A thermal power generation system and an operating method thereof

Abstract

The present invention discloses a thermal power generation system and its operation method. A first heat exchange unit and a heat storage system are provided on the basis of a thermal power generation system including a boiler, a steam turbine, a generator and a water supply system. The first heat exchange unit is provided inside or outside the boiler and is used to export the heat energy in the boiler to the heat storage system through the first heat exchange unit for storage and standby. This arrangement can greatly increase the deep peak-shaving capability of the thermal power generation system. The boiler has a minimum stable combustion load requirement. If the output still needs to be reduced, the excess heat energy generated in the boiler when it is at the minimum stable combustion requirement can be exported to the heat storage system for storage through the first heat exchange unit, thereby improving the deep peak-shaving capability of the thermal power generation system. It can also prevent the boiler from operating under conditions below the minimum stable combustion load requirement, improve the economic and safety of the unit operation, and solve the problem of energy waste in existing thermal power units at the minimum design conditions.

Description

Technical Field

[0001] The present invention belongs to the technical field of thermal power generation, and in particular relates to a thermal power generation system and an operation method thereof. Background Art

[0002] To achieve the goals of carbon neutrality and carbon peak, China has invested heavily in the development of renewable energy. However, renewable energy sources are generally highly volatile, posing significant challenges to the stable operation of power grids. Grids urgently need flexible power sources to improve their overall structure and maintain their security and stability.

[0003] In my country's existing power system, thermal power installed capacity is huge and its output is stable. Using it as a flexible peak-shaving power source can effectively promote the consumption of new energy and ensure the safe and stable operation of the power grid.

[0004] However, the operating economy of the thermal power generation system will decrease under low-load conditions. During deep peak regulation, the load output by the thermal power generation system to the power grid must be lower than the minimum design condition, and the boiler units in the thermal power generation system have a minimum stable combustion load requirement. Therefore, the heat energy generated by the boiler units under the minimum stable combustion load condition cannot be utilized, resulting in reduced efficiency of the boiler units in the thermal power generation system. Moreover, when the thermal power generation system operates under low-load conditions for a long time, the internal power field and temperature field of the boiler units will deviate greatly, affecting the life and safety of the equipment. In addition, the operation of the boiler units under low-load conditions will also increase the difficulty of operation and the workload. Summary of the Invention

[0005] In response to the technical problems existing in the prior art, the present invention provides a thermal power generation system and an operation method thereof, which can improve the deep peak-shaving capability of the existing thermal power generation system, while ensuring the safe and stable operation of the thermal power generation system and avoiding energy waste.

[0006] In order to solve the above problems, the technical solution of the present invention is:

[0007] A thermal power generation system of the present invention includes a boiler, a steam turbine, a generator, a water supply system, a heat storage system and a first heat exchange unit;

[0008] The water working medium outlet of the water supply system is connected to the water working medium inlet of the boiler through a pipeline, so as to provide water working medium to the boiler;

[0009] The steam outlet of the boiler is connected to the steam inlet of the steam turbine so that the steam is used to drive the steam turbine to drive the generator to generate electricity;

[0010] The first heat exchange unit is arranged inside or outside the boiler, and the heat storage system absorbs the heat energy in the boiler through the first heat exchange unit and stores it for future use.

[0011] In a thermal power generation system of the present invention, when the first heat exchange unit is disposed inside the boiler, the first heat exchange unit is a heat exchange tube disposed inside the boiler, a low-temperature heat storage medium outlet of the heat storage system is connected to a heat storage medium inlet of the heat exchange tube via a pipeline, and the heat storage medium outlet of the heat exchange tube is connected to a high-temperature heat storage medium inlet of the heat storage system via a pipeline;

[0012] When the first heat exchange unit is arranged outside the boiler, the first heat exchange unit is a heat exchanger arranged outside the boiler, the low-temperature heat storage medium outlet of the heat storage system is connected to the heat storage medium inlet of the heat exchanger through a pipeline, the heat storage medium outlet of the heat exchanger is connected to the high-temperature heat storage medium inlet of the heat storage system through a pipeline, the flue gas inlet of the heat exchanger is connected to the furnace of the boiler through a pipeline, and the flue gas outlet of the heat exchanger is connected to at least one of the furnace of the boiler, the atmosphere, or other external mechanisms through a pipeline.

