JPH0361076B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to a sealing structure between a ceramic tube and a tube plate in, for example, a dust collector, a heat exchanger, etc.

"Prior Art and its Problems" Conventionally, in heat exchangers using metal tubes, the tubes have been attached by welding directly to the tube plate or by expanding the tubes. Therefore, the airtightness between the heating fluid and the heated fluid was sufficiently maintained. However, it is difficult to exchange heat with a high-temperature fluid of, for example, 800° C. or higher using a metal tube. In such cases, ceramic tubes are used, but
Needless to say, in this case, connection by welding or pipe expansion is not possible. Furthermore, when connecting ceramic tubes, it is necessary to have a structure that absorbs the difference in thermal expansion and mechanical shock that occurs between the ceramic tube and the metal tube plate or can body. The same situation applies to dust collectors using porous ceramic tubes.

JP-A-60-62592 discloses that the end of a ceramic tube is formed into a convex or concave spherical shape, and a concave or convex spherical part is formed in which the spherical part fits into a tube holding member. However, a seal structure has been proposed in which a spherical part of the end of a ceramic tube and a spherical part of a tube holding member are butted against each other to form a spherical connection. In this seal structure, good sealing performance is obtained due to the spherical coupling, and the positional deviation between the ceramic tube and the tube holding member can be absorbed to some extent.

However, with the above sealing structure, it is extremely difficult to process the end of the ceramic tube into a spherical shape, and when the ceramic tube is long, it is difficult to support it with a tube plate at the middle part. There was a problem that I couldn't do it. The same publication also describes a method in which an end piece is attached to the end of a ceramic tube to make the end piece spherical, but when the end piece is attached, the diameter of the flow path of the ceramic tube is reduced at that part. A problem arose.

``Object of the Invention'' An object of the present invention is to facilitate the formation of the spherical part in a structure that uses the spherical part to support and seal a ceramic tube in the insertion hole of the tube sheet, and to provide a structure that supports and seals a ceramic tube in the insertion hole of the tube plate, and that enables the formation of the spherical part not only at the end of the pipe but also at the end of the tube. It is an object of the present invention to provide a sealing structure between a ceramic tube and a tube sheet, which allows the tube to be supported by the tube sheet at any intermediate portion thereof.

"Structure of the Invention" The sealing structure between a ceramic tube and a tube plate according to the present invention includes: attaching a metal annular member to the outer periphery of the ceramic tube, and forming at least a part of the outer circumferential surface of the annular member into a spherical shape; It is characterized in that the spherical portion is brought into contact with the inner periphery of the insertion hole of the tube plate from above.

In this way, in the present invention, a metal annular member that can be formed separately from the ceramic tube is attached to the ceramic tube, and the outer peripheral surface of the metal annular member is formed into a spherical shape. It is easier to form a spherical part than by directly processing the spherical part. Further, unlike when an end piece is provided, the diameter of the flow path of the ceramic tube is not reduced. Furthermore, since the metal annular member can be attached to any location in the longitudinal direction of the tube, it is possible to support not only the ends of the ceramic tube, but also the intermediate portion of the ceramic tube.

Then, since the spherical part of the metal annular member attached to the ceramic tube and the inner periphery of the insertion hole of the tube plate are brought into contact from above, the weight of the ceramic tube and the metal annular member is added to bring them into line contact. The surface pressure on the surface is increased and good sealing performance is obtained. Moreover, even if the ceramic tube and tube sheet do not abut at a precisely perpendicular angle, the spherical joint ensures sealing performance. Furthermore, in a spherical joint, a slight deviation along the spherical surface is allowed, so no special consideration is required in manufacturing and assembly.

"Embodiment of the Invention" FIG. 1 shows an embodiment applied to a dust collector of the present invention.

The can body 14 includes a dust-containing gas inlet 15, cleaning gas outlets 16a and 16b, and a hopper 17.
Also, inside the can body 14, there are three upper and lower tube plates 18.
a, 18b, and 18c are arranged at predetermined intervals. Insertion holes 13a, 13b, 13c are formed in each tube plate 18a, 18b, 18c.
And these insertion holes 13a, 13b, 13c
A plurality of air-permeable porous ceramic tubes 11 are inserted through and supported. In this case, the ceramic tube 11
Metal annular members 12a, 12b, 12c are attached to the upper end, middle, and lower end, and the outer peripheral surfaces of the metal annular members 12a, 12b, 12c are the same as the tube plates 18a, 18b, 18c. insertion hole 13
They are supported in contact with the inner peripheries of a, 13b, and 13c, respectively.

