Sample tube checking device and method for ferrite furnace tube oxide skin accumulation detection

Abstract

The invention provides a sample tube verification device and method for ferrite furnace tube oxide skin accumulation detection, belongs to the technical field of nondestructive detection equipment, and can at least partially solve the problem that the application of an existing magnetic detection method on a ferrite furnace tube lacks reliable detection reference. In order to solve the problems of high radiation risk, low detection efficiency, high requirement on detection space and easy missing detection in the prior art in the prior art, the invention provides a sample tube, and the sample tube is provided with a filling unit, an isolation assembly and a closing assembly. The simulation medium can form a plurality of mutually distinguished accumulation states in the sample tube, so that the simulation of different accumulation working conditions of the oxide skin in the ferrite furnace tube is realized under the condition of not repeatedly preparing a plurality of sample tubes, and the preparation number and the use cost of the verification sample tube are reduced.

Description

Technical Field

[0001] This invention belongs to the field of non-destructive testing equipment technology, specifically relating to a calibration sample tube device and method for detecting oxide scale buildup in ferrite furnace tubes. Background Technology

[0002] Against the backdrop of the "dual carbon" target, the installed capacity of new energy sources is growing rapidly, placing higher demands on the peak-shaving capabilities of thermal power units in the power system. Currently, the vast majority of in-service thermal power units need to operate under conditions of deep peak shaving and frequent start-ups and shutdowns for extended periods. Rapid fluctuations in unit load subject the high-temperature heating surfaces of the furnace tubes to repeated thermal shocks, resulting in uneven local temperature distribution and significant thermal stress. Due to the significant difference in the coefficient of thermal expansion between the furnace tube matrix material and the oxide scale formed on its inner wall, the oxide scale is prone to micro-cracks and gradual peeling under repeated thermal stress.

[0003] Peeled oxide scale easily accumulates in low-flow-rate areas such as the lower bends of furnace tubes under the influence of flowing media. The poor thermal conductivity of oxide scale leads to localized heat transfer deterioration, causing a rapid increase in the temperature of the covered tube wall and ultimately resulting in overheating and tube rupture accidents. Related statistics show that in a survey of 248 thermal power units conducted by Edison in the United States, approximately 80% of the in-service units had equipment damage caused by oxide scale peeling. Domestically, numerous units have also experienced tube rupture accidents caused by the accumulation of oxide scale on high-temperature heating surface furnace tubes. The economic losses from a single accident requiring shutdown and repair can reach tens of millions of yuan, seriously threatening the safe and stable operation of the unit and potentially causing casualties. Early-stage 300MW and 600MW subcritical units primarily used ferritic steel for their high-temperature heating surface furnace tubes. As service time increased, the oxide scale on the inner wall of these tubes thickened continuously. Under long-term deep peak-shaving conditions, the thicker oxide scale is more prone to large-area peeling and deposition at the lower bends, reducing the flow area and significantly decreasing cooling capacity, thus potentially triggering tube rupture accidents within a short period. In recent years, several ferritic furnace tube units in China have experienced this type of failure.

[0004] Currently, the main methods for detecting oxide scale buildup inside furnace tubes include magnetic detection and radiographic testing. Magnetic detection is well-established for austenitic stainless steel furnace tubes, but due to the ferromagnetic nature of ferritic steels, its application to ferritic furnace tubes lacks reliable references. While radiographic testing can be used for ferritic furnace tubes, it suffers from drawbacks such as high radiation risk, low detection efficiency, high requirements for testing space, and a tendency to miss detections. Therefore, we propose a calibration sample tube device and method for detecting oxide scale buildup in ferritic furnace tubes. Summary of the Invention

[0005] The present invention aims to solve at least one of the technical problems existing in the prior art, and provides a calibration sample tube device and method for detecting oxide scale buildup in ferrite furnace tubes.

[0006] In one aspect, this invention provides a calibration sample tube device for detecting oxide scale buildup in ferritic furnace tubes, comprising a sample tube having: The filling unit includes a simulated medium that is filled inside the sample tube during operation. An isolation assembly includes a plurality of isolation elements disposed on the sample tube for limiting and separating the simulated medium inside the sample tube during operation; and The sealing assembly includes sealing members respectively disposed at both ends of the sample tube; The isolation element is disposed at multiple preset positions on the sample tube, so that the simulated medium forms different accumulation states on the same sample tube.

