Thermal power generating unit and pressure-bearing heat storage coupling system and operation method

Abstract

The invention relates to a thermal power generating unit and pressure-bearing heat storage coupling system and an operation method.The system comprises a unit subsystem and a heat storage and supply subsystem, the heat storage and supply subsystem comprises a heat storage loop, a heat storage tank, a flash evaporation steam supply loop and a heat exchange hot water supply loop, and the heat storage loop comprises a steam-water heat exchanger, a first mixing heat exchanger and a first booster pump; a steam inlet of the steam-water heat exchanger communicates with the cold re-extraction branch pipe and the hot re-extraction branch pipe, and a high-pressure water inlet and a drainage outlet of the steam-water heat exchanger communicate with a high-pressure water outlet and a drainage inlet of the first mixing heat exchanger correspondingly. A heat storage water outlet and a heat storage water inlet of the heat storage tank communicate with a high-pressure water inlet of the first mixing heat exchanger and a high-pressure water outlet of the steam-water heat exchanger correspondingly, and the flash evaporation steam supply loop and the heat exchange hot water supply loop are used for load rising peak shaving and frequency modulation. The variable load rate of the unit is improved, and frequency modulation of the unit is achieved; and the peak regulation capacity of the unit is improved, and ultra-wide load peak regulation of the unit is achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of thermal power generation units, and in particular to a coupling system of a thermal power generation unit and a pressurized heat storage device and an operating method thereof. Background Art

[0002] In recent years, the installed capacity of new energy power generation such as wind power and solar power in my country has grown rapidly, making the problem of new energy consumption more and more serious, and causing the peak-shaving problem of the power grid to become increasingly prominent. However, as a stable power source in my country, coal-fired power units are crucial to solving the peak-shaving problem of the power grid. At present, the actual technical peak-shaving range of my country's coal-fired power units has reached 60% to 70%. In developed Western countries, cogeneration units generally use heat storage to carry out flexibility transformation, and their peak-shaving range can reach 70% to 80%. It can be seen that there is still a lot of room for improvement in peak-shaving of my country's coal-fired power units.

[0003] In order to tap the flexibility of cogeneration units, technologies such as low-pressure cylinder zero output and electric heat storage boilers are widely used to improve the peak-shaving capacity of cogeneration units. However, the peak-shaving and frequency-regulating problems of pure condensing conditions of coal-fired power units are currently mainly solved through boiler-side flexibility transformation, but due to restrictions on project implementation and safety factors, the scope of application of the transformation is limited. Summary of the invention

[0004] The present invention provides a coupling system and operation method of a thermal power unit and pressurized heat storage, which utilizes heat storage coupled with flash evaporation to achieve both an increase in the load change rate of the coal-fired power pure condensing unit to respond to the frequency regulation needs of the power grid and an increase in the peak regulation capacity of the coal-fired power pure condensing unit to respond to the peak regulation needs of the power grid.

[0005] To achieve the above object, the present invention adopts the following technical solutions:

[0006] A coupling system of a thermal power unit and pressurized heat storage, comprising a unit subsystem and a heat storage subsystem;

[0007] The above-mentioned unit subsystem includes a boiler, a high-pressure cylinder, an intermediate-pressure cylinder, a low-pressure cylinder and a boiler feed water pipeline. The above-mentioned boiler feed water pipeline is sequentially provided with a condenser, a condensate pump, a low-pressure heater group, a first intermediate-pressure heater, a deaerator, a second intermediate-pressure heater and a high-pressure heater group along the flow direction of condensate.

[0008] The exhaust port of the high-pressure cylinder is connected to a cold re-extraction branch pipe, and the reheat steam outlet of the boiler is connected to a hot re-extraction branch pipe;

[0009] The above-mentioned heat storage and supply subsystem includes a heat storage circuit, a heat storage tank, a flash steam supply circuit and a heat exchange hot water supply circuit;

[0010] The heat storage circuit comprises a steam-water heat exchanger, a first mixed heat exchanger and a first booster pump. The steam inlet of the steam-water heat exchanger is connected to the cold re-extraction steam branch pipe and the hot re-extraction steam branch pipe. The high-pressure water inlet and drain outlet of the steam-water heat exchanger are respectively connected to the high-pressure water outlet and drain inlet of the first mixed heat exchanger. The hot water storage outlet and the hot water storage inlet of the heat storage tank are respectively connected to the high-pressure water inlet of the first mixed heat exchanger and the high-pressure water outlet of the steam-water heat exchanger. A first booster pump is provided at the high-pressure water outlet of the first mixed heat exchanger.

[0011] The hot water inlet of the heat storage tank is provided with a second booster pump, the high-pressure water inlet and outlet of the flash steam supply circuit are respectively connected with the hot water outlet of the heat storage tank and the water inlet of the second booster pump, and the exhaust port of the flash steam supply circuit is connected with the low-pressure heater group, the first medium-pressure heater and the deaerator;

[0012] The high-pressure water inlet and outlet of the heat exchange hot water supply circuit are respectively connected to the hot water discharge outlet of the heat storage tank and the water inlet of the second booster pump, and the water supply inlet and water supply outlet of the heat exchange hot water supply circuit are respectively connected to the outlet of the condensate pump and the water inlet of the deaerator.

[0013] Preferably, the cold re-extraction steam branch pipe and the hot re-extraction steam branch pipe are respectively provided with a first control valve and a second control valve, and the first control valve and the second control valve are used in combination to adjust the temperature and flow rate of the steam entering the steam-water heat exchanger according to the peak regulation and frequency regulation requirements of the unit.

[0014] Preferably, a third control valve is provided at the high-pressure water inlet of the flash steam supply circuit, and a fourth control valve is provided at the high-pressure water inlet of the heat exchange hot water supply circuit. The third control valve and the fourth control valve are used in conjunction with each other to control the operation of the flash steam supply circuit and the heat exchange hot water supply circuit according to the peak regulation and frequency regulation requirements of the unit.

