A high-temperature molten salt energy storage and heat release system for absorbing new energy sources and its application method

Abstract

This invention discloses a high-temperature molten salt energy storage and heat release system and its application method for absorbing new energy sources. The method includes: pumping 290°C low-temperature molten salt into a low-pressure and / or high-pressure molten salt electric heater via a cold salt pump to heat it to 560°C high-temperature molten salt, which then enters a hot salt tank; heating demineralized water to 80°C via a low-pressure feedwater heater and sending it to a deaerator; further heating the demineralized water to 160°C via the deaerator and pumping it into a high-pressure feedwater heater; heating the demineralized water to 255°C to become demineralized water steam, which enters a steam generator; performing a heat exchange process between the demineralized water steam and the high-temperature molten salt to generate 350°C superheated steam; and pumping the 560°C high-temperature molten salt from the hot salt tank into the steam generator via a hot salt pump to exchange heat with the demineralized water steam, reducing the temperature to 290°C, and returning it to the cold salt tank. The ability to supply high-pressure steam through molten salt energy storage aligns with the characteristics and advantages of the industry, and has a reference and guiding role in the demonstration and application of energy storage and new energy industries.

Description

Technical Field

[0001] This invention relates to the field of energy storage technology, specifically to a high-temperature molten salt energy storage and heat release system and its application method for absorbing new energy sources. Background Technology

[0002] Currently, molten salt energy storage systems generally use low-voltage electric heaters to obtain electricity from the public power grid to heat the ternary molten salt. Subsequently, through energy exchange between the molten salt and water vapor, a small flow of low-pressure steam is generated and supplied. At the same time, in the coal-fired power industry, low-voltage electric heaters and molten salt systems are also used for flexibility retrofitting to improve the peak-shaving capacity of thermal power units.

[0003] However, new energy sources such as wind and solar power are characterized by randomness and intermittency, and their large-scale grid connection has negatively impacted the safe and stable operation of the power grid. Specifically, this manifests as insufficient peak-shaving capacity of new energy sources and the occurrence of power curtailment during peak midday power generation periods, affecting the absorption of new energy sources.

[0004] Therefore, those skilled in the art urgently need to develop a new technical solution to address the above problems. Summary of the Invention

[0005] To overcome the problems existing in related technologies, this invention discloses a high-temperature molten salt energy storage heat release system and its application method for absorbing new energy sources. Compared with other energy storage methods, molten salt energy storage for supplying high-pressure steam has advantages in terms of economy and safety, and can meet the characteristics and advantages of the industry, thus playing a reference and leading role in the demonstration application of energy storage and new energy industries.

[0006] According to a first aspect of the present invention, a method for applying a high-temperature molten salt energy storage and heat release system for absorbing new energy sources is provided. The system includes: a high-temperature molten salt heat storage subsystem and a high-temperature molten salt heat release subsystem; the high-temperature molten salt heat storage subsystem includes: a low-pressure molten salt electric heater, a high-pressure molten salt electric heater, a cold salt tank, a hot salt tank, and a cold salt pump; the high-temperature molten salt heat release subsystem includes: a demineralized water tank, a low-pressure feedwater heater, a deaerator, an electric feedwater pump, a high-pressure feedwater heater, and a steam generator.

[0007] The application method includes:

[0008] The cold salt pump pumps low-temperature molten salt at 290°C into the low-pressure molten salt electric heater and / or the high-pressure molten salt electric heater for heating, raising the temperature to 560°C to become high-temperature molten salt, which then enters the hot salt tank.

[0009] The demineralized water in the demineralized water tank at 20°C is heated to 80°C by the low-pressure feed water heater, and the demineralized water at 80°C enters the deaerator.

[0010] The deaerator further heats the 80°C demineralized water to 160°C, and the electric feed water pump pumps the 160°C demineralized water into the high-pressure feed water heater.

[0011] The demineralized water at 160°C is heated to 255°C by the high-pressure feedwater heater to become demineralized water steam, which then enters the steam generator.

[0012] The demineralized steam and the high-temperature molten salt are exchanged through the steam generator. The 255°C demineralized steam is then used to generate 350°C superheated steam to supply steam to the outside.

