On-line test method and device for corrosion resistance of pipe on high-temperature heating surface of boiler

Abstract

The invention discloses an online test method and device for corrosion resistance of a pipe on a high-temperature heating surface of a boiler, and the online test method comprises the following steps: introducing steam into the pipe, enabling the pipe to extend into a hearth of the boiler for heating, adjusting the temperature rise of the steam from an inlet of the pipe to the interior of the pipe by adjusting the flow of the steam, and further controlling the pipe wall temperature of the pipe to reach a set value, measuring the pipe wall thickness change of the pipe, and calculating the corrosion rate of the pipe. On the premise that main steam parameters and power generation efficiency of an existing boiler are not affected, a reasonable test heating surface process arrangement and control method is adopted, the pipe wall temperature of a test heating surface pipe is controlled, and data obtained through a test are more objective and accurate.

Description

Technical Field

[0001] The present invention relates to the field of electric power and solid waste treatment environmental protection technology. More specifically, the present invention relates to an online test method and device for corrosion resistance of boiler high-temperature heating surface pipes. Background Art

[0002] In order to further improve the resource utilization capacity of solid waste and increase the power generation per unit of waste, it is necessary to increase the main steam parameters of the waste power plant, but this will increase the corrosion rate of the heating surface; at the same time, because my country's medical waste will face the problem of insufficient processing capacity in certain specific cases, it is a feasible way to harmlessly treat medical waste and mix it with domestic waste for coordinated treatment. When domestic waste is incinerated with medical waste, the high chlorine content in medical waste will also aggravate the corrosion of the boiler heating surface pipes. Therefore, studying the corrosion rate of the heating surface is crucial to further improve the parameters of waste incineration power plants and the proportion of medical waste incineration. In order to study the corrosion rate of different heating surface materials at higher temperatures, it is necessary to find a stable high-temperature corrosion environment. In the prior art, simulations are usually carried out in the laboratory or hanging plate tests are carried out in different flue gas temperature areas on the flue gas side of the actual boiler. Conducting simulation tests in the laboratory cannot completely restore the flue gas composition of boiler incineration, which affects the accuracy of the results; using the boiler flue gas side hanging plate test method, although the flue gas composition can be guaranteed, the tube wall temperature is completely consistent with the flue gas temperature, and the flue gas temperature in the boiler is unstable, fluctuates greatly and cannot be controlled, which will also affect the accuracy of the results. The invention patent application with application publication number CN110608992A discloses a probe device and method for testing the high-temperature corrosion resistance of the metal material of the heating surface of a waste incineration boiler. The probe device has good sealing and can realize the high-temperature corrosion resistance of different metal materials in a waste incineration power plant. However, it controls the temperature of the heating surface by introducing cooling gas into the tubular specimen, which requires the additional installation of a compressed air cabinet, resulting in additional energy consumption, and the temperature control method and its accuracy are unclear, and there is room for improvement. Summary of the invention

[0003] An object of the present invention is to provide an online test method and device for the corrosion resistance of boiler high-temperature heating surface pipes, which uses the original steam in the boiler to perform corrosion resistance tests on the heating surface pipes without affecting the main steam parameters and power generation efficiency of the existing boiler system, thereby saving energy.

