阅读说明：本技术 利用密封片与固定板之间胀差补偿的空预器热端密封装置 (Air preheater hot end sealing device utilizing expansion difference compensation between sealing sheet and fixing plate ) 是由 石伟伟 韦红旗 申先念 于 2021-09-13 设计创作，主要内容包括：本发明公开了一种利用密封片与固定板之间胀差补偿的空预器热端密封装置,至少包括固定板和密封片,密封片上设有沿长度方向分布的密封片安装孔,固定板上设有沿长度方向分布的固定板安装孔,密封片的线性膨胀系数大于固定板的线性膨胀系数；固定板和密封片通过同时穿过密封片安装孔和固定板安装孔的装夹螺栓相对固定；靠近转子中心筒的一端为膨胀起始端,膨胀起始端的装夹螺栓拧紧固定、其余的装夹螺栓非完全拧紧,使得密封片和固定板受热后分别向靠近转子外缘角钢的另一端自由膨胀；膨胀起始端下游的密封片和固定板之间设置至少一组二维导向机构。上述装置,最大化地补偿了空预器热端三角漏风区域,显著降低了空预器漏风率；稳定性好,寿命长。(The invention discloses an air preheater hot end sealing device utilizing expansion difference compensation between a sealing sheet and a fixing plate, which at least comprises the fixing plate and the sealing sheet, wherein the sealing sheet is provided with sealing sheet mounting holes distributed along the length direction; the fixed plate and the sealing sheet are relatively fixed through clamping bolts which simultaneously penetrate through the sealing sheet mounting holes and the fixed plate mounting holes; one end close to the rotor central cylinder is an expansion starting end, the clamping bolt of the expansion starting end is screwed and fixed, and the other clamping bolts are not screwed completely, so that the sealing sheet and the fixing plate are heated and then respectively expand freely towards the other end close to the rotor outer edge angle steel; at least one set of two-dimensional guide mechanism is arranged between the sealing sheet and the fixing plate at the downstream of the expansion starting end. The device maximally compensates the triangular air leakage area at the hot end of the air preheater, and obviously reduces the air leakage rate of the air preheater; good stability and long service life.)

1. Utilize the poor air preheater hot junction sealing device who compensates of expanding between gasket and the fixed plate, install on the radial baffle of hot junction of air preheater rotor, one end is close to a rotor center section of thick bamboo, the other end is close to rotor outer fringe angle steel, at least including the fixed plate that sets gradually along thickness direction, gasket and clamp plate, is equipped with the gasket mounting hole that distributes along length direction on the gasket, is equipped with the fixed plate mounting hole that distributes along length direction on the fixed plate, its characterized in that: the linear expansion coefficient of the sealing sheet is larger than that of the fixing plate; the fixing plate is arranged along the length direction of the sealing sheet and is relatively fixed through a clamping bolt which simultaneously penetrates through the mounting hole of the sealing sheet and the mounting hole of the fixing plate; one end close to the rotor central cylinder is an expansion starting end, the clamping bolt of the expansion starting end is screwed and fixed, and the other clamping bolts are not screwed completely, so that the sealing sheet and the fixing plate are heated and then respectively expand freely towards the other end close to the rotor outer edge angle steel; at least one set of two-dimensional guide mechanism is arranged between the sealing sheet and the fixing plate at the downstream of the expansion starting end.

2. The hot end sealing device for an air preheater using differential expansion compensation between a sealing plate and a fixing plate according to claim 1, wherein: at least one group of roller wheel mechanisms are arranged at the edge of the sealing plate and at one end close to the rotor outer edge angle steel, and the top point of each roller wheel is not lower than the edge of the sealing plate.

3. The hot end sealing device of the air preheater compensated by the expansion difference between the sealing plate and the fixing plate according to claim 1 or 2, wherein: the two-dimensional guide mechanism comprises a guide rail and a guide block, the travel of the guide rail is a straight line or a curve, and the included angle between the travel of the guide rail or the tangent of the travel of the guide rail and the horizontal plane is not less than 10 degrees.

