Staged molten salt thermal storage system and control method thereof
The molten salt thermal storage system, with its tiered design and real-time control, solves the problems of low thermal storage efficiency and poor stability caused by fluctuations in heat source temperature, achieving efficient and stable thermal energy storage and utilization.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- 甘肃龙源新能源有限公司
- Filing Date
- 2026-04-24
- Publication Date
- 2026-06-12
Smart Images
Figure CN122192057A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of new energy storage technology, and in particular to a graded molten salt thermal storage system and its control method. Background Technology
[0002] As the global energy structure shifts towards clean energy, energy storage technology has received widespread attention as a key means to address the intermittency and volatility of new energy sources. Molten salt thermal energy storage technology has enormous application potential in large-scale energy storage due to its advantages such as high thermal density, wide operating temperature range, and relatively low cost. However, the temperature of heat sources often fluctuates. For example, in solar thermal systems, changes in solar radiation intensity can lead to unstable temperatures of the heat energy output from the collector. In related technologies, when the heat source temperature is high, the molten salt in the thermal storage system may not be able to fully absorb the heat energy, resulting in heat energy waste, lower system thermal storage efficiency, and lower operational stability. Summary of the Invention
[0003] The present invention aims to at least solve one of the technical problems existing in the prior art. Therefore, one object of the present invention is to provide a graded molten salt thermal energy storage system with high thermal energy storage efficiency and high operational stability.
[0004] The present invention also proposes a control method for the above-mentioned graded molten salt thermal storage system.
[0005] A graded molten salt thermal energy storage system according to a first aspect of the present invention includes: a high-temperature thermal energy storage unit, wherein a first thermal energy storage medium is disposed therein; a medium-temperature thermal energy storage unit, wherein a second thermal energy storage medium is disposed therein, the thermal decomposition temperature of the second thermal energy storage medium being lower than that of the first thermal energy storage medium; a low-temperature thermal energy storage unit, wherein a third thermal energy storage medium is disposed therein, the thermal decomposition temperature of the third thermal energy storage medium being lower than that of the second thermal energy storage medium; a first heat exchanger connected between the high-temperature thermal energy storage unit and the medium-temperature thermal energy storage unit for transferring heat from the high-temperature thermal energy storage unit to the medium-temperature thermal energy storage unit; a second heat exchanger connected between the medium-temperature thermal energy storage unit and the low-temperature thermal energy storage unit for transferring heat from the medium-temperature thermal energy storage unit to the low-temperature thermal energy storage unit; a heat energy input module connected to the high-temperature thermal energy storage unit for inputting heat into the high-temperature thermal energy storage unit; and a heat energy output module connected to the low-temperature thermal energy storage unit for outputting and utilizing the heat from the low-temperature thermal energy storage unit.
[0006] According to embodiments of the present invention, the graded molten salt thermal energy storage system stores thermal energy storage media with different temperature ranges through a graded design of high-temperature thermal energy storage units, medium-temperature thermal energy storage units, and low-temperature thermal energy storage units. This achieves efficient storage and flexible utilization of thermal energy in different temperature ranges, improving the system's thermal energy storage efficiency and operational stability. Furthermore, by connecting the thermal energy input module to the high-temperature thermal energy storage unit, the high-temperature thermal energy storage unit can exchange heat with heat sources with large temperature variations, allowing the thermal energy storage medium in the high-temperature thermal energy storage unit to absorb thermal energy more fully and reducing thermal energy waste. By connecting the thermal energy output module to the low-temperature thermal energy storage unit, the low-temperature thermal energy storage unit can stably output thermal energy, making the heat exchange between the low-temperature thermal energy storage unit and the thermal energy output module more stable, thereby reducing thermal energy waste.
[0007] According to some embodiments of the present invention, the high-temperature thermal storage unit includes a high-temperature molten salt tank, a high-temperature molten salt circulation pipeline, and a high-temperature molten salt pump. The high-temperature molten salt tank is used to store the first thermal storage medium and has a high-temperature molten salt inlet and a high-temperature molten salt outlet. The two ends of the high-temperature molten salt circulation pipeline are respectively connected to the high-temperature molten salt inlet and the high-temperature molten salt outlet. The heat input module is connected to the high-temperature molten salt tank for inputting heat into the high-temperature molten salt tank. The medium-temperature thermal storage unit includes a medium-temperature molten salt tank, a first medium-temperature molten salt circulation pipeline, a first medium-temperature molten salt pump, a second medium-temperature molten salt circulation pipeline, and a second medium-temperature molten salt pump. The medium-temperature molten salt tank is used to store the second thermal storage medium and has a first medium-temperature molten salt inlet, a first medium-temperature molten salt outlet, a second medium-temperature molten salt inlet, and a second medium-temperature molten salt outlet. The two ends of the first medium-temperature molten salt circulation pipeline are respectively connected to the first medium-temperature molten salt inlet and the first medium-temperature molten salt outlet. The two ends of the second medium-temperature molten salt circulation pipeline are respectively connected to the second medium-temperature molten salt inlet and the first medium-temperature molten salt outlet. The second medium-temperature molten salt outlet is described; the low-temperature thermal storage unit includes a low-temperature molten salt tank, a low-temperature molten salt circulation pipeline, and a low-temperature molten salt pump. The low-temperature molten salt tank is used to store the third thermal storage medium and has a low-temperature molten salt inlet and a low-temperature molten salt outlet. The two ends of the low-temperature molten salt circulation pipeline are respectively connected to the low-temperature molten salt inlet and the low-temperature molten salt outlet. The heat output module is connected to the low-temperature molten salt tank for outputting and utilizing the heat in the low-temperature molten salt tank. The first heat exchanger has a first heat exchange channel and a second heat exchange channel that exchange heat with each other. The second heat exchanger has a third heat exchange channel and a fourth heat exchange channel that exchange heat with each other. The high-temperature molten salt pump and the first heat exchange channel are connected in series to the high-temperature molten salt circulation pipeline. The first medium-temperature molten salt pump and the second heat exchange channel are connected in series to the first medium-temperature molten salt circulation pipeline. The second medium-temperature molten salt pump and the third heat exchange channel are connected in series to the second medium-temperature molten salt circulation pipeline. The low-temperature molten salt pump and the fourth heat exchange channel are connected in series to the low-temperature molten salt circulation pipeline.
