Two-stage heat exchange control method and system for fused salt heating straight-flow type steam generator

Abstract

The embodiment of the invention provides a two-stage heat exchange control method and system for a fused salt heating straight-flow type steam generator, and belongs to the technical field of industrial heat energy transmission. The method comprises the steps that real-time heat supply demand information is collected; heat supply path information in the corresponding heat supply period is determined; a joint optimization model is constructed based on the heat supply path information, and a control scheme of the two-stage heat exchange device of the fused salt heating straight-flow type steam generator is generated based on the joint optimization model; wherein the joint optimization model comprises a high-temperature fused salt flow distribution model and an incoming water temperature control model which are coupled; and executing the control scheme, and monitoring steam output information of a steam outlet of the evaporator in real time so as to control the steam output information of the steam outlet to be matched with the heat supply path information in real time. According to the scheme, dynamic coupling optimization of high-temperature molten salt flow distribution and incoming water temperature control is achieved, and the problems that in the prior art, the heat exchange efficiency is low, and the heat supply path control precision is insufficient are effectively solved.

Description

Technical Field

[0001] The present invention relates to the technical field of industrial heat energy transmission, and in particular to a two-stage heat exchange control method for a molten salt heated once-through steam generator and a two-stage heat exchange control system for a molten salt heated once-through steam generator. Background Art

[0002] In the field of modern energy utilization and heating, molten salt is widely used in efficient heat energy transmission and conversion systems due to its excellent heat transfer performance and high heat capacity. As a high-efficiency heating equipment, the molten salt heated direct current steam generator usually adopts a two-stage heat exchange structure. Through the evaporator and heater connected in series, the graded heat exchange between the high-temperature molten salt and the incoming water is realized, thereby generating high-temperature steam with stable quality. This device has important application value in the fields of industrial heating, solar power generation, etc. However, in actual use, the existing two-stage heat exchange control method has the following major technical problems: 1) Insufficient optimization of heat exchange efficiency: In the existing technologies, most of them only adopt simple fixed-ratio flow distribution or preset water inlet 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.

[0003] 2) Lack of precision in heating path control: Existing solutions usually plan heating paths based on static heating demand and fail to respond to dynamic operating conditions (such as fluctuations in steam demand or changes in incoming water temperature) in real time, which can easily lead to fluctuations in steam quality and make it difficult to ensure the stability of the heating system.

[0004] 3) Insufficient model coupling: The flow distribution between the evaporator and the heater is highly coupled with the inlet water temperature control, but the existing control strategies are mostly separate designs, which fail to fully consider the mutual influence between the two, resulting in difficulty in further improving the control accuracy and heating efficiency of the overall system.

[0005] 4) Insufficient safety and stability: In high-temperature molten salt operation, the dynamic adjustment of the molten salt outlet temperature, incoming water temperature and steam output state is the key to ensure the safe operation of the system. However, the existing technology lacks a systematic joint optimization solution, resulting in risks such as low-temperature solidification of molten salt or overheating of steam during operation.

[0006] In order to solve the above technical problems, it is necessary to propose a heat exchange control solution. Summary of the invention

[0007] The purpose of the embodiments of the present invention is to provide a two-stage heat exchange control method and system for a molten salt heated once-through steam generator, so as to at least solve the problems of insufficient efficiency, steps and accuracy in existing heat exchange control schemes.

[0008] In order to achieve the above-mentioned purpose, the first aspect of the present invention provides a two-stage heat exchange control method for a molten salt heated once-through steam generator, which is applied to the control of the two-stage heat exchange device of the molten salt heated once-through steam generator in the heating process, wherein the two-stage heat exchange device of the molten salt heated once-through steam generator comprises an evaporator and a heater connected in series, so as to realize the graded heat exchange of the high-temperature molten salt through the convection heat exchange between the incoming water and the high-temperature molten salt, and the evaporator and the heater are connected by a three-way valve, so as to merge part of the original high-temperature molten salt and part of the high-temperature molten salt after the heat exchange of the evaporator into the heater; the method comprises: in response to a heating request signal, collect real-time heating demand information; perform analysis on the heating demand information to determine the heating path information within the corresponding heating cycle; construct 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 direct current 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 incoming water temperature control model; execute the control scheme, and monitor the steam output information of the steam outlet of the evaporator in real time to control the steam output information of the steam outlet to match the heating path information in real time.

[0009] Optionally, the heating demand information includes: heating cycle information and target temperature information at each moment; the parsing of the heating demand information to determine the heating path information within the corresponding heating cycle includes: within the heating cycle, performing time series analysis to decompose the target temperature information at each moment into heating demands at discrete time points; based on a transmission loss model of steam from the steam outlet of the evaporator to the target heating position, determining the steam demand and steam temperature corresponding to each moment based on the heating demand at each time point as the heating path information.

[0010] Optionally, after decomposing the target temperature information at each moment into heating demands at discrete time points, the method further includes: performing time series arrangement on the heating demands at each time point, identifying outliers and missing points; performing correction processing on the outliers, and performing filling processing on the missing points to obtain complete heating demands at each time point.

[0011] Optionally, the outlier identification rule is: calculate the corresponding mean and standard deviation based on the heating demand at each time point; perform the triple standard deviation method based on the heating demand at each time point, and the corresponding mean and standard deviation to identify outliers; the processing rule for performing correction processing on outliers is: perform correction processing on outliers based on the sliding average method.

[0012] Optionally, the evaporator and the heater are both provided with a zigzag water pipe; the evaporator and the heater water pipes are connected, and the water flow direction is from the heater to the evaporator; the outlet of the evaporator's water pipe is connected to the steam outlet of the evaporator.

[0013] Optionally, the construction rules of the joint optimization model are: based on the heating path information, respectively constructing a high-temperature molten salt flow distribution model and an incoming water temperature control model; based on the system usage safety, constructing corresponding model constraints, so as to execute the coupling of the high-temperature molten salt flow distribution model and the incoming water temperature control model based on the model constraints to obtain a joint optimization model.

[0014] Optionally, the construction rules of the high-temperature molten salt flow distribution model are as follows: initialize the inlet water temperature in the heater and the evaporator, and set the inlet water temperature in the heater and the evaporator to a constant value; use the inlet node of the high-temperature molten salt, the inlet node of the evaporator, the three-way valve bypass node, the evaporator outlet node and the heater inlet node 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 three-way valve bypass node, 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 of the flow model to obtain the high-temperature molten salt flow distribution model.

[0015] Optionally, the constraints of the traffic model are:

[0016] The high temperature molten salt flow distribution model is expressed as:

[0017] in, is the flow rate of the original high-temperature molten salt allocated to the evaporator; is the flow rate of the original high-temperature molten salt allocated to the three-way valve bypass; is the total flow rate of the original high-temperature molten salt; The heat exchange efficiency of the evaporator is determined based on the fixed evaporator water temperature; is the heat transfer efficiency of the heater determined based on the fixed heater inlet water temperature; Overall heat transfer efficiency.

