Coupling heat exchange system and coupling heat exchange method

Abstract

The invention discloses a coupling heat exchange system and a coupling heat exchange method.The coupling heat exchange system comprises a high-temperature steam fused salt heat exchanger, a salt-salt heat exchanger, an anti-condensation heater and a binary fused salt storage tank, and the high-temperature steam fused salt heat exchanger, the binary fused salt storage tank and the salt-salt heat exchanger are sequentially connected; the anti-condensation heater is connected with the binary fused salt storage tank so as to heat the binary fused salt storage tank to prevent the binary fused salt in the binary fused salt storage tank from being solidified, the salt-salt heat exchanger is further connected to the high-temperature steam fused salt heat exchanger, and the high-temperature steam fused salt heat exchanger is used for being connected with a unit through a high-temperature steam pipeline. The high-temperature steam molten salt heat exchanger further outputs low-temperature steam through a low-temperature steam pipeline, and the salt-salt heat exchanger is further connected with a low-temperature ternary salt pipeline to input low-temperature ternary salt and connected with a high-temperature ternary salt pipeline to output high-temperature ternary salt. According to the method, high-temperature decomposition of the ternary molten salt can be avoided, and high steam heat storage power can be guaranteed.

Description

Technical Field

[0001] This application relates to the field of energy technology, and in particular to a coupled heat exchange system and a coupled heat exchange method. Background Technology

[0002] The flexibility retrofitting of coal-fired power plants is a core measure to address the high proportion of renewable energy grid integration and enhance the power system's regulation capabilities. Molten salt thermal energy storage technology, as a key support, is driving the transformation of thermal power from a "baseload power source" to a "flexibly adjustable power source." Molten salt thermal energy storage achieves the spatial and temporal transfer of thermal energy by embedding high-temperature molten salt energy storage devices in the "boiler-turbine" thermal system of coal-fired power units. When the unit is operating at low load, the superheated steam generated by the boiler heats the molten salt through a steam-molten salt heat exchanger, storing the thermal energy in a high-temperature molten salt tank. When peak shaving is required, the high-temperature molten salt releases heat through a molten salt-steam heat exchanger, and the generated steam is supplied to industrial steam or returned to the unit to drive the turbine for power generation. This process breaks the rigid constraint of the traditional "boiler-turbine coupling" in thermal power units, allowing the boiler to maintain stable operation while the turbine flexibly adjusts its output, achieving thermoelectric decoupling.

[0003] Traditionally used nitrate molten salts include Solar salts (binary molten salts) and Hitec salts (ternary molten salts). Because ternary molten salts have better matching properties with the steam parameters of coal-fired power units, all existing and under-construction coal-fired power unit coupling molten salt flexibility enhancement projects currently use ternary molten salts. Ternary molten salts are prone to decomposition at high temperatures (e.g., above 450℃), such as sodium nitrite gradually transforming into sodium nitrate, accompanied by the production of toxic nitrogen oxides. After decomposition, the component ratio of ternary molten salts evolves towards that of binary molten salts, and performance parameters such as melting point gradually change, leading to alterations in the performance of the molten salt system and its inability to operate normally. High-temperature steam, such as main steam and reheat steam, from supercritical and ultra-supercritical units is often used as the heat source for molten salt heat storage. The temperature of this high-temperature steam heat source is typically between 566℃ and 620℃. Before exchanging heat with the ternary molten salt, the high-temperature steam is cooled to 480℃ to 500℃ by water spraying, but there is still a risk of wall temperature exceeding the limit, leading to the decomposition of the ternary molten salt. To address the aforementioned issues, traditional technologies employ water spraying for cooling. Although high-temperature steam can be cooled to a lower temperature by water spraying, this process is irreversible and will lead to a decrease in steam enthalpy and enthalpy, directly resulting in a reduction in thermal storage power and affecting the normal operation of the energy storage system. In order to avoid insufficient total thermal storage, the amount of ternary molten salt is increased to compensate, but this method will increase the investment in molten salt. Summary of the Invention

[0004] Therefore, it is necessary to provide a coupled heat exchange system that can both avoid the high-temperature decomposition of ternary molten salt and ensure high steam heat storage power.

[0005] One embodiment of this application provides a coupled heat exchange system.

