Thermoelectric decoupling steam-molten salt heat exchange system and cold state starting method

Abstract

The invention provides a thermoelectric decoupling steam-molten salt heat exchange system and a cold state starting method, and relates to the technical field of new energy. Comprising a fused salt heat release subsystem, a fused salt mixer and a fused salt heat storage subsystem, the fused salt heat release subsystem comprises a steam supply device used for providing superheated steam; the working medium circulation assembly comprises a closed circulation loop and a steam pocket, the water working medium is heated by the superheated steam to generate heated steam and heated water, and the heated water continuously flows in the closed circulation loop as the water working medium; the heated steam exchanges heat with the mixed molten salt in the superheater, and the heated steam after heat exchange is heated to become first superheated steam; the molten salt mixer is used for mixing the cold molten salt and the hot molten salt to form mixed molten salt; and the fused salt heat storage subsystem is used for storing cold fused salt and hot fused salt. The problems that in the prior art, a thermoelectrolysis steam-fused salt heat exchange system uses an electric heater for starting preheating, the cost is high, and a cold state starting method of a fused salt heat storage system which uses steam as a heat source for heating fused salt does not exist are solved.

Description

Technical Field

[0001] The present invention relates to the field of new energy technology, and in particular to a thermoelectric decoupled steam-molten salt heat exchange system and a cold start method for the thermoelectric decoupled steam-molten salt heat exchange system. Background Art

[0002] Cogeneration units have the functions of supplying electricity, steam, and hot water. They are an effective means to improve the thermal efficiency and economy of coal-fired power plants and achieve energy conservation and emission reduction. However, with the continuous upgrading of my country's energy structure adjustment, traditional coal-fired units cannot meet the demand for operational flexibility, and the coupled molten salt storage and heat exchange system can achieve thermal and electrical decoupling of the unit, achieving the effect of "lowering the valley and reducing the peak" while ensuring steam supply, improving the flexibility of the unit and the economic benefits of the power plant. Therefore, the heat storage and heat release system with molten salt as the heat transfer medium is crucial in the thermal and electrical decoupling of coal-fired units. Its startup and operation are related to the quality and stability of the steam output of the system, thus affecting the operating performance of the entire power station.

[0003] When the molten salt system is cold started, a special preheating process is used. On the one hand, it can prevent the molten salt entering the system from solidifying, and on the other hand, it can prevent high-temperature molten salt or high-temperature steam from directly entering the normal temperature system. This can effectively reduce adverse effects such as thermal shock and stress concentration on equipment and pipelines, and ensure equipment safety and system life.

[0004] In the prior art, the startup preheating of the steam-water side of the molten salt exothermic system (i.e., the steam generation system) is mainly performed by installing an electric heater on the pipeline to provide heat for preheating. When coupled with a coal-fired power unit, if the original unit steam is used instead of the electric heater to provide preheating heat, the advantage of the low cost of steam in the coal-fired power unit can be fully utilized and the energy utilization rate can be further improved. However, there is currently no solution or application for using steam as a heat source to preheat the steam generation system.

[0005] When the molten salt system is used for thermal-electric decoupling of coal-fired power units, the source of molten salt heat is mainly electricity or the heat energy of high-temperature steam of the unit. When the high-temperature steam of the unit is used to heat the molten salt heat storage, it is necessary to heat the molten salt heat storage system through steam heating similar to the molten salt heat release system, but there is currently no startup preheating solution specifically for this system.

[0006] Therefore, a method is urgently needed to solve the above problems. Summary of the invention

[0007] The purpose of the embodiments of the present invention is to provide a thermoelectric decoupled steam-molten salt heat exchange system and a cold start method, which are used to solve the problems in the prior art that the thermoelectric decoupled molten salt heat exchange system uses an electric heater for startup preheating and there is no cold start method for the molten salt heat storage system that uses steam as a heat source to heat the molten salt.

[0008] In order to achieve the above-mentioned object, the present invention provides a thermal-electric decoupled steam-molten salt heat exchange system connected to a coal-fired power generation unit, comprising: a molten salt heat release subsystem, a molten salt mixer and a molten salt heat storage subsystem; The molten salt heat release subsystem comprises: A steam supply device for providing superheated steam as a heat source; The working medium circulation component comprises a closed circulation loop and a steam drum arranged on the closed circulation loop, wherein water working medium flows in the closed circulation loop, the steam drum is connected to a steam supply device, the water working medium entering the steam drum through the closed circulation loop is heated by superheated steam provided by the steam supply device to generate heated steam and heated water, the heated water continues to flow in the closed circulation loop as the water working medium, and the heated steam is discharged through a steam outlet of the steam drum; A superheater is connected to the steam drum and the molten salt mixer. The heated steam from the steam drum and the mixed molten salt from the molten salt mixer are heat exchanged in the superheater. After the heat exchange, the heated steam is heated to become the first superheated steam, and the mixed molten salt loses heat to become the first de-temperature molten salt. The molten salt mixer is connected to the molten salt heat storage subsystem and is used to mix cold molten salt from the molten salt heat storage subsystem with hot molten salt to form mixed molten salt; The molten salt heat storage subsystem is connected to the coal-fired power generation unit and the superheater of the molten salt heat release subsystem, and is used to store cold molten salt and hot molten salt.

[0009] Specifically, the working fluid circulation component also includes: an evaporator, a working fluid deaerator and a preheater; The working fluid deaerator, the preheater, the steam drum and the evaporator are connected in sequence through pipelines to form a closed circulation loop; The working medium outlet of the working medium deaerator is connected to the water inlet of the steam drum, so as to supply water working medium to the steam drum; The first inlet and the second inlet of the evaporator are both connected to the water outlet of the drum to form an auxiliary circulation loop, the second inlet and the second inlet of the evaporator are also connected to the working fluid inlet of the working fluid deaerator, the evaporation salt inlet of the evaporator is connected to the superheating salt outlet of the superheater, and the evaporation salt outlet of the evaporator is connected to the preheating salt inlet of the preheater. The evaporator can use the heated water from the drum to exchange heat with the first dethermal molten salt from the superheater. After the first dethermal molten salt loses heat, it becomes the second dethermal molten salt and enters the preheater; The preheater is located on the loop section between the working fluid outlet of the working fluid deaerator and the water inlet of the steam drum. The preheating salt outlet of the preheater is connected to the molten salt heat storage subsystem. The preheater uses the second dethermal molten salt from the evaporator to preheat the water working fluid supplied to the steam drum by the working fluid deaerator.

[0010] Specifically, the working medium circulation component also includes: a water feed pump and a circulating water pump; The water feed pump is arranged on the closed circulation loop, located on the loop section between the working medium deaerator and the preheater, and is used to feed the water working medium in the working medium deaerator into the preheater; The circulating water pump is arranged on the closed circulation loop, located on the loop section between the evaporator and the working fluid deaerator, and is used to pump the heated water in the evaporator as the water working fluid into the working fluid deaerator.

[0011] Specifically, the molten salt heat storage subsystem includes: a hot storage tank, a cold storage tank, a molten salt heat exchange component and a hydrophobic expansion tank; The hot storage tank is connected to the molten salt mixer and is used to store hot molten salt and supply hot molten salt to the molten salt mixer; The cold storage tank is connected to the molten salt mixer and the preheater, and is used to store cold molten salt and supply cold molten salt to the molten salt mixer; The molten salt heat exchange component is connected to the hot storage tank, the cold storage tank, the superheater and the coal-fired power generation unit. The molten salt heat exchange component is used to use the first superheated steam from the superheater or the unit extraction steam extracted from the coal-fired power generation unit to heat the cold molten salt from the cold storage tank into hot molten salt. The hot molten salt is sent to the hot storage tank for storage. The first superheated steam or the unit extraction steam loses heat and becomes heat-depleted steam. The steam expansion tank is used to recover the lost heat steam.

