Thermal battery energy storage system coupled with boiler power generation system and operation method

Abstract

The invention relates to a thermal battery energy storage system coupled with a boiler power generation system and an operation method, the thermal battery energy storage system comprises a heat pump module, a fused salt energy storage module and a steam module, the heat pump module comprises a compressor, a fused salt-working medium heat exchanger, an expansion machine and a steam-working medium heat exchanger; the fused salt energy storage module comprises a cold salt tank, a fused salt conveying device, a main steam-fused salt heat exchanger, a fused salt-working medium heat exchanger, a hot salt tank and an energy release heat exchanger; the steam module comprises a power generation loop, a heat release loop and a heat absorption loop, the power generation loop comprises a low-pressure heater, a deaerator, a first water pump, a high-pressure heater, a boiler and a steam turbine, and the heat release loop comprises the boiler, a main steam isolation door, a main steam-molten salt heat exchanger, a steam-working medium heat exchanger, a second water pump and a water return isolation door. The heat absorption loop is connected between the steam turbine and the deaerator and comprises a main water supply isolation door, a third water pump and an energy release heat exchanger. The system has good peak regulation and peak resistance, and meets the construction requirements of the current novel power system.

Description

Technical Field

[0001] This invention relates to the field of thermal power generation technology, and in particular to a thermal battery energy storage system and its operation method coupled to a boiler power generation system. Background Technology

[0002] As the proportion of new energy sources in the power grid continues to increase, the role of coal-fired power generating units in the power grid has begun to shift from providing stable power to "peak shaving and valley filling" (peak regulation), and will eventually only undertake the peak regulation task of the power grid. New energy sources as the main power source, with coal-fired power providing support and security, are the main characteristics of the new power system. The construction of the new power system requires boiler power generation systems to provide more regulation capabilities.

[0003] Existing electric thermal energy storage technologies mainly use electric heaters to directly heat the storage medium. Due to the limitations of electrothermal conversion efficiency and heat loss, the overall energy storage system is not very efficient, resulting in poor peak-shaving and peak-loading capabilities of the boiler power generation system. Summary of the Invention

[0004] The first objective of this invention is to provide a thermal battery energy storage system coupled to a boiler power generation system, so as to improve the regulation capability of the boiler power generation system and enhance its peak shaving and peak load capacity.

[0005] The second objective of this invention is to provide an operating method for the thermal battery energy storage system of the above-mentioned coupled boiler power generation system.

[0006] To achieve the above objectives, the present invention provides the following technical solution:

[0007] In a first aspect of this application, a thermal battery energy storage system coupled to a boiler power generation system is provided, comprising:

[0008] The heat pump module includes a compressor, a working fluid pipeline of a molten salt-working fluid heat exchanger, an expander, and a working fluid pipeline of a steam-working fluid heat exchanger, which are connected in series to form a working fluid loop.

[0009] The molten salt energy storage module includes a cold salt tank, a molten salt conveying device, a molten salt pipeline of a main steam-molten salt heat exchanger, a molten salt pipeline of a molten salt-working fluid heat exchanger, a hot salt tank, and a molten salt pipeline of an energy release heat exchanger, which are connected in series to form a molten salt circuit.

[0010] The steam module includes a power generation circuit, a heat release circuit, and a heat absorption circuit. The power generation circuit consists of a low-pressure heater, a deaerator, a first water pump, a high-pressure heater, a superheated steam pipe of the boiler, a high-pressure cylinder of the turbine, a reheat steam pipe of the boiler, and an intermediate-low-pressure cylinder of the turbine connected in series. The heat release circuit consists of a superheated steam pipe of the boiler, a main steam isolation valve, a main steam pipe of the main steam-molten salt heat exchanger, a steam pipe of the steam-working fluid heat exchanger, a second water pump, and a return water isolation valve connected in series. The heat absorption circuit is connected between the high-pressure cylinder and the intermediate-low-pressure cylinder of the turbine and the deaerator, and consists of a main feedwater isolation valve, a third water pump, and a water pipe of the heat release heat exchanger connected in series.

[0011] In one possible implementation, the energy-releasing heat exchanger includes at least a superheater for heating steam from future water to a superheated state.

[0012] In one possible implementation, the energy-releasing heat exchanger includes a preheater, a phase change heat exchanger, and a superheater connected in series.

