A full-closed built-in blind plate device for preventing high-temperature flue gas leakage

Abstract

The application discloses a full-closed built-in blind plate device for preventing high-temperature flue gas leakage in the technical field of waste heat boilers, which comprises a high-temperature flue, an installation box capable of communicating with the high-temperature flue is arranged above the high-temperature flue, and the installation box is connected with the high-temperature flue through a fixing mechanism; a sealing gasket is arranged between the high-temperature flue and the installation box; a blind plate is slidably connected to the installation box in the vertical direction, a sealing assembly is arranged below the blind plate, and a driving mechanism for driving the blind plate to move in the vertical direction is arranged at the side of the blind plate; and the application can better prevent the leakage of high-temperature flue gas.

Description

Technical Field

[0001] This invention relates to the field of waste heat boiler technology, specifically to a fully enclosed built-in blind flange device for preventing high-temperature flue gas leakage. Background Technology

[0002] The blind flange is located between the bypass tee damper and the waste heat boiler (HRSG). When the power plant is in single-cycle mode for a long time or the waste heat boiler needs to be overhauled, the blind flange body stored outside the flue needs to be inserted into the blind flange flue to isolate the tee flue damper from the waste heat boiler, providing secondary protection for the waste heat boiler equipment or maintenance personnel.

[0003] In existing blind-plate combined circulation or short-term single circulation systems, the blind plates are stored on the external steel frame of the high-temperature flue. During long-term single circulation or maintenance of the waste heat boiler, the flue cover is opened, and the blind plate is lowered and inserted into the flue via an electric actuator or electric hoist before the flue cover is closed. Conversely, when combined circulation is required, the flue cover is opened, the blind plate is lifted using an electric actuator or electric hoist, stored on the external steel frame, and then the flue cover is closed.

[0004] The existing blind flange requires manual opening and closing of the flue cover before and after lifting. Before opening, a ring of bolts needs to be manually removed, and then the cover is rotated using an electric or manual winch. After closing, a ring of bolts and flange sealing gaskets also need to be manually installed and tightened. The operation of the blind flange cover is done manually or semi-automatically, which is time-consuming and labor-intensive. Frequent tightening of the cover flange can easily lead to loosening, requiring frequent replacement to prevent high-temperature flue gas leakage.

[0005] Based on this, the present invention designs a fully enclosed built-in blind flange device to prevent high-temperature flue gas leakage, so as to solve the above problems. Summary of the Invention

[0006] The purpose of this invention is to provide a fully enclosed built-in blind flange device for preventing high-temperature flue gas leakage, so as to solve the problems mentioned in the background art.

[0007] To achieve the above objectives, the present invention provides the following technical solution: a fully enclosed built-in blind flange device for preventing high-temperature flue gas leakage, comprising a high-temperature flue, an installation box that can communicate with the high-temperature flue is provided above the high-temperature flue, the installation box and the high-temperature flue are connected by a fixing mechanism; a sealing gasket is provided between the high-temperature flue and the installation box; a blind flange is slidably connected to the installation box in the vertical direction, a sealing component is provided below the blind flange, and a driving mechanism for driving its movement in the vertical direction is provided on the side of the blind flange.

[0008] As a further embodiment of the present invention, the sealing assembly includes a sealing plate, which is rotatably mounted inside the high-temperature flue and located directly below the blind plate. A torsion spring for resetting is fitted on the rotating shaft of the sealing plate.

[0009] As a further embodiment of the present invention, the fixing mechanism includes a fixing plate, which is fixedly installed on the outer wall of the high-temperature flue. The fixing plate has a first sliding groove, which is composed of a horizontal groove and two vertical grooves. The two vertical grooves are respectively connected to one end and the middle of the horizontal groove. A first locking block is provided in each of the two vertical grooves. The first locking block is wedge-shaped and is elastically slidably connected to the fixing plate. A first guide post is slidably connected in the first sliding groove and is fixedly connected to the mounting box.

[0010] As a further embodiment of the present invention, the first locking block is slidably connected to a first slider in the vertical direction. The first slider is slidably connected to a fixed plate. A first spring for resetting is fixedly connected to the first slider. A second sliding groove is provided on the fixed plate. The second sliding groove is L-shaped and one side of the second sliding groove is inclined. A second guide post is slidably connected in the second sliding groove and is fixedly connected to the first locking block. A first air pipe is fixedly connected to the fixed plate. The first air pipe is a three-way pipe. A first piston is slidably connected to both ends of the top of the first air pipe. The two first pistons are fixedly connected to the two first sliders respectively. The bottom end of the first air pipe extends through the side wall of the high-temperature flue into the high-temperature flue and is slidably connected to a second piston. A pipe body is slidably connected to the end of the second piston away from the first air pipe. The pipe body is fixedly connected to the high-temperature flue and is filled with a liquid that expands when heated.

