Molten salt steam generating system and control method of molten salt steam generating system

Abstract

The invention discloses a fused salt steam generation system and a control method of the fused salt steam generation system. According to the fused salt steam generation system, one end of a first high-temperature fused salt pipeline is connected with a high-temperature fused salt tank, the other end of the first high-temperature fused salt pipeline is connected with one end of a first fused salt mother pipeline, the other end of the first fused salt mother pipeline is connected with a superheater, and one end of a second high-temperature fused salt pipeline is connected with the high-temperature fused salt tank, and the other end of the second high-temperature fused salt pipeline is connected with a second fused salt mother pipeline. The other end of the second fused salt main pipeline is connected to the fused salt conveying pipeline between the superheater and the evaporator, one end of a third high-temperature fused salt pipeline is connected with the high-temperature fused salt tank, the other end of the third high-temperature fused salt pipeline is connected with one end of a third fused salt main pipeline, and the other end of the third fused salt main pipeline is connected to the fused salt conveying pipeline between the evaporator and the preheater; the first high-temperature fused salt pipeline, the second high-temperature fused salt pipeline and the third high-temperature fused salt pipeline are each provided with an electric adjusting valve used for adjusting the flow of fused salt. According to the invention, accurate control of the temperature of each heat exchange device can be realized.

Description

Technical Field

[0001] This application relates to the field of molten salt energy storage technology, and in particular to a molten salt steam generation system and a control method for the molten salt steam generation system. Background Technology

[0002] In the molten salt heat release stage, feedwater and high-temperature molten salt in the molten salt steam generation system exchange heat through heat exchange equipment to produce high-quality steam to meet the user's steam demand. Currently, the high-temperature molten salt in the molten salt steam generation system flows sequentially to the superheater, evaporator, and preheater. During the operation of the molten salt steam generation system, scaling and blockage inside the upstream heat exchange equipment can cause changes in the molten salt inlet temperature and flow rate of the downstream heat exchange equipment. Simultaneously, the steam-water side outlet parameters of the heat exchange equipment are affected by changes in the molten salt side inlet parameters, the decrease in heat transfer efficiency caused by scaling and blockage in the heat exchange equipment, and the strong parameter coupling during frequent switching of steam usage conditions by the user. Therefore, it is difficult to achieve precise control of the steam-water side outlet temperature of each heat exchange equipment through the adjustment of a single branch valve. Thus, how to achieve precise control of the temperature and flow rate of each heat exchange equipment is a problem that urgently needs to be solved. Summary of the Invention

[0003] In view of the above problems, this application provides a molten salt steam generation system and a control method for the molten salt steam generation system.

[0004] To solve the above-mentioned technical problems, this application proposes the following solution:

[0005] In a first aspect, this application provides a molten salt steam generating system, comprising: a steam generating system, including at least a superheater, an evaporator, and a preheater; and a molten salt system, including at least: a high-temperature molten salt tank, a low-temperature molten salt tank, a molten salt heat storage device, a first high-temperature molten salt pipeline, a second high-temperature molten salt pipeline, a third high-temperature molten salt pipeline, a first molten salt header pipeline, a second molten salt header pipeline, and a third molten salt header pipeline; one end of the first high-temperature molten salt pipeline is connected to the high-temperature molten salt tank, and the other end is connected to one end of the first molten salt header pipeline, and the other end of the first molten salt header pipeline... The superheater is connected to the first high-temperature molten salt pipeline. One end of the second high-temperature molten salt pipeline is connected to the high-temperature molten salt tank, and the other end is connected to one end of the second molten salt main pipeline. The other end of the second molten salt main pipeline is connected to the molten salt conveying pipeline between the superheater and the evaporator. One end of the third high-temperature molten salt pipeline is connected to the high-temperature molten salt tank, and the other end is connected to one end of the third molten salt main pipeline. The other end of the third molten salt main pipeline is connected to the molten salt conveying pipeline between the evaporator and the preheater. Electric regulating valves for adjusting the molten salt flow rate are installed on the first, second, and third high-temperature molten salt pipelines.

[0006] Secondly, this application provides a control method for a molten salt steam generation system. The method is applied to the molten salt steam generation system as described in the first aspect, wherein the superheater, evaporator, and preheater are heat exchange devices, and the superheater, evaporator, and preheater sequentially constitute an upper and lower stage heat exchange relationship. The method includes obtaining the actual outlet temperature and target outlet temperature of the steam-water side of the first heat exchange device; when the absolute value of the temperature difference between the actual outlet temperature and the target outlet temperature of the steam-water side of the first heat exchange device is greater than a threshold, determining the target inlet temperature of the molten salt side based on the target outlet temperature of the steam-water side of the first heat exchange device; obtaining the outlet temperature and outlet flow rate of the molten salt side of the upper stage heat exchange device of the first heat exchange device according to the heat exchange relationship; when the outlet temperature is lower than the target inlet temperature, determining the molten salt flow rate from the high-temperature molten salt tank to the first heat exchange device based on the outlet temperature, outlet flow rate, and target inlet temperature; and adjusting the opening degree of the high-temperature electric regulating valve corresponding to the first heat exchange device based on the molten salt flow rate, so that the actual inlet temperature of the molten salt side of the first heat exchange device is the target inlet temperature.

[0007] By employing the above-described technical solution, the technical solution provided in this application has at least the following advantages:

[0008] This application achieves precise control of molten salt flow rate and temperature by adding independent high-temperature molten salt pipelines and a main molten salt pipeline between the high-temperature molten salt tank and heat exchange equipment such as superheaters, evaporators, and preheaters, and equipping each high-temperature molten salt pipeline with a high-temperature electric regulating valve. Specifically, the independent pipeline design directly delivers high-temperature molten salt to different heat exchange equipment, and the dynamic opening control of each regulating valve flexibly matches the heat load requirements of each heat exchange equipment. For example, when the molten salt temperature at the evaporator inlet is detected to be lower than the set value, the regulating valve of the second high-temperature molten salt pipeline can be opened separately to supplement the evaporator with high-temperature molten salt, quickly raising the molten salt temperature and avoiding fluctuations in steam and water side parameters. The molten salt steam generation system of this application not only ensures independent and precise control of the steam and water side outlet temperatures of each heat exchange equipment, but also reduces system inertia by reducing interstage thermal coupling, significantly improving the overall thermal response speed and operational stability, while optimizing molten salt circulation energy consumption.

[0009] The above description is only an overview of the technical solution of this application. In order to better understand the technical means of this application and to implement it in accordance with the contents of the specification, and to make the above and other objects, features and advantages of this application more obvious and understandable, the following are specific embodiments of this application. Attached Figure Description

[0010] Various other advantages and benefits will become apparent to those skilled in the art upon reading the following detailed description of preferred embodiments. The accompanying drawings are for illustrative purposes only and are not intended to limit the scope of this application. Furthermore, the same reference numerals denote the same parts throughout the drawings. In the drawings:

[0011] Figure 1 This invention provides a schematic diagram of the structure of a conventional molten salt steam generation system according to an embodiment of the present application.

[0012] Figure 2 This illustration shows a structural schematic diagram of a molten salt steam generation system including a high-temperature molten salt pipeline, provided in an embodiment of this application.

[0013] Figure 3 This illustration shows a structural schematic diagram of a molten salt steam generation system including a temperature-controlled molten salt pipeline, according to an embodiment of this application.

[0014] Figure 4 This illustration shows a structural schematic diagram of a molten salt steam generation system including a molten salt bypass pipe, according to an embodiment of this application.

[0015] Figure 5 This illustration shows a structural schematic diagram of a molten salt steam generation system including a desuperheater, according to an embodiment of this application.

[0016] Figure 6 A schematic diagram of another molten salt steam generation system provided in an embodiment of this application is shown;

[0017] Figure 7 A schematic flowchart of a control method for a molten salt steam generation system provided in an embodiment of this application is shown. Detailed Implementation

[0018] Exemplary embodiments of the present application will now be described in more detail with reference to the accompanying drawings. While exemplary embodiments of the present application are shown in the drawings, it should be understood that the present application may be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that this application will be thorough and complete, and will fully convey the scope of the present application to those skilled in the art.

[0019] In the embodiments of this application, the terms "first," "second," etc., do not have a logical or temporal dependency, nor do they limit the quantity or execution order. It should also be understood that although the following description uses the terms "first," "second," etc., to describe various elements, these elements should not be limited by the terms. These terms are merely used to distinguish one element from another.

[0020] In this application, the term "at least one" means one or more, and the term "multiple" means two or more.

[0021] It should also be understood that the term “if” can be interpreted as “when” or “upon”, or “in response to determination” or “in response to detection”. Similarly, depending on the context, the phrase “if determination…” or “if detection [the stated condition or event]” can be interpreted as “when determination…” or “in response to determination…” or “when detection [the stated condition or event]” or “in response to detection [the stated condition or event]”.

[0022] To facilitate understanding, some relevant comparative examples will be described before describing the embodiments of this application.

[0023] Under the new power system, thermal power generation will gradually shift from being the main source of electricity supply to a supporting and regulating source. Some thermal power units not only need to address the challenges of peak load management and valley load mitigation, but also need to meet heating and steam supply demands. The thermal power unit-molten salt energy storage coupling system is considered a novel energy storage technology that can effectively solve these problems. This technology features high energy density, long storage period, high safety, and low retrofit cost, and is highly adaptable to thermal power units of different capacities.

