasifier 12 is connected to the inlet of the first heater 14, and the outlet of the first heater 14 is connected to the inlet of the second expansion unit 17; the cold storage device is used to recover the cold energy of the carbon dioxide liquid gasification process and provide cold energy for the main cooler. In this embodiment, the carbon dioxide liquid at the bottom of the liquid storage tank 8 first enters the gasifier 12 to be gasified into high-pressure carbon dioxide gas, and the non-condensable gas at the top of the liquid storage tank 8 enters the cold side of the main cooler 7 to release cold energy, and then merges with the high-pressure carbon dioxide gas at the outlet of the gasifier 12. The mixed gas is heated by the first heater 14 and enters the second expansion unit 17 to perform work, so as to drive an external steam turbine to output electrical energy to the outside. The cold energy recovered from the carbon dioxide liquid gasification process is stored in the cold storage device and can be used as the cold energy source for the main cooler.

[0030] like Figure 2 As shown, in a specific embodiment of the present disclosure, the cold side outlet of the main cooler 7 is connected to the inlet of the first heater 14, and the gas outlet of the second expansion unit 17 is vented or used to connect to the inlet of the carbon dioxide concentration device.

[0031] like Figure 1 As shown, in a specific embodiment of the present disclosure, the system further includes a third expansion unit 16 and a second heater 15; the inlet of the second heater 15 is connected to the cold side outlet of the main cooler 7, the outlet of the second heater 15 is connected to the inlet of the third expansion unit 16, and the gas outlet of the third expansion unit 16 is vented. In this embodiment, by setting the third expansion unit 16 and the second heater 15, the non-condensable gas at the top of the liquid storage tank 8 is connected to the cold side inlet of the main cooler 7, and the non-condensable gas at the cold side outlet of the main cooler 7 is heated by the second heater 15, and then enters the third expansion unit 16 to perform work to output electrical energy to the outside, and the non-condensable gas at the outlet of the third expansion unit 16 is directly vented, so that the carbon dioxide-rich gas can be concentrated to meet the needs of subsequent processes.

[0032] In a specific embodiment of the present disclosure, the system further includes a heat accumulator 13, which is used to store the compression heat generated by the main compressor unit 1, the gas booster unit 3 and the circulating compressor unit 9, and supply heat to the first heater 14 and / or the second heater 15. In this embodiment, by providing a heat accumulator in the system, the compression heat generated by the main compressor unit, the gas booster unit and the circulating compressor unit can be recycled and utilized, and heat can be supplied to the first heater 14 and / or the second heater 15, which can further improve the energy utilization rate.

[0033] In a specific embodiment of the present disclosure, coolers are respectively provided at the outlets of each compressor stage of the gas compression device and the circulating compressor unit 9, and the compression heat of all the coolers is stored by the heat accumulator 13. In a preferred embodiment, the system further comprises a first cooler 2, a second cooler 4 and a third cooler 10; the outlet of the main compressor unit 1 is connected to the inlet of the first cooler 2, and the outlet of the first cooler 2 is connected to the inlet of the gas booster unit 3; the outlet of the circulating compressor unit 9 is connected to the inlet of the third cooler 10, and the outlet of the third cooler 10 is connected to the inlet of the gas booster unit 3; the outlet of the gas booster unit 3 is connected to the inlet of the second cooler 4, and the outlet of the second cooler 4 is connected to the inlet of the first expansion unit 5 and the hot side inlet of the main cooler 7.

[0034] like Figure 3 As shown, in a specific embodiment of the present disclosure, the liquid outlet of the gas-liquid separation tank 6 is connected to the cold side inlet of the main cooler. In the embodiment, after the carbon dioxide liquid at the bottom of the gas-liquid separation tank 6 enters the cold side of the main cooler 7 to release cold energy, it is sent out from the cold side outlet of the main cooler 7 and enters the circulation compressor unit 9. In this embodiment, the required expansion refrigeration cycle volume is relatively small.

[0035] According to the present disclosure, the main compressor unit 1, the gas booster unit 3, the circulating compressor unit 5, the first expansion unit, the second expansion unit and the third expansion unit all adopt a multi-stage series connection. In a specific embodiment of the present disclosure, the number of compressors in the main compressor unit 1 is 1-3; the number of boosters in the gas booster unit 3 is 1-2; the number of expansion machines in the first expansion unit 5 is 1-2; the number of compressors in the circulating compressor unit 9 is 1-2; the number of expansion machines in the third expansion unit 16 is 1-3; the number of expansion machines in the second expansion unit 17 is 1-3.

