A sealing device for hot end of air preheater

Abstract

The present invention discloses a sealing device for the hot end of an air preheater, comprising a sealing sheet and a driving splint; there are more than two driving splints distributed on the sealing sheet, both ends of the driving splints are connected to the sealing sheet, and the expansion coefficient of the driving splints is greater than the expansion coefficient of the sealing sheet. The sealing device for the hot end of an air preheater of the present invention installs a driving splint with an expansion coefficient greater than that of the sealing sheet at the free end of the sealing sheet, and the free end of the sealing sheet is warped and deformed upward by the thermal expansion of the driving splint to offset the tendency of the partition to droop downward, thereby eliminating the traditional triangular air leakage area of ​​the air preheater and significantly reducing the air leakage rate of the air preheater; it has the comprehensive advantages of low cost, high reliability, good sealing performance, and long service life.

Description

Technical Field

[0001] The invention relates to a sealing device for a hot end of an air preheater, belonging to the field of sealing devices. 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 current engineering projects: one is the fan plate automatic tracking system (LCS for short) equipped by the three major domestic host manufacturers (Dongfang Guo, Harbin Guo and Shanghai Guo); 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 sheet with the fan plate. The sealing sheet automatically sticks to the fan plate and the fan plate automatically tracks the sealing sheet to achieve the purpose of reducing air leakage. However, both solutions have the following 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 shows from the side 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] The present invention provides a sealing device for the hot end of an air preheater, wherein a plurality of driving clamps with a larger expansion coefficient than the sealing plate are installed on the sealing plate, and the free end of the sealing plate is driven to warp and deform upward by the thermal expansion of the driving clamps, so as to offset the tendency of the partition plate to droop downward, thereby eliminating the traditional triangular air leakage area of ​​the air preheater and significantly reducing the air leakage rate of the air preheater.

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

[0008] A sealing device for the hot end of an air preheater comprises a sealing sheet and a driving clamping plate; there are more than two driving clamping plates distributed on the sealing sheet, both ends of the driving clamping plates are connected to the sealing sheet, and the expansion coefficient of the driving clamping plate is greater than the expansion coefficient of the sealing sheet.

[0009] When in use, the fixed end of the sealing sheet is installed on the radial partition of the hot end of the air preheater, forming a sealing pair with the hot end fan-shaped plate of the air preheater, and the length direction of the sealing sheet is consistent with the radial length of the air preheater rotor; after heating, since the expansion coefficient of the driving splint is greater than the expansion coefficient of the sealing sheet, the free end of the sealing sheet will bend and deform upward, showing a trend opposite to the deformation of the rotor partition (the rotor partition has a tendency to droop downward due to uneven heating from top to bottom and weakened rigidity after heating, resulting in a "mushroom-shaped" deformation, and the sealing sheet will bend upward under the drive of the expansion of the driving splint), thereby eliminating the traditional triangular air leakage area of ​​the air preheater and significantly reducing the air leakage rate of the air preheater.

[0010] In order to improve the deformation stability, the hot end sealing device of the air preheater further includes a ball, which is arranged between the sealing sheet and the driving clamping plate, and the two sides of the ball are respectively beyond the sealing sheet and the driving clamping plate. When the sealing device is installed, a buffer plate, a pressure plate, etc. are arranged on both sides. The arrangement of the ball improves the sliding friction between the buffer plate, the pressure plate or the radial partition and the sealing device into rolling friction, avoiding the problem of poor deformation stability caused by excessive installation friction. The process is easy to control and can better ensure the sealing effect.

[0011] In order to improve the stability and repeatability of the device's thermal deformation and further reduce the air leakage rate, the sealing sheet facing the drive clamp is provided with an expansion gap from the bottom. The setting of the expansion gap increases the deformation of the sealing device when heated, enhances the elastic deformation, enhances the repeatability of alternating hot and cold, makes the deformation more stable, and prolongs the service life.

