JPH0569962B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field to Which the Invention Pertains] The present invention relates to a steam seal structure employed in a connecting portion of equipment that utilizes high-temperature, high-pressure steam, such as a steam turbine.

[Prior art and its problems]

Conventionally, as equipment for steam turbines that use high-temperature, high-pressure superheated steam, for example, the connection between the lid of a steam strainer installed in the main steam piping and the steam strainer casing has a wedge-shaped end surface between the two. A cylindrical space is formed, and a cylindrical gasket with a wedge shape on one end surface is inserted into the space, and the force for fixing the lid to the steam strainer casing is transmitted to the gasket. A gasket was brought into close contact with the peripheral wall of the space to prevent leakage of steam, and the gasket was a ring-shaped metal gasket having a cross-sectional shape substantially the same as the cross-section of the space.

The advantages and disadvantages of a steam strainer using a conventional metal packing will be explained below with reference to a vertical cross-sectional view. FIG. 5 is a longitudinal sectional view of the steam strainer, and FIG. 6 is an enlarged view of part B thereof. In the figure, reference numeral 10 denotes a steam strainer casing (hereinafter referred to as casing), which has a T-shaped tubular shape, the upper opening of which is the steam outlet 12, the side openings are the steam inlet 11, and the lower opening 13 will be described later. It is designed to be closed by a lid 3. Inside the strainer unit 1 is a hollow cylindrical strainer unit 1 that is fixed to a lid 3 and has both ends open.
is accommodated. Therefore, the steam flowing in from the steam inlet 11 passes through the mesh of the strainer unit 1, thereby removing foreign matter mixed in the steam, and flowing out to the steam outlet 12.

The lid 3 is formed into a disc shape with tapered parts and step parts provided on its outer peripheral surface in stages, and has a hollow cylindrical shape in which the lower end of the strainer unit 1 is fitted and held on its upper end surface. unit holding part 3
A is fixed, and a plurality of studs 8 are arranged in a circular shape on the lower end surface. Then, it is fitted and fixed into the lower opening 13 of the casing 10 in the manner described below.

That is, a ring groove 4a having a square cross section is cut into the inner circumferential wall of the lower opening 13 of the casing 10, into which a segment ring 4 formed by subdividing the ring having a square cross section into several parts can be fitted. Place the strainer unit 1 on the unit holding part 3a.
Insert the lid 3 that is fitted and fixed into the casing 10 from the lower opening 13 so that the straight unit 1 is erected in the casing 10, so that the outer circumferential surface of the lid 3 and the casing 10
A cylindrical metal packing 14 having a wedge shape on the upper end surface and a ring with a square cross section are placed in a cylindrical space having a wedge shape on the upper end surface formed between the inner peripheral wall of the ring and the inner circumferential wall of the ring. A metal presser ring 5 is inserted and held by the segment ring 4 fitted into the ring groove 4a.

Next, a flat ring has a notch 2b on its peripheral edge for fitting into the lower end surface of the casing 10.
A segment ring 4 is provided with a plurality of through holes for passing one end of a stud 8 implanted in the lid 3, and further has one half fitted into the casing 10 and the other half protruding from the inner wall surface. Move the cylindrical support ring 2a, which has an L-shaped notch on the upper end surface of its outer periphery where the protruding lower corner touches, to the same side as the notch 2b, on the same surface as the ring (in the figure). Insert the support ring 2a into the lower opening of the casing 10, place the lower corner of the segment ring 4 on the notch, and support the retainer ring 2 fixed on the stud 8 from the retainer ring 2. By screwing and tightening the nut 9 into the downward protrusion, the lid 3 is moved toward the lower end of the casing 10 by interposing the metal packing 14 and the presser ring 5 between the lid 3 and the segment ring 4. It is fixed to the segment ring 4 by pulling it. In this way, the casing 10
The lid 3 and the lid 3 are integrated, and the metal gasket 14 is applied with a tightening force to make them come into close contact with the opposing wall surface, and the pressure of the steam flowing through the lid 3 makes them come into close contact with each other, thereby preventing leakage of steam from the connection between the lid 3 and the casing 10. is now being prevented.

