A compressed air energy storage system coupled with a thermal power plant and a method of using the same

Abstract

The present invention discloses a compressed air energy storage system coupled with a thermal power plant and a method for using the same, comprising thermal equipment of the thermal power plant and a compressed air energy storage system: the steam outlet of the thermal equipment of the thermal power plant is connected to a compressor-driven steam turbine of the compressed air energy storage system; the compressed air energy storage system comprises a compressor, a compressor-driven steam turbine, a heat exchange system, an air storage chamber, an air expander and a generator, the air inlet of the compressor is connected to the air, the compressor-driven steam turbine is connected to the compressor, and the compressor-driven steam turbine is used to drive the compressor to compress air; the air outlet of the compressor is connected to the air inlet of the air storage chamber through the heat exchange system, and the air storage chamber is used to store compressed air; the air outlet of the air storage chamber is connected to the air inlet of the air expander through the heat exchange system, and the expander is connected to the generator; the present invention has the advantages of a large adjustment range and a fast response speed.

Description

Technical Field

[0001] This invention belongs to the field of energy storage technology, specifically relating to a compressed air energy storage system coupled to a thermal power plant and its usage method. Background Technology

[0002] In recent years, the installed capacity of new energy power generation, such as wind power and photovoltaic power, has grown rapidly. In some regions, the installed capacity of new energy far exceeds the local absorption capacity, resulting in serious problems of wind and solar curtailment. To improve the utilization rate of new energy power generation and reduce wind and solar curtailment, it is necessary to further improve the flexibility of the power grid in relation to thermal power units. Due to the requirements for combustion stability of coal-fired boilers, the adjustment range of thermal power units is generally between 50% and 100%. Currently, among commercially available large-scale energy storage technologies, only compressed air energy storage technology can achieve large-capacity, low-cost, and long-term energy storage. Summary of the Invention

[0003] To address the problems existing in the prior art, this invention provides a compressed air energy storage system coupled to a thermal power plant and its usage method, aiming to improve the flexibility and peak-shaving capacity of conventional thermal power units.

[0004] To achieve the above objectives, the present invention provides a compressed air energy storage system coupled to a thermal power plant, comprising thermal equipment of the thermal power plant and a compressed air energy storage system:

[0005] The compressed air energy storage system includes a compressor, a steam turbine, a heat exchange system, an air storage chamber, an air expander, and a generator. The compressor inlet is connected to air, and the steam turbine is connected to the compressor to drive the compressor to compress air. The compressor outlet is connected to the air inlet of the air storage chamber through the heat exchange system, and the air storage chamber is used to store compressed air. The air outlet of the air storage chamber is connected to the air inlet of the air expander through the heat exchange system, and the air expander is connected to the generator. The steam outlet of the thermal power plant's thermal equipment is connected to the steam turbine of the compressed air energy storage system.

[0006] Furthermore, the compressor is a multi-stage compressor, with a heat exchange and storage system installed after each stage of compression to recover the heat of compression. Adjacent compressors are connected through the heat exchange system. The cooling medium inlet of the heat exchange system is connected to the condensate outlet of the condensate tank, and the cooling medium outlet of the heat exchange system is connected to the inlet of the deaerator. The heat exchange system is used to recover the heat of compression generated during the compression process.

[0007] Furthermore, the cooling medium used in the heat exchange system is condensate from the thermal power plant. After heat exchange, the temperature of the condensate rises and it enters the deaerator of the thermal power plant.

[0008] Furthermore, the air expander is configured as a multi-stage air expander, with adjacent air expanders connected by a heat exchange system. The heating medium inlet of the heat exchange system is connected to the exhaust port of the high-pressure heater, and the heating medium outlet of the heat exchange system is connected to the inlet of the deaerator. The heat exchange system is used to heat the compressed air in the air storage chamber.

[0009] Furthermore, the adjacent air expanders are connected to the same generator; the heating medium of the heat exchange system is extracted from the high-pressure heater of the steam turbine of the thermal power plant, and the heated medium after heat exchange is introduced into the deaerator of the thermal power plant.

[0010] Furthermore, when the steam turbine is a condensing steam turbine, the exhaust steam outlet of the steam turbine is connected to the air inlet of the condenser; when the steam turbine is a back-pressure steam turbine, the exhaust steam outlet of the steam turbine is connected to the air supply network.

[0011] Furthermore, the steam output from the steam outlet of the thermal power plant's thermal equipment can be the main steam from the boiler, the reheat steam from the boiler, or the extraction steam from the high-pressure heater.

[0012] Furthermore, the gas storage chamber is an abandoned mine shaft, salt cave, underground cavern, or surface gas storage tank group.