[0013] The hot salt pump pumps molten salt at 560°C from the hot salt tank into the steam generator to exchange heat with the demineralized water steam. The temperature of the molten salt is reduced to 290°C, becoming low-temperature molten salt, and then returned to the cold salt tank.

[0014] Optionally, the steam generator includes: a preheater, an evaporator, and a superheater;

[0015] The application method includes:

[0016] The 255°C demineralized water steam sequentially enters the preheater, evaporator and superheater, and after exchanging heat with the high-temperature molten salt, generates 350°C superheated steam.

[0017] The hot salt pump pumps molten salt at 560°C from the hot salt tank into the superheater to exchange heat with demineralized water steam. The temperature of the molten salt decreases to 523°C, and then it enters the evaporator to exchange heat with the demineralized water steam. The temperature of the molten salt at 523°C continues to decrease to 323°C. The molten salt at 323°C enters the preheater to exchange heat with the demineralized water steam. The temperature of the molten salt at 323°C decreases to approximately 290°C, becoming low-temperature molten salt, and is returned to the cold salt tank.

[0018] Optionally, the low-pressure molten salt electric heater and the high-pressure molten salt electric heater, along with the electricity used to absorb photovoltaic power, heat the low-temperature molten salt, converting electrical energy into heat energy.

[0019] Optionally, the number of low-pressure molten salt electric heaters is 8, and the number of high-pressure molten salt electric heaters is 5. The step of pumping 290°C low-temperature molten salt into the low-pressure molten salt electric heaters and / or the high-pressure molten salt electric heaters for heating via the cold salt pump includes:

[0020] When the instantaneous power of the photovoltaic is lower than the preset power threshold, molten salt at 290°C is pumped into the low-pressure molten salt electric heater by a cold salt pump for heating.

[0021] When the instantaneous power of the photovoltaic system is higher than or equal to a preset power threshold, molten salt at 290°C is pumped into n high-pressure molten salt electric heaters via a cold salt pump for heating. The n high-pressure molten salt electric heaters should simultaneously satisfy both the first and second conditions.

[0022] The first condition is: , This indicates the number of high-pressure molten salt electric heaters started at time t. This represents the instantaneous power of the photovoltaic system at time t. Indicates the preset power threshold. Indicates the step parameters;

[0023] The second condition is: , This indicates the number of high-pressure molten salt electric heaters that were started at the previous moment. This indicates the hysteresis bandwidth.

[0024] Optionally, a feedwater electric heater is provided at the outlet of the preheater;

[0025] If the temperature of the demineralized steam entering the preheater is below 255°C, the feedwater electric heater is activated to heat the demineralized steam entering the preheater to 255°C.

[0026] According to a second aspect of the embodiments disclosed in this invention, a high-temperature molten salt energy storage and heat release system for absorbing new energy sources is provided, the system comprising: a high-temperature molten salt heat storage subsystem and a high-temperature molten salt heat release subsystem;

[0027] The high-temperature molten salt thermal storage subsystem includes: a low-pressure molten salt electric heater, a high-pressure molten salt electric heater, a cold salt tank, a hot salt tank, and a cold salt pump, wherein the cold salt tank, the cold salt pump, the low-pressure molten salt electric heater / high-pressure molten salt electric heater, and the hot salt tank are connected in sequence.

[0028] The high-temperature molten salt exothermic subsystem includes: a demineralized water tank, a low-pressure feedwater heater, a deaerator, an electric feedwater pump, a high-pressure feedwater heater, and a steam generator, which are connected in sequence.

[0029] Optionally, the steam generator includes a preheater, an evaporator, and a superheater connected in sequence.

[0030] Optionally, the cold salt pump is a vertically suspended centrifugal pump structure;

[0031] The cold salt pump is supported on the top of the cold salt tank near the tank wall, and the pump head of the cold salt pump is immersed in the low-temperature molten salt in the cold salt tank to pump the low-temperature molten salt into the low-pressure molten salt electric heater / high-pressure molten salt electric heater.

[0032] Optionally, the number of demineralized water tanks is two, each with a capacity of 50m³. 3 Demineralized water tank and 1 100m 3 The demineralized water tank.

[0033] Optionally, the heating steam in the low-pressure feedwater heater and deaerator comes from recovered auxiliary steam.

