An ORC-coupled non-supplementary heat compressed air energy storage system and method

Abstract

The present invention discloses an ORC-coupled non-supplementary heat compressed air energy storage system and method, which includes a compressed air energy storage system, a heat storage system, a first water heat storage system, a second water heat storage system, and an ORC low-temperature power generation system; the air outlet of the air storage reservoir of the compressed air energy storage system is successively connected with a gas-water heater, an air high-temperature heater, and an air turbine unit; a cooler group is arranged between the two-stage compressors in the compressed air energy storage system; the hot side of the gas-water heater is connected to the first water heat storage system, the hot side of the air high-temperature heater is connected to the high-temperature heat storage system, and the cold sides of the cooler group are respectively connected to the high-temperature heat storage system and the first water heat storage system; the inlet and outlet of the heating working medium of the ORC low-temperature power generation system are connected to the inlet and outlet of the second water heat storage system; the present invention uses low-valley electricity or abandoned wind and solar power to compress air for energy storage, stores the low-grade heat generated during air compression, and couples the compressed air energy storage system with the ORC low-temperature waste heat power generation technology to recover and utilize the waste heat of compressed air, thereby improving the overall electricity-electricity conversion efficiency.

Description

Technical Field

[0001] The present invention belongs to the technical field of energy storage, and relates to an ORC-coupled non-supplementary heat compressed air energy storage system and method. Background Art

[0002] Industrial and commercial enterprises need to consume a large amount of electricity to maintain the normal operation of production equipment and supporting facilities. With the increase in power consumption, the peak-valley load difference of the power grid is getting larger and larger. In order to improve the power load balance problem and cope with the current situation that electricity is difficult to store on a large scale, various energy storage methods are being studied more and more deeply. Compressed-Air Energy Storage (hereinafter referred to as CAES) means that during the low-load period of the power grid, electrical energy is used to compress air, and the high-pressure air is sealed in abandoned mines, sunken undersea gas storage tanks, caves, salt caverns or newly built gas storage wells, and the compressed air is released during the peak-load period of the power grid to drive a turbine expander for power generation.

[0003] Compressed air energy storage provides a new solution for China to build a new power system to achieve large-scale storage of electrical energy and "peak shaving and valley filling", which will strongly promote the large-scale consumption of new energy. However, the low-grade heat source in the system cannot be used in the power generation process and needs to be dissipated with the cooling system, resulting in waste of resources and increasing the investment in cooling equipment. The overall technical economy of the system needs to be improved. Summary of the Invention

[0004] In order to solve the problems existing in the prior art, the present invention provides an ORC (Organic Rankine Cycle) coupled non-supplementary heat compressed air energy storage system, which overcomes the deficiencies of the existing technology. By combining compressed air energy storage with ORC low-temperature waste heat power generation technology, the system efficiency can be further improved, zero-carbon operation can be realized, and power generation can be carried out using the lower-grade heat that cannot be utilized by the original compressed air power generation system, thereby reducing energy consumption and improving the electricity-electricity conversion efficiency.

[0005] To achieve the above object, the technical solution adopted by the present invention is: an ORC-coupled non-supplementary heat compressed air energy storage system, comprising a compressed air energy storage system, an air-water heater, an air high-temperature heater, an air turbine unit, a generator, a high-temperature heat storage system, a first water heat storage system, a second water heat storage system, and an ORC low-temperature power generation system; the air outlet of the air storage chamber of the compressed air energy storage system is sequentially connected to the air-water heater, the air high-temperature heater, and the air turbine unit; the air turbine unit is connected to the generator; the compressed air energy storage system includes a multi-stage compressor, and a cooler group is arranged between two-stage compressors; the hot side of the air-water heater is connected to the first water heat storage system, the hot side of the air high-temperature heater is connected to the high-temperature heat storage system, and the cold sides of the cooler group are respectively connected to the high-temperature heat storage system and the first water heat storage system; the inlet and outlet of the heating working medium of the ORC low-temperature power generation system are connected to the inlet and outlet of the second water heat storage system; the second water heat storage system provides a heat source for the ORC low-temperature power generation system.

[0006] The heat exchanger group between two adjacent stages of compressors includes an air cooler and an air-water cooler, the cold side of the air cooler is connected to the heat storage system; the cold side of the air-water cooler is connected to the first water heat storage system.

[0007] The high-temperature heat storage system includes a hot medium tank and a cold medium tank, the outlet of the hot medium tank is connected to the hot side inlet of the air high-temperature heater, and the inlet of the cold medium tank is connected to the hot side outlet of the air high-temperature heater; the heat storage medium in the high-temperature heat storage system is molten salt, heat-conducting oil, sand or heat storage particles.