4. The hot end sealing device for an air preheater using differential expansion compensation between a sealing plate and a fixing plate according to claim 3, wherein: the guide rail of the two-dimensional guide mechanism is arranged on the sealing sheet, and the guide block is arranged on the fixed plate; a guide rail with an inclined plane structure is arranged on the sealing sheet, a guide block matched with the guide rail is arranged on the fixing plate, and the guide block is in sliding fit with the guide rail; or, a groove with a downward opening and an inclined arrangement is arranged at the lower edge of the sealing sheet as a guide rail, the guide block is matched with the shape of the groove, the guide block is in sliding fit in the groove and can slide up and down relative to the groove, and one side of the guide block is connected to the fixing plate; or, a parallelogram cavity is arranged on the sealing sheet, the guide rail is provided with two parallel sides with equal length, the guide block is also in a parallelogram shape, the guide block is arranged at the inner side of the parallelogram cavity, the two sides of the guide block are respectively in sliding fit with the two sides of the guide rail, the height of the guide block is less than that of the parallelogram cavity, and one side of the guide block is connected on the fixing plate.

5. The hot end sealing device of the air preheater compensated by the expansion difference between the sealing plate and the fixing plate according to claim 1 or 2, wherein: set up between gasket and the fixed plate and be no less than 2 two-dimentional guiding mechanism of group.

6. The hot end sealing device of the air preheater compensated by the expansion difference between the sealing plate and the fixing plate according to claim 1 or 2, wherein: the linear expansion coefficient of the sealing sheet is more than 30% larger than that of the fixing plate.

7. The hot end sealing device of the air preheater compensated by the expansion difference between the sealing plate and the fixing plate according to claim 1 or 2, wherein: more than two balls are arranged on the sealing sheet around the sealing sheet mounting hole where the clamping bolt which is not completely screwed down is located.

8. The hot end sealing device of the air preheater compensated by the expansion difference between the sealing plate and the fixing plate according to claim 1 or 2, wherein: the thickness of sealing piece and fixed plate is all not less than 3mm, and the last border of sealing piece is higher than the last border of fixed plate.

9. The hot end sealing device of the air preheater compensated by the expansion difference between the sealing plate and the fixing plate according to claim 1 or 2, wherein: the sealing piece mounting hole is a chamfer rectangle, and the width in the horizontal direction is not less than the sum of the expansion difference between the sealing piece and the fixing plate at the corresponding position and the diameter of the clamping bolt; the fixing plate mounting hole is a round hole or a waist hole in the horizontal direction, and the size of the fixing plate mounting hole in the vertical direction is 0.2-5mm larger than the diameter of the clamping bolt.

10. The hot end sealing device of the air preheater compensated by the expansion difference between the sealing plate and the fixing plate according to claim 1 or 2, wherein: the fixed plate and the hot end radial partition plate are arranged in a split mode, and the fixed plate is located between the hot end radial partition plate and the sealing piece.

Technical Field

The invention relates to a hot end sealing device of an air preheater by utilizing expansion difference compensation between a sealing sheet and a fixing plate, belonging to the field of sealing devices.

Background

The rotary air preheater is a heat exchange equipment applied to large coal-fired power station boiler, and it utilizes the heat of boiler flue gas to heat the air required for combustion so as to raise the efficiency of boiler. The air preheater rotor is changed from a cold state to a hot state, due to the fact that the temperatures of the upper end surface and the lower end surface are different and the rigidity of steel materials is weakened after the steel materials are heated, mushroom-shaped deformation is generated, a traditional rigid sealing sheet is fixed on a rotor partition plate in a segmented mode through bolts, and along with the deformation of the rotor partition plate, an air leakage gap is changed accordingly. Based on the mechanism of the mushroom-shaped deformation of the rotor, proper cold-state gaps are reserved at the radial positions of the axial direction and the cold end, and the dynamic and static fit gaps tend to be zero in the hot state; although the cold reserved gap at the radial position of the hot end is small, a large triangular air leakage area is formed in the hot state.