[0036] The second aspect of the present disclosure provides a method for storing carbon dioxide energy using the system provided by the first aspect of the present disclosure, the method comprising an energy storage process and an energy release process; in the energy storage process, the carbon dioxide-rich gas from the coal chemical plant is introduced into the gas compression device for pressurization to obtain pressurized carbon dioxide-rich gas; part of the pressurized carbon dioxide-rich gas is introduced into the first expansion unit 5 for expansion and refrigeration, and then introduced into the gas-liquid separation tank 6 for gas-liquid separation, the carbon dioxide gas obtained by gas-liquid separation is introduced into the cold side of the main cooler 7 as a cooling medium to release cold energy, the carbon dioxide gas after cold release is introduced into the circulation compressor unit 9 for pressurization, and then returned to the gas compression device; the remaining part of the pressurized carbon dioxide-rich gas is directly introduced into the hot side of the main cooler 7 for cooling and liquefaction, and the obtained low-temperature carbon dioxide liquid is introduced into the liquid storage tank 8 for storage; in the energy release process, the energy in the liquid carbon dioxide is released by the energy release device, and cold energy is provided to the main cooler 7.

[0037] According to the present disclosure, the carbon dioxide-rich gas from the coal chemical plant can be vented air from the coal chemical plant. The method disclosed in the present disclosure has high energy storage efficiency and energy utilization rate.

[0038] In a specific embodiment of the present disclosure, the gas compression device includes a main compressor unit 1 and a gas booster unit 3, and the energy storage process also includes: introducing the carbon dioxide-rich gas from the coal chemical plant into the main compressor unit 1 and the gas booster unit 3 in sequence for pressurization to obtain pressurized carbon dioxide-rich gas; introducing part of the pressurized carbon dioxide-rich gas into the first expansion unit 5 for expansion and refrigeration, and then introducing it into the gas-liquid separation tank 6 for gas-liquid separation, introducing the carbon dioxide gas obtained by gas-liquid separation into the cold side of the main cooler 7 as a cooling medium, and introducing the released carbon dioxide gas into the circulation compressor unit 9 in sequence for pressurization and then returning it to the gas booster unit 3.

[0039] In a specific embodiment of the present disclosure, the energy consumption of the main compressor unit 1 and the circulating compressor unit 9 is provided by green electricity, and the first expansion unit 5 performs work to drive the gas booster unit 3.

[0040] In a specific embodiment of the present disclosure, the pressure of the gas-liquid separation tank 6 is 0.5-1.0 MPa, and the cooling temperature is -56°C to -40°C; preferably, the pressure is 0.8-1.0 MPa, and the cooling temperature is -45°C to -40°C.

[0041] In a specific embodiment of the present disclosure, the energy release device includes a vaporizer 12, a first heater 14 and a second expansion unit 17; the energy release device releases the energy in the liquid carbon dioxide including: introducing the carbon dioxide liquid in the liquid storage tank 8 into the vaporizer 12 for gasification, introducing the high-pressure carbon dioxide gas obtained by gasification into the first heater 14 for heating, introducing the high-temperature and high-pressure carbon dioxide gas obtained by heating into the second expansion unit 17 to perform work and output electrical energy to obtain concentrated carbon dioxide gas; allowing the cold storage device 11 to collect the cold in the vaporizer 12; wherein the cold storage device provides cold for the main cooler 7 during the energy storage process; wherein the pressure of the liquid storage tank 8 is 4.0-9.0MPa, and the temperature is -40°C to 25°C; preferably, the pressure is 6-7MPa, and the temperature is -10°C to 0°C.

[0042] In a specific embodiment of the present disclosure, the energy release device also includes a second heater 15 and a second expansion unit 16; the energy release process also includes: introducing the non-condensable gas in the liquid storage tank 8 into the cold side of the main cooler 7 as a cooling medium to release cold energy, introducing the non-condensable gas after the release of cold energy into the second heater 15 for heating, introducing the high-temperature non-condensable gas obtained by heating into the second expansion unit 16 to perform work and output electrical energy, and venting the outlet gas of the second expansion unit 16.