[0004] In order to achieve these purposes and other advantages of the present invention, according to one aspect of the present invention, there is provided an online test method for corrosion resistance of boiler high-temperature heating surface pipes, comprising the following steps: introducing steam into the pipes, extending the pipes into the furnace of the boiler for heating, adjusting the steam temperature rise from the inlet of the pipes to the inside of the pipes by adjusting the flow rate of the steam, thereby controlling the pipe wall temperature of the pipes to reach a set value, measuring the change in the pipe wall thickness of the pipes, and calculating the corrosion rate of the pipes; The relationship between the wall temperature of the pipe and the steam temperature rise from the inlet of the pipe to the inside of the pipe is as follows: T j =(T r +Δt)+K×M×(T y -(T r +Δt)) / (K+1 / α1+0.25×ε); Where K = β × ((δ / λ m ) ×(2 / (β+1))+(1 / α2)); Among them, T j is the wall temperature of the middle test point of the pipe, °C; T r is the inlet steam temperature of the pipe, °C; Δt is the steam temperature rise from the inlet of the pipe to the test point in the middle of the pipe, °C; β is the ratio of the outer diameter to the inner diameter of the pipe; δ is the wall thickness of the pipe, m; λ m is the metal heat transfer coefficient of the pipe, W / (m·K); α1 is the heat transfer coefficient of the flue gas in the furnace to the pipe wall of the pipe, W / (m 2 ·K); α2 is the heat transfer coefficient from the tube wall to the steam, W / (m 2 ·K); T y is the flue gas temperature in the furnace, ℃; ε is the pollution coefficient, m 2 K / W; M is the correction factor between the calculated value and the actual measured value.

[0005] Preferably, the calculation formula of Δt is: Δt=(T c -T r )×L1 / L 总 ; Among them, T c is the outlet steam temperature of the pipe, °C; T r is the inlet steam temperature of the pipe, °C; L1 is the length from the inlet of the pipe to the test point in the middle of the pipe, m; L 总 is the length of the tube in the furnace, m.

[0006] Preferably, the pipe is made of a metal material to be tested.

[0007] Preferably, the steam is branch steam extracted from the low / medium temperature superheater header of the boiler. After being heated by the flue gas in the furnace along with the test tube group, the branch steam flows back to the main steam pipeline of the boiler and merges with the main steam of the boiler.

[0008] Preferably, after the branch steam merges with the main steam, the temperature of the main steam increases by less than 1°C.

[0009] The present invention also provides a test device based on the above-mentioned online test method for corrosion resistance of boiler high-temperature heating surface pipes, including a test pipe group, the test pipe group including a steam inlet pipeline and a steam outlet pipeline parallel to each other, a plurality of tubular test pieces are vertically connected in parallel between the steam inlet pipeline and the steam outlet pipeline, the plurality of tubular test pieces are serpentine-shaped pipes made of a plurality of different metal materials to be tested, the steam inlet pipeline and the steam outlet pipeline are respectively provided with a steam inlet and a steam outlet, the steam inlet is connected to the low / medium temperature superheater header of the boiler through a steam inlet pipeline, a branch steam inlet valve, a steam flow regulating valve and a steam flow meter are provided on the steam inlet pipeline, the steam outlet is connected to the main steam pipeline of the boiler through a steam outflow pipeline, a branch steam outlet valve is provided on the steam outflow pipeline, wherein each tubular test piece in the test pipe group is sealed and passes through the furnace wall of the boiler and extends into the high temperature area of ​​the furnace.

[0010] Preferably, the steam inlet and the steam outlet are respectively installed with an inlet thermocouple and an outlet thermocouple, a tube wall temperature sensor is installed at the middle test point of each tubular test piece in the test tube group, and a flue gas temperature sensor is installed in the furnace near the test tube group.

[0011] Preferably, the steam inlet pipeline and the steam outlet pipeline are located outside the boiler, and their axial directions are 90° to the flue gas flow direction in the boiler, and the plane where each tubular test piece is located is parallel to the flue gas flow direction in the boiler.

[0012] The present invention includes at least the following beneficial effects: without affecting the main steam parameters and power generation efficiency of the existing boiler, the present invention places the test heating surface in a higher smoke temperature area on the basis of the existing parameter boiler, adopts a high-temperature steam small flow parallel mode to partially increase the steam temperature parameters in the test heating surface pipe, and controls the pipe wall temperature by adjusting the inlet steam flow of the test heating surface pipe, so that the test data is more objective, and finally the corrosion rate of each pipe is obtained, and suitable corrosion-resistant pipes are found. This will provide a basis for further improving the main steam parameters of waste incineration waste heat boilers, improving the power generation efficiency of waste incineration power plants, and providing a basis for the design of boilers and high-temperature superheater pipes required for the co-burning of solid waste such as medical waste.

