Two-stage heat exchange control method and system for molten salt heating once-through steam generator

Abstract

The embodiment of the present application provides a kind of molten salt heating once-through steam generator two-stage heat exchange control method and system, belong to industrial heat transfer technical field.The method includes: collecting real-time heat supply demand information;Determine the heat supply path information in corresponding heat supply period;Based on the heat supply path information, construct joint optimization model, to generate the control scheme of the molten salt heating once-through steam generator two-stage heat exchange device based on the joint optimization model;Wherein, the joint optimization model includes coupled high-temperature molten salt flow distribution model and water temperature control model;The control scheme is executed, and the steam output information of the steam outlet of evaporator is monitored in real time, to control the steam output information of the steam outlet and heat supply path information real-time matching.The present application scheme realizes the dynamic coupling optimization of high-temperature molten salt flow distribution and water temperature control, effectively solves the problem of low heat exchange efficiency and insufficient heat supply path control precision in the prior art.

Description

Technical Field

[0001] This invention relates to the field of industrial heat transfer technology, specifically to a two-stage heat exchange control method and a two-stage heat exchange control system for a molten salt heated DC steam generator. Background Technology

[0002] In modern energy utilization and heating, molten salt is widely used in high-efficiency heat transfer and conversion systems due to its excellent heat transfer performance and high heat capacity. Molten salt-heated direct-flow steam generators, as a type of high-efficiency heating equipment, typically employ a two-stage heat exchange structure. Through a series-connected evaporator and heater, staged heat exchange between high-temperature molten salt and incoming water is achieved, thereby generating high-temperature steam of stable quality. This device has significant application value in industrial heating, solar power generation, and other fields. However, in practical applications, existing two-stage heat exchange control methods suffer from the following main technical problems:

[0003] 1) Insufficient optimization of heat exchange efficiency: In existing technologies, most only use simple fixed ratio flow distribution or preset inlet water temperature schemes, which are difficult to dynamically adapt to changes in heating demand, resulting in low molten salt heat exchange efficiency and insufficient energy utilization.

[0004] 2) Lack of precision in heating path control: Existing solutions typically plan heating paths based on static heating demand, failing to respond in real time to dynamic operating conditions (such as fluctuations in steam demand or changes in inlet water temperature), which can easily lead to fluctuations in steam quality and make it difficult to ensure the stability of the heating system.

[0005] 3) Insufficient model coupling: The flow distribution between the evaporator and the heater is highly coupled with the control of the incoming water temperature, but most existing control strategies are designed separately and fail to fully consider the mutual influence between the two, making it difficult to further improve the control accuracy and heating efficiency of the overall system.

[0006] 4) Insufficient safety and stability: In high-temperature molten salt operation, the dynamic adjustment of molten salt outlet temperature, inlet water temperature, and steam output status is crucial to ensuring the safe operation of the system. However, existing technologies lack a systematic joint optimization scheme, leading to risks such as low-temperature solidification of molten salt or steam overheating during operation.

[0007] To solve the above technical problems, a heat exchange control scheme needs to be proposed. Summary of the Invention

[0008] The purpose of this invention is to provide a two-stage heat exchange control method and system for a molten salt heated DC steam generator, so as to at least solve the problems of insufficient efficiency and accuracy of existing heat exchange control schemes.

[0009] To achieve the above objectives, the first aspect of the present invention provides a two-stage heat exchange control method for a molten salt heated direct-flow steam generator, applied to the control of the two-stage heat exchange device in the heating process of the molten salt heated direct-flow steam generator. The two-stage heat exchange device includes an evaporator and a heater connected in series, to achieve staged heat exchange of the high-temperature molten salt through convective heat exchange between the incoming water and the high-temperature molten salt. The evaporator and the heater are connected by a three-way valve to allow a portion of the original high-temperature molten salt and a portion of the high-temperature molten salt after heat exchange in the evaporator to flow into the heater. The method includes: responding to a heating request. The system collects real-time heating demand information; analyzes the heating demand information to determine the heating path information within the corresponding heating cycle; constructs a joint optimization model based on the heating path information, and generates a control scheme for the two-stage heat exchange device of the molten salt heated DC steam generator based on the joint optimization model; wherein, the joint optimization model includes a coupled high-temperature molten salt flow distribution model and an inlet water temperature control model; executes the control scheme, and monitors the steam output information of the evaporator's steam outlet in real time to control the real-time matching of the steam output information of the steam outlet with the heating path information.

[0010] Optionally, the heating demand information includes: heating cycle information and target temperature information at each time point; the step of parsing the heating demand information to determine the heating path information within the corresponding heating cycle includes: performing time series analysis within the heating cycle to decompose the target temperature information at each time point into heating demand at discrete time points; and determining the steam demand and steam temperature at each time point based on the transmission loss model of steam from the steam outlet of the evaporator to the target heating location, as heating path information.

[0011] Optionally, after decomposing the target temperature information at each time point into heating demand at discrete time points, the method further includes: performing a time-series arrangement of the heating demand at each time point, identifying outliers and missing points; performing correction processing on outliers, and performing filling processing on missing points, to obtain complete heating demand at each time point.

[0012] Optionally, the outlier identification rule is as follows: calculate the corresponding mean and standard deviation based on the heating demand at each time point; perform the three-standard-deviation method to identify outliers based on the heating demand at each time point and the corresponding mean and standard deviation; the processing rule for correcting outliers is as follows: perform correction processing on outliers based on the moving average method.

[0013] Optionally, both the evaporator and the heater are provided with a tortuous water pipe; the water pipes of the evaporator and the heater are connected, and the water flow direction is from the heater to the evaporator; the outlet of the water pipe of the evaporator is connected to the steam outlet of the evaporator.

[0014] Optionally, the construction rules of the joint optimization model are as follows: a high-temperature molten salt flow distribution model and an inlet water temperature control model are constructed based on the heating path information; corresponding model constraints are constructed based on system usage safety, and the high-temperature molten salt flow distribution model and the inlet water temperature control model are coupled based on the model constraints to obtain the joint optimization model.

[0015] Optionally, the construction rules for the high-temperature molten salt flow distribution model are as follows: initialize the inlet water temperature in the heater and evaporator, and define the inlet water temperature in the heater and evaporator as a constant value; use the inlet node of the high-temperature molten salt, the inlet node of the evaporator, the bypass node of the three-way valve, the outlet node of the evaporator, and the inlet node of the heater as the nodes of the flow model to construct the corresponding flow model; wherein, the edge flow of the flow model is the high-temperature molten salt flow distribution to the evaporator inlet node and the bypass node of the three-way valve, and the edge cost of the flow model is inversely proportional to the unit molten salt heat exchange efficiency; use the minimum cost maximum flow algorithm as the solution rule for the flow model to obtain the high-temperature molten salt flow distribution model.

[0016] Optionally, the constraints of the flow model are:

[0017]

[0018] The high-temperature molten salt flow distribution model is expressed as follows:

[0019]

[0020] in, The flow rate of the initial high-temperature molten salt allocated to the evaporator; The flow rate of the original high-temperature molten salt allocated to the three-way valve bypass; This represents the total flow rate of the original high-temperature molten salt; The heat exchange efficiency of the evaporator is determined based on a fixed evaporator inlet water temperature. The heat exchange efficiency of the heater is determined based on the inlet water temperature of the heater. Overall heat exchange efficiency.

[0021] Optionally, the rule for determining the evaporator heat exchange efficiency based on a fixed evaporator inlet water temperature is as follows:

[0022]

[0023] in, The specific heat capacity of molten salt; The temperature of the original high-temperature molten salt; The temperature of the molten salt after heat exchange is based on the inlet water temperature of the constant evaporator. The temperature of the molten salt at the outlet of the device.

[0024] Optionally, the rule for determining the heater heat exchange efficiency based on the constant heater inlet water temperature is as follows:

[0025]

[0026] in, The temperature of the mixed molten salt between the original high-temperature molten salt in the three-way valve bypass and the molten salt after heat exchange in the evaporator; The temperature of the molten salt after heat exchange is based on the inlet water temperature of the constant heater.

