A heat exchanger oblique arrangement tube bundle support strip expansion device and pipe penetrating method

Abstract

The application discloses a kind of inclined arrangement tube bundle support strip expansion device and pipe penetrating method of pressurized water reactor passive residual heat removal heat exchanger, the device includes expansion pin, expansion screw, positioning groove plate, nylon top wire and butterfly nut, wherein, positioning groove plate can be fixed in tube bundle support strip expansion pin, by pre-tightening butterfly nut, the expansion screw inside expansion pin moves along the taper hole section inside expansion pin, so that the front end of expansion section is expanded, and the gap L between two adjacent tube bundle support strips is expanded;When the gap L between two tube bundle support strips is reduced after welding with the toothed plate, the installation sequence of the device can be set according to the pipe penetrating sequence, and the gap L between tube bundle support strips is expanded;In the process of expansion, expansion pin does not rub with the semicircular groove of support strip, and does not scratch tube bundle support strip, to ensure the pipe penetrating effect of heat exchange tube.

Description

Technical Field

[0001] This invention relates to the field of nuclear power heat exchanger manufacturing, specifically to an auxiliary device and method for pipe installation in a passive waste heat removal heat exchanger for pressurized water reactors. Background Technology

[0002] The passive residual heat removal heat exchanger is a critical Class I nuclear-grade device used for passive cooling within the containment structure of a pressurized water reactor nuclear power plant. Installed inside a water tank at the top of the containment, it is enclosed by a large stainless steel frame on the outside and cooled internally by exposed C-shaped heat exchange tubes. The heat exchange tubes carry a primary loop medium containing nuclear radiation, therefore, strict requirements are placed on the quality of the outer wall of the heat exchange tubes during manufacturing, prohibiting any impacts or scratches. Each row of C-shaped heat exchange tubes 63 in the tube bundle assembly is fixed and supported by multiple sets of tube bundle support bars 61 welded to the toothed plates 62 of the outer frame to prevent vibration during operation.

[0003] Based on the distribution of C-shaped heat exchange tubes 63 within the frame, the tube bundle support bars 61 are arranged in various ways, including horizontally and obliquely. During equipment manufacturing, the tube bundle support bars 61 are pre-installed in the slots of the toothed plate 62 and welded to it. After all the tube bundle support bars 61 are installed and welded, the C-shaped heat exchange tubes are inserted row by row from the inside out and from bottom to top into the semi-circular grooves 611 between the tube bundle support bars, up to the end face of the tube sheet 64, and then welded to it. Figure 7 As shown in the image.

[0004] To prevent friction between the C-shaped heat exchange tubes 63 and the tube bundle support bars 61 during operation, the design requires that the diameter D of the semi-circular groove 611 of the tube bundle support bars be only 0.1 mm larger than the diameter d of the heat exchange tubes. During tube insertion, the coaxiality between the semi-circular groove 611 of each row of tube bundle support bars and the tube sheet holes must be controlled within 0.3 mm. Furthermore, stress scratches are not allowed between the C-shaped heat exchange tubes 63 and the tube bundle support bars 61 during tube insertion to prevent scratches on the surface of the heat exchange tubes.

[0005] During the welding of the tube bundle support strip 61 to the toothed plate 62, thermal shrinkage during welding causes slight elastic deformation of the tube bundle support strip 61 after welding, resulting in a smaller spacing L between the tube bundle support strips, which no longer meets the tube insertion requirements. In the prior art, under such circumstances, for transversely arranged tube bundle support strips, such as... Figure 8 As shown, an expansion rod with a diameter larger than the diameter D of the semicircular groove can be inserted between the two tube bundle support bars in advance to increase the distance L to meet the tube insertion requirements. This prior art has the following drawbacks:

[0006] (1) There are strict requirements for the expansion specifications of this expansion rod, namely, the diameter of the expansion rod shall not be greater than the gap L+1mm of the tube bundle support strip after shrinkage. Otherwise, if the expansion rod is inserted too tightly, it will cause slight scratches on the inner wall of the semi-circular groove 611 of the tube bundle support strip, which will bring the risk of damaging the tubes when the heat exchange tubes are inserted later.