[0013] Other advantages, objectives and features of the present invention will be embodied in part through the following description, and in part will be understood by those skilled in the art through study and practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 This is a schematic diagram of the structure of the test device in a technical solution of the present invention: Figure 2 It is a side view of the installation of any tubular test piece in a technical solution of the present invention; Figure 3 This is a top view of the installation of the test tube group described in one technical solution of the present invention. DETAILED DESCRIPTION

[0015] The present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments so that those skilled in the art can implement the invention with reference to the description.

[0016] It should be understood that the terms such as “having”, “including” and “comprising” used herein do not exclude the existence or addition of one or more other elements or combinations thereof.

[0017] It should be noted that the experimental methods described in the following embodiments are conventional methods unless otherwise specified, and the reagents and materials can be obtained from commercial sources unless otherwise specified; in the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "set" should be understood in a broad sense, for example, they can be fixedly connected, set, or detachably connected, set, or connected and set in one piece. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood in specific circumstances. The orientation or position relationship indicated by the terms "lateral", "longitudinal", "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc. is based on the orientation or position relationship shown in the accompanying drawings, which is only for the convenience of describing the present invention and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation of the present invention.

[0018] The present invention provides an online test method for corrosion resistance of boiler high-temperature heating surface pipes, comprising the following steps: introducing steam into the pipes, extending the pipes into the furnace of the boiler for heating, adjusting the steam temperature rise from the inlet of the pipes to the inside of the pipes by adjusting the flow of the steam, thereby controlling the pipe wall temperature of the pipes to reach a set value, measuring the change in the pipe wall thickness of the pipes, and calculating the corrosion rate of the pipes; The relationship between the wall temperature of the pipe and the steam temperature rise from the inlet of the pipe to the inside of the pipe is as follows: T j =(T r +Δt)+K×M×(T y -(T r +Δt)) / (K+1 / α1+0.25×ε); Where K = β × ((δ / λ m ) ×(2 / (β+1))+(1 / α2)); Among them, T j is the wall temperature of the middle test point of the pipe, °C; T r is the inlet steam temperature of the pipe, °C; Δt is the steam temperature rise from the inlet of the pipe to the test point in the middle of the pipe, °C; β is the ratio of the outer diameter to the inner diameter of the pipe; δ is the wall thickness of the pipe, m; λ m is the metal heat transfer coefficient of the pipe, W / (m·K); α1 is the heat transfer coefficient of the flue gas in the furnace to the pipe wall of the pipe, W / (m 2 ·K); α2 is the heat transfer coefficient from the tube wall to the steam, W / (m 2 ·K); T y is the flue gas temperature in the furnace, ℃; ε is the pollution coefficient, m 2 K / W; M is the correction factor between the calculated value and the actual measured value.

[0019] In the above technical solution, the online test method for corrosion resistance of boiler high-temperature heating surface pipes aims to efficiently and accurately evaluate the corrosion resistance of pipes in high-temperature environments by precisely controlling the working temperature of the pipes and monitoring the changes in their wall thickness. The specific steps are as follows: First, the test preparation stage Select representative boiler high-temperature heating surface pipes as test objects to ensure that their materials, specifications and manufacturing processes meet the actual use requirements. Pre-treat the pipes, including cleaning, rust removal, drying and other steps, to eliminate the impact of surface contamination on the test results. Place the pipes in the furnace of the boiler.

[0020] A steam branch is led out from the low / medium temperature superheater header in the original boiler system, passes through the furnace wall of the boiler and enters the pipe. After the steam is heated by the flue gas in the boiler, it passes through the boiler and flows back to the main steam pipe in the original boiler system, ensuring that the steam can stably and continuously enter the interior of the pipe.