[0027] Optionally, the rules for solving the flow model based on the minimum cost maximum flow algorithm are as follows: the flow model is converted into a flow network, including evaporator flow, bypass flow, and heater inlet mixing temperature; flow conservation and cost functions are set; the goal is to maximize the total heat exchange efficiency, which is equivalent to minimizing the total flow cost; wherein the cost is inversely proportional to the efficiency of the evaporator and the heater; by finding the shortest cost path from the source node to the sink node, the flow allocation is gradually increased, and the flow allocation ratio of the evaporator and the bypass is adjusted until the optimal flow allocation rule is obtained.

[0028] Optionally, the construction rule for the inlet water temperature control model is as follows: the flow rate of the original high-temperature molten salt allocated to the evaporator and the three-way valve bypass is set to a constant value to obtain initial conditions; based on the initial conditions, the corresponding inlet water temperature control model is constructed, expressed as:

[0029]

[0030] in, Overall heat exchange efficiency; The specific heat capacity of molten salt; The temperature of the original high-temperature molten salt; The temperature of the molten salt after heat exchange is based on the inlet water temperature of the constant evaporator. The temperature of the molten salt at the outlet of the device; The temperature of the mixed molten salt between the original high-temperature molten salt in the three-way valve bypass and the molten salt after heat exchange in the evaporator; The temperature of the molten salt after heat exchange is based on the inlet water temperature of the constant heater.

[0031] Optionally, the solution rule for the inlet water temperature control model is as follows: initialize the heater inlet water temperature to the intermediate value between the preset maximum inlet water temperature and the preset minimum inlet water temperature; update the inlet water temperature based on the gradient descent method, and calculate the total heat exchange efficiency after each update until the minimum total heat exchange efficiency is obtained, and output the current corresponding heater inlet water temperature; simulate the evaporator inlet water temperature based on the current corresponding heater inlet water temperature and the determined flow rates of the original high-temperature molten salt allocated to the evaporator and the three-way valve bypass, and obtain the target inlet water temperature under the optimal heat exchange efficiency.

[0032] Optionally, the joint optimization model is expressed as:

[0033]

[0034] in, R represents the total heat exchange efficiency; R represents the system safety risk cost.

[0035] Optionally, the rule for determining the system security risk cost is as follows:

[0036]

[0037] in, The penalty weight for the molten salt outlet temperature exceeding the preset safe molten salt temperature; Penalty weight for heater inlet water temperature exceeding the maximum design allowable inlet water temperature; and These are the molten salt outlet temperature and the preset safe molten salt temperature, respectively. and These are the heater inlet water temperature and the maximum design allowable inlet water temperature, respectively.

[0038] Optionally, the step of generating a control scheme for the two-stage heat exchange device of the molten salt heated DC steam generator based on the joint optimization model includes: performing condition initialization to set the molten salt distribution flow rate of the evaporator and the molten salt distribution flow rate of the three-way valve bypass to be distributed proportionally, and setting the heater inlet water temperature to the middle value of a preset safe inlet water temperature range; based on the initialized conditions, adopting a nested optimization strategy to simultaneously optimize the molten salt flow distribution and the inlet water temperature to obtain the optimal molten salt flow distribution rule and the target inlet water temperature, so as to generate the corresponding control scheme.

[0039] Optionally, the nested optimization strategy simultaneously optimizes flow distribution and inlet water temperature to obtain the optimal molten salt flow distribution rule and target inlet water temperature, thereby generating a corresponding control scheme. This includes: in each iteration, the outer layer optimization is to fix the heater inlet water temperature and perform flow distribution rule optimization based on the molten salt flow distribution model; the inner layer optimization is to fix the molten salt flow distribution rule and perform target inlet water temperature optimization based on the inlet water temperature control model; when the joint optimization model reaches its maximum value or reaches the preset number of iterations, the iteration stops, and the corresponding molten salt flow distribution rule and target inlet water temperature are output to generate a corresponding control scheme.

[0040] Optionally, the execution of the control scheme and the real-time monitoring of the steam output information of the evaporator's steam outlet to control the real-time matching of the steam output information of the steam outlet with the heating path information includes: generating an actual steam output curve based on the real-time information of the steam output information of the steam outlet; comparing the actual steam output curve with the expected steam output curve corresponding to the heating path information; and when a situation exceeds a preset deviation threshold, performing initialization based on the expected steam output curve of the corresponding node and regenerating the corresponding control scheme until heating is completed.

[0041] A second aspect of this invention provides a two-stage heat exchange control system for a molten salt-heated direct-flow steam generator, applied to the control of the two-stage heat exchange device during the heating process. The two-stage heat exchange device includes an evaporator and a heater connected in series, achieving staged heat exchange of the high-temperature molten salt through convective heat exchange between the incoming water and the high-temperature molten salt. The evaporator and the heater are connected by a three-way valve to allow a portion of the original high-temperature molten salt and a portion of the high-temperature molten salt after heat exchange in the evaporator to flow into the heater. The system includes a data acquisition unit for acquiring real-time heating demand in response to a heating request signal. The system includes: an information parsing unit for parsing the heating demand information and determining the heating path information within the corresponding heating cycle; a scheme generation unit for constructing a joint optimization model based on the heating path information, and generating a control scheme for the two-stage heat exchange device of the molten salt heated DC steam generator based on the joint optimization model; wherein the joint optimization model includes a coupled high-temperature molten salt flow distribution model and an inlet water temperature control model; and an execution unit for executing the control scheme and monitoring the steam output information of the evaporator's steam outlet in real time to control the real-time matching of the steam output information of the steam outlet with the heating path information.

[0042] On the other hand, the present invention provides a computer-readable storage medium storing instructions that, when executed on a computer, cause the computer to perform the above-described two-stage heat exchange control method for a molten salt heated DC steam generator.

[0043] Through the above technical solution, this invention introduces a joint optimization model to achieve dynamic coupling optimization of high-temperature molten salt flow distribution and inlet water temperature control, effectively solving the problems of low heat exchange efficiency and insufficient heating path control accuracy in existing technologies. By collecting and analyzing heating demand information in real time, the method can adjust control parameters according to the dynamic operating conditions within the heating cycle, enabling real-time matching of steam output information and heating path information, significantly improving the system's responsiveness and steam quality stability. Furthermore, the adopted joint optimization model can maximize the system's overall heat exchange efficiency through the coordinated optimization of flow and temperature while meeting heating demand, thereby improving energy utilization. Real-time monitoring and control of the evaporator and heater's operating status further enhances the system's operational stability and safety, effectively avoiding operational risks such as molten salt solidification or steam overheating, and meeting the demand for efficient and safe heating under complex operating conditions.

[0044] Other features and advantages of the embodiments of the present invention will be described in detail in the following detailed description section. Attached Figure Description

[0045] The accompanying drawings are provided to further illustrate embodiments of the present invention and form part of the specification. They are used together with the following detailed description to explain the embodiments of the present invention, but do not constitute a limitation thereof. In the drawings:

[0046] Figure 1 This is a schematic diagram of the structure of a two-stage heat exchange device for a molten salt heated DC steam generator according to one embodiment of the present invention;

[0047] Figure 2 This is a flowchart of the steps of a two-stage heat exchange control method for a molten salt heated DC steam generator provided in one embodiment of the present invention;

[0048] Figure 3 This is a system structure diagram of a two-stage heat exchange control system for a molten salt heated DC steam generator provided in one embodiment of the present invention.