[0012] The applicant has found through practical research that the expansion drive of the driving clamp plate, coupled with the design of the expansion gap from the bottom of the sealing sheet directly opposite to the driving clamp plate, can better offset the downward droop of the partition plate with the upward warping of the sealing sheet, so as to better eliminate the traditional triangular air leakage area of ​​the air preheater and significantly reduce the air leakage rate of the air preheater. When thermally expanded, the expansion gap will be widened under the expansion drive of the driving clamp plate, thereby ensuring the upward warping amount of the sealing sheet and the stability and repeatability of thermal deformation.

[0013] In order to save costs, one end of the sealing sheet in the length direction is a fixed end, and the other end in the length direction is a free end, and the driving clamping plates are distributed on the sealing sheet outside the fixed end.

[0014] In order to better ensure the upward warping amount of the sealing device, reduce the amount of driving clamps and reduce costs, the two ends of the bottom of the driving clamps are fixedly connected to the sealing sheet. Further preferably, the two ends of the bottom of the driving clamps are fixedly connected to the bottom of the sealing sheet.

[0015] In order to ensure the stability of the upward warping of the sealing sheet, the middle position of the top of the driving clamp is fixedly connected to the sealing sheet, that is, the driving clamp and the sealing sheet are fixed at three points, namely, the middle of the top of the driving clamp and the two ends of the bottom of the driving clamp.

[0016] In order to facilitate installation and ensure integrity, sealing and stability, the sealing device for the hot end of the air preheater also includes a wrapping sheet and a fixing clamping plate; the wrapping sheet is arranged along the length direction of the sealing sheet;

[0017] One end of the sealing sheet and the wrapping sheet in the width direction is aligned as the expansion end, and the other end of the sealing sheet in the width direction is beyond the wrapping sheet as the sealing end, the expansion end is the bottom of the sealing sheet and the wrapping sheet, and the sealing end is the top of the sealing sheet and the wrapping sheet;

[0018] One end of the sealing sheet and the wrapping sheet in the length direction is a fixed end, and the other end in the length direction is a free end. The fixed splint is installed between the fixed ends of the sealing sheet and the wrapping sheet. The driving splint is installed between the sealing sheet and the wrapping sheet outside the fixed end. Both ends of the bottom of the driving splint are fixedly connected to the sealing sheet and the wrapping sheet. The sealing sheet and the wrapping sheet facing the driving splint are provided with expansion gaps starting from the bottom. The expansion coefficient of the driving splint is greater than the expansion coefficient of the sealing sheet and the wrapping sheet.

[0019] Further preferably, both ends of the bottom of the driving splint are fixedly connected to the bottom of the sealing sheet and the bottom of the wrapping sheet.

[0020] When thermally expanded, driven by the expansion of the driving splint, the expansion gap between the sealing sheet and the wrapping sheet will widen, and the sealing sheet and the wrapping sheet will warp upward, with good thermal deformation stability and strong repeatability.

[0021] For the convenience of installation and control, the driving clamping plate and the fixed clamping plate have the same thickness, that is, the fixed clamping plate and the driving clamping plate located between the sealing sheet and the wrapping sheet and at the fixed end and the free end have the same thickness.

[0022] In order to improve the thermal deformation stability of the device, the expansion coefficients of the fixed clamping plate, the sealing sheet and the wrapping sheet are the same. Further preferably, the expansion coefficient of the driving clamping plate is 10-60% greater than the expansion coefficient of the fixed clamping plate, the sealing sheet or the wrapping sheet.

[0023] In order to ensure the stability of the upward warping of the sealing device, the middle position of the top of the driving clamp is fixedly connected to the sealing sheet and the wrapping sheet. That is, the driving clamp is fixed to the sealing sheet and the wrapping sheet at three points, namely, the middle of the top of the driving clamp and the two ends of the bottom of the driving clamp.

