A low-temperature heat supply molten salt energy storage dynamic adjustment control method

Abstract

This invention relates to the field of thermal energy storage and utilization technology, and particularly to a dynamic regulation and control method for low-temperature heating molten salt energy storage. The method comprises five steps: system initialization and molten salt anti-condensation preparation, off-peak electricity period thermal storage operation control, peak electricity period heat release and heating control, full-process parameter monitoring and safety interlocking, and dynamic control of molten salt anti-condensation. The DCS system enables dynamic adjustment of the molten salt electric heater power and pump frequency conversion, coupled with closed-loop flow control and precise heating temperature regulation. Simultaneously, it monitors all system parameters in real time and triggers interlocking protection, and can dynamically adjust the electric heat tracing power based on the molten salt pipeline wall temperature. In this invention, through off-peak and off-peak electricity period staggered operation and multi-parameter coordinated adjustment, precise matching of molten salt thermal storage and heating demand is achieved, ensuring stable water supply temperature, fully utilizing off-peak electricity resources to improve energy efficiency, and simultaneously constructing a full-process molten salt anti-condensation system to enhance the stability and safety of system operation.

Description

Technical Field

[0001] This invention relates to the field of thermal energy storage and utilization technology, and in particular to a dynamic regulation and control method for low-temperature heating molten salt energy storage. Background Technology

[0002] In the field of low-temperature heating, molten salt energy storage technology has gradually attracted attention due to its advantages of high energy density and strong stability. However, existing technologies mostly apply molten salt energy storage to high-temperature power generation scenarios, and their adaptability design for low-temperature heating is insufficient. Currently, low-temperature heating commonly uses water thermal storage or direct electric heating. Water thermal storage suffers from low energy density and large heat loss, while direct electric heating directly consumes peak electricity resources, resulting in low energy utilization efficiency. The few attempts to apply molten salt energy storage to low-temperature heating lack a precise scheduling mechanism for peak and off-peak electricity periods and have not established a coordinated regulation logic between molten salt heating power, pump flow rate, and heating demand.

[0003] In existing technologies, the matching degree between molten salt thermal storage and heating demand is poor, and flow control and temperature regulation are disconnected, resulting in large fluctuations in water supply temperature and an inability to stably meet heating requirements. Furthermore, off-peak electricity resources are not fully utilized for peak-shaving energy storage, leading to energy waste. Therefore, there is an urgent need for a dynamic regulation and control method for low-temperature heating molten salt energy storage that can achieve precise matching between molten salt thermal storage and heating demand, ensure stable water supply temperature, and improve energy utilization efficiency. Summary of the Invention

[0004] To overcome the above shortcomings, this invention provides a dynamic regulation and control method for low-temperature heating molten salt energy storage, aiming to improve the problems of insufficient matching between molten salt heat storage and heating demand, unstable water supply temperature, and low energy utilization efficiency in the existing technology.

[0005] This invention provides the following technical solution: a method for dynamic regulation and control of molten salt energy storage for low-temperature heating, comprising the following steps: S1: System initialization and molten salt anti-condensation preparation: Preheat the molten salt in the cold salt tank and hot salt tank, as well as the water in the molten salt evaporator, until the system reaches the preset initial temperature. S2: Off-peak electricity period thermal storage operation control: During off-peak electricity periods, the cold salt pump is started to transport the low-temperature molten salt in the cold salt tank to the molten salt electric heater for heating, and the heated high-temperature molten salt is stored in the hot salt tank; at the same time, the electric heat tracing device maintains the heat tracing of the molten salt pipeline and equipment; S3: Peak Power Period Heat Release and Heating Control: During peak power periods, the hot salt pump is started to transport the high-temperature molten salt in the hot salt tank to the molten salt evaporator to release heat to heat the water supply; the heating temperature is stabilized by adjusting the flow rate of the hot salt pump. S4: Full-process parameter monitoring and safety interlock: During the operation of any of the S1, S2, and S3 stages, the DCS system collects key system parameters in real time and performs logical judgments; when any parameter exceeds its corresponding safety threshold, the DCS system triggers and executes the corresponding interlock protection action. S5: Dynamic control of molten salt anti-condensation: When the system is in non-active heating operation or standby state, the electric heat tracing device is kept running continuously; the DCS system periodically collects the wall temperature measurement value of the molten salt pipeline and dynamically adjusts the heating power of the electric heat tracing device of the corresponding section according to the wall temperature measurement value.