[0007] (2) This expansion method requires personnel to apply external force to pry open the appropriate gap, which is very labor-intensive. Moreover, different gaps L require expansion rods of appropriate diameter. In cases where there are many deformation areas of the tube bundle support bar, it is necessary to prepare and use expansion rods of various models, which consumes a lot of time to carry out expansion operations and delays the construction period.

[0008] (3) There are also diagonally arranged tube bundle support structures, such as Figure 9 As shown, inflation levers cannot be used to prop up inflation in this situation, and there is currently no reasonable solution. Figure 9 The method shown uses an expansion rod in the prior art for manual prying and expansion, which makes it difficult to control the force and precision, and may cause the tube bundle support bar to twist and deform, affecting the working condition of the heat exchange tube.

[0009] Each waste heat exhaust heat exchanger has approximately 900 C-shaped heat exchange tubes. Each heat exchange tube must pass through multiple rows of horizontally and diagonally arranged tube bundle support bars to enter the tube holes of tube sheet 64. It can be seen that the amount of work involved in tube insertion is large and the adjustment is difficult, which brings certain obstacles to production progress and quality.

[0010] In summary, there is an urgent need for a device that can support the expansion of tube bundles with obliquely arranged structures and various gaps to assist in tube insertion. Summary of the Invention

[0011] To overcome the aforementioned problems, the inventors conducted in-depth research and designed a device and method for expanding obliquely arranged tube bundle support bars in a heat exchanger. This device includes an expansion pin, an expansion screw, a positioning groove plate, a nylon set screw, and a wing nut. The positioning groove plate fixes the expansion pin to the tube bundle support bar. By pre-tightening the wing nut, the expansion screw inside the expansion pin moves along the tapered hole section within the expansion pin, causing the front end of the expansion section to expand and widen the gap L between two adjacent tube bundle support bars. When the gap L between the two tube bundle support bars decreases after welding the tube bundle support bars to the toothed plate, the installation sequence of this device can be set according to the tube insertion sequence to expand the gap L between the tube bundle support bars. During the expansion process, the expansion pin does not rub against the semi-circular groove of the support bar, thus preventing scratches on the tube bundle support bar, thereby completing this invention.

[0012] Specifically, the purpose of this invention is to provide a support bar expansion device for obliquely arranged tube bundles in a heat exchanger, the device comprising an expansion pin 1, an expansion screw 2, a positioning groove plate 3, a nylon set screw 4, and a wing nut 5;

[0013] Wherein, after the expansion pin 1 passes through the positioning groove plate 3, the device is fixed between the two tube bundle support bars by the nylon top screw 4. The expansion screw 2 moves toward the inside of the expansion pin 1 through the wing nut 5, thereby causing the expansion pin 1 to expand outward, and thus expand the two tube bundle support bars.

[0014] The expansion pin 1 includes an expansion section and a handle 13, both of which are cylindrical. The outer diameter of the expansion section is equal to the outer diameter of the heat exchange tube; the outer diameter of the handle is larger than the outer diameter of the expansion section.

[0015] The side where the expansion section is located is the front, and the side where the means 13 is located is the rear. At the front end of the expansion section, a tapered hole section 11 coaxial with the expansion pin 1 is provided along the axial direction. From front to back, the inner diameter of the tapered hole section 11 gradually decreases. A through hole 14 penetrating the expansion pin 1 is provided at the rear of the tapered hole section 11.

[0016] A slotted groove 12 is provided at the junction of the tapered section 11 and the through hole 14, which penetrates the expansion pin 1 in the radial direction.

[0017] The expansion screw 2 includes a tapered head 21, a straight rod section 22, and a fine thread 23 connected in sequence.

[0018] The taper of the conical head 21 is the same as the taper of the conical hole section 11;

[0019] The outer diameter of the straight rod section 22 is smaller than the inner diameter of the through hole 14.

[0020] The expansion screw 1 is inserted into the expansion pin 1 from the front end, so that the fine thread 23 extends out from the through hole 14 of the handle 13 and can be screwed into the wing nut 5.

[0021] Preferably, when the wing nut 5 is pre-tightened, the tapered head 21 of the expansion screw 2 slides backward along the tapered hole section 11, squeezing the front end of the expansion section, so that the front end of the expansion section expands outward around the slit groove 12, and the single-sided expansion amount, that is, the radius expansion range, is less than 2mm.

