Fused salt energy storage system

Abstract

The fused salt energy storage system is used for peak regulation of a thermal power generating unit and comprises a first fused salt tank, a second fused salt tank and a heat exchange unit, the heat exchange unit is arranged between the first fused salt tank and the second fused salt tank, the heat exchange unit is used for conducting heat exchange on fused salt and water or steam, and the heat exchange unit comprises a fused salt heat exchanger; the fused salt heat exchanger comprises a fused salt flow path and a water flow path, an inlet of the fused salt flow path is directly or indirectly connected with the first fused salt tank, and an outlet of the fused salt flow path is connected with the second fused salt tank; the water flow path is connected in parallel with a first heated flow path of the low-pressure heater. According to the fused salt energy storage system disclosed by the invention, the low-pressure heater system is squeezed through the fused salt heat exchanger, steam extraction of the low-pressure heater is reduced, and the steam amount of acting of the low-pressure cylinder is increased, so that the load is increased, the load rising rate is increased, quick response of the system is realized, gradient utilization of energy is realized, and the energy storage density of the system is improved.

Description

Technical Field

[0001] This application relates to the field of molten salt energy storage technology, and more specifically, to a molten salt energy storage system. Background Technology

[0002] Molten salt energy storage technology uses molten salt thermal energy storage to achieve energy storage and can be coupled with thermal power units to achieve peak shaving. Peak shaving refers to the power system adjusting the output power of the generation side through various means to meet fluctuations in user electricity load (electricity demand) and maintain a real-time balance between power generation and consumption. Molten salt energy storage technology utilizes the thermal storage capacity of molten salt to actively store electricity as heat energy when there is a power supply surplus or a power demand trough. When the grid needs it, the heat energy is converted into electrical energy, thereby achieving peak shaving and valley filling, system frequency regulation, and providing flexibility to the power supply.

[0003] Currently, the requirements for peak shaving amplitude and speed of thermal power units are getting higher and higher. However, the current peak shaving rate of molten salt energy storage systems, especially the rapid response capability at the minute and second level, is insufficient, causing delays in power regulation and limiting the system load response speed.

[0004] Therefore, how to improve the system load response speed has become a technical problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0005] The purpose of this application is to disclose a molten salt energy storage system to improve the system load response speed.

[0006] This application provides a molten salt energy storage system for peak shaving in thermal power units. The thermal power unit includes a boiler, a steam turbine, and a low-pressure heater. The low-pressure heater includes a first heating flow path and a first heated flow path. The steam extraction port of the steam turbine is connected to the first heating flow path, and the steam exhaust port of the steam turbine is indirectly connected to the boiler through the first heated flow path. The low-pressure heater uses the steam extracted from the steam turbine to heat the flowing water. The molten salt energy storage system includes:

[0007] A first molten salt vessel and a second molten salt vessel, wherein the temperature of the molten salt in the first molten salt vessel is higher than the temperature of the molten salt in the second molten salt vessel;

[0008] A heat exchange unit is disposed between the first molten salt tank and the second molten salt tank. The heat exchange unit is used to exchange heat between molten salt and water or steam. The heat exchange unit includes a molten salt heat exchanger. The molten salt heat exchanger includes a molten salt flow path and a water flow path. The inlet of the molten salt flow path is directly or indirectly connected to the first molten salt tank, and the outlet of the molten salt flow path is connected to the second molten salt tank. The water flow path is connected in parallel with the first heated flow path of the low-pressure heater.

[0009] In one possible implementation, a low-pressure inlet regulating valve is provided on the inlet pipe of the first heated flow path, and a low-pressure bypass regulating valve is provided on the inlet pipe of the water flow path.

[0010] In one possible implementation, a temperature sensor and a first controller are also included. The temperature sensor detects a first temperature and a second temperature, where the first temperature is the temperature at the outlet of the water flow path and the second temperature is the temperature at the outlet of the first heated flow path. The first controller is communicatively connected to the temperature sensor. When the low-pressure bypass regulating valve is open, the first controller controls the opening degree of the low-pressure inlet regulating valve according to preset conditions. The preset conditions include a first condition, a second condition, and a third condition.

[0011] The first condition is: the first temperature is less than the second temperature, and the difference between the two is greater than a first preset value, and the opening degree of the low-pressure inlet regulating valve is fully open;

[0012] The second condition is: the first temperature is less than the second temperature, and the difference between the two is less than or equal to the first preset value, and the opening degree of the low-pressure inlet regulating valve is proportional to the difference.