[0007] Furthermore, the sample tube is a ferritic steel tube.

[0008] Specifically, the sample tube includes an elbow section for simulating deposition or blockage of the simulated medium in the elbow region of the ferrite furnace tube.

[0009] Specifically, the insulating element is a high-temperature resistant insulating sheet, and the simulated medium is an oxide scale medium.

[0010] Preferably, the insulating element is a mica sheet.

[0011] Specifically, the sample tube has multiple mounting positions at the preset position, and the mounting positions are spaced apart along the extension direction of the sample tube.

[0012] Furthermore, the mounting position is an insertion port located on the outer wall of the sample tube, for inserting the isolation element into the inner cavity of the sample tube through the insertion port and forming a barrier against the simulated medium.

[0013] Furthermore, the sample tube is provided with a grading mark at the preset position and on the closure to indicate the stacking level of the simulated medium.

[0014] Another aspect of the present invention provides a calibration method for detecting oxide scale buildup in ferrite furnace tubes. The method is implemented using the aforementioned calibration sample tube device for detecting oxide scale buildup in ferrite furnace tubes, and includes the following steps: S1: Obtain the sample tube that matches the specifications of the ferrite furnace tube to be tested, and fill the sample tube with the simulated medium; S2: The isolation element limits and separates the simulated medium to form at least two stacking simulation zones, and different stacking simulation zones correspond to different stacking states; S3: Use the magnetic detection device to be verified to test the sample tube and obtain the detection response of each of the stacking simulation regions; S4: Adjust the parameters of the magnetic detection device according to the detection response, and evaluate its detection capability.

[0015] Specifically, in step S2, the different stacking states include multiple stacking levels divided according to a preset grading threshold. The grading threshold includes the stacking degree expressed as a percentage. By changing the setting position of the separator on the sample tube, the same sample tube can form different stacking states.

[0016] The beneficial effects of this invention are as follows: By setting filling units, isolation components, and sealing components within the same sample tube, the simulated medium can form multiple distinct stacking states inside the sample tube. This allows for the simulation of different oxide scale stacking conditions inside ferrite furnace tubes without repeatedly preparing multiple sample tubes, reducing the number of calibration sample tubes required and the cost of use. Furthermore, by setting multiple preset positions on the sample tube and arranging isolation components at these positions, the internal space of the sample tube is divided into multiple stacking simulation zones. These different stacking simulation zones correspond to different stacking states, solving the problem of lacking reliable reference samples in the magnetic detection of oxide scale stacking in ferrite furnace tubes. This provides a clear and repeatable physical reference for the calibration and performance evaluation of the testing equipment. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of a calibration sample tube device for detecting oxide scale buildup in ferrite furnace tubes according to a specific embodiment of the present invention. Figure 2 This is a flowchart illustrating the steps of a verification method for detecting oxide scale buildup in ferrite furnace tubes, according to a specific embodiment of the present invention.

[0018] The components include: 1. Sample tube; 2. Simulated medium; 3. Isolation component; 4. Sealing component. Detailed Implementation

[0019] To enable those skilled in the art to better understand the technical solution of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0020] like Figure 1 As shown in the figure, a calibration sample tube device for detecting oxide scale buildup in ferrite furnace tubes provided in a specific embodiment of the present invention includes a sample tube 1, which is provided with: The filling unit includes a simulated medium 2 that is filled inside the sample tube during operation; the isolation assembly includes multiple isolation members 3 disposed on the sample tube 1 for limiting and separating the simulated medium 2 inside the sample tube during operation; and the sealing assembly includes sealing members 4 disposed at both ends of the sample tube 1; wherein the isolation members 3 are disposed at multiple preset positions on the sample tube 2, so that the simulated medium 2 forms different accumulation states on the same sample tube 1.

[0021] Specifically, sample tube 1 is used to simulate the oxide scale accumulation state of ferrite furnace tubes in power plants under long-term operation and peak-shaving conditions, in order to calibrate and verify the performance of the oxide scale accumulation detection equipment. The purpose of setting up the filling unit is to introduce a simulated medium inside the sample tube to simulate the oxide scale accumulation state of the inner wall of the ferrite furnace tube, so that sample tube 1 is close to the actual operating conditions of oxide scale accumulation in furnace tubes in terms of physical and magnetic properties. By controlling the filling amount and distribution position of the simulated medium, different degrees and positions of accumulation can be formed in sample tube 1, thereby providing a stable and repeatable detection object for the detection equipment.