[0022] When the wing nut 5 is loosened, the front end of the expansion section of the expansion pin 1 elastically deforms and rebounds, pushing the expansion screw 2 to reset, and the diameter of the front end of the expansion section also returns to be equal to the outer diameter of the heat exchange tube.

[0023] The positioning groove plate 3 is a C-shaped plate with a square groove 31 on the inner side. The two sides of the positioning groove plate 3 are provided with elongated oval holes 32 for the expansion screw 1 to be inserted. The middle part of the positioning groove plate 3 is provided with a set screw thread hole 33.

[0024] The square groove 31 can accommodate the tube bundle support bar.

[0025] The nylon set screw 4 is screwed through the set screw threaded hole 33 and then abuts against the tube bundle support bar, so that the expansion screw 1 and the nylon set screw 4 clamp the tube bundle support bar from both sides, thereby fixing the device to the tube bundle support bar.

[0026] The end of the nylon top wire 4 is a ball head surface 41, and the radius of the ball head surface 41 is the same as the radius of the semi-circular groove on the tube bundle support bar.

[0027] Among them, multiple tube bundle support bars 61 are arranged side by side to fix the heat exchange tube 63, and the heat exchange tube is a C-shaped heat exchange tube;

[0028] On one side of the tube bundle support bar, there are multiple inwardly recessed semi-circular grooves 611, into which the heat exchange tube is embedded.

[0029] The present invention also provides a method for inserting C-shaped heat exchange tubes into a heat exchanger. In this method, the C-shaped heat exchange tubes are inserted into and fixed to a support system composed of transversely arranged tube bundle support bars and obliquely arranged tube bundle support bars, and the distance between the tube bundle support bars 61 is fixed by expanding the obliquely arranged tube bundle support bar expansion device as described in claims 1 to 7.

[0030] The support system includes multiple tube bundle support bars 61. Toothed plates 62 are provided at both the upper and lower ends of the tube bundle support bars 61. The toothed plates 62 are elongated and have multiple notches on one side. Both ends of the tube bundle support bars 61 are embedded in the notches, and the tube bundle support bars 61 and the toothed plates 62 are welded and fixed together.

[0031] On one side of the tube bundle support bar, a plurality of inwardly recessed semi-circular grooves 611 are provided at intervals, and the heat exchange tube 63 is embedded in the semi-circular groove.

[0032] The method includes the following steps:

[0033] Step 1: When the gap between the two tube bundle support bars 61 is too small, causing the C-shaped heat exchange tube 63 to be unable to be inserted smoothly, the expansion device of the obliquely arranged tube bundle support bar of the heat exchanger is installed at the position where the gap is too small, and / or the expansion device is installed independently on the upper and lower sides of the position where the gap is too small.

[0034] Step 2: Adjust the spacing between the two tube bundle support bars 61 by using the expansion device for the diagonally arranged tube bundle support bars of the exchanger;

[0035] Step 3: Insert heat exchange tubes between the two tube bundle support bars 61. When all the semi-circular grooves 611 between the two tube bundle support bars 61, except for those with heat exchanger obliquely arranged tube bundle support bar expansion devices, insert heat exchange tubes, disassemble the heat exchanger obliquely arranged tube bundle support bar expansion devices, and then insert heat exchange tubes 63.

[0036] Step 4: Repeat steps 1 to 3 above to continue installing each subsequent heat exchange tube 63.

[0037] The beneficial effects of this invention include:

[0038] (1) According to the present invention, the device and method for expanding the support bars of the obliquely arranged tube bundle of the pressurized water reactor passive waste heat discharge heat exchanger can perform the expansion work between the support bars of the horizontally arranged tube bundle and the support bars of the obliquely arranged tube bundle, and solves the problem of the reduced spacing caused by the welding deformation of the support bars of the obliquely arranged tube bundle.

[0039] (2) According to the present invention, the expansion device and tube insertion method for the obliquely arranged tube bundle support bar of the pressurized water reactor passive waste heat discharge heat exchanger can be freely adjusted, is convenient and efficient to use, and saves the production of various specifications of expansion rods, thus saving manufacturing costs and a lot of testing time.