[0013] In one possible implementation, the molten salt pipes of the superheater, the molten salt pipes of the phase change heat exchanger, and the molten salt pipes of the preheater are connected in series along the molten salt conveying direction.

[0014] In one possible implementation, the water pipes of the preheater, the water pipes of the phase change heat exchanger, and the water pipes of the superheater are connected in series along the water transport direction.

[0015] In one possible implementation, the heat absorption circuit further includes a steam system isolation door connected in series between the water pipe of the superheater and the high-pressure cylinder or medium-low-pressure cylinder of the steam turbine, the steam system isolation door being used to prevent steam in the steam turbine from flowing into the heat absorption circuit.

[0016] In one possible implementation, the molten salt conveying device includes a cold salt pump and a hot salt pump, wherein the cold salt pump is disposed downstream of the cold salt tank along the molten salt conveying direction, and the hot salt pump is disposed downstream of the hot salt tank along the molten salt conveying direction.

[0017] In one possible implementation, the boiler is one of a coal-fired boiler, a gas-fired boiler, an oil-fired boiler, and a waste incinerator.

[0018] In one possible implementation, the steam turbine is electrically connected to the compressor via a power generation module.

[0019] As can be seen from the above technical solutions, the thermal battery energy storage system of the coupled boiler power generation system provided by the present invention includes a heat pump module, a molten salt energy storage module, and a steam module. The heat pump module includes a compressor, a working fluid pipeline of a molten salt-working fluid heat exchanger, an expander, and a working fluid pipeline of a steam-working fluid heat exchanger, all connected in series to form a working fluid loop. The molten salt energy storage module includes a cold salt tank, a molten salt conveying device, a molten salt pipeline of a main steam-molten salt heat exchanger, a molten salt pipeline of a molten salt-working fluid heat exchanger, a hot salt tank, and a molten salt pipeline of an energy release heat exchanger, all connected in series to form a molten salt loop. The steam module includes a power generation loop, a heat release loop, and a steam storage loop. The power generation circuit consists of a low-pressure heater, a deaerator, a first water pump, a high-pressure heater, a superheated steam pipe of the boiler, a high-pressure cylinder of the turbine, a reheat steam pipe of the boiler, and a medium- and low-pressure cylinder of the turbine connected in series. The heat release circuit consists of a superheated steam pipe of the boiler, a main steam isolation valve, a main steam pipe of the main steam-molten salt heat exchanger, a steam pipe of the steam-working fluid heat exchanger, a second water pump, and a return water isolation valve connected in series. The heat absorption circuit is connected between the high-pressure cylinder and the medium- and low-pressure cylinder of the turbine and the deaerator, and consists of a main feedwater isolation valve, a third water pump, and a water pipe of the heat release heat exchanger connected in series.

[0020] The thermal battery energy storage system of the above-mentioned coupled boiler power generation system has three working modes: power generation mode, peak shaving mode and peak mode. In power generation mode, the main steam isolation door, return water isolation door and main feed water isolation door are all closed, and only the power generation circuit is running. The boiler burns fuel to heat the feed water into steam and sends it into the high-pressure cylinder and medium and low-pressure cylinder of the steam turbine to drive the steam turbine to generate electricity.

[0021] In peak shaving mode, the main steam isolation valve and return water isolation valve are opened, while the main feedwater isolation valve is closed. The power generation circuit, heat release circuit, heat pump module, and molten salt energy storage module operate simultaneously. A portion of the steam from the power generation circuit enters the heat release circuit. The steam in the heat release circuit preheats the molten salt output from the cold salt tank of the molten salt energy storage module in the main steam-molten salt heat exchanger. The cooled steam then enters the steam-working fluid heat exchanger to heat the working fluid of the heat pump module. The working fluid heated by the steam is further compressed to a high temperature and high pressure state by the compressor. Then, the high temperature and high pressure working fluid enters the molten salt-working fluid heat exchanger to heat the preheated molten salt. After that, the working fluid enters the expander to expand. Subsequently, the working fluid continuously circulates in the steam-working fluid heat exchanger, compressor, molten salt-working fluid heat exchanger, and expander. The heated molten salt is stored in the hot salt tank, thus completing the peak shaving energy storage.