[0013] A thermal power generation system according to the present invention includes a high-temperature heat exchange system; a cold reheat steam outlet of the steam turbine is connected to a steam inlet of the high-temperature heat exchange system via a pipeline, the steam outlet of the high-temperature heat exchange system is connected to a hot reheat steam inlet of the steam turbine via a pipeline, a high-temperature heat storage medium outlet of the heat storage system is connected to a heat storage medium inlet of the high-temperature heat exchange system via a pipeline, and the heat storage medium outlet of the high-temperature heat exchange system is connected to a low-temperature heat storage medium inlet of the heat storage system via a pipeline.

[0014] A thermal power generation system according to the present invention includes a low-temperature heat exchange system; a cold reheat steam outlet of the steam turbine is connected to a steam inlet of the low-temperature heat exchange system via a pipeline, and the steam outlet of the low-temperature heat exchange system is connected to a condensation inlet of a water supply system via a pipeline; a low-temperature heat storage medium outlet of the heat storage system is connected to a heat storage medium inlet of the low-temperature heat exchange system and a heat storage medium inlet of the first heat exchange unit via pipelines, respectively, and the heat storage medium outlet of the low-temperature heat exchange system is connected to the low-temperature heat storage medium inlet of the heat storage system via a pipeline.

[0015] In a thermal power generation system of the present invention, a high-temperature pump is provided at the outlet of the high-temperature heat storage medium of the heat storage system; and a low-temperature pump is provided at the outlet of the low-temperature heat storage medium of the heat storage system.

[0016] In a thermal power generation system of the present invention, a first steam-water valve is provided on the pipeline between the cold reheat steam outlet of the steam turbine and the steam inlet of the high-temperature heat exchange system;

[0017] A second steam-water valve is provided on the pipeline between the cold reheat steam outlet of the steam turbine and the steam inlet of the low-temperature heat exchange system.

[0018] In a thermal power generation system of the present invention, a third steam-water valve is provided on the pipeline between the steam outlet of the low-temperature heat exchange system and the condensation inlet of the water supply system.

[0019] In a thermal power generation system of the present invention, a first heat storage medium valve is provided on the pipeline between the low-temperature heat storage medium outlet of the heat storage system and the heat storage medium inlet of the first heat exchange unit;

[0020] A second heat storage medium valve is provided on the pipeline between the low-temperature heat storage medium outlet of the heat storage system and the heat storage medium inlet of the low-temperature heat exchange system.

[0021] A thermal power generation system of the present invention further includes a waste heat recovery device, which is arranged on a pipeline between the steam outlet of the low-temperature heat exchange system and the condensation inlet of the water supply system.

[0022] In a thermal power generation system of the present invention, the exhaust steam outlet of the steam turbine is connected to the condensation inlet of the water supply system through a pipeline, and a fourth steam-water valve is provided on the pipeline between the exhaust steam outlet of the steam turbine and the condensation inlet of the water supply system.

[0023] In a thermal power generation system of the present invention, the water supply system includes a condensation system and a water supply pump connected by a pipeline.

[0024] An operating method of the present invention is applied to any of the above-mentioned thermal power generation systems, and the operating mode is as follows:

[0025] Power generation mode: The heat storage system absorbs and stores the heat energy in the boiler through the first heat exchange unit; at the same time, the heat energy in the heat storage system is extracted and used to heat the cold reheat steam discharged from the steam turbine into hot reheat steam, which then enters the steam turbine to continue to perform work;

[0026] Energy storage mode: The heat storage system absorbs and stores the heat energy in the boiler through the first heat exchange unit; at the same time, the cold reheat steam discharged from the steam turbine is extracted through the heat exchanger and stored in the heat storage system for standby use;

[0027] Energy storage and power generation hybrid mode: the heat storage system absorbs and stores the heat energy in the boiler through the first heat exchange unit; the cold reheat steam discharged from the steam turbine is divided into two paths, one path uses the heat energy in the heat storage system to heat the hot reheat steam and enters the steam turbine to continue to do work, and the other path extracts the heat energy through the heat exchanger and stores it in the heat storage system.

[0028] Due to the adoption of the above technical solution, the present invention has the following advantages and positive effects compared with the prior art:

[0029] 1. One embodiment of the present invention further provides a first heat exchange unit and a heat storage system based on an existing thermal power generation system comprising a boiler, a steam turbine, a generator, and a water supply system. The first heat exchange unit is disposed inside or outside the boiler and is configured to transfer heat energy from the boiler to the heat storage system through the first heat exchange unit for storage for future use. This configuration can significantly increase the deep peak-shaving capability of the thermal power generation system. If the boiler has a minimum stable combustion load requirement and the thermal power generation system output still needs to be reduced, the excess heat energy generated by the boiler at the minimum stable combustion load requirement, which exceeds the grid demand, can be transferred to the heat storage system for storage via the first heat exchange unit. This improves the deep peak-shaving capability of the thermal power generation system and prevents the boiler from operating below the minimum stable combustion load requirement. When the thermal power generation system output needs to be increased, the heat energy in the heat storage system can be transferred to generate electricity. This accelerates the response time of the thermal power generation system to increase output, increases the peak output of the thermal power generation system, improves the economic and safety of the unit operation, and solves the problem of energy waste in existing thermal power units operating at their minimum design conditions.