[0049] Explanation of reference numerals in the attached figures

[0050] 1-High-temperature molten salt pipeline; 2-Evaporator salt inlet pipeline; 3-Evaporator steam outlet pipeline; 4-Evaporator; 5-Evaporator salt outlet pipeline; 6-Heater water outlet pipeline; 7-Heater; 8-Heater salt outlet pipeline; 9-Heater water inlet pipeline; 10-Heater salt inlet pipeline; 11-Three-way valve; 12-Evaporator water inlet pipeline; 13-High-temperature molten salt bypass pipeline. Detailed Implementation

[0051] The specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are for illustration and explanation only and are not intended to limit the present invention.

[0052] The two-stage heat exchange device of the molten salt heated direct-flow steam generator used in this invention includes an evaporator and a heater connected in series. This allows for staged heat exchange of the high-temperature molten salt through convective heat exchange between the incoming water and the high-temperature molten salt. The evaporator and heater are connected by a three-way valve to allow a portion of the original high-temperature molten salt and a portion of the high-temperature molten salt after heat exchange in the evaporator to flow into the heater. Figure 1 The two-stage heat exchange device of the molten salt heated direct-flow steam generator used in this invention mainly consists of an evaporator 4 and a heater 7, with molten salt flowing through the shell side and water flowing through the tube side. The piping connections mainly consist of a high-temperature molten salt pipe 1, an evaporator salt inlet pipe 2, an evaporator steam outlet pipe 3, an evaporator salt outlet pipe 5, a heater water outlet pipe 6, a heater salt outlet pipe 8, a heater water inlet pipe 9, a heater salt inlet pipe 10, a three-way valve 11, an evaporator water inlet pipe 12, and a high-temperature molten salt bypass pipe 13.

[0053] In one possible implementation, the working principle and process of each part of the two-stage heat exchange device of the molten salt heated DC steam generator used in the present invention are as follows.

[0054] 1. High-temperature molten salt (560℃) is transported to the molten salt heating direct-flow steam generator via high-temperature molten salt pipeline 1;

[0055] 2. The high-temperature molten salt (560℃) from the high-temperature molten salt pipe 1 is divided into two paths. One path enters the evaporator 4 from the bottom through the evaporator salt inlet pipe 2; the other path flows to the three-way valve 11 through the high-temperature molten salt bypass pipe 13. The high-temperature molten salt enters the evaporator from the bottom and exits the evaporator from the top, making the heat exchange surface inside the evaporator more evenly heated.

[0056] 3. Inside the evaporator 4, after the high-temperature molten salt (560℃) exchanges heat with the incoming water (290℃), it flows out through the evaporator salt outlet pipe 5 located at the top of the evaporator and flows to the three-way valve 11, where it mixes with the high-temperature molten salt from the high-temperature molten salt bypass pipe 13. The flow rate of the high-temperature molten salt entering the evaporator can be adjusted by the opening of the three-way valve.

[0057] 4. The mixed high-temperature molten salt (325℃) enters the heater 7 from the bottom through the three-way valve 11 and the heater salt inlet pipe 10; the molten salt enters the heater from the bottom of the evaporator and exits the heater from the top, so that the heat exchange surface inside the heater is heated more evenly.

[0058] 5. After heat exchange between the molten salt and the incoming water (230℃) in heater 7, it becomes low-temperature molten salt (295℃) and flows out from the top of heater 7 through the heater salt outlet pipe 8. Both the heater water outlet pipe and the salt outlet pipe are located at the top of the heater. The outlet water temperature is 290℃. This structural design ensures that the heater salt outlet temperature will not be lower than the outlet water temperature, eliminating the need for additional control of the outlet salt temperature and naturally preventing the risk of system blockage caused by excessively low outlet salt temperature. The incoming water temperature can be set at 230℃, which is 20℃ lower than the original patent (preheating temperature set at 250℃).

[0059] 6. The water from the molten salt heated DC steam generator enters the heater 7 from the bottom through the heater inlet pipe 9. After heat exchange with the molten salt in the heater, it becomes high temperature water (290℃). It flows out from the top of the heater through the heater outlet pipe 6, and then enters the evaporator from the bottom of the evaporator 4 through the evaporator inlet pipe 12.

[0060] 7. Inside the evaporator 4, high-temperature water (290℃) exchanges heat with high-temperature molten salt (560℃) to become steam (295℃, dryness 80%), which flows out from the top of the evaporator 4 through the evaporator steam outlet pipe 3. The evaporator salt outlet pipe and the evaporator steam outlet pipe are both located at the top of the evaporator. The temperature difference between the steam temperature and the molten salt temperature is small. When the temperature and flow rate of the high-temperature molten salt change, the steam dryness fluctuates within a small range, and the system stability is better.

[0061] 8. The three-way valve 11, the high-temperature molten salt pipeline 1, the evaporator salt inlet pipeline 2, and the heater salt inlet pipeline 10 are all located at the bottom of the equipment. The three-way valve 11 can play two roles: 1) When the system is running, the opening of the three-way valve 11 can be used to regulate the flow rate of high-temperature molten salt entering the evaporator 4, thus playing a regulating role; 2) When the system is shut down, the three-way valve 11 can be used to connect the high-temperature molten salt pipeline 1, the evaporator salt inlet pipeline 2, and the heater salt inlet pipeline 10, which can be used as a system salt discharge pipeline to drain the molten salt in the steam generator.

[0062] Figure 2 This is a flowchart illustrating a two-stage heat exchange control method for a molten salt-heated direct-flow steam generator according to one embodiment of the present invention. Figure 2 As shown, this invention provides a two-stage heat exchange control method for a molten salt heated DC steam generator, the method comprising:

[0063] Step S10: In response to the heating request signal, collect real-time heating demand information.

[0064] Specifically, the heating demand information includes: heating cycle information and target temperature information at each time.

[0065] In this embodiment of the invention, the heating demand information includes heating cycle information and target temperature information at each moment. The heating cycle information describes the time range and dynamic characteristics of the heating task, such as the start time, duration, and load variation patterns, and is a crucial basis for determining the heating path. The target temperature information refers to the required steam outlet temperature and flow rate at each moment within the heating cycle, typically generated dynamically by the operating status of the heating equipment or user demand. Accurate collection of this information is of great significance for achieving precise planning of the heating path.

[0066] By collecting and analyzing this real-time information, the characteristics of heating tasks can be dynamically identified, and the operating status of evaporators and heaters can be adjusted according to demand, thereby ensuring a high degree of matching between steam output and the heating path. Compared with traditional fixed-parameter control methods, this dynamic acquisition method based on real-time data significantly improves response speed and flexibility, and can better adapt to fluctuations in heating load. Furthermore, accurate acquisition of heating demand information provides data support for subsequent flow allocation and inlet water temperature control, making the calculation results of the joint optimization model more closely aligned with actual operating needs. Ultimately, this improves heat exchange efficiency and heating quality, reduces energy waste, and ensures safe and stable operation.

[0067] Step S20: Analyze the heating demand information to determine the heating path information within the corresponding heating cycle.

[0068] Specifically, during the heating cycle, time series analysis is performed to decompose the target temperature information at each moment into heating demand at discrete time points; based on the transmission loss model of steam from the steam outlet of the evaporator to the target heating location, the steam demand and steam temperature at each moment are determined based on the heating demand at each time point, which serve as heating path information.

[0069] Furthermore, after decomposing the target temperature information at each moment into heating demand at discrete time points, the method also includes: performing a time-series arrangement of the heating demand at each time point, identifying outliers and missing points; performing correction processing on outliers, and performing filling processing on missing points, to obtain the complete heating demand at each time point.

[0070] Furthermore, the outlier identification rule is as follows: calculate the mean and standard deviation of the heating demand at each time point; perform the three-standard-deviation method to identify outliers based on the heating demand at each time point and the corresponding mean and standard deviation; the processing rule for correcting outliers is as follows: perform correction processing on outliers based on the moving average method.

