Device and method for measuring inner diameter of vertical tank body

Abstract

The invention is applicable to the technical field of nondestructive testing, and provides a device and a method for measuring the inner diameter of a vertical tank, the device comprises a host, a tripod, a rotating platform, a rotating rod and a plurality of laser modules, the rotating platform is mounted at the top of the tripod, the rotating rod is mounted at the position of a rotating central axis of the rotating platform, and the laser modules are mounted on the rotating platform. The multiple laser modules are installed on the upper portion of the rotating rod at equal intervals in the height direction and arranged in the same direction, and emergent light rays of all the laser modules are parallel and located on the same plane. The device is simple in structure, small in size and low in cost, can pass through a fine vertical storage tank opening, and is easy to carry and store; the device is convenient to operate, the rotating platform is controlled by the host to rotate accurately, measured data can be obtained on site, and the actual inner diameter circle of the vertical storage tank is obtained after correction. The device can obviously reduce the cost and is convenient to popularize.

Description

Technical Field

[0001] The invention belongs to the technical field of nondestructive testing, and in particular relates to a device and a method for measuring the inner diameter of a vertical tank. Background Art

[0002] Vertical tanks, as a medium storage equipment widely used in industry, have many characteristics and uses. Vertical tanks refer to storage equipment that stands upright as a whole. Its structure is usually composed of tanks, support legs, inlet and outlet ports, vents, inspection ports and other parts. The tank body is generally made of stainless steel, which has high strength, corrosion resistance and sealing performance. The volume of vertical tanks can be customized according to different needs, and it occupies a small area, which is suitable for high-rise buildings and large tank fields. Vertical tanks are widely used in various industrial fields, such as petroleum, chemical, food, medicine, etc. They are used to store various gases, liquids and solid materials, such as coal gas, liquefied gas, fuel, water, liquid petrochemical raw materials and products, etc. In the petroleum industry, vertical tanks are often used to store crude oil, refined oil, etc.; in the chemical industry, they are used to store various chemical raw materials and products; in the food industry, they are used to store liquid foods such as juice and beverages.

[0003] Among the many parameters of a vertical tank, its inner diameter is a key parameter. The inner diameter of a vertical tank is its horizontal dimension, which directly determines the cross-sectional area and total volume of the tank, thus affecting its storage capacity. Changes in the inner diameter will also affect the force distribution of the tank, and reasonable structural design and calculation are required to ensure the safety and stability of the tank during normal use. The inner diameter also directly affects the economic benefits of the tank. The choice of inner diameter is also closely related to other parameters, such as the thickness and height of the tank bottom, the position and size of the inlet and outlet, etc. The reasonable matching of these parameters can ensure the normal operation and long-term stability of the tank. The size of the inner diameter will also affect the maintenance and management of the tank. Tanks with larger inner diameters may be more difficult to clean, inspect and sample, and require special equipment and methods to operate. Therefore, it is necessary to measure the inner diameter of the vertical tank. There are currently several measurement methods:

[0004] The first method is the steel tape measurement method. The circumference of the first ring plate of the tank is measured by a steel tape measure at 3 / 4 of the outside, and its outer diameter is calculated accordingly. Based on this standard, a radial deviation measuring instrument (such as C-3 or similar equipment) is used to measure the diameter of each other ring plate, and compared with the outer diameter of the first ring plate to obtain the corresponding radial deviation. Then, the actual inner diameter of each ring plate is corrected by the radial deviation data. The second method is the total station measurement method. The total station is stably installed at an appropriate position near the tank, and automatic measurement is performed by inputting the measurement point position parameters. The total station can measure the diameter of each ring plate of the tank at different heights, and obtain the inner diameter data through data processing. The operation process of these two methods is relatively complicated. The third method is the three-dimensional laser scanning technology. The three-dimensional laser scanning technology uses the principle of laser ranging to record the three-dimensional coordinate information and reflectivity information of the dense points on the target surface, and obtains the three-dimensional model of the target object through computer processing. In the measurement of the inner diameter of the tank, this technology can accurately obtain the three-dimensional coordinate data of the inner wall of the tank, and then calculate the inner diameter. As a precision measuring instrument, the current three-dimensional laser scanner is mainly imported equipment and is expensive. Summary of the invention

[0005] In view of the above problems, the purpose of the present invention is to provide a device and method for measuring the inner diameter of a vertical tank, aiming to solve the technical problems of the existing method of complex measurement process and high cost.

