JPH0824541A - Sealing structure of ceramic pipe - Google Patents

Abstract

PURPOSE:To secure sealing property and reduce the risk of damage due to thermal stress by placing a metallic pipe having about the same diameter as that of a ceramic pipe coaxially on the ceramic pipe with a packing material and engaging slidably a metallic ring fixed on a plate with the metallic pipe through a ceramic fiber material. CONSTITUTION:The ceramic pipe 1 is placed on a lower tube plate 2 without binding, the metallic pipe 3 coaxial with the ceramic pipe 1 is placed on the ceramic pipe 1 and is connected to a sealing part 5 fixed to a tube plate 4. The metallic pipe 3 on the ceramic pipe l is placed only with a sheet packing 3b, the metallic ring 5a fixed to the tube plate 4 is arranged around the metallic pipe 3 and the space between the metallic ring 5a and the metallic pipe 3 is sealed with the ceramic fiber material 5b, 5c. In this way, the sealing property is secured without binding the ceramic pipe.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a ceramic tube seal structure applied to a ceramic filter device or the like.

[0002]

2. Description of the Related Art In recent years, a system for operating a gas turbine by the combustion gas of a pressurized fluidized bed boiler using coal as a fuel has been developed, and a filter device functioning at a high temperature for dedusting the combustion gas is developed. Is needed. Since the temperature of this combustion gas is 850 ° C. or higher, conventional filter devices such as bag filters cannot be used. Therefore, although the ceramic filter device is being developed, the most serious problem in the ceramic filter device is damage to the ceramic tube forming the filter element due to thermal stress. Unlike conventional metal tubes and bag filter materials, ceramic tubes are inflexible and do not stretch, so they break immediately when the critical stress is exceeded. A particular problem with ceramics tubes is the joints with metals with different coefficients of thermal expansion, and when this ceramics tube is long, the amount of elongation due to the difference in thermal expansion that should be absorbed by the sealing part of the ceramics tube is several tens of millimeters. Also reaches. The most common structure for absorbing such a large difference in thermal expansion is the sand seal structure used in the heat treatment furnace. This sand seal structure aims at an energy saving effect by improving the sealing property in the furnace, and many inventions have been filed besides the patent No. 1752997. Further, in Japanese Examined Patent Publication No. 1-44954, as a sealing method for a ceramic heat transfer tube in a ceramic heat exchanger having a structure substantially similar to that of a ceramic filter device, the ceramic tube is penetrated through a metal tube plate and a metal ring is arranged around it. A method of sand-sealing the gap is used.

[0003]

However, these ceramic tube sealing structures cannot be applied to a ceramic filter device. In the case of a ceramics filter device, a large number of elongated filter elements are installed on a large metal tube plate. The biggest problem is that the ceramic tube is directly bound to the tube sheet through the sand seal. The metal tube sheet already has a distortion at the time of manufacturing, and even if the manufacturing is perfect and there is no distortion at all, a large deformation occurs due to the temperature difference of the tube sheet itself when the pressurized fluidized bed boiler is started. . Also, even during normal operation, backwashing is regularly performed to remove dust adhering to the surface of the filter element.
Deformation of mm occurs. Due to these deformations of the tube sheet, a large stress is generated in the filter element inserted through the tube sheet and easily damaged. To avoid this damage, it is effective to loosen the powder seal and reduce the load due to thermal stress, but as described in Japanese Patent Publication No. 1-44954, the powder scatters and seals. Sex decreases. In particular, since backwashing is performed in the ceramic filter device, the powder is instantly scattered.

In order to solve this, Japanese Patent Application No. 5-156913 uses a method of indirectly sealing a ceramics tube through a metal tube. This method is a method in which a metal ring is placed around the metal tube and the space is sand-sealed. In this method, the ceramics pipe is indirectly restrained, not directly restrained, so that the ceramics pipe is not stressed and is not damaged. However, this method causes various problems because the sand seal is used. First,
It is difficult to uniformly seal a large number of filter elements. That is, since the powder is packed in a narrow space, the sealing property changes depending on the leakage during the filling operation and the degree of the filling. Next, vibration of the ceramics filter device becomes a problem. In other words, what holds the powder down is only the powder holding rings that are placed above and below the powder, and the powder is compressed by the vibration caused by backwashing during operation and the holding force changes, so that the ceramic tube does not break. However, since the metal pipe is restrained, the sealing property between the metal pipe and the ceramics pipe is deteriorated, and the sealing property against the most important dust is deteriorated.

[0005]

A ceramic pipe sealing structure according to the present invention is intended to solve the above problems.
In a ceramic tube sealing structure for sealing between a ceramic tube placed with its central axis oriented in the vertical direction and a plate provided above the ceramic tube with its surface oriented in the vertical direction, a packing is provided on the ceramic tube. Characterized by a metal tube coaxially mounted via a material and a metal ring fixed to the plate and slidably fitted to the metal tube via a ceramic fiber material And

Further, the ceramic pipe sealing structure according to the present invention is provided between a ceramic pipe placed with its central axis oriented in the vertical direction and a plate provided above the ceramic pipe with its surface oriented in the vertical direction. In a sealing structure of a ceramics tube for sealing, a metal tube coaxially mounted on the ceramics tube via a packing material and a ceramics fixed to the plate and impregnated with powder And a metal ring slidably fitted to the metal pipe via a fiber material.