[0024] In order to improve the installation stability, the sealing device for the hot end of the air preheater also includes a ball bearing. The sealing sheet and the wrapping sheet are each provided with more than two waist-shaped holes along the length direction. The number of waist-shaped holes on the sealing sheet and the wrapping sheet is equal and the position is relative. The ball bearing is arranged between the sealing sheet and the wrapping sheet and is installed along the periphery of the waist-shaped holes without a fixed clamping plate. The two sides of the ball bearing extend beyond the sealing sheet and the wrapping sheet respectively. When the sealing device is installed, a buffer plate, a pressure plate, etc. are arranged on both sides. The arrangement of the ball bearing improves the sliding friction between the buffer plate, the pressure plate or the radial partition and the sealing device into rolling friction, avoiding the problem of poor deformation stability caused by excessive installation friction. The process is easy to control and can better ensure the sealing effect.

[0025] To facilitate installation and control, each driving splint faces a waist-shaped hole on the sealing plate, and the expansion gaps on the sealing plate and the wrapping plate facing each driving splint start from the bottom and pass through the bottom of the waist-shaped hole; a through hole no smaller than the waist-shaped hole is provided on the driving splint facing the waist-shaped hole, which does not affect the installation.

[0026] On the sealing sheet and wrapping sheet without fixed splints, a driving splint is installed on each waist-shaped hole of the sealing sheet, or driving splints are installed on the waist-shaped holes of the sealing sheet at intervals. The specific amount can be determined according to the product model and working conditions. As long as the upward warping deformation of the sealing device can offset the downward drooping amount of the partition, when a driving splint is provided on the waist-shaped hole, the ball passes through the driving splint and exceeds the sealing sheet and wrapping sheet on both sides.

[0027] In order to improve the sealing performance, when the driving splints are installed on the waist-shaped holes at intervals on the sealing plates and wrapping plates without fixed splints, a filling plate with the same expansion coefficient as the sealing plate can be set around the waist-shaped holes where the driving splints are not installed. Of course, in order not to affect the installation, the filling plate opposite to the waist-shaped hole must also have a through hole that is not smaller than the waist-shaped hole.

[0028] In order to ensure the stability of the device, at least 3 balls are arranged around each waist-shaped hole without a fixed splint, and the two sides of the balls extend at least 0.5mm beyond the sealing sheet and the wrapping sheet. More preferably, 4 balls are arranged around each waist-shaped hole without a fixed splint, and the diameter of the balls is 8-10mm.

[0029] In order to further improve the stability and repeatability of thermal deformation, the top and bottom of the waist-shaped holes of the sealing sheet and the wrapping sheet without a fixed splint are provided with expansion gaps that penetrate the waist-shaped holes, and the expansion gaps on the sealing sheet and the wrapping sheet are lower than the top of the wrapping sheet; the expansion gaps on the sealing sheet and the wrapping sheet are relative to each other, and the expansion gaps on the sealing sheet and the wrapping sheet are perpendicular to the length direction of the sealing sheet and the wrapping sheet.

[0030] The sealing sheet of the present application can be a straight sheet, a bent sheet or a corrugated sheet. Preferably, the sealing sheet is a bent sheet. In order to avoid collision and abrasion, it is further preferred that the top of the sealing sheet is bent at 20 to 30 degrees. That is, the top of the sealing sheet is provided with a folded edge that deviates from the width direction of the sealing sheet by 20 to 30 degrees.

[0031] 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.

[0032] 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.

[0033] 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.

[0034] Technologies not particularly limited in the present invention are all prior arts.

[0035] The sealing device for the hot end of the air preheater of the present invention has a driving clamp with an expansion coefficient greater than that of the sealing plate installed at the free end of the sealing plate, and the free end of the sealing plate is driven to bend and deform upward by the thermal expansion of the driving clamp, so as to offset the tendency of the partition to droop downward, thereby eliminating the traditional triangular air leakage area of ​​the air preheater and significantly reducing the air leakage rate of the air preheater; it has the comprehensive advantages of low cost, high reliability, good sealing performance, and long service life; further, through the provision of an expansion gap, the deformation amount 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; through the provision of a wrapping plate and a fixed clamp, the stability and controllability of the device are further improved; through the provision of balls, the deformation stability of the sealing device in a clamped state is improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 This is a schematic diagram of the sealing sheet structure of the present invention;