[0071] In this embodiment of the invention, during the heating cycle, time series analysis is first performed to decompose the target temperature information at each moment into heating demand at discrete time points. This step, by discretizing continuous time information, generates detailed time node data, ensuring that the heating path accurately reflects the demand changes at each moment. Furthermore, based on the transmission loss model of steam from the evaporator's steam outlet to the target heating location, combined with the discretized heating demand data, the steam demand and steam temperature at each time point are determined. The transmission loss model plays a crucial role here, comprehensively considering the heat and pressure losses of steam in the pipeline, making the heating path information closer to actual operating conditions. This data ultimately forms the heating path information, becoming an important input for subsequent flow allocation and temperature control optimization.

[0072] To improve the completeness and accuracy of heating path information, after decomposing the target temperature information into heating demand at discrete time points, further time-series processing of this data is required. First, the heating demand at each time point is sequentially arranged to ensure data order and completeness. Next, outlier and missing point identification rules are used to perform data quality checks. The outlier identification rule is based on the three-standard-deviation method, which calculates the mean and standard deviation of the heating demand at each time point to determine if there are any abnormal data points (i.e., outliers). This method is simple and efficient, and can quickly detect data points that significantly deviate from the normal range.

[0073] For detected outliers, a moving average method is used for correction. The moving average method smooths outliers based on adjacent data points within a time window, thus eliminating the influence of outlier pairs and making the corrected data more consistent with the actual needs of the heating supply path. Furthermore, for missing points in the heating demand, interpolation or model prediction based on adjacent time points is used to fill in the gaps, thereby restoring data integrity. These data processing methods ensure the accuracy and continuity of heating supply path information, providing reliable data support for operation.

[0074] Through the above steps, complete heating path information is generated, including steam demand and steam temperature at each moment. This data not only reflects the dynamic demand of the target heating location but also helps to adapt to fluctuations in heating load in real time, providing a basis for subsequent control strategies.

[0075] Based on the present invention, through time series analysis and data discretization, heating demand can be refined, generating high-precision heating path information that reflects actual operating conditions. Simultaneously, the introduction of a transmission loss model makes the heating path information more closely aligned with the actual heating process. Outlier correction and missing point filling methods effectively address anomalies and incompleteness in heating demand data, ensuring the continuity and accuracy of heating path information and providing a high-quality data foundation for operation. By analyzing heating demand information in real time, dynamic changes in heating load can be flexibly addressed, ensuring a high degree of matching between the heating path and actual demand, thus improving heating responsiveness. Complete and accurate heating path information provides accurate input for flow distribution and inlet water temperature control, making the calculation results of the joint optimization model closer to actual needs, thereby improving heat exchange efficiency and steam quality. By accurately planning steam demand and temperature, overheating or underheating problems caused by improper path planning are avoided, thereby improving energy utilization efficiency. Precise heating path information can effectively reduce safety hazards caused by heating mismatch, ensuring operational stability and reliability.

[0076] Preferably, both the evaporator and the heater are provided with tortuous water pipes; the water pipes of the evaporator and the heater are connected, and the water flow direction is from the heater to the evaporator; the outlet of the water pipe of the evaporator is connected to the steam outlet of the evaporator.

[0077] In this embodiment of the invention, the water inlet pipes of the evaporator and the heater are connected to achieve a continuous water supply process from the heater to the evaporator. This ensures that the flow direction and heat exchange sequence of the incoming water meet the design requirements and satisfy the stable output requirements of steam quality. Furthermore, the outlet of the evaporator's water inlet pipe is directly connected to the steam outlet of the evaporator, facilitating the efficient conversion of heated water into steam and its export, providing high-quality steam output for heating needs. The tortuous arrangement of the water inlet pipe extends the flow path of water within the heat exchanger, increasing the contact area between the incoming water and the high-temperature molten salt, and improving heat exchange efficiency. The design of the water inlet direction from the heater to the evaporator fully utilizes the preheating capacity of the heater, keeping the water entering the evaporator at a high temperature, which helps reduce the heat load on the evaporator.

[0078] Step S30: Construct a joint optimization model based on the heating path information, and generate a control scheme for the two-stage heat exchange device of the molten salt heated DC steam generator based on the joint optimization model.

[0079] Specifically, the construction rules of the joint optimization model are as follows: a high-temperature molten salt flow distribution model and an inlet water temperature control model are constructed based on the heating path information; the corresponding model constraints are constructed based on the safety of use, and the high-temperature molten salt flow distribution model and the inlet water temperature control model are coupled based on the model constraints to obtain the joint optimization model.

[0080] In this embodiment of the invention, firstly, a high-temperature molten salt flow distribution model and an inlet water temperature control model are constructed based on the heating path information. The flow distribution model rationally allocates the molten salt flow rate according to the dynamic heat load demand of the evaporator and heater in the heating path, optimizing heat exchange efficiency; while the inlet water temperature control model ensures steam output quality and adapts to dynamic heating demands by adjusting the inlet water temperature. Secondly, model constraints are constructed based on operational safety requirements, including minimum molten salt temperature limits, inlet water temperature range constraints, and stability requirements for steam output temperature and flow rate, to avoid operational risks caused by parameter exceeding limits. Finally, the flow distribution model and the inlet water temperature control model are coupled through these constraints to achieve synergistic optimization, ultimately obtaining a joint optimization model.

[0081] Based on the solution of this invention, by jointly optimizing flow distribution and temperature control, heat exchange efficiency can be maximized while meeting heating demand, thereby improving energy utilization. Dynamic adjustment of flow rate and inlet water temperature ensures a high degree of matching between the steam output temperature and flow rate and the heating path, reducing quality fluctuations.

[0082] Furthermore, the construction rules for the high-temperature molten salt flow distribution model are as follows: initialize the inlet water temperature in the heater and evaporator, and define the inlet water temperature in the heater and evaporator as a constant value; use the inlet node of the high-temperature molten salt, the inlet node of the evaporator, the bypass node of the three-way valve, the outlet node of the evaporator, and the inlet node of the heater as the nodes of the flow model to construct the corresponding flow model; wherein, the edge flow of the flow model is the high-temperature molten salt flow distribution amount flowing to the evaporator inlet node and the bypass node of the three-way valve, and the edge cost of the flow model is inversely proportional to the unit molten salt heat exchange efficiency; use the minimum cost maximum flow algorithm as the solution rule for the flow model to obtain the high-temperature molten salt flow distribution model.

[0083] In this embodiment of the invention, the rule first initializes the inlet water temperature of the heater and evaporator, defining it as a constant value to simplify the complexity of temperature variables in the flow allocation model and ensure that the model can focus on optimizing the molten salt flow rate. Next, the inlet node of the high-temperature molten salt, the inlet node of the evaporator, the bypass node of the three-way valve, the outlet node of the evaporator, and the inlet node of the heater are set as key nodes in the flow model, thereby constructing the network topology of the flow model. The edge flow rate in the flow model represents the dynamic allocation ratio of molten salt between the evaporator and the bypass, while the edge cost is inversely proportional to the unit molten salt heat exchange efficiency, reflecting the cost relationship between heat exchange performance and the flow allocation scheme. In the solution rule, the minimum cost maximum flow algorithm is used to solve the flow model. This algorithm aims to achieve the optimal allocation of molten salt flow rate between the evaporator and the heater. By finding the shortest cost path for flow allocation, it maximizes the total heat exchange efficiency of the two-stage heat exchange while satisfying flow conservation and equipment operating constraints. By iteratively solving the model, the molten salt flow allocation strategy can be dynamically optimized to accurately match the heat load requirements of the evaporator and the heater.

[0084] Specifically, the constraints of the flow model are:

[0085]

[0086] The high-temperature molten salt flow distribution model is expressed as follows:

[0087]

[0088] in, The flow rate of the initial high-temperature molten salt allocated to the evaporator; The flow rate of the original high-temperature molten salt allocated to the three-way valve bypass; This represents the total flow rate of the original high-temperature molten salt; The heat exchange efficiency of the evaporator is determined based on a fixed evaporator inlet water temperature. The heat exchange efficiency of the heater is determined based on the inlet water temperature of the heater. Overall heat exchange efficiency.