[0040] (3) According to the expansion device and tube insertion method of the obliquely arranged tube bundle support bar of the pressurized water reactor passive waste heat discharge heat exchanger provided by the present invention, nylon top screws are selected to pre-tighten the semi-circular groove of the tube bundle support bar. The material ensures the surface quality of the semi-circular groove of the tube bundle support bar after pre-tightening, and ensures that no scratches are caused during the contact and sliding process with the heat exchange tube. At the same time, when the expansion pin presses the tube bundle support bar, the two are relatively stationary, avoiding scratches on the semi-circular groove of the tube bundle support bar. For nuclear power nuclear-level products, the quality of the outer wall of the heat exchange tube is the key point to be ensured in manufacturing. Only through the above device and method can the convenience of tube insertion and the absence of scratches on the semi-circular groove be taken into account at the same time.

[0041] (4) The expansion device and tube insertion method for the obliquely arranged tube bundle support bar of the pressurized water reactor passive waste heat discharge heat exchanger provided by the present invention can not affect the tube insertion when the oblique arrangement position is limited by space. Moreover, the installation method is simple, the device manufacturing cost is low, it is easy to use, and the effect is significant. Attached Figure Description

[0042] Figure 1 This diagram shows the structure of the pressurized water reactor passive waste heat removal heat exchanger with obliquely arranged tube bundle support bar expansion device installed between the tube bundle support bars.

[0043] Figure 2 Show Figure 1 Schematic diagram of the AA section, i.e., the structural diagram of the tube bundle support bars arranged obliquely with expansion;

[0044] Figure 3 The diagram shows the front view and BB cross-sectional view of the expansion pin of the obliquely arranged tube bundle support bar expansion device of the passive waste heat removal heat exchanger of the pressurized water reactor of the present invention;

[0045] Figure 4 This diagram shows the expansion screw structure of the obliquely arranged tube bundle support bar expansion device for the passive waste heat removal heat exchanger of the pressurized water reactor according to the present invention;

[0046] Figure 5 This invention shows a front view and a CC sectional view of the positioning groove plate of the obliquely arranged tube bundle support bar expansion device for the passive waste heat removal heat exchanger of the pressurized water reactor.

[0047] Figure 6 This diagram shows a schematic of the nylon top wire structure of the obliquely arranged tube bundle support bar expansion device for the passive waste heat removal heat exchanger of the pressurized water reactor according to the present invention;

[0048] Figure 7 A schematic diagram of the C-shaped heat exchange tubes of a passive waste heat removal heat exchanger is shown when the tubes are inserted.

[0049] Figure 8 This diagram illustrates the structure of the expansion pins in the prior art when they expand and laterally arrange the tube bundle support bars.

[0050] Figure 9 This diagram illustrates the structure of the prior art when the expansion pins are used to expand the obliquely arranged tube bundle support bars.

[0051] Explanation of icon numbers:

[0052] 1-Expansion Selling

[0053] 11-Conical section

[0054] 12-Crack Groove

[0055] 13-The means

[0056] 14-Through Hole

[0057] 2-Expansion Screw

[0058] 21-Conical head

[0059] 22-Straight rod section

[0060] 23- Fine thread

[0061] 3-Positioning groove plate

[0062] 31-Square Groove

[0063] 32-Octagonal hole

[0064] 33-Set screw threaded hole

[0065] 4-Nylon set screw

[0066] 5-Wing Nut

[0067] 61-Tube bundle support bar

[0068] 611-Semicircular Groove

[0069] 62-toothed plate

[0070] 63-Heat exchanger tube

[0071] 64-Tube Sheet

[0072] D - Diameter of the semicircular groove

[0073] d - heat exchange tube diameter

[0074] L - Distance between tube bundle support bars Detailed Implementation

[0075] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Through these descriptions, the features and advantages of the present invention will become clearer and more apparent.

[0076] The term “exemplary” as used herein means “serving as an example, embodiment, or illustration.” Any embodiment illustrated herein as “exemplary” is not necessarily to be construed as superior to or better than other embodiments. Although various aspects of embodiments are shown in the accompanying drawings, the drawings are not necessarily drawn to scale unless specifically indicated otherwise.