[0006] The present invention adopts the following technical solution:

[0007] On the one hand, the device for measuring the inner diameter of a vertical tank comprises a main unit, a tripod, a rotating platform, a rotating rod and a plurality of laser modules, wherein the rotating platform is mounted on the top of the tripod, the rotating rod is mounted to the rotation center axis position of the rotating platform, the plurality of laser modules are mounted on the upper part of the rotating rod at equal intervals in the height direction and are arranged in the same direction, and the emitted light rays of all laser modules are parallel and located in the same plane.

[0008] Furthermore, the length of each leg of the tripod bracket is individually adjustable.

[0009] Furthermore, the rotating platform includes a base made of a rigid material, the base is fixed to the top of a tripod, and a high-precision servo motor is installed on the base.

[0010] Furthermore, the rotating rod is made of lightweight rigid material.

[0011] Furthermore, the spacing between the laser modules is set to be between 100 mm and 300 mm.

[0012] Furthermore, the host is connected to the rotating platform and the laser module via cables to provide power and perform data interaction, data processing and data display.

[0013] On the other hand, the method for measuring the inner diameter of a vertical tank is implemented based on the device, and the method comprises the following steps:

[0014] Step S1, place the device at the center of the bottom plate of the vertical storage tank, adjust the height of the three legs of the tripod and fix the tripod so that the rotating platform is as parallel to the bottom plate of the storage tank as possible, and the rotating axis of the rotating rod is basically parallel to the central axis of the vertical storage tank;

[0015] Step S2, during the measurement process, the servo motor on the rotating platform is controlled to drive the rotating rod to rotate smoothly around its central axis. Every time it rotates a small angle, the host records the distance from each distance measuring module to the wall of the vertical storage tank at this sampling angle, and records the current rotation angle of the servo motor. The measurement is completed after the servo motor drives the rotating rod to rotate one circle, and the distance data on the entire measuring surface is obtained;

[0016] Step S3, calculating the angle A between the measuring surface and the horizontal cross section of the vertical storage tank by using the distance values ​​detected by each distance measuring module at a rotation angle and the spacing between the distance measuring modules;

[0017] Step S4, multiplying the recorded distance data on the entire measuring surface by cosA to obtain all projection data points of the positive section;

[0018] Step S5, establishing a coordinate system on the horizontal cross section of the vertical storage tank, fitting each projection data point into a circle, determining the position of the center of the circle, and connecting each projection data point into an actual inner diameter circle of the vertical storage tank.

[0019] Furthermore, the method further comprises the following steps:

[0020] Step S6: Mark the positions of the maximum diameter and the minimum diameter on the graph of the actual inner diameter circle, and calculate the out-of-roundness rate.

[0021] Further, in step S3, the angle A=arctan((L i+1 -L i ) / d), where d is the distance between the ranging modules, (L i+1 -L i ) is the distance difference detected by one pair of adjacent distance measuring modules, or is the average value of the distance difference detected by all adjacent distance measuring modules.

[0022] Furthermore, in step S5, each projection data point is fitted into a circle by the least square method.

