CN117345365A

CN117345365A - Gas-liquid two-phase carbon dioxide energy storage system utilizing waste heat of thermal power plant and control method

Info

Publication number: CN117345365A
Application number: CN202311255563.0A
Authority: CN
Inventors: 谢永慧; 王秦; 王鼎; 张荻; 汪晓勇; 杨彪; 范培源; 陈强; 惠大好
Original assignee: Baihe New Energy Technology Shenzhen Co ltd
Current assignee: Baihe New Energy Technology Shenzhen Co ltd
Priority date: 2023-09-26
Filing date: 2023-09-26
Publication date: 2024-01-05

Abstract

The disclosure provides a gas-liquid two-phase carbon dioxide energy storage system utilizing waste heat of a thermal power plant and a control method, and relates to the technical field of energy storage. The energy storage system includes: the energy storage device comprises an air storage, an energy storage component, an energy storage container and an energy release component which are sequentially connected in a closed loop manner; the heat absorption assembly is connected between the energy storage container and the energy release assembly and is connected with the thermal power plant, absorbs waste heat output by the work of the thermal power plant, and provides heat for carbon dioxide flowing from the energy storage container to the energy release assembly so as to evaporate and/or heat the carbon dioxide. The energy storage system greatly reduces the external heat supply of the gas-liquid two-phase carbon dioxide energy storage system, greatly reduces the main heat loss of the thermal power plant, and improves the energy utilization rate of the thermal power plant.

Description

Gas-liquid two-phase carbon dioxide energy storage system utilizing waste heat of thermal power plant and control method

Technical Field

The disclosure relates to the technical field of energy storage, in particular to a gas-liquid two-phase carbon dioxide energy storage system utilizing waste heat of a thermal power plant and a control method.

Background

The thermal power plant is a plant for outputting electric energy by utilizing a thermal power generation technology, and waste heat such as high-temperature flue gas generated in a boiler of the thermal power plant carries a large amount of available heat to be discharged into the environment, so that the thermal power plant is a main heat loss of the thermal power plant.

In order to ensure stable power supply of a power grid, a thermal power plant usually synchronously sends out adjustment of matched electric quantity according to the change of the load of the power grid, namely, the peak shaving operation of the thermal power plant. In the related art, in order to cooperate with peak shaving operation of a thermal power plant, a carbon dioxide energy storage system can be used for compressing carbon dioxide by using redundant electric quantity in a low electricity consumption period and storing the carbon dioxide in a liquid state; and in the electricity consumption peak period, releasing carbon dioxide to drive the generator to output electric energy, so as to realize peak shifting and valley filling of the electric quantity output of the thermal power plant. The carbon dioxide energy storage system needs a large amount of heat in the energy storage process and the energy release process, and the heat supply equipment is added for supplementing, so that the manufacturing cost of the energy storage system is increased, and the efficiency of the energy storage system is reduced.

Disclosure of Invention

The gas-liquid two-phase carbon dioxide energy storage system utilizing the waste heat of the thermal power plant and the control method thereof can greatly reduce or even eliminate the need of heat supply equipment, reduce the manufacturing cost of the energy storage system, improve the efficiency of the energy storage system, greatly reduce the main heat loss of the thermal power plant and improve the energy utilization rate of the thermal power plant.

The technical scheme is as follows:

In one aspect, a gas-liquid two-phase carbon dioxide energy storage system utilizing waste heat of a thermal power plant is provided, comprising: the energy storage device comprises an air storage, an energy storage component, an energy storage container and an energy release component which are sequentially connected in a closed loop manner;

the heat absorption assembly is connected between the energy storage container and the energy release assembly and is connected with the thermal power plant, absorbs waste heat output by work of the thermal power plant, and provides heat for carbon dioxide flowing from the energy storage container to the energy release assembly so as to evaporate and/or heat the carbon dioxide.

In some embodiments, the heat absorbing assembly is connected to a flue of the thermal power plant for absorbing heat contained in high temperature flue gas generated by the boiler.

In some embodiments, the heat absorbing assembly comprises a flue gas heat exchanger connected to a flue of the thermal power plant; the flue gas heat exchanger is used for absorbing heat of high-temperature flue gas by utilizing a heat storage working medium when the thermal power plant works.

In some embodiments, a heat storage assembly is also included;

the heat storage component is connected with the flue gas heat exchanger and is used for storing heat storage working media after heat absorption by the flue gas heat exchanger.

In some embodiments, the heat sink assembly further comprises a first energy release heat exchanger;

The energy release assembly comprises a first expander, the flue gas heat exchanger and/or the heat storage assembly is/are connected with one end of the first energy release heat exchanger, and the other end of the first energy release heat exchanger is/are connected with the first expander; the first energy release heat exchanger receives carbon dioxide which is output by the flue gas heat exchanger and/or the heat storage component and flows through the heat storage working medium heating temperature rise;

and/or the energy release assembly comprises an evaporator, the flue gas heat exchanger and/or the heat storage assembly is/are connected with the evaporator, the evaporator is connected with the first energy release heat exchanger, the evaporator receives the liquid carbon dioxide which is output by the flue gas heat exchanger and/or the heat storage assembly and flows through the heat storage working medium, and the evaporated gaseous carbon dioxide flows into the first energy release heat exchanger to heat.

In some embodiments, the energy release assembly further comprises a third expander, and the heat absorption assembly further comprises a second energy release heat exchanger respectively connected with the first expander and the third expander;

the second energy release heat exchanger is connected with the flue gas heat exchanger and/or the heat storage component, and is used for receiving the heat storage working medium output by the flue gas heat exchanger and/or the heat storage component to heat and raise the temperature of the gaseous carbon dioxide output by the first expander when the energy release component works.

In some embodiments, further comprising: a rankine cycle assembly;

the Rankine cycle assembly comprises a third energy release heat exchanger and a second expander which are connected in a closed loop, and a circulating working medium which circularly flows is arranged between the third energy release heat exchanger and the second expander;

the third energy release heat exchanger is connected with the second energy release heat exchanger, and when the energy release assembly works, the heat storage working medium output by the second energy release heat exchanger provides heat for the circulating working medium in the third energy release heat exchanger, so that the heat-absorbing circulating working medium enters the second expander to do work.

In some embodiments, the rankine cycle assembly further comprises a working medium condenser and a fourth heat exchanger;

the working medium condenser is connected with a second vapor outlet of the third expander and is used for cooling and condensing the gaseous circulating working medium output by the second vapor outlet into a liquid state;

the fourth heat exchanger is respectively connected with the working medium condenser, the second steam outlet and the third energy release heat exchanger, and is used for heating the liquid circulating working medium output by the working medium condenser through the gaseous circulating working medium output by the second steam outlet so as to improve the temperature of the liquid circulating working medium entering the third energy release heat exchanger.

On the other hand, the gas-liquid two-phase carbon dioxide energy storage system utilizing the waste heat of the thermal power plant comprises a gas storage, an energy storage component, an energy storage container and an energy release component which are sequentially connected in a closed loop; the energy storage assembly comprises a fifth heat exchanger and a compressor;

the fifth heat exchanger is connected between the gas storage and the compressor and is connected with the thermal power plant, and the fifth heat exchanger is used for providing heat for carbon dioxide output by the gas storage through waste heat output by the thermal power plant when the energy storage assembly works so as to improve the temperature of the carbon dioxide entering the compressor.

