A coal power unit peak shaving system coupled with energy storage

Abstract

This invention belongs to the field of energy storage technology, specifically a peak-shaving system for coal-fired power units coupled with energy storage. Current power generation systems combining liquid compressed air energy storage with coal-fired power units cannot meet the peak-shaving demands of the power grid during peak load periods. Therefore, this invention provides a peak-shaving system for coal-fired power units coupled with energy storage, comprising a steam unit with a boiler, a hydraulic air energy storage unit, an energy storage and power generation unit with a combustion chamber, and a flue gas unit with a chimney. The boiler's exhaust port is connected to the chimney via a first flue gas pipe. The combustion chamber is connected to a natural gas pipeline, which supplies natural gas into the combustion chamber. The combustion chamber's exhaust port is connected to the chimney via a combustion flue gas pipe. This system combines compressed air energy storage with natural gas, providing auxiliary power through the combined effect of compressed air energy release and natural gas combustion power generation. This allows the coal-fired power unit to operate safely and stably while meeting the peak-shaving demands of the power grid during peak load periods.

Description

Technical Field

[0001] This invention belongs to the field of energy storage technology, specifically a peak-shaving system for coal-fired power units with coupled energy storage. Background Technology

[0002] A power generation system combining compressed air energy storage (CISS) with coal-fired power units can help the power grid flexibly respond to different load conditions without shutting down the boiler. Its working principle involves the conversion of thermal energy, electrical energy, and pressure energy. During off-peak hours, excess steam generated by boiler combustion is used to compress, liquefy, cool, and store air. During peak load periods, the stored air is released to regenerate power, ensuring the safe and stable operation of the coal-fired power unit and achieving functions such as peak shaving, spinning reserve, and emergency response. However, existing coal-fired power generation systems with CISS rely solely on air storage for auxiliary power generation during peak load periods, which still cannot meet the electricity demands for peak shaving, spinning reserve, and emergency response. Summary of the Invention

[0003] The technical problem to be solved and the technical task proposed by this invention is that the current power generation system combining liquid compressed air energy storage with coal-fired power units cannot meet the peak-shaving and other needs of the power grid during peak load periods. This invention provides a coal-fired power unit peak-shaving system with coupled energy storage. The system can combine compressed air energy storage with natural gas, and provide sufficient auxiliary power supply through the combined action of compressed air energy release and natural gas combustion power generation, so as to ensure the safe and stable operation of the coal-fired power unit while meeting the needs of power grid peak-shaving and other work during peak load periods.

[0004] The technical solution adopted by this invention to solve the technical problem is: a peak-shaving system for coal-fired power units coupled with energy storage, comprising a steam unit with a boiler, a hydraulic air energy storage unit, an energy storage and power generation unit with a combustion chamber, and a flue gas unit with a chimney. The flue gas outlet of the boiler is connected to the chimney through a first flue gas pipe. The combustion chamber is characterized by being connected to a natural gas pipeline, which delivers natural gas into the combustion chamber. The flue gas outlet of the combustion chamber is connected to the chimney through a combustion flue gas pipe. This invention, based on existing coal-fired power generation coupled with hydraulic air energy storage, introduces natural gas to participate in combustion for auxiliary power generation, improving the turbine's workload during peak grid load periods. Through the combined action of natural gas and released liquid compressed air, it participates in power generation for grid peak shaving, compensating for the shortcomings of releasing liquid compressed air for combustion and power generation, thus achieving safe and stable operation of the coal-fired unit. During low grid load periods, the boiler maintains stable operation, and the excess steam generated is converted into compressed air for cooling and liquefaction storage, and released for energy storage during high grid load periods.

