JPH042840B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION TECHNICAL FIELD The present invention relates to a ceramic tube connection structure that is applied to, for example, dust collectors and heat exchangers.

"Prior art and its problems" In recent years, in order to improve the efficiency of heat exchangers and dust collectors, devices that use ceramic pipes to process high-temperature gas have been developed. is accompanied by various technical difficulties. That is, when compared with metal materials, ceramic tubes are brittle and break easily, and are weak in mechanical strength and thermal shock, so long tubes cannot be used. Further, when a ceramic tube and a metal member are assembled, expansion and contraction occurs due to the difference in thermal expansion, and excessive stress is generated in the ceramic tube, often resulting in breakage. Further, when connecting the ceramic pipe and the metal member, ordinary connection means such as welding or bolting cannot be used.

For example, in the case of dust collectors, the distance between the tube sheets is often about 2 m, and if you try to connect them with a single ceramic tube, it will not only be difficult to form the ceramic tube, but it will also be difficult to form the ceramic tube. It is also easy to become unreasonable. Therefore, it is necessary to use a plurality of ceramic tubes connected in the longitudinal direction.

As a connection structure for ceramic pipes, for example, the sixth
As shown in the figure, a structure is known in which the open ends of ceramic tubes 1 and 2 are aligned with each other and bonded together with an inorganic adhesive 3 or the like interposed therebetween. However, in this connection structure, the adhesive force of the adhesive 3 is not sufficient and it is extremely difficult to bond airtightly, so the strength against bending stress etc. is insufficient, and sufficient sealing performance cannot be obtained. Ta.

Therefore, as shown in FIG. 7, a ceramic annular holder 4 is attached to the outer periphery of the connection between the ceramic tubes 1 and 2, and an adhesive 3 is filled in the gap between the ceramic tubes 1 and 2 and the annular holder 4. Fixed structures have also been proposed. However, with this structure, the adhesive strength tends to vary due to differences in the adhesive skill level of each individual, and it is difficult to obtain a predetermined strength and sealing performance. Further, since no means for absorbing the difference in thermal expansion between the ceramic tubes 1 and 2 and the metal annular holder 4 is provided, the structure is also vulnerable to thermal shock. For this reason, the connecting portions were often the cause of damage.

OBJECT OF THE INVENTION An object of the present invention is to provide a ceramic tube connection structure which solves the above-mentioned problems and which has a relatively simple structure and provides sufficient strength and sealing performance.

"Summary of the Invention" The joining structure of ceramic tubes according to the present invention is such that the open ends of two ceramic tubes to be connected are arranged opposite each other, and a heat-expandable material, a ceramic fiber, and an organic bonding material are placed on the outer periphery of this connection. An annular holder is attached via a heat-expandable mat formed by bonding the ceramic pipes together, and the heat-expandable mat is expanded to grip the connecting portion of the ceramic tube.

In the present invention, "heat-expandable mat" means
It is made by bonding a heat-expandable material and a ceramic fiber with an organic binder to form a pine-like shape.
It means something that has the property of expanding up to 3 times as much and then maintaining the expanded state even if the temperature is repeatedly raised and lowered. In this case, as the heat-expanding material, for example, vermiculite, pearlite, etc. are used, and as the ceramic fiber, for example, a fibrous inorganic material containing alumina or silica as a main component is used. Incidentally, silica cloth or the like may be used as the ceramic fiber, and in that case, a structure in which a heat-expandable material is sandwiched between the silica cloth may be used. Specific examples of such heat-expandable mats include "Interum Mat" (trade name, manufactured by Sumitomo 3M Ltd.).

The present invention utilizes the characteristics of such a heat-expandable mat. That is, a ring-shaped holder is attached to the outer periphery of the connection part of the ceramic tube with the heat-expandable mat interposed therebetween, and the temperature at which the heat-expandable mat expands is set at 400° C. or higher, so that the heat-expandable mat It can be expanded to grip the ceramic tube firmly. As mentioned above, once the heat-expandable mat expands above a certain temperature, it maintains its expanded state even when the temperature drops to about room temperature, so that sufficient gripping force can be obtained and good sealing performance can be achieved. Furthermore, since the heat-expandable mat has a certain degree of elasticity, it can also absorb the difference in thermal expansion that occurs between the annular holder and the ceramic tube.

Embodiment of the Invention FIG. 1 shows an embodiment of the direct structure of the present invention.

That is, the open ends of the ceramic tubes 11 and 12 are aligned and placed close to each other, and the annular holder 14 is attached to the outer periphery of the connecting portion via the heat-expandable mat 13, spanning both the ceramic tubes 11 and 12. . The heat-expandable mat 1 is then heat-treated by heat-treating the connection portion to, for example, 400°C or higher.
3 is inflated and the annular holder 14 grips the ceramic tubes 11 and 12.

According to this connection structure, the heat-expandable mat 13
Due to the thermal expansion, the outer periphery of the connecting portion of the ceramic tubes 11 and 12 is firmly gripped, and sufficient connection strength and sealing performance are obtained. Heat-expandable mat 13
Since it has a certain degree of elasticity, it can absorb the relative displacement in the axial or radial direction of the ceramic tubes 11 and 12 caused by the difference in thermal expansion, and its strength against thermal shock is also improved.