[0008] According to some embodiments of the present invention, the heat input module includes a heat source, an input pump, and an input pipeline. The high-temperature molten salt tank is provided with a first connection port and a second connection port. The two ends of the input pipeline are respectively connected to the first connection port and the second connection port. A first heating flow channel is formed inside the heat source. The first heating flow channel and the input pump are connected in series to the input pipeline.
[0009] According to some embodiments of the present invention, the heat input module further includes a heater having a second heating channel connected in series with the input pipeline and located downstream of the first heating channel.
[0010] According to some embodiments of the present invention, the heat output module includes a heat utilization heat exchanger, an output pump, and an output pipeline. The low-temperature molten salt tank is provided with a third connection port and a fourth connection port. The two ends of the output pipeline are respectively connected to the third connection port and the fourth connection port. An output heat exchange channel is formed inside the heat utilization heat exchanger. The output heat exchange channel and the output pump are connected in series to the output pipeline. The heat utilization heat exchanger is used to transfer heat to the heat utilization device.
[0011] According to some embodiments of the present invention, the graded molten salt thermal storage system further includes a monitoring component and a control module. The monitoring component includes parameters for monitoring the operating parameters of the high-temperature thermal storage unit, the medium-temperature thermal storage unit, and the high-temperature thermal storage unit. The control module is electrically connected to the monitoring component and is used to adjust the graded molten salt thermal storage system based on the data monitored by the monitoring component. The monitoring component includes a first temperature sensor, a second temperature sensor, and a third temperature sensor. The first temperature sensor is located in the high-temperature molten salt tank, the second temperature sensor is located in the medium-temperature molten salt tank, and the third temperature sensor is located in the low-temperature molten salt tank. And / or, the... The monitoring component includes a first pressure sensor, a second pressure sensor, and a third pressure sensor. The first pressure sensor is located in the high-temperature molten salt tank, the second pressure sensor is located in the medium-temperature molten salt tank, and the third pressure sensor is located in the low-temperature molten salt tank. Alternatively, the monitoring component includes a first flow sensor, a second flow sensor, a third flow sensor, and a fourth flow sensor. The first flow sensor is located in the high-temperature molten salt circulation pipeline, the second flow sensor is located in the first medium-temperature molten salt circulation pipeline, the third flow sensor is located in the second medium-temperature molten salt circulation pipeline, and the fourth flow sensor is located in the low-temperature molten salt circulation pipeline.
[0012] According to some embodiments of the present invention, the first heat storage medium comprises a potassium nitrate-sodium nitrate mixed molten salt; and / or, the second heat storage medium comprises a sodium nitrate-sodium nitrite mixed molten salt; and / or, the third heat storage medium comprises a calcium chloride-magnesium chloride mixed molten salt.
[0013] A control method for a graded molten salt thermal energy storage system according to a second aspect of the present invention, wherein the graded molten salt thermal energy storage system is the graded molten salt thermal energy storage system according to a first aspect of the present invention, the control method comprising: The system monitors the temperature, pressure, and flow rate in each pipeline of the high-temperature molten salt tank, the medium-temperature molten salt tank, and the low-temperature molten salt tank, and transmits the monitored data to the control module in real time. The control module compares and analyzes the received data with preset parameters, and adjusts the system according to the analysis results.
[0014] According to the control method of the graded molten salt thermal storage system of the present invention, by monitoring the temperature, pressure and flow rate in each pipeline of the high-temperature molten salt tank, the medium-temperature molten salt tank and the low-temperature molten salt tank, and transmitting the monitored data to the control module in real time, the heat transfer between multiple thermal storage units can be adjusted according to the received temperature data, and the pressure can be released in a timely manner according to the received pressure data. According to the flow rate data, it is possible to detect whether the molten salt in the pipeline is blocked and to carry out timely maintenance, which is conducive to the high operational safety and stability of the graded molten salt thermal storage system.
[0015] According to some embodiments of the present invention, the control module compares and analyzes the received data with preset parameters, and adjusts the system according to the analysis results, including: When the temperature inside the high-temperature molten salt tank is greater than or equal to the first upper limit threshold, the control module controls the heater to reduce the heating power, controls the delivery pump to reduce the delivery power, and controls the high-temperature molten salt pump and the first medium-temperature molten salt pump to increase the pumping power. When the temperature inside the medium-temperature molten salt tank is greater than or equal to the second upper limit threshold, and the second upper limit threshold is less than the first upper limit threshold, the control module controls the heater to reduce the heating power, controls the delivery pump to reduce the delivery power, controls the high-temperature molten salt pump and the first medium-temperature molten salt pump to reduce the pumping power, and controls the low-temperature molten salt pump and the second medium-temperature molten salt pump to increase the pumping power.
[0016] According to some embodiments of the present invention, the control module compares and analyzes the received data with preset parameters, and adjusts the system according to the analysis results, including: When the temperature inside the high-temperature molten salt tank is less than or equal to the first lower threshold, the control module controls the heater to increase the heating power and controls the delivery pump to increase the delivery power. When the temperature inside the medium-temperature molten salt tank is less than or equal to the second lower threshold, and the second lower threshold is less than the first lower threshold, the control module controls the heater to increase the heating power, controls the delivery pump to increase the delivery power, and controls the high-temperature molten salt pump and the first medium-temperature molten salt pump to increase the pumping power. When the temperature inside the low-temperature molten salt tank is less than or equal to the third lower limit threshold, and the third lower limit threshold is less than the second lower limit threshold, the control module controls the heater to increase the heating power, controls the delivery pump to increase the delivery power, controls the high-temperature molten salt pump and the first medium-temperature molten salt pump to increase the pumping power, and controls the low-temperature molten salt pump and the second medium-temperature molten salt pump to increase the pumping power.
[0017] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description
[0018] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which: Figure 1 This is a schematic diagram of a graded molten salt thermal storage system according to some embodiments of the present invention; Figure 2 This is a flowchart of a control method for a graded molten salt thermal storage system according to some embodiments of the present invention.