[0013] The third condition is: the first temperature is greater than or equal to the second temperature, and the opening degree of the low-pressure inlet regulating valve is fully closed.

[0014] In one possible implementation, the heat exchange unit includes a steam superheater and a steam generator;

[0015] The molten salt inlet of the steam superheater is connected to the first molten salt tank, the molten salt outlet of the steam superheater is connected to the molten salt inlet of the steam generator, and the steam outlet of the steam superheater is connected to the boiler;

[0016] The molten salt outlet of the steam generator is connected to the molten salt inlet of the molten salt heat exchanger, the water inlet pipe of the steam generator is indirectly connected to the water outlet pipe of the low-pressure heater, and the steam outlet of the steam generator is connected to the steam inlet of the steam superheater.

[0017] In one possible implementation, the outlet of the first molten salt tank is connected to a molten salt outlet pipe and a molten salt bypass pipe, the molten salt outlet pipe and the molten salt bypass pipe are connected in parallel, the molten salt outlet pipe is connected to the molten salt inlet of the steam superheater, and the molten salt bypass pipe is connected to the molten salt flow path of the molten salt heat exchanger.

[0018] In one possible implementation, a molten salt outlet regulating valve is provided on the molten salt outlet pipeline, and a molten salt bypass regulating valve is provided on the molten salt bypass pipeline.

[0019] In one possible implementation, a second controller is also included, which controls the opening degree of the molten salt bypass control valve according to a fourth condition, a fifth condition, and a sixth condition when both the molten salt outlet control valve and the molten salt bypass control valve are open.

[0020] The fourth condition is: the temperature at the outlet of the water flow path is less than the temperature at the outlet of the first heated flow path, and the difference between the two is greater than the second preset value, and the opening degree of the molten salt bypass regulating valve is fully open.

[0021] The fifth condition is: the temperature at the outlet of the water flow path is less than the temperature at the outlet of the first heated flow path, and the difference between the two is less than or equal to the second preset value; the opening degree of the molten salt bypass regulating valve is proportional to the difference between the two.

[0022] The sixth condition is that the temperature at the outlet of the water flow path is greater than or equal to the temperature at the outlet of the first heated flow path, and the opening of the molten salt bypass regulating valve remains unchanged.

[0023] In one possible implementation, the thermal power unit includes a high-pressure heater, the high-pressure heater includes a second heating flow path and a second heated flow path, the steam extraction port of the steam turbine is connected to the second heating flow path, and the first heated flow path is indirectly connected to the boiler through the second heated flow path;

[0024] The steam outlet of the steam generator is connected to a high-pressure steam extraction pipe and a steam generator pipe. The high-pressure steam extraction pipe and the steam generator pipe are connected in parallel. The high-pressure steam extraction pipe is connected to the second heating flow path, and the steam generator pipe is connected to the steam superheater.

[0025] In one possible implementation, the high-pressure steam extraction pipeline is equipped with a high-pressure steam extraction pipeline regulating valve, and the steam generator pipeline is equipped with a steam generator outlet pipeline regulating valve.

[0026] In one possible implementation, the steam outlet of the steam superheater is connected to a reheating pipe and a heating pipe, the reheating pipe and the heating pipe being connected in parallel; the reheating pipe is connected to the boiler and is equipped with a reheating shut-off valve; the heating pipe is connected to the steam user and is equipped with a heating shut-off valve.

[0027] The molten salt energy storage system disclosed in this application utilizes a molten salt heat exchanger connected in parallel with a low-pressure heater during heat release. This heat exchanger heats the water, reducing the amount of water the low-pressure heater needs to heat and consequently reducing the amount of steam extracted from the turbine. This allows the extracted steam, originally intended for the low-pressure heater, to remain within the turbine, increasing its output power. Furthermore, the molten salt heat exchanger only raises the water temperature without a phase change process, avoiding the significant latent heat of vaporization required to heat water into steam. During peak shaving, adjusting the flow rate of molten salt or water allows for relatively direct and rapid changes in the output hot water temperature or flow rate, resulting in low system inertia and a fast response. Additionally, lower water pressure and temperature at the inlet of the molten salt heat exchanger allow the molten salt to cool to even lower levels during heat exchange, extracting more heat and improving the energy utilization rate of the molten salt and the overall system energy storage density.