[0015] Preferably, the heat storage tank is a pressurized high-temperature hot water heat storage tank.

[0016] Preferably, the flash steam supply circuit comprises a flash tank and a second mixing heat exchanger;

[0017] The high-pressure water inlet of the flash tank is connected to the hot water outlet of the heat storage tank, the saturated water outlet of the flash tank is connected to the first water inlet of the second mixing heat exchanger, and the steam outlet of the flash tank is connected to the low-pressure heater group, the first medium-pressure heater and the deaerator;

[0018] The second water inlet of the second mixing heat exchanger is connected to the water outlet of the condenser, and a third booster pump is provided at the second water inlet of the second mixing heat exchanger. The water outlet of the second mixing heat exchanger is connected to the hot water inlet of the heat storage tank.

[0019] Preferably, the heat exchange hot water supply circuit includes a water-to-water heat exchanger, the high-pressure water inlet and outlet of the water-to-water heat exchanger are respectively connected to the hot water discharge outlet of the heat storage tank and the water inlet of the second booster pump, the water supply inlet of the water-to-water heat exchanger is connected to the water outlet of the condensate pump, and the water supply outlet of the water-to-water heat exchanger is connected to the water inlet of the deaerator.

[0020] An operating method based on the above-mentioned coupling system of thermal power unit and pressurized heat storage, wherein the flash steam supply circuit in the above-mentioned system comprises a flash tank and a second mixing heat exchanger, the above-mentioned heat exchange hot water supply circuit comprises a water-to-water heat exchanger, and the above-mentioned operating method comprises a peak shaving method, and the above-mentioned peak shaving method comprises:

[0021] When the thermal power unit is load-reduced for peak regulation, the first control valve in the cold re-extraction branch pipe and the second control valve on the hot re-extraction branch pipe are opened, so that the cold re-steam in the cold re-extraction branch pipe and the hot re-steam in the hot re-extraction branch pipe form mixed high-temperature steam and enter the steam-water heat exchanger, and the drain discharged from the steam-water heat exchanger and the low-temperature water output from the heat storage tank enter the first mixing heater for mixing and heating, and then enter the steam-water heat exchanger under the action of the first booster pump to exchange heat with the mixed high-temperature steam to form high-temperature water and then return to the heat storage tank for heat storage;

[0022] When the thermal power unit is loaded for peak regulation and the water pressure in the heat storage tank meets the flash evaporation condition, the third control valve at the high-pressure water inlet of the flash evaporator is opened, and the fourth control valve at the high-pressure water inlet of the water-to-water heat exchanger is closed, so that the high-pressure and high-temperature water in the heat storage tank enters the flash evaporator for flash evaporation, and the steam generated by the flash evaporation is transported to the low-pressure heater group, the first medium-pressure heater and the deaerator, and the saturated water generated by the flash evaporation enters the second mixing heat exchanger, can be mixed with the condensed water, and then enters the heat storage tank again through the second booster pump;

[0023] When the thermal power unit is loaded for peak regulation and the water pressure in the heat storage tank does not meet the flash evaporation conditions, the third control valve at the high-pressure water inlet of the flash tank is closed, and the fourth control valve at the high-pressure water inlet of the water-to-water heat exchanger is opened, so that the high-pressure and high-temperature water in the heat storage tank enters the water-to-water heat exchanger and exchanges heat with the incoming condensate. The low-temperature water after heat exchange enters the heat storage tank through the second booster pump, and the high-temperature water after heat exchange with the condensate is transported to the deaerator.

[0024] Preferably, the low-pressure heater group in the above system includes a first low-pressure heater, a second low-pressure heater, and a third low-pressure heater arranged along the flow direction of water, the first low-pressure heater, the second low-pressure heater, the third low-pressure heater, the first medium-pressure heater and the deaerator are all connected to the steam outlet of the flash evaporator, and the first low-pressure heater, the second low-pressure heater, the third low-pressure heater, the first medium-pressure heater and the steam inlet of the deaerator are respectively provided with a first steam supply valve, a second steam supply valve, a third steam supply valve, a fourth steam supply valve and a fifth steam supply valve, the water supply outlet of the water-to-water heat exchanger is connected to the inlet of the deaerator, and a hot water supply valve is provided at the water supply outlet of the water-to-water heat exchanger; the operation method also includes a frequency modulation method, and the frequency modulation method includes:

[0025] When the thermal power unit participates in load reduction and frequency regulation, the hot re-steam flow through the hot re-extraction branch pipe and the cold re-steam flow in the cold re-extraction branch pipe are changed by adjusting the opening of the first control valve and the second control valve, so as to change the steam inlet amount of the intermediate pressure cylinder;

[0026] When the thermal power unit participates in load increase and frequency modulation and uses the flash steam supply circuit, the steam supply from the flash evaporator to the first low-pressure heater, the second low-pressure heater, the third low-pressure heater, the second-stage medium-pressure regenerative heater and the deaerator is adjusted by adjusting the opening of the first steam supply valve, the second steam supply valve, the third steam supply valve, the fourth steam supply valve and the fifth steam supply valve to replace the unit's regenerative steam flow;

[0027] When the thermal power unit participates in load increase and frequency regulation and uses the heat exchange hot water supply circuit, the amount of hot water sent to the deaerator by the water-to-water heat exchanger is adjusted by adjusting the opening of the hot water supply valve, replacing the unit's heat recovery extraction steam to heat the circulating condensate.

