Water-cooled wall tube high-precision welding processing technology based on real-time temperature control monitoring

Abstract

The invention relates to the technical field of welding, in particular to a water-cooled wall tube high-precision welding processing technology based on real-time temperature control monitoring, the cross section of a water-cooled wall tube is divided into a plurality of welding areas, corresponding detection images are collected, and wall tube characterization parameters are calculated based on the wall tube thickness and the wall tube groove angle; heating the pre-welded water-cooled wall tube, acquiring a weld infrared image, acquiring a wall tube temperature based on the weld infrared image, calculating a water film characteristic parameter so as to judge whether the water-cooled wall tube meets a water film forming requirement or not, and judging a reason that the water-cooled wall tube does not meet the water film forming requirement based on a water film deviation parameter; adjusting a pretreatment parameter or an interception length based on the water film deviation parameter, and adjusting a water film deviation threshold based on the dyeing deviation parameter; and obtaining the temperature rise rate of the water wall tube to judge whether the water film thickness is qualified. According to the invention, the accuracy of the water wall tube high-precision welding processing technology based on real-time temperature control monitoring is improved.

Description

Technical Field

[0001] This invention relates to the field of welding technology, and in particular to a high-precision welding process for water-cooled wall tubes based on real-time temperature control monitoring. Background Technology

[0002] As a core pressure-bearing component of power plant boilers, the welding precision of water-cooled wall tubes directly affects the safe operation and service life of the boiler. Welding defects are difficult to identify and warn of in real time. During the welding process of water-cooled wall tubes, the formation quality of the water film on the inner wall of the tube directly affects the stability of the welding temperature field and the quality of the weld formation. If the water film thickness is uneven, discontinuous, or missing, it will lead to local overheating of the tube wall, causing boiling heat transfer deterioration, which in turn will cause the tube wall to burn out or the weld defects to worsen. In view of the technical problems existing in the current water-cooled wall tube welding process, such as insufficient risk classification and control, inaccurate judgment of water film quality, lack of real-time temperature control, and blind adjustment of pretreatment parameters, it is urgent to develop a high-precision welding process based on real-time temperature control monitoring. Through precise zonal detection, risk classification, closed-loop control of water film quality, and real-time parameter adjustment, it can meet the needs of efficient, safe, and long-term operation of thermal equipment.

[0003] Chinese Patent Application Publication No. CN118720333A discloses a weld structure and welding process suitable for narrow-gap water-cooled wall tube panels, relating to the field of boiler manufacturing technology. The invention includes a bevel-shaped gap between adjacent water-cooled wall tubes, with weld joints located on the sides of the adjacent tubes. These weld joints are distributed on the upper side of the bevel-shaped gap and are connected to it. The bevel-shaped gap includes either a V-shaped bevel or a U-shaped bevel. In addition to the existing weld joints, the adjacent water-cooled wall tubes are considered as a whole. The gap between the tubes is machined into a bevel shape and welded together with the weld joints. This increases the weld thickness and safety factor at the tangent point and facilitates radiographic testing. It solves the technical problem that when the gap between adjacent water-cooled wall tubes is small, the difficulty in observation, welding, and flaw detection makes it difficult to ensure the welding quality at the tangent point, posing a significant threat to the safe operation of the unit.

[0004] The existing technology also has the following problems: The existing technology does not take into account the analysis of the characteristics of the water film under the condition of heating the water-cooled wall tube to detect the heat absorption capacity of the water-cooled wall tube in actual application, and does not take into account the situation of not meeting the conditions to adjust the welding process in time to improve the welding accuracy. Summary of the Invention

[0005] To address this, the present invention provides a high-precision welding process for water-cooled wall tubes based on real-time temperature control monitoring. This process overcomes the problem in existing technologies that do not consider analyzing the characteristics of the water film under heating conditions to detect the heat absorption capacity of the water-cooled wall tubes in practical applications, and promptly adjust the welding process to improve welding precision in cases where conditions are not met.

[0006] To achieve the above objectives, the present invention provides a high-precision welding process for water-cooled wall tubes based on real-time temperature control monitoring, comprising: The cross-section of the water-cooled wall tube is divided into several welding areas and corresponding detection images are acquired. The wall tube thickness and wall tube bevel angle of each welding area are calculated respectively. Based on the wall tube thickness and the wall tube bevel angle, the wall tube characterization parameters are calculated. Based on the comparison results between the wall tube characterization parameters and the wall tube standard parameters, the risk trend and pretreatment parameters of the water-cooled wall tube, as well as the cutting length for pre-welding water-cooled wall tubes with strong welding risks, are determined. The pre-welded water-cooled wall tube is heated and the weld infrared image is acquired. The wall tube temperature is obtained based on the weld infrared image. The water film characteristic parameters of a single welded flow section are calculated based on the wall tube temperature, and it is determined whether the water-cooled wall tube meets the water film formation requirements. In response to the water-cooled wall tube not meeting the water film formation requirements, the reason why the water-cooled wall tube does not meet the water film formation requirements is determined based on the water film deviation parameters. Fluorescent tracers are introduced into the water-cooled wall tube and staining images of the inside of the water-cooled wall tube are collected. Staining characterization parameters are generated based on the staining brightness and staining length obtained from the staining images. Based on the staining characterization parameters, it is determined whether the reason why the water-cooled wall tube does not meet the requirements for water film formation is accurate. If the reason why the water-cooled wall tube does not meet the water film formation requirements is accurate, adjust the pretreatment parameters or the cutting length based on the water film deviation parameters. If the reason why the water-cooled wall tube does not meet the water film formation requirements is inaccurate, adjust the water film deviation threshold based on the staining deviation parameters. In response to the water-cooled wall tube meeting the water film formation requirements, the water-cooled wall tube is welded, and the temperature rise rate of the water-cooled wall tube is obtained to determine whether the water film thickness is qualified. In response to the water film thickness being unqualified, the temperature rise deviation parameter is calculated based on the temperature rise rate and the temperature rise rate threshold to adjust the water film characteristic threshold.

