Thermal power generating unit deep peak shaving system coupling solid medium heat storage and thermoelectric co-storage

Abstract

The invention discloses a thermal power generating unit deep peak shaving system coupling solid medium heat storage and thermoelectric co-storage. The thermal power generating unit deep peak shaving system comprises a thermal power generating unit and a solid medium heat storage unit. The thermal generator set comprises a boiler unit, a turboset and a generator; the solid medium heat storage unit comprises a cold solid medium tank, a cold solid medium heat exchanger, an electric heater, a hot solid medium tank and a hot solid medium heat exchanger; the low-temperature solid medium is suitable for exchanging heat with high-temperature steam of the boiler unit in the cold solid medium heat exchanger; the electric heater is suitable for electrically heating the solid heat storage medium; the low-temperature solid medium is subjected to steam heat exchange and / or electric heating to form a high-temperature solid medium; the high-temperature solid medium exchanges heat with low-temperature fluid of the turboset in the hot solid medium heat exchanger, and a low-temperature solid heat storage medium is formed after heat exchange; and low-temperature fluid of the turboset returns to the thermal power generating unit after heat exchange. Thermoelectric coupling heat storage is adopted, and the solid heat storage medium can be heated to a higher temperature in a mode of combining steam heat exchange and electric heating, so that the heat storage temperature and the energy quality of the solid medium heat storage unit are improved.

Description

Technical Field

[0001] This invention relates to the field of power system technology, and in particular to a deep peak-shaving system for thermal power units that couples solid-medium thermal storage with thermoelectric co-storage. Background Technology

[0002] Against the backdrop of global energy conservation, carbon reduction, and dwindling fossil fuel resources, the proportion of renewable energy in the power system is gradually increasing. However, the integration of electricity generated by renewable energy sources into the grid brings a series of problems, such as the volatility of solar and wind power, posing a severe challenge to the flexibility of thermal power units. Thermal power units urgently need to undertake the task of deep peak shaving. Energy storage technology is an effective technology to assist in achieving deep peak shaving. Under low electricity demand, excess electricity from the units is transferred to the energy storage system for storage, and then the energy is returned to the units under high electricity demand, achieving time-based energy transfer and flexible allocation. Thermal energy storage technology can store energy on a large scale and at low cost. Through direct heat exchange, the heat energy of high-temperature steam in thermal power units can be transferred to the thermal storage medium, improving energy efficiency compared to storing only electrical energy. Efficiency. Among them, solid particulate thermal storage media have advantages such as high thermal storage temperature, high thermal storage density, safety and non-toxicity, and low cost, making them suitable for large-scale thermal storage.

[0003] However, the storage temperature of the heat storage medium in current solid-medium thermal energy storage systems is limited by the steam temperature and must be lower than the steam temperature. This limited storage temperature restricts the ways to recover and utilize thermal energy. At the same time, due to the minimum steam intake of the steam turbine, only a portion of the steam can be extracted from the generator set for heat exchange, and the remaining steam must participate in power generation. The peak-shaving depth is still limited by the stable operation requirements of the generator set, resulting in a limited peak-shaving depth.

[0004] In related technologies, some solid-medium thermal energy storage systems use molten salt as the thermal energy storage medium, which requires the molten salt to remain in a liquid state. The thermal energy storage temperature is also limited by the melting point and boiling point of the molten salt material. If the temperature exceeds the limit, the molten salt will solidify or decompose, which may cause equipment blockage or decomposition to produce toxic substances. Therefore, the thermal energy storage temperature is limited and the deep peak shaving capability is insufficient.

[0005] Existing technologies are limited by the thermal storage temperature, and when returning heat energy to thermal power units, it can only be used to heat boiler feedwater or low-temperature steam, resulting in low energy efficiency. Summary of the Invention

[0006] This invention aims to at least solve one of the technical problems existing in the prior art. Therefore, one objective of this invention is to propose a deep peak-shaving system for thermal power units that couples solid-medium thermal storage with co-storage of thermoelectric power, aiming to solve the problems of limited thermal storage temperature and insufficient peak-shaving depth in existing thermal storage systems.

[0007] This invention proposes a deep peak-shaving system for thermal power units that couples solid-medium thermal energy storage with co-storage of thermal power. The deep peak-shaving system for thermal power units includes a thermal power generating unit and a solid-medium thermal energy storage unit. The thermal power generating unit includes a boiler unit, a steam turbine unit, and a generator. The boiler unit generates high-temperature steam, the steam turbine unit is adapted to convert steam energy into mechanical energy, and the generator is adapted to convert mechanical energy into electrical energy.

[0008] The solid-medium thermal energy storage unit includes a cold solid-medium tank, a cold solid-medium heat exchanger, an electric heater, a hot solid-medium tank, and a hot solid-medium heat exchanger. The cold solid-medium tank stores a low-temperature solid thermal energy storage medium. The connection between the cold solid-medium tank and the cold solid-medium heat exchanger allows the low-temperature solid thermal energy storage medium to exchange heat with high-temperature steam from the boiler unit in the cold solid-medium heat exchanger. The electric heater is connected to the cold solid-medium heat exchanger to electrically heat the solid thermal energy storage medium flowing through the cold solid-medium heat exchanger. The electric heater is also connected to a generator. After heat exchange and / or electric heating, the low-temperature solid thermal energy storage medium forms a high-temperature solid thermal energy storage medium. The hot solid-medium tank is connected to the cold solid-medium heat exchanger and is suitable for storing the high-temperature solid thermal energy storage medium. The hot solid-medium heat exchanger connects the hot solid-medium tank and the cold solid-medium tank. The high-temperature solid thermal energy storage medium exchanges heat with a low-temperature fluid from the turbine unit in the hot solid-medium heat exchanger, forming a low-temperature solid thermal energy storage medium which is then stored in the cold solid-medium tank. The low-temperature fluid from the turbine unit returns to the boiler unit or the turbine unit after heat exchange.

