A boiler high-temperature heating surface temperature indicating coating and over-temperature early warning system

Abstract

The invention discloses a temperature-indicating coating for high-temperature heating surfaces of boilers and an overtemperature warning system. The coating comprises the following components by mass percentage: 5%-8% of a thermosensitive pigment A that changes color at temperatures below 300°C, 5%-8% of a thermosensitive pigment B that changes color at 300-400°C, 5%-8% of a thermosensitive pigment C that changes color at 400-500°C, 5%-8% of a thermosensitive pigment D that changes color at 500-600°C, 5%-8% of a thermosensitive pigment E that changes color at 600-700°C, 5%-8% of a thermosensitive pigment F that changes color at 700-800°C, 5%-8% of a thermosensitive pigment G that changes color at 800-1000°C, 20% of a ceramic matrix, 5% of a corrosion inhibitor, 5% of a wear-resistant filler, 10%-15% of a binder, 5% of a stabilizer, and the remainder of solvent. The system includes a functional coating and a color-temperature recognition system. The coating can be applied to the high-temperature heating surface of the boiler and can undergo irreversible color changes or physical property changes when the temperature reaches a preset threshold, thereby providing an over-temperature warning and having the functions of preventing high-temperature corrosion and wear.

Description

Technical Field

[0001] The present invention relates to the technical field of boiler safety monitoring, and in particular to a temperature indicating coating for a high-temperature heating surface of a boiler and an over-temperature early warning system. Background Art

[0002] Boilers are critical equipment in industries such as power, petroleum, chemical, and metallurgy. The operating status of their high-temperature heating surfaces (such as superheaters and reheaters) is directly related to the safety and efficiency of the entire system. These high-temperature heating surfaces are subjected to high temperatures and high pressures for extended periods of time. Controlling their temperature distribution and tube wall temperature is crucial to preventing accidents such as overheating and tube bursts.

[0003] Overheating of a boiler's high-temperature heating surfaces can lead to a variety of serious problems. Overheating can weaken the tube wall material, causing tube bursts and directly impacting safe boiler operation. Long-term overheating can accelerate the deterioration of piping materials and shorten equipment life. In severe cases, overheating often results in boiler shutdown for maintenance, severely impacting production schedules and economic benefits.

[0004] Uneven temperature distribution on a boiler's high-temperature heating surfaces can lead to a series of significant disadvantages. First, it can lead to the generation and increase of thermal stress. Thermal stress is the internal stress caused by inconsistent thermal expansion and contraction of materials during temperature changes. Heating surfaces subjected to long-term high thermal stress are prone to fatigue damage and even serious accidents such as tube bursts. Second, uneven temperature distribution can lead to ash and slagging accumulation on the heating surfaces. This accumulation further exacerbates the uneven temperature distribution on the heating surfaces, creating a vicious cycle. Furthermore, ash and slagging reduce the heat transfer efficiency of the heating surfaces and increase flow resistance on the flue gas side, posing a threat to the safe operation of the boiler. Third, uneven temperature distribution on the heating surfaces exacerbates wear and corrosion on the heating surfaces, reducing their service life. Furthermore, due to reduced heat transfer efficiency and fuel waste, the overall operating efficiency of the boiler is reduced, further shortening its service life.

[0005] At present, the methods for monitoring the wall temperature of high-temperature heating surfaces of boilers mainly include direct measurement, numerical calculation, extrapolation based on steam temperature measurement points outside the furnace, and prediction using nonlinear models such as neural networks. These methods each have their own advantages and disadvantages, but all have certain limitations. Although direct measurement is accurate, the arrangement of measurement points is limited, making it difficult to fully reflect the temperature distribution of the entire heating surface. Numerical calculation relies on complex models and a large amount of computing resources, and the calculation results are greatly affected by the accuracy of the model and boundary conditions. Extrapolation based on steam temperature measurement points outside the furnace: Affected by the complex flow field and temperature field inside the furnace, the extrapolated results may have large errors. Although predictions using nonlinear models such as neural networks can handle complex nonlinear relationships, they require a large amount of training data and high computational costs.

[0006] Irreversible temperature-indicating paint is a special functional coating that uses color changes to indicate surface temperature changes and distribution. It is categorized into single-color irreversible temperature-indicating paints and multi-color irreversible temperature-indicating paints. The former undergoes a single, irreversible color change with temperature, while the latter undergoes multiple, continuous, and irreversible color changes. These coatings offer advantages such as ease of use, low cost, and protection against damage to the structure and operating conditions of the test object. They are widely used in a variety of fields, including aviation, automotive, and industrial piping.

