Method and System for Monitoring Freezing of Finned Tube Bundles in Direct Air-Cooled Islands

Abstract

This invention discloses a method and system for monitoring the antifreeze properties of finned tube bundles in direct air-cooled islands, relating to the field of temperature measurement technology for direct air-cooled units. The method includes acquiring temperature monitoring data of the finned tube bundle surface, calculating the antifreeze margin from the temperature monitoring data to obtain antifreeze status data; pre-setting an antifreeze monitoring model and inputting the antifreeze status data into the model; and intelligently monitoring and locating the freezing status of the finned tube bundle based on the output of the antifreeze monitoring model. This invention ensures the effectiveness of monitoring and improves the efficiency of temperature data acquisition by establishing a one-dimensional temperature monitoring deployment scheme. By locating freezing based on the working fluid flow characteristics, temperature anomalies in the finned tube bundle are classified into different risk levels, and corresponding antifreeze assessment methods are adopted, improving the accuracy of freezing identification. A real-time monitoring and evaluation system is established through antifreeze margin indicators, and the antifreeze monitoring scheme is regularly updated and optimized to improve monitoring efficiency.

Description

Technical Field

[0001] This invention relates to the field of temperature measurement technology for direct air-cooled units, and in particular to a method and system for monitoring the antifreeze properties of finned tube bundles in direct air-cooled islands. Background Technology

[0002] During winter operation, direct air-cooled units are frequently affected by freezing issues. Due to factors such as lower power generation load, lower fan speed, unit start-up and shutdown, lower ambient temperature, and higher ambient wind speed, direct air-cooled units are highly susceptible to freezing of the working fluid inside the finned tube bundle, leading to deformation and damage of the tube bundle. This, in turn, affects the safe operation and economy of the entire unit. Therefore, antifreeze monitoring of the finned tube bundle is particularly important.

[0003] The direct air condenser uses a single row of finned tube bundles, connecting the upper distribution pipe to the lower connecting pipe, and maintaining a 60° tilt angle with the ground to ensure that the steam in the distribution pipe can be condensed into condensate and flow into the lower connecting pipe. Therefore, the working fluid in the finned tube bundle flows longitudinally along the tube bundle.

[0004] When a freezing accident occurs, the temperature of the working fluid inside the tube bundle will drop sharply. When the working fluid temperature is lower than the condensation temperature, freezing will occur. Whether it is a co-current or counter-current tube bundle, once freezing occurs, the internal working fluid will continuously condense into ice, which will lead to a continuous reduction in the flow rate of the working fluid and exhaust steam. The most intuitive phenomenon reflected is that the temperature of the frozen tube bundle and the surrounding tube bundle drops significantly. In severe cases, the freezing of a large area of ​​tube bundle will occur.

[0005] Currently, the commonly used monitoring device employs temperature-sensing cables. These typically encapsulate individual sensors within the cable for contact temperature measurement, enabling accurate monitoring of the finned tube bundle's temperature. Existing cable deployment schemes usually employ three or more cables for two-dimensional temperature monitoring of the finned tube bundle in both the horizontal and vertical dimensions. While this method increases the coverage area of ​​the measuring points, it doesn't significantly aid in freeze protection monitoring. Air-cooled condensers have a vast heat dissipation surface; typical units contain thirty or more air-cooled units, each approximately 10 meters long and 10 meters high. Deploying multiple cables across all heat dissipation surfaces results in numerous useless measuring points. This not only fails to aid freeze protection monitoring but also negatively impacts the overall heat dissipation efficiency of the condenser, increasing the overall cost. Summary of the Invention

[0006] In view of the problems existing in the prior art, the present invention is proposed.

[0007] Therefore, the problem to be solved by this invention is how to use an economical and efficient monitoring method to utilize the longitudinal flow characteristics of the working fluid in the finned tube bundle of the direct air-cooled island, and to replace the traditional two-dimensional layout with a one-dimensional measuring point layout, so as to ensure the monitoring and location capabilities of freezing accidents, reduce the impact on heat dissipation, and reduce system costs.

