JPH02212679A - Gas leakage seal - Google Patents

Abstract

PURPOSE: To enhance a sealing property between engaging flanges by embedding a compressible seal member in a groove formed in one of the flanges abutting against each other, and by forming a crosswise gas channel. CONSTITUTION: A groove 19 is extended along a flange 12, in the direction crossing the direction of gas leakage along the interface 15 from an inner zone 17 to the surroundings 18. Further, a gasket structure 20 includes a bottom strip 21 and a pair of vertical side wall strips 22, 23 which serve as side walls of a rectangular cross-sectional space in which a compressible gasket 24 is fitted. High pressure gas from a casing inner zone 17 flows along the interface 15 between flanges 11, 12 and reaches the gasket structure 20, and then it flows into a crosswise channel 26 in which lower pressure gas is present, and is then finally led into a low pressure zone in an associated device. Meanwhile, a gasket 24 prevents extra gas from further advancing even along the interface 15.

Description

DETAILED DESCRIPTION OF THE INVENTION This invention relates to an improved gas seal, and more particularly to a dual gas seal structure and apparatus for containing and utilizing gas leakage between two opposing flanges of a pressure vessel structure.

BACKGROUND OF THE INVENTION In some pressure vessel applications, gaskets or seals are used in conjunction with flange connections to prevent gases, such as air, from escaping through the flange joint. For various technical reasons, flanged joints may be used that do not completely seal air leaks, but allow some amount of air to leak, especially if the amount of air that escapes is partially used. This is true if it does not adversely affect the entire device being used.

High-temperature gas turbine generators typically use an air compressor with a cylindrical casing surrounding a cylindrical bladed rotor. Air at atmospheric pressure is introduced into the compressor through one open end of the cylinder and compressed by a rotating breviation of the rotor that interengages blades within the casing. High pressure air is removed from the opposite end of the casing and directed to the combustion and exhaust region of the gas turbine unit, which operates at lower pressures.

The compressor casing and the intermediate parts of the casing between the compressor and the combustion device are usually multi-part structures with the components suitably bolted together via suitable flanges. Unfortunately, it has been found that the flanges of multi-part assemblies allow excessive air leakage through the normally flat metal-to-metal mating surfaces of both flanges, for example due to thermal deformation of the flanges. Air leakage problems are exacerbated when the casing structure has curved or angular sections. If the casing has curved sections or sections that meet each other at an angle, and therefore the flange is also bent at such an angle, a flange with an otherwise desirable machined surface may not provide the desired air-sealing properties. Difficult to maintain. For example, flanges can be used to provide seals to horizontal and vertical surfaces, and to do so
Two right-angled flanges may also be used. Using a gasket seal between two flanges is the best way to seal the flanges.

Not only is this a hindrance to the desired metal-to-metal contact, but it is also a problem when using gasket seals only where most air leakage occurs, and thus an hindrance to the overall extended contact of the flange surfaces.

OBJECTS OF THE INVENTION It is an object of the present invention to provide an improved sealing device that seals between engaging flanges associated with a high-temperature gas turbine engine without interfering with the close contact of the machined surfaces that the flanges abut.

Another object of the present invention is to provide an improved gas seal device that seals between both flanges by embedding a compressible seal structure in a gas guide groove provided in one of the abutting flanges of a gas turbine casing. It is in.

Another object of the invention is to embed a compressible seal in a groove provided in one of the abutting flanges of a gas turbine compressor casing, and to reduce the air pressure inside the gas turbine by embedding a compressible seal in a groove provided in one of the abutting flanges of the gas turbine compressor casing. An object of the present invention is to provide an improved gas sealing device for sealing a flange surface by providing a transverse air channel for reuse at a lower location.

SUMMARY OF THE INVENTION According to the present invention, a shallow groove is provided in one of a pair of opposing machined flange surfaces of an air containment casing structure of a high-temperature gas turbine generator. A compressible seal placed on one side within this groove is adapted to be compressed appropriately, but not excessively, when the flange surfaces meet in metal-to-metal contact relationship.

A compressed resilient seal is retained on one side of the groove and defines a narrow open air channel on the other side of the groove. Air escaping between the abutting surfaces of the flange is captured in an open channel;
It is transported to the low-pressure area of the gas turbine and used there effectively. The compressible sill prevents leakage air from escaping between the abutment flanges as unwanted and potentially dangerous hot air jets.

BRIEF DESCRIPTION OF THE DRAWINGS In order that the invention may be better understood, the invention will now be described in conjunction with the accompanying drawings.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows a sectional view of the flange seal structure of the present invention. This flange seal assembly 10 consists of an upper flange 11 and a lower flange 12 opposite thereto.
The first part flange 11 and the bottom flange 12 have smooth surfaces 13 and 14, respectively, and a metal-to-metal contact 15 is established by a flange port 16 that passes through the second part flange 11 and threadably engages the bottom flange 12. is held in Typically, the -1 part flange 11 is associated with the casing -1 second part and the lower flange 12 is associated with the opposite lower casing half, for example in conjunction with a horizontally divided casing half of an axial compressor. There is.

