A heat exchanger heat transfer pipe hole positioning method based on polar coordinate positioning

Abstract

The application discloses a heat transfer pipe hole positioning method based on polar coordinate positioning of a heat exchanger, and comprises the following steps: S1, a mechanical arm is installed to a flange surface of the heat exchanger, and a rotating disc assembly is moved to a tube plate; S2, each shaft of the multi-shaft mechanical arm is adjusted and corrected, so that the mechanical arm is restored to a default initial state; S3, in the initial state of the mechanical arm, a preset positioning reference hole position is selected; S4, a crosshair at the front end of a mechanical arm probe is adjusted to the center of the reference hole to perform manual calibration; and S5, the relative position of a target hole to the reference hole is calculated through the calibrated reference hole, and the target hole is relatively positioned. The method avoids the cumbersome work of modifying hardware devices through algorithm calculation, and because no hardware change is involved, the complexity of operation can be reduced in system maintenance and modification.

Description

Technical Field

[0001] This invention relates to the field of nuclear power plant heat exchanger maintenance technology, specifically to a method for locating heat transfer tube holes in heat exchangers based on polar coordinate positioning. Background Technology

[0002] The steam generator is one of the key pieces of equipment in a high-temperature gas-cooled reactor (HTGR) nuclear power system, connecting and isolating the primary and secondary loops of the HTGR. Within the steam generator, the heat transfer tubes are a crucial component of the primary loop pressure boundary, serving as a vital barrier to prevent the leakage of radioactive fission products. The heat exchanger tube sheet is a circular plate with orifices for the heat transfer tubes. During operation, the HTGR steam generator tubes are surrounded by extremely hot primary loop coolant helium gas, while superheated steam flows through the tubes. Operating under high temperature, high pressure, and high radiation dose environments, the heat transfer tubes are susceptible to damage due to mechanical or chemical causes. Given the high temperature, high radiation levels, and harsh operating conditions within the steam generator tube box, manual inspection of the tube sheet poses a significant risk of radioactive contamination to personnel. Therefore, mechanical methods are used for heat transfer tube maintenance.

[0003] Mechanical maintenance is employed. A slide rail is fixed to the steam generator nozzle using a mounting plate or other mechanical means. A turntable assembly rotates one revolution at the front end of the slide rail, and the maintenance device mounted on the turntable can move within a radius. Maintenance probes are mounted in front of the turntable for location-based maintenance. During operation, the slide rail extends in front of the tube sheet. Since the tube sheet is circular at the end of the evaporator, the rotational characteristics of the turntable at the front end of the slide rail establish polar coordinates for full-coverage positioning of the heat transfer tubes on the tube sheet. Using the polar coordinates established by the turntable, the coordinates of all heat transfer tubes on the tube sheet are preset, and the rotation and movement of the turntable reach the designated polar coordinates. Due to the slide rail needing to extend forward a certain distance, the weight of the turntable and maintenance probes, and the installation position of the slide rail and turntable, a slight offset may occur between the actual polar coordinates and the preset polar coordinates, making it impossible to ideally locate the heat transfer tubes using the originally preset polar coordinates. Summary of the Invention

[0004] To address the aforementioned problem of inaccurate heat transfer tube positioning, this invention provides a method for locating heat exchanger heat transfer tube orifices based on polar coordinate positioning.

[0005] The present invention is achieved using the following technical solution:

[0006] A method for locating the tube holes of a heat exchanger based on polar coordinate positioning includes the following steps:

[0007] S1. The robotic arm is installed on the heat exchanger flange face and the turntable assembly is moved to the tube sheet;

[0008] S2. Adjust and calibrate each axis of the multi-axis robotic arm to restore the robotic arm to its default initial state;

[0009] S3. In the initial state of the robotic arm, select the preset positioning reference hole position;

[0010] S4. Using the crosshair at the front end of the robotic arm probe, manually calibrate the crosshair to the center of the reference hole.

[0011] S5. Using the calibrated reference hole, calculate the positional relationship between the target hole and the reference hole, and perform relative positioning of the target hole.