[0007] Existing irreversible temperature-indicating coatings used in power system overheating fault analysis are only suitable for use within a specific, narrow temperature range. This means that if the temperature of the boiler's heating surface exceeds this range, the material may not accurately display or record temperature changes. Furthermore, the internal environment of a boiler is complex, potentially containing pollutants such as dust and smoke. Furthermore, during long-term operation, it encounters extreme temperature and pressure conditions. Existing materials cannot withstand prolonged high temperatures or mechanical stress, leading to premature failure.

[0008] To sum up, how to quickly, accurately and effectively provide temperature warnings for high-temperature heating surfaces on site to guide subsequent operation, maintenance and repair of the equipment is an important problem. Summary of the Invention

[0009] The purpose of the present invention is to provide a temperature-indicating coating for the high-temperature heating surface of a boiler and an over-temperature warning system. The coating can be applied to the high-temperature heating surface of the boiler and can undergo irreversible color changes or physical property changes when the temperature reaches a preset threshold (up to 1000 degrees Celsius), thereby providing an over-temperature warning and having the functions of preventing high-temperature corrosion and wear.

[0010] In one aspect, the present invention provides a temperature-indicating coating for high-temperature heating surfaces of boilers. According to an embodiment of the present invention, the coating comprises the following components in percentage by mass: 5%-8% of a thermal pigment A that changes color at temperatures below 300°C, 5%-8% of a thermal pigment B that changes color at temperatures between 300 and 400°C, 5%-8% of a thermal pigment C that changes color at temperatures between 400 and 500°C, 5%-8% of a thermal pigment D that changes color at temperatures between 500 and 600°C, 5%-8% of a thermal pigment E that changes color at temperatures between 600 and 700°C, 5%-8% of a thermal pigment F that changes color at temperatures between 700 and 800°C, 5%-8% of a thermal pigment G that changes color at temperatures between 800 and 1000°C, 20% of a ceramic matrix, 5% of an anticorrosive agent, 10%-15% of a binder, 5% of a stabilizer, and the remainder being solvent.

[0011] In addition, the temperature indicating paint for the high-temperature heating surface of a boiler according to the above embodiment of the present invention may also have the following additional technical features:

[0012] In some embodiments of the present invention, the thermal pigment A includes zinc oxide or lead white (Pb(OH)2·2PbCO3); the thermal pigment B is cobalt sulfate heptahydrate or bismuth oxide; the thermal pigment C is a mixture of transition metal oxides, specifically cobalt sulfate or chromium oxide; the thermal pigment D is cobalt chloride; the thermal pigment E is cobalt phosphate; the thermal pigment F is chrome yellow (PbCrO4); and the thermal pigment G is copper mercury iodide.

[0013] In some embodiments of the present invention, the ceramic matrix is ​​zirconia.

[0014] In some embodiments of the present invention, the corrosion inhibitor is a silicate or an aluminate.

[0015] In some embodiments of the present invention, the wear-resistant filler is silicon carbide, aluminum oxide or boron nitride.

[0016] In some embodiments of the present invention, the solvent is ethyl acetate or isopropyl alcohol, the binder is sodium silicate, and the stabilizer is aluminum oxide.

[0017] The components of the temperature indicating coating for the high temperature heating surface of the boiler are shown in Table 1:

[0018] Table 1 Composition of temperature indicating coating for high temperature heating surface of boiler

[0019]

[0020]

[0021] In another aspect of the present invention, a method for preparing a temperature-indicating coating for a high-temperature heating surface of a boiler is provided. According to an embodiment of the present invention, the method comprises the following steps:

[0022] (1) First add the solvent to the stirring container, then add the adhesive, stir until the adhesive is completely dissolved in the solvent, then add the stabilizer, anti-corrosion agent, all heat-sensitive pigments, wear-resistant fillers, and leveling agent in sequence, stirring while adding to ensure that all components are evenly dispersed;

[0023] (2) The mixed paint is sent to a sand mill for grinding and dispersion until the paint fineness reaches the required level.