[0008] To solve the above-mentioned technical problems, the present invention provides the following technical solution:

[0009] In a first aspect, embodiments of the present invention provide a method for monitoring the antifreeze of finned tube bundles in a direct air-cooled island, which includes acquiring temperature monitoring data of the surface of the finned tube bundle and performing antifreeze margin calculation on the temperature monitoring data to obtain antifreeze status data.

[0010] Pre-set an anti-freezing monitoring model and input anti-freezing status data into the anti-freezing monitoring model;

[0011] Intelligent monitoring and regional positioning of the freezing status of finned tube bundles are performed based on the output of the antifreeze monitoring model.

[0012] As a preferred embodiment of the direct air-cooled island finned tube bundle antifreeze monitoring method of the present invention, the temperature monitoring data includes:

[0013] Temperature data collected by temperature sensing cables arranged laterally on the surface of the finned tube bundle of the direct air-cooled island;

[0014] Temperature data is collected through temperature measuring points arranged at preset intervals on the temperature sensing cable.

[0015] As a preferred embodiment of the direct air-cooled island finned tube bundle antifreeze monitoring method of the present invention, the antifreeze margin calculation process includes:

[0016] Calculate the antifreeze effect based on surface temperature and freezing point temperature;

[0017] Calculate the maximum freeze resistance at saturation temperature and freezing point temperature;

[0018] Calculate the ratio of the frost protection degree to the maximum frost protection degree.

[0019] As a preferred embodiment of the direct air-cooled island finned tube bundle antifreeze monitoring method of the present invention, the antifreeze monitoring model includes:

[0020] Freezing risk classification based on the difference in antifreeze margin;

[0021] Identification of frozen areas based on temperature changes at adjacent measuring points;

[0022] Assessment of the freezing impact range based on the flow characteristics of the working fluid.

[0023] As a preferred embodiment of the direct air-cooled island finned tube bundle antifreeze monitoring method of the present invention, the intelligent monitoring of the freezing state includes:

[0024] Real-time temperature measurement data is collected to calculate the antifreeze margin;

[0025] A freezing risk assessment was conducted by comparing the antifreeze margin under normal operating conditions.

[0026] The freezing area is located by combining the flow characteristics of the working fluid.

[0027] As a preferred embodiment of the direct air-cooled island finned tube bundle antifreeze monitoring method of the present invention, the antifreeze margin calculation process adopts:

[0028] Normal operating condition antifreeze

[0029] in, For normal operating conditions, the antifreeze level, This refers to the surface temperature of the finned tube bundle under normal operating conditions. It is the freezing point temperature;

[0030] Maximum antifreeze under normal operating conditions

[0031] in, This represents the maximum antifreeze capability under normal operating conditions. This represents the saturation temperature inside the condenser under normal operating conditions. It is the freezing point temperature;

[0032] Freeze protection margin:

[0033]

[0034] in, Calculate the frost protection margin under normal operating conditions. This is the antifreeze degree. Compared to the maximum antifreeze performance under normal operating conditions percentage;

[0035] The criterion for comparing the difference in antifreeze margin with that under normal operating conditions is as follows:

[0036] A difference of <0.5 indicates no risk of freezing.

[0037] A difference of 0.5 ≤ difference < 0.8 indicates a risk of freezing in the surrounding tubular bundles;

[0038] A difference of 0.8 ≤ difference < 1 indicates a risk of freezing around the measuring point tube bundle;

[0039] A difference of ≥1 indicates that the measuring point has been frozen.

[0040] As a preferred embodiment of the direct air-cooled island finned tube bundle antifreeze monitoring method of the present invention, the specific implementation of frozen area identification includes:

[0041] A layout structure with the heat dissipation surface at a 60-degree angle to the ground;

[0042] The spacing of one temperature measuring point is set at 0.55 meters;

[0043] Density distribution with one measuring point arranged for every 5 finned tube bundles;

[0044] A method of laying out a temperature-sensing cable on each of the two heat dissipation surfaces;

[0045] The layout is adapted to the longitudinal flow characteristics of the working fluid in a single-row tube bundle, and the freezing monitoring of the entire heat dissipation surface is achieved through the layout of one-dimensional measuring points.

