A pre-pressed bimetallic thermal expansion elastic compensation sealing device and its installation structure

Abstract

The present invention discloses a pre-stressed bimetallic thermal expansion elastic compensation sealing device and its mounting structure. The compensation sealing device comprises a self-warping sealing plate, a thermal expansion displacement plate, and a pre-stressing mechanism. The self-warping sealing plate comprises a sealing sheet and a shrinkage strip, the shrinkage strip being fixed to the sealing sheet and having a linear expansion coefficient smaller than that of the sealing sheet. The thermal expansion displacement plate is superimposed and abuts against one side of the sealing sheet, with the top of the sealing sheet protruding above the thermal expansion displacement plate, and the linear expansion coefficients of the thermal expansion displacement plate and the sealing sheet are different. The pre-stressing mechanism comprises a stop block, a stop rail, and a pressure block. The angle between the guide of the stop rail and the radial direction of the air preheater rotor is non-zero. The stop block can move along the stop rail or be laterally separated from the stop rail. The pressure block is located at the top of the stop block to limit its upward movement. The stop block is connected to the sealing sheet, and the stop rail and the pressure block are both connected to the thermal expansion displacement plate. The present invention significantly increases the compensation range and allows for elastic yield, making it safe and reliable.

Description

Technical Field

[0001] The invention relates to a pre-pressed bimetallic thermal expansion elastic compensation sealing device and an installation structure thereof, belonging to the field of sealing devices. Background Art

[0002] A rotary air preheater is a heat exchange device used in large coal-fired power plant boilers. It uses the heat from the boiler flue gas to heat the air required for combustion, thereby improving the boiler's efficiency. When the air preheater rotor goes from cold to hot, it deforms in a "mushroom-like" pattern due to the different temperatures of the upper and lower end surfaces and the weakening of the steel's rigidity after being heated. Traditional rigid sealing plates are fixed to the rotor baffles in sections with bolts. As the rotor baffles deform, the air leakage gap also changes. Based on the mechanism of the rotor's "mushroom-like" deformation, appropriate cold-state clearances are reserved at the axial and cold-end radial positions, so that the dynamic and static clearances approach zero when hot. Although the reserved cold-state clearance at the hot-end radial position is very small, a larger triangular air leakage area will form when hot.

[0003] To reduce the triangular air leakage area and lower the air preheater leakage rate, two technical approaches are currently commonly adopted: the automatic sector plate tracking system (LCS), used by the three major domestic power plant manufacturers (Dongfang Boiler, Harbin Boiler, and Shanghai Boiler); and the recently developed flexible sealing technology. This, understandably, represents two aspects of a single issue: the air preheater sealing problem hinges on the fit between the sealing plate and the sector plate. Both automatic sealing plate contact with the sector plate and automatic sector plate tracking can reduce air leakage. However, both approaches face challenges in practical application. Due to factors such as harsh operating conditions (high temperatures, dust, etc.), maintenance quality, and management level, most power plants fail to operate LCS systems properly or experience suboptimal operational results. Howard, a leading global supplier of rotary air preheaters, has not yet implemented LCS systems on its air preheaters, highlighting the need for further improvement in this technology. Traditional flexible sealing technology, however, suffers from issues such as rapid wear, structural unreliability, and insufficient gap compensation, making it fundamentally unsuitable for project requirements.

[0004] In short, the problem of air leakage in the hot-end radial triangular leakage area has never been completely resolved. Furthermore, as units develop toward larger capacities, the diameter of the air preheater rotor continues to increase. If no measures are taken, the proportion of air leakage in the hot-end radial triangular leakage area will increase. If traditional rigid sealing plates are used and the hot-end fan-shaped plates are not adjustable, the radial outermost gap at the hot end of a 300MW unit will exceed 10mm, that of a 600MW unit will exceed 25mm, and that of a 1000MW unit will be around 50mm. The radial triangular 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, with the absolute leakage to the flue gas side exceeding 3%, and the primary air leakage rate may exceed 30%.