[0022] In peak mode, the main steam isolation door and return water isolation door are closed, the main feedwater isolation door is open, and the power generation circuit, heat absorption circuit, and molten salt energy storage module are in operation. The heat absorption circuit draws water from the deaerator of the power generation circuit, that is, it draws water from the regenerating part of the power generation circuit and sends the water into the water pipe of the energy release heat exchanger. At the same time, the molten salt energy storage module sends the hot molten salt in the hot salt tank into the molten salt pipe of the energy release heat exchanger. The water absorbs heat from the hot molten salt to form superheated steam and then sends it back to the high-pressure cylinder of the turbine in the power generation circuit to complete the release of stored energy.

[0023] It is evident that during the peak-shaving energy storage phase, the heat pump module of the coupled boiler power generation system of this application can directly consume electrical energy and simultaneously absorb the heat from the main steam output from the boiler's superheated steam pipeline, thereby improving peak-shaving capacity. The heat release circuit directly extracts the main steam from the boiler's superheated steam pipeline. The extracted main steam has a high grade, and the heat stored after absorption by the heat pump module and molten salt energy storage module also has a high grade. Since the main steam is extracted, the work done by the steam turbine is reduced, further improving the peak-shaving capacity. During the peak phase, the heat stored in the molten salt can be used to heat the boiler return water, generating steam that returns to the steam turbine, increasing the power generation of the boiler generator set, improving the peak-shaving capacity of the boiler power generation system, and meeting the construction requirements of the current new power system.

[0024] In a second aspect of this application, a method for operating a thermal battery energy storage system coupled to a boiler power generation system as described in the first aspect and its possible implementations is provided, comprising:

[0025] In power generation mode, the main steam isolation valve, return water isolation valve, and main feedwater isolation valve are closed, and the power generation circuit operates.

[0026] In peak shaving mode, the main steam isolation door and the return water isolation door are opened, the main feedwater isolation door is closed, and the power generation circuit, the heat release circuit, the heat pump module and the molten salt energy storage module are in operation. The heat release circuit draws steam from the power generation circuit and heats the molten salt together with the heat pump module, and stores it in the hot salt tank.

[0027] In peak mode, the main steam isolation valve and return water isolation valve are closed, and the main feedwater isolation valve is opened. The power generation circuit, heat absorption circuit, and molten salt energy storage module are in operation. Part of the feedwater in the power generation circuit enters the heat absorption circuit and is heated into high-temperature and high-pressure steam by the heat exchanger of the molten salt energy storage module. The steam is then returned to the power generation circuit.

[0028] Since this operating method employs the thermal battery energy storage system of the coupled boiler power generation system in the first aspect and its possible implementations, this operating method should have the same beneficial effects as the thermal battery energy storage system of the coupled boiler power generation system described above, and will not be elaborated further here. Attached Figure Description

[0029] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0030] Figure 1 This is a schematic diagram of the thermal battery energy storage system of the coupled boiler power generation system provided in an embodiment of the present invention.

[0031] In the picture:

[0032] 1 is the compressor; 2 is the molten salt-working fluid heat exchanger; 3 is the expander; 4 is the steam-working fluid heat exchanger; 5 is the cold salt tank; 6 is the cold salt pump; 7 is the main steam-molten salt heat exchanger; 8 is the hot salt tank; 9 is the hot salt pump; 10 is the energy release heat exchanger; 1001 is the preheater; 1002 is the phase change heat exchanger; 1003 is the superheater; 11 is the low-pressure heater; 12 is the deaerator; 13 is the first water pump; 14 is the high-pressure heater; 15 is the boiler; 16 is the high-pressure cylinder of the steam turbine; 17 is the medium and low-pressure cylinder of the steam turbine; 18 is the main steam isolation valve; 19 is the second water pump; 20 is the return water isolation valve; 21 is the main feedwater isolation valve; 22 is the third water pump; 23 is the steam system isolation valve.

[0033] A is the working fluid circuit; B is the molten salt circuit; C is the power generation circuit; D is the heat release circuit; E is the heat absorption circuit. Detailed Implementation

[0034] One of the core aspects of this invention is to provide a thermal battery energy storage system coupled to a boiler power generation system. The structural design of this thermal battery energy storage system coupled to the boiler power generation system enables it to improve the regulation capability of the boiler power generation system and enhance its peak shaving and peak load capacity.