[0046] Secondly, embodiments of the present invention provide a direct air-cooled island finned tube bundle antifreeze monitoring system, which includes a data acquisition module, an antifreeze assessment module, and a freeze identification module.

[0047] The data acquisition module is used to collect temperature data from the measuring points of the temperature sensing cable, working fluid flow data, ambient temperature data, and tube bundle location data to establish a finned tube bundle temperature monitoring model.

[0048] The antifreeze assessment module is used to calculate the antifreeze margin based on the collected temperature data and to assess the risk of freezing.

[0049] The freeze identification module is used to track the freeze protection monitoring process in real time, establish a freeze area identification system through the freeze protection margin index, and regularly optimize and update the freeze protection monitoring plan.

[0050] Thirdly, embodiments of the present invention provide a computer device, including a memory and a processor, wherein the memory stores a computer program, wherein: when the computer program instructions are executed by the processor, the steps of the direct air-cooled island finned tube bundle antifreeze monitoring method as described in the first aspect of the present invention are implemented.

[0051] Fourthly, embodiments of the present invention provide a computer-readable storage medium having a computer program stored thereon, wherein: when the computer program instructions are executed by a processor, they implement the steps of the direct air-cooled island finned tube bundle antifreeze monitoring method as described in the first aspect of the present invention.

[0052] The beneficial effects of this invention are as follows: The direct air-cooled island finned tube bundle antifreeze monitoring method provided by this invention ensures the effectiveness and economy of monitoring by establishing a one-dimensional temperature monitoring deployment scheme, improves the efficiency of temperature data acquisition, reduces deployment redundancy, and improves the accuracy and reliability of antifreeze monitoring; by locating freezes based on the working fluid flow characteristics, the temperature anomalies of the finned tube bundle are classified into different risk levels, and corresponding antifreeze assessment methods are adopted, which improves the accuracy of freeze identification, reduces monitoring costs and the impact on heat dissipation, and ensures the economy and practicality of antifreeze monitoring; by establishing a real-time monitoring and evaluation system through antifreeze margin indicators, the antifreeze monitoring scheme is updated and optimized regularly, improving monitoring efficiency and reducing the occurrence of freezing accidents, ensuring the advanced nature and high efficiency of the monitoring scheme. This invention achieves better results in terms of monitoring efficiency, system cost, and antifreeze early warning. Attached Figure Description

[0053] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0054] Figure 1 A flowchart for monitoring the antifreeze of finned tube bundles in a direct air-cooled island;

[0055] Figure 2 Simulation diagram for verifying the antifreeze monitoring method of finned tube bundles in direct air-cooled islands; Detailed Implementation

[0056] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0057] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein, and those skilled in the art can make similar extensions without departing from the spirit of the invention. Therefore, the invention is not limited to the specific embodiments disclosed below.

[0058] Secondly, the term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The phrase "in one embodiment" appearing in different places in this specification does not necessarily refer to the same embodiment, nor is it a single or selective embodiment that is mutually exclusive with other embodiments.

[0059] Example 1

[0060] Reference Figures 1-2 This is the first embodiment of the present invention, which provides a method for monitoring the antifreeze properties of a direct air-cooled island finned tube bundle, including:

[0061] S1, acquire temperature monitoring data of the finned tube bundle surface, and perform antifreeze margin calculation on the temperature monitoring data to obtain antifreeze status data;

[0062] In this embodiment of the application, the temperature monitoring data includes:

[0063] Temperature data collected by temperature sensing cables arranged laterally on the surface of the finned tube bundle of the direct air-cooled island;

[0064] Temperature data is collected through temperature measuring points arranged at preset intervals on the temperature sensing cable.

[0065] In this embodiment of the application, the antifreeze margin calculation process includes:

[0066] Calculate the antifreeze effect based on surface temperature and freezing point temperature;

[0067] Calculate the maximum freeze resistance at saturation temperature and freezing point temperature;

[0068] Calculate the ratio of the frost protection degree to the maximum frost protection degree.