[0018] Optionally, the determination rule of the evaporator heat exchange efficiency determined based on the fixed evaporator water inlet temperature is:

[0019] in, is the specific heat capacity of the molten salt; is the temperature of the original high-temperature molten salt; is the temperature of the molten salt after heat exchange based on the constant evaporator inlet water temperature; is the temperature of the molten salt at the outlet of the device.

[0020] Optionally, the heat exchange efficiency of the heater determined based on the fixed value heater inlet water temperature is determined as follows:

[0021] in, The temperature of the mixed molten salt of the original high-temperature molten salt bypassed by the three-way valve and the molten salt after heat exchange in the evaporator; It is the temperature of the molten salt after heat exchange based on the incoming water temperature of the fixed heater.

[0022] Optionally, the rules for solving the flow model based on the minimum cost maximum flow algorithm are: converting the flow model into a flow network, including evaporator flow, bypass flow and heater inlet mixing temperature, setting flow conservation and cost functions; maximizing the total heat exchange efficiency as the goal, which is equivalent to minimizing the total flow cost; wherein the cost is expressed inversely proportional to the efficiency of the evaporator and the heater; gradually increasing the flow distribution by finding the shortest cost path from the source node to the sink node, and adjusting the flow distribution ratio of the evaporator and the bypass until the optimal flow distribution rule is obtained.

[0023] Optionally, the construction rule of the incoming water temperature control model is: the flow rate of the original high-temperature molten salt distributed to the evaporator and the three-way valve bypass is set to a constant value to obtain the initial condition; based on the initial condition, the corresponding incoming water temperature control model is constructed, which is expressed as:

[0024] in, Overall heat transfer efficiency; is the specific heat capacity of the molten salt; is the temperature of the original high-temperature molten salt; is the temperature of the molten salt after heat exchange based on the constant evaporator inlet water temperature; is the temperature of the molten salt at the outlet of the device; The temperature of the mixed molten salt of the original high-temperature molten salt bypassed by the three-way valve and the molten salt after heat exchange in the evaporator; It is the temperature of the molten salt after heat exchange based on the incoming water temperature of the fixed heater.

[0025] Optionally, the solution rule of the inlet water temperature control model is: initialize the heater inlet water temperature to the intermediate value of the preset maximum inlet water temperature and the preset minimum inlet water temperature; based on the gradient descent method, update the inlet water temperature, and calculate the total heat exchange efficiency after each update until the lowest total heat exchange efficiency is obtained, and output the current corresponding heater inlet water temperature; based on the current corresponding heater inlet water temperature, and the respectively determined flow rates of the original high-temperature molten salt allocated to the evaporator and the three-way valve bypass, simulate the evaporator inlet water temperature to obtain the target inlet water temperature under the optimal heat exchange efficiency.

[0026] Optionally, the joint optimization model is expressed as:

[0027] in, is the total heat transfer efficiency; R is the system safety risk cost.

[0028] Optionally, the system security risk cost determination rule is:

[0029] in, The penalty weight for the molten salt outlet temperature exceeding the preset safe molten salt temperature; The penalty weight for the heater inlet water temperature exceeding the maximum design allowable water temperature; and They are the molten salt outlet temperature and the preset safe molten salt temperature respectively; and They are the heater inlet water temperature and the maximum design allowable water temperature respectively.

[0030] Optionally, the control scheme for the two-stage heat exchange device of the molten salt heated direct-flow steam generator generated based on the joint optimization model includes: performing conditional initialization to set the evaporator molten salt distribution flow and the three-way valve bypass molten salt distribution flow to equal proportion, and setting the heater inlet water temperature to the middle value of a preset safe inlet water temperature range; based on the initialized conditions, a nested optimization strategy is adopted to simultaneously optimize the molten salt flow distribution and the inlet water temperature to obtain the optimal molten salt flow distribution rule and target inlet water temperature to generate a corresponding control scheme.

[0031] Optionally, the nested optimization strategy is adopted to simultaneously optimize the flow distribution and the inlet water temperature to obtain the optimal molten salt flow distribution rule and the target inlet water temperature to generate a corresponding control scheme, including: in each round of iteration, the outer layer is optimized to fix the heater inlet water temperature to perform flow distribution rule optimization based on the molten salt flow distribution model; the inner layer is optimized to fix the molten salt flow distribution rule to perform target inlet water temperature optimization based on the inlet water temperature control model; when the joint optimization model reaches a maximum value or reaches a preset number of iterations, the iteration is stopped, and the corresponding molten salt flow distribution rule and target inlet water temperature are output to generate a corresponding control scheme.

[0032] Optionally, the control scheme is executed and the steam output information of the steam outlet of the evaporator is monitored in real time to control the steam output information of the steam outlet to match the heating path information in real time, including: 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, initialization is performed based on the expected steam output curve of the corresponding node, and the corresponding control scheme is regenerated until the heating is completed.

[0033] The second aspect of the present invention provides a two-stage heat exchange control system for a molten salt heated direct current steam generator, which is applied to the control of the two-stage heat exchange device of the molten salt heated direct current steam generator during the heating process. The two-stage heat exchange device of the molten salt heated direct current steam generator includes an evaporator and a heater connected in series, so as to realize the graded heat exchange of the high-temperature molten salt through the convection 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 merge part of the original high-temperature molten salt and part of the high-temperature molten salt after the evaporator heat exchange into the heater; the system includes: a collection unit for collecting real-time heating demand in response to a heating request signal Information; a parsing unit, used to parse the heating demand information and determine the heating path information within the corresponding heating cycle; a scheme generating unit, used to construct a joint optimization model based on the heating path information, so as to generate a control scheme for the two-stage heat exchange device of the molten salt heated direct current 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 incoming water temperature control model; an execution unit, used to execute the control scheme and monitor the steam output information of the steam outlet of the evaporator in real time, so as to control the steam output information of the steam outlet to match the heating path information in real time.

[0034] On the other hand, the present invention provides a computer-readable storage medium having instructions stored thereon, which, when executed on a computer, enables the computer to execute the above-mentioned two-stage heat exchange control method for a molten salt-heated once-through steam generator.

[0035] Through the above technical scheme, the scheme of the present invention realizes the dynamic coupling optimization of high-temperature molten salt flow distribution and incoming water temperature control by introducing a joint optimization model, effectively solving the problems of low heat exchange efficiency and insufficient control accuracy of the heating path in the prior art. By real-time acquisition and analysis of heating demand information, the method can adjust the control parameters according to the dynamic operating conditions within the heating cycle, so that the steam output information and the heating path information are matched in real time, significantly improving the responsiveness of the system and the stability of steam quality. In addition, the adopted joint optimization model can maximize the total heat exchange efficiency of the system through the coordinated optimization of flow and temperature while meeting the heating demand, thereby improving energy utilization. Real-time monitoring and control of the operating status of the evaporator and the heater further enhances the operating stability and safety of the system, effectively avoids operating risks such as molten salt solidification or steam overheating, and meets the demand for efficient and safe heating under complex conditions.