[0005] To solve the above technical problems, the applicant has disclosed an air preheater hot end sealing device (application number: 202210091062.2) that utilizes expansion difference compensation between a sealing sheet and a fixed plate. The device is installed on the hot end radial partition of the air preheater rotor, with one end close to the rotor center tube and the other end close to the rotor outer edge angle steel. The device comprises at least a sealing sheet and a gasket arranged along the thickness direction. The sealing sheet is provided with sealing sheet mounting holes distributed along the length direction, and the gasket is provided with gasket mounting holes distributed along the length direction. The linear expansion coefficient of the sealing sheet is different from that of the gasket; the gasket is arranged along the length direction of the sealing sheet and is relatively fixed by clamping bolts that pass through the sealing sheet mounting holes and the gasket mounting holes at the same time; the end close to the rotor center tube is the expansion starting end, the clamping bolts at the expansion starting end are fully tightened and fixed, and the remaining clamping bolts are not fully tightened and fixed, so that the sealing sheet and the gasket are free to expand toward the other end close to the rotor outer edge angle steel after being heated; at least one set of two-dimensional guide mechanisms is provided between the sealing sheet and the gasket downstream of the expansion starting end. The applicant has discovered through research that the expansion of the sealing plate along the radial direction of the air preheater rotor is greater than the expansion of the gasket. By using a two-dimensional guiding mechanism, the horizontal radial relative displacement is converted into a vertical axial upward displacement, and at the same time, a dislocated displacement is formed, which can effectively compensate for the triangular air leakage area at the hot end of the air preheater. The deformation of the above-mentioned sealing device and the mushroom-shaped deformation of the air preheater are both driven by heat. The deformation directions of the two are opposite and synchronous, thereby keeping the radial gap at the hot end of the air preheater at a small level. This technical solution has been able to solve the problem of triangular air leakage at the hot end of the air preheater. However, once the sealing device rubs against the fan-shaped plate at the hot end of the air preheater, the sealing device cannot elastically retreat, which is not conducive to coping with abnormal operating conditions of the unit. In addition, in actual application, due to the expansion characteristics of the optional metal materials, the maximum expansion difference between the sealing plate and the gasket from the cold state to the hot state can only reach 3.5 to 4 mm / m. In order to ensure that the inclined surface of the driving block and the driven block can slide freely during the operation of the two-dimensional guide mechanism, the angle between the inclined surface and the length direction of the sealing plate should not exceed 45°. As a result, the sealing device has insufficient compensation for units with large mushroom-shaped deformation (such as 1000MW coal-fired units), and can generally only compensate for a maximum gap of 20 to 30 mm. Summary of the Invention

[0006] The present invention provides a pre-pressed bimetallic thermal expansion elastic compensation sealing device and its installation structure, which is installed on the hot end radial partition of the air preheater rotor and is used to eliminate the triangular air leakage area caused by heat in the air preheater. The deformation of the sealing device and the mushroom-shaped deformation of the air preheater are both driven by heat, and the deformation directions of the two are opposite and synchronous, so as to keep the radial gap of the hot end of the air preheater at a small level at all times; and once the sealing device collides with the hot end sector plate of the air preheater, it can elastically give way, thereby improving the operating safety of the air preheater and facilitating the long-term maintenance of a low 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 pre-stressed bimetallic thermal expansion elastic compensation sealing device, one end of which is a fixed end and the other end is a free end in the longitudinal direction, comprising a self-warping sealing plate, a thermal expansion displacement plate and a pre-stressing mechanism;

[0009] The self-warping sealing plate and the thermal expansion displacement plate are both long strips with the same length direction;

[0010] The self-warping sealing plate comprises at least a sealing sheet and a shrinkage strip, wherein the shrinkage strip is fixed to the sealing sheet, the sealing sheet and the shrinkage strip are made of different metals, and the linear expansion coefficient of the shrinkage strip is smaller than the linear expansion coefficient of the sealing sheet;

[0011] The thermal expansion displacement plate is superimposed on one side of the sealing sheet, and the top of the sealing sheet is higher than the thermal expansion displacement plate. The thermal expansion displacement plate is also made of metal, and the linear expansion coefficient of the thermal expansion displacement plate is different from that of the sealing sheet.

[0012] The preloading mechanism includes a stop block, a stop guide rail and a pressure block. The angle between the guide of the stop guide rail and the radial direction of the air preheater rotor is not zero. The stop block can move along the stop guide rail and can also be separated from the stop guide rail laterally. The pressure block is located on the top of the stop block and limits the upward movement of the stop block. The stop block is connected to the sealing plate, and the stop guide rail and the pressure block are both connected to the thermal expansion displacement plate.

[0013] For easy installation, the stop block, stop rail and pressure block are all located on the top of the thermal expansion displacement plate. The stop rail and pressure block are all connected to the top of the thermal expansion displacement plate. The stop block is not connected to the thermal expansion displacement plate, but is connected to the sealing sheet.

[0014] The above-mentioned thermal expansion displacement plate is also made of metal. The linear expansion coefficient of the thermal expansion displacement plate is different from that of the sealing plate. After heating, the thermal expansion displacement plate and the sealing plate produce an expansion difference along the radial direction of the air preheater rotor. Combined with the shrinkage strip, the sealing plate is pre-warped, and then pre-pressed by the pressure block, and then the compression is slowly released through the horizontal expansion difference. It can effectively reduce the radial clearance of the hot end of the air preheater, and effectively buffer the collision and friction, and can elastically retreat after collision and friction.

[0015] The thermal expansion displacement plate is close to one side of the sealing sheet, that is, in the thickness direction, the sealing sheet and the thermal expansion displacement plate are superimposed and close to each other.

[0016] The direction from top to bottom of the present application (ie, the height direction) is perpendicular to the length direction.

