Boiler heating surface anti-over-temperature coating heat insulation performance testing device and testing method

Abstract

The present disclosure provides a boiler heating surface anti-over-temperature coating heat insulation performance testing device and testing method, and relates to the technical field of surface engineering. The testing device comprises a boiler pipe, a heating unit and a temperature measuring unit; wherein the outer side of the boiler pipe is coated with a heat insulation coating to be tested; the heating unit comprises a first heating assembly and a second heating assembly, the first heating assembly is used for heating a fluid medium flowing into the inside of the boiler pipe; the second heating assembly is sleeved on the outer side of the boiler pipe and is used for heating the outer wall of the boiler pipe to simulate the temperature of the furnace; the temperature measuring unit comprises a first temperature measuring assembly and a second temperature measuring assembly; the first temperature measuring assembly is arranged in the inside of the furnace of the second heating assembly; the second temperature measuring assembly is arranged at the interface between the boiler pipe and the heat insulation coating to be tested. The present disclosure synchronously simulates the real temperature environment of the high-temperature fluid in the inside of the boiler pipe and the flue gas outside the furnace through the double heating assemblies, so that the test result can accurately reflect the actual application performance of the coating.

Description

Technical Field

[0001] This disclosure relates to the field of surface engineering technology, and in particular to a testing device and method for testing the thermal insulation performance of a boiler heating surface overheat protection coating. Background Technology

[0002] Deep peak shaving in thermal power units has become the norm, and the problem of overheating of boiler heating surfaces is becoming increasingly prominent. Applying heat-insulating coatings is an efficient and economical solution. However, existing laboratory testing methods mostly use a single heat source, which cannot simulate the real temperature environment inside and outside the pipeline. The test results deviate greatly from actual applications, making it difficult to accurately evaluate the coating performance. There is an urgent need to develop testing devices and methods that can accurately simulate actual working conditions. Summary of the Invention

[0003] To overcome the problems existing in related technologies, this disclosure provides a testing device and method for testing the thermal insulation performance of boiler heating surface overheat protection coating.

[0004] According to a first aspect of the present disclosure, a test device for the thermal insulation performance of a boiler heating surface overheat protection coating is provided, comprising: a boiler tube, a heating unit, and a temperature measuring unit; The outer side of the boiler tube is coated with the heat insulation coating to be tested; The heating unit includes: a first heating component and a second heating component. The first heating component is used to heat the fluid medium introduced into the boiler tube to simulate the fluid temperature environment inside the boiler heating surface. The second heating component is sleeved on the outside of the boiler tube and is used to heat the outer wall of the boiler tube to simulate the flue gas temperature environment in the boiler furnace. The temperature measurement unit includes: a first temperature measurement component and a second temperature measurement component; the first temperature measurement component is disposed inside the furnace of the second heating component and is used to measure the furnace temperature; the second temperature measurement component is disposed at the interface between the boiler tube and the heat insulation coating to be measured and is used to measure the interface temperature. The heat insulation temperature of the heat insulation coating is the difference between the furnace temperature measured by the first temperature measuring component and the interface temperature measured by the second temperature measuring component.

[0005] In some embodiments, the first heating component is a medium heating furnace, and the second heating component is a tubular furnace, wherein the inner diameter of the furnace chamber of the tubular furnace is larger than the outer diameter of the boiler tube; when the furnace chamber is in a closed state, a closed space is formed inside the furnace chamber.

[0006] In some embodiments, the second temperature measuring component is embedded inside the wall of the boiler tube, and the distance between it and the outer wall of the boiler tube is 0.5~2mm; or The second temperature measuring component is welded with a protective sleeve on the outside, and the heat insulation coating to be tested is applied to the outer surface of the boiler tube with the protective sleeve welded on.

[0007] In some embodiments, the temperature measuring unit further includes: a third temperature measuring component and a fourth temperature measuring component; The third temperature measuring component is located at the inlet of the boiler tube and is used to measure the temperature of the fluid medium at the inlet. The fourth temperature measuring component is located at the outlet of the boiler tube and is used to measure the temperature of the fluid medium at the outlet.