[0089] In this embodiment of the invention, the total flow rate of the high-temperature molten salt is equal to the sum of the molten salt flow rate allocated to the evaporator and the molten salt flow rate allocated to the three-way valve bypass. Secondly, the total heat exchange efficiency of the high-temperature molten salt flow allocation model is expressed as the sum of the heat exchange efficiency of the evaporator and the heat exchange efficiency of the heater. The heat exchange efficiency of the evaporator is calculated based on the evaporator inlet water temperature and the molten salt flow rate; the heat exchange efficiency of the heater is calculated based on the heater inlet water temperature and the molten salt flow rate. The total flow constraint expresses the flow relationship of the molten salt between the evaporator and the bypass, ensuring flow conservation and providing clear conditions for subsequent optimization. Combining the heat exchange efficiencies of the evaporator and the heater into the total heat exchange efficiency facilitates overall efficiency optimization and improves energy utilization. Calculating the heat exchange efficiency based on constant water temperature and flow rate provides operability and accuracy for dynamically optimizing the flow allocation strategy. Through a clear mathematical model, the complex heat exchange is decomposed into two sub-components (evaporator and heater), reducing the difficulty of control implementation.

[0090] Specifically, the rule for determining the evaporator heat exchange efficiency based on a fixed evaporator inlet water temperature is as follows:

[0091]

[0092] in, The specific heat capacity of molten salt; The temperature of the original high-temperature molten salt; The temperature of the molten salt after heat exchange is based on the inlet water temperature of the constant evaporator. The temperature of the molten salt at the outlet of the device.

[0093] In this embodiment of the invention, the heat exchange efficiency of the evaporator is the ratio of the evaporator's heat exchange capacity to the total heat exchange capacity. The calculation formula is as follows: the numerator represents the molten salt flow rate allocated to the evaporator multiplied by the molten salt's specific heat capacity and the temperature drop of the molten salt in the evaporator, representing the actual heat exchange occurring within the evaporator; the denominator represents the total heat exchange capacity. This quantifies the evaporator's contribution to the total heat exchange. By analyzing the molten salt flow rate and temperature changes in the evaporator, the efficiency of the evaporator during the heat exchange process is clarified, providing a scientific basis for optimizing flow rate allocation. Calculations based on a constant inlet water temperature allow the efficiency model to adapt to changes in flow rate and temperature under different operating conditions, improving dynamic adaptability. Quantifying the evaporator's heat exchange efficiency facilitates the optimization of molten salt flow rate allocation and temperature control, thereby achieving efficient utilization of thermal energy.

[0094] Specifically, the rule for determining the heater heat exchange efficiency based on the constant heater inlet water temperature is as follows:

[0095]

[0096] in, The temperature of the mixed molten salt between the original high-temperature molten salt in the three-way valve bypass and the molten salt after heat exchange in the evaporator; The temperature of the molten salt after heat exchange is based on the inlet water temperature of the constant heater.

[0097] In this embodiment of the invention, the temperature changes of the molten salt at the heater inlet and outlet directly reflect the heat exchange capacity of the heater, supporting a quantitative assessment of the heater's operating status. This model provides an accurate basis for subsequent molten salt flow rate allocation optimization, improving the coordinated efficiency of the heater and evaporator by adjusting the molten salt flow rate and temperature. Based on the constant calculation rules for the heater's inlet water temperature, the model adapts to varying operating conditions, enabling real-time adjustment of control parameters and improved responsiveness. Accurately evaluating the heater's heat exchange efficiency helps optimize molten salt utilization and energy distribution, reducing energy waste.

[0098] Specifically, the rules for solving the flow model based on the minimum cost maximum flow algorithm are as follows: the flow model is converted into a flow network, including evaporator flow, bypass flow, and heater inlet mixing temperature; flow conservation and cost functions are set; the goal is to maximize the total heat exchange efficiency, which is equivalent to minimizing the total flow cost; wherein the cost is inversely proportional to the efficiency of the evaporator and the heater; by finding the shortest cost path from the source node to the sink node, the flow allocation is gradually increased, and the flow allocation ratio of the evaporator and the bypass is adjusted until the optimal flow allocation rule is obtained.

[0099] In this embodiment of the invention, the flow model is first converted into a flow network, which consists of key nodes such as evaporator flow rate, bypass flow rate, and heater inlet mixing temperature, establishing a topology. Flow conservation is the core constraint of this model, requiring the total flow rate to be rationally allocated to the evaporator and bypass to meet the heat exchange requirements of the evaporator and heater. Furthermore, a cost function is defined, which is inversely proportional to the heat exchange efficiency of the evaporator and heater; the higher the heat exchange efficiency, the lower the cost, reflecting the impact of flow allocation on heat exchange performance. During the solution process, maximizing the total heat exchange efficiency is the optimization objective, equivalent to minimizing the total flow cost. By employing the minimum cost maximum flow algorithm, using the shortest cost path search from the source node to the sink node, the flow allocation ratio of the evaporator and bypass is gradually increased to find the optimal solution that balances heat exchange efficiency and flow rate. In each iteration, the algorithm dynamically adjusts the flow allocation strategy according to the flow conservation condition and the cost function, ensuring that the sum of the flow rates of the evaporator and bypass equals the total flow rate of the high-temperature molten salt. Finally, the algorithm outputs the optimal flow allocation rule when the optimization objective is achieved, providing a basis for subsequent control schemes.

[0100] Based on the present invention, the minimum-cost maximum flow algorithm optimizes the allocation of molten salt flow between the evaporator and the bypass, maximizing the synergistic heat exchange efficiency of the evaporator and heater. By minimizing total flow cost, energy waste caused by unreasonable flow allocation is reduced, improving energy utilization. The model can adjust the flow allocation strategy according to real-time operating conditions, adapting to changes in heating demand and ensuring operational flexibility and stability. Flow conservation constraints and an inverse efficiency-cost function are employed to ensure that the flow allocation between the evaporator and the bypass conforms to physical constraints while optimizing heat exchange performance. The algorithm automatically searches for the optimal flow path, simplifying the process of manually designing complex flow rules and significantly improving control efficiency. The flow network structure can be extended to multi-node and multi-path scenarios, suitable for more complex heating systems, laying the foundation for subsequent expansion and optimization.

[0101] Furthermore, the construction rule for the inlet water temperature control model is as follows: the flow rate of the original high-temperature molten salt allocated to the evaporator and the three-way valve bypass is set to a constant value to obtain initial conditions; based on the initial conditions, the corresponding inlet water temperature control model is constructed, expressed as:

[0102]

[0103] in, Overall heat exchange efficiency; The specific heat capacity of molten salt; The temperature of the original high-temperature molten salt; The temperature of the molten salt after heat exchange is based on the inlet water temperature of the constant evaporator. The temperature of the molten salt at the outlet of the device; The temperature of the mixed molten salt between the original high-temperature molten salt in the three-way valve bypass and the molten salt after heat exchange in the evaporator; The temperature of the molten salt after heat exchange is based on the inlet water temperature of the constant heater.

[0104] In this invention, an inlet water temperature control model is constructed by setting the flow rate of high-temperature molten salt allocated to the evaporator and the three-way valve bypass to a constant value, thus determining the initial conditions. In the formula, the total heat exchange efficiency is expressed as the sum of the evaporator heat exchange efficiency and the heater heat exchange efficiency. This model allows for the evaluation of the combined impact of different inlet water temperatures on the heat exchange efficiencies of the evaporator and heater.