[0077] This application provides a support bar expansion device for obliquely arranged tube bundles in a passive waste heat removal heat exchanger of a pressurized water reactor, such as... Figure 1 and Figure 2 As shown, the device includes an expansion pin 1, an expansion screw 2, a positioning groove plate 3, a nylon set screw 4, and a wing nut 5;

[0078] Wherein, after the expansion pin 1 passes through the positioning groove plate 3, the device is fixed between the two tube bundle support bars by the nylon top screw 4. The expansion screw 2 moves toward the inside of the expansion pin 1 through the wing nut 5, thereby causing the expansion pin 1 to expand outward, and thus expand the two tube bundle support bars.

[0079] In a preferred embodiment, such as Figure 3 As shown, the expansion pin 1 includes an expansion section and a handle 13, both of which are cylindrical. The outer diameter of the expansion section is equal to the outer diameter of the heat exchange tube; the outer diameter of the handle is larger than the outer diameter of the expansion section; the expansion section can pass through the elongated hole 32, while the handle cannot.

[0080] The side where the expansion section is located is the front, and the side where the means 13 is located is the rear. At the front end of the expansion section, a tapered hole section 11 coaxial with the expansion pin 1 is provided along the axial direction. From front to back, the inner diameter of the tapered hole section 11 gradually decreases. A through hole 14 penetrating the expansion pin 1 is provided at the rear of the tapered hole section 11.

[0081] A slit groove 12 is provided at the junction of the tapered section 11 and the through hole 14, extending radially through the expansion pin 1. The size of the slit groove 12 is larger than the diameter of the through hole. By providing this slit groove 12, the connection size and strength of the expansion pin 1 at this position are reduced, allowing it to deform and bend appropriately.

[0082] In a preferred embodiment, such as Figure 4 As shown, the expansion screw 2 includes a tapered head 21, a straight rod section 22, and a fine thread 23 connected in sequence;

[0083] The taper of the conical head 21 is the same as the taper of the conical hole section 11;

[0084] The outer diameter of the straight rod segment 22 is smaller than the inner diameter of the through hole 14, and the straight rod segment 22 can move easily within the through hole 14.

[0085] The purpose of selecting fine thread 23 is to increase the adjustment accuracy, that is, the feed amount of tapered head 21 is smaller each time the wing nut is turned, which not only makes the resistance on the wing nut relatively small, but also improves the expansion accuracy.

[0086] In a preferred embodiment, the expansion screw 1 is inserted into the expansion pin 1 from the front end, so that the fine thread 23 extends out from the through hole 14 of the handle 13 and can be screwed into the wing nut 5.

[0087] Preferably, when the wing nut 5 is pre-tightened, the tapered head 21 of the expansion screw 2 slides backward along the tapered hole section 11, squeezing the front end of the expansion section, so that the front end of the expansion section expands outward around the slit groove 12, and the single-sided expansion amount, that is, the radius expansion range, is less than 2mm.

[0088] When the wing nut 5 is loosened, the front end of the expansion section of the expansion pin 1 elastically deforms and rebounds, pushing the expansion screw 2 to reset, and the diameter of the front end of the expansion section also returns to be equal to the outer diameter of the heat exchange tube.

[0089] In a preferred embodiment, the positioning groove plate 3 is a C-shaped plate with a square groove 31 on its inner side, such as... Figure 5 As shown, the positioning groove plate 3 has elongated oval holes 32 on both sides for the expansion screw 1 to be inserted, and a set screw threaded hole 33 in the middle of the positioning groove plate 3; that is, after the expansion screw 1 is inserted into the elongated oval hole 32, it can still move back and forth a certain distance in the horizontal direction, so as to cooperate with the installation, fixing and expansion operation of the nylon set screw.

[0090] Preferably, the square groove 31 can accommodate the tube bundle support bar so that the expansion device can cover the tube bundle support bar; preferably, the nylon set screw 4 is screwed through the set screw thread hole 33 and then abuts against the tube bundle support bar, so that the expansion screw 1 and the nylon set screw 4 clamp the tube bundle support bar from both sides, thereby fixing the device to the tube bundle support bar.