[0005] As a further improvement and supplement to the above technical solution, the present invention adopts the following technical measures: The steam unit includes a boiler, a high-pressure cylinder, and medium- and low-pressure cylinders. The high-pressure cylinder and the medium- and low-pressure cylinders are respectively connected to the high-pressure cylinder exhaust pipe and the four-section extraction pipe for outputting steam. The high-pressure cylinder exhaust pipe is divided into two paths, which are respectively connected to the boiler return pipe and the small turbine inlet pipe. The outlet end of the four-section extraction pipe is connected to the small turbine inlet pipe. The hydraulic air energy storage unit includes a small turbine, a first air compressor, a compressed air tank, a cold storage heat exchanger, a hydraulic air tank, and a cryogenic pump. The steam inlet of the small turbine is connected to the small turbine inlet pipe. The small turbine is connected to the first air compressor to drive its operation. The outlet of the first air compressor is connected to the compressed air tank through a pipeline. The compressed air tank is connected to... The heat medium inlet of the cold storage heat exchanger is connected via a cold storage heat exchanger input pipe. The heat medium outlet of the cold storage heat exchanger is connected to a hydraulic air tank via a hydraulic air inlet pipe. The hydraulic air tank is connected to the cold medium inlet of the cold storage heat exchanger via a pipeline, and a cryogenic pump is installed on the pipeline. The cold medium outlet of the cold storage heat exchanger is connected to the energy storage power generation unit via a hydraulic air outlet pipe. The energy storage power generation unit includes a vaporization tank and a combustion chamber, a second air compressor, an expander, and a generator. The air inlet of the vaporization tank is connected to the hydraulic air outlet pipe. The air outlet of the vaporization tank is connected to the combustion chamber via a pipeline. The output of the second air compressor is connected to the combustion chamber. The output of the combustion chamber is connected to the expander to perform work. The output of the expander is connected to the generator to drive it to generate electricity.

[0006] Furthermore, a gas-liquid separator pump is installed on the hydraulic air inlet pipe. The gas-liquid separator pump removes moisture from the liquid cooling compressed air output from the cold storage heat exchanger through pressure difference.

[0007] Furthermore, the compressed air tank is connected to an inlet pipe of a plant-use compressed air tank and an outlet pipe of the plant-use compressed air tank. The compressed air tank is also connected to the plant-use compressed air tank via a pipeline, specifically for storing excess compressed air for power plant use. Many devices used in power plants require compressed air as a power source, the starting of gas turbines and steam turbines also requires compressed air, and various valves and instruments also require compressed air for control.

[0008] Furthermore, the boiler's exhaust port is connected to the combustion chamber via a second flue gas duct. The flue gas from the boiler combustion can also be transported to the combustion chamber via the second flue gas duct, where it burns together with compressed air and natural gas released from the hydraulic air energy storage unit, fully utilizing the waste heat and combustible components of the flue gas to improve combustion efficiency.

[0009] A booster pump is installed on the pipeline between the vaporization tank and the combustion chamber. The booster pump pressurizes the vaporized compressed air delivered from the vaporization tank to increase the internal energy of the air, and then sends it into the combustion chamber to improve combustion efficiency.

[0010] Furthermore, an auxiliary steam pipe is connected to the boiler return steam pipe, with the other end of the auxiliary steam pipe connected to the hot medium inlet of the air preheater. The hot medium outlet of the air preheater is connected back to the boiler via the auxiliary steam return pipe. The cold medium inlet and outlet of the air preheater are sequentially connected to the pipeline between the gasification tank and the booster pump. The auxiliary steam pipe utilizes the steam returned from the boiler return steam pipe and sends it to the air preheater to heat the air sent from the gasification tank. The heated air is then pressurized by the booster pump and input into the combustion chamber for combustion.

[0011] Furthermore, the combustion flue gas pipe is connected to a waste heat boiler on the section connecting to the chimney. The waste heat boiler is connected to a natural gas pipeline, and its inlet and outlet are connected to a feed water pipe and a hot water pipe, respectively. The hot water pipe is then connected back to the boiler. The waste heat boiler, being a natural gas boiler, starts up quickly and reacts rapidly, enabling it to heat water quickly. It combines flue gas with natural gas for combustion to heat water. The heated water is then sent back to the coal-fired power unit's boiler to assist in steam generation, reducing the boiler's workload during peak electricity demand periods and ensuring its safe and stable operation.

[0012] Furthermore, the small steam turbine inlet pipe is connected to the boiler exhaust pipe, and the boiler exhaust pipe is connected to the boiler. The boiler is a commonly used auxiliary facility in coal-fired power units. Steam is sent from the boiler exhaust pipe to the small steam turbine inlet pipe, which not only meets the boiler's need to reduce load during periods of low grid load, but also allows the steam output from the boiler to be used to drive the small steam turbine and rotate it, thereby driving the first air compressor to provide compressed air.

