JPH0510691A - Sealing member for gas preheating device and sealing structure for device using the same - Google Patents

Abstract

PURPOSE:To obtain a sealing member for a gas preheating device, which has high wear resistance, corrosion resistance, and high thermal impact resistance durable against washing in a hot state. CONSTITUTION:A film 3 made of glaze having smaller thermal expansion coefficient than that of alumina ceramics is provided on the surface of a body 8 made of the ceramics. Preferably, the ceramics are exposed from a slide surface 9. It is desirable to set a difference of the coefficients of the body 8 and the film 3 to 9X10<-7>/ deg.C or more.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gas preheater seal member and a gas preheater seal structure using the same.

[0002]

2. Description of the Related Art An air preheater is a thermal power generation boiler, a ship boiler, and other chemical equipment such as oil making, distillation, and reforming furnaces that recover heat from exhaust gas by heat exchange into combustion air to improve thermal efficiency. Is used to increase the
FIG. 10 is a schematic perspective view of the air preheater.

A rotor 11 is rotatably accommodated in a rotor housing 17, and two radial sealing plates 13 are provided on the side surface of the rotor 11 for each rotor side surface. The rotor housing 17 is supported by a pedestal (not shown), and the rotor 11 is rotated by a drive device (not shown) as indicated by arrow H.

Thermal waste gas is circulated on the upper side of the rotor 11 as shown by an arrow D, and air is circulated on the lower side in the opposite direction as shown by an arrow F. The exhaust gas layer and the air layer are shut off by the radial sealing plate 13. A heating element is housed in the rotor 11, and the heating element absorbs heat from the heat exhaust gas D. Then, when the rotor 11 rotates, the cold air is heated when passing through the heating element, and the hot air is sent to the boiler or the like as indicated by an arrow G. On the other hand, since heat is absorbed from the hot exhaust gas,
The cold exhaust gas is discharged to the outside air as shown by arrow E.

In such an air preheater, the rotor 11
There are gaps between the outer peripheral portion of the rotor and the rotor housing 17, and between the side surface of the rotor 11 and the radial sealing plate 13, and exhaust gas and air leak from these gaps, lowering the thermal efficiency. Therefore, it is important to make these gaps as small as possible to enhance the sealing effect.

[0006]

As a method of sealing the gap between the outer peripheral portion of the rotor 11 and the housing 17, structural sealing is performed by making the gap as small as possible.

The temperature of the exhaust gas is 300 to 400 ° C., the temperature of the air is room temperature to 100 ° C., and the rotor 11 which houses the heating element is deformed in response to such temperature change. In a structural seal, the expansion due to such a temperature change or the settling causes the gap to increase and the sealing effect to decrease.

As a method of sealing the gap between the side surface of the rotor 11 and the radial sealing plate 13, a diaphragm plate divided into 12 or 24 pieces is provided on the side surface of the rotor, and the gap between this and the radial sealing plate made of metal is made as small as possible. A structural seal is provided by means of

In such a mere structural sealing method, the sealing effect is limited, and when the structural material is corroded by the exhaust gas component, the gap between the structural materials becomes large and the sealing effect deteriorates. from these things,
It is expected that the sealing effect will be improved by not only simply reducing the gap between the structural materials but also by attaching a seal member to the outer peripheral portion of the rotor and sliding the seal member under pressure on the counterpart housing.

As a sliding member used in a rotary air preheater for boiler combustion in a thermal power plant or the like, it is necessary to have excellent wear resistance, corrosion resistance and thermal shock resistance. The members used SS steel or corrosion resistant steel,
The abrasion resistance and the corrosion resistance are still insufficient, and frequent maintenance is required, which is not particularly satisfactory as a sliding member.

That is, in a rotary air preheater for boiler combustion used in a thermal power plant or the like, the fuel used for the boiler is coal, heavy oil, etc., and therefore sulfur oxides, nitrogen oxides, etc. are contained in the heat exhaust gas. There is a problem that the corrosive gas is contained and dew condensation occurs in the low temperature part of the air preheater, and each component of the air preheater is easily corroded.