[0008] In some embodiments, the thermal insulation coating to be tested includes a base coat and a thermal insulation layer sequentially coated on the outer surface of the boiler tube, wherein the thickness of the base coat is less than or equal to the thickness of the thermal insulation layer.

[0009] In some embodiments, the length of the thermal insulation coating to be tested is greater than the length of the boiler tube located within the second heating assembly; The second temperature measuring component is used to measure the midpoint of the thermal insulation coating under test and / or the boiler tube along its length.

[0010] In some embodiments, the fluid medium includes at least one of nitrogen, argon, helium, water vapor, and carbon dioxide.

[0011] According to a second aspect of the present disclosure, a method for testing the thermal insulation performance of an overheat-resistant coating on a boiler heating surface is provided, applied to the testing device for testing the thermal insulation performance of an overheat-resistant coating on a boiler heating surface described in the first aspect of the present disclosure, the method comprising: The thermal insulation coating to be tested is applied to the outer surface of the boiler tube; The fluid medium is heated by the first heating component and then introduced into the boiler tube, so that the inlet temperature of the fluid medium is consistent with the internal design temperature of the target boiler heating surface. The outer wall of the boiler tube is heated by the second heating component to simulate the flue gas temperature environment of the boiler furnace. The furnace temperature of the second heating component and the interface temperature between the boiler tube and the insulation coating were collected respectively. The insulation temperature of the insulation coating to be tested is determined based on the furnace temperature and the interface temperature.

[0012] In some embodiments, the interface temperature is acquired in the following manner: The interface temperature is collected based on a second temperature measuring component embedded inside the boiler tube wall; or The interface temperature is collected by a second temperature measuring component installed inside a protective sleeve welded to the outer wall of the boiler tube.

[0013] In some embodiments, determining the insulation temperature of the insulation coating to be tested based on the furnace temperature and the interface temperature includes: The difference between the furnace temperature and the interface temperature is taken as the insulation temperature of the insulation coating to be tested.

[0014] The testing apparatus provided in this disclosure includes a boiler tube, a heating unit, and a temperature measuring unit. The boiler tube is coated with a heat-insulating coating to be tested. The heating unit includes a first heating component and a second heating component. The first heating component heats the fluid medium introduced into the boiler tube to simulate the fluid temperature environment inside the boiler's heating surface. The second heating component is fitted onto the outside of the boiler tube to heat the outer wall of the boiler tube to simulate the flue gas temperature environment in the boiler furnace. The temperature measuring unit includes a first temperature measuring component and a second temperature measuring component. The first temperature measuring component is disposed inside the furnace of the second heating component to measure the furnace temperature. The second temperature measuring component is disposed at the interface between the boiler tube and the heat-insulating coating to be tested to measure the interface temperature. The heat-insulating temperature of the coating is the difference between the furnace temperature measured by the first temperature measuring component and the interface temperature measured by the second temperature measuring component. This disclosure eliminates the deviation between traditional testing methods and actual service environments by simultaneously simulating the real temperature environment of the high-temperature fluid inside the boiler tube and the external flue gas in the furnace using dual heating components. The test results can accurately reflect the actual application performance of the coating. Attached Figure Description

[0015] Figure 1 This diagram shows a structural schematic of a test device for testing the thermal insulation performance of a boiler heating surface overheat protection coating, according to an embodiment of the present disclosure. Figure 2 This diagram illustrates the structure of the interface temperature measurement method embedded in the inner wall according to an embodiment of the present disclosure. Figure 3 A physical schematic diagram of the interface temperature measurement method embedded in the inner wall according to an embodiment of this disclosure is shown; Figure 4 A cross-sectional view of a boiler tube is shown in the embodiment of the interface temperature measurement method embedded in the inner wall of this disclosure. Figure 5 This diagram illustrates the structure of the interface temperature measurement method using an outer wall sleeve in an embodiment of the present disclosure. Figure 6 This diagram shows a temperature measuring boiler tube after spraying, as shown in an embodiment of the present disclosure. Figure 7 This diagram illustrates a process flow chart for testing the thermal insulation performance of an overheat-resistant coating on a boiler heating surface, according to an embodiment of this disclosure. Figure 8 This diagram illustrates the thermal insulation temperature fitting results for coatings of various thicknesses at different external wall temperatures in embodiments of this disclosure. Detailed Implementation