[0024] In another aspect of the present invention, a boiler high-temperature heating surface overtemperature warning system is provided. According to an embodiment of the present invention, the warning system includes:

[0025] Functional coating, applying the boiler high temperature heating surface temperature indicating coating on the boiler high temperature heating surface;

[0026] The color-temperature recognition system includes a comparative colorimetric test block and an image recognition system. The image recognition system is used to collect color changes of the coating on the high-temperature heating surface of the boiler, and perform image fitting and comparison with the comparative colorimetric test block, converting it into a recognizable signal to achieve temperature early warning.

[0027] In another aspect of the present invention, a method for early warning of overtemperature of a high-temperature heating surface of a boiler is provided. According to an embodiment of the present invention, the method comprises the following steps:

[0028] (1) Comparative colorimetric test blocks under multiple temperature ranges: Select an alloy test block with the same material and roughness as the high-temperature heating surface of a boiler, coat it with the boiler high-temperature heating surface temperature indicating paint, and slowly increase the temperature from room temperature to 1000°C to obtain a comparative test block with seven consecutive color change areas;

[0029] (2) Spraying and curing: spraying the boiler high-temperature heating surface temperature indicating paint evenly on the boiler high-temperature heating surface and performing heating and curing treatment;

[0030] (3) After using the image recognition system to collect data on the color information of the over-temperature discoloration part, the image fitting and comparison are performed with the comparison test blocks under multiple temperature ranges to obtain the precise temperature range of the over-temperature part.

[0031] Compared with the prior art, the present invention has the following beneficial effects:

[0032] The irreversible boiler high-temperature heating surface temperature indicating paint can work stably in an environment of up to 1000°C. When the temperature reaches the preset threshold, the color changes, providing an accurate temperature zone. The anti-corrosion agent in the coating can form a dense protective film at high temperatures, effectively isolating oxygen and corrosive gases, and protecting the heating surface from high-temperature corrosion. The added anti-wear agent increases the hardness of the coating, enhances its ability to resist wear, and extends the service life of the boiler heating surface. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 Schematic diagram of the boiler high-temperature heating surface temperature indicating coating in Example 1 of the present invention and the over-temperature warning system in Example 3;

[0034] Figure 2 This is a schematic diagram of the color of the comparative colorimetric test block in Example 4 of the present invention;

[0035] Figure 3 Schematic diagram of the color of the boiler water wall area after coating in Example 4 of the present invention (one overhaul cycle);

[0036] Figure 4 Schematic diagram of the temperature of the boiler water wall area after coating in Example 4 of the present invention (one overhaul cycle);

[0037] Figure 5 Schematic diagram of the temperature of the leaking high-temperature superheater tube panel after coating in Example 5 of the present invention;

[0038] Figure 6 Schematic diagram of the temperature of the leaking high-temperature superheater tube panel after coating after image fitting and comparison in Example 5 of the present invention. DETAILED DESCRIPTION

[0039] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0040] Example 1

[0041] A temperature-indicating coating for high-temperature heating surfaces of boilers comprises the following components by weight: 5% zinc oxide coating, 5% cobalt sulfate heptahydrate, 5% cobalt sulfate, 5% cobalt chloride, 8% cobalt phosphate, 8% chrome yellow (PbCrO4), 8% copper mercury iodide, 20% zirconium oxide (a high-temperature resistant ceramic matrix), 5% cerium oxide, 15% silicon carbide, 3% sodium silicate, and 5% aluminum oxide. The remainder is isopropyl alcohol solvent. The components and their functions are detailed in Table 2.

[0042] Table 2 Composition and function of temperature indicating coating for high temperature heating surface of boiler

[0043]

[0044]

[0045] like Figure 1 As shown, a method for preparing a temperature indicating coating for a high-temperature heating surface of a boiler comprises the following steps:

[0046] (1) Weighing ingredients: Accurately weigh each component according to the above ratio. Pour isopropyl alcohol into the mixing container as the solvent base.

[0047] (2) Mixing and stirring: Add sodium silicate solution to a stirring container, turn on the stirrer, and stir at medium speed (400 rpm) until the binder is completely dissolved in the isopropyl alcohol. Add alumina, cerium oxide, various high-temperature resistant pigments, high-temperature resistant ceramic matrix, and silicon carbide in sequence, stirring while adding to ensure that the components are evenly dispersed.