On the other hand, a control method of a gas-liquid two-phase carbon dioxide energy storage system utilizing waste heat of a thermal power plant is provided, and the control method is suitable for the gas-liquid two-phase carbon dioxide energy storage system utilizing waste heat of the thermal power plant;

the control method comprises the following steps:

and when the energy release assembly works, the waste heat output by the thermal power plant is led to the heat absorption assembly to provide heat for the carbon dioxide flowing from the energy storage container to the energy release assembly so as to evaporate or/and heat the carbon dioxide.

According to the gas-liquid two-phase carbon dioxide energy storage system utilizing the waste heat of the thermal power plant, the heat absorption component is arranged between the energy storage container and the energy release component, and is connected with the thermal power plant, so that the waste heat output by the work of the thermal power plant can be introduced, and heat is provided for carbon dioxide output by the energy storage container, so that the heat absorption and evaporation of the carbon dioxide and/or the temperature rise are realized, and the external heat supply equipment of the gas-liquid two-phase carbon dioxide energy storage system is greatly reduced or even not required; meanwhile, the heat of low-grade waste heat which is output by the thermal power plant and needs to be discharged into the environment is recycled, so that the heat loss of the thermal power plant is reduced, and the energy utilization rate of the thermal power plant is improved.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present disclosure, the drawings required for the description of the embodiments will be briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present disclosure, and other drawings may be obtained according to these drawings without inventive effort for a person of ordinary skill in the art.

Fig. 1 is a block diagram of a gas-liquid two-phase carbon dioxide energy storage system using waste heat of a thermal power plant according to an embodiment of the present disclosure;

fig. 2 is a block diagram of a gas-liquid two-phase carbon dioxide energy storage system using waste heat of a thermal power plant according to another embodiment of the present disclosure;

FIG. 3 is a block diagram of a gas-liquid two-phase carbon dioxide energy storage system utilizing thermal power plant waste heat according to another embodiment of the present disclosure;

fig. 4 is a block diagram of a gas-liquid two-phase carbon dioxide energy storage system using waste heat of a thermal power plant according to another embodiment of the present disclosure;

fig. 5 is a block diagram of a gas-liquid two-phase carbon dioxide energy storage system using waste heat of a thermal power plant according to another embodiment of the present disclosure;

FIG. 6 is a block diagram of a rankine cycle assembly provided by another embodiment of the present disclosure;

Fig. 7 is a schematic structural diagram of a gas-liquid two-phase carbon dioxide energy storage system using waste heat of a thermal power plant with a heat storage assembly according to an embodiment of the present disclosure.

Reference numerals in the drawings are respectively expressed as:

1. a gas storage;

2. an energy storage assembly; 201. a compressor; 202. a fifth heat exchanger; 203. an energy storage heat exchanger; 204. a condenser; 205. a constant temperature pool;

3. an energy storage container;

4. an energy release assembly; 401. a first expander; 402. a second expander;

5. a heat sink assembly; 51. a flue gas heat exchanger; 52. a heat storage assembly; 521. a first heat storage tank; 522. a first cold storage tank; 53. a first energy release heat exchanger; 54. a second energy release heat exchanger;

6. a flue;

7. a rankine cycle assembly; 701. a third energy release heat exchanger; 702. a third expander; 703. a working medium condenser; 704. a fourth heat exchanger;

8. an evaporator;

9. a second heat storage tank;

10. a second cold storage tank;

11. a media cooler;

12. a carbon dioxide cooler.

Detailed Description

Reference will now be made in detail to exemplary embodiments, examples of which are illustrated in the accompanying drawings. When the following description refers to the accompanying drawings, the same numbers in different drawings refer to the same or similar elements, unless otherwise indicated. The implementations described in the following exemplary examples are not representative of all implementations consistent with the present disclosure. Rather, they are merely examples of apparatus and methods consistent with some aspects of the present disclosure as detailed in the accompanying claims.

In the description of the present disclosure, it should be understood that the terms "center," "longitudinal," "transverse," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," "circumferential," etc. indicate orientations or positional relationships based on the orientation or positional relationships shown in the drawings, are merely for convenience in describing the present application and simplifying the description, and do not indicate or imply that the device or element being referred to must have a particular orientation, be configured and operated in a particular orientation, and therefore should not be construed as limiting the present disclosure.

Carbon dioxide energy storage system utilizes two phases of carbon dioxide to realize energy storage and release in the energy storage and release process, but carbon dioxide can absorb a large amount of heat in the two phases and release process, and this part of heat needs a large amount of external heat supply such as heat pump, greatly increases external heat supply equipment investment and occupation area.

The basic production process of the thermal power plant is as follows: the fuel heats water to generate steam when being combusted, chemical energy of the fuel is converted into heat energy, steam pressure pushes the steam turbine to rotate, the heat energy is converted into mechanical energy, and then the steam turbine drives the generator to rotate, so that the mechanical energy is converted into electric energy.

The flue gas generated by the combustion of the fuel contains higher heat, usually at 95-120 ℃, before being discharged into the environment through the chimney outlet, and this heat is usually wasted.

In this regard, the present disclosure provides a gas-liquid two-phase carbon dioxide energy storage system that utilizes thermal power plant waste heat, can the external heat supply of the two-phase carbon dioxide energy storage system of greatly reduced gas-liquid, external heat supply equipment investment and area are significantly reduced, improve thermal power plant energy utilization simultaneously.

In addition, the heat in high-temperature media such as the output flue gas of the thermal power plant is recycled, and the energy utilization rate of the thermal power plant is improved.

For the purposes of clarity, technical solutions and advantages of the present disclosure, the following further details the embodiments of the present disclosure with reference to the accompanying drawings.

On the one hand, referring to fig. 1 and 7, this embodiment provides a gas-liquid two-phase carbon dioxide energy storage system using waste heat of a thermal power plant, including: the energy storage device comprises an air storage 1, an energy storage component 2, an energy storage container 3 and an energy release component 4 which are sequentially connected in a closed loop mode.

The heat absorbing assembly 5 is connected between the energy storage container 3 and the energy release assembly 4 and is connected with the thermal power plant, and the heat absorbing assembly 5 absorbs waste heat output by the thermal power plant and provides heat for carbon dioxide flowing to the energy release assembly 4 from the energy storage container 3 so as to evaporate and/or heat the carbon dioxide.

According to the gas-liquid two-phase carbon dioxide energy storage system utilizing waste heat of the thermal power plant, the heat absorption component 5 is arranged between the energy storage container 3 and the energy release component 4, the heat absorption component 5 is connected with the thermal power plant, the waste heat output by the work of the thermal power plant is stored, the waste heat output by the thermal power plant can be introduced when the energy release component 4 works, heat is provided for carbon dioxide flowing to the energy release component 4 from the energy storage container 3, so that the heat absorption and evaporation of the carbon dioxide and/or the temperature rise are/is achieved, and the external heat supply of the gas-liquid two-phase carbon dioxide energy storage system is greatly reduced.

Meanwhile, the gas-liquid two-phase carbon dioxide energy storage system utilizing the waste heat of the thermal power plant can recycle heat in high-temperature media such as flue gas of the thermal power plant, and the energy utilization rate of the thermal power plant is improved.

The embodiment provides a control method applicable to the energy storage system of the embodiment, and has all the technical effects of the embodiment.

The control method comprises the following steps:

when the energy release assembly 4 works, waste heat output by the work of the thermal power plant is led to the heat absorption assembly 5 to provide heat for the carbon dioxide flowing from the energy storage container 3 to the energy release assembly 4 so as to evaporate or/and heat the carbon dioxide. Illustratively, heat is provided to the carbon dioxide output from the energy storage vessel 3 to cause the carbon dioxide to vaporize and/or enter the energy release assembly 4 (e.g., the first expander 401) to raise the temperature, reducing the external heat source required for carbon dioxide to vaporize or raise the temperature.