[0016] Exemplary embodiments will now be described in detail, examples of which are illustrated in the accompanying drawings. When the following description relates to the drawings, unless otherwise indicated, the same numerals in different drawings denote the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with this disclosure. Rather, they are merely examples of apparatuses and methods consistent with some aspects of this disclosure as detailed in the appended claims.

[0017] The boiler heating surface overheat protection coating insulation performance testing device provided in this embodiment achieves accurate measurement of insulation temperature through dual heating components and multiple temperature measurement components. It is suitable for simulation testing of the overheat protection coating insulation performance of superheaters and reheaters in thermal power plants, and can effectively improve the reliability of coating research and development.

[0018] Specifically, Figure 1 This diagram illustrates the structure of a test device for testing the thermal insulation performance of a boiler heating surface overheat protection coating, according to an embodiment of this disclosure. Figure 1 As shown, the device includes: boiler tube 1, heating unit and temperature measuring unit.

[0019] Among them, boiler tube 1 uses the same material and specifications as the heating surface of the actual power plant boiler, and its outer side is coated with the heat insulation coating 8 to be tested.

[0020] The heating unit includes a first heating component 2 and a second heating component 3. The first heating component 2 is used to heat the fluid medium 9 that is introduced into the boiler tube 1 to simulate the fluid temperature environment inside the boiler heating surface. The second heating component 3 is sleeved on the outside of the boiler tube 1 and is used to heat the outer wall of the boiler tube 1 to simulate the flue gas temperature environment in the boiler furnace.

[0021] The temperature measurement unit includes: a first temperature measurement component 4 and a second temperature measurement component 5; the first temperature measurement component 4 is disposed inside the furnace of the second heating component 3 and is used to measure the furnace temperature; the second temperature measurement component 5 is disposed at the interface between the boiler tube 1 and the heat insulation coating 8 to be measured and is used to measure the interface temperature.

[0022] The insulation temperature of the heat insulation coating is the difference between the furnace temperature measured by the first temperature measuring component 4 and the interface temperature measured by the second temperature measuring component 5.

[0023] In some embodiments, the first heating component 2 is a medium heating furnace, and the second heating component 3 is a tubular furnace, wherein the inner diameter of the furnace chamber of the tubular furnace is larger than the outer diameter of the boiler tube 1. This design ensures that the boiler tube 1 is heated uniformly within the furnace chamber, avoiding local temperature differences from affecting the test results.

[0024] When the furnace is closed, a closed space is formed inside the furnace, which can effectively reduce heat loss and make the temperature distribution inside the furnace more uniform. At this time, the temperature of the furnace can approximately represent the temperature of the outer wall of the sample to be tested, further improving the accuracy of the test.

[0025] In some embodiments, the second temperature measuring component 5 is positioned at the middle position along the length of the heat insulation coating 8 and / or boiler tube 1 to be measured. This position is the area with the most uniform temperature distribution in the furnace, which can effectively avoid the influence of temperature gradients at the furnace inlet and outlet, and further improve the accuracy of interface temperature measurement.

[0026] In some embodiments, the temperature measuring unit further includes a third temperature measuring component 6 and a fourth temperature measuring component 7. The third temperature measuring component 6 is located at the inlet of the boiler tube 1 and is used to measure the temperature of the fluid medium 9 at the inlet; the fourth temperature measuring component 7 is located at the outlet of the boiler tube 1 and is used to measure the temperature of the fluid medium 9 at the outlet. By monitoring the temperature change of the fluid medium 9 flowing through the pipeline 10 to the inlet and outlet of the boiler tube 1 after being heated by the first heating component 2, the heat exchange situation inside the boiler tube 1 can be grasped in real time, ensuring that the internal fluid temperature is stable at the target design value, and at the same time, it can help verify the heat insulation effect of the coating.