[0012] A further improvement of the present invention is that, in step S1, after the device is fixed to the flange face of the steam generator nozzle, the rotation axis of the turntable assembly is adjusted to 180° and the displacement axis is adjusted to 150mm, the device is in the theoretical center position, and the slide rail assembly is moved to the tube sheet.

[0013] A further improvement of the present invention is that, in step S1, the tube sheet has a total of 665 heat transfer tube holes, and the numbering rule is set as follows: the first row is row 0, the leftmost first column is column -26, the rightmost column is column +26, and the column where the middle axis of symmetry is located is column 0.

[0014] A further improvement of the present invention is that, in step S2, the scale of each axis of the robotic arm is adjusted to the initial scale position, and the initial adjustment of each axis is performed through the video at the front end of the robotic arm, so that each axis is restored to the default state of the device.

[0015] A further improvement of the present invention is that, in step S3, the selected reference holes are preferably evenly distributed on the tube sheet, and the reference holes are representative of other tube holes.

[0016] A further improvement of the present invention is that, in step S4, when calibrating the reference hole, the infrared crosshair carried by the front probe is used for manual calibration. The crosshair is moved to the center of the reference hole and calibrated to obtain the true position of the reference hole.

[0017] A further improvement of the present invention is that, in step S5, the relative positional relationship between the target hole and its adjacent reference hole is calculated using polar coordinates, and the position is calculated using this positional relationship to finally obtain the true position of the target hole.

[0018] A further improvement of the present invention is that, when calculating the position of the target hole, the position calculation is performed by relying on one or more reference holes, and the average or weighted average value is used when calculating the position of multiple reference holes.

[0019] The present invention has at least the following beneficial technical effects:

[0020] Compared to traditional direct positioning, this invention utilizes a relative positioning method, dividing the entire tube sheet into multiple sub-regions. The resulting offset is used for relative positioning within these regions, thereby correcting for offsets caused by external factors. Traditional positioning starts from the center point, calibrating the origin before positioning the entire tube sheet. However, under the influence of external gravity and equipment limitations, the tube offset can continuously expand outwards, leading to inaccurate positioning. In this invention, each sub-region actually has similar offsets and errors; calibrating the center of a region is equivalent to calibrating an entire region. Therefore, it is not necessary to calibrate all the holes to offset them, yet the correction can cover the entire tube sheet. This not only greatly reduces the calibration workload but also improves positioning accuracy. This invention avoids the tedious work of modifying hardware through algorithmic calculations, and because it does not involve hardware changes, system maintenance and modifications are less complex. Attached Figure Description

[0021] Figure 1 The control flowchart for the method of locating the heat transfer tube holes in a heat exchanger.

[0022] Figure 2 This is a schematic diagram of the turntable assembly.

[0023] Figure 3 This is a schematic diagram of the heat exchanger tube sheet.

[0024] Figure 4 This is a schematic diagram of a cross laser line.

[0025] Figure 5 This is a flowchart for mechanical zero-point calibration.

[0026] Figure 6 This is a schematic diagram of target hole error correction based on the reference hole.

[0027] Figure 7 This is a schematic diagram of the coverage area of ​​the reference hole.

[0028] Figure 8 This is a schematic diagram for confirming the reference hole.

[0029] Figure 9 This is a schematic diagram showing the position of the reference hole.

[0030] Figure 10 This is a schematic diagram showing the positional relationship between the reference hole and the target hole. Detailed Implementation

[0031] Exemplary embodiments of the present disclosure will now be described in more detail with reference to the accompanying drawings. While exemplary embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure may be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided to enable a more thorough understanding of the present disclosure and to fully convey the scope of the disclosure to those skilled in the art. It should be noted that, unless otherwise specified, the embodiments and features described herein can be combined with each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0032] like Figure 1 As shown, the present invention provides a method for locating the tube holes of a heat exchanger based on polar coordinate positioning, comprising the following steps:

[0033] S1. Install the equipment and move the turntable assembly to the tube sheet.

