A thermal power unit and compressed air energy storage coupled deep peak shaving system

Abstract

This invention relates to a deep peak-shaving system coupling a thermal power unit with compressed air energy storage. The output end of the steam turbine cylinder group is connected to a first generator. The power output end of the first generator is connected to the power grid and the power supply end of the motor. The output end of the motor is connected to a compressor via a first coupling and to a refrigeration and storage device via a second coupling. The refrigeration and storage device is connected to the heat absorption pipe of a circulating heat exchanger. The output end of the compressor is connected to the gas storage chamber via the heat release pipe of the compression process heat exchanger. The condensate drain outlet of the condenser is connected to the heat absorption pipe of the compression process heat exchanger. The output end of the gas storage chamber is connected to an expander via the heat absorption pipe of the expansion process heat exchanger. The output end of the expander is connected to a circulating water pump via a third coupling. One end of the circulating water pump is connected to a cooling tower, and the other end is connected to the condenser via the heat release pipe of the circulating heat exchanger. Compared with the prior art, this invention has advantages such as broadening the peak-shaving range.

Description

Technical Field

[0001] This invention relates to peak shaving systems, and more particularly to a deep peak shaving system that couples thermal power units with compressed air energy storage. Background Technology

[0002] In recent years, the development of new energy power generation has been rapid, and the increasing proportion of new energy power generation has led to a more significant peak-shaving role for thermal power units, which in turn places higher demands on the depth of peak-shaving. However, during peak-shaving, the unit load is relatively low. When the boiler operates at low load, problems arise such as unstable combustion of the burner, low flue gas temperature preventing the normal operation of denitrification equipment, and a decrease in superheated steam and reheat steam parameters, affecting the safety of steam-water side operation and impacting the flexibility of the thermal power unit. Furthermore, the unit's economic efficiency gradually decreases with decreasing load, and the energy consumption of the unit during deep peak-shaving is significantly higher than that under conventional load. Therefore, both safety and economic factors limit the wide-load, deep peak-shaving capabilities of thermal power units.

[0003] Energy storage technology emerged during the development of new energy sources such as solar and wind power, and has developed rapidly in recent years. It stores electrical energy using specific methods or media and releases it when electricity is needed. It possesses unique time-of-use storage and release characteristics, enabling it to "shave peaks and fill valleys" and balance power loads. How to integrate energy storage technology into the power system to better promote the utilization of renewable energy, improve grid transmission capacity and stability, and assist in peak shaving for coal-fired power plants has become a key focus of current energy research. In particular, the auxiliary peak shaving role of energy storage technology is crucial during the transition period of energy transformation. Currently, there are many types of energy storage technologies, each with its own advantages and disadvantages. Compressed air energy storage technology stands out among these technologies, boasting the largest capacity and most mature technology. Compared to other forms of energy storage, it offers advantages such as high operating efficiency, long service life, large storage capacity, and low investment, making it one of the "most promising energy storage methods." Summary of the Invention

[0004] The purpose of this invention is to provide a deep peak shaving system that couples thermal power units with compressed air energy storage.

[0005] The objective of this invention can be achieved through the following technical solutions:

[0006] A deep peak-shaving system coupled with compressed air energy storage for thermal power units includes:

[0007] Steam turbine steam cylinder group, first generator, compressor, electric motor, first coupling, second coupling, gas storage chamber, cooling tower, condenser, compression process heat exchanger, expander, circulating heat exchanger, third coupling and circulating water pump;

[0008] The output end of the steam turbine cylinder group is connected to the first generator. The power output end of the first generator is connected to the power grid and the power supply end of the motor. The output end of the motor is connected to the compressor through the first coupling and to the refrigeration and storage equipment through the second coupling. The refrigeration and storage equipment is connected to the heat absorption pipe of the circulating heat exchanger. The output end of the compressor is connected to the gas storage chamber through the heat release pipe of the compression process heat exchanger. The condensate drain outlet of the condenser is connected to the heat absorption pipe of the compression process heat exchanger. The output end of the gas storage chamber is connected to the expander through the heat absorption pipe of the expansion process heat exchanger. The output end of the expander is connected to the circulating water pump through the third coupling. One end of the circulating water pump is connected to the cooling tower, and the other end is connected to the condenser through the heat release pipe of the circulating heat exchanger.