[0011] As a further embodiment of the present invention, the driving mechanism includes a rack and pinion, and two racks are provided. Both racks are fixedly installed inside the blind plate. Each rack has a pin gear on its side that can mesh with it. The two pin gears are fixedly connected to a drive shaft. The drive shaft is rotatably connected to the mounting box. A first drive wheel is also fixedly connected to the drive shaft. The first drive wheel is connected to a second drive wheel via a belt drive. A motor for driving the rotation of the second drive wheel is provided on its side.

[0012] As a further embodiment of the present invention, a second locking block is provided on the side of the sealing plate. The second locking block is wedge-shaped and is slidably connected to the high-temperature flue. A second spring for resetting is fixedly connected to the second locking block. A third piston is fixedly connected to the second locking block. A second gas pipe is slidably connected to the third piston. The end of the second gas pipe away from the third piston is connected to the first gas pipe.

[0013] As a further embodiment of the present invention, a rubber sealing block is fixedly connected to the end of the sealing plate away from the rotating shaft.

[0014] As a further aspect of the present invention, the liquid that expands upon heating is mercury.

[0015] Compared with the prior art, the beneficial effects of the present invention are: 1. This invention, by placing a blind flange inside an installation box and designing the installation box as a closed structure, ensures that high-temperature flue gas will not leak. Furthermore, the sealing plate prevents high-temperature flue gas from entering the installation box. When maintenance is required, the drive mechanism simply moves the blind flange downwards without obstructing its movement. When the blind flange moves to the position that isolates the high-temperature flue, the bottom end of the sealing plate adheres to the side wall of the blind flange, further preventing high-temperature flue gas from entering the installation box. This significantly improves the efficiency of maintenance of the waste heat boiler. Attached Figure Description Attached Figure Description Figure 1 This is a schematic diagram of the overall structure of the present invention; Figure 2 This is a schematic cross-sectional view of the overall structure of the present invention; Figure 3 This is a cross-sectional schematic diagram of the fixing mechanism structure of the present invention; Figure 4 for Figure 3 Enlarged view of a portion of point A in the middle; Figure 5 for Figure 3 Enlarged view of a section at point B in the middle; Figure 6 This is a schematic diagram of the mounting box and the first guide post structure of the present invention; Figure 7 This is a schematic diagram of the second slide groove structure of the present invention; Figure 8 This is a schematic diagram of the blind plate, pin rack, and pin gear structure of the present invention; Figure 9 This is a cross-sectional schematic diagram of the second locking block, second spring, third piston, and second air tube structure of the present invention; Figure 10 This is a schematic diagram of the sealing plate and rubber sealing block structure of the present invention.

[0017] The attached diagram lists the components represented by each number as follows: 1. High-temperature flue; 2. Mounting box; 3. Blind flange; 4. Sealing plate; 5. Fixing plate; 6. First sliding groove; 6. Horizontal groove; 6. Vertical groove; 6. First locking block; 7. First guide post; 8. First slider; 9. First spring; 10. Second sliding groove; 11. Second guide post; 12. First air pipe; 13. First piston; 14. Second piston; 15. Pipe body; 16. Pin rack; 17. Pin gear; 18. Drive shaft; 19. First drive wheel; 20. Belt; 21. Second drive wheel; 22. Motor; 23. Second locking block; 24. Second spring; 25. Third piston; 26. Second air pipe; 27. Rubber sealing block; 28. Sealing gasket; 29. Detailed Implementation

[0018] Please see Figure 1-10 This invention provides a technical solution: a fully enclosed built-in blind flange device for preventing high-temperature flue gas leakage, comprising a high-temperature flue 1, an installation box 2 that can communicate with the high-temperature flue 1 is provided above the high-temperature flue 1, the installation box 2 and the high-temperature flue 1 are connected by a fixing mechanism; a sealing gasket 29 is provided between the high-temperature flue 1 and the installation box 2; a blind flange 3 is slidably connected to the installation box 2 in the vertical direction, a sealing component is provided below the blind flange 3, and a driving mechanism for driving it to move in the vertical direction is provided on the side of the blind flange 3.