[0030] 2. In one embodiment of the present invention, the first heat exchange unit can be modified using the original heat exchanger (such as the reheater) in the boiler, which requires little modification to the original unit process system, has low modification cost, short construction period, and is easy to implement; the newly added heat storage system has a long service life and low maintenance cost.

[0031] 3. In one embodiment of the present invention, the capacity of the high-temperature heat storage unit and the low-temperature heat storage unit can be designed according to the peak-shaving and energy storage requirements. The heat storage process and the heat release process are independent of each other, and the system operation is highly flexible. The power plant can customize the operation mode and energy storage solution according to its own peak-shaving needs.

[0032] 4. In one embodiment of the present invention, there is no loss of heat storage medium, the heat storage and exchange efficiency is as high as 99%, the overall efficiency of the system is high, the energy loss is small, and the economic benefits are good; the heat storage parameters are high. When the selected heat storage medium is molten salt, the molten salt heat storage temperature can reach above 550°C, and the exothermic steam parameters are high.

[0033] 5. In one embodiment of the present invention, the unit operation mode switching is simple and convenient, the peak load regulation speed is fast, and it can meet the regulation requirements of large fluctuations in the power system load; at the same time, it improves the start-stop speed and load variable capacity of the entire unit. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 This is a schematic diagram of a heat storage system suitable for deep peak regulation of existing thermal power units according to the present invention;

[0035] Figure 2 Schematic diagram of the power generation mode of the heat storage system of the present invention applicable to deep peak regulation of existing thermal power units;

[0036] Figure 3 It is a schematic diagram of the energy storage mode of the heat storage system suitable for deep peak regulation of existing thermal power units according to the present invention.

[0037] Explanation of reference numerals: 1: first heat exchange unit; 2: high-temperature storage tank; 3: high-temperature pump; 4: high-temperature heat exchange system; 5: low-temperature storage tank; 6: low-temperature pump; 7: low-temperature heat exchange system; 8-1: first medium pipeline; 8-2: second medium pipeline; 8-3-1: third medium pipeline; 8-3-2: sixth medium pipeline; 8-4: fourth medium pipeline; 8-5: fifth medium pipeline; 9-1: first heat storage medium valve; 9-2: second heat storage medium valve; 10-1 : First steam-water pipeline; 10-2: Second steam-water pipeline; 10-3: Third steam-water pipeline; 10-4: Fourth steam-water pipeline; 10-5: Fifth steam-water pipeline; 10-6: Reflux pipeline; 11-1: First steam-water valve; 11-2: Second steam-water valve; 11-3: Fourth steam-water valve; 11-4: Third steam-water valve; 12: Waste heat recovery device; 13: Condensation system; 14: Feed water pump; 15: Boiler; 16: Steam turbine; 17: Generator. DETAILED DESCRIPTION

[0038] The following is a further detailed description of a thermal power generation system and its operating method proposed by the present invention in conjunction with the accompanying drawings and specific embodiments. The advantages and features of the present invention will become more apparent from the following description and claims.

[0039] See Figures 1 to 3 In one embodiment, a thermal power generation system includes a boiler 15 , a steam turbine 16 , a generator 17 , a water supply system, a heat storage system, and a first heat exchange unit 1 .

[0040] The water outlet of the water supply system is connected to the water inlet of the boiler 15 via a return line 10-6, thereby supplying water to the boiler 15. The steam outlet of the boiler 15 is connected to the steam inlet of the steam turbine 16 via a first steam-water line 10-1, so that the steam drives the steam turbine 16 and drives the generator 17 to generate electricity.

[0041] The first heat exchange unit 1 is disposed inside or outside the boiler 15 , and the heat storage system absorbs heat energy in the boiler 15 through the first heat exchange unit 1 and stores it for future use.