[0034] In summary, the technical solution disclosed in this invention can bring the following beneficial effects:

[0035] (1) By increasing the voltage level of the electric heater from low voltage to 6kV high voltage, the current of the equipment is reduced, thereby helping the equipment to develop towards larger size per unit area and improving the overall efficiency and stability of the system.

[0036] (2) The system can absorb up to 500MW of new energy power per day and about 810 million kWh of new energy (such as photovoltaic) power per year, which effectively improves the absorption capacity of new energy, reduces the phenomenon of power curtailment, and promotes the utilization of renewable energy.

[0037] (3) The system can continuously generate high-pressure steam at 8MPa and 350℃, with a maximum steam supply of 300t / h and an annual supply of approximately 953,000 tons of green high-pressure steam. This alleviates the tight steam supply situation in industrial parks that require high-pressure steam, while reducing coal combustion by approximately 340,000 tons and significantly reducing carbon dioxide emissions, thus demonstrating significant environmental benefits.

[0038] (4) The molten salt energy storage system designed in this system has a heat storage time of 4 hours and can be charged and discharged simultaneously, which has high flexibility. At the same time, compared with other energy storage methods, molten salt energy storage for high-pressure steam is more economical, which can reduce operating costs and improve economic benefits.

[0039] Other features and advantages disclosed in this invention will be described in detail in the following detailed description section. Attached Figure Description

[0040] The accompanying drawings are provided to further illustrate the present disclosure and form part of the specification. They are used together with the following detailed description to explain the present disclosure, but do not constitute a limitation thereof. In the drawings:

[0041] Figure 1 This is a schematic flowchart illustrating an application method of a high-temperature molten salt energy storage and heat release system for absorbing new energy sources, according to an exemplary embodiment.

[0042] Figure 2This is a structural block diagram of a high-temperature molten salt energy storage and heat release system for absorbing new energy sources, according to an exemplary embodiment.

[0043] Figure 3 It is based on Figure 1 The diagram shows a flow chart of a demineralized water heating process in a steam generator. Detailed Implementation

[0044] The specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are for illustration and explanation only and are not intended to limit the scope of the present disclosure.

[0045] Figure 1 This is a schematic flowchart illustrating an application method of a high-temperature molten salt energy storage and heat release system for absorbing new energy sources, according to an exemplary embodiment. Figure 1 As shown, a high-temperature molten salt energy storage and heat release system for absorbing new energy sources is applied. The system includes a high-temperature molten salt heat storage subsystem and a high-temperature molten salt heat release subsystem. The high-temperature molten salt heat storage subsystem includes a low-pressure molten salt electric heater, a high-pressure molten salt electric heater, a cold salt tank, a hot salt tank, and a cold salt pump. The high-temperature molten salt heat release subsystem includes a demineralized water tank, a low-pressure feedwater heater, a deaerator, an electric feedwater pump, a high-pressure feedwater heater, and a steam generator.

[0046] like Figure 2 As shown, the high-temperature molten salt thermal storage subsystem is a key component of this system. It uses a binary molten salt (40% KNO3 + 60% NaNO3) as the thermal storage medium. This molten salt has an operating temperature range of 260℃-580℃, an effective thermal storage capacity of 19,900 tons, and exhibits good fluidity, economy, and stability. The other component of this system, the high-temperature molten salt exothermic subsystem, includes a hot salt pump and a molten salt-steam generator, used to release heat from the molten salt to generate superheated steam. The high-temperature molten salt exothermic subsystem is equipped with one large and one small demineralized water tank (considering auxiliary equipment cooling), with a total capacity of 150 m³. 3 Two demineralized water pumps (one operational, one standby), one low-pressure heater, and one unit with an effective volume of 90m³. 3 The system includes a deaerator with a deoxygenation efficiency of 370t / h, two 0% electric variable frequency feedwater pumps and one 50% fixed frequency feedwater pump, one high-pressure feedwater heater, one low-pressure feedwater heater, two 50% capacity steam generators (including preheaters, evaporators, steam drums and superheaters), and three 50% capacity hot brine pumps (two in operation and one on standby). The molten brine pumps are frequency-controlled.