[0007]

That is, in the ceramic pipe sealing structure according to the present invention, the space between the ceramic pipe placed with its central axis oriented in the up-down direction and the plate provided above the ceramic pipe with its surface oriented in the up-down direction. In the sealing structure of the ceramic tube for sealing the metal tube, a metal tube having substantially the same diameter is coaxially placed on the ceramic tube via a packing material, and a metal ring fixed to the plate is slid on the metal tube via the ceramic fiber material. The ceramic tube is movably fitted, and the load of the metal tube placed on the upper part of the ceramic tube is only received downward through the packing material.The ceramic tube is not joined to the metal tube and is completely separated from the plate. ing. Therefore, even if an unexpectedly high stress such as an earthquake occurs in the plate, the discontinuous metal pipe and ceramic pipe act as a safety valve, and the sealing property between them both deteriorates and causes dust leakage. The stress generated in the plate is not directly applied to the ceramic tube. Also,
The sealing property between the metal ring attached to the plate and the metal tube placed on the upper part of the ceramic tube can be also ensured by filling the ceramic fiber material. With these, the sealing property can be secured without restraining the ceramic tube.

Further, in the ceramic pipe sealing structure according to the present invention, between the ceramic pipe placed with its central axis oriented in the vertical direction and the plate provided above the ceramic pipe with its surface oriented in the vertical direction. In the ceramic tube sealing structure for sealing the metal tube, a metal tube of approximately the same diameter is placed coaxially on the ceramic tube via a packing material, and the metal tube fixed to the plate is impregnated with the powder by impregnating the metal tube with the powder. The ceramic pipe is slidably fitted through it, and the ceramic pipe is joined to the metal pipe only by receiving the load of the metal pipe placed on top of it downward through the packing material. Not completely separated from the board. Therefore, even if an unexpectedly high stress such as an earthquake occurs in the plate, the discontinuous metal pipe and ceramic pipe act as a safety valve, and the sealing property between them both deteriorates and causes dust leakage. The stress generated in the plate is not directly applied to the ceramic tube. Also, the sealing property between the metal ring attached to the plate and the metal pipe placed on top of the ceramic pipe is filled with the ceramic fiber material that has been impregnated with the powder to ensure uniform sealing performance. can do. With these, the sealing property can be secured without restraining the ceramic tube.

[0009]

1 and 2 are explanatory views of a ceramics filter device according to an embodiment of the present invention. In the figure,
The ceramics filter device according to the present embodiment is used for dedusting combustion gas in a pressurized fluidized bed boiler, and the ceramics tube 1 forming the filter element of the present ceramics filter device is not restricted by the lower tube plate 2. It is located in A metal tube 3 larger than the ceramic tube 1 is placed on the ceramic tube 1, and the metal tube 3 is connected to a seal portion 5 fixed to a tube plate 4. Ceramic tube 1
The upper metal tube 3a is placed only through the sheet packing 3b. A metal ring 5a fixed to the tube plate 4 is arranged around the metal tube 3a. In the gap between the metal ring 5a and the metal tube 3a, the ceramic fiber materials 5b and 5c are formed.
Is filled with the seal material. The material of the ceramic fiber materials 5b and 5c is not particularly limited, but it is desirable to dispose the long fiber ceramic fiber material 5b with high strength on both sides and the short fiber ceramic fiber material 5c with high sealing property inside. These ceramic fiber materials 5b,
5c is molded according to the gap, and unlike a sealing method using powder, it is possible to keep a plurality of sealing portions at a uniform differential pressure.

Further, in the present apparatus, in order to keep the height of the seal portion uniform, the metal cylinder 5d is placed on the upper surface of the seal portion 5 in an unconstrained state, and the metal cylinder 5d is placed on the upper surface of the metal cylinder 5d. A metal plate 5e is fixedly installed on the tube plate 4 in order to prevent the metal plate 5e from popping out. The role of the metal tube 5d is important, and when the length of the ceramic tube 1 is 6.4 m, even if the difference in expansion with the tube sheet 4 attached to the main body container in the length direction is reduced by the slide structure. About 30 mm occurs, but without the metal cylinder 5d, the ceramic fiber materials 5b, 5c change the sealing position in association with the metal pipe 3a on the filter element and the metal ring 5a for fixing the tube plate 4 as the temperature rises and falls. Therefore, the sealing property cannot be maintained during operation or when backwashing. Although FIG. 1 shows a state in which the metal tube 5d is set at room temperature, the metal tube 5d lowers from the position shown in FIG. 1 when the temperature rises, and returns to the position shown in FIG. 1 when the temperature returns to room temperature. Due to such an action, the sealing property in the seal portion 5 is always kept uniform, and since dust-containing gas passes through the inner surface of the ceramic tube 1, dust also enters the seal portion 5. The dust is pushed out to the outside when the temperature is lowered by 5d, so that the sealing property is constantly maintained.

