Method, device and equipment for preventing leakage of clamping pipe of platen reheater of subcritical boiler

Abstract

The invention provides a subcritical boiler platen reheater clamping pipe leakage prevention method, device and equipment. The subcritical boiler platen reheater clamping pipe leakage prevention method comprises the steps that dissimilar steel welding connection of a clamping pipe and a pulling plate is relieved; assembling a pipe ring on the outer wall of the clamping pipe to form non-welding type mechanical isolation, and welding and fixing a pulling plate on the outer wall of the pipe ring to complete reconstruction of a stress conduction path; after reconstruction is completed, a two-factor monitoring mechanism for spheroidizing degradation of the clamping pipe and temperature fluctuation of the screen reheater is established; monitoring data are collected based on a two-factor monitoring mechanism, and combustion parameter pre-adjustment and pipeline preventive replacement are dynamically triggered; according to the method, the leakage correlation event is periodically analyzed, the coal blending combustion and maintenance strategy is reversely optimized, the problem that leakage is likely to be caused in a traditional welding mode is solved by removing welding and completing stress conduction path reconstruction, faults can be warned in advance through two-factor monitoring and periodic analysis, and the possibility of leakage is reduced.

Description

Technical Field

[0001] This invention relates to the field of boiler technology, and in particular to a method, device, and equipment for preventing leakage of the clamping tube of a subcritical boiler screen-type reheater. Background Art

[0002] As a key component for tube panel positioning in subcritical boiler reheaters, the reliability of the connection between the clamping tube and the stainless steel tie plate directly affects the safe operation of the unit. Existing technologies generally employ dissimilar steel welding (the clamping tube is made of low-alloy heat-resistant steel, and the tie plate is made of austenitic stainless steel). This method has the following inherent drawbacks: the high heat input during welding leads to high residual stress in the fusion line region. Under frequent start-ups and shutdowns, and rapid load increases and decreases, the alternating stress continuously accumulates, promoting crack initiation. The difference in the linear expansion coefficients of dissimilar steels causes the heat-affected zone of the weld to be subjected to cyclic shear stress, accelerating crack propagation. Long-term high-temperature operation causes pearlite spheroidization in the clamping tube, reducing the toughness of the weld heat-affected zone and further weakening its crack resistance.

[0003] Therefore, how to solve the leakage problem of the clamping tube of the subcritical boiler screen reheater has become a technical problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0004] This invention provides a method, apparatus, and equipment for preventing leakage of clamping tubes in subcritical boiler screen reheaters, which solves the defect that leakage is prone to occur during welding of clamping tubes in subcritical boiler screen reheaters in the prior art.

[0005] In a first aspect, the present invention provides a method for preventing leakage of the clamping tubes of a subcritical boiler screen-type reheater, comprising:

[0006] Release the dissimilar steel welding connection between the clamping tube and the pull plate;

[0007] A non-welded mechanical isolation is formed by assembling a pipe ring on the outer wall of the clamping pipe, and the pull plate is welded and fixed to the outer wall of the pipe ring to complete the reconstruction of the stress transmission path;

[0008] After the reconstruction is completed, a two-factor monitoring mechanism for the spherical deterioration of the clamping tube and the temperature fluctuation of the reheater screen is established.

[0009] Based on the aforementioned dual-factor monitoring mechanism, monitoring data is collected to dynamically trigger pre-adjustment of combustion parameters and preventive replacement of pipelines;

[0010] Periodically analyze leakage-related events to optimize coal blending and maintenance strategies.

[0011] The method for preventing leakage of clamping tubes in a subcritical boiler reheater according to the present invention further includes:

[0012] The assembly gap of the tube ring is designed based on the thermal expansion characteristics of the clamping tube;

[0013] Based on the assembly gap, a high-temperature resistant and fretting-wear resistant layer is integrated into the inner wall of the tube ring to reduce residual stress in the tie plate-tube ring weld.

[0014] According to the present invention, a method for preventing leakage of clamping tubes in a subcritical boiler screen reheater is provided, wherein the execution of the dual-factor monitoring mechanism includes:

[0015] During the planned maintenance period, samples of the clamping tube were cut and tested for spheroidization grade and mechanical properties to obtain the spheroidization degradation rate.

[0016] The temperature gradient and fluctuation frequency of the reheater tube wall are collected in real time to obtain the intensity of temperature fluctuation;

[0017] When the spheroidization degradation rate is positively correlated with the intensity of temperature fluctuation, a pipeline replacement warning is activated.

[0018] According to the present invention, a method for preventing leakage of clamping tubes in a subcritical boiler screen-type reheater is provided, wherein the combustion parameter pre-adjustment includes:

[0019] Predict the heat load distribution of the reheater based on load change trends;

[0020] Based on the aforementioned heat load distribution, the burner sway angle and air distribution ratio are adjusted in advance to balance the tube screen temperature, and the desuperheating water self-locking program is activated to forcibly limit the amount of desuperheating water input under emergency overheating conditions.

[0021] According to the present invention, a method for preventing leakage of clamping tubes in a subcritical boiler reheater includes preventative replacement of the pipes.

[0022] Construct a three-dimensional evaluation model of clamping tube position, degradation degree, and runtime;

[0023] Using the aforementioned three-dimensional evaluation model, high-leakage-risk pipe sections are identified and a priority replacement sequence is generated;

[0024] During the maintenance window, replace pipe sections in batches according to the priority replacement sequence and re-inspect assembly gaps.

[0025] According to the present invention, a method for preventing leakage of clamping tubes in a subcritical boiler reheater includes the following: periodic analysis of leakage-related events and reverse optimization of coal blending and maintenance strategies.