[0028] Compared to related technologies, the molten salt energy storage system disclosed in this application uses hot water generated by a molten salt heat exchanger to replace the hot water generated by a low-pressure heater, thereby displacing the low-pressure heater system, reducing steam extraction from the low-pressure heater, increasing the amount of steam used for work in the low-pressure cylinder, thus increasing the load and improving the load increase rate, achieving rapid system response, realizing energy cascade utilization, and increasing the system's energy storage density. Attached Figure Description

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

[0030] Figure 1 This is a schematic diagram of the molten salt energy storage system disclosed in the embodiments of this application. Figure 1 ;

[0031] Figure 2 This is a schematic diagram of the molten salt energy storage system disclosed in the embodiments of this application. Figure 2 ;

[0032] Figure 3 This is a schematic diagram of the molten salt energy storage system disclosed in the embodiments of this application. Figure 3 ;

[0033] Figure 4 This is a schematic diagram of the molten salt energy storage system disclosed in the embodiments of this application. Figure 4 ;

[0034] Figure 5This is a schematic diagram of the molten salt energy storage system disclosed in the embodiments of this application. Figure 5 ;

[0035] Figure 6 This is a schematic diagram of the molten salt energy storage system disclosed in the embodiments of this application. Figure 6 .

[0036] The attached figures are labeled as follows:

[0037] 100. First molten salt vessel;

[0038] 200. Second molten salt vessel;

[0039] 300. Heat exchange unit; 310. Molten salt heat exchanger; 320. Steam generator; 330. Steam superheater;

[0040] 400. Thermal power unit; 410. Boiler; 420. Steam turbine; 430. Condenser; 440. Condensate pump; 450. Low-pressure heater; 460. Deaerator; 470. Feed water pump; 480. High-pressure heater;

[0041] 500. Control valve assembly; 510. Low-pressure inlet control valve; 520. Low-pressure bypass control valve; 530. Molten salt outlet control valve; 540. Molten salt bypass control valve; 550. Steam generator outlet pipeline control valve; 560. Discharge high-pressure extraction steam pipeline control valve;

[0042] 600. Heat release water pump. Detailed Implementation

[0043] The purpose of this application is to disclose a molten salt energy storage system to improve the system load response speed.

[0044] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application.

[0045] This application discloses a molten salt energy storage system for peak shaving of thermal power units at 400 rpm. See also... Figure 1-6 In this embodiment, the energy storage process of the molten salt energy storage system is not analyzed; only the energy release process is analyzed. The energy release process occurs when the power grid is at its peak load and the generating unit needs to increase its output. In this process, the molten salt energy storage system releases energy to increase the electrical output of the thermal power unit 400.

[0046] The thermal power unit 400 may include a boiler 410, a steam turbine 420, and a low-pressure heater 450. The boiler 410 burns coal to heat water into high-temperature, high-pressure steam. This steam drives the steam turbine 420 to rotate, which in turn drives the generator to produce electricity. The steam turbine 420 is divided into a high-pressure cylinder, an intermediate-pressure cylinder, and a low-pressure cylinder. After performing work in the high-pressure cylinder, the steam is returned to the reheater of the boiler 410 for reheating, and then enters the intermediate-pressure and low-pressure cylinders to continue performing work. This process aims to improve overall efficiency.

[0047] The low-pressure heater 450 includes a first heating flow path and a first heated flow path. The steam extraction port of the steam turbine 420 is connected to the first heating flow path, and the steam exhaust port of the steam turbine 420 is indirectly connected to the boiler 410 through the first heated flow path. The low-pressure heater 450 uses the steam extracted from the steam turbine 420 to heat the flowing water. Figure 1 In the illustrated embodiment, the low-pressure steam that has completed its work in the turbine 420 is discharged from the exhaust port and then passes sequentially through the condenser 430 and the condensate pump 440, entering the first heated flow path of the low-pressure heater 450 in liquid water state. After being heated by extracted steam in the low-pressure heater 450, the water passes sequentially through the deaerator 460, the feedwater pump 470, and the high-pressure heater 480, returning to the boiler 410 in steam state.