[0047] Specifically, the application method includes:

[0048] In step 101, the low-temperature molten salt at 290°C is pumped into the low-pressure molten salt electric heater and / or the high-pressure molten salt electric heater by the cold salt pump for heating. The temperature rises to 560°C to become high-temperature molten salt, which then enters the hot salt tank.

[0049] For example, the low-pressure molten salt electric heater and / or high-pressure molten salt electric heater in the disclosed embodiments of the present invention are used to convert electrical energy into thermal energy for storage. Designed for a thermal storage duration of 4 hours, the total molten salt thermal storage capacity of the low-pressure molten salt electric heater and / or high-pressure molten salt electric heater is 2000 MWht, which can be fully utilized for photovoltaic energy absorption. In addition, the high-temperature molten salt thermal storage subsystem is also equipped with one cold salt tank, one hot salt tank, and three 50% capacity variable frequency cold salt pumps (two in operation and one on standby).

[0050] The specific molten salt thermal storage process is as follows: a cold salt pump pumps low-temperature molten salt (approximately 290°C) into a molten salt electric heater, raising the temperature to approximately 560°C before returning it to the hot salt tank. In the embodiments disclosed in this invention, the molten salt storage tank is a vertical, domed cylindrical tank connected to the atmosphere, used for storing molten salt.

[0051] The cold salt pump is a vertically suspended centrifugal pump. Each unit is equipped with three 50% capacity cold salt pumps, two in operation and one on standby, all of which are variable frequency pumps. The cold salt pump is supported on the top of the cold salt tank near the tank wall, with the pump head immersed in the low-temperature molten salt, pumping the molten salt into the molten salt electric heater. The design temperature of the cold salt pump is 400℃. This design temperature is used for the design of the pump body material and thermal expansion mechanical properties. The design flow rate of the pump set is the sum of the maximum heat exchange flow rate of the electric heater, plus a 5% margin, i.e., 2300t / h.

[0052] In step 102, the demineralized water in the demineralized water tank at 20°C is heated to 80°C by a low-pressure feedwater heater, and the demineralized water at 80°C enters the deaerator.

[0053] For example, demineralized water from the demineralized water header is supplied to one 50m³ unit. 3 and 1 100m 3 The demineralized water tank, of which 50m³ 3 The demineralized water in the demineralized water tank cools the auxiliary cooling water and then flows into the 100m³. 3 The demineralized water tank is equipped with two demineralized water pumps (one in operation and one on standby). The demineralized water at 20°C in the tank is heated to 80°C by a low-pressure heater and then pumped into the deaerator.

[0054] In step 103, the 80°C demineralized water is further heated to 160°C by a deaerator, and the 160°C demineralized water is pumped into the high-pressure feed water heater by an electric feed water pump.

[0055] For example, the deoxygenated water at 80°C is further heated to 160°C in the deaerator before entering the high-pressure feedwater heater through the low-pressure feedwater pipeline.

[0056] In step 104, the demineralized water at 160°C is heated to 255°C by a high-pressure feedwater heater to become demineralized water steam, which then enters the steam generator.

[0057] For example, after the deoxygenated water is heated to 160°C in the deaerator, it is pumped through a low-pressure water supply pipeline and then into a high-pressure heater to be heated to 255°C by three electric water supply pumps (two in operation and one on standby).

[0058] Specifically, Figure 3 It is based on Figure 1 The diagram shows a flow chart illustrating the heating process of demineralized water within a steam generator. Figure 3 As shown, the steam generator includes: a preheater, an evaporator, and a superheater; the method further includes:

[0059] In step 301, 255°C demineralized water steam sequentially enters the preheater, evaporator and superheater, and after exchanging heat with the high-temperature molten salt, generates 350°C superheated steam.

[0060] In step 302, the hot salt pump pumps molten salt at 560°C from the hot salt tank into the superheater to exchange heat with the demineralized water steam. The temperature of the molten salt drops to 523°C, and then it enters the evaporator to exchange heat with the demineralized water steam. The temperature of the molten salt at 523°C continues to drop to 323°C. The molten salt at 323°C enters the preheater to exchange heat with the demineralized water steam. The temperature of the molten salt at 323°C drops to about 290°C, becoming low-temperature molten salt, and is returned to the cold salt tank.