[0017] The above-mentioned device compensates the sealing method. After being heated, the thermal expansion displacement plate and the sealing piece produce an expansion difference along the radial direction of the air preheater rotor, causing the sealing piece to have a pre-warping amount. At the same time, the shrinkage tensile stress of the shrinkage strip increases the pre-warping amount of the sealing piece. Driven by the sealing piece, the stop block produces a pre-upward sliding amount along the guide rail, and then is pre-pressed by the pressure block. The stop block and the stop guide rail are separated laterally, and the compression amount is slowly released through the horizontal expansion difference, so that the sealing piece automatically warps upward, which can effectively reduce the radial clearance of the hot end of the air preheater, and effectively buffer the collision and friction, and can elastically retreat after the collision and friction.

[0018] As one specific implementation solution, the linear expansion coefficient of the sealing sheet is smaller than the linear expansion coefficient of the thermal expansion displacement plate.

[0019] In order to facilitate installation and improve stability in use, the stop rail and the pressure block are integrated into one structure.

[0020] To increase the compensation, the guide rails are angled at a 15-75° angle to the radial direction of the air preheater rotor. Different operating conditions require different amounts of sealing compensation, so the appropriate angle can be selected based on the specific operating conditions. This solution allows for a larger guide angle, significantly increasing the upward warping of the sealing disc. This is particularly useful for large coal-fired boiler units with significant mushroom-shaped rotor deformation.

[0021] In order to improve the compensation effect, the shrinkage strip is fixed to the free end of the sealing sheet and is located above the middle of the sealing sheet in the height direction.

[0022] For ease of installation, the shrink strip is positioned above the top of the thermal expansion plate. To enhance operational stability, the shrink strip is welded to the sealing plate. To accommodate general operating conditions, the shrink strip's length ranges from 1000 to 3000 mm.

[0023] In order to enhance elasticity and reduce damage from collision and wear, a bending angle of 10 to 30° (the angle before bending) is set on the top of the sealing sheet. The shrinkage strip is welded along the length direction of the bending angle, and one end of the shrinkage strip is flush with the free end of the sealing sheet.

[0024] The above-mentioned pre-pressed bimetallic thermal expansion elastic compensation sealing device is installed on the hot end radial partition of the air preheater rotor along the radial direction of the air preheater rotor, and one end of the self-warping sealing plate and the thermal expansion displacement plate in the length direction is close to the central tube of the air preheater rotor and is a fixed end, and the other end in the length direction is away from the central tube of the air preheater rotor and is a free end;

[0025] The fixed ends of the self-warping sealing plate and the thermal expansion displacement plate are completely fixed to the hot end partition of the air preheater rotor by bolts, and the free ends of the self-warping sealing plate and the thermal expansion displacement plate are partially fixed to the hot end partition of the air preheater rotor by bolts.

[0026] The above-mentioned installation structure also includes a distance sleeve, which passes through the vertical waist-shaped holes and the transverse waist-shaped holes at the free ends of the sealing plate and the thermal expansion displacement plate at the same time. The length of the distance locking sleeve is 1 to 3 mm greater than the total thickness of the sealing plate and the thermal expansion displacement plate, so that the sealing plate and the thermal expansion displacement plate still have a movable gap after the installation bolts are tightened;

[0027] There are more than two mounting holes along the length of the thermal expansion displacement plate. The first mounting hole from the fixed end of the thermal expansion displacement plate is a round hole, and the rest are transverse waist-shaped holes. The transverse waist-shaped holes are used to reserve horizontal movement clearance when the thermal expansion displacement plate expands due to heat;

[0028] The sealing plate is provided with two or more vertical waist-shaped holes along the length direction, which are used to reserve vertical movable gaps when the sealing plate is driven by heat; each horizontal waist-shaped hole corresponds to a vertical waist-shaped hole, and the horizontal waist-shaped hole intersects with its corresponding vertical waist-shaped hole, and the circular hole corresponds to the first vertical waist-shaped hole from the fixed end;

[0029] The installation method of the fixed end is: the bolts pass through the first gasket, the bolt holes on the radial partition, the mounting holes on the thermal expansion displacement plate, the vertical waist holes on the sealing plate, the pressure plate and the second gasket in sequence, and then are locked and fixed with nuts; the installation method of the free end is: the bolts pass through the first gasket, the bolt holes on the radial partition, the fixed-distance locking sleeve, the pressure plate and the second gasket in sequence, and then are locked and fixed with nuts.

[0030] As one of the preferred implementation schemes, starting from the fixed end, the first 1 to 6 bolt holes on the partition are installed using the fixed end method, and the remaining bolt holes are installed using the free end method; in the height direction, ensure that the top of the thermal expansion displacement plate is slightly lower than or flush with the upper edge of the partition.