[0019] Figure label: 100. Staged molten salt thermal storage system; 10. High-temperature thermal storage unit; 11. High-temperature molten salt tank; 111. High-temperature molten salt inlet; 112. High-temperature molten salt outlet; 113. First connection port; 114. Second connection port; 12. High-temperature molten salt circulation pipeline; 13. High-temperature molten salt pump; 20. Medium-temperature thermal storage unit; 21. Medium-temperature molten salt tank; 211. First medium-temperature molten salt inlet; 212. First medium-temperature molten salt outlet; 213. Second medium-temperature molten salt inlet; 214. Second medium-temperature molten salt outlet; 22. First medium-temperature molten salt circulation pipeline; 23. First medium-temperature molten salt pump; 24. Second medium-temperature molten salt circulation pipeline; 25. Second medium-temperature molten salt pump; 30. Low-temperature thermal storage unit; 31. Low-temperature molten salt tank; 311. Low-temperature molten salt inlet; 312. Low-temperature molten salt outlet; 313. Third connection port; 314. Fourth connection port; 32. Low-temperature molten salt circulation pipeline; 33. Low-temperature molten salt pump; 40. First heat exchanger; 50. Second heat exchanger; 60. Heat input module; 61. Heat source; 62. Input pump; 63. Input pipeline; 64. Heater; 70. Heat output module; 71. Energy utilization heat exchanger; 72. Output pump; 73. Output pipeline; 74. Heat utilization device. Detailed Implementation
[0020] Embodiments of the present invention are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.
[0021] The following is for reference. Figures 1-2 A graded molten salt thermal storage system 100 according to an embodiment of the present invention is described.
[0022] refer to Figure 1 According to a first aspect of the present invention, a graded molten salt thermal energy storage system 100 includes: a high-temperature thermal energy storage unit 10, a medium-temperature thermal energy storage unit 20, a low-temperature thermal energy storage unit 30, a first heat exchanger 40, a second heat exchanger 50, a thermal energy input module 60, and a thermal energy output module 70.
[0023] The high-temperature thermal storage unit 10 contains a first thermal storage medium, the medium-temperature thermal storage unit 20 contains a second thermal storage medium, the thermal decomposition temperature of the second thermal storage medium is lower than that of the first thermal storage medium, and the low-temperature thermal storage unit 30 contains a third thermal storage medium, the thermal decomposition temperature of the third thermal storage medium is lower than that of the second thermal storage medium.
[0024] The first heat exchanger 40 is connected between the high-temperature heat storage unit 10 and the medium-temperature heat storage unit 20 to transfer heat from the high-temperature heat storage unit 10 to the medium-temperature heat storage unit 20. The second heat exchanger 50 is connected between the medium-temperature heat storage unit 20 and the low-temperature heat storage unit 30 to transfer heat from the medium-temperature heat storage unit 20 to the low-temperature heat storage unit 30.
[0025] The heat input module 60 is connected to the high-temperature heat storage unit 10 to input heat into the high-temperature heat storage unit 10. The heat output module 70 is connected to the low-temperature heat storage unit 30 to output and utilize the heat from the low-temperature heat storage unit 30.
[0026] For example, the heat input module 60 is connected to the high-temperature heat storage unit 10 to input heat into the high-temperature heat storage unit 10. The heat energy can be stored in the high-temperature heat storage unit 10, or it can be transferred from the high-temperature heat storage unit 10 to the medium-temperature heat storage unit 20 through the first heat exchanger 40 and stored in the medium-temperature heat storage unit 20. It can also be transferred from the medium-temperature heat storage unit 20 to the low-temperature heat storage unit 30 again through the second heat exchanger 50 and stored in the low-temperature heat storage unit 30.
[0027] By maximizing the thermal decomposition temperature of the first heat storage medium and connecting the heat input module 60 to the high-temperature heat storage unit 10, the high-temperature heat storage unit 10 can exchange heat with the heat source 61, which has a large temperature range, allowing the heat storage medium in the high-temperature heat storage unit 10 to absorb heat energy more fully and reducing heat energy waste.
[0028] By minimizing the thermal decomposition temperature of the third thermal storage medium and connecting the thermal energy output module 70 to the low-temperature thermal storage unit 30, it is beneficial to ensure that the low-temperature thermal storage unit 30 outputs thermal energy stably, making the heat exchange between the low-temperature thermal storage unit 30 and the thermal energy output module 70 more stable, thereby reducing the waste of thermal energy.
[0029] By dividing the thermal storage units according to temperature levels, it is beneficial to enable different thermal storage media to store and release heat within their optimal operating temperature range, avoiding heat loss in a single-stage system due to unsuitable thermal storage medium temperature, thereby improving thermal storage efficiency.
[0030] According to an embodiment of the present invention, the graded molten salt thermal energy storage system 100 stores thermal energy storage media with different temperature ranges through a graded design of a high-temperature thermal energy storage unit 10, a medium-temperature thermal energy storage unit 20, and a low-temperature thermal energy storage unit 30, thereby achieving efficient storage and flexible utilization of thermal energy in different temperature ranges, improving the system's thermal energy storage efficiency and operational stability. Furthermore, by connecting the thermal energy input module 60 to the high-temperature thermal energy storage unit 10, the high-temperature thermal energy storage unit 10 can exchange heat with a heat source 61 with a large temperature range variation, allowing the thermal energy storage medium in the high-temperature thermal energy storage unit 10 to absorb thermal energy more fully and reducing thermal energy waste. By connecting the thermal energy output module 70 to the low-temperature thermal energy storage unit 30, it is beneficial to enable the low-temperature thermal energy storage unit 30 to output thermal energy stably, making the heat exchange between the low-temperature thermal energy storage unit 30 and the thermal energy output module 70 more stable, thereby reducing thermal energy waste.