[0043] In a specific embodiment of the present disclosure, the non-condensable gas at the top of the liquid storage tank 8 enters the cold side of the main cooler 7 to release cold energy, and then merges with the high-pressure carbon dioxide gas at the outlet of the gasifier 12 and enters the first heater 14 together.

[0044] In a specific embodiment of the present disclosure, the energy storage process also includes: introducing the low-pressure carbon dioxide liquid obtained by gas-liquid separation in the gas-liquid separation tank 6 into the cold side of the main cooler 7 as a cooling medium, and introducing it into the circulation compressor unit 9 after releasing the cold.

[0045] In a specific embodiment of the present disclosure, the method further includes: coolers are respectively provided at the outlets of each compressor stage of the gas compression device and the circulation compressor unit 9, and compression heat is stored through a heat accumulator 13, and the heat accumulator 13 provides heat for the first heater 14 and / or the second heater 15.

[0046] In a specific embodiment of the present disclosure, the electric energy required by the main compressor unit 1 and the circulating compressor unit 9 is provided by green electricity.

[0047] The present disclosure is further illustrated below by way of examples, but the present disclosure is not limited thereby.

[0048] The carbon dioxide-rich gas in Example 1-2 is typical coal chemical CO2 venting air, and its composition and properties are shown in Table 1.

[0049] Table 1

[0050] Example 1 This embodiment provides a Figure 1 The open carbon dioxide energy storage system shown includes a main compressor unit 1, a gas booster unit 3, a first expansion unit 5, a gas-liquid separation tank 6, a main cooler 7, a circulating compressor unit 9, a liquid storage tank 8, a gasifier 12, a first heater 14, a second expansion unit 17, a first cooler 2, a second cooler 4 and a third cooler 10, a third expansion unit 16 and a second heater 15, and a heat accumulator 13.

[0051] The outlet of the main compressor unit 1 is connected to the inlet of the first cooler 2, and the outlet of the first cooler 2 is connected to the inlet of the gas booster unit 3; the outlet of the gas booster unit 3 is connected to the inlet of the second cooler 4, and the outlet of the second cooler 4 is connected to the inlet of the first expansion unit 5 and the hot side inlet of the main cooler 7. The outlet of the first expansion unit 5 is connected to the inlet of the gas-liquid separation tank 6, and the gas outlet of the gas-liquid separation tank 6 is connected to the cold side inlet of the main cooler 7; The cold side outlet of the main cooler 7 is communicated with the inlet of the circulating compressor unit 9, the outlet of the circulating compressor unit 9 is communicated with the inlet of the third cooler 10, and the outlet of the third cooler 10 is communicated with the inlet of the gas booster unit 3; the hot side outlet of the main cooler 7 is communicated with the inlet of the liquid storage tank 8, the gas outlet of the liquid storage tank 8 is communicated with the cold side inlet of the main cooler 7, the cold side outlet of the main cooler 7 is communicated with the inlet of the second heater 15, and the outlet of the second heater 15 is communicated with the inlet of the third expansion unit 16; the liquid outlet of the liquid storage tank 8 is communicated with the inlet of the vaporizer 12, the outlet of the vaporizer 12 is communicated with the inlet of the first heater 14, and the outlet of the first heater 14 is communicated with the inlet of the second expansion unit 17; The heat accumulator 13 is used to store the compression heat generated by the main compressor unit 1, the gas booster unit 3 and the circulating compressor unit 9, and to supply heat to the first heater 14 and the second heater 15. The cold accumulator 11 is used to recover the cold energy of the carbon dioxide liquid gasification process and provide cold energy to the main cooler 7.