[0006] A coupled heat exchange system includes a high-temperature steam molten salt heat exchanger, a salt-salt heat exchanger, an anti-condensation heater, and a binary molten salt storage tank. The high-temperature steam molten salt heat exchanger, the binary molten salt storage tank, and the salt-salt heat exchanger are connected sequentially. The anti-condensation heater is connected to the binary molten salt storage tank to heat the tank and prevent the binary molten salt inside from solidifying. The salt-salt heat exchanger is also connected to the high-temperature steam molten salt heat exchanger. The high-temperature steam molten salt heat exchanger is used to connect to a generator unit via a high-temperature steam pipeline. It also outputs low-temperature steam via a low-temperature steam pipeline. The salt-salt heat exchanger is further connected to a low-temperature ternary salt pipeline for inputting low-temperature ternary salt and to a high-temperature ternary salt pipeline for outputting high-temperature ternary salt.

[0007] In some embodiments, the high-temperature side inlet of the high-temperature steam molten salt heat exchanger is connected to the unit via a high-temperature steam pipeline, the high-temperature side outlet of the high-temperature steam molten salt heat exchanger outputs low-temperature steam via a low-temperature steam pipeline, the low-temperature side outlet of the high-temperature steam molten salt heat exchanger is connected to the inlet of the binary molten salt storage tank, the outlet of the binary molten salt storage tank is connected to the high-temperature side inlet of the salt-salt heat exchanger, and the high-temperature side outlet of the salt-salt heat exchanger is connected to the liquid phase inlet of the high-temperature steam molten salt heat exchanger.

[0008] In some embodiments, the coupled heat exchange system further includes a molten salt transfer pump connected between the binary molten salt storage tank and the salt-salt heat exchanger. The molten salt transfer pump is used to transfer the binary molten salt in the binary molten salt storage tank to the salt-salt heat exchanger. The molten salt transfer pump can adjust the temperature of the transferred binary molten salt by controlling the flow rate.

[0009] In some embodiments, the molten salt transfer pump is mounted on the binary molten salt tank and communicates with the outlet of the binary molten salt tank. The molten salt transfer pump has a suction pipe that extends to the bottom of the binary molten salt tank.

[0010] In some embodiments, the coupled heat exchange system further includes a low-temperature steam molten salt heat exchanger connected to the high-temperature steam molten salt heat exchanger via the low-temperature steam pipeline to utilize the low-temperature steam output from the high-temperature steam molten salt heat exchanger.

[0011] In some embodiments, the low-temperature side inlet of the low-temperature steam molten salt heat exchanger is connected to a low-temperature ternary salt pipeline to input low-temperature ternary salt; the low-temperature side outlet of the low-temperature steam molten salt heat exchanger is connected to a high-temperature ternary salt pipeline to output high-temperature ternary salt.

[0012] In some embodiments, the anti-condensation heater is connected to the bottom of the binary molten salt tank, and the anti-condensation heater has an electric heating wire that extends into the binary molten salt tank.

[0013] One embodiment of this application also provides a coupled heat exchange method.

[0014] A coupled heat transfer method includes the following steps:

[0015] When the temperature of the low-temperature steam exceeds 290℃, the binary molten salt is controlled to absorb the heat of the high-temperature steam in the high-temperature steam molten salt heat exchanger.

[0016] When the binary molten salt is heated to over 450°C, it enters the binary molten salt storage tank and is then transported to the salt-salt heat exchanger.

[0017] Furthermore, the high-temperature binary molten salt in the salt-salt heat exchanger heats the low-temperature ternary molten salt input into the salt-salt heat exchanger into high-temperature ternary molten salt for heat storage and output. After cooling down, the binary molten salt returns to the high-temperature steam-molten salt heat exchanger to continue absorbing heat, and so on.

[0018] In some embodiments, the coupled heat exchange method further includes the following steps:

[0019] When the temperature of the low-temperature steam is below 290°C, the binary molten salt is controlled to absorb the heat of the high-temperature steam in the high-temperature steam molten salt heat exchanger. After the high-temperature steam releases heat for the first time in the high-temperature steam molten salt heat exchanger, the temperature drops to below 400°C and then enters the low-temperature steam molten salt heat exchanger.

[0020] Furthermore, steam with a temperature higher than 400°C is cooled to below 250°C by low-temperature ternary molten salt in the low-temperature steam molten salt heat exchanger, and the ternary molten salt is heated to become high-temperature ternary molten salt heat storage, and so on.