The characteristic feature of the present invention is that, in the above, the metallic annular members 12a, 12b, 12c
It has a sealing structure between the outer circumferential surface of and the inner circumference of the insertion holes 13a, 13b, and 13c. Therefore, to explain the sealing structure between the metallic annular member 12c at the lower end and the insertion hole 13c, as shown in FIG. The outer peripheral surface of the metallic annular member 12c is formed into a spherical shape having a center P on the axis l of the ceramic tube 11. On the other hand, the inner periphery of the insertion hole 13c of the tube plate 18c forms a tapered wall that is narrowed downward. Then, the spherical part of the metallic annular member 12c is inserted into the insertion hole 1.
A seal is made in line contact with the inner circumference of 3c.
The seal structures of the other metallic annular members 12a and 12b are also similar to those described above.

In the above configuration, the combined dust gas is introduced from the combined dust gas inlet 15, flows through each ceramic pipe 11, passes through the wall of the ceramic pipe 11, and at that time, dust is removed and becomes a clean gas. The gas is taken out from the gas outlet ports 16a and 16b. Also,
The removed dust passes through the inside of the ceramic tube 11 as it is, is collected in the hopper 17, and is taken out to the outside at an appropriate time. In this way, dust can be removed from the dust-containing gas to produce clean gas.

In the present invention, the ceramic tube 11
A metal annular member 12a, 1 attached to the outer periphery of
The outer peripheral surfaces of 2b and 12c are spherical, and the spherical portion forms a tapered wall of the insertion holes 13a, 13b, 13.
Since it is supported in contact with the inner periphery of c, the abutting portion is in line contact, high contact surface pressure is obtained, and good sealing performance is obtained. Therefore, the tube plate 18a,
A seal between 18b, 18c and the ceramic tube 11 is ensured, and leakage of dust-containing gas to the clean gas side can be prevented. In addition, the spherical parts of the metallic annular members 12a, 12b, 12c and the insertion hole 1
3a, 13b, and 13c are supported by joining with the tapered walls, a slight deviation along the spherical part can be tolerated. For example, the ceramic tube 11 and the tube plate 18
A, 18b, and 18c are not connected at exactly perpendicular angles to ensure sealing performance. This also applies when displacement occurs due to thermal shock or mechanical shock.

Further, in the present invention, a metallic annular member 12 having a spherical outer peripheral surface is attached to the outer periphery of the ceramic tube 11.
a, 12b, and 12c are attached, processing is easier than directly processing the end of the ceramic tube 11 into a spherical shape. Furthermore, unlike the case where an end piece is provided, the diameter of the internal flow path of the ceramic tube 11 is not reduced. In addition, the metallic annular members 12a, 12b, 12c are connected to the ceramic tube 11.
It can be attached to any location along the longitudinal direction of the ceramic tube 11, and the ceramic tube 11 can be supported at a plurality of locations.

On the other hand, the insertion holes 1 of the tube plates 18a, 18b, 18c
3a, 13b, and 13c are formed directly on the tube sheet in the above embodiment, but they may be formed by attaching a concave annular member having a tapered inner wall to the insertion hole of the tube sheet.

When selecting the material of the metallic annular members 12a, 12b, 12c and the material of the inner periphery of the insertion holes 13a, 13b, 13c, either they should have the same hardness, or the inner periphery of the insertion hole should have a harder hardness. It is preferable to have the following. Metallic annular member 1
2a, 12b, 12c are attached to the ceramic tube 11, so their replacement is relatively easy, whereas the insertion holes 13a, 13b, 13c are formed in the tube plates 18a, 18b, 18c. This is because there are circumstances in which replacement or repair cannot be carried out frequently. Therefore, in a combination of the two, it is preferable to apply heat treatment only to the inner periphery of the insertion hole.

