Claims:1) A means to prevent leakage of working fluid between outer casing and inner casing of a turbomachine, said outer casing split across horizontal plane in to a bottom half outer casing (42) and a top half outer casing (48), said inner casing split across horizontal plane in to a bottom half inner casing (40) and a top half inner casing (44), said bottom half inner casing (40) configured within said bottom half outer casing (42), said top half inner casing (44) adapted to mate and bolt with complementary said bottom half inner casing (40) characterized in that a plurality of grooves (G3) provided on integrally formed hoses (H1) of said top half inner casing (44), a plurality of annular seals (46) split at one portion adapted to mate with the plurality of grooves (G3) of said top half inner casing (44) and said top half outer casing (48) gradually placed over said top half inner casing (44) and bolted to said bottom half outer casing (42) in such a way that internally formed holes (H2) of said top half outer casing (48) adapted to mate with said plurality of annular seals (46) of said top half inner casing (44) in an interference fit.

2) A means to prevent leakage of working fluid between outer casing and inner casing of a turbomachine as claimed in claim 1, wherein a chamfer (C) formed around the circumference of said internally formed holes (H2) of said top half outer casing (42) compresses said plurality of annular seals (46) and guides the assembly of said top half outer casing (42) with said top half inner casing (44).

3) A means to prevent leakage of working fluid between outer casing and inner casing of a turbomachine as claimed in claim 1, wherein uniform height is maintained between said top half outer casing (48) and said bottom half outer casing (42) on either side of horizontal plane during assembly.

4) A means to prevent leakage of working fluid between outer casing and inner casing of a turbomachine as claimed in claim 1, wherein said split at one portion of said plurality of annular seals (46) facilitates in adding tension in the plurality of annular seals (46) when compressed and further producing an expansion effect.

5) A means to prevent leakage of working fluid between outer casing and inner casing of a turbomachine as claimed in claim 1, wherein said split at one portion of said plurality of annular seals (46) is made in such a way that a complementary L shaped steps (LS) are formed on either ends of said plurality of annular seals (46).

6) A means to prevent leakage of working fluid between outer casing and inner casing of a turbomachine as claimed in claim 5, wherein said complementary L shaped steps (LS) of said plurality of annular seals (46) mate with each other during assembly.

7) A method of assembly of a means to prevent leakage of working fluid between outer casing and inner casing of a turbomachine, said method of assembly of said means comprising the steps of :
a) placing a top half inner casing (44) over a bottom half inner casing (40) configured within a bottom half outer casing (42) and locked in position, said top half inner casing (44) provided with a plurality of grooves (G3) over circumference of integrally formed hoses (H1);
b) positioning a plurality of annular seals (46) over said plurality of grooves (G3) of said top half inner casing (44);
c) placing a top half outer casing (48) gradually over said top half inner casing (44) in such a way that internally formed holes (H2) of said top half outer casing (48) adapted to mate with said plurality of annular seals (46) of said top half inner casing (44) in an interference fit; and
d) locking of said top half outer casing (48) to said bottom half outer casing (42) across horizontal plane.
, Description:FIELD OF THE INVENTION:
The present invention relates to the field of seal rings. Particularly, the present invention relates to a method of assembly of the seal rings between outer casing and inner casing of a turbo machine.

BACKGROUND OF THE INVENTION:
Figure 1(a) illustrates a cross sectional view of assembly of outer casing and inner casing at control stage of a steam turbine.

Figure 1(b) illustrates an enlarged view of portion A of figure 1(a).