[0009] According to some embodiments of this application, a steam turbine unit includes a high-pressure turbine unit, an intermediate-pressure turbine unit, a low-pressure turbine unit, a condenser, a low-pressure heater unit, a deaerator, and a high-pressure heater unit. The steam inlet of the high-pressure turbine unit is connected to the main steam outlet of the boiler unit, and the steam outlet of the high-pressure turbine unit is connected to the steam inlet of the boiler unit. The main steam generated by the boiler unit enters the high-pressure turbine unit for the first round of work, and the steam after work is directly returned to the boiler unit for reheating. The steam inlet of the intermediate-pressure turbine unit is connected to the reheat steam outlet of the boiler unit, and the reheat steam generated by the boiler unit enters the intermediate-pressure turbine unit for the second round of work. The steam inlet of the low-pressure turbine unit is connected to the steam outlet of the intermediate-pressure turbine unit, and the steam after the second round of work enters the low-pressure turbine unit for the third round of work. The inlet of the condenser is connected to the steam outlet of the low-pressure turbine unit, and the steam after the third round of work enters the low-pressure turbine unit for the third round of work. The steam enters the condenser to generate condensate; the inlet of the low-pressure heater unit is connected to the steam outlet of the low-pressure cylinder unit of the turbine and the outlet of the condenser; the condensate enters the low-pressure heater unit, and the steam after the third round of work enters the low-pressure heater unit to preheat the condensate; the inlet of the deaerator is connected to the steam outlet of the low-pressure cylinder unit of the turbine and the outlet of the low-pressure heater unit; the preheated condensate enters the deaerator for deoxygenation, and the steam after the second round of work enters the deaerator to preheat the condensate; the inlet of the high-pressure heater unit is connected to the steam outlet of the high-pressure cylinder unit of the turbine, the steam outlet of the intermediate cylinder unit of the turbine, and the outlet of the deaerator, and the outlet of the high-pressure heater unit is connected to the feedwater inlet of the boiler unit; the deoxygenated condensate enters the high-pressure heater unit, the steam after the first round of work enters the high-pressure heater unit to preheat the condensate, and the steam after the second round of work enters the high-pressure heater unit to preheat the condensate; the preheated condensate returns to the boiler unit for reheating.

[0010] According to some embodiments of this application, three thermo-solid heat exchangers are provided, respectively configured as a first-stage thermo-solid heat exchanger, a second-stage thermo-solid heat exchanger, and a third-stage thermo-solid heat exchanger. The high-temperature solid heat storage medium sequentially passes through the high-temperature sides of the first-stage, second-stage, and third-stage thermo-solid heat exchangers for heat exchange. The low-temperature side inlet of the third-stage thermo-solid heat exchanger is connected to the outlet of the condenser, and the low-temperature side outlet is connected to the inlet of the deaerator. A portion of the condensate flows into the third-stage thermo-solid heat exchanger for heat exchange, and after being heated, flows into the deaerator. The low-temperature side inlet of the second-stage thermo-solid heat exchanger is connected to the outlet of the deaerator, and the low-temperature side outlet is connected to the high-pressure heater. The unit's outlet is connected; the deoxygenated condensate flows to the second-stage thermo-solid heat exchanger for heat exchange, and after being heated to the boiler feedwater temperature, part of it mixes with the boiler feedwater output from the high-pressure heater unit and enters the boiler unit for reheating; the low-temperature side inlet of the first-stage thermo-solid heat exchanger is connected to the low-temperature side outlet of the second-stage thermo-solid heat exchanger, and the low-temperature side outlet of the first-stage thermo-solid heat exchanger is connected to the main steam outlet of the boiler unit; part of the condensate after heat exchange in the second-stage thermo-solid heat exchanger flows to the first-stage thermo-solid heat exchanger for heat exchange, is heated and evaporated and superheated to the main steam temperature, and then mixes with the main steam output from the boiler unit and enters the high-pressure cylinder unit of the steam turbine for the first round of work.

[0011] According to some embodiments of this application, the high-temperature side inlet of the cold solid-medium heat exchanger is connected to the reheat steam outlet of the boiler unit through a heat exchange pipeline, and an extraction valve is provided on the heat exchange pipeline; the high-temperature side outlet of the cold solid-medium heat exchanger is connected to the steam inlet of the boiler unit.

[0012] According to some embodiments of this application, the steam turbine unit further includes a first feedwater pump and a second feedwater pump; the first feedwater pump is located at the outlet of the condenser; and the second feedwater pump is located at the outlet of the deaerator.

[0013] According to some embodiments of this application, the solid-medium thermal storage unit further includes a first induced draft fan and a second induced draft fan. The first induced draft fan is connected to the cold solid-medium tank to draw ambient air to fluidize the low-temperature solid thermal storage medium in the cold solid-medium tank and deliver it to the cold solid-medium heat exchanger. The second induced draft fan is connected to the hot solid-medium tank to fluidize the high-temperature solid thermal storage medium in the hot solid-medium tank and deliver it to the hot solid-medium heat exchanger.

[0014] According to some embodiments of this application, the solid-medium thermal energy storage unit further includes a hot gas-solid separator and a cold gas-solid separator. The hot gas-solid separator is disposed between the electric heater and the hot solid-medium tank to separate fluidizing gas and high-temperature solid thermal energy storage medium. The cold gas-solid separator is disposed between the hot solid-medium heat exchanger and the cold solid-medium tank to separate fluidizing gas and low-temperature solid thermal energy storage medium.

[0015] According to some embodiments of this application, the second induced draft fan is connected to the air outlet of the hot gas-solid separator to fluidize the high-temperature solid thermal storage medium by extracting the high-temperature gas separated by the hot gas-solid separator.

[0016] According to some embodiments of this application, the solid thermal storage medium is one or more of solid particulate materials such as sand, quartz sand, ceramic particles, and silicon carbide particles.

[0017] According to some embodiments of this application, the cold solid-medium heat exchanger is a fluidized bed heat exchanger, and the electric heater is a fluidized bed heat exchanger equipped with electric heating rods.