[0031] In order to further improve the safety and stability of operation, as one of the more preferred installation structures, the pre-pressing mechanism is located at one end of the free end;

[0032] A gap compensation device is also provided at one end of the fixed end, which includes a lifting block, a driving block and a shrinking block arranged in sequence along the length direction; the lifting block and the shrinking block are fixedly connected to the sealing plate, and the driving block is fixedly connected to the thermal expansion displacement plate. The three together form a moving pair through angle coordination; when the driving block of the thermal expansion displacement plate moves relative to each other in the horizontal direction, the lifting block and the shrinking block on the sealing plate convert their horizontal displacement into upward and downward warping in the vertical direction respectively.

[0033] The free end mentioned above refers to the part closer to the free end; the fixed end refers to the part closer to the fixed end.

[0034] For ease of installation, the gap compensation devices are all located on the top of the thermal expansion displacement plate, the driving block is fixedly connected to the top of the thermal expansion displacement plate, the lifting block and the contraction block are not connected to the thermal expansion displacement plate, and are connected to the sealing sheet.

[0035] As one of the specific implementation schemes, the driving block is a parallelogram structure with horizontal upper and lower bottom edges and parallel two oblique sides. The lifting block is parallel to the side adjacent to the driving block and can be movably engaged. The contraction block is parallel to the side adjacent to the driving block and can be movably engaged.

[0036] The inclination angle of the driving block's oblique side relative to the horizontal plane is preferably 10 to 50° or 170 to 130°.

[0037] In order to further improve the safety and stability of operation, as another preferred installation structure, the pre-pressing mechanism is located at one end of the free end;

[0038] A gap compensation device is also provided at one end of the fixed end, which includes a lifting block and a driving block arranged along the length direction; the lifting block is fixedly connected to the sealing plate, and the driving block is fixedly connected to the thermal expansion displacement plate, and the two together form a moving pair through angle coordination; when the driving block of the thermal expansion displacement plate moves relative to each other in the horizontal direction, the lifting block on the sealing plate converts its horizontal displacement into upward and downward warping in the vertical direction.

[0039] As one of the specific implementation schemes, the side of the lifting block adjacent to the driving block is parallel to each other and movably close to each other; on the side of the lifting block adjacent to the driving block: the inclination angle of the driving block is 10~50°, and the inclination angle of the lifting block is 170~130°.

[0040] Technologies not particularly limited in the present invention are all prior arts.

[0041] The pre-stressed bimetallic thermal expansion elastic compensation sealing device of the present invention can be designed to have a larger angle between the guide of the stop guide rail and the radial direction of the air preheater rotor. After the sealing plate and the thermal expansion displacement plate generate radial expansion difference due to heat, the self-warping sealing plate automatically warps upward by 1 to 3 times the value of the above-mentioned radial expansion difference. It is particularly suitable for units with large mushroom-shaped deformation of the rotor of a large coal-fired boiler. Once the sealing plate collides with the fan-shaped plate at the hot end of the air preheater, the sealing plate can elastically retreat downward, which effectively reduces the sealing gap by designing the interference warping compensation amount and significantly improves the operating safety of the air preheater. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 Schematic diagram of the installation structure of the pre-pressed bimetallic thermal expansion elastic compensation sealing device of the present invention Figure 1 ;

[0043] Figure 2 for Figure 1 Right perspective view (gasket and pressure plate omitted);

[0044] Figure 3 Schematic diagram of the installation structure of the pre-pressed bimetallic thermal expansion elastic compensation sealing device of the present invention Figure 2 ;

[0045] Figure 4 for Figure 3 Right side perspective view (gasket and pressure plate omitted) 1;

[0046] Figure 5 for Figure 3 Right side perspective view (gasket and pressure plate omitted) 2;

[0047] Figure 6 Schematic diagram of the pre-pressing mechanism structure of the present invention;

[0048] Figure 7 This is a schematic diagram of the structure of the thermal expansion displacement plate of the present invention;

[0049] Figure 8 This is a schematic diagram of the structure of the self-warping sealing plate of the present invention;

[0050] Figure 9 This is the first gap compensation device of the present invention;

[0051] Figure 10 This is the second gap compensation device of the present invention;

[0052] In the figure, 1-contraction strip, 2-sealing sheet, 3-pre-pressing mechanism, 31-stop guide rail, 32-stop block, 33-pressure block, 4-pressure plate, 5-thermal expansion displacement plate, 6-fixed distance locking sleeve, 7-bolt, 8-nut, 9-partition, 10-gasket, 11-fan-shaped plate, 12-driving block, 13-lifting block, 14-contraction block. DETAILED DESCRIPTION

[0053] In order to better understand the present invention, the content of the present invention is further illustrated below in conjunction with the examples, but the content of the present invention is not limited to the following examples.

[0054] The orientations or positional relationships indicated by “length”, “width”, “thickness”, “up”, “down”, “vertical”, “horizontal”, “top”, “bottom”, etc. herein are based on the orientations 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 device or element referred to must have a specific orientation, be constructed and operate in a specific orientation. Therefore, they should not be understood as limiting the present invention.

