Multi-waste-heat utilization Carnot cell system and operation method thereof

Abstract

The invention provides a multi-waste-heat utilization Carnot cell system and an operation method thereof, and belongs to the technical field of thermal power. The system comprises an electricity-to-heat conversion system, a fused salt heat storage and release system, an auxiliary heating system and a steam turbine power generation system. The electricity-to-heat system comprises a compressor and an auxiliary steam turbine, the fused salt heat storage and release system comprises a high-temperature storage tank and a low-temperature storage tank, and the steam turbine power generation system comprises a boiler, a high-pressure cylinder, an intermediate-pressure cylinder and a low-pressure cylinder; the auxiliary heating system comprises a second heat exchanger, and the second heat exchanger heats heat supply network water through part of steam of the medium-pressure cylinder and heats a working medium at an outlet of an auxiliary steam turbine in the electricity-to-heat conversion system according to needs. The auxiliary heating system further heats heat supply network water through heat at an inlet of the low-temperature storage tank according to needs. Dead steam of the low-pressure cylinder and part or all heat supply drain water are used as low-temperature heat sources of the electricity-to-heat conversion system, the heating performance coefficient and the reciprocating efficiency of the system are improved by reducing the temperature of the storage tank and increasing the outlet temperature of a working medium of the auxiliary steam turbine, and thermoelectric coupling can be reduced.

Description

Technical Field

[0001] The present invention belongs to the technical field of thermal power generation, and in particular relates to a Carnot battery system for utilizing excess heat and an operating method thereof. Background Art

[0002] As the proportion of renewable energy (such as wind and solar) in the power system continues to increase, one of the greatest challenges facing the system is increasing its regulatory flexibility. However, renewable energy generation is significantly intermittent and volatile, resulting in frequent supply and demand imbalances in the power grid. Coal-fired cogeneration units, as the foundational power source for the power system, play a key role in regulating system load fluctuations. However, while traditional coal-fired cogeneration units offer significant energy-saving advantages, they also have strong thermal-electric coupling, and their "heat-to-electricity" operation mode has captured a significant portion of the power market share. Therefore, achieving thermal-electric decoupling and enhancing the low-carbon operational flexibility of cogeneration units are key to building a new power system dominated by clean energy.

[0003] Currently, there are molten salt Carnot battery systems for the transformation of coal-fired power plants. However, the energy release stage of these conventional molten salt Carnot battery systems is only used to replace boilers. Although they can reduce coal consumption, the thermoelectric coupling is not effectively reduced. Summary of the Invention

[0004] In view of the deficiencies of the prior art, the present invention provides a Carnot battery system for utilizing excess heat and an operating method thereof.

[0005] In order to solve one, part or all of the above technical problems, the technical solution adopted by the present invention is: A Carnot battery system for utilizing excess heat comprises an electric heat conversion system, a molten salt heat storage and release system for storing heat generated by the electric heat conversion system, an auxiliary heating system connected to a heat network, and a steam turbine power generation system capable of utilizing the heat released by the molten salt heat storage and release system for auxiliary power generation; the electric heat conversion system comprises a compressor and an auxiliary steam turbine, the molten salt heat storage and release system comprises a high-temperature storage tank and a low-temperature storage tank, and the steam turbine power generation system comprises a boiler, a high-pressure cylinder, an intermediate-pressure cylinder, and a low-pressure cylinder; the auxiliary heating system comprises a second heat exchanger, which utilizes part of the steam from the intermediate-pressure cylinder to heat water in the heat network and heats the working fluid at the outlet of the auxiliary steam turbine in the electric heat conversion system as needed; the auxiliary heating system also utilizes the heat at the inlet of the low-temperature storage tank to heat water in the heat network as needed.

[0006] Furthermore, the molten salt heat storage and release system also includes a first heat exchanger, a preheater, an evaporator, an auxiliary superheater and an auxiliary reheater; after the heat source circuits of the auxiliary superheater and the auxiliary reheater are connected in parallel, one end is connected to the high-temperature storage tank, and the other end is connected in sequence to the heat source circuit of the evaporator, the heat source circuit of the preheater, the heat source circuit of the first heat exchanger and the low-temperature storage tank; after the cold source circuits of the auxiliary superheater, the evaporator and the preheater are connected in series in sequence, they are also connected in parallel with the superheater of the boiler as a whole; the cold source circuit of the auxiliary reheater is connected in parallel with the reheater of the boiler.

[0007] Furthermore, the heat source circuit of the second heat exchanger is connected to the medium pressure cylinder; the cold source circuit of the second heat exchanger is directly connected in series in the heat network, or is connected in series with the cold source circuit of the first heat exchanger and then connected in series as a whole in the heat network.