[0105] Based on this invention, the model accurately reflects the impact of inlet water temperature on performance by decomposing the heat exchange efficiencies of the evaporator and heater, providing a quantitative indicator for optimized control. Combining the efficiencies of the evaporator and heater into a total heat exchange efficiency lays a theoretical foundation for optimizing their coordinated operation, thereby improving overall heat exchange efficiency. Setting initial conditions with a fixed molten salt flow rate simplifies the model's complexity and clarifies the optimization direction for inlet water temperature control. The model can adjust inlet water temperature parameters based on real-time operating conditions, thereby dynamically optimizing heat exchange efficiency to meet different heating demands. By quantifying the effects of different inlet water temperatures, unnecessary energy loss is reduced, improving the energy utilization rate of molten salt heat exchange. By evaluating and optimizing inlet water temperature parameters, evaporator or heater malfunctions caused by excessively low or high inlet water temperatures are avoided, further improving safety and stability.

[0106] Furthermore, the solution rules for the inlet water temperature control model are as follows: the heater inlet water temperature is initialized to the intermediate value between the preset maximum inlet water temperature and the preset minimum inlet water temperature; the inlet water temperature is updated based on the gradient descent method, and the total heat exchange efficiency after each update is calculated until the minimum total heat exchange efficiency is obtained, and the current corresponding heater inlet water temperature is output; based on the current corresponding heater inlet water temperature and the determined flow rates of the original high-temperature molten salt allocated to the evaporator and the three-way valve bypass, the evaporator inlet water temperature is simulated to obtain the target inlet water temperature under the optimal heat exchange efficiency.

[0107] In this embodiment of the invention, the heater inlet water temperature is initialized to the median value between the preset maximum and minimum inlet water temperatures. This initial value ensures the temperature remains within a safe operating range and provides a reasonable starting point for subsequent optimization. Then, the heater inlet water temperature is iteratively updated using the gradient descent method. During each update, the model recalculates the corresponding total heat transfer efficiency and adjusts the inlet water temperature parameters according to the direction of change in heat transfer efficiency, gradually approaching the minimum total heat transfer efficiency. Finally, when the heat transfer efficiency converges to the optimal value, the corresponding heater inlet water temperature is output.

[0108] Furthermore, based on the determined heater inlet water temperature and the molten salt flow rates allocated to the evaporator and the three-way valve bypass, the evaporator inlet water temperature is simulated and calculated. By analyzing the heat transfer process within the evaporator, the evaporator inlet water temperature is determined, achieving a synergistic optimization effect with the heater inlet water temperature and the allocated molten salt flow rates. The final output of this process is the target inlet water temperature under the condition of highest heat exchange efficiency.

[0109] Specifically, the joint optimization model is expressed as:

[0110]

[0111] in, R represents the total heat exchange efficiency; R represents the safety risk cost.

[0112] Furthermore, the rule for determining the security risk cost is as follows:

[0113]

[0114] in, The penalty weight for the molten salt outlet temperature exceeding the preset safe molten salt temperature; Penalty weight for heater inlet water temperature exceeding the maximum design allowable inlet water temperature; and These are the molten salt outlet temperature and the preset safe molten salt temperature, respectively. and These are the heater inlet water temperature and the maximum design allowable inlet water temperature, respectively.

[0115] In this embodiment of the invention, the joint optimization model simultaneously considers total heat exchange efficiency and safe operating costs, achieving a dynamic balance between efficiency and safety, and improving overall performance. By introducing risk penalty functions for molten salt outlet temperature and heater inlet water temperature, equipment damage or operational abnormalities caused by temperature parameters exceeding the design range are effectively avoided. The model can dynamically adjust weight coefficients according to different operating conditions, adapting to different design requirements and improving model flexibility. The model monitors temperature parameters in real time during the optimization process, ensuring that operation remains within a safe range, significantly improving reliability and stability. The formula structure is clear, facilitating embedding into intelligent control systems for automated operation optimization.

[0116] Furthermore, the control scheme for generating the two-stage heat exchange device of the molten salt heated DC steam generator based on the joint optimization model includes: performing condition initialization to set the molten salt distribution flow rate of the evaporator and the molten salt distribution flow rate of the three-way valve bypass to be distributed proportionally, and setting the heater inlet water temperature to the middle value of the preset safe inlet water temperature range; based on the initialized conditions, adopting a nested optimization strategy to simultaneously optimize the molten salt flow distribution and the inlet water temperature to obtain the optimal molten salt flow distribution rule and the target inlet water temperature, so as to generate the corresponding control scheme.

[0117] Furthermore, the nested optimization strategy simultaneously optimizes flow distribution and inlet water temperature to obtain the optimal molten salt flow distribution rule and target inlet water temperature, thereby generating a corresponding control scheme. This includes: in each iteration, the outer layer optimization is to fix the heater inlet water temperature and perform flow distribution rule optimization based on the molten salt flow distribution model; the inner layer optimization is to fix the molten salt flow distribution rule and perform target inlet water temperature optimization based on the inlet water temperature control model; when the joint optimization model reaches its maximum value or reaches the preset number of iterations, the iteration stops, and the corresponding molten salt flow distribution rule and target inlet water temperature are output to generate a corresponding control scheme.

[0118] In this embodiment of the invention, by combining a nested optimization method and simultaneously optimizing the molten salt flow distribution and the inlet water temperature, the overall performance of the two-stage heat exchanger is improved. The following is a detailed extension of this control scheme:

[0119] 1) Condition initialization: The first step in the control scheme is to perform condition initialization. This specifically includes:

[0120] The evaporator molten salt distribution flow rate and the three-way valve bypass molten salt distribution flow rate are set to be proportionally distributed. This proportional distribution strategy provides a symmetrical and stable initial condition, ensuring good basic performance at the beginning of optimization, while avoiding local optima caused by initial condition deviations. The heater's inlet water temperature is set to the middle value of a preset safe inlet water temperature range. This setting effectively avoids equipment operation risks that may be caused by excessively low or high inlet water temperatures, providing a safety guarantee for subsequent optimization processes. Through this initialization step, the control scheme lays a reliable starting point for subsequent nested optimization strategies, making the optimization process more stable and efficient.

[0121] 2) Nested optimization strategy: Based on the initialization conditions, the control scheme employs a nested optimization strategy to collaboratively optimize the molten salt flow distribution rules and inlet water temperature. The specific execution of the nested optimization strategy includes the following two parts:

[0122] With a fixed heater inlet water temperature, the molten salt flow distribution rules are optimized: The outer layer optimization aims to optimize the molten salt flow distribution ratio between the evaporator and the three-way valve bypass based on a molten salt flow distribution model. After fixing the heater inlet water temperature, the optimization process uses a minimum cost maximum flow algorithm to dynamically adjust the molten salt flow rates of the evaporator and bypass, achieving globally optimal heat exchange efficiency for both the evaporator and heater. This step improves overall heat exchange efficiency by adjusting the distribution of molten salt in the two-stage heat exchange system, ensuring heat load matching between the evaporator and heater.

[0123] A fixed molten salt flow distribution rule is used to optimize the target inlet water temperature: In the inner-layer optimization of each iteration, the target inlet water temperature is optimized using an inlet water temperature control model based on the fixed molten salt flow distribution rule. The heater inlet water temperature is gradually adjusted using the gradient descent method, and the change in overall heat exchange efficiency is calculated until the optimal inlet water temperature that maximizes heat exchange efficiency is found. This process also dynamically adjusts the evaporator inlet water temperature to ensure the synergistic optimization effect of the two-stage heat exchange devices.

[0124] Nested optimization stops iterating when either of the following conditions is met: the objective function of the joint optimization model reaches its maximum value (i.e., the heat exchange efficiency is optimal); or the preset maximum number of iterations is reached. After nested optimization is complete, the optimal molten salt flow distribution rule and target inlet water temperature are output, generating the final control scheme.

[0125] 3) Control scheme generation and execution: The control scheme generated through the above optimization process includes two parts:

[0126] Defining the molten salt flow rate ratio between the evaporator and the bypass provides support for dynamic optimization of heat exchange efficiency. This includes controlling the inlet water temperature of both the heater and evaporator to ensure the heat exchange efficiency and operational safety of the two-stage heat exchange system. This control scheme can be directly used to control the operation of the two-stage heat exchange system, guiding real-time adjustments to the molten salt flow rate and inlet water temperature to meet dynamic heating demands.