[0036] Other features and advantages of the embodiments of the present invention will be described in detail in the following detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] The accompanying drawings are used to provide a further understanding of the embodiments of the present invention and constitute a part of the specification. Together with the following specific embodiments, they are used to explain the embodiments of the present invention, but do not constitute a limitation on the embodiments of the present invention. In the accompanying drawings: Figure 1 It is a structural schematic diagram of a two-stage heat exchange device of a molten salt-heated once-through steam generator provided in one embodiment of the present invention; Figure 2 It is a flowchart of the steps of a two-stage heat exchange control method for a molten salt heated once-through steam generator provided by one embodiment of the present invention; Figure 3 It is a system structure diagram of a two-stage heat exchange control system of a molten salt heated direct current steam generator provided in one embodiment of the present invention.

[0038] Description of Reference Numerals 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 DESCRIPTION

[0039] The specific implementation of the present invention is described in detail below in conjunction with the accompanying drawings. It should be understood that the specific implementation described here is only used to illustrate and explain the present invention, and is not used to limit the present invention.

[0040] The two-stage heat exchange device of the molten salt heated direct current steam generator used in the scheme of the present invention comprises an evaporator and a heater connected in series, so as to realize the graded heat exchange of the high-temperature molten salt through the convection 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 collect part of the original high-temperature molten salt and part of the high-temperature molten salt after the heat exchange of the evaporator into the heater. Figure 1 The two-stage heat exchange device of the molten salt heated direct current steam generator used in the scheme of the present invention is mainly composed of an evaporator 4 and a heater 7, with molten salt passing through the shell and water passing through the tube. The pipeline connection is mainly composed of a high-temperature molten salt pipeline 1, an evaporator salt inlet pipeline 2, an evaporator steam outlet pipeline 3, an evaporator salt outlet pipeline 5, a heater water outlet pipeline 6, a heater salt outlet pipeline 8, a heater water inlet pipeline 9, a heater salt inlet pipeline 10, a three-way valve 11, an evaporator water inlet pipeline 12, and a high-temperature molten salt bypass pipeline 13. Among them, In a possible implementation manner, the working principles and processes of the various parts of the two-stage heat exchange device of the molten salt-heated once-through steam generator used in the solution of the present invention are specifically as follows.

[0041] 1. High temperature molten salt (560°C) is transported from high temperature molten salt pipeline 1 to the molten salt heated once-through steam generator; 2. The high-temperature molten salt (560°C) from the high-temperature molten salt pipeline 1 is divided into two paths. One path enters the evaporator 4 from the bottom of the evaporator 4 through the evaporator salt inlet pipeline 2; the other path flows to the three-way valve 11 through the high-temperature molten salt bypass pipeline 13; the high-temperature molten salt enters the evaporator from the bottom of the evaporator and exits the evaporator from the top of the evaporator, so that the heat exchange surface in the evaporator is heated more evenly; 3. In the evaporator 4, after the high-temperature molten salt (560°C) exchanges heat with the incoming water (290°C), it flows out through the evaporator salt outlet pipe 5 arranged at the top of the evaporator, flows to the three-way valve 11, and 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; 4. The mixed high-temperature molten salt (325°C) enters the heater 7 from the bottom of the heater 7 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 of the heater, so that the heat exchange surface in the heater is heated more evenly; 5. After the molten salt and the incoming water (230°C) in the heater 7 are heat exchanged, they become low-temperature molten salt (295°C), and flow out from the top of the heater 7 through the heater salt outlet pipe 8; the heater water outlet pipe and the salt outlet pipe are both arranged at the top of the heater, and the water outlet temperature is 290°C. This structural design ensures that the heater salt outlet temperature will not be lower than the water outlet temperature, and there is no need to additionally control the salt outlet temperature, which naturally prevents the risk of system clogging caused by the salt outlet temperature being too low; the incoming water temperature can be set at 230°C, which is 20°C lower than the original patent (the preheating temperature is set at 250°C); 6. The water from the molten salt heated once-through steam generator enters the heater 7 from the bottom of the heater 7 through the heater water inlet pipe 9, and after completing the heat exchange with the molten salt in the heater, it becomes high-temperature water (290°C), flows out from the top of the heater through the heater water outlet pipe 6, and then enters the evaporator from the bottom of the evaporator 4 through the evaporator water inlet pipe 12; 7. In the evaporator 4, high-temperature water (290°C) and high-temperature molten salt (560°C) are heat-exchanged to become steam (295°C, 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 arranged 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 fluctuation range of the steam dryness is small, and the system stability is better.

[0042] 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 arranged at the bottom of the equipment. The three-way valve 11 can play two roles: 1) When the system is running, the flow of high-temperature molten salt entering the evaporator 4 is adjusted by the opening of the three-way valve 11 to play a regulating role; 2) When the system is shut down, the high-temperature molten salt pipeline 1, the evaporator salt inlet pipeline 2, and the heater salt inlet pipeline 10 can be connected by adjusting the three-way valve 11, which can be used as a system salt discharge pipeline to discharge the molten salt in the steam generator.

[0043] Figure 2 1 is a flow chart of a two-stage heat exchange control method for a molten salt heated once-through steam generator provided by an embodiment of the present invention. Figure 2 As shown, an embodiment of the present invention provides a two-stage heat exchange control method for a molten salt heated once-through steam generator, the method comprising: Step S10: In response to the heating request signal, collect real-time heating demand information.

[0044] Specifically, the heating demand information includes: heating cycle information and target temperature information at each moment.

[0045] In an embodiment of the present invention, the heating demand information includes heating cycle information and target temperature information at each moment. Among them, the heating cycle information describes the time range and dynamic characteristics of the heating task, such as the heating start time, duration, load change law, etc., and is the key basis for determining the heating path. The target temperature information refers to the steam outlet temperature and flow demand required at each moment in the heating cycle, which is usually dynamically generated by the operating status of the heating equipment or user demand. The accurate collection of this information is of great significance for realizing accurate planning of the heating path.

[0046] By collecting and analyzing this real-time information, the characteristics of the heating task can be dynamically identified, and the operating status of the evaporator and heater can be adjusted according to demand, so that the steam output is highly matched with the heating path. Compared with the traditional fixed parameter control method, this dynamic collection method based on real-time data significantly improves the response speed and flexibility, and can better adapt to fluctuations in heating loads. In addition, the accurate acquisition of heating demand information provides data support for subsequent flow distribution and incoming water temperature control, making the calculation results of the joint optimization model more in line with actual operating needs, ultimately improving heat exchange efficiency and heating quality, reducing energy waste, and ensuring safe and stable operation.

[0047] Step S20: parsing the heating demand information to determine the heating path information within the corresponding heating cycle.

[0048] Specifically, during the heating cycle, time series analysis is performed to decompose the target temperature information at each moment into the 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 position, the steam demand and steam temperature corresponding to each moment are determined based on the heating demand at each time point as the heating path information.

