A flexible sealing method for an air preheater

Abstract

The present invention relates to a flexible sealing method for an air preheater. Flexible contact sealing devices (10) are installed at the upper, lower, left, and right sides of each straight pipe interface (1) of the air preheater, and boxed spring sealing devices (20) are installed at the adjacent positions of the four corners. A soft sealing layer (5) is filled in the adjacent side gaps between the boxed spring sealing devices (20) and the flexible contact sealing devices (10). Its installation includes seven steps. The flexible sealing method for an air preheater of the present invention has better sealing effect, convenient maintenance, and long service life.

Description

Technical Field

[0001] The present invention relates to a flexible sealing method for an air preheater, belonging to the technical field of air preheater sealing. Background Art

[0002] A flame heating furnace is a process heating furnace widely used in the petroleum, petrochemical, and natural gas industries. Fuel oil or gas is used as fuel, and the flame directly heats the process fluid flowing continuously in the furnace tubes to meet the temperature requirements of downstream equipment for the process fluid. Among them, the air preheater is an important component of the flame heating furnace.

[0003] An air preheater, also simply referred to as an air preheater, is a preheating and energy-saving device that improves the heat exchange performance of a heating furnace and reduces heat loss. Its principle of action is to transfer the heat carried in the flue gas discharged from the tail flue of the heating furnace to the air participating in combustion before entering the heating furnace through a heat exchanger, preheating the air to a certain temperature to achieve the effect of energy conservation.

[0004] The straight pipe interface device of the heating furnace air preheater is an intermittent reciprocating motion sealing system, and there are machining errors in the straight pipe interfaces. Conventional rigid seals have leakage problems. There are 5 straight pipe interfaces at the connection with the heat exchanger flat plate. Due to factors such as assembly errors and welding deformations in the box body and straight pipe interfaces, which are all welded structural parts, the misalignment error value between the 5 straight pipe interfaces reaches 20 mm ( Figure 1 as shown), which cannot meet the requirement of the designed gap of 30 mm. Therefore, there is an urgent need for a sealing method that can solve the leakage problem caused by the relative reciprocating motion of the straight pipe interfaces of the air preheater and large errors in the interfaces. Summary of the Invention

[0005] The purpose of the present invention is to overcome the above deficiencies and provide a flexible sealing method for an air preheater with good sealing effect.

[0006] The purpose of the present invention is achieved as follows:

[0007] A flexible sealing method for an air preheater, in which flexible contact sealing devices are installed at the upper, lower, left, and right sides of each straight pipe interface of the air preheater, and boxed spring sealing devices are installed at the adjacent positions of the four corners. A soft sealing layer is filled in the adjacent side gaps between the boxed spring sealing devices and the flexible contact sealing devices; the boxed spring sealing device includes a sealing box with a counterbore inside, an inner sleeve slidably embedded in the counterbore, and a spring arranged between the sealing box and the inner sleeve; a screw is provided at the center of the bottom of the counterbore, the screw penetrates through the spring and the through hole at the center of the inner sleeve, and an adjusting nut is screwed at the end of the screw to adjust the telescopic range of the sealing box;

[0008] The installation steps are as follows:

[0009] Step 1: Open installation windows on the four sides of the straight pipe interface, install horizontal and vertical mounting plates on the inner sides of the four sides, and weld and fix the installation bolts on the mounting plates;

[0010] Step 2: Install a heat exchanger inside the air preheater casing, and the flat connection of the heat exchanger corresponds to the position of the straight pipe interface;

[0011] Step 3: Pre-compress the boxed spring type sealing device through an adjusting nut, install the boxed spring type sealing device at the corresponding position on the mounting plate, and ensure that its external sealing box fits the flat plate of the heat exchanger by selecting different installation positions on the inner sleeve;

[0012] Step 4: Pre-compress the flexible contact type sealing device through an adjusting nut, install the flexible contact type sealing device at the corresponding position on the mounting plate, and ensure that its sealing part fits the flat plate of the heat exchanger by selecting different mounting holes on the mounting part;

[0013] Step 5: Fill a soft sealing layer in the adjacent side gaps between the boxed spring type sealing device and the flexible contact type sealing device;

[0014] Step 6: Loosen the adjusting nuts of the boxed spring type sealing device and the flexible contact type sealing device to the maximum stroke position, weld and fix the adjusting nuts or directly remove the adjusting nuts;

[0015] Step 7: Seal the outer installation window of the straight pipe interface.