[0007] Furthermore, the process of dividing the cross-section of the water-cooled wall tube into several welding areas and acquiring corresponding detection images, and calculating the wall tube thickness and wall tube bevel angle for each welding area, includes: The cross-section of the water-cooled wall tube is divided into several welding areas and detection images corresponding to each welding area are acquired. Each welding area includes at least one continuous welding section. Collect several wall thicknesses and wall bevel angles in each of the aforementioned welding areas; The mean thickness of each of the wall tubes is calculated as the thickness factor corresponding to each of the welding areas; The mean value of the bevel angle of each of the aforementioned pipe walls is calculated as the angle factor corresponding to each of the aforementioned welding areas.

[0008] Furthermore, the risk trend of the water-cooled wall tube is determined based on the comparison results between the wall tube characterization parameters and the wall tube standard parameters, wherein... The weighted sum of the thickness factor and the angle factor is determined to be a wall tube characterization parameter; The wall tube deviation parameter is the absolute value of the difference between the wall tube characterization parameter and the wall tube standard parameter; If the wall tube deviation parameter is greater than or equal to the first wall tube deviation threshold and less than or equal to the second wall tube deviation threshold, then the risk trend of the water-cooled wall tube is determined to be weak welding risk. If the wall tube deviation parameter is less than the first wall tube deviation threshold or greater than the second wall tube deviation threshold, the risk trend of the water-cooled wall tube is determined to be strong welding risk.

[0009] Furthermore, the process of determining the pretreatment parameters and the cut length for pre-welding of water-cooled wall tubes with high welding risk based on the comparison results between the wall tube characterization parameters and the wall tube standard parameters includes, The preprocessing parameter is determined to be the product of the first ratio and the standard preprocessing parameter; The cut length is determined to be the product of the total length of the water-cooled wall tube with high welding risk and the second ratio. Wherein, the first ratio is the ratio of the wall tube characterization parameter to the wall tube standard parameter, the second ratio is the sum of the ratio of the wall tube standard parameter and the ratio of the wall tube characterization parameter, and the pretreatment parameters include welding current and welding speed.

[0010] Furthermore, the process of calculating the water film characteristic parameters of a single welded flow section based on the wall pipe temperature obtained from the weld infrared image includes, The difference between the minimum and maximum circumferential wall tube temperatures of the same weld seam is calculated as the wall temperature difference. The standard deviation of the wall temperature difference of several welds is calculated as a characteristic parameter of the water film.

[0011] Furthermore, based on the characteristic parameters of the water film, it is determined whether the water-cooled wall tube meets the requirements for water film formation, among which, If the water film characteristic parameters are greater than the water film characteristic threshold, the water-cooled wall tube is determined to not meet the requirements for water film formation. If the water film characteristic parameters are less than or equal to the water film characteristic threshold, then the water-cooled wall tube is determined to meet the water film formation requirements.

[0012] Furthermore, the process of determining the reasons why the water-cooled wall tube does not meet the water film formation requirements based on the water film deviation parameter includes, The absolute value of the difference between the water film characteristic parameters and the water film characteristic threshold is determined as the water film deviation parameter; If the water film deviation parameter is less than or equal to the water film deviation threshold, the reason why the water-cooled wall tube does not meet the water film formation requirements is that there is weld bead at the weld. If the water film deviation parameter is greater than the water film deviation threshold, the reason why the water-cooled wall tube does not meet the water film formation requirements is that the weld is not fully welded.

[0013] Furthermore, the process of obtaining staining brightness and staining length from the staining image to generate staining characterization parameters includes, Acquire dyeing images of the weld seam and obtain the dyeing brightness and dyeing length of each dyeing image; The ratio of the mean of several staining brightness values ​​to the reference staining brightness value is determined as the brightness factor; The length factor is determined by the ratio of the mean of several staining lengths to the baseline staining length. The weighted sum of the brightness factor and the length factor is determined to be the staining characterization parameter.

[0014] Furthermore, the accuracy of determining the reasons why the water-cooled wall tubes do not meet the requirements for water film formation based on staining characterization parameters is as follows: If the reason why the water-cooled wall tube does not meet the water film formation requirements is that there is weld bead at the weld, and the staining characterization parameter is greater than the staining characterization threshold, then the reason for the water-cooled wall tube not meeting the water film formation requirements is inaccurate. If the reason why the water-cooled wall tube does not meet the water film formation requirements is that the weld is not fully welded, and the staining characterization parameter is less than the staining characterization threshold, then the reason for the water-cooled wall tube not meeting the water film formation requirements is inaccurate.

[0015] Furthermore, the process of obtaining the temperature rise rate of the water-cooled wall tube to determine whether the water film thickness is qualified includes, Several monitoring points are set up outside the water-cooled wall tubes, and the initial and final temperatures of each monitoring point are collected at a preset time to calculate the temperature difference. The ratio of the temperature difference to the preset time is the temperature rise rate. If the temperature rise rate at any monitoring point exceeds the temperature rise rate threshold, the water film thickness is deemed unqualified.

[0016] Compared with existing technologies, the advantages of this invention are as follows: By dividing the cross-section of the water-cooled wall tube into several welding areas and acquiring corresponding detection images, the wall tube thickness and bevel angle of each area are calculated, thereby generating wall tube characterization parameters. This achieves refined detection and quantitative analysis of the welding areas of the water-cooled wall tube. Partial detection can accurately capture dimensional deviations in different areas. For wall tubes with low welding risk, the deviations from standard wall tube parameters are small, and the deviations in wall thickness and bevel angle only have a slight impact on welding quality, which can be met by conventional welding processes. For wall tubes with high welding risk, the deviations from standard wall tube parameters are too large, and the wall thickness and bevel angle deviate significantly. The standard range can easily lead to defects such as incomplete welding and weld beads during the welding process, which cannot guarantee the stable formation of the water film and the safe operation of the pipe wall. It is necessary to cut the pipe section. Based on the comparison of the wall pipe characterization parameters and standard parameters, the cutting length of the water-cooled wall pipe with high welding risk is determined when pre-welding a single welding flow section. The supplementary length of the water-cooled wall pipe with weak welding risk is determined according to the cutting length. The water-cooled wall pipe with weak welding risk and the water-cooled wall pipe with high welding risk are mixed for welding to improve the welding accuracy and use efficiency of the water-cooled wall pipe. The pretreatment and welding process are precisely matched, thereby further improving the accuracy of the high-precision welding process of water-cooled wall pipe based on real-time temperature control monitoring.