[0024] The molten salt steam generation system is one of the core modules in the thermal power unit-molten salt energy storage coupling system. During the molten salt heat release stage, high-quality steam is generated after heat exchange between steam / water and high-temperature molten salt in the steam generation system. After prolonged operation, scaling and blockage may occur inside the tubes and shells of heat exchange equipment such as superheaters, evaporators, and preheaters. This can lead to changes in the inlet and outlet parameters on both the molten salt and steam / water sides of the heat exchange equipment, affecting the overall heat exchange efficiency and ultimately directly impacting the performance and safety of the entire steam generation system. Furthermore, the steam generation system needs to operate under different heating and steam supply conditions, resulting in significant differences in the inlet and outlet parameters on both the molten salt and steam / water sides of the various heat exchange equipment within the system.

[0025] like Figure 1 As shown, in existing molten salt steam generation systems, high-temperature molten salt flows sequentially through the heat exchanger, evaporator, and preheater. Scaling and blockage within the upstream heat exchange equipment can cause changes in the molten salt inlet temperature and flow rate of the downstream heat exchange equipment. Simultaneously, the steam-water side outlet parameters of the heat exchange equipment are affected by factors such as changes in the molten salt side inlet parameters, decreased heat transfer efficiency due to scaling and blockage, and strong parameter coupling during frequent switching of steam usage conditions by users. Therefore, it is difficult to achieve precise control of the steam-water side outlet temperature of each heat exchange equipment through adjustment of a single branch valve.

[0026] Therefore, this application provides a molten salt steam generation system.

[0027] Figure 2This is a schematic diagram of a molten salt steam generation system provided in this application. See below for reference. Figure 2 An embodiment of this application will be described.

[0028] like Figure 2 As shown, the molten salt steam generation system includes a steam generation system and a molten salt system.

[0029] The steam generation system includes: a deaerator (2), a feedwater pump (3), a steam drum (69), demineralized water (67), and heat exchange equipment, which includes a preheater (4), an evaporator (5), and a superheater (6).

[0030] The steam generation system consists of four operating stages: water treatment, preheating, evaporation, and superheating.

[0031] During the water treatment stage, the demineralized water (67) passes through the deaerator (2) to remove dissolved oxygen and other non-condensable gases (such as CO2) from the demineralized water, preventing corrosion of metal components in the steam generation system.

[0032] The outlet of the water pump (3) is connected to the outlet of the deaerator (2) through the pipe (37) from the outlet of the deaerator to the inlet of the water pump. The water pump (3) pressurizes the water after it has been deoxygenated by the deaerator (2) and delivers the water to the subsequent heat exchange equipment.

[0033] During the preheating stage, the steam-water side inlet of the preheater (4) is connected to the feedwater pump (3) through the feedwater pump outlet pipe to the preheater inlet pipe (38). The preheater (4) is used to preheat the feedwater with molten salt, increase the water temperature entering the steam drum (close to the saturation temperature), and improve the thermal efficiency.

[0034] During the evaporation stage, the steam drum (69) and the steam-water side outlet of the preheater (4) are connected through the preheater outlet to the steam drum inlet pipe (39), and the feedwater that has been preheated by the preheater (4) enters the steam drum.

[0035] The steam-water side inlet of the evaporator (5) is connected to the steam drum (69) via a downcomer (40). The feedwater in the steam drum enters the evaporator (5) to absorb heat from the molten salt, further heating the feedwater to finally obtain a steam-water mixture. The steam-water side outlet of the evaporator (5) is connected to the steam drum (69) via a riser (41). The steam drum receives the steam-water mixture from the evaporator and generates saturated steam through steam-water separation.

[0036] During the superheating stage, the steam-water side inlet of the superheater (6) is connected to the steam drum (69) through the steam drum outlet to the superheater inlet pipe (42). The superheater (6) further heats the saturated steam output from the steam drum into high-temperature superheated steam. The steam-water side outlet of the superheater (6) outputs qualified superheated steam to the user through the superheater outlet to the heating and steam supply user pipe (43).

[0037] The following is a brief description of the steam-water side process of the steam generation system: Feedwater from the deaerator is pressurized by the feedwater pump and enters the preheater, where it is heated before entering the steam drum. Feedwater from the steam drum is sent to the evaporator via a downcomer for further heating, and then returns to the steam drum via a riser. Saturated steam from the steam drum enters the superheater for further heating into superheated steam before being delivered to heating and steam supply users.

[0038] The structure of the molten salt system is described below. For example... Figure 2 As shown, the molten salt system includes: a high-temperature molten salt tank (7), a low-temperature molten salt tank (8), a high-temperature salt pump (9), a low-temperature salt pump (11), and a molten salt heat storage device (68).

[0039] The high-temperature molten salt tank (7) is a high-temperature molten salt storage device used to store molten salt heated to a high temperature (usually 390°C).

[0040] The low-temperature molten salt tank (8) is a temporary storage device for low-temperature molten salt, used to receive low-temperature molten salt (usually around 190°C) after the release of heat. The molten salt forms a closed loop between the low-temperature molten salt tank (8) and the high-temperature molten salt tank (7), realizing the reuse of molten salt.

[0041] The high-temperature salt pump (9) can drive high-temperature molten salt, that is, pump the high-temperature molten salt from the high-temperature molten salt tank (7) to the heat exchange equipment.

[0042] The cryogenic salt pump (11) can drive cryogenic molten salt, that is, pump the cryogenic molten salt from the cryogenic molten salt tank (8) to the molten salt heat storage device to reheat it.

[0043] The molten salt heat storage device (68) is used to heat the molten salt output from the low-temperature molten salt tank (8). When the molten salt is heated to the target temperature, the molten salt heat storage device (68) outputs high-temperature molten salt to the high-temperature molten salt tank (7).

[0044] The connection structure between the various devices in the molten salt system is described below.

[0045] The low-temperature molten salt tank (8) and the low-temperature salt pump (11) are connected through the molten salt pipeline (32) from the outlet of the low-temperature molten salt tank to the inlet of the low-temperature salt pump. The low-temperature salt pump (11) and the molten salt heat storage device (68) are connected through the molten salt pipeline (33) from the outlet of the low-temperature salt pump to the inlet of the molten salt heat storage device. The molten salt heat storage device (68) and the high-temperature molten salt tank (7) are connected through the molten salt pipeline (34) from the molten salt heat storage device to the inlet of the high-temperature molten salt tank. During the heat storage stage, the low-temperature molten salt is pumped from the low-temperature molten salt tank (8) to the molten salt heat storage device to absorb heat. After being heated, it is stored in the high-temperature molten salt tank (7). The flow of molten salt driven by the low-temperature salt pump (11) forms a loop of "low-temperature tank → heating → high-temperature tank", realizing large-scale storage of thermal energy.

[0046] The high-temperature molten salt tank (7) and the high-temperature salt pump (9) are connected through a pipe (12) from the outlet of the high-temperature molten salt tank to the inlet of the hot salt pump. During the heat release phase, the high-temperature molten salt is pumped from the high-temperature molten salt tank (7) to the heat exchange equipment to release heat, and then returns to the low-temperature molten salt tank (8) after cooling down. The high-temperature salt pump (9) can ensure that the high-temperature molten salt is delivered at a stable flow rate and pressure, maximizing the thermal energy utilization efficiency.

[0047] The connection structure between each piece of equipment in the molten salt system and each heat exchanger in the steam generation system is described below.

[0048] The high-temperature salt pump (9) is connected to the molten salt side inlet of the superheater (6) through the high-temperature salt pump outlet main pipe (13), the first high-temperature molten salt pipe (14), and the first molten salt main pipe (22). That is, one end of the high-temperature salt pump outlet main pipe (13) is connected to the high-temperature salt pump (9), and the other end is connected to the first high-temperature molten salt pipe (14). The other end of the first high-temperature molten salt pipe (14) is connected to the first molten salt main pipe (22), and the other end of the first molten salt main pipe (22) is connected to the molten salt side inlet of the superheater (6).

[0049] The high-temperature salt pump outlet main pipe (13) serves as the main pipe for the output of high-temperature molten salt, distributing the high-temperature molten salt from the high-temperature salt pump (9) to multiple heat exchange devices (such as superheaters, evaporators, and preheaters).

[0050] The first high-temperature molten salt pipeline (14) and the first molten salt main pipeline (22) are used to supply the high-temperature molten salt in the high-temperature salt pump outlet main pipeline (13) to the superheater (6) to ensure its heat input priority.

[0051] A first high-temperature electric regulating valve (46) is installed on the first high-temperature molten salt pipeline (14). The first high-temperature electric regulating valve (46) adjusts the molten salt flow rate of the first high-temperature molten salt pipeline (14) in real time according to the feedback signal of the superheater outlet steam temperature. When the superheat is insufficient, the valve is opened wider to increase the high-temperature molten salt flow rate and raise the steam temperature. When the superheat exceeds the standard, the valve is closed to reduce the molten salt flow rate and lower the steam temperature.