[0028] Preferably, when the thermal power unit is loaded up for peak load regulation, the flash evaporator is preferentially selected to generate steam to replace the unit's heat recovery steam extraction, so as to increase the amount of steam used to generate power for the unit and meet the unit's peak load regulation requirements; secondly, the water-to-water heat exchanger is selected to heat the feed water to replace the unit's heat recovery steam extraction, so as to increase the amount of steam used to generate power for the unit and meet the unit's peak load regulation requirements.

[0029] Preferably, when the thermal power unit is loaded and frequency modulated, the flash evaporator is preferentially selected to generate steam to change the heat recovery steam flow of the replaced unit, so as to change the variable load rate of the unit and meet the unit frequency modulation requirements; secondly, the water-to-water heat exchanger is selected to heat the feed water to change the heat recovery steam flow of the replaced unit, so as to change the variable load rate of the unit and meet the unit frequency modulation requirements.

[0030] Compared with the prior art, the present invention has the following beneficial effects:

[0031] 1. This coupling system adds a heat storage and supply subsystem to the unit, extracts reheat steam and / or high-pressure cylinder exhaust steam to exchange heat with hot water, and stores it in the heat storage tank, so that the unit can quickly reduce the load. By returning the heat in the heat storage tank to the boiler feed water pipeline through flash steam supply or heat exchange hot water supply, it can directly or indirectly reduce the extraction amount of steam in the cylinder, thereby increasing the additional power generation of the unit, allowing the unit to quickly increase the load, making the unit more flexible in peak load regulation, and improving the peak load regulation capacity of the unit.

[0032] 2. By using the reheated steam and high-pressure cylinder extraction steam of the unit as the main energy source for heat storage, the heat of the steam can be fully utilized to avoid heat waste. The water discharged after the extraction steam heat exchange can be used as water replenishment for the heat storage tank. It can also increase the initial temperature of the hot water stored in the heat storage tank before heat exchange, and use the waste heat of the hot water to make the heat exchange in the steam-water heat exchanger more sufficient.

[0033] 3. Two heating circuits are set up to meet the heating needs of the heat storage tank under different conditions and meet the load increase requirements of the unit. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0035] Figure 1 Schematic diagram of a system according to an embodiment of the present invention.

[0036] Description of reference numerals:

[0037] 1. Boiler; 2. High-pressure cylinder; 3. Medium-pressure cylinder; 4. Low-pressure cylinder; 5. Boiler feed water pipeline; 6. Condenser; 7. Condensate pump; 8. First low-pressure heater; 9. Second low-pressure heater; 10. Third low-pressure heater; 11. First medium-pressure heater; 12. Deaerator; 13. Second medium-pressure heater; 14. First high-pressure heater; 15. Second high-pressure heater; 16. Cold re-exhaust pipe; 17. Cold re-extraction branch pipe; 18. Hot re-extraction branch pipe; 19. First control valve; 20. Second control valve; 21. Steam-water heat exchanger; 22. First mixing heat exchanger; 23. First booster pump; 24. First pipe; 25. First valve; 26. Second pipe; 27. Third pipe; 28. Third valve; 29. ​​Heat storage tank; 30. Water inlet Main pipe; 31. Second booster pump; 32. Water supply main pipe; 33. Fourth pipe; 34. Flash evaporator; 35. Second mixing heat exchanger; 36. Fifth pipe; 37. Fifth valve; 38. Water supply pipe; 39. Third booster pump; 40. First steam supply pipe; 41. Second steam supply pipe; 42. Third steam supply pipe; 43. Fourth steam supply pipe; 44. Fifth steam supply pipe; 45. First steam supply valve; 46. Second steam supply valve; 47. Third steam supply valve; 48. Fourth steam supply valve; 49. Fifth steam supply valve; 50. Water supply valve; 51. Sixth pipe; 52. Water-to-water heat exchanger; 53. Seventh pipe; 54. Seventh valve; 55. Eighth pipe; 56. Eighth valve; 57. Hot water supply pipe; 58. Hot water supply valve; 59. Third control valve; 60. Fourth control valve. DETAILED DESCRIPTION

[0038] The technical solution of the present invention will be described clearly and completely below in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0039] In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", and "third" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance.

[0040] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be fixed connection, detachable connection, or integrated connection; it can be mechanical connection or electrical connection; it can be directly connected or indirectly connected through an intermediate medium, or it can be internal connection of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0041] like Figure 1 As shown, an embodiment of the present invention provides a coupling system of a thermal power unit and pressurized heat storage, including a unit subsystem and a heat storage subsystem, wherein the unit subsystem is an existing system used for heating and power generation of the unit, and the heat storage subsystem is used to store steam heat and supply heat to the unit, so that the peak regulation and frequency regulation of the unit subsystem are more flexible.