[0009] The steam turbine cylinder assembly includes a high-pressure cylinder, an intermediate-pressure cylinder, and a low-pressure cylinder connected in sequence via a rotating shaft.

[0010] The high-pressure cylinder, medium-pressure cylinder, and low-pressure cylinder are connected to the first generator via a rotating shaft. Steam passes through the high-pressure cylinder, medium-pressure cylinder, and low-pressure cylinder in sequence to perform work and drive the generator to generate electricity.

[0011] The system also includes a condensate pump, and the output end of the heat absorption line of the compression process heat exchanger is connected to the boiler via the condensate pump.

[0012] The condensate pump is a variable frequency pump.

[0013] The system also includes a second generator, and the output of the expander is connected to the second generator via a fourth coupling.

[0014] The heat release pipes of the expansion process heat exchanger are connected to the steam cylinder group of the steam turbine.

[0015] The circulating water pump is a variable frequency pump.

[0016] The compressor has multiple stages.

[0017] The expander has multiple stages.

[0018] Compared with existing technologies, this invention has the following beneficial effects: When deep peak shaving is required, the compression process of compressed air energy storage participates in unit operation, and part of the turbine output is used to drive the compressor to do work, converting excess electricity beyond peak shaving into the pressure energy of air for storage, or into cooling capacity, to reduce unit back pressure and achieve cold-end optimization. When the unit needs additional output, the expansion process of compressed air energy storage participates in unit operation, and the energy stored in the compression process is fed into the grid as part of the output, or can be used to drive the circulating water pump, reducing plant power consumption. The coupled system expands the unit's operating load range from Gmin~Gmax to (Gmin-G1)~(Gmax+G2), increasing the peak shaving range to G1+G2, realizing wide-load deep peak shaving of the unit, optimizing the cold end, reducing plant power consumption, and improving the unit's economic efficiency. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the structure of the present invention;

[0020] The components include: 1. Boiler; 2. High-pressure cylinder; 3. Medium-pressure cylinder; 4. Low-pressure cylinder; 5. First generator; 6. Power transmission line; 7. Power grid; 8. Cooling tower; 9. Circulating water pump; 10. Heat exchanger; 11. Condenser; 12. Compressor; 13. First coupling; 14. Third motor; 15. Second coupling; 16. Refrigeration and storage equipment; 17. Expansion process heat exchanger; 18. Third coupling; 19. Expander; 20. Fourth coupling; 21. Second generator; 22. First regulating valve; 23. Second regulating valve; 24. Gas storage chamber; 25. Third regulating valve; 26. Compression process heat exchanger; 27. Condensate pump; 28. Fourth regulating valve; 29. ​​Pressure sensor. Detailed Implementation

[0021] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. These embodiments are based on the technical solution of the present invention and provide detailed implementation methods and specific operating procedures. However, the scope of protection of the present invention is not limited to the following embodiments.

[0022] A deep peak-shaving system coupling thermal power units with compressed air energy storage, such as... Figure 1 As shown, it includes:

[0023] Steam turbine steam cylinder group, first generator 5, compressor 12, electric motor, first coupling 13, second coupling 15, gas storage chamber 24, cooling tower 8, condenser 11, compression process heat exchanger 26, expander 19, circulating heat exchanger 10, third coupling 18 and circulating water pump 9;

[0024] The output end of the steam turbine cylinder group is connected to the first generator 5. The power output end of the first generator 5 is connected to the power grid 7 and the power supply end of the motor respectively. The output end of the motor is connected to the compressor 12 through the first coupling 13 and to the refrigeration and storage equipment 16 through the second coupling 15. The refrigeration and storage equipment 16 is connected to the heat absorption pipe of the circulating heat exchanger 10. The output end of the compressor 12 is connected to the gas storage chamber 24 through the heat release pipe of the compression process heat exchanger 26. The condensate drain outlet of the condenser 11 is connected to the heat absorption pipe of the compression process heat exchanger 26. The output end of the gas storage chamber 24 is connected to the expander 19 through the heat absorption pipe of the expansion process heat exchanger 17. The output end of the expander 19 is connected to the circulating water pump 9 through the third coupling 18. One end of the circulating water pump 9 is connected to the cooling tower 8, and the other end is connected to the condenser 11 through the heat release pipe of the circulating heat exchanger 10.