[0037] Figure 2 This is a schematic diagram of the driving splint structure of the present invention;

[0038] Figure 3 This is a schematic diagram of the structure of the wrapping sheet of the present invention;

[0039] Figure 4 This is a schematic structural diagram of a sealing device for a hot end of an air preheater according to the present invention;

[0040] Figure 5 for Figure 4 Enlarged view of point E in the middle;

[0041] Figure 6 This is a schematic diagram of the installation of a sealing device for the hot end of an air preheater according to the present invention;

[0042] In the figure, 1-sealing sheet; 12-sealing sheet expansion gap; 13-sealing sheet waist hole; 14-sealing sheet ball mounting hole; 15-sealing sheet bending line; 2-driving splint; 21-driving splint ball mounting hole; 22-driving splint waist hole; 3-wrapping sheet; 32-wrapping sheet expansion gap; 33-wrapping sheet waist hole; 34-wrapping sheet ball mounting hole; 4-ball; 5-mounting pressure plate; 6-radial partition; 7-fan plate; 8-mounting fasteners. DETAILED DESCRIPTION

[0043] 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.

[0044] The directions or positional relationships indicated by the following “length”, “width”, “thickness”, “up”, “down”, “front”, “back”, “left”, “right”, “vertical”, “horizontal”, “top”, “bottom”, “inside”, “outside”, “clockwise”, “counterclockwise”, etc. are based on the directions or positional relationships shown in the accompanying drawings and are only for the convenience of describing the present invention and simplifying the description. They do not indicate or imply that the referred device or element must have a specific direction, be constructed and operate in a specific direction, and therefore should not be understood as limiting the present invention. Example

[0045] A sealing device for the hot end of an air preheater comprises a sealing sheet and a driving clamping plate; there are more than two driving clamping plates distributed on the sealing sheet, both ends of the driving clamping plates are connected to the sealing sheet, and the expansion coefficient of the driving clamping plate is greater than the expansion coefficient of the sealing sheet.

[0046] When in use, the fixed end of the sealing sheet is installed on the radial partition of the hot end of the air preheater, forming a sealing pair with the hot end fan-shaped plate of the air preheater, and the length direction of the sealing sheet is consistent with the radial length of the air preheater rotor; after heating, since the expansion coefficient of the driving splint is greater than the expansion coefficient of the sealing sheet, the free end of the sealing sheet will bend and deform upward, showing a trend opposite to the deformation of the rotor partition (the rotor partition has a tendency to droop downward due to uneven heating from top to bottom and weakened rigidity after heating, resulting in a "mushroom-shaped" deformation, and the sealing sheet will bend upward under the drive of the expansion of the driving splint), thereby eliminating the traditional triangular air leakage area of ​​the air preheater and significantly reducing the air leakage rate of the air preheater. Example

[0047] On the basis of Example 1, the following improvements are further made: in order to improve deformation stability, the sealing device for the hot end of the air preheater further includes a ball, which is arranged between the sealing sheet and the driving clamping plate, and the two sides of the ball are respectively beyond the sealing sheet and the driving clamping plate. When the sealing device is installed, a buffer plate, a pressure plate, etc. are arranged on both sides. The arrangement of the ball improves the sliding friction between the buffer plate, the pressure plate or the radial partition and the sealing device into rolling friction, avoiding the problem of poor deformation stability caused by excessive installation friction, and the process is easy to control and can better ensure the sealing effect. Example

[0048] On the basis of Example 2, the following improvements are further made: in order to improve the stability and repeatability of the device's deformation when heated and further reduce the air leakage rate, the sealing sheet directly opposite to the driving clamp is provided with an expansion gap from the bottom. The setting of the expansion gap increases the deformation of the sealing device when heated, enhances the elastic deformation, enhances the repeatability of alternating hot and cold, makes the deformation more stable, and prolongs the service life.