The traditional method of assembly of the seal rings at the interface of outer casing OC and inner casing IC of the steam turbine to prevent leakage of steam is very complicated, laborious and time consuming. The method of assembly of the annular seals includes the following steps:
1) Firstly, the top half of outer casing OC is inverted.
2) The inner wall of the outer casing OC is indicated by a letter I as shown in the figure 1(b). Secondly, an annular spacer 12 is inserted in to the outer casing such that the circumference of the annular spacer 12 mates with the inner wall I of the outer casing OC.
3) Thirdly, an annular spacer-top 14 having an inner diameter greater than the annular spacer 12 is inserted in to the outer casing OC such that the annular spacer-top 14 is positioned over the annular spacer 12.
4) Fourthly, a pair of annular seals 16 of L shaped cross-section mounted on a pair of annular seal holders 18 of L shaped cross-section are inversely inserted in to the outer casing OC such that base portion B of the annular seals 16 and top portion T1 of the annular seal holders 18 mates with the preceding surface of the annular spacer-top 14 or the annular seal holder 18.
5) Fifthly, a split shear ring 20 is inserted in to a slot provided in the outer casing OC such that the split shear ring 20 mates with the preceding surface of the annular seal holder 18.
6) Sixthly, an annular spacer-bottom 22 of L shaped cross-section is inversely inserted in to the outer casing OC in such a way that it mates with the preceding surface of the annular seal holder 18 at its top portion T2 and encompassed by the split shear ring 20.
7) Seventhly, a locking pin 24 passing through the annular spacer-bottom 22 is inserted in to the inner wall I of the outer casing OC which thereby arrests the movement of the annular seal holders 18, the annular seals 16, the annular spacer-top 14 and the annual spacer 12.
8) Finally, a plurality of cylinders 26 which acts as a conduit for fluid communication between the outer casing OC and the inner casing IC are inserted in to the outer casing OC achieving an interference fit between the annular seals 16 and the cylinders 26.

Typically, gaps G1 provided between the annular seals 16 and the annular seal holders 18 and a gap G2 provided between one of the annular seals 16 and the annular spacer-top 14 facilitates in achieving the interference fit between the annular seals 16 and the cylinders 26.

Some techniques have been disclosed in the prior art to arrest leakage of steam between casings of a steam turbine.
US Patent Application Publication no. 20140205435 published on July 24, 2014 titled “Inner Casing for a Steam turbine Engine” discloses a steam turbine comprising an outer casing and inner casing, wherein the inner casing is configured within the outer casing. The inner casing is split in to two halves across the horizontal plane. The two halves of the inner casing are assembled together by placing an annular seal split at one portion in a recess defined in the two halves of the inner casing. A pin is adapted to fit in a recess defined in the two halves of the inner casing in such a way to close the split portion of the annular seal thereby preventing the rotation of the annular seal. In this method, the assembly time is more due to lack of visibility of sealing location to the workmen and requires dexterity of the workmen. Further, once assembled the workmen would not be in a position to confirm whether the annular seal and the pin are sat in exact seating location in the two halves of the inner casing. The US Patent Publication also teaches about sealing mechanism between the outer casing and top half of the inner casing but here the annular seal act as a conduit for passage of steam and is in spaced relationship between the outer casing and top half of the inner casing. In this method, the recess to accommodate the annular seals is defined within the outer casing and top half of the inner casing.

US Patent no. 2796231 filed on March 24, 1954 titled “High Pressure Steam Turbine Casing Structure” discloses an inner casing split in to two halves on horizontal plane disposed in to respective two halves of a outer casing in spaced relation. Though the granted patent discusses about double wall casing structure, it is silent on sealing arrangement between the casings. The granted patent teaches about labyrinth seal disposed between the inner casing and a gland collar and between the outer casing and a rotor.

Therefore, there is felt a need for development of a sealing arrangement between outer casing and inner casing to overcome the drawbacks of the prior art and thereby effectively preventing the leakage of steam.

OBJECTS OF THE INVENTION:
An object of the present invention is to provide a simple and fool proof mechanism to prevent leakage of working fluid between outer casing and inner casing.

Another object of the present invention is to reduce time involved in assembling of seals between outer casing and inner casing.

One more object of the present invention is to provide visibility to the workmen while assembling of seals between outer casing and inner casing.

