A dual-synergistic compressed air energy storage system

Abstract

The present invention relates to the field of energy storage technology, and discloses a dual-coordinated compressed air energy storage system, including a carbon dioxide circuit, a gas storage reservoir, and an air circuit connected in sequence; the gas storage reservoir is a pressure-bearing container, which is divided into an air cavity and a carbon dioxide gas cavity by a flexible diaphragm, and the flexible diaphragm can be freely scaled and not subjected to tension to keep the pressure of the air cavity and the carbon dioxide gas cavity equal and the volume adjustable; the carbon dioxide circuit includes a liquid storage tank, a carbon dioxide compressor, and a carbon dioxide expander, the liquid storage tank is respectively connected to the carbon dioxide compressor and the carbon dioxide expander, and the carbon dioxide compressor and the carbon dioxide expander are both connected to the carbon dioxide gas cavity; the air circuit includes an air compressor and an air expander, and the air compressor and the air expander are both connected to the air cavity. The present invention solves the problem of site selection flexibility of gas compression energy storage, so as to develop gas compression energy storage in numerous industrial parks or other applicable areas.

Description

Technical Field

[0001] The present invention relates to the field of energy storage technology, and in particular to a dual-coordinated compressed air energy storage system. Background Art

[0002] Compressed air energy storage is a physical energy storage method. At present, my country is at the world's leading level in the field of compressed air energy storage. It has successfully realized the non-regenerative compressed air energy storage technology route, built demonstration power stations in Bijie, Feicheng, Jintan, Zhangbei, etc., and is building a 300MW-class large-capacity compressed air energy storage power station. Due to the advantages of compressed air energy storage such as safety, environmental protection, high efficiency, long duration and long life, it has been included in national and local relevant plans as one of the important new energy storage technologies.

[0003] The compressed air energy storage power station has a large gas storage capacity and high gas storage pressure. The most technically mature and economically feasible gas storage method is still the traditional underground salt cavern gas storage. Artificial chambers are still in the demonstration and verification stage, and the cost of high-pressure pipeline gas storage is relatively high. The distribution area of ​​high-quality salt cavern resources is relatively scarce, which leads to great limitations in the development of compressed air energy storage power stations.

[0004] my country is the world's largest industrial manufacturing country, with about 20,000 industrial parks of various types, and carbon emissions from industrial parks account for 31% of the country's total carbon emissions. In industrially developed areas, especially in the eastern coastal areas, industrial parks have a very large demand for energy storage, and the policy incentives for energy storage are also strong, including widening the peak-valley electricity price difference, providing subsidies for energy storage projects, and supporting demonstrations of new energy storage technologies. Since most industrial parks do not have underground salt caverns or other underground gas storage resources, they are often not suitable for the development of artificial chambers, and land use indicators are relatively tight. Therefore, gas compression energy storage, including compressed air or compressed carbon dioxide energy storage, is applied to industrial parks. It is necessary to develop ground gas storage solutions that meet land use indicators and specifications and are economically feasible. Summary of the invention

[0005] The present invention provides a dual-cooperative compressed air energy storage system to solve the problem of site selection flexibility of gas compression energy storage, so as to develop gas compression energy storage in numerous industrial parks or other applicable areas.

[0006] The present invention provides a dual-coordinated compressed air energy storage system, comprising an air circuit, a carbon dioxide circuit and a gas storage reservoir, wherein the carbon dioxide circuit, the gas storage reservoir and the air circuit are connected in sequence;

[0007] The gas storage is a pressure container, which is divided into an air cavity and a carbon dioxide cavity by a flexible diaphragm, and the flexible diaphragm can be freely expanded and contracted without being subjected to tension, so as to keep the pressure of the air cavity and the carbon dioxide cavity equal and the volume can be adjusted;

[0008] The carbon dioxide circuit comprises a liquid storage tank, a carbon dioxide compressor and a carbon dioxide expander, wherein the liquid storage tank is connected to the carbon dioxide compressor and the carbon dioxide expander respectively, and the carbon dioxide compressor and the carbon dioxide expander are both connected to the carbon dioxide gas chamber;

[0009] The air circuit includes an air compressor and an air expander, and both the air compressor and the air expander are connected to the air chamber.