In order to solve this problem, the present applicant has disclosed a seal member made of inorganic glass and wear resistant ceramics in the specification of Japanese Patent Application No. 1-184493 (filed on July 19, 1989). This seal member is preferably pressed and slid on a sealing bar, for example, whereby the sealing effect can be most effectively exhibited.

However, as a result of further study by the present inventor, it was found that a problem still remains. That is, there is also a problem that dust in the heat exhaust gas adheres to each component such as the heat element of the air preheater and deteriorates the heat exchange characteristics of the air preheater, and the air preheater is appropriately removed to remove the deposits. Washing with water is carried out. At this time, boilers such as thermal power plants are operated continuously for a long period of time, and the boiler rest period is extremely short.
The above-mentioned deposits are removed by washing with water at 200 ° C. Therefore, air preheater parts are
Severe thermal shock due to the temperature difference. Therefore, for example, when alumina ceramics having extremely excellent wear resistance is adopted as the seal member disclosed in Japanese Patent Application No. 1-184493, there is a problem that the alumina ceramics is broken by the thermal shock.

Further, a rotary air preheater for boiler combustion used in a thermal power plant or the like is a large device having a rotor diameter of 1 to 20 m, and the parts used for the preheater are large. A 200 x 100 x 50 mm seal is used. Therefore, there is a problem that the ceramic used for the seal member is inevitably large in size and is inevitably extremely vulnerable to thermal shock due to the shape effect.

An object of the present invention is to provide a seal member for a gas preheater which has a high degree of wear resistance and a high degree of corrosion resistance, and which has high thermal shock resistance and can withstand washing with water in a hot state. .

[0016]

SUMMARY OF THE INVENTION The present invention is a gas preheater seal member for sealing a gap between an outer peripheral portion of a rotor of a gas preheater and a housing or a side face of the rotor and a radial sealing plate. The present invention relates to a sealing member for a gas preheater, in which a coating made of glaze having a thermal expansion coefficient smaller than that of the main body made of alumina ceramics is provided on the surface of the main body.

[0017]

According to the present invention, since the main body of the seal member for the gas preheater is made of alumina ceramics, the amount of wear on the sliding surface of the seal member can be reduced and the corrosion by sulfur oxide and nitrogen oxide can be suppressed. can do. That is, alumina ceramics has higher hardness and excellent wear resistance than metals. Further, for example, the exhaust gas of the air preheater contains sulfur oxides, nitrogen oxides, etc., which react with water to generate sulfuric acid, sulfurous acid, nitric acid, nitrous acid, etc. It is stable.

On the other hand, alumina ceramics have the drawback of low thermal shock resistance and cannot withstand washing with water in a hot state of about 200 ° C. However, in the present invention, since the coating made of glaze having a coefficient of thermal expansion smaller than the coefficient of thermal expansion of the body made of alumina ceramics is provided on the surface of the body, this glaze acts as a compression glaze, and the body made of alumina ceramics is , Protects against thermal shock such as washing with water. With the above-described unique structure, the seal member of the present invention simultaneously satisfies extremely high wear resistance, corrosion resistance and thermal shock resistance.

In order to obtain this function and effect satisfactorily, it is preferable that the difference between the coefficient of thermal expansion of the main body and the coefficient of thermal expansion of the coating is 9 × 10 ⁻⁷ / ° C. or more. Further, in order to maintain the wear resistance and corrosion resistance of the main body at a high level, the alumina content in the alumina ceramics forming the main body must be 85% by weight or more.

An example of the components of the glaze which can be used under such conditions is shown below. SiO ₂ 60.0 to 74.0 wt% Al ₂ O ₃ 11.0 to 17.0 〃 Fe ₂ O ₃ <0.7 〃 TiO ₂ <0.3 〃 CaO 1.0 〜 5.0 〃 MgO 1.0 〜 5.5 〃 K ₂ O, Na ₂ O 3.0 〜 8.0 〃 ZrO ₂ 1.5 to 3.5 〃 BaO <4.0 wt% MnO, CoO <0.3 〃

If only the alumina ceramics is exposed on the sliding surface of the sealing member, the high wear resistance of the alumina ceramics can be effectively exhibited. In this case, it is effective to enhance the thermal shock resistance of the sealing member by covering 50% or more of the total surface area other than this sliding surface with a glaze film. In this sense, the film thickness is 100 μm. The above is also preferable.