[0027] In some embodiments, the thermal insulation coating 8 to be tested includes a base layer and a thermal insulation layer sequentially coated on the outer surface of the boiler tube 1, wherein the thickness of the base layer is less than or equal to the thickness of the thermal insulation layer. The base layer is typically made of NiCrAlY alloy material, which can improve the bonding strength between the thermal insulation layer and the substrate of the boiler tube 1 and prevent the coating from peeling off; the thermal insulation layer is typically made of YSZ (yttrium-stabilized zirconia) ceramic material, which has excellent high-temperature thermal insulation performance.

[0028] Furthermore, the coating length of the heat insulation coating 8 to be tested is greater than the length of the boiler tube 1 located in the furnace of the second heating component 3 (for example, 100~200mm longer than the boiler tube 1), so that the coating completely covers the heated tube section in the furnace and extends to both ends, avoiding the thermal edge effect at the end of the furnace that causes uneven local temperature of the tube section, and ensuring that the heat flux density in the test area is uniform and stable.

[0029] In some embodiments, the fluid medium 9 includes at least one of nitrogen, argon, helium, water vapor, and carbon dioxide. Using an inert gas as a heat transfer medium can prevent oxidation and corrosion of the inner wall of the boiler tubes at high temperatures, while ensuring that the heat transfer process is stable and controllable. Using nitrogen, carbon dioxide, or water vapor as a heat transfer medium can more closely resemble the working environment of the boiler during actual operation, further improving the authenticity of the test conditions.

[0030] In some embodiments, the testing apparatus provided in this disclosure is further configured with a temperature display, i.e. Figure 1The first temperature display 11, the second temperature display 12, the third temperature display 13, the fourth temperature display 14, and the fifth temperature display 15 are shown in the figure.

[0031] The first temperature display 11 is electrically connected to the first temperature measuring component 4 and is used to display the measured temperature inside the furnace of the tubular furnace in real time (furnace temperature T2); the second temperature display 12 is electrically connected to the second temperature measuring component 5 and is used to display the interface temperature between the boiler tube and the insulation coating to be measured in real time (interface temperature T5); the third temperature display 13 is electrically connected to the third temperature measuring component 6 and is used to display the fluid medium temperature at the inlet of the boiler tube in real time (inlet temperature T3); the fourth temperature display 14 is electrically connected to the fourth temperature measuring component 7 and is used to display the fluid medium temperature at the outlet of the boiler tube in real time (outlet temperature T4); the fifth temperature display 15 is electrically connected to the first heating component alone and is used to display the set and actual heating temperature of the medium heating furnace in real time (medium heating furnace temperature T1).

[0032] Each temperature display independently acquires signals from its corresponding temperature sensing element, without interfering with each other. It can synchronously and in real time observe five temperature parameters, making it convenient for test personnel to adjust the heating power and record test data in real time.

[0033] Next, we will combine Figures 2 to 6 This section explains two methods for measuring interface temperature, each corresponding to different application scenarios.

[0034] First, please refer to Figure 2 , Figure 2 A schematic diagram of an interface temperature measurement method embedded in the inner wall according to an embodiment of this disclosure is shown. Figure 2 As shown, the second temperature measuring component 5 is embedded inside the wall of the boiler tube 1, at a distance of 0.5~2mm from the outer wall of the boiler tube 1, and this area is encapsulated. The wall thickness of the boiler tube 1 is typically 5mm. Embedding the measuring component at a distance of 0.5~2mm from the outer wall can accurately reflect the true temperature at the interface between the coating and the substrate, while avoiding interference from the measuring component with the coating process and heat conduction. This method is used to simulate the situation where there is no temperature measuring device on the outer wall of the power plant boiler tube. It can eliminate the influence of the temperature measuring element on heat conduction, accurately measure the inherent thermal insulation performance of the coating itself, and provide accurate data support for the basic research and formulation optimization of coating materials. The dispersion of the test data can be controlled within 3%.