[0021] Second, the trial implementation phase Steam flow regulation: By adjusting the opening of the steam flow control valve, the inlet steam temperature and steam temperature rise of the pipe can be accurately adjusted. The steam temperature and temperature rise should be adjusted based on the material, specification and expected wall temperature of the pipe.

[0022] Tube wall temperature control: Use a temperature sensor to monitor the tube wall temperature at a test point in the middle of the tube in real time. The test point is not fixed and can be located anywhere in the middle of the tube. The steam flow rate is fine-tuned through a feedback control system to keep the tube wall temperature within the set value range. The set value of the tube wall temperature should be determined based on the corrosion resistance evaluation standard of the tube and the actual use conditions.

[0023] Pipe wall thickness measurement: Measure the pipe wall thickness before and after the test to record its changes over time. High-precision measuring tools should be used to measure the pipe wall thickness, and ensure the accuracy and reliability of the measurement results.

[0024] Calculation of pipe wall temperature: In order to more accurately control the working temperature of the pipe, the present invention provides a complex mathematical model to calculate the pipe wall temperature. The model takes into account a variety of factors, including the inlet steam temperature of the pipe, the steam temperature rise, the geometric dimensions of the pipe (such as the ratio of the outer diameter to the inner diameter β, the pipe wall thickness δ), the metal heat transfer coefficient λ of the pipe m , heat transfer coefficient of flue gas in the furnace to the pipe wall α1, heat transfer coefficient of pipe wall to steam α2, flue gas temperature in the furnace T y And the pollution coefficient ε, etc. In addition, a correction coefficient M between the calculated value and the actual measured value is introduced to improve the accuracy of the calculation result.

[0025] Wall thickness change measurement and corrosion rate calculation: After the pipe has been running stably for a period of time, use a high-precision measuring tool to measure the change in the pipe wall thickness. By comparing the pipe wall thickness before and after the test, the corrosion rate of the pipe can be calculated to evaluate its corrosion resistance. The calculation formula for the corrosion rate of the pipe is: V=(δ0-δ1) / t; where δ0 is the initial thickness of the pipe, δ1 is the thickness of the pipe after the test, and t is the test time.

[0026] Key Parameters Explanation The wall temperature of the pipe (T j ): It is the temperature that the pipe is set to reach during operation.

[0027] The inlet steam temperature of the pipe (T r ): is the initial temperature of the steam when it enters the pipe.

[0028] Steam temperature rise (Δt): It is the temperature increase of steam from the inlet to the inside of the pipe, which can be adjusted by adjusting the steam flow rate. When the flue gas temperature and the heating area remain unchanged, the greater the steam flow rate in the test tube, the lower the steam temperature rise.

[0029] The ratio of the outer diameter to the inner diameter of the pipe (β): reflects the geometric shape of the pipe and has an important influence on the heat transfer performance of the pipe.

[0030] The wall thickness of the pipe (δ): It is an important structural parameter of the pipe and affects the strength and heat transfer performance of the pipe.

[0031] Metal heat transfer coefficient (λ m ): Indicates the heat conductivity of the pipe material.

[0032] Heat transfer coefficient (α1, α2): respectively represents the heat transfer capacity from flue gas in the furnace to the pipe wall and from the pipe wall to the steam.

[0033] The flue gas temperature in the furnace (T y ): It is the actual temperature of the flue gas in the furnace, which affects the heat transfer and corrosion process of the pipe.

[0034] Contamination coefficient (ε): reflects the impact of the degree of pipe surface contamination on heat transfer performance.

[0035] Correction coefficient (M): used to correct the difference between the calculated value and the actual measured value to improve the accuracy of the calculation result.

[0036] In summary, the online test method for corrosion resistance of boiler high-temperature heating surface pipes provided by the present invention, based on the existing parameter boiler, places the test heating surface in a higher smoke temperature area, adopts a high-temperature steam small flow parallel mode to partially increase the steam temperature parameters in the test heating surface pipe, and controls the pipe wall temperature by adjusting the inlet steam flow of the test heating surface pipe, so that the test data is more objective, and finally the corrosion rate of each pipe is obtained, and suitable corrosion-resistant pipes are found. It provides a basis for further improving the main steam parameters of waste incineration waste heat boilers, improving the power generation efficiency of waste incineration power plants, and providing a selection basis for the design of boilers and high-temperature superheater pipes required for the co-burning of solid waste such as medical waste.