[0008] Furthermore, the electric heat conversion system also includes a heat source heat exchanger, a heat recovery heat exchanger, a first cold source heat exchanger and a second cold source heat exchanger, and the outlet of the compressor is connected in sequence to the heat source circuit of the heat source heat exchanger, the heat source circuit of the heat recovery heat exchanger, the auxiliary steam turbine, the cold source circuit of the first cold source heat exchanger, the cold source circuit of the second cold source heat exchanger, the cold source circuit of the heat recovery heat exchanger and the inlet of the compressor; the steam turbine power generation system also includes a condenser and a deaerator, and the outlet of the low-pressure cylinder is connected in sequence to the condenser, the deaerator and the feed water inlet of the boiler; the cold source circuit of the heat source heat exchanger is connected in series between the low-temperature storage tank and the high-temperature storage tank; the heat source circuit of the first cold source heat exchanger is connected in parallel with the condenser; one end of the heat source circuit of the second cold source heat exchanger is connected in series with the heat source circuit of the second heat exchanger, and the other end is connected to the outlet of the condenser.

[0009] Furthermore, a shunt pipeline connected to the inlet of the deaerator is provided between the heat source circuit of the second cold source heat exchanger and the heat source circuit of the second heat exchanger.

[0010] Furthermore, a throttle valve is provided at the inlet of the low-temperature storage tank and the high-temperature storage tank; and a molten salt circulation pump is provided at the outlet of the low-temperature storage tank and the high-temperature storage tank.

[0011] Furthermore, the power supply for the compressor is provided by the abandoned electricity of the new energy station, the auxiliary steam turbine and the excess electricity of the thermal power plant.

[0012] Furthermore, a feed water pump is provided at the feed water inlet of the deaerator and the feed water inlet of the boiler.

[0013] Furthermore, the set temperature of the low-temperature storage tank is 260°C.

[0014] Furthermore, the steam turbine power generation system also includes a generator, and the high-pressure cylinder, the medium-pressure cylinder, the low-pressure cylinder and the generator are coaxially connected.

[0015] A method for operating a Carnot battery system for utilizing excess heat, wherein when the electric-to-heat system is in operation: part of the exhaust steam from the low-pressure cylinder is returned to the working medium cycle of the steam turbine power generation system after heating the working medium at the outlet of the auxiliary steam turbine; if the molten salt heat storage and release system is only in a heat storage state, part of the steam from the intermediate pressure cylinder is used to heat the water in the hot network; if the molten salt heat storage and release system is in a combined heat storage and release operation state, part of the steam from the molten salt heat storage and release system and the intermediate pressure cylinder is used to heat the water in the hot network at the same time; if the amount of wasted electricity accepted is relatively large, When the amount of waste electricity accepted is large and the amount of steam from the intermediate pressure cylinder used to heat the water in the hot network is large, part of the heat-supply drain water output by the second heat exchanger is directly returned to the working fluid cycle of the steam turbine power generation system, and the remaining part of the heat-supply drain water is returned to the working fluid cycle of the steam turbine power generation system after heating the working fluid at the outlet of the auxiliary steam turbine; if the amount of wasted electricity accepted is large and the amount of steam from the intermediate pressure cylinder used to heat the water in the hot network is small, all of the heat-supply drain water output by the second heat exchanger is returned to the working fluid cycle of the steam turbine power generation system after heating the working fluid at the outlet of the auxiliary steam turbine.

[0016] Furthermore, when the electric heat conversion system is in a closed state: the exhaust steam of the low-pressure cylinder is not used to heat the working fluid at the outlet of the auxiliary steam turbine; if the molten salt heat storage and release system is in a heat release state, the molten salt heat storage and release system and part of the steam of the intermediate pressure cylinder are simultaneously used to heat the hot network water, and all the heat supply drain output by the second heat exchanger is directly returned to the working fluid cycle of the steam turbine power generation system.

[0017] Compared with the prior art, the present invention has the following beneficial effects: This invention builds upon the traditional molten salt Carnot battery system for thermal power plants by adding an auxiliary heating system. This system utilizes low-pressure cylinder exhaust steam and some or all of the heat supply drain as the low-temperature heat source for the heat-to-electricity system. By lowering the storage tank temperature and raising the outlet temperature of the auxiliary steam turbine's circulating fluid, it improves the system's heating coefficient of performance and round-trip efficiency, while also reducing thermoelectric coupling. Furthermore, the auxiliary heating system can heat water in the heating network, further utilizing waste heat to expand the operating range of the cogeneration system, enhancing operational flexibility and energy efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The present invention will be described in further detail below with reference to the accompanying drawings.