[0127] Step S40: Execute the control scheme and monitor the steam output information of the evaporator's steam outlet in real time to control the real-time matching of the steam output information of the steam outlet with the heating path information.

[0128] Specifically, based on the real-time information of steam output from the steam outlet, a corresponding steam output curve is generated. The actual steam output curve is compared with the expected steam output curve corresponding to the heating path information. If the deviation exceeds the preset threshold, initialization is performed based on the expected steam output curve of the corresponding node, and the corresponding control scheme is regenerated until heating is completed.

[0129] In this embodiment of the invention, an actual steam output curve is generated based on real-time steam output information from the steam outlet. This curve reflects the dynamic changes in key parameters such as temperature and flow rate of the current steam output. Simultaneously, combined with heating path information, a desired steam output curve is generated, defining the target parameter range for steam output within the heating cycle. During operation, the actual steam output curve is continuously compared with the desired steam output curve. When the actual output exceeds a preset deviation threshold, it indicates that the current control scheme cannot meet the heating path requirements, potentially leading to problems such as overheating, underheating, or insufficient flow rate of the steam output. At this point, an initialization operation is performed based on the desired steam output curve of the corresponding node, and the control scheme is regenerated, adjusting the molten salt flow distribution and inlet water temperature parameters until the actual steam output matches the desired steam output curve again, meeting the heating demand. This closed-loop control strategy continuously optimizes the steam output state during the heating process, ensuring that it always operates as expected and can quickly respond to dynamic load changes and unexpected operating conditions.

[0130] Based on this invention, by comparing the actual steam output curve with the desired steam output curve in real time, steam output deviations can be accurately identified, and the control scheme can be quickly adjusted to ensure that the output parameters are completely consistent with the heating path requirements. When deviations occur, the system can automatically reinitialize and generate a new control scheme, quickly adapting to dynamic changes in steam demand and effectively coping with complex operating conditions and load fluctuations. By adjusting the molten salt flow distribution and inlet water temperature in real time, heat exchange efficiency is maximized, energy waste is reduced, and overall performance is improved. When the steam output deviation exceeds a threshold, timely intervention can be initiated to avoid steam quality degradation or equipment failure due to prolonged deviations, ensuring stable operation. Real-time monitoring and dynamic optimization form a closed-loop automated control process, reducing manual intervention and improving the level of control intelligence. By quickly responding to steam output deviations, potential risks to equipment and operation caused by overheating, underheating, or insufficient flow of steam are avoided, improving heating safety. This control method can adapt to various operating conditions and demand scenarios, such as dynamic load changes or the needs of special heating paths, possessing high flexibility and applicability.

[0131] Figure 3 This is a system structure diagram of a two-stage heat exchange control system for a molten salt-heated direct-flow steam generator provided in one embodiment of the present invention. Figure 3 As shown, this invention provides a two-stage heat exchange control system for a molten salt heated DC steam generator. The system includes: a data acquisition unit for acquiring real-time heating demand information in response to a heating request signal; a parsing unit for parsing the heating demand information to determine the heating path information within the corresponding heating cycle; a scheme generation unit for constructing a joint optimization model based on the heating path information to generate a control scheme for the two-stage heat exchange device of the molten salt heated DC steam generator; wherein the joint optimization model includes a coupled high-temperature molten salt flow distribution model and an inlet water temperature control model; and an execution unit for executing the control scheme and monitoring the steam output information of the evaporator's steam outlet in real time to control the real-time matching of the steam output information of the steam outlet with the heating path information.

[0132] The present invention also provides a computer-readable storage medium storing instructions that, when executed on a computer, cause the computer to perform the above-described two-stage heat exchange control method for a molten salt heated DC steam generator.

[0133] Those skilled in the art will understand that all or part of the steps in the methods of the above embodiments can be implemented by a program instructing related hardware. This program is stored in a storage medium and includes several instructions to cause a microcontroller, chip, or processor to execute all or part of the steps of the methods described in the various embodiments of the present invention. The aforementioned storage medium includes various media capable of storing program code, such as a USB flash drive, a portable hard drive, a read-only memory (ROM), a random access memory (RAM), a magnetic disk, or an optical disk.

[0134] The optional embodiments of the present invention have been described in detail above with reference to the accompanying drawings. However, the embodiments of the present invention are not limited to the specific details described above. Within the scope of the technical concept of the embodiments of the present invention, various simple modifications can be made to the technical solutions of the embodiments of the present invention, and these simple modifications all fall within the protection scope of the embodiments of the present invention. It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. To avoid unnecessary repetition, the embodiments of the present invention will not further describe the various possible combinations.

[0135] Furthermore, various different embodiments of the present invention can be combined in any way, as long as they do not violate the spirit of the embodiments of the present invention, they should also be regarded as the content disclosed by the embodiments of the present invention.

Claims

1. A two-stage heat exchange control method for a molten salt heated direct-flow steam generator, applied to the control of the two-stage heat exchange device in the heating process of the molten salt heated direct-flow steam generator, characterized in that... The molten salt heated direct-flow steam generator has a two-stage heat exchange device comprising an evaporator and a heater connected in series. This allows for staged heat exchange of the high-temperature molten salt through convective heat exchange between the incoming water and the high-temperature molten salt. The evaporator and heater are connected by a three-way valve to allow a portion of the original high-temperature molten salt and a portion of the high-temperature molten salt after heat exchange in the evaporator to flow into the heater. The method includes: In response to heating request signals, collect real-time heating demand information; The heating demand information is parsed to determine the heating path information within the corresponding heating cycle; A joint optimization model is constructed based on the heating path information, and a control scheme for the two-stage heat exchange device of the molten salt heated direct-flow steam generator is generated based on the joint optimization model; wherein... The joint optimization model includes a coupled high-temperature molten salt flow distribution model and an inlet water temperature control model. The control scheme is executed, and the steam output information of the evaporator's steam outlet is monitored in real time to ensure that the steam output information of the steam outlet is matched with the heating path information in real time.

2. The method according to claim 1, characterized in that, The heating demand information includes: Heating cycle information and target temperature information at each time point; The step of parsing the heating demand information to determine the heating path information within the corresponding heating cycle includes: During the heating cycle, time series analysis is performed to decompose the target temperature information at each moment into heating demand at discrete time points. Based on the transmission loss model of steam from the steam outlet of the evaporator to the target heating location, the steam demand and steam temperature at each time point are determined according to the heating demand at each time point, which serve as the heating path information.

3. The method according to claim 2, characterized in that, After decomposing the target temperature information at each moment into heating demand at discrete time points, the method further includes: Perform a time-series arrangement of heating demand at each point in time, and identify outliers and missing points; Outliers are corrected and missing points are filled to obtain the complete heating demand at each point in time.

4. The method according to claim 3, characterized in that, The outlier identification rule is as follows: Calculate the mean and standard deviation of heating demand at each time point; Based on the heating demand at each time point, and the corresponding mean and standard deviation, the three-standard-deviation method is used to identify outliers; The processing rules for correcting outliers are as follows: Outlier points are corrected using the moving average method.

5. The method according to claim 1, characterized in that, Both the evaporator and the heater are equipped with tortuous water pipes. The evaporator and heater are connected by a water inlet pipe, with the water flowing from the heater to the evaporator. The outlet of the water inlet pipe of the evaporator is connected to the steam outlet of the evaporator.

6. The method according to claim 5, characterized in that, The construction rules for the joint optimization model are as follows: Based on the heating path information, a high-temperature molten salt flow distribution model and an inlet water temperature control model were constructed respectively. Based on the model constraints corresponding to the system's safety construction, the high-temperature molten salt flow distribution model and the inlet water temperature control model are coupled based on the model constraints to obtain a joint optimization model.