[0048] (3) Grinding and dispersion: The mixed paint is sent to the sand mill for grinding and dispersion until the paint fineness reaches the required level (e.g. not more than 20 μm). During the grinding process, pay attention to controlling the temperature and stirring speed to avoid overheating of the paint or the generation of bubbles.

[0049] Example 2

[0050] A temperature-indicating coating for high-temperature heating surfaces of boilers comprises the following components in percentage: 4% zinc oxide coating, 4% bismuth oxide, 4% chromium oxide, 8% cobalt chloride, 8% cobalt phosphate, 8% chrome yellow (PbCrO4), 8% copper mercury iodide, 35% high-temperature resistant ceramic substrate, 5% cerium oxide, 18% boron nitride, 5% sodium silicate, 5% aluminum oxide, and the balance is isopropyl alcohol solvent. The components and their functions are shown in Table 3.

[0051] Table 3 Composition and function of temperature indicating coating for high temperature heating surface of boiler

[0052] Element effect Ratio range (%) zinc oxide <300℃discoloration 4 Bismuth oxide 300-400℃ color change 4 Chromium oxide 400-500℃ color change 4 Cobalt chloride 500-600℃ color change 8 Cobalt phosphate 600-700℃ color change 8 <![CDATA[Chrome Yellow (PbCrO4)]]> 700-800℃ color change 8 Copper mercury iodide 800-1000℃ color change 8 Zirconia Provide high temperature resistance, corrosion resistance and strength support 20 Cerium oxide Provide high temperature corrosion resistance of the coating 5 Boron nitride Improve coating wear resistance 18 Isopropyl alcohol Adjust the viscosity and fluidity of the paint to facilitate construction margin Sodium silicate Ensure that the coating components are tightly bonded to form a stable structure 5 Alumina Improve the overall performance and construction performance of the coating 5

[0053] Example 3

[0054] like Figure 1 As shown, a boiler high-temperature heating surface overtemperature warning system includes:

[0055] Functional coating, applying the boiler high-temperature heating surface temperature indicating coating described in Example 1 or 2 to the boiler high-temperature heating surface;

[0056] The color-temperature recognition system includes a comparative colorimetric test block and an image recognition system. The image recognition system includes the following parts:

[0057] (1) Image acquisition device: responsible for capturing the image or video stream to be identified and converting it into digital signals for subsequent processing.

[0058] (2) Image preprocessing module: This module performs preprocessing operations such as denoising, contrast enhancement, and color correction on the collected images to improve the accuracy and stability of color recognition. The preprocessing step can effectively reduce the impact of environmental factors (such as lighting and shadows) on color recognition and improve the robustness of the system.

[0059] (3) Color recognition algorithm module: Color space conversion: Convert the image from the RGB color space to a color space more suitable for color recognition (such as HSV, Lab, etc.). Color segmentation: Use color thresholds, clustering algorithms, and other methods to segment the color areas in the image. Color recognition: Based on the segmented color areas, identify and extract specific color information (such as color name, RGB value, HSV value, etc.). Through precise color recognition algorithms, the system can accurately distinguish different colors in the image, providing reliable data support for subsequent color analysis and statistics.

[0060] (4) Data storage and management module: responsible for storing and managing color recognition results, original images and other data, and supporting data query, retrieval and export.

[0061] Finally, a color-temperature recognition system is used to capture the color changes of the coatings on the boiler's high-temperature heating surfaces. First, a high-resolution camera or image sensor is used to capture the color of the coatings on the boiler's high-temperature heating surfaces in real time. These coatings are designed to change color significantly with temperature changes at high temperatures. The captured images undergo preprocessing, including noise removal, contrast enhancement, and color correction, to improve image quality and facilitate subsequent processing. The system then compares the preprocessed images with pre-set comparison colorimetric test blocks. These colorimetric test blocks represent standard color samples at different temperatures. An image template matching algorithm is used to find the colorimetric test block that most closely matches the color in the captured image, thereby determining the temperature corresponding to that color region. Once the temperature corresponding to the color is determined, the system calculates the temperature distribution map for the entire heating surface based on the color information of each pixel or color region in the image. If the temperature in a region exceeds the specified operating temperature of the material, a temperature warning is issued for that region.