[0037] In another technical solution, the calculation formula of Δt is: Δt=(T c -T r )×L1 / L 总 ; Among them, T c is the outlet steam temperature of the pipe, °C; T r is the inlet steam temperature of the pipe, °C; L1 is the length from the inlet of the pipe to the test point in the middle of the pipe, m; L 总 is the length of the tube in the furnace, m.

[0038] In another technical solution, the pipe is a tubular test piece made of the metal material to be tested. In this technical solution, the pipe is a tubular test piece carefully made of a specific metal material to be tested, which is generally widely used in the high-temperature heating surface of the boiler, such as stainless steel, alloy steel or other special alloys that are resistant to high temperature and corrosion. The size, shape and specifications of these tubular test pieces are customized according to the specific requirements of the boiler design to ensure that they can accurately simulate the heating and corrosion conditions in the actual working environment.

[0039] In another technical solution, the steam is the branch steam extracted from the low / medium temperature superheater header of the boiler. After the test tube group is heated by the flue gas in the furnace, the branch steam flows back to the main steam pipeline of the boiler and merges with the main steam of the boiler. In this technical solution, the steam is extracted from the low / medium temperature superheater header of the boiler, which utilizes the existing steam system of the boiler, significantly improving the efficiency and practicality of the test. As the test tube group passes through the furnace, these branch steams are fully heated by the hot flue gas, which is consistent with the actual working conditions of the high temperature heating surface of the boiler. After heating, these steams are not wasted, but flow back to the main steam pipeline of the boiler, seamlessly merge with the main steam of the boiler, and continue to participate in the thermal cycle of the boiler. By extracting branch steam for testing, there is no need to generate additional steam, thereby saving energy and cost. At the same time, the heated steam flows back to the main steam pipeline, realizing the maximum utilization of steam resources. This design is cleverly integrated into the existing steam system of the boiler, without the need to make major changes to the main structure of the boiler, reducing the impact of the test on the operation of the boiler, and also facilitating the conduct of the test and the collection of data. By adjusting the flow and temperature of the branch steam, different operating conditions can be flexibly simulated, providing more possibilities for the corrosion resistance evaluation of the pipe. The steam generated during the test is avoided from being directly discharged into the atmosphere, reducing environmental pollution, and also meeting the requirements of modern industry for energy conservation and emission reduction. In short, the design of testing the branch steam extracted from the low / medium temperature superheater header of the boiler and returning it to the main steam pipeline after heating not only improves the efficiency and accuracy of the test, but also achieves efficient utilization of resources and friendly protection of the environment, with significant beneficial effects.

[0040] In another technical solution, after the branch steam merges with the main steam, the temperature of the main steam rises by less than 1°C. In this technical solution, during the steam mixing process, since the temperature of the test steam is close to the temperature of the main steam (after heating), the temperature rise of the mixed main steam is strictly controlled within a range of less than 1°C. This small temperature change is almost negligible for the stable operation of the boiler system, thereby ensuring that the test process will not have any adverse effects on the boiler's thermal cycle, steam parameters, and subsequent power generation or process.