[0019] The sealing assembly includes a sealing plate 4, which is rotatably installed inside the high-temperature flue 1 and located directly below the blind plate 3. A torsion spring for resetting is fitted on the rotating shaft of the sealing plate 4.

[0020] When the above solution is put into practical use, such as Figure 1-2 As shown, during combined circulation or short-term single circulation, the blind flange 3 is stored in the mounting box 2. The mounting box 2 is detachably installed on the top of the high-temperature flue 1 via a fixing mechanism, which facilitates the replacement of the blind flange 3. When the waste heat boiler needs maintenance, the drive mechanism drives the blind flange 3 to move downwards. When the blind flange 3 moves downwards and contacts the sealing plate 4, the blind flange 3 will drive the sealing plate 4 to... Figure 2 The indicated state is rotated clockwise downwards until the drive mechanism moves the blind plate 3 to contact the bottom of the high-temperature flue 1. At this point, the right end of the sealing plate 4 is in contact with the left side wall of the blind plate 3, and the blind plate 3 isolates the high-temperature flue 1. At this point, the flue gas on the left side of the high-temperature flue 1 cannot flow to the right, and because the sealing plate 4 is in contact with the blind plate 3, the flue gas cannot enter the installation box 2. Then, the staff can inspect and maintain the waste heat boiler. After the inspection and maintenance are completed, the drive mechanism drives the blind plate 3 to move upwards back into the installation box 2, and then the sealing plate 4 will return to its original position under the action of the torsion spring. Figure 2The waste heat boiler can then continue to operate at the indicated position. This invention, by setting the blind plate inside the mounting box 2 and making the mounting box 2 a closed structure, can ensure that high-temperature flue gas will not leak. Through the setting of the sealing plate 4, the sealing plate 4 can block high-temperature flue gas from entering the mounting box 2. When maintenance is required, the drive mechanism can drive the blind plate 3 to move directly downwards. The sealing plate 4 will not obstruct the downward movement of the blind plate 3. When the blind plate 3 moves to the position of isolating the high-temperature flue 1, the bottom end of the sealing plate 4 fits against the side wall of the blind plate 3, which can continue to prevent high-temperature flue gas from entering the mounting box 2, which can greatly improve the maintenance efficiency of the waste heat boiler.

[0021] As a further embodiment of the present invention, the fixing mechanism includes a fixing plate 5, which is fixedly installed on the outer wall of the high-temperature flue 1. A first sliding groove 6 is provided on the fixing plate 5. The first sliding groove 6 is composed of a horizontal groove 61 and two vertical grooves 62. The two vertical grooves 62 are respectively connected to one end and the middle of the horizontal groove 61. A first locking block 7 is provided in each of the two vertical grooves 62. The first locking block 7 is wedge-shaped and is elastically slidably connected to the fixing plate 5. A first guide post 8 is slidably connected in the first sliding groove 6 and is fixedly connected to the mounting box 2.

[0022] When the above solution is put into practical use, such as Figure 3-4 As shown, when it is necessary to install the mounting box 2 onto the high-temperature flue 1, the operator uses a hoisting tool to lift the mounting box 2, aligning the first guide column 8 with the transverse groove 61; as shown. Figure 6 As shown, there are two first guide posts 8, and the two first guide posts 8 are of different lengths; as Figure 3 As shown, the two vertical grooves 62 are of different depths; when the mounting box 2 is lifted, it is sufficient to ensure that the longer first guide post 8 enters the horizontal groove 61 first to prevent the mounting box 2 from being installed backwards. Furthermore, the longer first guide post 8 will not fall when passing through the shallower vertical groove 62 located on the outside, thus ensuring smooth installation of the mounting box 2. When the longer first guide post 8 moves directly above the deeper vertical groove 62, the shorter first guide post 8 moves directly above the shallower vertical groove 62. Then, the lifting tool drives the mounting box 2 to move vertically downwards. The two first guide posts 8 will respectively push the wedge-shaped surface of the first locking block 7, driving the first locking block to move outwards until the first guide post 8 moves below the first locking block 7. Then, the first locking block 7 will return to its initial position under the action of the spring. At this point, the mounting box 2 is installed, and the first guide post 8... Figure 4 As shown, located below the first locking block 7, the mounting box 2 presses against the sealing gasket 29. The sealing gasket 29 ensures that the high-temperature flue gas inside the high-temperature flue 1 will not leak from the mounting box 2; as Figure 2 and Figure 9As shown, the sealing gasket 29 is placed in the slot opened at the top of the high-temperature flue 1, and the sealing gasket 29 protrudes from the slot, which facilitates the replacement of the sealing gasket 29. It should be noted that a pull block (not shown in the figure) needs to be fixed on the outside of the first locking block 7 for easy pulling by the staff. When the blind plate 3 needs to be replaced, the staff can pull the pull block to move the first locking block 7 outward to remove the restriction on the first guide post 8. Then the hoisting tool can lift the installation box 2 and pull the installation box 2 out of the horizontal slot 61. With the setting of the fixing mechanism, the installation box 2 only needs to be hoisted to the designated position by the hoisting tool and then pressed down to complete the installation. There is no need to fix it with bolts or the like, which can greatly simplify the installation process of the installation box 2 and greatly reduce the workload of the staff.