A row of poles 1-16 (only one shown) located along the flange holds the joined casing halves in structural relationship to form part of an axial compressor or turbine casing structure. In a conventional manner, a row of bolts 16 are spaced apart along the two-part flange 11 and fully threaded into the lower flange 12, connecting their smooth or machined surfaces 13 and 14 to the metal. - Abuts at the metal contact interface 15. This intimate arrangement is typically sufficient to prevent excessive air leakage from within the structure, specifically air leakage from the interior of the structure 17 transversely along the interface 15 into the environment 18. be.

A flange, such as flange (10) in FIG. 1, may be of long length and may have curves, turns, corners, etc. along it. We have found that flanges with sharp turns or curves can cause air leakage, especially at such turns or curves, but that straight, straight sections provide an adequate seal. If a flat gasket is used only at the leakage location between the flanges, the wedging effect of the gasket will prevent the machined surfaces 13 and 14 from forming a continuous, cohesive interface 15. And when the casing houses close-fitting working components or moving mechanisms, it is difficult to maintain proper clearance between such mechanisms and the casing.

The seal structure of the present invention forms an effective continuous seal between flanges that have curved portions or abrupt changes in direction. Referring again to Figure 1, one of the opposing flanges,
For example, the flange 12 has a groove 19 with a rectangular cross section.
This groove 19 extends along the entire length of the flange at bends, corners and other turns. Groove 19 extends along flange 12 in a direction transverse to the normal leakage direction of air leaking from interior region 17 to environment 18 along interface 15 . Gasket structure 20 matching the shape of groove 19
is fitted into the groove 19. Details of this gasket structure 20 are shown in FIG.

In FIG. 2, gasket structure 20 includes a bottom strip 21 and a pair of spaced upright sidewall strips 22 and 23. In FIG. These strips 21 , 22 and 23 are preferably thin flexible metal strips, such as stainless steel or hard bronze, each of an elongated rectangular profile that mates smoothly with the elongated rectangular walls of the groove 19 . Spaced apart strips 22 and 23 are arranged in rectangular groove 19 such that the longitudinal side edges of the strips rest on bottom strip 21 . strips 22 and 2
3 is joined to the bottom strip 21, for example by welding or brazing, to form an integral structure. The total height of this monolithic structure is equal to or slightly less than the depth of the groove 19. The spaced apart strips 22 and 23 form the side walls of a space of rectangular cross section into which a compressible flexible sealing strip or gasket 24 of rectangular cross section fits. The total height of the gasket 24 is greater than the sidewall strip 22.
and 23, which is larger than the depth of the groove 19 to the bottom wall 21 by a value approximately equal to its degree of compression.

The degree of compression of the gasket usually needs to be sufficient in the gasket structure, but it must not be excessively compressed. for example,
If the gasket 24 of FIG. 2 is capable of compressing its height dimension by a fixed amount before the material becomes completely solid and non-porous, the gasket 24 will be able to compress its height from the working surface 14 to its degree of compression or range of compression 25. The dimensions can be made such that the relationship in FIG. 1 and FIG.

Because the gasket structure 20 consists of a thin flexible metal strip surrounding the flexible gasket 24, this monolithic structure is extremely flexible and easily follows or becomes able to follow turns in the groove 19. It can be formed in advance. The depth of groove 19 for purposes of sizing gasket 24 is the distance from interface 15 to bottom strip 21 in FIG. In the sealed condition, when flanges 11 and 12 abut at the working surface intimate interface 15 of FIG. 1, gasket 24 is fully compressed, and when fully compressed, the material of gasket 24 becomes non-porous Machining surface 1
3 in a tight sealing relationship. The sidewall strip 22 becomes a partition within the groove 19, and the remaining width of the groove 19 is connected to the sidewall 2.
2 and as an air channel 26 extending coextensive with the gasket 24. groove 19 and channel 2
6 is of a predetermined size depending on the equipment in which it is applied, for example a high-temperature gas turbine engine, and the channel 26 ultimately leads to and enters an area of pressure much lower than the air leakage pressure.

High-temperature gas turbine systems typically require extra air to cool components that operate at extremely high temperatures. According to the invention, therefore, the channels 26 capture the air hitherto lost due to leakage and direct it to appropriate ducts leading to these low pressure areas, providing an effective reuse of the air. be able to. For example, in a high-temperature gas turbine, channels 26 lead to a manifold from which air is supplied to various applications within the gas turbine system or external to the system.

After utilization within the device, this air can be injected into the combustion device or hot gas stream of the device.