[0062] Example 4

[0063] A boiler high-temperature heating surface overtemperature early warning method comprises the following steps:

[0064] (1) Comparative color test block under multiple temperature ranges: The same material (15CrMo) of the boiler water-cooled wall was selected to coat the boiler high-temperature heating surface temperature indicating coating (coating layer 70 μm) prepared in Example 1, and the temperature was slowly increased from room temperature to 1000°C to obtain a continuous seven-color color change area comparative color test block, as shown in FIG. Figure 2 As shown;

[0065] (2) Spraying and Curing: This embodiment selects an ultra-supercritical boiler with frequent deep peak regulation as the coating application target. The boiler water-cooled wall area prone to overheating (selecting a single wall in the lower furnace prone to overheating with an elevation of 20-40 meters and a width of 7 meters) is coated with the boiler's high-temperature heating surface temperature-indicating coating. Since it is a multi-component coating, the thickness is greater than that of a single-component coating, preferably 70 μm. Then, the coating is heated at 50°C for 10 minutes and then cured for 2 hours.

[0066] (3) After the boiler has been running for an overhaul period, the color information of the coated area is collected using the image recognition system of the color-temperature recognition system, and a color change diagram is obtained as shown in the figure. Figure 3 After collecting the color information of the over-temperature discoloration part using the colorimeter of the image recognition system, the image fitting and comparison with the comparison test blocks under multiple temperature intervals are performed to obtain the accurate temperature range of the over-temperature part as shown below. Figure 4 shown.

[0067] 15CrMo steel is a heat-resistant alloy steel that exhibits excellent mechanical and thermal properties within a certain high temperature range. Specifically, the maximum operating temperature of 15CrMo steel can reach 540°C, and the typical wall temperature warning is around 490°C. As the temperature gradually increases, the performance of 15CrMo steel gradually decreases. Figure 4 The image clearly shows the location and size of the temperature region exceeding 490°C. This uneven overheating pattern is consistent with the differential overheating of the water-cooled wall during deep peak regulation. Overheating leads to material degradation, and the uneven distribution of heat causes thermal stress in the furnace tubes.

[0068] according to Figure 4 Based on the temperature distribution diagram, the following adjustments were made to the boiler: (1) Optimizing the air distribution method: Adjusting the ratio of primary and secondary air to ensure sufficient and evenly distributed air volume in the combustion area effectively avoids local overheating. (2) Hydrodynamic adjustment: Ensure unobstructed water circulation in the water-cooled wall. Increase the number of circulating pumps, adjust the flow rate of the entire circulating pump, or adjust the throttle ring aperture to improve the water circulation condition locally and make the temperature tend to be balanced.

[0069] At the same time, due to the preservatives and wear-resistant agents added to the coating, no serious high-temperature corrosion and furnace wear were found on the water-cooled wall during this overhaul.

[0070] Example 5

[0071] A method for early warning of overtemperature of a high-temperature heating surface of a boiler, which differs from Example 4 in that: in step (1), a comparative colorimetric test block is prepared by coating a material (HR3C) of the same material as the boiler high-temperature superheater tube with the boiler high-temperature heating surface temperature indicating coating of Example 2. In step (2), a half-panel high-temperature superheater tube (7 tubes) connected to the inlet header of a 1000MW unit is selected as the application object, and the boiler high-temperature heating surface temperature indicating coating of Example 2 is used to apply an irreversible temperature indicating coating to the boiler high-temperature superheater tube panel, with a coating thickness of 70 μm.

[0072] After the operation, a furnace tube leak occurred at the lower elbow of the high-temperature superheater, causing an unplanned shutdown of the unit. During the shutdown accident analysis, the color information of the coated area was collected to obtain a color change diagram, such as Figure 5 After collecting the color information of the over-temperature color change part using a colorimeter and performing image fitting and comparison with the color comparison test blocks under multiple temperature intervals, the accurate temperature range of the high-temperature superheater is obtained, as shown in the figure below. Figure 6 shown.

[0073] HR3C steel is an austenitic heat-resistant steel with excellent high-temperature performance. It boasts excellent steam oxidation resistance, high allowable stress, and good high-temperature corrosion resistance. It is widely used in superheater and reheater tubes in ultra-supercritical boilers, where flue gas temperatures are high. These units typically operate at high temperatures, typically above 566°C, 600°C, or even 620°C. The overtemperature warning threshold for the HR3C high-temperature superheater tubes in this unit is set at 590°C. The purple area, representing the coating's color change temperature, is 600-610°C, representing normal operating temperatures. The orange-red area, representing 700-800°C, indicates the furnace tubes have reached their upper operating temperature limit. The burst was identified as the lower elbow at the outermost ring of the tube panel. The overtemperature color area also identifies the area (orange-red) where the tube section should be replaced.

