A thermal compensation sealing device and its installation structure used in the hot end of air preheater

Abstract

The present invention discloses a thermal compensation sealing device and its installation structure applied to the hot end of an air preheater, the thermal compensation sealing device comprises a first sealing sheet and a second sealing sheet; the first sealing sheet and the second sealing sheet are both in the shape of long strips; the first sealing sheet is provided with more than two first expansion gaps along the length direction, the second sealing sheet is provided with more than two second expansion gaps along the length direction, the first sealing sheet and the second sealing sheet are attached to each other, and the length directions of the first sealing sheet and the second sealing sheet are consistent, the first expansion gap and the second expansion gap are staggered; the fixed end of the first sealing sheet and the fixed end of the second sealing sheet are fixedly connected by spot welding; the thermal expansion coefficients of the first sealing sheet and the second sealing sheet are different. The present invention can eliminate the traditional triangular air leakage area of ​​the air preheater and significantly reduce the air leakage rate of the air preheater; increase the deformation amount of the sealing device when heated, and enhance the elastic deformation, repeatability of alternating hot and cold, and deformation stability.

Description

Technical Field

[0001] The invention relates to a thermal compensation sealing device applied to the hot end of an air preheater and a mounting structure thereof, belonging to the field of air preheater sealing. Background Art

[0002] The rotary air preheater is a heat exchange device used in large coal-fired power plant boilers. It uses the heat of boiler flue gas to heat the air required for combustion, thereby improving the efficiency of the boiler. When the air preheater rotor changes from cold to hot, it deforms into a "mushroom-shaped" shape due to the different temperatures of the upper and lower end surfaces and the weakening of the rigidity of the steel after being heated. The traditional rigid sealing plate is fixed to the rotor partition in sections by bolts. As the rotor partition deforms, the air leakage gap also changes. Based on the mechanism of the "mushroom-shaped" deformation of the rotor, appropriate cold clearances are reserved at the axial and cold end radial positions, and the dynamic and static clearances tend to zero in the hot state; although the cold clearance reserved at the hot end radial position is very small, a larger triangular air leakage area will be formed in the hot state.

[0003] In order to reduce the area of ​​the above-mentioned triangular air leakage zone and reduce the air leakage rate of the air preheater, two technical routes are generally adopted in the current engineering: one is the fan plate automatic tracking system (LCS for short) equipped by the three major domestic host manufacturers (Dongfang Boiler, Harbin Boiler and Shanghai Boiler); the other is the flexible sealing technology developed in recent years.

[0004] It is not difficult to understand that this actually reflects two aspects of a problem: the air preheater sealing problem is the problem of matching the sealing piece with the fan plate. The sealing piece automatically sticks to the fan plate and the fan plate automatically tracks the sealing piece to achieve the purpose of reducing air leakage. However, both solutions have problems in engineering applications: affected by harsh working conditions (high temperature, dust, etc.), maintenance quality, management level and other factors, most power plant LCS systems cannot be put into operation normally or the operation effect is not ideal. HOWDEN, the world's leading supplier of rotary air preheaters, has not equipped LCS on air preheaters, which also indirectly shows that this technology needs to be further improved. Traditional flexible sealing technology has exposed problems such as excessive wear, unreliable structure, and insufficient gap compensation, which cannot meet engineering requirements at all.

[0005] In short, the air leakage problem in the radial triangular air leakage area at the hot end has not been completely solved. Moreover, as the unit develops towards large capacity, the diameter of the air preheater rotor continues to increase. If no measures are taken, the air leakage share of the radial triangular air leakage area at the hot end will become larger and larger. If a traditional rigid sealing plate is used and the hot end fan plate is not adjustable, the radial outermost gap of the hot end of the 300MW unit exceeds 10mm, the 600MW unit exceeds 25mm, and the gap of the 1000MW unit is about 50mm. The radial triangular air leakage at the hot end of the air preheater equipped with units of 600MW and above accounts for more than 50% of the total air leakage, and the absolute air leakage to the flue gas side also exceeds 3%, and the primary air leakage rate may exceed 30%. Summary of the invention

[0006] In order to solve the air leakage problem in the radial triangular air leakage area of ​​the hot end in the prior art, the present invention provides a thermal compensation sealing device applied to the hot end of an air preheater and an installation structure thereof.

