US3642380A

US3642380A - Turbine support structure

Info

Publication number: US3642380A
Application number: US26232A
Authority: US
Inventors: Paul D Saunders
Original assignee: Westinghouse Electric Corp
Current assignee: CBS Corp
Priority date: 1970-04-07
Filing date: 1970-04-07
Publication date: 1972-02-15
Anticipated expiration: 1989-02-15

Abstract

In a turbine of the type in which the cylinder or stator casing is supported by a vertical wall, vertical motion at the rotor centerline, due to thermal expansion, is caused mainly by expansion of the stator casing. If the casing is effectively fixed at the bottom, as in prior structures, the thermal expansion of the casing adds to the expansion of the rest of the supporting structure. The disclosed support structure introduces flexibility into the supporting wall along the lower portion of the casing, thereby causing the expansion of the casing to be subtracted from the expansion of the rest of the supporting structure.

Description

United States Patent Saunders Feb. 15, 1972 [54] TURBINE SUPPORT STRUCTURE [211 Appl. No.: 26,232

[52] US. Cl ..4l5/136, 415/219 [51] Int. Cl ..F0ld 25/26 [58] fieldoISearch ..4l5/l34,136,219,l2

' [56] References Cited UNITED STATES PATENTS FOREIGN PATENTS OR APPLICATIONS 949,873 2/1964 Great Britain ..4l5/ l 36 Primary Examiner-C. J. Husar Attorney-A. T. Stratton, F. P. Lyle and F. Cristiano, Jr.

[57] ABSTRACT In a turbine of the type in which the cylinder or stator casing is supported by a vertical wall, vertical motion at the rotor centerline, due to thennal expansion, is caused mainly by expansion of the stator casing. If the casing is effectively fixed at the bottom, as in prior structures, the thermal expansion of the casing adds to the expansion of the rest of the supporting structure. The disclosed support structure introduces flexibility into the supporting wall along the lower portion of the easing, thereby causing the expansion of the casing to be subtracted from the expansion of the rest of the supporting structure.

7 Claims, 4 Drawing Figures PATENTEDFEB 15 I972 SHEET 1 OF 2 TURBINE SUPPORT STRUCTURE BACKGROUND OF THE INVENTION This invention relates, generally, to elastic fluid machines, and more particularly, to means for supporting the stator casing of an axial flow turbine.

In prior turbine support structures in which the turbine cylinder or stator casing is supported by a vertical wall, the casing is effectively fixed at the bottom, thereby causing the thermal expansion of the casing to be added to the expansion of the rest of the supporting structure which results in undesirable vertical motion of the casing at the rotor centerline. The present invention provides a turbine support structure which overcomes the aforesaid undesirable feature of prior structures.

SUMMARY OF THE INVENTION In accordance with one embodiment of the invention, the lower half of a turbine cylinder or casing is disposed in a semicircular opening in a vertical wall which supports the easing. The radius of the opening is greater than the radius of the casing, thereby spacing the casing from the wall. A semicircular strap of flexible material extends flatwise around the lower portion of the casing between the casing and the wall with one edge attached to the wall and the other edge attached to the casing. Thus, radial flexibility is introduced into the support structure along the lower portion of the cylinder. This has the effect of changing the point of flxity of the cylinder relative to the wall from the bottom of the cylinder to a point above the horizontal joint of the cylinder. The thermal expansion of the cylinder tends to move the rotor centerline downwardly relative to the wall, and this expansion is subtracted from the expansion of the rest of the supporting structure.

BRIEF DESCRIPTION OF THE DRAWINGS For a better understanding of the nature of the invention, reference may be had to the following detailed description, taken in conjunction with the accompanying drawings, in which:

FIG. 1 is a view, partly in elevation and partly in axial sec- 'tion, taken on a vertical plane, of an axial flow turbine and DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to the drawings, particularly to FIG. 1, there is shown an axial flow turbine having a'plurality of stages for expanding fluid in an axial direction in a manner well known in the art. Each expansion stage comprises an annular row of stationary nozzles or vanes 12 cooperating with and immediately preceding an annular row of rotatable blades 14. The stationary nozzles increase in radial length progressively from the first row of expansion stage nozzles 16 to the last row of expansion stage nozzles 18. Likewise, the rotatable blades increase in radial length progressively from the first row of expansion stage blades 20 to the last row of expansion stage blades 22.

The stationary nozzles 12 are retained in a generally tubular stator casing structure 24. The rotatable blades 14 may be carried by a rotor wheel 26 attached to a rotor shaft 28 concentrically disposed within the casing 24 and rotatably supported by

suitable bearings

30 and 32. The bearing 30 is mounted in a bearing housing 34 supported by a vertical wall 36 of an exhaust housing 38 of the turbine 10. The bearing 32 is mounted in a bearing housing 40 supported by the stator casing 24. The housing 40 also encompasses a thrust bearing 42 for the shaft 28.

A suitable inlet structure 44 is provided for directing hot motive fluid into an annular nozzle chamber 46 from which it flows axially through the expansion stage nozzles 12 and blades 14. After expansion, the motive fluid is exhausted into the exhaust housing 38 from which it flows downwardly into a condenser housing 48 attached to the bottom of the exhaust housing 38 by means of flanges $0. The condenser housing 48 rests on the bottom of a boat or other suitable support structure 52. Condensing water may enter the condenser through pipe 49 and leave through pipe 51. The condensed vapor may leave through pipe 53 at the bottom of the housing 48.

One end of the rotor shaft 28 is provided with a coupling flange S4 for connecting the shaft 28 to a reduction gearing shaft (not shown) to drive the propeller of a marine vessel. Also, the other end of the rotor shaft 28 may be connected to the shaft of a reversing turbine (not shown). Therefore, it is essential that the horizontal centerline L-L of the rotor shaft be maintained in proper alignment under all conditions of operation.