[0052] In addition, the molten salt side outlet of the superheater (6) is connected to the molten salt side inlet of the evaporator (5) through the superheater to evaporator molten salt pipe (25), and the molten salt side outlet of the evaporator (5) is connected to the molten salt side inlet of the preheater (4) through the evaporator to preheater molten salt pipe (26).

[0053] The high-temperature salt pump (9) and the molten salt conveying pipeline (25) are connected through the high-temperature salt pump outlet main pipe (13), the second high-temperature molten salt pipeline (15), and the second molten salt main pipe (23). That is, one end of the high-temperature salt pump outlet main pipe (13) is connected to the high-temperature salt pump (9), and the other end is connected to the second high-temperature molten salt pipeline (15). The other end of the second high-temperature molten salt pipeline (15) is connected to the second molten salt main pipe (23), and the other end of the second molten salt main pipe (23) is connected to the molten salt conveying pipeline (25) between the superheater and the evaporator.

[0054] The second high-temperature molten salt pipeline (15) and the second molten salt main pipeline (23) supply the high-temperature molten salt in the high-temperature salt pump outlet main pipeline (13) to the evaporator (5) to ensure the heat input during its evaporation process.

[0055] A second high-temperature electric regulating valve (48) is installed on the second high-temperature molten salt pipeline (15). The second high-temperature electric regulating valve (48) adjusts the molten salt flow rate in real time according to the temperature and flow rate signal of the steam-water mixture at the evaporator outlet to match the evaporation demand. When the steam demand increases, the valve is opened wider to increase the molten salt flow rate and improve the evaporation rate. When the steam demand decreases, the valve is closed to avoid excessive evaporation that could cause fluctuations in the steam drum water level or waste of molten salt heat.

[0056] The high-temperature salt pump (9) and the molten salt conveying pipeline (26) are connected through the high-temperature salt pump outlet main pipe (13), the third high-temperature molten salt pipeline (16), and the third molten salt main pipe (24). That is, one end of the high-temperature salt pump outlet main pipe (13) is connected to the high-temperature salt pump (9), and the other end is connected to the third high-temperature molten salt pipeline (16). The other end of the third high-temperature molten salt pipeline (16) is connected to the third molten salt main pipe (24), and the other end of the third molten salt main pipe (24) is connected to the molten salt conveying pipeline (26) between the evaporator and the preheater.

[0057] The third high-temperature molten salt pipeline (16) and the third molten salt main pipeline (24) are used to supply the high-temperature molten salt in the high-temperature salt pump outlet main pipeline (13) to the preheater (4) for heating the feed water.

[0058] A third high-temperature electric regulating valve (50) is installed on the third high-temperature molten salt pipeline (16). The third high-temperature electric regulating valve (50) adjusts the molten salt flow rate in real time according to the preheater outlet feedwater temperature and flow rate signal to match the preheating demand. When the feedwater demand increases, the valve is opened wider to increase the molten salt flow rate and improve the preheating efficiency. When the feedwater demand decreases, the valve is closed to avoid overheating, which could lead to feedwater vaporization or waste of molten salt heat.

[0059] like Figure 3As shown, the molten salt system also includes a temperature-regulating salt pump (10), a first temperature-regulating molten salt pipe (19), a second temperature-regulating molten salt pipe (20), and a third temperature-regulating molten salt pipe (21).

[0060] The temperature-regulating salt pump (10) is used to directly pump low-temperature molten salt to each heat exchanger and mix it with the high-temperature molten salt transported from the high-temperature molten salt tank, thereby achieving dynamic adjustment of the molten salt temperature and preventing the molten salt entering the heat exchanger from overheating. The temperature-regulating salt pump (10) can adapt to the changing molten salt inlet parameter requirements, which enhances the flexibility of the molten salt steam generation system.

[0061] The following describes the connection structure between the various devices in the molten salt system and the various heat exchange devices in the steam generation system after the addition of the temperature-regulating salt pump.

[0062] One end of the first temperature-regulating molten salt pipeline is connected to the low-temperature molten salt tank, and the other end is connected to one end of the first molten salt main pipeline. The first temperature-regulating molten salt pipeline (19) is used to supply the low-temperature molten salt output from the low-temperature molten salt tank to the superheater (6), assisting the first high-temperature molten salt pipeline (14) in achieving precise control of the molten salt temperature. After adding the temperature-regulating salt pump, the first molten salt main pipeline (22) is used to receive the mixed molten salt (high-temperature molten salt + low-temperature molten salt) from the first high-temperature molten salt pipeline and the first temperature-regulating molten salt pipeline, thereby achieving precise control of the molten salt temperature at the superheater inlet. By mixing multiple molten salts, it adapts to the frequent changes in the user's steam consumption conditions.

[0063] A first temperature-regulating electric regulating valve (53) is installed on the first temperature-regulating molten salt pipeline (19). The first temperature-regulating electric regulating valve (53) adjusts the molten salt flow rate of the branch (19) in real time according to the feedback signal of the superheater outlet steam temperature. When the superheat is insufficient, the valve is closed to reduce the temperature-regulating molten salt flow rate and increase the steam temperature. When the superheat exceeds the standard, the valve is opened to increase the temperature-regulating molten salt flow rate and decrease the steam temperature.

[0064] One end of the second temperature-regulating molten salt pipeline is connected to the low-temperature molten salt tank, and the other end is connected to one end of the second molten salt main pipeline. The second temperature-regulating molten salt pipeline (20) is used to supply the low-temperature molten salt output from the low-temperature molten salt tank to the evaporator (5) to ensure that the heat input during its evaporation process is controllable. After adding the temperature-regulating salt pump, the second molten salt main pipeline (23) is used to receive the mixed molten salt (high-temperature molten salt + low-temperature molten salt) from the second high-temperature molten salt pipeline and the second temperature-regulating molten salt pipeline, thereby flexibly controlling the molten salt temperature at the evaporator inlet to meet the evaporation requirements of the evaporator.

[0065] A second temperature-regulating electric regulating valve (55) is installed on the second temperature-regulating molten salt pipeline (20). The second temperature-regulating electric regulating valve (55) adjusts the flow rate of the temperature-regulating molten salt in real time according to the steam parameter signal at the evaporator outlet to match the evaporation demand. When the steam demand increases, the valve is closed to reduce the flow rate of the temperature-regulating molten salt and increase the evaporation rate. When the steam demand decreases, the valve is opened to avoid excessive evaporation that could cause fluctuations in the steam drum water level or waste of molten salt heat.

[0066] One end of the third temperature-regulating molten salt pipeline is connected to the low-temperature molten salt tank, and the other end is connected to one end of the third molten salt main pipeline. The third temperature-regulating molten salt pipeline (21) is used to supply the low-temperature molten salt output from the low-temperature molten salt tank to the preheater (4) for dynamically adjusting the feedwater preheating temperature. After adding the temperature-regulating salt pump, the third molten salt main pipeline (24) is used to receive mixed molten salt (high-temperature molten salt + low-temperature molten salt) from the third high-temperature molten salt pipeline and the third temperature-regulating molten salt pipeline, flexibly controlling the molten salt temperature at the preheater inlet. For example, when the system is under low load, low-temperature molten salt is added to prevent feedwater vaporization or waste of molten salt heat.

[0067] A third temperature-regulating electric regulating valve (57) is installed on the third temperature-regulating molten salt pipeline (21). The third temperature-regulating electric regulating valve (57) adjusts the flow rate of the temperature-regulating molten salt in real time according to the feed water temperature or flow signal at the preheater outlet to match the preheating requirements. When the feed water temperature is too low, the valve is closed to reduce the flow rate of the temperature-regulating molten salt and improve the preheating efficiency. When the feed water temperature is too high, the valve is opened to avoid overheating, which could lead to local vaporization of the feed water or waste of molten salt heat.

[0068] In addition, the low-temperature molten salt tank (8) and the temperature-regulating salt pump (10) are connected through the outlet of the low-temperature molten salt tank to the inlet pipe (17) of the temperature-regulating salt pump.

[0069] like Figure 4 As shown, the molten salt system also includes: a first molten salt bypass pipe (27), a second molten salt bypass pipe (28), and a third molten salt bypass pipe (29).

[0070] One end of the first molten salt bypass pipe (27) is connected to the first molten salt main pipe (22), and the other end is connected to the molten salt transport pipe (25) between the superheater and the evaporator. The first molten salt bypass pipe (27) can divert a portion of the molten salt to bypass the superheater (6), reducing the amount of molten salt flowing through the superheater, thereby regulating the heat input of the superheater and preventing steam overheating. When steam demand changes, the bypass molten salt can quickly balance the heat exchange of the system and maintain stable steam parameters. For example, when the superheat rises abnormally, the bypass molten salt can be quickly opened to reduce the heat exchange of the superheater and prevent the steam-water side pipe wall from overheating and bursting.

[0071] A first bypass electric regulating valve (59) is installed on the first molten salt bypass pipeline (27). The first bypass electric regulating valve (59) adjusts the bypass molten salt flow rate in real time according to the superheater outlet steam temperature signal, and accurately controls the proportion of molten salt flowing through the superheater. When the steam superheat is too high, the first bypass electric regulating valve (59) is opened wider to increase the bypass molten salt flow rate and reduce the heat input to the superheater. When the steam superheat is too low, the first bypass electric regulating valve (59) is closed to reduce the bypass flow rate and increase the heat input to the superheater. The first bypass electric regulating valve (59) works in conjunction with the main molten salt regulating valves (46, 53) to achieve "main + bypass" composite temperature control.