[0049] Practice has proven that the expansion drive of the driving splint, coupled with the design of the expansion gap from the bottom of the sealing sheet facing the driving splint, can better offset the downward droop of the partition with the upward warping of the sealing sheet, so as to better eliminate the traditional triangular air leakage area of ​​the air preheater and significantly reduce the air leakage rate of the air preheater. When heated and expanded, the expansion gap will be widened under the expansion drive of the driving splint, thereby ensuring the upward warping amount of the sealing sheet and the stability and repeatability of thermal deformation. Example

[0050] On the basis of Example 5, the following improvements are further made: one end of the sealing sheet in the length direction is a fixed end, and the other end in the length direction is a free end, and the driving clamping plate is distributed on the sealing sheet outside the fixed end, that is, the driving clamping plate is not provided at the fixed end. In order to better ensure the upward warping amount of the sealing device and reduce the amount of the driving clamping plate, the bottom ends of the driving clamping plate are fixedly connected to the bottom of the sealing sheet. Example

[0051] On the basis of Example 4, the following improvements are further made: in order to ensure the stability of the upward warping of the sealing sheet, the middle position of the top of the driving clamp is fixedly connected to the sealing sheet. That is, the driving clamp and the sealing sheet are fixed at three points, namely the middle of the top of the driving clamp and the two ends of the bottom of the driving clamp. Example

[0052] On the basis of Example 5, the following improvements are further made: in order to facilitate installation and ensure sealing and stability, the sealing device for the hot end of the air preheater further comprises a wrapping sheet and a fixed clamping plate; the wrapping sheet is arranged along the length direction of the sealing sheet; the driving clamping plate and the fixed clamping plate have the same thickness; the fixed clamping plate, the sealing sheet and the wrapping sheet have the same expansion coefficient;

[0053] One end of the sealing sheet and the wrapping sheet in the width direction is aligned as the expansion end, and the other end of the sealing sheet in the width direction is beyond the wrapping sheet as the sealing end, the expansion end is the bottom of the sealing sheet and the wrapping sheet, and the sealing end is the top of the sealing sheet and the wrapping sheet;

[0054] One end of the sealing sheet and the wrapping sheet in the length direction is a fixed end, and the other end in the length direction is a free end, a fixed splint is installed between the fixed ends of the sealing sheet and the wrapping sheet, a driving splint is installed between the sealing sheet and the wrapping sheet outside the fixed end, both ends of the bottom of the driving splint are fixedly connected to the bottom of the sealing sheet and the bottom of the wrapping sheet, the middle position of the top of the driving splint is fixedly connected to the sealing sheet and the wrapping sheet, the sealing sheet and the wrapping sheet facing the driving splint are provided with expansion gaps starting from the bottom, and the expansion coefficient of the driving splint is 20% greater than the expansion coefficient of the sealing sheet (in practice, it can also be 15%, 30% or 40%, etc.).

[0055] When thermally expanded, driven by the expansion of the driving splint, the expansion gap between the sealing sheet and the wrapping sheet will widen, and the sealing sheet and the wrapping sheet will warp upward, with good thermal deformation stability and strong repeatability. Example

[0056] On the basis of Example 6, the following improvements were further made: Figure 4-5 As shown, in order to improve the installation stability, the sealing device for the hot end of the air preheater also includes a ball bearing, and the sealing sheet and the wrapping sheet are each provided with more than two waist-shaped holes along the length direction. The number of waist-shaped holes on the sealing sheet and the wrapping sheet is equal and the position is opposite. The ball bearing is arranged between the sealing sheet and the wrapping sheet, and is installed along the periphery of the waist-shaped holes without a fixed clamping plate. The two sides of the ball bearing extend beyond the sealing sheet and the wrapping sheet respectively. When the sealing device is installed, a buffer plate, a pressure plate, etc. are arranged on both sides of the sealing sheet and the wrapping sheet. The arrangement of the ball bearing improves the sliding friction between the buffer plate, the pressure plate or the radial partition and the sealing device into rolling friction, and the process is easy to control and can better ensure the implementation effect.