As shown in connection with fig. 1 and 7, in some embodiments, a heat absorbing assembly 5 is connected to a flue 6 of the thermal power plant for absorbing heat contained in high temperature flue gas flowing through the flue 6. For example, a flue 6 connected to a boiler, utilizes the high temperature flue gas to provide heat to the carbon dioxide of the energy release assembly 4 (as shown in fig. 7).

Wherein the energy release assembly 4 operates during peak application times.

In some possible implementation manners, the heat absorbing component 5 is connected to the outlet of the energy storage container 3, and is used for evaporating or evaporating and heating the liquid carbon dioxide output by the energy storage container 3, so that the carbon dioxide flows to the energy release component 4 in a gaseous form, and in the evaporation process of the carbon dioxide, heat can be absorbed from high-temperature flue gas, so that external heat supply of the gas-liquid two-phase carbon dioxide energy storage system is greatly reduced, and the investment and occupied area of external heat supply equipment are greatly reduced.

In some possible implementations, the waste heat output by the thermal power plant includes high temperature flue gas generated by the combustion of fuel.

In some possible implementations, the gas reservoir 1 is a double-layered membrane structure, including a mulching film, an inner membrane, and an outer membrane; the outer membrane is used for resisting wind and snow, an interlayer cavity is arranged between the inner membrane and the outer membrane, and gas in the interlayer cavity upwards props the outer membrane to keep the appearance, so that the gas storage 1 is not easy to collapse, the inner membrane and the mulching film form a containing cavity for storing gaseous carbon dioxide, and the pressure and the temperature in the inner membrane can be maintained within a certain range so as to meet the energy storage requirement. Illustratively, the pressure of the gaseous carbon dioxide within the gas reservoir 1 may be close to ambient pressure, i.e. the surrounding atmospheric pressure. In some embodiments, the temperature within the gas reservoir 1 is in the range of-40 ℃ to 70 ℃, illustratively-40 ℃, 0 ℃, 15 ℃, 20 ℃, 25 ℃, 30 ℃, 35 ℃, 40 ℃, 50 ℃, 60 ℃, 70 ℃, etc., and the pressure difference between the gas pressure within the gas reservoir 1 and the outside atmosphere is less than 1000Pa.

In another possible implementation manner, the air storage 1 may be provided with a heat insulation component to insulate the air storage 1, so that the temperature inside the air storage is maintained within a required range.

In another possible implementation manner, the volume of the accommodating cavity of the air storage 1 can be changed, when carbon dioxide is filled, the volume of the accommodating cavity of the air storage 1 is increased, and when carbon dioxide flows out, the volume of the accommodating cavity of the air storage 1 is reduced, so that the pressure in the air storage 1 is constant. The pressure and temperature inside the gas storage 1 are maintained within a certain range, and in the above analysis, they can be regarded as approximately constant values.

It will be appreciated that in other embodiments of the present disclosure, other variable volume containers may also be employed for the gas storage 1.

In other possible implementations, the energy storage vessel 3 is used to store liquid carbon dioxide in a high pressure state.

Alternatively, the pressure of the liquid carbon dioxide in the energy storage vessel 3 is between 2MPa and 10MPa, as exemplified by 2MPa, 5MPa, 6MPa, 7MPa, 7.2MPa, 7.5MPa, 8MPa, 10MPa, etc. being optional.

Alternatively, the liquid carbon dioxide in the energy storage vessel 3 may not exceed 50 ℃, in particular not exceed 30 ℃, for example between 20 ℃ and 30 ℃. Illustratively, the temperature of the liquid carbon dioxide as it flows into the energy storage vessel 3 is between 20 ℃ and 30 ℃ such that the temperature of the liquid carbon dioxide in the energy storage vessel 33 does not exceed 30 ℃.

Illustratively, the temperature of the liquid carbon dioxide in the energy storage vessel 3 is between 20 ℃ and 30 ℃ and the pressure is between 7MPa and 7.5 MPa. In this way, potential safety hazards caused by accidental rising and pressure increase of liquid carbon dioxide in the energy storage container 3 can be avoided, so that the carbon dioxide energy storage system disclosed by the invention is more suitable for being deployed in places with dense personnel, such as residential areas, schools, hospitals, stations, business centers and the like.

In actual production, the temperature of the high-temperature flue gas is higher than 90 ℃ and higher than the temperature (below 30 ℃) of the liquid carbon dioxide output by the energy storage container 3, so that the corresponding evaporation or heating effect can be achieved.

As shown in connection with fig. 1, 7, in some embodiments, the heat absorbing assembly 5 comprises a flue gas heat exchanger 51 connected to a flue 6 of a thermal power plant; the flue gas heat exchanger 51 is used for absorbing heat of high-temperature flue gas by utilizing a heat storage working medium when the thermal power plant works. The heat storage working medium can be heat conducting oil or pressurized water, and the heat conducting oil or the pressurized water can be utilized to absorb the heat of the high-temperature flue gas.

The flue gas heat exchanger 51 of this embodiment can set up in the flue 6 of thermal power plant, also can connect in parallel with thermal power plant flue 6, the in-process of thermal power plant produces high temperature flue gas and passes through flue gas heat exchanger 51 exothermic cooling, later get back to the flue 6 of boiler and discharge through the chimney, reduce the original power generation system of reforming transform thermal power plant as far as possible, flue gas heat exchanger 51 retrieves the waste heat in the high temperature flue gas, high temperature flue gas carries out heat transfer because of the difference in temperature with the heat storage working medium, the heat storage working medium is further with heat transfer to release energy subassembly 4.

The flue gas temperature of the flue of the thermal power plant is approximately 130-150 ℃, the flue gas temperature after heat exchange by the flue gas heat exchanger 51 is reduced to about 90 ℃, and the flue gas can be discharged through the original chimney of the thermal power plant without generating chimney corrosion.

As shown in connection with fig. 2, 7, in some embodiments, the heat sink assembly 5 further comprises a heat storage assembly 52; the heat storage component 52 is connected with the flue gas heat exchanger 51, and the heat storage component 52 is used for storing heat storage working media after heat absorption by the flue gas heat exchanger 51.

The heat storage component 52 can continuously store heat in the high-temperature flue gas in the flue 6 when the energy release component 4 is not in operation during the operation of the thermal power plant, and provide heat for the carbon dioxide flowing from the energy storage container 3 to the energy release component 4 when the energy release component 4 is in operation, so that the carbon dioxide is evaporated and/or heated.

In some possible implementations, referring to fig. 7, the heat storage assembly 52 includes a first heat storage tank 521 and a first cold storage tank 522, where the first heat storage tank 521 is connected to an outlet of the flue gas heat exchanger 51, and the first cold storage tank 522 is connected to an inlet of the flue gas heat exchanger 51, so that when the heat storage working medium absorbs heat and heats up through the flue gas heat exchanger 51, the heat storage working medium can enter and temporarily store in the first heat storage tank 521, and after heat exchange and cooling with carbon dioxide, the heat storage working medium flows back and then enters and temporarily stores in the first cold storage tank 522, and when the flue gas heat exchanger 51 works, the low-temperature heat storage working medium is input into the flue gas heat exchanger 51.

As shown in connection with fig. 3 and 7, the energy release assembly 4 comprises a first expander 401 and the heat absorption assembly 5 further comprises a first energy release heat exchanger 53.