[0022] Furthermore, the purpose of setting up the isolation components is to limit and separate the simulated medium 2 inside the sample tube 1. By setting isolation components at different preset positions in the sample tube 1, the internal space of the sample tube 1 can be divided into multiple independent stacking simulation zones, so that the simulated medium 2 in each stacking simulation zone corresponds to different stacking states. This structure allows multiple oxide scale stacking conditions to be simulated within the same sample tube 1, avoiding the need to repeatedly prepare multiple sample tubes 1 for different stacking states, thereby improving calibration efficiency and reducing usage costs.

[0023] Furthermore, the purpose of setting up the sealing component is to seal both ends of the sample tube 1 to prevent leakage or positional changes of the simulated medium 2 during filling, transportation, and testing, thus ensuring the stability and consistency of the internal stacking state of the sample tube 1. At the same time, the sealing component facilitates the installation, replacement, and adjustment of the simulated medium 2 and the isolation component 3, providing a structural basis for the reuse of the sample tube 1 and the switching between multiple operating conditions.

[0024] Based on the above basic implementation method, the sample tube 1 is a ferritic steel tube; the sample tube 1 includes an elbow section for simulating the deposition or blockage of the medium in the elbow area of ​​the ferritic furnace tube.

[0025] Specifically, sample tube 1 is a ferritic steel pipe, the diameter, wall thickness, and structural form of which can be selected according to the actual specifications of the ferritic furnace tube being tested to ensure the reliability and representativeness of the verification results. Sample tube 1 may include straight pipe sections and elbow sections, wherein the elbow sections are used to simulate the actual working conditions in which oxide scale is prone to deposition and blockage in the elbow area of ​​the furnace tube.

[0026] In one specific embodiment, the insulating element 3 is a high-temperature resistant insulating sheet, the simulated medium 2 is an oxide scale medium, and the insulating element 3 is a mica sheet.

[0027] In this embodiment, the mica sheet has good high temperature resistance and insulation properties. When used inside the sample tube, it will not adversely affect the magnetic detection equipment, and at the same time, it can effectively isolate the simulated medium.

[0028] Furthermore, mica sheets possess excellent high-temperature resistance, enabling them to meet the simulation requirements of the high-temperature operating environment of ferritic furnace tubes, and are not prone to thermal deformation or performance degradation. Mica sheets also exhibit excellent electrical insulation properties and low magnetic response characteristics, meaning that when used inside sample tube 1, they will not significantly interfere with the detection signal of the magnetic detection equipment, thus improving the accuracy and reliability of the detection results. In addition, the stable material and uniform thickness of mica sheets facilitate their fabrication into sheet-like structures and insertion into the sample tube, effectively isolating the simulated medium 2. The installation and disassembly process is simple, making them suitable for repeated use under field conditions.

[0029] In another specific embodiment, the sample tube 1 has multiple mounting positions at preset positions, and the mounting positions are spaced apart along the extension direction of the sample tube 1; the mounting position is an insertion port provided on the outer wall of the sample tube 1, so as to allow the isolation member 3 to be inserted into the inner cavity of the sample tube 1 through the insertion port and to form a barrier to the simulated medium 2.

[0030] Specifically, the purpose of setting the installation position at the preset location of the sample tube 1 is to provide a clear and standardized structural position for the arrangement of the spacer 3, so that the spacer 3 can be stably set in the designated position inside the sample tube 1. By setting multiple installation positions at intervals in the extension direction of the sample tube 1, multiple stacking simulation areas of different lengths or different volume ratios can be formed inside the sample tube 1, thereby forming different stacking states.

[0031] In one specific embodiment, the sample tube 1 is provided with a grading mark at a preset position and on the sealing member 4 to indicate the stacking level corresponding to the simulated medium 2.

[0032] In this embodiment, the advantage of setting an installation position is that it improves the repeatability and consistency of the installation position of the isolator 3, enabling different users to obtain the same stacking state when assembling the sample tube 1 at different times, thus reducing the impact of human error on the verification results. At the same time, the existence of the installation position provides a clear reference for adjusting the position of the isolator 3, facilitating rapid switching between different stacking states and improving the efficiency and reliability of the verification operation.