[0057] To facilitate installation and control, each driving splint faces a waist-shaped hole on the sealing plate, and the expansion gaps on the sealing plate and the wrapping plate facing each driving splint start from the bottom and pass through the bottom of the waist-shaped hole; a through hole no smaller than the waist-shaped hole is provided on the driving splint facing the waist-shaped hole, which does not affect the installation. Example

[0058] On the basis of Example 7, the following improvements were further made: Figure 1 and 3 As shown, on the sealing sheet and the wrapping sheet without a fixed splint: each waist-shaped hole of the sealing sheet is correspondingly installed with a piece as shown in FIG. Figure 2 The driving splint shown in the figure has 4 balls with a diameter of 9 mm arranged around each waist-shaped hole. The balls pass through the driving splint and extend beyond the sealing sheet and the wrapping sheet on both sides. The balls extend beyond the sealing sheet and the wrapping sheet on both sides by at least 0.5 mm. Example

[0059] On the basis of Example 8, the following improvements were further made: Figure 1 and 3 As shown, in order to further improve the stability and repeatability of thermal deformation, the top and bottom of the waist-shaped hole of the sealing sheet and the wrapping sheet without a fixed splint are provided with expansion gaps that penetrate the waist-shaped hole, and the expansion gaps on the sealing sheet and the wrapping sheet are lower than the top of the wrapping sheet; the expansion gaps on the sealing sheet and the wrapping sheet are relative, and the expansion gaps on the sealing sheet and the wrapping sheet are perpendicular to the length direction of the sealing sheet and the wrapping sheet. The sealing sheet can be a straight sheet, a bent sheet or a corrugated sheet. In the embodiment, taking the bent sheet as an example, the top of the sealing sheet is bent at 30°.

[0060] like Figure 6As shown, the radial partition, sealing plate, driving clamp, wrapping plate, mounting plate and gasket are fixed in this order with mounting fasteners, and the balls extending beyond the sealing plate and the wrapping plate are in direct contact with the radial partition and the mounting plate, so that the deformation stability will not be deteriorated due to excessive installation friction. The deformation stability is good and the sealing effect can be guaranteed. During installation, a gap of 1-15mm is reserved between the upper end surface of the thermal compensation sealing device and the hot end fan plate of the air preheater.

[0061] It has been verified in practice that the sealing devices for the hot end of the air preheater in the above-mentioned examples install a driving clamp with an expansion coefficient greater than that of the sealing plate at the free end of the sealing plate, and the free end of the sealing plate is driven to bend and deform upward by the thermal expansion of the driving clamp, so as to offset the tendency of the partition to droop downward, thereby eliminating the traditional triangular air leakage area of ​​the air preheater and significantly reducing the air leakage rate of the air preheater; it has the comprehensive advantages of low cost, high reliability, good sealing performance and long service life; further, through the setting of the expansion gap, the deformation amount of the sealing device when heated is increased, the elastic deformation is enhanced, the repeatability of alternating hot and cold is enhanced, the deformation is more stable, and the service life is longer; through the setting of the wrapping plate and the fixed clamp, the stability and controllability of the device are further improved; through the setting of the ball, the deformation stability of the sealing device in the clamped state is improved.

[0062] Through practice, the thermal compensation sealing devices in the above-mentioned examples have a large thermal deformation compensation amount of more than 60mm, which meets the application requirements of large air preheaters configured on coal-fired power generation units of various capacity levels; because balls are arranged between the sealing plate and the driving clamping plate, the rolling friction is small, and the expansion gap is reasonably designed, the thermal deformation is very stable and repeatable. Even after more than 1,000 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 ±5%.