[0021] In some embodiments, the temperature rise of the binary molten salt is controlled by flow rate.

[0022] In some embodiments, a portion of the binary molten salt is pre-stored in the binary molten salt storage tank.

[0023] This application uses binary molten salt as a heat exchange medium to replace high-temperature steam spray cooling, eliminating heat loss and ensuring high heat storage capacity while avoiding the decomposition of ternary molten salt caused by high temperatures. Specifically, the above-mentioned coupled heat exchange system uses binary molten salt as a heat exchange medium to replace the traditional water spray cooling. The binary molten salt directly exchanges heat with high-temperature steam, and the temperature of the binary molten salt can be controlled by the flow rate of the molten salt transfer pump. The temperature of the heated binary molten salt is controlled not to exceed 450℃, and then it exchanges heat with ternary molten salt to heat the ternary molten salt to a set temperature for heat storage. This application can be flexibly adjusted according to actual needs, such as... Figure 1 As shown, when the required low-temperature steam temperature is high, such as exceeding 290℃, a coupled heat exchange mode of high-temperature steam-binary molten salt-ternary molten salt can be adopted to achieve heat storage of the high-temperature steam by the ternary molten salt; Figure 2 As shown, when the required low-temperature steam temperature is low, such as when the low-temperature steam temperature is below 290℃, binary molten salt can be used to reduce the steam temperature to about 400℃. The binary molten salt heats the ternary molten salt, which stores heat through the ternary molten salt. At the same time, the cooled low-temperature steam continues to enter the low-temperature steam molten salt heat exchanger to heat the ternary molten salt for heat storage.

[0024] In summary, compared with traditional technologies, this application has the following beneficial effects:

[0025] (1) The decomposition temperature of binary molten salt is high. The temperature of binary molten salt is controlled by molten salt transfer pump so that the temperature of binary molten salt does not exceed the limit, such as not exceeding 450℃, to avoid the high-temperature decomposition of ternary molten salt in salt-salt heat exchanger.

[0026] (2) By using binary molten salt as an intermediary to exchange heat with high-temperature steam, and then exchanging heat with ternary molten salt for heat storage, the heat storage power of molten salt can be improved compared with the traditional method of directly spraying water to reduce the temperature and then exchanging heat with ternary molten salt.

[0027] (3) A certain amount of binary molten salt is stored in the binary molten salt storage tank to play a buffering role and avoid the high temperature runaway of the binary molten salt due to sudden changes in working conditions, which would lead to the high temperature decomposition of the ternary molten salt.

[0028] (4) An anti-condensation heater is installed at the bottom of the binary molten salt storage tank to prevent the binary molten salt from solidifying under special working conditions such as steam stoppage and no flow of ternary molten salt.

[0029] (5) When the low temperature requirement of low-temperature steam is low, such as below 290℃, the binary molten salt cannot meet the cooling requirements of high-temperature steam. Therefore, after the high-temperature steam is cooled to a certain temperature, such as 400℃, it continues to enter the low-temperature steam molten salt heat exchanger to exchange heat with the ternary molten salt and continue to cool down, ensuring that the heat exchange power is not lost and the ternary molten salt does not decompose. Attached Figure Description

[0030] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0031] To gain a more complete understanding of this application and its beneficial effects, the following description will be provided in conjunction with the accompanying drawings. In the following description, the same reference numerals denote the same parts.

[0032] Figure 1 This is a schematic diagram of a coupled heat exchange system according to an embodiment of this application;

[0033] Figure 2 This is a schematic diagram of a coupled heat exchange system according to an embodiment of this application;

[0034] Figure 3 This is a schematic diagram of the coupling heat exchange method according to an embodiment of this application.

[0035] Explanation of reference numerals in the attached figures

[0036] 10. Coupled heat exchange system; 100. High-temperature steam molten salt heat exchanger; 200. Salt-salt heat exchanger; 300. Anti-condensation heater; 400. Binary molten salt storage tank; 500. Molten salt transfer pump; 600. Low-temperature steam molten salt heat exchanger; 701. High-temperature steam pipeline; 702. Low-temperature steam pipeline; 703. Low-temperature ternary salt pipeline; 704. High-temperature ternary salt pipeline. Detailed Implementation

[0037] To make the above-mentioned objectives, features, and advantages of this application more apparent and understandable, the specific embodiments of this application are described in detail below with reference to the accompanying drawings. Many specific details are set forth in the following description to provide a thorough understanding of this application. However, this application can be implemented in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of this application. Therefore, this application is not limited to the specific embodiments disclosed below.