[0013] Furthermore, compressed air energy storage systems coupled with thermal power plants can enable thermal power units to adjust within a range of 10% to 100%.

[0014] As another objective of this invention, a method for using a compressed air energy storage system coupled to a thermal power plant is also provided. During deep peak shaving, the thermal power plant's thermal equipment feeds steam into a steam turbine to perform work, and the exhaust steam is discharged into a condenser. Air enters the compressor from its inlet, and the steam turbine drives the compressor to compress the air, resulting in high-temperature compressed air. The compressor is connected to a storage chamber via a heat exchange system. The inlet of the cooling medium in the heat exchange system is connected to the outlet of a condensate tank, and the low-temperature condensate in the condensate tank is fed into the heat exchange system. In the heat exchange system, high-temperature compressed air and low-temperature condensate exchange heat. The compressed air after heat exchange is then fed into the gas storage chamber for storage, and the condensate after heat exchange is fed into the deaerator. During peak power generation, high-pressure air in the gas storage chamber is fed into the heat exchange system. The heating medium inlet of the heat exchange system is connected to the steam extraction port of the high-pressure heater, and high-temperature steam is fed into the heat exchange system. In the heat exchange system, compressed air and high-temperature steam exchange heat. The condensate after the steam releases heat is fed into the deaerator, and the heated compressed air is fed into the air expander. The air expander performs work to drive the generator to generate electricity.

[0015] Compared with the prior art, the present invention has at least the following beneficial effects. The compressed air energy storage system of the present invention has the following advantages: large installed capacity, low construction and operation costs, and long operating time. The present invention couples the compressed air energy storage system with the thermal power plant's thermal system, which can realize efficient and low-cost large-scale energy storage. By coupling the compressed air energy storage system, the flexibility of thermal power units is greatly improved. Applying the compressed air energy storage system to thermal power plants improves the flexibility of thermal power plants.

[0016] The heat exchange system in the compressed air energy storage system of this invention cools the compressed air while recovering the heat of compression. It uses the existing condensate system of the thermal power plant to cool the compressed air, and the recovered heat of compression enters the existing deaerator of the thermal power plant through the condensate, thus realizing the utilization of the heat of compression. Compared with a separate compressed air energy storage system, the compressed air energy storage system in this invention does not require the configuration of a dedicated heat storage device and system, reducing the complexity of the compressed air energy storage system.

[0017] This invention significantly improves the flexibility and peak-shaving capacity of conventional thermal power units by coupling a compressed air energy storage system with a thermal power plant. It can increase the adjustment range of thermal power units from 50%~100% to 10%~100%, and obtain higher peak-shaving revenue when participating in grid peak-shaving. This improves the flexibility of thermal power units, which refers to the range of load changes of thermal power units. The larger the range of changes, the better the flexibility, and the higher the peak-shaving revenue when participating in grid peak-shaving. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of a preferred compressed air energy storage system coupled with a thermal power plant.

[0019] In the attached diagram: 1 is the compressor; 2 is the steam turbine; 3 is the boiler reheater outlet; 4 is the condenser; 5 is the heat exchange system; 6 is the condensate tank; 7 is the deaerator; 8 is the high-pressure heater extraction port; 9 is the gas storage chamber; 10 is the air expander; and 11 is the generator. Detailed Implementation

[0020] The present invention will be further described below with reference to the accompanying drawings and specific embodiments. The description is intended to explain the invention and not to limit it.

[0021] Figure 1 This is a schematic diagram of a preferred embodiment of a compressed air energy storage system coupled to a thermal power plant. It includes thermal power plant equipment and a compressed air energy storage system. The compressed air energy storage system includes a compressor 1, a steam turbine 2, a heat exchange system 5, an air storage chamber 9, an air expander 10, and a generator 11. The thermal power plant equipment includes a boiler reheater outlet 3, a condenser 4, a condensate tank 6, a deaerator 7, and a high-pressure heater extraction port 8.

[0022] Compressor 1 can be configured as a multi-stage compressor according to actual needs; air expander 10 can be configured as a multi-stage air expander according to actual needs; in a preferred embodiment of the present invention, the multi-stage compressor has 2 to 8 stages, and a heat exchange and heat storage system is provided after each stage of compression to recover the heat of compression and improve efficiency. In another preferred embodiment of the present invention, a heat exchange system is provided between the stages of the multi-stage expander to heat the compressed air entering the compressor and improve power generation efficiency; the multi-stage expander has 2 to 4 stages.