[0010] Furthermore, in the carbon dioxide circuit, the liquid storage tank and the carbon dioxide expander are connected by gasification, and the connecting pipeline between the liquid storage tank and the carbon dioxide expander is used as a gasification pipeline; the liquid storage tank and the carbon dioxide compressor are connected by condensation, and the connecting pipeline between the liquid storage tank and the carbon dioxide compressor is used as a condensation pipeline; low-temperature heat storage is performed between the gasification pipeline and the condensation pipeline.

[0011] Furthermore, the carbon dioxide compressor is connected to the first motor, and the exhaust pressure is 8MPa(a). The exhaust heat of the carbon dioxide compressor is recovered by a heat storage method, and high-pressure water heat storage is used for intake heat recovery of the carbon dioxide expander. The carbon dioxide expander is connected to the first generator, and the exhaust pressure is 3MPa(a).

[0012] Further, in the air circuit, the air compressor is divided into a first-stage compressor and a second-stage compressor, the first-stage compressor is connected to the second-stage compressor, and the connecting pipeline thereof is used as a compressor connecting pipeline; the air expander is divided into a first-stage expander and a second-stage expander, the first-stage expander is connected to the second-stage expander, and the connecting pipeline thereof is used as an expander connecting pipeline, and high-temperature heat is stored between the compressor connecting pipeline and the expander connecting pipeline;

[0013] The second-stage compressor is connected to the first-stage expander and both the second-stage compressor and the first-stage expander are connected to the air cavity. The connecting pipeline between the second-stage compressor and the air cavity is used as a compression pipeline, and the connecting pipeline between the first-stage expander and the air cavity is used as an expansion pipeline. Low-temperature heat storage is performed between the compression pipeline and the expansion pipeline.

[0014] Furthermore, the pressure ratio of the first-stage compressor is 10, the pressure ratio of the second-stage compressor is 3, the first-stage compressor is connected to the second motor, and the second-stage compressor is connected to the third motor.

[0015] Furthermore, the expansion ratio of the first-stage expander is 3, the expansion ratio of the second-stage expander is 10, and both the first-stage expander and the second-stage expander are connected to a second generator to jointly drive the second generator.

[0016] Furthermore, the exhaust heat of the air compressor is recovered by a heat storage method and used to reheat the air intake of the air expander; the exhaust heat temperature of the first-stage compressor is stored in molten salt and heat transfer oil, which is used for the intake heat recovery of the second-stage expander; the exhaust heat temperature of the second-stage compressor is stored in high-pressure water, which is used for the intake heat recovery of the first-stage expander.

[0017] Furthermore, the energy storage efficiency calculation formula of the dual-cooperative compressed air energy storage system is:

[0018] η=E out / E in

[0019] Where η is the energy storage efficiency, E out The output of the energy release process, E in Inputting electricity for the energy storage process; determining whether the compressed air energy storage level is reached by calculating the energy storage efficiency of the dual-cooperative compressed air energy storage system.

[0020] The beneficial effects of the present invention are:

[0021] The present invention uses a carbon dioxide circuit, a gas storage tank and an air circuit connected in sequence. The gas storage tank operates at a constant pressure, similar to a constant pressure compressed air energy storage system. The pressure of the gas storage tank is constant during operation, and the gas storage tank can be fully filled and discharged. High-pressure carbon dioxide can be liquefied at room temperature. The density of liquid carbon dioxide is large, and the volume of the liquid storage tank is much smaller than that of the gas storage tank, realizing the complementary advantages of compressed air energy storage and compressed carbon dioxide energy storage. The present invention integrates compressed air energy storage and compressed carbon dioxide energy storage, adopts a gas storage tank with a special structure, and constructs a gas compression energy storage system based on a ground gas storage reservoir, which gets rid of the dependence on geographical resources, is safe and environmentally friendly, has flexible site selection, and occupies a moderate area. It is suitable for supporting energy storage in industrial parks, serves industrial users, and gives full play to its multi-generation of electricity, gas, cold and heat. Compared with electrochemical energy storage, it has better commercial competitiveness. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a schematic structural diagram of the dual-cooperative compressed air energy storage system of the present invention.

[0023] The realization of the purpose, functional features and advantages of the present invention will be further explained in conjunction with embodiments and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0024] It should be understood that the specific embodiments described herein are only used to explain the present invention, and are not used to limit the present invention.