[0026] Establish a causal graph by collecting historical overheating events, coal quality data, and leakage locations;

[0027] Based on the causal graph, the threshold values ​​of the thermal parameters for coal blending and combustion are revised, the combustion adjustment rule library is updated, and the information is synchronized to the operator's terminal.

[0028] According to the present invention, a method for preventing leakage of the clamping tube of a subcritical boiler screen reheater includes, before releasing the dissimilar steel welding connection between the clamping tube and the pull plate:

[0029] Non-destructive testing is performed on the entire surface of the clamping tube to locate areas with dense defects.

[0030] Assess the remaining lifetime of the defect-intensive areas and assign remediation priorities;

[0031] Before assembling the pipe ring, critically defective pipe sections are replaced and repaired according to the aforementioned priority.

[0032] The method for preventing leakage of clamping tubes in a subcritical boiler reheater according to the present invention further includes:

[0033] An array of acoustic emission sensors is deployed in the weld area of ​​the clamped pipe to analyze the characteristic frequency of crack propagation in real time and locate the leakage risk point.

[0034] When the characteristic frequency exceeds the threshold, the unit load is automatically reduced and the corresponding control panel is isolated.

[0035] Secondly, the present invention also provides a leak-proof system for the clamping tubes of a subcritical boiler screen-type reheater, comprising:

[0036] The welding stress root cause treatment module is used to remove the dissimilar steel welding connection between the clamping tube and the pull plate; a pipe ring is assembled on the outer wall of the clamping tube to form a non-welded mechanical isolation, and the pull plate is welded and fixed to the outer wall of the pipe ring to complete the stress transmission path reconstruction.

[0037] The dynamic leakage risk protection module is used to establish a two-factor monitoring mechanism for the spherical deterioration of the clamping tube and the temperature fluctuation of the reheater; based on the two-factor monitoring mechanism, monitoring data is collected to dynamically trigger the pre-adjustment of combustion parameters and the preventive replacement of pipelines.

[0038] The continuous iteration module for running strategies is used to periodically analyze leakage-related events and reverse-optimize coal blending and maintenance strategies.

[0039] Thirdly, the present invention also provides an electronic device, including a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the program to implement the leakage prevention method for the clamping tube of the subcritical boiler screen reheater as described above.

[0040] Fourthly, the present invention also provides a non-transitory computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the subcritical boiler screen reheater clamp tube leak prevention method as described above.

[0041] Fifthly, the present invention also provides a computer program product, including a computer program that, when executed by a processor, implements the subcritical boiler screen reheater clamping tube leak prevention method as described above.

[0042] This invention provides a method, device, and equipment for preventing leakage of the clamping tube in a subcritical boiler reheater with a screen. The method includes: removing the dissimilar steel welded connection between the clamping tube and the pull plate; assembling a pipe ring on the outer wall of the clamping tube to form a non-welded mechanical isolation; welding and fixing the pull plate to the outer wall of the pipe ring to reconstruct the stress transmission path; establishing a two-factor monitoring mechanism for the spheroidization and deterioration of the clamping tube and the temperature fluctuation of the reheater with a screen after reconstruction; collecting monitoring data based on the two-factor monitoring mechanism to dynamically trigger pre-adjustment of combustion parameters and preventative replacement of pipelines; periodically analyzing leakage-related events to reverse-optimize coal blending and maintenance strategies. By removing the weld, the stress transmission path is reconstructed, solving the problem of leakage easily caused by traditional welding methods. Furthermore, through two-factor monitoring and periodic analysis, early warning of faults can be provided, reducing the possibility of leakage. Attached Figure Description

[0043] To more clearly illustrate the technical solutions in this invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0044] Figure 1 This is a flowchart illustrating the method for preventing leakage of the clamping tube of a subcritical boiler screen reheater provided in this embodiment.

[0045] Figure 2 This is a schematic diagram of the connection structure of the clamping tube of the screen-type reheater provided in this embodiment;

[0046] Figure 3 This is a schematic diagram of the anti-leakage system for the clamping tubes of the subcritical boiler screen reheater provided in this embodiment;

[0047] Figure 4 This is a schematic diagram of the structure of the electronic device provided in this embodiment. Detailed Implementation

[0048] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0049] Figure 1 This is a flowchart illustrating the method for preventing leakage of the clamping tube of a subcritical boiler screen reheater provided in this embodiment.

[0050] like Figure 1 As shown in the figure, the method for preventing leakage of the clamping tube of a subcritical boiler screen reheater provided in this embodiment of the invention mainly includes the following steps:

[0051] 101. Release the dissimilar steel welding connection between the clamping tube and the pull plate.

[0052] Specifically, given the serious safety hazards posed by the dissimilar steel welding connection between the clamping tube 1 and the pull plate 2 of the existing screen-type reheater 4, a thorough investigation was conducted on the weld area connecting the clamping tube 1 and the stainless steel pull plate 2 of the subcritical boiler screen-type reheater 4 to determine the cause of the leak. The main procedures included:

[0053] Spheroidization rating test: Sampling of steel from the 4 clamping tubes and 1 cut tube of the screen reheater was carried out for spheroidization rating test. Tubes with heavy spheroidization were replaced to improve the mechanical properties of the tubes.

[0054] Pipe material verification: Use a spectrometer to verify the metal material of clamp tube 1 of the screen reheater 4 to check for any misuse of pipe material.

[0055] Coal blending management: Strengthen the management of fuel coal blending and combustion, and carry out refined coal blending and coal feeding according to the load curve to prevent metal structure deterioration and performance degradation caused by overheating of the screen reheater 4.

[0056] Combustion Adjustment Management: Strengthen boiler combustion adjustment management and soot blower management. Make more advance adjustments to prevent overheating of the reheater 4 and to prevent excessive input of desuperheating water. Strengthen combustion adjustment during boiler start-up and shutdown, and strictly control the heating and cooling rates to prevent large fluctuations in the temperature of the reheater 4.