[0025] This application couples compressed air energy storage, a steam turbine cylinder group, and a cooling tower 8. When deep peak shaving is required, the compression process of the compressed air energy storage participates in the unit operation, and part of the turbine output is used to drive the compressor 12 to do work. Excess electricity beyond peak shaving is converted into the pressure energy of the air for storage, or into cooling capacity, to reduce the unit's back pressure and achieve cold-end optimization. When the unit needs additional output, the expansion process of the compressed air energy storage participates in the unit operation. The energy stored during compression is fed into the power grid 7 as part of the output, or can be used to drive the circulating water pump 9, reducing the plant's power consumption rate. The coupled system allows for a wider operating load range for the unit.

[0026] In this embodiment, the steam turbine cylinder group includes a high-pressure cylinder 2, an intermediate-pressure cylinder 3, and a low-pressure cylinder 4 connected in sequence. The high-pressure cylinder 2, the intermediate-pressure cylinder 3, and the low-pressure cylinder 4 are connected to the first generator 5 through a rotating shaft. Steam passes through the high-pressure cylinder 2, the intermediate-pressure cylinder 3, and the low-pressure cylinder 4 in sequence to do work, thereby driving the first generator 5 to generate electricity.

[0027] In addition, the system includes a condensate pump 27, the output of which is connected to the boiler via the heat absorption line of the compression process heat exchanger 26. In some embodiments, the condensate pump 27 may be a variable frequency pump.

[0028] The system also includes a second generator 21, and the output of the expander 19 is connected to the second generator 21 via a fourth coupling 20.

[0029] In addition, the heat release pipeline of the expansion process heat exchanger 17 is connected to the steam cylinder group of the steam turbine, and in some embodiments, the circulating water pump 9 is a variable frequency pump.

[0030] In some embodiments, the compressor 12 has multiple stages, and similarly, the expander 19 has multiple stages.

[0031] The following specific examples illustrate this application.

[0032] Let the maximum output of the unit be G. max The minimum output force to ensure safety is G. min The compressor 12 has a rated power of G1, and the expander 19 has an output power of G2.

[0033] (1) When the power plant receives the deep peak shaving command from the generating unit, it connects the first coupling 13, opens the third regulating valve 25, and connects the power supply from the first generator 5 to the motor 14. Part of the electrical energy output from the first generator 5 drives the motor, thereby driving the compressor 12 (which can be a single-stage or multi-stage compressor 12). The compression process of the compressed air energy storage participates in the unit operation, and the peak shaving load of the unit can be reduced to G under the condition of ensuring safety. min -G1;

[0034] (2) The condensate discharged from the condenser 11 is cooled by the heat exchanger 10 to cool the air whose temperature rises after compression. If the compressor 12 is a multi-stage compressor, the number of heat exchangers 26 in the compression process is the same as the number of stages of the compressor 12. Each heat exchanger 26 is arranged after each stage of the compressor 12.

[0035] (3) The compressed and cooled air is stored in the air storage chamber 24;

[0036] (4) The condensate heated by compressed air will increase the final feedwater temperature;

[0037] (5) When the pressure sensor 29 displays that the gas pressure in the gas storage chamber 24 has reached the limit pressure P of the gas storage device. max After the gas storage process ends, close the third regulating valve 25;

[0038] (6) If the gas storage process ends, the unit is still in a deep peak shaving state. Disconnect the first coupling 13 and connect the second coupling 15 so that part of the electrical energy output by the first generator 5 drives the refrigeration equipment to work. The cooling medium is cooled and stored in the refrigeration equipment 16.

[0039] (7) When the unit is operating at high load or during the day or when the ambient temperature is high, the cooling medium stored in the refrigeration and storage equipment 16 reduces the temperature of the circulating water through the heat exchanger 10, thereby reducing the unit vacuum and improving the unit's economy.

