A CO 2 Heat pump-molten salt heat storage cascade steam supply system and steam supply method

Abstract

The present invention belongs to the technical field of industrial steam supply, and particularly relates to a CO2 heat pump - molten salt thermal energy storage cascade steam supply system and a steam supply method. The CO2 heat pump - molten salt thermal energy storage cascade steam supply system provided by the present invention preheats a provided steam through a CO2 heat pump device, and then reheats it through a provided molten salt thermal energy storage device, so as to ensure the steam supply requirements of medium and high pressures and large flow rates for industrial steam users. At the same time, since the molten salt thermal energy storage device stores high-temperature steam, it reduces the thermal energy storage cost while meeting the flexible peak shaving requirements of thermal power units. Furthermore, the CO2 heat pump - molten salt thermal energy storage cascade steam supply system effectively saves coal resources and reduces environmental pollution by using CO2 as the compression and expansion cycle medium and combining molten salt thermal energy storage.

Description

Technical Field

[0001] The present invention belongs to the technical field of industrial steam supply and particularly relates to a CO 2 Heat pump-molten salt heat storage cascade steam supply system and steam supply method. Background Art

[0002] At present, domestic thermal power units are the key energy source as the energy ballast, and the energy supply in regional energy is even more important, which is mainly reflected in the supply of industrial steam to the area where the thermal power plant is located or the industrial park. In the supply of external industrial steam, high-parameter and continuous supply is crucial. There are the following difficulties in the current related technologies:

[0003] First, the demand for flexible peak load regulation of thermal power units is increasing, from the requirement of less than 50% load to 30% load, or even 20% load. In addition to new technical requirements for the safe operation of the main and auxiliary machines of thermal power units at low load, the flexibility policy also requires the continuous supply of steam to the outside world at low load. However, at low load, the steam extraction pressure of each section is difficult to guarantee, while the production of the park requires uninterrupted steam supply.

[0004] Second, the more common molten salt energy storage systems are currently used to ensure the peak load and frequency regulation of thermal power units under the load instructions of power plants. The heat release and heat dissipation processes are to meet the load requirements of the units. However, the existing molten salt heat storage systems can only meet the needs of low-pressure and small-flow steam supply, and cannot meet the needs of medium- and high-pressure and large-flow steam supply. Summary of the invention

[0005] 1. Technical issues to be resolved

[0006] In order to solve the above problems in the prior art, the present invention provides a CO 2 Heat pump-molten salt heat storage cascade steam supply system, through CO 2 It compresses and expands the circulating medium and combines it with molten salt heat storage to effectively save coal resources, reduce environmental pollution, and at the same time meet the steam supply needs of medium, high pressure and large flow.

[0007] (II) Technical solution

[0008] In order to achieve the above object, the main technical solutions adopted by the present invention include:

[0009] The present invention provides a CO 2 Heat pump-molten salt heat storage cascade steam supply system, including steam turbine steam supply device, molten salt heat storage and release device and CO 2 Heat pump steam supply device; the steam turbine steam supply device is used to provide steam for the molten salt heat storage and release device to enable the molten salt heat storage and release device to store heat; in the CO 2The heat pump steam supply device provides a path of desalted water, CO 2 The heat pump steam supply device is used to heat the desalted water to form steam which enters the preheating box for re-preheating; the molten salt heat storage and release device after heat storage is used to reheat the preheated steam.