[0013] This invention provides a coal-fired power unit peak-shaving system with coupled energy storage. The system can combine compressed air energy storage with natural gas. While the compressed air energy storage is released to participate in power generation, the participation of natural gas is also increased. The two are combined to provide auxiliary power supply. Regardless of the grid load, the boiler can maintain continuous and stable operation, enabling the coal-fired power unit to operate safely and stably and meet the grid peak-shaving needs during peak grid load periods. Attached Figure Description

[0014] Figure 1 : A schematic diagram of the system structure described in this invention.

[0015] In the diagram: 1. Boiler, 2. High-pressure cylinder, 3. Medium and low-pressure cylinder, 4. High-pressure cylinder exhaust pipe, 5. Four-stage extraction pipe, 6. Boiler return pipe, 7. Auxiliary steam pipe, 8. Small turbine inlet pipe, 9. Temporary boiler exhaust pipe, 10. Small turbine, 11. First air compressor, 12. Auxiliary steam return pipe, 13. Compressed air tank, 14. Cold storage heat exchanger input pipe, 15. Cold storage heat exchanger, 16. Gas-liquid separator pump, 17. Hydraulic air inlet pipe, 18. Hydraulic air tank, 19. Cryogenic pump 20. Hydraulic air outlet pipe; 21. Gasification tank; 22. Plant compressed air tank inlet pipe; 23. Plant compressed air tank; 24. Air preheater; 25. Booster pump; 26. Second air compressor; 27. Combustion chamber; 28. Expander; 29. ​​Generator; 30. Chimney; 30-1. First flue gas duct; 30-2. Second flue gas duct; 31. Water supply pipe; 32. Natural gas transmission pipe; 33. Combustion flue gas pipe; 34. Hot water pipe; 35. Waste heat boiler. Detailed Implementation

[0016] The present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0017] like Figure 1 As shown, a peak-shaving system for a coal-fired power unit with coupled energy storage includes a steam unit with a boiler 1, a hydraulic air energy storage unit, an energy storage and power generation unit with a combustion chamber 27, and a flue gas unit with a chimney 30. The exhaust port of the boiler 1 is connected to the chimney 30 through a first flue gas pipe 30-1. The exhaust port of the boiler 1 is also connected to the combustion chamber 27 through a second flue gas pipe 30-2. The combustion chamber 27 is connected to a natural gas transmission pipe 32, which can deliver natural gas into the combustion chamber 27. The exhaust port of the combustion chamber 27 is connected to the chimney 30 through a combustion flue gas pipe 33. The combustion flue gas pipe 33 is also connected to a waste heat boiler 35 on the section passing through the chimney 30. At the same time, the waste heat boiler 35 is connected to the natural gas transmission pipe 32 to introduce natural gas for heating hot water. The inlet and outlet of the waste heat boiler 35 are connected to a water supply pipe 31 and a hot water pipe 34, respectively. The hot water pipe 34 is connected back to the boiler 1.