[0038] In the description of this application, 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", "circumferential", etc., indicating the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application.

[0039] In this application, unless otherwise expressly specified and limited, the terms "installation," "connection," "joining," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise expressly limited. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0040] In this application, unless otherwise expressly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "on top of," and "over" the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0041] In the description of this application, "several" means one or more, "multiple" means two or more, "greater than," "less than," and "exceeding" are understood to exclude the stated number, while "above," "below," and "within" are understood to include the stated number. The use of "first" and "second" in the description is merely for distinguishing technical features and should not be construed as indicating or implying relative importance, or implicitly indicating the number of indicated technical features, or implicitly indicating the order of the indicated technical features.

[0042] In this document, "optionally," "optionally," and "optional" mean that something is optional, that is, it is selected from either "with" or "without." If multiple "options" appear in a technical solution, unless otherwise specified and there are no contradictions or mutual constraints, each "option" is independent. In this application, descriptions such as "optionally contains" and "optionally includes" indicate "contains or does not contain."

[0043] In this document, unless otherwise stated, the reaction steps may be performed in the order described herein or not. For example, other steps may be included between reaction steps, and the order of reaction steps may be appropriately interchanged. This is something that those skilled in the art can determine based on conventional knowledge and experience. Preferably, the reaction methods described herein are performed sequentially.

[0044] In this application, when numerical intervals (i.e., numerical ranges) are mentioned, unless otherwise specified, the distribution of selectable numerical values ​​within the numerical interval is considered continuous, and includes the two endpoints of the numerical interval (i.e., the minimum and maximum values), as well as every numerical value between these two endpoints. Unless otherwise specified, when a numerical interval refers only to integers within that numerical interval, it includes the two endpoint integers of the numerical range, as well as every integer between the two endpoints, which is equivalent to directly listing every integer. When multiple numerical ranges are provided to describe features or characteristics, these numerical ranges can be merged. In other words, unless otherwise specified, the numerical ranges disclosed in this application should be understood to include any and all subranges included therein. The "numerical value" in the numerical interval can be any quantitative value, such as a number, percentage, ratio, etc. The term "numerical interval" can be broadly included to include percentage intervals, ratio intervals, proportion intervals, etc.

[0045] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0046] This application provides a coupled heat exchange system to solve at least one of the following technical problems in the prior art: (1) Traditional technology uses water spray to cool high-temperature steam by exchanging heat with ternary molten salt, which leads to a decrease in steam enthalpy and t, directly resulting in a decrease in heat storage power and affecting the normal operation of the energy storage system; (2) Traditional technology compensates for the total heat storage by increasing the amount of ternary molten salt, which increases the investment in molten salt and raises the cost. The coupled heat exchange system will be described below with reference to the accompanying drawings.

[0047] The coupled heat exchange system 10 provided in this application embodiment is exemplary; please refer to [link to example]. Figure 1 As shown, Figure 1 This is a schematic diagram of the coupled heat exchange system 10 provided in an embodiment of this application. The coupled heat exchange system 10 of this application can be used for heat storage of high-temperature steam generated through main steam and hot reheat steam in supercritical and ultra-supercritical units.

[0048] To more clearly illustrate the structure of the coupled heat exchange system 10, the coupled heat exchange system 10 will be described below in conjunction with the accompanying drawings.

[0049] For example, please refer to Figure 1 As shown, a coupled heat exchange system 10 includes a high-temperature steam-molten salt heat exchanger 100, a salt-salt heat exchanger 200, an anti-condensation heater 300, and a binary molten salt storage tank 400. The high-temperature steam-molten salt heat exchanger 100, the binary molten salt storage tank 400, and the salt-salt heat exchanger 200 are connected sequentially. The anti-condensation heater 300 is connected to the binary molten salt storage tank 400 to heat the tank and prevent the binary molten salt inside from solidifying. The salt-salt heat exchanger 200 is also connected to the high-temperature steam-molten salt heat exchanger 100. The high-temperature steam-molten salt heat exchanger 100 is used to connect to a generator unit via a high-temperature steam pipeline 701. The high-temperature steam-molten salt heat exchanger 100 also outputs low-temperature steam via a low-temperature steam pipeline 702. The salt-salt heat exchanger 200 is also connected to a low-temperature ternary salt pipeline 703 for inputting low-temperature ternary salt and a high-temperature ternary salt pipeline 704 for outputting high-temperature ternary salt.