[0033] Specifically, by utilizing multiple simulated accumulation zones formed within sample tube 1, the detection capability of the testing equipment can be systematically evaluated. During the testing process, the magnetic detection equipment scans each simulated accumulation zone along the axial direction of sample tube 1, acquiring the corresponding detection response signal. By comparing and analyzing the response results output by the detection equipment with the accumulation levels marked on sample tube 1, the ability of the detection equipment to identify different degrees of accumulation can be evaluated.

[0034] In another specific embodiment, such as Figure 2 As shown, the present invention provides a calibration method for detecting oxide scale buildup in ferrite furnace tubes. This method is implemented using the aforementioned calibration sample tube device for detecting oxide scale buildup in ferrite furnace tubes, and includes the following steps: S1: Obtain the sample tube 1 that is compatible with the specifications of the ferrite furnace tube to be tested, and fill the sample tube 1 with the simulated medium 2; S2: The simulation medium 2 is limited and separated by the isolation element 3 to form at least two stacking simulation areas, and different stacking simulation areas correspond to different stacking states; S3: Use the magnetic detection device to be calibrated to test sample tube 1 and obtain the detection response of each stacking simulation zone; S4: Adjust the parameters of the magnetic detection equipment based on the detection response and evaluate its detection capability.

[0035] Furthermore, in step S2, different stacking states include multiple stacking levels divided according to a preset grading threshold. The grading threshold includes the stacking degree expressed as a percentage. By changing the setting position of the separator on the sample tube 1, different stacking states can be formed for the same sample tube 1.

[0036] Furthermore, the on-site implementation process of this device is as follows: The testing personnel first select a section of the same specification and material with an elbow as sample tube 1, based on the specifications and material of the ferrite furnace tube in the power plant to be tested. According to the required testing accuracy, the upward-facing sample tube 1 is segmented. Assuming the testing equipment's accuracy requirement is that it can effectively detect when the oxide scale buildup inside the ferrite furnace tube is at least n%, and when it reaches a maximum of 100%, the segmentation is x segments, where x = 100 / n. The first segment has an oxide scale buildup of n%, the second segment is 2n%, the yth segment is yn%, and the last segment is... The oxide scale buildup is 100%; the right-hand portion of sample tube 1 is filled with separator 3 to achieve a 100% oxide scale buildup; the sealing member 4 on the right-hand portion of sample tube 1 is divided into sections according to a predetermined segmentation plan, and mica sheets are inserted to divide the oxide scale buildup on the right-hand portion of sample tube 1 into sections with buildup percentages of n%, 2n%, yn%, and 100% respectively; a hole is made at a lower position on the upper part of sample tube 1, and a mica sheet is inserted; the original oxide scale in the right-hand portion of sample tube 1 is poured out, and an oxide scale buildup percentage of n% is poured in; the upper part of sample tube 1 is then opened. The sealing component 4 is used to pour the filled oxide scale into the mica sheet at the bottom of the upward part of the sample tube 1. A line is drawn on the outer wall of the oxide scale interface, and then a hole is made at the drawn line to insert the mica sheet. This determines the amount of oxide scale with a stacking degree of n% in the upward part of the sample tube 1. The previous step is repeated to determine the amount of oxide scale with a stacking degree of 2n%, yn%, and 100% in the upward part of the sample tube 1, and then lines are drawn, holes are made, and mica sheets are inserted in sequence. At the boundary of each segment of the upward part of the sample tube 1, n%, 2n%, yn%, and 100% are marked from bottom to top, and each segment is separated by the simulated medium 2, thus completing the sample tube. The oxide scale of the ferrite furnace tube of the power plant is then tested on site. The parameters of the oxide scale detection equipment are adjusted; the mica sheet of the upper part of the sample tube 1 is pulled out sequentially from bottom to top, and the position of the simulated medium 2 on the right-hand sealing part 4 of the sample tube 1 is adjusted accordingly. This ensures that the oxide scale accumulation degree in the right-hand part of the sample tube 1 is accurately simulated as n%, 2n%, yn%, and 100%. The oxide scale accumulation detection equipment for power plant ferrite furnace tubes is used to detect the oxide scale accumulation in different sections of the sample tube. Based on the detection results, the equipment parameters are further adjusted. This effectively verifies the detection accuracy and precision of the oxide scale accumulation detection equipment for power plant ferrite furnace tubes, reduces the risk of missed detections and misjudgments, and improves detection efficiency.

