Molten salt energy storage system and photo-thermal power station

Abstract

The invention relates to a fused salt energy storage system and a photo-thermal power station. The fused salt energy storage system comprises a solar heat absorber which comprises a low-temperature fused salt inlet and a high-temperature fused salt outlet; the steam generation system comprises a high-temperature fused salt inlet, a low-temperature fused salt outlet, a feed water inlet and a steam outlet, and the steam outlet is used for being connected to a load end; the high-temperature molten salt tank is connected between the high-temperature molten salt outlet and the high-temperature molten salt inlet; the low-temperature molten salt tank is connected between the low-temperature molten salt inlet and the low-temperature molten salt outlet; the water storage tank is communicated with the water supply inlet; the anti-freezing assembly is wound on the outer side of the pipeline between the solar heat absorber and the high-temperature molten salt tank, the anti-freezing assembly comprises a pipeline heat tracing piece, a heat reflecting layer and a heat preservation layer, the pipeline heat tracing piece is spirally wound on the pipeline in the length direction of the pipeline, and the heat reflecting layer is located between the pipeline heat tracing piece and the heat preservation layer.

Description

Technical Field

[0001] This application relates to the field of energy storage technology, and in particular to a molten salt energy storage system and a solar thermal power plant. Background Technology

[0002] In molten salt energy storage systems, molten salt serves as the core medium for heat storage and transfer. Its fluidity and the stability of heat supply directly determine the efficiency of the steam generation system, which in turn affects the operating efficiency of the load end connected to the steam generation system.

[0003] When the ambient temperature is in the low-temperature range, the viscosity of molten salt in the conveying pipeline can increase significantly due to the drop in temperature, reducing its fluidity. In extreme cases, it may even freeze locally within the conveying pipeline. Frozen molten salt can not only block the conveying pipeline and interrupt heat transfer, but may also generate local pressure due to volume collisions, damaging the conveying pipeline and related accessories, seriously affecting the continuity of system operation. Summary of the Invention

[0004] This application provides a molten salt energy storage system and a solar thermal power plant to address the shortcomings of related technologies.

[0005] According to a first aspect of the embodiments of this application, a molten salt energy storage system is provided, comprising: A solar thermal absorber, comprising a low-temperature molten salt inlet and a high-temperature molten salt outlet; A steam generating system, comprising a high-temperature molten salt inlet, a low-temperature molten salt outlet, a feedwater inlet, and a steam outlet, wherein the steam outlet is used to connect to the load end; A high-temperature molten salt tank, wherein the high-temperature molten salt tank is connected between the high-temperature molten salt outlet and the high-temperature molten salt inlet; A cryogenic molten salt tank, wherein the cryogenic molten salt tank is connected between the cryogenic molten salt inlet and the cryogenic molten salt outlet; A water storage tank, which is connected to the water supply inlet; An antifreeze assembly is wound around the outside of the pipe between the solar absorber and the high-temperature molten salt tank. The antifreeze assembly includes a pipe heat tracing element, a heat reflective layer, and an insulation layer. The pipe heat tracing element is spirally wound around the pipe along its length, and the heat reflective layer is located between the pipe heat tracing element and the insulation layer.

[0006] Optionally, the pipeline heat tracing component includes a self-regulating electric heat tracing component, and the molten salt energy storage system further includes a controller and a molten salt temperature sensor, wherein the molten salt temperature sensor is located close to the inlet of the high-temperature molten salt tank; The controller is electrically connected to the self-regulating electric heat tracing element and the molten salt temperature sensor respectively. The controller is used to control the start / stop state switching of the self-regulating electric heat tracing element according to the molten salt temperature of the molten salt temperature sensor.

[0007] Optionally, it also includes a steam pressure sensor, a steam temperature sensor, and a molten salt flow control valve, which are electrically connected to the controller respectively; The steam pressure sensor and the steam temperature sensor are respectively located near the steam outlet, and the molten salt flow control valve is located near the inlet of the high-temperature molten salt tank; The controller is used to adjust the opening degree of the molten salt flow control valve according to the real-time steam pressure, real-time steam temperature and molten salt temperature.

[0008] Optionally, it also includes a molten salt flow shut-off valve electrically connected to the controller, the molten salt flow shut-off valve being disposed between the solar absorber and the antifreeze component; The controller is used to control the molten salt flow control valve to switch to the lowest safe opening degree and control the molten salt flow shut-off valve to the shut-off state when the real-time steam pressure is greater than the steam overpressure threshold.