[0007] In order to solve the above technical problems, the technical solutions adopted by the present invention are as follows:

[0008] A thermal compensation sealing device applied to the hot end of an air preheater comprises a first sealing sheet and a second sealing sheet; the first sealing sheet and the second sealing sheet are both in the shape of long strips; the first sealing sheet is provided with more than two first expansion gaps along the length direction, the length direction of the first expansion gaps being perpendicular to the length direction of the first sealing sheet, and the second sealing sheet is provided with more than two second expansion gaps along the length direction, the length direction of the second expansion gaps being perpendicular to the length direction of the second sealing sheet; the first sealing sheet and the second sealing sheet are bonded together, and the length directions of the first sealing sheet and the second sealing sheet are consistent, and the first expansion gap and the second expansion gap are staggered; one end of the first sealing sheet and the second sealing sheet in the width direction is a fixed end, and the other end is a free end, the fixed end of the first sealing sheet and the fixed end of the second sealing sheet are arranged flush with each other, the free end of the first sealing sheet exceeds the free end of the second sealing sheet, and the fixed end of the first sealing sheet and the fixed end of the second sealing sheet are fixedly connected by spot welding; the thermal expansion coefficients of the first sealing sheet and the second sealing sheet are different.

[0009] The first expansion gap and the second expansion gap are staggered, that is, the two do not overlap but are staggered.

[0010] Compared with the sealing sheet without expansion gap, the present application increases the deformation of the sealing device when heated, enhances elastic deformability, enhances the repeatability of hot and cold alternation, makes the deformation more stable, and has a longer service life by setting the first expansion gap and the second expansion gap. The first expansion gap and the second expansion gap are staggered, which better ensures the uniformity of force, deformation and recovery. If the expansion gap is not provided, it will be hard pulled when heated and expanded, which not only has a small deformation, but also is not conducive to complete recovery, and the repeatability of hot and cold alternation is relatively poor, the deformation stability is poor, and the service life is short. Moreover, the present application only requires that the thermal expansion coefficients of the first sealing sheet and the second sealing sheet are different, and there is no need to specifically require whether the expansion coefficient of the first sealing sheet is larger or the expansion coefficient of the second sealing sheet is larger. As long as there is a difference in the thermal expansion coefficients of the two, the upward warping deformation of the non-completely fixed connection end after heating can be achieved under the premise that one end of the sealing device is completely fixedly connected and the other end is not completely fixedly connected in the length direction.

[0011] In order to improve the deformation stability of the sealing device, the fixed end of the first sealing sheet and the fixed end of the second sealing sheet are attached to each other and are fixedly connected by spot welding every 10-50 cm.

[0012] In order to facilitate installation and to facilitate the cantilever beam structure of the sealing device along the radial direction of the air preheater rotor, the first sealing plate and the second sealing plate are both provided with more than two waist-shaped holes along the length direction. The waist-shaped holes on the first sealing plate and the waist-shaped holes on the second sealing plate are equal in number and position. The length direction of the waist-shaped holes on the first sealing plate is consistent with the width direction of the first sealing plate, and the length direction of the waist-shaped holes on the second sealing plate is consistent with the width direction of the second sealing plate. The waist-shaped holes are used for placement and adjustment. The waist-shaped holes on the first sealing plate and the waist-shaped holes on the second sealing plate are in the same position, which means that the waist-shaped holes of the first sealing plate and the waist-shaped holes of the second sealing plate are opposite and overlap. In this way, one end of the first sealing plate and the second sealing plate in the length direction is completely fixedly connected by a fixing bolt assembly and welding, and the other end is partially fixedly connected by a fixing bolt assembly. The mounting bolts in the fixing bolt assembly pass through the waist-shaped holes of the first sealing plate and the second sealing plate at the same time, and the length of the waist-shaped holes of the first sealing plate and the second sealing plate is greater than the outer diameter of the mounting bolts, so that a cantilever beam structure of the sealing device along the radial direction of the air preheater rotor can be formed, that is, at the non-completely fixed end, the first sealing plate and the second sealing plate have a certain amount of movable space.

[0013] In order to further improve the deformation stability and deformation capacity of the sealing device and enhance the repeatability of hot and cold alternation, the upper and lower ends of the waist-shaped hole on the first sealing sheet are provided with first expansion gaps that penetrate the waist-shaped hole. The direction from the upper end to the lower end of the waist-shaped hole is also the length direction of the waist-shaped hole.

