An inner lining elbow structure for preventing thermal fatigue

Abstract

A structure of a lined elbow for preventing thermal fatigue provided by the present invention includes a lining in an arc-shaped plate structure, the lining is arranged at the upstream end of the outer arc inner wall of the elbow cylinder, and a spacing is provided between the outer arc surface of the lining and the inner arc surface of the elbow cylinder; this structure avoids thermal fatigue damage to the outer arc of the elbow, prolongs the service life of the pipeline, improves the safety and reliability of the pipeline, and reduces the maintenance cost; at the same time, it ensures the stability and safety of the structure.

Description

Technical Field

[0001] The present invention belongs to the field of pipeline structure design, and particularly relates to a lining elbow structure for preventing thermal fatigue. Background Art

[0002] For steam-water pipelines such as thermal power and nuclear power, in order to avoid over-temperature damage to equipment by internal fluids, spray desuperheaters are usually installed on the pipelines. When the steam temperature in the pipeline exceeds the set value, the spray desuperheater will start and spray water with a relatively low temperature into the pipeline to reduce the temperature of the fluid in the pipeline. Behind the spray desuperheaters of steam-water pipelines such as thermal power and nuclear power, elbows are inevitably installed to change the flow direction of steam. Due to limited on-site space, elbows are often arranged at positions not far from the spray desuperheaters. During the maintenance process, it is often found that there are a large number of turtle cracks on the inner wall of the outer arc of such elbows, showing typical characteristics of thermal fatigue cracks. The reason for the cracks is that the desuperheating water sprayed by the spray desuperheater when it starts impacts the inner wall of the outer arc of the downstream elbow. Frequent startup of the spray desuperheater will cause frequent temperature fluctuations on the inner wall of the outer arc of the downstream elbow, resulting in thermal fatigue and cracks. Under the current power situation, frequent peak shaving of units will further exacerbate the above thermal fatigue phenomena of each unit.

[0003] However, such cracks are located on the inner wall surface and are small in size, making it very difficult to distinguish them through conventional ultrasonic non-destructive testing. In addition, due to the small size of the cracks, it is also difficult to determine them through endoscopic observation. Usually, during the maintenance of power plants, after cutting the pipe, magnetic particle or penetrant testing is performed on the inner wall of the outer arc of the elbow to determine whether there are fatigue cracks. This brings great difficulties to the maintenance work of the units. If such defects are not discovered and processed in time, the fatigue cracks will connect and expand with each other, ultimately leading to the bursting of the elbow pipe, posing great potential safety hazards and economic losses to the operation of the units. Summary of the Invention

[0004] The purpose of the present invention is to provide a lining elbow structure for preventing thermal fatigue, which solves the above-mentioned deficiencies in the prior art.

[0005] In order to achieve the above purpose, the technical solution adopted by the present invention is:

[0006] A lining elbow structure for preventing thermal fatigue provided by the present invention includes a lining in the shape of an arc-shaped plate, the lining is arranged at the upstream end of the inner wall of the outer arc of the elbow cylinder, and a spacing is provided between the outer arc surface of the lining and the inner arc surface of the elbow cylinder.

[0007] Preferably, the lining and the upstream end of the elbow cylinder are fixedly connected through a fixing structure.

[0008] Preferably, the fixing structure includes a lower fixing seat and an upper fixing seat. Among them, there are multiple lower fixing seats, and the multiple lower fixing seats are evenly distributed along the circumferential direction of the inner lining. The upper fixing seat corresponds to the lower fixing seat one by one. The lower fixing seat is fixed on the inner wall of the elbow cylinder body. The upper fixing seat is installed at the inner arc surface of the inner lining. The lower fixing seat and the upper fixing seat are fixedly connected.

[0009] Preferably, the lower fixing seat and the upper fixing seat are fixedly connected by a pin.

[0010] Preferably, a support structure for limiting and supporting the inner lining is further provided between the inner lining and the elbow cylinder body.

[0011] Preferably, the support structure includes two groups of support bodies for supporting and limiting the inner lining, and the two groups of support bodies are respectively arranged in the middle and the downstream end of the inner lining.

[0012] Preferably, each group of support bodies includes multiple fixing seats and support pins. Among them, the multiple fixing seats are evenly distributed along the circumferential direction of the inner lining. The fixing seats are fixed on the inner arc surface of the inner lining, and the support pins pass through the fixing seats and the inner lining and contact the inner wall of the elbow cylinder body.

[0013] Preferably, a stop structure for limiting the inner lining is further provided at the downstream end of the elbow cylinder body.

[0014] Preferably, the stop structure includes multiple stop blocks, and the multiple stop blocks are evenly distributed along the circumferential direction of the elbow cylinder body.

[0015] Preferably, the height of the stop block is greater than the distance between the outer arc surface of the inner lining and the inner arc surface of the outer pipe cylinder body.