[0009] Optionally, it also includes a molten salt flow control valve and a molten salt flow shut-off valve electrically connected to the controller, wherein the molten salt flow shut-off valve is disposed between the solar absorber and the antifreeze component; The controller is used to control the molten salt flow control valve to switch to the lowest safe opening degree and control the molten salt flow cut-off valve to switch to the cut-off state when the molten salt temperature is lower than the molten salt freezing warning temperature.

[0010] Optionally, it may also include an alarm module electrically connected to the controller, wherein the controller is used to trigger the alarm mode of the alarm module.

[0011] Optionally, the controller further includes a remote communication module, which is used to establish a communication connection with a remote communication terminal to send the operating parameters of the molten salt energy storage system to the remote communication terminal.

[0012] Optional, also includes: A first pump body is connected between the high-temperature molten salt tank and the high-temperature molten salt inlet; A second pump body is connected between the cryogenic molten salt tank and the cryogenic molten salt inlet; The third pump body is connected between the water storage tank and the water inlet.

[0013] Optionally, the insulation layer includes an aluminum silicate cotton layer, wherein the thickness of the aluminum silicate cotton layer is greater than or equal to 50 mm and less than or equal to 80 mm.

[0014] According to a second aspect of the embodiments of this application, a concentrated solar power (CSP) plant is provided, comprising: Power generation equipment; As described in any of the preceding molten salt energy storage systems, the steam outlet of the molten salt energy storage system is connected to the power generation device.

[0015] The technical solutions provided by the embodiments of this application may include the following beneficial effects: As can be seen from the above embodiments, the antifreeze component in this application is wrapped around the outside of the molten salt conveying pipe, eliminating the need for the complex internal structure of the molten salt conveying pipe. Subsequent maintenance does not require disassembling the molten salt conveying pipe, resulting in significant cost and maintenance advantages. Moreover, through the heat reflection effect of the heat reflection layer and the heat insulation effect of the insulation layer, the heating and heat insulation effects of the antifreeze component can be improved, thereby enhancing the antifreeze performance.

[0016] It should be understood that the above general description and the following detailed description are exemplary and explanatory only, and do not limit this application. Attached Figure Description

[0017] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application.

[0018] Figure 1 This is a block diagram illustrating a molten salt energy storage system according to an exemplary embodiment.

[0019] Figure 2 This is a block diagram illustrating another molten salt energy storage system according to an exemplary embodiment.

[0020] Figure 3 This is a block diagram illustrating yet another molten salt energy storage system according to an exemplary embodiment. Detailed Implementation

[0021] Exemplary embodiments will now be described in detail, examples of which are illustrated in the accompanying drawings. When the following description relates to the drawings, unless otherwise indicated, the same numbers in different drawings denote the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with this application. Rather, they are merely examples of apparatuses and methods consistent with some aspects of this application as detailed in the appended claims.

[0022] The terminology used in this application is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. The singular forms “a,” “the,” and “the” used in this application and the appended claims are also intended to include the plural forms unless the context clearly indicates otherwise. It should also be understood that the term “and / or” as used herein refers to and includes any or all possible combinations of one or more of the associated listed items.

[0023] It should be understood that although the terms first, second, third, etc., may be used in this application to describe various information, such information should not be limited to these terms. These terms are only used to distinguish information of the same type from one another. For example, without departing from the scope of this application, first information may also be referred to as second information, and similarly, second information may also be referred to as first information. Depending on the context, the word "if" as used herein may be interpreted as "when," "when," or "in response to determination."

[0024] Figure 1 This is a block diagram illustrating a molten salt energy storage system according to an exemplary embodiment. Figure 1 As shown, the molten salt energy storage system includes a solar absorber 1, a steam generation system 2, a high-temperature molten salt tank 3, a low-temperature molten salt tank 4, a water storage tank 5, and an anti-freeze component 6. The solar absorber 1 includes a low-temperature molten salt inlet 11 and a high-temperature molten salt outlet 12. The steam generation system 2 includes a high-temperature molten salt inlet 21, a low-temperature molten salt outlet 22, a water supply inlet 23, and a steam outlet 24. The steam outlet 24 is connected to a load end 100, allowing the load end 100 to utilize steam from the steam outlet 24 for energy conversion. For example, the load end 100 may include a steam turbine or a generator, which can utilize steam for thermoelectric conversion.

