A molten salt electric heating system with both enhanced heat transfer and precise temperature control

Abstract

The application discloses a molten salt electric heating system with the functions of heat transfer strengthening and precise temperature control, and particularly relates to the field of molten salt energy storage technology, and comprises an initial optimization module, a structural support module, a data monitoring module, a dynamic adjustment module, a precise control module, a global balance module and a safety guarantee module. The initial optimization module is used for pretreating molten salt entering the heating system, removing impurities and gases interfering with heat transfer, and calibrating initial parameters and calculating an initial heat transfer reference coefficient based on physical properties of the molten salt to determine the pretreatment qualification. The safety guarantee module is used for starting a protection mechanism for abnormal states and correcting heat transfer parameters based on real-time data to adapt to changes in the molten salt and equipment states. Through molten salt pretreatment and parameter calibration, the application obtains a stable initial molten salt state and a clear heat transfer capacity reference, and solves the problem of poor heat transfer stability caused by fluctuations in the initial state of the molten salt.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of molten salt energy storage, more particularly, to a molten salt electric heating system with enhanced heat transfer and precise temperature control. BACKGROUND

[0002] Molten salt electric energy storage technology is one of the core technologies to realize large-scale consumption of new energy and grid peak regulation. It converts off-peak electricity or green electricity into heat energy and stores it in molten salt through electric heating elements, which has become the mainstream direction in the global energy storage field.

[0003] In the heating technology of existing molten salt electric energy storage systems, the mainstream scheme uses fixed straight pipes or U-shaped pipe electric heating elements. The advantages are simple structure, controllable cost, and can realize basic electric energy-thermal energy conversion. However, there are significant limitations in the molten salt electric energy storage scenario: first, the heat transfer mode depends on the natural state of the molten salt, the heat transfer coefficient between the element surface and the molten salt is low, and the heat distribution is uneven, which easily forms a heat accumulation area, leading to local degradation of the molten salt and shortening the service life of the heat storage medium; second, the temperature control strategy is based on the single path adjustment of the overall temperature of the molten salt, without considering the dynamic heat transfer coupling between the heating element and the molten salt, resulting in a large temperature fluctuation range and difficulty in meeting the stringent requirements of the energy storage system for the temperature stability of the molten salt. SUMMARY

[0004] In order to overcome the above-mentioned defects of the prior art, the present application provides a molten salt electric heating system with enhanced heat transfer and precise temperature control, which solves the problems of uneven heat transfer, temperature control lag and non-adaptation to molten salt state changes in the prior art through the following scheme.

[0005] To achieve the above-mentioned purpose, the present application provides the following technical scheme: a molten salt electric heating system with enhanced heat transfer and precise temperature control, comprising:

[0006] An initial optimization module: pretreats the molten salt entering the heating system, removes impurities and gases that interfere with heat transfer, and calibrates initial parameters and calculates initial heat transfer reference coefficients based on the physical properties of the molten salt to determine the pretreatment eligibility;

[0007] A structural support module: structured molten salt electric energy storage design, optimized heat transfer effect through heat transfer enhancement coefficient calculation;

[0008] A data monitoring module: builds a three-level monitoring network, real-time acquisition of key parameters, and establishment of real-time state matrix of each layer;

[0009] A dynamic adjustment module: calculates the heat transfer temperature difference and heat transfer path influence coefficient based on the monitoring data, and adjusts the real-time heat transfer coefficient according to the heat transfer temperature difference and heat transfer path influence coefficient;

[0010] Precise control module: based on target temperature and real-time data, construct a hierarchical temperature control model to achieve precise control of temperature;

[0011] Global balance module: aggregate data from each layer to calculate global parameters, and achieve global balance of heat transfer efficiency and temperature stability through collaborative adjustment strategy;

[0012] Safety assurance module: start protection mechanism for abnormal state, and correct heat transfer parameters based on real-time data to adapt to the change of molten salt and equipment state.

[0013] Preferably, the pretreatment includes two-stage filtration and vacuum degassing; the two-stage filtration uses two-stage metal filter screen; the vacuum degassing uses a vacuum degassing device; the calibrated initial parameters: at the outlet of the pretreatment, a detection unit is provided to collect initial parameters including initial temperature , initial viscosity , initial thermal conductivity , and initial conveying speed ; the calculation of the initial heat transfer reference coefficient: the collected initial parameters are calculated to obtain the initial heat transfer reference coefficient representing the initial heat transfer capacity; the pretreatment eligibility: when ≥ is qualified, when is unqualified, indicating that the molten salt circulation state is poor, and the molten salt needs to be pretreated again, wherein represents the initial heat transfer reference coefficient threshold.

[0014] Preferably, the structured molten salt electric energy storage design: 3 layers of staggered arrangement of finned heating pipes, 6 heating pipes per layer; wherein, the pipe diameter of a single heating pipe d; the fin is spiral, the height h, the pitch s; the hierarchical spacing is used: the upper layer center spacing , the middle layer spacing , and the lower layer spacing ; a power unit is provided: independent power adjustment for each layer, with a single reference power ; a conveying plate is provided below each layer of heating pipes, wherein the inclination angle of the upper layer , the middle layer , and the lower layer ; and the effective heat transfer enhancement coefficient of each layer is calculated , wherein, represents the inclination angle of the nth layer conveying plate.