[0050] This application uses binary molten salt as a heat exchange medium to replace high-temperature steam spray cooling, without heat loss, ensuring high heat storage power while avoiding the decomposition of ternary molten salt caused by high temperature.

[0051] In some embodiments, the high-temperature side inlet of the high-temperature steam-molten salt heat exchanger 100 is connected to the unit via a high-temperature steam pipeline 701. The high-temperature side outlet of the high-temperature steam-molten salt heat exchanger 100 outputs low-temperature steam via a low-temperature steam pipeline 702. The low-temperature side outlet of the high-temperature steam-molten salt heat exchanger 100 is connected to the inlet of the binary molten salt storage tank 400. The outlet of the binary molten salt storage tank 400 is connected to the high-temperature side inlet of the salt-salt heat exchanger 200. The high-temperature side outlet of the salt-salt heat exchanger 200 is then connected to the liquid phase inlet of the high-temperature steam-molten salt heat exchanger 100.

[0052] In some embodiments, the coupled heat exchange system 10 further includes a molten salt transfer pump 500. The molten salt transfer pump 500 is connected between the binary molten salt storage tank 400 and the salt-salt heat exchanger 200. The molten salt transfer pump 500 is used to transfer the binary molten salt from the binary molten salt storage tank 400 to the salt-salt heat exchanger 200. The molten salt transfer pump 500 can regulate the temperature of the transferred binary molten salt by controlling the flow rate.

[0053] In some embodiments, a molten salt transfer pump 500 is mounted on a binary molten salt storage tank 400 and communicates with the outlet of the binary molten salt storage tank 400. The molten salt transfer pump 500 has a suction pipe that extends to the bottom of the binary molten salt storage tank 400.

[0054] In some embodiments, the coupled heat exchange system 10 further includes a cryogenic steam molten salt heat exchanger 600. The cryogenic steam molten salt heat exchanger 600 is connected to the high-temperature steam molten salt heat exchanger 100 via a cryogenic steam line 702 to utilize the cryogenic steam output from the high-temperature steam molten salt heat exchanger 100.

[0055] In some embodiments, the low-temperature side inlet of the low-temperature steam molten salt heat exchanger 600 is connected to a low-temperature ternary salt pipeline 703 to input low-temperature ternary salt. The low-temperature side outlet of the low-temperature steam molten salt heat exchanger 600 is connected to a high-temperature ternary salt pipeline 704 to output high-temperature ternary salt.

[0056] In some embodiments, an anti-condensation heater 300 is connected to the bottom of a binary molten salt storage tank 400. The anti-condensation heater 300 has an electric heating wire that extends into the binary molten salt storage tank 400.

[0057] The aforementioned coupled heat exchange system 10 uses binary molten salt as the heat exchange medium, replacing the traditional water spray cooling method. The binary molten salt directly exchanges heat with high-temperature steam. The temperature of the binary molten salt can be controlled by the flow rate of the molten salt transfer pump 500, ensuring that the temperature of the heated binary molten salt does not exceed 450℃. It then exchanges heat with ternary molten salt, heating the ternary molten salt to a set temperature, and storing the heat through the ternary molten salt. This application can be flexibly adjusted according to actual needs, such as... Figure 1 As shown, when the required low-temperature steam temperature is high, such as exceeding 290℃, a coupled heat exchange mode of high-temperature steam-binary molten salt-ternary molten salt can be adopted to achieve heat storage of the high-temperature steam by the ternary molten salt; Figure 2 As shown, when the required low-temperature steam temperature is low, such as when the low-temperature steam temperature is below 290℃, the steam temperature can be reduced to about 400℃ using binary molten salt. The binary molten salt heats the ternary molten salt, which stores heat through the ternary molten salt. At the same time, the cooled low-temperature steam continues to enter the low-temperature steam molten salt heat exchanger 600 to heat the ternary molten salt for heat storage.

[0058] One embodiment of this application also provides a coupled heat exchange method.

[0059] A coupled heat transfer method, such as Figure 1 as well as Figure 3 As shown, Figure 3 This is a schematic diagram of the coupled heat transfer method according to an embodiment of this application, including the following steps:

[0060] S10. When the temperature of the low-temperature steam exceeds 290℃ (e.g., 320℃), control the binary molten salt to absorb the heat of the high-temperature steam in the high-temperature steam molten salt heat exchanger 100.