[0016] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0017] A lining elbow structure for preventing thermal fatigue provided by the present invention installs a protective lining on the inner wall of the outer arc of a conventional elbow structure. One end (the upstream of the working medium flow direction) of the inner lining is fixedly connected to the inner wall of the outer arc of the elbow, and the middle and the other end (the downstream of the working medium flow direction) are in contact with the inner wall of the outer arc of the elbow through support pins (not fixedly connected). Among them: when the desuperheating water is sprayed by the desuperheater, the desuperheating water impacts the inner lining of the elbow instead of the inner surface of the outer arc of the elbow, avoiding thermal fatigue damage to the outer arc of the elbow, extending the service life of the pipeline, improving the safety and reliability of the pipeline, and reducing the maintenance cost. At the same time, one end (the upstream end of the steam flow direction) of the inner lining is fixedly connected, and the middle and the end (the downstream end of the steam flow direction) are not fixedly connected, ensuring the free expansion of the inner lining along the steam flow direction and ensuring the stability and safety of the structure. Description of the Drawings

[0018] Figure 1 It is a schematic diagram of the lining elbow structure;

[0019] Figure 2 It is a schematic diagram of the inner lining structure;

[0020] Figure 3 It is a cross-sectional view at the position of the fixing structure;

[0021] Figure 4 It is a cross-sectional view at the position of the support structure;

[0022] Figure 5 It is a cross-sectional view at the position of the stop structure;

[0023] Among them, 1. Elbow cylinder; 2. Inner lining; 3. Lower fixing seat; 4. Upper fixing seat; 5. Fixing pin; 6. Fixing seat; 7. Support pin; 8. Stop block; 9. Relief hole; 10. Working medium flow direction; 11. Pin hole. Specific implementation mode

[0024] The following will describe the implementation mode of the present invention in detail with reference to the accompanying drawings, but these descriptions are only exemplary and are not intended to limit the protection scope of the present invention in any way.

[0025] As Figure 1 shown, an inner lining elbow structure for preventing thermal fatigue provided by the present invention includes an elbow cylinder 1, an inner lining 2, a fixing structure, a support structure and a stop structure. Among them, the inner lining 2 is arranged on the inner wall of the elbow cylinder 1 and is fixedly connected through the fixing structure.

[0026] A support structure is arranged between the inner lining 2 and the elbow cylinder 1 to realize a spacing between the inner lining 2 and the elbow cylinder 1.

[0027] The inner lining 2 is arranged at the inner wall of the outer arc of the elbow cylinder 1 and is located at the upstream end of the steam flow direction.

[0028] The fixing structure is installed at the upstream end of the inner lining 2.

[0029] The support structure is installed at the middle section and the downstream end of the inner lining 2.

[0030] The inner lining 2 is an arc-shaped plate structure.

[0031] The fixing structure includes a lower fixing seat 3, an upper fixing seat 4 and a fixing pin 5. Among them, a plurality of lower fixing seats 3 are provided, and the plurality of lower fixing seats 3 are evenly distributed along the circumferential direction of the inner lining 2, and the upper fixing seat 4 corresponds to the lower fixing seat 3 one by one.

[0032] The lower fixing seat 3 is fixed on the inner wall of the elbow cylinder 1; the upper fixing seat 4 is installed on the inner arc surface of the inner lining 2; the lower fixing seat 3 and the upper fixing seat 4 are connected by a pin 5.

[0033] The support structure includes two groups of supports, which are respectively arranged in the middle and the downstream end of the inner liner 2.

[0034] Each group of supports includes a plurality of fixing seats 6 and support pins 7. Among them, the plurality of fixing seats 6 are evenly distributed along the circumferential direction of the inner liner 3; the fixing seats 6 are fixed on the inner arc surface of the inner liner 2, and the support pins 7 pass through the fixing seats 6 and the inner liner 2 and are in contact with the inner wall of the elbow cylinder body 1.

[0035] A stop structure for limiting the inner liner 2 is further provided at the downstream end of the elbow cylinder body 1. The stop structure is used to prevent the inner liner 2 from slipping off after the connection with the elbow cylinder body 1 fails and separates.

[0036] The stop structure includes a plurality of stop blocks 8, and the plurality of stop blocks 8 are evenly distributed along the circumferential direction of the elbow cylinder body 1.

[0037] The height of the stop block 8 is greater than the distance between the outer arc surface of the inner liner 2 and the inner arc surface of the outer pipe cylinder body 1.

[0038] Embodiment

[0039] As Figure 2 shown, for the inner liner elbow structure for preventing thermal fatigue provided by the present invention, a plurality of relief holes 9 are evenly distributed along the circumferential direction at the upstream end of the inner liner 2, which facilitates the installation and connection of the structure.