[0017] Furthermore, this invention acquires the wall tube temperature and calculates water film characteristic parameters by collecting infrared images of the weld seam. The quality of water film formation directly affects the heat absorption efficiency and the ability to prevent high-temperature corrosion of the water-cooled wall tube during actual boiler operation. When it is determined that the water-cooled wall tube does not meet the water film formation requirements, the water film deviation parameter is calculated by comparing the water film characteristic parameters with the water film characteristic threshold to analyze the specific reasons. If the water film deviation parameter is slightly greater than the water film deviation threshold, it indicates that there is weld bead at the weld seam of the water-cooled wall tube. Therefore, the local temperature at the weld bead will be significantly higher than that of other parts, resulting in a slightly higher overall water film deviation parameter. If the water film deviation parameter is significantly greater than the water film deviation threshold, it indicates that the weld seam of the water-cooled wall tube is not fully welded, resulting in excessive circumferential temperature fluctuations in the weld seam. If the water film characteristic parameter is less than the water film characteristic threshold, it indicates that the water-cooled wall tube meets the water film formation requirements. This means that the tube wall can be effectively cooled and protected during boiler operation, reducing the risk of tube wall overheating, accelerated scaling, or even tube rupture due to local water film damage. This further improves the accuracy of the high-precision welding process of water-cooled wall tubes based on real-time temperature control monitoring.

[0018] Furthermore, this invention generates staining characterization parameters by introducing a fluorescent tracer into the pipe and acquiring images to obtain staining brightness and length data. The fluorescent tracer can clearly show the flow path and coverage uniformity of the water film on the inner wall of the pipe, and can physically confirm the reasons for the water film formation failure. The dual verification mechanism effectively avoids misjudgment caused by inference based solely on infrared images. If weld beads exist in the weld, the staining brightness or staining length of the stained area will be less than the reference value. If the weld is not completely welded, there will be fluorescent agent residue, and the staining brightness or staining length of the stained area will be greater than the reference value. The characterization threshold is set as the median value of the dyeing characterization parameters calculated for the two reasons for unqualified water film formation. The accuracy of the reason for unqualified water film formation can be verified by comparing the dyeing characterization parameters with the dyeing characterization threshold. When the reason for unqualified water film formation is the presence of weld beads at the weld, the cutting length is adjusted according to the water film deviation parameter. When the reason for unqualified water film formation is incomplete welding at the weld, the pretreatment parameters are adjusted according to the water film deviation parameter. This improves the robustness of the welding process and further improves the accuracy of the high-precision welding process for water-cooled wall tubes based on real-time temperature control monitoring.

[0019] Furthermore, this invention determines the water film thickness compliance by acquiring the temperature rise rate of the water-cooled wall tube, providing a more accurate basis for water film quality control. The water film thickness directly determines the heat dissipation effect and corrosion resistance of the water-cooled wall tube. The temperature rise rate is negatively correlated with the water film thickness; the thinner the water film, the faster the temperature rise rate, indicating that the water film thickness is unqualified, while the thicker the water film, the slower the temperature rise rate, indicating that the water film thickness is qualified. By collecting the temperature rise rate in real time and comparing it with a preset threshold, it is possible to intuitively determine whether the water film thickness meets the standard. In response to unqualified water film thickness, the temperature rise deviation parameter is calculated based on the temperature rise rate and the temperature rise rate threshold, and the water film characteristic threshold is adjusted in a targeted manner, realizing the dynamic optimization of the water film characteristic threshold, thereby further improving the accuracy of the high-precision welding process of water-cooled wall tubes based on real-time temperature control monitoring. Attached Figure Description

[0020] Figure 1 This is a flowchart illustrating the steps of a high-precision welding process for water-cooled wall tubes based on real-time temperature control monitoring, as described in an embodiment of the present invention. Figure 2 A logic diagram for determining the risk trend of water-cooled wall tubes in an embodiment of the present invention; Figure 3 This is a logic diagram for determining whether a water-cooled wall tube meets the requirements for water film formation in an embodiment of the present invention. Figure 4 This is a logic diagram for determining whether the water film thickness is qualified according to an embodiment of the present invention. Detailed Implementation

[0021] To make the objectives and advantages of the present invention clearer, the present invention will be further described below with reference to embodiments; it should be understood that the specific embodiments described herein are merely for explaining the present invention and are not intended to limit the present invention.

[0022] Preferred embodiments of the present invention will now be described with reference to the accompanying drawings. Those skilled in the art should understand that these embodiments are merely illustrative of the technical principles of the present invention and are not intended to limit the scope of protection of the present invention.