[0041] like Figure 1 As shown, the present invention also provides a test device based on the above-mentioned boiler high-temperature heating surface pipe corrosion resistance online test method, including a test pipe group 4, the test pipe group 4 includes a steam inlet pipeline 41 and a steam outlet pipeline 42 parallel to each other, a plurality of tubular test pieces 43 are vertically connected in parallel between the steam inlet pipeline 41 and the steam outlet pipeline 42, and the plurality of tubular test pieces 43 are serpentine-shaped pipes made of a plurality of different metal materials to be tested, and the steam inlet pipeline 41 and the steam outlet pipeline 42 are respectively provided with a steam inlet and an outlet. The steam inlet is connected to the low / medium temperature superheater header 1 of the boiler through a steam inlet pipeline, and a branch steam inlet valve 5, a steam flow regulating valve 7 and a steam flow meter 8 are arranged on the steam inlet pipeline. The steam outlet is connected to the main steam pipeline 3 of the boiler through a steam outflow pipeline, and a branch steam outlet valve 6 is arranged on the steam outflow pipeline, wherein each tubular test piece in the test tube group is sealed and passes through the furnace wall of the boiler and extends into the high temperature area of ​​the furnace. In the present technical scheme, the test tube group 4 is composed of a steam inlet pipeline 41 and a steam outlet pipeline 42 which are parallel to each other, and a plurality of tubular test pieces 43 are vertically connected in parallel between the two. These tubular test pieces 43 are not made of a single material, but are carefully made of a variety of different metal materials to be tested, aiming to comprehensively evaluate the performance of various materials under high temperature, high pressure and corrosive environment. The steam inlet pipeline 41 and the steam outlet pipeline 42 are respectively equipped with a steam inlet and a steam outlet, which provide a convenient channel for the inflow and outflow of steam. The steam inlet is closely connected to the low / medium temperature superheater header 1 of the boiler through the steam inflow pipeline. This design ensures that the source of the test steam is stable and reliable. At the same time, the steam inlet pipeline is also equipped with a branch steam inlet valve 5, a steam flow regulating valve 7 and a steam flow meter 8. The branch steam inlet valve 5 is used to control the inflow of steam, and the steam flow regulating valve 7 can accurately adjust the flow of steam to meet the needs under different test conditions, while the steam flow meter 8 monitors the flow of steam in real time to ensure the accuracy of the test data. The steam outlet is connected to the main steam pipeline of the boiler through the steam outflow pipeline, realizing the recycling of the test steam. The branch steam outlet valve 6 set on the steam outflow pipeline can safely and effectively discharge the steam out of the system after the test. It is worth mentioning that both the steam inlet pipe and the steam outlet pipe are designed to be sealed and pass through the boiler furnace wall, which not only ensures the smoothness of the steam, but also avoids the impact of the high temperature and high pressure environment in the furnace on the pipes, and ensures that the test pipe group 4 can be accurately located in the high temperature area of ​​the boiler furnace. The choice of this position makes the test conditions closer to the actual working environment of the high temperature heating surface of the boiler.

[0042] In another technical solution, the steam inlet and the steam outlet are respectively installed with an inlet thermocouple 9 and an outlet thermocouple 10, a tube wall temperature sensor 11 is installed in the middle of each tubular test piece in the test tube group 4, and a flue gas temperature sensor 12 is installed in the furnace near the test tube group 4. In this technical solution, the inlet thermocouple 9 and the outlet thermocouple 10 are used to measure the steam temperature of the steam inlet and the steam outlet, and the steam temperature of the steam inlet is the inlet steam temperature of the pipe (T r ), the steam temperature at the steam outlet is the outlet steam temperature of the pipe (T c The tube wall temperature sensor is used to measure the tube wall temperature at a fixed test point in the middle of the tubular specimen (T j ), the flue gas temperature sensor is used to measure the flue gas temperature at the location of the test tube group 4, which is the flue gas temperature in the furnace (T y ).