[0022]

First, an outline of an air preheater (an example of a gas preheater) to which the seal member of the present invention should be applied will be described.

FIG. 6 is a schematic side view of the air preheater, and FIG. 7 is a schematic front view of the same. A rotor 11 held by a rotating shaft 14 is housed in a housing 17. The rotor 11 is divided into 12 or 24 pieces by a diaphragm plate 12, and a heating element 15 is installed therein. The housing is separated into an exhaust gas tank and an air tank. When the rotor rotates, the heat amount of the exhaust gas is stored in the heating element in the exhaust gas tank, and the air is heated in the air tank. Exhaust gas is, for example, 350 ° C, air is 60
After passing through the air preheater at ℃, the exhaust gas is cooled to 140 ℃ and the air is heated to 300 ℃. Air is pressurized and flows into the boiler, but the pressure difference between air and exhaust gas is, for example, 2500
It is about mmaq. Therefore, when the air passes through the air preheater, some leakage occurs in the exhaust gas tank due to the pressure difference.

The leakage path is partly on the side of the rotor, the diaphragm plate 12 and the radial sealing plate 13.
Happens through the gap in. Second, it occurs at the outer periphery of the rotor 11 through the gap in the axial sealing plate 16. Further, the exhaust gas and the air held in the gaps between the heating elements flow into the air tank and the exhaust gas tank, respectively, by the rotation of the rotor, and leak.

A seal structure has been devised to minimize such leakage. A method of sealing by making the distance between the diaphragm plate 12 and the radial sealing plate 13 as small as possible is called a radial seal B. A method of sealing by making the space between the housing 17 and the axial sealing plate 16 installed on the outer circumference of the rotor as small as possible is called an axial seal A. Further, in order to prevent exhaust gas and air from flowing into the gap between the rotor outer periphery and the housing, the seal structure 18 is installed on the side surface of the rotor outer periphery, and the housing 17
The method of sealing by minimizing the distance from the sealing bar 19 attached to the above is called a bypass seal C.

The seal member of the present invention is used for at least one of the three seal portions of the radial seal B, the axial seal A and the bypass seal C. That is, the “seal of the gap between the outer peripheral portion of the rotor of the gas preheater and the housing” corresponds to the axial seal A and the bypass seal C. The “seal of the gap between the side surface of the rotor and the radial sealing plate” corresponds to the Radial B.

An example in which the present invention is applied to the bypass seal C will be described. FIG. 5 is a schematic view showing the vicinity of the outer circumference of a rotor of a vertical axis type air preheater. In this example, the present invention is applied to the sealing between the outer peripheral edge of the rotor 11 and the housing. That is, in the upper bypass seal portion in FIG. 5, the holder 21 is fixed to the sealing bar 19, and the seal structure 1 is held in the holder 21. At this time, the seal structure 1 can be slightly moved up and down in the holder 21, and the sliding surface of the seal structure 1 contacts the rotor tire 20 by its own weight and slides. There is a slight gap between the seal structure 1 and the sealing bar 19. With this structure, the rotor 11 expands due to heat,
When contracted, the seal structure 1 follows the deformation of the rotor 11.

In the lower bypass sealing portion in FIG. 5, the holder 21 is fixed to the rotor tire 20, and the seal structure 1 is held in the holder 21. The seal structure 1 can be slightly moved up and down in the holder 21, and the sliding surface of the seal structure 1 contacts the sealing bar 19 by its own weight and slides.

In this vertical axis type air preheater,
The seal structure 1 is pressed against the sealing bar 19 or the rotor tire 20 by the weight of the seal structure 1. On the other hand, in the case of the horizontal axis type air preheater, the self-weight of the seal structure 1 cannot be used, so the seal structure 1 must be urged toward the mating member by a leaf spring, a coil spring, or the like. I have to.