[0019] Figure 1 : A schematic structural diagram of the present invention; Figure 2 : One of the working state schematic diagrams of the present invention; Figure 3 : The second schematic diagram of the working state of the present invention; Figure 4 : The third schematic diagram of the working state of the present invention; Figure 5 : Schematic diagram of the working state of the present invention four; Figure 6 : The fifth schematic diagram of the working state of the present invention; Wherein: 100-electric heat conversion system, 1-compressor, 2-heat source heat exchanger, 3-regenerative heat exchanger, 4-first cold source heat exchanger, 5-second cold source heat exchanger, 6-auxiliary steam turbine; 200-molten salt heat storage and release system, 7-second molten salt circulation pump, 8-low-temperature storage tank, 9-first heat exchanger, 10-first throttle valve, 11-preheater, 12-evaporator, 13-first mixing valve, 14-auxiliary superheater, 15-second throttle valve, 16-high-temperature storage tank, 17-first molten salt circulation pump, 18-first diverter valve, 19-auxiliary reheater; 300- auxiliary heating system, 35- second heat exchanger, 39- switching valve; 400-steam turbine power generation system, 20-second mixing valve, 21-second diverter valve, 22-boiler, 23-third diverter valve, 24-second feedwater pump, 25-deaerator, 26-high-pressure cylinder, 27-third mixing valve, 28-fourth diverter valve, 29-medium-pressure cylinder, 30-low-pressure cylinder, 31-fifth diverter valve, 32-condenser, 33-first feedwater pump, 34-fourth mixing valve, 36-generator, 37-sixth diverter valve, 38-fifth mixing valve. DETAILED DESCRIPTION

[0020] In order to better understand the present invention, the content of the present invention is further clearly described below in conjunction with the examples and drawings, but the protection content of the present invention is not limited to the following examples. In the following description, a large number of specific details are given in order to provide a more thorough understanding of the present invention. However, it is obvious to those skilled in the art that the present invention can be implemented without one or more of these details.

[0021] A Carnot battery system for utilizing excess heat, such as Figure 1 As shown, it includes an electric heat conversion system 100 for converting electrical energy into thermal energy, a molten salt heat storage and release system 200 for storing the heat generated by the electric heat conversion system 100, a steam turbine power generation system 400 that can use the heat released by the molten salt heat storage and release system 200 for auxiliary power generation, and an auxiliary heating system 300 connected to the heat network.

[0022] The electric heat conversion system 100 includes a compressor 1, a heat source heat exchanger 2, a regenerative heat exchanger 3, a first cold source heat exchanger 4, a second cold source heat exchanger 5, and an auxiliary steam turbine 6. Each of the heat source heat exchanger 2, the regenerative heat exchanger 3, the first cold source heat exchanger 4, and the second cold source heat exchanger 5 is provided with a heat source circuit and a cold source circuit, wherein the circulating medium in the heat source circuit and the cold source circuit undergo heat exchange within the device. The outlet of the compressor 1 is connected in series with the heat source circuit of the heat source heat exchanger 2, the heat source circuit of the regenerative heat exchanger 3, the auxiliary steam turbine 6, the cold source circuit of the first cold source heat exchanger 4, the cold source circuit of the second cold source heat exchanger 5, the cold source circuit of the regenerative heat exchanger 3, and the inlet of the compressor 1. The cold source circuit of the heat source heat exchanger 2 is connected in series in the molten salt heat storage and release system 200, and is used to transfer heat to the molten salt heat storage and release system 200; both ends of the heat source circuit of the first cold source heat exchanger 4 are connected to the steam turbine power generation system 400, and the two ends of the heat source circuit of the second cold source heat exchanger 5 are respectively connected to the steam turbine power generation system 400 and the auxiliary heating system 300.

[0023] The power supply for the compressor 1 is provided by the abandoned electricity of the new energy station, the auxiliary steam turbine 6, and the excess electricity of the thermal power plant.

[0024] The main circulation path of the working fluid in the electric heat conversion system 100 is: compressor 1 (compressing the working fluid to a high temperature and high pressure state under electric drive) → heat source heat exchanger 2 (transferring heat to the molten salt heat storage and release system 200) → heat recovery heat exchanger 3 (exchanging heat with the low-temperature working fluid to further reduce the temperature of the high-temperature working fluid) → auxiliary steam turbine 6 (converting heat into electrical energy to provide auxiliary power for compressor 1) → first cold source heat exchanger 4 (using waste heat transferred from the steam turbine power generation system 400 to heat the working fluid) → second cold source heat exchanger 5 (using waste heat transferred from the auxiliary heating system 300 to heat the working fluid) → heat recovery heat exchanger 3 (exchanging heat with the high-temperature working fluid to reduce the temperature of the high-temperature working fluid) → compressor 1.