[0048] The molten salt energy storage system includes a first molten salt tank 100, a second molten salt tank 200, and a heat exchange unit 300. The temperature of the molten salt in the first molten salt tank 100 is higher than that in the second molten salt tank 200. The heat exchange unit 300 is located between the first molten salt tank 100 and the second molten salt tank 200, and is used to exchange heat between the molten salt and water or steam. When the power grid is at its peak load and the thermal power unit 400 needs to rapidly increase its output power, the molten salt in the first molten salt tank 100 transfers heat to the feedwater from the thermal power unit 400 in the heat exchange unit 300. After releasing its heat, the molten salt flows out of the heat exchange unit 300 and into the second molten salt tank 200. The next time there is a power surplus, the molten salt in the second molten salt tank 200 is heated and returned to the first molten salt tank 100.

[0049] The heat exchange unit 300 includes a molten salt heat exchanger 310. The molten salt heat exchanger 310 includes a molten salt flow path and a water flow path. The inlet of the molten salt flow path is directly or indirectly connected to the first molten salt tank 100, and the outlet of the molten salt flow path is connected to the second molten salt tank 200, forming a molten salt circuit. The water flow path is connected in parallel with the first heated flow path of the low-pressure heater 450, forming a feedwater circuit. Driven by a molten salt pump, the molten salt in the first molten salt tank 100 flows through the molten salt flow path, exchanges heat with the water flow path, and returns to the second molten salt tank 200 after releasing heat and cooling down. Part of the water pumped by the condensate pump 440 in the thermal power unit 400 enters the first heated flow path of the low-pressure heater 450, and part enters the water flow path to be heated by the molten salt. The heated water then flows into the deaerator 460.

[0050] The molten salt energy storage system disclosed in this application utilizes a molten salt heat exchanger 310 connected in parallel with the low-pressure heater 450 during heat release. This heats the water, reducing the amount of water the low-pressure heater 450 needs to heat, and consequently reducing the amount of steam extracted from the turbine 420 required by the low-pressure heater 450. This extracted steam, originally intended for the low-pressure heater 450, can continue to perform work within the turbine 420, thereby increasing the turbine 420's output power. Furthermore, the molten salt heat exchanger 310 only raises the water temperature without a phase change process, avoiding the significant latent heat of vaporization required in heating water to steam. During peak shaving, the system has low inertia, and by adjusting the flow rate of molten salt or water, the temperature or flow rate of the output hot water can be changed relatively directly and quickly, enabling the molten salt energy storage system to respond rapidly.

[0051] In addition, due to the low water pressure and temperature on the inlet side of the molten salt heat exchanger 310, the molten salt can be cooled to a lower level during the heat exchange process, thereby extracting more heat and improving the energy utilization rate of the molten salt and the energy storage density of the entire system.

[0052] Compared to related technologies, the molten salt energy storage system disclosed in this application uses hot water generated by the molten salt heat exchanger 310 to replace the hot water generated by the low-pressure heater 450, thereby displacing the low-pressure heater system, reducing the steam extraction of the low-pressure heater 450, increasing the amount of steam that the turbine 420 can use for work, thus increasing the load and improving the load increase rate, achieving rapid system response, realizing energy cascade utilization, and increasing the system's energy storage density.

[0053] In one specific implementation, see Figure 3 A low-pressure inlet regulating valve 510 is installed on the inlet pipe of the first heated flow path, and a low-pressure bypass regulating valve 520 is installed on the inlet pipe of the water flow path, for precisely controlling the feedwater flow rate entering the first heated flow path and the water flow path. During normal operation of the thermal power unit 400, the low-pressure inlet regulating valve 510 is normally open. When the molten salt energy storage system needs to increase its load, the flow distribution between the molten salt heat exchanger 310 and the low-pressure heater 450 is adjusted by decreasing the opening of the low-pressure inlet regulating valve 510 or increasing the opening of the low-pressure bypass regulating valve 520, thereby enabling the molten salt heat exchanger 310 to replace the low-pressure heater 450.

[0054] To achieve automatic control of the system, in one specific embodiment, the molten salt energy storage system further includes a temperature sensor and a first controller. The temperature sensor is used to detect a first temperature and a second temperature, where the first temperature is the temperature at the outlet of the water flow path, and the second temperature is the temperature at the outlet of the first heated flow path. The temperature sensor includes, but is not limited to, thermocouples or resistance temperature detectors (RTDs), and those skilled in the art can select a suitable sensor type based on design requirements.