[0031] According to some embodiments of the present invention, the high-temperature thermal storage unit 10 includes a high-temperature molten salt tank 11, a high-temperature molten salt circulation pipeline 12, and a high-temperature molten salt pump 13. The high-temperature molten salt tank 11 is used to store a first thermal storage medium, and the high-temperature molten salt tank 11 has a high-temperature molten salt inlet 111 and a high-temperature molten salt outlet 112. The two ends of the high-temperature molten salt circulation pipeline 12 are respectively connected to the high-temperature molten salt inlet 111 and the high-temperature molten salt outlet 112. The heat energy input module 60 is connected to the high-temperature molten salt tank 11 for inputting heat into the high-temperature molten salt tank 11; the medium-temperature thermal storage unit 20 includes a medium-temperature molten salt tank 11. The system includes a medium-temperature molten salt tank 21, a first medium-temperature molten salt circulation pipeline 22, a first medium-temperature molten salt pump 23, a second medium-temperature molten salt circulation pipeline 24, and a second medium-temperature molten salt pump 25. The medium-temperature molten salt tank 21 is used to store the second heat storage medium and has a first medium-temperature molten salt inlet 211, a first medium-temperature molten salt outlet, a second medium-temperature molten salt inlet 213, and a second medium-temperature molten salt outlet. The two ends of the first medium-temperature molten salt circulation pipeline 22 are connected to the first medium-temperature molten salt inlet 211 and the first medium-temperature molten salt outlet 212, respectively. The two ends of the second medium-temperature molten salt circulation pipeline 24 are connected to... The second intermediate-temperature molten salt inlet 213 and the second intermediate-temperature molten salt outlet 214 are connected separately. The low-temperature thermal storage unit 30 includes a low-temperature molten salt tank 31, a low-temperature molten salt circulation pipeline 32, and a low-temperature molten salt pump 33. The low-temperature molten salt tank 31 is used to store the third thermal storage medium, and the low-temperature molten salt tank 31 has a low-temperature molten salt inlet 311 and a low-temperature molten salt outlet 312. The two ends of the low-temperature molten salt circulation pipeline 32 are respectively connected to the low-temperature molten salt inlet 311 and the low-temperature molten salt outlet 312. The heat output module 70 is connected to the low-temperature molten salt tank 31 to discharge the heat from the low-temperature molten salt tank 31. Heat output utilization; the first heat exchanger 40 has a first heat exchange channel and a second heat exchange channel that exchange heat with each other, the second heat exchanger 50 has a third heat exchange channel and a fourth heat exchange channel that exchange heat with each other, the high temperature molten salt pump 13 and the first heat exchange channel are connected in series to the high temperature molten salt circulation pipeline 12, the first medium temperature molten salt pump 23 and the second heat exchange channel are connected in series to the first medium temperature molten salt circulation pipeline 22, the second medium temperature molten salt pump 25 and the third heat exchange channel are connected in series to the second medium temperature molten salt circulation pipeline 24, and the low temperature molten salt pump 33 and the fourth heat exchange channel are connected in series to the low temperature molten salt circulation pipeline 32.
[0032] For example, when the heat from the high-temperature thermal storage unit 10 is transferred to the medium-temperature thermal storage unit 20, the high-temperature molten salt pump 13 and the first medium-temperature molten salt pump 23 are started. The first thermal storage medium in the high-temperature molten salt tank 11 flows from the high-temperature molten salt outlet 112 into the high-temperature molten salt circulation pipeline 12 and flows through the first heat exchange channel. The second thermal storage medium in the medium-temperature molten salt tank 21 flows from the first medium-temperature molten salt outlet 212 into the first medium-temperature molten salt circulation pipeline 22 and flows through the second heat exchange channel. The first thermal storage medium in the first heat exchange channel and the second thermal storage medium in the second heat exchange channel exchange heat, causing the temperature of the first thermal storage medium to decrease and the temperature of the second thermal storage medium to increase. The first thermal storage medium with a decreased temperature flows back to the high-temperature molten salt tank 11 from the high-temperature molten salt inlet through the high-temperature molten salt circulation pipeline 12, and the second thermal storage medium with a increased temperature flows back to the medium-temperature molten salt tank 21 from the first medium-temperature molten salt inlet through the first medium-temperature molten salt circulation pipeline 22.
[0033] For example, when the heat from the medium-temperature thermal storage unit 20 is transferred to the low-temperature thermal storage unit 30, the second medium-temperature molten salt pump 25 and the low-temperature molten salt pump 33 are started. The second thermal storage medium in the medium-temperature molten salt tank 21 flows from the second medium-temperature molten salt outlet 214 into the second medium-temperature molten salt circulation pipeline 24 and flows through the third heat exchange channel. The third thermal storage medium in the low-temperature molten salt tank 31 flows from the low-temperature molten salt outlet 312 into the low-temperature molten salt circulation pipeline 32 and flows through the fourth heat exchange channel. The second thermal storage medium in the third heat exchange channel exchanges heat with the third thermal storage medium in the fourth heat exchange channel, causing the temperature of the second thermal storage medium to decrease and the temperature of the third thermal storage medium to increase. The second thermal storage medium with the decreased temperature then flows back into the medium-temperature molten salt tank 21 from the second medium-temperature molten salt inlet through the second medium-temperature molten salt circulation pipeline 24.
[0034] By providing a first heat exchanger 40 and a second heat exchanger 50, the heat stored in the high-temperature molten salt tank 11 can be transferred relatively stably to the medium-temperature molten salt tank 21 through heat exchange between the high-temperature molten salt and the medium-temperature molten salt. The heat in the medium-temperature molten salt tank 21 can be transferred relatively stably to the low-temperature molten salt tank 31 through heat exchange between the medium-temperature molten salt and the low-temperature molten salt. This achieves efficient storage and flexible utilization of thermal energy in different temperature ranges, and improves the heat storage efficiency and operational stability of the graded molten salt thermal energy storage system 100.
[0035] According to some embodiments of the present invention, the heat input module 60 includes a heat source 61, an input pump 62 and an input pipeline 63. The high-temperature molten salt tank 11 is provided with a first connection port 113 and a second connection port 114. The two ends of the input pipeline 63 are respectively connected to the first connection port 113 and the second connection port 114. A first heating flow channel is formed in the heat source 61. The first heating flow channel and the input pump 62 are connected in series to the input pipeline 63.