[0040] In addition, a pin hole 11 is machined on the inner liner 2, and the support pin 7 passes through it and is connected to the support structure mounting seat.

[0041] As Figure 3 shown, the fixing structure of the present invention fixedly connects the inner liner 2 and the cylinder body 1. The fixing structures are evenly distributed and play a fixing role. The lower surface of the lower fixing seat 3 of the fixing structure is connected to the inner wall of the cylinder body 1, the lower surface of the upper fixing seat 4 is connected to the inner arc surface of the inner liner 2, there is a through hole on the upper fixing seat 4, the fixing pin 5 passes through the through hole and is connected to the upper fixing seat 4, and the other end of the fixing pin 5 is connected to the lower fixing seat 3. The above connection methods are all welding, and the fixing seats and the cylinder body 1 and the inner liner 2 are fixedly connected in a non-full welding form.

[0042] As Figure 4 shown, the support structure of the present invention supports the inner liner 2 on the inner wall of the outer arc of the elbow cylinder body 1 through the support pin 7. The fixing seat 6 of the support structure is connected to the inner liner 2, and the support pin 7 passes through the pin hole 11 on the inner liner 2 and is connected to the support seat 6. The above connection method is evenly welded, and the connection between the fixing seat 6 of the support structure and the inner liner is in a non-full welding form connection. The other end of the support pin 7 is in contact with the inner wall of the elbow cylinder body 1 (non-fixed connection).

[0043] As Figure 5As shown in the figure, the stop structure of the present invention is connected to the inner wall of the cylinder 1 through the stop block 8. The stop block 8 is located on the end side of the inner liner 2 (the downstream side in the steam flow direction) and has a certain distance from the inner liner 2 to ensure the free expansion of the inner liner 2.

[0044] The working process of the present invention:

[0045] The structure of the present invention is installed on the downstream side of the spray desuperheater along the steam flow direction. When the spray desuperheater works, spray desuperheating water to reduce the steam temperature. When the low-temperature steam flows downstream to the elbow position, it impacts on the inner liner of the structure. The inner wall of the outer arc of the elbow does not directly contact the low-temperature steam, avoiding thermal fatigue failure at this position. The inner liner is fixed at one end of the elbow (the upstream end in the steam flow direction), and the middle and end of the inner liner are supported on the cylinder through support pins, ensuring the free expansion of the inner liner along the steam flow direction.

Claims

1. An inner lining elbow structure for preventing thermal fatigue, characterized in that, It includes a lining (2) in the shape of an arc-shaped plate structure. The lining (2) is arranged at the upstream end of the inner wall of the outer arc of the elbow cylinder body (1), and there is a spacing between the outer arc surface of the lining (2) and the inner arc surface of the elbow cylinder body (1). The lining (2) and the upstream end of the elbow cylinder body (1) are fixedly connected through a fixing structure. The fixing structure includes a lower fixing seat (3) and an upper fixing seat (4). Among them, a plurality of lower fixing seats (3) are provided, and the plurality of lower fixing seats (3) are evenly distributed along the circumferential direction of the lining (2). The upper fixing seat (4) corresponds to the lower fixing seat (3) one by one. The lower fixing seat (3) is fixed on the inner wall of the elbow cylinder body (1). The upper fixing seat (4) is installed at the inner arc surface of the lining (2). The lower fixing seat (3) and the upper fixing seat (4) are fixedly connected. A support structure for limiting and supporting the lining (2) is also provided between the lining (2) and the elbow cylinder body (1). The support structure includes two groups of support bodies for supporting and limiting the lining (2), and the two groups of support bodies are respectively arranged in the middle and the downstream end of the lining (2). Each group of support bodies includes a plurality of fixing seats (6) and support pins (7). Among them, the plurality of fixing seats (6) are evenly distributed along the circumferential direction of the lining (2). The fixing seat (6) is fixed on the inner arc surface of the lining (2), and the support pin (7) passes through the fixing seat (6) and the lining (2) and contacts the inner wall of the elbow cylinder body (1).

2. The inner liner elbow structure for preventing thermal fatigue according to claim 1, wherein, The lower fixing seat (3) and the upper fixing seat (4) are fixedly connected through a pin (5).

3. A lining elbow structure for preventing thermal fatigue according to claim 1, characterized in that, A stop structure for limiting the lining (2) is also provided at the downstream end of the elbow cylinder body (1).

4. A structure of a lined elbow for preventing thermal fatigue according to claim 3, characterized in that, The stop structure includes a plurality of stop blocks (8), and the plurality of stop blocks (8) are evenly distributed along the circumferential direction of the elbow cylinder body (1).

5. A lining elbow structure for preventing thermal fatigue according to claim 4, characterized in that, The height of the stop block (8) is greater than the spacing between the outer arc surface of the lining (2) and the inner arc surface of the elbow cylinder body (1).

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