[0015] Preferably, the three-level monitoring network includes point monitoring, area monitoring, and domain monitoring; the point monitoring: 3 infrared temperature sensors are arranged on the surface of each heating pipe along the axial direction to collect the surface temperature of the heating pipe ; the area monitoring: 3 temperature inspection points are arranged in each heating area to collect the molten salt temperature using armored thermocouples Record the conveyor speed at each floor's entrance / exit. / Pressure sensor collects pressure / The domain monitoring system includes an online viscometer and a laser thermal conductivity meter installed at the system outlet to monitor the current viscosity and thermal conductivity of the molten salt in real time. The monitoring point is located 5m downstream of the outlet. A real-time status parameter matrix for each layer is established. ,in, This indicates the average surface temperature of the heating element in this layer.

[0016] Preferably, the heat transfer temperature difference The heat transfer path influence coefficient ,in, Indicates the center-to-center spacing of the upper heating elements. This represents the center-to-center spacing of the nth layer of heating tubes; the method for adjusting and optimizing the real-time heat transfer coefficient is as follows: when the heat transfer temperature difference... Temperature difference greater than the heat transfer temperature threshold: Adjust the angle of the conveyor plate. Increase When the heat transfer path influence coefficient Less than the heat transfer path influence coefficient threshold: Adjust the molten salt quantity via the inlet valve. Increased to 1.2 times the original capacity, and reduced the spacing between heating elements. 0.05m; the real-time heat transfer coefficient was calculated after adjustment and optimization. ,in, This indicates the current thermal conductivity of the molten salt. This represents the effective heat transfer enhancement coefficient of the nth layer.

[0017] Preferably, the layered temperature control model includes layered temperature deviation calculation, layered safety factor calculation, layered power adjustment factor calculation, and layered power execution; the layered temperature deviation calculation involves setting a target temperature Tt and calculating the temperature deviation for each layer. At the same time, when A value >0 indicates that the molten salt temperature is higher than the target, and the model reduces the heating power for that layer; when... A value less than 0 indicates that the molten salt temperature is lower than the target, and the model increases the heating power for that layer. The layer safety factor calculation involves calculating the safety factor for the temperature difference between the heating element and the molten salt. Simultaneously, when the safety factor for the temperature difference between the heating element and the molten salt is less than the threshold value, the model forcibly limits the power of that layer to prevent local overheating of the heating element; the layer power adjustment coefficient is calculated by calculating the power adjustment coefficient for each layer. The layered power execution involves calculating the actual output power of each layer. ,in, This represents the effective heat transfer enhancement coefficient for each layer. represents the heating tube reference power, and there is a constraint condition: if is greater than the temperature deviation threshold value, is reduced by 15%, if <1.2, is forcibly reduced by 20%.

[0018] Preferably, the global parameter calculation includes system heat transfer uniformity coefficient calculation and system temperature uniformity coefficient calculation; the system heat transfer uniformity coefficient calculation calculates the system heat transfer uniformity coefficient representing the consistency of heat transfer of each layer , wherein, respectively represent the real-time heat transfer coefficients of the upper, middle and lower layers, represents the maximum real-time heat transfer coefficient among the three layers, represents the minimum real-time heat transfer coefficient among the three layers; the system temperature uniformity coefficient calculation calculates the system temperature uniformity coefficient representing the overall temperature stability , wherein, respectively represent the molten salt temperatures of the upper, middle and lower layers, represents the maximum molten salt temperature among the three layers, represents the minimum molten salt temperature among the three layers, and Tt represents the target temperature; the cooperative regulation strategy includes: if <0.85: increasing the lower layer vibration frequency while reducing the upper layer power; if U<0.95: adjusting the middle layer power; if <0.85 and U<0.95: preferentially increasing the lower layer heat transfer coefficient while increasing the middle layer power by 10%.

[0019] Preferably, the protection mechanism includes local overheating protection, scaling blockage processing and state adaptive correction; the local overheating protection: when the heating tube surface temperature is greater than the temperature threshold value, immediately reduce the power of the corresponding layer to 30%, start the cooling fan, and at the same time increase the molten salt conveying speed by 0.3 m / s; the scaling blockage processing: when the molten salt outlet pressure is greater than the pressure threshold value, adjust the ultrasonic wave scale removal unit; if the pressure is still greater than the pressure threshold value after 30 seconds , trigger local flushing; the state adaptive correction: update the initial heat transfer reference coefficient every 30 minutes or when the real-time heat transfer capacity factor deviates from the historical reference by more than 15%, update the initial heat transfer reference coefficient using a weighted fusion algorithm , wherein, represents the initial heat transfer reference coefficient after the last period correction, represents the current real-time heat transfer capacity factor, , represents the dynamic weight, and after updating as a new benchmark, synchronously correct the heat transfer path influence coefficient calculation benchmark of the dynamic adjustment module and the power adjustment coefficient initial threshold value of the precision control module; if , the initial value of the vibration frequency of the dynamic adjustment module is increased by 5 Hz, and the lower limit value of the power adjustment coefficient of the precision control module is increased by 10%, to compensate for the loss of heat transfer efficiency.