[0023] The beneficial effects of the present invention are as follows: the device of the present invention is an automatic measuring device based on optics, which can realize automatic measurement of the inner diameter of a vertical tank; the device has a simple structure, a small volume, and a low cost, and can pass through a small opening of a vertical tank, and is easy to carry and store; and the device is easy to operate, and the rotating platform is accurately rotated by controlling the host, and the measurement data can be obtained on site, and the actual inner diameter circle of the vertical tank can be obtained after correction. The device can significantly reduce costs and is easy to promote. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 is a structural principle diagram of a device for measuring the inner diameter of a vertical tank provided by an embodiment of the present invention;

[0025] Figure 2 It is a data correction principle diagram provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0026] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0027] In order to illustrate the technical solution of the present invention, a specific embodiment is provided below for illustration.

[0028] It is difficult to measure the inner diameter of a vertical tank, such as Figure 1 As shown, this embodiment provides a device for measuring the inner diameter of a vertical tank, comprising a main unit 1, a tripod 2, a rotating platform 3, a rotating rod 4 and a plurality of laser modules 5, wherein the rotating platform 3 is mounted on the top of the tripod 2, the rotating rod 4 is mounted to the rotation center axis position of the rotating platform 3, the plurality of laser modules 5 are mounted on the upper part of the rotating rod 4 at equal intervals in the height direction and are arranged in the same direction, and the emitted light rays of all the laser modules 5 are parallel and located in the same plane.

[0029] In this structure, the three legs of the tripod can be adjusted in length individually to keep the tripod stable in the vertical tank. While maintaining stability, the length of the three legs is adjusted so that the entire device (mainly the rotating rod part) is kept as parallel as possible to the center line of the vertical tank.

[0030] The main function of the rotating platform is to drive the rotating rod fixed thereon to rotate. The rotating platform includes a base of a rigid material and a high-precision servo motor. The base is fixed to the top of the tripod by bolts, and the servo motor is installed on the base. The role of the rotating platform using a rigid base is to firmly support the rotating rod while connecting the tripod to prevent the rotating rod from deforming during the measurement process. The high-precision servo motor is the core part of the rotating platform. The servo motor is stably fixed on the rigid base to maintain stability during the measurement.

[0031] The rotating rod is fixedly installed along the central axis of rotation. The function of the rotating rod is to carry the laser module, and the rotating rod rotates along the center of the high-precision servo motor rotation axis. The rotating rod is made of lightweight rigid materials, such as high-parameter carbon fiber tubes. Since the lightweight and rigid rotating rod itself is light but not easy to deform, it is not easy to cause deformation of the entire system, reducing system errors. Lightweight aluminum profiles can also be used if the rigidity requirements are met.

[0032] There are multiple laser modules, which are installed on the upper part of the rotating rod and installed at equal intervals. The laser modules are used for laser ranging. The spacing between two adjacent laser modules can generally be set to a fixed value between 100mm and 300mm. Generally speaking, for relatively small vertical storage tanks, such as those with an inner diameter less than 5m, a relatively small spacing, such as 100mm, can be set. For relatively large vertical storage tanks, such as those with an inner diameter greater than 5m, a relatively large spacing, such as 300mm, can be set. There are three laser modules in the figure. It should be noted that when installing the laser modules, the output lasers of the three laser modules must be kept in the same plane and coaxially, and the three laser beams must be parallel. During the specific installation, the installation position and angle of the laser module itself can be finely adjusted, and the relative position of the laser module on the rotating rod can be fixed by using the glue dispensing process.

[0033] The host is electrically connected to the rotating platform, laser module, etc. through cables. While providing power, it can also perform data interaction, data processing and data display, such as controlling the rotation of the rotating platform, setting the parameters of the rotating platform, receiving the distance data collected by the laser module, and calculating, processing and displaying it. The host is powered by a lithium battery, which also powers the rotating platform and laser module.

[0034] Based on the above device, this embodiment also provides a method for measuring the inner diameter of a vertical tank, the method comprising the following steps:

[0035] Step S1, place the device at the center of the bottom plate of the vertical storage tank, adjust the height of the three legs of the tripod and fix the tripod so that the rotating platform is as parallel to the bottom plate of the tank as possible, and the rotating axis of the rotating rod is basically parallel to the central axis of the vertical storage tank.