[0025] like Figure 1As shown, the present invention provides a dual-cooperative compressed air energy storage system, including an air circuit, a carbon dioxide circuit and a gas storage tank, wherein the carbon dioxide circuit, the gas storage tank and the air circuit are connected in sequence; the gas storage tank is a pressure container, which is divided into an air cavity and a carbon dioxide cavity by a flexible diaphragm, and the flexible diaphragm can be freely expanded and contracted without being subjected to tension, so as to keep the pressure of the air cavity and the carbon dioxide cavity equal and the volume adjustable; the carbon dioxide circuit includes a liquid storage tank, a carbon dioxide compressor and a carbon dioxide expander, wherein the liquid storage tank is respectively connected to the carbon dioxide compressor and the carbon dioxide expander, and the carbon dioxide compressor and the carbon dioxide expander are both connected to the carbon dioxide cavity; the air circuit includes an air compressor and an air expander, and the air compressor and the air expander are both connected to the air cavity.

[0026] In one embodiment, in the carbon dioxide circuit, the liquid storage tank is connected to the carbon dioxide expander by gasification, and the connecting pipeline between the liquid storage tank and the carbon dioxide expander is used as the gasification pipeline; the liquid storage tank is connected to the carbon dioxide compressor by condensation, and the connecting pipeline between the liquid storage tank and the carbon dioxide compressor is used as the condensation pipeline; low-temperature heat storage is performed between the gasification pipeline and the condensation pipeline. The carbon dioxide compressor is connected to the first motor, and the exhaust pressure is 8MPa(a). The exhaust heat of the carbon dioxide compressor is recovered by a heat storage method, and high-pressure water heat storage is used for the intake heat recovery of the carbon dioxide expander. The carbon dioxide expander is connected to the first generator, and the exhaust pressure is 3MPa(a).

[0027] In one embodiment, in the air circuit, the air compressor is divided into a one-stage compressor and a two-stage compressor, the one-stage compressor is connected to the two-stage compressor, and the connecting pipeline thereof is used as a compressor connecting pipeline; the air expander is divided into a one-stage expander and a two-stage expander, the one-stage expander is connected to the two-stage expander, and the connecting pipeline thereof is used as an expander connecting pipeline, and high-temperature heat storage is performed between the compressor connecting pipeline and the expander connecting pipeline; the two-stage compressor is connected to the one-stage expander and the two-stage compressor and the one-stage expander are both connected to the air cavity, the connecting pipeline between the two-stage compressor and the air cavity is used as a compression pipeline, the connecting pipeline between the one-stage expander and the air cavity is used as an expansion pipeline, and low-temperature heat storage is performed between the compression pipeline and the expansion pipeline.

[0028] In one embodiment, the pressure ratio of the first stage compressor is 10, the pressure ratio of the second stage compressor is 3, the first stage compressor is connected to a second motor, and the second stage compressor is connected to a third motor. The expansion ratio of the first stage expander is 3, the expansion ratio of the second stage expander is 10, and the first stage expander and the second stage expander are both connected to a second generator to jointly drive the second generator.

[0029] The operation process of the present invention is:

[0030] Initially, the system is in an energy-discharging state, the air cavity of the gas storage reservoir is in a gas-free state, and the carbon dioxide gas cavity is filled with carbon dioxide gas at a given storage pressure.

[0031] The energy storage stage includes the simultaneous compressed air energy storage and carbon dioxide liquefaction energy storage processes: the second motor and the third motor drive the air compressor to compress the air from the atmosphere to a given gas storage pressure and then send it to the air cavity. During this period, the air heat exchanger is used to recover the air compression heat and store it; at the same time, the first motor drives the carbon dioxide compressor to extract carbon dioxide from the carbon dioxide gas cavity and compress it to a liquefied pressure. During this period, the carbon dioxide heat exchanger is used to recover the gas carbon dioxide compression heat and store it, and then the carbon dioxide is condensed and liquefied and then sent to the liquid storage tank. During the energy storage process, the gas storage reservoir always maintains a given gas storage pressure. When the system is fully stored with energy, the air cavity is filled with compressed air and the carbon dioxide cavity is completely emptied.