In order to further improve the sealing property in such a sealing structure, as shown in FIG. 2, the ceramic fiber materials 5b and 5c are preliminarily immersed in the powder slurry 6 to allow the powder to penetrate into the surface layer. Is most desirable to include. The powder slurry 6 is a slurry in which powder having good fluidity such as alumina beads is dispersed in the liquid. The amount of the powder is not particularly limited, but powder of about 30 to 70 wt% can be used as the powder slurry 6 with water as the dispersion medium. As shown in FIG. 3B, the ceramic fiber material 5c or the ceramic fiber material 5b formed in a ring shape is dipped in the powder slurry 6 and dried to easily obtain the same. As shown in FIG. 4), a fiber ring containing the permeated powder is obtained. In actual penetration, the thickness of the penetration layer can be controlled by reducing the pressure of the penetration layer of the powder slurry 6. Further, in order to maintain the shape for a long time, it can be improved by adding a paste material such as starch to the powder slurry 6. The fiber ring containing the powder can contain about 1 to 2 of the powder with respect to the fiber 1 of the raw material, whereby the sealing property is remarkably improved. Specifically, the dimensions are 170φ × 140φ × 1
The leak rate of 70 liters / min at 500 mmAq of the fiber ring made of 5 ton material is reduced to 30 liters / min when the amount of 10 μm alumina bead powder is twice the fiber weight.

As described above, in the present ceramic filter device, the sealing structure between the tube sheet 4 and the ceramic tube 1 placed below the tube sheet 4 does not penetrate the upper surface of the ceramic tube 1 and has a cross-sectional diameter substantially the same as that of the ceramic tube 1. Place the metal tube 3 and fix the metal ring 5a surrounding the metal tube 3 to the tube plate 4,
The gap between the metal tube 3 and the metal ring 5a is filled with a sealing material mainly composed of ceramic fiber materials 5b and 5c, and an unrestrained metal cylinder 5d that fits in this gap is placed on the upper surface of the seal tube 1 and the tube plate. Indirectly seal 4 and
Further, a powder is infiltrated and contained in or mixed with the ceramic fiber materials 5b and 5c.
Is not joined to the metal tube 3 only by receiving the load of the metal tube 3 placed on it in the direction of compression, and is completely separated from the tube sheet 4. Therefore, even if unexpectedly high stress occurs in the tube sheet 4 due to an earthquake or the like, the discontinuity between the discontinuous metal tube 3 and the ceramic tube 1 acts as a safety valve, and the sealing performance deteriorates. The stress generated only by causing a dust leak is not directly applied to the ceramic tube 1. Further, the seal between the metal ring 5a attached to the tube sheet 4 and the metal tube 3 placed on the upper part of the ceramic tube 1 is also replaced with the sheet packing 3b, and a ceramic fiber material molded into a predetermined shape or a predetermined shape. A uniform sealability can be obtained with good reproducibility by forming the powder into a shape of (1) and allowing the powder to be infiltrated therein, or filling with a ceramic fiber material mixed with the powder. In this way, the sealing performance can be secured without restraining the ceramic tube 1 that is large in size and needs to be elongated as a high-temperature dedusting gas filter, and has a lower strength than metal. The risk of breakage due to the most problematic thermal stress can be reduced.

[0013]

The ceramic pipe sealing structure according to the present invention is constructed as described above, and since the sealing property can be secured without restraining the ceramic pipe, the thermal stress which is the most problematic in the ceramic pipe. The risk of breakage due to is reduced.

[Brief description of drawings]

FIG. 1 (a) is a vertical cross-sectional view of a ceramics tube of a ceramics filter device according to an embodiment of the present invention, and FIG. 1 (b) is a detailed view of essential parts thereof.

FIG. 2 is an explanatory diagram of a method for manufacturing a ceramic fiber material containing the powder.

[Explanation of symbols]

 1 Ceramics Tube 2 Lower Tube Plate 3 Metal Tube 3a Metal Tube 3b Sheet Packing 4 Tube Plate 5 Sealing Part 5a Metal Ring 5b Ceramic Fiber Material 5c Ceramic Fiber Material 5d Metal Tube 5e Metal Plate 6 Powder Slurry

Claims (2)

[Claims] 1. A ceramic pipe sealing structure for sealing between a ceramic pipe placed with its central axis oriented in the vertical direction and a plate provided above the ceramic pipe with its surface oriented in the vertical direction. A metal tube of substantially the same diameter placed coaxially on the ceramic tube via a packing material, and a metal ring fixed to the plate and slidably fitted to the metal tube via the ceramic fiber material. A ceramic tube seal structure characterized by being provided. 2. The sealing structure for a ceramic tube according to claim 1, wherein the ceramic fiber material is impregnated with a powder.