[0036] When measuring a vertical tank, the operator can enter the tank safely, carry the device into the tank, and then stably place the device near the center of the tank bottom plate. After fixing the device, adjust the height of the three legs of the tripod so that the rotating platform is basically parallel to the tank bottom plate. Under this condition, the rotating axis of the rotating rod is basically parallel to the central axis of the vertical tank. Since it is manually adjusted, it is impossible to ensure complete parallelism, so the present invention also needs to automatically correct the error caused by the calibration non-parallel problem.

[0037] Step S2, during the measurement process, the servo motor on the rotating platform is controlled to drive the rotating rod to rotate smoothly around its central axis. Every time it rotates a small angle, the host records the distance from each distance measurement module to the wall of the vertical storage tank at this sampling angle, and records the current rotation angle of the servo motor. The measurement is completed after the servo motor drives the rotating rod to rotate one circle, and the distance data on the entire measuring surface is obtained.

[0038] After the device is installed and connected to the host, it can be turned on for testing. At this time, the operator should try to squat to avoid blocking the laser beam of the laser module.

[0039] During the measurement process, the servo motor drives the rotating rod to rotate smoothly around its central axis. Every time it rotates a small angle (i.e., sampling angle), such as 0.1 degrees, the host records the respective distances from the three laser modules to the wall of the vertical tank at this sampling angle, such as Figure 2 As shown, they are recorded as L1, L2, and L3, and the current rotation angle of the servo motor is recorded. After obtaining stable distance data, the servo motor continues to control the rotation of a small angle, and then reads the readings of the three laser modules. This is repeated until the distance data on the entire measurement surface is obtained.

[0040] Step S3, calculating the angle A between the measuring surface and the horizontal cross section of the vertical storage tank by using the distance values ​​detected by each distance measuring module at a rotation angle and the spacing between the distance measuring modules.

[0041] Step S4: multiply the recorded distance data on the entire measuring surface by cosA to obtain all projection data points of the positive section.

[0042] like Figure 2 As shown in the figure, since there may be a small angle between the rotation axis of the rotating rod and the center line of the tank, the measuring surface may be an elliptical surface. In this step, the angle is calculated first. This angle is also the angle A between the measuring surface and the horizontal cross section of the vertical tank. Angle A = arctan((L i+1 -L i ) / d), where d is the distance between the ranging modules, (L i+1 -L i) is the distance difference detected by one pair of adjacent distance measuring modules, or is the average value of the distance difference detected by all adjacent distance measuring modules.

[0043] For example, the distance data L1, L2, and L3 detected by the three laser modules on the measuring surface are combined with the distance d between adjacent laser modules to obtain: tanA = (L3-L2) / d, so ∠A can be calculated, and then the distance data on the measuring surface is multiplied by cosA to obtain all the data points that constitute the positive section.

[0044] In addition, if necessary, you can further obtain and record the long axis of the measuring surface, the center of the measuring surface, the central angle of the measuring point of the measuring surface, the angle and length between the measuring point of the measuring surface and the projection point of the tank cross section, etc.

[0045] Step S5, establishing a coordinate system on the horizontal cross section of the vertical storage tank, fitting each projection data point into a circle, determining the position of the center of the circle, and connecting each projection data point into an actual inner diameter circle of the vertical storage tank.

[0046] In this step, the projection data points are fitted into a circle using the least squares method. It should be noted that the least squares method is only used to determine the center of the circle. The actual inner diameter circle of the storage tank is the circle formed by directly connecting the actual measured projection data points, which can truly reflect the internal structure of the container.

[0047] Step S6: Mark the maximum diameter and minimum diameter positions on the graph of the actual inner diameter circle, and calculate the out-of-roundness rate.