[0052] The high-pressure, near-normal-temperature carbon dioxide energy storage process is carried out in this system, as follows. The relevant parameters of the energy storage process are shown in Table 2, and the composition of the discharged non-condensable gas is shown in Table 3: In the energy storage process, the carbon dioxide-rich gas enters the main compressor unit 1 for compression and is cooled by the first cooler 2. It is mixed with the circulating carbon dioxide gas from the circulating compressor unit 9 and cooled by the third cooler 10, and enters the gas booster unit 3 for re-pressurization and cooling by the second cooler 4. The gas is divided into two paths. One path of gas directly enters the hot side of the main cooler 7 for cooling and liquefaction. The liquefied carbon dioxide-rich gas enters the gas-liquid separation tank 6; the other path of gas enters the first expansion unit 5 for expansion and cooling and then enters the gas-liquid separation tank 6. The gas at the top of the gas-liquid separation tank 6 enters the cold side of the main cooler 7 to release cold energy, providing cold energy for the carbon dioxide liquefaction process. The liquid at the bottom of the gas-liquid separation tank 6 enters the cold side of the main cooler, and is compressed by the circulating compressor unit 9 after releasing cold energy. The gas at the outlet of the cold side of the main cooler 7 enters the circulating compressor unit 9 for re-pressurization and cooling by the third cooler 10, and then enters the gas booster unit 3 for pressurization and the next cycle to complete energy storage. The first expansion unit 5 performs work to drive the gas booster unit 3.

[0053] In the energy release process, the carbon dioxide-rich liquid at the cold side outlet of the main cooler 7 enters the liquid storage tank 8. The carbon dioxide liquid at the bottom of the liquid storage tank 8 first enters the vaporizer 12 to be vaporized into high-pressure carbon dioxide gas. The high-pressure carbon dioxide gas is heated by the first heater 14 and enters the second expansion unit 17 to perform work. The second expansion unit 17 performs work to drive an external steam turbine to output electrical energy. After the non-condensable gas at the top of the liquid storage tank 8 enters the cold side of the main cooler 7 to release cold energy, the non-condensable gas is heated by the second heater 15 and then enters the third expansion unit 16. The third expansion unit 16 performs work to drive an external steam turbine to output electrical energy, and the non-condensable gas is discharged. The cold energy recovered from the process of gasifying the carbon dioxide liquid to form high-pressure carbon dioxide gas is stored in the cold storage device 11 and supplies cold energy to the main cooler.

[0054] Example 2 The same system and the same method as in Example 1 are used to perform medium-high pressure and low temperature carbon dioxide energy storage, the only difference being that the relevant parameters of the energy storage process are different, as shown in Table 4, and the composition of the discharged non-condensable gas is shown in Table 5.

[0055] Comparative Example 1 The working principle of traditional carbon dioxide energy storage system is as follows Figure 4 shown. Energy storage process: CO2 gas on the energy storage side is compressed to a supercritical state by the compressor 20, and the compression heat is absorbed by the recooler 21. The absorbed compression heat is stored in the heat storage tank 22, and the liquid CO2 is stored in the high-pressure LCO2 storage tank 25, that is, the electrical energy is stored in the form of heat energy and potential energy. Energy release process: The liquid CO2 in the high-pressure LCO2 storage tank 25 is heated by the reheater 23, and the released cold is stored in the cold storage tank 24 and enters the turbine expander 26 for expansion, driving the turbine to generate electricity, that is, converting heat energy and potential energy into electrical energy output. The CO2 gas drawn out by the turbine expander 26 is stored in the low-pressure GCO2 storage tank 27.

[0056] The operating fluid is liquid carbon dioxide with a purity of more than 99.9%, and the system is a closed cycle. The low-pressure side uses a gas storage warehouse to store slightly positive pressure and room temperature carbon dioxide gas. The gas storage warehouse requires flat and neat land, accounting for 60% of the total area of ​​the device. The high-pressure side uses a high-pressure liquid storage tank to store 6-8MPa pressure and room temperature carbon dioxide liquid. The system operation requires circulating cooling water, and the water system also uses a closed cycle. The system design efficiency is 70%±5%.

[0057] Table 2

[0058] Table 3

[0059] Table 4

[0060] Table 5

[0061] It can be seen from the above that the open carbon dioxide energy storage system and carbon dioxide energy storage method disclosed in the present invention have high energy storage efficiency and energy utilization rate.

[0062] The preferred embodiments of the present disclosure are described in detail above in conjunction with the accompanying drawings; however, the present disclosure is not limited to the specific details in the above embodiments. Within the technical concept of the present disclosure, a variety of simple modifications can be made to the technical solution of the present disclosure, and these simple modifications all fall within the protection scope of the present disclosure.

[0063] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, the present disclosure will not further describe various possible combinations.