This seal structure 1 has a structure in which the seal member of the present invention is attached to a hollow frame. Therefore, first, a configuration example of the seal member for an air preheater according to the present invention will be described with reference to FIGS. 1 (a) to 1 (d), and then the overall configuration of the seal structure 1 to which these seal members are attached The description will be made with reference to FIGS.

As shown in FIGS. 1 (a) to 1 (d), the alumina ceramics main body 8 is formed in a truncated pyramid shape,
Its bottom surface and sliding surface 9 are rectangular. The surface of the main body 8 is composed of a pair of trapezoidal side surfaces 8a, a pair of rectangular side surfaces, a bottom surface and a sliding surface 9. A total of four side portions 8c are formed between the side surfaces 8a and 8b, and a total of four side portions 8c are formed between the side surfaces 8a and 8b and the bottom surface.
One side portion 8d is formed, and a total of four side portions 8e are formed between the side surfaces 8a, 8b and the sliding surface 9. Further, four apex portions 8f contacting the side surfaces 8a, 8b and the sliding surface 9 and four apex portions 8g contacting the side surfaces 8a, 8b and the bottom surface are formed.

The bottom surface and the lower portions of the side surfaces 8a, 8b are covered with a coating 3 made of glaze. Alumina ceramics is exposed at the upper part of the sliding surface 9 and the side surfaces 8a and 8b. And the sides 8a, 8b
And 50% of the total area of the bottom surface is covered by the coating 3, and the remaining
Alumina ceramics are exposed in 50% of the area. In addition,
The radius of curvature of the side portions 8c, 8d, 8e and the top portions 8f, 8g is preferably 2 mm or more.

In the example shown in FIG. 1 (b), the coating 3 made of glaze covers the side portions 8c, 8d and the top portion 8g which are not in contact with the sliding surface and the bottom surface. The trapezoidal alumina ceramics are exposed from the side surface 8a, and the rectangular alumina ceramics are exposed from the side surface 8b. With such a configuration, the action of the coating 3 as a compression glaze is further enhanced.

Also in the example shown in FIG. 1C, the bottom surface and the lower portions of the side surfaces 8a and 8b are covered with the coating 3 made of glaze, as in the example shown in FIG. 1A. However, the surface excluding the sliding surface 9, that is, 70% of the side surfaces 8a, 8b and the bottom surface is covered with the coating film 3, and the alumina ceramics is exposed in the remaining 30% of the area. In the example shown in FIG. 1D, the alumina ceramics is exposed on the sliding surface 9, and the other surfaces are all covered with the coating 3.

FIG. 2 shows the sealing member of FIG.
FIG. 3 is a sectional view showing the individually attached seal structure 1, FIG. 3 is a fragmentary perspective view of the seal structure 1, and FIG. 4 is a side view of the seal structure 1. The coating 3 is not shown in FIGS.

Preferably, a substantially rectangular parallelepiped hollow frame body 2 is formed of corrosion-resistant steel, and each vertex of the frame body 2 is provided with R (R). A plurality of (two in this example) holes 2a are formed in the longitudinal direction on the side of the frame body 2 facing the sealing bar. Inside the two holes 2a,
The slip-out prevention member 7 is fixed by welding or the like, and a slender seal member 8 having a trapezoidal cross section is fitted into the slip-out prevention member 7. The flat sliding surface 9 of the seal member, which should slide with respect to the sealing bar, is exposed, and the other portions are substantially covered with the frame body 2 and the slip-off preventing member 7 and are not exposed. That is, the side surface 8b and the bottom surface 8h side are the removal preventing member 7
And the side surface 8a side is covered with the frame body 2.

According to this embodiment, since the sliding surface 9 of the seal member 8 and the sealing bar are slid under pressure, the above-mentioned effect of the alumina ceramics is great, and deformation, wear, corrosion and the like of the seal member are caused. It is possible to further improve the thermal efficiency by preventing a gap from being generated without causing the gap.

At the same time, since a coating made of glaze having a coefficient of thermal expansion smaller than that of the body 8 is provided on the surface of the body 8 made of alumina ceramics, the glaze is compressed as described above. It functions as a glaze and protects the alumina ceramic body 8 against thermal shock caused by washing with water or the like. Moreover, since the sealing member is surrounded by corrosion-resistant steel except for the sliding surface 9, this corrosion-resistant steel also acts as a buffer against thermal shock caused by washing with water or the like.

