EP3008294A1

EP3008294A1 - Sealing arrangement for a turbomachine

Info

Publication number: EP3008294A1
Application number: EP13748277.4A
Authority: EP
Inventors: Paramdeep Singh; Ranvijay Singh; Prarthana GULATI; Gaurav Kumar; Ajit kumar MEHTO
Original assignee: Siemens AG; Siemens Corp
Current assignee: Siemens AG
Priority date: 2013-07-25
Filing date: 2013-07-25
Publication date: 2016-04-20
Also published as: CN105531444A; WO2015010740A1

Abstract

Sealing arrangement for a turbomachine and a method therefor. A sealing arrangement for a turbomachine for providing a sealing at a parting plane (6) between an upper casing (3) and a lower casing (2) of the turbomachine is presented. The sealing arrangement includes a sealing strip (10) comprising a first portion (19) and a second portion (20) forming a groove (22) therebetween, wherein the first portion (19), the second portion (20) and the groove (22) extend from a first end (17) to a second end (18) of the sealing strip (10) and wherein the sealing strip (10) is mechanically coupled to the lower casing (2) such that the second portion (20) is in con- tact with the lower casing (2), wherein the sealing strip (10) is mechanically coupled to the lower casing (2) along the groove (22).

Description

SEALING ARRANGEMENT FOR A TURBOMACHINE

The present invention relates to sealing arrangement for a turbomachine and more particularly to a sealing arrangement at a parting plane between an upper casing and a lower casing of the turbomachine . A turbomachine, such as a steam turbine, includes a casing usually embodied in two parts, namely an upper casing and a lower casing. The two part embodiment of the casing facilitates assembly of a rotor. The upper casing and the lower casing are joined to one another in the assembled state by way of joining areas. The upper casing and the lower casing form a joint, and a plane formed between the upper casing and the lower casing is referred to as a parting plane. At the parting plane the upper casing and the lower casing are joined together by means of joint flange and joint screws or bolts.

At the parting plane steam leakage may occur during the operation of the steam turbine resulting in hot steam to escape through the joint at the parting plane. The wall thickness of the casings is non uniform which results in non-uniform temperature distribution and thus stresses appear in the casings, which results in leakages in the joint areas and particularly at the parting plane. Currently, leakage is prevented by using a sealing ring along with bolting and/or by providing grooves on the surface of the joint flanges which reduces the area and increase pressure to prevent leakage of steam. However, the above mentioned arrangements are unable to fully prevent leakage of steam at the parting plane of the upper casing and the lower casing. It is therefore an object of the present invention to provide an improved sealing arrangement for preventing leakage in a turbomachine . The object is achieved by providing a sealing arrangement according to claim 1.

According to the invention a sealing arrangement for a turbo- machine for providing a sealing at a parting plane between an upper casing and a lower casing of the turbomachine is presented. The sealing arrangement comprises a sealing strip comprising a first portion and a second portion forming a groove therebetween, wherein the first portion the second portion and the groove extend from a first end to a second end of the sealing strip and wherein the sealing strip is mechanically coupled to the lower casing such that the second portion is in contact with the lower casing. By having the sealing strip with the first portion and the second portion with the second portion in contact with the lower casing and a groove formed between the first portion and the second portion, the sealing strip enables an improved sealing preventing leakage of steam by having a sealing at a line of contact with the lower casing and the outer casing. Furthermore, the sealing arrangement is flexible and can provide sealing even during wear and tear.

The sealing strip is mechanically coupled to the lower casing along the groove which enables contact of the second portion with the lower casing and the first portion with the upper casing at respective contact points.

In one embodiment, the first portion of the sealing strip is in contact with the upper casing of the turbomachine. Such an arrangement prevents leakage of steam from the parting plane towards the upper casing side of the turbomachine.

In one embodiment, the sealing strip is formed from a metallic material. Use of metallic material is cost-effective since the strip can be easily manufactured and fastened to the wall of the casing. Additionally, sealing strip made of metallic material is capable of withstanding high temperatures and pressure.