Further, metallic annular members 12a, 12b, 12
Preferably, the surfaces of the contact portions between the spherical portion c and the tapered walls of the insertion holes 13a, 13b, and 13c are each precision-machined, thereby further improving the sealing performance.

By the way, in the above embodiment, the insertion holes 13 are formed in the spherical portions of the metallic annular members 12a, 12b, and 12c.
Although the tapered walls of the insertion holes 13a, 13b, and 13c are in contact with each other, various shapes can be adopted for the inner peripheral shapes of the insertion holes 13a, 13b, and 13c as long as they are rotationally symmetrical. To explain the seal structure at the lower end of the ceramic tube 11, for example, as shown in FIG. 3, the inner periphery of the insertion hole 13c may be formed into a concave spherical shape. In this case, the metallic annular member 12
When the radius of the spherical surface of c is R1, and the radius of the concave spherical surface of the insertion hole 13c is R2, it is necessary that R1<R2. Further, as shown in FIG. 4, the insertion hole 13c can be shaped like a bell mouth (a bell opening shape). In any of these cases, the outer periphery of the metallic annular member 12c and the insertion hole 1
3c is in line contact with the inner periphery, and good sealing performance is obtained.

In the seal structure shown in FIG. 2, the radius of the spherical part of the metallic annular member 12c is 250 mm, and the insertion hole 1
The inclination θ of the taper ring in 3c is 80°. Also,
In the seal structure shown in Figure 3, R1<R2=250
mm. Furthermore, in the seal structure shown in FIG. 4, the radius R1 of the metallic annular member 12c is 250 mm,
The radius R3 of the inner wall of the insertion hole 13c is 150 mm.
Then, the sealing performance was adjusted so that a force of 30 kg was applied to each sealing part, and the leakage rate of particles with a particle size of 0.3 μm was 0% in all cases. All seal parts are made of metal, and their surfaces are precisely machined.

In the above embodiment, the metallic annular member 12
A, 12b, and 12c have a structure in which they are directly fixed to the ceramic tube 11, and in this case, a method of fixing with an adhesive can be adopted as the fixing method. Also, a heat-expandable mat can be used instead of the adhesive. That is, the ceramic tube 11 and the metallic annular members 12a, 12b, 12c
In this method, a heat-expandable mat is interposed between the ceramic tube 11 and the ceramic tube 11, and the ceramic tube 11 is gripped and fixed by its thermal expansion. In addition, heat-expandable matte refers to heat-expandable materials such as vermiculite and pearlite,
It is formed into a mat shape by bonding ceramic fibers mainly composed of alumina, silica, etc. with an organic binder, and when heated to a certain extent, it expands by about 1.5 to 3 times in the thickness direction. It has the property of maintaining its expanded state even if the temperature is subsequently raised and lowered repeatedly.

Furthermore, the structure for attaching the metallic annular members 12a, 12b, 12c to the ceramic tube 11 is as follows.
For example, a structure as shown in FIG. 5 can also be adopted. Incidentally, FIG. 5 shows a seal structure applied to the intermediate portion of the ceramic tube 11. That is, a ceramic flange 20 is fixed to the outer periphery of the ceramic tube 11 via an adhesive 19. Then, the metal annular member 12b and the presser ring 21 are attached so as to sandwich the flange 20, and are tightened and fixed with bolts 22. Annular member 1
2b and the holding ring 21 are both made of metal. The outer periphery of the annular member 12b is formed into a spherical shape centered on a point P on the axis l of the ceramic tube 11. According to this mounting structure, the bolt 22
There is an advantage that the annular member 12b can be easily replaced by attaching and detaching the annular member 12b.

The pressing force applied between the metallic annular members 12a, 12b, 12c and the insertion holes 13a, 13b, 13c is determined by the weight of the ceramic tube 11 (for example, 250 mm in diameter) when the contact surfaces are precisely machined.
In the case of a ~300mm pipe, the sum of the weight of the metal annular member (10~20Kgf) is sufficient, but several kgf/
For sealing high pressures of cm ² or more, or for sealing high pressures of several thousand mm
If leakage is absolutely not allowed even under a differential pressure of about Aq, use the metallic annular members 12a, 12b, 1
A downward force may be applied to the spherical portion 2c. In that case, a heavy chain may be added, but it is also possible to have a structure as shown in FIG.