[0035] Specifically, Figure 3 The method for measuring interface temperature by embedding an inner wall in an embodiment of this disclosure is illustrated using physical photographs. Figure 3As shown, when preparing the sample to be tested, the middle section of boiler tube 1 is cut and separated. Temperature measuring holes are radially opened along the tube wall at the center of the cut and separated tube body. The bottom of the temperature measuring hole is 0.5~2mm from the outer surface of boiler tube 1, and the hole diameter is controlled at 4~5mm. A nickel-chromium-nickel-silicon thermocouple is selected as the temperature measuring element of the second temperature measuring component 5. The thermocouple measuring point is fixed to the bottom of the temperature measuring hole using an energy storage spot welding process. After the spot welding is completed, the temperature measuring hole is filled and sealed with high-temperature resistant repair agent 17. The sealing treatment can block the flow of heat inside the boiler tube. The medium gas flow enters the temperature measuring hole, avoiding the temperature measurement error caused by airflow disturbance, and greatly reducing the interference of the gas flow in the furnace on the interface temperature test results. After the sealing is completed, the segmented sample with the thermocouple pre-embedded is restored and spliced ​​with the original boiler tube 1 by welding process, restoring the complete and sealed tubular structure of boiler tube 1. The low temperature lead-out section of the pre-embedded thermocouple wire 16 passes out from the inner cavity of boiler tube 1, and the final lead is electrically connected to the second temperature display 12. The second temperature display 12 collects and displays the interface temperature T5 between the coating and the boiler tube substrate in real time.

[0036] Further reference Figure 4 The diagram shows a cross-sectional view of a boiler tube 1 with embedded thermocouple wires 16. The cross-section clearly shows a four-layer structure: the outermost layer is a spray-coated heat-insulating coating 8; below this is the boiler tube's base metal layer; the thermocouple wires 16, with a spiral twisted structure, are inserted into holes within the base metal; the gaps between the thermocouple wires 16 and the sidewalls of the holes are tightly filled and sealed with a high-temperature resistant repair agent 17; and the wall thickness from the bottom of the temperature measuring hole to the outer wall of the boiler tube is strictly controlled within 0.5~2mm. This size setting ensures that the thermocouple measuring point accurately falls at the true interface between the coating and the metal substrate, while preventing excessive hole depth from compromising the structural strength of the boiler tube base.

[0037] Next, please refer to Figure 5 , Figure 5 A schematic diagram of an interface temperature measurement method using an outer wall sleeve in an embodiment of this disclosure is shown. Figure 5 As shown, a protective sleeve is welded to the outside of the second temperature measuring component 5, and the heat insulation coating 8 to be tested is applied to the outer surface of the boiler tube 1 with the protective sleeve welded on. The protective sleeve is made of the same metal material as the boiler tube 1 and is welded and fixed to the outer wall surface of the boiler tube 1. After welding, the welded area is ground smooth to eliminate sharp edges, so as to facilitate uniform deposition of the coating and ensure the bonding quality between the coating and the substrate.

[0038] The temperature measuring boiler tube after spraying is like Figure 6As shown, the coating evenly covers the surface of boiler tube 1 and the protective sleeve, without obvious defects such as bulges or cracks. This method is used to simulate the temperature measurement method in the field application of boiler tubes. It can realistically reproduce the actual working conditions after the temperature measuring element is installed on site. It takes into account the influence of the protective sleeve on heat conduction. The test results are closer to the heat insulation effect of the coating in actual engineering applications. It can directly guide the selection of coating and construction process on site, and avoid the problem of poor overheat control effect caused by the deviation between laboratory test and field working conditions.