In another embodiment, the sealing strip is formed from a non-metallic material. Sealing strip made of non-metallic material is impervious to external or internal corrosion and may be used at locations which are not subjected to high tem- peratures.

In one embodiment a plurality of seals are disposed perpendicularly on the sealing strip at the first end and the second end, this prevents leakage through a space formed be- tween the groove and the first portion and the second portion of the sealing strip and further preventing leakage of the fluid from the ends of the sealing strip.

In one embodiment, the seals are labyrinth seals which enable in reduction of energy of the fluid entering from the ends of the sealing strip, since the labyrinth seal creates a complicated path for the fluid to pass through thereby reducing the energy of the fluid. In one embodiment, the upper casing and the lower casing apply a force on the first portion and the second portion respectively of the sealing strip in a radial direction thereby ensuring enhanced sealing at the respective points of contact .

In one embodiment, the sealing strip is coupled to the lower casing using bolt or screws. Bolting or screwing can be embodied easily and provides for durable and reliable coupling of the sealing strip to the inner wall of the casing.

The above-mentioned and other features of the invention will now be addressed with reference to the accompanying drawings of the present invention. The illustrated embodiments are intended to illustrate, but not limit the invention. The drawings contain the following figures, in which like numbers refer to like parts, throughout the description and drawings. FIG. 1 is a schematic representation of a three dimensional section of a casing of a turbomachine,

FIG. 2 is a schematic representation depicting a radial section of the casing of the turbomachine,

FIG. 3 is a schematic diagram depicting an exemplary sealing strip,

FIG. 4 is a schematic diagram depicting the sealing strip alongwith seals disposed perpendicularly in the sealing strip,

FIG. 5 is a schematic diagram depicting an assembly of the sealing strip to the casing, and

FIG. 6 is a flow diagram depicting a method for sealing arrangement for the turbomachine, in accordance with aspects of the present technique. Embodiments of the present invention generally relate to a turbomachine, such as a gas turbine, a steam turbine, a turbo fan, a turbo compressor and the like and more particularly to a sealing arrangement for preventing leakage of a fluid in the turbomachine. Although the invention is directed to a sealing arrangement for a turbomachine, it may however be noted that such a sealing arrangement may be used in any pressurized vessel for preventing leakage.

FIG. 1 depicts a three dimensional cut section of a casing 1 of a turbomachine such as but not limited to a steam turbine. The casing 1 includes a lower casing 2 and an upper casing 3. The upper casing 3 and the lower casing 2 are joined to one another in an assembled state. Joints between the upper cas- ing and the lower casing are formed on a plane 6, which is referred to as a parting plane between the upper casing 3 and the lower casing 2. More particularly, the parting plane 6 is the plane between the two parts that is the upper casing 3 and the lower casing 2 of the turbomachine .

In order to ensure that fluid, such as steam does not leak through the joints at the parting plane, the joints must be closed as tightly as possible. The upper casing 3 and the lower casing 2 are coupled to each other. More particularly, the upper casing 3 and the lower casing 2 are fixedly screwed or bolted to one another. To enable this, the lower casing 2 and the upper casing 3 include joint flanges 4, 5 which may be screwed tightly against one another.

As previously noted, even with the above mentioned arrangement fluid may leak through the joints at the parting plane 6, therefore in accordance with the aspects of the present technique, a sealing strip 10 is mechanically coupled to the casing 1. More particularly, the sealing strip 10 is mechanically coupled to the lower casing 2 at the parting plane 6 such that at least a part of the sealing strip 10 is above the parting plane 6. In accordance with aspects of the present technique, the part of the sealing strip above the parting plane 6 forms a contact with the upper casing 3 during the assembly. The sealing strip 10 may be placed along the entire extent of the parting plane 6, or alternatively, the sealing strip 10 may be placed at locations along the parting plane 6 where the probability of leakage of the fluid is high.