[0055] The first controller is communicatively connected to the temperature sensor. When the low-pressure bypass regulating valve 520 is open, the first controller controls the opening degree of the low-pressure inlet regulating valve 510 according to preset conditions. The preset conditions include a first condition, a second condition, and a third condition.

[0056] The first condition is that the first temperature is less than the second temperature, and the difference between the two is greater than a first preset value (such as 90°C; those skilled in the art can set the specific temperature value of the first preset value based on design requirements). The low-pressure inlet regulating valve 510 is fully open. Since the molten salt heat exchanger 310 has just been put into use, the first temperature and the second temperature differ significantly. To avoid a drop in the overall temperature within the thermal power unit's 400 pipeline, the low-pressure inlet regulating valve 510 is fully open.

[0057] The second condition is that the first temperature is less than the second temperature, and the difference between them is less than or equal to a first preset value. The opening degree of the low-pressure inlet regulating valve 510 is proportional to the difference. As the molten salt heat exchanger 310 is put into use, the first temperature will rise, and the difference between the first and second temperatures will decrease. Until the difference between the two equals the first preset value, and the difference continues to decrease, the first controller will control the opening degree of the low-pressure inlet regulating valve 510 to gradually decrease, and the molten salt heat exchanger 310 will gradually displace the low-pressure heater 450.

[0058] The third condition is that the first temperature is greater than or equal to the second temperature, and the low-pressure inlet regulating valve 510 is fully closed. When the first temperature is greater than or equal to the second temperature, the molten salt heat exchanger 310 can completely replace the low-pressure heater 450. At this time, the extracted steam that was originally supplied to the low-pressure heater 450 remains in the turbine 420 to do work, significantly increasing the output power of the turbine 420. This design can achieve automatic operation, greatly reducing the operational burden on operators. The controller uses real-time control of the valve opening based on the feedback temperature, ensuring control accuracy and rapid response.

[0059] In one specific embodiment, the heat exchange unit 300 further includes a steam superheater 330 and a steam generator 320. The molten salt inlet of the steam superheater 330 is connected to the first molten salt tank 100, the molten salt outlet of the steam superheater 330 is connected to the molten salt inlet of the steam generator 320, and the steam outlet of the steam superheater 330 is connected to the boiler 410. The molten salt outlet of the steam generator 320 is connected to the molten salt inlet of the molten salt heat exchanger 310, the water inlet pipe of the steam generator 320 is indirectly connected to the water outlet pipe of the low-pressure heater 450, and the steam outlet of the steam generator 320 is connected to the steam inlet of the steam superheater 330.

[0060] During the operation of the molten salt energy storage system, water from the molten salt heat exchanger 310 or the low-pressure heater 450 in the thermal power unit 400 is transported to the steam generator 320 via the deaerator 460 and then via the heat release feedwater pump 600. The feedwater first absorbs heat from the molten salt in the steam generator 320 and evaporates completely into steam. The steam then enters the steam superheater 330, where it exchanges heat with the molten salt and is heated to the required superheated steam. This superheated steam merges with the steam after it has done work in the high-pressure cylinder and is returned to the reheater of the boiler 410, then enters the intermediate-pressure cylinder and low-pressure cylinder to continue doing work. Molten salt in the first molten salt tank 100 is pumped into the steam superheater 330. After releasing heat and cooling down, the molten salt enters the steam generator 320 to release heat. Finally, the molten salt flowing out of the steam generator 320 is reheated in the molten salt heat exchanger 310 and flows into the second molten salt tank 200.

[0061] This design employs a multi-stage molten salt heat exchanger. Throughout the heat exchange path, molten salt at a high temperature is first used to generate superheated steam. Then, the cooled molten salt reheats the lower-pressure steam generator 320 and the even lower-temperature molten salt heat exchanger 310. At low pressure, the water's saturation temperature is lower, allowing the molten salt to continue cooling to even lower levels, thereby extracting more heat. This significantly improves heat exchange efficiency. Through this cascaded utilization, the lower limit of the molten salt's exothermic temperature is substantially reduced, bringing it closer to the design temperature of the second molten salt tank 200, thus significantly improving molten salt utilization and the overall system's energy storage density.