[0057] Detailed inspection and maintenance: During maintenance, conduct inspection 4 on the reheater to check for problems such as bulging, cracks, wear, blow damage, misalignment, bending, coking, and aging of the pipes. If any problems are found, address them accordingly.

[0058] By cutting and sampling the clamping tube 1 for steel spheroidization rating and verification, and comprehensively analyzing the causes and formation mechanisms of cracks, it was concluded that the cracks at the fusion line of the weld connecting the clamping tube 1 and the stainless steel pull plate 2 of the reheater 4 are influenced by multiple factors and are the result of the combined effect of multiple forces. These factors include residual stress at the weld due to poor welding quality, inconsistent linear expansion coefficients due to welding dissimilar steels, shaking or impact of the pipe bank itself during operation, and aging of the pipe metal structure. These adverse factors are highly likely to cause alternating stress concentration in the fusion line area of ​​the weld during frequent unit start-ups and shutdowns, rapid load increases and decreases, use of unsuitable coal types, and excessive input of desuperheating water, resulting in cracks that continue to expand until leakage occurs.

[0059] To improve the leakage problem, the connection between clamping tube 1 and pull plate 2 was optimized, and the dissimilar steel welding connection between clamping tube 1 and pull plate 2 was eliminated.

[0060] 102. Assemble a pipe ring on the outer wall of the clamping pipe to form a non-welded mechanical isolation, and weld the pull plate to the outer wall of the pipe ring to complete the stress transmission path reconstruction.

[0061] After disassembling the dissimilar steel welding connection between clamping tube 1 and pull plate 2, the connection method between clamping tube 1 and pull plate 2 was optimized and modified, changing from a welded connection to a tube ring 3 type connection. For example... Figure 2 As shown, specifically, a tube ring 3 is assembled on the outer wall of the clamping tube 1 to form a non-welded mechanical isolation. The pull plate 2 is welded and fixed to the outer wall of the tube ring 3, thus reconstructing the stress transmission path. The inner diameter of the tube ring 3 is larger than the outer diameter of the clamping tube 1 to create a gap between the tube ring 3 and the clamping tube 1. The material of the tube ring 3 is the same as that of the pull plate 2, or it is a metal material with good weldability to the pull plate 2. The clamping tube 1 mainly serves to support and position the tube panel of the reheater 4. The pull plate 2 mainly prevents the tube panel from shaking and the clamping tube 1 from deforming. The tube ring 3 mainly serves to directly fit the tube ring 3 onto the clamping tube 1 of the reheater 4 and then weld it to the pull plate 2, effectively avoiding the original welding connection between the pull plate 2 and the clamping tube 1.

[0062] Through the implementation of a practical and feasible anti-leakage technology for the clamping tube 1 of the screen-type reheater 4, the connection between the clamping tube 1 and the pull plate 2 is no longer welded. Instead, it is changed to a tube ring 3 connection, with the tube ring 3 fitted onto the clamping tube 1 and the pull plate 2 welded onto the tube ring 3. The connection between the pull plate 2 and the clamping tube 1 is no longer welded, effectively eliminating the risk of leakage caused by factors such as alternating stress concentration at the weld fusion line of the connection between the clamping tube 1 and the pull plate 2. This is of great significance for ensuring the safe and stable operation of the clamping tube 1 of the screen-type reheater 4 in subcritical boilers.

[0063] Furthermore, by adding a pipe ring 3 as an intermediate connector, the welding point is transferred from the pressure-bearing clamping pipe 1 body to the non-pressure-bearing pipe ring 3, fundamentally eliminating residual stress and heat-affected zone damage caused by welding on the clamping pipe 1, thus protecting the structural integrity of the clamping pipe 1. The clearance fit formed between the pipe ring 3 and the clamping pipe 1 provides a buffer space for the different thermal expansion caused by temperature changes during operation, avoiding huge thermal stress caused by inconsistent expansion of dissimilar steels, and significantly reducing the risk of fatigue damage at the connection. By eliminating the root cause of stress concentration, this application greatly reduces the probability of cracks in the weld zone of the clamping pipe 1, thereby preventing boiler leakage and unplanned shutdowns caused by such defects, and ensuring the long-term safe and stable operation of the unit. In addition, since the welding is not on the main pipe, when it is necessary to replace the pull plate 2 or the pipe ring 3, there is no need to perform complex cutting and welding repairs on the pressure-bearing clamping pipe 1, simplifying maintenance work and reducing maintenance costs.

[0064] The core of this embodiment lies in the arrangement and application of the tube ring 3. The tube ring 3 is an independent, non-pressure-bearing annular component. Structurally, the tube ring 3 is fitted onto the outer circumferential surface of the clamping tube 1. The pull plate 2 is no longer directly welded to the clamping tube 1, but is firmly welded to the outer surface of the tube ring 3. In this way, the tube ring 3 acts as an "isolation sleeve," completely transferring the welding operation and the resulting stresses away from the pressure-bearing clamping tube 1 body, achieving an indirect connection between the pull plate 2 and the clamping tube 1. There are no weld points on the wall of the clamping tube 1, maximizing the protection of its structural integrity and the original properties of the material.