The flue gas heat exchanger 51 and/or the heat storage component 52 are connected with one end of a first energy release heat exchanger 53, and the other end of the first energy release heat exchanger 53 is connected with a first expander 401; the first energy release heat exchanger 53 receives the carbon dioxide which is output by the flue gas heat exchanger 51 and/or the heat storage component 52 and flows through the heat storage working medium heating temperature rise.

In this embodiment, the flue gas heat exchanger 51 absorbs heat in high-temperature flue gas in the flue 6 of the thermal power plant, heats the heat storage working medium, and the high-temperature heat storage working medium (for example, heat conduction oil or water under pressure) reaches the first energy release heat exchanger 53 after being conveyed, and exchanges heat with carbon dioxide in the first energy release heat exchanger 53, so as to heat and raise the temperature of the carbon dioxide.

In some possible implementations, the first energy release heat exchanger 53 is connected with the flue gas heat exchanger 51, and the heat storage working medium heated by the flue gas heat exchanger 51 is directly conveyed to the first energy release heat exchanger 53, and exchanges heat with carbon dioxide in the first energy release heat exchanger 53.

In other possible implementations, the first energy release heat exchanger 53 is connected to the heat storage component 52, for example, to the first heat storage tank, the heat storage medium heated by the flue gas heat exchanger 51 is stored in the heat storage component 52, and is transported to the first energy release heat exchanger 53 by the heat storage component 52, and exchanges heat with carbon dioxide in the first energy release heat exchanger 53. This allows the carbon dioxide to be supplied with the high temperature heat storage medium stored in the heat storage assembly 52 during non-operating conditions of the thermal power plant. Because the energy release component 4 (for example, the first expander 401) works intermittently, when the energy release component 4 (for example, the first expander 401) does not work, the heat storage component 52 can be utilized to temporarily store the heat storage working medium heated by the flue gas heat exchanger 51, and when the energy release component 4 (for example, the first expander 401) works, the high-temperature heat storage working medium stored in the heat storage component 52 is output to the first energy release heat exchanger 53 to exchange heat of the carbon dioxide flowing through the first energy release heat exchanger 53.

In other possible implementations, the first energy release heat exchanger 53 is connected to the flue gas heat exchanger 51 and the heat storage component 52 (for example, the first heat storage tank 521), and the heat storage medium heated by the flue gas heat exchanger 51 or the heat storage medium stored in the heat storage component 52 is controlled to be delivered to the first energy release heat exchanger 53 by a valve (not shown), so that heat exchange with carbon dioxide is performed in the first energy release heat exchanger 53. It will be appreciated that the heat storage medium heated by the flue gas heat exchanger 51 and the heat storage medium stored in the heat storage assembly 52 are transferred together to the first energy release heat exchanger 53, where heat exchange with carbon dioxide takes place in the first energy release heat exchanger 53.

In some possible implementations, the first expander 401 includes, but is not limited to, a turbine type, and its principle is mainly that energy possessed by the fluid (carbon dioxide) is converted into kinetic energy when flowing through the nozzle, and when flowing through the rotor, the fluid impacts the blades, and drives the rotor to rotate, thereby driving the expander shaft to rotate. The expander shaft directly or drives other machines (such as a generator) through a transmission mechanism to output mechanical work, so that the energy release of the carbon dioxide energy storage system is realized.

It will be appreciated that the number of first expanders 401 in the energy release assembly 4 may be one, two or three, etc. The plurality of first expanders 401 can be connected in series or in parallel, and the energy release efficiency of the energy release assembly 4 can be improved due to the increase of the number of the first expanders 401, so that the carbon dioxide energy storage system can release energy rapidly and efficiently.

The first energy release heat exchanger 53 is illustratively a two-channel type or a three-channel type. For example, a two-channel type is used, wherein one channel is used for circulating liquid carbon dioxide, and the other channel is used for circulating any high-temperature medium, and the fluid in the two channels is used for completing heat exchange.

For example, three channels are used, one channel passing liquid carbon dioxide, one channel passing a first high temperature medium and the remaining channel passing the other high temperature medium, during which the fluid in both channels completes the heat exchange.

Another exemplary, first energy releasing heat exchanger 53 includes, but is not limited to, a jacketed heat exchanger, a submerged heat exchanger, a spray heat exchanger, a plate heat exchanger, a shell and tube heat exchanger, and the like.

In some possible implementations, the number of first energy release heat exchangers 53 is, for example, one, two, three, etc.; when the number of the first heat exchangers 53 is plural, the plural first heat exchangers 53 may be connected in series or in parallel.

Optionally, in some embodiments, when the number of the first energy releasing heat exchangers 53 is plural, at least part of the first energy releasing heat exchangers 53 are connected to the flue 6 of the boiler for extracting high temperature flue gas generated in the boiler. The high-temperature flue gas is generated by burning fuel in the boiler, a large amount of heat is contained in the high-temperature flue gas, and the heat is led to the first energy release heat exchanger 53 by the flue 6, so that the heat is provided for the carbon dioxide in the first energy release heat exchanger 53, the expansion work efficiency of the carbon dioxide is improved, the external heat supply of the gas-liquid two-phase carbon dioxide energy storage system is greatly reduced, and the energy utilization rate of a thermal power plant is improved.

As shown in the figures, in some embodiments, the energy release assembly 4 further includes a second expander 402, and the heat absorption assembly 5 further includes a second energy release heat exchanger 54 connected to the first expander 401 and the second expander 402, respectively; the second energy release heat exchanger 54 is connected with the flue gas heat exchanger 51 and/or the heat storage component 52, and the second energy release heat exchanger 54 is used for receiving the heat storage working medium output by the flue gas heat exchanger 51 and/or the heat storage component 52 to heat and raise the temperature of the gaseous carbon dioxide output by the first expander 401 so as to raise the temperature of the carbon dioxide entering the second expander 402 when the energy release component 4 works.

A second expander 402 is arranged downstream of the first expander 401, carbon dioxide entering the second expander 402 can be heated up again by using a second energy release heat exchanger 54, and the second energy release heat exchanger 54 provides heat by using the flue gas heat exchanger 51 and/or the energy storage component 2, so that the working efficiency of the carbon dioxide in the second expander 402 is improved.

In some possible implementations, the second energy release heat exchanger 54 is connected to the flue gas heat exchanger 51, and the heat storage medium heated by the flue gas heat exchanger 51 is directly transferred to the second energy release heat exchanger 54, and exchanges heat with carbon dioxide in the second energy release heat exchanger 54.

In other possible implementations, the second energy release heat exchanger 54 is connected to the heat storage assembly 52, for example, to the first heat storage tank, and the heat storage medium heated by the flue gas heat exchanger 51 is stored in the heat storage assembly 52, and is transported by the heat storage assembly 52 to the second energy release heat exchanger 54, and exchanges heat with carbon dioxide in the second energy release heat exchanger 54. This allows the carbon dioxide to be supplied with the high temperature heat storage medium stored in the heat storage assembly 52 during non-operating conditions of the thermal power plant. Because the energy release component 4 (for example, the second expander 402) is intermittent in operation, when the energy release component 4 (for example, the second expander 402) is not in operation, the heat storage component 52 can be utilized to temporarily store the heat storage working medium heated by the flue gas heat exchanger 51, and when the energy release component 4 (for example, the second expander 402) is in operation, the high-temperature heat storage working medium stored in the heat storage component 52 is output to the second energy release heat exchanger 54 to exchange heat for the carbon dioxide flowing through the second energy release heat exchanger 54.