[0062] To accelerate the heating rate of the molten salt heat exchanger 310, in one specific embodiment, the outlet of the first molten salt tank 100 is connected to a molten salt outlet pipe and a molten salt bypass pipe, such as... Figure 4 As shown, the molten salt outlet pipe and the molten salt bypass pipe are connected in parallel. The molten salt outlet pipe is connected to the molten salt inlet of the steam superheater 330, and the molten salt bypass pipe is connected to the molten salt flow path. This design allows the high-temperature molten salt in the first molten salt tank 100 to flow directly into the molten salt heat exchanger 310 through the molten salt bypass pipe, thereby accelerating the heating rate of the molten salt heat exchanger 310. Since the efficiency of the molten salt heat exchanger 310 in producing hot water is higher than that of the steam superheater 330 in producing superheated steam, the power enhancement efficiency of the molten salt heat exchanger 310 in displacing the low-pressure heater 450 is higher than the power enhancement efficiency of returning superheated steam to the boiler 410. The direct flow of molten salt from the first molten salt tank 100 into the molten salt heat exchanger 310 can rapidly increase the output power of the thermal power unit 400.

[0063] To further regulate the load increase rate, a molten salt outlet regulating valve 530 is installed on the molten salt outlet pipeline, and a molten salt bypass regulating valve 540 is installed on the molten salt bypass pipeline. When the system needs to increase its load, the system load increase rate is increased by decreasing the opening of the molten salt outlet regulating valve 530 and increasing the opening of the molten salt bypass regulating valve 540.

[0064] To enhance the automation level of the system, in one specific embodiment, the molten salt energy storage system also includes a second controller. When both the molten salt outlet regulating valve 530 and the molten salt bypass regulating valve 540 are open, the second controller controls the opening degree of the molten salt bypass regulating valve 540 according to the fourth and fifth conditions.

[0065] The fourth condition is that the temperature at the outlet of the water flow path is lower than the temperature at the outlet of the first heated flow path, and the difference between the two is greater than a second preset value (e.g., 90°C; those skilled in the art can set the specific temperature value of the second preset value based on design requirements). In this condition, the molten salt bypass regulating valve 540 is fully open. The smaller the second preset value is set, the longer the molten salt bypass regulating valve 540 remains fully open. The fifth condition is that the temperature at the outlet of the water flow path is lower than the temperature at the outlet of the first heated flow path, and the difference between the two is less than or equal to the second preset value. In this condition, the opening of the molten salt bypass regulating valve 540 is proportional to the difference between the two. As molten salt flows into the molten salt heat exchanger 310 through the molten salt bypass pipe, the temperature at the outlet of the water flow path increases, and the aforementioned difference decreases. Until the difference equals the second preset value, as the difference continues to decrease, the opening of the molten salt bypass regulating valve 540 decreases. The sixth condition is that the temperature at the outlet of the water flow path is greater than or equal to the temperature at the outlet of the first heated flow path. In this condition, the opening of the molten salt bypass regulating valve 540 remains unchanged. Since the temperature measurement points are the same, the second controller can be connected to the aforementioned temperature sensor signals. This design can precisely control the heating rate of the molten salt heat exchanger 310, thereby accurately regulating the system's load increase rate, achieving automatic operation, and greatly reducing the operational burden on operators.

[0066] In one specific embodiment, the thermal power unit 400 includes a high-pressure heater 480, which includes a second heating flow path and a second heated flow path. The extraction steam port of the steam turbine 420 is connected to the second heating flow path, and the first heated flow path is indirectly connected to the boiler 410 through the second heated flow path. The high-pressure heater 480 uses the extracted steam from the steam turbine 420 to heat the working fluid in the second heated flow path.

[0067] See Figure 5 As shown, the steam outlet of the steam generator 320 is connected to a high-pressure extraction steam pipe and a steam generator pipe. The high-pressure extraction steam pipe and the steam generator pipe are connected in parallel. The high-pressure extraction steam pipe is connected to the second heating flow path, and the steam generator pipe is connected to the steam superheater 330. Part of the steam generated by the steam generator 320 enters the steam superheater 330 for reheating, while the other part enters the second heating flow path through the high-pressure extraction steam pipe to exchange heat with the working fluid in the second heated flow path. This replaces the extraction steam originally from the steam turbine 420, allowing this extracted steam to continue to do work within the steam turbine 420, thereby increasing the output power of the steam turbine 420.