[0010] Preferably, the molten salt heat storage and release device comprises a molten salt drum, a molten salt superheater, a molten salt evaporator, a molten salt cold tank, a molten salt hot tank, a first molten salt heat exchanger and a second molten salt heat exchanger; the steam turbine steam supply device provides steam to the first molten salt heat exchanger and the second molten salt heat exchanger respectively so that the molten salt heat storage and release device can store heat; CO 2 The heat pump steam supply device is connected with the preheating box through the first steam pipeline, and the preheating box is connected with the molten salt drum through the first loop; the molten salt drum is connected with the molten salt superheater through the second steam pipeline, and the molten salt drum is used to provide preheated steam for the molten salt superheater, and the molten salt evaporator is connected with the molten salt drum through the second loop, and the molten salt evaporator is used to provide heat for the molten salt drum; the molten salt cold tank is connected with the first molten salt heat exchanger through the first pipeline, and the molten salt cold tank is connected with the second molten salt heat exchanger through the second pipeline, the first molten salt heat exchanger is connected with the molten salt hot tank through the third pipeline, and the second molten salt heat exchanger is connected with the molten salt hot tank through the fourth pipeline; the molten salt hot tank is connected with the molten salt superheater through the fifth pipeline to provide heat for the molten salt superheater to reheat the preheated steam in the molten salt superheater, the molten salt superheater is connected with the molten salt evaporator through the sixth pipeline, and the molten salt evaporator is connected with the molten salt cold tank through the seventh pipeline.

[0011] Preferably, CO 2 The heat pump steam supply device includes a first heat exchanger, a second heat exchanger, a compressor and an expansion valve; the first heat exchanger is connected to the second heat exchanger through a working fluid circuit, the compressor and the expansion valve are respectively arranged on the working fluid circuit, and CO is passed through the working fluid circuit. 2 The first heat exchanger is connected to a low-grade heat source to heat the CO flowing through the first heat exchanger. 2 The second heat exchanger is connected to the first water inlet pipeline, the first water inlet pipeline is used to provide desalted water for the second heat exchanger, and the second heat exchanger is connected to the preheating tank through the first steam pipeline.

[0012] Preferably, it also includes a second water inlet pipeline, one end of which is connected to the first heat exchanger, and the other end of which is used to connect to a low-grade heat source.

[0013] Preferably, it also includes a first water outlet pipeline, and the first heat exchanger is connected to the first water outlet pipeline for outputting the low-grade heat source after heat exchange.

[0014] Preferably, the turbine steam supply device includes a boiler, a turbine high-pressure cylinder, a turbine intermediate-pressure cylinder and a turbine low-pressure cylinder; the boiler provides steam to the turbine high-pressure cylinder and the turbine intermediate-pressure cylinder through the first main steam pipe and the second main steam pipe respectively, and the turbine intermediate-pressure cylinder provides steam to the turbine low-pressure cylinder through the third main steam pipe; the turbine steam supply device also includes a first steam branch pipe and a second steam branch pipe; one end of the first steam branch pipe is connected to the first main steam pipe, and the other end of the first steam branch pipe is connected to the first molten salt heat exchanger; one end of the second steam branch pipe is connected to the second main steam pipe, and the other end of the second steam branch pipe is connected to the second molten salt heat exchanger.

[0015] Preferably, the steam supply device of the steam turbine also includes a fourth main steam pipe, one end of the fourth main steam pipe is connected to the steam outlet of the high-pressure cylinder of the steam turbine, and the other end of the fourth main steam pipe is connected to the steam inlet of the boiler; the first molten salt heat exchanger is connected to the fourth main steam pipe through the third steam branch pipe.

[0016] Preferably, the second molten salt heat exchanger is connected to the third steam main pipeline through a fourth steam branch pipeline.

[0017] Preferably, a pipeline pump is provided on the first steam pipeline.

[0018] The present invention also provides a CO 2 A heat pump-molten salt heat storage cascade steam supply method comprises the following steps:

[0019] S1. The steam turbine steam supply device provides steam to the molten salt heat storage and release device so that the molten salt heat storage and release device can store heat;

[0020] S2. In CO 2 The heat pump steam supply device provides a path of desalted water, which is 2 The heat pump steam supply device heats up to form primary steam, which then enters the preheating box for further preheating to form secondary steam.

[0021] S3, the molten salt heat storage and release device after heat storage exchanges heat with the secondary steam so that the secondary steam forms tertiary steam after heat exchange;

[0022] S4, the third-level steam is used for external supply.