[0032] The energy release stage includes the simultaneous energy release of liquid carbon dioxide gasification and expansion and compressed air expansion: high-pressure liquid carbon dioxide is output from the liquid storage tank and is gasified by the evaporator and heated by the carbon dioxide regenerator before being input into the carbon dioxide expander to generate electricity. The carbon dioxide after expansion and decompression to the given gas storage pressure is input into the carbon dioxide gas cavity; the compressed air output from the air cavity is heated by the air regenerator and expanded in the air expander to generate electricity, and then discharged into the atmosphere after expansion to atmospheric pressure. The heat of liquid carbon dioxide gasification includes waste heat from the system and the outside, and the heat of carbon dioxide and air regeneration comes from the system heat storage device. During the energy release process, the gas storage reservoir always maintains the given gas storage pressure. When the system energy is fully released, the carbon dioxide gas cavity is filled with compressed carbon dioxide gas, and the air cavity is completely emptied.

[0033] In one embodiment, the working pressure of the gas storage is 3MPa(a). On the one hand, this pressure is more favorable for the selection of pressure vessels, such as spherical tanks and pipeline gas storages; on the other hand, the liquefaction temperature of carbon dioxide under 3MPa(a) pressure is -5.55℃, which can prevent the gas in the carbon dioxide gas cavity from liquefying in low temperature seasons and causing pressure out of control.

[0034] The air circuit adopts a two-stage compression and two-stage expansion method. The compression ratio of the first-stage compressor is about 10, and the compression ratio of the second-stage compressor is about 3. The two-stage compressors are each equipped with an electric motor. The expansion ratio of the first-stage expander is about 3, and the expansion ratio of the second-stage expander is about 10. The two expanders jointly drive a generator. The heat of the compressor exhaust is recovered by the heat storage method and used to reheat the expander intake. The exhaust heat temperature of the first-stage compressor is high, and molten salt and heat transfer oil can be used for heat storage, which is used for heat recovery of the second-stage expander intake; the exhaust heat temperature of the second-stage compressor is low, and high-pressure water can be used for heat storage, which is used for heat recovery of the first-stage expander intake.

[0035] In one embodiment, the carbon dioxide loop adopts a one-stage compression and one-stage expansion method. The carbon dioxide compressor is equipped with an electric motor, and the exhaust pressure is about 8MPa(a). The exhaust heat of the carbon dioxide compressor is recovered by heat storage method. High-pressure water heat storage can be used for expander intake heat recovery. The critical point of carbon dioxide is 31°C / 7.4MPa(a). The condensation of carbon dioxide can be liquefied by environmental cooling, and the gasification of carbon dioxide can utilize the low-temperature waste heat of the industrial park and the system's own waste heat. The exhaust pressure of the carbon dioxide expander is 3MPa(a), which drives a generator.

[0036] In one embodiment, the energy storage efficiency calculation formula of the system of the present invention is:

[0037] η=E out / E in

[0038] Where η is the energy storage efficiency, E out The output of the energy release process, E in The amount of electricity inputted into the energy storage process; the energy storage efficiency of the system of the present invention is calculated by the above formula to determine whether the energy storage efficiency of the system of the present invention can reach the level of compressed air energy storage.

[0039] The present invention uses a carbon dioxide circuit, a gas storage tank and an air circuit connected in sequence. The gas storage tank operates at a constant pressure, similar to a constant pressure compressed air energy storage system. The pressure of the gas storage tank is constant during operation, and the gas storage tank can be fully filled and discharged. High-pressure carbon dioxide can be liquefied at room temperature. The density of liquid carbon dioxide is large, and the volume of the liquid storage tank is much smaller than that of the gas storage tank, realizing the complementary advantages of compressed air energy storage and compressed carbon dioxide energy storage. The present invention integrates compressed air energy storage and compressed carbon dioxide energy storage, adopts a gas storage tank with a special structure, and constructs a gas compression energy storage system based on a ground gas storage reservoir, which gets rid of the dependence on geographical resources, is safe and environmentally friendly, has flexible site selection, and occupies a moderate area. It is suitable for supporting energy storage in industrial parks, serves industrial users, and gives full play to its multi-generation of electricity, gas, cold and heat. Compared with electrochemical energy storage, it has better commercial competitiveness.

[0040] It should be noted that, in this article, the terms "include", "comprises" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, device, article or method including a series of elements includes not only those elements, but also includes other elements not explicitly listed, or also includes elements inherent to such process, device, article or method. In the absence of further restrictions, an element defined by the sentence "includes a ..." does not exclude the presence of other identical elements in the process, device, article or method including the element.