[0039] Based on the same inventive concept, this disclosure also provides a method for testing the thermal insulation performance of an overheat-resistant coating on a boiler heating surface. This method can be executed by any electronic device, as shown in the following embodiments. Since the principle of this method embodiment in solving the problem is the same as that described above... Figure 1 The method embodiments shown are similar, therefore, the implementation of the method embodiments can be found in the above description. Figure 1 The implementation of the method embodiments shown will not be repeated here.

[0040] Figure 7 This diagram illustrates a flow chart of a method for testing the thermal insulation performance of an overheat protection coating on a boiler heating surface, as described in an embodiment of this disclosure. Figure 7 As shown, the method includes the following steps S701 to S705.

[0041] S701, the heat insulation coating to be tested is applied to the outer surface of the boiler tube.

[0042] S702, the fluid medium is heated by the first heating component and then introduced into the boiler tube to maintain the inlet temperature of the fluid medium consistent with the internal design temperature of the target boiler heating surface.

[0043] S703 heats the outer wall of the boiler tubes through a second heating component to simulate the flue gas temperature environment of the boiler furnace.

[0044] S704 collects the furnace temperature of the second heating component and the interface temperature between the boiler tube and the heat insulation coating, respectively.

[0045] S705, determine the insulation temperature of the insulation coating to be tested based on the furnace temperature and interface temperature.

[0046] In some embodiments, the interface temperature is acquired in the following ways: based on a second temperature measuring component embedded inside the boiler tube wall; or based on a second temperature measuring component installed inside a protective sleeve welded to the outer wall of the boiler tube.

[0047] In some embodiments, determining the insulation temperature of the insulation coating to be tested based on the furnace temperature and the interface temperature includes: using the difference between the furnace temperature and the interface temperature as the insulation temperature of the insulation coating to be tested.

[0048] The testing method in this embodiment strictly simulates the actual service temperature environment of the boiler heating surface. The testing process is standardized, and the test results between different laboratories are highly comparable, which can provide a basis for the industry to establish a unified performance testing standard for thermal insulation coatings.

[0049] To further verify the effectiveness of the device and method disclosed herein, the implementation process and technical effects of the embodiments of this disclosure will be described in detail below in conjunction with specific application scenarios.

[0050] Based on the overheating conditions of the final stage reheater in a power plant, this embodiment designed four YSZ thermal insulation coatings with thicknesses of 100μm, 300μm, 400μm, and 500μm. A NiCrAlY coating with a thickness of 0.1mm was used as the base layer. The thermal insulation temperature was tested using both internal and external wall temperature measurement methods using the aforementioned testing device.

[0051] During the test, the inlet air temperature of the insulation coating section was maintained at approximately the design temperature of 331℃. By adjusting the power of the tubular furnace, the furnace temperature was controlled at three levels: 719℃, 819℃, and 920℃. Data was collected after each temperature point stabilized, and the insulation temperature was calculated. The insulation temperature records are shown in Tables 1 to 4 below. In Tables 1 to 4, temperature T1 controls the temperature T3 before the fluid medium enters the boiler tube heating section; T2 simulates the furnace boiler tube outer wall temperature; T4 obtains the outlet medium temperature; and T5 obtains the coating / furnace tube metal outer wall temperature. The insulation temperature of the insulation coating, ΔT = T2 - T5.

[0052] (1) Test results of the inner wall embedded type.

[0053] Table 1 shows the thermal insulation temperature test results for a 100-micron thick thermal insulation coating. ΔT (thermal insulation temperature) = T2 (external temperature of the coating) - T5 (interface temperature between the coating and the substrate). It can be observed that the higher the external temperature, the higher the thermal insulation temperature caused by the coating under the same conditions. At a temperature of 920℃, the thermal insulation temperature is 110.3℃; when the temperature decreases to 719℃, the thermal insulation temperature decreases to 75.9℃.