[0012] Specifically, the molten salt heat exchange assembly includes: a main steam heat exchanger and a plurality of auxiliary heat exchangers; The steam inlet of the main steam heat exchanger is connected to the steam outlet of the superheater and the steam extraction outlet of the coal-fired power generation unit, and the steam outlet of the main steam heat exchanger is connected to the steam inlet of the hydrophobic expansion tank. The main steam heat exchanger uses the first superheated steam or the main steam extracted from the coal-fired power generation unit as the unit extraction steam to heat the cold molten salt into hot molten salt, and the first superheated steam or the main steam loses heat to become heat-losing steam; The steam inlet of the auxiliary heat exchanger is connected to the steam outlet of the superheater and the extraction steam outlet of the coal-fired power generation unit, and the steam outlet of the auxiliary heat exchanger is connected to the steam inlet of the hydrophobic expansion tank. The auxiliary heat exchanger uses the first superheated steam or the hot resteam and / or four-extraction steam extracted from the coal-fired power generation unit as the unit extraction steam to heat the cold molten salt into hot molten salt, and the hot resteam and four-extraction steam lose heat and become heat-losing steam.

[0013] Specifically, the molten salt heat exchange component also includes: a main steam condensing heat exchanger, which is arranged on the connecting pipe between the main steam heat exchanger and the hydrophobic expansion tank, and is used to use the deheated steam discharged from the main steam heat exchanger to preheat the cold molten salt entering the main steam heat exchanger.

[0014] Specifically, it also includes: a steam supply manifold for recovering the excess first superheated steam discharged from the superheater.

[0015] Another aspect of the present invention provides a cold start method of a thermoelectric decoupled steam-molten salt heat exchange system, which is used to start the thermoelectric decoupled steam-molten salt heat exchange system according to any one of the above claims, comprising: S1) preheating step: heating the water working medium in the drum by superheated steam to generate heated steam and heated water, the heated water continues to flow in the closed circulation loop as the water working medium to preheat the steam-water side of the working medium circulation component, the heated steam flows through the superheater and then flows on the steam-water side of the molten salt heat storage subsystem, the steam-water side of the molten salt heat storage subsystem and the steam-water side of the superheater are preheated by the heated steam, and at the same time, the molten salt side of the molten salt heat release subsystem and the molten salt side of the molten salt heat storage subsystem are preheated by electric tracing, until the temperature of the steam-water side of the working medium circulation component, the steam-water side of the molten salt heat storage subsystem and the steam-water side of the superheater reaches the first set temperature, the temperature of the molten salt side of the molten salt heat release subsystem and the molten salt side of the molten salt heat storage subsystem reaches the second set temperature, and the preheating is completed, wherein the steam-water side refers to the pipe or flow channel through which the working medium water or steam flows under normal operating conditions, and the molten salt side refers to the pipe or flow channel through which the molten salt flows under normal operating conditions; S2) semi-startup step: hot molten salt and cold molten salt are supplied to the molten salt mixer through the molten salt heat storage subsystem to form a mixed molten salt, the mixed molten salt exchanges heat with the heated steam in the superheater, the mixed molten salt loses heat to become the first temperature-losing molten salt, the heated steam is heated to become the first superheated steam, the first superheated steam flows on the steam-water side of the molten salt heat storage subsystem and exchanges heat with the cold molten salt, the first superheated steam flows on the steam-water side of the molten salt heat storage subsystem to further heat the steam-water side of the molten salt heat storage subsystem, the cold molten salt of the molten salt heat storage subsystem exchanges heat with the first superheated steam and then heats up and flows through the molten salt side of the molten salt heat storage subsystem, until the temperature of the first superheated steam discharged from the superheater reaches the third set temperature, and at the same time, the temperature of the molten salt side of the molten salt heat storage subsystem reaches the fourth set temperature, and the semi-startup is completed, that is, the molten salt heat release subsystem is started up; S3) Startup step: extract the extraction steam of the coal-fired power generation unit to heat the cold molten salt into hot molten salt, until the cold molten salt and the extraction steam of the unit achieve stable heat exchange, and the molten salt heat storage subsystem is started.

[0016] Specifically, in step S2), the mixed molten salt and the heated steam are heat exchanged in a superheater, including: The flow rate of hot molten salt fed into the molten salt mixer is adjusted according to the heating rate of the superheater until the temperature of the first superheated steam discharged from the superheater reaches the third set temperature, and the cold molten salt is stopped from being fed to the molten salt mixer, while the hot molten salt is continued to be fed to the molten salt mixer.

[0017] Specifically, in step S3), extracting steam from a coal-fired power generation unit to heat cold molten salt to form hot molten salt includes: The unit extraction steam extracted from the coal-fired power generation unit is cooled and depressurized to a fifth set temperature, and the unit extraction steam cooled and depressurized to the fifth set temperature is used to heat the cold molten salt to become hot molten salt.

[0018] The thermoelectric decoupled steam-molten salt heat exchange system provided by the present invention supplies superheated steam to the steam drum of the working medium circulation component through a steam supply device, and the superheated steam entering the steam drum heats the water working medium entering the steam drum through a closed circulation loop. After the water working medium is heated, it becomes heated steam and heated water, and the heated steam is discharged from the steam drum. The heated water can continue to flow in the closed circulation loop as the water working medium after being discharged from the steam drum. The temperature of the heated water is higher than the temperature of the water working medium entering the steam drum. In this way, heated water is continuously discharged from the steam drum to flow in the closed circulation loop, so that the temperature of the water working medium flowing in the closed circulation loop gradually increases, and then the closed circulation loop is supplied with heat by the gradually heated water working medium. Preheating, the heated steam discharged from the steam drum enters the superheater, and enters the molten salt heat storage subsystem through the superheater, so that the steam-water side of the superheater and the molten salt heat storage subsystem is preheated by the heated steam, and the heated steam can also exchange heat with the mixed molten salt entering the superheater in the superheater, and the heated steam absorbs the heat of the mixed molten salt and heats up to become the first superheated steam, and the first superheated steam enters the molten salt heat storage subsystem to further heat the steam-water side of the molten salt heat storage subsystem, and the molten salt heat storage subsystem can also use the first superheated steam or the unit extraction steam to heat the cold molten salt in the molten salt heat storage subsystem to become hot molten salt, and at the same time preheat the molten salt side of the molten salt heat storage subsystem by the heated molten salt. In this way, during the cold start-up process of the thermoelectric decoupled steam-molten salt heat exchange system, steam is used to preheat the thermoelectric decoupled steam-molten salt heat exchange system, thereby reducing the use of electric energy. This solves the problems in the prior art of high cost of using electric heaters for startup preheating of the thermoelectric decoupled molten salt heat exchange system and the lack of a cold start-up method for the molten salt heat storage system that uses steam as a heat source to heat the molten salt. This improves energy utilization, reduces operating costs, reduces thermal shock, and extends equipment life.

[0019] Other features and advantages of the embodiments of the present invention will be described in detail in the subsequent detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The accompanying drawings are used to provide a further understanding of the embodiments of the present invention and constitute a part of the specification. Together with the following specific implementations, they are used to explain the embodiments of the present invention, but do not constitute a limitation on the embodiments of the present invention. In the accompanying drawings: Figure 1 It is a schematic diagram of the structural layout of the thermoelectric decoupled steam-molten salt heat exchange system provided by the present invention.

[0021] Description of Reference Numerals 1-molten salt heat release subsystem; 2-working fluid circulation component; 3-superheater; 4-molten salt mixer; 5-molten salt heat storage subsystem; 6-steam supply manifold; 9-auxiliary circulation loop; 10-steam supply device; 20-closed circulation loop; 21-steam drum; 22-evaporator; 23-working fluid deaerator; 24-preheater; 25-feed water pump; 26-circulating water pump; 220-first inlet and outlet; 221-second inlet and outlet; 31-steam-water main pipeline; 32-steam-water branch pipeline; 51-hot storage tank; 52-cold storage tank; 53-molten salt heat exchange component; 54-drain expansion tank; 55-stop valve; 531-main steam heat exchanger; 532-auxiliary heat exchanger; 533-main steam condensing heat exchanger; 71-first stop valve; 72-second stop valve; 73-third stop valve; 74-fourth stop valve. DETAILED DESCRIPTION

[0022] The specific implementation of the embodiment of the present invention is described in detail below in conjunction with the accompanying drawings. It should be understood that the specific implementation described here is only used to illustrate and explain the embodiment of the present invention, and is not used to limit the embodiment of the present invention.