[0064] In addition, various embodiments of the present disclosure may be arbitrarily combined, and as long as they do not violate the concept of the present disclosure, they should also be regarded as the contents disclosed by the present disclosure.

Claims

1. An open carbon dioxide energy storage system, characterized in that: The system comprises a gas compression device, a first expansion unit (5), a gas-liquid separation tank (6), a main cooler (7), a circulating compressor unit (9), a liquid storage tank (8), a cold storage device (11) and an energy release device; The inlet of the gas compression device is used to communicate with the venting air outlet of the coal chemical device, and the outlet of the gas compression device is respectively communicated with the inlet of the first expansion unit (5) and the hot side inlet of the main cooler (7); the hot side outlet of the main cooler (7) is communicated with the inlet of the liquid storage tank (8); the outlet of the first expansion unit (5) is communicated with the inlet of the gas-liquid separation tank (6), and the gas outlet of the gas-liquid separation tank (6) is communicated with the cold side inlet of the main cooler (7); the cold side outlet of the main cooler (7) is communicated with the inlet of the circulation compressor unit (9), and the outlet of the circulation compressor unit (9) is communicated with the inlet of the gas compression device; The energy release device is used to release energy in liquid carbon dioxide, and the cold storage device collects cold energy generated by the energy release device and provides cold energy for the main cooler (7).

2. The carbon dioxide energy storage system according to claim 1, characterized in that: The gas compression device comprises a main compressor unit (1) and a gas booster unit (3); The inlet of the main compressor unit (1) is used to communicate with the venting air outlet of the coal chemical plant, the outlet of the main compressor unit (1) is communicated with the inlet of the gas booster unit (3), the outlet of the gas booster unit (3) is communicated with the inlet of the first expansion unit (5) and the hot side inlet of the main cooler (7), the outlet of the first expansion unit (5) is communicated with the inlet of the gas-liquid separation tank (6), the gas outlet of the gas-liquid separation tank (6) is communicated with the cold side inlet of the main cooler (7); the cold side outlet of the main cooler (7) is communicated with the inlet of the circulation compressor unit (9), and the outlet of the circulation compressor unit (9) is communicated with the inlet of the gas booster unit (3); The first expansion unit (5) performs work to drive the gas booster unit (3).

3. The carbon dioxide energy storage system according to claim 2, characterized in that: The energy release device comprises a vaporizer (12), a first heater (14) and a second expansion unit (17); The gas outlet of the liquid storage tank (8) is communicated with the cold side inlet of the main cooler (7), the liquid outlet of the liquid storage tank (8) is communicated with the inlet of the vaporizer (12), the gas outlet of the vaporizer (12) is communicated with the inlet of the first heater (14), and the outlet of the first heater (14) is communicated with the inlet of the second expansion unit (17); The cold storage device (11) is used to recover cold energy during the gasification process of carbon dioxide liquid and to provide cold energy for the main cooler (7); Preferably, the cold side outlet of the main cooler (7) is connected to the inlet of the first heater (14), and the gas outlet of the second expansion unit (17) is vented or used to connect to the inlet of the carbon dioxide concentration device.

4. The carbon dioxide energy storage system according to claim 2, characterized in that: The system further comprises a third expander unit (16) and a second heater (15); The inlet of the second heater (15) is connected to the cold side outlet of the main cooler (7), the outlet of the second heater (15) is connected to the inlet of the third expansion unit (16), and the gas outlet of the third expansion unit (16) is vented.

5. The carbon dioxide energy storage system according to claim 3 or 4, characterized in that: The system also includes a heat accumulator (13); The heat accumulator is used to store compression heat generated by the main compressor unit (1), the gas booster unit (3) and the circulating compressor unit (9), and to supply heat to the first heater (14) and / or the second heater (15); Preferably, a cooler is provided at the outlet of each compressor stage of the gas compression device and the circulation compressor unit (9), and all compression heat of the cooler is stored in the heat accumulator (13).

6. The carbon dioxide energy storage system according to claim 1, characterized in that: The liquid outlet of the gas-liquid separation tank (6) is in communication with the cold side inlet of the main cooler.