[0025] Molten salt heat storage and release system 200 includes a high-temperature storage tank 16, a low-temperature storage tank 8, a first heat exchanger 9, a preheater 11, an evaporator 12, an auxiliary superheater 14, and an auxiliary reheater 19. The auxiliary superheater 14, auxiliary reheater 19, evaporator 12, preheater 11, and first heat exchanger 9 are each equipped with a heat source circuit and a cold source circuit. The circulating media in these circuits exchange heat within the system. The cold source outlet of heat source heat exchanger 2 is connected in series with the high-temperature storage tank 16, the parallel heat source circuits of the auxiliary superheater 14 and auxiliary reheater 19, the heat source circuit of the evaporator 12, the heat source circuit of the preheater 11, the heat source circuit of the first heat exchanger 9, and the cold source inlet of the low-temperature storage tank 8 and heat source heat exchanger 2. The heat source circuits of the auxiliary superheater 14 and auxiliary reheater 19 are separated by a first diverter valve 18 and merged by a first mixing valve 13. The cold source circuit of the auxiliary reheater 19 is connected to the steam turbine power generation system 400; the cold source circuits of the preheater 11, the evaporator 12 and the auxiliary superheater 14 are connected in series with each other and are also connected in series as a whole in the working medium cycle of the steam turbine power generation system 400, wherein the cold source outlet of the auxiliary superheater 14 and the cold source inlet of the preheater 11 are connected to the steam turbine power generation system 400; the cold source circuit of the first heat exchanger 9 is connected to the auxiliary heating system 300.

[0026] At the same time, throttle valves are provided at the inlets of the low-temperature storage tank 8 and the high-temperature storage tank 16, namely the first throttle valve 10 and the second throttle valve 15; molten salt circulation pumps are provided at the outlets of the low-temperature storage tank 8 and the high-temperature storage tank 16, namely the first molten salt circulation pump 17 and the second molten salt circulation pump 7.

[0027] For example, the set temperature of the low-temperature storage tank 8 is 260°C.

[0028] When the molten salt heat storage and release system 200 stores heat, the main circulation path of the working fluid is: heat source heat exchanger 2 (obtaining heat generated by the electric heat conversion system 100) → high-temperature storage tank 16 (heating internal molten salt and storing main heat) → auxiliary superheater 14 and auxiliary reheater 19 (heating the working fluid of the steam turbine power generation system 400 on demand) → evaporator 12 (heating the working fluid of the steam turbine power generation system 400 on demand) → preheater 11 (heating the working fluid of the steam turbine power generation system 400 on demand) → first heat exchanger 9 (heating the hot network water in the auxiliary heating system 300 on demand) → low-temperature storage tank 8 (heating the internal molten salt and storing waste heat) → heat source heat exchanger 2.

[0029] When the molten salt heat storage and release system 200 releases heat, the main circulation path of the working fluid is: high-temperature storage tank 16 (obtaining internally stored heat) → auxiliary superheater 14 and auxiliary reheater 19 (heating the working fluid of the steam turbine power generation system 400) → evaporator 12 (heating the working fluid of the steam turbine power generation system 400) → preheater 11 (heating the working fluid of the steam turbine power generation system 400) → first heat exchanger 9 (heating the hot network water in the auxiliary heating system 300 on demand) → low-temperature storage tank 8 (obtaining internally stored heat) → heat source heat exchanger 2 → high-temperature storage tank 16.

[0030] The auxiliary heating system 300 includes a second heat exchanger 35 and a one-inlet, two-outlet switching valve 39. The second heat exchanger 35 is provided with a heat source circuit and a cold source circuit. The steam in the heat source circuit and the hot network water in the cold source circuit undergo heat exchange within the device. The switching valve 39 and the cold source circuit of the second heat exchanger 35 are connected in series in the hot network. Specifically, the inlet of the switching valve 39 is connected to the outlet of the hot network. One outlet of the switching valve 39 is connected in series with the cold source circuit of the first heat exchanger 9 and the cold source circuit of the second heat exchanger 35, and then connected to the inlet of the hot network. The other outlet of the switching valve 39 is connected in series with the cold source circuit of the second heat exchanger 35, and then connected to the inlet of the hot network.