Still another object of the present invention is to reduce effort of the workmen involved in assembling of seals between outer casing and inner casing.

Further another object of the present invention is to perform assembling of seals between outer casing and inner casing even with unskilled workmen also.

Yet one more object of the present invention is to reduce the number of components required to produce the desired sealing effect between outer casing and inner casing.

SUMMARY OF THE INVENTION:
In accordance with the present invention a means to prevent leakage of working fluid between outer casing and inner casing of a turbomachine is provided, the outer casing split across horizontal plane in to a bottom half outer casing (42) and a top half outer casing (48), the inner casing split across horizontal plane in to a bottom half inner casing (40) and a top half inner casing (44), the bottom half inner casing (40) configured within the bottom half outer casing (42), the top half inner casing (44) adapted to mate and bolt with complementary the bottom half inner casing (40) characterized in that a plurality of grooves (G3) provided on integrally formed hoses (H1) of the top half inner casing (44), a plurality of annular seals (46) split at one portion adapted to mate with the plurality of grooves (G3) of the top half inner casing (44) and the top half outer casing (48) gradually placed over the top half inner casing (44) and bolted to the bottom half outer casing (42) in such a way that internally formed holes (H2) of the top half outer casing (48) adapted to mate with the plurality of annular seals (46) of the top half inner casing (44) in an interference fit.

Typically, the split at one portion of the plurality of annular seals (46) facilitates in adding tension in the plurality of annular seals (46) when compressed and further produces an expansion effect.

Typically, a chamfer (C) formed around the circumference of the internally formed holes (H2) of the top half outer casing (42) compresses the plurality of annular seals (46) and guides the assembly of the top half outer casing (42) with the top half inner casing (44).

Typically, uniform height is maintained between the top half outer casing (48) and the bottom half outer casing (42) on either side of horizontal plane during assembly.

In accordance with the present invention a method of assembly of a means to prevent leakage of working fluid between outer casing and inner casing of a turbomachine is provided, the method of assembly of the means comprising the steps of:
i) placing a top half inner casing (44) over a bottom half inner casing (40) configured within a bottom half outer casing (42) and locked in position;
ii) providing a plurality of grooves (G3) over circumference of integrally formed hoses (H1) of said top half inner casing (44);
iii) positioning a plurality of annular seals (46) over said plurality of grooves (G3) of said top half inner casing (44);
iv) placing a top half outer casing (48) gradually over said top half inner casing (44) in such a way that internally formed holes (H2) of said top half outer casing (48) adapted to mate with said plurality of annular seals (46) of said top half inner casing (44) in an interference fit; and
v) locking of said top half outer casing (48) to said bottom half outer casing (42) across horizontal plane.

BRIEF DESCRIPTION OF THE DRAWINGS:
The invention will now be described with reference to the accompanying drawings in which:
Figure 1(a) illustrates a cross sectional view of assembly of outer casing and inner casing at control stage of a steam turbine according to the prior art;

Figures 1(b) illustrate an enlarged view of portion A of figure 1(a) respectively;

Figure 2 illustrates a perspective view of a bottom half inner casing and a top half inner casing assembled on to a bottom half outer casing in accordance with the present invention;

Figure 3 illustrates an enlarged view of grooves formed on the top half inner casing of figure 2;

Figure 4 illustrates an isometric view of annular seals in accordance with the present invention; and

Figure 5 illustrates a cross sectional view of a top half outer casing assembled on to the top half inner casing in accordance with the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS:
A preferred embodiment will now be described in detail with reference to accompanying drawings. The preferred embodiment does not limit the scope and ambit of the invention. The description provided is purely by way of example and illustration.

Figure 2 illustrates a perspective view of a bottom half inner casing and a top half inner casing assembled on to a bottom half outer casing.

Figure 3 illustrates an enlarged view of grooves formed on the top half inner casing of figure 2.