[0049] Furthermore, after decomposing the target temperature information at each moment into the heating demand at discrete time points, the method also includes: performing time series arrangement on the heating demand at each time point, identifying outliers and missing points; performing correction processing on the outliers, and performing filling processing on the missing points to obtain the complete heating demand at each time point.

[0050] Furthermore, the outlier identification rule is: calculate the corresponding mean and standard deviation based on the heating demand at each time point; perform the triple standard deviation method based on the heating demand at each time point, and the corresponding mean and standard deviation to identify outliers; the processing rule for performing correction processing on outliers is: perform correction processing on outliers based on the sliding average method.

[0051] In an embodiment of the present invention, during the heating cycle, time series analysis is first performed to decompose the target temperature information at each moment into the heating demand at discrete time points. This step discretizes the continuous time information to generate detailed time node data, thereby ensuring that the heating path can accurately reflect the demand changes at each moment. Furthermore, based on the transmission loss model of steam from the steam outlet of the evaporator to the target heating position, combined with the discretized heating demand data, the steam demand and steam temperature corresponding to each time point are determined. The transmission loss model plays an important role here. It can comprehensively consider the heat loss and pressure loss of steam in the pipeline, so that the heating path information is closer to the actual working conditions. These data ultimately form the heating path information, which becomes an important input for subsequent flow distribution and temperature control optimization.

[0052] In order to improve the integrity and accuracy of the heating path information, after decomposing the target temperature information into the heating demand at discrete time points, it is necessary to further perform time series processing on these data. First, the time series arrangement is performed for the heating demand at each time point to ensure the order and integrity of the data. Then, the data quality is checked using the outlier and missing point identification rules. The outlier identification rule is based on the triple standard deviation method, which determines whether there are abnormal data (i.e., outliers) by calculating the mean and standard deviation of the heating demand at each time point. This method is simple and efficient, and can quickly detect data points that significantly deviate from the normal range.

[0053] For the detected outliers, the sliding average method is used for correction. The sliding average method can smooth the outliers according to the adjacent data points in the time window, thereby eliminating the impact of the outliers and making the corrected data more in line with the actual needs of the heating path. In addition, for the missing points in the heating demand, the interpolation method or the model prediction method based on the adjacent time points is used to fill in, so as to restore the integrity of the data. These data processing methods ensure the accuracy and continuity of the heating path information and provide reliable data support for operation.

[0054] Through the above steps, the complete heating path information is finally generated, including the steam demand and steam temperature at each moment. These data not only reflect the dynamic demand of the target heating location, but also help to adapt to the fluctuation of heating load in real time, providing a basis for subsequent control strategies.

[0055] Based on the scheme of the present invention, through time series analysis and data discretization, the heating demand can be refined and high-precision heating path information reflecting the actual working conditions can be generated. At the same time, the introduction of the transmission loss model makes the heating path information more in line with the actual situation of the heating process. The outlier correction and missing point filling methods effectively deal with the abnormal and incomplete problems in the heating demand data, ensure the continuity and accuracy of the heating path information, and provide a high-quality data basis for operation. By analyzing the heating demand information in real time, it is possible to flexibly respond to the dynamic changes of the heating load, make the heating path highly matched with the actual demand, and improve the responsiveness of the heating. Complete and accurate heating path information can provide accurate input for flow distribution and incoming water temperature control, so that the calculation results of the joint optimization model are closer to the actual demand, thereby improving the heat exchange efficiency and steam quality. By accurately planning the steam demand and temperature, overheating or insufficient problems caused by improper path planning are avoided, thereby improving energy utilization efficiency. Accurate heating path information can effectively reduce the safety hazards caused by heating mismatch and ensure the stability and reliability of operation.

[0056] Preferably, the evaporator and the heater are both provided with a zigzag water pipe; the evaporator and the heater water pipes are connected, and the water flow direction is from the heater to the evaporator; the outlet of the evaporator's water pipe is connected to the steam outlet of the evaporator.

[0057] In an embodiment of the present invention, the water pipes of the evaporator and the heater are arranged in a connected manner to realize a continuous water supply process from the heater to the evaporator, ensure that the flow direction of the water and the heat exchange sequence meet the design requirements, and meet the stable output requirements of the steam quality. In addition, the outlet of the evaporator water pipe is directly connected to the steam outlet of the evaporator, which is convenient for efficiently converting the heated water into steam and exporting it, providing high-quality steam output for heating needs. The tortuous water pipe can extend the flow path of water inside the heat exchanger, increase the contact area between the water and the high-temperature molten salt, and improve the heat exchange efficiency. The water inlet direction design from the heater to the evaporator makes full use of the preheating capacity of the heater, keeps the water entering the evaporator at a high temperature, and helps to reduce the heat load of the evaporator.

[0058] Step S30: 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 once-through steam generator based on the joint optimization model.

[0059] Specifically, the construction rules of the joint optimization model are as follows: based on the heating path information, a high-temperature molten salt flow distribution model and an incoming water temperature control model are respectively constructed; based on the use of safety, corresponding model constraints are constructed to execute the coupling of the high-temperature molten salt flow distribution model and the incoming water temperature control model based on the model constraints to obtain a joint optimization model.

[0060] In an embodiment of the present invention, firstly, a high-temperature molten salt flow distribution model and an incoming water temperature control model are constructed respectively based on the heating path information. The flow distribution model reasonably distributes the molten salt flow and optimizes the heat exchange efficiency according to the dynamic heat load requirements of the evaporator and the heater in the heating path; and the incoming water temperature control model ensures the steam output quality by adjusting the incoming water temperature, while adapting to the dynamic heating demand. Secondly, model constraints are constructed based on the safety requirements, including the minimum temperature limit of molten salt, the incoming water temperature range constraints, the stability requirements of the steam output temperature and flow, etc., to avoid operational risks caused by parameter over-limit. Finally, the flow distribution model is coupled with the incoming water temperature control model through these constraints to achieve the coordinated optimization of the two, and finally obtain a joint optimization model.

[0061] Based on the scheme of the present invention, through the joint optimization of flow distribution and temperature control, it is possible to maximize the heat exchange efficiency and improve energy utilization while meeting the heating demand. The flow rate and incoming water temperature are dynamically adjusted to ensure that the temperature and flow rate of the steam output are highly matched with the heating path, reducing quality fluctuations.

[0062] Furthermore, the construction rules of the high-temperature molten salt flow distribution model are as follows: initialize the inlet water temperature in the heater and the evaporator, and set the inlet water temperature in the heater and the evaporator to 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 of the flow model to obtain the high-temperature molten salt flow distribution model.