In other possible implementations, the second energy release heat exchanger 54 is connected to both the flue gas heat exchanger 51 and the heat storage component 52 (e.g., the first heat storage tank), and the heat storage medium heated by the flue gas heat exchanger 51 or the heat storage medium stored in the heat storage component 52 is controlled to be delivered to the second energy release heat exchanger 54 by a valve (not shown), so that heat exchange with carbon dioxide occurs in the second energy release heat exchanger 54. It will be appreciated that the heat storage medium heated by the flue gas heat exchanger 51 and the heat storage medium stored in the heat storage assembly 52 are transferred together to the second energy release heat exchanger 54, where heat exchange with carbon dioxide takes place in the second energy release heat exchanger 54.

In other possible implementations, referring to fig. 7, the second energy release heat exchanger 54 is connected to the first energy release heat exchanger 53, the first energy release heat exchanger 53 is connected to the flue gas heat exchanger 51 and/or the heat storage component 52, the high-temperature heat storage working medium output by the flue gas heat exchanger 51 and/or the heat storage component 52 (for example, the first heat storage tank) firstly enters the first energy release heat exchanger 53 to perform first heat exchange with carbon dioxide to be entered into the first expander 401, the high-temperature heat storage working medium is converted into a medium-temperature heat storage working medium, the medium-temperature heat storage working medium enters the second energy release heat exchanger 54 to perform second heat exchange with carbon dioxide to be entered into the second expander 402, the medium-temperature heat storage working medium is converted into a low-temperature heat storage working medium, and the low-temperature working medium flows back to the first cold storage tank of the heat storage component 52, and then circulates back to the flue gas heat exchanger 51.

Since a great amount of heat energy is still contained in the heat storage medium after the heat exchange between the carbon dioxide and the high-temperature heat storage working medium (for example, the high-temperature flue gas or the flue gas heat exchanger 51 is input) is performed in the first energy release heat exchanger 53, the second energy release heat exchanger 54 and the second expansion machine 402 are arranged at the downstream of the first expansion machine 401, so that the medium temperature medium discharged by the first energy release heat exchanger 53 and the medium temperature carbon dioxide output by the first expansion machine 401 are subjected to heat exchange again in the second energy release heat exchanger 54, which is beneficial to improving the heat utilization rate.

In some possible implementations, as shown in connection with fig. 7, the energy release assembly 4 includes an evaporator 8, where the evaporator 8 is connected to the outlet of the energy storage container 3, and the evaporator 8 is used to convert the liquid carbon dioxide output from the energy storage container 3 into gaseous carbon dioxide. The evaporator 8 is connected to the flue gas heat exchanger 51 and/or the heat storage component 52 (not shown), and the liquid carbon dioxide is heated and evaporated by using the high-temperature heat storage working medium provided by the flue gas heat exchanger 51 and/or the heat storage component 52.

In some possible implementations, the evaporator 8 is connected to the first energy release heat exchanger 53, the evaporator 8 receives the liquid carbon dioxide flowing through the evaporation of the heat storage working medium output by the flue gas heat exchanger 51 and/or the heat storage component 52, and the evaporated gaseous carbon dioxide flows into the first energy release heat exchanger 53 to raise the temperature.

In some possible implementations, the heat absorbing assembly 5 includes an evaporator 8, the flue gas heat exchanger 51 and/or the heat storage assembly 52 are connected with one end of the evaporator 8, the other end of the evaporator 8 is connected with the first energy release heat exchanger 53, the evaporator 8 receives liquid carbon dioxide flowing through the heat storage working medium output by the flue gas heat exchanger 51 and/or the heat storage assembly 52 and evaporated, the evaporated gaseous carbon dioxide flows into the first energy release heat exchanger 53 to heat, and the heated gaseous carbon dioxide enters the first expander 401 to expand and do work. It will be appreciated that the evaporator 8 may be a component of the energy release assembly 4 or a component of the heat absorption assembly 5, and the first energy release heat exchanger 53 may also function as an evaporator to evaporate and heat carbon dioxide.

As shown in connection with fig. 7, in some embodiments, the gas-liquid two-phase carbon dioxide energy storage system that utilizes the waste heat of the thermal power plant further includes an energy storage heat exchanger 203, a second heat storage tank 9, and a first cold storage tank 522 that are connected in a closed loop in sequence. The energy storage assembly 2 comprises a compressor 201.

The energy storage heat exchanger 203 is connected with the energy storage component 2, the second heat storage tank 9 is connected with the energy release component 4, and the second heat storage tank 9 is used for absorbing and storing heat generated by the energy storage component 2 when the compressor 201 of the energy storage component 2 works and supplying heat to the first energy release heat exchanger 53 and/or the second energy release heat exchanger 54 when the energy release component 4 works.

The first cold storage tank 522 is used for storing a low-temperature heat exchange medium, and can input the low-temperature heat exchange medium into the energy storage heat exchanger 203 when the compressor 201 works; the energy storage heat exchanger 203 is connected with the compressor 201, and can absorb heat to heat the heat exchange medium when the compressor 201 works, and convey the high-temperature heat exchange medium to the second heat storage tank 9 for storage. The high-temperature heat exchange medium output from the second heat storage tank 9 can flow through at least one of the first energy release heat exchanger 53 and the second energy release heat exchanger 54, and transfer heat to the carbon dioxide in the first energy release heat exchanger 53 and/or the second energy release heat exchanger 54. After the heat exchange medium releases heat in the first energy release heat exchanger 53 and/or the second energy release heat exchanger 54, the heat exchange medium is input into the second cold storage tank 10 and stored therein, and the next heat exchange cycle is performed. Optionally, the heat exchange medium further comprises a medium cooler 11, the heat exchange medium is input into the medium cooler 11 for further cooling after being released in the first energy release heat exchanger 53 or the second energy release heat exchanger 54, and then is input into and stored in the second cold storage tank 10, and the next heat exchange cycle is performed. The medium cooler 11 is provided to further reduce the temperature design requirements of the second cold storage tank 10, reducing the manufacturing costs of the second cold storage tank 10.

In the operation process of the energy storage component 2, the carbon dioxide energy storage system of this embodiment utilizes the compressor 201 to convert electric energy into mechanical energy, and then utilizes the mechanical energy to pressurize gaseous carbon dioxide, and the mechanical energy is converted into pressure energy, realizes the storage of pressure energy, can produce a large amount of heat in the gaseous carbon dioxide pressurization process, and the second heat storage tank 9 can absorb and store this part of heat to carry out heat exchange with carbon dioxide when releasing energy component 4 during operation, make carbon dioxide evaporate or heat up, be favorable to improving the energy utilization rate in the energy storage system.

Illustratively, referring to fig. 7, the first energy release heat exchanger 53 and/or the second energy release heat exchanger 54 are connected between the second heat storage tank 9 and the medium cooler 11, and the heat exchange medium output by the second heat storage tank 9 flows through the first energy release heat exchanger 53 and/or the second energy release heat exchanger 54, and enters the medium cooler 11 to cool after releasing heat, and then is stored in the second cold storage tank 10.

As shown in conjunction with fig. 5 to 7, in some embodiments, the gas-liquid two-phase carbon dioxide energy storage system that uses waste heat of a thermal power plant further includes: a rankine cycle assembly 7.

The Rankine cycle assembly 7 comprises a third energy release heat exchanger 701 and a third expander 702 which are connected in a closed loop, and a circulating working medium which circularly flows between the third energy release heat exchanger 701 and the third expander 702.