[0069] Furthermore, the temperature monitoring data includes temperature data from the sensing cable measuring points, working fluid flow data, ambient temperature data, and tube bundle location data; the temperature data from the sensing cable measuring points includes real-time surface temperature and historical surface temperature; the working fluid flow data includes working fluid flow rate and direction; the ambient temperature data includes ambient temperature and wind speed; and the tube bundle location data includes relative location information of the measuring points.

[0070] It should be noted that for the 660MW direct air-cooled unit, the air-cooled island of the unit consists of 8 rows of radiators, with 7 air-cooling units in each row. Each fan corresponds to one air-cooling unit, and each air-cooling unit contains 220 finned tube bundles with a total length of 11 meters. A temperature sensing cable is horizontally arranged on each side of the heat dissipation surface of a row of radiators. Inside the cable, a measuring point is placed at approximately 0.55 meters intervals, and approximately every 5 finned tube bundles. This allows for monitoring of this row of radiators. This process is repeated for the other rows of radiators to achieve overall monitoring of the air-cooled island.

[0071] It should also be noted that the temperature measured at the sensing cable reflects the real-time temperature state of the finned tube bundle surface. Historical data is used to establish a baseline for normal operating conditions. The flow rate and direction of the working fluid directly affect the heat transfer effect inside the tube bundle, while ambient temperature and wind speed have a significant impact on heat dissipation performance. The collaborative analysis of these data helps to accurately assess the risk of freezing. The location information of the sensing points is used to determine the specific area of ​​temperature anomalies, providing a spatial positioning basis for subsequent freezing early warning.

[0072] This invention patent sets the surface temperature of the finned tube bundle under normal operating conditions to be The freezing point temperature is At this time, the antifreeze performance under normal operating conditions The calculation formula is as follows:

[0073]

[0074] S2, preset the antifreeze monitoring model and input the antifreeze status data into the antifreeze monitoring model;

[0075] In this embodiment of the application, the antifreeze monitoring model includes:

[0076] Freezing risk classification based on the difference in antifreeze margin;

[0077] Identification of frozen areas based on temperature changes at adjacent measuring points;

[0078] Assessment of the freezing impact range based on the flow characteristics of the working fluid.

[0079] Preferably, the surface temperature of the finned tube bundle under normal operating conditions is set as follows: The freezing point temperature is At this time, the antifreeze performance under normal operating conditions The calculation formula is as follows:

[0080]

[0081] This invention patent sets the saturation temperature inside the condenser under normal operating conditions as: At this point, the maximum antifreeze degree under normal operating conditions The calculation formula is as follows:

[0082]

[0083] The antifreeze margin defined in this invention patent is Calculate the antifreeze margin under normal operating conditions. This is the antifreeze degree. Compared to the maximum antifreeze performance under normal operating conditions The percentages are as follows:

[0084]

[0085] It should be noted that the verification experiment for freezing monitoring was conducted at an ambient temperature of -5℃, a condenser back pressure of 5 kPa, a freezing point of 0℃, and a finned tube bundle surface temperature of 41℃. Under these conditions, the condenser saturation temperature was 32.1℃. The difference in antifreeze margin was compared with that under normal operating conditions. If the difference was less than 0.5, it indicated that the tube bundle monitored at that point was not in danger; if the difference was between 0.5 and 0.8, it indicated that the surrounding tube bundles would be at risk of freezing; if the difference was between 0.8 and 1, it indicated that the tube bundle around the measuring point would be at risk of freezing; and if the difference was greater than 1, it indicated that the measuring point had already frozen.

[0086] It should also be noted that during the calculation of the antifreeze margin, real-time monitoring of the surface temperature trend, combined with the fluctuation range of the working fluid saturation temperature, can promptly identify potential freezing risks. Establishing a temperature gradient distribution map and analyzing the temperature change patterns between adjacent measuring points helps determine the development trend and impact range of freezing.

[0087] S3, intelligent monitoring and regional positioning of the finned tube bundle freezing status based on the output of the antifreeze monitoring model;

[0088] In this embodiment of the application, intelligent monitoring of the frozen state includes:

[0089] Real-time temperature measurement data is collected to calculate the antifreeze margin;

[0090] A freezing risk assessment was conducted by comparing the antifreeze margin under normal operating conditions.