[0023] In this example, the boiler reheater outlet 3 is connected to the turbine 2 of the compressed air energy storage system, the compressor 1 inlet is connected to air, the turbine 2 is connected to the compressor 1, and the turbine 2 drives the compressor 1 to compress air; the compressor 1 outlet is connected to the inlet of the air storage chamber 9 through the hot side of the heat exchange system 5, and the air storage chamber 9 is used to store compressed air; the air storage chamber 9 outlet is connected to the inlet of the air expander 10 through the cold side of the heat exchange system 5, and the air expander 10 is connected to the generator 11 to drive the generator 11 to generate electricity.

[0024] In this embodiment, a two-stage compressor is provided, which is connected to the hot side of a heat exchange system. The compressed air outlet of the last stage compressor 1 is connected to the hot side inlet of the heat exchange system 5. The hot side outlet of the heat exchange system 5 is connected to the gas storage chamber 5 through a pipeline. The cooling medium inlet of the heat exchange system 5 is connected to the condensate outlet of the condensate tank 6. The cooling medium outlet of the heat exchange system 5 is connected to the inlet of the deaerator 7. The cooling medium used in the heat exchange system 5 is the condensate from the thermal power plant. The cooled medium after heat exchange is introduced into the deaerator 7 of the thermal power plant. The liquid water in the deaerator enters the boiler in the thermal power plant and is heated into steam.

[0025] In this embodiment, a two-stage air expander is provided, and the two-stage air expander is connected to each other through the cold side of the heat exchange system 5. The compressed air outlet of the air storage chamber 9 is connected to the cold side inlet of the heat exchange system 5 through a pipe, and the cold side outlet of the heat exchange system 5 is connected to the compressed air inlet of the first-stage air expander.

[0026] Furthermore, the two-stage air expanders are connected to the same generator, and the heating medium of the heat exchange system 5 is extracted from the high-pressure heater of the steam turbine of the thermal power plant. The heating medium after heat exchange is introduced into the deaerator 7 of the thermal power plant.

[0027] In this example, turbine 2 is a condensing turbine, and the exhaust steam outlet of the turbine is connected to the air inlet of condenser 4.

[0028] The steam turbine 2 can also be a back-pressure steam turbine. When a back-pressure steam turbine is used, the exhaust steam outlet of the steam turbine is connected to the gas supply network.

[0029] In this example, the thermal power plant's thermal equipment uses the boiler's reheat steam to drive the turbine 2. The steam can also be the boiler's main steam or the extraction steam from the high-pressure heater.

[0030] Preferably, the gas storage chamber is an abandoned mine shaft, salt cave, underground cavern, or surface gas storage tank group.

[0031] A compressed air energy storage system coupled to a thermal power plant, during peak energy storage, introduces excess reheat steam from the boiler reheater outlet 3 into the turbine 2 of the compressed air energy storage system to perform work. The turbine 2 drives a two-stage compressor to compress air. The resulting high-temperature compressed air is fed into the hot side of a heat exchange system 5, while the condensate from the thermal power plant is fed into a condensate tank 6. The low-temperature condensate in the condensate tank 6 is driven by a condensate pump to enter the cold side of the heat exchange system 5. The high-temperature compressed air exchanges heat with the low-temperature condensate from the thermal power plant. The compressed air after heat exchange is then stored in a gas storage chamber, and the condensate after heat exchange enters the deaerator 7 of the thermal power plant. By using a portion of the reheat steam to drive the compressor 1 to compress air through the turbine 2, the amount of steam entering the power plant's generator turbine is reduced, thereby reducing the generator's power output and achieving peak energy storage.

[0032] During peak power generation, high-pressure air in the gas storage chamber 9 is introduced into the cold side of the heat exchange system 5. Some steam is drawn into the hot side of the heat exchange system 5 from the steam extraction port 8 of the high-pressure heater. The high-temperature steam exchanges heat with the compressed air. Each stage of the air expander 10 is equipped with a heat exchange system 5 at its inlet. The water after the steam releases heat and condenses enters the deaerator 7 of the thermal power plant. The heated compressed air enters the two-stage air expander to expand and do work, driving the generator 11 to generate electricity. The generator 11 is driven by the air expander 10 to generate electricity, increasing the power generation capacity of the thermal power plant.

[0033] It should be noted that the above description is only a part of the embodiments of the present invention, and all equivalent changes made to the system described in this invention are included within the protection scope of this invention. Those skilled in the art can make similar substitutions to the specific examples described, as long as they do not deviate from the structure of the invention or exceed the scope defined in these claims, all of which fall within the protection scope of this invention.