[0061] For example, to improve the efficiency of the evaporator, the feedwater needs to be heated to a certain temperature before entering the evaporator. Therefore, a feedwater preheater is required, with the heat source being molten salt. In the embodiments disclosed in this invention, the preheater is a shell-and-tube heat exchanger, with feedwater flowing on the tube side and molten salt flowing on the shell side. The evaporator is the main heat exchange equipment in the steam-water evaporation system and adopts a U-tube shell-and-tube heat exchanger. It consists of components such as a tube box, piping system, and shell, and is equipped with auxiliary instruments and valves such as pressure gauges, thermometers, level gauges, and safety valves. Steam / water flows on the tube side, and molten salt flows on the shell side. The steam drum has a horizontal structure, consisting of a cylinder, end caps, and several pipe joints. It is equipped with fixed supports and rolling supports, and manholes with self-tightening sealing structures are provided on both end caps. The internal device adopts a two-stage separation, which has extremely high separation efficiency. To improve the efficiency of the evaporation system, saturated steam needs to be heated to superheated steam with the required parameters. Therefore, a superheater is required. The heat source is molten salt, and it is a horizontal haircar heat exchanger with the feed water flowing on the tube side and the molten salt flowing on the shell side.

[0062] In step 105, the demineralized steam and the high-temperature molten salt are exchanged through the steam generator. The 255°C demineralized steam is then used to generate 350°C superheated steam for external supply.

[0063] Specifically, a feedwater electric heater is installed at the outlet of the preheater; if the temperature of the demineralized steam entering the preheater is lower than 255°C, the feedwater electric heater is activated to heat the temperature of the demineralized steam entering the preheater to 255°C.

[0064] For example, start the feedwater electric heater: used to heat the feedwater during startup or when the feedwater temperature does not reach the molten salt anti-condensation temperature of 255°C.

[0065] The hot salt pumps disclosed in this invention are vertically suspended centrifugal pumps, configured with three 50% capacity hot salt pumps (two operational and one standby). All of these hot salt pumps are variable frequency pumps, supported on the top of the hot salt tank near the tank wall. The pump body is immersed in high-temperature molten salt and is used to pump the high-temperature molten salt into the steam generator and pre-cooler. The design temperature is 570℃, which is used for the pump body material and thermal expansion mechanical design. The design flow rate of the pump group is the maximum heat exchange flow rate of the heat exchanger, with a 5% margin, i.e., 900 t / h. Electric feedwater pumps are used to provide water pressure to the steam generator, configured with three electric feedwater pumps (two operational and one standby). Demineralized water pumps are used to provide demineralized water pressure to the deaerator, configured with two demineralized water pumps (one operational and one standby).

[0066] In step 106, the hot salt pump pumps molten salt at 560°C from the hot salt tank into the steam generator to exchange heat with the demineralized water steam. The temperature of the hot molten salt drops to 290°C, becoming low-temperature molten salt, and is returned to the cold salt tank.

[0067] For example, the specific heat release process is as follows: the hot salt pump pumps the high-temperature molten salt at 560°C from the hot salt tank into the superheater, the temperature of the molten salt drops to about 523°C, and it enters the evaporator; after being reduced to about 323°C, it enters the preheater and is then reduced to about 290°C before returning to the cold salt tank.

[0068] In addition, the low-pressure molten salt electric heater and the high-pressure molten salt electric heater, along with the electricity used to absorb photovoltaic power, heat the low-temperature molten salt, converting electrical energy into heat energy.

[0069] Specifically, there are 8 low-pressure molten salt electric heaters and 5 high-pressure molten salt electric heaters. The cold salt pump pumps 290°C low-temperature molten salt into the low-pressure and / or high-pressure molten salt electric heaters for heating, including:

[0070] The molten salt electric heaters are configured with 8 × 37.5MW (low voltage) + 5 × 40MW (high voltage). When the instantaneous power of the photovoltaic system is lower than a preset power threshold, molten salt at 290℃ is pumped into the low-pressure molten salt electric heaters via a cold salt pump for heating. When the instantaneous power of the photovoltaic system is higher than or equal to the preset power threshold, molten salt at 290℃ is pumped into n high-pressure molten salt electric heaters via a cold salt pump for heating. The n high-pressure molten salt electric heaters must simultaneously satisfy both the first and second conditions.