[0091] In a preferred embodiment, such as Figure 6As shown, the end of the nylon set wire 4 is a spherical surface 41, the radius of which is consistent with the radius of the semi-circular groove on the tube bundle support bar. In this application, nylon is chosen because it has a certain hardness and strength. When the spherical surface at the end is pre-tightened and rests within the semi-circular groove 611 of the tube bundle support bar, it will not damage the surface and will not contaminate the stainless steel material. The tube bundle support bar is made of stainless steel. Although commonly used metals such as copper and aluminum in nuclear power manufacturing have lower hardness than stainless steel, they all corrode stainless steel and cannot be in direct contact. Nylon is a commonly used non-metallic, non-contaminating, hard material.

[0092] In a preferred embodiment, multiple tube bundle support bars 61 are arranged side by side to fix the heat exchange tube 63, and the heat exchange tube is a C-shaped heat exchange tube;

[0093] On one side of the tube bundle support bar, there are multiple inwardly recessed semi-circular grooves 611, into which the heat exchange tube is embedded.

[0094] The present invention also provides a method for inserting C-shaped heat exchange tubes into a heat exchanger. In this method, the C-shaped heat exchange tubes are inserted into and fixed to a support system composed of transversely arranged tube bundle support bars and obliquely arranged tube bundle support bars. The distance between the tube bundle support bars 61 is fixed by the heat exchanger obliquely arranged tube bundle support bar expansion device described above, so that the distance meets the tube insertion requirements.

[0095] Preferably, the support system includes multiple tube bundle support bars 61, and toothed plates 62 are provided at both the upper and lower ends of the tube bundle support bars 61. The toothed plates 62 are elongated and have multiple notches on one side. Both ends of the tube bundle support bars 61 are embedded in the notches, and the tube bundle support bars 61 and the toothed plates 62 are welded and fixed together.

[0096] On one side of the tube bundle support bar, a plurality of inwardly recessed semi-circular grooves 611 are provided at intervals, and the heat exchange tube 63 is embedded in the semi-circular groove.

[0097] In a preferred embodiment, the waste heat removal heat exchanger of the "Guohe-1" demonstration project is a new type of pressurized water reactor nuclear power unit developed and improved based on the AP1000 pressurized water reactor nuclear power technology. Its tube bundle assembly contains 897 C-shaped heat exchange tubes with an outer diameter of 19.25 mm. The theoretical diameter of the semi-circular groove of the tube bundle support bar is 19.35 mm, and the theoretical distance L between every two tube bundle support bars is 12.7 mm. The heat exchange tubes need to be installed row by row from the inside out and from bottom to top. Each tube heat exchange tube passes through a set of oblique and a set of transversely arranged tube bundle support bars on both sides, as shown below. Figure 7As shown, after welding the tube bundle support strip to the toothed plate, the minimum installation gap L of each row of heat pipes was measured to be 11.3 mm. That is, the minimum gap position of the support strip corresponds to the diameter D of the heat exchanger tube mounting hole of 17.95 mm, which is reduced by 1.4 mm.

[0098] The following steps shall be performed for the pipe insertion work of this device:

[0099] Step 1: When the gap between the two tube bundle support bars 61 is too small, causing the C-shaped heat exchange tube 63 to be unable to pass through smoothly, the expansion device of the obliquely arranged tube bundle support bar of the heat exchanger is installed at the position where the gap is too small, and / or the expansion device is installed independently on the upper and lower sides of the position where the gap is too small, that is, the expansion device in this application is installed column by column for each tube bundle support bar that does not meet the tube passage gap.

[0100] Preferably, in step 1, installing the expansion device for the obliquely arranged tube bundle support of the heat exchanger specifically includes the following sub-steps:

[0101] Sub-step 1-1: Select an expansion pin 1 with an outer diameter D of 19.25mm according to the product tube hole specifications; insert the expansion screw 2 into the expansion pin 1 and screw the wing nut 5 into the fine thread 23 of the expansion screw 2;

[0102] Sub-steps 1-2: Attach the positioning slot plate 3 to the heat exchange tube support bar 61, insert the expansion pin 1 into the elongated holes on both sides, and insert the expansion pin 1 into the semi-circular groove 611 of the adjacent tube bundle support bar 61.

[0103] In sub-steps 1-3, nylon set screw 4 is screwed into the set screw threaded hole 33 of the positioning groove plate 3 and pre-tightened so that the ball head surface 41 abuts against the semi-circular groove 611 of the tube bundle support bar; at this time, the positioning groove plate 3 presses the expansion pin 1 against the back side of the support bar 61 and fixes it to it.