In addition, in this embodiment, the ceramic tubes 11, 1
Although both ends of the ceramic tubes 11 and 12 are placed close to each other with a predetermined gap in between, the ends of the ceramic tubes 11 and 12 may be brought into contact with each other without a gap. In addition, ceramic tube 1
Either one of 1 and 12 may be closed at the other end located on the opposite side of the connecting portion. Further, the annular holder 14 may be made of ceramic or metal, but is preferably made of ceramic when the processing gas contains corrosive components or is at high temperature.

Next, the results of actually measuring the connection strength in the above example will be described. As the heat-expandable mat 13, "Interum Mat" (trade name, manufactured by Sumitomo 3M Co., Ltd.) was used. This heat-expandable mat is made of vermiculite, ceramic fiber, and an organic binder, and expands when kept at a temperature of 400°C or higher. Also,
To hold the ceramic tube, first compress the heat-expandable mat 2, which has an initial thickness of 4.9 mm, to a thickness of 3.5 mm.
Connect this to the ceramic tubes 11 and 12 and the annular holder 1.
The test was performed by filling the gap (3.5 mm) with No. 4 and holding this area at 550° C. for 1 hour. The outer diameter of the ceramic tubes 11 and 12 is 165 mm, the inner diameter of the annular holder 14 is 172 mm, and the axial length is 65 mm. The connection thus obtained has pull-out strength at room temperature.
It exhibited a sufficient gripping force of 100 kg or more, and the dust leakage rate was 0.02% or less for dust particles with a particle size of 0.3 μm or more, showing good and sufficient sealing performance. Furthermore, these performances can be expected to be equivalent or better even in a temperature range of about 500°C.

FIG. 2 shows another embodiment of the connection structure of the present invention.

In this embodiment, an annular groove 14a is formed on the inner periphery of the annular holder 14. and,
When the heat-expandable mat 13 expands, this groove 1
4a to provide stronger gripping force.

In the above embodiment, other unevenness forming means may be provided, such as providing an annular rib instead of the annular groove 14a. These irregularities may be formed on the outer circumference of the connecting ends of the ceramic tubes 11 and 12, or on both the inner circumference of the annular holder 14 and the outer circumference of the connecting ends of the ceramic tubes 11 and 12. good.

FIG. 3 shows still another embodiment of the connection structure of the present invention.

In this embodiment, a flange 14b is formed on the outer periphery of the intermediate portion of the annular holder 14, and this flange 14b engages with the tube sheet 15 and is connected to the tube sheet 15 by means such as bolt tightening. There is. This embodiment is applied when the ceramic tubes 11 and 12 are to be connected at the tube plate 15.

FIG. 4 shows another embodiment in which the connection structure shown in FIG. 3 is modified.

That is, in this embodiment, the annular holder 14
A flange 14b is formed on the outer periphery of the upper end. This flange 14b is adapted to engage with the tube plate 15.

FIG. 5 shows still another embodiment of the connection structure of the present invention.

That is, in this embodiment, the annular holder 14
A tapered wall 14 whose outer periphery is tapered downward.
c, and this tapered wall 14c is the tube plate 15.
It is designed to engage with the insertion hole 15a of. In this case, it is preferable that the insertion hole 15a of the tube plate 15a has an inner peripheral shape to which the tapered wall 14c fits. This embodiment is also applied when the ceramic tubes 11 and 12 are to be connected at the tube plate 15.

"Effects of the Invention" As explained above, according to the present invention, an annular holder is attached to the outer periphery of the connection part of the ceramic pipe via a heat-expandable mat, and the heat-expandable mat is thermally expanded to connect the ceramic pipe. Since the parts are gripped, sufficient connection strength and sealing performance can be obtained with a relatively simple structure. Further, since the heat-expandable mat has a certain degree of elasticity, it can absorb relative displacement in the axial or radial direction due to the difference in thermal expansion, and its strength against thermal shock is improved.

[Brief explanation of drawings]

1, 2, 3, 4 and 5 are sectional views showing different embodiments of the connection structure of the present invention, and FIGS. 6 and 7 are sectional views showing different examples of the conventional connection structure. It is a sectional view showing an example. In the figure, 11 and 12 are ceramic tubes, 13 is a heat-expandable mat, 14 is an annular holder, 14a is an annular groove, 14b is a flange, 14c is a tapered wall,
15 is a tube plate, and 15a is an insertion hole.

Claims (1)

[Scope of Claims] 1. A heat-expandable device in which the open ends of two ceramic tubes to be connected are arranged opposite each other, and a heat-expandable material and a ceramic fiber are bonded to the outer periphery of the connection portion using an organic bonding material. 1. A connection structure for ceramic tubes, characterized in that an annular holder is attached through a mat, and the heat-expandable mat is expanded to grip the connection part of the ceramic tube. 2. The ceramic tube connection structure according to claim 1, wherein a flange connected to a tube plate is formed on the outer periphery of the annular holder. 3. The ceramic tube connection structure according to claim 1, wherein a tapered wall portion that engages with the insertion hole of the tube plate is formed on the outer periphery of the annular holder. 4. A connection structure for ceramic tubes according to any one of claims 1 to 3, wherein irregularities are formed on the inner periphery of the annular holder and/or the outer periphery of the joint portion of the ceramic tubes. 5. A ceramic tube connection structure according to any one of claims 1 to 4, wherein the ceramic tube is a porous filter tube.