[0006] By adopting the above technical solutions: through the operation mode of off-peak electricity heat storage and peak electricity heat release, combined with the DCS system for dynamic adjustment of the power of the molten salt electric heater and the frequency conversion frequency of the pump group, as well as the closed-loop control of the flow, precise matching of heat storage and heating demand is achieved, improving energy utilization efficiency; relying on initial salt preheating, electric heat tracing throughout the process, and dynamic adjustment of wall temperature, a full-process molten salt anti-condensation system is constructed to ensure continuous system operation; through real-time monitoring of multiple parameters and multi-level interlocking protection, operational safety is enhanced; by leveraging the redundant configuration of pump groups and resource recycling, stability and economy are balanced; and with clearly defined key parameters and precise monitoring feedback, the system's automation level is improved, adapting to the actual application needs of low-temperature heating.

[0007] Preferably, in step S1, the system initialization specifically includes: adding ternary molten salt into the cold salt tank and the hot salt tank and starting the electric heater of the molten salt tank to melt the salt; simultaneously injecting water into the molten salt evaporator and starting the electric heater of the molten salt evaporator; and simultaneously starting the electric heating device after the salt melting begins; monitoring the temperature of the molten salt in the tank and the water temperature in the molten salt evaporator through temperature sensors and feeding them back to the DCS system; when the temperature of the molten salt in the tank and the water temperature both reach and stabilize at 180°C, the initialization is determined to be complete.

[0008] Preferably, during the salt melting process, the electric heater of the molten salt tank is controlled to operate at a power of 50kW per unit until the solid molten salt in the tank is completely melted and the temperature rises uniformly to 180°C.

[0009] Preferably, in step S2, the off-peak electricity period thermal storage operation control specifically includes: starting the cold salt pump to transport low-temperature molten salt with a temperature of about 200°C in the cold salt tank to the molten salt electric heater; controlling the operation of the molten salt electric heater and dynamically adjusting its output power based on real-time monitoring of the molten salt temperature at the outlet of the molten salt electric heater to heat the molten salt to a target temperature of about 350°C; and then transporting the heated high-temperature molten salt to the hot salt tank for storage.

[0010] Preferably, in step S2, the off-peak electricity period thermal storage operation control further includes flow closed-loop control, specifically: the molten salt flow rate output by the cold salt pump is measured in real time by an ultrasonic flow meter and fed back to the DCS system; the DCS system compares the flow measurement value with the preset flow rate setting value of 8.43t / h, and if a deviation occurs, the frequency of the inverter of the cold salt pump is adjusted so that the actual flow rate returns to the setting value.

[0011] Preferably, the method of dynamically adjusting the output power based on real-time monitoring of the molten salt temperature at the outlet of the molten salt electric heater specifically involves: measuring the molten salt temperature at the outlet of the molten salt electric heater in real time using a thermocouple and feeding it back to the DCS system; the DCS system compares the measured temperature value with a high-temperature target value of 350°C, and if it is lower than the target value, increases the output power of the molten salt electric heater; if it is higher than the target value, decreases its output power.

[0012] Preferably, in step S3, the peak-period heat release and heating control specifically includes: starting the hot salt pump to transport high-temperature molten salt (approximately 350°C) from the hot salt tank to the molten salt evaporator; the high-temperature molten salt releases heat in the molten salt evaporator to heat the water supply; a temperature sensor installed on the water supply pipeline measures the actual temperature of the water supply outlet in real time and feeds it back to the DCS system; the DCS system compares the actual temperature value with the target water supply temperature of 50°C, and adjusts the frequency converter frequency of the hot salt pump according to the comparison result to change the flow rate of the high-temperature molten salt, thereby controlling the water supply outlet temperature at 48-52°C.