[0042] This embodiment further incorporates a first heat exchange unit 1 and a heat storage system based on an existing thermal power generation system comprising a boiler 15, a steam turbine 16, a generator 17, and a water supply system. The first heat exchange unit 1 is disposed inside or outside the boiler and is used to transfer heat energy from the boiler 15 through the first heat exchange unit 1 to the heat storage system for storage for future use. This configuration significantly increases the deep peak-shaving capability of the thermal power generation system. While the boiler 15 has a minimum stable combustion load requirement, if the thermal power generation system's output still needs to be reduced, the excess heat energy generated when the boiler is operating at the minimum stable combustion requirement, which exceeds grid demand, can be transferred to the heat storage system for storage via the first heat exchange unit 1. This improves the deep peak-shaving capability of the thermal power generation system and prevents the boiler 15 from operating below the minimum stable combustion load requirement. When the thermal power generation system's output needs to be increased, the heat energy in the heat storage system can be transferred for power generation. This accelerates the response time of the thermal power generation system to increase output, increases the peak output of the thermal power generation system, improves the economic and safety of the unit's operation, and resolves the energy waste problem of existing thermal power units operating at their minimum design conditions.

[0043] The specific structure of the thermal power generation system of this embodiment is further described below:

[0044] In this embodiment, when the first heat exchange unit 1 is arranged inside the boiler 15, the first heat exchange unit 1 can be a heat exchange tube arranged in the boiler 15, and the low-temperature heat storage medium outlet of the heat storage system is connected to the heat storage medium inlet of the heat exchange tube through the fourth medium pipeline 8-4, and the heat storage medium outlet of the heat exchange tube is connected to the high-temperature heat storage medium inlet of the heat storage system through the first medium pipeline 8-1.

[0045] When the first heat exchange unit 1 is arranged outside the boiler 15, the first heat exchange unit 1 is a heat exchanger arranged outside the boiler 15, the low-temperature heat storage medium outlet of the heat storage system is connected to the heat storage medium inlet of the heat exchanger through the fourth medium pipeline 8-4, the heat storage medium outlet of the heat exchanger is connected to the high-temperature heat storage medium inlet of the heat storage system through the first medium pipeline 8-1, the flue gas inlet of the heat exchanger is connected to the furnace of the boiler through a pipeline, and the flue gas outlet of the heat exchanger is connected to at least one of the furnace of the boiler, the atmosphere or other external mechanisms through a pipeline.

[0046] Among them, the first heat exchange unit 1 can be modified using the original heat exchanger in the boiler (such as the reheater), which requires little modification to the original unit process system, has low modification cost, short construction period, and is easy to implement; the newly added heat storage system has a long service life and low maintenance cost.

[0047] In this embodiment, the thermal power generation system may include a high-temperature heat exchange system 4. The cold reheat steam outlet of the steam turbine 16 is connected to the steam inlet of the high-temperature heat exchange system 4 via the second steam-water pipeline 10-2 and its first branch. The steam outlet of the high-temperature heat exchange system 4 is connected to the hot reheat steam inlet of the steam turbine via the third steam-water pipeline 10-3. The high-temperature heat storage medium outlet of the heat storage system is connected to the heat storage medium inlet of the high-temperature heat exchange system 4 via the second medium pipeline 8-2. The heat storage medium outlet of the high-temperature heat exchange system 4 is connected to the low-temperature heat storage medium inlet of the heat storage system via the third medium pipeline 8-3-1.

[0048] The thermal power generation system may also include a low-temperature heat exchange system 7. The cold reheat steam outlet of the steam turbine is connected to the steam inlet of the low-temperature heat exchange system 7 via the second steam-water pipeline 10-2 and its second branch. The steam outlet of the low-temperature heat exchange system 7 is connected to the condenser inlet of the feedwater system via the fifth steam-water pipeline 10-5. The low-temperature heat storage medium outlet of the heat storage system is connected to the heat storage medium inlet of the low-temperature heat exchange system 7 via a main pipe and a fifth medium pipeline 8-5. The low-temperature heat storage medium outlet of the heat storage system is also connected to the heat storage medium inlet of the first heat exchange unit 1 via a main pipe and a fourth medium pipeline 8-4. The heat storage medium outlet of the low-temperature heat exchange system 7 is connected to the low-temperature heat storage medium inlet of the heat storage system via the sixth medium pipeline 8-3-2.

[0049] The high-temperature heat exchange system 4 and the low-temperature heat exchange system 7 may be a single heat exchanger or may be composed of multiple stages of heat exchangers, which is not specifically limited here.

[0050] In this embodiment, the second medium pipeline 8-2 is provided with a high-temperature pump 3 to pump the heat storage medium out of the high-temperature heat storage medium outlet of the heat storage system. The main pipe is provided with a low-temperature pump 6 to pump the heat storage medium out of the low-temperature heat storage medium outlet of the heat storage system.