[0065] To further optimize the technical effect, this embodiment features a specific design for the fit between the coil 3 and the clamping tube 1. Specifically, the inner diameter of the coil 3 is designed to be larger than the outer diameter of the clamping tube 11. For example, for a clamping tube 1 with an outer diameter of 60 mm, the inner diameter of the coil 3 can be designed to be 62 mm, thus forming a radial gap between them. The size of this gap is typically between 0.5 mm and 2.0 mm, and the specific value can be determined by calculation based on the thermal expansion coefficient of the material, the operating temperature range, and the tube diameter. This fit is called a clearance fit in mechanical design. This pre-set gap plays a crucial role in buffering thermal expansion. When the boiler is running, both the clamping tube 1 and the assembly consisting of the coil 3 and the pull plate 2 will expand due to heat. Because the alloy steel material of the clamping tube 1 has a different thermal expansion coefficient than the stainless steel material of the coil 3 and the pull plate 2, their expansion amounts differ under the same temperature rise. The presence of this gap allows for a small, unconstrained relative radial displacement between the clamping tube 1 and the tube ring 3, thereby effectively absorbing and releasing the enormous stress caused by thermal expansion mismatch, preventing this stress from acting on the connection interface, and significantly reducing the risk of thermal fatigue damage to the structure.

[0066] Furthermore, this embodiment has also optimized the material selection. To ensure the quality and reliability of the welded connection between the pull plate 2 and the tube ring 3, preferably, the material of the tube ring 3 is the same as that of the pull plate 2. For example, if the pull plate 2 is made of 304 stainless steel, then the tube ring 3 is also made of 304 stainless steel. In this way, the welding between the two is a same-metal welding, the process is mature, the weld quality is high, and it can effectively avoid various metallurgical defects that may be caused by welding dissimilar steels. In other optional solutions, the material of the tube ring 3 can also be selected as other metal materials with good weldability to the material of the pull plate 2, such as two different grades of stainless steel with good weld compatibility. The core principle is to ensure that the welded joint between the pull plate 2 and the tube ring 3 has excellent mechanical properties and long-term stability.

[0067] In the specific modification or manufacturing process, the target installation location of the clamping tube 1 first needs to be surface-treated to ensure it is flat and smooth. Then, the pre-processed integral tube ring 3 with precise inner and outer diameters is inserted from one end of the clamping tube 1 and slid axially to the predetermined position. Finally, the end of the pull plate 2 is aligned with the outer wall of the tube ring 3, and it is firmly welded to the tube ring 3 using a mature welding process (such as tungsten inert gas welding). Throughout the entire process, the clamping tube 1 itself does not bear any welding heat input or microstructural changes, and its safety as a pressure-bearing component is fundamentally guaranteed.

[0068] With the connection structure of this embodiment, the fixing force and vibration load transmitted from the reheater 4 tube panel are uniformly applied to a large area of ​​the clamping tube 1 in the form of contact stress through the pull plate 2 and the tube ring 3, avoiding the dangerous situation of high stress concentration at the weld root in the prior art. The connection structure described in this embodiment can be applied to newly built boiler equipment, or to the technical renovation of existing boilers using old connection structures. By applying this embodiment, the reliability of the connection point of the clamping tube 1 of the reheater 4 can be significantly improved, and related leakage accidents can be eliminated, thereby ensuring the long-term safe, stable, and efficient operation of the entire generator unit. This connection structure is part of the reheater 4, which is installed in a subcritical boiler, forming a safe and reliable boiler system.

[0069] 103. After the reconstruction is completed, a two-factor monitoring mechanism for the spherical deterioration of the clamping tube and the temperature fluctuation of the reheater screen is established.

[0070] Specifically, after the reconstruction is completed, the reconstructed structure needs to be monitored. In this embodiment, a two-factor monitoring mechanism is selected: during the planned maintenance period, a sample of clamping tube 1 is cut off for joint testing of spheroidization level and mechanical properties to obtain the spheroidization degradation rate; the temperature gradient and fluctuation frequency of the reheater tube wall are collected in real time to obtain the temperature fluctuation intensity; when the spheroidization degradation rate and the temperature fluctuation intensity are positively correlated, the pipeline replacement early warning is activated.

[0071] During the planned overhaul of the unit, representative samples were taken from the left, middle, and right regions of the clamping tube 1 of the reheater 4. The spheroidization grade (such as pearlite spheroidization grade, carbide and grain size) was evaluated according to the "Steel Spheroidization Rating Inspection" standard. Simultaneously, parameters such as yield strength and tensile strength were obtained through mechanical property testing. By comparing with historical overhaul data, the increase in spheroidization grade and the decrease in mechanical properties per unit time were calculated to determine the spheroidization deterioration rate of clamping tube 1.

[0072] Temperature sensors arranged on the walls of the reheater 4 are used to collect real-time temperature data of the clamping tube 1 and surrounding tube panels, calculating the temperature gradient (such as the instantaneous temperature difference between tube walls at different locations) and fluctuation frequency (such as the number of times the temperature exceeds the threshold or experiences sudden rises or falls per unit time). Combined with combustion adjustment management requirements, and linked to operational data such as burner angle adjustment, desuperheating water input, and boiler start-up and shutdown heating / cooling rates, the intensity of temperature fluctuations is quantified (e.g., the greater the fluctuation amplitude and the higher the frequency, the higher the intensity value).

[0073] Establish a database linking the spheroidization degradation rate with the intensity of temperature fluctuations, and statistically analyze the trends of both (e.g., whether the spheroidization degradation rate accelerates synchronously when the intensity of temperature fluctuations increases). When the two show a significant positive correlation (e.g., increased temperature fluctuations lead to accelerated spheroidization degradation), trigger a pipeline replacement warning, such as replacing pipes with severe spheroidization, and formulate a replacement plan in advance.

[0074] By employing dual-factor linkage monitoring, the limitations of single-indicator monitoring are overcome, accurately identifying high leakage risks caused by the superposition of "spheroidization degradation + temperature fluctuations," avoiding misjudgment or omission due to a single factor. Based on the correlation between degradation rate and temperature fluctuations, early warnings are initiated, allowing for replacement before pipeline performance approaches or exceeds standards but before cracks occur, reducing unplanned downtime for emergency repairs and lowering the risk of safety accidents caused by leaks.