In operation of the sealing device of FIG.
2 along the interface 15 to the seal structure 20 of the present invention. At this point, dual air leakage control is provided. The first part of the dual control includes a transverse channel 26 in which a low pressure air condition exists. The high pressure air enters the low pressure channel 26 from the interface 15 and enters the channel 26
According to the low pressure state within, it is finally guided to the low pressure area of the associated equipment. While the channels 26 are fully responsible for conveying the high pressure air to the low pressure area, any excess air that attempts to travel further along the interface 15 is routed through the gasket 24.
Further progress is blocked by the second part of the dual air control consisting of:

The gasket 24 is compressed between the flanges 11 and 12 and its interior (when uncompressed, excess air or channel 26
This is because they are blocking the pores and passages that allow them to pass through.

As mentioned above, the seal structure of the present invention is a seal structure that combines air bleed and gasket seal. Compressible gasket 24 can be selected from a variety of well-known compressible gasket or seal materials, such as rubber materials, fibrous materials, and thin metal mesh plaids or rovings. Alternatively, a metal structure as shown in FIG. 3 could be used.

The Jevlon-shaped seal structure 27 shown in FIG. 3 is similar to the seal structure 20 shown in FIGS. 28, including sidewall strips 29 and 30. In the space between the sidewall strips 29 and 30, a plurality of thin-walled angled strips 31 rest with their longitudinal side edges on the bottom wall strip 28 and extend laterally. They are arranged parallel to each other and spaced apart. Each strip 31 is slightly folded or bent along its longitudinal axis, so that the third
In cross-section as shown, the grid structure defines a Gevron-shaped structure, with each chevron-shaped strip (or Gevron) 31
is in a spaced-apart relationship with the adjacent strip 31. Each Gevron strip 31 is a resilient or spring member that engages the surface of the opposing flange 11 to provide a continuous biasing action along a plurality of extremely narrow areas or side edges, creating an effective series of transverse air seals. Demonstrate in relationships. The height of the Jevron strip 31 is
greater than the gasket depth of the groove 19 as defined above;
It projects from the surface 14 by a distance corresponding to its compression range 25 (FIGS. 2 and 3). As the flange 11 engages the chevron strip 31, the strip 31 flexes in its chevron region and reduces its height. flanges 11 and 12
When fully engaged, each strip 31 retains a high degree of elasticity or spring action and snugly engages the flange surface 13. If the compression range 25 is excessive, the chevron strip 31 will exceed its elastic limit and become permanently deformed or fixed, such that the thin-walled strip 31 will have a tight press against the flange 11 when the flanges are fully engaged. There isn't enough elasticity left to hit it. Additional strips or layers 33 of rubber or fiber material can be sandwiched between or interleaved with the strips 31 to increase elasticity and reduce deformation.

Furthermore, the thin-walled strip 31 is sufficiently spaced from the sidewall strip 30 so that, in its bending range, the thin-walled strip 31
1 does not prematurely contact the sidewall 30 or become permanently deformed before the air seal becomes effective. The free side edge of the thin-walled strip 31 that engages the smooth surface of the opposing flange 11 is connected to the opposing flange surface 13.
defines a generally planar surface 32 that contacts in planar abutting relationship.

Since the thin-walled strip 31 has a structure that remains elastic, the thin-walled strip 31 continues to press tightly against the opposing flange 11 when the flanges 11 and 12 are fully engaged. compression range or distance 25 is excessively large;
Gasket material 24 or flange surfaces 13 and 14 in FIG.
It is important to ensure that it does not protrude between the metals and interfere with smooth metal-to-metal contact. Similarly, thin-walled strip 31 of FIG. 3 must not be permanently deformed between flanges 11 and 12. Side walls 22 and 2 in FIGS. 1 and 2
3 is a gasket 2 so that the material itself absorbs the compression.
The thin wall 3 is essentially completely contained, and the thin wall 3 is brazed to the bottom wall 28 and side wall 30 to provide structural integrity that exhibits controlled compressive flexing. "Compression range" is defined variously for different seal materials, but is interrelated, and for compressible rubber gasket members, compression that deforms the material and occludes a significant amount of porosity within the material. This is the decrease in height of a gasket surrounded on three sides as shown in Figure 2 when a force is applied. For the Gevlon seal of FIG. 3, the compression range is such that it increases the sealing force of the Gevlon strip against the flanges without permanently deforming the Gevlon strip, but remains elastic when the flanges abut each other. The movement of the upper flange towards the Jevlon-shaped strip relates to the extent to which the height of the Jevlon-shaped strip can be reduced, ie it can be bent further. A layer 33 of rubber or fibrous material is located between each Gevlon layer. According to a feature of the invention, the opposing flanges abut in a metal-to-metal engagement relationship, causing the seal member to be compressed within its compression range, such that further compression of the flange engagement will cause the seal member to be compressed no further. to avoid being Gasket 24 projects a suitable distance from the flange surfaces to define a space or distance 25 in FIGS. 2 and 3 so that when flange surfaces 13 and 14 abut in mating relationship as shown in FIG. The gasket or seal system is compressed to its most effective amount and cannot be compressed any further as further compression would lead to failure of the seal.