[0023] It should be noted that, in the description of this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0024] Please see Figure 1 The diagram shows a flowchart of the high-precision welding process for water-cooled wall tubes based on real-time temperature control monitoring, as described in this embodiment of the invention. The high-precision welding process for water-cooled wall tubes based on real-time temperature control monitoring includes: Step S1: Divide the cross-section of the water-cooled wall tube into several welding areas and acquire corresponding detection images. Calculate the wall tube thickness and wall tube bevel angle for each welding area. Calculate the wall tube characterization parameters based on the wall tube thickness and wall tube bevel angle. Step S2: Based on the comparison results between the wall tube characterization parameters and the wall tube standard parameters, determine the risk trend and pretreatment parameters of the water-cooled wall tube, as well as the cutting length for pre-welding water-cooled wall tubes with strong welding risks. Step S3: Heat the pre-welded water-cooled wall tube and acquire infrared images of the weld. Obtain the wall tube temperature based on the infrared images of the weld. Calculate the water film characteristic parameters of a single welded flow section based on the wall tube temperature and determine whether the water-cooled wall tube meets the water film formation requirements. If the water-cooled wall tube does not meet the water film formation requirements, determine the reason why the water-cooled wall tube does not meet the water film formation requirements based on the water film deviation parameters. Step S4: Fluorescent tracer is introduced into the water-cooled wall tube and a staining image of the inside of the water-cooled wall tube is acquired. Based on the staining brightness and staining length obtained from the staining image, staining characterization parameters are generated, and the accuracy of the reason why the water-cooled wall tube does not meet the requirements for water film formation is determined based on the staining characterization parameters. Step S5: If the reason why the water-cooled wall tube does not meet the water film formation requirements is accurate, adjust the pretreatment parameters or adjust the cutting length based on the water film deviation parameters; if the reason why the water-cooled wall tube does not meet the water film formation requirements is inaccurate, adjust the water film deviation threshold based on the staining deviation parameters. Step S6: In response to the water-cooled wall tube meeting the water film formation requirements, the water-cooled wall tube is welded, and the temperature rise rate of the water-cooled wall tube is obtained to determine whether the water film thickness is qualified. In response to the water film thickness being unqualified, the temperature rise deviation parameter is calculated based on the temperature rise rate and the temperature rise rate threshold to adjust the water film characteristic threshold.

[0025] It is understandable that during boiler operation, the working fluid water inside the water-cooled wall tubes absorbs radiant heat from the furnace. The thin water film adhering closely to the tube wall preferentially boils and vaporizes. Under ideal conditions, the bubbles generated by vaporization can be carried away from the tube wall by the high-speed water flow inside the tube, allowing a continuous and stable liquid water film to always adhere to the inner wall of the tube and flow. This high-speed flowing liquid water film adhering closely to the tube wall can effectively block the high-temperature tube wall from the steam inside the tube, preventing the tube wall from being directly exposed to the high-temperature environment. When there are welding defects on the inner wall of the water-cooled wall tube, this liquid water film is easily replaced by a steam film with extremely poor thermal conductivity, causing the tube wall temperature to rise sharply, which in turn leads to the risk of tube rupture. Therefore, the water film mentioned in this invention specifically refers to a liquid water film that adheres closely to the tube wall and maintains continuous high-speed flow. The core purpose of this invention is to guide and improve welding accuracy by real-time detection and determination of the stable formation conditions of the water film on the inner wall of the water-cooled wall tube.

[0026] Specifically, the process of dividing the cross-section of the water-cooled wall tube into several welding areas and acquiring corresponding inspection images, and then calculating the wall tube thickness and bevel angle for each welding area, includes the following steps: The cross-section of the water-cooled wall tube is divided into several welding areas and detection images corresponding to each welding area are acquired. Each welding area includes at least one continuous welding section. Collect data on the wall thickness and bevel angle of several pipe sections in each welding area; The mean thickness of each tube wall is calculated as the thickness factor corresponding to each welding area. The mean angle of each pipe bevel is calculated as the angle factor corresponding to each welding area.

[0027] Understandably, the welding area includes a continuous welding section to ensure that the wall of the water-cooled wall tube is included in the detection images corresponding to each welding area, thus avoiding the waste of resources from invalid acquisition of multiple areas.

[0028] Please see Figure 2 As shown, this is a logic diagram for determining the risk trend of water-cooled wall tubes according to an embodiment of the present invention. The risk trend of the water-cooled wall tubes is determined based on the comparison results between the wall tube characterization parameters and the wall tube standard parameters. The weighted sum of the thickness factor and the angle factor is determined to be the wall tube characterization parameter; The wall tube deviation parameter is the absolute value of the difference between the wall tube characterization parameter and the wall tube standard parameter; If the wall tube deviation parameter is greater than or equal to the first wall tube deviation threshold and less than or equal to the second wall tube deviation threshold, then the risk trend of the water-cooled wall tube is determined to be weak welding risk. If the wall tube deviation parameter is less than the first wall tube deviation threshold or greater than the second wall tube deviation threshold, the risk trend of the water-cooled wall tube is determined to be strong welding risk.

[0029] Specifically, the wall tube characterization parameter = a × thickness factor + b × angle factor / 10, where the thickness factor is in mm, and a and b are weighting coefficients, a + b = 1. Since the probability of wall thickness deviation and angle deviation occurring in the actual processing of water-cooled wall tubes is the same and their impact on welding quality is consistent, a is generally taken as 0.5 and b as 0.5. The above formula only takes the numerical values ​​in the calculation.

[0030] In one specific embodiment, the standard pretreatment parameters for a water-cooled wall tube with a wall thickness of 6mm and a bevel angle of 62° are a welding current of 120A and a welding speed of 70mm / min, and its standard wall tube parameters are 6.1.

[0031] Specifically, the purpose of setting the wall tube deviation threshold is to characterize the degree of welding risk deviation in water-cooled wall tube welding. The first wall tube deviation threshold can be in the range of [0.5, 1.5], and the second wall tube deviation threshold can be in the range of [2.0, 3.0].

[0032] Specifically, the process of determining pretreatment parameters and the cut length for pre-welding of water-cooled wall tubes with high welding risk based on the comparison results between the wall tube characterization parameters and the wall tube standard parameters includes: The preprocessing parameter is determined to be the product of the first ratio and the standard preprocessing parameter; The cut length is determined to be the product of the total length of the water-cooled wall tube with high welding risk and the second ratio. The first ratio is the ratio of the wall tube characterization parameter to the wall tube standard parameter, the second ratio is the sum of the ratio of the wall tube standard parameter and the wall tube characterization parameter, and the pretreatment parameters include welding current and welding speed.