[0041] The above description is only a preferred embodiment of the present invention, and does not limit the patent scope of the present invention. Any equivalent structure or equivalent process transformation made by using the contents of the present invention specification and drawings, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. A dual-coordinated compressed air energy storage system, characterized in that: It includes an air circuit, a carbon dioxide circuit and a gas storage tank, wherein the carbon dioxide circuit, the gas storage tank and the air circuit are connected in sequence; The gas storage is a pressure container, which is divided into an air cavity and a carbon dioxide cavity by a flexible diaphragm, and the flexible diaphragm can be freely expanded and contracted without being subjected to tension, so as to keep the pressure of the air cavity and the carbon dioxide cavity equal and the volume can be adjusted; The carbon dioxide circuit comprises a liquid storage tank, a carbon dioxide compressor and a carbon dioxide expander, wherein the liquid storage tank is connected to the carbon dioxide compressor and the carbon dioxide expander respectively, and the carbon dioxide compressor and the carbon dioxide expander are both connected to the carbon dioxide gas chamber; The air circuit includes an air compressor and an air expander, and both the air compressor and the air expander are connected to the air chamber.

2. The dual-coordinated compressed air energy storage system according to claim 1, characterized in that: In the carbon dioxide circuit, the liquid storage tank is connected to the carbon dioxide expander by gasification, and the connecting pipeline between the liquid storage tank and the carbon dioxide expander is used as the gasification pipeline; the liquid storage tank is connected to the carbon dioxide compressor by condensation, and the connecting pipeline between the liquid storage tank and the carbon dioxide compressor is used as the condensation pipeline; low-temperature heat storage is performed between the gasification pipeline and the condensation pipeline.

3. The dual-coordinated compressed air energy storage system according to claim 2, characterized in that: The carbon dioxide compressor is connected to the first motor, and the exhaust pressure is 8MPa(a). The exhaust heat of the carbon dioxide compressor is recovered by a heat storage method, and high-pressure water heat storage is used for the intake heat recovery of the carbon dioxide expander. The carbon dioxide expander is connected to the first generator, and the exhaust pressure is 3MPa(a).

4. The dual-coordinated compressed air energy storage system according to claim 3 is characterized in that: In the air circuit, the air compressor is divided into a one-stage compressor and a two-stage compressor, the one-stage compressor is connected to the two-stage compressor, and the connecting pipeline thereof is used as a compressor connecting pipeline; the air expander is divided into a one-stage expander and a two-stage expander, the one-stage expander is connected to the two-stage expander, and the connecting pipeline thereof is used as an expander connecting pipeline, and high-temperature heat is stored between the compressor connecting pipeline and the expander connecting pipeline; The second-stage compressor is connected to the first-stage expander and both the second-stage compressor and the first-stage expander are connected to the air cavity. The connecting pipeline between the second-stage compressor and the air cavity is used as a compression pipeline, and the connecting pipeline between the first-stage expander and the air cavity is used as an expansion pipeline. Low-temperature heat storage is performed between the compression pipeline and the expansion pipeline.

5. The dual-coordinated compressed air energy storage system according to claim 4, characterized in that: The pressure ratio of the first-stage compressor is 10, the pressure ratio of the second-stage compressor is 3, the first-stage compressor is connected to the second motor, and the second-stage compressor is connected to the third motor.

6. The dual-coordinated compressed air energy storage system according to claim 5, characterized in that: The expansion ratio of the first-stage expander is 3, the expansion ratio of the second-stage expander is 10, and both the first-stage expander and the second-stage expander are connected to a second generator to jointly drive the second generator.

7. The dual-coordinated compressed air energy storage system according to claim 6, characterized in that: The exhaust heat of the air compressor is recovered by a heat storage method and used to reheat the air intake of the air expander; the exhaust heat temperature of the first-stage compressor is stored in molten salt and heat transfer oil, which is used for the intake heat recovery of the second-stage expander; the exhaust heat temperature of the second-stage compressor is stored in high-pressure water, which is used for the intake heat recovery of the first-stage expander.

8. The dual-coordinated compressed air energy storage system according to claim 7, characterized in that: The energy storage efficiency calculation formula of the dual-coordinated compressed air energy storage system is: η=E out / AND in Where η is the energy storage efficiency, E out The output of the energy release process, E in Inputting electricity for the energy storage process; determining whether the compressed air energy storage level is reached by calculating the energy storage efficiency of the dual-cooperative compressed air energy storage system.

Images