[0072] One end of the second molten salt bypass pipe (28) is connected to the molten salt transport pipe (25) between the superheater and the evaporator, and the other end is connected to the molten salt transport pipe (26) between the evaporator and the preheater. The second molten salt bypass pipe (28) is used to divert a portion of the molten salt to bypass the evaporator (5), reducing the amount of molten salt flowing into the evaporator, thereby regulating the heat exchange of the evaporator and avoiding excessive steam production or runaway steam drum water level. When steam demand decreases or the system operates at low load, the bypass molten salt can quickly balance the heat distribution and maintain stable evaporation.

[0073] A second bypass electric regulating valve (61) is installed on the second molten salt bypass pipeline (28). The second bypass electric regulating valve (61) adjusts the bypass molten salt flow rate in real time according to the evaporator outlet temperature and flow rate signal, and precisely controls the proportion of molten salt flowing through the evaporator. When the evaporation demand drops suddenly, the second bypass electric regulating valve (61) is opened wider to increase the bypass molten salt flow rate and reduce the heat input to the evaporator. When the steam demand increases suddenly, the second bypass electric regulating valve (61) is closed to reduce the bypass flow rate and increase the heat output of the evaporator.

[0074] One end of the third molten salt bypass pipe (29) is connected to the molten salt conveying pipe (26) between the evaporator and the preheater, and the other end is connected to the molten salt conveying pipe between the preheater and the low-temperature molten salt tank. The third molten salt bypass pipe (29) diverts a portion of the molten salt to bypass the preheater (4), reducing the amount of molten salt flowing into the preheater, thereby regulating the feedwater preheating temperature and avoiding overheating. When the feedwater flow rate or initial temperature changes (such as during low-load operation), the bypass molten salt can quickly balance the heat exchange and maintain a stable preheating temperature. When the preheater tube bundle leaks or the feedwater temperature is abnormal, the bypass molten salt is quickly opened to reduce the heat exchange of the preheater and prevent equipment damage.

[0075] A third bypass electric regulating valve (63) is installed on the third molten salt bypass pipeline (29). The third bypass electric regulating valve (63) adjusts the bypass molten salt flow rate in real time according to the preheater outlet feedwater temperature and flow rate signal, and accurately controls the proportion of molten salt flowing through the preheater. When the feedwater temperature is too high, the third bypass electric regulating valve (63) is opened wider to increase the bypass molten salt flow rate, reduce the heat input to the preheater, and prevent local vaporization of the feedwater. When the feedwater temperature is too low, the third bypass electric regulating valve (63) is closed to reduce the bypass flow rate and increase the heat input to the preheater.

[0076] After releasing heat in the superheater, the high-temperature molten salt cools down and then enters the evaporator to continue releasing heat. After further cooling in the evaporator, the molten salt enters the preheater to complete the final heat release.

[0077] like Figure 5 As shown, the steam generation system also includes: a desuperheater (1), a first desuperheating pipe (35), and a second desuperheating pipe (36). One end of the first desuperheating pipe (35) is connected to the outlet of the deaerator (2), and the other end is connected to the inlet on the steam-water side of the desuperheater (1). The desuperheater (1) exchanges heat between the molten salt at the outlet of the preheater and the feedwater from the deaerator, thereby reducing the temperature of the molten salt at the outlet of the desuperheater until the temperature of the molten salt entering the low-temperature molten salt tank meets the requirements.

[0078] The first desuperheating pipe (35) is equipped with a desuperheater inlet electric regulating valve (65). The desuperheater inlet electric regulating valve (65) is used to precisely adjust the flow rate of feedwater entering the desuperheater according to the molten salt temperature signal at the preheater outlet. The desuperheater inlet electric regulating valve (65) can ensure that the temperature of the molten salt entering the low-temperature molten salt storage tank meets the requirements.

[0079] One end of the second desuperheating pipe (36) is connected to the outlet on the steam-water side of the desuperheater (1), and the other end is connected to the inlet of the deaerator (2). The high-temperature feedwater after heat exchange with molten salt is sent back to the deaerator through the second desuperheating pipe (36). This application utilizes molten salt to further heat the feedwater in the deaerator, which can reduce the amount of heating steam used in the deaerator and improve energy utilization efficiency.

[0080] This application connects the desuperheater and the deaerator through the first desuperheating pipe (35) and the second desuperheating pipe (36) to form a closed loop, thereby realizing the efficient utilization of energy.

[0081] In addition, the molten salt side outlet of the preheater (4) is connected to the molten salt side inlet of the desuperheater (1) through the preheater outlet to the desuperheater molten salt pipe (30), and the molten salt side outlet of the desuperheater (1) is connected to the low temperature molten salt tank (8) through the desuperheater outlet to the low temperature molten salt tank inlet molten salt pipe (31).

[0082] After the molten salt releases heat in the preheater, its temperature decreases further, but it may still be higher than the safe storage temperature of the cryogenic molten salt tank. Therefore, the molten salt conveyed by the preheater is cooled by a desuperheater, which stores the cooled cryogenic molten salt (approximately 190°C) in the cryogenic molten salt tank, awaiting reheating and recirculation.

[0083] In the embodiments of this application, the desuperheater (1), preheater (4), evaporator (5), and superheater (6) are all shell-and-tube heat exchangers. Molten salt flows through the shell side of the desuperheater (1), preheater (4), evaporator (5), and superheater (6), while steam and water flow through the tube side of the desuperheater (1), preheater (4), evaporator (5), and superheater (6).

[0084] like Figure 6 As shown, this application also includes multiple electric valves for controlling the opening or closing of pipelines.

[0085] A cryogenic salt pump outlet electric valve (64) is installed on the molten salt pipeline (33) from the outlet of the cryogenic salt pump to the inlet of the molten salt heat storage device. The cryogenic salt pump outlet electric valve (64) serves as an isolation valve, used to quickly close in case of molten salt leakage, pump failure, or overpressure.

[0086] A high-temperature salt pump outlet electric valve (44) is installed on the high-temperature salt pump outlet main pipe (13). The high-temperature salt pump outlet electric valve (44) is used to control the connection and disconnection with the high-temperature salt pump outlet main pipe (13), and can be quickly closed in case of high-temperature salt pump failure, overpressure or pipeline leakage.

[0087] A temperature-regulating salt pump outlet electric valve (70) is installed on the outlet main pipe of the temperature-regulating salt pump. The temperature-regulating salt pump outlet electric valve (70) is used to control the opening and closing of the temperature-regulating molten salt outlet main pipe, and quickly closes in case of temperature-regulating salt pump failure, overpressure, or pipeline leakage.

[0088] The first high-temperature molten salt pipeline (14) is also equipped with a first high-temperature molten salt pipeline electric valve (45). The first high-temperature molten salt pipeline electric valve (45) is used to open or close the high-temperature molten salt branch flowing to the superheater (6). It can be used to cut off the molten salt supply in case of superheater failure.

[0089] By matching the real-time heat demand of the superheater with the valve combination (first high-temperature molten salt pipeline electric valve (45) and first high-temperature electric regulating valve (46)), the inlet temperature of the molten salt side of the superheater is avoided from being too high or too low, or from having too much or too little molten salt at the inlet.

[0090] A second high-temperature molten salt pipeline electric valve (47) is also installed on the second high-temperature molten salt pipeline (15). The second high-temperature molten salt pipeline electric valve (47) is used to open or close the high-temperature molten salt branch flowing to the evaporator (5). In case of evaporator failure, the molten salt supply is cut off in an emergency to prevent the accident from escalating.

[0091] The molten salt flow rate of the evaporator branch is independently controlled by valve groups (second high-temperature molten salt pipeline electric valve (47) and second high-temperature electric regulating valve (48)) to avoid interference with other equipment (such as superheaters). Since the evaporator needs stable heat to convert water into saturated steam, the independent branch can accurately match its heat demand.

[0092] A third high-temperature molten salt pipeline electric valve (49) is installed on the third high-temperature molten salt pipeline (16). The third high-temperature molten salt pipeline electric valve (49) is used to open or close the high-temperature molten salt branch flowing to the preheater (4). In the event of a preheater failure, the molten salt supply is cut off to prevent the accident from escalating.

[0093] The flow rate of molten salt in the preheater branch is independently controlled by valve groups (the third high-temperature molten salt pipeline electric valve (49) and the third high-temperature electric regulating valve (50)) to avoid interference with other equipment (such as evaporators and superheaters). The preheater needs to stabilize the heat to preheat the feedwater to near saturation temperature, and the independent branch can accurately match its heat demand.

[0094] The first temperature-regulating molten salt pipeline (19) is also equipped with a first temperature-regulating molten salt pipeline electric valve (52). The first temperature-regulating molten salt pipeline electric valve (52) is used to open or close the temperature-regulating molten salt branch that supplies low-temperature molten salt to the superheater (6). The molten salt supply is cut off in the event of a superheater failure.