As explained above, when the metal packing 14 is used for steam sealing between the lid 3 and the casing 10, it has the advantage that the force applied to the wedge-shaped part is concentrated and the sealing performance is improved. (In this case, the lid 3 and the casing 10) Since there is a risk of damaging the wall surface, the wedge-shaped portion of the metal gasket is coated with a soft metal such as silver, which increases manufacturing costs. In addition, since metal gaskets are used with their tips yielded, there are problems such as fatigue over time and leakage, and high maintenance costs such as having to make new ones when reassembling them during periodic inspections. It was hot.

[Purpose of the invention]

This invention was made in view of the above points,
The purpose of the present invention is to provide an inexpensive steam seal structure that does not leak due to fatigue over time and has a sufficient sealing effect.

[Summary of the invention]

According to the present invention, the above-mentioned object is a cylindrical graphite packing whose one end face is inclined and has a wedge shape, and the periphery of the top of the wedge shape is covered with a tangled body made of thin metal wires to protect it. , a ring-shaped asbestos packing with a square cross section made by wrapping tape-shaped graphite around the outer peripheral surface of an asbestos core, and a metal holding ring with a square cross section, at the connection part between the casing and the lid. A graphite packing, an asbestos packing, and a presser ring are inserted in this order into the space defined by both of them to form a packing part, and the packing part is engraved on the inner peripheral wall surface of the casing opening. A portion of the lid is fitted into the ring groove and held, and the remaining portion is held by a segment ring that protrudes above the wall surface. By screwing a nut into the stud planted on the bottom surface of the housing, the lid is held by the segment, and the tightening force of the screwed nut acts on the packing part to create a sealing force. This is achieved by holding the

[Embodiments of the invention]

Embodiments to which the present invention is applied will be described below based on the drawings. Figure 1 is a longitudinal cross-sectional view of a steam strainer having a cylindrical steam seal with a wedge-shaped end surface, Figure 2 is an enlarged view of section A in Figure 1, Figures 3 and 4. 1 is a partial perspective view of graphite packing and asbestos packing of the present invention. Note that the same parts as in the conventional example shown in FIGS. 5 and 6 are given the same reference numerals, and explanations of the overlapping parts will be omitted.

In Figures 1 to 4, 6 is a graphite packing, which is a graphite cylindrical body compression-molded into a cylindrical body with one end surface formed into a wedge shape, as shown in Figure 3. 6a, and an intertwined body 6b made of a cloth tape-like material knitted with thin metal wires, such as stainless steel wires. , is integrally formed. As shown in FIG. 4, the asbestos packing 7 consists of an asbestos core body 7a made of asbestos molded into a ring-shaped body with a rectangular cross section, and a graphite tape 7b. It is formed by wrapping it around the outer peripheral surface of 7a diagonally in a so-called armor wrap.

The graphite packing 6 and asbestos packing 7 as described above are the strainer unit 1.
is inserted into the inside of the casing 10 and the lid 3 is fixed to the inner peripheral surface of the casing 10 via the segment ring 4 to close the lower opening 13 of the casing 10. In order to prevent leakage of steam, the retainer ring 5 forms a packing part. That is, first, the graphite packing 6 is placed in a cylindrical space located below the contact area between the lid 3 and the casing 10 and having a wedge-shaped cross section at the top and an open bottom. It is inserted so that its top fits into the wedge-shaped part of the space, then the asbestos packing 7 is inserted, and the presser ring 5 is further inserted to fill the space to form the packing part.

This is because the stress relaxation property (elasticity) of graphite at high temperatures and the steam pressure flowing through the steam strainer concentrate on the wedge part and increase the degree of adhesion between the lid 3 and the graphite packing 6. The graphite packing 6, which has characteristics such as expanding the packing horizontally to increase sealing performance, is reinforced with a tangled body 6b at its wedge-shaped top that is easily damaged, and is used at the connection between the lid 3 and the casing 10. At the same time, an asbestos packing 7 whose shape is prevented from being damaged by graphite tape is arranged in the middle part, and in addition to its own sealing power, the graphite packing 6 contacts the atmosphere and oxidizes, causing thermal loss. The presser ring 5 is inserted in the lowest layer to prevent this and to effectively apply compressive force to both the packings 6 and 7 due to their tightening.