[0018] The steam unit in this embodiment includes a boiler 1, a high-pressure cylinder 2, and a medium-low-pressure cylinder 3. The high-pressure cylinder 2 and the medium-low-pressure cylinder 3 are respectively connected to the high-pressure cylinder exhaust pipe 4 and the four-section extraction pipe 5 for outputting steam. The high-pressure cylinder exhaust pipe 4 is divided into two paths, which are respectively connected to the boiler return steam pipe 6 and the small steam turbine inlet steam pipe 8. The outlet end of the four-section extraction pipe 5 is connected to the small steam turbine inlet steam pipe 8. The small steam turbine inlet steam pipe 8 is also connected to the nearby boiler exhaust pipe 9, which is connected to the nearby boiler. The hydraulic air energy storage unit includes a small steam turbine 10, a first air compressor 11, a compressed air tank 13, a cold storage heat exchanger 15, and a hydraulic air tank. 18 and cryogenic pump 19, the steam inlet of small steam turbine 10 is connected to small steam turbine inlet pipe 8, small steam turbine 10 is connected to first air compressor 11 to drive its operation, the outlet of first air compressor 11 is connected to compressed air tank 13 through pipeline, compressed air tank 13 is connected to a plant-use compressed air tank inlet pipe 22 and output connected to a plant-use compressed air tank 23, compressed air tank 13 is connected to the heat medium inlet of cold storage heat exchanger 15 through cold storage heat exchange input pipe 14, cold storage heat exchanger 15 heat medium outlet is output connected to hydraulic air tank 18 through hydraulic air inlet pipe 17, hydraulic... A gas-liquid separator pump 16 is installed on the compressed air inlet pipe 17. The hydraulic air tank 18 is connected to the cold medium inlet of the cold storage heat exchanger 15 through a pipeline, and the cryogenic pump 19 is installed on the pipeline. The cold medium outlet of the cold storage heat exchanger 15 is connected to the energy storage power generation unit through the hydraulic air outlet pipe 20. The energy storage power generation unit includes a vaporization tank 21, a combustion chamber 27, a second air compressor 26, an expander 28, and a generator 29. The air inlet of the vaporization tank 21 is connected to the hydraulic air outlet pipe 20, and the air outlet of the vaporization tank 21 is connected to the combustion chamber 27 through a pipeline. An air preheater 24 and a booster pump 25 are sequentially installed along the gas transmission direction on the pipeline. An auxiliary steam pipe 7 is connected to the boiler return steam pipe 6. The other end of the auxiliary steam pipe 7 is connected to the hot medium inlet of the air preheater 24. The hot medium outlet of the air preheater 24 is connected back to the boiler 1 through the auxiliary steam return steam pipe 12. The cold medium inlet and outlet of the air preheater 24 are sequentially connected to the pipeline between the gasification tank 21 and the booster pump 25. The output of the second air compressor 26 is connected to the combustion chamber 27. The output of the combustion chamber 27 is connected to the expander 28 to perform work. The output of the expander 28 is connected to the generator 29 to drive it to generate electricity.

[0019] This invention provides a coal-fired power unit peak-shaving system with coupled energy storage, which combines compressed air energy storage with natural gas. While the compressed air energy storage is released to participate in power generation, the participation of natural gas is also increased. The combined effect of the two provides auxiliary power supply, allowing the boiler of the coal-fired power unit to operate smoothly, maintaining the safe and stable operation of the coal-fired power unit, and meeting the needs of grid peak shaving during peak load periods.

[0020] The system described in this invention operates as follows: When the grid load suddenly drops to a low point, the unit operates at low load. The boiler steam parameters remain unchanged. At this time, the fourth-stage extraction steam from the medium-low pressure cylinder 3 enters the small turbine inlet pipe 8 along the fourth-stage extraction pipe 5, driving the small turbine 10 to rotate and the first air compressor 11 to compress air. As the grid load continues to decrease, the steam source is switched, shutting off the steam supply from the fourth-stage extraction pipe 5 and switching the high-pressure cylinder 2 inlet steam. The steam delivered by the high-pressure cylinder exhaust pipe 4 enters the small turbine inlet pipe 8, driving the small turbine to rotate and the first air compressor 11 to compress air. When the temporary boiler also needs to reduce its load, the steam from the temporary boiler enters the small turbine inlet pipe 8 through the temporary boiler exhaust pipe 9, driving the small turbine 10 to rotate and the first air compressor 11 to compress air. Compressed air; the aforementioned compressed air enters the compressed air tank 13 through a pipeline. The compressed air tank 13 serves to stabilize and store the compressed air. The compressed air in the compressed air tank 13 can be output in two paths. One path is sent along the plant-use compressed air tank inlet pipe 22 to the plant-use compressed air tank 23 to provide the compressed air required for the power plant's operation. The other path of compressed air enters the cold storage heat exchanger 15 for heat exchange and cooling. The cooled compressed air enters the vapor-liquid separator pump 16 to separate the moisture from the air and discharge it. The cooled liquid compressed air enters the hydraulic air tank 18 for storage. When the liquid compressed air storage reaches a set value, the storage of liquid compressed air stops. At this time, the excess compressed air will be transported to the plant-use compressed air tank 23 for storage along the other path. Furthermore, when the power grid is operating at low load, the flue gas generated by the boiler 1 combustion is mainly sent to the chimney 30 through the first flue gas pipe 30-1 for discharge.