[0055] Example 1

[0056] like Figure 1-2As shown, a pre-stressed bimetallic thermal expansion elastic compensation sealing device has one fixed end and the other free end in the length direction, including a self-warping sealing plate, a thermal expansion displacement plate and a pre-stressing mechanism;

[0057] The self-warping sealing plate and the thermal expansion displacement plate are both long strips with the same length direction;

[0058] The self-warping sealing plate comprises at least a sealing sheet and a shrinkage strip, wherein the shrinkage strip is fixed to the sealing sheet, the sealing sheet and the shrinkage strip are made of different metals, and the linear expansion coefficient of the shrinkage strip is smaller than the linear expansion coefficient of the sealing sheet;

[0059] The thermal expansion displacement plate is close to one side of the sealing sheet, and the top of the sealing sheet is higher than the thermal expansion displacement plate. The thermal expansion displacement plate is also made of metal, and the linear expansion coefficient of the thermal expansion displacement plate is different from that of the sealing sheet.

[0060] like Figure 1 As shown in the figure, the preloading mechanism is located on the top of the thermal expansion displacement plate. Figure 6 As shown, the pre-stressing mechanism includes a stop block, a stop guide rail and a pressure block. The angle between the guide of the stop guide rail and the radial direction of the air preheater rotor is not zero. The stop block can move along the stop guide rail and can also be separated from the stop guide rail laterally. The pressure block is located at the top of the stop block and limits the upward movement of the stop block. The stop block is connected to the sealing plate, and the stop guide rail and the pressure block are both connected to the top of the thermal expansion displacement plate.

[0061] When in use, the above-mentioned pre-pressed bimetallic thermal expansion elastic compensation sealing device is installed on the hot end radial partition of the air preheater rotor along the radial direction of the air preheater rotor, with one end of the self-warping sealing plate and the thermal expansion displacement plate in the length direction close to the central tube of the air preheater rotor and serving as the fixed end, and the other end in the length direction away from the central tube of the air preheater rotor and serving as the free end;

[0062] The fixed ends of the self-warping sealing plate and the thermal expansion displacement plate are completely fixed to the hot end partition of the air preheater rotor by bolts, and the free ends of the self-warping sealing plate and the thermal expansion displacement plate are not completely fixed to the hot end partition of the air preheater rotor by bolts, that is, there is a certain movable gap between the sealing plate and the thermal expansion displacement plate.

[0063] After being heated, the thermal expansion displacement plate and the sealing piece will produce differential expansion along the radial direction of the air preheater rotor, causing the sealing piece to have a pre-warping amount. At the same time, the shrinkage tensile stress of the shrinkage strip increases the pre-warping amount of the sealing piece. Driven by the sealing piece, the stop block will produce a pre-upward sliding amount along the guide rail, and then be pre-pressed by the pressure block. The stop block and the stop guide rail are separated laterally, and the compression amount is slowly released through the horizontal expansion difference, causing the sealing piece to automatically warp upward, which can effectively reduce the radial clearance of the hot end of the air preheater, and effectively buffer the collision and friction, and can elastically retreat after the collision and friction.

[0064] Example 2

[0065] On the basis of Example 1, the following improvements were made: the linear expansion coefficient of the sealing sheet was smaller than the linear expansion coefficient of the thermal expansion displacement plate, and the sealing sheet was made of 410 stainless steel (the average linear expansion coefficient between 0-400°C was 11.5×10 -6 / ℃), the thermal expansion displacement plate is made of aluminum-copper high-temperature resistant alloy (the average linear expansion coefficient between 0-400℃ is 23.2×10 -6 / ℃), the shrinkage bar is made of 630 stainless steel (the average linear expansion coefficient between 0-400℃ is 10.6×10 -6 / ℃).

[0066] Example 3

[0067] On the basis of Example 2, the following improvements are further made: in order to facilitate installation and improve the stability in use, the stop rail and the pressure block are integrated into one structure.

[0068] Example 4

[0069] On the basis of Example 3, the following improvements were made: In order to enhance elasticity and reduce friction damage, Figure 8 As shown, a 25° bending angle is provided at the top of the sealing sheet, the bending point of the bending angle is higher than the top of the thermal expansion displacement plate, one end of the shrinkage strip is flush with the free end of the sealing sheet, and is welded along the length direction of the bending point of the bending angle.

[0070] The above-mentioned pre-pressed bimetallic thermal expansion elastic compensation sealing device is installed as follows: Figure 1 As shown, it also includes a distance sleeve, which passes through the vertical waist-shaped holes and the transverse waist-shaped holes at the free ends of the sealing piece and the thermal expansion displacement plate at the same time. The length of the distance locking sleeve is 1 mm greater than the total thickness of the sealing piece and the thermal expansion displacement plate, so that the sealing piece and the thermal expansion displacement plate still have a movable gap after the installation bolts are tightened;

[0071] like Figure 7 As shown, the thermal expansion displacement plate is provided with more than two mounting holes along the length direction. The first mounting hole from the fixed end of the thermal expansion displacement plate is a round hole, and the rest are transverse waist-shaped holes. The transverse waist-shaped holes are used to reserve horizontal movable clearance when the thermal expansion displacement plate expands due to heat.