[0023] Figure 1 It is a schematic diagram of the thermal-electric decoupled steam-molten salt heat exchange system. Figure 1 As shown, the present invention provides a thermal-electric decoupled steam-molten salt heat exchange system, connected to a coal-fired power generation unit, comprising: a molten salt heat release subsystem 1, a molten salt mixer 4 and a molten salt heat storage subsystem 5; The molten salt heat release subsystem 1 comprises: A steam supply device 10, for providing superheated steam as a heat source; The working medium circulation component 2 includes a closed circulation loop 20 and a steam drum 21 arranged on the closed circulation loop 20. Water working medium flows in the closed circulation loop 20. The steam drum 21 is connected to the steam supply device 10. The water working medium entering the steam drum 21 through the closed circulation loop 20 is heated by the superheated steam provided by the steam supply device 10 to generate heated steam and heated water. The heated water continues to flow in the closed circulation loop 20 as the water working medium, and the heated steam is discharged through the steam outlet of the steam drum 21. The superheater 3 is connected to the steam drum 21 and the molten salt mixer 4. The heated steam from the steam drum 21 and the mixed molten salt from the molten salt mixer 4 are heat exchanged in the superheater 3. After the heat exchange, the heated steam is heated to become the first superheated steam, and the mixed molten salt loses heat to become the first dehumidified molten salt. The molten salt mixer 4 is connected to the molten salt heat storage subsystem 5 and is used to mix the cold molten salt from the molten salt heat storage subsystem 5 with the hot molten salt to form a mixed molten salt; The molten salt heat storage subsystem 5 is connected to the coal-fired power generation unit and the superheater 3 of the molten salt heat release subsystem 1, and is used to store cold molten salt and hot molten salt.

[0024] The steam-water side of the working fluid circulation component 2 refers to the pipes and flow channels through which the water working fluid flows, the molten salt side refers to the pipes and flow channels through which the molten salt flows, the flow channel in the superheater 3 that allows steam to flow is defined as the steam-water side of the superheater 3, the flow channel in the superheater 3 that allows molten salt to flow is defined as the molten salt side of the superheater 3, the steam-water side of the molten salt heat release subsystem 1 is composed of the steam-water side of the working fluid circulation component 2 and the steam-water side of the superheater 3, and the molten salt side of the molten salt heat release subsystem 1 is composed of the molten salt side of the working fluid circulation component 2 and the molten salt side of the superheater; the steam-water side of the molten salt heat storage subsystem 5 refers to the pipes and flow channels through which the steam flows, and the molten salt side of the molten salt heat storage subsystem 5 refers to the pipes and flow channels through which the molten salt flows.

[0025] In the thermoelectric decoupled steam-molten salt heat exchange system provided by the present invention, the steam supply device 10 supplies superheated steam to the steam drum 21 of the working medium circulation component 2, the steam outlet of the steam supply device 10 is connected to the steam inlet of the steam drum 21 through a pipeline, and a first stop valve 71 is arranged on the pipeline between the steam outlet of the steam supply device 10 and the steam inlet of the steam drum 21, and the flow state of the superheated steam in the pipeline between the steam outlet of the steam supply device 10 and the steam inlet of the steam drum 21 is controlled by the first stop valve 71. The external steam supply manifold of the coal-fired power generation unit can be used as the steam supply device 10, and the water working medium in the closed circulation loop 20 enters through the water inlet of the steam drum 21, and the water working medium entering the steam drum 21 is heated by the superheated steam. After being heated, the water working medium is heated to become heated water and heated steam, and the heated steam is discharged from the steam outlet of the steam drum 21. The heated water can be discharged from the water outlet of the steam drum 21 as the water working medium and continue to flow in the closed circulation loop 20, and the temperature of the heated water is higher than that of the water working medium entering the steam drum 21. Temperature, that is, the temperature of the water medium entering the water inlet of the drum 21 is lower than the temperature of the heated water discharged from the water outlet of the drum 21, so that the heated water is continuously discharged from the water outlet of the drum 21 and flows in the closed circulation loop 20, and the water medium in the closed circulation loop 20 continuously enters and exits the drum 21 and is heated by the superheated steam, so that the temperature of the water medium gradually increases, and the gradually heated water medium flows in the closed circulation loop 20, preliminarily preheating the steam-water side of the working medium circulation component 2; working medium circulation During the initial preheating process of the steam-water side of component 2, the molten salt heat release subsystem 1 and the molten salt heat storage subsystem 5 are initially preheated by electric heating; in the process of using heated water to preheat the working medium circulation component 2, the heated steam discharged from the steam drum 21 enters the molten salt heat storage subsystem 5 through the superheater 3, and the heated steam preheats the steam-water side of the superheater 3 and the steam-water side of the molten salt heat storage subsystem 5 in the process of flowing through the steam-water side of the superheater 3 and the steam-water side of the molten salt heat storage subsystem 5.After preheating the molten salt of the molten salt heat release subsystem 1 and the molten salt heat storage subsystem 5 by electric tracing, the molten salt mixer 4 mixes the cold molten salt and the hot molten salt from the molten salt heat storage subsystem 5 to form a mixed molten salt, and the mixed molten salt is sent to the superheater 3 for heat exchange with the heated steam. The heated steam absorbs the heat of the mixed molten salt and heats up to become the first superheated steam. The mixed molten salt loses heat and becomes the first detemperature molten salt. The first superheated steam is sent to the molten salt heat storage subsystem 5. The molten salt heat storage subsystem 5 uses the first superheated steam to heat the cold molten salt to become hot molten salt. In the process of using the first superheated steam to heat the cold molten salt, the steam-water side and the molten salt side of the molten salt heat storage subsystem 5 are further heated. After the heated steam and the first superheated steam entering the molten salt heat storage subsystem 5 successively preheat the steam-water side of the molten salt heat storage subsystem 5, the coal is extracted. The steam extraction of the generator set enters the molten salt heat storage subsystem 5 to further heat the steam-water side of the molten salt heat storage subsystem 5. At the same time, the steam extraction of the set can be used to heat the cold molten salt to become hot molten salt, so that the cold molten salt and the steam extraction of the set can achieve stable heat exchange, thereby completing the cold start of the system. In the present application, superheated steam is used to heat the water working medium to produce heated water and heated steam. The heated water flows in the working medium circulation component 2 to preheat the steam-water side of the working medium circulation component 2. The heated steam enters the molten salt heat storage subsystem 5 through the superheater 3 to preheat the steam-water side of the molten salt heat storage subsystem 5 and the steam-water side of the superheater 3, thereby solving the problems of high cost of starting and preheating using electric heaters in the prior art for the thermoelectric decoupled molten salt heat exchange system and the lack of a cold start method for the molten salt heat storage system using steam as a heat source to heat the molten salt.

[0026] In one embodiment, Figure 1 As shown, the working fluid circulation component 2 further includes: an evaporator 22, a working fluid deaerator 23 and a preheater 24; The working fluid deaerator 23, the preheater 24, the steam drum 21 and the evaporator 22 are sequentially connected by pipelines to form a closed circulation loop 20; The working medium outlet of the working medium deaerator 23 is connected to the water inlet of the drum 21, and is used to supply water working medium to the drum 21; The first inlet and outlet 220 and the second inlet and outlet 221 of the evaporator 22 are both connected to the water outlet of the drum 21 to form an auxiliary circulation loop 9. The second inlet and outlet 221 of the evaporator 22 is also connected to the working medium inlet of the working medium deaerator 23. The evaporation salt inlet of the evaporator 22 is connected to the superheating salt outlet of the superheater 3. The evaporation salt outlet of the evaporator 22 is connected to the preheating salt inlet of the preheater 24. The evaporator 22 can use the heated water from the drum 21 to exchange heat with the first dethermal molten salt from the superheater 3. After the first dethermal molten salt loses heat, it becomes the second dethermal molten salt and enters the preheater 24. After the heated water absorbs the heat of the first dethermal molten salt and heats up, it enters the working medium deaerator 23 as a water working medium through the closed circulation loop 20; The preheater 24 is located on the loop section between the working medium outlet of the working medium deaerator 23 and the water inlet of the steam drum 21. The preheating salt outlet of the preheater 24 is connected to the molten salt heat storage subsystem 5. The preheater 24 uses the second dethermal molten salt from the evaporator 22 to preheat the water working medium supplied to the steam drum 21 by the working medium deaerator 23.