7. The method according to claim 6, characterized in that, The construction rules for the high-temperature molten salt flow distribution model are as follows: Initialize the inlet water temperature in the heater and evaporator, and set the inlet water temperature in the heater and evaporator to a constant value; The inlet node of the high-temperature molten salt, the inlet node of the evaporator, the bypass node of the three-way valve, the outlet node of the evaporator, and the inlet node of the heater are used as nodes in the flow model to construct the corresponding flow model; among them, The edge flow rate of the flow model is the high-temperature molten salt flow rate distribution to the evaporator inlet node and the three-way valve bypass node, and the edge cost of the flow model is inversely proportional to the unit molten salt heat exchange efficiency. The minimum cost maximum flow algorithm is used as the solution rule for the flow model to obtain the high-temperature molten salt flow allocation model.

8. The method according to claim 7, characterized in that, The constraints of the flow model are: The high-temperature molten salt flow distribution model is expressed as follows: in, The flow rate of the initial high-temperature molten salt allocated to the evaporator; The flow rate of the original high-temperature molten salt allocated to the three-way valve bypass; This represents the total flow rate of the original high-temperature molten salt; The heat exchange efficiency of the evaporator is determined based on a fixed evaporator inlet water temperature. The heat exchange efficiency of the heater is determined based on the inlet water temperature of the heater. Overall heat exchange efficiency.

9. The method according to claim 8, characterized in that, The rule for determining the heat exchange efficiency of an evaporator based on a fixed evaporator inlet water temperature is as follows: in, The specific heat capacity of molten salt; The temperature of the original high-temperature molten salt; The temperature of the molten salt after heat exchange is based on the inlet water temperature of the constant evaporator. The temperature of the molten salt at the outlet of the device.

10. The method according to claim 9, characterized in that, The rule for determining the heater heat exchange efficiency based on the inlet water temperature of a fixed heater is as follows: in, The temperature of the mixed molten salt between the original high-temperature molten salt in the three-way valve bypass and the molten salt after heat exchange in the evaporator; The temperature of the molten salt after heat exchange is based on the inlet water temperature of the constant heater.

11. The method according to claim 7, characterized in that, The rules for solving the flow model based on the minimum cost maximum flow algorithm are as follows: The flow model is converted into a flow network, including evaporator flow, bypass flow and heater inlet mixing temperature, and flow conservation and cost functions are set. Maximizing the total heat exchange efficiency is equivalent to minimizing the total flow cost; where the cost is inversely proportional to the efficiency of the evaporator and the heater. By finding the shortest cost path from the source node to the sink node, gradually increase the traffic allocation and adjust the traffic allocation ratio of the evaporator and bypass until the optimal traffic allocation rule is obtained.

12. The method according to claim 6, characterized in that, The construction rules for the inlet water temperature control model are as follows: The initial conditions are obtained by setting the flow rate of the original high-temperature molten salt allocated to the evaporator and the three-way valve bypass to a constant value. Based on the initial conditions, the corresponding inlet water temperature control model for the framework is expressed as: in, Overall heat exchange efficiency; The flow rate of the initial high-temperature molten salt allocated to the evaporator; This represents the total flow rate of the original high-temperature molten salt; The specific heat capacity of molten salt; The temperature of the original high-temperature molten salt; The temperature of the molten salt after heat exchange is based on the inlet water temperature of the constant evaporator. The temperature of the molten salt at the outlet of the device; The temperature of the mixed molten salt between the original high-temperature molten salt in the three-way valve bypass and the molten salt after heat exchange in the evaporator; The temperature of the molten salt after heat exchange is based on the inlet water temperature of the constant heater.

13. The method according to claim 12, characterized in that, The solution rules for the inlet water temperature control model are as follows: Initialize the heater's incoming water temperature to the midpoint between the preset maximum and minimum incoming water temperatures; Based on the gradient descent method, the incoming water temperature is updated, and the total heat exchange efficiency after each update is calculated until the lowest total heat exchange efficiency is obtained, and the current corresponding heater incoming water temperature is output. Based on the current corresponding heater inlet water temperature and the determined flow rates of the original high-temperature molten salt allocated to the evaporator and the three-way valve bypass, the evaporator inlet water temperature is simulated to obtain the target inlet water temperature under optimal heat exchange efficiency.

14. The method according to claim 6, characterized in that, The joint optimization model is expressed as follows: in, The total heat exchange efficiency; R represents the system security risk cost.

15. The method according to claim 14, characterized in that, The rule for determining the system security risk cost is as follows: in, The penalty weight for the molten salt outlet temperature exceeding the preset safe molten salt temperature; Penalty weight for heater inlet water temperature exceeding the maximum design allowable inlet water temperature; and These are the molten salt outlet temperature and the preset safe molten salt temperature, respectively. and These are the heater inlet water temperature and the maximum design allowable inlet water temperature, respectively.

16. The method according to claim 15, characterized in that, The control scheme for the two-stage heat exchange device of the molten salt heated DC steam generator, generated based on the joint optimization model, includes: Execute condition initialization to set the evaporator molten salt distribution flow rate and the three-way valve bypass molten salt distribution flow rate to be proportionally distributed, and set the heater inlet water temperature to the middle value of the preset safe inlet water temperature range; Based on the initial conditions, a nested optimization strategy is adopted to simultaneously optimize the molten salt flow distribution and the inlet water temperature, thereby obtaining the optimal molten salt flow distribution rule and the target inlet water temperature to generate the corresponding control scheme.

17. The method according to claim 16, characterized in that, The nested optimization strategy simultaneously optimizes flow distribution and inlet water temperature to obtain the optimal molten salt flow distribution rule and target inlet water temperature, thereby generating a corresponding control scheme, including: In each iteration, the outer layer optimization is to fix the inlet water temperature of the heater and perform flow distribution rule optimization based on the molten salt flow distribution model; the inner layer optimization is to fix the molten salt flow distribution rule and perform target inlet water temperature optimization based on the inlet water temperature control model. When the joint optimization model reaches its maximum value or the preset number of iterations, the iteration stops, and the corresponding molten salt flow distribution rules and target influent temperature are output to generate the corresponding control scheme.

18. The method according to claim 1, characterized in that, The execution of the control scheme and the real-time monitoring of the steam output information at the evaporator's steam outlet to control the real-time matching of the steam output information at the steam outlet with the heating path information include: Real-time information on steam output from the steam outlet is used to generate a curve for the actual steam output. By comparing the actual steam output curve with the expected steam output curve corresponding to the heating path information, if the deviation exceeds the preset threshold, initialization is performed based on the expected steam output curve of the corresponding node, and the corresponding control scheme is regenerated until heating is completed.

19. A two-stage heat exchange control system for a molten salt heated direct-flow steam generator, applied to the control of the two-stage heat exchange device in the heating process of the molten salt heated direct-flow steam generator, characterized in that... The molten salt heated direct-flow steam generator's two-stage heat exchange device includes an evaporator and a heater connected in series to achieve staged heat exchange of the high-temperature molten salt through convective heat exchange between the incoming water and the high-temperature molten salt. The evaporator and the heater are connected by a three-way valve to allow some of the original high-temperature molten salt and some of the high-temperature molten salt after heat exchange in the evaporator to flow into the heater; the system includes: The data acquisition unit is used to collect real-time heating demand information in response to heating request signals. The parsing unit is used to parse the heating demand information and determine the heating path information within the corresponding heating cycle; The scheme generation unit is used to construct a joint optimization model based on the heating path information, and to generate a control scheme for the two-stage heat exchange device of the molten salt heated direct-flow steam generator based on the joint optimization model; wherein... The joint optimization model includes a coupled high-temperature molten salt flow distribution model and an inlet water temperature control model. The execution unit is used to execute the control scheme and monitor the steam output information of the evaporator's steam outlet in real time, so as to control the real-time matching of the steam output information of the steam outlet with the heating path information.

20. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores instructions that, when executed on a computer, cause the computer to perform the two-stage heat exchange control method for a molten salt heated DC steam generator as described in any one of claims 1-18.

Images