[0014] In order to prevent the above-mentioned sealing device from rubbing against the fan plate when it is deformed by heat, causing an increase in the rotor drive current, and to prevent the sealing device from being deformed by pressure and damaged, the free end of the first sealing sheet is provided with more than two separation gaps along the length direction, the length direction of the separation gaps is consistent with the width direction of the first sealing sheet, and the separation gaps are connected to the edge of the free end of the first sealing sheet. Preferably, the free end of the first sealing sheet is provided with a separation gap every 10-50cm along the length direction, the length of the separation gap is generally 10-20mm, and the width of the separation gap is generally not more than 1mm, so as to absorb the pressure deformation caused by rubbing at a certain position in sections.

[0015] In order to take into account the requirements of strength and stability, the length of the first expansion gap at the upper end of the waist-shaped hole is 1 / 2 to 5 / 6 of the distance from the upper end of the waist-shaped hole to the free end of the first sealing plate, preferably 2 / 3, and the first expansion gap at the lower end of the waist-shaped hole is connected to the edge of the fixed end of the first sealing plate.

[0016] In order to further improve the deformation stability and deformation capacity of the sealing device and enhance the repeatability of hot and cold alternation, a second expansion gap is provided at the fixed end between two adjacent waist-shaped holes on the second sealing sheet, and the second expansion gap is connected to the edge of the fixed end of the second sealing sheet. Further preferably, the second expansion gap is opened in the middle of two adjacent waist-shaped holes. The length of the second expansion gap is 1 / 2 to 5 / 6 of the width of the second sealing sheet, and more preferably 2 / 3.

[0017] The applicant has found through research that the difference in thermal expansion coefficients between the first sealing sheet and the second sealing sheet and the spot welding fixing position will significantly affect the upward warping amount of the non-completely fixed connection end of the sealing device after being heated, thereby significantly affecting the use effect of the thermal compensation sealing device applied to the hot end of the air preheater of the present invention. Preferably, the fixed end of the first sealing sheet and the fixed end of the second sealing sheet, the middle position of each two waist-shaped holes are fixedly connected by spot welding; all spot welding connection points are located on the same straight line. The thermal expansion coefficient of the first sealing sheet is 20 to 60% greater or less than the thermal expansion coefficient of the second sealing sheet.

[0018] In order to take into account both sealing performance and deformation stability, the width of the first expansion gap and the second expansion gap is no more than 1 mm.

[0019] The structural form of the first sealing sheet of the sealing device of the present application is not specifically limited, and can be a straight sheet, a bent sheet or a corrugated sheet. Preferably, the first sealing sheet of the sealing device is a bent sheet. In order to avoid collision and friction, it is further preferred that the free end of the first sealing sheet beyond the second sealing sheet is bent by 20 to 30 degrees. That is, the free end of the first sealing sheet beyond the second sealing sheet is provided with a folded edge that deviates from the width direction of the first sealing sheet by 20 to 30 degrees.

[0020] The above-mentioned installation structure of the thermal compensation sealing device applied to the hot end of the air preheater, the fixed ends of the first sealing plate and the second sealing plate are installed on the radial partition of the air preheater rotor, the thermal compensation sealing device applied to the hot end of the air preheater and the hot end fan plate of the air preheater form a sealing pair; the length directions of the first sealing plate and the second sealing plate are consistent with the radial length of the air preheater rotor; in order to achieve the purpose that the sealing plate basically does not follow the rotor to undergo "mushroom-shaped" deformation, the ends of the first sealing plate and the second sealing plate in the length direction close to the center of the air preheater rotor are completely fixedly connected to the radial partition of the air preheater rotor, and the ends of the first sealing plate and the second sealing plate in the length direction away from the center of the air preheater rotor are non-completely fixedly connected to the radial partition of the air preheater rotor, that is, the non-completely fixed connection end of the sealing device is allowed to have a certain sliding distance relative to the hot end radial partition, and on the hot end radial partition, the thermal compensation sealing device of the hot end of the air preheater presents a cantilever beam structure along the radial direction of the air preheater rotor.

[0021] The completely fixed connection between the sealing plate and the radial partition of the air preheater rotor in the present application means that the sealing plate and the radial partition of the air preheater rotor are fixed together without any slippage between them; the non-completely fixed connection between the sealing plate and the radial partition of the air preheater rotor means that although the sealing plate and the radial partition of the air preheater rotor are fixed together, there can be a certain slippage between them.