[0023] (III) Beneficial effects

[0024] The beneficial effects of the present invention are:

[0025] The present invention provides a CO 2 Heat pump-molten salt heat storage cascade steam supply system, through CO 2The heat pump device preheats the steam provided, and then reheats it through the molten salt heat storage device, which can meet the medium and high pressure and large flow steam supply needs of industrial steam units. At the same time, because the molten salt heat storage device stores high-temperature steam, it can meet the flexible peak-shaving needs of thermal power units while reducing the heat storage cost. 2 The heat pump-molten salt heat storage cascade steam supply system uses CO 2 It is a compression-expansion circulating medium combined with molten salt heat storage, which effectively saves coal resources and reduces environmental pollution.

[0026] This embodiment provides a CO 2 The heat pump-molten salt heat storage cascade steam supply method can heat the desalted water in a three-stage form and make full use of the molten salt heat storage and release device to ensure the medium, high pressure and large flow steam supply needs of industrial steam units. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 The CO provided by the present invention 2 Schematic diagram of the heat pump-molten salt thermal storage cascade steam supply system.

[0028] [Description of Reference Numerals]

[0029] 1: molten salt drum; 2: molten salt superheater; 3: molten salt evaporator; 4: molten salt cold tank; 5: molten salt hot tank; 6: first molten salt heat exchanger; 7: second molten salt heat exchanger; 8: first steam pipeline; 9: preheating box; 10: first loop; 11: second steam pipeline; 12: second loop; 13: first pipeline; 14: second pipeline; 15: third pipeline; 16: fourth pipeline; 17: fifth pipeline; 18: sixth pipeline; 19: seventh pipeline; 20: first heat exchanger; 21: second heat exchanger; 22: compressor; 23: expansion valve ; 24: working fluid circuit; 25: first water inlet pipeline; 26: second water inlet pipeline; 27: first water outlet pipeline; 28: boiler; 29: steam turbine high-pressure cylinder; 30: steam turbine intermediate-pressure cylinder; 31: steam turbine low-pressure cylinder; 32: first main steam pipeline; 33: second main steam pipeline; 34: fourth main steam pipeline; 35: first steam branch pipeline; 36: second steam branch pipeline; 37: third main steam pipeline; 38: third steam branch pipeline; 39: fourth steam branch pipeline; 40: first valve; 41: second valve; 42: pipeline pump. DETAILED DESCRIPTION

[0030] In order to better understand the above technical solution, exemplary embodiments of the present invention will be described in more detail below with reference to the accompanying drawings. Although exemplary embodiments of the present invention are shown in the accompanying drawings, it should be understood that the present invention can be implemented in various forms and should not be limited by the embodiments described herein. On the contrary, these embodiments are provided to enable a clearer and more thorough understanding of the present invention and to fully convey the scope of the present invention to those skilled in the art.

[0031] Embodiment 1

[0032] like Figure 1 As shown, the present invention provides a CO 2 Heat pump-molten salt heat storage cascade steam supply system, including steam turbine steam supply device, molten salt heat storage and release device and CO 2 Heat pump steam supply device.

[0033] The steam turbine steam supply device is used to provide steam to the molten salt heat storage and release device so that the molten salt heat storage and release device can store heat. A desalted water is provided in the CO2 heat pump steam supply device. The CO2 heat pump steam supply device is used to heat the desalted water to form steam and enter the preheating box 9 for re-preheating. The molten salt heat storage and release device after heat storage is used to reheat the preheated steam.

[0034] This embodiment provides a CO 2 Heat pump-molten salt heat storage cascade steam supply system, through CO 2 The heat pump device preheats the steam provided, and then reheats it through the molten salt heat storage device, forming a step-by-step heating system that can meet the medium and high pressure and large flow steam supply requirements of industrial steam units. At the same time, since the molten salt heat storage device stores high-temperature steam, it can meet the peak-shaving requirements of thermal power units while reducing the heat storage cost. 2 The heat pump-molten salt heat storage cascade steam supply system uses CO 2 It is a compression-expansion circulating medium combined with molten salt heat storage, which effectively saves coal resources and reduces environmental pollution.