Furthermore, in accordance with aspects of the present technique, the sealing strip 10 is coupled to an inner wall 7 of the lower casing 2. It may be noted that the coupling of the sealing strip 10 is done prior to the assembly of the upper casing 3 with the lower casing 2. Referring now to FIG. 2 a radial section of the casing 1 of the turbomachine is depicted. The sealing arrangement including the sealing strip 10 is coupled to the inner wall 7 of the casing 1 at the joints formed at the parting plane 6 be- tween the lower casing 2 and the upper casing 3. The sealing strip 10 includes a plurality of holes 12 for bolting or screwing to the inner wall 7 of the lower casing 2. Additionally, the sealing arrangement also includes a plurality of seals (not shown in FIG. 2) arranged perpendicular to the length of the sealing strip 10, wherein the plurality of seals are disposed on the sealing strip. The sealing arrangement will be described in a greater detail with reference to FIG. 3 and FIG. 4. Referring now to FIG. 3 a schematic diagram of the exemplary sealing strip 10 is depicted. The sealing strip 10 includes a first side 16 and a second side 14 opposing each other and a first end 17 and a second end 18 defining the length of the sealing strip 10. Furthermore, the sealing strip 10 includes a first portion 19 and a second portion 20 forming a groove 22 therebetween, such that the first portion 19, the second portion 20 and the groove 22 extends from the first end 17 to the second end 18 of the sealing strip 10. The groove 22 further includes a protrusion 23 extending from the first end 17 to the second end 18 of the sealing strip 10.

More particularly, the first portion 19, the second portion 20 and the groove 22 alongwith the protrusion 23 is present on the first side 16 of the sealing strip 10. As previously noted, the sealing strip 10 is mechanically coupled to the lower casing 2. Specifically, the sealing strip 10 is mechanically coupled to the inner wall 7 of the lower casing 2 such that the second portion 20 is in contact with the lower casing 2.

The sealing strip 10 is coupled to the lower casing 2 through bolts and/or screws. More particularly, the coupling of the sealing strip 10 is achieved by bolting or screwing along the protrusion 23 at the groove 22 of the sealing strip. Alternatively, the sealing strip 10 may also be attached to the lower casing 2 through welding. In accordance with aspects of the present technique, the sealing strip 10 may be formed from a metallic material or an alloy, such as but not limited to a nickel based alloy.

Alternatively, the sealing strip 10 may also be formed from a non-metallic material, such as but not limited to rubber or a polymer. It may further be noted that the choice of material for sealing strip 10 is dependent on the location of the sealing strip and exposure of the sealing strip 10 to the environment inside the turbomachine . As previously noted, the sealing strip 10 has the first portion 19 and the second portion 20 on the first side 16. The first portion 19 and the second portion 20 are typically curved in shape thereby forming a respective line of contact with the upper casing 3 and the lower casing 2 respectively. Particularly, the first portion 19 and the second portion 20 form a typical semi -circular shape and extend from the first end 17 to the second end 18.

As previously noted, the second portion 20 of the sealing strip 10 is coupled to the lower casing 2. The arrangement is such that the first portion 19 of the sealing strip 10 comes in contact with the upper casing 3 and specifically to the inner wall of the upper casing 3 forming a sealing at the contact points.

The joint at the parting plane 6 formed between the lower casing 2 and the upper casing 3 is sealed due to the first portion 19 and the second portion 20 of the sealing strip 10. Additionally, the sealing strip 10 includes a plurality of slots 24, 25 at the first end 17 and the second end 18 respectively. The slots 24, 25 extend in a region from the first portion 19 to the second portion 20 for accommodating seals, which are disposed perpendicularly along the length of the sealing strip 10.

FIG.4 is a schematic diagram of the sealing strip 10 along- with seals 30, 32 disposed perpendicularly in the sealing strip 10. As depicted the plurality of seals 30, 32 are disposed in slots 24, 25 in the sealing strip 10 at the first end 17 and the second end 18. The seals 30, 32 are disposed in a perpendicular direction along the length of the sealing strip 10. The seals 30, 32 are labyrinth seals which prevent the leakage of the fluid entering from the ends 17, 18 of the sealing strip 10.