[0061] S20. When the binary molten salt is heated to more than 450°C, it enters the binary molten salt storage tank 400 and is transported to the salt-salt heat exchanger 200.

[0062] S30, the high-temperature binary molten salt in the salt-salt heat exchanger 200 heats the low-temperature ternary molten salt (e.g., 190°C) that is input into the salt-salt heat exchanger 200 into a high-temperature ternary molten salt (e.g., 390°C) for heat storage and output. After cooling down (e.g., 290°C), the binary molten salt returns to the high-temperature steam molten salt heat exchanger 100 to continue absorbing heat, and so on.

[0063] In some of these embodiments, such as Figure 2 As shown, the coupled heat transfer method also includes the following steps:

[0064] When the temperature of the low-temperature steam is below 290℃ (e.g., 250℃), the binary molten salt is controlled to absorb the heat of the high-temperature steam in the high-temperature steam molten salt heat exchanger 100. After the high-temperature steam releases heat for the first time in the high-temperature steam molten salt heat exchanger 100, the temperature drops to below 400℃ and then enters the low-temperature steam molten salt heat exchanger 600.

[0065] Furthermore, steam with a temperature higher than 400°C is cooled to below 250°C by low-temperature ternary molten salt (e.g., 190°C) in the low-temperature steam molten salt heat exchanger 600. The ternary molten salt is then heated to become high-temperature ternary molten salt (e.g., 390°C) for heat storage, and this cycle continues.

[0066] In some embodiments, the temperature rise of the binary molten salt is controlled by flow rate.

[0067] In some embodiments, a portion of the binary molten salt is pre-stored in the binary molten salt storage tank 400.

[0068] In summary, compared with traditional technologies, this application has the following beneficial effects:

[0069] (1) The binary molten salt decomposition temperature is high. The binary molten salt temperature is controlled by the molten salt transfer pump 500 to ensure that the binary molten salt temperature does not exceed the limit, such as not exceeding 450℃, so as to avoid the high-temperature decomposition of the ternary molten salt in the salt-salt heat exchanger 200.

[0070] (2) By using binary molten salt as an intermediary to exchange heat with high-temperature steam, and then exchanging heat with ternary molten salt for heat storage, the heat storage power of molten salt can be improved compared with the traditional method of directly spraying water to reduce the temperature and then exchanging heat with ternary molten salt.

[0071] (3) A certain amount of binary molten salt is stored in the binary molten salt storage tank 400 to play a buffering role and avoid the high temperature runaway of the binary molten salt due to sudden changes in working conditions, which would lead to the high temperature decomposition of the ternary molten salt.

[0072] (4) An anti-condensation heater 300 is installed at the bottom of the binary molten salt storage tank 400 to prevent the binary molten salt from solidifying under special working conditions such as steam stoppage and no flow of ternary molten salt.

[0073] (5) When the low temperature requirement of low temperature steam is low, such as below 290℃, the binary molten salt cannot meet the cooling requirements of high temperature steam. Therefore, after the high temperature steam is cooled to a certain temperature, such as 400℃, it continues to enter the low temperature steam molten salt heat exchanger 600 to exchange heat with the ternary molten salt and continue to cool down, ensuring that the heat exchange power is not lost and the ternary molten salt does not decompose.

[0074] In the above embodiments, the descriptions of each embodiment have different focuses. For parts not described in detail in a certain embodiment, please refer to the relevant descriptions in other embodiments.

[0075] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0076] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of this patent application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this patent application should be determined by the appended claims.

Claims

1. A coupled heat exchange system, characterized in that, The system includes a high-temperature steam molten salt heat exchanger, a salt-salt heat exchanger, an anti-condensation heater, and a binary molten salt storage tank. The high-temperature steam molten salt heat exchanger, the binary molten salt storage tank, and the salt-salt heat exchanger are connected sequentially. The anti-condensation heater is connected to the binary molten salt storage tank to heat the tank and prevent the binary molten salt inside from solidifying. The salt-salt heat exchanger is also connected to the high-temperature steam molten salt heat exchanger. The high-temperature steam molten salt heat exchanger is used to connect to the generator unit via a high-temperature steam pipeline. The high-temperature steam molten salt heat exchanger also outputs low-temperature steam via a low-temperature steam pipeline. The salt-salt heat exchanger is also connected to a low-temperature ternary salt pipeline for inputting low-temperature ternary salt and to a high-temperature ternary salt pipeline for outputting high-temperature ternary salt.