[0022] The thermal expansion coefficients of the first sealing sheet and the second sealing sheet of the present application are different, that is, the expansion amounts of the two after heating are different. After heating, the side with a larger expansion amount will transfer the expansion driving force to the other side through spot welding fixation; since the spot welding fixing point is arranged at the lower end (fixed end) in the width direction of the sealing device, the expansion end of the sealing sheet is subjected to compressive stress under the action of larger thermal stress; and the sealing device is installed on the radial partition of the hot end of the air preheater, one end of the sealing sheet is fixedly connected and the other end is not completely fixedly connected. After heating, the sealing device as a whole will warp and deform upward at the end of the non-completely fixed connection, showing a trend opposite to the deformation of the rotor partition (due to uneven heating of the upper and lower rotor partitions and weakened rigidity after heating, the partition has a tendency to droop downward, and the sealing device has a tendency to warp upward under the action of different expansion amounts of the two sealing sheets), so as to eliminate the traditional triangular air leakage area of ​​the air preheater and significantly reduce the air leakage rate of the air preheater.

[0023] The applicant has discovered through research that when the air preheater goes from a cold state to a hot state, the rotor undergoes a "mushroom-shaped" deformation, which is actually due to the deformation of the rotor partition (the distance between the upper edge of the hot end partition and the sealing surface of the fan plate becomes larger). After the sealing device of the present application is installed in place according to the above characteristics, it hardly deforms with the partition (the gap between the free end of the sealing device and the sealing surface of the fan plate remains almost unchanged). Therefore, the traditional triangular air leakage area of ​​the air preheater can be eliminated, and the air leakage rate of the air preheater can be significantly reduced. Compared with other sealing technologies, the present application has the comprehensive advantages of low cost, high reliability and good sealing performance.

[0024] In order to further improve the stability of sealing gap control and avoid errors in the design and installation process that may cause the sealing device to rub against the fan plate after being heated, a gap of 1-15mm should be reserved between the upper end surface of the above-mentioned thermal compensation sealing device and the fan plate at the hot end of the air preheater during installation.

[0025] The fixed ends of the first sealing sheet and the second sealing sheet are also the thermal expansion sides; the free ends of the first sealing sheet and the second sealing sheet are also the sealing sides.

[0026] In order to ensure that the end of the above-mentioned sealing device close to the air preheater rotor center tube is completely fixedly connected to the hot end radial partition, it is preferred that the first sealing plate and the second sealing plate in the length direction close to the air preheater rotor center tube are completely fixedly connected to the hot end radial partition by means of a fixing bolt assembly and welding.

[0027] As a preferred embodiment, the ends of the first and second sealing sheets in the length direction away from the center of the air preheater rotor are non-completely fixedly connected to the radial partition of the air preheater rotor by means of a fixing bolt assembly, and the mounting bolts in the fixing bolt assembly simultaneously pass through the waist-shaped holes of the first and second sealing sheets, and the length of the waist-shaped holes of the first and second sealing sheets is greater than the outer diameter of the mounting bolts, so that the first and second sealing sheets can have a certain slippage relative to the radial partition of the air preheater rotor during cold and hot deformation. The length direction of the aforementioned waist-shaped holes is consistent with the width direction of the first and second sealing sheets.

[0028] The above-mentioned fixing bolt assembly includes mounting bolts, mounting gaskets, mounting buffer plates and mounting pressure plates. The mounting gaskets and mounting buffer plates each have two pieces. The mounting bolts pass through the mounting gaskets, the radial partitions of the air preheater rotor, the mounting buffer plates, the waist-shaped holes of the first sealing plate, the waist-shaped holes of the second sealing plate, the mounting buffer plates, the mounting pressure plates and the mounting gaskets in sequence, and are fixed by nuts. That is, buffer plates are provided on both sides of the sealing device, and the whole is locked by mounting pressure plates and bolt gaskets. Different bolt gasket assemblies should have the same preload force setting during installation. The applicant has found through research that only the cantilever structure, due to the decrease in strength after heating, plus the static friction caused by the deformation of the partition, the sealing plate will also droop significantly. In order to ensure the relative slippage of the sealing device when heated, it is necessary to reduce the friction between the sealing device and the rotor mounting partition and pressure plate. It is preferred to install buffer plates on both sides of the hot end thermal compensation sealing device. The buffer plate is preferably made of high-temperature resistant mica plate with a thickness of 2-3mm.

[0029] For each radial partition, the above-mentioned air preheater hot end thermal compensation sealing device is an integral whole, and segmentation is not allowed along the radial direction of the rotor. However, for the convenience of processing and transportation, the segmented structure is allowed to be welded on site to become a whole again.