[0035] Another core aspect of this invention is to provide an operation method for a thermal battery energy storage system based on the aforementioned coupled boiler power generation system.

[0036] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0037] This application provides a thermal battery energy storage system coupled to a boiler power generation system, such as... Figure 1As shown, the thermal battery energy storage system of the coupled boiler power generation system includes a heat pump module, a molten salt energy storage module, and a steam module.

[0038] The heat pump module includes a compressor 1, a working fluid pipe for a molten salt-working fluid heat exchanger 2, an expander 3, and a working fluid pipe for a steam-working fluid heat exchanger 4, which are connected in series to form a working fluid circuit A. The working fluid used in the heat pump module includes, but is not limited to, carbon dioxide (CO2) and air. Of course, other working fluids can also be used, and no limitation is made here.

[0039] When the heat pump module is running, the compressor 1 pressurizes the working fluid to form a high-temperature and high-pressure working fluid, which is then sent into the working fluid pipeline of the molten salt-working fluid heat exchanger 2. The high-temperature and high-pressure working fluid heats the molten salt in the molten salt-working fluid heat exchanger 2. After the working fluid is cooled, it enters the expander 3 and expands before entering the working fluid pipeline of the steam-working fluid heat exchanger 4. There, it exchanges heat with high-temperature steam, which increases the temperature of the working fluid. The working fluid circulates continuously in the compressor 1, the working fluid pipeline of the molten salt-working fluid heat exchanger 2, the expander 3, and the working fluid pipeline of the steam-working fluid heat exchanger 4.

[0040] Molten salt can be matched according to the actual situation of the boiler power generation system. In this embodiment, the molten salt used in the molten salt energy storage module is solar salt with a working temperature of 290℃~560℃. The molten salt energy storage module includes a cold salt tank 5, a molten salt conveying device, a molten salt pipeline of the main steam-molten salt heat exchanger 7, a molten salt pipeline of the molten salt-working fluid heat exchanger 2, a hot salt tank 8, and a molten salt pipeline of the energy release heat exchanger 10, which are connected in series to form a molten salt circuit B.

[0041] During heat storage, the low-temperature molten salt is heated to 560°C via the heat pump module, forming high-temperature molten salt stored in the hot salt tank 8. During heat release, the high-temperature molten salt is cooled to 290°C via the heat exchanger 10, forming low-temperature molten salt stored in the cold salt tank 5. Based on this, the outlet working fluid temperature of the compressor 1 is not lower than 560°C, so as to heat the molten salt to above 550°C.

[0042] The steam module includes a power generation circuit C, a heat release circuit D, and a heat absorption circuit E. The power generation circuit C is composed of a low-pressure heater 11, a deaerator 12, a first water pump 13, a high-pressure heater 14, a superheated steam pipe of a boiler 15, a high-pressure cylinder 16 of a steam turbine, a reheat steam pipe of a boiler 15, and an intermediate-low-pressure cylinder 17 of a steam turbine connected in series. Of course, in order to ensure that the steam output from the intermediate-low-pressure cylinder 17 of the steam turbine is completely converted into condensate, a condenser can also be installed between the intermediate-low-pressure cylinder 17 of the steam turbine and the low-pressure heater 11 to ensure that the steam output from the intermediate-low-pressure cylinder 17 of the steam turbine is completely converted into condensate.

[0043] The heat release circuit D is composed of the superheated steam pipe of boiler 15, main steam isolation valve 18, main steam pipe of main steam-molten salt heat exchanger 7, steam pipe of steam-working fluid heat exchanger 4, second water pump 19 and return water isolation valve 20 connected in series.

[0044] The heat absorption circuit E is connected between the high-pressure cylinder 16 and the medium-low pressure cylinder of the steam turbine and the deaerator 12. It is composed of the main feedwater isolation valve 21, the third water pump 22 and the water pipe of the energy release heat exchanger 10 connected in series. That is, the water at the outlet of the deaerator 12 is converted into steam after passing through the heat absorption circuit E and enters the high-pressure cylinder 16 or the medium-low pressure cylinder of the steam turbine to do work.