[0051] In this embodiment, a first steam-water valve 11-1 is provided on the first branch. A second steam-water valve 11-2 is provided on the second branch. The exhaust steam outlet of the steam turbine 16 is connected to the condenser inlet of the feedwater system via a fourth steam-water pipe 10-4, and a fourth steam-water valve 11-3 is provided on the fourth steam-water pipe 10-4. A third steam-water valve 11-4 is provided on the fifth steam-water pipe 10-5. The opening and closing of the first and second steam-water valves 11-1 and 11-2 control whether the cold reheat steam flows to the high-temperature heat exchange system 4 and the low-temperature heat exchange system 7; the opening and closing of the fourth steam-water valve 11-3 controls whether the exhaust steam flows to the feedwater system for water circulation; and the third steam-water valve 11-4 controls whether the cold reheat steam, after releasing heat in the low-temperature heat exchange system 7, flows back to the feedwater system for water circulation.

[0052] The following is an explanation of the steam flow direction of a thermal power generation system: the steam generated in the boiler is first output to the high-pressure cylinder of the steam turbine 16 through the first steam-water pipe 10-1 to perform work, and forms cold reheat steam, which is output to the high-temperature heat exchange system 4 through the second steam-water pipe 10-2 to absorb heat, forming hot reheat steam, and then transported back to the medium and low-pressure cylinders of the steam turbine 16 through the third steam-water pipe 10-3 to perform work. The steam after doing work is transported to the condensation inlet of the water supply system through the fourth steam-water pipe 10-4, and then transported back to the boiler 15 from the water supply system through the return pipe 10-6 for the next cycle.

[0053] In this embodiment, a first heat storage medium valve 9-1 is provided on the fourth medium pipeline 8-4, and a second heat storage medium valve 9-2 is provided on the fifth medium pipeline 8-5. The opening and closing of these two heat storage medium valves can control the flow direction of the heat storage medium pumped out of the low-temperature heat storage medium outlet of the heat storage system, that is, whether it flows to the first heat exchange unit 1 or to the low-temperature heat exchange system 7.

[0054] In this embodiment, the heat storage system can be either a dual-tank system or a single-tank system. A dual-tank system refers to a system in which the low-temperature heat storage medium and the high-temperature heat storage medium are stored in the low-temperature storage tank 5 and the high-temperature storage tank 2, respectively. A single-tank system refers to a system in which the low-temperature heat storage medium and the high-temperature heat storage medium are stored in two separate compartments within the same tank. In this embodiment, the capacity of the high-temperature storage tank 2 and the low-temperature tank 5, or the two compartments storing the low-temperature heat storage medium and the high-temperature heat storage medium, can be designed based on peak shaving and energy storage requirements. The heat storage and release processes are independent of each other, providing high system operational flexibility. Power plants can customize their operating modes and energy storage solutions based on their peak shaving needs.

[0055] The following uses a dual-tank heat storage system as an example to illustrate the flow of heat storage medium in a thermal power generation system: After absorbing heat in the first heat exchange unit 1, the heat storage medium enters the high-temperature storage tank 2 via the first medium pipeline 8-1 for storage. When work is required, the high-temperature pump 3 provides power to output the heat storage medium from the high-temperature storage tank 2 via the second medium pipeline 8-2 to the high-temperature heat exchange system 4 for heat exchange with the cold reheat steam. After heat exchange, the heat storage medium is transported to the low-temperature storage tank 5 via the third medium pipeline 8-3-1. When the heat storage medium needs to enter the next cycle, the low-temperature pump 6 provides power to output the heat storage medium from the low-temperature storage tank 5 via the fourth medium pipeline 8-4 to the first heat exchange unit 1 to begin a new cycle.

[0056] In this embodiment, the thermal power generation system may also include a waste heat recovery device 12, which is arranged on the fifth steam-water pipeline 10-5, so as to further utilize the heat energy in the cold reheat steam that absorbs heat through the low-temperature heat exchange system 7. The waste heat recovery device 12 can supply heat to the outside according to user needs.

[0057] In this embodiment, the water supply system may specifically include a condensation system 13 and a water supply pump 14 provided on the return pipe 10 - 6 .

[0058] In this embodiment, the thermal storage system may also include an instrumentation thermal control system, which is signal-connected to each of the aforementioned valves and pumps. Specifically, the instrumentation thermal control system may include instruments such as pressure gauges, thermometers, and flow meters. Based on the instrumentation thermal control system and user needs, users can remotely control the system's switching between power generation and storage modes and adjust specific system parameters.