[0071] The first condition is: , This indicates the number of high-pressure molten salt electric heaters started at time t. This represents the instantaneous power of the photovoltaic system at time t. Indicates the preset power threshold. Indicates the step parameters;

[0072] The second condition is: , This indicates the number of high-pressure molten salt electric heaters that were started at the previous moment. This indicates the hysteresis bandwidth.

[0073] For example, when the instantaneous photovoltaic power is lower than the system design threshold (e.g., 30% of the rated power), only the low-voltage electric heater is activated (low-power mode); once the threshold is exceeded, the high-voltage electric heater is gradually activated (stepped response).

[0074] In addition, it should be noted that, given the thermophysical properties of molten salt, when the temperature is below the freezing point, the liquid salt easily solidifies due to its low thermal conductivity, causing blockages in pipes, valves, or equipment. Therefore, to prevent blockages caused by molten salt solidification and to reduce the thermal shock of hot salt to pipes and equipment, anti-condensation protection designs are required for the equipment, pipes, and valves through which molten salt flows. All equipment through which the molten salt medium flows in the storage and release system, such as pipes, valves, and heat exchangers, must be equipped with electric heat tracing devices for preheating before system commissioning and insulation after shutdown to prevent molten salt solidification. The design should be carried out in accordance with the "Code for Design of Thermal Insulation Engineering for Industrial Equipment and Pipelines" (GB50264—2013), "Insulation, Anti-condensation and Electric Heat Tracing of Pipelines and Equipment" (16S401), and "Resistant Heat Tracing for Explosive Atmospheres Part 2: Design, Installation and Maintenance Guidelines" (GB / T19518.2—2017).

[0075] Compared to traditional electric heat tracing, molten salt electric heat tracing systems must withstand the extremely high temperatures of molten salt, which can reach approximately 560°C during normal operation. Considering the corrosive properties of molten salt, high-temperature molten salt electric heat tracing systems utilize mineral-insulated heating cables (MI cables). These MI cables preheat and traceive all molten salt pipes, valves, and equipment to prevent crystallization. The MI cable uses one or more alloy heating wires as the heat source, high-purity, electrofused magnesium oxide as the thermally conductive insulator, and a hard alloy jacket. Furthermore, due to the corrosive nature of molten salt on pipes, an additional PE or low-smoke halogen-free jacket is also required.

[0076] The electrical system scheme in the disclosed embodiments of the present invention: The electrical load of the molten salt energy storage system is mainly divided into two parts: (1) a total of 10 sets of molten salt electric heaters with a total power of 200MW and a voltage level of 6kV; (2) a molten salt electric heater with a total power of 300MW and a voltage level of 0.69kV; (3) 400V process equipment and auxiliary equipment such as water pumps, valves, lighting, HVAC, electric heat tracing, and thermal instruments, with a total power of about 8MW.

[0077] Two circuits of the 220kV system are connected to the 220kV indoor GIS power distribution equipment of this system via 220kV cables. The system is designed with six 220kV cable feeders of 220kV GIS to the high-voltage side cable terminals of six oil-immersed SFF-90000 / 220kV 90 / 45-45MVA 236.2 / 4330.3-4330.3A molten salt energy storage transformers. The low-voltage side of the transformer has a double-split winding 6kV common busbar leading to the electrical equipment room, and is connected to the switchgear of the busbar power distribution equipment of sections 6kV 1A and 1B, 6kV 2A and 2B, 6kV 3A and 3B, 6kV 4A and 4B, 6kV 5A and 5B, and 6kV 6A and 6B. The switchgear busbars are evenly distributed to five 6kV 40000kW molten salt electric heaters (high voltage), and power is evenly distributed to eight 0.69kV 37500kW loads via 56 dry-type transformers SCB14-6300 / 6 (6±2x2.5% / 0.69kV). Simultaneously, two 1000kVA auxiliary dry-type transformers, SCB14-1000 / 6 and 6.3±2x2.5% / 0.4, are connected from the 6kV working section 3B and 6kV working section 5A busbars, respectively.

