Compressed air energy storage system based on compression and expansion dual-purpose unit

Abstract

The invention discloses a compressed air energy storage system based on a compression-expansion dual-purpose unit, relates to the technical field of compressed air energy storage, and solves the technical problem that the existing compressed air energy storage system is relatively complex and has a high cost. The key points of the technical solution are to use a single-stage multi-cylinder rotary compression-expansion dual-purpose unit to replace two sets of equipment, a compressor unit and an expansion unit, which has the advantages of large and adjustable pressure ratio, high isentropic efficiency, low manufacturing cost and suitability for large and medium-sized units; water is used to adjust the compressed air outlet temperature and to enhance the heat transfer of the heat exchanger; an air-water separator, a small water tank and an air-water mixer are provided to achieve the water sprayed in the compression and inflation process. After being cooled by the heat exchanger, it is stored under high pressure and reused in the expansion work process, which can increase the working capacity of the compressed air in the expander and also enhance the heat transfer of the heat exchanger.

Description

Technical Field

[0001] The present application relates to the technical field of compressed air energy storage, and in particular to a compressed air energy storage system based on a compression-expansion dual-purpose unit. Background Art

[0002] The intermittent nature of renewable energy generation such as solar and wind power requires that they must be equipped with energy storage systems in order to be accepted by the power grid. Pumped storage power stations are limited by the scarce geological conditions of the upper and lower reservoirs, while the underground cave resources required by compressed air energy storage systems are relatively abundant, making it a solution with broad application prospects.

[0003] The compressed air energy storage system consumes electricity to drive the compressor to compress the air and store it in the gas storage container during periods of abundant and excess power generation from renewable energy sources. The compressed air is then released from the gas storage container during periods of peak power demand to drive the expander to drive the generator to generate electricity.

[0004] Energy storage technology is an important means to achieve the goal of carbon neutrality, improve the utilization rate of renewable energy such as solar energy and wind energy, improve the current situation of "abandoning solar energy" and "abandoning wind energy", and stabilize the operation of the power grid. However, the current compressed air energy storage system mainly adopts the solution of multi-stage compressor intermediate cooling and multi-stage expander intermediate heating. Its process is relatively complicated, the equipment is relatively large and expensive, and there is a problem of large investment in system equipment, and it is difficult to make profits by using the difference between peak and valley electricity prices. Summary of the invention

[0005] The present application provides a compressed air energy storage system based on a compression-expansion dual-purpose unit, and its technical purpose is to simplify the setting of the compressed air energy storage system to achieve efficient and low-cost energy storage.

[0006] The above technical objectives of this application are achieved through the following technical solutions:

[0007] A compressed air energy storage system based on a compression-expansion dual-purpose unit, comprising an air filter, a one-way air valve, a water spray adjustment system, a compression-expansion dual-purpose unit, a heat exchanger, an air-cooled oil cooler, an air-water separator, a small water tank, an air-water mixer, a spiral channel storage tank, an oil pump, a four-way valve, an oil expansion tank, a valve group and an underground cave; the valve group comprises three three-way valves and two two-way valves;

[0008] The air filter and the one-way air valve are connected to the air interface of the low-pressure end of the compression and expansion dual-purpose unit through a three-way pipe; the water spray adjustment system and the drain pipe are connected to the water interface of the low-pressure end of the compression and expansion dual-purpose unit through a three-way valve A; the high-pressure end interface of the compression and expansion dual-purpose unit is connected to the high-temperature end interface of the air side of the heat exchanger; the low-temperature end interface of the air side of the heat exchanger is connected to the three-way valve B; the other two interfaces of the three-way valve B are respectively connected to the inlet of the air-water separator and the outlet of the air-water mixer; the water side outlet of the air-water separator is connected to the inlet of the small water tank, and the outlet of the small water tank is connected to the water side inlet of the air-water mixer through a two-way valve D; the air side outlet of the air-water separator and the air side inlet of the air-water mixer are both connected to the inlet and outlet pipelines of the underground cave through a three-way pipe and a two-way valve E;

[0009] The high-temperature end interface of the energy storage fluid heat transfer oil side of the heat exchanger is connected to the top interface of the spiral channel storage tank; the low-temperature end interface of the energy storage fluid heat transfer oil side of the heat exchanger is respectively connected to the inlet of the air-cooled oil cooler and the upper interface of the three-way valve C through a three-way pipe, the outlet of the air-cooled oil cooler is connected to the left interface of the three-way valve C, the lower interface of the three-way valve C is connected to the left interface of the four-way valve, the right interface of the four-way valve is connected to the bottom interface of the spiral channel storage tank, the upper interface of the four-way valve is connected to the outlet of the oil pump, and the lower interface of the four-way valve is connected to the inlet of the oil pump and the interface pipeline of the oil expansion tank through a three-way pipe.