That is, in the seal structure shown in FIG. 6, ceramic tubes 11a and 11b are arranged one above the other, and their upper and lower ends are supported by tube plates 18a and 18b. Metal annular members 12a, 12b are attached to the lower ends of the ceramic tubes 11a, 11b. The outer peripheral surfaces of the metallic annular members 12a and 12b are spherical as described above. And the insertion holes 13a, 13b of the tube plates 18a, 18b.
The inner periphery of the annular members 12a and 12b is a tapered wall, and the outer peripheries of the annular members 12a and 12b are in contact with this tapered wall to form a seal. A metal bellows 24 is attached to the upper end of the ceramic tube 11b, and this bellows 24 is attached to the upper end of the ceramic tube 11b.
It is connected to the metallic annular member 12a of a.
Therefore, the ceramic tubes 11a and 11b are in communication via the bellows 24. In this case, the bellows 24 is in a compressed state and imparts its elastic force to the ceramic tube 11b below.

In the above sealing structure, the elastic force of the bellows 24 acts on the lower ceramic tube 11b, so that the metallic annular member 12b is strongly pressed against the insertion hole 13b. Therefore, better sealing performance can be obtained. Further, since the bellows 24 absorbs the axial displacement due to the difference in thermal expansion between the ceramic tube 11b and the tube plates 18a and 18b, stress concentration on the ceramic tube 11b can be avoided and damage can be prevented.

"Effects of the Invention" As explained above, according to the present invention, the ceramic tube is fitted with a metallic annular member and the outer peripheral surface of the metallic annular member is formed into a spherical shape. It is easier to form a spherical part than by direct processing. Further, unlike when an end piece is provided, the diameter of the flow path of the ceramic tube is not reduced. Furthermore, since the metallic annular member can be attached to any location in the longitudinal direction of the ceramic tube, it is possible to support the ceramic tube at an intermediate portion or the like. Since the spherical part of the metallic annular member attached to the ceramic tube and the inner periphery of the insertion hole in the tube plate are brought into contact with each other through line contact, the surface pressure on the contact surface is high and good sealing performance is obtained. . Moreover, even if the ceramic tube and tube sheet do not abut at a precisely perpendicular angle, the spherical joint ensures sealing performance. Furthermore, in a spherical joint, a slight deviation along the spherical surface is allowed, which facilitates manufacturing and assembly. Furthermore, since organic rubber and gaskets are not required in the sealing part, a cooling structure for cooling the sealing part can be omitted, simplifying the structure and reducing heat loss.

[Brief explanation of drawings]

Fig. 1 is a sectional view showing an embodiment in which the seal structure according to the present invention is applied to a dust collector, Fig. 2 is a sectional view of the main part of the same seal structure, and Fig. 3 is another embodiment of the seal structure according to the present invention. FIG. 4 is a sectional view of a main part showing still another embodiment of the seal structure according to the present invention, and FIG. 5 is another example of a mounting structure for a metal annular member in each of the above embodiments. FIG. 6 is a sectional view showing still another embodiment of the seal structure according to the present invention. In the figure, 11, 11a, 11b are ceramic tubes,
12a, 12b, 12c are metallic annular members;
3a, 13b, 13c are insertion holes, 18a, 18
b, 18c are tube plates.

Claims (1)

[Scope of Claims] 1. A metal annular member is attached to the outer periphery of the ceramic tube, at least a part of the outer periphery of the annular member is formed into a spherical shape, and the spherical surface is applied to the inner periphery of the insertion hole of the tube plate from above. A sealing structure between a ceramic tube and a tube plate, characterized by a linear contact between the parts. 2. A sealing structure between a ceramic tube and a tube sheet according to claim 1, wherein the inner periphery of the insertion hole of the tube sheet is a tapered wall. 3. A sealing structure between a ceramic tube and a tube plate according to claim 1, wherein the inner periphery of the insertion hole of the tube plate has a spherical shape with a radius larger than that of the spherical portion. 4. A sealing structure between a ceramic tube and a tube sheet according to claim 1, wherein the inner periphery of the insertion hole in the tube sheet is shaped like a bell mouth.