[0036] For example, when the heat source 61 generates heat, the input pump 62 starts, and the first heat storage medium in the high-temperature molten salt tank 11 flows into the input pipe 63 from the first connection port 113 and flows through the first heating channel in the heat source 61 to exchange heat with the heat source 61. The first heat storage medium with increased temperature then flows back to the high-temperature molten salt tank 11 from the second connection port 114 through the input pipe 63 to store the heat in the high-temperature molten salt tank 11.
[0037] By providing an input pipe 63 and forming a first heating channel within the heat source 61, heat is transferred relatively stably to the high-temperature molten salt tank 11 through heat exchange between the high-temperature molten salt and the heat source 61. This facilitates the stable storage of heat in the heat source 61 and improves the heat storage efficiency and operational stability of the graded molten salt thermal storage system 100.
[0038] According to some embodiments of the present invention, the heat input module 60 further includes a heater 64 having a second heating channel connected in series with the input pipe 63 and located downstream of the first heating channel.
[0039] By including a heater 64 in the heat input module 60 and positioning the second heating channel downstream of the first heating channel, heat can be supplemented when the heat source 61 is insufficient, ensuring that the heat input from the heat input module 60 to the high-temperature heat storage unit 10 is not too low. This helps maintain the optimal heat storage temperature of the molten salt and improves the heat storage efficiency of the graded molten salt heat storage system 100.
[0040] According to some embodiments of the present invention, the heat output module 70 includes a heat utilization heat exchanger, an output pump 72, and an output pipeline 73. The low-temperature molten salt tank 31 is provided with a third connection port 313 and a fourth connection port 314. The two ends of the output pipeline 73 are respectively connected to the third connection port 313 and the fourth connection port 314. An output heat exchange channel is formed inside the heat utilization heat exchanger. The output heat exchange channel and the output pump 72 are connected in series to the output pipeline 73. The heat utilization heat exchanger is used to transfer heat to the heat utilization device 74.
[0041] For example, when heat energy needs to be supplied to the heat utilization device 74, the output pump 72 is started, and the third heat storage medium in the low temperature molten salt tank 31 flows into the output pipeline 73 from the third connection port 313 and flows through the output heat exchange channel in the heat utilization heat exchanger. The heat utilization heat exchanger is used to transfer heat to the heat utilization device 74. The third heat storage medium with reduced temperature then flows back to the low temperature molten salt tank 31 from the fourth connection port 314 through the output pipeline 73.
[0042] By incorporating a heat exchanger, the heat stored in the low-temperature molten salt tank 31 is transferred to the heat utilization device 74 relatively stably through heat exchange between the low-temperature molten salt and the heat exchanger. This facilitates a stable supply of heat energy to the heat utilization device 74 and improves the heat storage efficiency and operational stability of the graded molten salt heat storage system 100.
[0043] According to some embodiments of the present invention, the graded molten salt thermal storage system 100 further includes a monitoring component and a control module. The monitoring component includes a component for monitoring the operating parameters of the high-temperature thermal storage unit 10, the medium-temperature thermal storage unit 20, and the high-temperature thermal storage unit 10. The control module is electrically connected to the monitoring component and is used to adjust the graded molten salt thermal storage system 100 according to the data monitored by the monitoring component. The monitoring component includes a first temperature sensor, a second temperature sensor, and a third temperature sensor. The first temperature sensor is located in the high-temperature molten salt tank 11, the second temperature sensor is located in the medium-temperature molten salt tank 21, and the third temperature sensor is located in the low-temperature molten salt tank 31.
[0044] For example, a control module may include a PLC (Programmable Logic Controller).
[0045] By installing a first temperature sensor, a second temperature sensor, and a third temperature sensor in the high-temperature molten salt tank 11, the medium-temperature molten salt tank 21, and the low-temperature molten salt tank 31 respectively, the temperatures of the first, second, and third heat storage media can be monitored in real time. This allows the control module to adjust the graded molten salt heat storage system 100 based on the temperature data, enabling different heat storage media to store and release heat within their optimal operating temperature range. This avoids heat loss in a single-stage system due to unsuitable heat storage medium temperatures, thereby improving heat storage efficiency.
[0046] According to some embodiments of the present invention, the monitoring component includes a first pressure sensor, a second pressure sensor and a third pressure sensor, wherein the first pressure sensor is disposed in a high-temperature molten salt tank 11, the second pressure sensor is disposed in a medium-temperature molten salt tank 21 and the third pressure sensor is disposed in a low-temperature molten salt tank 31.
[0047] For example, the high-temperature molten salt tank 11, the medium-temperature molten salt tank 21, and the low-temperature molten salt tank 31 can be equipped with pressure relief valves. When the first pressure sensor, the second pressure sensor, and the third pressure sensor detect that the pressure inside the tank is too high, the pressure relief valves can be opened to release the pressure.
[0048] By installing a first pressure sensor, a second pressure sensor, and a third pressure sensor in the high-temperature molten salt tank 11, the medium-temperature molten salt tank 21, and the low-temperature molten salt tank 31 respectively, the pressure in these tanks can be monitored in real time. This allows for pressure relief when excessive gas is generated from the volatilization or decomposition of the first, second, and third heat storage media, leading to excessive pressure inside the tanks. This prevents rupture in the high-temperature molten salt tank 11, the medium-temperature molten salt tank 21, and the low-temperature molten salt tank 31, thereby improving the safety of the graded molten salt heat storage system 100.
[0049] According to some embodiments of the present invention, the monitoring component includes a first flow sensor, a second flow sensor, a third flow sensor and a fourth flow sensor. The first flow sensor is located in the high-temperature molten salt circulation pipeline 12, the second flow sensor is located in the first medium-temperature molten salt circulation pipeline 22, the third flow sensor is located in the second medium-temperature molten salt circulation pipeline 24, and the fourth flow sensor is located in the low-temperature molten salt circulation pipeline 32.
[0050] For example, when the first flow sensor, the second flow sensor, the third flow sensor, and the fourth flow sensor detect abnormal flow, an alarm can be issued and the control module can be used to shut down the operation of the graded molten salt thermal storage system 100, making it easier for manual maintenance.