[0016] Furthermore, the flexible contact type sealing device includes a mounting part and a sealing part; both ends of the back of the sealing part are movably connected to the mounting part through hinges and elastic adjusting devices; the elastic adjusting device includes a connecting rod movably connected to the mounting part and the sealing part, a spring sleeved on the connecting rod, and an adjusting nut screwed at the end of the connecting rod for adjusting the opening and closing range of the sealing part.

[0017] Furthermore, the soft sealing layer is a rubber cushion layer.

[0018] Furthermore, the pre-compression range of the boxed spring type sealing device in Step 3 is 3 - 5 mm.

[0019] Furthermore, the pre-compression range of the flexible contact type sealing device in Step 4 is 3 - 5 mm.

[0020] Furthermore, wear-resistant ceramic layers are provided at the parts where the sealing part and the sealing box contact the flat plate of the heat exchanger.

[0021] Compared with the prior art, the beneficial effects of the present invention are:

[0022] The present invention adopts a flexible sealing solution that combines the installation of flexible contact sealing devices at the edges of each straight pipe interface of the air preheater and boxed spring sealing devices at the corners, which has a better sealing effect compared to the traditional rigid sealing solution;

[0023] The present invention opens installation windows on the four side surfaces of the straight pipe interface. First, a flexible sealing device is installed using a pre-compressed clearance fit. Finally, the adjusting nut is loosened through the installation window, causing the sealing part of the flexible sealing device to pop out to achieve an interference fit installation effect, meeting the sealing requirements when the gap changes irregularly; at the same time, it is more convenient for subsequent inspection, repair, and replacement, and maintenance work can be carried out without removing the entire inner heat exchanger box body;

[0024] The present invention adjusts the fitting degree between the flexible sealing device and the heat exchanger plate by selecting different installation positions or installation hole positions during the installation of the flexible sealing device, which can effectively eliminate the error value of 20 mm between the five straight pipe interfaces caused by factors such as assembly errors and welding deformations; and makes the spring working loads of the flexible seals basically consistent, increasing the service life. Brief Description of the Drawings

[0025] Figure 1 It is an assembly schematic diagram of an air preheater related to a flexible sealing method of the present invention.

[0026] Figure 2 It is a schematic diagram of the flexible sealing assembly structure of a flexible sealing method of an air preheater of the present invention.

[0027] Figure 3 It is Figure 2 A sectional structure schematic diagram in the A direction of

[0028] Figure 4 It is a schematic diagram of the installation structure of the straight pipe interface of a flexible sealing method of an air preheater of the present invention.

[0029] Figure 5 It is a schematic diagram of the structure of a boxed spring sealing device of a flexible sealing method of an air preheater of the present invention.

[0030] Figure 6 It is a schematic diagram of the structure of a flexible contact sealing device of a flexible sealing method of an air preheater of the present invention.

[0031] Figure 7 It is an assembly sealing schematic diagram of a flexible contact sealing device of a flexible sealing method of an air preheater of the present invention.

[0032] Wherein:

[0033] Straight pipe interface 1, heat exchanger 2, spring 3, adjusting nut 4, soft sealing layer 5, installation window 6, installation plate 7;

[0034] Flexible contact seal device 10, mounting part 11, sealing part 12, hinge 13, connecting rod 14, boxed spring seal device 20, seal box 21, inner sleeve 22, screw rod 23. Detailed implementation mode

[0035] See Figures 1 - 7 , a flexible seal method for an air preheater according to the present invention, installs flexible contact seal devices 10 at the upper, lower, left and right sides of each straight pipe interface 1 of the air preheater, and installs boxed spring seal devices 20 at the adjacent positions of the four corners. Fill the soft seal layer 5 in the adjacent side gaps between the boxed spring seal device 20 and the flexible contact seal device 10. The soft seal layer 5 is a rubber cushion layer;