[0042] Among them, the unit subsystem includes a boiler 1, a high-pressure cylinder 2, a medium-pressure cylinder 3, a low-pressure cylinder 4 and a boiler feed water pipeline 5. The boiler feed water pipeline 5 is provided with a condenser 6, a condensate pump 7, a low-pressure heater group, a first medium-pressure heater 11, a deaerator 12, a second medium-pressure heater 13 and a high-pressure heater group in sequence along the flow direction of circulating water. In this embodiment, the low-pressure heater group includes a first low-pressure heater 8, a second low-pressure heater 9 and a third low-pressure heater 10 arranged in sequence along the flow direction of circulating water, and the high-pressure heater group includes a first high-pressure heater 14 and a second high-pressure heater 15 arranged in sequence in the flow direction of circulating water. Specifically, the steam outlet of the boiler 1 is connected to a main steam pipe, the main steam pipe is connected to the steam inlet of the high-pressure cylinder 2, the exhaust port of the high-pressure cylinder 2 is connected to the first high-pressure steam pipe and the second high-pressure steam pipe, and the first high-pressure steam pipe is connected to the second high-pressure heater 15 , for steam supply, the second high-pressure steam pipe is connected with a cold re-exhaust pipe 16 and a cold re-extraction branch pipe 17, the cold re-exhaust pipe 16 is directly connected with the reheat steam inlet of the boiler 1 for reheating, a high-pressure steam branch pipe is formed at the cold re-exhaust pipe 16, which is connected with the first high-pressure heater 14 to supply steam for it, the reheat steam outlet of the boiler 1 is connected with a medium-pressure steam supply pipe and a hot re-extraction branch pipe 18, the medium-pressure steam supply pipe is connected with the steam inlet of the medium-pressure cylinder 3, the steam extraction port of the medium-pressure cylinder 3 is connected with three medium-pressure steam extraction pipes, which are respectively connected with the first medium-pressure heater 11, the deaerator 12 and the second medium-pressure heater 13, the steam exhaust port of the medium-pressure cylinder 3 is connected with a low-pressure steam supply pipe, which is connected with the steam inlet of the low-pressure cylinder 4, the steam exhaust port of the low-pressure cylinder 4 is connected with the exhaust steam inlet of the condenser 6, and the steam extraction port of the low-pressure cylinder 4 is connected with three low-pressure steam extraction pipes, which are respectively connected with the first low-pressure heater 8, the second low-pressure heater 9 and the third low-pressure heater 10.

[0043] Among them, the heat storage and supply subsystem includes a heat storage circuit, a heat storage tank 29, a flash steam supply circuit and a heat exchange hot water supply circuit. The heat storage circuit uses the heat of the cold re-steam in the cold re-extraction branch pipe 17 and the hot re-steam in the hot re-extraction branch pipe 18 to exchange heat with the water in the heat storage tank 29, so that hot water is formed in the heat storage tank 29 to achieve heat storage. The flash steam supply circuit and the heat exchange hot water supply circuit use the high-pressure hot water in the heat storage tank 29 as a heat source to supply steam to the low-pressure heater, the medium-pressure heater and the deaerator 12 or provide hot water for the circulating water circuit, thereby saving steam extraction from the cylinder, realizing the heat storage and supply of the unit by the heat storage subsystem, and realizing the peak load regulation of the unit. Specifically, the heat storage tank 29 is a pressurized high-temperature hot water storage tank.

[0044] Specifically, the heat storage circuit includes a steam-water heat exchanger 21, a first mixed heat exchanger 22 and a first booster pump 23. The exhaust ports of the cold re-extraction steam branch pipe 17 and the hot re-extraction steam branch pipe 18 are connected and are connected to the steam inlet of the steam-water heat exchanger 21. The drain outlet of the steam-water heat exchanger 21 is connected to the drain inlet of the first mixed heat exchanger 22. The hot water outlet of the heat storage tank 29 is connected to the high-pressure water inlet of the first mixed heat exchanger 22 through a first pipe 24. A first valve 25 is provided on the first pipe 24. The high-pressure water outlet of the first mixed heat exchanger 22 is connected to the high-pressure water inlet of the steam-water heat exchanger 21 through a second valve. The first and second pipes 26 are connected, the first booster pump 23 is installed on the second pipe 26, the high-pressure water outlet of the steam-water heat exchanger 21 is connected with the hot water storage inlet of the heat storage tank 29 through the third pipe 27, and the third valve 28 is arranged on the third pipe 27. The heat storage on and off of the whole heat storage circuit can be controlled by the first valve 25 and the third valve 28. Specifically, in the heat storage stage, the first valve 25 and the third valve 28 are opened, and the cold re-steam in the cold re-extraction steam branch pipe 17 and the hot re-steam in the hot re-extraction steam branch pipe 18 are mixed together and enter the steam-water heat exchanger 21. After heat exchange, the formed drainage enters the first mixing heat exchanger. The hot water in the heat storage tank 29 is mixed with the hot water in the heat storage tank 22, which is used to replenish water and preheat the hot water. Then, the hot water enters the steam-water heat exchanger 21 under the action of the first booster pump 23, exchanges heat with the mixed steam to form high-temperature water, and then enters the heat storage tank 29 for storage. By extracting the extracted steam, the unit can be quickly loaded down, and the flexibility of load reduction can be improved. In the above heat storage process, the hot water in the heat storage tank 29 is preheated first and then heated, so that the heat in the mixed steam can be fully utilized for sufficient heat exchange. In addition, the exhaust steam of the high-pressure cylinder 2 and the reheated steam of the boiler 1 are used to charge the hot water. When the heat storage energy source is used, the purpose is to make full use of the heat of steam and avoid heat waste. If the steam in the main steam pipe of boiler 1 is used directly, the steam parameters are too high, which can easily lead to insufficient heat exchange and heat waste. Furthermore, the cold re-steam in the cold re-extraction branch pipe 17 and the hot re-steam in the hot re-extraction branch pipe 18 can be mixed and used together, as mentioned above, or the cold re-extraction branch pipe 17 can be used alone, which is specifically determined according to the heat storage temperature of the water in the heat storage tank 29. Of course, in existing use, the cold re-extraction branch pipe 17 and the hot re-extraction branch pipe 18 are generally opened together and used together.

[0045] Specifically, the cold re-extraction steam branch pipe 17 and the hot re-extraction steam branch pipe 18 are respectively installed with a first control valve 19 and a second control valve 20, which are used in conjunction with each other to adjust the temperature of the steam entering the steam-water heat exchanger 21. Specifically, the first control valve 19 can be opened and the second control valve 20 can be closed to allow only the cold re-extraction steam branch pipe 17 to supply steam, or the first control valve 19 and the second control valve 20 can be opened to allow both the cold re-extraction steam branch pipe 17 and the hot re-extraction steam branch pipe 18 to supply steam at the same time, which is specifically determined according to the water storage temperature required by the heat storage tank 29. Of course, the first control valve 19 and the second control valve 20 are generally opened at the same time to allow both the cold re-extraction steam branch pipe 17 and the hot re-extraction steam branch pipe 18 to supply steam at the same time. Of course, the first control valve 19 and the second control valve 20 are control valves with adjustable openings. The openings of the first control valve 19 and the second control valve 20 can be adjusted to adjust the temperature and supply amount of the mixed steam entering the steam-water heat exchanger 21, thereby realizing frequency modulation during the load reduction process of the unit.