[0020] Technical effects and advantages of the present application:

[0021] 1. The present application obtains stable initial molten salt state and clear heat transfer capacity benchmark through molten salt pretreatment and parameter calibration, solves the problem of poor heat transfer stability caused by initial state fluctuation of molten salt, and achieves the benefits of ensuring consistent heat transfer in subsequent heating process and reducing local heat transfer imbalance caused by initial state difference; through structured molten salt electric energy storage design, the heat transfer structure suitable for molten salt and enhanced heat transfer area uniformity are obtained, solving the problem of insufficient heat transfer area and low efficiency of traditional heating structure, and achieving the benefits of improving total heat transfer area, stabilizing heat transfer coefficient and reducing the formation of heat accumulation area.

[0022] 2. The present application obtains real-time parameter acquisition data covering point-surface-domain through distributed monitoring network deployment, solves the problem of single monitoring dimension and lack of heat transfer and temperature control data support, and provides accurate data basis for subsequent adjustment; through dynamic heat transfer strengthening adjustment, balanced heat transfer state and elimination of heat transfer dead zone are obtained, solving the problem of low heat transfer efficiency caused by natural dependence and large local heat transfer resistance, and achieving the benefits of small local temperature difference of molten salt and avoiding molten salt degradation caused by uneven heat transfer.

[0023] 3. The present application obtains heating power output matching the state of molten salt and stable temperature control effect through hierarchical precise temperature control algorithm, solves the problem of temperature control depending on single-point feedback, adjustment lag and large temperature fluctuation, and achieves the benefits of small temperature fluctuation, short adjustment response time and avoiding the decline of molten salt stability caused by temperature fluctuation; through system collaborative optimization, the overall balanced heat transfer efficiency and temperature uniformity are obtained, solving the problem of low system efficiency caused by lack of global adjustment logic and disconnection between local adjustment and overall demand, ensuring the energy utilization efficiency of the whole system; through safety feedback and adaptive correction, the rapid response to abnormal state and the adjustment parameters adapting to the change of molten salt state are obtained, solving the problem of poor system safety caused by not considering molten salt degradation, equipment fouling and other problems in long-term operation, prolonging the service life of the equipment, improving the energy conversion rate and reducing the cost loss caused by abnormal shutdown. BRIEF DESCRIPTION OF DRAWINGS

[0024] Figure 1 It is a schematic diagram of the overall structure of the present application. DETAILED DESCRIPTION ​

[0025] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by a person of ordinary skill in the art without creative effort belong to the protection scope of the present application.

[0026] As shown in the accompanying drawings Figure 1 , a molten salt electric heating system with the functions of heat transfer enhancement and precise temperature control comprises an initial optimization module, a structural support module, a data monitoring module, a dynamic adjustment module, a precise control module, a global balance module and a safety guarantee module.

[0027] The initial optimization module: pretreats the molten salt entering the heating system, removes impurities and gases interfering with heat transfer, and calibrates initial parameters and calculates initial heat transfer reference coefficients based on the physical properties of the molten salt to determine the pretreatment eligibility.

[0028] Specifically, the pretreatment includes two-stage filtration and vacuum degassing; the two-stage filtration uses two-stage metal filter screens; the vacuum degassing uses a vacuum degassing device; the calibration of initial parameters: a detection unit is provided at the outlet of the pretreatment to collect initial parameters including initial temperature , initial viscosity , initial thermal conductivity and initial conveying speed ; the calculation of initial heat transfer reference coefficients: the collected initial parameters are calculated to obtain the initial heat transfer reference coefficients characterizing the initial heat transfer capacity, where the thermal conductivity and the conveying speed are the core parameters promoting heat transfer, and the viscosity and the temperature are the parameters hindering heat transfer. The numerator is the product of the promoting factors, and the denominator is the product of the hindering factors, which can effectively characterize the initial heat transfer capacity of the molten salt logically; the pretreatment eligibility is based on the basic law that the thermal conductivity x the conveying speed is positively correlated with the heat transfer capacity, and the viscosity x the temperature is negatively correlated with the heat transfer resistance; when ≥ , it is eligible, and when , it is unqualified, indicating that the molten salt circulation state is poor and needs to be pretreated again, where The initial heat transfer reference coefficient threshold is represented. It can be understood that: solid impurities (such as particles, metal debris) in the molten salt will adhere to the surface of the heating pipe to form a heat transfer resistance layer, and dissolved gas (such as air, water vapor) will form bubbles during heating, which will seriously reduce the heat transfer efficiency. In addition, the fluctuation of the initial state (viscosity, thermal conductivity) of the molten salt will cause the heat transfer performance to be unstable, and the reference needs to be determined through parameter calibration. The heat transfer interference factors are removed through filtration and degassing, and the quantitative reference of the initial heat transfer capacity is established through parameter calibration, which avoids the problem of blindness in subsequent adjustment caused by unknown initial state, and provides stable conditions for the entire heating process.