In prior turbines in which the stator casing 24 is supported by a vertical wall 56 which is part of the exhaust housing 38 as shown in FIG. 1, the vertical motion of the casing 24 at the shaft centerline L-L, due to thermal expansion is caused mainly by expansion of the casing. If the stator casing is effectively fixed at the bottom, as in prior structures, the thermal expansion of the casing adds to the expansion of the rest of the supporting structure which includes the exhaust housing 38 and condenser housing 48, thereby throwing the shaft centerline L-L out of alignment with connecting shafts.

In order to maintain proper alignment of the shaft centerline, the support structure shown in FIGS. 1, 2 and 3 is provided. As shown in FIG. 2, the stator casing is divided at a horizontal joint into an upper portion 24a and a lower portion 24b. The lower portion 24b is disposed in a semicircular opening 58 in the wall 56 of the exhaust housing 38. The radius of the opening 58 is greater than the radius of the casing portion 24b.

As shown more clearly in FIG. 3, the opening 58 is sealed by means of a flexible member, such as a semicircular metal strip 60 which extends flatwise around the lower portion 24b of the casing between the casing and the wall. One edge of the strip 60 is secured to the wall 56, as by welding, and the other edge is secured to the casing 24b, thereby preventing motive fluid from escaping from the exhaust housing 38. The strip 60 subtends the lower portion of the casing 24b, is frustoconical shaped, and is so disposed that it is subjected to bending stress during expansion and contraction of the casing 24b, thereby permitting radial movement of the casing relative to the wall.

In this manner flexibility is provided in the supporting wall along the lower portion of the stator casing. This has the effect of changing the point of fixity of the casing relative to the wall from the bottom of the casing to a point at or above the horizontal joint of the casing. Therefore, the thermal expansion of the casing tends to move the rotor centerline downwardly relative to the wall, and this expansion is subtracted from the expansion of the rest of the supporting structure.

As shown more clearly in FIG. 2, the exhaust housing 38 is divided into an upper portion or exhaust hood 38a and a lower portion or exhaust base 38b. The exhaust housing may be formed from sheet metal and the two

portions

380 and 38b are provided with

horizontal flanges

62a and 62b, respectively, which are joined together by bolts64. The end wall 56 of the base 38b extends on opposite sides of the casing 24 at right angles to the casing 24, the upper portion of the end wall 56 is welded directly to the upper portion of the casing 240 and cooperates with the strip 60 to form a circumferential seal between the end wall 56 and the casing 24. The two

portions

24a and 24b of the casing are separate castings provided with

horizontal flanges

66a and 66b, respectively, which are joined together by bolts 68. The flange 66b extends beyond the opening 58 in the wall 56, thereby supporting the casing 24. The hood 38a may be secured to the upper portion 24a of the casing, as by welding, thereby pennitting the hood 38a and casing portion 24a to be removed as a unit to provide access to the turbine rotor.

From the foregoing description it is apparent that the invention provides a structure for supporting the stator casing of a turbine in a manner in which there is substantially no relative motion of'the rotor shaft centerline between the cold and the hot full speed ahead conditions of operation. The support structure may be economically manufactured and installed.

I claim as my invention:

1. In an elastic fluid turbine support structure comprising, in combination,

a generally tubular stator casing having a lower portion and an upper portion divided at a horizontal joint,

a vertical supporting wall subtending the casing and having a semicircular opening therein for receiving the lower portion of the casing,

the radius of the opening being greater than the radius of the casing, and

a semicircular flexible member subtending the lower portion of the casing and so disposed to form an angle with the wall, to extend between the casing and the wall, to be attached to the casing and wall in such a manner as to form a seal therebetween, and to permit radial movement of the casing relative to the wall.

2. The combination defined in claim 1, wherein the wall is part of an exhaust housing for receiving fluid from the stator casing.

3. The combination defined in claim 1, wherein the flexible member is a strip of flexible material extending flatwise around the lower portion of the casing between the casing and the wall with one edge attached to the wall and the other edge attached to the casing.

4. The combination defined in claim 3, wherein the strip is subjected to bending stress during expansion and contraction of the casing.

5. The combination defined in claim 1, wherein the wall extends on opposite sides of the casing at right angles to the longitudinal axis of the casing to support the casing and an upper portion of the wall disposed above the axis of the turbine is fastened directly to the casing forming a seal therebetween which cooperates with the seal formed by the flexible member to provide a circumferential seal between the casing and the wall.

6. The combination defined in claim 5, including horizontal flanges on the upper and the lower portions of the casing secured together at the horizontal joint between said portions and cooperating with the wall to support the casing.

7. The combination defined in claim 1 and further comprising a condenser having a housing, the support wall being disposed to extend vertically downwardly to the housing.

Claims

1. In an elastic fluid turbine support structure comprising, in combination, a generally tubular stator casing having a lower portion and an upper portion divided at a horizontal joint, a vertical supporting wall subtending the casing and having a semicircular opening therein for receiving the lower portion of the casing, the radius of the opening being greater than the radius of the casing, and a semicircular flexible member subtending the lower portion of the casing and so disposed to form an angle with the wall, to extend between the casing and the wall, to be attached to the casing and wall in such a manner as to form a seal therebetween, and to permit radial movement of the casing relative to the wall.

5. The combination defined in claim 1, wherein the wall extends on opposite sides of the casing at right angles to the longitudinal axis of the casing to support the casing and an upper portion of the wall disposed above the axis of the turbine is fastened directly to the casing forming a seal therebetween, which cooperates with the seal formed by the flexible member to provide a circumferential seal between the casing and the wall.