[0018] According to the deep peak-shaving system for thermal power units disclosed in this application, the heat of high-temperature steam in the thermal power unit is exchanged with a solid thermal storage medium. Excess electricity from the thermal power unit is then absorbed through electric heating, raising the solid thermal storage medium to a higher temperature. This improves the thermal storage temperature and energy quality of the solid thermal storage unit. The stored heat can be returned to the thermal power unit to heat low-temperature steam or boiler feedwater, improving energy efficiency. This application can increase thermal storage density, reduce the cost of the thermal storage system, and contribute to improving the energy utilization rate and economic benefits of deep peak shaving. This application adopts a thermoelectric coupled thermal storage method, which allows the thermal power unit to operate under the lowest stable operating conditions of the boiler unit and turbine unit while fully extracting the extra steam heat energy from the thermal power unit, avoiding energy loss caused by thermoelectric conversion. It can also absorb excess electricity generated by the thermal power unit under low load demand. Based on achieving the unit's inherent peak-shaving depth as much as possible, it further deepens the peak-shaving depth, improving the flexibility of the thermal power unit. This solves the problem of limited thermal storage temperature in existing thermal storage systems and helps to address the flexible allocation of multiple energy systems such as generators and renewable energy.

[0019] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0020] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which:

[0021] Figure 1 This is a schematic diagram of a deep peak-shaving system for thermal power units according to some embodiments of the present invention;

[0022] Figure 2 This is a schematic diagram of the working process of a deep peak shaving system for thermal power units according to some embodiments of the present invention.

[0023] Figure label:

[0024] 1. Cold solid medium tank; 2. Cold solid medium heat exchanger; 3. First induced draft fan; 4. Electric heater; 5. Hot gas-solid separator; 6. Hot solid medium tank; 7. Second induced draft fan; 8. First stage hot solid medium heat exchanger; 9. Second stage hot solid medium heat exchanger; 10. Third stage hot solid medium heat exchanger; 11. Cold gas-solid separator.

[0025] Boiler unit 12; High-pressure turbine unit 13; Intermediate-pressure turbine unit 14; Low-pressure turbine unit 15; Generator 16; Condenser 17; First feedwater pump 18; Low-pressure heater unit 19; Deaerator 20; Second feedwater pump 21; High-pressure heater unit 22;

[0026] Steam extraction valve 23; Steam return valve 24; Steam inlet valve 25; First return water pump 26; First pumping water pump 27; Second return water pump 28; Second pumping water pump 29. Detailed Implementation

[0027] Embodiments of the present invention are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.

[0028] The following is for reference. Figures 1-2 This invention describes a deep peak-shaving system for thermal power units that combines solid-medium thermal storage with thermoelectric co-storage according to an embodiment of the present invention.

[0029] This invention proposes a deep peak-shaving system for thermal power units that couples solid-medium thermal energy storage with co-storage of heat and electricity. The system includes a thermal power generating unit and a solid-medium thermal energy storage unit. The thermal power generating unit includes a boiler unit 12, a turbine unit, and a generator 16. The boiler unit 12 generates high-temperature steam, the turbine unit is adapted to convert steam energy into mechanical energy, and the generator 16 is adapted to convert mechanical energy into electrical energy. The solid-medium thermal energy storage unit includes a cold solid-medium tank 1, a cold solid-medium heat exchanger 2, an electric heater 4, a hot solid-medium tank 6, and a hot solid-medium heat exchanger. The cold solid-medium tank 1 stores a low-temperature solid thermal energy storage medium. The connection between the cold solid-medium tank 1 and the cold solid-medium heat exchanger 2 allows the low-temperature solid thermal energy storage medium to react with the steam from the boiler in the cold solid-medium heat exchanger 2. The boiler unit 12 has a high-temperature steam heat exchanger; an electric heater 4 is connected to a cold solid-medium heat exchanger 2 to electrically heat the solid heat storage medium flowing through the cold solid-medium heat exchanger 2; and the electric heater 4 is connected to a generator 16; the low-temperature solid heat storage medium is transformed into a high-temperature solid heat storage medium after heat exchange and / or electric heating; the hot solid-medium tank 6 is connected to the cold solid-medium heat exchanger 2 and is suitable for storing the high-temperature solid heat storage medium; the hot solid-medium heat exchanger connects the hot solid-medium tank 6 and the cold solid-medium tank 1, and the high-temperature solid heat storage medium exchanges heat with the low-temperature fluid from the turbine unit in the hot solid-medium heat exchanger, and after heat exchange, it forms a low-temperature solid heat storage medium and is stored in the cold solid-medium tank 1; the low-temperature fluid from the turbine unit returns to the boiler unit 12 or the turbine unit after heat exchange.

[0030] According to the deep peak-shaving system for thermal power units of this application, the solid thermal storage medium in the solid-medium thermal storage unit circulates to store and release heat. Specifically, the low-temperature solid thermal storage medium in the cold solid-medium tank 1 flows to the cold solid-medium heat exchanger 2, where it exchanges heat with the high-temperature steam from the boiler unit 12, absorbing the heat from the high-temperature steam for heat storage; after heat storage, it forms a high-temperature solid thermal storage medium stored in the hot solid-medium tank 6. The high-temperature solid thermal storage medium in the hot solid-medium tank 6 flows to the hot solid-medium heat exchanger, where it exchanges heat with the low-temperature fluid from the turbine unit, releasing heat to transfer heat to the low-temperature fluid and raising its temperature; after heat release, it forms a low-temperature solid thermal storage medium stored in the low solid-medium tank. Furthermore, in actual operation, when the intake air volume of the turbine unit reaches the lower limit of the intake air volume, the thermal power generating unit (hereinafter referred to as the thermal power unit) has no excess steam available for heat exchange of the solid thermal storage medium; to address this problem, the solid thermal storage unit is also equipped with an electric heater 4, which can use electrical energy to electrically heat the low-temperature solid thermal storage medium, raising its temperature to form a high-temperature thermal storage medium. The electric heater 4 is powered by the generator 16, and its power consumption is determined by the redundant power supply that exceeds the low load demand of the power grid.