[0059] In this embodiment, the heat storage medium can specifically be molten salt. High-temperature storage tank 2 and low-temperature storage tank 5 serve as high-temperature molten salt storage tanks and low-temperature molten salt storage tanks, respectively. High-temperature pump 3 and low-temperature pump 6 serve as high-temperature molten salt pumps and low-temperature molten salt pumps, respectively. This embodiment achieves zero heat loss in the heat storage medium, achieving a heat storage and exchange efficiency of up to 99%, resulting in high overall system efficiency, minimal energy loss, and excellent economic benefits. The system also boasts high heat storage parameters. When molten salt is used as the heat storage medium, the molten salt heat storage temperature can reach over 550°C, and the exothermic steam parameters are high.

[0060] The deep peak regulation capability of the thermal power generation system of this embodiment is described below with some specific examples:

[0061] For example, taking the case where the power grid does not require electrical energy input from the thermal power generation system, the boiler 15 of the thermal power generation system of this embodiment is maintained at the minimum stable combustion load requirement. At this time, the heat generated in the boiler 15 can be transferred to the molten salt through the first heat exchange unit 1 and then completely exported to the heat storage system for storage and standby. The heat generated in the boiler 15 will not generate steam or drive the steam turbine, so that the thermal power generation system will not output electrical energy to the power grid. When the power required by the power grid is lower than the power generated by the boiler at the minimum stable combustion load requirement, the amount of heat energy exported by the first heat exchange unit 1 can be controlled by changing the molten salt flow rate, and the amount of steam generated by the residual heat in the boiler can be controlled, thereby controlling the power generation of the thermal power generation system, so that the power output of the thermal power generation system matches the power grid demand.

[0062] When the demand on the power grid increases rapidly and a quick response is required, the molten salt in the high-temperature storage tank 2 can be discharged and heat exchanged with the cold reheat steam discharged from the turbine 16 through the high-temperature heat exchange system 4 to form hot reheat steam, which enters the medium and low pressure cylinders of the turbine 16 to perform work, thereby accelerating the response speed of the thermal power generation system to the demand on the power grid.

[0063] Example 2

[0064] This embodiment provides an operating method, which is applied to the thermal power generation system in the above-mentioned embodiment 1, and specifically may include the following modes:

[0065] Power generation mode: The heat storage system absorbs and stores heat energy from the boiler 15 through the first heat exchange unit 1. At the same time, the heat energy in the heat storage system is extracted and used to heat the cold reheat steam discharged from the steam turbine 16 into hot reheat steam, which then enters the steam turbine 16 to continue generating power.

[0066] Energy storage mode: The heat storage system absorbs and stores heat energy from the boiler 15 through the first heat exchange unit 1. At the same time, the cold reheat steam discharged from the steam turbine 16 is extracted and stored in the heat storage system through the low-temperature heat exchange system 7 for standby use.

[0067] Energy storage and power generation hybrid mode: The heat storage system absorbs and stores the heat energy in the boiler 15 through the first heat exchange unit 1; the cold reheat steam discharged from the turbine 16 is divided into two paths, one path uses the heat energy in the heat storage system to heat the hot reheat steam and enters the steam turbine 16 to continue to do work, and the other path uses the low-temperature heat exchange system 7 to extract the heat energy and store it in the heat storage system.

[0068] The following takes the case where the heat storage medium is molten salt and the heat storage system includes a low-temperature storage tank 5 and a high-temperature storage tank 2 as an example to specifically describe the above modes:

[0069] Power generation mode: see Figure 2 The molten salt absorbs heat through the first heat exchange unit 1 and enters the high-temperature storage tank 2. The high-temperature pump 3 provides power to send the high-temperature molten salt into the high-temperature heat exchange system 4 to exchange heat with steam. The molten salt after heat exchange becomes low-temperature molten salt and enters the low-temperature storage tank 5. The low-temperature pump 6 provides power to send the low-temperature molten salt back to the boiler to absorb heat, completing the cycle of the molten salt system; at this time, the first heat storage medium valve 9-1 is in the open state, and the second heat storage medium valve 9-2 is in the closed state.

[0070] Synchronously, the water working medium is heated to the rated state in the boiler 15 and then enters the high-pressure cylinder of the steam turbine 16 to perform work, forming cold reheat steam that enters the high-temperature heat exchange system 4. The hot reheat steam output after heating enters the medium and low-pressure cylinders of the steam turbine 16 to continue to perform work; the exhaust steam discharged after work enters the condensation system 13, and then returns to the boiler 15 through the feed water pump 14 and the return pipe 10-6, completing the circulation of the steam-water system; at this time, the first steam-water valve 11-1 and the fourth steam-water valve 11-3 are in the open state, and the second steam-water valve 11-2 and the third steam-water valve 11-4 are in the closed state.