[0031] Steam turbine power generation system 400 includes a boiler 22, a generator 36, a high-pressure cylinder 26, an intermediate-pressure cylinder 29, a low-pressure cylinder 30, a deaerator 25, and a condenser 32. The high-pressure cylinder 26, intermediate-pressure cylinder 29, low-pressure cylinder 30, and generator 36 are coaxially connected. The superheater outlet of boiler 22 and the cold outlet of auxiliary superheater 14 are combined by a second mixing valve 20 and then connected to the inlet of the high-pressure cylinder 26. The outlet of the high-pressure cylinder 26 is split by a second diverter valve 21 and then connected to the cold inlet of the auxiliary reheater 19 and the reheater inlet of boiler 22, respectively. The cold outlet of the auxiliary reheater 19 and the reheater outlet of boiler 22 are combined by a third mixing valve 27 and then connected to the inlet of the intermediate-pressure cylinder 29. One outlet of the intermediate-pressure cylinder 29 is connected to the steam inlet of the deaerator 25, while the other outlet is split by a fourth diverter valve 28 and then connected to the inlet of the low-pressure cylinder 30 and the heat inlet of the second heat exchanger 35. The outlet of the low-pressure cylinder 30 is diverted by the fifth diverter valve 31, with one path connected to the inlet of the condenser 32 and the other path connected in series with the heat source circuit of the first cold source heat exchanger 4 and then connected to the hot well of the condenser 32. That is, the heat source circuit of the first cold source heat exchanger 4 and the condenser 32 are connected in parallel. The heat source outlet of the second heat exchanger 35 is diverted into two paths by the sixth diverter valve 37. One path is connected in series with the heat source circuit of the second cold source heat exchanger 5 and then merges with the outlet of the condenser 32 through the fourth mixing valve 34. After merging, it merges with the other path of the sixth diverter valve 37 through the fifth mixing valve 38. The merged paths are then connected to the feedwater inlet of the deaerator 25. The outlet of the deaerator 25 is diverted by the third diverter valve 23 and connected to the feedwater inlet of the boiler 22 and the cold source inlet of the preheater 11, respectively.

[0032] At the same time, feedwater pumps are provided at the feedwater inlet of the deaerator 25 and the feedwater inlet of the boiler 22. Specifically, a first feedwater pump 33 is provided at the feedwater inlet of the deaerator 25 (at the inlet of the fifth mixing valve 38), and a second feedwater pump 24 is provided at the feedwater inlet of the boiler 22 (at the inlet of the third diverter valve 23).

[0033] The cooling circuits of the preheater 11, evaporator 12, and auxiliary superheater 14 are connected in series, with one end connected to the superheater outlet of boiler 22 and the other end connected to the feedwater inlet of boiler 22, effectively connecting the entire system in parallel with the superheater of boiler 22. The cooling circuit of the auxiliary reheater 19 has one end connected to the inlet of the reheater of boiler 22 and the other end connected to the outlet of the reheater of boiler 22, effectively connecting the cooling circuit of the auxiliary reheater 19 to the reheater of boiler 22 in parallel. With this arrangement, some of the water in the steam turbine power generation system 400 can be heated as needed via the molten salt heat storage and release system 200 to steam for use in the high-pressure cylinder 26. Similarly, some of the steam discharged from the high-pressure cylinder 26 can be heated as needed via the molten salt heat storage and release system 200 to be used in the intermediate-pressure cylinder 29. This multi-stage heating system, utilizing the preheater 11, evaporator 12, auxiliary superheater 14, and auxiliary reheater 19, achieves higher heat utilization efficiency.

[0034] The steam turbine in the steam turbine power generation system 400 is equipped with three cylinders: a high-pressure cylinder 26, an intermediate-pressure cylinder 29, and a low-pressure cylinder 30. When the molten salt heat storage and discharge system 200 is storing heat, steam generated by the superheater of the boiler 22 drives the high-pressure cylinder 26. The steam discharged from the high-pressure cylinder 26 is heated by the reheater of the boiler 22 and then drives the intermediate-pressure cylinder 29. Part of the steam from the intermediate-pressure cylinder 29 drives the low-pressure cylinder 30, part of which provides heat for the deaerator 25, and part of which provides heat for the second heat exchanger 35. The steam discharged from the low-pressure cylinder 30 is condensed in the condenser 32, deoxygenated in the deaerator 25, and then returned to the boiler 22. When the molten salt heat storage and discharge system 200 is discharging heat, steam generated by the superheater of the boiler 22 and steam generated by the cold source circuit of the auxiliary superheater 14 jointly drive the high-pressure cylinder 26. The steam discharged from the high-pressure cylinder 26, partially heated by the reheater of the boiler 22 and partially heated by the auxiliary reheater 19, jointly drives the intermediate-pressure cylinder 29.