[0033] In a specific embodiment, the standard parameters of the wall tube are set to 6.1. The wall tube characterization parameters for a water-cooled wall tube with a length of 9m, a wall thickness of 8mm, and a bevel angle of 68° are calculated to be 7.4. The first ratio of the wall tube characterization parameters to the standard parameters is 7.4 / 6.1. Therefore, the pretreatment parameters for the water-cooled wall tube are a welding current of 145.6A and a welding speed of 84.9mm / min. The first wall tube deviation threshold is set to 1.5, the second wall tube deviation threshold is set to 2.0, and the calculated wall tube deviation parameter is 1.3. The risk trend of the water-cooled wall tube is determined to be strong welding risk. The ratio of the wall tube characterization parameters to the standard parameters is 6.1 / 7.4. Therefore, the second ratio is 1-(6.1 / 7.4)=0.176. The cut length is 9x0.176=1.58m, and the corresponding supplementary length for the water-cooled wall tube with weak welding risk is 1.58m.

[0034] Specifically, water-cooled wall tubes with high welding risk are cut according to the cutting length. The treatment is carried out on the premise that the length of the water-cooled wall tube after cutting still meets the actual use requirements. If the length of the water-cooled wall tube after cutting cannot meet the actual application needs, the entire water-cooled wall tube is replaced.

[0035] Specifically, this invention divides the cross-section of the water-cooled wall tube into several welding areas and acquires corresponding detection images. It then calculates the wall tube thickness and bevel angle for each area, generating wall tube characterization parameters. This achieves refined detection and quantitative analysis of the welding areas of the water-cooled wall tube. Zoned detection can accurately capture dimensional deviations in different areas. For wall tubes with low welding risk, the characterization parameters deviate slightly from the standard parameters, with deviations in wall thickness and bevel angle having only a minor impact on welding quality. Conventional welding processes can meet the usage requirements. However, for wall tubes with high welding risk, the characterization parameters deviate significantly from the standard parameters, with wall thickness and bevel angle severely deviating from the standard range, potentially leading to… Defects such as incomplete welding and weld beads during the welding process cannot guarantee the stable formation of the water film and the safe operation of the pipe wall. It is necessary to cut the pipe section. Based on the comparison of the wall pipe characterization parameters and standard parameters, the cutting length of the water-cooled wall pipe with high welding risk is determined when pre-welding a single welding flow section. The supplementary length of the water-cooled wall pipe with weak welding risk is determined according to the cutting length. The water-cooled wall pipes with weak welding risk and water-cooled wall pipes with high welding risk are mixed for welding to improve the welding accuracy and use efficiency of the water-cooled wall pipe. The pretreatment and welding process are precisely matched, thereby further improving the accuracy of the high-precision welding process of water-cooled wall pipe based on real-time temperature control monitoring.

[0036] Specifically, the process of calculating the water film characteristic parameters of a single welded flow section based on the wall pipe temperature obtained from the weld infrared image includes: The difference between the minimum and maximum circumferential wall tube temperatures of the same weld seam is calculated as the wall temperature difference. The standard deviation of the wall temperature difference of several welds is calculated as a characteristic parameter of the water film.

[0037] Specifically, the present invention acquires infrared images of the weld seam of the water-cooled wall tube under heating conditions using an infrared thermal imager, and converts the infrared radiation intensity corresponding to each pixel in the weld seam infrared image into temperature values ​​to obtain the minimum and maximum wall tube temperatures.

[0038] Specifically, the detection length of a single welding process section is set to 20m so that after adding fluorescent tracers, the push-rod type long-distance endoscopic detection device can effectively acquire stained images.

[0039] Specifically, when calculating the standard deviation of the wall temperature difference, it is necessary to first normalize the wall temperature difference to convert it to a uniform range, for example, to the interval [0, 1], to eliminate the influence of numerical differences. This will not be elaborated further here.

[0040] Please see Figure 3 As shown, this is a logic diagram for determining whether a water-cooled wall tube meets the requirements for water film formation according to an embodiment of the present invention. The determination is based on water film characteristic parameters. If the water film characteristic parameters are greater than the water film characteristic threshold, the water-cooled wall tube is determined to not meet the requirements for water film formation. If the water film characteristic parameters are less than or equal to the water film characteristic threshold, then the water-cooled wall tube is determined to meet the requirements for water film formation.

[0041] Specifically, the purpose of setting the water film characteristic threshold is to characterize the fluctuation of the wall temperature difference of the water-cooled wall tube under heating state and the consistency of the wall temperature difference of the water-cooled wall tube of the same specification under the same working conditions. The water film characteristic threshold is selected in the range [0.2, 0.4], preferably 0.3.

[0042] Specifically, the process of determining why water-cooled wall tubes do not meet water film formation requirements based on water film deviation parameters includes: The absolute value of the difference between the water film characteristic parameters and the water film characteristic threshold is determined as the water film deviation parameter; If the water film deviation parameter is less than or equal to the water film deviation threshold, the reason why the water-cooled wall tube does not meet the water film formation requirements is that there is weld bead at the weld. If the water film deviation parameter is greater than the water film deviation threshold, the reason why the water-cooled wall tube does not meet the water film formation requirements is that the weld is not fully welded.

[0043] Specifically, the purpose of setting the water film deviation threshold is to characterize the consistency of the test results of the water-cooled wall tube. The water film deviation threshold can be in the range of [0.1, 0.3], preferably 0.2.

[0044] Specifically, this invention acquires the wall tube temperature and calculates water film characteristic parameters by collecting infrared images of the weld seam. The quality of water film formation directly affects the heat absorption efficiency and high-temperature corrosion prevention ability of the water-cooled wall tube during actual boiler operation. When it is determined that the water-cooled wall tube does not meet the water film formation requirements, the water film deviation parameter is calculated by comparing the water film characteristic parameters with the water film characteristic threshold to analyze the specific reasons. If the water film deviation parameter is slightly greater than the water film deviation threshold, it indicates that there is weld bead at the weld seam of the water-cooled wall tube. Therefore, the local temperature at the weld bead will be significantly higher than that of other parts, resulting in a slightly higher overall water film deviation parameter. If the water film deviation parameter is significantly greater than the water film deviation threshold, it indicates that the weld seam of the water-cooled wall tube is not fully welded, resulting in excessive circumferential temperature fluctuations in the weld seam. If the water film characteristic parameter is less than the water film characteristic threshold, it indicates that the water-cooled wall tube meets the water film formation requirements. This means that the tube wall can be effectively cooled and protected during boiler operation, reducing the risk of tube wall overheating, accelerated scaling, or even tube rupture due to local water film damage. This further improves the accuracy of the high-precision welding process of water-cooled wall tubes based on real-time temperature control monitoring.