[0091] The freezing area is located by combining the flow characteristics of the working fluid.

[0092] Furthermore, freezing status monitoring includes real-time assessment of the antifreeze margin and location of the frozen area based on the longitudinal flow characteristics of the working fluid within the tube bundle. According to the single-row tube principle used in direct air-cooled condensers, the working fluid can only flow longitudinally along the tube bundle. When a single tube bundle freezes, it causes blockage inside the bundle, resulting in a corresponding decrease in the temperature and flow rate of the working fluid in the longitudinal direction.

[0093] It should be noted that when a freezing accident occurs, the temperature of the working fluid inside the tube bundle will drop sharply. When the working fluid temperature is lower than the condensation temperature, freezing will occur. Whether it is a co-current or counter-current tube bundle, once freezing occurs, the internal working fluid will continuously condense into ice, which will cause the flow rate of the working fluid and exhaust steam to continuously decrease. This change will radiate to several surrounding tube bundles.

[0094] It should also be noted that the intelligent monitoring system, through real-time data analysis, can accurately identify the initial location and expansion trend of freezing. The system automatically adjusts the monitoring frequency according to the freezing risk level, focusing on high-risk areas. Simultaneously, through the accumulation and analysis of historical data, the system continuously optimizes monitoring parameters and judgment criteria, improving the accuracy and reliability of its early warnings.

[0095] Furthermore, this embodiment also provides a direct air-cooled island finned tube bundle antifreeze monitoring system, including,

[0096] Data acquisition module, antifreeze assessment module, freeze identification module;

[0097] The data acquisition module is used to collect temperature data from the measuring points of the temperature sensing cable, working fluid flow data, ambient temperature data, and tube bundle location data to establish a finned tube bundle temperature monitoring model.

[0098] The antifreeze assessment module is used to calculate the antifreeze margin based on the collected temperature data and to conduct a freezing risk assessment.

[0099] The freeze identification module is used to track the freeze protection monitoring process in real time, establish a freeze area identification system through the freeze protection margin index, and regularly optimize and update the freeze protection monitoring plan.

[0100] This embodiment also provides a computer device applicable to the direct air-cooled island finned tube bundle antifreeze monitoring method, including a memory and a processor; the memory is used to store computer-executable instructions, and the processor is used to execute the computer-executable instructions to realize the direct air-cooled island finned tube bundle antifreeze monitoring method as proposed in the above embodiment.

[0101] The computer device can be a terminal, comprising a processor, memory, communication interface, display screen, and input devices connected via a system bus. The processor provides computing and control capabilities. The memory includes non-volatile storage media and internal memory. The non-volatile storage media stores the operating system and computer programs. The internal memory provides an environment for the operation of the operating system and computer programs stored in the non-volatile storage media. The communication interface is used for wired or wireless communication with external terminals; wireless communication can be achieved through Wi-Fi, carrier networks, NFC (Near Field Communication), or other technologies. The display screen can be an LCD screen or an e-ink screen. The input devices can be a touch layer covering the display screen, buttons, a trackball, or a touchpad on the computer device's casing, or an external keyboard, touchpad, or mouse.

[0102] This embodiment also provides a storage medium storing a computer program, which, when executed by a processor, implements the method for monitoring the antifreeze of direct air-cooled island finned tube bundles as proposed in the above embodiments.

[0103] In summary, the direct air-cooled island finned tube bundle antifreeze monitoring method provided by this invention ensures the effectiveness and economy of monitoring by establishing a one-dimensional temperature monitoring deployment scheme, improves the efficiency of temperature data acquisition, reduces deployment redundancy, and enhances the accuracy and reliability of antifreeze monitoring. By locating freezes based on the working fluid flow characteristics, temperature anomalies in the finned tube bundle are classified into different risk levels, and corresponding antifreeze assessment methods are adopted, improving the accuracy of freeze identification, reducing monitoring costs and the impact on heat dissipation, and ensuring the economy and practicality of antifreeze monitoring. By establishing a real-time monitoring and evaluation system through antifreeze margin indicators, the antifreeze monitoring scheme is updated and optimized regularly, improving monitoring efficiency, reducing the occurrence of freezing accidents, and ensuring the advanced nature and high efficiency of the monitoring scheme. This invention achieves better results in terms of monitoring efficiency, system cost, and antifreeze early warning.