[0031] According to the deep peak-shaving system for thermal power units disclosed in this application, by exchanging the heat of high-temperature steam in the thermal power unit with a solid thermal storage medium, and then absorbing the excess electricity from the thermal power unit through electric heating, the solid thermal storage medium can be heated to a higher temperature, thereby improving the thermal storage temperature and energy quality of the solid thermal storage unit. Simultaneously, the stored heat can be returned to the thermal power unit to heat low-temperature steam or boiler feedwater, improving energy efficiency. This application can increase thermal storage density, reduce the cost of the thermal storage system, and contribute to improving the energy utilization rate and economic benefits of deep peak shaving.

[0032] This application employs a thermoelectric coupled thermal energy storage method to extract and store steam heat exchange energy from thermal power units. This allows the thermal power unit to operate under the minimum stable operating conditions of the boiler unit and turbine unit while fully extracting additional steam heat energy from the unit, improving thermal energy storage efficiency, and avoiding energy losses caused by thermoelectric conversion. Losses; the use of electrothermal conversion for thermal energy storage can absorb excess electricity generated by thermal power units under low load demand; on the basis of achieving the peak shaving depth of the unit itself as much as possible, the peak shaving depth can be further deepened to improve the flexibility of thermal power units, which can solve the problem of limited thermal storage temperature of existing thermal energy storage systems and help solve the problem of flexible allocation of multiple energy systems such as generator units and renewable energy.

[0033] According to some embodiments of this application, the steam turbine unit includes a high-pressure turbine unit 13, an intermediate-pressure turbine unit 14, a low-pressure turbine unit 15, a condenser 17, a low-pressure heater unit 19, a deaerator 20, and a high-pressure heater unit 22; the steam inlet of the high-pressure turbine unit 13 is connected to the main steam outlet of the boiler unit 12, and the steam outlet of the high-pressure turbine unit 13 is connected to the steam inlet of the boiler unit 12; the main steam generated by the boiler unit 12 enters the high-pressure turbine unit 13 to perform the first round of work, and the steam after work... A portion of the steam is directly returned to boiler unit 12 for reheating; the steam inlet of the intermediate-pressure turbine unit 14 is connected to the reheat steam outlet of boiler unit 12, and the reheat steam generated by boiler unit 12 enters the intermediate-pressure turbine unit 14 for a second round of work; the steam inlet of the low-pressure turbine unit 15 is connected to the steam outlet of the intermediate-pressure turbine unit 14, and part of the steam after the second round of work enters the low-pressure turbine unit 15 for a third round of work; the inlet of the condenser 17 is connected to the steam outlet of the low-pressure turbine unit 15, and part of the steam after the third round of work enters the low-pressure turbine unit 15 for a third round of work; the steam inlet of the condenser 17 is connected to the steam outlet of the low-pressure turbine unit 15, and part of the steam after the third round of work enters the low-pressure turbine unit 15 for a third round of work. Steam enters condenser 17 to generate condensate; the inlet of low-pressure heater unit 19 is connected to the steam outlet of turbine low-pressure cylinder unit 15 and the outlet of condenser 17; condensate enters low-pressure heater unit 19, and steam after the third round of work enters low-pressure heater unit 19 to preheat condensate; the inlet of deaerator 20 is connected to the steam outlet of turbine low-pressure cylinder unit 15 and the outlet of low-pressure heater unit 19; condensate, after preheating, enters deaerator 20 for deoxygenation, and steam after the second round of work enters deaerator 20 to preheat condensate. The inlet of the high-pressure heater unit 22 is connected to the steam outlet of the high-pressure cylinder unit 13 of the steam turbine, the steam outlet of the intermediate-pressure cylinder unit 14 of the steam turbine, and the outlet of the deaerator 20. The outlet of the high-pressure heater unit 22 is connected to the feedwater inlet of the boiler unit 12. The deaerated condensate enters the high-pressure heater unit 22. The steam after the first round of work enters the high-pressure heater unit 22 to preheat the condensate. The steam after the second round of work enters the high-pressure heater unit 22 to preheat the condensate. The preheated condensate returns to the boiler unit 12 for reheating.

[0034] In this embodiment, when the thermal power unit is generating electricity, the boiler unit 12 heats the feedwater with coal to obtain high-temperature and high-pressure main steam. The main steam enters the high-pressure cylinder unit 13 of the turbine to complete the first round of expansion work. After the first round of work, part of the steam enters the high-pressure heater unit 22 to preheat the feedwater, and the other part returns to the reheater of the boiler unit 12 for reheating to obtain reheated steam. The reheated steam enters the intermediate-pressure cylinder unit 14 of the turbine to complete the second round of expansion work. After the second round of work, part of the steam enters the high-pressure heater unit 22. The steam is used to preheat the feedwater. Part of it enters the deaerator 20 to preheat the feedwater of the low-pressure heater unit 19, and the remaining part enters the turbine low-pressure cylinder unit 15 to complete the third round of work. Part of the steam after the third round of work enters the low-pressure heater unit 19 to preheat the condensate, and the other part is condensed into liquid water through the condenser 17. The liquid condensate is heated and pressurized through the low-pressure heater unit 19, deaerator 20, and high-pressure heater unit 22 before entering the boiler unit 12 for further heating, and then returns to the turbine unit to do work, completing the steam-water cycle.

[0035] The above embodiments illustrate the operation process of a thermal power generating unit without the addition of a solid-medium thermal storage unit for heat storage and release.