[0036] The flexible contact seal device 10 includes a mounting part 11 and a sealing part 12; both ends of the back surface of the sealing part 12 are movably connected to the mounting part 11 through a hinge 13 and an elastic adjusting device respectively; the elastic adjusting device includes a connecting rod 14 movably connected to the mounting part 11 and the sealing part 12, and a spring 3 sleeved on the connecting rod 14. An adjusting nut 4 is screwed at the end of the connecting rod 14 to adjust the opening and closing range of the sealing part 12, and the opening and closing linear distance range of the sealing part 12 is greater than 30 mm;

[0037] The boxed spring seal device 20 includes a seal box 21 with a counterbore inside, an inner sleeve 22 slidably embedded in the counterbore, and a spring 3 arranged between the seal box 21 and the inner sleeve 22; a screw rod 23 is provided at the center of the bottom of the counterbore. The screw rod 23 penetrates through the through hole at the center of the spring 3 and the inner sleeve 22, and an adjusting nut 4 is screwed at the end of the screw rod 23 to adjust the telescopic range of the seal box 21, and the telescopic distance of the seal box 21 is greater than 25 mm;

[0038] The installation steps of the seal method are as follows:

[0039] Step 1: Open installation windows 6 on the four sides of the straight pipe interface 1, and install horizontal and vertical mounting plates 7 on the inner sides of the four sides. Weld the mounting bolts to the mounting plates 7;

[0040] Step 2: Install a heat exchanger in the box body of the air preheater, and the flat connection part of the heat exchanger 2 corresponds to the position of the straight pipe interface 1;

[0041] Step 3: Pre-compress the boxed spring seal device 20 by 3-5 mm through the adjusting nut, and install the boxed spring seal device 20 at the corresponding position of the mounting plate 7. Ensure that the external seal box 21 fits the flat plate of the heat exchanger 2 by welding at different mounting positions on the inner sleeve 22; a wear-resistant ceramic layer is provided at the part where the seal box 21 contacts the flat plate of the heat exchanger 2;

[0042] Step 4: Pre-compress the flexible contact sealing device 10 by 3 - 5 mm through the adjusting nut, and install the flexible contact sealing device 10 at the corresponding position on the mounting plate 7. Fix it to the mounting plate 7 with bolts by selecting different mounting holes on the mounting part 11 to ensure that its sealing part 12 is in close contact with the flat plate of the heat exchanger 2; a wear-resistant ceramic layer is provided at the part where the sealing part 12 contacts the flat plate of the heat exchanger 2.

[0043] Step 5: Fill the soft sealing layer 5 in the adjacent side gaps between the boxed spring sealing device 20 and the flexible contact sealing device 10.

[0044] Step 6: Loosen the adjusting nut 4 of the boxed spring sealing device 20 and the flexible contact sealing device 10 to the maximum stroke position, weld the adjusting nut 4 in place or directly remove the adjusting nut 4; when the adjusting nut 4 is in a loose state, the spring structure will be automatically locked due to force vibration, causing the sealing device to be unable to return to its natural state, increasing the gap and resulting in increased leakage.

[0045] Step 7: Seal the outer installation window 6 of the straight pipe interface 1.

[0046] Adopt a combined sealing form of flexible contact sealing and boxed spring sealing. Due to the working principle of the spring type, an appropriate interference fit installation must be used to meet the irregular changes in the gap and make the sealing effect reach an ideal state. If an interference fit installation is used, the inner heat exchanger box body cannot be assembled, and forced assembly will damage the sealing device; if a clearance fit is used, the sealing design requirements cannot be met. Subsequently, if the sealing device is in a non-working state, it cannot be inspected, repaired, or replaced, and the entire inner heat exchanger box body needs to be pulled out for maintenance work. Therefore, installation windows 6 are opened on the four sides of the straight pipe interface 1, and a flexible sealing device is installed with a pre-compressed clearance fit. Finally, through the installation window 6, the adjusting nut 4 can be easily loosened, causing the sealing part of the flexible sealing device to pop out to produce the effect of an interference fit installation, meeting the sealing requirements when the gap changes irregularly; at the same time, it is more convenient for subsequent inspection, repair, and replacement, and maintenance work can be carried out without pulling out the entire inner heat exchanger box body.