[0037] To aid in a better understanding of the present invention, a more comprehensive and specific embodiment is described. In this embodiment, the present invention provides a calibration sample tube device for detecting oxide scale buildup in ferrite furnace tubes, comprising a sample tube 1, wherein the sample tube 1 is provided with: The filling unit includes a simulated medium 2 that is filled inside the sample tube 1 during operation; an isolation assembly including multiple isolation members 3 disposed on the sample tube 1 for limiting and separating the simulated medium 2 inside the sample tube 1 during operation; and a sealing assembly including sealing members 4 disposed at both ends of the sample tube 1; wherein the isolation members 3 are disposed at multiple preset positions on the sample tube 1, so that the simulated medium 2 forms different accumulation states on the same sample tube 1.

[0038] In this embodiment, the sample tube 1 is a ferritic steel tube; the sample tube 1 includes an elbow section for simulating the deposition or blockage of the medium in the elbow area of ​​the ferritic furnace tube; the isolation element 3 is a high-temperature resistant insulating sheet, and the simulated medium 2 is an oxide scale medium; the isolation element 3 is a mica sheet; the sample tube 1 has multiple installation positions at preset locations, and the installation positions are spaced apart along the extension direction of the sample tube 1; the installation position is an insertion port on the outer wall of the sample tube 1, so that the isolation element 3 can be inserted into the inner cavity of the sample tube 1 through the insertion port and form a barrier to the simulated medium 2; the preset positions of the sample tube 1 and the sealing element 4 are provided with grade markings to indicate the corresponding deposition level of the simulated medium 2.

[0039] Specifically, another aspect of the present invention provides a calibration method for detecting oxide scale buildup in ferrite furnace tubes. This method is implemented using the aforementioned calibration sample tube device for detecting oxide scale buildup in ferrite furnace tubes, and includes the following steps: S1: Obtain a sample tube 1 that matches the specifications of the ferrite furnace tube being tested, and fill the sample tube 1 with a simulated medium 2. S2: The simulation medium 2 is limited and separated by the isolation element 3 to form at least two stacking simulation areas, and different stacking simulation areas correspond to different stacking states; S3: Use the magnetic detection device to be calibrated to test sample tube 1 and obtain the detection response of each stacking simulation zone; S4: Adjust the parameters of the magnetic detection equipment according to the detection response and evaluate its detection capability; wherein, in step S2, different stacking states include multi-level stacking degree divided according to preset grading thresholds, the grading thresholds include stacking degree expressed as a percentage, and by changing the setting position of the isolation member on the sample tube, the same sample tube can form different stacking states.

[0040] In summary, the embodiments disclosed herein have at least the following technical effects: The present invention sets up a filling unit, an isolation component and a sealing component in the same sample tube 1, so that the simulation medium 2 can form multiple mutually distinct stacking states inside the sample tube 1. Thus, without repeatedly preparing multiple sample tubes 1, the simulation of different stacking conditions of oxide scale in ferrite furnace tubes can be realized, reducing the number of calibration sample tubes 1 to be prepared and the cost of use. This invention divides the internal space of sample tube 1 into multiple stacking simulation zones by setting multiple preset positions on sample tube 1 and arranging isolation components 3 at the preset positions. Different stacking simulation zones correspond to different stacking states, which solves the problem of lacking reliable reference samples in the magnetic detection of oxide scale accumulation in ferrite furnace tubes. It provides a clear and repeatable physical reference for the calibration and performance evaluation of the detection equipment. The calibration sample tube of this invention can simulate the deposition or blockage of oxide scale in different locations such as the straight and elbow sections of ferritic furnace tubes, so that the testing equipment can cover the key parts that are prone to oxide scale accumulation and failure in actual operation during the calibration process, thereby improving the correlation and representativeness of the test results with the actual operating conditions. This invention uses high-temperature resistant insulating isolation components to separate and limit the simulated medium 2, which reduces the interference of the isolation structure on the magnetic detection signal while ensuring structural stability. This is beneficial to improving the accuracy of the detection equipment in identifying different stacking states and the detection stability. The present invention sets installation positions and grade markings on the sample tube 1, so that the installation position of the isolation component 3 and the corresponding relationship of each stacking state are clearly marked, which improves the consistency and repeatability of the sample tube 1 during assembly and use, and reduces the impact of human operation differences on the verification results. The calibration sample tube provided by this invention has a simple structure, is easy to assemble and disassemble, is suitable for use under power plant field conditions, can be carried and operated by a single person, and meets the actual needs of on-site calibration of power plant ferrite furnace tube oxide scale accumulation detection equipment. This invention combines a calibration method for calibration sample tubes with comparative analysis of detection responses under different stacking conditions to achieve a comprehensive assessment of the sensitivity, resolution, and risk of missed detection of the detection equipment. This helps to optimize and adjust the parameters of the detection equipment and improve the reliability and safety of oxide scale accumulation detection in ferrite furnace tubes.