[0036] According to some embodiments of this application, three thermo-solid heat exchangers are provided, respectively configured as a first-stage thermo-solid heat exchanger 8, a second-stage thermo-solid heat exchanger 9, and a third-stage thermo-solid heat exchanger 10. The high-temperature solid heat storage medium sequentially passes through the high-temperature side of the first-stage thermo-solid heat exchanger 8, the second-stage thermo-solid heat exchanger 9, and the third-stage thermo-solid heat exchanger 10 for heat exchange. The low-temperature side inlet 10a of the third-stage thermo-solid heat exchanger 10 is connected to the outlet of the condenser 17, and the low-temperature side outlet 10b is connected to the inlet of the deaerator 20. A portion of the condensate flows into the third-stage thermo-solid heat exchanger 10 for heat exchange, and after being heated, flows into the deaerator 20. The low-temperature side inlet 9a of the second-stage thermo-solid heat exchanger 9 is connected to the outlet of the deaerator 20, and the low-temperature side outlet 9b is connected to the high-pressure... The outlet of heater unit 22 is connected; the deoxygenated condensate flows to the second-stage thermo-solid heat exchanger 9 for heat exchange, and after being heated to the boiler feedwater temperature, part of it mixes with the boiler feedwater output from the high-pressure heater unit 22 and enters the boiler unit 12 for reheating; the low-temperature side inlet 8a of the first-stage thermo-solid heat exchanger 8 is connected to the low-temperature side outlet 9b of the second-stage thermo-solid heat exchanger 9, and the low-temperature side outlet 8b of the first-stage thermo-solid heat exchanger 8 is connected to the main steam outlet of the boiler unit 12; part of the condensate after heat exchange in the second-stage thermo-solid heat exchanger 9 flows to the first-stage thermo-solid heat exchanger 8 for heat exchange, is heated and evaporated and superheated to the main steam temperature, and then mixes with the main steam output from the boiler unit 12 and enters the high-pressure cylinder unit 13 of the steam turbine for the first round of work.

[0037] In this embodiment, three thermo-solid heat exchangers are used to generate three-stage heat release from the cryogenic fluid of the thermal power unit, enabling cascaded utilization of thermal energy and contributing to higher efficiency. By heating the low-pressure and high-pressure feedwater of boiler unit 12 through the three-stage thermo-solid heat exchangers, the functions of the high-pressure heater unit 22 and low-pressure heater unit 19 of the thermal power unit are partially replaced. Furthermore, some main steam can be generated to directly participate in the power generation of the high-pressure turbine unit 13, which has advantages in increasing the power generation capacity and improving the unit's flexibility.

[0038] Specifically, the solid heat storage medium in the three-stage heat exchanger can be divided into high-temperature section thermo-solid medium, medium-temperature section thermo-solid medium, and low-temperature section thermo-solid medium according to their relative temperatures. The first two stages of heat exchange are used to heat the high-pressure feedwater of the thermal power unit. Specifically, a portion of feedwater is drawn from the outlet of the deaerator 20, passes through the second-stage thermo-solid medium heat exchanger 9, and after heat exchange using the medium-temperature section thermo-solid medium, a portion returns to the outlet of the high-pressure heater unit 22 of the thermal power unit to mix with the high-pressure boiler feedwater and enters the boiler unit 12 for further heating; the other portion continues to enter the first-stage thermo-solid medium heat exchanger 8, where it continues to evaporate and heat to the rated temperature of the main steam using the high-temperature section thermo-solid medium, mixes with the main steam, and enters the high-pressure turbine unit 13 of the thermal power unit to expand and perform work, thereby increasing the unit's power generation. The third-stage heat exchanger heats the low-pressure feedwater of the thermal power unit. Specifically, a portion of the condensate is extracted before the inlet of the low-pressure heater unit 19 of the turbine unit, passes through the third-stage thermo-solid heat exchanger 10, and after heat exchange in the low-temperature section, returns to the thermal power unit to mix with the feedwater at the outlet of the low-pressure heat exchanger unit before entering the deaerator 20. The second-stage thermo-solid heat exchanger 9 can partially replace the function of the high-pressure heater unit 22 of the thermal power unit; the third-stage thermo-solid heat exchanger 10 can partially replace the function of the low-pressure heater unit 19 of the thermal power unit.

[0039] According to some embodiments of this application, the high-temperature side inlet 2a of the cold solid-medium heat exchanger 2 is connected to the reheat steam outlet of the boiler unit 12 via a heat exchange pipeline, and an extraction valve 23 is installed on the heat exchange pipeline; the high-temperature side outlet 2b of the cold solid-medium heat exchanger 2 is connected to the steam inlet of the boiler unit 12. In this embodiment, the reheat steam has already done some work in the turbine unit, and its extraction has little impact on the main system. The solid-medium thermal energy storage unit can balance the load fluctuations of the turbine unit by extracting part of the reheat steam, which helps to maximize the value of thermal energy storage. Among them, the extraction valve 23 can provide the power to extract steam; in practical applications, when the power demand is low and the boiler load is excessive, the extraction valve 23 is used to extract part of the reheat steam for thermal energy storage.

[0040] According to some embodiments of this application, the turbine unit further includes a first feedwater pump 18 and a second feedwater pump 21; the first feedwater pump 18 is located at the outlet of the condenser 17; and the second feedwater pump 21 is located at the outlet of the deaerator 20. In this embodiment, the condensate is pumped by using feedwater pumps.

[0041] According to some embodiments of this application, the solid-medium thermal storage unit further includes a return steam valve 24, an inlet steam valve 25, a first return water pump 26, a first pumping water pump 27, a second return water pump 28, and a second pumping water pump 29. The return steam valve 24 is located between the high-temperature side outlet of the cold solid-medium heat exchanger 2 and the steam inlet of the boiler unit 12, returning the heat-exchanged steam to the reheater of the boiler unit 12 for further heating. The inlet steam valve 25 is located between the low-temperature side outlet of the first-stage solid-medium heat exchanger 8 and the main steam outlet of the boiler unit 12, mixing the steam superheated to the main steam temperature with the main steam and further sending it to the high-pressure cylinder unit 13 of the steam turbine for expansion and work. The first pump 27 is located between the second feedwater pump 21 and the low-temperature inlet of the second-stage thermo-solid heat exchanger 9, drawing a portion of the condensate before the inlet of the high-pressure heater unit 22 to the second-stage solid heat exchanger for heat exchange. The first return pump 26 is located between the low-temperature outlet of the second-stage thermo-solid heat exchanger 9 and the outlet of the high-pressure heater unit 22, mixing a portion of the condensate heated to the boiler feedwater temperature with the high-pressure boiler feedwater and returning it to the boiler unit 12. The second pump 29 is located between the first feedwater pump 18 and the low-temperature inlet of the third-stage thermo-solid heat exchanger 10, drawing a portion of the condensate before the inlet of the low-pressure heater to the third-stage solid heat exchanger for heat exchange. The second return pump 28 is located between the low-temperature outlet of the third-stage thermo-solid heat exchanger 10 and the outlet of the low-pressure heater unit 19, mixing the condensate heated to the outlet temperature of the low-pressure heater unit 19 with the low-pressure feedwater and sending it to the deaerator 20 for deoxygenation.