[0068] In one specific embodiment, a high-pressure steam extraction pipeline regulating valve 560 is installed on the high-pressure steam extraction pipeline, and a steam generator outlet pipeline regulating valve 550 is installed on the steam generator pipeline. High-pressure steam extraction is used to increase the output power of the steam turbine 420. This method is highly efficient. When a rapid increase in the output power of the thermal power unit 400 is required, the high-pressure steam extraction pipeline regulating valve 560 is increased, and the steam generator outlet pipeline regulating valve 550 is decreased, which facilitates a rapid increase in unit load.

[0069] In one specific embodiment, the steam outlet of the steam superheater 330 may be connected to a reheat / cooling pipe and a heating pipe, such as... Figure 6 As shown, the reheat and cooling return pipelines are connected in parallel. The reheat and cooling return pipeline is connected to boiler 410 and is equipped with a reheat and cooling return shut-off valve 570. The heating pipeline connects to steam users and is equipped with a heating shut-off valve 580. Part of the steam generated by the steam superheater 330 is returned to the thermal power unit 400 for power generation, and the other part is supplied directly or after desuperheating and pressure reduction to industrial or heating users. This design ensures full utilization of the steam's heat, with almost no loss of cooling source, and facilitates the expansion of system functionality, improving the power plant's economic competitiveness. When high-power power generation is required, the heating shut-off valve 580 can be closed to stop external heating, allowing more steam to be used for power generation, thus giving the system good peak-shaving capabilities.

[0070] The terms "first" and "second," etc., used in this application are used to distinguish different objects, not to describe a specific order, and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion. For example, a process, method, system, product, or device that includes a series of steps or units may include steps or units not listed, but rather steps or units not listed. Additionally, in the description of embodiments in this application, "a plurality of" means two or more.

[0071] In the description of this application, it should be understood that the terms "height," "thickness," "upper," "lower," "top," "bottom," "inner," and "outer," etc., indicating orientation or positional relationships based on the orientation or positional relationships shown in the accompanying drawings, are used only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application. In the description of this application, "a plurality of" means two or more, and "at least one" can mean one, two, or more, unless otherwise expressly specified.

[0072] The above description of the disclosed embodiments enables those skilled in the art to make or use this application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of this application. Specific technical means in some embodiments may be incorporated, in whole or in part, into another embodiment unless explicitly excluded by another embodiment. Therefore, this application is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A molten salt energy storage system for peak shaving of thermal power units (400), characterized in that, The thermal power unit (400) includes a boiler (410), a steam turbine (420), and a low-pressure heater (450). The low-pressure heater (450) includes a first heating flow path and a first heated flow path. The steam extraction port of the steam turbine (420) is connected to the first heating flow path, and the steam exhaust port of the steam turbine (420) is indirectly connected to the boiler (410) through the first heated flow path. The low-pressure heater (450) uses the steam extracted from the steam turbine (420) to heat the water flowing through it. The molten salt energy storage system includes: A first molten salt vessel (100) and a second molten salt vessel (200), wherein the temperature of the molten salt in the first molten salt vessel (100) is greater than the temperature of the molten salt in the second molten salt vessel (200); A heat exchange unit (300) is disposed between the first molten salt tank (100) and the second molten salt tank (200). The heat exchange unit (300) is used to exchange heat between molten salt and water or steam. The heat exchange unit (300) includes a molten salt heat exchanger (310). The molten salt heat exchanger (310) includes a molten salt flow path and a water flow path. The inlet of the molten salt flow path is directly or indirectly connected to the first molten salt tank (100), and the outlet of the molten salt flow path is connected to the second molten salt tank (200). The water flow path is connected in parallel with the first heated flow path of the low-pressure heater (450).

2. The molten salt energy storage system as described in claim 1, characterized in that, A low-pressure inlet regulating valve (510) is provided on the inlet pipe of the first heated flow path, and a low-pressure bypass regulating valve (520) is provided on the inlet pipe of the water flow path.