[0075] 104. Based on the dual-factor monitoring mechanism, monitoring data is collected to dynamically trigger pre-adjustment of combustion parameters and preventive replacement of pipelines.

[0076] Among them, the pre-adjustment of combustion parameters includes: predicting the heat load distribution of the reheater based on the load change trend; adjusting the burner swing angle and air distribution ratio in advance to balance the tube and screen temperature in combination with the heat load distribution, activating the desuperheating water self-locking program, and forcibly limiting the desuperheating water input under overheating emergency conditions.

[0077] Specifically, temperature and pressure sensors installed at the inlet and outlet of the reheater 4 and at key locations are used to collect steam parameters in real time. Simultaneously, a load forecasting model is used, combined with grid dispatch instructions and historical load curves of the unit, to predict the unit's load change trends in advance. By correlating load changes with steam parameters and based on heat transfer principles and unit operating experience, a heat load distribution prediction model is constructed to estimate the heat load distribution in different areas of the reheater 4 under different loads.

[0078] Based on the predicted heat load distribution, when the heat load in a certain area is too high, the automatic control system adjusts the corresponding burner angle to change the flame center position and reduce the heat absorption in that area. Simultaneously, it adjusts the primary and secondary air distribution ratios to optimize the combustion process, making the flame more uniform and stable, and balancing the tube and screen temperatures. For example, in a tangential combustion boiler, if the temperature in zone 4 of the reheater at a certain corner is too high, the burner angle at that corner is appropriately lowered to increase the secondary air ratio, enhance combustion disturbance, and reduce the local heat load.

[0079] In overheating emergency conditions, to prevent new problems such as water hammer and large fluctuations in steam temperature caused by excessive desuperheating water injection, the desuperheating water self-locking program is automatically activated when the wall temperature of tube 4 of the reheater is detected to rise rapidly and approach the alarm value. Through logic control, the opening of the desuperheating water regulating valve is limited, allowing only a small amount of desuperheating water to be injected slowly. At the same time, high-frequency monitoring of steam temperature, flow rate, and tube wall temperature is strengthened. Combined with the combustion adjustment effect, the steam temperature is gradually stabilized to avoid abnormal thermal stress in the tube and screen caused by improper operation of the desuperheating water.

[0080] The preventive replacement of pipelines includes: constructing a three-dimensional evaluation model of clamping pipe location, degree of deterioration, and operating time; using the three-dimensional evaluation model to identify high-leaking-risk pipe sections and generate a priority replacement sequence; and replacing pipe sections in batches according to the priority replacement sequence during the maintenance window and re-inspecting the assembly clearance.

[0081] Specifically, historical maintenance data for clamping tube 1 is collected, including the spheroidization level, mechanical performance test results, and replacement records for each maintenance; real-time operating data, such as tube wall temperature, steam pressure, and operating time; and the spatial location information of clamping tube 1 in the screen-type reheater 4. Using big data analysis and machine learning algorithms, a three-dimensional evaluation model is constructed, with the location of clamping tube 1 as the spatial dimension, the degree of degradation (comprehensive spheroidization level and mechanical performance degradation index) as the state dimension, and the operating time as the time dimension, to quantify the degree of degradation risk of clamping tube 1 at different locations during different operating stages.

[0082] Real-time operational data is continuously input into the 3D assessment model, which identifies high-leakage-risk pipe sections based on preset risk thresholds. Based on the risk level, and considering factors such as maintenance resources and downtime, an optimization algorithm generates a priority replacement sequence. For example, pipe sections with extremely high risk and located in easily maintainable positions are prioritized for replacement; for pipe sections with relatively low risk but located in critical structural positions, a reasonable replacement sequence is determined after comprehensive consideration.

[0083] During the unit maintenance window, high-risk pipe sections are replaced in batches strictly according to the priority replacement sequence. During the replacement process, maintenance procedures are strictly followed to ensure that the new pipe sections meet material and specification requirements and that welding quality is up to standard. After replacement, high-precision measuring tools are used to re-inspect the assembly gaps to ensure they meet design standards and prevent localized wear and stress concentration caused by improper assembly, which could affect the long-term operational safety of the pipe panels.

[0084] 105. Periodically analyze leakage-related events and reverse-optimize coal blending and maintenance strategies.

[0085] Specifically, historical overheating events, coal quality data, and leakage locations can be collected to establish a causal graph; based on the causal graph, the threshold values ​​of coal blending and combustion thermal parameters can be revised, the combustion adjustment rule library can be updated, and the data can be synchronized to the operator's terminal.

[0086] Regularly (e.g., quarterly or after each unit has completed a major overhaul) review the relevant historical data of clamp tube 1 of the reheater 4: First, collect historical overheating event records, including the time of overheating, duration, location of the affected tube section, highest temperature value, and corresponding combustion conditions; second, summarize the coal quality data of the same period, such as key indicators such as coal type ratio, calorific value, volatile matter, ash content, and sulfur content; third, organize the leakage event archive, clarifying the specific location of clamp tube 1 for each leakage, crack morphology (e.g., transverse crack, longitudinal crack), spheroidization deterioration level before leakage, and temperature fluctuation records.

[0087] By using data correlation analysis tools, overheating events, coal quality parameter fluctuations, and leakage locations are matched in multiple dimensions to identify potential causal chains such as "specific coal quality (e.g., excessively high proportion of high volatile coal) → unstable combustion → local overheating → accelerated spheroidization of clamping tubes → leakage". A visual causal map is constructed, and the influence weight of each factor on leakage risk is marked (e.g., the contribution of corrosion caused by high-sulfur coal to leakage).