[0010] Furthermore, the underground cave is a constant-pressure compressed air energy storage system or a variable-pressure compressed air energy storage system.

[0011] Underground caves adopt constant pressure or variable pressure compressed air energy storage systems according to the characteristics of whether they can be operated underground. In underground caves with large vertical shafts such as abandoned coal mines, nylon pipes can be placed in the underground tunnels, and in conjunction with ground water pools, a constant pressure gas storage system with air in and water out, air out and water in can be formed in the nylon pipes. This can not only improve the volume utilization rate of the cave, but also realize the operation of the compression and expansion dual-purpose machine at the designed operating point.

[0012] The beneficial effects of this application are:

[0013] (1) The compression-expansion dual-purpose machine adopts a single-stage multi-cylinder rotary compression-expansion dual-purpose machine scheme, and uses a compression-expansion dual-purpose unit to replace two sets of equipment, namely, the compressor unit and the expansion unit, and uses water spray to adjust the compressed air outlet temperature. It has the advantages of large and adjustable pressure ratio, high isentropic efficiency, low manufacturing cost and suitability for large and medium-sized units. The use of the compression-expansion dual-purpose unit can greatly simplify the process, improve efficiency and greatly reduce equipment costs, just like the turbine and water pump dual-purpose units of pumped storage power stations.

[0014] (2) The operation of the compressed air energy storage system is divided into a compression energy storage stage and an expansion energy release stage. In addition to the compressor unit and the expansion unit, the heat exchanger is also a relatively expensive equipment in the compressed air energy storage system, and the thermal oil storage tank is a device that occupies a large space. The present application shares a set of compression / expansion, heat exchange, and energy storage equipment. The system equipment is simple and compact. The mode of sharing a set of heat exchangers and cold and hot thermal oil storage tanks for the energy storage and release processes can also greatly simplify the process and improve operating efficiency. At the same time, it greatly makes the system equipment compact and reduces the initial investment and operating costs of the system equipment.

[0015] (3) Spraying water during the compression and inflation process can not only adjust the temperature of the compressed air at the compressor outlet, but also enhance the heat transfer of the heat exchanger. By setting up an air-water separator, a small water tank and an air-water mixer, the water sprayed during the compression and inflation process can be stored under high pressure, avoiding the use of a high-pressure water pump. The high-pressure water in the small water tank is returned to the compressed air before entering the heat exchanger during the expansion process, which can increase the working capacity of the compressed air in the expander. At the same time, it can also enhance the heat transfer of the heat exchanger and reduce the heat exchange area. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 This is a schematic diagram of the system flow when inflating an underground cave during the compression and inflation stage of this application;

[0017] Figure 2 This is a schematic diagram of the system flow when the present application utilizes high-pressure gas in an underground cave to drive a compression-expansion dual-purpose unit to expand and generate electricity;

[0018] In the figure: 1. Air filter; 2. One-way air valve; 3. Water spray regulation system; 4. Compression expansion dual-purpose unit; 5. Heat exchanger; 6. Air-cooled oil cooler; 7. Air-water separator; 8. Small water tank; 9. Air-water mixer; 10. Spiral channel storage tank; 11. Oil pump; 12. Four-way valve; 13. Oil expansion tank; 14. Valve group; 14-1. Three-way valve A; 14-2. Three-way valve B; 14-3. Three-way valve C; 14-4. Two-way valve D; 14-5. Two-way valve E; 15. Underground cave. DETAILED DESCRIPTION

[0019] The technical solution of the present application will be described in detail below with reference to the accompanying drawings.

[0020] The operation process of the embodiment of the present application is as follows:

[0021] like Figure 1 As shown, during the off-peak period of electricity consumption, when the abundant off-peak electricity is used to drive the compressor unit to inflate the underground cave 15, its operation process includes the following steps:

[0022] The compression and expansion unit 4 inhales air from the atmosphere through the air filter 1 from the upper interface of the low-pressure end, and the lower interface is provided with appropriate flow of water spray by the water spray regulating system 3 through the three-way valve A14-1, so that the heat released during the compression process is used to heat the spray water to evaporate and maintain a suitable outlet temperature; the outlet gas of the compression and expansion unit 4 enters the heat exchanger 5 to heat the heat transfer oil on the other side, and the steam in it condenses into water droplets again after being cooled. The gas-water mixture is guided to the gas-water separator 7 through the three-way valve B14-2, and the water is stored in the small water tank 8, and the compressed air flows to the underground cave 15 through the two-way valve E14-5. At the same time, the cold heat transfer oil flows out from the bottom interface of the spiral channel storage tank 10 under the drive of the oil pump 11 and the guidance of the four-way valve 12 and flows to the other side of the heat exchanger, cooling the compressed air, and flows back to the spiral channel storage tank 10 from the top interface of the spiral channel storage tank 10 after being heated.