[0035] Among them, the molten salt heat storage and release device includes a molten salt drum 1, a molten salt superheater 2, a molten salt evaporator 3, a molten salt cold tank 4, a molten salt hot tank 5, a first molten salt heat exchanger 6 and a second molten salt heat exchanger 7.

[0036] The steam turbine steam supply device is used to provide steam to the first molten salt heat exchanger 6 and the second molten salt heat exchanger 7 respectively so that the molten salt heat storage and release device can store heat. 2The heat pump steam supply device is connected to the preheating tank 9 through the first steam pipeline 8, the preheating tank 9 is connected to the molten salt drum 1 through the first loop 10, the molten salt drum 1 is connected to the molten salt superheater 2 through the second steam pipeline 11, the molten salt drum 1 is used to provide preheated steam for the molten salt superheater 2, the molten salt evaporator 3 is connected to the molten salt drum 1 through the second loop 12, the molten salt cold tank 4 is connected to the first molten salt heat exchanger 6 through the first pipeline 13, and the molten salt cold tank 4 is connected to the second molten salt through the second pipeline 14. The first molten salt heat exchanger 6 is connected to the molten salt hot tank 5 through the third pipeline 15, the second molten salt heat exchanger 7 is connected to the molten salt hot tank 5 through the fourth pipeline 16, the molten salt hot tank 5 is connected to the molten salt superheater 2 through the fifth pipeline 17 to provide heat for the molten salt superheater 2 to reheat the preheated steam in the molten salt superheater 2, the molten salt superheater 2 is connected to the molten salt evaporator 3 through the sixth pipeline 18, and the molten salt evaporator 3 is connected to the molten salt cold tank 4 through the seventh pipeline 19. Among them, the preheating box 9 is connected to the CO 2 The steam output by the heat pump steam supply device is preheated again to increase the steam temperature in stages.

[0037] In the molten salt heat storage and release device, ternary salt is stored in the molten salt cold tank 4. The ternary salt is pumped into the first molten salt heat exchanger 6 through the first pipeline 13 by the molten salt pump to absorb the heat of steam. The heated ternary salt enters the molten salt hot tank 5 through the third pipeline 15. The ternary salt stored in the molten salt cold tank 4 is pumped into the second molten salt heat exchanger 7 through the second pipeline 14 by the molten salt pump to absorb the heat of steam. The heated ternary salt enters the molten salt hot tank 5 through the fourth pipeline 16. The 360°C ternary salt stored in the molten salt hot tank 5 enters the molten salt superheater 2 through the fifth pipeline 17 for molten salt-steam heat exchange. The ternary salt after heat exchange enters the molten salt evaporator 3 through the sixth pipeline 18. The ternary salt after heat exchange in the molten salt evaporator 3 enters the molten salt cold tank 4 through the seventh pipeline 19 to complete the circulation in the molten salt system.

[0038] The molten salt evaporator 3 is connected to the molten salt drum 1 through the second loop 12, and the molten salt evaporator 3 is used to provide heat for the molten salt drum 1. The function of the second loop 12 is to send the liquid water formed by the heat release of the vapor-liquid separation device in the molten salt drum 1 into the molten salt evaporator 3, and send the steam formed by heating the molten salt evaporator 3 back to the molten salt drum 1. The molten salt evaporator 3 provides steam for the molten salt drum 1. The water of the molten salt drum 1 after vapor-liquid separation enters the molten salt evaporator 3 to continue to absorb heat and become steam to return to the molten salt drum 1, thereby making better use of the heat.

[0039] Specifically, CO 2The heat pump steam supply device includes a first heat exchanger 20, a second heat exchanger 21, a compressor 22 and an expansion valve 23. The first heat exchanger 20 is connected to the second heat exchanger 21 through a working fluid circuit 24, and the compressor 22 and the expansion valve 23 are respectively arranged on the working fluid circuit 24. The working fluid circuit 24 is connected to CO 2 The first heat exchanger 20 is connected to a low-grade heat source to heat the CO flowing through the first heat exchanger 20. 2 The second heat exchanger 21 is connected to the first water inlet pipeline 25, and the second heat exchanger 21 is connected to the preheating box 9 through the first steam pipeline 8. In this embodiment, in order to further reduce environmental pollution and achieve zero carbon emissions, CO 2 The driving source of the heat pump steam supply device is a photovoltaic power station, which drives the compressor 22 through a transformer. The desalted water enters the second heat exchanger 21 through the first water inlet pipeline 25 for heat exchange and then generates steam to enter the first steam pipeline 8. In actual application, a pipeline pump 42 is provided on the first steam pipeline 8 to adjust the steam flow output from the first steam pipeline 8 to the preheating box 9.