[0063] In an embodiment of the present invention, the rule first initializes the incoming water temperature of the heater and the evaporator, and stipulates it as a fixed value to simplify the complexity of the temperature variable in the flow distribution model, so as to ensure that the model can focus on the optimization of the molten salt flow. Then, 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 the key nodes in the flow model, so as to construct the network topology of the flow model. The edge flow in the flow model represents the dynamic distribution ratio of the molten salt between the evaporator and the bypass, while the edge cost adopts the inverse ratio of the unit molten salt heat exchange efficiency, reflecting the cost relationship between the heat exchange performance and the flow distribution scheme. In the solution rule, the minimum cost maximum flow algorithm is used to solve the flow model. The algorithm aims to achieve the optimal distribution of the molten salt flow between the evaporator and the heater, and maximizes the total heat exchange efficiency of the two-stage heat exchange by finding the shortest cost path of the flow distribution under the premise of satisfying the flow conservation and equipment operation restrictions. By iteratively solving the model, the distribution strategy of the molten salt flow can be dynamically optimized to accurately match the heat load requirements of the evaporator and the heater.

[0064] Specifically, the constraints of the traffic model are:

[0065] The high temperature molten salt flow distribution model is expressed as:

[0066] in, is the flow rate of the original high-temperature molten salt allocated to the evaporator; is the flow rate of the original high-temperature molten salt allocated to the three-way valve bypass; is the total flow rate of the original high-temperature molten salt; The heat exchange efficiency of the evaporator is determined based on the fixed evaporator water temperature; is the heat transfer efficiency of the heater determined based on the fixed heater inlet water temperature; Overall heat transfer efficiency.

[0067] In an embodiment of the present invention, the total flow rate of 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 distribution model is expressed as the sum of the heat exchange efficiency of the evaporator and the heat exchange efficiency of the heater. Among them, 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 flow relationship between the molten salt and the bypass is expressed by the total flow constraint to ensure the conservation of flow and provide clear conditions for subsequent optimization. The heat exchange efficiency of the evaporator and the heater is combined into the total heat exchange efficiency, which is convenient for overall efficiency optimization and improves energy utilization. The heat exchange efficiency is calculated based on the fixed water temperature and flow rate, providing operability and accuracy for the dynamic optimization flow distribution strategy. Through a clear mathematical model, the complex heat exchange is decomposed into two sub-(evaporator and heater), which reduces the difficulty of control implementation.

[0068] Specifically, the determination rule of the evaporator heat exchange efficiency based on the fixed evaporator water inlet temperature is:

[0069] in, is the specific heat capacity of the molten salt; is the temperature of the original high-temperature molten salt; is the temperature of the molten salt after heat exchange based on the constant evaporator inlet water temperature; is the temperature of the molten salt at the outlet of the device.

[0070] In an embodiment of the present invention, the heat exchange efficiency of the evaporator is the ratio of the heat exchange of the evaporator to the total heat exchange. The calculation formula is: the numerator represents the molten salt flow rate allocated to the evaporator multiplied by the specific heat capacity of the molten salt and the temperature drop of the molten salt in the evaporator, which represents the actual amount of heat exchange in the evaporator; the denominator represents the total heat exchange of the whole. It can quantify the contribution of the evaporator to the total heat exchange. Through the molten salt flow rate and temperature change of the evaporator, the efficiency of the evaporator in the heat exchange process is clarified, which provides a scientific basis for optimizing the flow distribution. Based on the constant value calculation of the incoming water temperature, the efficiency model can adapt to the flow and temperature changes under different working conditions, and improve the dynamic adaptability. By quantifying the heat exchange efficiency of the evaporator, it is convenient to optimize the molten salt flow distribution and temperature control, thereby realizing the efficient use of thermal energy.

[0071] Specifically, the determination rule of the heater heat exchange efficiency determined based on the fixed value heater inlet water temperature is:

[0072] in, The temperature of the mixed molten salt of the original high-temperature molten salt bypassed by the three-way valve and the molten salt after heat exchange in the evaporator; It is the temperature of the molten salt after heat exchange based on the incoming water temperature of the fixed heater.

[0073] In an embodiment of the present invention, the temperature change of the molten salt at the inlet and outlet of the heater directly reflects the heat exchange capacity of the heater, and supports the quantitative evaluation of the operating status of the heater. The model provides an accurate basis for the subsequent optimization of the molten salt flow distribution, and improves the synergistic efficiency of the heater and the evaporator by adjusting the molten salt flow and temperature. Based on the fixed value calculation rule of the heater inlet water temperature, the model adapts to the changing working conditions, can adjust the control parameters in real time, and improve the response capability. By accurately evaluating the heat exchange efficiency of the heater, it helps to optimize the utilization of molten salt and energy distribution, and reduce energy waste.

[0074] Specifically, the rules for solving the flow model based on the minimum cost maximum flow algorithm are: converting the flow model into a flow network, including evaporator flow, bypass flow and heater inlet mixed temperature, setting flow conservation and cost functions; maximizing the total heat exchange efficiency as the goal, which is equivalent to minimizing the total flow cost; wherein the cost is expressed inversely by the efficiency of the evaporator and the heater; by finding the shortest cost path from the source node to the sink node, gradually increasing the flow distribution, adjusting the flow distribution ratio of the evaporator and the bypass, until the optimal flow distribution rule is obtained.

[0075] In the embodiment of the present invention, the flow model is first converted into a flow network, which consists of key nodes such as evaporator flow, bypass flow and heater inlet mixed temperature, and a topological structure is established. Flow conservation is the core constraint of the model, requiring the total flow to be reasonably allocated to the evaporator and bypass to meet the heat exchange requirements of the evaporator and the heater. In addition, a cost function is defined, which is inversely proportional to the heat exchange efficiency of the evaporator and the heater. The higher the heat exchange efficiency, the lower the cost, reflecting the impact of flow distribution on heat exchange performance. In the solution process, maximizing the total heat exchange efficiency is the optimization goal, which is equivalent to minimizing the total flow cost. By adopting the minimum cost maximum flow algorithm, the shortest cost path search from the source node to the sink node is used to gradually increase the flow distribution ratio of the evaporator and the bypass, and find the optimal solution for heat exchange efficiency and flow balance. In each iteration, the algorithm dynamically adjusts the flow distribution strategy according to the flow conservation condition and the cost function to ensure that the sum of the flow of the evaporator and the bypass is equal to the total flow of the high-temperature molten salt. Finally, the algorithm outputs the optimal flow distribution rule when the optimization goal is reached, providing a basis for subsequent control schemes.

[0076] Based on the scheme of the present invention, the molten salt flow is optimally distributed between the evaporator and the bypass through the minimum cost maximum flow algorithm, maximizing the collaborative heat exchange efficiency of the evaporator and the heater. Based on the goal of minimizing the total flow cost, the energy waste caused by unreasonable flow distribution is reduced and the energy utilization rate is improved. The model can adjust the flow distribution strategy according to the real-time working conditions, adapt to the changes in heating demand, and ensure the flexibility and stability of operation. The flow conservation constraint and the inverse efficiency cost function are used to ensure that the flow distribution between the evaporator and the bypass not only meets the physical constraints, but also optimizes the heat exchange performance. The algorithm automatically searches for the optimal flow path, simplifies the process of manually designing complex flow rules, and greatly improves the control efficiency. The flow network structure can be expanded to multi-node and multi-path situations, which is suitable for more complex heating and lays the foundation for subsequent expansion and optimization.