Therefore, according to such a seal member, the sealing effect is high and the life is long, and the air preheating efficiency of, for example, thermal power generation, ship boilers, etc. can be increased, and oil making, distillation and reforming furnaces are also possible. When applied to chemical equipment such as, the efficiency of heat recovery is increased. Further, the safety during use is increased and the frequency of maintenance can be reduced.

Next, more specific experimental results will be described. (Experiment 1) First, a seal member shown in FIG.
For this, the difference in cold heat cracking temperature was measured. In particular,
A body 8 having a width of 45 ± 0.5 mm, a height of 20 ± 0.3 mm, a length of 42 ± 0.3 mm, and a radius of curvature of 2 mm at the top was prepared. The Al ₂ O ₃ content in this alumina ceramics was 96% by weight. Glaze slurry was spray-coated to a predetermined thickness on all the surfaces of the main body 8 except the sliding surface 9, dried, baked, and cooled to prepare each test sample.

The thickness of the glaze coating after firing is 100 ±
It was set to 20 μm. By changing the composition of the glaze,
As shown in FIG. 8, the thermal shock resistance test was carried out for each sample while changing the difference in the coefficient of thermal expansion between the alumina ceramic body and the glaze.

Specifically, each sample was held at each predetermined temperature for a sufficiently long time and then immersed in a water tank containing a large amount of water at the predetermined temperature for a certain period of time. After the sample was taken out of the water tank, the presence or absence of cracks in the sample was checked with a fuchsin solution.
Then, the minimum value of the temperature difference between the heating temperature and the water temperature when a crack was generated in the sample was displayed as the cold heat cracking temperature difference (° C). The result is shown in FIG.

As can be seen from the results shown in FIG. 8, the difference in cold crack temperature between the samples having no glaze on the surface of the main body is 120 ° C.
On the other hand, the difference in cold heat cracking temperature of the sample in which the glaze was applied to all surfaces except the sliding surface of the main body increased as the difference in thermal expansion coefficient between the alumina ceramics and the glaze increased. More specifically, the difference in thermal expansion coefficient is 9 × 10 ⁻⁷
The temperature difference between cold and heat cracks increased significantly from around 20 ° C / ° C.
It became almost flat from around ^-7 / ℃.

When spraying glaze sludge onto the alumina ceramic body, the body should be heated to approximately 150 ° C.
It is preferable to heat the glaze to a uniform thickness so that a glaze having a considerable thickness can be applied.

(Experiment 2) The content of the alumina component in the main body 8 was variously changed as shown in FIG.
The specific wear of the body 8 (× 10 ^-11 mm ² /
N) was measured. As can be seen from the results of FIG. 9, as the content of the alumina component in the main body 8 increased, the specific wear amount decreased geometrically. Especially, if the content of alumina component is 85% by weight or more, the specific wear amount is 30 × 10 ^-11 mm ²
It becomes / N or less, and practically high wear resistance can be imparted.

(Experiment 3) With respect to the alumina ceramics main body which was not subjected to glaze, the content of the alumina component was changed as shown in Table 1 and the temperature difference of cold heat cracking was measured. As can be seen from Table 1, as the content of the alumina component increases, the difference in cold heat cracking temperature decreases, and the content of the alumina component increases.
At 96% by weight, the difference in cold cracking temperature decreased to 120 ° C.

On the other hand, a glaze A having a thermal expansion coefficient of 69 × 10 ^-7 / ° C or a glaze B having a thermal expansion coefficient of 52 × 10 ^-7 / ° C was applied to the entire surface of the main body except the sliding surface to a thickness of 550 μm. As a result, the sample shown in FIG. 1 (d) was obtained. These results are also shown in Table 1 below.