[0023] As a further embodiment of the present invention, the first locking block 7 is slidably connected to a first slider 9 in the vertical direction. The first slider 9 is slidably connected to a fixing plate 5. A first spring 10 for resetting is fixedly connected to the first slider 9. A second sliding groove 11 is provided on the fixing plate 5. The second sliding groove 11 is L-shaped and one side of the second sliding groove 11 is inclined. A second guide post 12 is slidably connected in the second sliding groove 11. The second guide post 12 is fixedly connected to the first locking block 7. A first air pipe 13 is fixedly connected to the fixing plate 5. The first air pipe 13 is a three-way pipe. A first piston 14 is slidably connected to both ends of the top of the first air pipe 13. The two first pistons 14 are fixedly connected to the two first sliders 9 respectively. The bottom end of the first air pipe 13 extends through the side wall of the high-temperature flue 1 into the high-temperature flue 1 and is slidably connected to a second piston 15. A pipe body 16 is slidably connected to the end of the second piston 15 away from the first air pipe 13. The pipe body 16 is fixedly connected to the high-temperature flue 1. The pipe body 16 is filled with a liquid that expands when heated.

[0024] When the above solution is put into practical use, such as Figure 3-7 As shown, when high-temperature flue gas passes through the high-temperature flue 1, the temperature inside the high-temperature flue 1 rises; after the temperature inside the high-temperature flue 1 rises, the liquid inside the pipe 16 also expands accordingly, and the second piston 15 moves to the left under the action of liquid pressure. The end of the second piston 15 located inside the first air pipe 13 will push the air inside the first air pipe 13 to compress. After the pressure inside the first air pipe 13 increases, the first piston 14 will drive the first slider 9 to move closer to the first locking block 7 under the action of air pressure. The first slider 9 will drive the first locking block 7 to move closer to the first guide post 8; as Figure 7As shown, the first locking block 7 drives the second guide post 12 to slide within the second slide groove 11. The end of the second slide groove 11 near the first guide post 8 is set in an inclined shape. Under the action of the second slide groove 11, when the first locking block 7 moves towards the side near the first guide post 8, it will press the first guide post 8 downward, which can better press the mounting box 2. Through the arrangement of the first slider 9, the first spring 10, the second slide groove 11, the second guide post 12, the first gas pipe 13, the first piston 14, the second piston 15 and the pipe body 16, the present invention can make the first locking block 7 drive the first guide post 8 to move downward when high-temperature flue gas enters the high-temperature flue duct 1 of the waste heat boiler, so that the mounting box 2 can fit more tightly with the high-temperature flue duct 1, and the mounting box 2 can be better pressed on the sealing gasket 29 to prevent high-temperature flue gas leakage.

[0025] As a further embodiment of the present invention, the driving mechanism includes a rack and pinion 17, and two racks and pinions 17 are provided. Both racks and pinions 17 are fixedly installed inside the blind plate 3. Each rack and pinion 17 has a pin gear 18 that can mesh with it on its side. The two pin gears 18 are fixedly connected to a drive shaft 19. The drive shaft 19 is rotatably connected to the mounting box 2. A first drive wheel 20 is also fixedly connected to the drive shaft 19. The first drive wheel 20 is connected to a second drive wheel 22 via a belt 21. A motor 23 for driving the rotation of the second drive wheel 22 is provided on its side.