[0104] Step 2: Adjust the spacing between the two tube bundle support bars 61 by using the expansion device for the diagonally arranged tube bundle support bars of the exchanger;

[0105] Preferably, step 2 specifically includes the following process:

[0106] Sub-step 2-1: Hold the handle 13 of the expansion pin 1 and rotate the expansion pin 1 so that the groove 1 rotates upward;

[0107] In sub-step 2-2, adjust the wing nut 5 to expand the front end of the expansion section of the expansion pin 1. The torsional torque of the wing nut 5 should be below 8 Nm. Expand the distance between the two tube bundle support bars 61 to ensure that adjacent heat exchange tubes 63 can be smoothly inserted. The expansion width should meet the minimum spacing L of the support bars ≥ 12.7 mm, and the expansion amount on one side should be below 2 mm. Since the expansion pin 1 and the support bar 61 are relatively stationary during expansion, there will be no scratching on their semi-circular grooves 611. The surface quality of the support bars is good after expansion. If the support bars deform significantly in a local position, this device can be added to assist in expansion at that position to ensure that the spacing at each position of the entire row meets the requirements for the introduction of heat exchange tubes.

[0108] Step 3: Insert heat exchange tubes between the two tube bundle support bars 61. When all the semi-circular grooves 611 between the two tube bundle support bars 61, except for those with heat exchanger obliquely arranged tube bundle support bar expansion devices, insert heat exchange tubes, disassemble the heat exchanger obliquely arranged tube bundle support bar expansion devices, and then insert heat exchange tubes 63.

[0109] Preferably, in step 3, during the disassembly of the expansion device for the obliquely arranged tube bundle support bars of the heat exchanger, the wing nuts 5 and nylon set screws 4 are loosened one by one, and the device is carefully removed to ensure that the heat exchange tubes are not scratched throughout the process. At this time, the tube bundle support bars 61 are expanded by the introduced C-shaped heat exchange tubes 63 and no longer bend; at this time, the distance L between the two tube bundle support bars meets the tube insertion requirements, and the heat exchange tube insertion process is smooth and without resistance.

[0110] Step 4: Repeat steps 1 to 3 above to continue installing each subsequent heat exchange tube 63.

[0111] The expansion device and corresponding tube insertion method of this application were used to complete the tube insertion of the above-mentioned 897 C-shaped heat exchange tubes. The results were good, with no damage or scratches on any of the heat exchange tubes. The efficiency was high, with all tube insertion and installation work completed in just three days.

[0112] The present invention has been described above with reference to preferred embodiments; however, these embodiments are merely exemplary and illustrative. Various substitutions and modifications can be made to the present invention based on these embodiments, all of which fall within the scope of protection of the present invention.

Claims

1. A support bar expansion device for obliquely arranged tube bundles in a passive waste heat removal heat exchanger of a pressurized water reactor, characterized in that, The expansion device includes an expansion pin (1), an expansion screw (2), a positioning groove plate (3), a nylon set screw (4), and a wing nut (5); Wherein, after the expansion pin (1) passes through the positioning groove plate (3), the expansion pin (1) is fixed between the two tube bundle support bars by the nylon set screw (4). The expansion screw (2) is driven to move toward the inside of the expansion pin (1) by the wing nut (5), so that the expansion pin (1) expands outward, thereby expanding the two tube bundle support bars; The expansion pin (1) includes an expansion section and a handle (13) that are both cylindrical. The outer diameter of the expansion section is equal to the outer diameter of the heat exchange tube. The outer diameter of the handle is greater than the outer diameter of the expansion section. The side where the expansion section is located is the front, and the side where the means (13) is located is the rear. At the front end of the expansion section, a tapered hole section (11) coaxial with the expansion pin (1) is provided along the axial direction. From front to back, the inner diameter of the tapered hole section (11) gradually decreases. A through hole (14) penetrating the expansion pin (1) is provided at the rear of the tapered hole section (11). A slot (12) is provided at the junction of the tapered section (11) and the through hole (14) to penetrate the expansion pin (1) in the radial direction. The expansion screw (2) includes a tapered head (21), a straight rod section (22), and a fine thread (23) connected in sequence. The taper of the conical head (21) is the same as the taper of the conical hole section (11); The outer diameter of the straight rod section (22) is smaller than the inner diameter of the through hole (14); The positioning slot plate (3) is a C-shaped plate with a square groove (31) on the inner side. The two sides of the positioning slot plate (3) are provided with elongated oval holes (32) for inserting expansion pins (1). The middle part of the positioning slot plate (3) is provided with a set screw thread hole (33). The square groove (31) can accommodate the tube bundle support bar; The nylon set screw (4) is screwed through the set screw thread hole (33) and then abuts against the tube bundle support bar, so that the expansion pin (1) and the nylon set screw (4) clamp the tube bundle support bar from both sides, thereby fixing the expansion device to the tube bundle support bar; The end of the nylon top wire (4) is a ball head surface (41), and the radius of the ball head surface (41) is consistent with the radius of the semi-circular groove on the tube bundle support bar.