[0078] The present invention also discloses a high-temperature molten salt energy storage and heat release system for absorbing new energy sources. The system includes: a high-temperature molten salt heat storage subsystem and a high-temperature molten salt heat release subsystem.

[0079] The high-temperature molten salt thermal storage subsystem includes: a low-pressure molten salt electric heater, a high-pressure molten salt electric heater, a cold salt tank, a hot salt tank, and a cold salt pump. The cold salt tank, the cold salt pump, the low-pressure molten salt electric heater / high-pressure molten salt electric heater, and the hot salt tank are connected in sequence.

[0080] The high-temperature molten salt exothermic subsystem includes: a demineralized water tank, a low-pressure feedwater heater, a deaerator, an electric feedwater pump, a high-pressure feedwater heater, and a steam generator, which are connected in sequence.

[0081] Optionally, the steam generator includes a preheater, an evaporator, and a superheater connected in sequence.

[0082] Optionally, the cold salt pump is a vertically suspended centrifugal pump structure;

[0083] The cold salt pump is supported on the top of the cold salt tank near the tank wall. The pump head of the cold salt pump is immersed in the low-temperature molten salt in the cold salt tank to pump the low-temperature molten salt into the low-pressure molten salt electric heater / high-pressure molten salt electric heater.

[0084] Optionally, the number of demineralized water tanks is two, one of which is 50m³. 3 Demineralized water tank and 1 100m 3 The demineralized water tank.

[0085] Optionally, the heating steam in the low-pressure feedwater heater and deaerator is derived from recovered auxiliary steam.

[0086] In summary, this invention discloses a high-temperature molten salt energy storage and heat release system and its application method for absorbing new energy sources. The method includes: pumping 290°C low-temperature molten salt into a low-pressure and / or high-pressure molten salt electric heater via a cold salt pump to heat it to 560°C high-temperature molten salt, which then enters a hot salt tank; heating demineralized water to 80°C via a low-pressure feedwater heater and sending it to a deaerator; further heating the demineralized water to 160°C via the deaerator and pumping it into a high-pressure feedwater heater; heating the demineralized water to 255°C to become demineralized water steam, which enters a steam generator; performing a heat exchange process between the demineralized water steam and the high-temperature molten salt to generate 350°C superheated steam; and pumping the 560°C high-temperature molten salt from the hot salt tank into the steam generator via a hot salt pump to exchange heat with the demineralized water steam, reducing the temperature to 290°C, and returning it to the cold salt tank. The ability to supply high-pressure steam through molten salt energy storage aligns with the characteristics and advantages of the industry, and has a reference and guiding role in the demonstration and application of energy storage and new energy industries.

[0087] The preferred embodiments of this disclosure have been described in detail above with reference to the accompanying drawings. However, this disclosure is not limited to the specific details of the above embodiments. Within the scope of the technical concept of this disclosure, various simple modifications can be made to the technical solutions of this disclosure, and these simple modifications all fall within the protection scope of this disclosure.

[0088] 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. In order to avoid unnecessary repetition, this disclosure will not describe the various possible combinations separately.

[0089] Furthermore, various different embodiments of this disclosure can be combined in any way, as long as they do not violate the spirit of this disclosure, they should also be regarded as the content disclosed in this disclosure.