[0045] Specifically, the process of generating staining characterization parameters by obtaining staining brightness and staining length from the staining image includes, Acquire dyeing images of the weld seam and obtain the dyeing brightness and dyeing length of each dyeing image; The ratio of the mean of several staining brightness values ​​to the reference staining brightness value is determined as the brightness factor; The length factor is determined by the ratio of the mean of several staining lengths to the baseline staining length. The weighted sum of the brightness factor and length factor is determined as the staining characterization parameter.

[0046] Specifically, the present invention can acquire stained images of the inner wall of water-cooled wall tubes using a push-rod type long-distance endoscopic inspection device, perform grayscale processing on the stained images, divide several stained areas at the weld seam, extract the average pixel grayscale value of each stained area as the stained brightness, extract the pixel distance of each stained area along the tube wall axis and combine it with the image calibration coefficient to convert it into the actual physical length, thus obtaining the stained length.

[0047] Specifically, in practice, the baseline dyeing brightness is the average of the dyeing brightness of each dyeing area inside several water-cooled wall tubes of the same specification under the same working conditions, and the baseline dyeing length is the average of the dyeing length of each dyeing area inside several water-cooled wall tubes of the same specification under the same working conditions.

[0048] Specifically, the sum of the weighting coefficients of the brightness factor and the length factor is 1. Since the dyeing brightness is more sensitive and distinguishable for identifying weld defect types, while the dyeing length reflects the defect range, the weighting coefficient of the brightness factor is generally taken as 0.6 and the weighting coefficient of the length factor is 0.4.

[0049] Specifically, the accuracy of determining the reasons why water-cooled wall tubes fail to meet water film formation requirements based on staining characterization parameters is as follows: If the reason why the water-cooled wall tube does not meet the water film formation requirements is that there is weld bead at the weld, if the staining characterization parameter is greater than the staining characterization threshold, the reason for the water-cooled wall tube not meeting the water film formation requirements is inaccurate. If the staining characterization parameter is less than or equal to the staining characterization threshold, the reason for the water-cooled wall tube not meeting the water film formation requirements is accurate. If the reason why the water-cooled wall tube does not meet the water film formation requirements is that the weld is not fully welded, then if the staining characterization parameter is less than the staining characterization threshold, the reason for the water-cooled wall tube not meeting the water film formation requirements is inaccurate. If the staining characterization parameter is greater than or equal to the staining characterization threshold, then the reason for the water-cooled wall tube not meeting the water film formation requirements is accurate.

[0050] Specifically, the staining characterization threshold is determined through calibration tests. Standard water-cooled wall tube samples with known reasons for not meeting the water film formation requirements are selected, namely qualified calibration samples with weld beads at the weld and qualified calibration samples with incomplete welding at the weld. Fluorescent tracers are introduced and images of the inner wall are collected. The corresponding staining characterization parameters are calculated by weighting according to the brightness factor of 0.6 and the length factor of 0.4. The median value of the staining characterization parameters of the two types of samples is used as the staining characterization threshold, so that the threshold can effectively distinguish the staining characterization parameter range corresponding to weld beads and incomplete welding. The staining characterization threshold is selected within the range [0.9, 1.1], preferably 1.0.

[0051] Specifically, in response to the accurate cause that the water-cooled wall tube does not meet the requirements for water film formation, the process of adjusting pretreatment parameters or adjusting the cutting length based on the water film deviation parameters includes: If the reason why the water-cooled wall tube does not meet the water film formation requirements is that there is weld bead at the weld, then the cut length is adjusted based on the water film deviation parameter. If the reason why the water-cooled wall tube does not meet the requirements for water film formation is that the weld is not fully welded, then the pretreatment parameters should be adjusted based on the water film deviation parameters.

[0052] In one specific embodiment, if the reason why the water-cooled wall tube does not meet the water film formation requirements is that there is weld bead at the weld, if the water film deviation parameter is less than or equal to 0.3, the cutting length will be increased by 5%; if the water film deviation parameter is greater than 0.3, the cutting length will be increased by 10%.

[0053] In one specific embodiment, if the reason why the water-cooled wall tube does not meet the water film formation requirements is that the weld is not fully welded, if the water film deviation parameter is less than or equal to 0.3, the pretreatment parameter will be reduced by 5%; if the water film deviation parameter is greater than 0.3, the pretreatment parameter will be reduced by 10%.

[0054] Specifically, in response to the inaccuracy of the reason why the water-cooled wall tubes do not meet the requirements for water film formation, the process of adjusting the water film deviation threshold based on the staining deviation parameter includes: The ratio of the absolute value of the difference between the staining characterization parameter and the staining characterization threshold to the staining characterization threshold is the staining deviation parameter.

[0055] In one specific embodiment, if the staining deviation parameter is less than 0.4, the staining characterization threshold is increased by 10%; if the staining deviation parameter is in the range of [0.4, 0.7], the staining characterization threshold is increased by 15%; and if the staining deviation parameter is greater than 0.7, the staining characterization threshold is increased by 20%.