[0013] Preferably, in step S3, the peak power period heat release and heating control further includes: continuously monitoring the water level in the molten salt evaporator through a differential pressure level gauge and feeding it back to the DCS system; if the water level measurement value is lower than the preset minimum safe water level, the DCS system controls the start of the water replenishment pump to replenish water to the molten salt evaporator until the water level returns to the normal range.

[0014] Preferably, in step S4, the key system parameters include molten salt temperature, molten salt flow rate, system pressure, molten salt tank level, molten salt evaporator water level and temperature; the safety threshold and interlock protection actions at least include: When the molten salt temperature is detected to be below 142℃ or above 450℃, the first level of interlock is executed: the DCS system stops the operation of the molten salt electric heater. When the system pressure is detected to exceed the normal operating range of 0.5MPa to 1MPa, the second-level interlock is executed: the DCS system stops the operation of the cold salt pump and the hot salt pump; When the pressure in the molten salt pipeline exceeds 2MPa, the third-level interlock is activated: the DCS system controls the opening of the pipeline pressure relief valve; When the temperature of the molten salt in the molten salt tank remains below 150°C for 10 minutes, the fourth level of interlock is activated: the DCS system automatically starts the electric heater of the molten salt tank to intervene and raise the temperature.

[0015] Preferably, in step S5, the step of dynamically adjusting the heating power of the electric heat tracing device for the corresponding section based on the wall temperature measurement value specifically involves the DCS system comparing the wall temperature measurement values ​​of key points in the molten salt pipeline collected at regular intervals with the anti-condensation temperature threshold of 170°C. If the wall temperature measurement value of any key point is lower than the anti-condensation temperature threshold, the heating power of the electric heat tracing device for the corresponding pipe section is increased.

[0016] The present invention has the following beneficial effects: 1. In this invention, by using the operation mode of storing heat during off-peak hours and releasing heat during peak hours, combined with the dynamic adjustment of the power of the molten salt electric heater and the frequency of the cold salt pump and hot salt pump by the DCS system, and with the flow closed-loop control and precise regulation of the heating temperature, the precise matching of molten salt heat storage and heating demand is achieved, ensuring that the water supply temperature is stable within the target range. At the same time, it makes full use of off-peak electricity resources, improves energy utilization efficiency, and ensures the efficient coordination of the system's heat storage and heat release processes.

[0017] 2. In this invention, a complete molten salt anti-condensation protection system is formed by preheating the molten salt during the system initialization stage, using an electric heat tracing device for full-process heat tracing, and using a DCS system to periodically collect the molten salt pipeline wall temperature and dynamically adjust the electric heat tracing power. This effectively prevents the molten salt from solidifying due to excessively low temperatures, prevents pipeline and equipment blockage, and ensures the continuous and stable operation of the system under different operating conditions.

[0018] 3. In this invention, key parameters such as molten salt temperature, system pressure, and liquid level are collected in real time through the DCS system. Multi-level interlock protection actions are set up to implement corresponding shutdown, pressure relief, or temperature increase intervention measures for different abnormal parameter conditions. This comprehensively covers the safety risk points in system operation, enhances the safety and reliability of system operation, and avoids equipment damage due to abnormal parameters.

[0019] 4. In this invention, the cold salt pump and the hot salt pump adopt a redundant configuration of 1 in use and 1 in standby. Molten salt and condensate are recycled. The water replenishment pump dynamically replenishes water according to the water level of the molten salt evaporator. This not only improves the fault tolerance of the system operation and avoids system shutdown due to the failure of a single device, but also reduces resource waste and takes into account the stability and economy of the system operation.

[0020] 5. In this invention, by clearly defining key parameters such as the ternary molten salt ratio, electric heater power, and temperature and pressure thresholds, and combining the precise monitoring and data feedback of various sensors, the system control logic becomes more operable, ensuring the orderly coordinated operation of each device, reducing the need for human intervention, improving the system's automation level, and adapting to the actual application needs of low-temperature heating scenarios. Attached Figure Description

[0021] Figure 1 This is a flowchart of a dynamic regulation and control method for low-temperature heating molten salt energy storage proposed in this invention. Detailed Implementation