In this way, the packing part filling the space between the lid 3 and the casing 10 is fitted into the ring groove 4a provided in the casing 10,
A portion of the lid 3 is held by a segment ring 4 protruding from the inner wall surface of the casing 10.
Multiple studs 8 planted on the lower end surface of
is passed through a bolt hole arranged in the retainer ring 2, and a nut 9 is screwed into the protrusion of the bolt hole and tightened, so that the lid 3 is pulled toward the lower end surface of the casing 10 via the retainer ring 2. By holding it in the segment ring 4, the lower opening 13 of the casing 10 is hermetically closed with the lid 3.

This tightening applies an initial tightening surface pressure to both the graphite packing 6 and the asbestos packing 7, which are inserted into the space between the lid 3 and the segment ring 4 via the retaining ring 5, and the force is reduced. The lid 3 and the casing 10 are expanded horizontally.
Let it blend in and adhere to the wall surface. Therefore, when steam is vented, steam pressure acts on the lid 3, which acts on the wedge-shaped portion of the graphite packing 6, making the sealing performance even more effective. Since the asbestos packing 7 has the property of not losing weight after the heat loss reaches a certain value, it is necessary to retighten the nut 9 after the initial ventilation and apply tightening surface pressure to both the packings 6 and 7 again. In this way, steam leakage from the steam strainer is completely prevented.

〔Effect of the invention〕

As explained above, according to the present invention, a graphite packing whose wedge top is protected by an intertwined body is placed in the cylindrical space defined at the connection between the casing and the lid, which is the insertion part of the packing for steam sealing. The asbestos packing whose external shape is protected by wrapping graphite tape and the metal retaining ring are inserted in this order to form a packing part with a three-layer structure made of different materials, and the packing part is inserted into the casing opening. It is held by the protruding part of the segment ring that is fitted into the ring groove carved in the ring groove so that a part thereof protrudes, and further via the retaining ring whose outer peripheral edge is supported by the end face of the casing opening.
By screwing a nut into the stud installed in the lid and holding the lid with a segment ring, surface pressure is maintained for steam sealing, and the properties of each material are designed to increase pressure. This allows a more perfect seal to be maintained. Therefore, compared to conventional metal packings, most of the packing parts that contact the inner wall of the casing and the outer circumferential surface of the lid are made of graphite, which is soft and does not damage the other side, and eliminates cost-increasing factors such as silver coating. At the same time, since plastic deformation does not occur at the tip of the seal, it is possible to reuse it and reduce maintenance costs, making it possible to provide an extremely economical steam seal structure.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view of a steam strainer casing according to an embodiment of the present invention, FIG. 2 is an enlarged view of part A in FIG. 1, and FIGS. 3 and 4 are graphite packing and asbestos according to the present invention. FIG. 5 is a longitudinal sectional view of a steam strainer casing using a conventional packing. FIG. 6 is an enlarged view of section B in FIG. 5. 2: Retaining ring, 3: Lid, 4: Segment ring, 5: Holding ring, 6: Graphite packing, 6b: Interlaced body, 7: Graphite packing,
7b: graphite tape, 9: bolt, 10:
Nut, 11: Steam strainer casing, 1
5: Metal packing.

Claims (1)

[Claims] 1. A wedge-shaped cylinder with one end surface inclined at the connection point for steam sealing between the casing of a device through which steam flows and the lid that closes the opening of the casing. In a type of steam seal structure in which a gasket is enclosed in a shaped space, one end surface is inclined to form a wedge shape, and the area around the top of the wedge shape is protected by covering the area with a tangled body made of thin metal wires. A cylindrical graphite packing, a ring-shaped asbestos packing with a square cross section in which tape-shaped graphite is wrapped around the outer peripheral surface of an asbestos core, and a metal holding ring with a square cross section are placed in the space. A graphite packing, an asbestos packing, and a presser ring are inserted in this order to form a packing part, and the packing part is held by partially fitting into a ring groove provided on the inner peripheral wall surface of the casing opening,
The remaining portion is held by a segment ring protruding above the wall surface, and is further attached to a stud planted in the bottom surface of the lid via a retaining ring whose outer peripheral edge is supported by the end surface of the casing opening. By screwing a nut, the lid is held by the segment ring, and the tightening force of screwing the nut acts on the packing part to maintain steam sealing force. Steam seal construction.