[0021] When the power grid is under high load, the coal-fired power units also gradually increase their load and enter a high-load operation state. The steam from the high-pressure cylinder 2 enters the high-pressure cylinder exhaust pipe 4, and the steam is discharged into the boiler return steam pipe 6 and sent back to the boiler 1. At this time, the small steam turbine inlet pipe 8 and the auxiliary steam pipe 7 are closed, the small steam turbine 10 stops working, and the hydraulic air energy storage unit stops operating. As the power grid load increases, the traditional coal-fired power units cannot meet the power demand even when operating at high load, and auxiliary power supply is required. First, the second air compressor 26 is started, and compressed air enters the combustion chamber 27 for combustion, driving the expander 28 to do work and drive the generator 29 to generate electricity. As the power load continues to increase, the hydraulic air energy storage unit is started. First, the auxiliary steam pipe 7 is opened to preheat the pipeline. Then, the hydraulic air tank 18 sends the stored liquid compressed air to the cold storage heat exchanger 15 through the cryogenic pump 19 for heat exchange. The medium filled in the cold storage heat exchanger 15 releases the heat obtained from cooling the compressed air, heating the liquid compressed air output from the hydraulic air tank 18. Here, the cold storage heat exchanger is existing technology, which uses internal packing to accumulate or release heat energy. When the power grid load is low, the heat energy obtained from cooling the compressed air is accumulated, and when the power grid load is high, the heat energy is released. The heated compressed air is sent to the vaporization tank 21 through the hydraulic air outlet pipe 20 for vaporization. The vaporized compressed air enters the air preheater 24. The heat exchange continues and the temperature rises. The heated compressed air is pressurized by the booster pump 25 and enters the combustion chamber 27 for combustion. The gas after combustion enters the expander 28 to expand and do work, driving the generator 29 to generate electricity. When the grid load continues to rise, the water supply pipe 31 supplies water to the waste heat boiler 35 and opens the natural gas pipeline 32 to send natural gas into the waste heat boiler 35 for combustion to heat the water and send it into the combustion chamber 27 for combustion. The water heated by the waste heat boiler is sent back to the boiler through the hot water pipe 34 to reduce the boiler's workload. The first flue gas pipeline 30-1, which was originally open when the grid was under low load, is closed. The second flue gas pipeline 30-2, which was closed when the grid was under low load, is opened. The flue gas generated by the boiler 1 is sent into the combustion chamber 27 for auxiliary combustion. The flue gas after combustion is sent into the waste heat boiler 35 through the combustion flue gas pipe 33 to participate in the combustion of natural gas. The flue gas generated by the waste heat boiler 35 is finally discharged into the chimney 30.

[0022] When the power grid load decreases from high, the waste heat boiler 35 is shut down first, the natural gas supply to the waste heat boiler is suspended, the water supply to the waste heat boiler is cut off, and the water supply from the waste heat boiler to boiler 1 is suspended. The previously opened second flue gas pipe 30-2 is closed again, and the first flue gas pipe 30-1 is reopened. The flue gas generated by boiler 1 is discharged directly into chimney 30 through the first flue gas pipe. As the power grid load continues to decrease, the hydraulic air energy storage unit is shut down, and the cryogenic pump 19 and auxiliary steam pipe 7 are shut down one after another. When there is no more compressed air output in the gasification tank 21, the booster pump 25 is shut down. When the power grid load continues to decrease, the second air compressor 26 is shut down, the natural gas transmission pipe 32 is stopped from supplying gas to the combustion chamber 27, and the generator 29 is shut down. At this time, the boiler power generation is consistent with the power grid load, which can meet the needs of the power grid under low load.