[0022] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0023] This invention provides a method for dynamic regulation and control of molten salt energy storage for low-temperature heating, such as... Figure 1 As shown, it includes the following steps: S1: System initialization and molten salt anti-condensation preparation: Preheat the molten salt in the cold salt tank and hot salt tank, as well as the water in the molten salt evaporator, until the system reaches the preset initial temperature. Furthermore, the system initialization specifically includes: adding ternary molten salt into the cold salt tank and the hot salt tank and starting the electric heater of the molten salt tank to melt the salt; simultaneously injecting water into the molten salt evaporator and starting the electric heater of the molten salt evaporator; and simultaneously starting the electric heat tracing device after the salt melting begins; monitoring the temperature of the molten salt in the tank and the water temperature in the molten salt evaporator through temperature sensors and feeding them back to the DCS system; when the temperature of the molten salt in the tank and the water temperature both reach and stabilize at 180°C, the initialization is considered complete. Furthermore, during the salt melting process, the electric heater of the molten salt tank is controlled to operate at a power of 50kW per unit until the solid molten salt in the tank is completely melted and the temperature rises uniformly to 180°C.

[0024] Specifically, ternary molten salt is added to both the cold and hot salt tanks in a ratio of 53% potassium nitrate, 40% sodium nitrite, and 7% sodium nitrate. This ratio ensures that the molten salt's freezing point remains stable at 142℃ and its decomposition point at approximately 450℃, providing a suitable molten salt medium for low-temperature heating scenarios. Two immersion-type electric heaters (two each for the cold and hot salt tanks, totaling four units, each with a power of 60kW) are activated. This multi-unit, evenly distributed heating achieves rapid and uniform melting of the solid molten salt. Simultaneously, the electric heaters of the 50kW molten salt evaporator are activated, with dual-path heating working in tandem to quickly raise the temperature of the molten salt in the tanks and the water temperature in the evaporator to 180℃. After the salt melting begins, an electric heat tracing device covering the molten salt tanks, pipes, and valves is activated simultaneously to preheat all components in contact with the molten salt, preventing solidification due to excessively low component temperatures as the molten salt flows through. Simultaneously, the nitrogen protection system is activated, filling the tank with inert gas through a 15MPa, 1000L nitrogen cylinder. A gas-connected pipe, nitrogen sealing valve, and breather valve are installed between tanks to maintain stable pressure, preventing air from contacting the ternary molten salt and thus preventing oxidation and deterioration. For example, in winter when ambient temperatures are low, four 60kW electric heaters operate simultaneously, with preheating via electric heat tracing. Salt melting and reaching the initial temperature of 180℃ can be completed in just 3 hours, effectively avoiding problems such as unmelted molten salt or salt buildup on the pipe walls, ensuring smooth system startup.

[0025] S2: Off-peak electricity period thermal storage operation control: During off-peak electricity periods, the cold salt pump is started to transport the low-temperature molten salt in the cold salt tank to the molten salt electric heater for heating, and the heated high-temperature molten salt is stored in the hot salt tank; at the same time, the electric heat tracing device maintains the heat tracing of the molten salt pipeline and equipment; Furthermore, the off-peak electricity period thermal storage operation control specifically includes: starting the cold salt pump to transport low-temperature molten salt at a temperature of approximately 200°C from the cold salt tank to the molten salt electric heater; controlling the operation of the molten salt electric heater and dynamically adjusting its output power based on real-time monitoring of the molten salt temperature at the outlet of the molten salt electric heater to heat the molten salt to a target temperature of approximately 350°C; and then transporting the heated high-temperature molten salt to the hot salt tank for storage. Furthermore, the off-peak electricity period thermal storage operation control also includes flow closed-loop control, specifically: the molten salt flow rate output by the cold salt pump is measured in real time by an ultrasonic flow meter and fed back to the DCS system; the DCS system compares the flow measurement value with the preset flow rate setting value of 8.43t / h, and if there is a deviation, the frequency of the inverter of the cold salt pump is adjusted so that the actual flow rate returns to the setting value; Furthermore, the method of dynamically adjusting the output power based on real-time monitoring of the molten salt temperature at the outlet of the molten salt electric heater specifically involves: measuring the molten salt temperature at the outlet of the molten salt electric heater in real time using a thermocouple and feeding it back to the DCS system; the DCS system compares the measured temperature value with a high-temperature target value of 350°C, and if it is lower than the target value, increases the output power of the molten salt electric heater; if it is higher than the target value, decreases its output power.