[0072] like Figure 8 As shown, the sealing plate is provided with two or more vertical waist-shaped holes along the length direction, which are used to reserve a vertical movable gap when the sealing plate is driven by heat; each horizontal waist-shaped hole corresponds to a vertical waist-shaped hole, and the horizontal waist-shaped hole intersects with its corresponding vertical waist-shaped hole, and the circular hole corresponds to the first vertical waist-shaped hole from the fixed end;

[0073] The installation method of the fixed end is: the bolts pass through the first gasket, the bolt holes on the radial partition, the mounting holes on the thermal expansion displacement plate, the vertical waist holes on the sealing plate, the pressure plate and the second gasket in sequence, and then are locked and fixed with nuts; the installation method of the free end is: the bolts pass through the first gasket, the bolt holes on the radial partition, the fixed-distance locking sleeve, the pressure plate and the second gasket in sequence, and then are locked and fixed with nuts.

[0074] Starting from the fixed end, the first 1 to 6 bolt holes on the partition are installed in the fixed end manner, and the remaining bolt holes are installed in the free end manner; in the height direction, ensure that the top of the thermal expansion displacement plate is slightly lower than or flush with the upper edge of the partition.

[0075] For the air preheater equipped with a 600MW coal-fired power generation unit, the total length of the radial sealing plate is about 6.5m. The thermal expansion displacement plate and the sealing plate produce an expansion difference of about 22mm along the radial direction of the air preheater rotor. The guide of the stop guide rail is designed to form a 53° angle with the radial direction of the air preheater rotor, and the length of the contraction strip is 1.8m. The number and hole spacing of the waist holes on the thermal expansion displacement plate and the sealing plate are set according to the number and hole spacing of the bolt holes on the partition. If there are 19 bolt holes in the long length direction of the partition, the first bolt position on the length direction of the thermal expansion displacement plate is designed to be a circular hole that matches the installation bolt, and the installation positions of the remaining 18 bolt holes are all set as horizontal waist holes; while all bolt holes in the sealing plate are vertical waist holes. Starting from the fixed end, the first three bolt holes are installed in a locked manner (also known as the fixed end installation method), and the remaining bolt holes are installed in a movable manner (also known as the free end installation method); in the height direction, the top of the thermal expansion displacement plate is flush with the top of the partition; after the outermost side of the sealing plate is heated, a maximum compensation of approximately 29mm can be generated.

[0076] For the air preheater equipped with a 1000MW coal-fired power generation unit, the total length of the radial sealing plate is about 7.6m. The thermal expansion displacement plate and the sealing plate produce an expansion difference of about 26mm along the radial direction of the air preheater rotor. The guide of the stop guide rail is designed to form a 63° angle with the radial direction of the air preheater rotor, and the length of the contraction strip is 2.4m; the number and hole spacing of the waist holes on the thermal expansion displacement plate and the sealing plate are set according to the number and hole spacing of the bolt holes on the partition. If there are 24 bolt holes in total in the long length direction of the partition, the first bolt position on the length direction of the thermal expansion displacement plate is designed to be a circular hole that cooperates with the installation bolt, and the installation positions of the remaining 23 bolt holes are all set as horizontal waist holes; and all bolt holes in the sealing plate are vertical waist holes. Starting from the fixed end, the first four bolt holes are installed in a locked manner (also known as the fixed end installation method), and the remaining bolt holes are installed in a movable manner (also known as the free end installation method); in the height direction, the top of the thermal expansion displacement plate is flush with the top of the partition; after the outermost side of the sealing plate is heated, a maximum compensation of approximately 51mm can be generated.

[0077] Example 5

[0078] The difference from Example 4 is that: Figure 3-4 As shown, during installation, the pre-stressing mechanism is located at one end of the free end; a gap compensation device is also provided at one end of the fixed end, and the gap compensation device is located at the top of the thermal expansion displacement plate. The gap compensation device consists of a lifting block, a driving block and a shrinking block arranged in sequence along the length direction; the lifting block and the shrinking block are fixedly connected to the sealing plate, and the driving block is fixedly connected to the top of the thermal expansion displacement plate. The three together form a moving pair through angle coordination; when the driving block of the thermal expansion displacement plate moves relative to each other in the horizontal direction, the lifting block and the shrinking block on the sealing plate convert its horizontal displacement into upward and downward warping in the vertical direction respectively.

[0079] Example 6

[0080] On the basis of Example 5, the following improvements were made: Figure 9 As shown, the driving block is a parallelogram structure with horizontal upper and lower bottom sides and parallel oblique sides. The inclination angles of the oblique sides of the driving block relative to the horizontal plane are 30° and 150°. The lifting block is parallel to the side adjacent to the driving block and can be movably engaged. The contraction block is parallel to the side adjacent to the driving block and can be movably engaged.