[0048]

[Table 1]

As a result of measuring the difference in cold heat cracking temperature of these samples, as shown in Table 1, the difference in cold heat cracking temperature was improved by applying glaze. Alumina content of 85% by weight
The difference in cold heat cracking temperature is significantly improved in a larger area, for example, when the alumina content is 96%, the coefficient of thermal expansion is 52 × 10 ^-7 /
Temperature difference of cold heat cracking is 88 ℃ by applying glaze which is ℃
Also improved. Therefore, it was clarified that even alumina ceramics, which has high abrasion resistance and high corrosion resistance but originally has low thermal shock resistance, can sufficiently withstand a thermal shock of 170 to 200 ° C. by applying a glaze.

(Experiment 4) A seal member as shown in FIG. 1 (d) was prepared. However, the content of the alumina component in the main body 8 was 96%, and the difference in the coefficient of thermal expansion between the main body 8 and the coating 3 made of glaze was 26 × 10 ⁻⁷ / ° C. Then, the thickness of the glaze was increased and the difference in cold heat cracking temperature was measured, and the results shown in Table 2 were obtained. That is, by applying a glaze having a thickness of 100 μm or more, the difference in cold heat cracking temperature is remarkably improved, and thermal shock resistance that can be provided as a sealing member can be added to the alumina ceramics.

[0051]                 Table 2 ────────────────────────────────   Thickness of coating made of glaze (μm) Cold heat cracking temperature difference (℃) ────────────────────────────────             0 120           50 130           90 140         100 170         320 182         550 208         780 210

(Experiment 5) First, the main body 8 having the dimensions described in Experiment 1 was prepared. Here, the content of the alumina component of the main body 8 is set to 96%, and the difference in thermal expansion coefficient between the main body 8 and the glaze is 26 ×.
The temperature was 10 ⁻⁷ / ° C., and the thickness of the glaze was 550 μm. The main body 8 was glazed as shown in FIGS. 1 (a), 1 (b), 1 (c), and 1 (d) to prepare samples.

Specifically, in the example of FIG. 1 (a), the sliding surface 9
The area of 50% of the entire surface except for was covered with a coating made of glaze. In FIG. 1 (b), glaze is applied so as to cover the side portions 8c and 8d, but at this time, the side surface 8 is formed along the side portions 8c and 8d.
The width d of the coating 3 provided on a and 8b was set to 8 mm. Figure 1
In the example of (c), 70% of the entire surface except the sliding surface 9 is covered with a coating made of glaze.

When the difference in cold heat cracking temperature between the samples of FIGS. 1 (a) to 1 (d) and the sample without glaze was measured, the following results were obtained. Cold cracking temperature difference (℃) Sample without glaze 120 Sample 165 of FIG. 1 (a) 165 Sample of FIG. 1 (b) 178 Sample of FIG. 1 (c) 188 Sample of FIG. 1 (d) 208

Further, while basically using the coating pattern of FIG. 1 (a) and changing the area to which the glaze was applied, the cold crack temperature difference was measured, and the following results were obtained.

[0056]     Glaze area (%) Cold heat cracking temperature difference (℃)             0 120           40 130           50 165           60 178           70 188           80 208

(Experiment 6) First, the main body 8 having the dimensions described in Experiment 1 was prepared. The content of this alumina component was 96%. This main body 8 was designated as Sample No. 1. Then, the main body 8 was mounted in the seal structure 1 as shown in FIGS. However, the frame body 2 and the slip-out preventing member 7 were both formed of SUS430 steel having a thickness of 3 mm. This is sample N
o.2.

Next, on all surfaces of the main body 8 except the sliding surface 9,
A glaze with a thickness of 550 ± 50 μm was applied. The difference between the coefficient of thermal expansion of this glaze and the coefficient of thermal expansion of the main body 8 was 46 × 10 ⁻⁷ / ° C. (Sample No. 3). Then, this sample was sealed as shown in FIGS. It was mounted in structure 1. However, both the frame body 2 and the slip-out prevention member 7 are made of SUS430 having a thickness of 3 mm.
Made of steel. This was designated as Sample No. 4.

The results of measuring the cold heat cracking temperature difference of these sample Nos. 1 to 4 are shown below. Thermal cracking temperature difference (℃) Sample No. 1 120 ± 11 Sample No. 2 140 ± 14 Sample No. 3 208 ± 17 Sample No. 4 253 ± 13

As can be seen from the above results, the thermal shock resistance of the sample No. 3 to which the glaze was applied according to the present invention was remarkably improved, and the sample No. 3 in which the sample No. 3 was covered with a metal plate was used. In No. 4, the thermal shock resistance is further improved because the metal plate has a large buffering effect against thermal shock.