[0074] The above contents are merely examples and explanations of the present invention. Those skilled in the art may make various modifications or additions to the described specific embodiments or replace them in similar ways. As long as they do not deviate from the structure of the present invention or exceed the scope defined by the claims, they shall fall within the scope of protection of the present invention.

Claims

1. A temperature indicating coating for a high temperature heating surface of a boiler, characterized in that: The invention comprises the following components in percentage by mass: 5%-8% of a thermosensitive pigment A which changes color at a temperature lower than 300°C, 5%-8% of a thermosensitive pigment B which changes color at a temperature between 300 and 400°C, 5%-8% of a thermosensitive pigment C which changes color at a temperature between 400 and 500°C, 5%-8% of a thermosensitive pigment D which changes color at a temperature between 500 and 600°C, 5%-8% of a thermosensitive pigment E which changes color at a temperature between 600 and 700°C, 5%-8% of a thermosensitive pigment F which changes color at a temperature between 700 and 800°C, 5%-8% of a thermosensitive pigment G which changes color at a temperature between 800 and 1000°C, 20% of a ceramic matrix, 5% of an anticorrosive agent, 5% of a wear-resistant filler, 10%-15% of a binder, 5% of a stabilizer, and the remainder of a solvent. Wherein, the heat-sensitive pigment A is zinc oxide or lead white; the heat-sensitive pigment B is cobalt sulfate heptahydrate or bismuth oxide; the heat-sensitive pigment C is cobalt sulfate or chromium oxide; the heat-sensitive pigment D is cobalt chloride; the heat-sensitive pigment E is cobalt phosphate; the heat-sensitive pigment F is chrome yellow; the heat-sensitive pigment G is copper mercury iodide; The anticorrosive agent is silicate or aluminate; the solvent is ethyl acetate or isopropyl alcohol; the adhesive is sodium silicate; and the stabilizer is aluminum oxide.

2. The temperature indicating paint for high temperature heating surface of a boiler according to claim 1, characterized in that: The ceramic matrix is ​​zirconia.

3. The temperature indicating paint for high temperature heating surface of a boiler according to claim 1, characterized in that: The wear-resistant filler is silicon carbide or boron nitride.

4. A method for preparing a temperature indicating coating for a high temperature heating surface of a boiler according to any one of claims 1 to 3, characterized in that: The following steps are involved: (1) First add the solvent to the mixing container, then add the adhesive, stir until the adhesive is completely dissolved in the solvent, then add the stabilizer, anti-corrosion agent, all heat-sensitive pigments, wear-resistant fillers and other raw materials in sequence, stirring while adding to ensure that all components are evenly dispersed; (2) The mixed paint is sent to a sand mill for grinding and dispersion until the paint fineness reaches the required level.

5. A boiler high temperature heating surface overtemperature warning system, characterized in that: include: Functional coating, wherein the boiler high-temperature heating surface temperature indicating coating according to any one of claims 1 to 3 is applied to the boiler high-temperature heating surface; The color-temperature recognition system includes a comparative colorimetric test block and an image recognition system. The image recognition system is used to collect color changes of the coating on the high-temperature heating surface of the boiler, and perform image fitting and comparison with the comparative colorimetric test block, converting it into a recognizable signal to achieve temperature early warning.

6. A boiler high temperature heating surface overtemperature early warning method, characterized in that: The following steps are involved: (1) Comparative colorimetric test blocks under multiple temperature ranges: an alloy test block with the same material and roughness as the high-temperature heating surface of a boiler is selected and coated with the boiler high-temperature heating surface temperature indicating coating according to any one of claims 1 to 3, and then the temperature is slowly increased in the temperature range from room temperature to 1000°C to obtain a comparative test block with continuous seven color change areas; (2) Spraying and curing: spraying the boiler high-temperature heating surface temperature indicating paint according to any one of claims 1 to 3 evenly on the boiler high-temperature heating surface, and performing heating and curing treatment; (3) After using the image recognition system to collect data on the color information of the over-temperature discoloration part, the image fitting and comparison are performed with the comparison test blocks under multiple temperature ranges to obtain the precise temperature range of the over-temperature part.

Images