[0042] According to some embodiments of this application, the solid-medium thermal storage unit further includes a first induced draft fan 3 and a second induced draft fan 7. The first induced draft fan 3 is connected to the cold solid-medium tank 1 to draw ambient air, fluidize the low-temperature solid thermal storage medium in the cold solid-medium tank 1, and transport it to the cold solid-medium heat exchanger 2. The second induced draft fan 7 is connected to the hot solid-medium tank 6 to fluidize the high-temperature solid thermal storage medium in the hot solid-medium tank 6 and transport it to the hot solid-medium heat exchanger. In this embodiment, the solid thermal storage medium is fluidized by the induced draft fan, causing it to circulate in the solid-medium thermal storage unit for heat storage and release.

[0043] According to some embodiments of this application, the solid-medium thermal energy storage unit further includes a hot gas-solid separator 5 and a cold gas-solid separator 11. The hot gas-solid separator 5 is disposed between the electric heater 4 and the hot solid-medium tank 6 to separate the fluidizing gas and the high-temperature solid thermal energy storage medium. The cold gas-solid separator 11 is disposed between the hot solid-medium heat exchanger and the cold solid-medium tank 1 to separate the fluidizing gas and the low-temperature solid thermal energy storage medium. In this embodiment, the separation of the fluidizing gas and the solid thermal energy storage medium can be achieved by setting the gas-solid separator, so as to store the solid thermal energy storage medium.

[0044] According to some embodiments of this application, the second induced draft fan 7 is connected to the air outlet 5a of the hot gas-solid separator 5 to extract the high-temperature gas separated by the hot gas-solid separator 5 to fluidize the high-temperature solid thermal storage medium. In this embodiment, when the low-temperature solid thermal storage medium flows through the cold solid-solid heat exchanger 2, both the solid thermal storage medium and the fluidizing gas absorb heat and rise in temperature. The fluidizing gas separated in the hot gas-solid separator 5 has a higher temperature. When the high-temperature gas is used to fluidize the high-temperature solid thermal storage medium, the heat loss of the solid thermal storage medium can be reduced, and the energy efficiency can be improved.

[0045] According to some embodiments of this application, the solid thermal storage medium adopts one or more solid particulate materials such as sand, quartz sand, ceramic particles, and silicon carbide particles. In this embodiment, the solid thermal storage medium adopts one or more mixed solid particles such as sand, quartz sand, ceramic particles, and silicon carbide particles, which can stably store heat at around 1000℃. During the heat storage stage, it can be heated to 800℃-1000℃ using an electric heater 4, which is higher than the temperature limit of commonly used molten salt thermal storage media. This allows for higher heat storage temperatures and higher-grade thermal energy, which is beneficial for converting heat into higher-grade energy during heat release, thereby improving energy efficiency. efficiency.

[0046] According to some embodiments of this application, the cold solid-medium heat exchanger 2 is a fluidized bed heat exchanger, and the electric heater 4 is a fluidized bed heat exchanger equipped with electric heating rods. In this embodiment, the cold solid-medium heat exchanger 2 used for heat exchange between the low-temperature solid particle heat storage medium and reheat steam is a fluidized bed heat exchanger, and the electric heater 4 is a fluidized bed heat exchanger equipped with electric heating rods, which can improve the heat transfer coefficient of the solid particle heat storage medium and achieve higher heat exchange efficiency.

[0047] According to the thermal power unit deep peak shaving system of this application, such as Figure 2 As shown, the running method is as follows:

[0048] S1. Determine if there is redundancy in the power generation of thermal power units:

[0049] If the grid demand is less than the power generation of the thermal power units, then proceed to step S2;

[0050] If the grid demand is greater than or equal to the power generation of the thermal power unit, then the heat release stage begins, and step S3 is executed.

[0051] S2, Thermal Storage:

[0052] S2.1 Determine if the boiler load has reached the minimum load:

[0053] If the boiler load reaches the minimum load, then enter the thermal storage stage and execute step S2.2;

[0054] If the boiler load does not reach the minimum load, reduce the boiler load; after reducing the boiler load, reassess whether there is redundancy in the power generation of the thermal power unit.

[0055] If the grid demand is greater than or equal to the power generation of the thermal power unit, then heat storage will not be carried out, the boiler load will be increased, and the thermal power unit will operate normally.

[0056] If the grid demand is still less than the power generation of thermal power units, then step S2.1 is executed repeatedly.

[0057] S2.2 Reheat steam is extracted to heat the low-temperature solid thermal storage medium for thermal storage. During the reheat steam extraction and thermal storage process:

[0058] S2.3 Determine again whether there is redundancy in the power generation of the thermal power unit:

[0059] If the grid demand is greater than or equal to the power generation of thermal power units, then the thermal storage will be terminated.

[0060] If the grid demand is less than the power generation of the thermal power units, then proceed to the initial step S2.4;

[0061] S2.4 Determine whether the turbine unit's intake air volume has decreased to the minimum intake air volume:

[0062] If the turbine unit's intake air volume is less than or equal to the minimum intake air volume, then stop extracting reheat steam and proceed to step S2.5;

[0063] If the turbine unit's intake air volume is greater than the minimum intake air volume, then continue to extract reheat steam for heat storage, and repeat steps S2.2-S2.4.