[0043] In another technical solution, the steam inlet pipe 41 and the steam outlet pipe 42 are located outside the boiler, and the axial direction of the two is 90° to the flue gas flow direction in the boiler, and the plane where each tubular test piece 43 is located is parallel to the flue gas flow direction in the boiler. In this technical solution, when the flue gas flows in the boiler, it is often affected by various factors and unevenly distributed. By arranging the tubular test piece 43 in parallel with the flue gas flow direction, the flue gas can be caused to form a more uniform flow around the pipe, reducing the phenomenon of local overheating or uneven cooling, and improving the accuracy and reliability of the test results. On the high-temperature heating surface of the boiler, corrosion is often uneven, which is related to many factors such as flue gas composition, temperature distribution and pipe material. By arranging the tubular test piece 43 in parallel with the flue gas flow direction, the structural settings of each parallel pipe are completely consistent, so that the steam flow rate in the pipe is consistent, a more realistic corrosion environment can be simulated, so that the pipe can be subjected to more uniform corrosion during the test, so as to more accurately evaluate its corrosion resistance. Example

[0044] Take the installation of test equipment on a conventional waste incineration boiler as an example. The parameters of conventional waste incineration boilers are main steam pressure of 6.4MPa and main steam temperature of 450℃. Superheater steam enters high-temperature superheater 2 from low / medium temperature superheater header 1 after desuperheating and is heated to 450℃, and is sent to the steam turbine through main steam pipeline 3. Test steam is drawn from low / medium temperature superheater header 1 (steam pressure 6.57MPa, steam temperature 430℃, steam flow 1.0t / h). After the steam enters test tube group 4 and is heated to 500℃, it is finally introduced into main steam pipeline 3 to mix with the original boiler main steam. The test steam dosage is 1% of the boiler main steam volume. After mixing, the main steam temperature is increased by less than 1℃, which does not affect the boiler system. Test tube group 4 is installed in the three-channel inlet area of ​​the boiler furnace, where the smoke temperature is about 720℃, and the tube wall temperature of the test tube group is 520℃. After running for one cycle, the wall thickness of the test tube group was tested, data was collected, and the corrosion rates of various pipes were compared to find corrosion-resistant pipes for high-temperature superheaters in high-parameter waste incineration waste heat boilers that burn medical waste, thus breaking through the existing waste incineration technology.

[0045] The tube wall temperature detection method of the test tube group: the tube wall temperature measuring point of the test tube group directly detects the tube wall temperature through the tube wall temperature sensor, and after the tube wall temperature calculated value is corrected with the data collected by the steam flow meter 8, the test tube group inlet thermocouple 9, the test tube group 4 own structure data, the test tube group outlet thermocouple 10 and the flue gas temperature measuring point 12, the steam flow is adjusted by controlling the steam flow regulating valve 7, and finally the tube wall temperature reaches the required value for the test.

[0046] The pipe wall temperature control method of the test pipe group: the steam regulating valve 7 controls the test steam flow rate by adjusting the valve opening and changing the overall resistance of the pipeline. When the flue gas temperature and the heating area remain unchanged, the greater the steam flow rate in the test pipe, the lower the outlet steam temperature, and the lower the test pipe wall temperature, so as to adjust the test pipe wall temperature to meet the test requirements.

[0047] The test device can be completely independent from the original boiler system, and the pipeline is cut off through the branch steam inlet valve 5 and the branch steam outlet valve 6. In the event of equipment problems or online testing, the operation of the original boiler system will not be affected.

[0048] The test tube group 4 is composed of various high-grade tubes, which are placed in a boiler for testing. The corrosion rates of various tubes can be obtained simultaneously in one test cycle, thus meeting the test requirements more efficiently.

[0049] Although the embodiments of the present invention have been disclosed as above, they are not limited to the applications listed in the specification and the implementation modes, and they can be fully applied to various fields suitable for the present invention. For those familiar with the art, additional modifications can be easily implemented. Therefore, without departing from the general concept defined by the claims and the scope of equivalents, the present invention is not limited to the specific details and the illustrations shown and described herein.