[0027] The working medium circulation component 2 also includes: a water supply pump 25 and a circulating water pump 26; The water feed pump 25 is arranged on the closed circulation loop 20, located on the loop section between the working medium deaerator 23 and the preheater 24, and is used to feed the water working medium in the working medium deaerator 23 into the preheater 24; The circulating water pump 26 is arranged on the closed circulation loop 20 , located on the loop section between the evaporator 22 and the working fluid deaerator 23 , and is used to pump the heated water in the evaporator 22 into the working fluid deaerator 23 as the water working fluid.

[0028] The preheater 24 and the evaporator 22 both have flow channels for allowing water working medium to flow and flow channels for allowing molten salt to flow. The flow channels for allowing water working medium to flow are the steam-water side of the preheater 24 and the steam-water side of the evaporator 22, and the flow channels for allowing molten salt to flow are the molten salt side of the preheater 24 and the molten salt side of the evaporator 22. The steam-water side of the working medium circulation component 2 is formed by the steam-water side of the preheater 24, the steam-water side of the evaporator 22, the deaerator 23, the steam drum 20, and the pipeline of the closed circulation loop 20. The working medium water passes through the steam drum 20. After the superheated steam is heated, its temperature rises, and then when it flows on the steam-water side of the working fluid circulation component 2, it can preheat the steam-water side of the working fluid circulation component 2. The flow channel in the superheater 3 that allows steam to flow is the steam-water side of the superheater 3, and the flow channel in the superheater 3 that allows molten salt to flow is the molten salt side of the superheater 3. The steam-water side of the molten salt heat release subsystem 1 is composed of the steam-water side of the working fluid circulation component 2 and the steam-water side of the superheater 3, and the molten salt side of the molten salt heat release subsystem 1 is composed of the molten salt side of the working fluid circulation component 2 and the molten salt side of the superheater 3.

[0029] The working fluid deaerator 23 supplies working fluid water to the steam drum 21, a preheater 24 is arranged on the pipeline section between the working fluid deaerator 23 and the steam drum 21, two evaporators 22 are arranged on the loop section between the water outlet of the steam drum 21 and the working fluid inlet of the working fluid deaerator 23, the first inlet and outlet 220 of each evaporator 22 are connected to the water outlet of the steam drum 21, the second inlet and outlet 221 of each evaporator 22 are connected to the water outlet of the steam drum 21 to form an auxiliary circulation loop 9, the second inlet and outlet 221 of each evaporator 22 is also connected to the working fluid inlet of the working fluid deaerator 23, a circulating water pump 26 is arranged on the loop section between the second inlet and outlet 221 of the evaporator 22 and the working fluid inlet of the working fluid deaerator 23, and a feed water pump 25 is arranged on the loop section between the working fluid outlet of the working fluid deaerator 23 and the water inlet of the preheater 24.

[0030] In the preheating stage of the working medium circulation component 2, the feed water pump 25 pumps the water working medium in the working medium deaerator 23 to the steam drum 21. The water working medium flows through the preheater 24 and is discharged from the water outlet of the preheater 24 into the steam drum 21. At the same time, the steam supply device 10 supplies superheated steam to the steam drum 21. The water working medium is heated by the superheated steam to become heated water and heated steam. The heated water is discharged from the water outlet of the steam drum 21 into the evaporator 22 as the water working medium. The heated water flows through the steam-water side of the evaporator 22 to preheat the steam-water side of the evaporator 22, and then is discharged from the evaporator 22. The circulating water pump 26 pumps the heated water discharged from the evaporator 22 into the working medium deaerator 23, and the feed water pump 25 pumps the water working medium in the working medium deaerator 23 to the preheater 24 and the steam drum 21, so that the water working medium flows in the closed circulation loop 20 and continuously enters and exits the steam drum 21, and the superheated steam entering the steam drum 21 continuously heats the water working medium flowing in the closed circulation loop 20, so that the temperature of the water working medium flowing in the closed circulation loop 20 is increased, and the continuously heated water working medium flows through the evaporator 22, the working medium deaerator 23, and the preheater 24 of the working medium circulation component 2. 4 and the closed circulation loop 20, the steam-water side of the evaporator 22, the working medium deaerator 23, the steam-water side of the preheater 24 and the pipeline of the closed circulation loop 20 are preheated. While the steam-water side of the working medium circulation component 2 is preheated by the water working medium that is constantly heated, the molten salt side of the molten salt heat release subsystem 1 and the molten salt side of the molten salt heat storage subsystem 5 are preheated by electric heating. While preheating the steam-water side of the molten salt heat release subsystem 1, the heated steam flow generated by the steam drum 21 passes through the preheater 3 and enters the steam-water side of the molten salt heat storage subsystem 5. The heated steam preheats the steam-water side of the superheater 3 and the steam-water side of the molten salt heat storage subsystem 5. The temperature of the steam-water side of the molten salt heat release subsystem 1 and the molten salt heat storage subsystem 5 reaches the first set temperature. After the temperature of the molten salt heat release subsystem 1 and the molten salt heat storage subsystem 5 reaches the second set temperature, the thermoelectric decoupled steam-molten salt heat exchange system completes the initial preheating. After that, the steam supply device 10 stops supplying superheated steam to the steam drum 21, the molten salt heat release subsystem 1 and the molten salt heat storage subsystem 5 stop preheating by electric tracing, and the operation of the circulating water pump 26 is stopped. The steam-water side of the molten salt heat release subsystem 1 and the molten salt heat storage subsystem 5 are both preheated by the water working medium and the generated heated steam, avoiding the high preheating cost caused by using electric energy to preheat the steam-water side of the molten salt heat release subsystem 1 and the molten salt heat storage subsystem 5.

[0031] In addition to obtaining water working medium from the evaporator 22, the working medium deaerator 23 can also obtain water working medium from the steam supply manifold of the coal-fired unit, the circulating water at the outlet of the preheater of the steam generation system, or the pumping water before the main engine deaerator, so as to keep the liquid level in the working medium deaerator 23 at an appropriate height.

[0032] After the preheating of the molten salt heat release subsystem 1 is completed and the circulating water pump 26 is stopped, the heated water generated in the drum 21 is discharged from the lower water outlet of the drum 21 and enters the evaporator 22. The heated water exchanges heat with the first dethermal molten salt from the superheater 3 in the evaporator 22. The heated water absorbs the waste heat of the first dethermal molten salt and its temperature rises. The heated water returns to the drum 21 again through the auxiliary circulation loop 9. The first dethermal molten salt loses heat and becomes the second dethermal molten salt. The second dethermal molten salt enters the preheater 2. 4 exchanges heat with the water working medium from the working medium deaerator 23. The second dethermal molten salt loses heat and becomes cold molten salt, which enters the cold storage tank 52 of the molten salt heat storage subsystem 5 for storage. The water working medium absorbs the waste heat of the second dethermal molten salt and enters the steam drum 21. The heated steam in the steam drum 21 enters the superheater 3 and exchanges heat with the mixed molten salt from the molten salt mixer 4. The heated steam absorbs the heat of the mixed molten salt and becomes the first superheated steam. The mixed molten salt loses heat and becomes the first dethermal molten salt and enters the evaporator 22.

[0033] like Figure 1 As shown, the molten salt heat storage subsystem 5 includes: a hot storage tank 51, a cold storage tank 52, a molten salt heat exchange component 53 and a hydrophobic expansion tank 54; The heat storage tank 51 is connected to the molten salt mixer 4 and is used to store hot molten salt and supply hot molten salt to the molten salt mixer 4; The cold storage tank 52 is connected to the molten salt mixer 4 and is used to store cold molten salt and supply cold molten salt to the molten salt mixer 4; The molten salt heat exchange component 53 is connected to the hot storage tank 51, the cold storage tank 52, the superheater 3 and the coal-fired power generation unit. The molten salt heat exchange component 53 is used to use the first superheated steam from the superheater 3 or the unit extraction steam extracted from the coal-fired power generation unit to heat the cold molten salt from the cold storage tank 52 into hot molten salt. The hot molten salt is sent to the hot storage tank 51 for storage. The first superheated steam or the unit extraction steam loses heat and becomes heat-depleted steam. The drain expansion tank 54 is used to recover the heat-depleted steam generated by the molten salt heat exchange component 53 .