Claims

1. A sealing device for the hot end of an air preheater, characterized in that: It includes a sealing sheet and a driving splint; there are more than two driving splints distributed on the sealing sheet, both ends of the driving splints are connected to the sealing sheet, and the expansion coefficient of the driving splint is greater than the expansion coefficient of the sealing sheet; It also includes a ball, which is arranged between the sealing sheet and the driving clamping plate, and the two sides of the ball are respectively beyond the sealing sheet and the driving clamping plate; The sealing sheets facing the driving clamping plate are all provided with expansion gaps starting from the bottom; The two ends of the bottom of the driving clamping plate are fixedly connected to the sealing sheet; The middle position of the top of the driving clamping plate is fixedly connected to the sealing sheet; It also includes a wrapping sheet and a fixing clamp; the wrapping sheet is arranged along the length direction of the sealing sheet; One end of the sealing sheet and the wrapping sheet in the width direction is aligned as the expansion end, and the other end of the sealing sheet in the width direction is beyond the wrapping sheet as the sealing end, the expansion end is the bottom of the sealing sheet and the wrapping sheet, and the sealing end is the top of the sealing sheet and the wrapping sheet; One end of the sealing sheet and the wrapping sheet in the length direction is a fixed end, and the other end in the length direction is a free end. The fixed splint is installed between the fixed ends of the sealing sheet and the wrapping sheet. The driving splint is installed between the sealing sheet and the wrapping sheet outside the fixed end. Both ends of the bottom of the driving splint are fixedly connected to the sealing sheet and the wrapping sheet. The sealing sheet and the wrapping sheet facing the driving splint are provided with expansion gaps starting from the bottom. The expansion coefficient of the driving splint is greater than the expansion coefficient of the sealing sheet and the wrapping sheet.

2. The sealing device for the hot end of the air preheater according to claim 1, characterized in that: One end of the sealing sheet in the length direction is a fixed end, and the other end in the length direction is a free end. The driving clamping plates are distributed on the sealing sheet outside the fixed end.

3. The sealing device for the hot end of an air preheater according to claim 1 or 2, characterized in that: The driving splint and the fixed splint have the same thickness; the fixed splint, the sealing sheet and the wrapping sheet have the same expansion coefficient.

4. The sealing device for the hot end of an air preheater according to claim 1 or 2, characterized in that: It also includes balls. The sealing sheet and the wrapping sheet are each provided with more than two waist-shaped holes along the length direction. The number of waist-shaped holes on the sealing sheet and the wrapping sheet are equal and the positions are opposite. The balls are arranged between the sealing sheet and the wrapping sheet and are installed along the periphery of the waist-shaped holes without a fixed splint. The two sides of the balls extend beyond the sealing sheet and the wrapping sheet respectively.

5. The sealing device for the hot end of the air preheater according to claim 4, characterized in that: Each driving splint faces a waist-shaped hole on the sealing sheet, and the expansion gaps on the sealing sheet and the wrapping sheet facing each driving splint start from the bottom and pass through the bottom of the waist-shaped hole; a through hole not smaller than the waist-shaped hole is provided on the driving splint facing the waist-shaped hole.

6. The sealing device for the hot end of the air preheater according to claim 4, characterized in that: On the sealing sheet and wrapping sheet without fixed splints: a driving splint is installed on each waist-shaped hole of the sealing sheet, or driving splints are installed on the waist-shaped holes of the sealing sheet at intervals. When driving splints are provided on the waist-shaped holes, the ball passes through the driving splints and exceeds the sealing sheet and the wrapping sheet on both sides.

7. The sealing device for the hot end of an air preheater according to claim 4, characterized in that: At least three balls are arranged around each waist-shaped hole without a fixed splint, and both sides of the balls extend beyond the sealing sheet and the wrapping sheet by at least 0.5 mm.

8. The sealing device for the hot end of an air preheater according to claim 7, characterized in that: Four balls are arranged around each waist-shaped hole without a fixed splint, and the diameter of the balls is 8-10mm.

9. The sealing device for the hot end of an air preheater according to claim 4, characterized in that: The top and bottom of the waist-shaped holes of the sealing sheet and the wrapping sheet without a fixed splint are both provided with expansion gaps that penetrate the waist-shaped holes, and the expansion gaps on the sealing sheet and the wrapping sheet are both lower than the top of the wrapping sheet; the expansion gaps on the sealing sheet and the wrapping sheet are relatively positioned, and the expansion gaps on the sealing sheet and the wrapping sheet are both perpendicular to the length direction of the sealing sheet and the wrapping sheet.

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