In order to reduce the area of the triangular air leakage area and reduce the air leakage rate of the air preheater, two technical routes are generally adopted in the current engineering: the automatic tracking system is characterized by comprising a sector plate automatic tracking system (LCS for short) equipped in three host manufacturers (east pan, Ha pan and upper pan) in China; the second is the flexible sealing technology developed in recent years.

It will be appreciated that this in fact represents two aspects of a problem: the sealing problem of the air preheater is the matching problem of the sealing sheet and the sector plate, and the purpose of reducing air leakage can be realized by automatically attaching the sealing sheet to the sector plate and automatically tracking the sealing sheet by the sector plate. However, the two schemes have the following problems in engineering application: influenced by various factors such as severe working conditions (high temperature, dust and the like), maintenance quality, management level and the like, most LCS systems of power plants cannot be normally put into operation or the operation effect is not ideal. The leading supplier HOWDEN of the rotary air pre-heater has not been matched with LCS on the air pre-heater, and it is also shown from the side that the technology needs to be further improved. The traditional flexible sealing technology is exposed to the problems of too fast abrasion, unreliable structure, insufficient clearance compensation amount and the like, and can not meet the engineering requirements at all.

In a word, the air leakage problem of the hot end radial triangular air leakage area is not thoroughly solved, the diameter of the rotor of the air preheater is continuously increased along with the development of a unit in a large-capacity direction, and if no measures are taken, the air leakage share of the hot end radial triangular air leakage area is larger and larger. If adopt traditional rigidity gasket and hot junction sector plate when unadjustable, 300MW unit hot junction radial outermost fringe clearance exceeds 10mm, and 600MW unit surpasses 25mm, and 1000MW unit clearance is about 50 mm. The radial triangular air leakage at the hot end of the air preheater equipped in the unit with the power of 600MW or more accounts for more than 50% of the total air leakage rate, the absolute air leakage rate to the flue gas side is also over 3%, and the primary air leakage rate can exceed 30%.

Disclosure of Invention

The invention provides an air preheater hot end sealing device utilizing expansion difference compensation between a sealing sheet and a fixing plate, which is arranged on a hot end radial partition plate of an air preheater rotor and is used for eliminating a triangular air leakage area generated by heating an air preheater and obviously reducing the air leakage rate of the air preheater.

In order to solve the technical problems, the technical scheme adopted by the invention is as follows:

the sealing device for the hot end of the air preheater compensated by the expansion difference between the sealing sheet and the fixing plate is arranged on a radial partition plate of the hot end of the rotor of the air preheater, one end of the sealing sheet is close to the central cylinder of the rotor, and the other end of the sealing sheet is close to an angle steel on the outer edge of the rotor; the fixing plate is arranged along the length direction of the sealing sheet and is relatively fixed through a clamping bolt which simultaneously penetrates through the mounting hole of the sealing sheet and the mounting hole of the fixing plate; one end close to the rotor central cylinder is an expansion starting end, the clamping bolt of the expansion starting end is screwed and fixed, and the other clamping bolts are not screwed completely, so that the sealing sheet and the fixing plate are heated and then respectively expand freely towards the other end close to the rotor outer edge angle steel; at least one set of two-dimensional guide mechanism is arranged between the sealing sheet and the fixing plate at the downstream of the expansion starting end.

The length direction of the sealing sheet is consistent with the radial direction of the air preheater rotor; the radial direction of the rotor of the air preheater, the direction from the rotor center cylinder to the angle steel of the outer edge of the rotor is defined as the direction from the upstream to the downstream.