[0047] When installing the flexible sealing device, its installation position is adjusted by selecting different installation positions or installation holes to ensure that the flexible sealing device is in close contact with the flat plate of the heat exchanger 2, which can effectively eliminate the error value of 20 mm between the five straight pipe interfaces 1 caused by factors such as assembly errors and welding deformations; and make the spring working loads of the flexible seals basically the same, increasing the service life.

[0048] In addition: It should be noted that the above specific implementation manner is only an optimized solution of this patent. Any changes or improvements made by those skilled in the art based on the above conceptions are within the protection scope of this patent.

Claims

1. A flexible sealing method for an air preheater, characterized in that: At the upper, lower, left and right sides of each straight pipe interface (1) of the air preheater, a flexible contact sealing device (10) is installed, and a boxed spring sealing device (20) is installed at the adjacent positions of the four corners. A soft sealing layer (5) is filled in the adjacent side gaps between the boxed spring sealing device (20) and the flexible contact sealing device (10); the boxed spring sealing device (20) includes a sealing box (21) with a counterbore inside, an inner sleeve (22) slidably fitted in the counterbore, and a spring (3) arranged between the sealing box (21) and the inner sleeve (22); a screw rod (23) is provided at the center of the bottom of the counterbore, the screw rod (23) penetrates through the through hole at the center of the spring (3) and the inner sleeve (22), and an adjusting nut (4) is screwed at the end of the screw rod (23) for adjusting the telescopic range of the sealing box (21). The installation steps are as follows: Step 1: Installing windows (6) are opened on the four sides of the straight pipe interface (1), and horizontal and vertical mounting plates (7) are additionally installed on the inner sides of the four sides. Mounting bolts are welded and fixed on the mounting plates (7). Step 2: A heat exchanger is installed in the box body of the air preheater, and the flat connection part of the heat exchanger (2) corresponds to the position of the straight pipe interface (1). Step 3: The boxed spring sealing device (20) is pre-compressed through the adjusting nut, and the boxed spring sealing device (20) is installed at the corresponding position of the mounting plate (7). By selecting different mounting positions on the inner sleeve (22), it is ensured that the outer sealing box (21) fits the flat plate of the heat exchanger (2). Step 4: The flexible contact sealing device (10) is pre-compressed through the adjusting nut, and the flexible contact sealing device (10) is installed at the corresponding position of the mounting plate (7). By selecting different mounting holes on the mounting part (11), it is ensured that the sealing part (12) fits the flat plate of the heat exchanger (2). Step 5: A soft sealing layer (5) is filled in the adjacent side gaps between the boxed spring sealing device (20) and the flexible contact sealing device (10). Step 6: The adjusting nuts (4) of the boxed spring sealing device (20) and the flexible contact sealing device (10) are loosened to the maximum stroke position, and the adjusting nuts (4) are welded dead or directly removed. Step 7: The outer installing window (6) of the straight pipe interface (1) is blocked.

2. The flexible sealing method of the air preheater according to claim 1, characterized in that: The flexible contact sealing device (10) includes a mounting part (11) and a sealing part (12); both ends of the back of the sealing part (12) are movably connected to the mounting part (11) through hinges (13) and elastic adjusting devices respectively; the elastic adjusting device includes a connecting rod (14) movably connected to the mounting part (11) and the sealing part (12), a spring (3) sleeved on the connecting rod (14), and an adjusting nut (4) is screwed at the end of the connecting rod (14) for adjusting the opening and closing range of the sealing part (12).

3. The flexible sealing method of the air preheater according to claim 1, wherein: The soft sealing layer (5) is a rubber cushion layer.

4. The flexible sealing method of the air preheater according to claim 1, characterized in that: In the above Step 3, the pre-compression range of the boxed spring sealing device (20) is 3 - 5 mm.

5. The flexible sealing method of the air preheater according to claim 1, wherein: In the above Step 4, the pre-compression range of the flexible contact sealing device (10) is 3 - 5 mm.

6. The flexible sealing method of the air preheater according to claim 1, characterized in that: A wear-resistant ceramic layer is provided at the parts where the sealing part (12) and the sealing box (21) are in flat contact with the heat exchanger (2).

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