[0104] Example 2

[0105] Reference Figures 1-2 This is the second embodiment of the present invention, which provides a method for monitoring the antifreeze properties of a direct air-cooled island finned tube bundle, including:

[0106] S1: Acquire temperature monitoring data on the surface of the finned tube bundle.

[0107] Furthermore, the temperature monitoring data includes temperature data at the sensing cable measuring point, differential pressure data, ambient temperature data, and tube bundle status data; the temperature data at the sensing cable measuring point includes instantaneous temperature and temperature change rate; the differential pressure data includes the differential pressure at both ends of the tube bundle and the flow resistance; the ambient temperature data includes the ambient temperature and wind speed; and the tube bundle status data includes information on the degree of tube bundle blockage.

[0108] It should be noted that for the 350MW direct air-cooled unit, in the 6 rows of radiators in the air-cooled island, each row is equipped with 5 air-cooled units, each unit contains 180 finned tube bundles, and temperature sensing cables are arranged between adjacent heat dissipation surfaces, with a temperature measuring point arranged every 0.5 meters, so that adjacent measuring points can monitor the temperature changes of 4-5 tube bundles.

[0109] It should also be noted that by monitoring the pressure difference and flow resistance at both ends of the tube bundle, combined with temperature change data, abnormal flow inside the tube bundle can be detected early. Real-time monitoring of ambient temperature and wind speed helps assess the impact of external conditions on heat dissipation, while monitoring the degree of tube bundle blockage provides a basis for preventive maintenance.

[0110] S2: Perform antifreeze margin calculation on temperature monitoring data.

[0111] Furthermore, the freeze protection margin calculation simultaneously considers temperature data, differential pressure data, and tube bundle status data. When the differential pressure across the tube bundle increases abnormally, the monitoring frequency in that area is increased; when a tube bundle blockage trend is detected, the freeze protection warning threshold is adjusted accordingly.

[0112] It should be noted that in actual operation, potential freezing risks can be identified by analyzing the temperature change rate and pressure difference trends. The system will dynamically adjust the calculation parameters of the antifreeze margin based on changes in the monitored data to adapt to different operating conditions.

[0113] S3: Performs intelligent monitoring of the frozen state and location of the area.

[0114] Furthermore, the freezing status monitoring adopts a zoned monitoring strategy. The heat dissipation surface is divided into multiple monitoring zones, and several key monitoring points are set in each zone. By analyzing the temperature distribution characteristics and pressure difference change patterns of the measuring points within the zone, accurate freezing status judgment and zone location can be achieved.

[0115] It should be noted that the system establishes a temperature distribution pattern library under different operating conditions based on historical operating data. When an anomaly is detected, comparative analysis is used to determine the specific location and affected area of ​​freezing. Simultaneously, monitoring data on the degree of tube blockage is combined to assess the potential risks of freezing development.

[0116] It should be noted that the direct air-cooled island finned tube bundle antifreeze monitoring method of the present invention is based on the following principle: the finned tube bundle of the condenser adopts a single row of tubes, and the internal working fluid flows longitudinally along the tube bundle. If a single finned tube bundle freezes, it will cause blockage inside the tube bundle, and the temperature and flow rate of the working fluid in the longitudinal direction of the tube bundle will decrease accordingly. The phenomenon reflected on the outside of the finned tube bundle is that the temperature of the frozen tube bundle will drop sharply, and this change will radiate to several surrounding tube bundles. The temperature measured by the temperature sensing cable measuring point in the frozen area will also change to a certain extent. Therefore, the temperature change is described as the difference between the antifreeze margin under normal operating conditions and the antifreeze margin under actual conditions. The smaller the difference, the closer the current temperature is to the normal temperature, and the less likely freezing will occur. Conversely, the larger the difference, the more the current temperature deviates from the normal temperature. Therefore, the process of antifreeze monitoring can be simplified to simply placing a measuring point in the middle of the middle finned tube bundle. Thus, the measuring points only need to be arranged every few tube bundles in the horizontal dimension of the finned tube bundle, forming a horizontal one-dimensional measuring point layout. Then, the temperature data measured in real time by the measuring points is analyzed to roughly locate the freezing position.