[0077] Furthermore, the construction rule of the inlet water temperature control model is: the flow rate of the original high-temperature molten salt distributed to the evaporator and the three-way valve bypass is set to a constant value to obtain the initial condition; based on the initial condition, the corresponding inlet water temperature control model is constructed, which is expressed as:

[0078] in, Overall heat transfer efficiency; is the specific heat capacity of the molten salt; is the temperature of the original high-temperature molten salt; is the temperature of the molten salt after heat exchange based on the constant evaporator inlet water temperature; is the temperature of the molten salt at the outlet of the device; The temperature of the mixed molten salt of the original high-temperature molten salt bypassed by the three-way valve and the molten salt after heat exchange in the evaporator; It is the temperature of the molten salt after heat exchange based on the incoming water temperature of the fixed heater.

[0079] In the implementation of the present invention, the high-temperature molten salt flow rate allocated to the evaporator and the three-way valve bypass is set to a constant value, the initial conditions are determined, and the inlet water temperature control model is constructed. 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. Through this model, the comprehensive impact of different inlet water temperatures on the evaporator and heater heat exchange efficiency can be evaluated.

[0080] Based on the scheme of the present invention, the model accurately reflects the impact of the incoming water temperature on the performance by decomposing the heat exchange efficiency of the evaporator and the heater, and provides a quantitative indicator for optimization control. The efficiency of the evaporator and the heater is synthesized into the total heat exchange efficiency, which lays a theoretical foundation for optimizing the coordinated operation of the two, thereby improving the overall heat exchange efficiency. By setting the initial conditions with a fixed molten salt flow rate, the complexity of the model is simplified, and the optimization direction of the incoming water temperature control is clarified. The model can adjust the incoming water temperature parameters based on real-time operating conditions, thereby dynamically optimizing the heat exchange efficiency to meet different heating needs. By quantifying the effects of different incoming water temperatures, unnecessary energy losses are reduced and the energy utilization rate of molten salt heat exchange is improved. By evaluating and optimizing the incoming water temperature parameters, abnormal operation of the evaporator or heater caused by too low or too high incoming water temperature is avoided, and the safety and stability are further improved.

[0081] Furthermore, the solution rule of 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 lowest 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 respectively 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.

[0082] In an embodiment of the present invention, the inlet water temperature of the heater is initialized to the middle value of the preset maximum inlet water temperature and the minimum inlet water temperature. The setting of this initial value can ensure that the temperature is within the safe operating range and provide a reasonable starting point for subsequent optimization. Then, the inlet water temperature of the heater is iteratively updated by the gradient descent method. During each update process, the model recalculates the corresponding total heat exchange efficiency, and adjusts the inlet water temperature parameters according to the direction of change of the heat exchange efficiency, gradually approaching the minimum total heat exchange efficiency. Finally, when the heat exchange efficiency converges to the optimal value, the corresponding inlet water temperature of the heater is output.

[0083] Furthermore, based on the determined heater inlet water temperature and the molten salt flow rate 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 in the evaporator, the evaporator inlet water temperature is determined so that it can achieve a synergistic optimization effect with the heater inlet water temperature and the allocated molten salt flow rate. The process ultimately outputs the target inlet water temperature under the condition of the highest heat exchange efficiency.

[0084] Specifically, the joint optimization model is expressed as:

[0085] in, is the total heat transfer efficiency; R is the safety risk cost.

[0086] Furthermore, the safety risk cost determination rule is:

[0087] in, The penalty weight for the molten salt outlet temperature exceeding the preset safe molten salt temperature; The penalty weight for the heater inlet water temperature exceeding the maximum design allowable water temperature; and They are the molten salt outlet temperature and the preset safe molten salt temperature respectively; and They are the heater inlet water temperature and the maximum design allowable water temperature respectively.

[0088] In an embodiment of the present invention, the joint optimization model simultaneously considers the total heat exchange efficiency and safe operation cost, achieves a dynamic balance between efficiency and safety, and improves the overall performance. By introducing the risk penalty function of the molten salt outlet temperature and the heater inlet water temperature, equipment damage or abnormal operation caused by temperature parameters exceeding the design range can be effectively avoided. The model can dynamically adjust the weight coefficient according to different operating conditions, adapt to different design requirements, and improve the flexibility of the model. The model monitors the temperature parameters in real time during the optimization process to ensure that the operation is always within a safe range, which significantly improves the reliability and stability. The formula structure is clear and easy to embed into intelligent control to achieve automated operation optimization.

[0089] Furthermore, the control scheme for the two-stage heat exchange device of the molten salt-heated direct-flow steam generator generated based on the joint optimization model includes: executing conditional initialization to set the evaporator molten salt distribution flow and the three-way valve bypass molten salt distribution flow to equal proportion, and setting the heater inlet water temperature to the middle value of the preset safe inlet water temperature range; based on the initialized conditions, a nested optimization strategy is adopted to simultaneously optimize the molten salt flow distribution and the inlet water temperature, so as to obtain the optimal molten salt flow distribution rule and the target inlet water temperature, so as to generate a corresponding control scheme.

[0090] Furthermore, the nested optimization strategy is adopted to simultaneously optimize the flow distribution and the inlet water temperature to obtain the optimal molten salt flow distribution rule and the target inlet water temperature to generate a corresponding control scheme, including: in each round of iteration, the outer layer is optimized to fix the heater inlet water temperature to perform flow distribution rule optimization based on the molten salt flow distribution model; the inner layer is optimized to fix the molten salt flow distribution rule to perform target inlet water temperature optimization based on the inlet water temperature control model; when the joint optimization model reaches the maximum value or reaches the preset number of iterations, the iteration is stopped, and the corresponding molten salt flow distribution rule and target inlet water temperature are output to generate a corresponding control scheme.

[0091] In the embodiment of the present invention, by combining the nested optimization method, the molten salt flow distribution and the incoming water temperature are optimized simultaneously, thereby achieving the overall performance improvement of the two-stage heat exchange device. The following is a specific extended description of the control scheme: 1) Conditional initialization: The first step of the control scheme is to perform conditional initialization. Specifically, it includes: The evaporator molten salt distribution flow and the three-way valve bypass molten salt distribution flow are set to equal proportion distribution. The equal proportion distribution strategy provides a symmetrical and stable initial condition, ensuring good basic performance at the beginning of the optimization, while avoiding the optimization falling into the local optimum due to the deviation of the initial conditions. The inlet water temperature of the heater is set to the middle value of the preset safe inlet water temperature range. Such a setting can effectively avoid the equipment operation risks caused by too low or too high inlet water temperature, and provide safety protection for the subsequent optimization process. Through this initialization step, the control scheme lays a reliable starting point for the subsequent nested optimization strategy, making the optimization process more stable and efficient.