[0008] The first water heat storage system includes a hot water tank and a cold water tank, the outlet of the hot water tank is connected to the hot side inlet of the air-water heater, and the inlet of the cold water tank is connected to the hot side outlet of the air-water heater; the cold side inlet and outlet of the air-water cooler are respectively connected to the inlet of the hot water tank and the outlet of the cold water tank.

[0009] A low-temperature heat exchanger is arranged at the outlet of the last-stage compressor, the low-temperature heat exchanger is connected to the second water heat storage system and provides heat for the second water heat storage system, and the inlet and outlet of the second water heat storage system are respectively connected to the inlet and outlet of the heating working medium of the ORC low-temperature power generation system.

[0010] The air turbine unit is provided with at least two-stage air turbines, and an air-water heater and an air high-temperature heater are sequentially arranged at the inlet of each stage of air turbine along the medium flow direction, the hot side of the air-water heater is connected to the first water heat storage system, and the hot side of the air high-temperature heater is connected to the high-temperature heat storage system.

[0011] The air storage chamber adopts a single chamber or multiple chambers in parallel.

[0012] A self-cleaning filter is arranged at the inlet of the compressed air energy storage system.

[0013] A regulating valve is arranged at the outlet of the compressed air energy storage system.

[0014] Operation method of ORC-coupled non-supplementary heat compressed air energy storage system of the present invention: Air is compressed and stored through the compressed air energy storage system. The compressed air passes through the air-water heater and the air high-temperature heater, exchanges heat with the first water heat storage system and the high-temperature heat storage respectively, and then enters the air turbine unit to do work, so that the air turbine unit drives the generator to generate electricity. Among them, the cooler group absorbs the heat generated during the compression of the compressed air, and at the same time stores the heat into the first water heat storage system and the high-temperature heat storage system through water and heat storage medium respectively. The first water heat storage system and the high-temperature heat storage system use the heat to heat the compressed air, and the second water heat storage system provides heat source for the ORC low-temperature power generation system.

[0015] Compared with the prior art, the present invention has at least the following beneficial effects:

[0016] The present invention uses low-valley electricity or abandoned wind and light electricity to compress air for energy storage, stores the low-grade heat during air compression in the water heat storage system, couples the compressed air energy storage system with the ORC low-temperature waste heat power generation technology, recovers and utilizes the waste heat of the compressed air, and improves the overall electricity-electricity conversion efficiency. While utilizing the low-grade heat source, it directly reduces the investment in the cooling equipment required for compressing heat digestion. During the peak electricity consumption period, compressed air is used to drive the air turbine to generate electricity and be connected to the grid. The ORC low-temperature power generation system can absorb the low-grade waste heat of air compression, so that the overall energy efficiency of the system is improved, and the electricity-electricity efficiency can reach more than 70%. It can be widely applied to high-power-consuming industrial and commercial enterprises, greatly reducing electricity costs, serving as a backup power supply, and also providing heating and cooling, and has great practical value for power grid balance, with high economic and social benefits and engineering practical value. Brief Description of the Drawings

[0017] Figure 1 is an ORC-coupled non-supplementary heat compressed air energy storage system;

[0018] In the figure: 1. Self-cleaning filter, 2. Compressor, 3. Air cooler, 4. Air-water cooler, 5. Gas storage chamber, 6. Air-water heater, 7. Air high-temperature heater, 8. Air turbine, 9. Generator, 10. Heat medium tank, 11. Cold medium tank, 12. Hot water tank, 13. Cold water tank, 14. ORC low-temperature power generation system. Detailed Embodiments

[0019] The present invention will be described in detail below in conjunction with the drawings and specific embodiments.

[0020] Reference Figure 1, the present invention provides an ORC-coupled non-supplementary heat compressed air energy storage system, which includes a compressor unit, a gas storage chamber 5, a gas-water heater 6, an air high-temperature heater 7, an air turbine 8, a generator 9, a high-temperature heat storage system, a first water heat storage system, a second water heat storage system, and an ORC low-temperature power generation system 14; the outlet of the compressor unit is sequentially connected to the gas storage chamber 5, the gas-water heater 6, the air high-temperature heater 7, and the air turbine 8; the air turbine 8 is connected to the generator 9; the compressor unit includes a plurality of compressors 2, and a cooler group is arranged between two-stage compressors; the hot side of the gas-water heater 6 is connected to the first water heat storage system, the hot side of the air high-temperature heater 7 is connected to the high-temperature heat storage system, and the cooler group is respectively connected to the high-temperature heat storage system and the first water heat storage system; the heating working medium inlet and outlet of the ORC low-temperature power generation system 14 are connected to the inlet and outlet of the second water heat storage system; the second water heat storage system supplies heat to the ORC low-temperature power generation system 14; the high-temperature heat storage system includes a hot medium tank 10 and a cold medium tank 11, the first water heat storage system includes a hot water tank 12 and a cold water tank 13, and the second water heat storage system has the same structure as the first water heat storage system.