[0029] The structural support module: structured molten salt electric energy storage design, the heat transfer enhancement coefficient is calculated to optimize the heat transfer effect;

[0030] Specifically, the structured molten salt electric energy storage design: 3 layers of staggered finned heating pipes, 6 heating pipes per layer; wherein the pipe diameter of a single heating pipe is d; the fin is spiral, the height is h, and the pitch is s; the layer spacing is: the center spacing of the upper layer is , the center spacing of the middle layer is , and the center spacing of the lower layer is ; set the power unit: independent power adjustment for each layer, the reference power of a single pipe is ; a conveying plate is arranged below each layer of heating pipes, wherein the inclination angle of the upper layer is , the inclination angle of the middle layer is , and the inclination angle of the lower layer is ; and the effective heat transfer enhancement coefficient of each layer is calculated , wherein, , the first term is the correction of the heat transfer area increased by the fin, and the second term is the enhancement correction of the conveying plate; the first term: the greater the fin height and the smaller the pitch, the more significant the increase in heat transfer area (2h / s is the simplified calculation coefficient of the additional area of the fin), and the physical meaning is the enhancement effect of the fin on the heat transfer area; the second term: increases with the increase of the angle , and the physical meaning is the enhancement effect of the conveying plate angle on the molten salt transmission; the multiplication of the two terms can comprehensively represent the synergistic heat transfer enhancement effect of the fin + conveying plate, which conforms to the law that heat transfer area and transmission state jointly determine heat transfer efficiency. It can be understood that: the traditional heating unit adopts a single group of straight pipes + no guiding structure, which has two defects: one is the insufficient heat transfer area (only the pipe body area), and the other is the disordered molten salt transmission. Through the optimization of layer spacing, fin parameters and conveying angle, the heat transfer area and transmission uniformity can be improved at the same time; through the structural design, the inherent defects of the traditional heating unit are solved from the hardware level, and the heat transfer area and the molten salt transmission path are adapted, which provides a structural basis for subsequent dynamic adjustment.

[0031] The data monitoring module: constructs a three-level monitoring network, collects key parameters in real time, and establishes a real-time state matrix of each layer;

[0032] Specifically, the three-level monitoring network includes point monitoring, surface monitoring, and domain monitoring; the point monitoring: three infrared temperature sensors are arranged on the surface of each heating pipe along the axial direction to collect the surface temperature of the heating pipe ; the surface monitoring: three temperature inspection points are arranged in each heating area to collect the molten salt temperature by using armored thermocouples ; the inlet / outlet of each layer records the conveying speed / , and a pressure sensor collects the pressure / , which is installed in a straight pipe section (to ensure stable pressure); the domain monitoring: an online viscosity meter and a laser heat conduction instrument are arranged at the outlet of the system to detect the current viscosity and heat conduction coefficient of the molten salt in real time, wherein the monitoring point is arranged 5 m behind the outlet (in the uniform mixing area of the molten salt); a real-time state parameter matrix of each layer is established to provide a standardized data carrier for subsequent calculation and adjustment, wherein represents the average temperature of the heating pipe surface of this layer. It can be understood that the regulation of heat transfer efficiency and temperature control accuracy depends on real-time data feedback, and traditional single-point temperature measurement + experience-based judgment has two problems: one is insufficient data dimension (only the molten salt temperature is measured, and key parameters such as heating pipe temperature and conveying speed are lacking), and the other is incomplete spatial coverage. Based on the point-surface-domain three-level monitoring logic, comprehensive and accurate collection of key parameters can be realized; through distributed monitoring, the blindness of traditional regulation is solved from the data level, and quantitative basis is provided for heat transfer intensification, temperature control algorithm, and safety feedback.

[0033] The dynamic adjustment module: calculates the heat transfer temperature difference and the heat transfer path influence coefficient based on the monitoring data, and adjusts and optimizes the real-time heat transfer coefficient according to the heat transfer temperature difference and the heat transfer path influence coefficient;