Claims

1. The on-line test method for corrosion resistance of boiler high temperature heating surface pipes is characterized by: The following steps are involved: Steam is introduced into the pipe, and the pipe is extended into the furnace of the boiler for heating. The steam temperature rise from the inlet of the pipe to the inside of the pipe is adjusted by adjusting the flow rate of the steam, thereby controlling the pipe wall temperature to reach a set value, measuring the change in the pipe wall thickness, and calculating the corrosion rate of the pipe; The relationship between the wall temperature of the pipe and the steam temperature rise from the inlet of the pipe to the inside of the pipe is as follows: T j =(T r +Δt)+K×M×(T y -(T r +Δt)) / (K+1 / α1+0.25×ε); Where, K=β×((δ / λ m ) ×(2 / (β+1))+(1 / α2)); Among them, T j is the wall temperature of the test point in the middle of the pipe, °C; T r is the inlet steam temperature of the pipe, °C; Δt is the steam temperature rise from the inlet of the pipe to the test point in the middle of the pipe, °C; β is the ratio of the outer diameter to the inner diameter of the pipe; δ is the wall thickness of the pipe, m; λ m is the metal heat transfer coefficient of the pipe, W / (m·K); α1 is the heat transfer coefficient of the flue gas in the furnace to the pipe wall of the pipe, W / (m 2 ·K); α2 is the heat transfer coefficient from the tube wall to the steam, W / (m 2 ·K); T y is the flue gas temperature in the furnace, ℃; ε is the pollution coefficient, m 2 K / W; M is the correction factor between the calculated value and the actual measured value.

2. The on-line test method for corrosion resistance of boiler high temperature heating surface pipes according to claim 1, characterized in that: The calculation formula of Δt is: Δt=(T c -T r )×L1 / L 总 ; Among them, T c is the outlet steam temperature of the pipe, °C; T r is the inlet steam temperature of the pipe, °C; L1 is the length from the inlet of the pipe to the test point in the middle of the pipe, m; L 总 is the length of the tube in the furnace, m.

3. The on-line test method for corrosion resistance of boiler high temperature heating surface pipes according to claim 1, characterized in that: The pipe is made of a metal material to be tested.

4. The on-line test method for corrosion resistance of boiler high temperature heating surface pipes according to claim 1, characterized in that: The steam is branch steam extracted from the low / medium temperature superheater header of the boiler. After being heated by the flue gas in the furnace along with the test tube group, the branch steam flows back to the main steam pipeline of the boiler and merges with the main steam of the boiler.

5. The on-line test method for corrosion resistance of boiler high temperature heating surface pipes according to claim 4, characterized in that: After the branch steam merges with the main steam, the temperature of the main steam increases by less than 1°C.

6. A test device based on the on-line test method for corrosion resistance of boiler high temperature heating surface pipes according to any one of claims 1 to 5, characterized in that: It comprises a test tube group, the test tube group comprises a steam inlet pipeline and a steam outlet pipeline which are parallel to each other, a plurality of tubular test pieces are vertically connected in parallel between the steam inlet pipeline and the steam outlet pipeline, the plurality of tubular test pieces are serpentine-shaped pipes made of a plurality of different metal materials to be tested, the steam inlet pipeline and the steam outlet pipeline are respectively provided with a steam inlet and a steam outlet, the steam inlet is connected with a low / medium temperature superheater header of the boiler through a steam inlet pipeline, a branch steam inlet valve, a steam flow regulating valve and a steam flow meter are provided on the steam inlet pipeline, the steam outlet is connected with a main steam pipeline of the boiler through a steam outflow pipeline, a branch steam outlet valve is provided on the steam outflow pipeline, wherein each tubular test piece in the test tube group is sealed and passes through the furnace wall of the boiler and extends into the high temperature area of ​​the furnace.

7. The test device according to claim 6, characterized in that The steam inlet and the steam outlet are respectively installed with an inlet thermocouple and an outlet thermocouple, a tube wall temperature sensor is installed at the middle test point of each tubular test piece in the test tube group, and a flue gas temperature sensor is installed in the furnace near the test tube group.

8. The test device according to claim 6, characterized in that The steam inlet pipeline and the steam outlet pipeline are located outside the boiler, and the axial directions of the two are 90° to the flue gas flow direction in the boiler, and the plane where each tubular test piece is located is parallel to the flue gas flow direction in the boiler.

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