[0117] Example 3

[0118] Reference Figures 1-2This is the second embodiment of the present invention, which provides a method for monitoring the antifreeze of finned tube bundles in a direct air-cooled island. In order to verify the beneficial effects of the present invention, scientific demonstration is carried out through economic benefit calculation and simulation experiments.

[0119] Taking a 660MW direct air-cooled unit as an example, the air-cooled island of this unit consists of 8 rows of radiators, with 7 air-cooling units per row (one air-cooling unit corresponding to each fan). Each air-cooling unit contains 220 finned tube bundles with a total length of 11 meters. A temperature sensing cable is horizontally arranged on each side of the heat dissipation surface of a row of radiators. Inside the cable, a measuring point is placed at approximately 0.55 meters intervals (approximately one measuring point every 5 finned tube bundles). This allows for monitoring of this row of radiators. This process is repeated for the other rows of radiators to achieve overall monitoring of the air-cooled island.

[0120] Based on the monitoring method in the example, the surface temperature data of the finned tube bundle monitored by the temperature sensing cable is substituted into the antifreeze margin calculation formula to obtain the antifreeze margin at this moment. This value is then recorded as and compared with the antifreeze margin under normal operating conditions to obtain the difference between the two. If the difference is less than 0.5, it means that the tube bundle monitored by the measuring point is not in danger; if the difference is between 0.5 and 0.8, it means that the surrounding tube bundles will be in danger of freezing; if the difference is between 0.8 and 1, it means that the tube bundle around the measuring point will be in danger of freezing; if the difference is greater than 1, it means that the measuring point has already frozen.

[0121]

[0122] The heat transfer process of an air-cooled unit in a 660MW direct air-cooled turbine was simulated using the Simulink platform in Matlab to verify the feasibility of the anti-freezing early warning method for the finned tube bundle of the direct air-cooled island. A verification experiment for freeze monitoring was conducted at an ambient temperature of -5℃, a condenser back pressure of 5 kPa, a freezing point of 0℃, and a finned tube bundle surface temperature of 41℃. The pressure-saturation temperature comparison table shows the condenser saturation temperature and the anti-freezing margin under these conditions. The effectiveness of the anti-freezing margin difference was also verified when the finned tube bundle surface temperature ranged from 5℃ to 45℃. The verification results are as follows: Figure 2 As shown in the table. Based on actual operational experience, freezing is generally not a risk when the surface temperature of the finned tube bundle is above 25℃; freezing may occur around the measuring point between 10℃ and 25℃; freezing at the measuring point itself is likely between 5℃ and 10℃; and freezing has generally occurred below 5℃. The data in the table is largely consistent with actual operational experience parameters, thus verifying the effectiveness of this method.

[0123] In summary, compared with existing technologies, this invention has the following advantages: The one-dimensional cable layout allows for monitoring and assessment of the occurrence and location of freezing incidents, reducing the impact on heat dissipation and improving economic efficiency. This invention provides a freeze-prevention early warning method for direct air-cooled island finned tube bundles, using this method to assist the one-dimensional layout of temperature-sensing cables in achieving freeze-prevention monitoring. This invention proposes a layout method that differs from two-dimensional monitoring schemes, employing a one-dimensional layout approach. This improves the ability to analyze the status of air-cooled radiators in frigid winter regions, enhances temperature early warning and logic control, accumulates winter operating experience, and reduces the workload of personnel.