[0030] The traditional sealing device is fixed by clamping multiple bolt assemblies. When the rotor deforms into a mushroom shape, the sealing plate is also deformed, resulting in an air leakage gap. The present invention only fixes one end close to the center tube (the traditional sealing device is segmented along the radial direction for the convenience of transportation and installation, generally with a section of more than 1 meter, while the present invention must be integral along the radial direction, with a length of more than 4 meters). One end of the center tube is the fixing point of the cantilever. When the rotor deforms, the other end does not deform accordingly or has a tendency opposite to the deformation of the hot end radial partition.

[0031] In this application, directional words such as up and down, left and right, top and bottom refer to the relative positions of the device in normal use.

[0032] Technologies not particularly limited in the present invention are all prior arts.

[0033] The present invention is applied to the heat compensation sealing device of the hot end of the air preheater, which can eliminate the traditional triangular air leakage area of ​​the air preheater and significantly reduce the air leakage rate of the air preheater; through the setting of the first expansion gap and the second expansion gap, the deformation of the sealing device when heated is increased, the elastic deformability is enhanced, the repeatability of alternating hot and cold is enhanced, the deformation is more stable, and the service life is longer, and the first expansion gap and the second expansion gap are staggered. The distribution is better to ensure the uniformity of force, deformation and recovery; it has the comprehensive advantages of low cost, high reliability, good sealing performance, long service life, etc.; further, through the setting of the separation gap, the sealing device is prevented from being damaged by pressure deformation. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 It is a schematic cross-sectional installation diagram of the heat compensation sealing device at the hot end of the air preheater according to an embodiment of the present invention.

[0035] Figure 2 It is a schematic structural cross-sectional diagram of a thermal compensation sealing device at the hot end of an air preheater according to an embodiment of the present invention.

[0036] Figure 3 for Figure 2 Right view of .

[0037] Figure 4 This is a schematic diagram of the first sealing sheet structure of the thermal compensation sealing device at the hot end of the air preheater according to an embodiment of the present invention.

[0038] Figure 5 This is a schematic diagram of the second sealing plate structure of the thermal compensation sealing device at the hot end of the air preheater according to an embodiment of the present invention.

[0039] Figure 6 This is an overall installation diagram of the heat compensation sealing device at the hot end of the air preheater according to an embodiment of the present invention.

[0040] In the figure, 1 is the first sealing sheet, 10 is the spot welding fixing point of the sealing device, 11 is the partition gap on the first sealing sheet, 12 is the first expansion gap, 13 is the bending line of the first sealing sheet, 2 is the second sealing sheet, 21 is the second expansion gap, 3 is the mounting pressure plate, 4 is the mounting gasket, 5 is the mounting bolt assembly, 6 is the mounting buffer plate, 7 is the rotor hot end partition, 71 is the fixed end welding point of the sealing device, 8 is the hot end fan plate of the air preheater, and 9 is the waist-shaped hole. DETAILED DESCRIPTION

[0041] In order to better understand the present invention, the content of the present invention is further explained below in conjunction with the embodiments, but the content of the present invention is not limited to the following embodiments.

[0042] Example 1

[0043] like Figure 2-3As shown, a thermal compensation sealing device applied to the hot end of an air preheater comprises a first sealing sheet and a second sealing sheet; Figure 4-5 As shown, the first sealing sheet and the second sealing sheet are both in the shape of long strips; the first sealing sheet is provided with more than two first expansion gaps along the length direction, and the length direction of the first expansion gap is perpendicular to the length direction of the first sealing sheet; the second sealing sheet is provided with more than two second expansion gaps along the length direction, and the length direction of the second expansion gap is perpendicular to the length direction of the second sealing sheet; the first sealing sheet and the second sealing sheet are bonded together, and the length directions of the first sealing sheet and the second sealing sheet are consistent, and the first expansion gap and the second expansion gap are staggered; one end of the first sealing sheet and the second sealing sheet in the width direction is a fixed end, and the other end is a free end, as shown in FIG. Figure 2 As shown, the fixed end of the first sealing sheet and the fixed end of the second sealing sheet are arranged flush with each other, the free end of the first sealing sheet exceeds the free end of the second sealing sheet, and the fixed end of the first sealing sheet and the fixed end of the second sealing sheet are fixedly connected by spot welding every 30 cm (in practice, 15 cm, 20 cm, 40 cm or 50 cm, etc.); the thermal expansion coefficients of the first sealing sheet and the second sealing sheet are different.