[0034] Specifically, the heat transfer temperature difference (the temperature difference between the heating pipe and the molten salt, which drives the heat transfer) and the heat transfer path influence coefficient , wherein represents the center distance of the upper heating pipe, represents the center distance of the nth layer of heating pipe, the first term : the speed change rate, when the outlet conveying speed is greater than the inlet, it indicates that the molten salt is heated or the structural disturbance is enhanced (such as fins, conveying plates), and the physical meaning is the basic strength of the influence; the second term : the distance correction coefficient, the lower layer distance The smaller, the larger the correction coefficient, the physical meaning is the magnification of the lower layer more dense spacing; the multiplication of the two can quantify the promotion effect on heat transfer; the said adjustment optimizes the real-time heat transfer coefficient mode: when the heat transfer temperature difference is greater than the heat transfer temperature difference threshold, that is, the heat transfer resistance is large: adjust the conveying plate angle increase ( increase , based on angle increase can improve the conveying speed by 5%); when the heat transfer path influence coefficient is less than the heat transfer path influence coefficient threshold: adjust the amount of molten salt through the inlet valve, to 1.2 times the original, and reduce the heating tube spacing 0.05m (to avoid blockage); adjust and optimize the calculation of the said real-time heat transfer coefficient , wherein represents the current molten salt thermal conductivity, represents the effective heat transfer enhancement coefficient of the nth layer, and the heat transfer coefficient is the core parameter for measuring heat transfer efficiency, which is jointly determined by , , , Four multiplications can comprehensively quantify the real-time heat transfer efficiency. It can be understood that: during the heating process, the state of the molten salt and the heat transfer temperature difference will change with time (such as local conveying speed reduction leading to heat transfer efficiency drop, or excessive temperature difference forming heat aggregation), which needs to be dynamically adjusted based on real-time data. Based on the principle that heat transfer coefficient is positively correlated with conveying speed and disturbance in heat transfer, the heat transfer efficiency can be improved by adjusting vibration, angle and spacing; through dynamic adjustment, the problem that static structure cannot adapt to dynamic heat transfer demand is solved from the process level, and heat transfer bottleneck is eliminated in real time to maintain efficient heat transfer.

[0035] The said precise control module: based on the target temperature and real-time data, a layered temperature control model is constructed to realize layered precise temperature control;

[0036] It needs to be specifically pointed out that: the said layered temperature control model includes layered temperature deviation calculation, layered safety factor calculation, layered power regulation coefficient calculation and layered power execution; the said layered temperature deviation calculation: set the target temperature Tt, calculate the temperature deviation of each layer , at the same time, when >0, it means that the molten salt temperature is higher than the target, and the model reduces the heating power of this layer, and the calculation of the temperature deviation clearly shows the difference between the actual temperature and the target of each layer, which provides a directional basis for power regulation (positive deviation needs to reduce power, negative deviation needs to increase power); when <0, it means that the molten salt temperature is lower than the target, and the model increases the heating power of this layer; the said layered safety factor calculation: calculates the heating tube-molten salt temperature difference safety factor Meanwhile, when the heating tube-molten salt temperature difference safety factor is less than the heating tube-molten salt temperature difference safety factor threshold, the model forcibly limits the power of the layer to avoid local overheating of the heating tube. The numerator is the safety margin of the heating tube from the target temperature, which needs to be greater than or equal to 0 (otherwise, the heating tube temperature exceeds the target, which can cause the molten salt to overheat); the denominator is the temperature difference between the heating tube and the molten salt, which is the heat transfer driving force (needs to be greater than or equal to 0, otherwise there is no heat transfer); the ratio of the safety margin to the heat transfer driving force is greater than or equal to the heating tube-molten salt temperature difference safety factor threshold, which can ensure that the surface temperature of the heating tube does not exceed the stable temperature of the molten salt, avoiding local overheating, and meeting the temperature control logic of balancing the heat transfer driving force and the safety margin. The introduction of the safety factor avoids sacrificing safety in pursuit of the target temperature (such as when the molten salt temperature does not meet the standard but the heating tube is already overheated, the power is forcibly limited); the calculation of the layered power adjustment coefficient: calculate the power adjustment coefficient of each layer The dynamic calculation of the power adjustment coefficient (related to the deviation, safety factor, and conveying speed) realizes the dynamic matching of the power and the heat transfer demand. The term is a temperature deviation correction. When the temperature is too high , the exponential term decreases, which reduces the power; when the temperature is too low, the exponential term increases, which increases the power, and the larger the deviation, the stronger the adjustment according to the temperature control logic. The term is a safety correction. The larger the safety factor (the more sufficient the safety margin), the larger the term (which can appropriately increase the power) to avoid excessive heating when the safety margin is insufficient; the layered power execution: calculate the actual output power of each layer , where represents the effective heat transfer enhancement coefficient of each layer, represents the reference power of the heating tube, and there is a constraint condition: if is greater than the temperature deviation threshold, reduce by 15%, if <1.2, forcibly reduce by 20%. It can be understood that: the traditional temperature control uses a single-point temperature-power simple feedback, which has two major defects: one is the adjustment lag (only based on the molten salt temperature, without considering the dynamic heat transfer characteristics of the heating tube and the molten salt), and the other is the lack of safety constraints (easy to cause local overheating of the heating tube due to excessive power). The algorithm based on layered temperature deviation and safety threshold can achieve the dual goals of precise adjustment and safety constraints, and solve the lag and overheating risk of traditional temperature control from the control level through the layered algorithm, realizing precise and stable control of temperature (the temperature control accuracy directly affects the stability of the molten salt and the energy storage efficiency).