[0034] After the equipment is fixed on the flange face of the steam generator nozzle, adjust the rotation axis 2 of the turntable assembly to 180° and the displacement axis 3 to 150mm. When the equipment is in the theoretical center position, move the slide rail assembly to the tube sheet 1, ensuring that the top clearance L of the slide rail assembly is not less than 50mm.

[0035] The tube sheet has a total of 665 heat transfer tube holes, numbered as follows: the first row is row 0, the leftmost column is column -26, the rightmost column is column +26, and the column containing the central axis of symmetry is column 0. For example Figure 3 The black hole is numbered (0, -7). The hole to its right is (0, -5), the hole to its lower left is (1, -6), and the hole to its lower right is (1, -4).

[0036] S2, Mechanical Zero Point Calibration

[0037] The turntable assembly is equipped with a video camera and a crosshair laser line at its front end. The center of the crosshair laser line is the working center of the device. After installation, the center of the crosshair will be near the center of hole 6 (15,0) on the tube sheet. Figure 4 As shown, begin mechanical zero-point calibration. The calibration steps are as follows: Figure 5 As shown.

[0038] S2-1: Zeroing the rotation axis. Fine-tune the rotation axis until the center line 8 of the displacement axis is parallel to the center lines of holes (14, -1)4 and (14, 1)5. Set the rotation axis angle at this point as the zero point of the rotation axis.

[0039] S2-2: Zeroing the displacement axis. Record the distance between the centerline 8 of the displacement axis and the centerlines of holes (14, -1)4 and (14, 1)5. Rotate the axis 180° relative to the motion mode. Adjust the displacement axis until the distance between the centerline 8 of the displacement axis and the centerlines of holes (14, -1)4 and (14, 1)5 is consistent with the recorded value before rotation. Half of the displacement axis motion value is the mechanical zero point error of the displacement axis. Set this error.

[0040] S2-3: Coordinate Compensation. Using relative motion mode, fine-tune the rotation axis and displacement axis until the center of the cross laser line coincides with the center of the tube sheet's center hole 6. Save the errors of the rotation axis and displacement axis to complete coordinate compensation.

[0041] S3. Select the reference hole position.

[0042] S3-1: Under existing mechanical precision conditions, the errors caused by gravity and mechanical installation precision shall not exceed a distance of one hole position at the outermost ring of the tube sheet. The actual position of the reference hole itself contains all errors, and the errors of nearby holes are similar to those of the reference hole. Based on the coverage of the reference hole, the reference hole can approximate the nearby holes, and these errors can be corrected by calculating the coordinates of nearby holes using the reference hole. For example... Figure 6 As shown.

[0043] S3-2: To make reasonable use of the effective error range, the coverage of the tube sheet should be maximized within a distance of 5 boreholes. The coverage area is determined through planning, and all boreholes within this area use similar offset errors. The location of exactly 5 boreholes is designated as a common area, and the assigned area is selected based on the actual situation. For example... Figure 7 As shown.

[0044] S3-3: The reference hole numbers obtained through the center of the region are (3,0), (7,-12), (7,12), (11,0), (11,-24), (11,24), (15,-14), (15,12), (19,0), (19,-24), (19,24), (23,-12), (23,12), (27,0), for a total of 14 reference hole positions. Figure 8 As shown.

[0045] S4, Reference Hole Calibration

[0046] The actual positions of 14 reference holes are manually calibrated and saved using the rotation and displacement axes. For example, the polar coordinates of reference hole A are marked as (R'a, C'a), where R'a represents the turntable radius and C'a represents the rotation angle. Figure 9 As shown.

[0047] The actual position coordinates of the 14 reference holes are recorded as (R'1, C'1), (R'2, C'2), (R'3, C'3)...(R'14, C'14).

[0048] S5. Locate the target hole using the reference hole.

[0049] S5-1: Calculate the nearest reference hole to the target hole position

[0050] In order to utilize the distance formula of the rectangular coordinate system, the polar coordinates of the target hole position and the reference theoretical position are converted into rectangular coordinates.

[0051] Polar coordinates (R) a C a Transform to Cartesian coordinates (X) a Y a )formula

[0052]

[0053] Using the obtained rectangular coordinates, the reference hole closest to the target hole position is calculated using the distance formula.