[0025] The high-temperature molten salt tank 3 is connected between the high-temperature molten salt outlet 12 and the high-temperature molten salt inlet 21. For example, the high-temperature molten salt tank 3 can be configured with two inlets and outlets. One inlet and outlet is connected to the high-temperature molten salt outlet 12 through a molten salt conveying pipe, and the other inlet and outlet is connected to the high-temperature molten salt inlet 12 through a molten salt conveying pipe, thus realizing the storage of high-temperature molten salt. The low-temperature molten salt tank 4 is connected between the low-temperature molten salt outlet 22 and the low-temperature molten salt inlet 11. For example, the low-temperature molten salt tank 4 can also be configured with two inlets and outlets. One inlet and outlet is connected to the low-temperature molten salt outlet 22 through a molten salt conveying pipe, and the other inlet and outlet is connected to the low-temperature molten salt inlet 11 through a molten salt conveying pipe, thus realizing the storage of low-temperature molten salt.

[0026] Water storage tank 5 is connected to water inlet 23 of steam generation system 2. Water can be added to steam generation system 2 through water storage tank 5 to ensure steam generation. Anti-freeze component 6 is wrapped around the outside of molten salt conveying pipe between solar generator 1 and high-temperature molten salt tank 3. Anti-freeze component 6 can insulate and heat molten salt conveying pipe, reducing the probability of molten salt freezing.

[0027] The antifreeze component 6 includes a pipe heat tracing element 61, a heat reflective layer 62, and an insulation layer 63. The pipe heat tracing element 61 is spirally wound along the length of the molten salt conveying pipe, which increases the contact area and improves the insulation efficiency of the molten salt conveying pipe. The heat reflective layer 62 reflects the heat from the pipe heat tracing element 61, and the reflected heat can then be applied back to the molten salt conveying pipe, thereby improving the antifreeze performance of the antifreeze component 6. The insulation layer 62 is located on the outermost side to achieve the insulation effect, reducing heat dissipation and heat loss.

[0028] Based on this, the antifreeze component 6 in this application is wrapped around the outside of the molten salt conveying pipe, eliminating the need for the complex internal structure of the molten salt conveying pipe. Subsequent maintenance does not require disassembly of the molten salt conveying pipe, resulting in significant cost and maintenance advantages. Furthermore, the heat reflection effect of the heat-reflecting layer 62 and the insulation effect of the insulation layer 63 enhance the heating and insulation effects of the antifreeze component 6, thereby improving its antifreeze performance. The insulation layer 63 may include an aluminum silicate surface layer, the thickness of which can be greater than or equal to 50 mm and less than or equal to 80 mm. Within this range, the insulation effect of the insulation layer 63 can be well achieved, while avoiding the bulkiness caused by an excessively thick insulation layer 43. The thermal conductivity of the insulation layer 63 can be less than or equal to 0.03 W / (m·K).

[0029] In some embodiments, such as Figure 2 As shown, the pipeline heat tracing component 61 may include a self-regulating electric heat tracing component, the power adjustment range of which can be 30 W / m-60 W / m; the target temperature for heating the inner wall of the molten salt conveying pipeline can be between 60℃ and 80℃. The molten salt energy storage system also includes a controller 7 and a molten salt temperature sensor 8. The molten salt temperature sensor 8 can be installed close to the inlet of the high-temperature molten salt tank 3, that is, it can be installed between the solar absorbers 1 of the high-temperature molten salt tank 3 and relatively close to the inlet of the high-temperature molten salt tank 3, to detect the temperature of the molten salt in the molten salt conveying pipeline. The molten salt temperature sensor 8 can be installed on the outside or inside of the molten salt conveying pipeline, and the temperature of the molten salt before entering the high-temperature molten salt tank 3 is detected by the molten salt temperature sensor 8.

[0030] The controller 7 is electrically connected to the molten salt temperature sensor 8 and the self-regulating electric heat tracing element, respectively. The controller 7 can control the start / stop state switching of the self-regulating electric heat tracing element based on the molten salt temperature detected by the molten salt temperature sensor 8. Based on this, on the one hand, the self-regulating electric heat tracing element's own characteristics can be utilized to start or stop heating the molten salt conveying pipeline; on the other hand, through the start / stop switching of the controller 7, when the molten salt temperature is much higher than its freezing point, the self-regulating electric heat tracing element can be switched to a stopped state, and when the molten salt temperature is close to or lower than its freezing point, it can be switched to a started state. This dual working mechanism helps extend the lifespan of the self-regulating electric heat tracing element and avoids it being in a working state for extended periods.

[0031] This controller may include a PID (Proportional-Integral-Derivative) controller. During system initialization of the molten salt energy storage system, relevant parameters of the PID controller can be set, such as the proportional gain, integral time, and derivative time. For example, the PID controller might have a proportional gain Kp = 2.5, an integral time Ti = 10s, and a derivative time Td = 2s.