[0037] The global balance module: aggregate data of each layer for global parameter calculation, realize global balance of heat transfer efficiency and temperature stability through cooperative regulation strategy;

[0038] Specifically, the global parameter calculation includes system heat transfer uniformity coefficient calculation and system temperature uniformity coefficient calculation; the system heat transfer uniformity coefficient calculation: calculate the system heat transfer uniformity coefficient representing the consistency of heat transfer of each layer , wherein, respectively represent the real-time heat transfer coefficients of the upper, middle and lower layers, represent the maximum real-time heat transfer coefficient in the three layers, represent the minimum real-time heat transfer coefficient in the three layers, the formula has the physical meaning that 1-the maximum difference of heat transfer coefficient and the maximum value, the smaller the difference (the more uniform the heat transfer of each layer), the closer to 1 (≥0.85 is qualified). The conventional method of quantifying the maximum deviation ratio (such as standard deviation, range rate) is required to meet the uniformity evaluation, which can effectively represent the consistency of the overall heat transfer of the system; the system temperature uniformity coefficient calculation: calculate the system temperature uniformity coefficient representing the overall temperature stability , wherein, respectively represent the molten salt temperatures of the upper, middle and lower layers, represent the maximum molten salt temperature in the three layers, represent the minimum molten salt temperature in the three layers, Tt represents the target temperature, the formula has the physical meaning that 1-the maximum difference of temperature and the target temperature, the smaller the difference (the closer the temperature of each layer), the closer to 1 (≥0.95 is qualified). The temperature control logic that meets the temperature uniformity requires to judge the deviation rationality in combination with the target temperature; the cooperative regulation strategy includes: if <0.85 (heat transfer is not uniform): increase the vibration frequency of the lower layer (increase by 5 Hz, based on the higher weight of the lower layer heat transfer), while reducing the power of the upper layer; if U<0.95 (temperature is not uniform): adjust the power of the middle layer (±8%, the middle layer is the heat transfer bridge of the upper and lower layers, adjusting the middle layer can quickly balance the temperature difference); if <0.85 and U<0.95 (double abnormality): preferentially increase the heat transfer coefficient of the lower layer (increase to , ensure the efficiency of the core heating area), while the power of the middle layer is increased by 10% (balance the temperature). It can be understood that: layered regulation may lead to local optimization but global imbalance (such as the heat transfer efficiency of a certain layer is improved but the overall heat transfer is not uniform, or the temperature of a certain layer meets the standard but the overall temperature difference is too large). Based on the cooperative regulation of global heat transfer uniformity and temperature uniformity, the unity of local regulation and global target can be realized. Through system cooperation, the limitations of layered regulation are solved from the global level, ensuring the overall optimization of heat transfer efficiency and temperature control accuracy (avoiding the performance decline caused by local optimization). The heat transfer uniformity coefficient The calculation of the temperature uniformity coefficient U quantifies the global performance (avoiding subjective judgment); [This is related to...] Adjusting for heat transfer unevenness (U < 0.85) by increasing the disturbance in the lower layer and reducing the power in the upper layer guides the molten salt to the weak heat transfer area, reducing the deviation of the heat transfer coefficient between layers to within 15%; adjusting for temperature unevenness (U < 0.95) by adjusting the power in the middle layer utilizes the heat transfer bridge effect of the middle layer to quickly balance the temperature between the upper and lower layers, reducing the temperature difference of the molten salt between layers to within 3% × Tt; the priority strategy in case of dual anomalies (ensuring the core heating area of ​​the lower layer) ensures the stability of the core performance of the system under complex operating conditions.

[0039] The safety protection module activates a protection mechanism for abnormal conditions and corrects heat transfer parameters based on real-time data to adapt to changes in molten salt and equipment status.