[0095] The branch flow rate is independently controlled by valve groups (first temperature-regulating molten salt pipeline electric valve (52) and first temperature-regulating electric regulating valve (53)). The superheater needs to dynamically match the steam parameters, and the independent branch can accurately adjust the heat input.

[0096] The second temperature-regulating molten salt pipeline (20) is also equipped with a second temperature-regulating molten salt pipeline electric valve (54). The second temperature-regulating molten salt pipeline electric valve (54) is used to open or close the temperature-regulating molten salt branch that supplies low-temperature molten salt to the evaporator (5). In the event of an evaporator failure, the molten salt supply is cut off to prevent the accident from escalating.

[0097] The molten salt flow rate of the evaporator branch is independently controlled by valve groups (second temperature-regulating molten salt pipeline electric valve (54) and second temperature-regulating electric regulating valve (55)). The evaporator needs to dynamically match changes in steam load, and the independent branch can accurately adjust the heat input.

[0098] The third temperature-regulating molten salt pipeline (21) is also equipped with a third temperature-regulating molten salt pipeline electric valve (56). The third temperature-regulating molten salt pipeline electric valve (56) is used to open or close the temperature-regulating molten salt branch that supplies low-temperature molten salt to the preheater (4). In the event of a preheater failure, the molten salt supply is cut off to prevent the accident from escalating.

[0099] The branch flow rate is independently controlled by the valve group (the third temperature-regulating molten salt pipeline electric valve (56) and the third temperature-regulating electric regulating valve (57)). The preheater needs to flexibly adjust the heat input according to the feed water flow rate and initial temperature. The independent branch can accurately match the heat demand and prevent feed water vaporization or insufficient preheating.

[0100] The first molten salt bypass pipe (27) is also equipped with a superheater molten salt bypass electric valve (58). The superheater molten salt bypass electric valve (58) is used to open / close the first molten salt bypass pipe (27) and to shut it off in case of system failure. For example, when the system needs to isolate molten salt, the bypass is quickly closed; when the superheater fails, the bypass is fully opened to maintain molten salt circulation.

[0101] The second molten salt bypass pipe (28) is equipped with an evaporator molten salt bypass electric valve (60). The evaporator molten salt bypass electric valve (60) is used to open / close the second molten salt bypass pipe (28). When the system needs to isolate molten salt, the bypass is quickly closed. When the evaporator fails, the bypass is fully opened to maintain molten salt circulation.

[0102] A preheater molten salt bypass electric valve (62) is installed on the third molten salt bypass pipeline (29). The preheater molten salt bypass electric valve (62) quickly closes the bypass when the system needs to isolate the molten salt. In the event of a preheater failure, the bypass is fully open to maintain molten salt circulation.

[0103] The first desuperheating pipe (35) is also equipped with a desuperheater inlet electric valve (65). The desuperheater inlet electric valve (65) acts as an isolation valve to control the opening and closing of the first desuperheating pipe (35) (such as cutting off the demineralized water during maintenance).

[0104] In summary, the molten salt steam generation system provided in this application can flexibly adjust the inlet and outlet temperatures and flow rates of the molten salt side of each heat exchange device in the steam generation system, thereby flexibly controlling the inlet and outlet temperatures and flow rates of the steam and water sides of each heat exchange device in the steam generation system, ensuring the safe operating boundaries and overall heat exchange performance of each heat exchange device in the steam generation system.

[0105] Next, the control method of the molten salt steam generation system will be described in detail with reference to the attached diagram. Figure 7 This application provides a schematic flowchart of a control method for a molten salt steam generation system. The method is used to control a system with… Figures 2 to 6 The molten salt steam generation system with the hardware structure shown includes the following steps:

[0106] Step 710: Obtain the actual outlet temperature and target outlet temperature of the steam-water side of the first heat exchanger.

[0107] The actual outlet temperature of the superheater on the steam-water side can be determined by measuring a temperature sensor that has been pre-inserted into the superheater outlet.

[0108] The target outlet temperature on the steam-water side of the superheater is determined based on user requirements (e.g., the user's steam demand is 319℃). When the outlet temperature on the steam-water side of the superheater is at the target outlet temperature, the user's steam demand can be met. However, overheating of the superheater may cause pipeline creep and rupture, endangering safety.

[0109] The steam-water side outlet of the evaporator contains a steam-water mixture, which is determined by a temperature sensor pre-inserted into the evaporator outlet.

[0110] The target outlet temperature on the steam-water side of the evaporator is the steam-water saturation temperature (e.g., 204.6℃ at 1.71MPa). When the actual outlet temperature on the steam-water side of the evaporator is the target outlet temperature, the steam-water separation efficiency within the steam drum can be guaranteed, preventing water from being carried into the superheater by the steam. Temperature fluctuations may lead to uncontrolled water level in the steam drum (overfilling or dry burning).

[0111] The preheater's steam-water side outlet is unsaturated water, and the actual outlet temperature of the preheater's steam-water side can be measured by a temperature sensor that has been pre-inserted into the preheater outlet.

[0112] The target outlet temperature on the steam-water side of the preheater is the temperature of the unsaturated water (e.g., 201.6℃ at 1.77MPa). When the outlet temperature on the steam-water side of the preheater is the target outlet temperature, it can prevent water with excessively low temperature from directly entering the evaporator, which would cause uneven thermal stress and reduce system efficiency.

[0113] The target outlet temperature on the molten salt side of the desuperheater is the molten salt temperature required to meet the salt inlet requirements of the cryogenic molten salt tank (e.g., 190℃). When the actual outlet temperature on the molten salt side of the desuperheater is the target outlet temperature, the salt temperature of the cryogenic molten salt tank can be kept stable, preventing uneven thermal stress in the cryogenic molten salt tank.

[0114] Step 720: When the absolute value of the temperature difference between the actual outlet temperature and the target outlet temperature on the steam-water side of the first heat exchanger is greater than the threshold, the target inlet temperature on the molten salt side is determined based on the target outlet temperature on the steam-water side of the first heat exchanger.

[0115] When the absolute value of the temperature difference between the actual outlet temperature and the target outlet temperature on the steam-water side of the first heat exchanger exceeds the threshold, it indicates that the molten salt steam generation system is deviating from its design operating conditions. This may be caused by decreased heat transfer efficiency (e.g., insufficient flow on the molten salt side, pipe scaling), abnormal flow on the steam-water side (e.g., pump failure or valve jamming), sensor malfunction, or control logic imbalance. In this case, it is necessary to adjust the molten salt side inlet temperature of the first heat exchanger to meet the steam-water side outlet temperature requirements.

[0116] In one embodiment, the steam-water flow rate of the first heat exchanger is obtained. This is determined by a steam-water flow meter pre-installed on the first heat exchanger.

[0117] The heat exchange capacity on the steam-water side of the first heat exchanger is determined based on the inlet enthalpy, outlet enthalpy, and steam-water flow rate of the steam-water side. The inlet enthalpy refers to the energy per unit mass carried by the feedwater entering each heat exchanger, and the outlet enthalpy refers to the energy per unit mass carried by the feedwater after absorbing heat from the molten salt and leaving each heat exchanger. The enthalpy can be obtained from a steam meter. Specifically, according to Q = m... 汽水 ·(h 汽水出 -h 汽水入 Calculate the heat transfer capacity of each heat exchanger, where m 汽水 h represents the flow rate of the soda. 汽水出 h 汽水入 Here are the enthalpy values ​​at the steam outlet and inlet. Taking an evaporator as an example, if saturated water (h1 = 859 kJ / kg) needs to be evaporated into saturated steam (h2 = 2794 kJ / kg), and the steam flow rate is 312 kg / s, then: Q = 312·(2794-859) = 603720 kW.

[0118] The target inlet temperature is determined based on the target outlet temperature, steam-water side heat exchange, minimum temperature difference, heat transfer coefficient, and heat transfer area. The minimum temperature difference indicates the minimum temperature difference between the molten salt side outlet temperature and the steam-water side outlet temperature of the first heat exchanger. Specifically, based on... Calculate the target inlet temperature on the molten salt side of each heat exchanger, where ΔT min The minimum temperature difference (determined by design specifications, such as ΔT ≥ 30℃ for evaporators), U is the heat transfer coefficient, and A is the heat transfer area. Taking an evaporator as an example, the target outlet temperature on the steam-water side is 204.6℃, and ΔT... min =30℃, if UA = 4566.7kW / ℃, then

[0119]

[0120] Step 730: Obtain the outlet temperature and outlet flow rate of the molten salt side of the upstream heat exchanger of the first heat exchanger based on the heat exchange relationship.

[0121] In a cascaded system consisting of a superheater, evaporator, and preheater, if the first heat exchanger is a superheater, there is no upstream heat exchanger. If the first heat exchanger is an evaporator, and its upstream heat exchanger is a superheater, then the outlet temperature and flow rate on the molten salt side are the measured values ​​at the superheater's molten salt outlet, which can be directly obtained through thermocouples and flow meters on the molten salt header. If the first heat exchanger is a preheater, then the molten salt data at the evaporator outlet needs to be obtained.