[0044] Example 2

[0045] On the basis of Example 1, the following improvements were further made: in order to facilitate installation and to facilitate the cantilever beam structure of the sealing device along the radial direction of the air preheater rotor, the first sealing plate and the second sealing plate are each provided with two or more waist-shaped holes along the length direction, the waist-shaped holes on the first sealing plate and the waist-shaped holes on the second sealing plate are equal in number and position, the length direction of the waist-shaped holes on the first sealing plate is consistent with the width direction of the first sealing plate, and the length direction of the waist-shaped holes on the second sealing plate is consistent with the width direction of the second sealing plate.

[0046] Example 3

[0047] On the basis of Example 2, the following improvements are made: In order to further improve the deformation stability and deformation capacity of the sealing device and enhance the repeatability of hot and cold alternation, Figure 4 As shown, the first expansion gap that penetrates the waist-shaped hole is provided at both ends of the waist-shaped hole in the length direction of the first sealing sheet. In order to take into account the requirements of strength and stability, the length of the first expansion gap at the upper end of the waist-shaped hole is 2 / 3 of the distance from the upper end of the waist-shaped hole to the free end of the first sealing sheet, and the first expansion gap at the lower end of the waist-shaped hole penetrates the edge of the fixed end of the first sealing sheet. Figure 5As shown, a second expansion gap is provided at the fixed end between two adjacent waist-shaped holes on the second sealing sheet, and the second expansion gap is connected to the edge of the fixed end of the second sealing sheet. The second expansion gap is opened in the middle of the two adjacent waist-shaped holes. The length of the second expansion gap is 2 / 3 of the width of the second sealing sheet. The widths of the first expansion gap and the second expansion gap are not greater than 1 mm.

[0048] In order to prevent the above-mentioned sealing device from rubbing against the fan plate when it is deformed by heat, causing an increase in the rotor drive current, and to prevent the sealing device from being deformed by pressure and damaged, the free end of the first sealing sheet is provided with more than two separation gaps along the length direction, the length direction of the separation gaps is consistent with the width direction of the first sealing sheet, and the separation gaps are connected with the edge of the free end of the first sealing sheet. The free end of the first sealing sheet is provided with a separation gap every 30 cm (in practice, 15 cm, 20 cm, 40 cm or 50 cm, etc.) along the length direction, the length of the separation gap is generally 15 mm (in practice, 10 mm or 20 mm, etc., etc.), and the width of the separation gap is not more than 1 mm, so as to absorb the pressure deformation caused by rubbing at a certain position in sections.

[0049] Example 4

[0050] On the basis of Example 3, the following improvements are made: the fixed end of the first sealing sheet and the fixed end of the second sealing sheet, and the middle position of each two waist-shaped holes are fixedly connected by spot welding; all spot welding connection points are located on the same straight line. The thermal expansion coefficient of the first sealing sheet is about 25% greater or less than the thermal expansion coefficient of the second sealing sheet (in practice, it can also be 30%, 40%, 50% or 60%, etc.). Figure 1 As shown, the first sealing sheet is bent at about 30° at a position 15 mm (in practice, 10 mm or 20 mm, etc.) beyond the free end of the second sealing sheet.

[0051] The above-mentioned installation structure of the thermal compensation sealing device applied to the hot end of the air preheater, the fixed ends of the first sealing plate and the second sealing plate are installed on the radial partition of the air preheater rotor, the thermal compensation sealing device applied to the hot end of the air preheater and the hot end fan plate of the air preheater form a sealing pair; the length directions of the first sealing plate and the second sealing plate are consistent with the radial length of the air preheater rotor; in order to achieve the purpose that the sealing plate basically does not follow the rotor to undergo "mushroom-shaped" deformation, the ends of the first sealing plate and the second sealing plate in the length direction close to the center of the air preheater rotor are completely fixedly connected to the radial partition of the air preheater rotor, and the ends of the first sealing plate and the second sealing plate in the length direction away from the center of the air preheater rotor are non-completely fixedly connected to the radial partition of the air preheater rotor, that is, the non-completely fixed connection end of the sealing device is allowed to have a certain sliding distance relative to the hot end radial partition, and on the hot end radial partition, the thermal compensation sealing device of the hot end of the air preheater presents a cantilever beam structure along the radial direction of the air preheater rotor.