[0051] By installing flow sensors in the high-temperature molten salt circulation pipeline 12, the first medium-temperature molten salt circulation pipeline 22, the second medium-temperature molten salt circulation pipeline 24, and the low-temperature molten salt circulation pipeline 32, the flow rate of molten salt in the pipeline can be monitored in real time. This allows for timely detection and appropriate measures to be taken when the pipeline becomes blocked, thereby improving the safety of the graded molten salt thermal energy storage system 100.
[0052] According to some embodiments of the present invention, the first heat storage medium comprises a potassium nitrate-sodium nitrate mixed molten salt.
[0053] For example, the mass ratio of potassium nitrate to sodium nitrate in a potassium nitrate-sodium nitrate mixed molten salt can be 60:40.
[0054] By including potassium nitrate-sodium nitrate mixed molten salt in the first heat storage medium, the first heat storage medium can have a lower melting point and a higher specific heat capacity, which is beneficial to the first heat storage medium having a wider operating temperature range, the first heat storage medium being able to store more heat, and also the first heat storage medium having better thermal stability.
[0055] According to some embodiments of the present invention, the second heat storage medium comprises a sodium nitrate-sodium nitrite mixed molten salt.
[0056] For example, the mass ratio of sodium nitrate to sodium nitrite in a sodium nitrate-sodium nitrite mixed molten salt can be 50:50.
[0057] By including a sodium nitrate-sodium nitrite mixed molten salt in the second heat storage medium, the second heat storage medium can have a lower melting point and a higher specific heat capacity, which is beneficial to a wider operating temperature range, a greater amount of heat that can be stored, and better thermal stability.
[0058] According to some embodiments of the present invention, the third heat storage medium comprises a calcium chloride-magnesium chloride mixed molten salt.
[0059] For example, the mass ratio of calcium chloride to magnesium chloride in a calcium chloride-magnesium chloride mixed molten salt can be 70:30.
[0060] By including a calcium chloride-magnesium chloride mixed molten salt in the third heat storage medium, the third heat storage medium can have a lower melting point and a higher specific heat capacity, which is beneficial to a wider operating temperature range, a greater amount of heat that can be stored, and better thermal stability.
[0061] refer to Figure 2 According to a second aspect embodiment of the present invention, a control method for a graded molten salt thermal storage system 100, wherein the graded molten salt thermal storage system 100 is a graded molten salt thermal storage system 100 according to a first aspect embodiment of the present invention, the control method includes: The system monitors the temperature, pressure, and flow rate of each pipeline in the high-temperature molten salt tank 11, the medium-temperature molten salt tank 21, and the low-temperature molten salt tank 31, and transmits the monitored data to the control module in real time. The control module compares and analyzes the received data with preset parameters, and adjusts the system according to the analysis results.
[0062] According to the control method of the graded molten salt thermal storage system 100 of the present invention, by monitoring the temperature, pressure and flow rate in each pipeline of the high-temperature molten salt tank 11, the medium-temperature molten salt tank 21 and the low-temperature molten salt tank 31, and transmitting the monitored data to the control module in real time, the heat transfer between multiple thermal storage units can be adjusted according to the received temperature data, and the pressure can be released in a timely manner according to the received pressure data. According to the flow rate data, it is possible to detect whether the molten salt in the pipeline is blocked and to carry out timely maintenance, which is beneficial to the high operational safety and stability of the graded molten salt thermal storage system 100.
[0063] According to some embodiments of the present invention, the control module compares and analyzes the received data with preset parameters, and adjusts the system according to the analysis results, including: When the temperature inside the high-temperature molten salt tank 11 is greater than or equal to the first upper limit threshold, the control module controls the heater 64 to reduce the heating power, controls the delivery pump to reduce the delivery power, and controls the high-temperature molten salt pump 13 and the first medium-temperature molten salt pump 23 to increase the pumping power. When the temperature inside the medium-temperature molten salt tank 21 is greater than or equal to the second upper limit threshold, and the second upper limit threshold is less than the first upper limit threshold, the control module controls the heater 64 to reduce the heating power, controls the delivery pump to reduce the delivery power, controls the high-temperature molten salt pump 13 and the first medium-temperature molten salt pump 23 to reduce the pumping power, and controls the low-temperature molten salt pump 33 and the second medium-temperature molten salt pump 25 to increase the pumping power.
[0064] For example, the range of the first upper limit temperature threshold can be 550-600℃, such as 550℃, 560℃, 570℃, 580℃, 590℃, 600℃, etc.
[0065] For example, the range of the second upper limit threshold can be 350-400℃, such as 350℃, 360℃, 370℃, 380℃, 390℃, 400℃, etc.
[0066] Among them, the first lower threshold is less than the first upper threshold, and the second lower threshold is less than the second upper threshold.
[0067] By adopting the above control method, when the temperature in the high-temperature molten salt tank 11 is greater than or equal to the first upper limit threshold, the heat input module 60 can reduce the heat transferred to the high-temperature thermal storage unit 10 and increase the heat transferred from the high-temperature thermal storage unit 10 to the medium-temperature thermal storage unit 20, thus preventing the molten salt in the high-temperature molten salt tank 11 from decomposing or vaporizing due to excessively high temperature. Similarly, when the temperature in the medium-temperature molten salt tank 21 is greater than or equal to the second upper limit threshold, the heat transferred from the high-temperature thermal storage unit 10 to the medium-temperature thermal storage unit 20 can be reduced and the heat transferred from the medium-temperature thermal storage unit 20 to the low-temperature thermal storage unit 30 can be increased, thus preventing the molten salt in the medium-temperature molten salt tank 21 from decomposing or vaporizing due to excessively high temperature, thereby improving the operational safety and stability of the graded molten salt thermal storage system 100.