[0026] Specifically, a molten salt electric heater with a base power of 550kW is selected, with sufficient heating margin to ensure that the low-temperature molten salt in the cold salt tank can be stably heated to 350℃ during the 8-hour off-peak electricity period. The cold salt pump adopts a redundant configuration of two units, one in operation and one on standby. Each unit has a design flow rate of 5m³ / h and a head of 20m. During operation, the output flow rate data is collected in real time by an ultrasonic flow meter and fed back to the DCS system. When the flow rate deviates from the preset value of 8.43t / h, the DCS system automatically adjusts the frequency of the cold salt pump inverter to maintain a stable flow rate. Simultaneously, the outlet temperature of the molten salt electric heater is monitored in real time by a thermocouple, and the heater output power is dynamically adjusted according to the temperature deviation to ensure that the molten salt accurately reaches the target temperature of 350℃. After the high-temperature molten salt is delivered to the hot salt tank, the nitrogen protection system continues to operate to maintain an inert atmosphere inside the tank and prevent oxidation reactions from contact with air. For example, when the flow rate of the cold salt pump drops to 7.8 t / h due to changes in pipeline resistance, the DCS system immediately increases the frequency of the inverter from 45 Hz to 50 Hz, and the flow rate recovers to 8.43 t / h within 1 minute. With the fine adjustment of the heater power, the molten salt is heated evenly, and the target heat storage capacity of 4 MWh is finally achieved. Moreover, the molten salt in the hot salt tank has stable performance and no oxidation or deterioration.

[0027] S3: Peak Power Period Heat Release and Heating Control: During peak power periods, the hot salt pump is started to transport the high-temperature molten salt in the hot salt tank to the molten salt evaporator to release heat to heat the water supply; the heating temperature is stabilized by adjusting the flow rate of the hot salt pump. Furthermore, the peak-period heat release and heating control specifically includes: starting the hot salt pump to transport high-temperature molten salt (approximately 350°C) from the hot salt tank to the molten salt evaporator; the high-temperature molten salt releases heat in the molten salt evaporator to heat the water supply; a temperature sensor installed on the water supply pipeline measures the actual temperature of the water supply outlet in real time and feeds it back to the DCS system; the DCS system compares the actual temperature value with the target water supply temperature of 50°C, and adjusts the frequency converter frequency of the hot salt pump according to the comparison result to change the flow rate of the high-temperature molten salt, thereby controlling the water supply outlet temperature at 48-52°C; Furthermore, the peak power period heat release and heating control also includes: continuously monitoring the water level in the molten salt evaporator through a differential pressure level gauge and feeding it back to the DCS system; if the water level measurement value is lower than the preset minimum safe water level, the DCS system controls the start of the water replenishment pump to replenish water to the molten salt evaporator until the water level returns to the normal range.

[0028] Specifically, the hot salt pumps employ a redundant configuration of two units, one in operation and one on standby. Each unit has a design flow rate of 5 m³ / h and a head of 20 m. During operation, the process parameters of molten salt pressure (1 MPa) and supply water pressure (0.5 MPa) are strictly controlled to ensure a stable and safe heat exchange process. The hot salt pumps deliver molten salt at 350°C from the hot salt tank to the molten salt evaporator. The high-temperature molten salt releases heat in the evaporator, causing the water in the tank to generate saturated steam. The steam exchanges heat with the cooling coils, heating the 30°C supply water to the target temperature. After releasing heat, the molten salt cools to 200°C and returns to the cold salt tank for recycling. Temperature sensors in the supply water pipeline collect the outlet water temperature in real time and feed it back to the DCS system. The DCS system adjusts the frequency of the hot salt pump inverter to change the molten salt delivery flow rate based on the deviation between the water temperature and the target value of 50°C, dynamically matching the heating demand. A differential pressure level gauge continuously monitors the water level inside the evaporator. When the water level falls below the minimum safe level, the DCS system activates the water replenishment pump to maintain a stable heat exchange area. Simultaneously, the condensate in the evaporator flows back to the bottom for recycling, improving water resource utilization. For example, when increased heating demand causes the supply water temperature to drop to 47℃, the DCS system increases the frequency of the hot salt pump from 40Hz to 46Hz and the molten salt delivery flow rate from 7.5t / h to 8.6t / h. After 1.5 minutes, the supply water temperature rises back to 49℃ and remains stable within the 48-52℃ range, ensuring that the heating quality meets standards.