[0035] This system has the following operation methods: like Figure 2As shown, when the amount of wasted power accepted is small, the amount of steam diverted to the intermediate pressure cylinder 29 of the second heat exchanger 35 by the fourth diverter valve 28 is large, and the molten salt heat storage and release system 200 is in a heat storage state, the outlet of the switching valve 39 connected to the second heat exchanger 35 is opened, and the other outlet is closed. At this time, the hot network water does not pass through the first heat exchanger 9, but directly enters the second heat exchanger 35 to be heated by the steam in the intermediate pressure cylinder 29. Part of the condensed steam is directly returned to the deaerator 25 for heating, and the remaining part of the heating water enters the second cold source heat exchanger 5 to heat the working medium at the outlet of the auxiliary steam turbine 6, and then merges with the condensate discharged from the condenser 32 and returns to the working medium cycle of the steam turbine power generation system 400; part of the exhaust steam from the low pressure cylinder 30 enters the condenser 32, and the remaining exhaust steam enters the first cold source heat exchanger 4 to heat the working medium at the outlet of the auxiliary steam turbine 6, and then returns to the hot well of the condenser 32; like Figure 3 As shown, when the amount of wasted power accepted is large, the amount of steam diverted to the intermediate pressure cylinder 29 of the second heat exchanger 35 by the fourth diverter valve 28 is small, and the molten salt heat storage and release system 200 is in a heat storage state, the outlet of the switching valve 39 connected to the second heat exchanger 35 is opened, and the other outlet is closed. At this time, the hot network water does not pass through the first heat exchanger 9, but directly enters the second heat exchanger 35 to be heated by the steam in the intermediate pressure cylinder 29. The heat supply drain condensed from the steam all enters the second cold source heat exchanger 5 to heat the working fluid at the outlet of the auxiliary steam turbine 6, and then merges with the condensate discharged from the condenser 32 and returns to the working fluid cycle of the steam turbine power generation system 400; part of the exhaust steam from the low pressure cylinder 30 enters the condenser 32, and the remaining exhaust steam enters the first cold source heat exchanger 4 to heat the working fluid at the outlet of the auxiliary steam turbine 6, and then returns to the hot well of the condenser 32; like Figure 4 As shown, when the electric heat conversion system 100 is shut down and not in operation, and the molten salt heat storage and release system 200 is in a heat release state, the outlet of the switching valve 39 connected to the first heat exchanger 9 is opened, and the other outlet is closed. At this time, the hot network water first enters the first heat exchanger 9 and is heated by the working medium in the molten salt heat storage and release system 200. It then enters the second heat exchanger 35 and is heated by the steam in the intermediate pressure cylinder 29. The heat supply drain condensed from the steam all enters the deaerator 25, and the exhaust steam from the low pressure cylinder 30 all enters the condenser 32. like Figure 5As shown, when the amount of wasted power accepted is large, the amount of steam diverted to the intermediate pressure cylinder 29 of the second heat exchanger 35 by the fourth diverter valve 28 is small, and the molten salt heat storage and release system 200 is in a combined heat storage and release operation state, the outlet of the switching valve 39 connected to the first heat exchanger 9 is opened, and the other outlet is closed. At this time, the hot network water first enters the first heat exchanger 9 and is heated by the working medium in the molten salt heat storage and release system 200, and then enters the second heat exchanger 35 and is heated by the steam in the intermediate pressure cylinder 29. The heat supply drain condensed from the steam all enters the second cold source heat exchanger 5 to heat the working medium at the outlet of the auxiliary steam turbine 6, and then merges with the condensate discharged from the condenser 32 and returns to the working medium cycle of the steam turbine power generation system 400; part of the exhaust steam from the low pressure cylinder 30 enters the condenser 32, and the remaining exhaust steam enters the first cold source heat exchanger 4 to heat the working medium at the outlet of the auxiliary steam turbine 6, and then returns to the hot well of the condenser 32; like Figure 6 As shown, when the amount of wasted power accepted is small, the amount of steam diverted by the fourth diverter valve 28 to the intermediate pressure cylinder 29 of the second heat exchanger 35 is large, and the molten salt heat storage and release system 200 is in a combined heat storage and release operation state, the outlet of the switching valve 39 connected to the first heat exchanger 9 is opened, and the other outlet is closed. At this time, the hot network water first enters the first heat exchanger 9 and is heated by the working medium in the molten salt heat storage and release system 200. It then enters the second heat exchanger 35 and is heated by the steam in the intermediate pressure cylinder 29. Part of the condensed steam is directly returned to the deaerator 25 for heating, and the remaining part of the heating water enters the second cold source heat exchanger 5 to heat the working medium at the outlet of the auxiliary steam turbine 6, and then merges with the condensate discharged from the condenser 32 and returns to the working medium cycle of the steam turbine power generation system 400; part of the exhaust steam from the low pressure cylinder 30 enters the condenser 32, and the remaining exhaust steam enters the first cold source heat exchanger 4 to heat the working medium at the outlet of the auxiliary steam turbine 6, and then returns to the hot well of the condenser 32.