The applicant finds that the expansion amount of the sealing sheet along the radial direction of the air preheater rotor is larger than that of the fixing plate, horizontal radial relative displacement is converted into vertical axial upward displacement through the two-dimensional guide mechanism, and meanwhile dislocation displacement is formed, so that the hot end triangular air leakage area of the air preheater can be effectively compensated. The deformation of the sealing device and the mushroom-shaped deformation of the air preheater are driven by heat, and the deformation directions of the sealing device and the air preheater are opposite and synchronous, so that the radial clearance of the hot end of the air preheater is kept at a small level all the time.

This application is through two-dimentional guiding mechanism's setting, when inflation or shrink for sealing fin and fixed plate slide according to specific route, can ensure the stability of operation, again can the accurate control displacement volume, and then the accurate control compensation volume avoids appearing compensating too big or undersize's problem, when effectively reducing air preheater air leakage rate, has ensured the operation of air preheater's safety and stability.

In order to prevent the sealing plate from being abnormally deformed to cause malignant collision and abrasion with a sector plate of the air preheater, preferably, at least one group of roller mechanisms is arranged at one end of the upper edge of the sealing plate, which is close to an angle steel of the outer edge of the rotor, and the top point of each roller is not lower than the upper edge of the sealing plate.

The sealing piece is vertical to the length direction of the sealing piece from top to bottom.

In order to obtain a suitable and stable deformation characteristic of the sealing device, it is preferable that the two-dimensional guide mechanism includes a guide rail and a guide block, the travel of the guide rail is a straight line or a curved line, and an included angle between the travel of the guide rail or a tangent of the travel of the guide rail and a horizontal plane is not less than 10 °. The larger the angle is, the larger the amount of horizontal displacement converted into a vertical position is, and the angle of the guide rail stroke is determined according to the specific size of the triangular air leakage area of the air preheater so as to realize the maximum compensation of the triangular air leakage area, reduce the air leakage rate to the maximum extent, and simultaneously avoid the overlarge compensation to cause collision and abrasion so as to ensure the safety. In addition, when the guide rail stroke is a straight line, the expansion amount in the horizontal direction is converted into the compensation amount in the vertical direction according to a fixed proportion, when the guide rail stroke is a non-straight stroke, the expansion amount in the horizontal direction is also non-linear when the expansion amount in the horizontal direction is converted into the compensation amount in the vertical direction, specifically, the guide rail stroke is selected to be a straight line or a curve according to the temperature change characteristic of the air preheater, when the linear relation between the temperature difference of the cold end and the temperature of the hot end is good, the straight line is selected, and when the non-linear relation is obvious, the curve is selected.

For convenient installation, the guide rail of the two-dimensional guide mechanism is arranged on the sealing sheet, and the guide block is arranged on the fixed plate.

The two-dimensional guide mechanism can be arranged into various structures, in order to facilitate manufacturing, a guide rail with an inclined surface structure is arranged on the sealing sheet, a guide block matched with the guide rail is arranged on the fixing plate, and the guide block is in sliding fit with the guide rail; or, a groove with a downward opening and an inclined arrangement is arranged at the lower edge of the sealing sheet as a guide rail, the guide block is matched with the shape of the groove, the guide block is in sliding fit in the groove and can slide up and down relative to the groove, and one side of the guide block is connected to the fixing plate; or, a parallelogram cavity is arranged on the sealing sheet, the guide rail is two sides with equal length in parallel, the guide block is also parallelogram, the guide block is arranged inside the parallelogram cavity, the two sides of the guide block are respectively matched with the two sides of the guide rail in a sliding way, the height of the guide block is less than that of the parallelogram cavity, and one side of the guide block is connected on the fixing plate, so that the guide block can slide along the side edge in the parallelogram cavity.

When the sealing sheet is provided with the parallelogram cavity, the parallelogram cavity comprises an upper bottom and a lower bottom which are parallel and two parallel side edges, preferably, the upper bottom and the lower bottom of the parallelogram cavity are parallel to the horizontal plane, and the included angle between the two side edges of the parallelogram cavity and the horizontal plane is not less than 10 degrees. The upper bottom and the lower bottom of the corresponding guide block are parallel to the horizontal plane, and two side edges of the guide block are parallel to and correspond to two side edges of the parallelogram cavity.