[0122] Step 740: When the outlet temperature is lower than the target inlet temperature, determine the molten salt flow rate from the high-temperature molten salt tank to the first heat exchanger based on the outlet temperature, outlet flow rate, and target inlet temperature.

[0123] When the first heat exchanger is an evaporator or preheater, and the outlet temperature of the molten salt side of the upstream heat exchanger is lower than the target inlet temperature of the first heat exchanger, it indicates that the heat of the molten salt flowing out from the upstream heat exchanger is insufficient. In this case, temperature compensation is required by supplementing the molten salt flow rate of the high-temperature molten salt tank based on the molten salt specific heat capacity and energy conservation equation.

[0124] In one implementation, according to Calculate the required molten salt flow rate to be replenished via the high-temperature molten salt tank, where m 出口 T is the outlet flow rate of the upstream heat exchanger. 目标入 T represents the target inlet temperature of the first heat exchanger. 实际出 T represents the outlet temperature of the upstream heat exchanger. 高温罐 The temperature of the molten salt in the high-temperature molten salt vessel.

[0125] Assuming the outlet flow rate of the upper-level heat exchanger is 747 kg / s, the outlet temperature of the upper-level heat exchanger is 300℃, the target inlet temperature of the first heat exchanger is 366.8℃, and the temperature of the molten salt in the high-temperature molten salt tank is 390℃, then... At this point, 2150.8 kg / s of molten salt needs to be added from the high-temperature molten salt tank. After mixing with the outlet flow of the upper heat exchange equipment, the total molten salt flow into the first heat exchange equipment is 2897.8 kg / s. The inlet temperature of the molten salt side of the first heat exchange equipment is 366.8℃, and the temperature of the mixed molten salt meets the standard.

[0126] Step 750: Adjust the opening of the high-temperature electric regulating valve corresponding to the first heat exchanger based on the molten salt flow rate, so that the actual inlet temperature of the molten salt side of the first heat exchanger is the target inlet temperature.

[0127] When the first heat exchanger is an evaporator or a preheater, after determining the molten salt flow rate from the high-temperature molten salt tank to the first heat exchanger based on step 740, the opening degree of the high-temperature electric regulating valve corresponding to the first heat exchanger is adjusted by the PID controller so that the actual inlet temperature of the molten salt side of the first heat exchanger is the target inlet temperature.

[0128] In one implementation, the deviation between the molten salt flow rate calculated in step 740 and the actual molten salt flow rate exiting the high-temperature molten salt tank is used as input. The opening degree of the high-temperature electric regulating valve corresponding to the first heat exchanger is dynamically calculated by combining proportional, integral, and derivative parameters. Simultaneously, feedback data from the molten salt flow meter and temperature sensor are collected in real time. The PID output is corrected through feedforward compensation (e.g., fluctuations in the outlet temperature of the upstream heat exchanger), and the characteristic curve is calibrated for valve nonlinear characteristics (e.g., dead zone, hysteresis) to ensure rapid response and steady-state accuracy of flow regulation. Finally, closed-loop control stabilizes the actual molten salt flow rate exiting the high-temperature molten salt tank at the target value.

[0129] When the first heat exchanger is a superheater, steps 730 and 740 are unnecessary. The opening of the corresponding high-temperature electric regulating valve of the superheater is directly adjusted by the PID controller based on the target inlet temperature on the molten salt side of the superheater, so that the actual inlet temperature on the molten salt side of the superheater is the target inlet temperature. The specific implementation method of adjusting the opening of the corresponding high-temperature electric regulating valve of the superheater by the PID controller is the same as that of the evaporator and preheater, and will not be described in detail here.

[0130] like Figure 3 As shown, in another embodiment, the molten salt system further includes: a first temperature-regulating electric regulating valve, a second temperature-regulating electric regulating valve, and a third temperature-regulating electric regulating valve.

[0131] When the first heat exchanger is an evaporator or preheater, and the outlet temperature of the upper heat exchanger (superheater or evaporator) is not equal to the target inlet temperature of the first heat exchanger, the flow ratio of molten salt flowing from the low-temperature molten salt tank to the first heat exchanger and from the high-temperature molten salt tank to the first heat exchanger is determined based on the outlet temperature, outlet flow rate, and target inlet temperature.

[0132] When the outlet temperature of the upstream heat exchanger deviates from the target inlet temperature of the first heat exchanger, mixing the molten salt in the high-temperature molten salt tank and the low-temperature molten salt tank is to dynamically balance the system's heat supply and demand. If the outlet temperature of the upstream heat exchanger is too high (exceeding the target inlet temperature), low-temperature molten salt needs to be added to cool it down to prevent the first heat exchanger from overheating and being damaged or the steam parameters from becoming uncontrollable. If the outlet temperature of the upstream heat exchanger is too low (below the target inlet temperature), high-temperature molten salt needs to be added to increase the heat input, ensuring that the evaporator or preheater reaches the target heat exchange capacity and maintaining stable process parameters on the steam-water side.

[0133] In one implementation, firstly, according to Calculate the target inlet flow rate on the molten salt side of each heat exchanger. Where, c p Let be the specific heat capacity of the molten salt. Taking an evaporator as an example, if the target inlet temperature on the molten salt side of the evaporator is 366.8℃ and the target outlet temperature is 208.5℃, then: Secondly, the molten salt temperature T in the high-temperature molten salt vessel is collected in real time by a high-temperature thermocouple. H The molten salt temperature T in the low-temperature molten salt vessel L Finally, according to Calculate the molten salt flow rate (m) replenished from the high-temperature molten salt tank. H The flow rate of molten salt replenished to the cryogenic molten salt tank is m L Finally, the flow rate ratio of molten salt flowing from the low-temperature molten salt tank to the first heat exchanger and the flow rate of molten salt flowing from the high-temperature molten salt tank to the first heat exchanger are obtained.

[0134] The calculated flow ratio is used as the input to the PID controller to determine the opening degree of the high-temperature electric regulating valve and the corresponding temperature-regulating electric regulating valve for the first heat exchanger. The high-temperature and temperature-regulating electric regulating valves are adjusted according to their opening degrees to control the actual inlet temperature of the molten salt side of the first heat exchanger as the target inlet temperature. By adjusting the flow ratio of high-temperature and low-temperature molten salt, efficiency losses caused by temperature mismatch of a single molten salt source can be avoided, and the system can flexibly respond to heat source fluctuations or load changes.

[0135] Based on this, the adjustment time difference between the high-temperature electric regulating valve and the temperature regulating electric regulating valve is calculated according to the temperature difference between the outlet temperature and the target inlet temperature. The high-temperature electric regulating valve and the temperature regulating electric regulating valve are adjusted according to the adjustment time difference so that the actual inlet temperature of the molten salt side of the first heat exchanger can quickly reach the target inlet temperature.

[0136] When the temperature difference between the actual inlet temperature and the target inlet temperature on the molten salt side of the first heat exchanger is greater than 0, it indicates that the actual inlet temperature of the molten salt side of the first heat exchanger is too high. In this case, the molten salt temperature needs to be lowered, preferably by opening the temperature regulating electric valve (by adding low-temperature molten salt) or closing the high-temperature electric regulating valve. When the temperature difference between the actual inlet temperature and the target inlet temperature on the molten salt side of the first heat exchanger is less than 0, it indicates that the actual inlet temperature of the molten salt side of the first heat exchanger is too low. In this case, the molten salt temperature needs to be raised, preferably by opening the high-temperature electric regulating valve or closing the temperature regulating electric regulating valve.

[0137] In one embodiment, a step signal is applied to both the high-temperature electric regulating valve and the temperature-regulating electric regulating valve, and the response time t from the opening degree to 10% to 90% is recorded. H and t L The signal transmission delay t for identifying valve action dH and t dL Based on the difference in valve response speed, the adjustment time difference Δt = |t| between the high-temperature electric regulating valve and the temperature-regulating electric regulating valve is set. H -t L |+(t dH -t dL This ensures that the two valves operate synchronously to compensate for temperature deviations. The adjustment time difference between the high-temperature electric regulating valve and the temperature-regulating electric regulating valve is used as the input to the PID controller, which outputs the opening degree of the high-temperature electric regulating valve and the temperature-regulating electric regulating valve. Based on the opening degree output by the PID controller, the high-temperature electric regulating valve and the temperature-regulating electric regulating valve corresponding to the first heat exchanger are adjusted, thereby making the actual inlet temperature of the molten salt side of the first heat exchanger the target inlet temperature.

[0138] The target inlet flow rate on the molten salt side is determined based on the target outlet temperature of the steam-water side of the first heat exchanger; the planned molten salt flow rate to the first heat exchanger is determined, including: molten salt flowing from the low-temperature molten salt tank to the first heat exchanger, molten salt flowing from the high-temperature molten salt tank to the first heat exchanger, molten salt flowing out of the upstream heat exchanger and / or molten salt diverted before flowing into the upstream heat exchanger; when the planned molten salt flow rate is not equal to the target inlet flow rate, the flow difference between the planned molten salt flow rate and the target inlet flow rate is determined; the opening degree of the bypass electric regulating valve corresponding to the first heat exchanger is adjusted based on the flow difference so that the actual inlet flow rate on the molten salt side of the first heat exchanger is the target inlet flow rate.