[0029] S4: Full-process parameter monitoring and safety interlock: During the operation of any of the S1, S2, and S3 stages, the DCS system collects key system parameters in real time and performs logical judgments; when any parameter exceeds its corresponding safety threshold, the DCS system triggers and executes the corresponding interlock protection action. Furthermore, the key system parameters include molten salt temperature, molten salt flow rate, system pressure, molten salt tank level, molten salt evaporator water level and temperature; the safety thresholds and interlocking protection actions at least include: When the molten salt temperature is detected to be below 142℃ or above 450℃, the first level of interlock is executed: the DCS system stops the operation of the molten salt electric heater. When the system pressure is detected to exceed the normal operating range of 0.5MPa to 1MPa, the second-level interlock is executed: the DCS system stops the operation of the cold salt pump and the hot salt pump; When the pressure in the molten salt pipeline exceeds 2MPa, the third-level interlock is activated: the DCS system controls the opening of the pipeline pressure relief valve; When the temperature of the molten salt in the molten salt tank remains below 150°C for 10 minutes, the fourth level of interlock is activated: the DCS system automatically starts the electric heater of the molten salt tank to intervene and raise the temperature.

[0030] Specifically, radar level gauges are used to collect real-time molten salt level data in both cold and hot salt tanks, ensuring that the molten salt storage level remains within a safe range during heat storage and release, preventing pump idling due to excessively low levels or molten salt overflow due to excessively high levels. K-type armored thermocouples are used to collect the wall temperature of molten salt pipelines, tanks, and equipment, in conjunction with a pressure transmitter with an accuracy of ±0.075% to monitor pipeline pressure. All monitoring data is transmitted to the DCS system via 4-20mA signals, enabling comprehensive awareness of the system's operational status. When the molten salt temperature is detected to be below 142℃ or above 450℃, the DCS system immediately stops the molten salt electric heater to prevent the molten salt from solidifying and clogging pipes or decomposing and damaging equipment. When the system pressure exceeds the range of 0.5MPa to 1MPa, the cold salt pump and hot salt pump stop operating to prevent pressure imbalance and potential safety hazards. When the pipeline pressure exceeds 2MPa, the pressure relief valve is quickly opened to release pressure, reducing the pressure to a safe range within 30 seconds. When the molten salt temperature in the molten salt tank remains below 150℃ for 10 minutes, the molten salt tank electric heater is automatically activated for emergency heating, and the pressure data from the nitrogen protection system is simultaneously fed back to the DCS, forming multiple layers of protection. For example, during one operation, a slight valve jam caused the pipeline pressure to rise to 2.1MPa. The DCS system immediately triggered the third-level interlock, the pressure relief valve opened quickly, and the pipeline pressure dropped to 1.8MPa after 25 seconds, effectively avoiding the risk of pipeline overpressure rupture and ensuring the safe operation of the system throughout its entire lifecycle.

[0031] S5: Dynamic control of molten salt anti-condensation: When the system is in non-active heating operation or standby state, the electric heat tracing device is kept running continuously; the DCS system periodically collects the wall temperature measurement value of the molten salt pipeline and dynamically adjusts the heating power of the electric heat tracing device of the corresponding section according to the wall temperature measurement value.

[0032] Furthermore, the step of dynamically adjusting the heating power of the electric heat tracing device for the corresponding section based on the wall temperature measurement value is as follows: the DCS system compares the wall temperature measurement values ​​of key points in the molten salt pipeline collected at regular intervals with the anti-condensation temperature threshold of 170°C. If the wall temperature measurement value of any key point is lower than the anti-condensation temperature threshold, the heating power of the electric heat tracing device for the corresponding pipe section is increased.