[0034] The molten salt heat exchange assembly 53 includes: a main steam heat exchanger 531 and a plurality of auxiliary heat exchangers 532; The steam inlet of the main steam heat exchanger 531 is connected to the steam outlet of the superheater 3 and the steam extraction outlet of the coal-fired power generation unit, and the steam outlet of the main steam heat exchanger 531 is connected to the steam inlet of the hydrophobic expansion tank 54. The main steam heat exchanger 531 uses the first superheated steam or the main steam extracted from the coal-fired power generation unit as the unit extraction steam to heat the cold molten salt into hot molten salt, and the first superheated steam or the main steam loses heat and becomes heat-losing steam; The steam inlet of the auxiliary heat exchanger 532 is connected to the steam outlet of the superheater 3 and the extraction steam outlet of the coal-fired power generation unit. The steam outlet of the auxiliary heat exchanger 532 is connected to the steam inlet of the hydrophobic expansion tank 54. The auxiliary heat exchanger 532 uses the first superheated steam or the hot resteam and / or four-extraction steam extracted from the coal-fired power generation unit as the unit extraction steam to heat the cold molten salt into hot molten salt, and the hot resteam and four-extraction steam lose heat and become heat-losing steam.

[0035] The molten salt heat exchange component 53 also includes: a main steam condensing heat exchanger 533, which is arranged on the connecting pipe section between the main steam heat exchanger 531 and the drain expansion tank 54, and is used to use the deheated steam discharged from the main steam heat exchanger 531 to preheat the cold molten salt entering the main steam heat exchanger 531.

[0036] like Figure 1As shown, a main steam heat exchanger 531 and two auxiliary heat exchangers 532 are provided, the steam inlet of the main steam heat exchanger 531 is connected to the steam outlet of the superheater 3 through a pipeline, the steam outlet of the main steam heat exchanger 531 is connected to the steam inlet of the main steam condensing heat exchanger 533, the steam outlet of the main steam condensing heat exchanger 533 is connected to the steam inlet of the drain expansion tank 54 through a pipeline, the steam inlet of each auxiliary heat exchanger 532 is connected to the steam outlet of the superheater 3 through a pipeline, the steam outlet of the auxiliary heat exchanger 532 is connected to the steam inlet of the drain expansion tank 54 through a pipeline, the cold salt outlet of the cold storage tank 52 is connected to the condensing salt inlet of the main steam condensing heat exchanger 533, and the salt inlet of the molten salt mixer 4 The auxiliary salt inlet of the cold storage tank 52 is connected to the auxiliary salt inlet of each auxiliary heat exchanger 532 through a pipeline, the cold salt inlet of the cold storage tank 52 serves as the cold salt inlet of the molten salt heat storage subsystem 5, the cold salt inlet of the cold storage tank 52 is connected to the preheating salt outlet of the preheater 24 through a pipeline, the condensing salt outlet of the main steam condensing heat exchanger 533 is connected to the main salt inlet of the main steam heat exchanger 531 through a pipeline, the main salt outlet of the main steam heat exchanger 531 is connected to the hot salt inlet of the hot storage tank 51 through a pipeline, the auxiliary salt outlet of each auxiliary heat exchanger 523 is connected to the hot salt inlet of the hot storage tank 51 through a pipeline, the hot salt outlet of the hot storage tank 51 is connected to the salt inlet of the molten salt mixer 4 through a pipeline, and the salt outlet of the molten salt mixer 4 is connected to the superheater The superheated salt inlet of the superheater 3 is connected by a pipeline, and the superheated salt outlet of the superheater 3 is connected to the evaporation salt inlet of the evaporator 22 by a pipeline; the main steam heat exchanger 531 has a flow channel allowing steam to flow and a flow channel allowing molten salt to flow, the flow channel allowing steam to flow in the main steam heat exchanger 531 is defined as the main steam steam-water side, and the flow channel allowing molten salt to flow in the main steam heat exchanger 531 is defined as the main steam molten salt side, the auxiliary heat exchanger 532 has a flow channel allowing steam to flow and a flow channel allowing molten salt to flow, the flow channel allowing steam to flow in the auxiliary heat exchanger 532 is defined as the auxiliary steam-water side, and the flow channel allowing molten salt to flow in the auxiliary heat exchanger 532 is defined as the auxiliary molten salt side, the main steam condensing heat exchanger 5 33 has a flow channel allowing steam to flow and a flow channel allowing molten salt to flow. The flow channel allowing steam to flow in the main steam condensing heat exchanger 533 is defined as the condensing steam-water side, and the flow channel allowing molten salt to flow in the main steam condensing heat exchanger 533 is defined as the condensing steam-molten salt side. The steam-water side of the molten salt heat storage subsystem 5 is composed of the main steam-steam-water side of the main steam heat exchanger 531, the auxiliary steam-water side of the auxiliary heat exchanger 532, the condensing steam-water side of the main steam condensing heat exchanger 533, and the pipeline through which steam flows. The molten salt side of the molten salt heat storage subsystem 5 is composed of the main steam-molten salt side of the main steam heat exchanger 531, the auxiliary molten salt side of the auxiliary heat exchanger 532, the condensing steam-molten salt side of the main steam condensing heat exchanger 533, and the pipeline through which molten salt flows.

[0037] After the preheating of the molten salt heat release subsystem 1 and the molten salt heat storage subsystem 5 is completed, the circulating water pump 26 stops working. At this time, the cold storage tank 52 of the molten salt heat storage subsystem 5 supplies cold molten salt to the molten salt mixer 4, the auxiliary heat exchanger 532 and the main steam condensing heat exchanger 533, and the hot storage tank 51 supplies hot molten salt to the molten salt mixer 4. The cold molten salt and the hot molten salt are mixed in the molten salt mixer 4 to form a mixed molten salt. The mixed molten salt is sent to the superheater 3, and the temperature rise from the steam drum 21 Steam and the mixed molten salt exchange heat in the superheater 3. The heated steam absorbs the heat of the mixed molten salt and then heats up to become the first superheated steam. The mixed molten salt loses heat and becomes the first temperature-depleted molten salt, which flows through the molten salt side of the evaporator 22 and the molten salt side of the preheater 24 in sequence. The first superheated steam enters the main steam heat exchanger 531 and the auxiliary heat exchanger 532. The first superheated steam exchanges heat with the cold molten salt from the cold storage tank 52 in the main steam heat exchanger 531 and the auxiliary heat exchanger 532. The cold molten salt in the cold storage tank 52 is transported in four ways. One way of cold molten salt is sent to the molten salt mixer 4, another way is sent to the main steam heat exchanger 531, and the remaining two ways are sent to two auxiliary heat exchangers 532. After the cold molten salt exchanges heat with the first superheated steam in the auxiliary heat exchanger 532, the temperature rises to become hot molten salt and enters the hot storage tank 51 for storage, and the first superheated steam loses heat and becomes de-heated steam and enters the hydrophobic expansion tank 54; the cold molten salt sent to the main steam heat exchanger 531 exchanges heat with the first superheated steam in the main steam heat exchanger 531 to become hot molten salt and enter the hot storage tank 51 for storage, and the first superheated steam exchanges heat with the cold molten salt in the main steam heat exchanger 531 to become de-heated steam and enter the hydrophobic expansion tank 54. In order to make full use of The de-heated steam discharged from the main steam heat exchanger 531 is provided with a main steam condensing heat exchanger 533 between the main steam heat exchanger 531 and the drain expansion tank 54, and the cold molten salt sent to the main steam heat exchanger 531 is first sent to the main steam condensing heat exchanger 533, so that the cold molten salt first exchanges heat with the de-heated steam discharged from the main steam heat exchanger 531 in the main steam condensing heat exchanger 533, and the cold molten salt is preheated by the de-heated steam discharged from the main steam heat exchanger 531. The preheated cold molten salt then enters the main steam heat exchanger 531 to exchange heat with the first superheated steam. The de-heated steam discharged from the main steam heat exchanger 531 exchanges heat with the cold molten salt in the main steam condensing heat exchanger 533 to become low-temperature de-heated steam with a temperature lower than that of the de-heated steam, and the low-temperature de-heated steam enters the drain expansion tank 54. A stop valve 55 is provided on the connecting pipe between the main steam heat exchanger 531 and the drain expansion tank 54 to control the flow state of the de-heated steam in the connecting pipe.