[0036] The "accepted curtailed electricity" mentioned above refers to the total amount of curtailed electricity accepted by compressor 1 during operation, including curtailed electricity from renewable energy stations and excess electricity from thermal power plants. When heating the working fluid in power-to-heat system 100, the mass flow rate diverted by fifth diverter valve 31 and sixth diverter valve 37 is adjusted based on the mass flow rate of the circulating working fluid in power-to-heat system 100. The mass flow rate of the circulating working fluid in power-to-heat system 100 is determined by the total amount of curtailed electricity accepted.

[0037] The system's heating coefficient of performance (COP) can be considered as the ratio of the heat storage capacity of the molten salt heat storage system 200 to the amount of power wasted by the heat-to-electricity system 100. The heat-to-electricity system 100 utilizes part of the exhaust steam from the low-pressure cylinder 30 to heat the working fluid at the outlet of the auxiliary steam turbine 6. Figure 2-Figure 3 、 Figure 5-Figure 6In the shown mode, the electric heat transfer system 100 also uses the heat drain of the auxiliary heating system 300 to heat the working fluid at the outlet of the auxiliary steam turbine 6. The electric heat transfer system 100 can use the exhaust steam of the low-pressure cylinder 30 and part or all of the heat drain as the low-temperature heat source of the electric heat transfer system 100, and heat the working fluid at the outlet of the auxiliary steam turbine 6 through a two-stage heating method of the first cold source heat exchanger 4 and the second cold source heat exchanger 5, that is, it can realize multi-stage utilization of waste heat and improve the system heating performance coefficient and round-trip efficiency. Figure 4-Figure 6 In the mode shown, the hot network water is heated by the first heat exchanger 9, which can correspondingly reduce the temperature of the working fluid entering the first throttle valve 10 and the temperature of the low-temperature storage tank 8. The working fluid with a lower temperature can absorb more heat when it circulates to the heat source heat exchanger 2, which can further improve the system's heating performance coefficient and round-trip efficiency.

[0038] exist Figure 2-Figure 3 In the mode shown, the mass flow rate of the heated hot network water is determined by the amount of steam in the intermediate pressure cylinder 29 diverted by the fourth diverter valve 28, and the mass flow rate of the heated hot network water is determined by the mass flow rate of the working fluid flowing from the high temperature storage tank 16 to the low temperature storage tank 8 and the amount of steam in the intermediate pressure cylinder 29 diverted by the fourth diverter valve 28.

[0039] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention and are not limiting. Other modifications or equivalent substitutions made to the technical solution of the present invention by ordinary technicians in this field should be included in the scope of the claims of the present invention as long as they do not depart from the spirit and scope of the technical solution of the present invention.

Claims

1. A Carnot battery system for utilizing excess heat, characterized in that: It comprises an electric heat conversion system (100), a molten salt heat storage and release system (200) for storing heat generated by the electric heat conversion system (100), an auxiliary heating system (300) connected to a heat network, and a steam turbine power generation system (400) capable of utilizing the heat released by the molten salt heat storage and release system (200) for auxiliary power generation; The electric heat conversion system (100) includes a compressor (1) and an auxiliary steam turbine (6); the molten salt heat storage and release system (200) includes a high-temperature storage tank (16) and a low-temperature storage tank (8); and the steam turbine power generation system (400) includes a boiler (22), a high-pressure cylinder (26), a medium-pressure cylinder (29), and a low-pressure cylinder (30); The auxiliary heating system (300) includes a second heat exchanger (35), which utilizes part of the steam from the intermediate pressure cylinder (29) to heat the hot network water and heats the working fluid at the outlet of the auxiliary steam turbine (6) in the electric heat conversion system (100) as needed; the auxiliary heating system (300) also utilizes the heat at the inlet of the low-temperature storage tank (8) to heat the hot network water as needed.

2. The Carnot battery system for utilizing excess heat according to claim 1, characterized in that: The molten salt heat storage and release system (200) further includes a first heat exchanger (9), a preheater (11), an evaporator (12), an auxiliary superheater (14) and an auxiliary reheater (19); after the heat source circuits of the auxiliary superheater (14) and the auxiliary reheater (19) are connected in parallel, one end is connected to the high-temperature storage tank (16), and the other end is sequentially connected to the heat source circuit of the evaporator (12), the heat source circuit of the preheater (11), the heat source circuit of the first heat exchanger (9) and the low-temperature storage tank (8); after the cold source circuits of the auxiliary superheater (14), the evaporator (12) and the preheater (11) are sequentially connected in series, they are also connected in parallel with the superheater of the boiler (22) as a whole; the cold source circuit of the auxiliary reheater (19) is connected in parallel with the reheater of the boiler (22).