[0088] Based on the causal graph, the threshold values ​​of thermal parameters for coal blending are revised for high-risk causal chains. For example, if the graph shows that "when the proportion of a certain type of bituminous coal exceeds 30% and the volatile matter content is >25%, the overheating event in the left area of ​​the screen reheater 4 increases by 40%, and the leakage rate of the clamping tube 1 increases accordingly", then the threshold value for the proportion of that type of coal is lowered to 25%, and the volatile matter control threshold is tightened to 22%.

[0089] Meanwhile, based on the correlation between the amount of desuperheating water added and overheating under specific coal quality in the graph, additional details such as "when high ash coal is co-fired, the desuperheating water adjustment rate should be reduced by 10% to avoid sudden temperature changes" were added; for areas with frequent leaks, special clauses such as "the sampling frequency of clamping pipe 1 in this area is increased to once every six months" and "priority is given to replacing pipe sections of the same batch material that have been in operation for more than 80,000 hours" were added to the maintenance strategy.

[0090] Finally, the revised thermal parameter thresholds and the updated combustion adjustment rule library will be synchronized to the operator's terminal (such as the DCS system operation interface or mobile operation guidance APP) through the unit operation management system to ensure that parameter warnings and operation guidance are delivered in real time.

[0091] Furthermore, based on the above embodiments, this embodiment also includes: designing the assembly gap of the tube ring 3 according to the thermal expansion characteristics of the clamping tube 1; and integrating a high-temperature resistant and fretting wear-resistant layer on the inner wall of the tube ring 3 based on the assembly gap, and performing residual stress reduction treatment on the pull plate-tube ring weld.

[0092] Specifically, firstly, data on the coefficient of thermal expansion of the material used for the clamping tube 1 of the reheater 4 at different temperatures are collected. Combined with the operating temperature range of the clamping tube 1 during normal unit operation (e.g., from ambient temperature at startup to high temperature during operation), the thermal expansion of the clamping tube 1 under different operating conditions is calculated. Simultaneously, considering the assembly relationship between the tube coil 3 and the pull plate 2, and the surrounding tube panel, as well as the rate of temperature change during unit start-up and shutdown, the required movement space for the tube coil 3 during thermal expansion and contraction is determined. Following the principle that "the reserved gap must cover the maximum thermal expansion and avoid vibration and friction caused by excessive gaps," the assembly gap values ​​between the tube coil 3 and the pull plate 2, and between the tube coil 3 itself, are designed.

[0093] Based on the designed assembly gaps, a high-temperature resistant and wear-resistant material (such as a nickel-based alloy coating or ceramic composite material) is selected as the anti-fretting wear layer. Using plasma spraying or laser cladding technology, this material layer is uniformly sprayed or clad in key areas on the inner wall of the tube coil 3 that come into contact with other components (such as the area in contact with the pull plate 2, and the sides of the tube coil 3 that are close to each other), ensuring uniform coating thickness and a strong bond with the substrate of the tube coil 3. After coating, the surface is polished to ensure flatness and avoid localized stress concentration or abnormal gaps caused by coating protrusions.

[0094] After the welding of the pull plate 2 and the pipe ring 3 is completed, the weld and heat-affected zone are treated with localized high-temperature tempering. The weld area is heated to a specific temperature and held for a certain period of time, then slowly cooled to eliminate residual stress generated during the welding process. For welds with complex structures, ultrasonic impact treatment can also be used as an auxiliary method. High-frequency mechanical impact causes plastic deformation of the weld surface, offsetting some of the residual stress. After the treatment is completed, the residual stress in the weld area is detected using stress testing equipment to ensure that the stress value is controlled within a safe range.

[0095] The reasonable assembly gap design avoids the squeezing deformation of the clamping tube 1 due to insufficient space during thermal expansion, and prevents damage to the tube wall or cracking of the weld due to excessive squeezing between the tube ring 3 and the pull plate 2 or other tube rings 3. Structurally, this reduces the risk of leakage caused by thermal expansion. The high-temperature resistant and fretting wear-resistant layer on the inner wall of the tube ring 3 effectively resists the fretting friction caused by vibration and thermal expansion and contraction during operation, reducing the amount of wear on the tube wall and avoiding leakage problems such as tube wall thinning and perforation caused by wear, thus extending the service life of the clamping tube 1.

[0096] Furthermore, based on the above embodiments, this embodiment further includes the following steps before releasing the dissimilar steel welding connection between the clamping tube 1 and the pull plate 2: performing non-destructive testing on the entire surface of the clamping tube 1 to locate areas with dense defects; assessing the remaining lifespan of the areas with dense defects and marking the treatment priority; and replacing and repairing critical defective pipe sections according to priority before assembling the pipe ring 3.

[0097] Specifically, before disconnecting the dissimilar steel welded connection between clamping tube 1 and pull plate 2, a combination of ultrasonic testing and penetrant testing is used to inspect the entire surface of clamping tube 1. Ultrasonic testing focuses on detecting volumetric defects such as cracks and delamination within the tube wall. By adjusting the probe angle and frequency, it ensures accurate scanning of stress concentration areas such as the bends in the tube coil 3 and the heat-affected zone of the weld with pull plate 2. Penetrant testing targets surface defects such as fine cracks and pinholes on the tube surface. By applying penetrant, cleaning agent, and developer, the defect morphology is clearly displayed. Based on the inspection data, image processing technology is used to create a defect distribution heatmap, marking areas where the number, size, and density of defects exceed preset thresholds as defect-dense areas.