[0045] like Figure 1 As shown, since the molten salt energy storage module in this application can heat the incoming water into high-temperature and high-pressure superheated steam, the heat absorption circuit E is connected between the high-pressure cylinder 16 of the steam turbine and the deaerator 12. Of course, if the steam pressure and temperature are suitable, the heat absorption circuit E can also be connected between the medium and low-pressure cylinder 17 of the steam turbine and the deaerator 12. This is not limited here.

[0046] The thermal battery energy storage system of the above-mentioned coupled boiler power generation system has three working modes: power generation mode, peak shaving mode and peak mode. In power generation mode, the main steam isolation door 18, return water isolation door 20 and main feed water isolation door 21 are all closed, and only the power generation circuit C is running. The boiler 15 burns fuel to heat the feed water into steam and sends it into the high-pressure cylinder 16 and the medium and low-pressure cylinder of the steam turbine to drive the steam turbine to generate electricity.

[0047] In peak shaving mode, the main steam isolation door 18 and the return water isolation door 20 are opened, and the main feedwater isolation door 21 is closed. The power generation circuit C, the heat release circuit D, the heat pump module, and the molten salt energy storage module operate simultaneously. A portion of the steam from the power generation circuit C enters the heat release circuit D. The steam in the heat release circuit D preheats the molten salt output from the cold salt tank 5 of the molten salt energy storage module in the main steam-molten salt heat exchanger 7. The cooled steam enters the steam-working fluid heat exchanger 4 to heat the working fluid of the heat pump module. The working fluid heated by the steam is further compressed to a high temperature and high pressure state by the compressor 1. Then, the high temperature and high pressure working fluid enters the molten salt-working fluid heat exchanger 2 to heat the preheated molten salt. After that, the working fluid enters the expander 3 to expand. Subsequently, the working fluid continuously circulates in the steam-working fluid heat exchanger 4, the compressor 1, the molten salt-working fluid heat exchanger 2, and the expander 3. The heated molten salt is stored in the hot salt tank 8, thus completing the peak shaving energy storage.

[0048] In peak mode, the main steam isolation door 18 and the return water isolation door 20 are closed, and the main feedwater isolation door 21 is open. The power generation circuit C, the heat absorption circuit E, and the molten salt energy storage module are in operation. The heat absorption circuit E draws water from the deaerator 12 of the power generation circuit C, that is, it draws water from the regenerating part of the power generation circuit C and sends the water into the water pipe of the energy release heat exchanger 10. At the same time, the molten salt energy storage module sends the hot molten salt in the hot salt tank 8 into the molten salt pipe of the energy release heat exchanger 10. The water absorbs heat from the hot molten salt to form superheated steam and then sends it back to the high-pressure cylinder 16 or the medium and low-pressure cylinder of the turbine of the power generation circuit C to complete the release of stored energy.

[0049] Compared with the prior art, the thermal battery energy storage system of the coupled boiler power generation system provided in this application embodiment can directly consume electrical energy during the peak-shaving energy storage stage. At the same time, it can absorb the heat of the main steam output from the superheated steam pipe of boiler 15, thereby improving the peak-shaving capacity. The heat release circuit D directly extracts the main steam from the superheated steam pipe of boiler 15. The extracted main steam has a high grade, and the heat stored after being absorbed by the heat pump module and the molten salt energy storage module also has a high grade. Since the main steam is extracted, the work done by the steam turbine is reduced, further improving the peak-shaving capacity. During the peak stage, the heat stored in the molten salt can be used to heat the return water of boiler 15, generate steam and return it to the steam turbine, increase the power generation of boiler 15 generator set, improve the peak capacity of the boiler power generation system, and meet the construction requirements of the current new power system.

[0050] Preferably, in one embodiment of this application, the energy release heat exchanger 10 includes at least a superheater 1003. The superheater 1003 is used to heat water into superheated steam at high temperature and high pressure. In this embodiment of the application, the superheated steam generated by the energy release heat exchanger 10 has a pressure of not less than 16.7 MPa and a temperature of not less than 538°C.

[0051] To further optimize the above technical solution, in one embodiment of this application, in order to make full use of the heat of high-temperature molten salt, the above-mentioned energy release heat exchanger 10 includes a preheater 1001, a phase change heat exchanger 1002 and a superheater 1003 connected in series.