3. The Carnot battery system for utilizing excess heat according to claim 2, characterized in that: The heat source circuit of the second heat exchanger (35) is connected to the medium-pressure cylinder (29); the cold source circuit of the second heat exchanger (35) is directly connected in series in the heat network, or is connected in series with the cold source circuit of the first heat exchanger (9) and then connected in series as a whole in the heat network.

4. The Carnot battery system for utilizing excess heat according to claim 2, characterized in that: The electric heat conversion system (100) further comprises a heat source heat exchanger (2), a heat recovery heat exchanger (3), a first cold source heat exchanger (4) and a second cold source heat exchanger (5); the outlet of the compressor (1) is sequentially connected to the heat source circuit of the heat source heat exchanger (2), the heat source circuit of the heat recovery heat exchanger (3), the auxiliary steam turbine (6), the cold source circuit of the first cold source heat exchanger (4), the cold source circuit of the second cold source heat exchanger (5), the cold source circuit of the heat recovery heat exchanger (3) and the inlet of the compressor (1); The steam turbine power generation system (400) further includes a condenser (32) and a deaerator (25), and the outlet of the low-pressure cylinder (30) is sequentially connected to the condenser (32), the deaerator (25), and the feed water inlet of the boiler (22); The cold source circuit of the heat source heat exchanger (2) is connected in series between the low-temperature storage tank (8) and the high-temperature storage tank (16); The heat source circuit of the first cold source heat exchanger (4) is connected in parallel with the condenser (32); One end of the heat source circuit of the second cold source heat exchanger (5) is connected in series with the heat source circuit of the second heat exchanger (35), and the other end is connected to the outlet of the condenser (32).

5. The Carnot battery system for utilizing excess heat according to claim 4, characterized in that: A shunt pipeline connected to the inlet of the deaerator (25) is also provided between the heat source circuit of the second cold source heat exchanger (5) and the heat source circuit of the second heat exchanger (35).

6. The Carnot battery system for utilizing excess heat according to claim 1, characterized in that: A throttle valve is provided at the inlet of the low-temperature storage tank (8) and the high-temperature storage tank (16); and a molten salt circulation pump is provided at the outlet of the low-temperature storage tank (8) and the high-temperature storage tank (16).

7. The Carnot battery system for utilizing excess heat according to claim 1, characterized in that: The power supply for the compressor (1) is provided by the abandoned electricity of the new energy station, the auxiliary steam turbine (6) and the excess electricity of the thermal power plant.

8. The Carnot battery system for utilizing excess heat according to claim 4, characterized in that: A water feed pump is provided at the water feed inlet of the deaerator (25) and the water feed inlet of the boiler (22).

9. A method for operating a Carnot battery system for utilizing excess heat according to any one of claims 1 to 8, characterized in that: When the electric heat conversion system (100) is in operation: Part of the exhaust steam from the low-pressure cylinder (30) heats the working medium at the outlet of the auxiliary steam turbine (6) and then returns to the working medium cycle of the steam turbine power generation system (400); If the molten salt heat storage and release system (200) is only in a heat storage state, part of the steam in the intermediate pressure cylinder (29) is used to heat the hot network water; If the molten salt heat storage and release system (200) is in a combined heat storage and release operation state, the molten salt heat storage and release system (200) and part of the steam in the intermediate pressure cylinder (29) are simultaneously used to heat the hot network water; If the amount of rejected electricity received is small and the amount of steam in the intermediate pressure cylinder (29) used to heat the hot network water is large, part of the heat supply drain water output by the second heat exchanger (35) is directly returned to the working medium cycle of the steam turbine power generation system (400), and the remaining heat supply drain water is returned to the working medium cycle of the steam turbine power generation system (400) after heating the working medium at the outlet of the auxiliary steam turbine (6); If the amount of wasted electricity accepted is large and the amount of steam in the intermediate pressure cylinder (29) used to heat the hot network water is small, all the heat-supplying drain water output by the second heat exchanger (35) is returned to the working medium cycle of the steam turbine power generation system (400) after heating the working medium at the outlet of the auxiliary steam turbine (6).

10. The method for operating the Carnot battery system for utilizing excess heat according to claim 9, characterized in that: When the electric heat conversion system (100) is in the closed state: exhaust steam from the low-pressure cylinder (30) is not used to heat the working medium at the outlet of the auxiliary steam turbine (6); If the molten salt heat storage and release system (200) is in a heat release state, the molten salt heat storage and release system (200) and part of the steam in the intermediate pressure cylinder (29) are simultaneously used to heat the hot network water, and all the heat supply drain water output by the second heat exchanger (35) is directly returned to the working medium cycle of the steam turbine power generation system (400).

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