[0054] Table 1. Thermal insulation temperature test of 100μm thick thermal insulation coating / °C

[0055] Table 2 shows the thermal insulation temperature test results for a 300μm thick thermal insulation coating. It can be observed that, under the same conditions, the higher the external temperature, the higher the thermal insulation temperature caused by the coating. At a temperature of 920℃, the thermal insulation temperature is 135.8℃, and when the temperature decreases to 719℃, the thermal insulation temperature decreases to 118.7℃. The overall thermal insulation temperature is higher than that of a 100μm coating. Increased coating thickness leads to an increase in thermal insulation temperature.

[0056] Table 2. Thermal insulation temperature test of 300μm thick thermal insulation coating

[0057] Table 3 shows the thermal insulation temperature test results of a 400μm thick thermal insulation coating. It can be observed that the higher the external temperature, the higher the thermal insulation temperature caused by the coating under the same conditions. At a temperature of 920℃, the thermal insulation temperature is 166℃; when the temperature decreases to 719℃, the thermal insulation temperature decreases to 124.1℃.

[0058] Table 3. Thermal insulation temperature test of 400μm thick thermal insulation coating

[0059] Table 4 shows the thermal insulation temperature test results of a 500μm thick thermal insulation coating. It can be observed that the higher the external temperature, the higher the thermal insulation temperature caused by the coating under the same conditions. At a temperature of 920℃, the thermal insulation temperature is 194.6℃, and when the temperature decreases to 719℃, the thermal insulation temperature decreases to 135.8℃. Compared to a thinner coating, its thermal insulation temperature is further increased.

[0060] Table 4. Thermal insulation temperature test of 500μm thick thermal insulation coating

[0061] The test results above show that, under the same conditions, the higher the external temperature of the coating, the higher the insulation temperature of the coating; the greater the coating thickness, the higher the insulation temperature. When the coating thickness is 500μm and the furnace temperature is 920℃, the insulation temperature can reach 194.6℃, which can effectively reduce the wall temperature of the boiler tubes and meet the over-temperature prevention requirements under deep peak shaving conditions.

[0062] By linearly fitting the insulation temperatures of coatings of various thicknesses at different external wall temperatures, the following results can be obtained: Figure 8 The results are shown below. Based on the fitting results, the following conclusions can be drawn: First, as the thickness increases, the insulation temperature of the coating also increases; second, the higher the outer wall temperature, the more obvious the insulation effect of the coating; third, the higher the outer wall temperature, the smaller the deviation between the test results and the fitted line, indicating that the device has better test stability under high-temperature conditions. This is highly consistent with the high-temperature environment of the boiler's actual operation, further enhancing the engineering reference value of the test results.

[0063] (2) Test results of external sleeve type temperature measurement method To simulate the on-site installation of temperature sensing elements, this embodiment also employs an external wall temperature measurement method for comparative testing. In this method, the thermocouple protective sheath is fixed to the boiler tube surface by welding. To facilitate coating deposition, the welded surface is ground smooth and sharp edges are eliminated. Then, a plasma spraying process is used to apply coatings of different thicknesses according to optimized parameters. For comparative analysis, this embodiment also includes a blank control group without coating to analyze the impact of the welded area on the test results.

[0064] The test results are shown in Table 5 below: Table 5 Test results of thermal insulation temperature (°C)

[0065] As shown in Table 5, the thermal insulation temperature of the coating increases with the increase of the outer wall temperature, that is, the thermal insulation temperature increases with the increase of the coating thickness.

[0066] Other embodiments of this disclosure will readily occur to those skilled in the art upon consideration of the specification and practice of the invention disclosed herein. This disclosure is intended to cover any variations, uses, or adaptations of this disclosure that follow the general principles of this disclosure and include common knowledge or customary techniques in the art not disclosed herein. The specification and examples are to be considered exemplary only, and the true scope and spirit of this disclosure are indicated by the appended claims.