The third energy release heat exchanger 701 is connected with the second energy release heat exchanger 54, and when the energy release assembly 4 works, the heat storage working medium output by the second energy release heat exchanger 54 provides heat for the circulating working medium in the third energy release heat exchanger 701, so that the gaseous circulating working medium evaporated by heat absorption enters the third expander 702 to do work.

In order to increase the output work of the energy release stage and further improve the working efficiency of the energy storage system, the energy storage system of the embodiment is provided with a Rankine cycle assembly 7, and the Rankine cycle assembly 7 can utilize the heat in the high-temperature flue gas in the flue 6 of the thermal power plant, and the third energy release heat exchanger 701 heats the circulating working medium to push the third expander 702 to apply work, so that the output work of the energy release stage is improved.

In the rankine cycle assembly 7 of the embodiment, by using the rankine cycle principle (rankine cycle), the cycle working medium is heated and evaporated into a gas state in the third energy release heat exchanger 701, enters the third expander 702 to expand and do work, is cooled and condensed into a liquid state, and converts the heat in the high-temperature flue gas into the kinetic energy of the gas state cycle working medium in the third expander 702 in this cycle, and pushes the generator to output in the form of electric energy.

Referring to fig. 7, in some possible implementations, the third energy release heat exchanger 701 is connected to the flue gas heat exchanger 51 and/or the heat storage component 52, and the high-temperature heat storage working medium output by the flue gas heat exchanger 51 and/or the heat storage component 52 enters the third energy release heat exchanger 701, and the heating cycle working medium pushes the third expander 702 to perform work.

Referring to fig. 7, in some possible implementations, the third energy release heat exchanger 701 is connected to the flue gas heat exchanger 51 and/or the heat storage assembly 52 through the first energy release heat exchanger 53 and/or the second energy release heat exchanger 54. Namely, the high-temperature heat storage working medium output by the flue gas heat exchanger 51 and/or the heat storage component 52 flows through the first energy release heat exchanger or the second energy release heat exchanger 54 to exchange heat with carbon dioxide, and then flows into the third energy release heat exchanger 701 to exchange heat with the circulating working medium again. It can be understood that the high-temperature heat storage working medium output by the flue gas heat exchanger 51 and/or the heat storage component 52 can also flow through the evaporator 8, the first energy release heat exchanger 53, the second energy release heat exchanger 54 and carbon dioxide respectively for heat exchange through a valve (not shown), and then flow into the third energy release heat exchanger 701 and the circulating working medium for heat exchange again.

In other possible implementations, the third energy release heat exchanger 701 is connected to the flue gas heat exchanger 51 and/or the heat storage component 52 through the second energy release heat exchanger 54 and the first energy release heat exchanger 53 in sequence, that is, the high-temperature heat storage working medium output by the flue gas heat exchanger 51 and/or the heat storage component 52 flows through the first energy release heat exchanger 53 to perform first heat exchange with carbon dioxide, then flows into the second energy release heat exchanger 54 to perform second heat exchange with carbon dioxide, and then flows into the third energy release heat exchanger 701 to perform third heat exchange with the circulating working medium.

In the case where the heat storage assembly 52 includes the first heat storage tank 521, the third energy release heat exchanger 701 is directly connected to the first heat storage tank 521; or the first heat storage tank 521 is connected through the first energy release heat exchanger 53 and/or the second energy release heat exchanger 54. And the flue gas heat exchanger 51 is further connected through the first heat storage tank 521, so that heat of the high-temperature heat storage working medium discharged from the first heat storage tank 521 is transferred to the third energy release heat exchanger 701.

When the heat storage assembly 52 includes the first cold storage tank 522, the third energy release heat exchanger 701 is connected with the first cold storage tank 522, and then connected with the flue gas heat exchanger 51 through the first cold storage tank 522, so as to implement circulation of the heat storage working medium between the third energy release heat exchanger 701 and the flue gas heat exchanger 51. The low-temperature heat storage working medium from the first cold storage tank 522 absorbs the heat of the flue gas heat exchanger 51 to be a high-temperature heat storage working medium, and the high-temperature heat storage working medium directly enters the third energy release heat exchanger 701 to exchange heat with the circulating working medium for cooling and then returns to the first cold storage tank 522 for storage. It can be understood that the low-temperature heat storage working medium from the first cold storage tank 522 absorbs heat of the flue gas heat exchanger 51 to become a high-temperature heat storage working medium, and then enters the third energy release heat exchanger 701 to exchange heat with the circulating working medium to be cooled, and returns to the first cold storage tank 522 to be stored. It can be also understood that the low-temperature heat storage working medium from the first cold storage tank 522 absorbs the heat of the flue gas heat exchanger 51 to become a high-temperature heat storage working medium, and then the high-temperature heat storage working medium can be transported to the first heat storage tank 521 for temporary storage, and then enters at least one middle heat-using component for heat exchange and cooling, and then enters the third energy release heat exchanger 701 for heat exchange and cooling with the circulating working medium and returns to the first cold storage tank 522 for storage. Intermediate heat-consuming components such as evaporator 8, first heat release heat exchanger 53, second heat release heat exchanger 54, fifth heat exchanger 202, etc.

As shown in connection with fig. 6 and 7, in some embodiments, the rankine cycle assembly 7 further includes a working fluid condenser 703 and a fourth heat exchanger 704.

The working medium condenser 703 is connected to the second vapor outlet of the third expander 702, and is used for cooling and condensing the gaseous circulating working medium discharged from the second vapor outlet into a liquid state; the fourth heat exchanger 704 is respectively connected with the working medium condenser 703, the second vapor outlet of the third expander 702 and the third energy release heat exchanger 701, and the fourth heat exchanger 704 is used for heating (i.e. backheating) the liquid circulating working medium output by the working medium condenser 703 through the gaseous circulating working medium output by the second vapor outlet so as to increase the temperature of the liquid circulating working medium entering the third energy release heat exchanger 701.

In the rankine cycle assembly 7 of the present embodiment, the circulating working medium enters the third energy release heat exchanger 701 in a liquid state, absorbs heat in the high-temperature flue gas and is converted into steam, and then enters the second expander 402 to do expansion work, then a part of steam is input into the working medium condenser 703 to be cooled and condensed into a liquid state, and the other part of steam is input into the fourth heat exchanger 704, the temperature of the liquid circulating working medium is raised by using the steam, and the heated liquid circulating working medium enters the third energy release heat exchanger 701 again to absorb heat, so that the energy release process is completed. The liquid circulating working medium enters the fourth heat exchanger 704 to exchange heat with the vapor extracted from the third expander 702, so that the heat of the high-temperature flue gas required by the third energy release heat exchanger 701 is reduced. Further, a liquid booster pump (not shown) is disposed in a connecting pipeline between the fourth heat exchanger 704 and the third energy release heat exchanger 701 to boost the pressure of the liquid circulating working medium at the outlet of the fourth heat exchanger 704, so as to improve the power generation efficiency of the rankine cycle assembly 7. Alternatively, the circulating working medium may be water, and the circulating working medium may be an organic working medium, and the organic working medium may be selected from an organic matter such as cyclopropane, butane, R152a, and the like, which is required to meet the requirement of the rankine cycle assembly 7 on the evaporation temperature. In one example, the evaporation temperature is not less than 60 ℃.

In some embodiments, the high temperature flue gas output from the boiler is subjected to dry desulfurization. The flue gas can be subjected to dry desulfurization after passing through the air preheater, so that corrosion of sulfuric acid formed by the flue gas due to too low temperature to equipment can be prevented, and meanwhile, the temperature of the flue gas can be kept to the greatest extent by the dry desulfurization, and the temperature loss in the desulfurization process is reduced.