[0040] In this embodiment, CO 2 The heat pump-molten salt heat storage cascade steam supply system also includes a second water inlet pipeline 26 and a first water outlet pipeline 27. The second water inlet pipeline 26 is connected to the first heat exchanger 20, and the other end of the second water inlet pipeline 26 is used to connect to the low-grade heat source. The first heat exchanger 20 is connected to the first water outlet pipeline 27 for outputting the low-grade heat source after heat exchange. It should be noted that in this embodiment, the low-grade heat source is the low-grade waste heat in the circulating water of the thermal power unit. The water temperature of the circulating water entering the inlet of the second water inlet pipeline 26 is 35°C, and the temperature of the circulating water discharged from the first water outlet pipeline 27 is 20°C. The first heat exchanger 20 transfers the CO in the working fluid circuit 24 therein to the first heat exchanger 20. 2 The working fluid is heated to provide heat for the second heat exchanger 21 to heat the desalted water. In this embodiment, the water treatment system leads a 200t / h, 20°C desalted water into the first heat exchanger 20 through the first water inlet pipeline 25. The desalted water is heated to the saturated steam temperature under the corresponding pressure in the first heat exchanger 20, such as 0.4Mpa-0.5Mpa of the desalted water pipeline of the 330MW unit, which can be heated to about 150°C.

[0041] The desalted water pressure can be designed according to the actual demand for industrial steam supply pressure. For the demand for medium-pressure industrial steam, the steam supply pressure can be designed as 1.6 MPa, and for the demand for high-pressure industrial steam, it can be designed as a pressure above 2.0 MPa. In this embodiment, the pressure can be increased to 2.2-2.6 MPa by adjusting the pipeline pump 42.

[0042] Specifically, the steam turbine steam supply device includes a boiler 28, a high-pressure cylinder 29 of a steam turbine, an intermediate-pressure cylinder 30 of a steam turbine, and a low-pressure cylinder 31 of a steam turbine. The boiler 28 provides steam to the high-pressure cylinder 29 and the intermediate-pressure cylinder 30 of the steam turbine through the first main steam pipe 32 and the second main steam pipe 33, respectively, and the intermediate-pressure cylinder 30 of the steam turbine provides steam to the low-pressure cylinder 31 of the steam turbine through the third main steam pipe 37. The steam turbine steam supply device also includes a first steam branch pipe 35 and a second steam branch pipe 36, one end of the first steam branch pipe 35 is connected to the first main steam pipe 32, and the other end of the first steam branch pipe 35 is connected to the first molten salt heat exchanger 6 for providing high-temperature steam to the first molten salt heat exchanger 6, one end of the second steam branch pipe 36 is connected to the second main steam pipe 33, and the other end of the second steam branch pipe 36 is connected to the second molten salt heat exchanger 7 for providing steam to the second molten salt heat exchanger 7. Of course, a first valve 40 is provided on the first steam branch pipe 35, and a second valve 41 is provided on the second steam branch pipe 36 to adjust the input steam amount.