[0038] When extracting steam from a coal-fired power generation unit to heat cold molten salt, the steam from the unit enters the main steam heat exchanger 531 and the auxiliary heat exchanger 532 to exchange heat with the cold molten salt so that the cold molten salt absorbs the heat extracted from the unit and becomes hot molten salt, thereby storing the heat of the steam from the unit. The main steam from the coal-fired power generation unit enters the main steam heat exchanger 531 to exchange heat with the cold molten salt. After the main steam exchanges heat with the cold molten salt, it becomes heat-depleted steam with a higher temperature. In order to make full use of the latent heat of the heat-depleted steam discharged from the main steam heat exchanger 531, A main steam condensing heat exchanger 533 is provided. The cold molten salt first enters the main steam condensing heat exchanger 533 before entering the main steam heat exchanger 531. The cold molten salt exchanges heat with the deheated steam discharged from the main steam heat exchanger 531 in the main steam condensing heat exchanger 533. The cold molten salt is preheated by the deheated steam discharged from the main steam heat exchanger 531. The preheated cold molten salt then enters the main steam heat exchanger 531 to exchange heat with the first superheated steam. The hot resteam and / or four-extraction steam of the coal-fired power generation unit are extracted and enter the auxiliary heat exchanger 532 to exchange heat with the cold molten salt.

[0039] like Figure 1 As shown, in order to facilitate pipeline layout, a main pipeline 31 and multiple branch pipelines 32 are set at the steam outlet of the superheater 3. The main pipeline 31 has multiple outlets, each outlet is connected to a branch pipeline 32, and the steam inlet of the main steam heat exchanger 531 and the steam inlet of the auxiliary heat exchanger 532 are respectively connected to a branch pipeline 32. The first superheated steam discharged from the steam outlet of the superheater 3 first flows through the main pipeline 31, and then enters the main steam heat exchanger 531 and the auxiliary heat exchanger 532 through the branch pipeline 32. In order to facilitate the control of the flow state of the first superheated steam in the main pipeline 31, a second stop valve 72 is set on the main pipeline 31.

[0040] The steam extraction outlet of the coal-fired generator set is connected to the steam inlet of the main steam heat exchanger 531 and the steam inlet of the auxiliary heat exchanger 532 through pipelines, and a third stop valve 73 is arranged on the pipeline between the steam extraction outlet of the coal-fired generator set and the steam inlet of the main steam heat exchanger 531, and a fourth stop valve 74 is arranged on the pipeline between the steam extraction outlet of the coal-fired generator set and the steam inlet of the auxiliary heat exchanger 532.

[0041] In order to recover the first superheated steam discharged from the superheater 3 during the preheating process of the working medium circulation component 2 , it also includes: a steam supply header 6 for recovering the excess first superheated steam discharged from the superheater 3 .

[0042] Another aspect of the present invention provides a cold start method for a thermoelectric decoupled steam-molten salt heat exchange system, which is used to start the thermoelectric decoupled steam-molten salt heat exchange system described in any one of the above items, and the cold start method comprises: S1) preheating step: heating the water working medium in the drum by superheated steam to generate heated steam and heated water, the heated water continues to flow in the closed circulation loop as the water working medium to preheat the steam-water side of the working medium circulation component, the heated steam flows through the superheater and then flows on the steam-water side of the molten salt heat storage subsystem, the steam-water side of the molten salt heat storage subsystem and the steam-water side of the superheater are preheated by the heated steam, and at the same time, the molten salt side of the molten salt heat release subsystem and the molten salt side of the molten salt heat storage subsystem are preheated by electric tracing, until the temperature of the steam-water side of the working medium circulation component, the steam-water side of the molten salt heat storage subsystem and the steam-water side of the superheater reaches the first set temperature, the temperature of the molten salt side of the molten salt heat release subsystem and the molten salt side of the molten salt heat storage subsystem reaches the second set temperature, and the preheating is completed, wherein the steam-water side refers to the pipe or flow channel through which the working medium water or steam flows under normal operating conditions, and the molten salt side refers to the pipe or flow channel through which the molten salt flows under normal operating conditions; S2) semi-startup step: hot molten salt and cold molten salt are supplied to the molten salt mixer through the molten salt heat storage subsystem to form a mixed molten salt, the mixed molten salt exchanges heat with the heated steam in the superheater, the mixed molten salt loses heat to become the first temperature-losing molten salt, the heated steam is heated to become the first superheated steam, the first superheated steam flows on the steam-water side of the molten salt heat storage subsystem and exchanges heat with the cold molten salt, the first superheated steam flows on the steam-water side of the molten salt heat storage subsystem to further heat the steam-water side of the molten salt heat storage subsystem, the cold molten salt of the molten salt heat storage subsystem exchanges heat with the first superheated steam and then heats up and flows through the molten salt side of the molten salt heat storage subsystem, until the temperature of the first superheated steam discharged from the superheater reaches the third set temperature, and at the same time, the temperature of the molten salt side of the molten salt heat storage subsystem reaches the fourth set temperature, and the semi-startup is completed, that is, the molten salt heat release subsystem is started up; S3) Startup step: extract the extraction steam of the coal-fired power generation unit to heat the cold molten salt into hot molten salt, until the cold molten salt and the extraction steam of the unit achieve stable heat exchange, and the molten salt heat storage subsystem is started.

[0043] In step S2), the mixed molten salt and the heated steam are heat exchanged in a superheater, including: The flow rate of hot molten salt fed into the molten salt mixer is adjusted according to the heating rate of the superheater until the temperature of the first superheated steam discharged from the superheater reaches the third set temperature, and the cold molten salt is stopped from being fed to the molten salt mixer, while the hot molten salt is continued to be fed to the molten salt mixer.

[0044] In step S3), extracting steam from the coal-fired power generation unit to heat the cold molten salt to form hot molten salt includes: The unit extraction steam extracted from the coal-fired power generation unit is cooled and depressurized to a fifth set temperature, and the unit extraction steam cooled and depressurized to the fifth set temperature is used to heat the cold molten salt to become hot molten salt.

[0045] When starting the thermoelectric decoupled steam-molten salt heat exchange system in cold state, first preheat the thermoelectric decoupled steam-molten salt heat exchange system, such as Figure 1As shown, the second stop valve 72 is opened to maintain the pipeline connection between the outlet of the superheater 3 and the main steam heat exchanger 531 and the auxiliary heat exchanger 532, and the stop valve 55, the third stop valve 73 and the fourth stop valve 74 are closed. Start the feed water pump 25 and the circulating water pump 26, and the water working medium flows in the closed circulation loop 20. The water working medium flows out of the working medium deaerator 23, passes through the preheater 24, the steam drum 21, and the evaporator 22, and then returns to the working medium deaerator 23. Under normal pressure, superheated steam is supplied to the steam drum 21 through the steam supply device 10. The water working medium flowing in the closed circulation loop 20 is heated by the superheated steam. Superheated steam is continuously supplied to the steam drum 21. The water working medium exchanges heat with the superheated steam. The temperature of the water working medium flowing in the closed circulation loop 20 gradually increases until heated steam is generated and enters the superheater 3 and the steam-water side of the subsequent molten salt heat storage subsystem 5. At the same time, the molten salt heat release subsystem 1 and the molten salt side of the molten salt heat storage subsystem 5 are preheated by the electric heater.

[0046] Superheated steam is continuously supplied to the steam drum 21 through the steam supply device 10 to heat the water working medium to generate heated steam. The closed circulation loop 20 generates heated steam with gradually increasing temperature and pressure, which enters the superheater 3 and the steam-water side of the molten salt heat storage subsystem 5. At the same time, the heating rate of the molten salt heat release subsystem 1 and the molten salt side of the molten salt heat storage subsystem 5 is controlled by adjusting the electric heating power until the steam-water side of the molten salt heat release subsystem 1 and the molten salt heat storage subsystem 5 reaches the first set temperature and the molten salt side of the molten salt heat release subsystem 1 and the molten salt heat storage subsystem 5 reaches the second set temperature, and the thermoelectric decoupled steam-molten salt heat exchange system completes preheating.