[0040] (8) Part of the electricity generated by the first generator 5 is used for compressed air or refrigeration, which reduces the power supply of the unit to the power grid 7. However, the actual operating load of the unit is high and the energy consumption is low.

[0041] (9) When certain auxiliary equipment of the unit fails, causing the unit to be unable to operate at high or full load, or when the unit's heat supply is too large to operate at high or full load, if the power grid 7 requires the unit to output power at high or full load, the expansion process of compressed air energy storage can be involved in the unit's operation, and the unit's maximum power supply load can be increased to G. max +G2;

[0042] (10) Open the first regulating valve 22, the second regulating valve 23 and the fourth regulating valve 28 so that the air stored in the air storage chamber 24 is heated by the exhaust steam of the intermediate pressure cylinder 3 before entering the expander 19, thereby improving the work capacity. After the exhaust steam is cooled, it is discharged into the condenser 11.

[0043] (11) Connect the fourth coupling 20 so that the transmission line 6 from the second generator 21 to the power grid 7 is open, the expander 19 of the compressed air energy storage does work, and the system output is the sum of the output of the first generator 5 and the second generator 21.

[0044] (12) The expander 19 can be a multi-stage expander 19, with an expansion process heat exchanger 17 provided before each stage expander 19. The air in the storage chamber 24 is heated by the expansion process heat exchanger 17 before entering each stage expander 19.

[0045] (13) If the output of the unit itself can meet the load requirements of the power grid 7, and there is no need for the second generator 21 to generate electricity and connect to the grid, the first regulating valve 22, the second regulating valve 23, and the fourth regulating valve 28 can be opened, and the third coupling 18 can be connected. The compressed air in the air storage chamber 24 drives the expander 19 to do work, which drives the circulating water pump 9 to work, saving plant power.

[0046] (14) If the pressure sensor 29 shows that the air pressure in the air storage chamber 24 has dropped to the inlet pressure P of the expander 19, T-in When the expansion process ends, the first regulating valve 22, the second regulating valve 23, and the fourth regulating valve 28 are closed.

[0047] (15) The regulating valve can be closed and the coupling can be disconnected to separate the thermal power unit from the compressed air energy storage.

[0048] If the aforementioned functions are implemented as software functional units and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of this invention, or the part that contributes to the prior art, or a part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of this invention. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