[0032] Furthermore, the molten salt energy storage system also includes a steam pressure sensor 9, a steam temperature sensor 10, and a molten salt flow control valve 101, all of which are electrically connected to the controller 7. The steam pressure sensor 9 and the steam temperature sensor 10 are respectively located near the steam outlet 24 to detect the real-time steam pressure and real-time steam temperature output from the steam generation system 2. The molten salt flow control valve 101 is located near the inlet of the high-temperature molten salt tank.

[0033] The controller also adjusts the opening degree of the molten salt flow control valve 101 based on real-time steam temperature, real-time steam pressure, and molten salt temperature to achieve precise matching between molten salt flow and steam demand. Furthermore, by incorporating multiple parameters such as real-time steam temperature, real-time steam pressure, and molten salt temperature, it controls the molten salt flow, improving the stability of steam parameters compared to traditional single-parameter adjustment schemes and meeting the steam quality requirements of the load end 100. Specifically, when the molten salt energy storage system is in its initial state, i.e., before heat generation begins, the initial opening degree of the molten salt flow control valve 101 can be 50%, preventing extreme situations.

[0034] The opening degree of the molten salt flow control valve 101 can be adjusted based on the differences between the real-time steam temperature and the target steam temperature, the differences between the real-time steam pressure and the target steam pressure, and the differences between the molten salt temperature and the safe temperature. The target steam temperature can be 550℃, the target steam pressure can be 14MPa, and the safe temperature can be greater than or equal to 50℃.

[0035] Based on this embodiment, the molten salt energy storage system also includes a molten salt flow shut-off valve 102 electrically connected to the controller 7. The molten salt flow shut-off valve 102 is located between the antifreeze component 6 and the solar absorber 1. The controller 7 is used to control the molten salt flow control valve 101 to switch to the lowest safe opening degree and control the molten salt flow shut-off valve 102 to switch to the shut-off state when the real-time steam pressure is greater than the steam overpressure threshold, so as to quickly cut off the fault and realize the overpressure early warning strategy of the molten salt energy storage system. Compared with the traditional system, it reduces the risk of fault expansion and ensures the safety of system operation.

[0036] For example, the molten salt energy storage system also includes an alarm module 103 electrically connected to the controller 7. The controller 7 can control the alarm module 103 to switch to alarm mode. For instance, when the real-time steam pressure exceeds the steam overpressure threshold, the controller 7 can control the alarm module 103 to switch to alarm mode to promptly alert staff to the status of the molten salt energy storage system. The alarm module 103 can be an audible and visual alarm or other alarm methods.

[0037] For example, the controller 7 also includes a remote communication module 71, which is used to establish a communication connection between the controller and the remote communication terminal 200. This allows the controller to send operating parameters of the molten salt energy storage system to the remote communication terminal 200. For instance, it can send the parameter relationship between real-time steam pressure and steam overpressure threshold to indicate to the user whether the molten salt energy storage system is currently in a safe, dangerous, or critical state. Alternatively, it can send current real-time molten salt flow rate, real-time molten salt temperature, real-time steam temperature, and real-time steam pressure to the remote communication terminal 200.

[0038] In the above embodiments, the controller 7 can also be used to control the molten salt flow control valve 101 to switch to the lowest safe opening degree and control the molten salt flow shut-off valve 102 to switch to the shut-off state when the molten salt temperature is lower than the molten salt freezing warning temperature. This enables the molten salt energy storage system to be configured with multi-level parameter warnings, improving the safety performance of the molten salt energy storage system. Of course, referring to the settings of the alarm module 103 and the remote communication module 71, when the molten salt temperature is lower than the molten salt freezing warning temperature, the controller 7 can also control the alarm module 3 to switch to alarm mode, or send the risk to the remote communication terminal through the remote communication module 71.

[0039] In the above embodiments, such as Figure 3 As shown, the molten salt energy storage system also includes a first pump body 104, a second pump body 105, and a third pump body 106. The first pump body 104 is connected between the high-temperature molten salt tank 3 and the high-temperature molten salt inlet 21, pumping high-temperature molten salt into the steam generation system 2. The second pump body 105 is connected between the low-temperature molten salt tank 4 and the low-temperature molten salt inlet 11, pumping low-temperature molten salt into the solar absorber 1, improving the efficiency of molten salt delivery. The third pump body 106 is connected between the water storage tank 5 and the water supply inlet 23, replenishing water to the steam generation system.

[0040] Based on the technical solution of this application, a solar thermal power plant is also provided. The solar thermal power plant includes a power generation device and the molten salt energy storage system described in any of the foregoing embodiments. The power generation device is connected to the steam outlet 24 of the steam generation system 2, and the power generation device generates electricity based on the high temperature and high pressure steam from the steam generation system 2.