7. A method for storing carbon dioxide energy using the system according to any one of claims 1 to 6, characterized in that: The method includes an energy storage process and an energy release process; In the energy storage process, the carbon dioxide-rich gas from the coal chemical plant is introduced into the gas compression device for pressurization to obtain pressurized carbon dioxide-rich gas; Introducing part of the pressurized carbon dioxide-rich gas into the first expansion unit (5) for expansion and refrigeration, and then introducing it into the gas-liquid separation tank (6) for gas-liquid separation, introducing the carbon dioxide gas obtained by gas-liquid separation into the cold side of the main cooler (7) as a cooling medium to release cold energy, and introducing the carbon dioxide gas after releasing cold into the circulation compressor unit (9) for pressurization and then returning to the gas compression device; Directly introducing the remaining portion of the pressurized carbon dioxide-rich gas into the hot side of the main cooler (7) for cooling and liquefaction, and introducing the obtained low-temperature carbon dioxide liquid into the liquid storage tank (8) for storage; In the energy release process, the energy in the liquid carbon dioxide is released through the energy release device, and cold energy is provided for the main cooler (7).

8. The carbon dioxide energy storage method according to claim 7, characterized in that: The gas compression device comprises a main compressor unit (1) and a gas booster unit (3), and the energy storage process further comprises: The carbon dioxide-rich gas from the coal chemical plant is sequentially introduced into the main compressor unit (1) and the gas booster unit (3) for pressurization to obtain the pressurized carbon dioxide-rich gas; the carbon dioxide gas after cooling is sequentially introduced into the circulating compressor unit (9) for pressurization and then returned to the gas booster unit (3); Preferably, the energy consumption of the main compressor unit (1) and the circulating compressor unit (9) is provided by green electricity, and the first expansion unit (5) performs work to drive the gas booster unit (3).

9. The carbon dioxide energy storage method according to claim 7, characterized in that: The energy release device comprises a vaporizer (12), a first heater (14) and a second expansion unit (17); The releasing of energy in the liquid carbon dioxide by the energy release device comprises: introducing the carbon dioxide liquid in the liquid storage tank (8) into a vaporizer (12) for vaporization, introducing the high-pressure carbon dioxide gas obtained by vaporization into a first heater (14) for heating, and introducing the high-temperature and high-pressure carbon dioxide gas obtained by heating into a second expansion unit (17) for performing work and outputting electrical energy, thereby obtaining concentrated carbon dioxide gas; The cold storage device (11) collects cold energy in the gasifier (12); wherein the cold energy in the cold storage device provides cold energy for the main cooler (7) during the energy storage process; Preferably, the non-condensable gas at the top of the liquid storage tank (8) enters the cold side of the main cooler (7) to release cold energy, and then merges with the high-pressure carbon dioxide gas at the outlet of the gasifier (12) to enter the first heater (14) together; Preferably, the pressure of the liquid storage tank (8) is 4.0-9.0 MPa, and the temperature is -40°C to 25°C; more preferably, the pressure is 6-7 MPa, and the temperature is -10°C to 0°C.

10. The carbon dioxide energy storage method according to claim 7, characterized in that: The energy release device further comprises a second heater (15) and a second expansion unit (16); The energy release process also includes: introducing the non-condensable gas in the liquid storage tank (8) into the cold side of the main cooler (7) as a cooling medium to release cold energy, introducing the non-condensable gas after the cold release into the second heater (15) for heating, introducing the high-temperature non-condensable gas obtained by heating into the second expansion unit (16) to perform work and output electrical energy, and venting the outlet gas of the second expansion unit (16).

11. The carbon dioxide energy storage method according to claim 7, characterized in that: The energy storage process further comprises: introducing the low-pressure carbon dioxide liquid obtained by gas-liquid separation in the gas-liquid separation tank (6) as a cooling medium into the cold side of the main cooler (7), and introducing the circulating compressor unit (9) after releasing the cold; Preferably, the pressure of the gas-liquid separation tank (6) is 0.5-1.0 MPa, and the cooling temperature is -56°C to -40°C; more preferably, the pressure is 0.8-1.0 MPa, and the cooling temperature is -45°C to -40°C.

12. The carbon dioxide energy storage method according to claim 7, characterized in that: The method further comprises: coolers are respectively provided at the outlets of each compressor stage of the gas compression device and the circulation compressor unit (9), and compression heat is stored through a heat accumulator (13), wherein the heat accumulator (13) provides heat for the first heater (14) and / or the second heater (15).

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