Claims

1. A coal power plant peak shaving system coupled with energy storage, comprising a steam unit with a boiler (1), a hydraulic air energy storage unit, an energy storage power generation unit with a combustion chamber (27) and a flue gas unit with a chimney (30), the flue gas outlet of the boiler (1) is connected to the chimney (30) through a first flue gas pipeline (30-1), characterized in that The combustion chamber (27) is connected to a natural gas pipeline (32), which can deliver natural gas into the combustion chamber (27). The exhaust port of the combustion chamber (27) is connected to the chimney (30) through a combustion flue pipe (33). The hydraulic air energy storage unit includes a small steam turbine (10), a first air compressor (11), a compressed air tank (13), a cold storage heat exchanger (15), a hydraulic air tank (18), and a cryogenic pump (19). The steam inlet of the small steam turbine (10) is connected to the steam inlet pipe (8). The small steam turbine (10) is connected to the first air compressor (11) to drive its operation. The outlet of the first air compressor (11) is connected to the compressed air tank (13) through a pipeline. The compressed air tank (13) is connected to the first air compressor (11) through a pipeline. The cold storage heat exchange input pipe (14) is connected to the heat medium inlet of the cold storage heat exchanger (15). The heat medium outlet of the cold storage heat exchanger (15) is connected to the hydraulic air tank (18) through the hydraulic air inlet pipe (17). The hydraulic air tank (18) is connected to the cold medium inlet of the cold storage heat exchanger (15) through the pipeline. The pipeline is equipped with the aforementioned low temperature pump (19). The cold medium outlet of the cold storage heat exchanger (15) is connected to the energy storage power generation unit through the hydraulic air outlet pipe (20). The energy storage and power generation unit includes a vaporization tank (21), a combustion chamber (27), a second air compressor (26), an expander (28), and a generator (29). The air inlet of the vaporization tank (21) is connected to the hydraulic air outlet pipe (20), and the air outlet of the vaporization tank (21) is connected to the combustion chamber (27) through a pipeline. The output of the second air compressor (26) is connected to the combustion chamber (27), and the output of the combustion chamber (27) is connected to the expander (28) to make it do work. The output of the expander (28) is connected to the generator (29) to drive it to generate electricity.

2. The peak-shaving system for coal-fired power units with coupled energy storage according to claim 1, characterized in that: The steam unit includes a boiler (1), a high-pressure cylinder (2), and a medium-low pressure cylinder (3). The high-pressure cylinder (2) and the medium-low pressure cylinder (3) are respectively connected to the high-pressure cylinder exhaust pipe (4) and the four-section extraction pipe (5) for outputting steam. The high-pressure cylinder exhaust pipe (4) is divided into two paths and respectively connected to the boiler return steam pipe (6) and the small steam turbine inlet pipe (8). The outlet end of the four-section extraction pipe (5) is connected to the small steam turbine inlet pipe (8).

3. The peak-shaving system for coal-fired power units with coupled energy storage as described in claim 2, characterized in that: The hydraulic air intake pipe (17) is equipped with a gas-liquid separation pump (16).

4. The peak-shaving system for coal-fired power units with coupled energy storage as described in claim 2, characterized in that: The compressed air tank (13) is connected to an air inlet pipe (22) for a factory compressed air tank and has an output connection to a factory compressed air tank (23).

5. The peak-shaving system for coal-fired power units with coupled energy storage as described in claim 2, characterized in that: The flue gas outlet of the boiler (1) is connected to the combustion chamber (27) via the second flue gas pipe (30-2).

6. The peak-shaving system for coal-fired power units with coupled energy storage as described in claim 2, characterized in that: A booster pump (25) is provided on the pipeline between the gasification tank (21) and the combustion chamber (27).

7. The peak-shaving system for coal-fired power units with coupled energy storage as described in claim 6, characterized in that: The boiler return steam pipe (6) is connected to an auxiliary steam pipe (7). The other end of the auxiliary steam pipe (7) is connected to the hot medium inlet of the air preheater (24). The hot medium outlet of the air preheater (24) is connected back to the boiler (1) through the auxiliary steam return pipe (12). The cold medium inlet and outlet of the air preheater (24) are sequentially connected to the pipeline between the gasification tank (21) and the booster pump (25).

8. The peak-shaving system for coal-fired power units with coupled energy storage as described in claim 2, characterized in that... The combustion flue gas pipe (33) is connected to the waste heat boiler (35) on the pipe section connecting the chimney (30). The waste heat boiler (35) is connected to the natural gas transmission pipe (32). The inlet and outlet of the waste heat boiler (35) are connected to the water supply pipe (31) and the hot water pipe (34) respectively. The hot water pipe (34) is connected back to the boiler (1).

9. In the peak-shaving system of the coal-fired power unit with coupled energy storage according to claim 2, the steam inlet pipe (8) of the small steam turbine is connected to the grate pipe (9) of the nearby furnace, and the grate pipe (9) of the nearby furnace is connected to the nearby furnace.

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