[0041] Other embodiments of this application will readily occur to those skilled in the art upon consideration of the specification and practice of the disclosure herein. This application is intended to cover any variations, uses, or adaptations of this application that follow the general principles of this application and include common knowledge or customary techniques in the art not disclosed herein. The specification and examples are to be considered exemplary only, and the true scope and spirit of this application are indicated by the following claims.

[0042] It should be understood that this application is not limited to the precise structure described above and shown in the accompanying drawings, and various modifications and changes can be made without departing from its scope. The scope of this application is limited only by the appended claims.

Claims

1. A molten salt energy storage system, characterized in that, include: A solar thermal absorber, comprising a low-temperature molten salt inlet and a high-temperature molten salt outlet; A steam generating system, comprising a high-temperature molten salt inlet, a low-temperature molten salt outlet, a feedwater inlet, and a steam outlet, wherein the steam outlet is used to connect to the load end; A high-temperature molten salt tank, wherein the high-temperature molten salt tank is connected between the high-temperature molten salt outlet and the high-temperature molten salt inlet; A cryogenic molten salt tank, wherein the cryogenic molten salt tank is connected between the cryogenic molten salt inlet and the cryogenic molten salt outlet; A water storage tank, which is connected to the water inlet; An antifreeze assembly is wound around the outside of the pipe between the solar absorber and the high-temperature molten salt tank. The antifreeze assembly includes a pipe heat tracing element, a heat reflective layer, and an insulation layer. The pipe heat tracing element is spirally wound around the pipe along its length, and the heat reflective layer is located between the pipe heat tracing element and the insulation layer.

2. The molten salt energy storage system according to claim 1, characterized in that, The pipeline heat tracing component includes a self-regulating electric heat tracing component, and the molten salt energy storage system also includes a controller and a molten salt temperature sensor, with the molten salt temperature sensor located near the inlet of the high-temperature molten salt tank. The controller is electrically connected to the self-regulating electric heat tracing element and the molten salt temperature sensor respectively. The controller is used to control the start / stop state switching of the self-regulating electric heat tracing element according to the molten salt temperature of the molten salt temperature sensor.

3. The molten salt energy storage system according to claim 2, characterized in that, It also includes a steam pressure sensor, a steam temperature sensor, and a molten salt flow control valve, which are electrically connected to the controller respectively. The steam pressure sensor and the steam temperature sensor are respectively located near the steam outlet, and the molten salt flow control valve is located near the inlet of the high-temperature molten salt tank; The controller is used to adjust the opening degree of the molten salt flow control valve according to the real-time steam pressure, real-time steam temperature and molten salt temperature.

4. The molten salt energy storage system according to claim 3, characterized in that, It also includes a molten salt flow shut-off valve electrically connected to the controller, the molten salt flow shut-off valve being disposed between the solar absorber and the antifreeze component; The controller is used to control the molten salt flow control valve to switch to the lowest safe opening degree and control the molten salt flow shut-off valve to the shut-off state when the real-time steam pressure is greater than the steam overpressure threshold.

5. The molten salt energy storage system according to claim 2, characterized in that, It also includes a molten salt flow control valve and a molten salt flow shut-off valve electrically connected to the controller, wherein the molten salt flow shut-off valve is disposed between the solar absorber and the antifreeze component; The controller is used to control the molten salt flow control valve to switch to the lowest safe opening degree and control the molten salt flow cut-off valve to switch to the cut-off state when the molten salt temperature is lower than the molten salt freezing warning temperature.

6. The molten salt energy storage system according to claim 2, characterized in that, It also includes an alarm module electrically connected to the controller, the controller being used to trigger the alarm mode of the alarm module.

7. The molten salt energy storage system according to claim 2, characterized in that, The controller also includes a remote communication module, which is used to establish a communication connection with a remote communication terminal to send the operating parameters of the molten salt energy storage system to the remote communication terminal.

8. The molten salt energy storage system according to claim 1, characterized in that, Also includes: A first pump body is connected between the high-temperature molten salt tank and the high-temperature molten salt inlet; A second pump body is connected between the cryogenic molten salt tank and the cryogenic molten salt inlet; The third pump body is connected between the water storage tank and the water inlet.

9. The molten salt energy storage system according to claim 1, characterized in that, The insulation layer includes an aluminum silicate cotton layer, the thickness of which is greater than or equal to 50 mm and less than or equal to 80 mm.

10. A solar thermal power plant, characterized in that, include: Power generation equipment; The molten salt energy storage system as described in any one of claims 1-9, wherein the steam outlet of the molten salt energy storage system is connected to the power generation device.

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