[0139] When the first heat exchanger is an evaporator or a preheater, the planned molten salt flow to the first heat exchanger includes: molten salt flowing from the low-temperature molten salt tank to the first heat exchanger, molten salt flowing from the high-temperature molten salt tank to the first heat exchanger, molten salt flowing out of the upper-level heat exchanger and / or molten salt diverted before flowing into the upper-level heat exchanger.

[0140] When the first heat exchanger is a superheater, the planned molten salt flow rate to the first heat exchanger includes: molten salt flowing from the low-temperature molten salt tank to the first heat exchanger and molten salt flowing from the high-temperature molten salt tank to the first heat exchanger.

[0141] The following is based on Figure 6 The molten salt steam generation system shown explains how to control the opening of the regulating valves corresponding to each heat exchanger based on the target inlet temperature and target inlet flow rate on the molten salt side of each heat exchanger, so that the actual outlet temperature on the steam-water side of each heat exchanger is the target outlet temperature.

[0142] First, start the high-temperature salt pump (9) and open the high-temperature salt pump outlet electric valve (44), the first high-temperature molten salt pipeline electric valve (45), the second high-temperature molten salt pipeline electric valve (47), and the third high-temperature molten salt pipeline electric valve (49). Establish the high-temperature salt pump path, namely, from the high-temperature molten salt tank (7) to the high-temperature salt pump (9) to the high-temperature salt pump outlet main pipe (13) to each branch (14 / 15 / 16) to the heat exchange equipment (6 / 5 / 4) to the low-temperature molten salt tank (8).

[0143] Start the temperature-regulating salt pump (10), and open the first temperature-regulating molten salt pipeline electric valve (52), the second temperature-regulating molten salt pipeline electric valve (54), and the third temperature-regulating molten salt pipeline electric valve (56). Establish the temperature-regulating salt pump path, namely, from the low-temperature molten salt tank (8) to the temperature-regulating salt pump (10) to the temperature-regulating salt pump outlet main pipe (18) to each temperature-regulating branch (19 / 20 / 21) to the heat exchange equipment (6 / 5 / 4).

[0144] If the outlet valve is closed when starting the pump, pressure buildup may damage the pump body (especially for high-temperature salt pumps). Therefore, after starting the pump, gradually open the outlet valve to ensure a smooth flow of molten salt (valve opening and pump speed should be controlled in tandem).

[0145] When the heat exchanger is a superheater, the opening of the first high-temperature electric regulating valve and / or the first temperature-regulating electric regulating valve is controlled by a PID controller to ensure that the actual inlet temperature on the molten salt side of the superheater is the target inlet temperature. For example, increasing the opening of the first high-temperature electric regulating valve will increase the proportion of high-temperature molten salt, thereby increasing the mixing temperature of the molten salt. Increasing the opening of the first temperature-regulating electric regulating valve will increase the proportion of low-temperature molten salt, thereby decreasing the mixing temperature of the molten salt. When the temperature of the high-temperature molten salt decreases, the opening of the first high-temperature electric regulating valve needs to be increased, and the opening of the first temperature-regulating electric regulating valve needs to be appropriately decreased, so that the actual inlet temperature on the molten salt side of the superheater is the target inlet temperature.

[0146] Furthermore, in the control of the molten salt inlet temperature and flow rate of the superheater, the decoupled control of temperature and flow rate needs to be achieved in stages and in coordination. First, the molten salt mixing ratio is adjusted by the electric regulating valves (46, 53) of the high-temperature molten salt branch and the temperature-regulating molten salt branch to bring the molten salt inlet temperature to the target value. However, this adjustment process may cause the molten salt inlet flow rate to deviate from the target value. If the molten salt flow rate after mixing is insufficient, the opening of the first bypass electric regulating valve needs to be reduced to allow more molten salt to flow to the superheater. If the molten salt flow rate after mixing is excessive, the opening of the first bypass electric regulating valve is increased to divert some molten salt, thereby ensuring that the molten salt inlet flow rate on the superheater side reaches the target inlet flow rate.

[0147] When the heat exchanger is an evaporator, the opening of the second high-temperature electric regulating valve and / or the second temperature-regulating electric regulating valve is controlled by a PID controller to ensure that the actual inlet temperature on the molten salt side of the evaporator is the target inlet temperature. The opening of the second bypass electric regulating valve is controlled, thereby controlling the actual inlet flow rate on the molten salt side of the evaporator to be the target inlet flow rate.

[0148] When the heat exchanger is a preheater, the opening of the third high-temperature electric regulating valve and / or the third temperature-regulating electric regulating valve is controlled by a PID controller to ensure that the actual inlet temperature on the molten salt side of the preheater is the target inlet temperature. The opening of the third bypass electric regulating valve is controlled, thereby controlling the actual inlet flow rate on the molten salt side of the preheater to be the target inlet flow rate.

[0149] The control principles for the target inlet temperature and target inlet flow rate on the molten salt side of the evaporator and preheater are the same as those for the superheater, and will not be elaborated here.

[0150] In addition, the outlet temperature of the molten salt side of the desuperheater also needs to be controlled. Specifically, the target outlet temperature of the molten salt side of the desuperheater needs to be obtained. For example, the target outlet temperature of the molten salt side of the desuperheater is usually set at 190°C (balancing safety and fluidity).

[0151] The target inlet flow rate on the steam-water side of the desuperheater is determined based on the target outlet temperature on the molten salt side of the desuperheater. In one embodiment, based on... Calculate the target inlet flow rate on the steam-water side of the desuperheater. For example, if the molten salt flow rate is 10 kg / s, the inlet temperature is 200°C, the target outlet temperature is 190°C, and the steam-water mixture is cooling water (inlet 25°C, outlet 80°C, enthalpy difference 230 kJ / kg), then:

[0152] When the actual outlet temperature on the molten salt side of the desuperheater does not equal the target outlet temperature, the desuperheater inlet electric valve is opened. The opening of the desuperheater inlet electric regulating valve is controlled by the PID controller to ensure that the actual inlet flow rate on the steam-water side of the desuperheater matches the target inlet flow rate. If the outlet temperature on the molten salt side of the desuperheater is too high, it indicates insufficient molten salt cooling. The feedwater flow rate needs to be increased, and the opening of the desuperheater inlet electric regulating valve needs to be increased to increase the inlet flow rate on the steam-water side of the desuperheater. This enhances the cooling effect of the desuperheater on the molten salt, ultimately causing the outlet temperature on the molten salt side of the desuperheater to return to the set value (target outlet temperature). If the outlet temperature on the molten salt side of the desuperheater is too low, the opposite adjustment is applied.

[0153] In addition, according to the needs of operation adjustment, the corresponding molten salt pipelines can be quickly cut off by closing the electric valves of the first high temperature molten salt pipeline (45), the second high temperature molten salt pipeline (47), the third high temperature molten salt pipeline (49), the first temperature regulating molten salt pipeline (52), the second temperature regulating molten salt pipeline (54), the third temperature regulating molten salt pipeline (56), the superheater molten salt bypass electric valve (58), the evaporator molten salt bypass electric valve (60), and the preheater molten salt bypass electric valve (62). This achieves the purpose of quickly adjusting the inlet molten salt temperature and flow rate of each heat exchanger in the steam generation system, thereby ensuring that the steam and water side parameters of the steam generation system meet the safety requirements of the heat exchanger equipment and the system performance.

[0154] Specifically, closing electric valve 45 (high-temperature branch) and electric valve 52 (temperature-regulating branch), and opening electric valve 58 (bypass) can cut off the superheater molten salt supply and quickly reduce the steam temperature. Closing electric valve 47 (high-temperature branch) and electric valve 54 (temperature-regulating branch), and opening electric valve 60 (bypass) can reduce the heat input to the evaporator and stabilize the steam drum water level. Closing electric valve 49 (high-temperature branch) and electric valve 56 (temperature-regulating branch), and opening electric valve 62 (bypass) can reduce the feedwater preheating temperature. Simultaneously closing electric valves 45 / 47 / 49 (high-temperature branch), electric valves 52 / 54 / 56 (temperature-regulating branch), and electric valves 58 / 60 / 62 (bypass) can completely stop the molten salt circulation, putting the system into a safe shutdown state (suitable for emergency isolation of the molten salt system in cases of severe leaks or other accidents).

[0155] It is understood that, in order to achieve the functions in the above embodiments, the computer device includes hardware structures and / or software modules corresponding to the execution of each function. Those skilled in the art should readily recognize that, based on the units and method steps described in conjunction with the embodiments disclosed in this application, this application can be implemented in hardware or a combination of hardware and computer software. Whether a function is executed by hardware or by computer software driving hardware depends on the specific application scenario and design constraints of the technical solution.

[0156] This application is described with reference to flowchart illustrations and / or block diagrams of methods and systems according to embodiments of this application. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0157] In a typical configuration, the device includes one or more processors (CPUs), memory, and a bus. The device may also include input / output interfaces, network interfaces, etc.

[0158] Memory may include non-persistent memory in computer-readable media, such as random access memory (RAM) and / or non-volatile memory, like read-only memory (ROM) or flash RAM, and memory includes at least one memory chip. Memory is an example of computer-readable media.