[0040] Specifically, it should be noted that the protection mechanism includes local overheat protection, scaling and blockage treatment, and adaptive state correction; the local overheat protection: when the surface temperature of the heating tube... When the temperature exceeds the threshold, immediately reduce the power of the corresponding layer to 30%, turn on the cooling fan, and simultaneously increase the molten salt conveying speed of that layer by 0.3 m / s; Regarding the scaling and clogging treatment: when the molten salt outlet pressure... If the pressure exceeds the threshold, adjust the ultrasonic descaling unit; if after 30 seconds... If the pressure remains above the threshold, local flushing is triggered; the state adaptive correction involves updating the initial heat transfer reference coefficient every 30 minutes, or updating the initial heat transfer reference coefficient using a weighted fusion algorithm when the real-time heat transfer capacity factor deviates from the historical reference by more than 15%. ,in, This represents the initial heat transfer reference coefficient after correction in the previous cycle. This represents the current real-time heat transfer capacity factor. , Indicates dynamic weights, after update As a new benchmark, the calculation benchmark for the heat transfer path influence coefficient of the dynamic adjustment module and the initial threshold for the power adjustment coefficient of the precision control module are simultaneously revised; if < If so, the initial value of the vibration frequency of the dynamic adjustment module is increased by 5 Hz, and the lower limit value of the power adjustment coefficient of the precision control module is increased by 10%, to compensate for the loss of heat transfer efficiency. It can be understood that: in long-term operation, the state of the molten salt (viscosity, thermal conductivity) will gradually change (such as long-term heating leading to degradation of molten salt), and sudden abnormalities may occur (such as overheating of the heating pipe, fouling of the pipeline). If there is a lack of real-time feedback and correction, it will lead to a continuous decline in efficiency and even damage to the equipment. Based on the safety mechanism of the molten salt and the characteristics of the equipment, abnormal early warning-quick response-state adaptation can be realized. Through safety feedback and adaptive correction, the state of sudden abnormality in long-term operation is solved from the security level, ensuring the safety, stability and long-term efficiency of the system (system life and long-term efficiency are the core indicators of industrial applications). Local overheating protection (reduce power, enhance heat dissipation) avoids damage to the heating pipe due to overheating (the cost of replacing the heating pipe accounts for more than 30% of the total maintenance cost of the equipment), while preventing the degradation of molten salt due to overheating (molten salt degradation will reduce the heat transfer efficiency by 10%-15%) and fouling and blocking treatment (ultrasonic cleaning, flushing) to restore the pipeline transport capacity (fouling will increase the pressure loss by more than 50%, and the heat transfer efficiency will decrease by 20%); state adaptive correction (update the heat transfer benchmark coefficient) allows subsequent adjustment to adapt to changes in the state of the molten salt (such as after the viscosity of the molten salt increases, the heat transfer capacity is automatically corrected to avoid the disconnection between the adjustment parameters and the actual state), ensuring long-term efficient operation of the system.

[0041] Secondly, the present application discloses an embodiment of the drawings, only involves the structure related to the present disclosure, other structures can refer to the usual design, without conflict, the same embodiment and different embodiments of the present application can be combined with each other;

[0042] Finally, the above-mentioned is only the preferred embodiment of the present application, and is not used to limit the present application, any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application should be included in the protection scope of the present application.

Claims

1. A molten salt electric heating system that combines enhanced heat transfer and precise temperature control, characterized in that, include: Initial optimization module: Pre-treats the molten salt entering the heating system to remove impurities and gases that interfere with heat transfer, and calibrates the initial parameters and calculates the initial heat transfer reference coefficient based on the physical properties of the molten salt to determine the qualification of the pre-treatment. Structural support module: Structured molten salt electric energy storage design, optimizing heat transfer effect through heat transfer enhancement coefficient calculation; Data monitoring module: Constructs a three-level monitoring network, collects key parameters in real time, and establishes a real-time status matrix for each level; The three-tiered monitoring network includes point monitoring, area monitoring, and domain monitoring; the point monitoring involves installing three infrared temperature sensors along the axial direction on the surface of each heating tube to collect the surface temperature of the heating tube. The surface monitoring system includes three temperature monitoring points set up in each heating zone, using armored thermocouples to collect molten salt temperatures. Record the conveyor speed at each floor's entrance / exit. / Pressure sensor collects pressure / The domain monitoring system includes an online viscometer and a laser thermal conductivity meter installed at the system outlet to monitor the current viscosity and thermal conductivity of the molten salt in real time. The monitoring point is located 5m downstream of the outlet. A real-time status parameter matrix for each layer is established. ,in, This indicates the average surface temperature of the heating element in this layer; Dynamic adjustment module: Calculates the heat transfer temperature difference and heat transfer path influence coefficient based on monitoring data, and adjusts and optimizes the real-time heat transfer coefficient according to the heat transfer temperature difference and heat transfer path influence coefficient; The heat transfer temperature difference The heat transfer path influence coefficient ,in, Indicates the center-to-center spacing of the upper heating elements. This represents the center-to-center spacing of the nth layer of heating tubes; the method for adjusting and optimizing the real-time heat transfer coefficient is as follows: when the heat transfer temperature difference... Temperature difference greater than the heat transfer temperature threshold: Adjust the angle of the conveyor plate. Increase When the heat transfer path influence coefficient Less than the heat transfer path influence coefficient threshold: Adjust the molten salt quantity via the inlet valve. Increased to 1.2 times the original capacity, and reduced the spacing between heating elements. 0.05m; the real-time heat transfer coefficient was calculated after adjustment and optimization. ,in, This indicates the current thermal conductivity of the molten salt. This represents the effective heat transfer enhancement coefficient of the nth layer; Precision control module: Based on the target temperature and real-time data, a layered temperature control model is built to achieve layered precise temperature control; The layered temperature control model includes layered temperature deviation calculation, layered safety factor calculation, layered power adjustment factor calculation, and layered power execution; the layered temperature deviation calculation involves setting a target temperature Tt and calculating the temperature deviation for each layer. At the same time, when A value >0 indicates that the molten salt temperature is higher than the target, and the model reduces the heating power for that layer; when... A value less than 0 indicates that the molten salt temperature is lower than the target, and the model increases the heating power for that layer. The layer safety factor calculation involves calculating the safety factor for the temperature difference between the heating element and the molten salt. Simultaneously, when the safety factor for the temperature difference between the heating element and the molten salt is less than the threshold value, the model forcibly limits the power of that layer to prevent local overheating of the heating element; the layer power adjustment coefficient is calculated by calculating the power adjustment coefficient for each layer. The layered power execution involves calculating the actual output power of each layer. ,in, This represents the effective heat transfer enhancement coefficient for each layer. This represents the reference power of the heating element, and there are constraints: if Greater than the temperature deviation threshold Reduce by 15%, if <1.2, Forced reduction of 20%; Global balance module: It aggregates data from each layer to calculate global parameters and achieves a global balance between heat transfer efficiency and temperature stability through a coordinated adjustment strategy. Safety protection module: It activates protection mechanisms for abnormal conditions and corrects heat transfer parameters based on real-time data to adapt to changes in molten salt and equipment status.