[0098] For the identified areas with dense defects, the remaining safe operating time of the area was calculated using a remaining life assessment model, taking into account the high-temperature mechanical properties of the clamping pipe 1 material, historical operating data, and defect propagation patterns. Based on the assessment results, areas with a remaining life of less than 10,000 hours and defects located in critical stress areas of pipe coil 3 (such as near welds or bends) were marked as "Level 1 Priority" and required immediate handling; areas with a remaining life of 10,000-20,000 hours or defects located in non-critical areas were marked as "Level 2 Priority" and could be handled during this maintenance; areas with a remaining life of more than 20,000 hours were marked as "Level 3 Priority" and included in routine monitoring.

[0099] According to the treatment priority, critical defective pipe sections corresponding to the first and second priority levels are replaced and repaired. When cutting defective pipe sections, ensure a safe distance between the cut and the edge of the defect-dense area to avoid residual hidden dangers; the new pipe section is made of heat-resistant steel matching the original pipe material, and is butt-welded using argon arc welding. After welding, the weld is subjected to non-destructive testing to ensure that there are no new defects such as incomplete penetration or cracks. After the repair is completed, the straightness and outer diameter tolerance of the pipe section are measured to ensure that the assembly gap with the adjacent pipe ring 3 meets the design standards, laying the foundation for the subsequent assembly of pipe ring 3.

[0100] Furthermore, this embodiment also includes: deploying an acoustic emission sensor array in the weld area of ​​clamping pipe 1 to analyze the characteristic frequency of crack propagation in real time and locate the leakage risk point; when the characteristic frequency exceeds the threshold, automatically reducing the unit load and isolating the corresponding pipe panel.

[0101] Specifically, in areas prone to cracking, such as the dissimilar steel weld area between clamping pipe 1 and pull plate 2, and the butt weld of pipe sections, an acoustic emission sensor array is installed at a density of one sensor every 50mm. The sensor selection must be suitable for high-temperature environments, and it must be tightly bonded to the pipe wall using a high-temperature resistant coupling agent to ensure stable signal transmission. After deployment, a simulated crack signal generator (e.g., applying mechanical impact at a known crack location) is used for calibration. The characteristic frequency ranges corresponding to different crack propagation stages (e.g., microcrack initiation, steady-state propagation, and rapid propagation) are recorded, and the calibration data is entered into the monitoring system.

[0102] The monitoring system acquires acoustic emission signals from the sensor array in real time, filters out interference signals such as unit vibration and medium flow using a filtering algorithm, and extracts the characteristic frequencies generated by crack propagation. Combining the time difference of signal arrival from each sensor, the system uses triangulation to calculate the location of the crack, generates a leakage risk point distribution map, and simultaneously displays the weld number, operating time, and historical defect records corresponding to each risk point.

[0103] When the system detects that the characteristic frequency of a certain area has exceeded a preset threshold for a continuously preset duration, and the located risk point coincides with a historically dense area of ​​defects, an automatic response mechanism is triggered: First, a load reduction command is sent to the unit's DCS system to gradually reduce the unit load from the current value, thereby reducing the heat load and pressure on the corresponding pipe panel; second, the inlet and outlet valves of the pipe panel are closed through control logic to isolate it from other pipe panels and prevent media leakage and spread. Simultaneously, a pop-up window on the operator's terminal displays the location of the risk point, characteristic frequency data, and handling suggestions to assist in manual confirmation and subsequent maintenance arrangements.

[0104] Based on the same general inventive concept, this invention also protects a leak-proof system for the clamping tube of a subcritical boiler screen reheater. The leak-proof system for the clamping tube of a subcritical boiler screen reheater described below can be referred to in correspondence with the leak-proof method for the clamping tube of a subcritical boiler screen reheater described above.

[0105] Figure 3 This is a schematic diagram of the anti-leakage system for the clamping tube of the subcritical boiler screen reheater provided in this embodiment.

[0106] like Figure 3 As shown in the figure, this embodiment provides a leak-proof system for the clamping tubes of a subcritical boiler screen-type reheater, comprising:

[0107] The welding stress root cause treatment module 301 is used to remove the dissimilar steel welding connection between the clamping tube and the pull plate; a pipe ring is assembled on the outer wall of the clamping tube to form a non-welded mechanical isolation, and the pull plate is welded and fixed to the outer wall of the pipe ring to complete the stress transmission path reconstruction.

[0108] The dynamic leakage risk protection module 302 is used to establish a two-factor monitoring mechanism for the balling and deterioration of the clamping tube and the temperature fluctuation of the reheater; based on the two-factor monitoring mechanism, monitoring data is collected to dynamically trigger the pre-adjustment of combustion parameters and the preventive replacement of pipelines;

[0109] The continuous iteration module 303 is used to periodically analyze leakage-related events and reverse-optimize coal blending and maintenance strategies.

[0110] Figure 4 This is a schematic diagram of the structure of the electronic device provided in this embodiment.

[0111] like Figure 4As shown, the electronic device may include a processor 410, a communication interface 420, a memory 430, and a communication bus 440. The processor 410, communication interface 420, and memory 430 communicate with each other via the communication bus 440. The processor 410 can call logical instructions from the memory 430 to execute a leak-proof method for the clamping tubes of a subcritical boiler screen reheater.

[0112] Furthermore, the logical instructions in the aforementioned memory 430 can be implemented as software functional units and, when sold or used as independent products, can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention, or the part that contributes to the prior art, or a part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of the present invention. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0113] On the other hand, the present invention also provides a computer program product, which includes a computer program that can be stored on a non-transitory computer-readable storage medium. When the computer program is executed by a processor, the computer is able to execute the subcritical boiler screen reheater clamp tube anti-leakage method provided by the above methods.

[0114] In another aspect, the present invention also provides a non-transitory computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the method for preventing leakage of the clamping tube of a subcritical boiler screen reheater provided by the methods described above.