Claims

1. A device for testing the thermal insulation performance of an overheat-resistant coating on a boiler heating surface, characterized in that, include: Boiler tubes, heating unit, and temperature measurement unit; The outer side of the boiler tube is coated with the heat insulation coating to be tested; The heating unit includes: a first heating component and a second heating component. The first heating component is used to heat the fluid medium introduced into the boiler tube to simulate the fluid temperature environment inside the boiler heating surface. The second heating component is sleeved on the outside of the boiler tube and is used to heat the outer wall of the boiler tube to simulate the flue gas temperature environment in the boiler furnace. The temperature measurement unit includes: a first temperature measurement component and a second temperature measurement component; the first temperature measurement component is disposed inside the furnace of the second heating component and is used to measure the furnace temperature; the second temperature measurement component is disposed at the interface between the boiler tube and the heat insulation coating to be measured and is used to measure the interface temperature. The heat insulation temperature of the heat insulation coating is the difference between the furnace temperature measured by the first temperature measuring component and the interface temperature measured by the second temperature measuring component.

2. The apparatus according to claim 1, characterized in that, The first heating component is a medium heating furnace, and the second heating component is a tubular furnace. The inner diameter of the furnace chamber of the tubular furnace is larger than the outer diameter of the boiler tube. When the furnace chamber is in a closed state, a closed space is formed inside the furnace chamber.

3. The apparatus according to claim 1, characterized in that, The second temperature measuring component is embedded inside the wall of the boiler tube, and the distance between it and the outer wall of the boiler tube is 0.5~2mm; or The second temperature measuring component is welded with a protective sleeve on the outside, and the heat insulation coating to be tested is applied to the outer surface of the boiler tube with the protective sleeve welded on.

4. The apparatus according to claim 1, characterized in that, The temperature measurement unit further includes: a third temperature measurement component and a fourth temperature measurement component; The third temperature measuring component is located at the inlet of the boiler tube and is used to measure the temperature of the fluid medium at the inlet. The fourth temperature measuring component is located at the outlet of the boiler tube and is used to measure the temperature of the fluid medium at the outlet.

5. The apparatus according to claim 1, characterized in that, The heat insulation coating to be tested includes a base layer and a heat insulation layer that are sequentially coated on the outer surface of the boiler tube, wherein the thickness of the base layer is less than or equal to the thickness of the heat insulation layer.

6. The apparatus according to claim 1, characterized in that, The length of the heat insulation coating to be tested is greater than the length of the boiler tube located in the second heating component; The second temperature measuring component is used to measure the midpoint of the thermal insulation coating under test and / or the boiler tube along its length.

7. The apparatus according to any one of claims 1 to 5, characterized in that, The fluid medium includes at least one of nitrogen, argon, helium, water vapor, and carbon dioxide.

8. A method for testing the thermal insulation performance of an overheat-resistant coating on a boiler heating surface, characterized in that, The method, applied to the boiler heating surface overheat protection coating insulation performance testing device according to any one of claims 1 to 7, comprises: The thermal insulation coating to be tested is applied to the outer surface of the boiler tube; The fluid medium is heated by the first heating component and then introduced into the boiler tube, so that the inlet temperature of the fluid medium is consistent with the internal design temperature of the target boiler heating surface. The outer wall of the boiler tube is heated by the second heating component to simulate the flue gas temperature environment of the boiler furnace. The furnace temperature of the second heating component and the interface temperature between the boiler tube and the insulation coating were collected respectively. The insulation temperature of the insulation coating to be tested is determined based on the furnace temperature and the interface temperature.

9. The method according to claim 8, characterized in that, The interface temperature is collected in the following manner: The interface temperature is collected based on a second temperature measuring component embedded inside the boiler tube wall; or The interface temperature is collected by a second temperature measuring component installed inside a protective sleeve welded to the outer wall of the boiler tube.

10. The method according to claim 8, characterized in that, The step of determining the insulation temperature of the insulation coating to be tested based on the furnace temperature and the interface temperature includes: The difference between the furnace temperature and the interface temperature is taken as the insulation temperature of the insulation coating to be tested.

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