[0124] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A method for monitoring the anti-freezing of a direct air-cooling island finned tube bundle, characterized in that: The method comprises the following steps: obtaining temperature monitoring data of the surface of the finned tube bundle, and performing anti-freezing margin calculation processing on the temperature monitoring data to obtain anti-freezing state data; the anti-freezing margin calculation processing comprises: calculating the anti-freezing degree of the surface temperature and the freezing point temperature; calculating the maximum anti-freezing degree of the saturation temperature and the freezing point temperature; calculating the ratio of the anti-freezing degree and the maximum anti-freezing degree to obtain the anti-freezing margin; the anti-freezing margin calculation processing adopts: Normal operating freeze protection wherein, is the normal operating antifreeze degree, is the finned tube bundle surface temperature under normal operating conditions, is the freezing point temperature; maximum freeze protection under normal conditions wherein, is the maximum freeze protection degree under normal operating conditions, is the saturation temperature in the condenser under normal operating conditions, is the freezing temperature; anti-freezing margin: Wherein, To prevent freezing, the anti-freezing margin under normal working conditions is calculated , that is, the anti-freezing degree ( ) is the percentage of the maximum anti-freezing degree under normal working conditions ( ). the surface temperature data of the finned tube bundle is brought into the anti-freezing margin calculation formula to obtain the anti-freezing margin at this moment, which is recorded as and compared with the anti-freezing margin under normal working conditions to obtain the anti-freezing margin difference value between them, and the anti-freezing margin difference value and the normal working condition comparison criterion are: difference <0.5, no freezing danger is determined; 0.5≤difference<0.8, freezing risk exists around the tube bundle; 0.8≤difference<1, freezing risk exists around the tube bundle of the measuring point; difference≥1, freezing has occurred at the measuring point; presetting an anti-freezing monitoring model, and inputting the anti-freezing state data into the anti-freezing monitoring model; the anti-freezing monitoring model comprises: freezing risk grading judgment based on the anti-freezing margin difference value; freezing area identification based on the temperature change of the adjacent measuring point; freezing influence range evaluation based on the flow characteristics of the working medium; 2. The method of claim 1, wherein the method is characterized by: intelligent monitoring and area positioning of the finned tube bundle freezing state according to the output of the anti-freezing monitoring model. The temperature monitoring data comprises: temperature data collected by temperature sensing cables arranged transversely on the surface of the finned tube bundle of the direct air cooling island; 3. The method of claim 1, wherein the method is characterized by: the temperature data is obtained by temperature measuring points arranged at a preset interval on the temperature sensing cables. The intelligent monitoring of the freezing state comprises: real-time collection of temperature measuring point data for anti-freezing margin calculation; freezing risk assessment by comparing the anti-freezing margin under normal working conditions; 4. The method of claim 1, wherein the method is characterized by: freezing area positioning combined with the flow characteristics of the working medium. The specific implementation of the freezing area identification comprises: a layout structure with an angle of 60 degrees between the heat dissipation surface and the ground; an interval setting of arranging one temperature measuring point every 0.55 meters; a density distribution of arranging one measuring point every 5 finned tube bundles; a layout mode of arranging one temperature sensing cable on each side of the heat dissipation surface; 5. A direct air-cooling island finned tube bundle anti-freezing monitoring system based on the direct air-cooling island finned tube bundle anti-freezing monitoring method according to any one of claims 1 to 4, characterized in that: the layout mode is adapted to the longitudinal flow characteristics of the working medium in the single-row tube bundle, and the freezing monitoring of the entire heat dissipation surface is realized through one-dimensional measuring point layout. It also comprises a data collection module, an anti-freezing evaluation module, and a freezing identification module; the data collection module is used to collect temperature data of the temperature sensing cable measuring points, flow data of the working medium, environmental temperature data, and tube bundle position data, and to establish a finned tube bundle temperature monitoring model; the anti-freezing evaluation module is used to calculate the anti-freezing margin based on the collected temperature data and to perform freezing risk assessment; 6. A computer device comprising a memory and a processor, the memory storing a computer program, characterized in that: the freezing identification module is used to track the anti-freezing monitoring process in real time, to establish a freezing area identification system through the anti-freezing margin index, and to periodically optimize and update the anti-freezing monitoring scheme.

7. A computer readable storage medium having stored thereon a computer program, characterized in that: The processor executes the computer program to realize the steps of the direct air cooling island finned tube bundle anti-freezing monitoring method according to any one of claims 1-4. The computer program is executed by the processor to realize the steps of the direct air cooling island finned tube bundle anti-freezing monitoring method according to any one of claims 1-4.

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