[0041] It is understood that the above embodiments are merely exemplary implementations used to illustrate the principles of the present invention, and the present invention is not limited thereto. For those skilled in the art, various modifications and improvements can be made without departing from the spirit and essence of the present invention, and these modifications and improvements are also considered to be within the scope of protection of the present invention.

Claims

1. A calibration sample tube device for detecting oxide scale buildup in ferrite furnace tubes, characterized in that, Includes a sample tube, which is equipped with: The filling unit includes a simulated medium that is filled inside the sample tube during operation. An isolation assembly includes a plurality of isolation elements disposed on the sample tube for limiting and separating the simulated medium inside the sample tube during operation; and The sealing assembly includes sealing members respectively disposed at both ends of the sample tube; The isolation element is disposed at multiple preset positions on the sample tube, so that the simulated medium forms different accumulation states on the same sample tube.

2. The calibration sample tube device for detecting oxide scale buildup in ferrite furnace tubes according to claim 1, characterized in that, The sample tube is a ferritic steel tube.

3. The calibration sample tube device for detecting oxide scale buildup in ferrite furnace tubes according to claim 1, characterized in that, The sample tube includes an elbow section for simulating deposition or blockage of the simulated medium in the elbow region of the ferrite furnace tube.

4. The calibration sample tube device for detecting oxide scale buildup in ferrite furnace tubes according to claim 1, characterized in that, The insulating element is a high-temperature resistant insulating sheet, and the simulated medium is an oxide scale medium.

5. The calibration sample tube device for detecting oxide scale buildup in ferrite furnace tubes according to claim 4, characterized in that, The insulating component is a mica sheet.

6. The calibration sample tube device for detecting oxide scale buildup in ferrite furnace tubes according to claim 1, characterized in that, The sample tube has multiple mounting positions at the preset position, and the mounting positions are spaced apart along the extension direction of the sample tube.

7. The calibration sample tube device for detecting oxide scale buildup in ferrite furnace tubes according to claim 1, characterized in that, The mounting position is an insertion port located on the outer wall of the sample tube, for inserting the isolation element into the inner cavity of the sample tube through the insertion port and forming a barrier against the simulated medium.

8. The calibration sample tube device for detecting oxide scale buildup in ferrite furnace tubes according to any one of claims 1 to 7, characterized in that, The sample tube has a grading mark at the preset position and on the closure to indicate the stacking level of the simulated medium.

9. A verification method for detecting oxide scale buildup in ferritic furnace tubes, characterized in that, The method is implemented using the calibration sample tube device for detecting oxide scale buildup in ferrite furnace tubes according to any one of claims 1 to 8, and includes the following steps: S1: Obtain the sample tube that matches the specifications of the ferrite furnace tube to be tested, and fill the sample tube with the simulated medium; S2: The isolation element limits and separates the simulated medium to form at least two stacking simulation zones, and different stacking simulation zones correspond to different stacking states; S3: Use the magnetic detection device to be verified to test the sample tube and obtain the detection response of each of the stacking simulation regions; S4: Adjust the parameters of the magnetic detection device according to the detection response, and evaluate its detection capability.

10. The verification method for detecting oxide scale buildup in ferrite furnace tubes according to claim 9, characterized in that, In step S2, the different stacking states include multiple stacking levels divided according to a preset grading threshold. The grading threshold includes the stacking degree expressed as a percentage. By changing the setting position of the separator on the sample tube, the same sample tube can form different stacking states.

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