[0064] S2.5 Utilize the redundant power of the thermal power unit to operate the electric heater 4 to electrically heat the low-temperature solid heat storage medium; during the electric heating process: cyclically execute steps S2.3-S2.5.

[0065] S3, Heat release:

[0066] S3.1 Extracts the high-temperature solid thermal storage medium and performs three-stage heat exchange. During the heat exchange process:

[0067] S3.2 Determine again whether there is redundancy in the power generation of the thermal power unit:

[0068] If the grid demand is less than or equal to the power generation of the thermal power unit, then heat release will end.

[0069] If the grid demand exceeds the power generation of the thermal power units, proceed to step S3.3.

[0070] S3.3 Determine whether the upper limit of solid thermal storage capacity has been reached:

[0071] If the upper limit of solid thermal storage capacity is not reached, heat exchange continues and steps S3.1-S33 are repeated.

[0072] If the upper limit of solid thermal storage capacity is reached, the boiler load is increased to improve the power generation of the thermal power unit, and steps S3.2-S3.3 are repeated.

[0073] According to the deep peak-shaving system for thermal power units of this application, under low grid load demand, the thermal storage stage begins operation. The first induced draft fan 3 extracts low-temperature solid particle thermal storage medium from the cold solid medium tank 1, which then enters the cold solid medium heat exchanger 2 for heat exchange. The heat source is a portion of the reheat steam extracted from the thermal power unit under conditions ensuring stable generator operation. The low-temperature solid particle thermal storage medium is heated to a certain temperature, and then further heated to a higher temperature using an electric heater 4. The mixture of the electrically heated high-temperature solid thermal storage medium and air undergoes gas-solid separation by a hot gas-solid separator 5. The high-temperature air is discharged from the air outlet 5a of the hot gas-solid separator 5 and can be further used for waste heat recovery; the high-temperature solid medium is discharged from the solid medium outlet of the hot gas-solid separator 5 and enters the thermal solid medium tank 6 for storage.

[0074] Under high grid load demand, the heat release process begins. The high-temperature solid heat storage medium is discharged from the thermal solid-solid medium tank 6 and fluidized by the ambient air drawn by the second induced draft fan 7 or the high-temperature air discharged from the air outlet 5a of the thermal gas-solid separator 5. It then enters three thermal solid-solid heat exchangers to complete three-stage heat exchange, achieving cascaded energy recovery. After completing the three-stage heat exchange, the gas-solid mixture undergoes gas-solid separation through the cold gas-solid separator 11. The air is discharged from the air outlet 11a of the cold gas-solid separator 11, while the low-temperature solid particulate heat storage medium is discharged from the solid outlet of the cold gas-solid separator 11 and returned to the cold solid-solid medium tank 1 for storage.

[0075] The solid-medium thermal energy storage unit of this application shall meet the conditions for stable system operation in both heat storage and heat release. The above-mentioned operation method controls heat storage and heat release by judging whether the power generation of the thermal power unit is redundant, whether the boiler load is excessive, and whether the turbine unit meets the minimum air intake requirements for stable operation, thereby ensuring efficient and stable system operation.

[0076] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0077] In the description of this invention, "first feature" and "second feature" may include one or more of the features.

[0078] In the description of this invention, "a plurality of" means two or more.

[0079] In the description of this invention, the first feature being "above" or "below" the second feature may include the first and second features being in direct contact, or it may include the first and second features not being in direct contact but being in contact through another feature between them.

[0080] In the description of this invention, the terms "above," "over," and "on top" for the first feature and the second feature include the first feature being directly above or diagonally above the second feature, or simply indicate that the first feature is at a higher horizontal level than the second feature.

[0081] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0082] Although embodiments of the invention have been shown and described, those skilled in the art will understand that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the claims and their equivalents.

Claims

1. A deep peak-shaving system for thermal power units that couples solid-medium thermal storage with thermoelectric co-storage, characterized in that, include: A thermal power generating unit, comprising a boiler unit, a steam turbine unit, and a generator, wherein the boiler unit generates high-temperature steam, the steam turbine unit is adapted to convert steam energy into mechanical energy, and the generator is adapted to convert mechanical energy into electrical energy; Solid-media thermal storage unit, the solid-media thermal storage unit comprising: A cold solid medium tank, wherein the cold solid medium tank stores a low-temperature solid heat storage medium; A cold solid-medium heat exchanger, wherein the cold solid-medium tank is connected to the cold solid-medium heat exchanger, and the low-temperature solid heat storage medium is adapted to exchange heat with high-temperature steam from the boiler unit in the cold solid-medium heat exchanger. An electric heater is connected to the cold solid-solid heat exchanger to electrically heat the solid heat storage medium flowing through the cold solid-solid heat exchanger; and the electric heater is connected to the generator. The low-temperature solid thermal storage medium is transformed into a high-temperature solid thermal storage medium after heat exchange and / or electric heating. A thermo-solid heat exchanger, the thermo-solid heat exchanger being connected to the cold-solid heat exchanger and being adapted to store the high-temperature solid heat storage medium; A thermo-solid heat exchanger connects the thermo-solid tank and the cold solid tank. The high-temperature solid heat storage medium exchanges heat with the low-temperature fluid from the turbine unit in the thermo-solid heat exchanger. After the heat exchange, it forms a low-temperature solid heat storage medium and is stored in the cold solid tank. The low-temperature fluid from the turbine unit returns to the boiler unit or the turbine unit after heat exchange.