[0026] When the above solution is put into practical use, such as Figure 1 and Figure 8 As shown, when the drive mechanism is working, the motor 23 drives the second transmission wheel 22 to rotate. The second transmission wheel 22 drives the first transmission wheel 20 to rotate via the belt 21. The first transmission wheel 20 drives two pin gears 18 to rotate synchronously via the transmission shaft 19. The pin gears 18 drive the pin racks 17 to move the blind plate 3 downward. This invention realizes the lifting and lowering of the blind plate 3 through the pin gears 18 and pin racks 17. Pin gear transmission is especially suitable for large equipment with high speed ratio and low speed operation. The two pin racks 17 are located on both sides of the blind plate. When the pin gear rack on one side is damaged, the other row of pin gear racks can also realize the lifting and lowering of the blind plate, thereby achieving the effect of redundant drive and avoiding the phenomenon of the entire equipment being shut down for maintenance due to a problem with a single row of teeth.

[0027] As a further embodiment of the present invention, a second locking block 24 is provided on the side of the sealing plate 4. The second locking block 24 is wedge-shaped and is slidably connected to the high-temperature flue 1. A second spring 25 for resetting is fixedly connected to the second locking block 24. A third piston 26 is fixedly connected to the second locking block 24. A second air pipe 27 is slidably connected to the third piston 26. The end of the second air pipe 27 away from the third piston 26 is connected to the first air pipe 13.

[0028] When the above solution is put into practical use, such as Figure 9 As shown, when the air in the first air pipe 13 is compressed, the air in the second air pipe 27 connected to the first air pipe 13 is also compressed. The second and third pistons 26 will drive the second locking block 24 to move closer to the sealing plate 4. The second locking block 24 will drive the sealing plate 4 to fit tightly against the top inner wall of the high-temperature flue 1 through the wedge-shaped surface. This ensures that when high-temperature flue gas passes through the high-temperature flue 1, the sealing plate 4 can better seal the top of the high-temperature flue 1 and prevent high-temperature flue gas leakage.

[0029] As a further embodiment of the present invention, a rubber sealing block 28 is fixedly connected to the end of the sealing plate 4 away from the rotating shaft.

[0030] When the above solution is put into practical use, such as Figure 10 As shown, a rubber sealing block 28 is provided on the end of the sealing plate 4 that is in contact with the blind plate 3, which can better prevent the leakage of high-temperature flue gas.

[0031] As a further aspect of the present invention, the liquid that expands upon heating is mercury.

[0032] When the above scheme is put into actual use, mercury expands more sensitively when heated. After high-temperature flue gas passes through the high-temperature flue 1, the sealing of the high-temperature flue 1 can be carried out immediately, which can better prevent the leakage of high-temperature flue gas.

[0033] Working principle: such as Figure 1-2 As shown, during combined circulation or short-term single circulation, the blind flange 3 is stored in the mounting box 2. The mounting box 2 is detachably installed on the top of the high-temperature flue 1 via a fixing mechanism, which facilitates the replacement of the blind flange 3. When the waste heat boiler needs maintenance, the drive mechanism drives the blind flange 3 to move downwards. When the blind flange 3 moves downwards and contacts the sealing plate 4, the blind flange 3 will drive the sealing plate 4 to... Figure 2 The indicated state is rotated clockwise downwards until the drive mechanism moves the blind plate 3 to contact the bottom of the high-temperature flue 1. At this point, the right end of the sealing plate 4 is in contact with the left side wall of the blind plate 3, and the blind plate 3 isolates the high-temperature flue 1. At this point, the flue gas on the left side of the high-temperature flue 1 cannot flow to the right, and because the sealing plate 4 is in contact with the blind plate 3, the flue gas cannot enter the installation box 2. Then, the staff can inspect and maintain the waste heat boiler. After the inspection and maintenance are completed, the drive mechanism drives the blind plate 3 to move upwards back into the installation box 2, and then the sealing plate 4 will return to its original position under the action of the torsion spring. Figure 2The waste heat boiler can then continue to operate at the indicated position. This invention, by setting the blind plate inside the mounting box 2 and making the mounting box 2 a closed structure, can ensure that high-temperature flue gas will not leak. Through the setting of the sealing plate 4, the sealing plate 4 can block high-temperature flue gas from entering the mounting box 2. When maintenance is required, the drive mechanism can drive the blind plate 3 to move directly downwards. The sealing plate 4 will not obstruct the downward movement of the blind plate 3. When the blind plate 3 moves to the position of isolating the high-temperature flue 1, the bottom end of the sealing plate 4 fits against the side wall of the blind plate 3, which can continue to prevent high-temperature flue gas from entering the mounting box 2, which can greatly improve the maintenance efficiency of the waste heat boiler.