[0081] Example 7

[0082] The difference from Example 4 is that: Figure 5 As shown, during installation, the pre-stressing mechanism is located at one end of the free end; a gap compensation device is also provided at one end of the fixed end, and the gap compensation device is composed of a lifting block and a driving block arranged along the length direction; the lifting block is fixedly connected to the sealing plate, and the driving block is fixedly connected to the thermal expansion displacement plate, and the two together form a moving pair through angle matching; when the driving block of the thermal expansion displacement plate moves relative to each other in the horizontal direction, the lifting block on the sealing plate converts its horizontal displacement into upward and downward warping in the vertical direction.

[0083] Example 8

[0084] On the basis of Example 7, the following improvements were made: Figure 10 As shown, the side of the lifting block adjacent to the driving block is parallel to each other and movably close to each other. On the side of the lifting block adjacent to the driving block: the inclination angle of the driving block is 30°, and the inclination angle of the lifting block is 150°.

[0085] After practical operation, the inventors found that the adoption of the scheme of Examples 5-8 can significantly improve the overall reliability of the gap compensation of the sealing device. The reason is that the inventors believe that, from the perspective of gap compensation stability, since the force during the lifting process is much greater than the force during the pre-pressing process, the performance of gap compensation through the lifting action is more stable and less susceptible to other external forces; from the perspective of gap compensation safety performance, the gap compensated by lifting cannot be further retreated, but the gap compensated by gradually releasing the pre-pressing can be retreated again, that is, the gap compensation with a pre-pressing mechanism is safer; during the operation of the unit, the air preheater rotor is a central support structure during rotation, and the gap change characteristics near the center tube end are more stable and the gap change amplitude is smaller. Once the friction occurs, the force arm is smaller, and the impact on the current of the air preheater rotor drive motor is smaller. Therefore, the lifting block with a more stable gap compensation characteristic is still used near the center tube end, while the other end uses the pre-pressing mechanism to achieve larger gap compensation, and it can elastically retreat in case of friction.

Claims

1. A pre-stressed bimetallic thermal expansion elastic compensation sealing device, one end of which is fixed and the other end is free in the longitudinal direction, characterized in that: It includes a self-warping sealing plate, a thermal expansion displacement plate and a pre-pressing mechanism; The self-warping sealing plate and the thermal expansion displacement plate are both long strips with the same length direction; The self-warping sealing plate comprises at least a sealing sheet and a shrinkage strip, wherein the shrinkage strip is fixed to the sealing sheet, the sealing sheet and the shrinkage strip are made of different metals, and the linear expansion coefficient of the shrinkage strip is smaller than the linear expansion coefficient of the sealing sheet; The thermal expansion displacement plate is close to one side of the sealing sheet, and the top of the sealing sheet is higher than the thermal expansion displacement plate. The thermal expansion displacement plate is also made of metal, and the linear expansion coefficient of the thermal expansion displacement plate is different from that of the sealing sheet. The pre-pressing mechanism includes a stop block, a stop rail and a pressure block. The angle between the guide of the stop rail and the radial direction of the air preheater rotor is not zero. The stop block can move along the stop rail and can also be separated from the stop rail laterally. The pressure block is located on the top of the stop block to limit the upward movement of the stop block. The stop block is connected to the sealing plate, and the stop rail and the pressure block are both connected to the thermal expansion displacement plate. The preloading mechanism is located at one end of the free end; A gap compensation device is also provided at one end of the fixed end. The gap compensation device includes a lifting block, a driving block, and a shrinking block arranged in sequence along the length direction. The lifting block and the shrinking block are fixedly connected to the sealing plate, and the driving block is fixedly connected to the thermal expansion displacement plate. The three together form a moving pair through angular coordination. When the driving block of the thermal expansion displacement plate moves relative to each other in the horizontal direction, the lifting block and the shrinking block on the sealing plate convert their horizontal displacement into vertical upward and downward movement respectively. Alternatively, a gap compensation device is further provided at one end of the fixed end, comprising a lifting block and a driving block arranged along the length direction; the lifting block is fixedly connected to the sealing sheet, and the driving block is fixedly connected to the thermal expansion displacement plate, and the two are angularly matched to form a moving pair; when the driving block of the thermal expansion displacement plate moves relative to the horizontal direction, the lifting block on the sealing sheet converts its horizontal displacement into upward and downward tilting in the vertical direction; Compensation sealing method: after being heated, the thermal expansion displacement plate and the sealing piece produce expansion difference along the radial direction of the air preheater rotor, causing the sealing piece to have a pre-warping amount. At the same time, the shrinkage tensile stress of the shrinkage strip increases the pre-warping amount of the sealing piece. Driven by the sealing piece, the stop block produces a pre-upward sliding amount along the guide rail, and then is pre-pressed by the pressure block. The stop block and the stop guide rail are separated laterally, and the compression amount is slowly released through the horizontal expansion difference, causing the sealing piece to automatically warp upward, effectively reducing the radial clearance of the hot end of the air preheater, while buffering collision and friction, and elastically retreating after collision and friction.