[0033] Specifically, the electric heat tracing device comprehensively covers the molten salt tank, all molten salt pipelines and valves, operating continuously in all operating states, including heat storage, heat release, and standby, providing insulation for components in contact with the molten salt throughout the entire process. The DCS system collects the wall temperature of key pipeline points every 5 minutes via K-type armored thermocouples, strictly adhering to the set temperature range of 170-180℃. When the wall temperature at any key point drops below 170℃, the heating power of the electric heat tracing device for that pipe section is immediately increased. Once the wall temperature rises to 180℃, the power is restored to normal, avoiding wasted heating power and preventing localized low temperatures that could lead to molten salt solidification. This dual anti-condensation design of "full-process insulation + dynamic adjustment," combined with the salt preheating in the S1 stage and real-time monitoring during operation, forms a complete anti-condensation guarantee. For example, during system standby, if the ambient temperature drops to -5℃ and the wall temperature of a certain section of the pipe drops to 168℃, the DCS system will quickly increase the electric heating power of that section from 3kW to 4.5kW. After 8 minutes, the wall temperature will rise to 175℃ and stabilize in that range, ensuring that the molten salt is always in a temperature environment above the freezing point, thus completely avoiding the risk of pipe blockage and ensuring the long-term stable operation of the system.

[0034] Finally, it should be noted that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for dynamic adjustment control of low-temperature heat supply molten salt energy storage, characterized in that, Includes the following steps: S1: System initialization and molten salt anti-condensation preparation: Preheat the molten salt in the cold salt tank and hot salt tank, as well as the water in the molten salt evaporator, until the system reaches the preset initial temperature. S2: Off-peak electricity period thermal storage operation control: During off-peak electricity periods, the cold salt pump is started to transport the low-temperature molten salt in the cold salt tank to the molten salt electric heater for heating, and the heated high-temperature molten salt is stored in the hot salt tank; at the same time, the electric heat tracing device maintains the heat tracing of the molten salt pipeline and equipment; S3: Peak Power Period Heat Release and Heating Control: During peak power periods, the hot salt pump is started to transport the high-temperature molten salt in the hot salt tank to the molten salt evaporator to release heat to heat the water supply; the heating temperature is stabilized by adjusting the flow rate of the hot salt pump. S4: Full-process parameter monitoring and safety interlock: During the operation of any of the S1, S2, and S3 stages, the DCS system collects key system parameters in real time and performs logical judgments; when any parameter exceeds its corresponding safety threshold, the DCS system triggers and executes the corresponding interlock protection action. S5: Dynamic control of molten salt anti-condensation: When the system is in non-active heating operation or standby state, the electric heat tracing device is kept running continuously; the DCS system periodically collects the wall temperature measurement value of the molten salt pipeline and dynamically adjusts the heating power of the electric heat tracing device of the corresponding section according to the wall temperature measurement value.

2. A low temperature heat supply molten salt energy storage dynamic adjustment control method according to claim 1, characterized in that, In step S1, the system initialization specifically includes: adding ternary molten salt into the cold salt tank and the hot salt tank and starting the electric heater of the molten salt tank to melt the salt; simultaneously injecting water into the molten salt evaporator and starting the electric heater of the molten salt evaporator; and simultaneously starting the electric heat tracing device after the salt melting begins; monitoring the temperature of the molten salt in the tank and the water temperature in the molten salt evaporator through temperature sensors and feeding them back to the DCS system; when the temperature of the molten salt in the tank and the water temperature both reach and stabilize at 180°C, the initialization is determined to be complete.

3. A method of dynamic adjustment control of a low-temperature heat supply molten salt energy storage system according to claim 2, characterized in that, During the salt melting process, the electric heater of the molten salt tank is controlled to operate at a power of 50kW per unit until the solid molten salt in the tank is completely melted and the temperature rises uniformly to 180°C.