2. The deep peak-shaving system for thermal power units coupled with solid-medium thermal storage and co-thermal power storage according to claim 1, characterized in that, The steam turbine unit includes: The steam turbine high-pressure cylinder unit has its steam inlet connected to the main steam outlet of the boiler unit, and its steam outlet connected to the steam inlet of the boiler unit. The main steam generated by the boiler unit enters the steam turbine high-pressure cylinder unit to perform the first round of work, and the steam after work is directly returned to the boiler unit for reheating. The intermediate pressure cylinder unit of the steam turbine is connected to the reheat steam outlet of the boiler unit, and the reheat steam generated by the boiler unit enters the intermediate pressure cylinder unit of the steam turbine for a second round of work. The steam turbine low-pressure cylinder unit has its steam inlet connected to the steam outlet of the steam turbine intermediate-pressure cylinder unit. After the second round of work, part of the steam enters the steam turbine low-pressure cylinder unit to perform the third round of work. The condenser has its inlet connected to the steam outlet of the low-pressure cylinder unit of the steam turbine. The steam after the third round of work enters the condenser to generate condensate. The low-pressure heater unit has its inlet connected to the steam outlet of the low-pressure cylinder unit of the steam turbine and the outlet of the condenser; the condensate enters the low-pressure heater unit, and part of the steam after the third round of work enters the low-pressure heater unit to preheat the condensate; The deaerator has its inlet connected to the steam outlet of the low-pressure cylinder unit of the steam turbine and the outlet of the low-pressure heater unit. The condensate is preheated and then enters the deaerator for deoxygenation. The steam after the second round of work enters the deaerator to preheat the condensate. The high-pressure heater unit has its inlet connected to the steam outlet of the high-pressure cylinder unit of the steam turbine, the steam outlet of the intermediate-pressure cylinder unit of the steam turbine, and the outlet of the deaerator. Its outlet is connected to the feedwater inlet of the boiler unit. The deaerated condensate enters the high-pressure heater unit. A portion of the steam after the first round of work enters the high-pressure heater unit to preheat the condensate. A portion of the steam after the second round of work enters the high-pressure heater unit to preheat the condensate. The preheated condensate is then returned to the boiler unit for reheating.

3. The deep peak-shaving system for thermal power units coupled with solid-medium thermal storage and co-thermal power storage according to claim 2, characterized in that, The thermo-solid heat exchanger is provided in three stages, respectively constructed as a first-stage thermo-solid heat exchanger, a second-stage thermo-solid heat exchanger, and a third-stage thermo-solid heat exchanger; the high-temperature solid heat storage medium sequentially passes through the high-temperature side of the first-stage, second-stage, and third-stage thermo-solid heat exchangers for heat exchange; wherein... The low-temperature side inlet of the third-stage thermo-solid heat exchanger is connected to the outlet of the condenser, and the low-temperature side outlet is connected to the inlet of the deaerator; part of the condensate flows into the third-stage thermo-solid heat exchanger for heat exchange, and after being heated, it flows into the deaerator; The low-temperature side inlet of the second-stage thermo-solid heat exchanger is connected to the outlet of the deaerator, and the low-temperature side outlet is connected to the outlet of the high-pressure heater unit. The deaerated condensate flows into the second-stage thermo-solid heat exchanger for heat exchange. After being heated to the boiler feedwater temperature, part of it mixes with the boiler feedwater output from the high-pressure heater unit and enters the boiler unit for reheating. The low-temperature inlet of the first-stage thermo-solid heat exchanger is connected to the low-temperature outlet of the second-stage thermo-solid heat exchanger, and the low-temperature outlet of the first-stage thermo-solid heat exchanger is connected to the main steam outlet of the boiler unit. After heat exchange in the second-stage thermo-solid heat exchanger, part of the condensate flows to the first-stage thermo-solid heat exchanger for heat exchange, is heated and evaporated and superheated to the main steam temperature, and then mixes with the main steam output from the boiler unit and enters the high-pressure cylinder unit of the steam turbine to perform the first round of work.

4. The deep peak-shaving system for thermal power units coupled with solid-medium thermal storage and co-thermal power storage according to claim 2, characterized in that, The high-temperature inlet of the cold solid-medium heat exchanger is connected to the reheat steam outlet of the boiler unit via a heat exchange pipeline, and an exhaust valve is installed on the heat exchange pipeline; the high-temperature outlet of the cold solid-medium heat exchanger is connected to the steam inlet of the boiler unit.

5. The deep peak-shaving system for thermal power units coupled with solid-medium thermal storage and co-thermal power storage according to claim 2, characterized in that, The turbine unit also includes: The first feedwater pump is located at the outlet of the condenser; The second water supply pump is located at the outlet of the deaerator.

6. The deep peak-shaving system for thermal power units coupled with solid-medium thermal storage and co-thermal power storage according to claim 1, characterized in that, The solid-medium thermal storage unit also includes: A first induced draft fan is connected to the cold solid medium tank to draw ambient air, fluidize the low-temperature solid heat storage medium in the cold solid medium tank, and deliver it to the cold solid medium heat exchanger. A second induced draft fan is connected to the thermo-solid medium tank to fluidize the high-temperature solid heat storage medium in the thermo-solid medium tank and transport it to the thermo-solid medium heat exchanger.

7. The deep peak-shaving system for thermal power units coupled with solid-medium thermal storage and co-thermal power storage according to claim 6, characterized in that, The solid-medium thermal storage unit also includes: A hot gas-solid separator is disposed between the electric heater and the hot solid medium tank to separate fluidizing gas and high-temperature solid heat storage medium. A cold gas-solid separator is disposed between the heat-solid medium heat exchanger and the cold solid medium tank to separate fluidizing gas and low-temperature solid heat storage medium.

8. The deep peak-shaving system for thermal power units coupled with solid-medium thermal storage and co-thermal power storage according to claim 7, characterized in that, The second induced draft fan is connected to the air outlet of the heat-gas-solid separator to extract the high-temperature gas separated by the heat-gas-solid separator and fluidize the high-temperature solid heat storage medium.

9. The deep peak-shaving system for thermal power units coupled with solid-medium thermal storage and co-thermal power storage according to claim 1, characterized in that, The solid thermal storage medium is one or more of the following solid particulate materials: sand, quartz sand, ceramic particles, silicon carbide particles, etc.

10. The deep peak-shaving system for thermal power units with coupled solid-medium thermal storage and co-thermal power storage according to claim 1, characterized in that, The cold solid-medium heat exchanger is a fluidized bed heat exchanger, and the electric heater is a fluidized bed heat exchanger equipped with electric heating rods.

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