[0046] Specifically, the hot water inlet of the heat storage tank 29 is connected to the water inlet main pipe 30, and the second booster pump 31 and the water inlet valve are installed on the fourth pipe 33, wherein the high-pressure water inlet and the water outlet of the flash steam supply circuit are respectively connected to the hot water outlet of the heat storage tank 29 and the water inlet of the second booster pump 31 to form a loop, and the exhaust port of the flash steam supply circuit is connected to the first low-pressure heater 8, the second low-pressure heater 9 and the third low-pressure heater 10, the first medium-pressure heater 11 and the deaerator 12, and the steam formed by flash evaporation will be transported to the first low-pressure heater 8, the second low-pressure heater 9 and the third low-pressure heater 10, the first medium-pressure heater 11 and the deaerator 12, thereby reducing the steam extraction amount of the medium-pressure cylinder 3 and the low-pressure cylinder 4, so that more steam can be used for power generation, so that the unit can stably and quickly increase the load without excessively increasing the combustion cost of the unit. Specifically, the flash steam supply circuit includes a flash tank and a second mixing heat exchanger 35, wherein the hot water outlet of the heat storage tank 29 is connected to the water supply main 32, the high-pressure water inlet of the flash tank is connected to the water supply main 32 through the fourth pipe 33, the saturated water outlet of the flash tank is connected to the first water inlet of the second mixing heat exchanger 35 through the fifth pipe 36, the fifth pipe 36 is equipped with a fifth valve 37, the second water inlet of the first mixing heat exchanger 22 is connected to the water outlet of the condenser 6 through the water supply pipe 38, the water supply pipe 38 is equipped with a third booster pump 39, the water outlet of the second mixing heat exchanger 35 is connected to the second booster pump 31, the steam outlet of the flash tank is connected to the first low-pressure heater 8, the second low-pressure heater 9 and the third low-pressure heater 10, the first medium-pressure heater 11 and the deaerator 12 through the first steam supply pipe 40, the second steam supply pipe 41, the third steam supply pipe 42, the fourth steam supply pipe 43, the steam outlet of the flash tank is connected to the first low-pressure heater 8, the second low-pressure heater 9 and the third low-pressure heater 10, the first medium-pressure heater 11 and the deaerator 12 through the first steam supply pipe 40, the second steam supply pipe 41, the third steam supply pipe 42, the fourth steam supply pipe 4 ... 43 is connected to the fifth steam supply pipe 44, which is used to supply steam to the above-mentioned steam supply pipes. Of course, the first steam supply valve 45, the second steam supply valve 46, the third steam supply valve 47, the fourth steam supply valve 48 and the fifth steam supply valve 49 are respectively provided on the first steam supply pipe, the second steam supply pipe 41, the third steam supply pipe 42, the fourth steam supply pipe 43 and the fifth steam supply pipe 44. By controlling the corresponding valves, the on-off of the corresponding steam supply pipes can be controlled; specifically, when supplying steam, the high-pressure and high-temperature water in the heat storage tank 29 enters the flash evaporator 34, the saturated water formed by the flash steam enters the first mixing heat exchanger 22, and is mixed with the condensate supplied by the third booster pump 39, and then enters the heat storage tank 29 through the second booster pump 31, and the steam coming out of the flash evaporator 34 enters the first low-pressure heater 8, the second low-pressure heater 9 and the third low-pressure heater 10, the first medium-pressure heater 11 and the deaerator 12 to supplement steam. Of course, it is known that a water supply valve 50 is provided on the water supply pipe 38, and the opening degree of the water supply valve 50 can be adjusted to control the amount of water replenishment. Of course, in normal operation, the opening degree of the water supply valve 50 is constant, and the amount of water replenishment is constant.

[0047] Specifically, the high-pressure water inlet and outlet of the heat exchange hot water supply circuit are respectively connected to the hot water outlet of the heat storage tank 29 and the water inlet of the second booster pump 31, the water supply inlet of the heat exchange hot water supply circuit is connected to the water outlet of the condensate pump 7, and the water supply outlet is connected to the water inlet of the deaerator 12. Specifically, the heat exchange hot water supply circuit includes a water-to-water heat exchanger 52, the high-pressure water inlet of the water-to-water heat exchanger 52 is connected to the water supply main 32 through the sixth pipe 51, the water outlet is connected to the third booster pump 39 through the seventh pipe 53, the seventh pipe 53 is provided with a seventh valve 54, the water supply inlet of the water-to-water heat exchanger 52 is connected to the water outlet of the condensate pump 7 through the eighth pipe 55, the eighth pipe 55 is provided with an eighth control valve, the water supply outlet is connected to the water inlet of the deaerator 12 through the hot water supply pipe 57, and the hot water supply valve 58 is provided on the hot water supply pipe 57; Specifically, when supplying hot water, first open the seventh valve 54, the eighth valve 56 and the hot water supply valve 58, and the high-pressure and high-temperature water in the heat storage tank 29 enters the water-to-water heat exchanger 52. At the same time, the condensed water enters the water-to-water heat exchanger 52 through the hot water supply pipe 57. The high-pressure and high-temperature water is converted into low-temperature and low-pressure water and enters the seventh pipe 53. Then, it enters the heat storage tank 29 through the third booster pump 39. The condensed water becomes high-temperature water and enters the hot water supply pipe 57. Then, it enters the deaerator 12 for deoxygenation, thereby indirectly reducing the steam supply from the medium-pressure cylinder 3 to the deaerator 12 and the second medium-pressure heater 13.