[0048] Finally, the positions of the maximum diameter and the minimum diameter can be determined based on the distance of the projection data point from the center of the circle, and finally the loss-of-circularity rate can be calculated.

[0049] Therefore, it can be seen from the above method that the device has a simple structure, a small size, a low operation method, low cost, simple calculation, the detection data can be obtained on site, and the results can be obtained quickly, which is suitable for wide promotion and use.

[0050] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A device for measuring the inner diameter of a vertical tank, characterized in that: The device includes a main unit, a tripod, a rotating platform, a rotating rod and a plurality of laser modules, wherein the rotating platform is installed on the top of the tripod, the rotating rod is installed to the rotation center axis position of the rotating platform, the plurality of laser modules are installed on the upper part of the rotating rod at equal intervals along the height direction and are arranged in the same direction, and the emitted light rays of all the laser modules are parallel and located in the same plane.

2. The device for measuring the inner diameter of a vertical tank as claimed in claim 1, characterized in that: The length of each leg of the tripod bracket is adjustable individually.

3. The device for measuring the inner diameter of a vertical tank as claimed in claim 2, characterized in that: The rotating platform comprises a base of a rigid material, the base is fixed to the top of a tripod, and a high-precision servo motor is mounted on the base.

4. The device for measuring the inner diameter of a vertical tank according to any one of claims 1 to 3, characterized in that: The rotating rod is made of lightweight rigid material.

5. The device for measuring the inner diameter of a vertical tank as claimed in claim 4, characterized in that: The spacing between the laser modules is set to be between 100 mm and 300 mm.

6. The device for measuring the inner diameter of a vertical tank as claimed in claim 5, characterized in that: The host is connected to the rotating platform and the laser module via cables, provides power and performs data interaction, data processing and data display.

7. A method for measuring the inner diameter of a vertical tank, characterized in that: The method is implemented based on the device according to any one of claims 1 to 6, and the method comprises the following steps: Step S1, place the device at the center of the bottom plate of the vertical storage tank, adjust the height of the three legs of the tripod and fix the tripod so that the rotating platform is as parallel to the bottom plate of the storage tank as possible, and the rotating axis of the rotating rod is basically parallel to the central axis of the vertical storage tank; Step S2, during the measurement process, the servo motor on the rotating platform is controlled to drive the rotating rod to rotate smoothly around its central axis. Every time it rotates a small angle, the host records the distance from each distance measuring module to the wall of the vertical storage tank at this sampling angle, and records the current rotation angle of the servo motor. The measurement is completed after the servo motor drives the rotating rod to rotate one circle, and the distance data on the entire measuring surface is obtained; Step S3, calculating the angle A between the measuring surface and the horizontal cross section of the vertical storage tank by using the distance values ​​detected by each distance measuring module at a rotation angle and the spacing between the distance measuring modules; Step S4, multiplying the recorded distance data on the entire measurement surface by cosA to obtain all projection data points of the positive section; Step S5, establishing a coordinate system on the horizontal cross section of the vertical storage tank, fitting each projection data point into a circle, determining the position of the center of the circle, and connecting each projection data point into an actual inner diameter circle of the vertical storage tank.

8. The method for measuring the inner diameter of a vertical tank as claimed in claim 7, characterized in that: The method further comprises the steps of: Step S6: Mark the maximum diameter and minimum diameter positions on the graph of the actual inner diameter circle, and calculate the out-of-roundness rate.

9. The method for measuring the inner diameter of a vertical tank as claimed in claim 8, characterized in that: In step S3, the angle A=arctan((L i+1 -L i ) / d), where d is the distance between the ranging modules, (L i+1 -L i ) is the distance difference detected by one pair of adjacent distance measuring modules, or is the average value of the distance difference detected by all adjacent distance measuring modules.

10. The method for measuring the inner diameter of a vertical tank according to claim 9, characterized in that: In step S5, each projection data point is fitted into a circle by the least square method.

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