Claims

1. A compressed air energy storage system coupled with a thermal power plant, characterized in that: Including thermal power plant thermal equipment and compressed air energy storage system: The compressed air energy storage system comprises a compressor (1), a steam turbine (2), a heat exchange system (5), an air storage chamber (9), an air expander (10) and a generator (11); the air inlet of the compressor (1) is in communication with the air, the steam turbine (2) is connected to the compressor (1), and the steam turbine (2) is used to drive the compressor to compress air; the air outlet of the compressor (1) is connected to the air inlet of the air storage chamber through the heat exchange system (5), and the air storage chamber (9) is used to store compressed air; the air outlet of the air storage chamber (9) is connected to the air inlet of the air expander (10) through the heat exchange system (5), and the air expander (10) is connected to the generator (11); the steam outlet of the thermal equipment of the thermal power plant is connected to the steam turbine (2) of the compressed air energy storage system; The compressor (1) is a multi-stage compressor, and a heat exchange and heat storage system is provided after each stage of compression to recover compression heat. The adjacent compressors (1) are connected via a heat exchange system (5), and the cooling medium inlet of the heat exchange system (5) is connected to the condensate outlet of the condensate tank (6), and the cooling medium outlet of the heat exchange system (5) is connected to the inlet of the deaerator (7). The heat exchange system (5) is used to recover the compression heat generated during the compression process; The cooling medium used in the heat exchange system (5) is condensed water from a thermal power plant. After heat exchange, the temperature of the condensed water increases and enters the deaerator (7) of the thermal power plant. The air expander (10) is configured as a multi-stage air expander. Adjacently arranged air expanders (10) are connected via a heat exchange system (5). The heating medium inlet of the heat exchange system (5) is connected to the high-pressure heater steam extraction port (8). The heating medium outlet of the heat exchange system (5) is connected to the inlet of the deaerator (7). The heat exchange system (5) is used to heat the compressed air in the air storage chamber.

2. A compressed air energy storage system coupled with a thermal power plant according to claim 1, characterized in that: The adjacent air expanders (10) are connected to the same generator; the heating medium of the heat exchange system (5) is extracted steam from a high-pressure heater of a steam turbine in a thermal power plant, and the heating medium after heat exchange is introduced into a deaerator (7) in the thermal power plant.

3. A compressed air energy storage system coupled with a thermal power plant according to claim 1, characterized in that: When the steam turbine (2) is a condensing steam turbine, the exhaust steam outlet of the steam turbine (2) is connected to the air inlet of the condenser (4); when the steam turbine (2) is a back-pressure steam turbine, the exhaust steam outlet of the steam turbine (2) is connected to the air supply network.

4. A compressed air energy storage system coupled to a thermal power plant according to claim 1, characterized in that: The steam outputted from the steam outlet of the thermal power plant thermal equipment may be the main steam of the boiler, the reheated steam of the boiler or the extraction steam of the high-pressure heater.

5. A compressed air energy storage system coupled with a thermal power plant according to claim 1, characterized in that: The gas storage chamber (9) is an abandoned mine cave, salt cave, underground cave or ground gas storage tank group.

6. A compressed air energy storage system coupled with a thermal power plant according to claim 1, characterized in that: The compressed air energy storage system coupled with the thermal power plant can increase the regulation range of the thermal power unit to 10%~100%.

7. A method for using the compressed air energy storage system coupled with a thermal power plant according to any one of claims 1 to 6, characterized in that: When in deep peak regulation, the thermal power plant's thermal equipment passes steam into the steam turbine (2) to perform work, and the exhaust steam after the work is discharged into the condenser (4); air enters the compressor (1) from the air inlet of the compressor (1), and the steam turbine (2) drives the compressor (1) to compress the air. The high-temperature compressed air obtained is connected to the air storage chamber (9) through the heat exchange system (5). The cooling medium inlet of the heat exchange system (5) is connected to the outlet of the condensate tank (6), and the low-temperature condensate in the condensate tank (6) is passed into the heat exchange system (5). In the heat exchange system (5), the high-temperature compressed air and the low-temperature condensate enter the heat exchange system (5). Heat exchange is performed, and the compressed air after heat exchange is passed into the air storage chamber (9) for storage, and the condensed water after heat exchange is passed into the deaerator (7); when peak power generation is performed, the high-pressure air in the air storage chamber (9) is passed into the heat exchange system (5), the heating medium inlet of the heat exchange system (5) is connected to the high-pressure heater extraction port (8), and high-temperature steam is passed into the heat exchange system (5). In the heat exchange system, the compressed air and the high-temperature steam are heat exchanged, and the condensed water after the steam releases heat is passed into the deaerator (7), and the heated compressed air is passed into the air expander (10), and the air expander (10) performs work to drive the generator (11) to generate electricity.

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