[0048] Specifically, a third control valve 59 is installed on the fourth pipe 33, and a fourth control valve 60 is installed at the sixth pipe 51. The third control valve 59 and the fourth control valve 60 are used in conjunction with each other to control the operation of the flash steam supply circuit and the heat exchange hot water supply circuit. Specifically, there are the following three operation modes: the first mode: the third control valve 59 is opened and the fourth control valve 60 is opened at the same time, so that the flash steam supply circuit and the heat exchange hot water supply circuit operate at the same time; the second mode: the third control valve 59 is opened and the fourth control valve 60 is closed, so that the flash steam supply circuit operates and the heat exchange hot water supply circuit does not operate; the third mode: the third control valve 59 is closed and the fourth control valve 60 is opened, so that the flash steam supply circuit does not operate and the heat exchange hot water supply circuit operates; at the same time, the third control valve 59 and the fourth control valve 60 are both valves with adjustable openings, and the flow rate of high-pressure and high-temperature water entering the corresponding circuit can be controlled by adjusting their respective operating openings, thereby controlling the supply rate of corresponding steam or corresponding hot water, and realizing frequency modulation during the load increase process of the unit.

[0049] The coupling system adds a heat storage and supply subsystem to the unit, extracts reheated steam and / or exhaust steam from the high-pressure cylinder 2 for heat exchange with the stored hot water, and stores the extracted steam in the heat storage tank 29, so that the unit can quickly reduce the load. By returning the heat in the heat storage tank 29 to the boiler feed water pipeline 5 through flash steam supply or heat exchange for hot water supply, the extraction amount of steam in the cylinder can be directly or indirectly reduced, thereby increasing the increased power generation of the unit, allowing the unit to quickly increase the load, making full use of energy, making the unit more flexible in peak load regulation, and improving the peak load regulation capacity of the unit; by adjusting the opening of the first control valve 19, the second control valve 20, the first steam supply valve 45, the second steam supply valve 46, the third steam supply valve 47, the fourth steam supply valve 48, the fifth steam supply valve 49 and the hot water supply valve 58, the frequency modulation of the unit's load increase and decrease is achieved, making the frequency modulation more flexible.

[0050] The embodiment of the present invention further provides an operation method based on the coupling system of the thermal power unit and the pressurized heat storage, including peak regulation and frequency regulation, wherein the peak regulation operation method includes:

[0051] When the thermal power unit is load-reduced for peak regulation, the first control valve 19 and the second control valve 20 are opened, and the first valve 25 and the third valve 28 are opened, so that the cold re-steam in the cold re-extraction branch pipe 17 and the hot re-steam in the hot re-extraction branch pipe 18 form mixed high-temperature steam and enter the steam-water heat exchanger 21, and the drain water discharged from the steam-water heat exchanger 21 and the low-temperature water output from the heat storage tank 29 enter the first mixing heater for mixing and heating, and then enter the steam-water heat exchanger 21 under the action of the first booster pump 23 to exchange heat with the mixed high-temperature steam, forming high-temperature water and then returning to the heat storage tank 29 for heat storage, thereby realizing heat storage;

[0052] When the thermal power unit is loaded for peak regulation and the water pressure in the heat storage tank 29 meets the flash evaporation condition, the third control valve 59 is opened and the fourth control valve 60 is closed, so that the high-pressure and high-temperature water in the heat storage tank 29 enters the flash evaporator 34 for flash evaporation, and the steam generated by the flash evaporation is transported to the first low-pressure heater 8, the second low-pressure heater 9, the third low-pressure heater 10, the first medium-pressure heater 11 and the deaerator 12. The saturated water generated by the flash evaporation enters the second mixing heat exchanger 35, and after mixing with the condensed water, enters the heat storage tank 29 again through the second booster pump 31;

[0053] When the thermal power unit is loaded for peak regulation and the water pressure in the heat storage tank 29 does not meet the flash evaporation condition, the third control valve 59 is closed and the fourth control valve 60 is opened, so that the high-pressure and high-temperature water in the heat storage tank 29 enters the water-to-water heat exchanger 52 and exchanges heat with the incoming condensate. The low-temperature water after the heat exchange enters the heat storage tank 29 through the second booster pump 31, and the high-temperature water after the heat exchange with the condensate is transported to the deaerator 12 for deoxygenation.

[0054] The frequency modulation methods include:

[0055] When the thermal power unit participates in load reduction and frequency regulation, the opening of the first control valve 19 and the second control valve 20 can be adjusted to change the steam flow through the hot re-extraction branch pipe 18 and the cold re-extraction branch pipe 17, thereby changing the amount of steam entering the intermediate pressure cylinder 3, thereby changing the load change rate of the unit and realizing load reduction and frequency regulation of the unit. The specific adjustment of the opening of the first control valve 19 and the second control valve 20 is determined according to demand conditions.

[0056] When the thermal power unit participates in load increase frequency modulation and uses the flash steam supply circuit, the steam supply amount sent by the flash evaporator 34 to the first low-pressure heater 8, the second low-pressure heater 9, the third low-pressure heater 10, the second-stage medium-pressure regenerative heater and the deaerator 12 is adjusted by adjusting the opening of the first steam supply valve 45, the second steam supply valve 46, the third steam supply valve 47, the fourth steam supply valve 48 and the fifth steam supply valve 49, so as to replace the unit heat recovery extraction flow, thereby changing the unit's variable load rate and realizing the unit's load increase frequency modulation. The specific opening adjustment of the first steam supply valve 45, the second steam supply valve 46, the third steam supply valve 47, the fourth steam supply valve 48 and the fifth steam supply valve 49 is determined according to the demand situation;

[0057] When the thermal power unit participates in load-raising frequency modulation and uses the heat exchange hot water supply circuit, the opening of the hot water supply valve 58 is adjusted to adjust the amount of hot water delivered to the deaerator 12 by the water-to-water heat exchanger 52, replacing the heating of the circulating condensate by the unit's heat recovery extraction steam, changing the unit's load-changing rate, and thus achieving the unit's load-raising frequency modulation. The specific opening adjustment of the hot water supply valve 58 is determined according to demand conditions.