Claims

1. A fully enclosed built-in blind flange device for preventing high-temperature flue gas leakage, comprising a high-temperature flue (1), characterized in that: An installation box (2) is provided above the high-temperature flue (1) and is connected to it via a fixing mechanism; a sealing gasket (29) is provided between the high-temperature flue (1) and the installation box (2); a blind plate (3) is slidably connected to the installation box (2) in the vertical direction; a sealing component is provided below the blind plate (3); and a driving mechanism for driving the blind plate (3) to move in the vertical direction is provided on the side of the blind plate (3). The sealing assembly includes a sealing plate (4), which is rotatably installed inside the high-temperature flue (1) and located directly below the blind plate (3). A torsion spring for resetting is fitted on the rotating shaft of the sealing plate (4). The fixing mechanism includes a fixing plate (5), which is fixedly installed on the outer wall of the high-temperature flue (1). A first sliding groove (6) is provided on the fixing plate (5). The first sliding groove (6) is composed of a horizontal groove (61) and two vertical grooves (62). The two vertical grooves (62) are respectively connected to one end and the middle of the horizontal groove (61). A first locking block (7) is provided in each of the two vertical grooves (62). The first locking block (7) is wedge-shaped and is elastically slidably connected to the fixing plate (5). A first guide post (8) is slidably connected in the first sliding groove (6). The first guide post (8) is fixedly connected to the mounting box (2).

2. The fully enclosed built-in blind flange device for preventing high-temperature flue gas leakage according to claim 1, characterized in that: The first locking block (7) is slidably connected to a first slider (9) in the vertical direction. The first slider (9) is slidably connected to a fixing plate (5). A first spring (10) for resetting is fixedly connected to the first slider (9). A second sliding groove (11) is provided on the fixing plate (5). The second sliding groove (11) is L-shaped and one side of the second sliding groove (11) is inclined. A second guide post (12) is slidably connected in the second sliding groove (11). The second guide post (12) is fixedly connected to the first locking block (7). A first air tube (13) is fixedly connected to the fixing plate (5). The first air pipe (13) is a three-way pipe. The top two ends of the first air pipe (13) are slidably connected to the first piston (14). The two first pistons (14) are fixedly connected to the two first sliders (9). The bottom end of the first air pipe (13) extends through the side wall of the high temperature flue (1) into the high temperature flue (1) and is slidably connected to the second piston (15). The end of the second piston (15) away from the first air pipe (13) is slidably connected to the pipe body (16). The pipe body (16) is fixedly connected to the high temperature flue (1). The pipe body (16) is filled with a liquid that expands when heated.

3. The fully enclosed built-in blind flange device for preventing high-temperature flue gas leakage according to claim 1, characterized in that: The drive mechanism includes a rack (17), and there are two racks (17). Both racks (17) are fixedly installed inside the blind plate (3). Each rack (17) has a pin gear (18) on its side that can mesh with it. The two pin gears (18) are fixedly connected to a drive shaft (19). The drive shaft (19) is rotatably connected to the mounting box (2). A first drive wheel (20) is also fixedly connected to the drive shaft (19). The first drive wheel (20) is connected to a second drive wheel (22) via a belt (21). A motor (23) for driving the second drive wheel (22) is provided on its side.

4. A fully enclosed built-in blind flange device for preventing high-temperature flue gas leakage according to claim 2, characterized in that: The sealing plate (4) is provided with a second locking block (24) on its side. The second locking block (24) is wedge-shaped and is slidably connected to the high-temperature flue (1). A second spring (25) for resetting is fixedly connected to the second locking block (24). A third piston (26) is fixedly connected to the second locking block (24). A second air pipe (27) is slidably connected to the third piston (26). The end of the second air pipe (27) away from the third piston (26) is connected to the first air pipe (13).

5. A fully enclosed built-in blind flange device for preventing high-temperature flue gas leakage according to claim 4, characterized in that: A rubber sealing block (28) is fixedly connected to the end of the sealing plate (4) away from the rotating shaft.

6. A fully enclosed built-in blind flange device for preventing high-temperature flue gas leakage according to claim 2, characterized in that: The liquid that expands when heated is mercury.

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