[0021] The heat storage medium in the high-temperature heat storage system is molten salt, heat-conducting oil, sand or heat storage particles; the outlet of the hot medium tank 10 is connected to the hot side inlet of the air high-temperature heater 7, the inlet of the cold medium tank 11 is connected to the hot side outlet of the air high-temperature heater 7, and the heat exchanger group between the compressors includes an air cooler 3 and a gas-water cooler 4, and the cold side of the air cooler 3 is connected to the high-temperature heat storage system; specifically, the cold side inlet of the air cooler 3 is connected to the cold medium tank 11, and the cold side outlet of the air cooler 3 is connected to the inlet of the hot medium tank 10; the cold side of the gas-water cooler 4 is connected to the first water heat storage system. The high-temperature heat storage system means that the temperature of the heat storage medium is higher than the temperatures of the first water heat storage system and the second water heat storage system.

[0022] Taking the molten salt medium as an example for the high-temperature heat storage system, the outlet of the hot salt tank is connected to the hot side inlet of the air high-temperature heater 7, the inlet of the cold salt tank is connected to the hot side outlet of the air high-temperature heater 7, and the cold side inlet and outlet of the air cooler 3 are respectively connected to the outlet of the cold salt tank and the inlet of the hot salt tank.

[0023] The outlet of the hot water tank 12 is connected to the hot side inlet of the gas-water heater 6, and the inlet of the cold water tank 13 is connected to the hot side outlet of the gas-water heater 6; the cold side inlet of the gas-water cooler 4 is connected to the outlet of the cold water tank 13, and the cold side outlet of the gas-water cooler 4 is connected to the inlet of the hot water tank 12.

[0024] As an optional embodiment, the turbine 8 is provided with multiple stages, and a gas-water heater 6 and an air high-temperature heater 7 are sequentially arranged at the inlet of each stage of the turbine 8 along the medium flow direction. The hot side of the gas-water heater 6 is connected to the first water heat storage system, and the hot side of the air high-temperature heater 7 is connected to the high-temperature heat storage system.

[0025] The inlet and outlet of the heating working fluid of the ORC low-temperature power generation system 14 are respectively connected to the outlet of the hot water tank 12 and the inlet of the cold water tank 13. Taking molten salt as the heat storage medium as an example:

[0026] The first part, Figure 1 The shown ORC coupled with a non-supplementary heat compression air energy storage system: During the compression energy storage process, the compression air subsystem generally adopts a multi-stage compression and inter-stage cooling method. The air enters the compressor 2 through the self-cleaning filter 1. The air at the outlet of each stage of the compressor enters the air cooler 3 for high-temperature section heat exchange, heating the low-temperature molten salt and storing it in the hot molten salt tank; then it passes through the air-water cooler 4 for low-temperature section heat exchange, heating the cold water into high-temperature hot water and storing it in the hot water tank 12. Only a low-temperature heat exchanger 41 is set at the outlet of the last stage of the compressor. The low-temperature heat exchanger 41 is connected to the second water heat storage system. The high-pressure normal-temperature air after compression and cooling is stored in the high-pressure gas storage tank 5.

[0027] During the energy release and power generation process, the high-pressure air in the gas storage tank 5 drives the air turbine and then drives the generator to complete power generation. This process adopts a multi-stage expansion process of preheating + reheat. To maintain the stable operation of the turbine and improve the work capacity of the air, the high-pressure air in the gas storage tank 5 is throttled to the rated pressure by the main regulating valve or supplemented with air through the air supply valve, and then enters the air-water heater 6 first, heating the air with the hot water in the hot water tank 12. The cooled cold water is stored in the cold water tank 13; then it enters the air high-temperature heater 7, heating the air with the molten salt in the hot salt tank. The cooled molten salt is stored in the cold molten salt tank. The heated high-temperature and high-pressure hot air enters the turbine 8 to drive the generator 9 to do work. After the air expands to a certain extent, both the temperature and pressure decrease. Subsequently, the air enters the next section of the air-water heater 6 and the air high-temperature heater 7, completes a reheat using the heat of water and molten salt, and then enters the next section of the turbine to do work.