In order to ensure the deformation stability of the sealing device, preferably, at least 2 groups of two-dimensional guide mechanisms are arranged between the sealing sheet and the fixing plate.

In order to obtain a sufficient amount of thermal compensation, the coefficient of linear expansion of the sealing sheet is preferably greater than the coefficient of linear expansion of the fixing plate by 30% or more.

In order to reduce the influence of static friction on the deformation of the sealing device, it is preferable that two or more balls be provided around the seal piece mounting hole in which the clamping bolt that is not completely tightened is located on the seal piece.

In order to guarantee the strength and the stability of the sealing device, the thickness of the sealing sheet and the thickness of the fixing plate are not smaller than 3mm, and the upper edge of the sealing sheet is higher than that of the fixing plate.

In order to ensure smooth relative expansion and stable deformation characteristics of the sealing sheet and the fixing plate, the mounting hole of the sealing sheet is a chamfer rectangle, and the width of the sealing sheet in the horizontal direction is not less than the sum of the expansion difference between the sealing sheet and the fixing plate at the corresponding position and the diameter of the clamping bolt; the fixing plate mounting hole is a round hole or a waist hole in the horizontal direction, and the size of the fixing plate mounting hole in the vertical direction is 0.2-5mm larger than the diameter of the clamping bolt.

The fixed plate and the hot end radial partition plate can be arranged integrally or in a split mode, and for convenience in installation and maintenance, the fixed plate and the hot end radial partition plate are preferably arranged in a split mode and are located between the hot end radial partition plate and the sealing piece.

For each radial partition plate, the hot end sealing device of the air preheater is an integral body, the segmentation is not allowed along the radial direction of the rotor, but the segmented structure is allowed to be welded on site and then become an integral body again for the convenience of processing and carrying.

The present invention is not particularly limited to the prior art.

According to the air preheater hot end sealing device for compensating expansion difference between the sealing sheet and the fixing plate, the linear expansion coefficient of the sealing sheet is larger than that of the fixing plate, the sealing sheet and the fixing plate are expanded to different degrees when heated, and meanwhile, the arrangement of the two-dimensional guide mechanism is combined, so that horizontal radial relative displacement is converted into vertical axial upward displacement, a triangular air leakage area of the hot end of the air preheater is compensated to the maximum extent, the air leakage rate of the air preheater is reduced remarkably, and the operation stability is ensured; the deformation of the sealing device and the mushroom-shaped deformation of the air preheater are driven by heat, and the deformation directions of the sealing device and the mushroom-shaped deformation of the air preheater are opposite and synchronous, so that the radial clearance of the hot end of the air preheater is kept at a small level all the time; furthermore, the stability is improved, the vicious collision and abrasion are avoided, and the service life of the sealing piece is prolonged.

Drawings

Fig. 1 is a front view of a hot end sealing device of an air preheater using expansion difference compensation between a sealing plate and a fixing plate in embodiment 1 of the present invention;

FIG. 2 is a side view of a hot end sealing device of an air preheater utilizing differential expansion compensation between a sealing plate and a fixing plate in embodiment 1 of the present invention;

FIG. 3 is a front view of a hot end sealing device of an air preheater utilizing differential expansion compensation between a sealing plate and a fixing plate in embodiment 2 of the present invention;

FIG. 4 is a side view of the hot end sealing device of the air preheater utilizing differential expansion compensation between the sealing plate and the fixing plate in embodiment 2 of the present invention;

FIG. 5 is a side view of the hot end sealing device of the air preheater utilizing differential expansion compensation between the sealing plate and the fixing plate in embodiment 3 of the present invention;

FIG. 6 is a schematic view of a two-dimensional guide mechanism in embodiment 4 of the present invention;

FIG. 7 is a schematic view of a two-dimensional guide mechanism in embodiment 5 of the present invention;

FIG. 8 is a schematic view of a two-dimensional guide mechanism in embodiment 7 of the present invention;

in the figure, 1 is a sealing sheet, 2 is a fixing plate, 3 is a pressing plate, 4 is a clamping bolt, 5 is a hot end radial partition plate, 6 is a sealing sheet mounting hole, 7 is a fixing plate mounting hole, 8 is a two-dimensional guide mechanism, 9 is an expansion starting end, 10 is a guide rail, 11 is a guide block, 12 is a ball and 13 is a roller mechanism.