[0159] Computer-readable media includes both permanent and non-permanent, removable and non-removable media that can store information using any method or technology. Information can be computer-readable instructions, data structures, modules of programs, or other data. Examples of computer storage media include, but are not limited to, phase-change memory (PRAM), static random access memory (SRAM), dynamic random access memory (DRAM), other types of random access memory (RAM), read-only memory (ROM), electrically erasable programmable read-only memory (EEPROM), flash memory or other memory technologies, CD-ROM, digital versatile optical disc (DVD) or other optical storage, magnetic tape, magnetic magnetic disk storage or other magnetic storage devices, or any other non-transferable medium that can be used to store information accessible by a computing device. As defined herein, computer-readable media does not include transient computer-readable media, such as modulated data signals and carrier waves.

[0160] It should also be noted that the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus. Unless otherwise specified, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes that element.

[0161] Those skilled in the art will understand that embodiments of this application can be provided as methods, systems, or computer program products. Therefore, this application can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, this application can take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0162] The above are merely embodiments of this application and are not intended to limit the scope of this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the scope of the claims of this application.

Claims

1. A molten salt steam generation system, characterized in that, The molten salt steam generation system includes: A steam generation system includes at least a superheater, an evaporator, and a preheater; The molten salt system includes at least: a high-temperature molten salt tank, a low-temperature molten salt tank, a molten salt heat storage device, a first high-temperature molten salt pipeline, a second high-temperature molten salt pipeline, a third high-temperature molten salt pipeline, a first molten salt main pipeline, a second molten salt main pipeline, and a third molten salt main pipeline. One end of the first high-temperature molten salt pipe is connected to the high-temperature molten salt tank, and the other end is connected to one end of the first molten salt main pipe. The other end of the first molten salt main pipe is connected to the superheater. One end of the second high-temperature molten salt pipe is connected to the high-temperature molten salt tank, and the other end is connected to one end of the second molten salt main pipe. The other end of the second molten salt main pipe is connected to the molten salt conveying pipe between the superheater and the evaporator. One end of the third high-temperature molten salt pipe is connected to the high-temperature molten salt tank, and the other end is connected to one end of the third molten salt main pipe. The other end of the third molten salt main pipe is connected to the molten salt conveying pipe between the evaporator and the preheater. The first, second, and third high-temperature molten salt pipelines are all equipped with electric regulating valves for adjusting the molten salt flow rate.

2. The molten salt steam generating system according to claim 1, characterized in that, The molten salt system further includes: a first temperature-regulating molten salt pipe, a second temperature-regulating molten salt pipe, and a third temperature-regulating molten salt pipe; One end of the first temperature-regulating molten salt pipeline is connected to the low-temperature molten salt tank, and the other end is connected to one end of the first molten salt main pipe. One end of the second temperature-regulating molten salt pipeline is connected to the low-temperature molten salt tank, and the other end is connected to one end of the second molten salt main pipe. One end of the third temperature-regulating molten salt pipeline is connected to the low-temperature molten salt tank, and the other end is connected to one end of the third molten salt main pipe. The first temperature-regulating molten salt pipeline, the second temperature-regulating molten salt pipeline, and the third temperature-regulating molten salt pipeline are all equipped with electric regulating valves for adjusting the molten salt flow rate.

3. The molten salt steam generating system according to claim 2, characterized in that, The molten salt system further includes: a first molten salt bypass pipe, a second molten salt bypass pipe, and a third molten salt bypass pipe; One end of the first molten salt bypass pipe is connected to the first molten salt main pipe, and the other end is connected to the molten salt conveying pipe between the superheater and the evaporator. One end of the second molten salt bypass pipe is connected to the molten salt conveying pipe between the superheater and the evaporator, and the other end is connected to the molten salt conveying pipe between the evaporator and the preheater. One end of the third molten salt bypass pipe is connected to the molten salt conveying pipe between the evaporator and the preheater, and the other end is connected to the molten salt conveying pipe between the preheater and the low-temperature molten salt tank. The first molten salt bypass pipeline, the second molten salt bypass pipeline, and the third molten salt bypass pipeline are all equipped with electric regulating valves for adjusting the molten salt flow rate.

4. The molten salt steam generating system according to claim 1, characterized in that, The steam generation system also includes: a desuperheater, a deaerator, a first desuperheating pipe, and a second desuperheating pipe; One end of the first desuperheating pipe is connected to the outlet of the deaerator, and the other end is connected to the inlet on the steam-water side of the desuperheater. One end of the second desuperheating pipe is connected to the outlet on the steam-water side of the desuperheater, and the other end is connected to the inlet of the deaerator. The first desuperheating pipe is equipped with an electric regulating valve for adjusting the water supply flow and an electric valve for controlling the opening or closing of the first desuperheating pipe.

5. The molten salt steam generating system according to claim 3, characterized in that, The first high-temperature molten salt pipeline, the second high-temperature molten salt pipeline, the third high-temperature molten salt pipeline, the first temperature-regulating molten salt pipeline, the second temperature-regulating molten salt pipeline, the third temperature-regulating molten salt pipeline, the first molten salt bypass pipeline, the second molten salt bypass pipeline, and the third molten salt bypass pipeline are all equipped with electric valves for controlling the opening or closing of the pipelines.

6. A control method for a molten salt steam generation system, characterized in that, The method is applied to the molten salt steam generation system as described in any one of claims 1-5, wherein the superheater, evaporator, and preheater are heat exchange devices, and the superheater, evaporator, and preheater sequentially constitute an upper and lower stage heat exchange relationship, and the method includes: Obtain the actual outlet temperature and target outlet temperature on the steam-water side of the first heat exchanger; When the absolute value of the temperature difference between the actual outlet temperature and the target outlet temperature on the steam-water side of the first heat exchanger is greater than the threshold, the target inlet temperature on the molten salt side is determined based on the target outlet temperature on the steam-water side of the first heat exchanger. The outlet temperature and outlet flow rate of the molten salt side of the upstream heat exchanger of the first heat exchanger are obtained based on the heat exchange relationship. When the outlet temperature is lower than the target inlet temperature, the flow rate of molten salt from the high-temperature molten salt tank to the first heat exchanger is determined based on the outlet temperature, the outlet flow rate, and the target inlet temperature. Adjust the opening of the high-temperature electric regulating valve corresponding to the first heat exchanger based on the molten salt flow rate, so that the actual inlet temperature of the molten salt side of the first heat exchanger is the target inlet temperature.

7. The method according to claim 6, characterized in that, The method further includes: When the first heat exchange device is the evaporator or the preheater, and the outlet temperature is not equal to the target inlet temperature, the flow ratio of molten salt flowing from the low-temperature molten salt tank to the first heat exchange device and from the high-temperature molten salt tank to the first heat exchange device is determined based on the outlet temperature, the outlet flow rate, and the target inlet temperature. The opening degree of the high-temperature electric regulating valve and the corresponding temperature-regulating electric regulating valve corresponding to the first heat exchanger are determined based on the flow rate ratio. The high-temperature electric regulating valve and the temperature-regulating electric regulating valve are adjusted according to the opening degree to control the actual inlet temperature of the molten salt side of the first heat exchanger to the target inlet temperature.

8. The method according to claim 7, characterized in that, The step of adjusting the high-temperature electric regulating valve and the temperature-regulating electric regulating valve according to the opening degree includes: Based on the temperature difference between the outlet temperature and the target inlet temperature, calculate the adjustment time difference between the high-temperature electric regulating valve and the temperature-regulating electric regulating valve; Adjust the high-temperature electric regulating valve and the temperature-regulating electric regulating valve according to the adjustment time difference, so that the actual inlet temperature of the molten salt side of the first heat exchanger can quickly reach the target inlet temperature.

9. The method according to claim 8, characterized in that, The method further includes: The target inlet flow rate on the molten salt side is determined based on the target outlet temperature on the steam-water side of the first heat exchanger. Determine the planned molten salt flow rate to the first heat exchanger, the planned molten salt flow rate including: molten salt flowing from the low temperature molten salt tank to the first heat exchanger, molten salt flowing from the high temperature molten salt tank to the first heat exchanger, molten salt flowing out of the upper heat exchanger and / or molten salt diverted before flowing into the upper heat exchanger; When the planned molten salt flow rate is not equal to the target inlet flow rate, determine the flow rate difference between the planned molten salt flow rate and the target inlet flow rate; Adjust the opening of the bypass electric regulating valve corresponding to the first heat exchanger based on the flow difference, so that the actual inlet flow rate on the molten salt side of the first heat exchanger is the target inlet flow rate.

10. The method according to claim 6, characterized in that, Determining the target inlet temperature of the molten salt side based on the target outlet temperature of the steam-water side of the first heat exchanger includes: Obtain the steam-water flow rate of the first heat exchanger; The heat exchange capacity on the steam-water side of the first heat exchanger is determined based on the inlet enthalpy, outlet enthalpy, and steam-water flow rate of the first heat exchanger. The target inlet temperature is determined based on the target outlet temperature, the heat exchange capacity on the steam-water side, the minimum temperature difference, the heat transfer coefficient, and the heat exchange area. The minimum temperature difference is used to indicate the minimum temperature difference between the molten salt side outlet temperature and the steam-water side outlet temperature of the first heat exchanger.

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