[0068] According to some embodiments of the present invention, the control module compares and analyzes the received data with preset parameters, and adjusts the system according to the analysis results, including: When the temperature inside the high-temperature molten salt tank 11 is less than or equal to the first lower threshold, the control module controls the heater 64 to increase the heating power and controls the delivery pump to increase the delivery power. When the temperature inside the medium-temperature molten salt tank 21 is less than or equal to the second lower threshold, and the second lower threshold is less than the first lower threshold, the control module controls the heater 64 to increase the heating power, controls the delivery pump to increase the delivery power, and controls the high-temperature molten salt pump 13 and the first medium-temperature molten salt pump 23 to increase the pumping power. When the temperature inside the low-temperature molten salt tank 31 is less than or equal to the third lower threshold, and the third lower threshold is less than the second lower threshold, the control module controls the heater 64 to increase the heating power, controls the delivery pump to increase the delivery power, controls the high-temperature molten salt pump 13 and the first medium-temperature molten salt pump 23 to increase the pumping power, and controls the low-temperature molten salt pump 33 and the second medium-temperature molten salt pump 25 to increase the pumping power.
[0069] For example, the range of the first lower threshold can be 450-500℃, such as 450℃, 460℃, 470℃, 480℃, 490℃, 500℃, etc.
[0070] For example, the range of the second lower limit threshold can be 250-300℃, such as 250℃, 260℃, 270℃, 280℃, 290℃, 300℃, etc.
[0071] For example, the value range of the third lower limit threshold can be 50-100℃, such as 50℃, 60℃, 70℃, 80℃, 90℃, 100℃, etc.
[0072] By employing the above control methods, when the temperature in the high-temperature molten salt tank 11 is less than or equal to the first lower threshold, the heat input module 60 can be increased to supply heat to the high-temperature thermal storage unit 10, preventing the molten salt in the high-temperature molten salt tank 11 from freezing due to excessively low temperature. Similarly, when the temperature in the medium-temperature molten salt tank 21 is less than or equal to the second lower threshold, the heat input module 60 and the high-temperature thermal storage unit 10 can be increased to supply heat to the medium-temperature thermal storage unit 20, preventing the molten salt in the medium-temperature molten salt tank 21 from freezing due to excessively low temperature. Furthermore, when the temperature in the low-temperature molten salt tank 31 is less than or equal to the third lower threshold, the heat input module 60, the high-temperature thermal storage unit 10, and the medium-temperature thermal storage unit 20 can be increased to supply heat to the low-temperature thermal storage unit 30, preventing the molten salt in the low-temperature molten salt tank 31 from freezing due to excessively low temperature. This prevents blockage of the molten salt in the tanks or pipelines, improving the operational safety and stability of the graded molten salt thermal storage system 100.
[0073] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention 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. Therefore, they should not be construed as limitations on this invention.
[0074] In the description of this invention, "first feature" and "second feature" may include one or more of the features.
[0075] In the description of this invention, "a plurality of" means two or more.
[0076] In the description of this invention, the first feature being "above" or "below" the second feature may include the first and second features being in direct contact, or it may include the first and second features not being in direct contact but being in contact through another feature between them.
[0077] In the description of this invention, the terms "above," "over," and "on top" for the first feature and the second feature include the first feature being directly above or diagonally above the second feature, or simply indicating that the first feature is at a higher horizontal level than the second feature.
[0078] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.
[0079] Although embodiments of the invention have been shown and described, those skilled in the art will understand that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the claims and their equivalents.
Claims
1. A graded molten salt thermal storage system, characterized in that, include: A high-temperature thermal storage unit, wherein a first thermal storage medium is provided inside the high-temperature thermal storage unit; A medium-temperature thermal storage unit, wherein a second thermal storage medium is provided in the medium-temperature thermal storage unit, and the thermal decomposition temperature of the second thermal storage medium is lower than that of the first thermal storage medium. A low-temperature thermal storage unit, wherein a third thermal storage medium is provided in the low-temperature thermal storage unit, and the thermal decomposition temperature of the third thermal storage medium is lower than that of the second thermal storage medium. A first heat exchanger is connected between the high-temperature thermal storage unit and the medium-temperature thermal storage unit to transfer heat from the high-temperature thermal storage unit to the medium-temperature thermal storage unit. A second heat exchanger is connected between the medium-temperature thermal storage unit and the low-temperature thermal storage unit to transfer heat from the medium-temperature thermal storage unit to the low-temperature thermal storage unit. A heat input module is connected to the high-temperature heat storage unit to input heat into the high-temperature heat storage unit. A heat output module is connected to the low-temperature thermal storage unit to output and utilize the heat from the low-temperature thermal storage unit.
2. The staged molten salt thermal storage system according to claim 1, characterized in that, The high-temperature thermal storage unit includes a high-temperature molten salt tank, a high-temperature molten salt circulation pipeline, and a high-temperature molten salt pump. The high-temperature molten salt tank is used to store the first thermal storage medium and has a high-temperature molten salt inlet and a high-temperature molten salt outlet. The two ends of the high-temperature molten salt circulation pipeline are respectively connected to the high-temperature molten salt inlet and the high-temperature molten salt outlet. The heat energy input module is connected to the high-temperature molten salt tank to input heat into the high-temperature molten salt tank. The medium-temperature thermal storage unit includes a medium-temperature molten salt tank, a first medium-temperature molten salt circulation pipeline, a first medium-temperature molten salt pump, a second medium-temperature molten salt circulation pipeline, and a second medium-temperature molten salt pump. The medium-temperature molten salt tank is used to store the second thermal storage medium and has a first medium-temperature molten salt inlet, a first medium-temperature molten salt outlet, a second medium-temperature molten salt inlet, and a second medium-temperature molten salt outlet. The two ends of the first medium-temperature molten salt circulation pipeline are respectively connected to the first medium-temperature molten salt inlet and the first medium-temperature molten salt outlet, and the two ends of the second medium-temperature molten salt circulation pipeline are respectively connected to the second medium-temperature molten salt inlet and the second medium-temperature molten salt outlet. The cryogenic thermal storage unit includes a cryogenic molten salt tank, a cryogenic molten salt circulation pipeline, and a cryogenic molten salt pump. The cryogenic molten salt tank is used to store the third thermal storage medium and has a cryogenic molten salt inlet and a cryogenic molten salt outlet. The two ends of the cryogenic molten salt circulation pipeline are respectively connected to the cryogenic molten salt inlet and the cryogenic molten salt outlet. The heat energy output module is connected to the cryogenic molten salt tank to output and utilize the heat in the cryogenic molten salt tank. The first heat exchanger has a first heat exchange channel and a second heat exchange channel that exchange heat with each other, and the second heat exchanger has a third heat exchange channel and a fourth heat exchange channel that exchange heat with each other. The high-temperature molten salt pump and the first heat exchange channel are connected in series to the high-temperature molten salt circulation pipeline. The first medium-temperature molten salt pump and the second heat exchange channel are connected in series to the first medium-temperature molten salt circulation pipeline. The second medium-temperature molten salt pump and the third heat exchange channel are connected in series to the second medium-temperature molten salt circulation pipeline. The low-temperature molten salt pump and the fourth heat exchange channel are connected in series to the low-temperature molten salt circulation pipeline.