[0058] Preferably, when the thermal power unit is loaded up for peak load regulation, the flash evaporator is preferentially selected to generate steam to replace the unit's heat recovery steam extraction, so as to increase the amount of steam used to generate power for the unit and meet the unit's peak load regulation requirements; secondly, the water-to-water heat exchanger is selected to heat the feed water to replace the unit's heat recovery steam extraction, so as to increase the amount of steam used to generate power for the unit and meet the unit's peak load regulation requirements.

[0059] Preferably, when the thermal power unit is loaded and frequency modulated, the flash evaporator is preferentially selected to generate steam to change the heat recovery steam flow of the replaced unit, so as to change the variable load rate of the unit and meet the unit frequency modulation requirements; secondly, the water-to-water heat exchanger is selected to heat the feed water to change the heat recovery steam flow of the replaced unit, so as to change the variable load rate of the unit and meet the unit frequency modulation requirements.

[0060] The above-mentioned peak-shaving and frequency modulation methods give priority to flash evaporation peak-shaving and frequency modulation when the water pressure meets the condition of flash evaporation. When the water pressure does not meet the flash evaporation condition, water-to-water heat exchange peak-shaving and frequency modulation are selected. By utilizing heat storage coupled flash evaporation and water-to-water heat exchange, the load variation rate of the coal-fired pure condensing unit can be increased to respond to the frequency regulation needs of the power grid, and the peak-shaving capacity of the coal-fired pure condensing unit can be increased to respond to the peak-shaving needs of the power grid.

[0061] The above-mentioned embodiments are only preferred embodiments of the present invention and cannot be used to limit the scope of protection of the present invention. Any non-substantial changes and substitutions made by technicians in this field on the basis of the present invention shall fall within the scope of protection required by the present invention.

Claims

1. A coupling system of a thermal power unit and pressurized heat storage, characterized in that: It includes unit subsystem and heat storage subsystem; The unit subsystem includes a boiler, a high-pressure cylinder, an intermediate-pressure cylinder, a low-pressure cylinder and a boiler feed water pipeline, wherein the boiler feed water pipeline is provided with a condenser, a condensate pump, a low-pressure heater group, a first intermediate-pressure heater, a deaerator, a second intermediate-pressure heater and a high-pressure heater group in sequence along the flow direction of condensate; The exhaust port of the high-pressure cylinder is connected to a cold re-extraction branch pipe, and the reheat steam outlet of the boiler is connected to a hot re-extraction branch pipe; The heat storage and supply subsystem includes a heat storage loop, a heat storage tank, a flash steam supply loop and a heat exchange hot water supply loop; The heat storage circuit comprises a steam-water heat exchanger, a first mixed heat exchanger and a first booster pump, the steam inlet of the steam-water heat exchanger is connected to the cold re-extraction steam branch pipe and the hot re-extraction steam branch pipe, the high-pressure water inlet and the drain outlet of the steam-water heat exchanger are respectively connected to the high-pressure water outlet and the drain inlet of the first mixed heat exchanger, the hot water storage outlet and the hot water storage inlet of the heat storage tank are respectively connected to the high-pressure water inlet of the first mixed heat exchanger and the high-pressure water outlet of the steam-water heat exchanger, and a first booster pump is provided at the high-pressure water outlet of the first mixed heat exchanger; The hot water inlet of the heat storage tank is provided with a second booster pump, the high-pressure water inlet and outlet of the flash steam supply circuit are respectively connected with the hot water outlet of the heat storage tank and the water inlet of the second booster pump, and the exhaust port of the flash steam supply circuit is connected with the low-pressure heater group, the first medium-pressure heater and the deaerator; The high-pressure water inlet and outlet of the heat exchange hot water supply circuit are respectively connected to the hot water discharge outlet of the heat storage tank and the water inlet of the second booster pump, and the water supply inlet and water supply outlet of the heat exchange hot water supply circuit are respectively connected to the water outlet of the condensate pump and the water inlet of the deaerator.

2. The coupling system according to claim 1, characterized in that: The cold re-extraction steam branch pipe and the hot re-extraction steam branch pipe are respectively provided with a first control valve and a second control valve, and the first control valve and the second control valve are used in combination to adjust the temperature and flow of the steam entering the steam-water heat exchanger according to the peak regulation and frequency regulation requirements of the unit.

3. The coupling system according to claim 1, characterized in that: A third control valve is provided at the high-pressure water inlet of the flash steam supply circuit, and a fourth control valve is provided at the high-pressure water inlet of the heat exchange hot water supply circuit. The third control valve and the fourth control valve are used in conjunction with each other to control the operation of the flash steam supply circuit and the heat exchange hot water supply circuit according to the peak regulation and frequency regulation requirements of the unit.

4. The coupling system according to claim 1, characterized in that: The heat storage tank is a pressurized high-temperature hot water heat storage tank.

5. The coupling system according to claim 1, characterized in that: The flash steam supply circuit includes a flash tank and a second mixing heat exchanger; The high-pressure water inlet of the flash tank is connected to the hot water outlet of the heat storage tank, the saturated water outlet of the flash tank is connected to the first water inlet of the second mixing heat exchanger, and the steam outlet of the flash tank is connected to the low-pressure heater group, the first medium-pressure heater and the deaerator; The second water inlet of the second mixing heat exchanger is connected to the water outlet of the condenser, and a third booster pump is provided at the second water inlet of the second mixing heat exchanger. The water outlet of the second mixing heat exchanger is connected to the hot water inlet of the heat storage tank.