As previously noted, the sealing strip 10 includes the groove 22 between the first portion 19 and the second portion 20.

Fluid may enter through a space formed by the groove 22 from the first end 17 or the second end 18 and may leak therefrom. In order to prevent leakage, the seals 30, 32 are disposed perpendicularly along the length of the sealing strip 10 to prevent leakage.

Seals 30, 32 may be formed from a metallic or a non-metallic material based on the operating conditions and thermodynamic parameters. The length of the seals 30, 32 is dependent on the thermodynamical parameters of the fluid such as, but not limited to pressure and temperature. Energy of the fluid passing through the seals 30, 32 is lowered due to the structure of the seals preventing leakage from the joints. In one embodiment, the space between the first seal 30 and the second seal 32 in the sealing strip 10 may be connected to a low pressure region inside the turbomachine enabling the fluid to be passed to the low pressure region.

FIG. 5 is a schematic diagram depicting an assembly of the sealing strip to the casing of the turbomachine. Three different positions of the sealing strip during assembly are illustrated by reference numerals 34, 36 and 38. Reference numeral 34 depicting the first position shows a side view of the sealing strip 10 having the first portion 19, the second portion 20 and the groove 22 therebetween. The groove 22 includes a protrusion 23 which extends along the length of the sealing strip 10. The protrusion 23 is designed such that a difference between a width 39 of the sealing strip 10 at the contact points 43, 45 and a width 40 of the sealing strip 10 at the protrusion 23 is "X" mm, as depicted in FIG. 5. It may be noted that "X" may be from about 1 mm to about 2 mm. However, in other cases "X", which is the gap between the two widths, may vary from a distance greater than 0 mm to about 5 mm depending on the design requirements and placement of the sealing strip.

Reference numeral 36 depicts the coupling of the sealing strip 10 through a bolt 42 along the groove 22 between the first portion 19 and the second portion 20. The sealing strip 10 is coupled to the inner wall 7 of the lower casing 2 along the protrusion 23 in the groove 22 which results in the second portion 20 forming the sealing with the lower casing 2 at the contact point 45. The first portion 19 of the sealing strip 10 is not deformed and extends to a distance "X" further from the inner wall 7 of the lower casing 2, as depicted. Reference numeral 38, depicts the upper casing 3 placed over the lower casing 2, such that the upper casing 3 forms a contact with the first portion 19 of the sealing strip 10 at the contact point 43. The upper casing 3 includes a chamfer 46 on an edge to prevent damage to the sealing strip 10 during the assembly procedure. At the above-mentioned step of assembly, both the first portion 19 and the second portion 20 of the sealing strip 10 are deformed resulting in a preload for sealing . FIG. 6 is a flow diagram depicting an exemplary method 50 for providing the sealing arrangement, in accordance with aspects of the present technique. As previously noted, the sealing arrangement provides a sealing at a parting plane 6 between the upper casing 3 and the lower casing 2 of a turbomachine . More particularly, the sealing arrangement provides a sealing at the joints in the parting plane between the lower casing 2 and the upper casing 3.

The sealing arrangement includes the sealing strip 10 and the plurality of seals 30, 32 disposed perpendicularly along the length of the sealing strip 10. The sealing strip 10 includes the first portion 19 and the second portion 20 forming the groove 22 therebetween, such that the first portion 19, the second portion 20 and the groove 22 extend along the length of the sealing strip 10 that is from the first end 17 to the second end 18.

At step 52, the sealing strip 10 is positioned close to the lower casing 2 of the turbomachine such that, the second portion 20 of the sealing strip 10 is contact with the inner wall 7 of the lower casing 2 and the first portion 19 is above the parting plane 6.