2. The coupled heat exchange system according to claim 1, characterized in that, The high-temperature side inlet of the high-temperature steam molten salt heat exchanger is connected to the unit through a high-temperature steam pipeline. The high-temperature side outlet of the high-temperature steam molten salt heat exchanger outputs low-temperature steam through a low-temperature steam pipeline. The low-temperature side outlet of the high-temperature steam molten salt heat exchanger is connected to the inlet of the binary molten salt storage tank. The outlet of the binary molten salt storage tank is connected to the high-temperature side inlet of the salt-salt heat exchanger. The high-temperature side outlet of the salt-salt heat exchanger is then connected to the liquid phase inlet of the high-temperature steam molten salt heat exchanger.

3. The coupled heat exchange system according to claim 1, characterized in that, The coupled heat exchange system also includes a molten salt transfer pump, which is connected between the binary molten salt storage tank and the salt-salt heat exchanger. The molten salt transfer pump is used to transfer the binary molten salt in the binary molten salt storage tank to the salt-salt heat exchanger. The molten salt transfer pump can adjust the temperature of the transferred binary molten salt by controlling the flow rate.

4. The coupled heat exchange system according to claim 3, characterized in that, The molten salt transfer pump is installed on the binary molten salt storage tank and is connected to the outlet of the binary molten salt storage tank. The molten salt transfer pump has a suction pipe that extends to the bottom of the binary molten salt storage tank.

5. The coupled heat exchange system according to any one of claims 1 to 4, characterized in that, The coupled heat exchange system also includes a low-temperature steam molten salt heat exchanger, which is connected to the high-temperature steam molten salt heat exchanger through the low-temperature steam pipeline to utilize the low-temperature steam output from the high-temperature steam molten salt heat exchanger.

6. The coupled heat exchange system according to claim 5, characterized in that, The low-temperature side inlet of the low-temperature steam molten salt heat exchanger is connected to a low-temperature ternary salt pipeline for inputting low-temperature ternary salt; the low-temperature side outlet of the low-temperature steam molten salt heat exchanger is connected to a high-temperature ternary salt pipeline for outputting high-temperature ternary salt.

7. The coupled heat exchange system according to any one of claims 1 to 4, 6, characterized in that, The anti-condensation heater is connected to the bottom of the binary molten salt storage tank. The anti-condensation heater has an electric heating wire that extends into the binary molten salt storage tank.

8. A coupled heat transfer method, characterized in that, Includes the following steps: When the temperature of the low-temperature steam exceeds 290℃, the binary molten salt is controlled to absorb the heat of the high-temperature steam in the high-temperature steam molten salt heat exchanger. When the binary molten salt is heated to over 450°C, it enters the binary molten salt storage tank and is then transported to the salt-salt heat exchanger. Furthermore, the high-temperature binary molten salt in the salt-salt heat exchanger heats the low-temperature ternary molten salt input into the salt-salt heat exchanger into high-temperature ternary molten salt for heat storage and output. After cooling down, the binary molten salt returns to the high-temperature steam-molten salt heat exchanger to continue absorbing heat, and so on.

9. The coupled heat transfer method according to claim 8, characterized in that, It also includes the following steps: When the temperature of the low-temperature steam is below 290°C, the binary molten salt is controlled to absorb the heat of the high-temperature steam in the high-temperature steam molten salt heat exchanger. After the high-temperature steam releases heat for the first time in the high-temperature steam molten salt heat exchanger, the temperature drops to below 400°C and then enters the low-temperature steam molten salt heat exchanger. Furthermore, steam with a temperature higher than 400°C is cooled to below 250°C by low-temperature ternary molten salt in the low-temperature steam molten salt heat exchanger, and the ternary molten salt is heated to become high-temperature ternary molten salt heat storage, and so on.

10. The coupled heat transfer method according to claim 8 or 9, characterized in that, The coupled heat exchange method also satisfies at least one of the following conditions: (1) The temperature rise of the binary molten salt is controlled by the flow rate; (2) A portion of binary molten salt is pre-stored in the binary molten salt storage tank.

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