[0052] Specifically, such as Figure 1 As shown, the molten salt pipes of superheater 1003, phase change heat exchanger 1002, and preheater 1001 are connected in series along the molten salt conveying direction. In this way, the high-temperature molten salt first enters the superheater 1003, where the molten salt temperature is the highest, which can heat the incoming water into superheated steam with high temperature and high pressure. After cooling, the medium-temperature molten salt enters the phase change heat exchanger 1002 to continue to release heat to the incoming water. At this time, the medium-temperature molten salt will undergo a phase change. The medium-temperature molten salt enters the preheater 1001 to preheat the incoming water and improve the energy release effect.

[0053] Correspondingly, the water pipes of the preheater 1001, the phase change heat exchanger 1002, and the superheater 1003 are connected in series along the water transport direction. That is, the water with a lower temperature first enters the preheater 1001, and then passes through the phase change heat exchanger 1002 and the superheater 1003 in sequence until it becomes superheated steam with high temperature and high pressure.

[0054] Please see Figure 1 Since the end of the heat absorption circuit E needs to be connected to the high-pressure cylinder 16 or the medium-low pressure cylinder of the steam turbine, in order to prevent steam from flowing back into the heat absorption circuit E, the heat absorption circuit E also includes a steam system isolation door 23 connected in series between the water pipe of the superheater 1003 and the high-pressure cylinder or the medium-low pressure cylinder of the steam turbine. The steam system isolation door 23 is used to prevent steam in the steam turbine from flowing into the heat absorption circuit E.

[0055] Please continue reading. Figure 1 In one embodiment of this application, the molten salt conveying device includes a cold salt pump 6 and a hot salt pump 9. The cold salt pump 6 is disposed downstream of the cold salt tank 5 along the molten salt conveying direction, and the hot salt pump 9 is disposed downstream of the hot salt tank 8 along the molten salt conveying direction.

[0056] To further optimize the above technical solution, in this embodiment of the application, the boiler 15 is one of a coal-fired boiler 15, a gas-fired boiler 15, an oil-fired boiler 15, and a waste incinerator.

[0057] Preferably, the steam turbine is electrically connected to the compressor 1 through the power generation module, so that the compressor 1 of the heat pump module can directly consume the electrical energy generated by the steam turbine.

[0058] In order to make the power consumption of the heat pump system adjustable and enhance the peak-shaving capability, in one embodiment of this application, the compressor 1 is equipped with a frequency converter to make the input power adjustable.

[0059] This application embodiment also provides an operation method for a thermal battery energy storage system of a coupled boiler power generation system as described in the above embodiments, the operation method including:

[0060] In power generation mode, the main steam isolation valve 18, return water isolation valve 20, and main feedwater isolation valve 21 are closed, and only the power generation circuit C operates. The boiler 15 burns fuel to heat the incoming water into superheated steam, which is then sent to the high-pressure cylinder 16 of the turbine through the superheated steam passage of the boiler 15. The steam from the high-pressure cylinder 16 of the turbine returns to the reheated steam passage of the boiler 15 for reheating and is then sent to the medium and low-pressure cylinder 17 of the turbine to drive the turbine to do work, converting thermal energy into mechanical energy. The steam then returns to the superheated steam passage of the boiler 15 in sequence through the low-pressure heater 11, deaerator 12, first water pump 13, and high-pressure heater 14.

[0061] In peak shaving mode, the main steam isolation door 18 and the return water isolation door 20 are opened, and the main feedwater isolation door 21 is closed. The power generation circuit C, the heat release circuit D, the heat pump module, and the molten salt energy storage module are in operation. A portion of the superheated steam from the power generation circuit C enters the heat release circuit D. The steam in the heat release circuit D preheats the molten salt output from the cold salt tank 5 of the molten salt energy storage module in the main steam-molten salt heat exchanger 7. The cooled steam enters the steam-working fluid heat exchanger 4 to heat the working fluid of the heat pump module. The working fluid heated by the steam is further compressed to a high temperature and high pressure state by the compressor 1. Then, the high temperature and high pressure working fluid enters the molten salt-working fluid heat exchanger 2 to heat the preheated molten salt. Subsequently, the working fluid enters the expander 3 to expand. After that, the working fluid continuously circulates in the steam-working fluid heat exchanger 4, the compressor 1, the molten salt-working fluid heat exchanger 2, and the expander 3. The heated molten salt is stored in the hot salt tank 8, completing the peak shaving energy storage.