3. The staged molten salt thermal storage system according to claim 2, characterized in that, The heat input module includes a heat source, an input pump, and an input pipeline. The high-temperature molten salt tank is provided with a first connection port and a second connection port. The two ends of the input pipeline are respectively connected to the first connection port and the second connection port. A first heating flow channel is formed inside the heat source. The first heating flow channel and the input pump are connected in series to the input pipeline.
4. The staged molten salt thermal storage system according to claim 3, characterized in that, The heat input module further includes a heater, which has a second heating channel connected in series with the input pipeline and located downstream of the first heating channel.
5. The staged molten salt thermal storage system according to claim 2, characterized in that, The heat output module includes a heat utilization heat exchanger, an output pump, and an output pipeline. The low-temperature molten salt tank is provided with a third connection port and a fourth connection port. The two ends of the output pipeline are respectively connected to the third connection port and the fourth connection port. An output heat exchange channel is formed inside the heat utilization heat exchanger. The output heat exchange channel and the output pump are connected in series to the output pipeline. The heat utilization heat exchanger is used to transfer heat to the heat utilization device.
6. The graded molten salt thermal storage system according to claim 2, characterized in that, It also includes a monitoring component and a control module. The monitoring component includes a function for monitoring the operating parameters of the high-temperature thermal storage unit, the medium-temperature thermal storage unit, and the high-temperature thermal storage unit. The control module is electrically connected to the monitoring component and is used to adjust the graded molten salt thermal storage system according to the data monitored by the monitoring component. The monitoring component includes a first temperature sensor, a second temperature sensor, and a third temperature sensor, wherein the first temperature sensor is located in the high-temperature molten salt tank, the second temperature sensor is located in the medium-temperature molten salt tank, and the third temperature sensor is located in the low-temperature molten salt tank; and / or, the monitoring component includes a first pressure sensor, a second pressure sensor, and a third pressure sensor, wherein the first pressure sensor is located in the high-temperature molten salt tank, the second pressure sensor is located in the medium-temperature molten salt tank, and the third pressure sensor is located in the low-temperature molten salt tank; and / or, the monitoring component includes a first flow sensor, a second flow sensor, a third flow sensor, and a fourth flow sensor, wherein the first flow sensor is located in the high-temperature molten salt circulation pipeline, the second flow sensor is located in the first medium-temperature molten salt circulation pipeline, the third flow sensor is located in the second medium-temperature molten salt circulation pipeline, and the fourth flow sensor is located in the low-temperature molten salt circulation pipeline.
7. The staged molten salt thermal storage system according to any one of claims 1-6, characterized in that, The first heat storage medium comprises a potassium nitrate-sodium nitrate mixed molten salt; and / or, the second heat storage medium comprises a sodium nitrate-sodium nitrite mixed molten salt; and / or, the third heat storage medium comprises a calcium chloride-magnesium chloride mixed molten salt.
8. A control method for a graded molten salt thermal storage system according to any one of claims 2-6, characterized in that, include: The system monitors the temperature, pressure, and flow rate in each pipeline of the high-temperature molten salt tank, the medium-temperature molten salt tank, and the low-temperature molten salt tank, and transmits the monitored data to the control module in real time. The control module compares and analyzes the received data with preset parameters, and adjusts the system according to the analysis results.
9. The control method for the graded molten salt thermal storage system according to claim 8, characterized in that, The control module compares and analyzes the received data with preset parameters, and adjusts the system according to the analysis results, including: When the temperature inside the high-temperature molten salt tank is greater than or equal to the first upper limit threshold, the control module controls the heater to reduce the heating power, controls the delivery pump to reduce the delivery power, and controls the high-temperature molten salt pump and the first medium-temperature molten salt pump to increase the pumping power. When the temperature inside the medium-temperature molten salt tank is greater than or equal to the second upper limit threshold, and the second upper limit threshold is less than the first upper limit threshold, the control module controls the heater to reduce the heating power, controls the delivery pump to reduce the delivery power, controls the high-temperature molten salt pump and the first medium-temperature molten salt pump to reduce the pumping power, and controls the low-temperature molten salt pump and the second medium-temperature molten salt pump to increase the pumping power.
10. The control method for the graded molten salt thermal storage system according to claim 8, characterized in that, The control module compares and analyzes the received data with preset parameters, and adjusts the system according to the analysis results, including: When the temperature inside the high-temperature molten salt tank is less than or equal to the first lower threshold, the control module controls the heater to increase the heating power and controls the delivery pump to increase the delivery power. When the temperature inside the medium-temperature molten salt tank is less than or equal to the second lower threshold, and the second lower threshold is less than the first lower threshold, the control module controls the heater to increase the heating power, controls the delivery pump to increase the delivery power, and controls the high-temperature molten salt pump and the first medium-temperature molten salt pump to increase the pumping power. When the temperature inside the low-temperature molten salt tank is less than or equal to the third lower limit threshold, and the third lower limit threshold is less than the second lower limit threshold, the control module controls the heater to increase the heating power, controls the delivery pump to increase the delivery power, controls the high-temperature molten salt pump and the first medium-temperature molten salt pump to increase the pumping power, and controls the low-temperature molten salt pump and the second medium-temperature molten salt pump to increase the pumping power.