[0056] Specifically, this invention generates staining characterization parameters by introducing a fluorescent tracer into the pipe and acquiring images to obtain staining brightness and length data. The fluorescent tracer can clearly show the flow path and coverage uniformity of the water film on the inner wall of the pipe, and can physically confirm the reasons for the water film formation failure. The dual verification mechanism effectively avoids misjudgments caused by inference based solely on infrared images. If weld beads exist in the weld, the staining brightness or staining length of the stained area will be less than the reference value. If the weld is not completely welded, there will be fluorescent agent residue, and the staining brightness or staining length of the stained area will be greater than the reference value. The characterization threshold is set as the median value of the dyeing characterization parameters calculated for the two reasons for unqualified water film formation. The accuracy of the reason for unqualified water film formation can be verified by comparing the dyeing characterization parameters with the dyeing characterization threshold. When the reason for unqualified water film formation is the presence of weld beads at the weld, the cutting length is adjusted according to the water film deviation parameter. When the reason for unqualified water film formation is incomplete welding at the weld, the pretreatment parameters are adjusted according to the water film deviation parameter. This improves the robustness of the welding process and further improves the accuracy of the high-precision welding process for water-cooled wall tubes based on real-time temperature control monitoring.

[0057] Please see Figure 4 The diagram shown is a logic diagram for determining whether the water film thickness is qualified according to an embodiment of the present invention. The process of obtaining the temperature rise rate of the water-cooled wall tube to determine whether the water film thickness is qualified includes: Several monitoring points are set up outside the water-cooled wall tubes, and the initial and final temperatures of each monitoring point are collected at a preset time to calculate the temperature difference. The ratio of the temperature difference to the preset time is the temperature rise rate. If the temperature rise rate at any monitoring point is greater than the temperature rise rate threshold, the water film thickness is deemed unqualified. If the temperature rise rate at all monitoring points is less than the temperature rise rate threshold, the water film thickness is deemed acceptable.

[0058] Specifically, the preset time is 1 hour, and the temperature value is collected at each detection point every 10 minutes. The initial temperature is the first temperature value, and the final temperature is the last temperature value.

[0059] Specifically, the purpose of setting the temperature rise rate threshold is to characterize the consistency of water film thickness in different parts of the water-cooled wall tube in actual application. The temperature rise rate threshold can be in the range of [10℃ / min, 20℃ / min], preferably 15℃ / min.

[0060] Specifically, in response to a non-compliant water film thickness, the process of calculating a temperature rise deviation parameter based on the temperature rise rate and a temperature rise rate threshold to adjust the water film characteristic threshold includes the following steps: Determine all temperature rise rates greater than the temperature rise rate threshold as the temperature rise factor; The mean of the differences between each temperature rise factor and the temperature rise rate threshold is determined as the temperature rise deviation parameter.

[0061] In one specific embodiment, if the temperature rise deviation parameter is less than or equal to 10°C / min, it is determined that the water film characteristic threshold will be increased by 10%; if the temperature rise deviation parameter is greater than 10°C / min, it is determined that the water film characteristic threshold will be increased by 20%.

[0062] Specifically, this invention determines the water film thickness compliance by acquiring the temperature rise rate of the water-cooled wall tube, providing a more accurate basis for water film quality control. The water film thickness directly determines the heat dissipation effect and corrosion resistance of the water-cooled wall tube. The temperature rise rate is negatively correlated with the water film thickness; the thinner the water film, the faster the temperature rise rate, indicating that the water film thickness is unqualified, while the thicker the water film, the slower the temperature rise rate, indicating that the water film thickness is qualified. By collecting the temperature rise rate in real time and comparing it with a preset threshold, it is possible to intuitively determine whether the water film thickness meets the standard. In response to unqualified water film thickness, the temperature rise deviation parameter is calculated based on the temperature rise rate and the temperature rise rate threshold, and the water film characteristic threshold is adjusted in a targeted manner, realizing the dynamic optimization of the water film characteristic threshold, thereby further improving the accuracy of the high-precision welding process of water-cooled wall tubes based on real-time temperature control monitoring.

[0063] The technical solution of the present invention has been described above with reference to the preferred embodiments shown in the accompanying drawings. However, it will be readily understood by those skilled in the art that the scope of protection of the present invention is obviously not limited to these specific embodiments. Without departing from the principles of the present invention, those skilled in the art can make equivalent changes or substitutions to the relevant technical features, and the technical solutions after these changes or substitutions will all fall within the scope of protection of the present invention.

Claims

1. A high-precision welding process for water-cooled wall tubes based on real-time temperature control monitoring, characterized in that, include: The cross-section of the water-cooled wall tube is divided into several welding areas and corresponding detection images are acquired. The wall tube thickness and wall tube bevel angle of each welding area are calculated respectively. Based on the wall tube thickness and the wall tube bevel angle, the wall tube characterization parameters are calculated. Based on the comparison results between the wall tube characterization parameters and the wall tube standard parameters, the risk trend and pretreatment parameters of the water-cooled wall tube, as well as the cutting length for pre-welding of water-cooled wall tubes with strong welding risks, are determined. The pre-welded water-cooled wall tube is heated and the weld infrared image is acquired. The wall tube temperature is obtained based on the weld infrared image. The water film characteristic parameters of a single welded flow section are calculated based on the wall tube temperature, and it is determined whether the water-cooled wall tube meets the water film formation requirements. In response to the water-cooled wall tube not meeting the water film formation requirements, the reason why the water-cooled wall tube does not meet the water film formation requirements is determined based on the water film deviation parameters. Fluorescent tracers are introduced into the water-cooled wall tube and staining images of the inside of the water-cooled wall tube are collected. Staining characterization parameters are generated based on the staining brightness and staining length obtained from the staining images. Based on the staining characterization parameters, it is determined whether the reason why the water-cooled wall tube does not meet the requirements for water film formation is accurate. If the reason why the water-cooled wall tube does not meet the water film formation requirements is accurate, adjust the pretreatment parameters or the cutting length based on the water film deviation parameters. If the reason why the water-cooled wall tube does not meet the water film formation requirements is inaccurate, adjust the water film deviation threshold based on the staining deviation parameters. In response to the water-cooled wall tube meeting the water film formation requirements, the water-cooled wall tube is welded, and the temperature rise rate of the water-cooled wall tube is obtained to determine whether the water film thickness is qualified. In response to the water film thickness being unqualified, the temperature rise deviation parameter is calculated based on the temperature rise rate and the temperature rise rate threshold to adjust the water film characteristic threshold.