2. The molten salt electric heating system according to claim 1, characterized in that: The pretreatment includes two-stage filtration and vacuum degassing; the two-stage filtration uses two-stage metal mesh filters; the vacuum degassing uses a vacuum degassing device; the initial parameters are calibrated by setting up a detection unit at the pretreatment outlet to collect initial parameters including initial temperature. Initial viscosity Initial thermal conductivity and initial conveying speed The calculation of the initial heat transfer reference coefficient: used to calculate the initial heat transfer reference coefficient characterizing the initial heat transfer capacity from the collected initial parameters. The pretreatment qualification: when ≥ To be qualified, when If the result is unsatisfactory, it indicates that the molten salt circulation is not in good condition and re-pretreatment is required. This represents the initial heat transfer reference coefficient threshold.

3. The molten salt electric heating system according to claim 1, characterized in that: The structured molten salt electric energy storage design employs three layers of staggered finned heating tubes, with six heating tubes per layer. The diameter of each heating tube is d; the fins are helical with a height h and a pitch s; and the layer spacing is as follows: the center-to-center spacing of the upper layer... Interlayer spacing lower layer spacing Power unit settings: independent power adjustment for each layer, single-strand reference power. A conveyor plate is installed below each layer of heating pipes, with the upper layer having an inclined angle. Middle layer lower level And calculate the effective heat transfer enhancement coefficient for each layer. ,in, This indicates the tilt angle of the nth layer conveyor plate.

4. The molten salt electric heating system according to claim 1, characterized in that: The global parameter calculation includes the calculation of the system heat transfer uniformity coefficient and the calculation of the system temperature uniformity coefficient; the calculation of the system heat transfer uniformity coefficient: calculating the system heat transfer uniformity coefficient that characterizes the heat transfer consistency of each layer. ,in, These represent the real-time heat transfer coefficients of the upper, middle, and lower layers, respectively. This represents the highest real-time heat transfer coefficient among the three layers. The minimum real-time heat transfer coefficient among the three layers is represented; the system temperature uniformity coefficient is calculated as follows: the system temperature uniformity coefficient, which characterizes the overall temperature stability, is calculated. ,in, These represent the temperatures of the upper, middle, and lower layers of molten salt, respectively. This indicates the highest molten salt temperature among the three layers. Tt represents the minimum molten salt temperature among the three layers, and Tt represents the target temperature; the coordinated regulation strategy includes: if <0.85: Increase the lower layer vibration frequency while decreasing the upper layer power; if U<0.95: Adjust the middle layer power; if <0.85 and U<0.95: Prioritize increasing the heat transfer coefficient of the lower layer, while increasing the power of the middle layer by 10%.

5. The molten salt electric heating system according to claim 1, characterized in that: The protection mechanism includes local overheat protection, scaling and blockage treatment, and adaptive state correction; the local overheat protection: when the surface temperature of the heating tube... When the temperature exceeds the threshold, immediately reduce the power of the corresponding layer to 30%, turn on the cooling fan, and simultaneously increase the molten salt conveying speed of that layer by 0.3 m / s; Regarding the scaling and clogging treatment: when the molten salt outlet pressure... If the pressure exceeds the threshold, adjust the ultrasonic descaling unit; if after 30 seconds... If the pressure remains above the threshold, local flushing is triggered; the state adaptive correction involves updating the initial heat transfer reference coefficient every 30 minutes, or updating the initial heat transfer reference coefficient using a weighted fusion algorithm when the real-time heat transfer capacity factor deviates from the historical reference by more than 15%. ,in, This represents the initial heat transfer reference coefficient after correction in the previous cycle. This represents the current real-time heat transfer capacity factor. , Indicates dynamic weights, after update As a new benchmark, the calculation benchmark for the heat transfer path influence coefficient of the dynamic adjustment module and the initial threshold for the power adjustment coefficient of the precision control module are simultaneously revised; if < If the initial value of the vibration frequency of the dynamic adjustment module is increased by 5Hz, the lower limit of the power adjustment coefficient of the precision control module is increased by 10% to compensate for the loss of heat transfer efficiency.

Images