[0047] After preheating is completed, the first stop valve 71 is closed, the circulating water pump 26 is closed, and the electric tracing on the molten salt side of the molten salt heat release subsystem 1 and the molten salt heat storage subsystem 5 is closed. The cold storage tank 52 delivers cold molten salt to the molten salt mixer 4 to enter the molten salt heat release subsystem. After the molten salt circulation is successfully established, the flow rate of the water medium pumped to the drum 21 is adjusted by the feed water pump 25, and the flow rate of the water medium pumped from the steam supply manifold of the coal-fired unit or the main engine deaerator to the working medium deaerator 23 can also be adjusted to supplement the water medium flow rate entering the working medium deaerator 23, ensuring that the liquid level of the water medium in the working medium deaerator 23 is at a normal level, and the inlet water temperature of the preheater 24 is not lower than the first set temperature. Afterwards, the hot storage tank 51 delivers hot molten salt to the molten salt mixer 4, and the flow rate of the hot molten salt entering the molten salt mixer 4 is adjusted according to the temperature rise rate control requirements of the heat exchange component in the system, the cold molten salt and the hot molten salt are mixed in the molten salt mixer 4 to form a mixed molten salt, and the mixed molten salt is sent to the superheater 3 to exchange heat with the heated steam in the superheater 3, and then, the flow rate of the hot molten salt sent from the hot storage tank 51 to the molten salt mixer 4 is gradually increased, thereby increasing the temperature of the formed mixed molten salt. The increase in the temperature of the mixed molten salt correspondingly increases the temperature of the first superheated steam, and gradually establishes a stable heat exchange state in the molten salt heat release subsystem 1 until the superheater 3 comes out. The first superheated steam that meets the third set temperature can be continuously and stably generated at the mouth; the cold storage tank 52 not only delivers cold molten salt to the molten salt mixer 4, but also delivers cold molten salt to the main steam heat exchanger 531 and the auxiliary heat exchanger 532. The cold molten salt is heated up to become hot molten salt after heat exchange with the first superheated steam from the superheater 3 in the main steam heat exchanger 531 and the auxiliary heat exchanger 532, and enters the hot storage tank 51 for storage. At this time, the semi-startup is completed, and the molten salt heat release subsystem 1 is started up in the semi-startup state, the steam-water side of the molten salt heat storage subsystem 5 is preheated to the third set temperature, and the molten salt side of the molten salt heat storage subsystem 5 is preheated to the fourth set temperature.

[0048] After completing the semi-startup of the thermoelectric decoupled steam-molten salt heat exchange system, close the second stop valve 72, open the stop valve 55, the third stop valve 73 and the fourth stop valve 74, and after the unit extraction steam of the coal-fired power generation unit is cooled and depressurized to the fifth set temperature, the main steam serving as the unit extraction steam is introduced into the main steam heat exchanger 531 for heat exchange with the cold molten salt, the hot re-steam serving as the unit extraction steam is introduced into an auxiliary heat exchanger 532 for heat exchange with the cold molten salt, and the fourth extraction steam serving as the unit extraction steam is introduced into another auxiliary heat exchanger 532 for heat exchange with the cold molten salt, thereby further increasing the steam-water side temperature of the molten salt heat storage subsystem 5 to the operating temperature, thereby further increasing the temperature of the components and pipelines in the working fluid circulation component 2 and the molten salt heat storage subsystem 5. At the same time, the cold storage tank 52 transports cold molten salt to the main steam heat exchanger 531 and the auxiliary heat exchanger 532. The cold molten salt exchanges heat with the unit extraction steam in the main steam heat exchanger 531 and the auxiliary heat exchanger 532 and gradually establishes a stable heat exchange state. The heated hot molten salt enters the hot storage tank 51 for storage, and the cold start-up of the thermoelectric decoupled steam-molten salt heat exchange system is completed.

[0049] It should be noted that the selection of the first set temperature and the second set temperature must ensure that the temperature difference on the shell and tube side of the heat exchanger is within a reasonable range and effectively prevent the cold molten salt from solidifying after entering the system; the second set temperature is the electric heating preheating temperature; the third set temperature is the steam production temperature under normal operating conditions of the molten salt heat release subsystem, and the fourth set temperature must maintain a certain end difference with the third set temperature; the value of the fifth set temperature is selected according to the design operating conditions of the heat exchanger of the molten salt heat exchange component, and at the same time, it must ensure that the temperature difference between the tube side and the shell side of each equipment is within a reasonable range.

[0050] The thermoelectric decoupled steam-molten salt heat exchange system provided by the present invention supplies superheated steam to the steam drum of the working medium circulation component through a steam supply device, and the superheated steam entering the steam drum heats the water working medium entering the steam drum through a closed circulation loop. After the water working medium is heated, it becomes heated steam and heated water, and the heated steam is discharged from the steam drum. The heated water can continue to flow in the closed circulation loop as the water working medium after being discharged from the steam drum. The temperature of the heated water is higher than the temperature of the water working medium entering the steam drum. In this way, heated water is continuously discharged from the steam drum to flow in the closed circulation loop, so that the temperature of the water working medium flowing in the closed circulation loop gradually increases, and then the closed circulation loop is supplied with heat by the gradually heated water working medium. Preheating, the heated steam discharged from the steam drum enters the superheater, and enters the molten salt heat storage subsystem through the superheater, so that the steam-water side of the superheater and the molten salt heat storage subsystem is preheated by the heated steam, and the heated steam can also exchange heat with the mixed molten salt entering the superheater in the superheater, and the heated steam absorbs the heat of the mixed molten salt and heats up to become the first superheated steam, and the first superheated steam enters the molten salt heat storage subsystem to further heat the steam-water side of the molten salt heat storage subsystem, and the molten salt heat storage subsystem can also use the first superheated steam or the unit extraction steam to heat the cold molten salt in the molten salt heat storage subsystem to become hot molten salt, and at the same time preheat the molten salt side of the molten salt heat storage subsystem by the heated molten salt. In this way, during the cold start-up process of the thermoelectric decoupled steam-molten salt heat exchange system, steam is used to preheat the thermoelectric decoupled steam-molten salt heat exchange system, thereby reducing the use of electric energy. This solves the problems in the prior art of high cost of using electric heaters for startup preheating of the thermoelectric decoupled molten salt heat exchange system and the lack of a cold start-up method for the molten salt heat storage system that uses steam as a heat source to heat the molten salt. This improves energy utilization, reduces operating costs, reduces thermal shock, and extends equipment life.

[0051] The optional implementation modes of the embodiments of the present invention are described in detail above in conjunction with the accompanying drawings. However, the embodiments of the present invention are not limited to the specific details in the above implementation modes. Within the technical concept of the embodiments of the present invention, various simple modifications can be made to the technical scheme of the embodiments of the present invention, and these simple modifications all belong to the protection scope of the embodiments of the present invention.

[0052] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. To avoid unnecessary repetition, the embodiments of the present invention will not further describe various possible combinations.

[0053] In addition, various implementation modes of the embodiments of the present invention may be arbitrarily combined, and as long as they do not violate the concept of the embodiments of the present invention, they should also be regarded as the contents disclosed by the embodiments of the present invention.

Claims

1. A thermoelectric decoupled steam-molten salt heat exchange system connected to a coal-fired power generation unit, characterized in that: include: A molten salt heat release subsystem (1), a molten salt mixer (4) and a molten salt heat storage subsystem (5); The molten salt heat release subsystem (1) comprises: A steam supply device (10) for providing superheated steam as a heat source; The working medium circulation component (2) comprises a closed circulation loop (20) and a steam drum (21) arranged on the closed circulation loop (20), wherein a water working medium flows in the closed circulation loop (20), and the steam drum (21) is connected to a steam supply device (10), and the water working medium entering the steam drum (21) through the closed circulation loop (20) is heated by superheated steam provided by the steam supply device (10) to generate heated steam and heated water, and the heated water continues to flow in the closed circulation loop (20) as the water working medium, and the heated steam is discharged through a steam outlet of the steam drum (21); The superheater (3) is connected to the steam drum (21) and the molten salt mixer (4); the heated steam from the steam drum (21) and the mixed molten salt from the molten salt mixer (4) are heat exchanged in the superheater (3); the heated steam after the heat exchange is heated to become first superheated steam, and the mixed molten salt loses heat to become first dehumidified molten salt; The molten salt mixer (4) is connected to the molten salt heat storage subsystem (5) and is used to mix cold molten salt from the molten salt heat storage subsystem (5) with hot molten salt to form mixed molten salt; The molten salt heat storage subsystem (5) is connected to the coal-fired power generation unit and the superheater (3) of the molten salt heat release subsystem (1) and is used to store cold molten salt and hot molten salt.