[0062] In peak mode, the main steam isolation door 18 and the return water isolation door 20 are closed, and the main feedwater isolation door 21 is opened. The power generation circuit C, the heat absorption circuit E, and the molten salt energy storage module are in operation. The heat absorption circuit E draws water from the deaerator 12 of the power generation circuit C and sends the water into the water pipe of the energy release heat exchanger 10. At the same time, the molten salt energy storage module sends the hot molten salt in the hot salt tank 8 into the molten salt pipe of the energy release heat exchanger 10. The water absorbs heat from the hot molten salt to form superheated steam and then sends it back to the high-pressure cylinder 16 or the medium and low-pressure cylinder of the turbine of the power generation circuit C to complete the release of stored energy.

[0063] In summary, the heat pump module in the thermal battery energy storage system of the coupled boiler power generation system provided in this application embodiment can directly consume the electrical energy generated by the steam turbine, while absorbing the heat from the main steam in the power generation circuit C of boiler 15. It has a high electro-thermal efficiency. Furthermore, by extracting the main steam in the power generation circuit C, the work done by the steam turbine is reduced, thereby achieving further peak shaving of the power generation system. The total load reduction of the power generation system is the reduction in power generation due to the extracted steam and the net power consumption of the heat pump module.

[0064] The main steam extracted by the heat release circuit D is of high quality, and the heat stored after absorption by the heat pump module is also of high quality, ensuring that the electro-electric efficiency of the heat storage and release cycle of the coupled boiler power generation system provided in this embodiment is not less than 62%. The extracted main steam is converted into condensate after heat absorption by the heat pump module and returned to the power generation circuit C, ensuring the steam-water balance of the boiler power generation system.

[0065] The molten salt energy storage module, in conjunction with the heat absorption circuit E, can generate steam with a pressure of not less than 16.7 MPa and a temperature of not less than 538°C, which is returned to the power generation circuit C. This increases the power generation of the power generation circuit C and thus improves the peak power generation capacity of the power generation system.

[0066] Based on the above, the thermal battery energy storage system of the coupled boiler power generation system provided in this application can achieve zero or near-zero output during deep peak shaving of the power generation system under specific conditions. That is, during deep peak shaving, the power output of the power generation circuit C is reduced to zero or near zero, but it does not completely stop operation. Instead, it only maintains the operation of the heat pump module, the molten salt energy storage module and related equipment. Furthermore, since the compressor 1 is equipped with a frequency converter, the amount of electricity consumed by the heat pump module is adjustable, which can improve the load change rate of the power generation system and further enhance the peak shaving capability.

[0067] As indicated in this application and claims, unless the context clearly indicates otherwise, the words "a," "an," "a," and / or "the" are not specifically singular and may include the plural. Generally, the terms "comprising" and "including" only indicate the inclusion of expressly identified steps and elements, which do not constitute an exclusive list, and the method or apparatus may also include other steps or elements. An element defined by the phrase "comprising an..." does not exclude the presence of other identical elements in the process, method, product, or apparatus that includes the element.

[0068] In the description of this application, unless otherwise expressly defined, terms such as "setup," "installation," and "connection" should be interpreted broadly, and those skilled in the art can reasonably determine the specific meaning of the above terms in this application in conjunction with the specific content of the technical solution.

[0069] It should be noted that the various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. The same or similar parts between the various embodiments can be referred to each other.

[0070] This article uses specific examples to illustrate the principles and implementation methods of the present invention. The descriptions of the above embodiments are only for the purpose of helping to understand the core ideas of the present invention. It should be noted that those skilled in the art can make several improvements and modifications to the present invention without departing from the principles of the present invention, and these improvements and modifications also fall within the protection scope of the claims of the present invention.