2. The pre-compression bimetallic thermal expansion elastic compensation sealing device according to claim 1, characterized in that: The linear expansion coefficient of the sealing sheet is smaller than the linear expansion coefficient of the thermal expansion displacement plate.

3. The pre-compression bimetallic thermal expansion elastic compensation sealing device according to claim 1 or 2, characterized in that: The stop rail and the pressure block are an integrated structure; the guide of the stop rail forms an angle of 15 to 75 degrees with the radial direction of the air preheater rotor.

4. The pre-compression bimetallic thermal expansion elastic compensation sealing device according to claim 1 or 2, characterized in that: The shrinkage strip is fixed to the free end of the sealing sheet and is located above the middle of the sealing sheet in the height direction.

5. The pre-compression bimetallic thermal expansion elastic compensation sealing device according to claim 1 or 2, characterized in that: The shrinkage strip is higher than the top of the thermal expansion displacement plate; the shrinkage strip is welded on the sealing sheet, and the length of the shrinkage strip ranges from 1000 to 3000 mm.

6. The pre-compression bimetallic thermal expansion elastic compensation sealing device according to claim 1 or 2, characterized in that: The top of the sealing sheet is provided with a bending angle of 10 to 30 degrees, the shrinkage strip is welded along the length direction of the bending angle, and one end of the shrinkage strip is flush with the free end of the sealing sheet.

7. A mounting structure using the pre-compression bimetallic thermal expansion elastic compensation sealing device according to any one of claims 1 to 6, mounted on the hot end radial partition of the air preheater rotor along the radial direction of the air preheater rotor, characterized in that: One end of the self-warping sealing plate and the thermal expansion displacement plate in the length direction is close to the central tube of the air preheater rotor and is a fixed end, and the other end in the length direction is far away from the central tube of the air preheater rotor and is a free end; The fixed ends of the self-warping sealing plate and the thermal expansion displacement plate are completely fixed to the hot end partition of the air preheater rotor by bolts, and the free ends of the self-warping sealing plate and the thermal expansion displacement plate are partially fixed to the hot end partition of the air preheater rotor by bolts.

8. The mounting structure according to claim 7, wherein: It also includes a distance sleeve, which passes through the vertical waist-shaped holes and the transverse waist-shaped holes at the free ends of the sealing piece and the thermal expansion displacement plate at the same time. The length of the distance locking sleeve is 1-3 mm greater than the total thickness of the sealing piece and the thermal expansion displacement plate, so that the sealing piece and the thermal expansion displacement plate still have a movable gap after the installation bolts are tightened; There are more than two mounting holes along the length of the thermal expansion displacement plate. The first mounting hole from the fixed end of the thermal expansion displacement plate is a round hole, and the rest are transverse waist-shaped holes. The transverse waist-shaped holes are used to reserve horizontal movement clearance when the thermal expansion displacement plate expands due to heat; The sealing plate is provided with two or more vertical waist-shaped holes along the length direction, which are used to reserve vertical movable gaps when the sealing plate is driven by heat; each horizontal waist-shaped hole corresponds to a vertical waist-shaped hole, and the horizontal waist-shaped hole intersects with its corresponding vertical waist-shaped hole, and the circular hole corresponds to the first vertical waist-shaped hole from the fixed end; The installation method of the fixed end is: the bolts pass through the first gasket, the bolt holes on the radial partition, the mounting holes on the thermal expansion displacement plate, the vertical waist holes on the sealing plate, the pressure plate and the second gasket in sequence, and then are locked and fixed with nuts; the installation method of the free end is: the bolts pass through the first gasket, the bolt holes on the radial partition, the fixed-distance locking sleeve, the pressure plate and the second gasket in sequence, and then are locked and fixed with nuts.

9. The mounting structure according to claim 8, wherein: Starting from the fixed end, the first 1 to 6 bolt holes on the partition are installed in the fixed end manner, and the remaining bolt holes are installed in the free end manner; in the height direction, ensure that the top of the thermal expansion displacement plate is lower than or flush with the upper edge of the partition.

10. The mounting structure according to any one of claims 7 to 9, wherein: When the gap compensation device includes a lifting block, a driving block and a shrinking block arranged in sequence along the length direction, the driving block is a parallelogram structure with horizontal upper and lower bottom sides and parallel oblique sides; the lifting block and the driving block are parallel to each other on one side and movably engage with each other, and the shrinking block and the driving block are parallel to each other on one side and movably engage with each other; When the gap compensation device includes a lifting block and a driving block arranged along the length direction, the lifting block and the driving block are adjacent to each other on one side and are movably engaged with each other.

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