In accordance with the present invention, a bottom half inner casing 40 is disposed within a bottom half outer casing 42. A top half inner casing 44 is mounted on the bottom half outer casing 42 with the help of flanges F complementary to the bottom half inner casing 40 and bolted to the bottom half inner casing 40.

A plurality of grooves G3 are provided around the circumference of integrally formed hoses H1 of the top half inner casing 44 at their top end.

Figure 4 illustrates an isometric view of annular seals.
In accordance with the present invention, there is provided a plurality of annular seals 46 split at one portion having an inner diameter complementary to the grooves G3 of the top half inner casing 44. The split at one portion of the plurality of annular seals 46 is made in such a way that a complementary L shaped steps LS are formed on either ends which mate with each other during assembly. The split at one portion of the annular seals 46 facilitates in achieving proper fit during assembly.

Figure 5(a) illustrates a cross sectional view of a top half outer casing assembled on to the top half inner casing.

Figure 5(b) illustrates an enlarged view of portion B of figure 5(a).

In accordance with the present invention, the plurality of annular seals 46 are adapted to mate with the plurality of grooves G3 of the top half inner casing 44 and a top half outer casing 48 is placed over the top half inner casing 44 in such a way that internally formed holes H2 of the top half outer casing 48 are adapted to pass over the plurality of annular seals 46 encompassing the plurality of grooves G3 of the top half inner casing 44. A chamfer C is provided around the circumference of the internally formed holes H2 of the top half outer casing 48 which guides the assembly of the top half outer casing 48 with the top half inner casing 44 by compressing the plurality of annular seals 46. The top half outer casing 48 is locked to the bottom half outer casing 42 at horizontal plane.

The configuration and method of assembly of the plurality of annular seals 46 in accordance with the present invention is as follows:
The plurality of annular seals 46 are adapted to encircle over the plurality of grooves G3
of the top half inner casing 44. The top half outer casing 48 is gradually placed over the top half inner casing 44 such that the internally formed holes H2 of the top half outer casing 48 are adapted to pass over the plurality of annular seals 46 encompassing the plurality of grooves G3 of the top half inner casing 44 and equal height is maintained between the top half outer casing 48 and the bottom half outer casing 42 on either side of the horizontal plane. The Chamfer C of internally formed holes H2 of the top half outer casing 48 while assembling over the plurality of annular seals 46 compresses the plurality of annular seals 46 adding tension in the plurality of annular seals 46 which ultimately results in the expansion of the plurality of annular seals 46 thereby providing a tight sealing effect between the top half outer casing 48 and the top half inner casing 44. The maintenance of equal height between the top half outer casing 48 and the bottom half outer casing 42 on either side of the horizontal plane ensures proper seating of the internally formed holes H2 of the top half outer casing 48 over the plurality of annular seals 46 of the top half inner casing 44 as any minor tilt in the assembly of the top half outer casing 48 may result in the creation of gap between the internally formed holes H2 of the top half outer casing 48 and the plurality of annular seals 46 which ultimately results in the leakage of the working fluid.

TECHNICAL ADVANCEMENTS:
A means to prevent leakage of working fluid between outer casing and inner casing of a turbomachine has several technical advantages including but not limited to the realization of :
• a simple and fool proof mechanism to prevent leakage of working fluid between outer casing and inner casing ;
• a means which can be assembled between outer casing and inner casing in less time ;
• a means which can facilitate in providing visibility to the workmen while assembling in between outer casing and inner casing ;
• a means which can reduce effort of the workmen while assembling in between outer casing and inner casing ;
• a means that can be assembled between outer casing and inner casing even with unskilled workmen also ; and
• a means where less components are used to produce the desired sealing effect between outer casing and inner casing.

Although the invention has been described herein above with reference to the embodiments of the invention, the invention is not limited to the embodiments described herein above. It is to be understood that modifications and variations of the embodiments can be made without departing from the spirit and scope of the invention.