[0071] Energy storage mode: see Figure 3After the water working medium is heated to the rated state in the boiler, it enters the high-pressure cylinder of the steam turbine 16 to perform work. The cold reheated steam enters the low-temperature heat exchange system 7, exchanges heat with the low-temperature molten salt, recovers part of the heat through the waste heat recovery device 12, enters the condensation system 13, and then returns to the boiler through the feed water pump 14 and the return pipe 10-6, completing the circulation of the steam-water system; at this time, the first steam-water valve 11-1 and the fourth steam-water valve 11-3 are in the closed state, and the second steam-water valve 11-2 and the third steam-water valve 11-4 are in the open state.

[0072] Synchronously, power is provided by the cryogenic pump 6, a portion of the low-temperature molten salt enters the low-temperature heat exchange system 7 to exchange heat with the cold reheat steam, and the low-temperature molten salt after absorbing heat returns to the low-temperature storage tank 5 for low-temperature molten salt energy storage, and the other portion of the low-temperature molten salt returns to the boiler to absorb heat; at this time, the first heat storage medium valve 9-1 and the second heat storage medium valve 9-2 are both in the open state, and the flow rate can be adjusted according to the valve opening.

[0073] Energy storage and power generation hybrid mode: see Figure 1 After the water working medium is heated to the rated state in the boiler, it enters the high-pressure cylinder of the steam turbine 16 to perform work, and the cold reheat steam enters the high-temperature heat exchange system 4 and the low-temperature heat exchange system 7 respectively. After a part of the steam is heated, the hot reheat steam formed enters the medium and low-pressure cylinders of the steam turbine 16 to continue to perform work. At the same time, the remaining steam exchanges heat with the low-temperature molten salt and recovers part of the heat through the waste heat recovery device 12. The exhaust steam discharged from the steam turbine 16 is combined with the steam discharged from the preheating recovery device and enters the condensation system 13, and then returns to the boiler 15 through the feed water pump 14 and the return pipe 10-6, completing the circulation of the steam-water system; at this time, the first steam-water valve 11-1, the second steam-water valve 11-2, the fourth steam-water valve 11-3 and the third steam-water valve 11-4 are all in the open state, and the steam ratio is adjusted by the opening, thereby adjusting the system energy storage and power generation ratio.

[0074] Synchronously, the high-temperature molten salt in the high-temperature storage tank 22 is powered by the high-temperature pump 3 to send the high-temperature molten salt into the high-temperature heat exchange system 4 for heat exchange with steam. The molten salt after heat exchange becomes low-temperature molten salt and enters the low-temperature storage tank 5. The low-temperature molten salt pump provides power to send the low-temperature molten salt back to the boiler 15 and the low-temperature heat exchange system 7 for heat exchange and then returns to the low-temperature storage tank 5; at this time, the first heat storage medium valve 9-1 and the second heat storage medium valve 9-2 are both in the open state, and the molten salt ratio is adjusted by the opening, thereby adjusting the system energy storage and power generation ratio.

[0075] The embodiments of the present invention have been described in detail above with reference to the accompanying drawings, but the present invention is not limited to the above embodiments. Even if various changes are made to the present invention, if these changes fall within the scope of the claims of the present invention and their equivalents, they still fall within the scope of protection of the present invention.

Claims

1. A thermal power generation system, characterized in that: It includes a boiler, a steam turbine, a generator, a water supply system, a heat storage system, a high-temperature heat exchange system and a first heat exchange unit; The water working medium outlet of the water supply system is connected to the water working medium inlet of the boiler through a pipeline, so as to provide water working medium to the boiler; The steam outlet of the boiler is connected to the steam inlet of the steam turbine so that the steam is used to drive the steam turbine to drive the generator to generate electricity; The cold reheat steam outlet of the steam turbine is connected to the steam inlet of the high-temperature heat exchange system through a pipeline, the steam outlet of the high-temperature heat exchange system is connected to the hot reheat steam inlet of the steam turbine through a pipeline, the high-temperature heat storage medium outlet of the heat storage system is connected to the heat storage medium inlet of the high-temperature heat exchange system through a pipeline, and the heat storage medium outlet of the high-temperature heat exchange system is connected to the low-temperature heat storage medium inlet of the heat storage system through a pipeline; The first heat exchange unit is arranged inside or outside the boiler, and the low-temperature heat storage medium of the heat storage system absorbs the heat energy in the boiler through the first heat exchange unit to obtain high-temperature heat storage medium and stores it for standby; wherein the heat storage medium is molten salt.