2. The high-precision welding process for water-cooled wall tubes based on real-time temperature control monitoring according to claim 1, characterized in that, The process of dividing the cross-section of the water-cooled wall tube into several welding areas and acquiring corresponding detection images, and calculating the wall tube thickness and wall tube bevel angle for each welding area, includes: The cross-section of the water-cooled wall tube is divided into several welding areas and detection images corresponding to each welding area are acquired. Each welding area includes at least one continuous welding section. Collect several wall thicknesses and wall bevel angles in each of the aforementioned welding areas; The mean thickness of each of the wall tubes is calculated as the thickness factor corresponding to each of the welding areas; The mean value of the bevel angle of each of the aforementioned pipe walls is calculated as the angle factor corresponding to each of the aforementioned welding areas.

3. The high-precision welding process for water-cooled wall tubes based on real-time temperature control monitoring according to claim 2, characterized in that, The risk trend of the water-cooled wall tube is determined based on the comparison results between the wall tube characterization parameters and the wall tube standard parameters, wherein, The weighted sum of the thickness factor and the angle factor is determined to be a wall tube characterization parameter; The wall tube deviation parameter is the absolute value of the difference between the wall tube characterization parameter and the wall tube standard parameter; If the wall tube deviation parameter is greater than or equal to the first wall tube deviation threshold and less than or equal to the second wall tube deviation threshold, then the risk trend of the water-cooled wall tube is determined to be weak welding risk. If the wall tube deviation parameter is less than the first wall tube deviation threshold or greater than the second wall tube deviation threshold, the risk trend of the water-cooled wall tube is determined to be strong welding risk.

4. The high-precision welding process for water-cooled wall tubes based on real-time temperature control monitoring according to claim 3, characterized in that, The process of determining the pretreatment parameters and the cut length for pre-welding of water-cooled wall tubes with high welding risk based on the comparison results between the wall tube characterization parameters and the wall tube standard parameters includes: The preprocessing parameter is determined to be the product of the first ratio and the standard preprocessing parameter; The cut length is determined to be the product of the total length of the water-cooled wall tube with high welding risk and the second ratio. Wherein, the first ratio is the ratio of the wall tube characterization parameter to the wall tube standard parameter, the second ratio is the sum of the ratio of the wall tube standard parameter and the ratio of the wall tube characterization parameter, and the pretreatment parameters include welding current and welding speed.

5. The high-precision welding process for water-cooled wall tubes based on real-time temperature control monitoring according to claim 4, characterized in that, The process of calculating the water film characteristic parameters of a single welded flow section based on the wall pipe temperature obtained from the infrared image of the weld seam includes the following steps: The difference between the minimum and maximum circumferential wall tube temperatures of the same weld seam is calculated as the wall temperature difference. The standard deviation of the wall temperature difference of several welds is calculated as a characteristic parameter of the water film.

6. The high-precision welding process for water-cooled wall tubes based on real-time temperature control monitoring according to claim 5, characterized in that, Determining whether water-cooled wall tubes meet the requirements for water film formation based on water film characteristic parameters, among which, If the water film characteristic parameters are greater than the water film characteristic threshold, the water-cooled wall tube is determined to not meet the requirements for water film formation. If the water film characteristic parameters are less than or equal to the water film characteristic threshold, then the water-cooled wall tube is determined to meet the water film formation requirements.

7. The high-precision welding process for water-cooled wall tubes based on real-time temperature control monitoring according to claim 6, characterized in that, The process of determining the reasons why the water-cooled wall tube does not meet the water film formation requirements based on the water film deviation parameter includes: The absolute value of the difference between the water film characteristic parameters and the water film characteristic threshold is determined as the water film deviation parameter; If the water film deviation parameter is less than or equal to the water film deviation threshold, the reason why the water-cooled wall tube does not meet the water film formation requirements is that there is weld bead at the weld. If the water film deviation parameter is greater than the water film deviation threshold, the reason why the water-cooled wall tube does not meet the water film formation requirements is that the weld is not fully welded.

8. The high-precision welding process for water-cooled wall tubes based on real-time temperature control monitoring according to claim 7, characterized in that, The process of obtaining staining brightness and staining length from the staining image to generate staining characterization parameters includes, Acquire dyeing images of the weld seam and obtain the dyeing brightness and dyeing length of each dyeing image; The ratio of the mean of several staining brightness values ​​to the reference staining brightness value is determined as the brightness factor; The length factor is determined by the ratio of the mean of several staining lengths to the baseline staining length. The weighted sum of the brightness factor and the length factor is determined to be the staining characterization parameter.

9. The high-precision welding process for water-cooled wall tubes based on real-time temperature control monitoring according to claim 8, characterized in that, Whether the method of determining the reasons why water-cooled wall tubes do not meet the requirements for water film formation based on staining characterization parameters is accurate is important. If the reason why the water-cooled wall tube does not meet the water film formation requirements is that there is weld bead at the weld, and the staining characterization parameter is greater than the staining characterization threshold, then the reason for the water-cooled wall tube not meeting the water film formation requirements is inaccurate. If the reason why the water-cooled wall tube does not meet the water film formation requirements is that the weld is not fully welded, and the staining characterization parameter is less than the staining characterization threshold, then the reason for the water-cooled wall tube not meeting the water film formation requirements is inaccurate.

10. The high-precision welding process for water-cooled wall tubes based on real-time temperature control monitoring according to claim 9, characterized in that, The process of obtaining the temperature rise rate of the water-cooled wall tube to determine whether the water film thickness is qualified includes, Several monitoring points are set up outside the water-cooled wall tubes, and the initial and final temperatures of each monitoring point are collected at a preset time to calculate the temperature difference. The ratio of the temperature difference to the preset time is the temperature rise rate. If the temperature rise rate at any monitoring point exceeds the temperature rise rate threshold, the water film thickness is deemed unqualified.

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