Claims

1. A thermal battery energy storage system coupled to a boiler power generation system, characterized in that, include: The heat pump module includes a compressor (1) forming a working fluid circuit (A) in series, a working fluid pipeline of a molten salt-working fluid heat exchanger (2), an expander (3), and a working fluid pipeline of a steam-working fluid heat exchanger (4). The molten salt energy storage module includes a cold salt tank (5) that forms a molten salt circuit (B) in series, a molten salt conveying device, a molten salt pipeline of the main steam-molten salt heat exchanger (7), a molten salt pipeline of the molten salt-working fluid heat exchanger (2), a hot salt tank (8), and a molten salt pipeline of the energy release heat exchanger (10). The steam module includes a power generation circuit (C), a heat release circuit (D), and a heat absorption circuit (E). The power generation circuit (C) is composed of a low-pressure heater (11), a deaerator (12), a first water pump (13), a high-pressure heater (14), a superheated steam pipe of a boiler (15), a high-pressure cylinder (16) of a steam turbine, a reheated steam pipe of a boiler (15), and a medium- and low-pressure cylinder (17) of a steam turbine connected in series. The heat release circuit (D) is composed of a superheated steam pipe of a boiler (15). The main steam pipe of the steam turbine, the steam pipe of the steam-working fluid heat exchanger (4), the second water pump (19) and the return water isolation door (20) are connected in series. The heat absorption circuit (E) is connected between the high pressure cylinder (16) and the medium and low pressure cylinder of the steam turbine and the deaerator (12). It is composed of the main feed water isolation door (21), the third water pump (22) and the water pipe of the energy release heat exchanger (10) connected in series.

2. The thermal battery energy storage system of the coupled boiler power generation system according to claim 1, characterized in that, The energy release heat exchanger (10) includes at least a superheater (1003) for heating steam to a superheated state in the future water.

3. The thermal battery energy storage system of the coupled boiler power generation system according to claim 2, characterized in that, The heat exchanger (10) includes a preheater (1001), a phase change heat exchanger (1002), and a superheater (1003) connected in series.

4. The thermal battery energy storage system of the coupled boiler power generation system according to claim 3, characterized in that, The molten salt pipes of the superheater (1003), the molten salt pipes of the phase change heat exchanger (1002), and the molten salt pipes of the preheater (1001) are connected in series along the molten salt conveying direction.

5. The thermal battery energy storage system of the coupled boiler power generation system according to claim 4, characterized in that, The water pipes of the preheater (1001), the phase change heat exchanger (1002), and the superheater (1003) are connected in series along the water transport direction.

6. The thermal battery energy storage system of the coupled boiler power generation system according to claim 5, characterized in that, The heat absorption circuit (E) also includes a steam system isolation door (23) between the water pipe connected in series with the superheater (1003) and the high-pressure cylinder or medium-low-pressure cylinder of the steam turbine. The steam system isolation door (23) is used to prevent steam in the steam turbine from flowing into the heat absorption circuit (E).

7. The thermal battery energy storage system of the coupled boiler power generation system according to any one of claims 1-6, characterized in that, The molten salt conveying device includes a cold salt pump (6) and a hot salt pump (9). The cold salt pump (6) is located downstream of the cold salt tank (5) along the molten salt conveying direction, and the hot salt pump (9) is located downstream of the hot salt tank (8) along the molten salt conveying direction.

8. The thermal battery energy storage system of the coupled boiler power generation system according to any one of claims 1-6, characterized in that, The boiler (15) is one of a coal-fired boiler (15), a gas-fired boiler (15), an oil-fired boiler (15), and a waste incinerator.

9. The thermal battery energy storage system of the coupled boiler power generation system according to any one of claims 1-6, characterized in that, The steam turbine is electrically connected to the compressor (1) via a power generation module.

10. A method for operating a thermal battery energy storage system of a coupled boiler power generation system as described in any one of claims 1-9, characterized in that, include: In power generation mode, the main steam isolation valve (18), return water isolation valve (20) and main feedwater isolation valve (21) are closed, and the power generation circuit (C) is in operation; In peak shaving mode, the main steam isolation door (18) and the return water isolation door (20) are opened, and the main feed water isolation door (21) is closed. The power generation circuit (C), the heat release circuit (D), the heat pump module and the molten salt energy storage module are in operation. The heat release circuit (D) draws steam from the power generation circuit (C) and heats the molten salt together with the heat pump module, and stores it in the hot salt tank (8). In peak mode, the main steam isolation door (18) and return water isolation door (20) are closed, and the main feed water isolation door (21) is opened. The power generation circuit (C), the heat absorption circuit (E) and the molten salt energy storage module are in operation. Part of the feed water in the power generation circuit (C) enters the heat absorption circuit (E) and is heated into high temperature and high pressure steam by the heat exchanger (10) of the molten salt energy storage module, and the steam is returned to the power generation circuit (C).

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