2. The thermoelectric decoupled steam-molten salt heat exchange system according to claim 1, characterized in that: The working fluid circulation component (2) further comprises: an evaporator (22), a working fluid deaerator (23) and a preheater (24); The working fluid deaerator (23), the preheater (24), the steam drum (21) and the evaporator (22) are connected in sequence through pipelines to form a closed circulation loop (20); The working medium outlet of the working medium deaerator (23) is connected to the water inlet of the steam drum (21) for supplying water working medium to the steam drum (21); The first inlet and outlet (220) and the second inlet and outlet (221) of the evaporator (22) are both connected to the water outlet of the drum (21) to form an auxiliary circulation loop (9); the second inlet and outlet (221) of the evaporator (22) is also connected to the working fluid inlet of the working fluid deaerator (23); the evaporation salt inlet of the evaporator (22) is connected to the superheating salt outlet of the superheater (3); the evaporation salt outlet of the evaporator (22) is connected to the preheating salt inlet of the preheater (24); the evaporator (22) can utilize the heated water from the drum (21) to exchange heat with the first dethermal molten salt from the superheater (3); the first dethermal molten salt becomes the second dethermal molten salt after losing heat and enters the preheater (24); The preheater (24) is located on a loop section between the working medium outlet of the working medium deaerator (23) and the water inlet of the drum (21); the preheating salt outlet of the preheater (24) is connected to the molten salt heat storage subsystem (5); the preheater (24) uses the second dethermal molten salt from the evaporator (22) to preheat the working medium water supplied to the drum (21) by the working medium deaerator (23).

3. The thermoelectric decoupled steam-molten salt heat exchange system according to claim 2, characterized in that: The working fluid circulation component (2) further comprises: a water supply pump (25) and a circulating water pump (26); The water feed pump (25) is arranged on the closed circulation loop (20), located on the loop section between the working medium deaerator (23) and the preheater (24), and is used to feed the water working medium in the working medium deaerator (23) into the preheater (24); The circulating water pump (26) is arranged on the closed circulation loop (20), located on the loop section between the evaporator (22) and the working fluid deaerator (23), and is used to pump the heated water in the evaporator (22) as the water working fluid into the working fluid deaerator (23).

4. The thermoelectric decoupled steam-molten salt heat exchange system according to claim 2, characterized in that: The molten salt heat storage subsystem (5) comprises: a hot storage tank (51), a cold storage tank (52), a molten salt heat exchange component (53) and a hydrophobic expansion tank (54); The heat storage tank (51) is connected to the molten salt mixer (4) and is used to store hot molten salt and supply hot molten salt to the molten salt mixer (4); The cold storage tank (52) is connected to the molten salt mixer (4) and the preheater (24) and is used to store cold molten salt and supply cold molten salt to the molten salt mixer (4); The molten salt heat exchange component (53) is connected to the hot storage tank (51), the cold storage tank (52), the superheater (3) and the coal-fired power generation unit. The molten salt heat exchange component (53) is used to use the first superheated steam from the superheater (3) or the unit extraction steam extracted from the coal-fired power generation unit to heat the cold molten salt from the cold storage tank (52) into hot molten salt. The hot molten salt is sent to the hot storage tank (51) for storage. The first superheated steam or the unit extraction steam loses heat and becomes heat-depleted steam. The drain expansion tank (54) is used to recover the lost heat steam.

5. The thermoelectric decoupled steam-molten salt heat exchange system according to claim 4, characterized in that: The molten salt heat exchange component (53) comprises: a main steam heat exchanger (531) and a plurality of auxiliary heat exchangers (532); The steam inlet of the main steam heat exchanger (531) is connected to the steam outlet of the superheater (3) and the steam extraction outlet of the coal-fired power generation unit, and the steam outlet of the main steam heat exchanger (531) is connected to the steam inlet of the drain expansion tank (54). The main steam heat exchanger (531) uses the first superheated steam or the main steam extracted from the coal-fired power generation unit as the unit extraction steam to heat the cold molten salt to become hot molten salt, and the first superheated steam or the main steam loses heat to become heat-losing steam. The steam inlet of the auxiliary heat exchanger (532) is connected to the steam outlet of the superheater (3) and the steam extraction outlet of the coal-fired power generation unit, and the steam outlet of the auxiliary heat exchanger (532) is connected to the steam inlet of the drain expansion tank (54). The auxiliary heat exchanger (532) uses the first superheated steam or the hot re-steam and / or the four-extraction steam extracted from the coal-fired power generation unit as the unit extraction steam to heat the cold molten salt to become hot molten salt, and the hot re-steam and the four-extraction steam lose heat to become heat-losing steam.

6. The thermoelectric decoupled steam-molten salt heat exchange system according to claim 5, characterized in that: The molten salt heat exchange component (53) further comprises: a main steam condensing heat exchanger (533), which is arranged on the connecting pipe between the main steam heat exchanger (531) and the drain expansion tank (54) and is used to preheat the cold molten salt entering the main steam heat exchanger (531) by using the deheated steam discharged from the main steam heat exchanger (531).

7. The thermoelectric decoupled steam-molten salt heat exchange system according to claim 1, characterized in that: Also includes: The steam supply header (6) is used to recover the excess first superheated steam discharged from the superheater (3).

8. A cold start method for a thermoelectric decoupled steam-molten salt heat exchange system, used to start the thermoelectric decoupled steam-molten salt heat exchange system according to any one of claims 1 to 7, characterized in that: include: S1) preheating step: heating the water working medium in the drum by superheated steam to generate heated steam and heated water, the heated water continues to flow in the closed circulation loop as the water working medium to preheat the steam-water side of the working medium circulation component, the heated steam flows through the superheater and then flows on the steam-water side of the molten salt heat storage subsystem, the steam-water side of the molten salt heat storage subsystem and the steam-water side of the superheater are preheated by the heated steam, and at the same time, the molten salt side of the molten salt heat release subsystem and the molten salt side of the molten salt heat storage subsystem are preheated by electric tracing, until the temperature of the steam-water side of the working medium circulation component, the steam-water side of the molten salt heat storage subsystem and the steam-water side of the superheater reaches the first set temperature, the temperature of the molten salt side of the molten salt heat release subsystem and the molten salt side of the molten salt heat storage subsystem reaches the second set temperature, and the preheating is completed, wherein the steam-water side refers to the pipe or flow channel through which the working medium water or steam flows under normal operating conditions, and the molten salt side refers to the pipe or flow channel through which the molten salt flows under normal operating conditions; S2) semi-startup step: hot molten salt and cold molten salt are supplied to the molten salt mixer through the molten salt heat storage subsystem to form a mixed molten salt, the mixed molten salt exchanges heat with the heated steam in the superheater, the mixed molten salt loses heat to become the first temperature-losing molten salt, the heated steam is heated to become the first superheated steam, the first superheated steam flows on the steam-water side of the molten salt heat storage subsystem and exchanges heat with the cold molten salt, the first superheated steam flows on the steam-water side of the molten salt heat storage subsystem to further heat the steam-water side of the molten salt heat storage subsystem, the cold molten salt of the molten salt heat storage subsystem exchanges heat with the first superheated steam and then heats up and flows through the molten salt side of the molten salt heat storage subsystem, until the temperature of the first superheated steam discharged from the superheater reaches the third set temperature, and at the same time, the temperature of the molten salt side of the molten salt heat storage subsystem reaches the fourth set temperature, and the semi-startup is completed, that is, the molten salt heat release subsystem is started up; S3) Startup step: extract the extraction steam of the coal-fired power generation unit to heat the cold molten salt into hot molten salt, until the cold molten salt and the extraction steam of the unit achieve stable heat exchange, and the molten salt heat storage subsystem is started.

9. The cold start method according to claim 8, characterized in that: In step S2), the mixed molten salt and the heated steam are heat exchanged in a superheater, including: The flow rate of hot molten salt fed into the molten salt mixer is adjusted according to the heating rate of the superheater until the temperature of the first superheated steam discharged from the superheater reaches the third set temperature, and the cold molten salt is stopped from being fed to the molten salt mixer, while the hot molten salt is continued to be fed to the molten salt mixer.

10. The cold start method according to claim 9, characterized in that: In step S3), extracting steam from the coal-fired power generation unit to heat the cold molten salt to form hot molten salt includes: The unit extraction steam extracted from the coal-fired power generation unit is cooled and depressurized to a fifth set temperature, and the unit extraction steam cooled and depressurized to the fifth set temperature is used to heat the cold molten salt to become hot molten salt.

Images