2. The expansion device for the obliquely arranged tube bundle support bars of the passive waste heat removal heat exchanger of a pressurized water reactor according to claim 1, characterized in that, The expansion screw (2) is inserted into the expansion pin (1) from the front end, so that the fine thread (23) extends out from the through hole (14) of the handle (13) and can be screwed into the wing nut (5); When the wing nut (5) is pre-tightened, the tapered head (21) of the expansion screw (2) slides backward along the tapered hole section (11), squeezing the front end of the expansion section, so that the front end of the expansion section expands outward around the crack groove (12), and the single-sided expansion amount, that is, the radius expansion range is less than 2mm; When the wing nut (5) is loosened, the front end of the expansion section of the expansion pin (1) elastically deforms and rebounds, pushing the expansion screw (2) to reset, and the diameter of the front end of the expansion section also returns to be equal to the outer diameter of the heat exchange tube.

3. The expansion device for the obliquely arranged tube bundle support bars of the passive waste heat removal heat exchanger of a pressurized water reactor according to claim 1, characterized in that, Multiple tube bundle support bars (61) are arranged side by side to fix the heat exchange tube (63), and the heat exchange tube is a C-shaped heat exchange tube; On one side of the tube bundle support bar, a plurality of inwardly recessed semi-circular grooves (611) are provided at intervals, and the heat exchange tubes are embedded in the semi-circular grooves.

4. A method for installing C-shaped heat exchanger tubes in a passive waste heat removal heat exchanger for a pressurized water reactor, characterized in that... In this method, C-shaped heat exchange tubes are inserted and fixed into a support system consisting of transversely arranged tube bundle support bars and obliquely arranged tube bundle support bars, and the distance between the two tube bundle support bars (61) is expanded by the obliquely arranged tube bundle support bar expansion device of the pressurized water reactor passive waste heat discharge heat exchanger as described in any one of claims 1 to 3.

5. The method for installing C-shaped heat exchange tubes in a passive waste heat removal heat exchanger for a pressurized water reactor according to claim 4, characterized in that, The support system includes multiple tube bundle support bars (61), and toothed plates (62) are provided at both the upper and lower ends of the tube bundle support bars (61). The toothed plates (62) are long strips with multiple notches on one side. Both ends of the tube bundle support bars (61) are embedded in the notches, and the tube bundle support bars (61) and the toothed plates (62) are welded and fixed together. On one side of the tube bundle support bar, there are multiple inwardly recessed semi-circular grooves (611) spaced apart, and the heat exchange tube (63) is embedded in the semi-circular groove.

6. The method for inserting C-shaped heat exchange tubes in a passive waste heat removal heat exchanger for a pressurized water reactor according to claim 4, characterized in that, The method includes the following steps: Step 1: When the spacing between the two tube bundle support bars (61) is too small, causing the C-shaped heat exchange tube (63) to be unable to be smoothly inserted, the expansion device is installed at the position where the spacing is too small, and / or the expansion device is installed independently on the upper and lower sides of the position where the spacing is too small. Step 2: Adjust the spacing between the two tube bundle support bars (61) using the expansion device; Step 3: Insert heat exchange tubes between the two tube bundle support bars (61). When heat exchange tubes are inserted into the semi-circular groove (611) between the two tube bundle support bars (61), except for those with expansion devices, remove the expansion devices and then insert heat exchange tubes (63). Step 4: Repeat steps 1 to 3 above to continue installing each subsequent heat exchange tube (63).

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