Claims

1. An application method for a high-temperature molten salt energy storage and heat release system for absorbing new energy sources, characterized in that, The system includes: a high-temperature molten salt thermal storage subsystem and a high-temperature molten salt heat release subsystem; the high-temperature molten salt thermal storage subsystem includes: a low-pressure molten salt electric heater, a high-pressure molten salt electric heater, a cold salt tank, a hot salt tank, and a cold salt pump; the high-temperature molten salt heat release subsystem includes: a demineralized water tank, a low-pressure feedwater heater, a deaerator, an electric feedwater pump, a high-pressure feedwater heater, and a steam generator; The application method includes: The cold salt pump pumps low-temperature molten salt at 290°C into the low-pressure molten salt electric heater and / or the high-pressure molten salt electric heater for heating, raising the temperature to 560°C to become high-temperature molten salt, which then enters the hot salt tank. The demineralized water in the demineralized water tank at 20°C is heated to 80°C by the low-pressure feed water heater, and the demineralized water at 80°C enters the deaerator. The deaerator further heats the 80°C demineralized water to 160°C, and the electric feed water pump pumps the 160°C demineralized water into the high-pressure feed water heater. The demineralized water at 160°C is heated to 255°C by the high-pressure feedwater heater to become demineralized water steam, which then enters the steam generator. The demineralized steam and the high-temperature molten salt are exchanged through the steam generator. The 255°C demineralized steam is then used to generate 350°C superheated steam to supply steam to the outside. A hot salt pump pumps molten salt at 560°C from a hot salt tank into a steam generator to exchange heat with the demineralized water steam. The temperature of the hot salt is reduced to 290°C, becoming low-temperature molten salt, and then returned to the cold salt tank. The low-pressure molten salt electric heater and the high-pressure molten salt electric heater are used to absorb the electricity from the photovoltaic system and heat the low-temperature molten salt to convert electrical energy into heat energy. The number of low-pressure molten salt electric heaters is 8, and the number of high-pressure molten salt electric heaters is 5. The process of pumping 290°C low-temperature molten salt into the low-pressure molten salt electric heaters and / or the high-pressure molten salt electric heaters for heating via the cold salt pump includes: When the instantaneous power of the photovoltaic is lower than the preset power threshold, molten salt at 290°C is pumped into the low-pressure molten salt electric heater for heating via a cold salt pump. When the instantaneous power of the photovoltaic system is higher than or equal to a preset power threshold, molten salt at 290°C is pumped into n high-pressure molten salt electric heaters via a cold salt pump for heating. The n high-pressure molten salt electric heaters should simultaneously satisfy both the first and second conditions. The first condition is: , This indicates the number of high-pressure molten salt electric heaters started at time t. This represents the instantaneous power of the photovoltaic system at time t. Indicates the preset power threshold. Indicates the step parameters; The second condition is: , This indicates the number of high-pressure molten salt electric heaters that were started at the previous moment. This indicates the hysteresis bandwidth.

2. The application method of the high-temperature molten salt energy storage and heat release system for absorbing new energy sources according to claim 1, characterized in that, The steam generator includes: a preheater, an evaporator, and a superheater; The application method includes: The 255°C demineralized water steam sequentially enters the preheater, evaporator and superheater, and after exchanging heat with the high-temperature molten salt, generates 350°C superheated steam. The hot salt pump pumps molten salt at 560°C from the hot salt tank into the superheater to exchange heat with demineralized water steam. The temperature of the molten salt drops to 523°C, and then it enters the evaporator to exchange heat with the demineralized water steam. The temperature of the molten salt at 523°C continues to drop to 323°C. The molten salt at 323°C enters the preheater to exchange heat with the demineralized water steam. The temperature of the molten salt at 323°C drops to 290°C, becoming low-temperature molten salt, and is returned to the cold salt tank.

3. The application method of the high-temperature molten salt energy storage and heat release system for absorbing new energy sources according to claim 2, characterized in that, A feedwater electric heater is installed at the inlet of the preheater; If the temperature of the demineralized steam entering the preheater is below 255°C, the feedwater electric heater is activated to heat the demineralized steam entering the preheater to 255°C.

4. The application method of the high-temperature molten salt energy storage and heat release system for absorbing new energy sources according to claim 1, characterized in that, The cold salt pump is a vertically suspended centrifugal pump. The cold salt pump is supported on the top of the cold salt tank near the tank wall, and the pump head of the cold salt pump is immersed in the low-temperature molten salt in the cold salt tank to pump the low-temperature molten salt into the low-pressure molten salt electric heater and / or the high-pressure molten salt electric heater.

5. The application method of the high-temperature molten salt energy storage and heat release system for absorbing new energy sources according to claim 1, characterized in that, The number of demineralized water tanks is two, one 50m³ and the other 100m³. 3 Demineralized water tank and 1 100m 3 The demineralized water tank.

6. The application method of the high-temperature molten salt energy storage and heat release system for absorbing new energy sources according to claim 1, characterized in that, The heating steam in the low-pressure feedwater heater and deaerator comes from recovered auxiliary steam.

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