[0028] The heat released by the cooling of the high-temperature air at the outlets of the first few stages of the compressor can meet the heat required for multiple reheats of the turbine. The heat released at the outlet of the last stage of the compressor, due to its low heat grade, does not participate in the power generation process. A separate water heat storage system is set up, which is provided with a hot water tank 12 and a cold water tank 13. The hot water tank 12 and the cold water tank 13 are respectively connected to the inlet and outlet of the ORC low-temperature power generation system 14. During the energy release and power generation process, the ORC low-temperature power generation system 14 is synchronously set up to utilize the lower-grade heat generated by the last stage of the compressor.

Claims

1. An ORC-coupled non-supplementary heat compressed air energy storage system, characterized in that, It includes a compressed air energy storage system, an air-water heater (6), an air high-temperature heater (7), an air turbine unit, a generator (9), a high-temperature heat storage system, a first water heat storage system, a second water heat storage system, and an ORC low-temperature power generation system (14); the air outlet of the gas storage chamber of the compressed air energy storage system is sequentially connected to the air-water heater (6), the air high-temperature heater (7), and the air turbine unit; the air turbine unit is connected to the generator (9); the compressed air energy storage system includes a multi-stage compressor, and a cooler group is arranged between two-stage compressors; the hot side of the air-water heater (6) is connected to the first water heat storage system, the hot side of the air high-temperature heater (7) is connected to the high-temperature heat storage system, and the cold sides of the cooler group are respectively connected to the high-temperature heat storage system and the first water heat storage system; the inlet and outlet of the heating working medium of the ORC low-temperature power generation system (14) are connected to the inlet and outlet of the second water heat storage system; the second water heat storage system provides heat source for the ORC low-temperature power generation system (14); the heat exchanger group between two adjacent stages of compressors includes an air cooler (3) and an air-water cooler (4), the cold side of the air cooler (3) is connected to the high-temperature heat storage system; the cold side of the air-water cooler (4) is connected to the first water heat storage system; the high-temperature heat storage system includes a hot medium tank (10) and a cold medium tank (11), the outlet of the hot medium tank (10) is connected to the hot side inlet of the air high-temperature heater (7), and the inlet of the cold medium tank (11) is connected to the hot side outlet of the air high-temperature heater (7); the first water heat storage system includes a hot water tank (12) and a cold water tank (13), the outlet of the hot water tank (12) is connected to the hot side inlet of the air-water heater (6), and the inlet of the cold water tank (13) is connected to the hot side outlet of the air-water heater (6); the inlet and outlet of the cold side of the air-water cooler (4) are respectively connected to the inlet of the hot water tank (12) and the outlet of the cold water tank (13); a low-temperature heat exchanger (41) is arranged at the outlet of the last-stage compressor, the low-temperature heat exchanger (41) is connected to the second water heat storage system and provides heat for the second water heat storage system, and the inlet and outlet of the second water heat storage system are respectively connected to the inlet and outlet of the heating working medium of the ORC low-temperature power generation system (14).

2. The ORC-coupled non-supplementary heat compressed air energy storage system according to claim 1, characterized in that, The heat storage medium in the high-temperature heat storage system is molten salt, heat-conducting oil or heat storage particles.

3. The ORC-coupled non-supplementary heat compressed air energy storage system according to claim 1, characterized in that, The air turbine unit is provided with at least two-stage air turbines (8), and an air-water heater (6) and an air high-temperature heater (7) are sequentially arranged at the inlet of each stage of air turbine (8) along the medium flow direction, the hot side of the air-water heater (6) is connected to the first water heat storage system, and the hot side of the air high-temperature heater (7) is connected to the high-temperature heat storage system.

4. The ORC-coupled non-supplementary heat compressed air energy storage system according to claim 1, characterized in that, The gas storage chamber (5) adopts a single chamber or multiple chambers in parallel.

5. The ORC-coupled non-supplementary heat compressed air energy storage system according to claim 1, characterized in that, A self-cleaning filter (1) is arranged at the inlet of the compressed air energy storage system.

6. The ORC-coupled non-supplementary heat compressed air energy storage system according to claim 1, characterized in that, A regulating valve is arranged at the outlet of the compressed air energy storage system.

7. An operation method of the ORC-coupled non-supplementary heat compressed air energy storage system according to any one of claims 1 to 6, characterized in that, Air is stored after being compressed by a compressed air energy storage system. The compressed air successively passes through an air-water heater (6) and an air high-temperature heater (7), exchanges heat with a first water heat storage system and a high-temperature heat storage respectively, and then enters an air turbine unit to do work, causing the air turbine unit to drive a generator (9) to generate electricity. Among them, the cooler group absorbs the heat generated during the compression of the compressed air, and at the same time stores the heat into the water heat storage system and the high-temperature heat storage system through water and heat storage media respectively. The first water heat storage system and the high-temperature heat storage system use the heat to heat the compressed air, and the second water heat storage system provides heat source for the ORC low-temperature power generation system (14).

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