[0092] 2) Nested optimization strategy. Based on the initialization conditions, the control scheme adopts the nested optimization strategy to coordinately optimize the molten salt flow distribution rule and the incoming water temperature. The specific implementation of the nested optimization strategy includes the following two parts: Fix the inlet water temperature of the heater and optimize the molten salt flow distribution rule: The goal of the outer optimization is to optimize the molten salt flow distribution ratio between the evaporator and the three-way valve bypass based on the molten salt flow distribution model. After fixing the inlet water temperature of the heater, the optimization process uses the minimum cost maximum flow algorithm to dynamically adjust the molten salt flow of the evaporator and the bypass, so that the heat exchange efficiency of the evaporator and the heater reaches the global optimum. This step adjusts the distribution of molten salt in the two-stage heat exchange device to ensure that the heat load of the evaporator and the heater matches, thereby improving the overall heat exchange efficiency.

[0093] Fixed molten salt flow distribution rule, optimized target inlet water temperature: In each round of iterative inner optimization, based on the fixed molten salt flow distribution rule, the target inlet water temperature is optimized using the inlet water temperature control model. The inlet water temperature at the heater inlet is gradually adjusted by the gradient descent method, and the change in the total heat transfer efficiency is calculated until the optimal inlet water temperature that maximizes the heat transfer efficiency is found. This process also dynamically adjusts the inlet water temperature of the evaporator to ensure the coordinated optimization effect of the two-stage heat exchange device.

[0094] The nested optimization stops iteration when any of the following conditions are met: The objective function of the joint optimization model reaches the maximum value (i.e., the heat transfer efficiency reaches the optimal value). The preset maximum number of iterations is reached. When the nested optimization is completed, the optimal molten salt flow distribution rule and target inlet water temperature are output to generate the final control solution.

[0095] 3) Control scheme generation and execution. The control scheme generated through the above optimization process includes two parts: The ratio of molten salt flow rate between the evaporator and the bypass is clarified to provide support for the dynamic optimization of heat exchange efficiency. Including the inlet water temperature of the heater and the inlet water temperature of the evaporator, to ensure the heat exchange efficiency and operation safety of the two-stage heat exchange device. This control scheme can be directly used to control the operation of the two-stage heat exchange device, guide the real-time adjustment of the molten salt flow rate and the inlet water temperature, and meet the dynamic heating demand.

[0096] Step S40: executing the control scheme, and monitoring the steam output information of the steam outlet of the evaporator in real time, so as to control the steam output information of the steam outlet to match the heating path information in real time.

[0097] Specifically, an actual steam output curve is generated based on the real-time information of the steam output information of the steam outlet; the actual steam output curve is compared with the expected steam output curve corresponding to the heating path information. When a deviation exceeds a preset threshold, initialization is performed based on the expected steam output curve of the corresponding node, and the corresponding control scheme is regenerated until the heating is completed.

[0098] In an embodiment of the present invention, an actual steam output curve is generated based on the real-time steam output information of the steam outlet. The curve reflects the dynamic changes of key parameters such as the temperature and flow rate of the current steam output. At the same time, combined with the heating path information, an expected steam output curve is generated, which defines the target parameter range of the steam output during the heating cycle. During operation, the actual steam output curve is continuously compared with the expected steam output curve. When the actual output exceeds the preset deviation threshold, it indicates that the current control scheme cannot meet the heating path requirements, which may cause problems such as overheating, too low or insufficient flow of steam output. At this time, an initialization operation is performed based on the expected steam output curve of the corresponding node, and the control scheme is regenerated to adjust the molten salt flow distribution and the incoming water temperature parameters until the actual steam output matches the expected steam output curve again to meet the heating demand. This closed-loop control strategy can continuously optimize the steam output state during the heating process, ensure that it always operates as expected, and can quickly respond to dynamic load changes and unexpected operating conditions.

[0099] Based on the scheme of the present invention, by comparing the actual steam output curve with the expected steam output curve in real time, the steam output deviation can be accurately identified, and the control scheme can be quickly adjusted to ensure that the output parameters are completely consistent with the requirements of the heating path. When a deviation occurs, it can automatically reinitialize and generate a new control scheme to quickly adapt to the dynamic changes in steam demand and effectively cope with complex working conditions and load fluctuations. By adjusting the molten salt flow distribution and the incoming water temperature in real time, the heat exchange efficiency is maximized, energy waste is reduced, and the overall performance is improved. When the steam output deviation exceeds the threshold, timely intervention can be made to avoid the degradation of steam quality or equipment failure caused by long-term deviation, and stable operation is guaranteed. Real-time monitoring and dynamic optimization form a closed-loop automatic control process, reduce manual intervention, and improve the intelligent level of control. By quickly responding to the steam output deviation, the potential risks to the equipment and operation caused by steam overheating, too low or insufficient flow are avoided, and the safety of heating is improved. The control method can adapt to a variety of working conditions and demand scenarios, such as dynamic load changes or the needs of special heating paths, and has high flexibility and applicability.

[0100] Figure 3 1 is a system structure diagram of a two-stage heat exchange control system for a molten salt heated once-through steam generator provided by an embodiment of the present invention. Figure 3 As shown, an embodiment of the present invention provides a two-stage heat exchange control system for a molten salt heated direct current steam generator, the system comprising: an acquisition unit, for acquiring real-time heating demand information in response to a heating request signal; an analysis unit, for analyzing 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, so as to generate a control scheme for the two-stage heat exchange device of the molten salt heated direct current steam generator based on the joint optimization model; wherein the joint optimization model comprises a coupled high-temperature molten salt flow distribution model and an incoming water temperature control model; an execution unit, for executing the control scheme, and monitoring the steam output information of the steam outlet of the evaporator in real time, so as to control the steam output information of the steam outlet to match the heating path information in real time. The embodiment of the present invention further provides a computer-readable storage medium, on which instructions are stored, which, when executed on a computer, enable the computer to execute the above-mentioned two-stage heat exchange control method for a molten salt-heated once-through steam generator.

[0101] Those skilled in the art will understand that all or part of the steps in the method for implementing the above-mentioned embodiments can be completed by instructing the relevant hardware through a program, and the program is stored in a storage medium, including several instructions for making a single-chip microcomputer, a chip or a processor execute all or part of the steps of the method described in each embodiment of the present invention. The aforementioned storage medium includes: U disk, mobile hard disk, read-only memory (ROM, Read-Only Memory), random access memory (RAM, Random Access Memory), disk or optical disk and other media that can store program codes.

[0102] The optional embodiments of the present invention are described in detail above in conjunction with the accompanying drawings. However, the embodiments of the present invention are not limited to the specific details in the above embodiments. Within the technical concept of the embodiments of the present invention, the technical scheme of the embodiments of the present invention can be subjected to a variety of simple modifications, and these simple modifications all belong to 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. In order to avoid unnecessary repetition, the embodiments of the present invention will not further describe various possible combinations.

[0103] In addition, various embodiments of the present invention may be arbitrarily combined, and as long as they do not violate the concept of the embodiments of the present invention, they should also be regarded as the contents disclosed in the embodiments of the present invention.