[0052] In order to further improve the stability of sealing gap control and avoid errors in the design and installation process that may cause the sealing device to rub against the fan plate after being heated, a gap of 1-15mm should be reserved between the upper end surface of the above-mentioned thermal compensation sealing device and the fan plate at the hot end of the air preheater during installation.

[0053] In order to ensure that the end of the sealing device close to the central tube of the air preheater rotor is completely fixedly connected to the hot end radial partition, the ends of the first and second sealing plates close to the central tube of the air preheater rotor in the length direction are completely fixedly connected to the hot end radial partition by means of a fixing bolt assembly and welding. The ends of the first and second sealing plates away from the center of the air preheater rotor in the length direction are non-completely fixedly connected to the air preheater rotor radial partition by means of a fixing bolt assembly. The mounting bolts in the fixing bolt assembly pass through the waist-shaped holes of the first and second sealing plates at the same time, and the length of the waist-shaped holes of the first and second sealing plates is greater than the outer diameter of the mounting bolts, so that the first and second sealing plates can have a certain slippage relative to the radial partition of the air preheater rotor during cold and hot deformation. The length direction of the aforementioned waist-shaped holes is consistent with the width direction of the first and second sealing plates.

[0054] like Figure 1 As shown, the fixing bolt assembly includes mounting bolts, mounting gaskets, mounting buffer plates and mounting pressure plates, and the mounting gaskets and mounting buffer plates each have two pieces; the mounting bolts sequentially pass through the mounting gaskets, the radial partitions of the air preheater rotor, the mounting buffer plates, the waist-shaped holes of the first sealing sheet, the waist-shaped holes of the second sealing sheet, the mounting buffer plates, the mounting pressure plates and the mounting gaskets, and are fixed by nuts. The buffer plate is made of high-temperature resistant mica plate with a thickness of 2.5 mm.

[0055] It has been verified in practice that the thermal expansion coefficients of the first sealing sheet and the second sealing sheet are different, that is, the expansion amounts of the two after being heated are different. After being heated, the one with a larger expansion amount will transfer the expansion driving force to the other side through spot welding fixation; since the spot welding fixing point is arranged at the lower end (fixed end) in the width direction of the sealing device, the expansion end of the sealing sheet is subjected to compressive stress under the action of large thermal stress; and the sealing device is installed on the radial partition of the hot end of the air preheater, one end of the sealing sheet is fixedly connected and the other end is not completely fixedly connected. After being heated, the sealing device as a whole will bend and deform upward at the end of the not completely fixed connection, showing a trend opposite to the deformation of the rotor partition (due to uneven heating of the upper and lower parts of the rotor partition and weakened rigidity after heating, the partition The plate tends to droop downward, while the sealing device tends to warp upward under the action of the different expansion amounts of the two sealing sheets), so as to eliminate the traditional triangular air leakage area of ​​the air preheater and significantly reduce the air leakage rate of the air preheater; through the setting of the first expansion gap and the second expansion gap, the deformation of the sealing device when heated is increased, the elastic deformability is enhanced, the repeatability of alternating hot and cold is enhanced, the deformation is more stable, and the service life is longer, and the first expansion gap and the second expansion gap are staggered. The distribution is better to ensure the uniformity of force, deformation and recovery; it has the comprehensive advantages of low cost, high reliability, good sealing performance and long service life; further, the setting of the separation gap prevents the sealing device from being damaged by pressure deformation.

[0056] Through practice, the thermal compensation sealing devices in the above examples have: large thermal deformation compensation amount, reaching more than 60mm, which meets the requirements of being applied to super-large air preheaters configured on 1000MW units; good thermal deformation stability and strong repeatability. Even after more than 1000 cold and hot state alternations (each start-up and shutdown process is a cold and hot state alternation process), the initial design thermal deformation deviation does not exceed 10%.