3. The molten salt energy storage system as described in claim 2, characterized in that, It also includes a temperature sensor and a first controller. The temperature sensor is used to detect a first temperature and a second temperature. The first temperature is the temperature at the outlet of the water flow path, and the second temperature is the temperature at the outlet of the first heated flow path. The first controller is communicatively connected to the temperature sensor. When the low-pressure bypass regulating valve (520) is open, the first controller controls the opening degree of the low-pressure inlet regulating valve (510) according to preset conditions. The preset conditions include a first condition, a second condition, and a third condition. The first condition is: the first temperature is less than the second temperature, and the difference between the two is greater than the first preset value, and the opening degree of the low-pressure inlet regulating valve (510) is fully open; The second condition is: the first temperature is less than the second temperature, and the difference between the two is less than or equal to the first preset value, and the opening degree of the low-pressure inlet regulating valve (510) is proportional to the difference. The third condition is: the first temperature is greater than or equal to the second temperature, and the opening degree of the low-pressure inlet regulating valve (510) is fully closed.

4. The molten salt energy storage system as described in claim 1, characterized in that, The heat exchange unit (300) includes a steam superheater (330) and a steam generator (320); The molten salt inlet of the steam superheater (330) is connected to the first molten salt tank (100), the molten salt outlet of the steam superheater (330) is connected to the molten salt inlet of the steam generator (320), and the steam outlet of the steam superheater (330) is connected to the boiler (410). The molten salt outlet of the steam generator (320) is connected to the molten salt inlet of the molten salt heat exchanger (310), the water inlet pipe of the steam generator (320) is indirectly connected to the water outlet pipe of the low-pressure heater (450), and the steam outlet of the steam generator (320) is connected to the steam inlet of the steam superheater (330).

5. The molten salt energy storage system as described in claim 4, characterized in that, The outlet of the first molten salt tank (100) is connected to a molten salt outlet pipe and a molten salt bypass pipe. The molten salt outlet pipe and the molten salt bypass pipe are connected in parallel. The molten salt outlet pipe is connected to the molten salt inlet of the steam superheater (330). The molten salt bypass pipe is connected to the molten salt flow path of the molten salt heat exchanger (310).

6. The molten salt energy storage system as described in claim 5, characterized in that, The molten salt outlet pipeline is equipped with a molten salt outlet regulating valve (530), and the molten salt bypass pipeline is equipped with a molten salt bypass regulating valve (540).

7. The molten salt energy storage system as described in claim 6, characterized in that, It also includes a second controller, which controls the opening degree of the molten salt bypass control valve (540) according to the fourth condition, the fifth condition and the sixth condition when both the molten salt outlet regulating valve (530) and the molten salt bypass regulating valve (540) are open; The fourth condition is: the temperature at the outlet of the water flow path is less than the temperature at the outlet of the first heated flow path, and the difference between the two is greater than the second preset value, and the opening degree of the molten salt bypass regulating valve (540) is fully open. The fifth condition is: the temperature at the outlet of the water flow path is less than the temperature at the outlet of the first heated flow path, and the difference between the two is less than or equal to the second preset value; the opening degree of the molten salt bypass regulating valve (540) is proportional to the difference between the two. The sixth condition is that the temperature at the outlet of the water flow path is greater than or equal to the temperature at the outlet of the first heated flow path, and the opening degree of the molten salt bypass regulating valve (540) remains unchanged.

8. The molten salt energy storage system as described in claim 4, characterized in that, The thermal power unit (400) includes a high-pressure heater (480), the high-pressure heater (480) includes a second heating flow path and a second heated flow path, the steam extraction port of the steam turbine (420) is connected to the second heating flow path, and the first heated flow path is indirectly connected to the boiler (410) through the second heated flow path; The steam outlet of the steam generator (320) is connected to a high-pressure steam extraction pipe and a steam generator pipe. The high-pressure steam extraction pipe and the steam generator pipe are connected in parallel. The high-pressure steam extraction pipe is connected to the second heating flow path, and the steam generator pipe is connected to the steam superheater (330).

9. The molten salt energy storage system as described in claim 8, characterized in that, The high-pressure steam extraction pipeline is equipped with a high-pressure steam extraction pipeline regulating valve (560), and the steam generator pipeline is equipped with a steam generator outlet pipeline regulating valve (550).

10. The molten salt energy storage system as described in claim 3, characterized in that, The steam outlet of the steam superheater (330) is connected to a reheat pipe and a heating pipe, which are connected in parallel. The reheat pipe is connected to the boiler (410), and a reheat shut-off valve (570) is provided on the reheat pipe. The heating pipe is connected to the steam user, and a heating shut-off valve (580) is provided on the heating pipe.

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