2. A thermal power generation system according to claim 1, characterized in that: When the first heat exchange unit is arranged inside the boiler, the first heat exchange unit is a heat exchange tube arranged in the boiler, the low-temperature heat storage medium outlet of the heat storage system is connected to the heat storage medium inlet of the heat exchange tube through a pipeline, and the heat storage medium outlet of the heat exchange tube is connected to the high-temperature heat storage medium inlet of the heat storage system through a pipeline; When the first heat exchange unit is arranged outside the boiler, the first heat exchange unit is a heat exchanger arranged outside the boiler, the low-temperature heat storage medium outlet of the heat storage system is connected to the heat storage medium inlet of the heat exchanger through a pipeline, the heat storage medium outlet of the heat exchanger is connected to the high-temperature heat storage medium inlet of the heat storage system through a pipeline, the flue gas inlet of the heat exchanger is connected to the furnace of the boiler through a pipeline, and the flue gas outlet of the heat exchanger is connected to at least one of the furnace of the boiler, the atmosphere, or other external mechanisms through a pipeline.

3. A thermal power generation system according to claim 1, characterized in that: It includes a low-temperature heat exchange system; the cold reheat steam exhaust port of the steam turbine is connected to the steam inlet of the low-temperature heat exchange system through a pipeline, and the steam outlet of the low-temperature heat exchange system is connected to the condensation inlet of the water supply system through a pipeline; the low-temperature heat storage medium outlet of the heat storage system is connected to the heat storage medium inlet of the low-temperature heat exchange system and the heat storage medium inlet of the first heat exchange unit through pipelines, respectively, and the heat storage medium outlet of the low-temperature heat exchange system is connected to the low-temperature heat storage medium inlet of the heat storage system through a pipeline.

4. A thermal power generation system according to claim 3, characterized in that: A high-temperature pump is provided at the outlet of the high-temperature heat storage medium of the heat storage system; a low-temperature pump is provided at the outlet of the low-temperature heat storage medium of the heat storage system.

5. A thermal power generation system according to claim 3, characterized in that: A first steam-water valve is provided on the pipeline between the cold reheat steam outlet of the steam turbine and the steam inlet of the high-temperature heat exchange system; A second steam-water valve is provided on the pipeline between the cold reheat steam outlet of the steam turbine and the steam inlet of the low-temperature heat exchange system.

6. A thermal power generation system according to claim 3, characterized in that: A third steam-water valve is provided on the pipeline between the steam outlet of the low-temperature heat exchange system and the condensation inlet of the water supply system.

7. A thermal power generation system according to claim 3, characterized in that: A first heat storage medium valve is provided on the pipeline between the low-temperature heat storage medium outlet of the heat storage system and the heat storage medium inlet of the first heat exchange unit; A second heat storage medium valve is provided on the pipeline between the low-temperature heat storage medium outlet of the heat storage system and the heat storage medium inlet of the low-temperature heat exchange system.

8. A thermal power generation system according to claim 3, characterized in that: It also includes a waste heat recovery device, which is arranged on the pipeline between the steam outlet of the low-temperature heat exchange system and the condensation inlet of the water supply system.

9. A thermal power generation system according to claim 1, characterized in that: The exhaust steam outlet of the steam turbine is connected to the condensation inlet of the water supply system through a pipeline, and a fourth steam-water valve is provided on the pipeline between the exhaust steam outlet of the steam turbine and the condensation inlet of the water supply system.

10. A thermal power generation system according to claim 1, characterized in that: The water supply system includes a condensation system and a water supply pump connected by a pipeline.

11. An operating method, characterized in that: Applied to the thermal power generation system according to any one of claims 1 to 10, the operation mode is as follows: Power generation mode: The heat storage system absorbs and stores the heat energy in the boiler through the first heat exchange unit; at the same time, the heat energy in the heat storage system is extracted and used to heat the cold reheat steam discharged from the steam turbine into hot reheat steam, which then enters the steam turbine to continue to perform work; Energy storage mode: The heat storage system absorbs and stores the heat energy in the boiler through the first heat exchange unit; at the same time, the cold reheat steam discharged from the steam turbine is extracted through the heat exchanger and stored in the heat storage system for standby use; Energy storage and power generation hybrid mode: the heat storage system absorbs and stores the heat energy in the boiler through the first heat exchange unit; the cold reheat steam discharged from the steam turbine is divided into two paths, one path uses the heat energy in the heat storage system to heat the hot reheat steam and enters the steam turbine to continue to do work, and the other path extracts the heat energy through the heat exchanger and stores it in the heat storage system.

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