Claims

1. A deep peak-shaving system coupling a thermal power unit with compressed air energy storage, characterized in that, include: Steam turbine cylinder assembly, first generator, compressor, third motor, first coupling, second coupling, gas storage chamber, cooling tower, condenser, compression process heat exchanger, expander, circulating heat exchanger, third coupling, and circulating water pump. The output end of the steam turbine cylinder group is connected to the first generator. The power output end of the first generator is connected to the power grid and the power supply end of the third motor. The output end of the third motor is connected to the compressor through the first coupling and to the refrigeration and storage equipment through the second coupling. The refrigeration and storage equipment is connected to the heat absorption pipe of the circulating heat exchanger. The output end of the compressor is connected to the gas storage chamber through the heat release pipe of the compression process heat exchanger. The compressed air in the gas storage chamber is gaseous. The condensate drain outlet of the condenser is connected to the heat absorption pipe of the compression process heat exchanger. The output end of the gas storage chamber is connected to the expander through the heat absorption pipe of the expansion process heat exchanger. The output end of the expander is connected to the circulating water pump through the third coupling. The input end of the circulating water pump is connected to the output end of the cooling tower, and the output end is connected to the condenser through the heat release pipe of the circulating heat exchanger. The peak shaving process includes: (1) When the power plant receives the deep peak shaving command of the unit, it connects the first coupling and uses part of the electrical energy output by the first generator to drive the third motor to work, thereby driving the compressor to work. The compression process of compressed air energy storage participates in the operation of the unit, and the peak load of the unit is reduced under the condition of ensuring safety. (2) The condensate discharged from the condenser is cooled by the circulating heat exchanger to cool the air whose temperature has increased after compression. (3) The compressed and cooled air is stored in the air storage chamber; (4) The condensate heated by compressed air increases the final feedwater temperature; (5) The gas storage process ends when the gas pressure in the gas storage chamber reaches the limit pressure; (6) If the gas storage process ends and the unit is still in deep peak shaving state, disconnect the first coupling and connect the second coupling so that part of the electrical energy output by the first generator drives the refrigeration and storage equipment to work, and the cooling medium is stored in the refrigeration and storage equipment after being cooled. (7) When the unit is operating at high load, or during the day or when the ambient temperature is high, the cooling medium stored in the refrigeration and storage equipment reduces the temperature of the circulating water through the circulating heat exchanger, thereby reducing the vacuum of the unit. (8) Part of the electricity generated by the first generator is used for compressed air or refrigeration, which reduces the power supply of the unit to the grid, but the actual operating load of the unit is high; (9) When some auxiliary equipment of the unit fails, the unit cannot operate at high load or full load, or the unit has a large heat supply and cannot operate at high load or full load. If the power grid requires the unit to output at high load or full load at this time, the expansion process of compressed air energy storage will participate in the unit operation, and the maximum power supply load of the unit will increase. (10) Open the first regulating valve, the second regulating valve and the fourth regulating valve so that the air stored in the gas storage chamber is heated by the exhaust steam of the intermediate pressure cylinder before entering the expander, thereby improving the work capacity. The exhaust steam is cooled and then discharged into the condenser. The first regulating valve is located between the expansion process heat exchanger and the condenser, the second regulating valve is located between the expansion process heat exchanger and the gas storage chamber, and the fourth regulating valve is located between the expansion process heat exchanger and the intermediate pressure cylinder. (11) Connect the fourth coupling so that the transmission line from the second generator to the power grid is open, the expander of the compressed air energy storage does work, and the system output is the sum of the output of the first generator and the second generator. (12) The expander is a multi-stage expander. Each stage expander is equipped with an expansion process heat exchanger. The air in the gas storage chamber is heated by the expansion process heat exchanger before entering each stage expander. (13) If the output of the unit itself can meet the grid load requirements, there is no need for the second generator to generate electricity and connect to the grid. The third coupling is connected, and the compressed air in the gas storage chamber drives the expander to do work, which drives the circulating water pump to work.

2. The deep peak-shaving system coupling thermal power units and compressed air energy storage according to claim 1, characterized in that, The steam turbine cylinder assembly includes a high-pressure cylinder, an intermediate-pressure cylinder, and a low-pressure cylinder connected in sequence via a rotating shaft.

3. A deep peak-shaving system coupled with compressed air energy storage for thermal power units according to claim 2, characterized in that, The high-pressure cylinder, medium-pressure cylinder, and low-pressure cylinder are connected to the first generator via a rotating shaft. Steam passes through the high-pressure cylinder, medium-pressure cylinder, and low-pressure cylinder in sequence to perform work and drive the generator to generate electricity.

4. A deep peak-shaving system coupling thermal power units and compressed air energy storage according to claim 1, characterized in that, The system also includes a condensate pump, and the output end of the heat absorption line of the compression process heat exchanger is connected to the boiler via the condensate pump.

5. A deep peak-shaving system coupling thermal power units and compressed air energy storage according to claim 4, characterized in that, The condensate pump is a variable frequency pump.

6. A deep peak-shaving system coupled with compressed air energy storage for thermal power units according to claim 1, characterized in that, The system also includes a second generator, and the output of the expander is connected to the second generator via a fourth coupling.

7. A deep peak-shaving system coupled with compressed air energy storage for thermal power units according to claim 1, characterized in that, The heat release pipes of the expansion process heat exchanger are connected to the steam cylinder group of the steam turbine.

8. A deep peak-shaving system coupled with compressed air energy storage for thermal power units according to claim 1, characterized in that, The circulating water pump is a variable frequency pump.

9. A deep peak-shaving system coupled with compressed air energy storage for thermal power units according to claim 1, characterized in that, The compressor has multiple stages.

10. A deep peak-shaving system coupled with compressed air energy storage for thermal power units according to claim 1, characterized in that, The expander has multiple stages.

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