[0061]

According to the present invention, since the main body of the seal member for the gas preheater is made of alumina ceramics, the amount of wear on the sliding surface of the seal member can be reduced and the seal made of sulfur oxide or nitrogen oxide can be used. Corrosion of members can also be suppressed. Moreover, since a coating made of glaze having a coefficient of thermal expansion smaller than that of the alumina ceramic body is provided on the surface of the body, this glaze acts as a compression glaze and heats the alumina ceramic body by washing with water etc. Protect against impact. With these, high wear resistance, high corrosion resistance, and high thermal shock resistance can be imparted to the seal member at the same time, and good sealing performance can be maintained for a long period of time.

[Brief description of drawings]

1 (a), (b), (c) and (d) are perspective views each showing a seal member used for a bypass seal of an air preheater.

FIG. 2 is a cross-sectional view showing a seal structure.

FIG. 3 is a fragmentary perspective view of the seal structure.

FIG. 4 is a side view showing a seal structure.

FIG. 5 is a schematic diagram showing the vicinity of the outer circumference of the rotor of the air preheater.

FIG. 6 is a schematic side view showing the entire air preheater.

FIG. 7 is a schematic front view showing the entire air preheater.

FIG. 8 is a graph showing the relationship between the difference in thermal expansion coefficient between the alumina ceramics body and the glaze and the difference in cold heat cracking temperature.

FIG. 9 is a graph showing the relationship between the alumina component content and the specific wear amount in the main body.

FIG. 10 is a perspective view schematically showing the configuration of an air preheater.

[Explanation of symbols]

1 Seal structure 2 Hollow frame 3 Film made of glaze 7 Removal prevention member 8 Alumina ceramic body 8c, 8d, 8e sides 8f, 8g top 9 Sliding surface 11 rotor 13 Radial sealing plate 16 Axial Sealing Plate 17 housing 20 rotor tire 21 holder A Akijar seal B radial seal C bypass seal

Claims (9)

[Claims] 1. A seal member for a gas preheater, which seals a gap between an outer peripheral portion of a rotor of a gas preheater and a housing or a side face of the rotor and a radial sealing plate, the seal member being provided on a surface of an alumina ceramic body. A sealing member for a gas preheater provided with a coating made of glaze having a thermal expansion coefficient smaller than that of the main body. 2. The seal member for a gas preheater according to claim 1, wherein a difference between a coefficient of thermal expansion of the main body and a coefficient of thermal expansion of the coating film is 9 × 10 ⁻⁷ / ° C. or more. 3. The main body has an alumina content of 85% by weight.
The sealing member for a gas preheater according to claim 1, which is made of the alumina ceramics described above. 4. The alumina ceramics is exposed only on the sliding surface of the gas preheater seal member, and 50% or more of the total area of the surfaces other than the sliding surface is covered with the coating. The seal member for a gas preheater according to 1. 5. The thickness of the coating is 100 μm or more,
The seal member for a gas preheater according to claim 4. 6. The sealing member for a gas preheater according to claim 4, wherein, of the side portion and the top portion of the main body, all of the side portion and the top portion which are not in contact with the sliding surface are covered with the coating. 7. The seal member for a gas preheater according to claim 4, wherein all surfaces except the sliding surface are substantially surrounded by metal. 8. The radius of curvature of the side portion and the top portion of the main body is 2
The seal member for a gas preheater according to claim 1, having a size of at least mm. 9. The gas preheater according to claim 1, wherein a hollow frame body, a removal prevention member fixed to the frame body so as to project into an inner space of the frame body, and fitted into the removal prevention member. A sealing member for a gas preheater, wherein a flat sliding surface of the sealing member for a gas preheater is exposed from the opening of the frame toward the outside of the frame, and the sealing member for the gas preheater is A seal structure for a gas preheater, wherein a portion other than a sliding surface is covered with the frame body and the slip-out preventing member.