Detailed Description

In order to better understand the present invention, the following examples are further provided to illustrate the present invention, but the present invention is not limited to the following examples.

The following references to "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," and the like are based on the orientation or positional relationship shown in the drawings and are intended merely to facilitate the description and to simplify the description, but do not refer to or imply that the referenced device or element must have a particular orientation, be constructed and operated in a particular orientation, and are not to be construed as limiting the invention.

Example 1

As shown in fig. 1-2, the air preheater hot end sealing device utilizing the expansion difference compensation between the sealing sheet and the fixing plate is installed on a hot end radial partition plate of an air preheater rotor, one end of the sealing sheet is close to a rotor center cylinder, and the other end of the sealing sheet is close to rotor outer edge angle steel, and at least comprises a fixing plate, a sealing sheet and a pressing plate which are sequentially arranged along the thickness direction, wherein the sealing sheet is provided with sealing sheet installation holes distributed along the length direction, the fixing plate is provided with fixing plate installation holes distributed along the length direction, and the sealing sheet installation holes and the fixing plate installation holes are equal in number and are in one-to-one correspondence; the linear expansion coefficient of the sealing sheet is larger than that of the fixing plate; the fixing plate and the hot-end radial partition plate are arranged in a split mode, the fixing plate is located between the hot-end radial partition plate and the sealing piece, the fixing plate is arranged along the length direction of the sealing piece and is fixed relatively through clamping bolts sequentially penetrating through the hot-end radial partition plate, the fixing plate mounting holes, the sealing piece mounting holes and the pressing plate, and each pair of sealing piece mounting holes and the fixing plate mounting holes correspond to one clamping bolt; one end close to the central cylinder of the rotor is an expansion starting end, a first clamping bolt at the expansion starting end is screwed and fixed, and the other clamping bolts are not screwed completely, so that the sealing sheet and the fixing plate are heated and then respectively expand freely towards the other end close to the angle steel at the outer edge of the rotor; 3 groups of two-dimensional guide mechanisms are arranged between the sealing sheet at the downstream of the expansion starting end and the fixed plate, each two-dimensional guide mechanism comprises a guide rail and a guide block, the travel of the guide rail is a straight line, the guide rail is arranged on the sealing sheet, and the guide blocks are arranged on the fixed plate.

Engineering practice proves that the expansion amount of the sealing sheet along the radial direction of the air preheater rotor is larger than that of the fixing plate, horizontal radial relative displacement is converted into vertical axial upward displacement through the two-dimensional guide mechanism, and meanwhile, dislocation displacement is formed, so that a hot-end triangular air leakage area of the air preheater can be effectively compensated; and the deformation of the sealing device and the mushroom-shaped deformation of the air preheater are driven by heat, and the deformation directions of the sealing device and the air preheater are opposite and synchronous, so that the radial clearance of the hot end of the air preheater is kept at a small level all the time.

Example 2

On the basis of the embodiment 1, the following improvements are further made: as shown in fig. 3-4, in order to prevent the sealing plate from being deformed abnormally and causing the sealing plate to be collided and ground with the sector plate of the air preheater maliciously, at least one group of roller mechanisms are installed at the upper edge of the sealing plate and one end close to the angle steel of the outer edge of the rotor, and the top point of each roller is not lower than the upper edge of the sealing plate; once the sealing plate and the sector plate are rubbed, the roller is firstly contacted with the sector plate, thereby ensuring that the sealing plate is not seriously damaged. In order to reduce the influence of static friction on the deformation of the sealing device, more than two balls are arranged on the sealing sheet around the sealing sheet mounting hole where the clamping bolt which is not completely screwed is located.