Claims

1. A two-stage heat exchange control method for a molten salt heated once-through steam generator, which is applied to the control of a two-stage heat exchange device of a molten salt heated once-through steam generator during a heating process, and is characterized in that: The two-stage heat exchange device of the molten salt heated once-through steam generator comprises an evaporator and a heater connected in series, so as to realize the graded heat exchange of the high-temperature molten salt by the convection heat exchange between the incoming water and the high-temperature molten salt, and the evaporator and the heater are connected by a three-way valve to collect part of the original high-temperature molten salt and part of the high-temperature molten salt after the heat exchange of the evaporator into the heater; the method comprises: In response to a heating request signal, collecting real-time heating demand information; Analyzing the heating demand information to determine the heating path information within the corresponding heating cycle; A joint optimization model is constructed based on the heating path information to generate a control scheme for the two-stage heat exchange device of the molten salt heated once-through 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 incoming water temperature control model; The control scheme is executed, and the steam output information of the steam outlet of the evaporator is monitored in real time, so as to control the steam output information of the steam outlet to match 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 moment; The performing of parsing on 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 the 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 position, the steam demand and steam temperature corresponding to each moment are determined based on the heating demand at each time point 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 the heating demand at discrete time points, the method further includes: Perform time series arrangement on the heat demand at each time point to identify outliers and missing points; Correction processing is performed on outliers and filling processing is performed on missing points to obtain complete heating demand at each time point.

4. The method according to claim 3, characterized in that: The outlier identification rule is: Calculate the corresponding mean and standard deviation based on the heating demand at each time point; Based on the heat demand at each time point, as well as the corresponding mean and standard deviation, the triple standard deviation method is used to identify outliers; The processing rules for correcting outliers are: Correction processing is performed on outliers based on the sliding average method.

5. The method according to claim 1, characterized in that The evaporator and the heater are both provided with a zigzag water pipe; The evaporator and the heater are connected by water pipes, and the water flows in the direction from the heater to the evaporator; The outlet of the water supply 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 of the joint optimization model are: Based on the heating path information, a high-temperature molten salt flow distribution model and an incoming water temperature control model are constructed respectively; Based on the system usage safety, corresponding model constraints are constructed to execute the coupling of the high-temperature molten salt flow distribution model and the incoming water temperature control model based on the model constraints to obtain a joint optimization model.

7. The method according to claim 6, characterized in that The construction rules of the high-temperature molten salt flow distribution model are: Initialize the inlet water temperature in the heater and the evaporator, and set the inlet water temperature in the heater and the evaporator to a fixed value; The inlet node of high-temperature molten salt, the inlet node of evaporator, the bypass node of three-way valve, the outlet node of evaporator and the inlet node of heater are used as the nodes of 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 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 of the flow model to obtain a high-temperature molten salt flow distribution model.

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

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

10. The method according to claim 9, characterized in that The determination rule of the heater heat exchange efficiency based on the fixed heater inlet water temperature is: in, The temperature of the mixed molten salt of the original high-temperature molten salt bypassed by the three-way valve and the molten salt after heat exchange in the evaporator; It is the temperature of the molten salt after heat exchange based on the incoming water temperature of the fixed heater.

11. The method according to claim 7, characterized in that The rules for solving the traffic model based on the minimum cost maximum flow algorithm are: Converting the flow model into a flow network, including evaporator flow, bypass flow and heater inlet mixed temperature, setting flow conservation and cost functions; The goal of maximizing the total heat transfer efficiency is equivalent to minimizing the total flow cost, where the cost is inversely proportional to the efficiency of the evaporator and heater; By finding the shortest cost path from the source node to the sink node, the flow distribution is gradually increased and the flow distribution ratio of the evaporator and the bypass is adjusted until the optimal flow distribution rule is obtained.

12. The method according to claim 6, characterized in that The construction rule of the incoming water temperature control model is: The flow rate of the original high-temperature molten salt distributed to the evaporator and the three-way valve bypass is set to a constant value to obtain the initial condition; Based on the initial conditions, the corresponding inlet water temperature control model is constructed and expressed as: in, Overall heat transfer efficiency; is the specific heat capacity of the molten salt; is the temperature of the original high-temperature molten salt; is the temperature of the molten salt after heat exchange based on the constant evaporator inlet water temperature; is the temperature of the molten salt at the outlet of the device; The temperature of the mixed molten salt of the original high-temperature molten salt bypassed by the three-way valve and the molten salt after heat exchange in the evaporator; It is the temperature of the molten salt after heat exchange based on the incoming water temperature of the fixed heater.

13. The method according to claim 12, characterized in that The solution rule of the incoming water temperature control model is: Initializing the heater inlet water temperature to an intermediate value between a preset maximum inlet water temperature and a preset minimum inlet water temperature; Based on the gradient descent method, the inlet 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 inlet water temperature is output; Based on the current corresponding heater inlet water temperature and the respectively 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.

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

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

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

17. The method according to claim 16, characterized in that The nested optimization strategy is adopted to optimize the flow distribution and the incoming water temperature at the same time, to obtain the optimal molten salt flow distribution rule and the target incoming water temperature, so as to generate the corresponding control scheme, including: In each round of iteration, the outer optimization is to fix the heater inlet water temperature, so as to optimize the flow distribution rule based on the molten salt flow distribution model; the inner optimization is to fix the molten salt flow distribution rule, so as to optimize the target water temperature based on the water temperature control model; When the joint optimization model reaches the maximum value or reaches the preset number of iterations, the iteration is stopped and the corresponding molten salt flow distribution rules and target inlet water temperature are output to generate the corresponding control plan.

18. The method according to claim 1, characterized in that The executing of the control scheme and real-time monitoring of the steam output information of the steam outlet of the evaporator to control the steam output information of the steam outlet to match the heating path information in real time include: Generating an actual steam output curve based on real-time information of steam output information of the steam outlet; The actual steam output curve is compared with the expected steam output curve corresponding to the heating path information. When a 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 the heating is completed.

19. A two-stage heat exchange control system for a molten salt heated once-through steam generator, applied to the control of a two-stage heat exchange device of a molten salt heated once-through steam generator during a heating process, characterized in that: The two-stage heat exchange device of the molten salt heated once-through steam generator includes an evaporator and a heater connected in series, so as to realize the graded heat exchange of the high-temperature molten salt through the convection 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 collect part of the original high-temperature molten salt and part of the high-temperature molten salt after the heat exchange of the evaporator into the heater; the system includes: A collection unit, for collecting real-time heating demand information in response to a heating request signal; A parsing unit, configured to parse the heating demand information and determine heating path information within a corresponding heating cycle; A scheme generating unit is used to construct a joint optimization model based on the heating path information, so as to generate a control scheme for the two-stage heat exchange device of the molten salt heated once-through 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 incoming water temperature control model; The execution unit is used to execute the control scheme and monitor the steam output information of the steam outlet of the evaporator in real time to control the steam output information of the steam outlet to match the heating path information in real time.

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

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