6. The coupling system according to claim 1, characterized in that: The heat exchange hot water supply circuit includes a water-to-water heat exchanger, the high-pressure water inlet and outlet of the water-to-water heat exchanger are respectively connected to the hot water discharge outlet of the heat storage tank and the water inlet of the second booster pump, the water supply inlet of the water-to-water heat exchanger is connected to the water outlet of the condensate pump, and the water supply outlet of the water-to-water heat exchanger is connected to the water inlet of the deaerator.

7. An operating method of a coupling system of a thermal power unit and pressurized heat storage according to any one of claims 1 to 6, characterized in that: The flash steam supply circuit in the coupling system includes a flash tank and a second mixing heat exchanger, the heat exchange hot water supply circuit includes a water-to-water heat exchanger, and the operation method includes a peak load regulation method, which includes: When the thermal power unit is load-reduced for peak load regulation, the first control valve on the cold re-extraction branch pipe and the second control valve on the hot re-extraction branch pipe are opened, so that the cold re-steam in the cold re-extraction branch pipe and the hot re-steam in the hot re-extraction branch pipe form mixed high-temperature steam and enter the steam-water heat exchanger, and the drain discharged from the steam-water heat exchanger and the low-temperature water output from the heat storage tank enter the first mixing heater for mixing and heating, and then enter the steam-water heat exchanger under the action of the first booster pump to exchange heat with the mixed high-temperature steam to form high-temperature water and then return to the heat storage tank for heat storage; When the thermal power unit is loaded for peak regulation and the water pressure in the heat storage tank meets the flash evaporation condition, the third control valve at the high-pressure water inlet of the flash evaporator is opened, and the fourth control valve at the high-pressure water inlet of the water-to-water heat exchanger is closed, so that the high-pressure and high-temperature water in the heat storage tank enters the flash evaporator for flash evaporation, and the steam generated by the flash evaporation is transported to the low-pressure heater group, the first medium-pressure heater and the deaerator, and the saturated water generated by the flash evaporation enters the second mixing heat exchanger, can be mixed with the condensed water, and then enters the heat storage tank again through the second booster pump; When the thermal power unit is loaded for peak regulation and the water pressure in the heat storage tank does not meet the flash evaporation conditions, the third control valve at the high-pressure water inlet of the flash tank is closed, and the fourth control valve at the high-pressure water inlet of the water-to-water heat exchanger is opened, so that the high-pressure and high-temperature water in the heat storage tank enters the water-to-water heat exchanger and exchanges heat with the incoming condensate. The low-temperature water after heat exchange enters the heat storage tank through the second booster pump, and the high-temperature water after heat exchange with the condensate is transported to the deaerator.

8. The method for operating the coupling system according to claim 7, characterized in that: The low-pressure heater group in the coupling system includes a first low-pressure heater, a second low-pressure heater, and a third low-pressure heater arranged along the flow direction of water, the first low-pressure heater, the second low-pressure heater, the third low-pressure heater, the first medium-pressure heater and the deaerator are all connected to the steam outlet of the flash evaporator, and the first low-pressure heater, the second low-pressure heater, the third low-pressure heater, the first medium-pressure heater and the steam inlet of the deaerator are respectively provided with a first steam supply valve, a second steam supply valve, a third steam supply valve, a fourth steam supply valve and a fifth steam supply valve, the feed water outlet of the water-to-water heat exchanger is connected to the inlet of the deaerator, and a hot water supply valve is provided at the feed water outlet of the water-to-water heat exchanger; the operation method also includes a frequency modulation method, and the frequency modulation method includes: When the thermal power unit participates in load reduction and frequency regulation, the hot re-steam flow through the hot re-extraction branch pipe and the cold re-steam flow in the cold re-extraction branch pipe are changed by adjusting the opening of the first control valve and the second control valve, so as to change the steam inlet amount of the intermediate pressure cylinder and the low pressure cylinder; When the thermal power unit participates in load increase and frequency modulation and uses the flash steam supply circuit, the steam supply from the flash evaporator to the first low-pressure heater, the second low-pressure heater, the third low-pressure heater, the second-stage medium-pressure regenerative heater and the deaerator is adjusted by adjusting the opening of the first steam supply valve, the second steam supply valve, the third steam supply valve, the fourth steam supply valve and the fifth steam supply valve to replace the unit's regenerative steam flow; When the thermal power unit participates in load increase and frequency regulation and uses the heat exchange hot water supply circuit, the amount of hot water sent to the deaerator by the water-to-water heat exchanger is adjusted by adjusting the opening of the hot water supply valve, replacing the unit's heat recovery extraction steam to heat the circulating condensate.

9. The method for operating the coupling system according to claim 7, characterized in that: When the thermal power unit increases load for peak load regulation, the flash evaporator is preferred to generate steam to replace the unit's heat recovery steam, so as to increase the amount of steam used to generate power and meet the unit's peak load regulation requirements; the water-to-water heat exchanger is secondly selected to heat the feed water to replace the unit's heat recovery steam, so as to increase the amount of steam used to generate power and meet the unit's peak load regulation requirements.

10. The method for operating the coupling system according to claim 8, characterized in that: When the thermal power unit is loaded and frequency adjusted, the flash evaporator is preferentially selected to generate steam to change the heat recovery steam flow of the replaced unit, so as to change the variable load rate of the unit and meet the unit frequency regulation requirements; the water-to-water heat exchanger is secondly selected to heat the feed water to change the heat recovery steam flow of the replaced unit, so as to change the variable load rate of the unit and meet the unit frequency regulation requirements.

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