Although this invention has been described with reference to its preferred embodiments, it will be apparent to those skilled in the art that various modifications and changes can be made without departing from the spirit of the invention.

[Brief explanation of the drawing]

Fig. 1 is a sectional view of the flange seal structure of the present invention, Fig. 2 is an enlarged sectional view of the gasket seal structure of Fig. 1, and Fig. 3 is a cross section similar to Fig. 2 showing a modification of the seal structure. It is a diagram. Explanation of main symbols 10... Flange seal assembly, 11. 12... Flange, 1314... Machining surface, 15... Close contact interface, 16... Bolt, 17...
Inside, 18...Environment, 19...Groove,
20...gasket structure, 21,. 28・
...Bottom strip, 22.23, 29.30...Side wall strip, 24
...Gasket, 25...Compression range, 26...
Space, 31... Yamagata Street Tsubu, 32
...Surface, 33...Rubber or fiber material layer.

Claims (1)

[Claims] 1. A casing structure consisting of a plurality of parts, wherein one region of the casing structure contains gas at high pressure, another region contains gas at low pressure, and one of the plurality of parts contains gas at low pressure. A smooth surface metal flange included therein engages a similar flange on another portion in metal-to-metal gas sealing contact to prevent gas from passing between the flanges and out of the casing structure. In a double gas leakage control and sealing device for use in a casing structure, one of the dual control devices comprises a groove provided in one of the flanges, the groove extending coextensive with the length of the flange; and transverse to the direction of gas leakage between the flanges, a sealing structure is disposed within the groove to define a gas channel coextensive with the flanges, the gas channel leading to an area of low gas pressure; As a result, the high-pressure leaking gas from inside the casing structure is captured midway in the groove and transported to a low-pressure area within the casing structure for effective use. a compressible seal member disposed in the seal structure, the compressible seal member being compressed within the groove by the flange within its compression range when the flanges abut against each other in a metal-to-metal contact relationship; The double gas leakage control and sealing device is characterized in that excess leakage gas in the groove is prevented from passing through the sealing member and exiting between the flanges. 2. Said sealing structure comprises: (a) a thin narrow rectangular bottom wall strip located at the bottom of said groove and extending coextensive with said groove; (b) within said groove, on one side thereof, upright and parallel to each other; a pair of thin narrow rectangular sidewall strips disposed in spaced relation, one sidewall strip being continuous with the sidewalls of the groove; (c) the other sidewall strip being continuous with the sidewalls of the groove; defining a gas channel, the gas channel extending transversely to the direction of gas leakage between the flanges; 2. The apparatus of claim 1, wherein the seal member is compressed within a compression range when the flanges abut in metal-to-metal contact. 3. The apparatus of claim 2, wherein the seal structure is a combination of metal strips bonded together to form a long, unitary, highly flexible integrated structure. 4. The apparatus of claim 2, wherein the compressible material is a non-metallic sealing gasket. 5. The apparatus of claim 2, wherein said compressible material is metal. 6. The apparatus of claim 2, wherein said seal member comprises a fine metal mesh material. 7. The apparatus of claim 2, wherein said sealing member is a Gevron-shaped seal. 8. The apparatus of claim 2, wherein the seal member projects outwardly from the groove a distance approximately equal to its compression range before the flanges abut in metal-to-metal contact. 9. The apparatus of claim 2, wherein said bottom wall strip and side wall strip are made of stainless steel. 10. The apparatus of claim 3, wherein said metal bonded combination is a bronze bonded combination. 11. In sealing the high-pressure section of a gas turbine casing provided with a pair of flanges having machined surfaces that abut each other, the leaking gas is made available to the low-pressure section of the turbine and the leaking gas is removed from the casing. In a double sealing method effective to prevent escape into the surrounding atmosphere, a seal is provided between the flanges along a passage extending longitudinally and transversely to the natural direction of gas leakage, provided that the seal is The above flange surfaces are allowed to come into contact with each other in a flange-flange contact relationship, and gas leaking between the abutted flanges is captured on the way before it reaches the seal, and this captured gas is used in the low pressure part of the turbine. A double sealing method that includes a step of transporting it to its low-pressure part. 12. The method according to claim 11, wherein the intermediate capturing step and the conveying step are performed through a groove formed in the abutment surface of at least one of the flanges. 13. The method of claim 11, wherein the step of forming a seal includes embedding a sealing gasket in the abutment surface of at least one of the flanges.