At step 54, the sealing strip 10 is mechanically coupled to the lower casing 2. More particularly, the sealing strip 10 is mechanically coupled to the inner wall 7 of the lower cas- ing 2 along the groove 22. This ensures a tight sealing between the second portion 20 of the sealing strip 10 and the lower casing 2 at the contact point 45. However, due to tightening of the sealing strip 10 with the lower casing 2, along the protrusion 23 in the groove 22, the second portion 20 of the sealing strip 10 is deformed.

At step 56, the upper casing 3 is assembled by placing it over the lower casing 2, the upper casing 3 forms a contact with the first portion 19 of the sealing strip 10 providing sealing at the contact point 43 with the first portion 19.

It may be noted that the upper casing 3 includes the chamfer 46 on the edge for providing a smooth fit without damaging the sealing strip 10, the upper casing 3 also deforms the first portion 19 of the sealing. The deformation of the first portion 19 and the second portion 20 by the upper casing 3 and the lower casing 2 respectively creates a preload for sealing. The deformation in the first portion 19 and the second portion 20 of the sealing strip 10 is due to the radial force exerted by the upper casing 3 and the lower casing 2 respectively providing a tight sealing. Subsequently, at step 58, the upper casing 3 and the lower casing 2 are bolted and/or screwed at the joint flanges 4, 5. By screwing or bolting the two parts 2, 3 of the casing, the casing is securely sealed. Additionally, during operation the pressure inside the casing 1 further compresses the sealing strip 10 in a radial direction further ensuring the sealing at the point of contact.

Although the invention has been described with reference to specific embodiments, this description is not meant to be construed in a limiting sense. Various modifications of the disclosed embodiments, as well as alternate embodiments of the invention, will become apparent to persons skilled in the art upon reference to the description of the invention. It is therefore contemplated that such modifications can be made without departing from the embodiments of the present invention as defined.

Claims

Patent Claims

1. A sealing arrangement for a turbomachine for providing a sealing at a parting plane (6) between an upper casing (3) and a lower casing (2) of the turbomachine, the sealing arrangement comprises

- a sealing strip (10) comprising a first portion (19) and a second portion (20) forming a groove (22) therebetween, wherein the first portion (19) , the second portion (20) and the groove (22) extend from a first end (17) to a second end (18) of the sealing strip (10) and wherein the sealing strip (10) is mechanically coupled to the lower casing (2) such that the second portion (20) is in contact with the lower casing (2) ,

wherein the sealing strip (10) is mechanically coupled to the lower casing (2) along the groove (22) .

2. The sealing arrangement according to claim 1,

wherein the first portion (19) of the sealing strip (10) is in contact with the upper casing (3) of the turbomachine.

3. The sealing arrangement according to claims 1 and 2, wherein the sealing strip (10) is formed from a metallic material.

4. The sealing arrangement according to claims 1 and 2, wherein the sealing strip (10) is formed from a non-metallic material.

5. The sealing arrangement according to any of the claims 1 to 5 ,

wherein the sealing strip (10) is coupled to the lower casing (2) through screws and/or bolts.

6. The sealing arrangement according to any of the claims 1 to 5 ,

wherein the sealing strip (10) is mechanically coupled to an inner wall (7) of the lower casing (2) .

7. The sealing arrangement according to claims 1 to 6 , further comprising a plurality of seals (30, 32) disposed perpendicularly on the sealing strip (10) at the first end (17) and the second end (18) .

8. The sealing arrangement according to claim 7,

wherein the seals (30, 32) are labyrinth seals.

9. The sealing arrangement according to claim 7 and 8, wherein the seals (30, 32) are formed from a metallic material .

10. The sealing arrangement according to claim 7 and 8, wherein the seals (30, 32) are formed from a non-metallic material.

11. The sealing arrangement according to any of the claims 1 to 10,

wherein the upper casing (3) and the lower casing (2) apply a force on the first portion (19) and the second portion (20) respectively of the sealing strip (10) in a radial direction .

12. A turbomachine comprising a sealing arrangement accord- ing to any of the preceding claims 1 to 11.