On the other hand, referring to fig. 7, the gas-liquid two-phase carbon dioxide energy storage system using waste heat of a thermal power plant according to this embodiment includes a gas storage 1, an energy storage component 2, an energy storage container 3 and an energy release component 4 connected in a closed loop in sequence; the energy storage assembly 2 comprises a compressor 201 and a fifth heat exchanger 202. The fifth heat exchanger 202 is connected between the gas storage 1 and the compressor 201 and is connected with a thermal power plant, and the fifth heat exchanger 202 is used for providing heat for carbon dioxide output by the gas storage 1 through waste heat (such as flue gas) output by the thermal power plant when the energy storage assembly 2 works, so as to increase the temperature of the carbon dioxide entering the compressor 201.

The compressor 201 is an important component of the energy storage assembly 2, and the working efficiency of the compressor 201 directly affects the energy storage efficiency, so that it is required to ensure that the working state of the compressor 201 is good. The inlet temperature of the compressor 201 has an important influence on the intake air amount, in-cylinder temperature, operation life, etc. of the compressor 201, and thus it is necessary to control the temperature of carbon dioxide entering the compressor 201.

In this embodiment, the fifth heat exchanger 202 is disposed between the gas storage 1 and the compressor 201, and the fifth heat exchanger 202 can utilize the waste heat output by the thermal power plant to preheat the gaseous carbon dioxide output by the gas storage 1, so as to ensure that the inlet temperature of the compressor 201 is stable, and meet the operation requirement of the compressor 201, so that the compressor 201 has a good operation state, and further improve the energy storage efficiency of the energy storage system.

Another exemplary fifth heat exchanger 202 includes, but is not limited to, a jacketed heat exchanger, a submerged heat exchanger, a spray heat exchanger, a plate heat exchanger, a shell and tube heat exchanger, and the like.

In some possible implementations, the number of fifth heat exchangers 202 is, for example, one, two, three, etc.; when the number of the fifth heat exchangers 202 is plural, the plural fifth heat exchangers 202 may be connected in series or in parallel.

Referring to fig. 7, in some embodiments, a condenser 204 is disposed between the compressor 201 and the energy storage container 3, the condenser 204 is connected to a constant temperature water tank 205, the carbon dioxide output from the compressor 201 is cooled and then is converted into a low temperature and high pressure state from a high temperature and high pressure state, the high temperature and high pressure carbon dioxide is in the condenser 204, the constant temperature water tank 205 provides cold energy, the carbon dioxide is cooled and condensed into a liquid state, and then the liquid carbon dioxide is stored in the energy storage container 3.

Illustratively, the heat absorbed by the thermostatic waterbath 205 is released by natural heat exchange cooling.

In other possible implementations, as shown in fig. 7, a carbon dioxide cooler 12 is further disposed between the energy release assembly 4 (e.g., the second expander 402) and the gas storage 1, so as to reduce the temperature of carbon dioxide and ensure safe operation of the gas storage 1.

In some possible implementations, the energy storage assembly 2 includes a condenser 204 and at least one compressed energy storage portion, each comprising a compressor 201 and an energy storage heat exchanger 203; condenser 204 is used to condense carbon dioxide and compressor 201 is used to compress carbon dioxide. The energy storage heat exchanger 203 in each compressed energy storage section is connected to a compressor 201, the compressor 201 in the compressed energy storage section at the beginning in the direction of the carbon dioxide circulation is connected to the gas reservoir 1, the energy storage heat exchanger 203 in the compressed energy storage section at the end is connected to a condenser 204, which is connected to the energy storage container 3, where the beginning and the end are defined in the direction from the gas reservoir 1 through the energy storage assembly 2 to the energy storage container 3.

In other possible implementations, the energy release assembly 4 includes an evaporator 8, an energy release cooler, at least one expansion energy release portion, the expansion energy release portion includes an expander and an energy release heat exchanger, the evaporator 8 is used for evaporating carbon dioxide, the expander is used for releasing energy, the energy release cooler is used for cooling the carbon dioxide entering the gas storage 1, the expander in each expansion energy release portion is connected with the energy release heat exchanger, the evaporator 8 is connected with the energy storage container 3, the energy release heat exchanger in the expansion energy release portion at the beginning along the flow direction of the carbon dioxide is connected with the evaporator 8, the expander in the expansion energy release portion at the end is connected with the energy release cooler, and the energy release cooler is connected with the gas storage 1; the beginning and the end are defined here in terms of the direction from the energy storage container 3 through the energy release assembly 4 to the gas reservoir 1.

The energy release heat exchangers may be shared with the first energy release heat exchanger 53 and the second energy release heat exchanger 54, and the energy release cooler may be, for example, the carbon dioxide cooler 12.

Only an example of an energy storage system having one compression energy storage portion and two expansion energy release portions is shown in fig. 7, but it should be understood that the compression energy storage portion and the expansion energy release portion of the present embodiment may be theoretically any number, and the present disclosure is not limited thereto.

On the other hand, the embodiment provides a control method of a carbon dioxide energy storage system, which is suitable for the gas-liquid two-phase carbon dioxide energy storage system utilizing the waste heat of the thermal power plant.

The control method comprises the following steps:

when the energy release assembly 4 works, waste heat output by the work of the thermal power plant is led to the heat absorption assembly 5 to provide heat for the carbon dioxide flowing from the energy storage container 3 to the energy release assembly 4 so as to evaporate or/and heat the carbon dioxide.

The control method of the embodiment adopts the gas-liquid two-phase carbon dioxide energy storage system utilizing the waste heat of the thermal power plant, and has all the technical effects of the disclosure.

According to the control method disclosed by the invention, the waste heat of the thermal power plant is utilized to enable the carbon dioxide to absorb heat and evaporate or raise the temperature, so that the external heat supply of the gas-liquid two-phase carbon dioxide energy storage system is greatly reduced, and the investment and the occupied area of external heat supply equipment are greatly reduced; meanwhile, waste heat of the thermal power plant is recycled, and the energy utilization rate of the thermal power plant is improved.

The control method comprises the following steps:

when the energy storage assembly 2 works, the waste heat output by the work of the thermal power plant is led to the fifth heat exchanger 202 to provide heat for the carbon dioxide output by the gas storage 1 so as to increase the temperature of the carbon dioxide entering the compressor 201.

According to the control method disclosed by the disclosure, the waste heat of the thermal power plant is utilized to preheat and heat the gaseous carbon dioxide output by the gas storage 1, so that the inlet temperature of the compressor 201 is ensured to be stable, the operation requirement of the compressor 201 is met, the compressor 201 has a good operation state, and the energy storage efficiency of the energy storage system is further improved.

The working process of the gas-liquid two-phase carbon dioxide energy storage system utilizing the waste heat of the thermal power plant and the control method provided by the disclosure is described in detail by the following combination examples:

when the power grid is in the electricity consumption valley, the normal temperature and normal pressure carbon dioxide stored in the gas storage 1 enters the fifth heat exchanger 202 for preheating, the heat in the process can be directly provided by the high temperature flue gas in the flue 6 of the thermal power plant or can be provided by the heat storage medium output by the flue gas heat exchanger 51 and/or the heat storage component 52, the warmed carbon dioxide enters the compressor 201 for compression, the pressurized carbon dioxide enters the energy storage heat exchanger 203 for cooling, and the temperature is reduced after the warmed carbon dioxide exchanges heat with the heat exchange medium from the second cold storage tank 10, so that the heat storage in the energy storage process is completed, and the heat is stored in the second heat storage tank 9. The cooled low-temperature high-pressure carbon dioxide enters a condenser 204 to be cooled and condensed into liquid, the cold energy of the process is provided by a constant-temperature water pool 205, and the liquid carbon dioxide enters an energy storage container 3, so that the energy storage process is completed.