[0115] The device embodiments described above are merely illustrative. The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the modules can be selected to achieve the purpose of this embodiment according to actual needs. Those skilled in the art can understand and implement this without any creative effort.

[0116] Through the description of the above embodiments, those skilled in the art can clearly understand that each embodiment can be implemented by means of software plus a necessary general hardware platform, or of course, by hardware. Based on this understanding, the essence of the above technical solution or the part that contributes to the existing technology can be embodied in the form of a software product. The computer software product can be stored in a computer-readable storage medium, such as ROM / RAM, a magnetic disk, an optical disk, etc., and includes a number of instructions for enabling a computer device (which can be a personal computer, a server, or a network device, etc.) to execute the methods described in each embodiment or certain parts of the embodiments.

[0117] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preventing leakage of clamping tubes in a subcritical boiler screen-type reheater, characterized in that, include: Release the dissimilar steel welding connection between the clamping tube and the pull plate; A non-welded mechanical isolation is formed by assembling a pipe ring on the outer wall of the clamping pipe, and the pull plate is welded and fixed to the outer wall of the pipe ring to complete the reconstruction of the stress transmission path; After the reconstruction is completed, a two-factor monitoring mechanism for the spherical deterioration of the clamping tube and the temperature fluctuation of the reheater screen is established. Based on the aforementioned dual-factor monitoring mechanism, monitoring data is collected to dynamically trigger pre-adjustment of combustion parameters and preventive replacement of pipelines; Periodically analyze leakage-related events to optimize coal blending and maintenance strategies.

2. The method for preventing leakage of the clamping tubes of a subcritical boiler screen-type reheater according to claim 1, characterized in that, Also includes: The assembly gap of the tube ring is designed based on the thermal expansion characteristics of the clamping tube; Based on the assembly gap, a high-temperature resistant and fretting-wear resistant layer is integrated into the inner wall of the tube ring to reduce residual stress in the tie plate-tube ring weld.

3. The method for preventing leakage of the clamping tubes of a subcritical boiler screen-type reheater according to claim 1, characterized in that, The execution of the two-factor monitoring mechanism includes: During the planned maintenance period, samples of the clamping tube were cut and tested for spheroidization grade and mechanical properties to obtain the spheroidization degradation rate. The temperature gradient and fluctuation frequency of the reheater tube wall are collected in real time to obtain the intensity of temperature fluctuation; When the spheroidization degradation rate is positively correlated with the intensity of temperature fluctuation, a pipeline replacement warning is activated.

4. The method for preventing leakage of the clamping tube of a subcritical boiler screen-type reheater according to claim 3, characterized in that, The pre-adjustment of combustion parameters includes: Predict the heat load distribution of the reheater based on load change trends; Based on the aforementioned heat load distribution, the burner sway angle and air distribution ratio are adjusted in advance to balance the tube screen temperature, and the desuperheating water self-locking program is activated to forcibly limit the amount of desuperheating water input under emergency overheating conditions.

5. The method for preventing leakage of the clamping tube of a subcritical boiler screen-type reheater according to claim 1, characterized in that, The preventative replacement of the pipeline includes: Construct a three-dimensional evaluation model of clamping tube position, degradation degree, and runtime; Using the aforementioned three-dimensional evaluation model, high-leakage-risk pipe sections are identified and a priority replacement sequence is generated; During the maintenance window, replace pipe sections in batches according to the priority replacement sequence and re-inspect assembly gaps.

6. The method for preventing leakage of the clamping tube of a subcritical boiler screen-type reheater according to claim 1, characterized in that, The periodic analysis of leakage-related events, and the reverse optimization of coal blending and maintenance strategies, include: Establish a causal graph by collecting historical overheating events, coal quality data, and leakage locations; Based on the causal graph, the threshold values ​​of the thermal parameters for coal blending and combustion are revised, the combustion adjustment rule library is updated, and the information is synchronized to the operator's terminal.

7. The method for preventing leakage of the clamping tubes of a subcritical boiler screen-type reheater according to claim 1, characterized in that, Before releasing the dissimilar steel welding connection between the clamping tube and the pull plate, the following is also included: Non-destructive testing is performed on the entire surface of the clamping tube to locate areas with dense defects. Assess the remaining lifetime of the defect-intensive areas and assign remediation priorities; Before assembling the pipe ring, critically defective pipe sections are replaced and repaired according to the aforementioned priority.

8. The method for preventing leakage of the clamping tube of a subcritical boiler screen-type reheater according to claim 1, characterized in that, Also includes: An array of acoustic emission sensors is deployed in the weld area of ​​the clamped pipe to analyze the characteristic frequency of crack propagation in real time and locate the leakage risk point. When the characteristic frequency exceeds the threshold, the unit load is automatically reduced and the corresponding control panel is isolated.

9. A leak-proof system for clamping tubes of a subcritical boiler screen-type reheater, characterized in that, include: The welding stress root cause treatment module is used to remove the dissimilar steel welding connection between the clamping tube and the pull plate; a pipe ring is assembled on the outer wall of the clamping tube to form a non-welded mechanical isolation, and the pull plate is welded and fixed to the outer wall of the pipe ring to complete the stress transmission path reconstruction. The dynamic leakage risk protection module is used to establish a two-factor monitoring mechanism for the spherical deterioration of the clamping tube and the temperature fluctuation of the reheater; based on the two-factor monitoring mechanism, monitoring data is collected to dynamically trigger the pre-adjustment of combustion parameters and the preventive replacement of pipelines. The continuous iteration module for running strategies is used to periodically analyze leakage-related events and reverse-optimize coal blending and maintenance strategies.

10. An electronic device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that, When the processor executes the program, it implements the leak prevention method for the clamping tube of the subcritical boiler screen reheater as described in any one of claims 1 to 8.

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