Example 3

On the basis of the embodiment 2, the following improvements are further made: as shown in fig. 5, the fixing plate and the hot end radial partition plate are integrally provided.

Example 4

On the basis of the embodiment 2, the following improvements are further made: as shown in fig. 6, the travel of the guide rail is a curve, and an included angle between a tangent line of the curve and a horizontal plane is 45-60 degrees; the guide rail is arranged at the lower edge of the sealing sheet, and the guide block is arranged at the lower edge of the fixing plate.

Example 5

On the basis of the embodiment 2, the following improvements are further made: in order to obtain enough thermal compensation amount, the linear expansion coefficient of the sealing sheet is more than 30% larger than that of the fixing plate; in order to guarantee the strength and the stability of the sealing device, the thickness of the sealing sheet and the thickness of the fixing plate are not smaller than 3mm, and the upper edge of the sealing sheet is higher than that of the fixing plate. Two-dimensional guiding mechanism is as shown in fig. 7, the guide rail is established at the gasket lower limb, it is downward that the opening is oblique, the groove structure that the slope set up, one side welding of guide block is on the fixed plate, guide block sliding connection is in the recess, the guide block slides along the degree of depth direction of recess, the depth direction of recess is also to the guide rail stroke, the guide rail stroke is about 60 with the horizontal angle, can convert 10 mm's horizontal displacement into 17.32 mm's vertical upward displacement like this, the gasket is when inflation and shrink, two-dimensional guiding mechanism all plays the guide effect.

Example 6

On the basis of the embodiment 5, the following improvements are further made: in order to ensure smooth relative expansion and stable deformation characteristics of the sealing sheet and the fixing plate, the mounting hole of the sealing sheet is a chamfer rectangle, and the width of the sealing sheet in the horizontal direction is not less than the sum of the expansion difference between the sealing sheet and the fixing plate at the corresponding position and the diameter of the clamping bolt; the fixing plate mounting hole is a round hole or a waist hole in the horizontal direction, and the size of the fixing plate mounting hole in the vertical direction is 0.2-5mm larger than the diameter of the clamping bolt.

Example 7

On the basis of the embodiment 2, the following improvements are further made: as shown in fig. 8, a parallelogram cavity is formed on the sealing sheet, and the guide rails are two parallel sides with equal length; the guide block is arranged in the parallelogram cavity and is also parallelogram, the guide block is welded on the fixed plate, two side edges of the guide block are respectively in sliding fit with two side edges of the guide rail, the height of the guide block is smaller than that of the parallelogram cavity, the left side and the right side of the guide block respectively play roles in thermal expansion guide and cold contraction guide, the guide block can only slide up and down along the side edges in the parallelogram cavity, and the upper bottom edge and the lower bottom edge of the parallelogram cavity play roles in lower limit and upper limit.

According to the air preheater hot end sealing device utilizing the expansion difference compensation between the sealing sheet and the fixing plate, the linear expansion coefficient of the sealing sheet is larger than that of the fixing plate, the sealing sheet and the fixing plate are expanded to different degrees when being heated, and meanwhile, the arrangement of the two-dimensional guide mechanism is combined, so that horizontal radial relative displacement is converted into vertical axial upward displacement, a triangular air leakage area of the hot end of the air preheater is compensated to the maximum extent, and the air leakage rate of the air preheater is reduced remarkably; the deformation of the sealing device and the mushroom-shaped deformation of the air preheater are driven by heat, and the deformation directions of the sealing device and the mushroom-shaped deformation of the air preheater are opposite and synchronous, so that the radial clearance of the hot end of the air preheater is kept at a small level all the time; furthermore, the stability is improved, the vicious collision and abrasion are avoided, and the service life of the sealing piece is prolonged.