[0043] In this embodiment, the steam supply device of the steam turbine further includes a fourth main steam pipe 34, one end of which is connected to the steam outlet of the high-pressure cylinder 29 of the steam turbine, and the other end of which is connected to the steam inlet of the boiler 28. The first molten salt heat exchanger 6 is connected to the fourth main steam pipe 34 through the third steam branch pipe 38. The second molten salt heat exchanger 7 is connected to the third main steam pipe 37 through the fourth steam branch pipe 39. By setting the third steam branch pipe 38, it is ensured that the steam after the heat release in the molten salt system still returns to the reheater of the boiler 28, and does not affect the reheat steam temperature and the wall temperature of the reheater of the boiler 28. The fourth steam branch pipe 39 is set to ensure that the steam extracted from the boiler 28 after the heat release in the molten salt heat storage and release device still returns to the turbine intermediate pressure cylinder 30 to work, and the energy is maximized. At the same time, the extracted steam returns to the low-pressure cylinder 31 of the steam turbine to continue to work, without destroying the steam-water balance of the original boiler-turbine, and ensuring that the heat absorption and heat release process of the molten salt system does not affect the stable operation of the unit.

[0044] Embodiment 2

[0045] This embodiment provides a method for utilizing the CO 2 The heat pump-molten salt thermal storage cascade steam supply system provides a CO 2 A heat pump-molten salt heat storage cascade steam supply method comprises the following steps:

[0046] S1. The steam turbine steam supply device provides steam to the molten salt heat storage and release device so that the molten salt heat storage and release device can store heat;

[0047] S2. In CO 2 The heat pump steam supply device provides a path of desalted water, which is 2The heat pump steam supply device heats up to form primary steam, which then enters the preheating box for further preheating to form secondary steam.

[0048] S3, the molten salt heat storage and release device after heat storage exchanges heat with the secondary steam so that the secondary steam forms tertiary steam after heat exchange;

[0049] S4, the third-level steam is used for external supply.

[0050] This embodiment provides a CO 2 The heat pump-molten salt heat storage cascade steam supply method can heat the desalted water in a three-stage form and make full use of the molten salt heat storage and release device to ensure the medium, high pressure and large flow steam supply needs of industrial steam units.

[0051] In the description of the present invention, it should be understood that the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0052] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium; it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0053] In the present invention, unless otherwise clearly specified and limited, when a first feature is “on” or “below” a second feature, it may be that the first and second features are in direct contact, or that the first and second features are in indirect contact through an intermediate medium. Moreover, when a first feature is “above”, “above” or “above” a second feature, it may be that the first feature is directly above or obliquely above the second feature, or it may simply mean that the first feature is higher in level than the second feature. When a first feature is “below”, “below” or “below” a second feature, it may be that the first feature is directly below or obliquely below the second feature, or it may simply mean that the first feature is lower in level than the second feature.

[0054] In the description of this specification, the description of the terms "one embodiment", "some embodiments", "embodiment", "example", "specific example" or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, unless they are contradictory.

[0055] Although the embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations of the present invention. A person skilled in the art may alter, modify, replace and modify the above embodiments within the scope of the present invention.