[0023] like Figure 2 As shown, during the peak hours of electricity consumption, when compressed air stored in underground caves is used to drive the expansion unit to generate electricity, its operation process includes the following steps:

[0024] The compressed air flows from the underground cave 15 to the gas-water mixer 9 through the two-way valve E14-5, and at the same time, the two-way valve D14-4 is adjusted to add water from the small water tank 8 to the gas-water mixer 9 at an appropriate flow rate. The gas-water mixture is guided to the heat exchanger 5 through the three-way valve B14-2, and is heated by the heat transfer oil on the other side, and the temperature rises and the water evaporates to become high-temperature and high-pressure wet air, and then flows to the compression-expansion dual-purpose unit 4 to expand and generate electricity. The gas in the outlet mixture returns to the atmosphere from the upper interface of the low-pressure end through the one-way air valve 2, and the liquid water flows out from the lower interface of the low-pressure end through the three-way valve A14-1, and can continue to be reused through the water spray regulation system 3. At the same time, the hot heat transfer oil, driven by the oil pump 11 and guided by the four-way valve 12, flows out from the top interface of the spiral channel storage tank 10 and flows to the other side of the heat exchanger, heating the compressed air, cooling itself, and then further cooling through the air-cooled oil cooler 6, and then flows back to the spiral channel storage tank 10 from the bottom interface of the spiral channel storage tank 10. The air-cooled oil cooler 6 can make the heat transfer oil have a stronger cooling capacity in the next round of energy storage cycle.

[0025] The above are exemplary embodiments of the present application, and the protection scope of the present application is defined by the claims and their equivalents.

Claims

1. A compressed air energy storage system based on a compression-expansion dual-purpose unit, characterized in that: It comprises an air filter (1), a one-way air valve (2), a water spray regulating system (3), a compression and expansion dual-purpose unit (4), a heat exchanger (5), an air-cooled oil cooler (6), an air-water separator (7), a small water tank (8), an air-water mixer (9), a spiral channel storage tank (10), an oil pump (11), a four-way valve (12), an oil expansion tank (13), a valve group (14) and an underground cave (15); the valve group (14) comprises three three-way valves and two two-way valves; The air filter (1) and the one-way air valve (2) are connected to the air interface at the low-pressure end of the compression and expansion dual-purpose unit (4) through a three-way pipe; the water spray adjustment system (3) and the drain pipe are connected to the water interface at the low-pressure end of the compression and expansion dual-purpose unit (4) through a three-way valve A (14-1); the high-pressure end interface of the compression and expansion dual-purpose unit (4) is connected to the high-temperature end interface of the air side of the heat exchanger (5); the low-temperature end interface of the air side of the heat exchanger (5) is connected to the three-way valve B (14-2); the three-way valve B (14-1) is connected to the water interface at the low-pressure end of the compression and expansion dual-purpose unit (4 ... -2) are respectively connected to the inlet of the gas-water separator (7) and the outlet of the gas-water mixer (9); the water side outlet of the gas-water separator (7) is connected to the inlet of the small water tank (8), and the outlet of the small water tank (8) is connected to the water side inlet of the gas-water mixer (9) through a two-way valve D (14-4); the gas side outlet of the gas-water separator (7) and the gas side inlet of the gas-water mixer (9) are both connected to the inlet and outlet pipelines of the underground cave (15) through a three-way pipe and a two-way valve E (14-5); The high-temperature end interface of the energy storage fluid heat transfer oil side of the heat exchanger (5) is connected to the top interface of the spiral channel storage tank (10); the low-temperature end interface of the energy storage fluid heat transfer oil side of the heat exchanger (5) is respectively connected to the inlet of the air-cooled oil cooler (6) and the upper interface of the three-way valve C (14-3) through a three-way pipe, the outlet of the air-cooled oil cooler (6) is connected to the left interface of the three-way valve C (14-3), the lower interface of the three-way valve C (14-3) is connected to the left interface of the four-way valve (12), the right interface of the four-way valve (12) is connected to the bottom interface of the spiral channel storage tank (10), the upper interface of the four-way valve (12) is connected to the outlet of the oil pump (11), and the lower interface of the four-way valve (12) is connected to the inlet of the oil pump (11) and the interface pipeline of the oil expansion tank (13) through a three-way pipe.

2. The compressed air energy storage system according to claim 1, characterized in that: The underground cave (15) is a constant-pressure compressed air energy storage system or a variable-pressure compressed air energy storage system.

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