4. The method of claim 2, wherein the method further comprises, In step S2, the specific control of the off-peak electricity period thermal storage operation includes: starting the cold salt pump to transport the low-temperature molten salt with a temperature of about 200°C in the cold salt tank to the molten salt electric heater; controlling the operation of the molten salt electric heater and dynamically adjusting its output power based on real-time monitoring of the molten salt temperature at the outlet of the molten salt electric heater to heat the molten salt to a target temperature of about 350°C; and then transporting the heated high-temperature molten salt to the hot salt tank for storage.

5. A low temperature heat supply molten salt energy storage dynamic adjustment control method according to claim 4, characterized in that, In step S2, the off-peak electricity period thermal storage operation control also includes flow closed-loop control, specifically: the molten salt flow rate output by the cold salt pump is measured in real time by an ultrasonic flow meter and fed back to the DCS system; the DCS system compares the flow measurement value with the preset flow rate setting value of 8.43t / h, and if there is a deviation, the frequency of the inverter of the cold salt pump is adjusted so that the actual flow rate returns to the setting value.

6. A low temperature heat supply molten salt energy storage dynamic adjustment control method according to claim 4, characterized in that, The method of dynamically adjusting the output power based on real-time monitoring of the molten salt temperature at the outlet of the molten salt electric heater is as follows: the molten salt temperature at the outlet of the molten salt electric heater is measured in real time by a thermocouple and fed back to the DCS system; the DCS system compares the measured temperature value with a high temperature target value of 350°C, and if it is lower than the target value, the output power of the molten salt electric heater is increased; if it is higher than the target value, the output power is decreased.

7. The method for dynamic regulation and control of low-temperature heating molten salt energy storage according to claim 1, characterized in that, In step S3, the peak power period heat release and heating control specifically includes: starting the hot salt pump to transport high-temperature molten salt at a temperature of approximately 350°C from the hot salt tank to the molten salt evaporator; the high-temperature molten salt releases heat in the molten salt evaporator to heat the water supply; the actual temperature of the water supply outlet is measured in real time by a temperature sensor installed on the water supply pipeline and fed back to the DCS system; the DCS system compares the actual temperature value with the target water supply temperature value of 50°C, and adjusts the frequency of the inverter of the hot salt pump according to the comparison result to change the flow rate of the high-temperature molten salt, thereby controlling the water supply outlet temperature at 48-52°C.

8. The method for dynamic regulation and control of low-temperature heating molten salt energy storage according to claim 1, characterized in that, In step S3, the peak power period heat release and heating control also includes: continuously monitoring the water level in the molten salt evaporator through a differential pressure level gauge and feeding it back to the DCS system; if the water level measurement value is lower than the preset minimum safe water level, the DCS system controls the start of the water replenishment pump to replenish water to the molten salt evaporator until the water level returns to the normal range.

9. The method for dynamic regulation and control of low-temperature heating molten salt energy storage according to claim 1, characterized in that, In step S4, the key system parameters include molten salt temperature, molten salt flow rate, system pressure, molten salt tank level, molten salt evaporator water level and temperature; the safety threshold and interlock protection actions include at least: When the molten salt temperature is detected to be below 142℃ or above 450℃, the first level of interlock is executed: the DCS system stops the operation of the molten salt electric heater. When the system pressure is detected to exceed the normal operating range of 0.5MPa to 1MPa, the second-level interlock is executed: the DCS system stops the operation of the cold salt pump and the hot salt pump; When the pressure in the molten salt pipeline exceeds 2MPa, the third-level interlock is activated: the DCS system controls the opening of the pipeline pressure relief valve; When the temperature of the molten salt in the molten salt tank remains below 150°C for 10 minutes, the fourth level of interlock is activated: the DCS system automatically starts the electric heater of the molten salt tank to intervene and raise the temperature.

10. The method for dynamic regulation and control of low-temperature heating molten salt energy storage according to claim 1, characterized in that, In step S5, the step of dynamically adjusting the heating power of the electric heat tracing device for the corresponding section based on the wall temperature measurement value is as follows: the DCS system compares the wall temperature measurement values ​​of key points in the molten salt pipeline collected at regular intervals with the anti-condensation temperature threshold of 170°C. If the wall temperature measurement value of any key point is lower than the anti-condensation temperature threshold, the heating power of the electric heat tracing device for the corresponding pipe section is increased.

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