[0054] Distance formula

[0055]

[0056] Where (Xa, Ya) and (Xb, Yb) represent the coordinates of any hole A and any hole B, respectively.

[0057] After calculating the distances from all reference holes to the target hole, select the closest one as the reference hole for solving the target hole problem.

[0058] S5-2: Calculate the average hole spacing

[0059] Due to errors, the mechanical maintenance plane may not be perfectly parallel to the plane of the tube sheet, resulting in distortion of the horizontal hole spacing. The average hole spacing needs to be calculated using the distance between the two hole positions (15,-14) and (15,12).

[0060]

[0061] S5-3: Calculate the relative path vector of the target hole position using the reference hole.

[0062] Using the nearest reference hole as the starting position, search for the nearest relative path to the target hole, such as... Figure 10 As shown.

[0063] The path vector from the reference hole number (a, b) to the target hole is (a-1, b+2.5).

[0064] S5-4: Calculating relative vectors using relative paths

[0065] The unit vector for horizontal movement of one hole position is (0, ±1), and the unit vector for line break is (±1, 0). The length of one unit vector in the horizontal direction is the average hole spacing L, and the height of line break is L*sin(60°). Therefore, the rectangular coordinate vector calculated from the relative path vector (a-1, b+2.5) and the average hole spacing is (L*sin(60°), 2.5L).

[0066] S5-5: Synthesizing the final target hole position coordinates

[0067] Based on the vectors obtained from the aforementioned reference holes and the vector calculation formula, the coordinates of target hole B, calculated from reference hole A, are as follows:

[0068]

[0069] Note: General formula for calculating coordinates of any hole

[0070] Min(A) represents finding the nearest reference hole to hole A, Base represents the reference hole closest to the target hole A, and the path vector from the reference hole to hole A is (line, col). Based on the above steps, a general calculation method is obtained:

[0071] Nearest reference hole: Base = Min(A)

[0072]

[0073]

[0074] Although the present invention has been described in detail above with general descriptions and specific embodiments, modifications or improvements can be made to it, which will be obvious to those skilled in the art. Therefore, all such modifications or improvements made without departing from the spirit of the present invention fall within the scope of protection claimed by the present invention.

Claims

1. A method for locating the tube holes of a heat exchanger based on polar coordinate positioning, characterized in that, Includes the following steps: S1. Install the robotic arm onto the heat exchanger flange and move the turntable assembly to the tube sheet; after the equipment is fixed on the steam generator nozzle flange, adjust the rotation axis of the turntable assembly to 180° and the displacement axis to 150mm, so that the equipment is at the theoretical center position, and move the slide rail assembly to the tube sheet; the tube sheet has a total of 665 heat transfer tube holes, and the numbering rule is as follows: the first row is row 0, the leftmost first column is column -26, the rightmost column is column +26, and the column where the middle axis of symmetry is located is column 0; S2. Adjust and calibrate each axis of the multi-axis robotic arm to restore the robotic arm to its default initial state; adjust the scale of each axis of the robotic arm to the initial scale position, and perform initial adjustment of each axis through the front-end video of the robotic arm to restore each axis to the default state of the device; S3. In the initial state of the robotic arm, select the preset positioning reference hole position; the selected reference holes should be evenly distributed on the tube sheet, and the reference holes should be representative of other tube holes; S4. Using the crosshair at the front end of the robotic arm probe, manually calibrate the crosshair to the center of the reference hole. When calibrating the reference hole, the infrared crosshair carried by the front probe is used for manual calibration. The crosshair is moved to the center of the reference hole and calibrated to obtain the true position of the reference hole. The relative positional relationship between the target hole and its neighboring reference holes is calculated using polar coordinates. This positional relationship is then used to calculate the actual position of the target hole. When calculating the position of the target hole, one or more reference holes are used. When calculating the position of multiple reference holes, the mean or a weighted average value is used. S5. Using the calibrated reference hole, calculate the positional relationship between the target hole and the reference hole, and perform relative positioning of the target hole.

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