When the power grid is at a peak of electricity consumption, the low-temperature high-pressure carbon dioxide (liquid state) stored in the energy storage container 3 enters the evaporator 8 to absorb heat and evaporate, and the heat of the process is directly provided by the high-temperature flue gas in the flue 6 of the thermal power plant, and can also be provided by the flue gas heat exchanger 51 and/or the heat storage component 52. The evaporated carbon dioxide (gas state) enters the first energy release heat exchanger 53 for heating, and can exchange heat with the high-temperature heat storage working medium provided by the flue gas heat exchanger 51 and/or the first heat storage tank 521 and the heat exchange medium provided by the second heat storage tank 9 for heating. The high-temperature and high-pressure carbon dioxide enters the first expander 401 to expand and apply work to the outside, the main shaft of the first expander 401 is connected with the generator and drives the generator to generate power, the carbon dioxide output by the first expander 401 can also enter the second energy release heat exchanger 54 to heat up, and the carbon dioxide exchanges heat with the high-temperature heat storage working medium provided by the flue gas heat exchanger 51 and/or the first heat storage tank 521 and the heat exchange medium provided by the second heat storage tank 9 to heat up, and then enters the second expander 402 to apply work. The low-temperature normal-pressure carbon dioxide after doing work is cooled in the carbon dioxide cooler 12, the cooled carbon dioxide is stored in the gas storage 1 and gradually returns to the normal-temperature normal-pressure state, and the energy release process is completed.

In addition, in the energy release process, the liquid circulating working medium of the Rankine cycle assembly 7 absorbs heat in the third energy release heat exchanger 701 and then is converted into a gas state, the gas circulating working medium enters the third expander 702 to expand and do work, and the main shaft of the second expander 402 is connected with the generator and drives the generator to generate power.

It should be noted that, in the description of the present disclosure, unless explicitly specified and limited otherwise, the terms "mounted," "connected," and "connected" are to be construed broadly, and may be either fixedly connected, detachably connected, or integrally connected, for example; may be a mechanical connection; can be directly connected or indirectly connected through an intermediate medium, and can be communicated with the inside of two elements or the interaction relationship of the two elements. The specific meaning of the terms in this disclosure will be understood by those of ordinary skill in the art as the case may be.

The terms "first," "second," and the like, are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defining "a first" or "a second" may explicitly or implicitly include one or more features. In the description of the present disclosure, the meaning of "a plurality" is two or more, unless explicitly defined otherwise.

In this disclosure, unless expressly stated or limited otherwise, a first feature being "above" or "below" a second feature may include both the first and second features being in direct contact, as well as the first and second features not being in direct contact but being in contact with each other by way of additional features therebetween. Moreover, a first feature being "above," "over" and "on" a second feature includes the first feature being directly above and obliquely above the second feature, or simply indicating that the first feature is higher in level than the second feature. The first feature being "under", "below" and "beneath" the second feature includes the first feature being directly under and obliquely below the second feature, or simply means that the first feature is less level than the second feature.

In the description of the present specification, reference to the terms "certain embodiments," "one embodiment," "some embodiments," "an exemplary embodiment," "an example," "a particular example," or "some examples" means that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the present disclosure. On the premise that technical characteristics are not conflicting, structures are not contradictory and the aim of the invention is not violated, the technical schemes of the embodiments can be arbitrarily combined and matched for use.

The foregoing is illustrative of the present disclosure and is not to be construed as limiting thereof, but rather as various modifications, equivalent arrangements, improvements, etc., which are within the spirit and principles of the present disclosure.

Claims

1. A gas-liquid two-phase carbon dioxide energy storage system utilizing waste heat of a thermal power plant is characterized by comprising: the energy storage device comprises an air storage, an energy storage component, an energy storage container and an energy release component which are sequentially connected in a closed loop manner;

the heat absorption assembly is connected between the energy storage container and the energy release assembly and is connected with a thermal power plant, absorbs waste heat output by work of the thermal power plant, and provides heat for carbon dioxide flowing from the energy storage container to the energy release assembly so as to evaporate and/or heat the carbon dioxide.

2. The gas-liquid two-phase carbon dioxide energy storage system utilizing waste heat of thermal power plant according to claim 1, wherein the heat absorbing component is connected to a flue of the thermal power plant and is used for absorbing heat contained in high-temperature flue gas flowing through the flue.

3. The gas-liquid two-phase carbon dioxide energy storage system utilizing waste heat of a thermal power plant according to claim 2, wherein the heat absorbing assembly comprises a flue gas heat exchanger connected with a flue of the thermal power plant; the flue gas heat exchanger is used for absorbing heat of high-temperature flue gas by utilizing a heat storage working medium when the thermal power plant works.

4. The gas-liquid two-phase carbon dioxide energy storage system utilizing waste heat of a thermal power plant according to claim 3, wherein the heat absorbing assembly further comprises a heat storage assembly;

5. The gas-liquid two-phase carbon dioxide energy storage system utilizing waste heat of a thermal power plant according to claim 4, wherein the heat absorbing assembly further comprises a first energy releasing heat exchanger;

6. The gas-liquid two-phase carbon dioxide energy storage system utilizing waste heat of a thermal power plant according to claim 5, wherein the energy release assembly further comprises a second expander, and the heat absorption assembly further comprises a second energy release heat exchanger respectively connected with the first expander and the second expander;

7. The gas-liquid two-phase carbon dioxide energy storage system utilizing waste heat of a thermal power plant according to claim 6, further comprising: a rankine cycle assembly;

the Rankine cycle assembly comprises a third energy release heat exchanger and a third expander which are connected in a closed loop, and a circulating working medium which circularly flows is arranged between the third energy release heat exchanger and the third expander;

the third energy release heat exchanger is connected with the second energy release heat exchanger, and when the energy release assembly works, the heat storage working medium output by the second energy release heat exchanger provides heat for the circulating working medium in the third energy release heat exchanger, so that the heat-absorbing circulating working medium enters the third expansion machine to do work.

8. The gas-liquid two-phase carbon dioxide energy storage system utilizing waste heat of a thermal power plant according to claim 7, wherein the rankine cycle assembly further comprises a working medium condenser and a fourth heat exchanger;

9. The gas-liquid two-phase carbon dioxide energy storage system utilizing the waste heat of the thermal power plant is characterized by comprising a gas storage, an energy storage component, an energy storage container and an energy release component which are sequentially connected in a closed loop; the energy storage assembly comprises a fifth heat exchanger and a compressor;

the fifth heat exchanger is connected between the gas storage and the compressor and is connected with the thermal power plant, and the fifth heat exchanger is used for providing heat for carbon dioxide output by the gas storage through waste heat output by the work of the thermal power plant so as to improve the temperature of the carbon dioxide entering the compressor.

10. A control method of a gas-liquid two-phase carbon dioxide energy storage system utilizing waste heat of a thermal power plant, which is characterized by being applicable to the gas-liquid two-phase carbon dioxide energy storage system utilizing waste heat of a thermal power plant according to any one of claims 1 to 8;

the control method comprises the following steps:

when the energy release assembly works, waste heat output by the work of the thermal power plant is led to the heat absorption assembly, and heat is provided for carbon dioxide flowing from the energy storage container to the energy release assembly so as to evaporate or/and heat the carbon dioxide.