Claims

1. A thermal compensation sealing device applied to the hot end of an air preheater, characterized in that: It comprises a first sealing sheet and a second sealing sheet; the first sealing sheet and the second sealing sheet are both in the shape of long strips; the first sealing sheet is provided with more than two first expansion gaps along the length direction, the length direction of the first expansion gaps is perpendicular to the length direction of the first sealing sheet, and the second sealing sheet is provided with more than two second expansion gaps along the length direction, the length direction of the second expansion gaps is perpendicular to the length direction of the second sealing sheet; the first sealing sheet and the second sealing sheet are bonded to each other, and the length directions of the first sealing sheet and the second sealing sheet are consistent, and the first expansion gap and the second expansion gap are staggered; one end of the first sealing sheet and the second sealing sheet in the width direction is a fixed end, and the other end is a free end, the fixed end of the first sealing sheet and the fixed end of the second sealing sheet are arranged flush, the free end of the first sealing sheet exceeds the free end of the second sealing sheet, and the fixed end of the first sealing sheet and the fixed end of the second sealing sheet are fixedly connected by spot welding; the first sealing sheet and the second sealing sheet have different thermal expansion coefficients; The first sealing sheet and the second sealing sheet are both provided with more than two waist-shaped holes along the length direction; The upper and lower ends of the waist-shaped hole on the first sealing sheet are both provided with a first expansion gap which penetrates the waist-shaped hole; A second expansion gap is arranged at a fixed end in the middle of two adjacent waist-shaped holes on the second sealing sheet, and the second expansion gap is connected with an edge of the fixed end of the second sealing sheet.

2. The thermal compensation sealing device applied to the hot end of the air preheater according to claim 1, characterized in that: The fixed end of the first sealing sheet and the fixed end of the second sealing sheet are attached to each other and are fixedly connected by spot welding every 10-50 cm; the width of the first expansion gap and the second expansion gap is no more than 1 mm.

3. The thermal compensation sealing device applied to the hot end of an air preheater according to claim 1 or 2, characterized in that: The thermal expansion coefficient of the first sealing sheet is 20 to 60% greater or less than the thermal expansion coefficient of the second sealing sheet.

4. The thermal compensation sealing device applied to the hot end of an air preheater according to claim 1 or 2, characterized in that: The number and position of the waist-shaped holes on the first sealing sheet are equal to those on the second sealing sheet. The length direction of the waist-shaped holes on the first sealing sheet is consistent with the width direction of the first sealing sheet, and the length direction of the waist-shaped holes on the second sealing sheet is consistent with the width direction of the second sealing sheet.

5. The thermal compensation sealing device applied to the hot end of an air preheater according to claim 1 or 2, characterized in that: The free end of the first sealing sheet is provided with more than two separation gaps along the length direction. The length direction of the separation gaps is consistent with the width direction of the first sealing sheet. The separation gaps are connected to the edge of the free end of the first sealing sheet.

6. The thermal compensation sealing device applied to the hot end of an air preheater according to claim 5, characterized in that: A separation gap is formed at the free end of the first sealing sheet at intervals of 10-50 cm along the length direction, the length of the separation gap is 10-20 mm, and the width of the separation gap is no greater than 1 mm.

7. The thermal compensation sealing device applied to the hot end of an air preheater according to claim 1 or 2, characterized in that: The length of the second expansion gap is 1 / 2 to 5 / 6 of the width of the second sealing sheet.

8. The thermal compensation sealing device applied to the hot end of an air preheater according to claim 1 or 2, characterized in that: The free end of the first sealing sheet beyond the second sealing sheet is bent at 20 to 30 degrees.

9. The installation structure of the thermal compensation sealing device applied to the hot end of the air preheater according to any one of claims 1 to 8, characterized in that: The fixed ends of the first sealing sheet and the second sealing sheet are installed on the radial partition of the air preheater rotor, and the thermal compensation sealing device applied to the hot end of the air preheater and the hot end fan plate of the air preheater form a sealing pair; the length directions of the first sealing sheet and the second sealing sheet are consistent with the radial length of the air preheater rotor; the ends of the first sealing sheet and the second sealing sheet in the length direction close to the center of the air preheater rotor are completely fixedly connected to the radial partition of the air preheater rotor, and the ends of the first sealing sheet and the second sealing sheet in the length direction away from the center of the air preheater rotor are not completely fixedly connected to the radial partition of the air preheater rotor; a sealing gap of at least 1-15mm is reserved between the free end of the first sealing sheet and the hot end fan plate of the air preheater.

10. The mounting structure according to claim 9, characterized in that: One end of the first sealing plate and the second sealing plate in the length direction close to the central tube of the air preheater rotor is completely fixedly connected to the hot end radial partition by means of a fixing bolt assembly and welding; one end of the first sealing plate and the second sealing plate in the length direction away from the center of the air preheater rotor is non-completely fixedly connected to the radial partition of the air preheater rotor by means of a fixing bolt assembly, and the mounting bolts in the fixing bolt assembly pass through the waist-shaped holes of the first sealing plate and the second sealing plate at the same time, and the length of the waist-shaped holes of the first sealing plate and the second sealing plate is greater than the outer diameter of the mounting bolts.

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