Claims

1. A CO 2 Heat pump-molten salt heat storage cascade steam supply system, It is characterized in that Including steam turbine steam supply device, molten salt heat storage and release device and CO 2 Heat pump steam supply device; The steam turbine steam supply device is used to provide steam to the molten salt heat storage and release device so that the molten salt heat storage and release device can store heat; In CO 2 The heat pump steam supply device provides a path of desalted water, the CO 2 The heat pump steam supply device is used to heat the desalted water to form steam which enters the preheating box for further preheating; The molten salt heat storage and release device after heat storage is used to reheat the preheated steam; The molten salt heat storage and release device comprises a molten salt drum, a molten salt superheater, a molten salt evaporator, a molten salt cold tank, a molten salt hot tank, a first molten salt heat exchanger and a second molten salt heat exchanger; The steam turbine steam supply device provides steam to the first molten salt heat exchanger and the second molten salt heat exchanger respectively so that the molten salt heat storage and release device can store heat; The CO 2 The heat pump steam supply device is connected to the preheating box through the first steam pipeline, and the preheating box is connected to the molten salt drum through the first loop; The molten salt drum is connected to the molten salt superheater through a second steam pipeline, and the molten salt drum is used to provide preheated steam for the molten salt superheater. The molten salt evaporator is connected to the molten salt drum through a second loop, and the molten salt evaporator is used to provide heat for the molten salt drum. The molten salt cold tank is connected to the first molten salt heat exchanger through a first pipeline, the molten salt cold tank is connected to the second molten salt heat exchanger through a second pipeline, the first molten salt heat exchanger is connected to the molten salt hot tank through a third pipeline, and the second molten salt heat exchanger is connected to the molten salt hot tank through a fourth pipeline; The molten salt hot tank is connected to the molten salt superheater through a fifth pipeline to provide heat to the molten salt superheater to reheat the preheated steam in the molten salt superheater, the molten salt superheater is connected to the molten salt evaporator through a sixth pipeline, and the molten salt evaporator is connected to the molten salt cold tank through a seventh pipeline; The steam turbine steam supply device comprises a boiler, a steam turbine high-pressure cylinder, a steam turbine intermediate-pressure cylinder and a steam turbine low-pressure cylinder; The boiler provides steam to the high-pressure cylinder and the intermediate-pressure cylinder of the steam turbine through the first main steam pipeline and the second main steam pipeline respectively, and the intermediate-pressure cylinder of the steam turbine provides steam to the low-pressure cylinder of the steam turbine through the third main steam pipeline; The steam turbine steam supply device also includes a first steam branch pipeline and a second steam branch pipeline; One end of the first steam branch pipe is in communication with the first main steam pipe, and the other end of the first steam branch pipe is in communication with the first molten salt heat exchanger; One end of the second steam branch pipe is in communication with the second main steam pipe, and the other end of the second steam branch pipe is in communication with the second molten salt heat exchanger; The steam turbine steam supply device further comprises a fourth main steam pipe, one end of which is connected to the steam outlet of the high-pressure cylinder of the steam turbine, and the other end of which is connected to the steam inlet of the boiler; The first molten salt heat exchanger is connected to the fourth main steam pipeline through a third steam branch pipeline; The second molten salt heat exchanger is connected to the third main steam pipeline through a fourth steam branch pipeline.

2. The CO according to claim 1 2 Heat pump-molten salt heat storage cascade steam supply system, Features: The CO 2 The heat pump steam supply device includes a first heat exchanger, a second heat exchanger, a compressor and an expansion valve; The first heat exchanger is connected to the second heat exchanger through a working fluid circuit, the compressor and the expansion valve are respectively arranged on the working fluid circuit, and the working fluid circuit has a CO 2 The first heat exchanger is connected to a low-grade heat source to heat the CO flowing through the first heat exchanger. 2 Working fluid; The second heat exchanger is communicated with a first water inlet pipeline, and the first water inlet pipeline is used to provide the desalted water to the second heat exchanger. The second heat exchanger is communicated with the preheating tank through the first steam pipeline.

3. The CO according to claim 2 2 Heat pump-molten salt heat storage cascade steam supply system, Features: It also includes a second water inlet pipeline, one end of which is connected to the first heat exchanger, and the other end of which is used to connect to the low-grade heat source.

4. The CO according to claim 3 2 Heat pump-molten salt heat storage cascade steam supply system, Features: It also includes a first water outlet pipeline, and the first heat exchanger is connected to the first water outlet pipeline for outputting the low-grade heat source after heat exchange.

5. The CO as described in claim 1 2 heat pump - molten salt thermal energy storage cascade steam supply system Features: The first steam pipeline is provided with a pipeline pump.

6. A CO 2 Heat pump-molten salt heat storage cascade steam supply method, Features: Using the CO described in any one of claims 1 to 5 2 The heat pump-molten salt heat storage cascade steam supply system comprises the following steps; S1. The steam turbine steam supply device provides steam to the molten salt heat storage and release device so that the molten salt heat storage and release device can store heat; S2. In CO 2 The heat pump steam supply device provides a path of desalted water, which is 2 The heat pump steam supply device heats up to form primary steam, and the primary steam enters the preheating box to be preheated again to form secondary steam; S3, the molten salt heat storage and release device after heat storage exchanges heat with the secondary steam so that the secondary steam forms tertiary steam after heat exchange; S4. The third-level steam is used for external supply.

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