US3169748A

US3169748A - Turbine apparatus

Info

Publication number: US3169748A
Application number: US242770A
Authority: US
Inventors: Robert D Howard; Richard A Ladner; Alvin L Stock
Original assignee: Westinghouse Electric Corp
Current assignee: CBS Corp
Priority date: 1962-12-06
Filing date: 1962-12-06
Publication date: 1965-02-16
Anticipated expiration: 1982-02-16

Description

Feb. 16, 1965 R. D. HOWARD ETAL TURBINE APPARATUS 2 Sheets-Sheet 1 Filed Dec. 6, 62

inner and outer semicircular ring members.

to the diametric edgeiof the diaphragm half. n member is slidably' received in the .keyway and 13 pro- 3,169,748 TUREINE 'AEPARATUS Robert J. Howard, lrlarple Township, Eeiaware (Iounty,

Pa, Richard A. Ladner, (Zamden, NJL, and Alvin fitock, Drexel Hill, Pa, assignors to West nghouse Electrio Corporation, Pittsburgh, 9a., a corporation of Pennsylvania Filed Dec. 6, 1962, Ser. No. 242,770

8 Claims. (Cl. 25339) associated diaphragm halves, then the rotor is positioned I in the lower casing half, and finally the upper casing half is inverted and superimposed on the lower casing half.

Since close running clearances must be established between the rotor and diaphragm structures, the placement of the diaphragm hmves in their associated casing halves is critical and must be accomplishedwith a high degree of precision. One of the methods currently employed requires positioning each diaphragm half with respect to the central longitudinal axis of the machine. Since the longitudinal axis of the machine extends through the intersectionof a central vertical plane and a central horizontal plane, in actual practice, each diaphragm half is first positioned with regard to the central horizontal plane and then positioned with regard to the central vertical plane.

This invention is concerned with an arrangement for positioning a diaphragm half in an associated casing half with regard to the central vertical plane and has for an object to provide an improved arrangement of thlS type.

Another object of the invention is to provide a 'diaphragnipositioning arrangement 'of the above type that is readily adjustable during assembly, thereby facilitating the precise positioning of the diaphragm half and permitting'larger dimensional tolerances during fabrication of the diaphragm half.

Briefly, in accordance with the invention, an annular bladed diaphragm structure is divided substantially diametrically to form a pair of substantially identical diaphragm halves of semicircular shape, each of which is provided with a semiannular array of blades carried by The outer ring member is provided with a slotted'keyway extending along a chord line disposed in spaced parallelrelation A key Patented Feb. 16, .1965

United States Patent Of'i e 3,169,743

respect to the central horizontal plane of the casing half in any suitable manner, for example, as described and claimed in R. A. Ladner application Serial No. 254,219,

filed January 28, 1963, and assigned to the same 'assignee as this invention. i

- able means.

The above andlthe objects are effected by the invention, as will be apparent from the followingdescriptionand claims taken in connection with the accompanying drawings, forming a part of this application, in which:

FIGURE 1 ,is a cross-sectional view of a steam turbine having the invention incorporated therein;

, FIG. 2 is a central vertical sectional view taken on line l'l-II of FIG. 1, but withtlre rotor omitted for clarity;

FIG. 3 is an enlarged fragmentary View taken on line lIIIlI of FIG. 1;

FIG. 4- is a fragmentary View taken substantially on line lV-IV of FIG. 3, but with the locking meansprovided at final assembly;

FIG. 5 is a fragmentary view taken on line VV of FIG. 4 and looking upwardly; and r FIGS. 6 and 7 are respective side elevation and bottom views of a keying member employed with the invention.

Referring to thedrawings in detail, in FIG. 1 there is shown an axial flow, mnlti-stage steam turbine 10 having a tubular casing or shell structure, of substantially circular internal cross-sectional shape, divided into an upper half portion 11 and a lower half portion 12. along a central horizontal plane extending through-the longitudinal axis of the casing structure, and joined at suitable flanges by suitable bolts 13. Within the upper and lower halves .1 and 12, there its :ro-tatably supported a rotor M having a plurality of annular rows of blades (not shown).

As well known in the art, Itheturbine may be provided with a plurality of expansion stages, as desired. Each of the stages is divided by a bladed diaphragm structure 15 received within the casing structure 11, 12. As illustrated FIG. 2, the steam turbine contains four diaphragm structures, and thus is divided into four stages. The diaphragm structures 15 are of annularshape and include an outer ringstructure 16, an inner ring structure 17 disposed concentrically with the outer ring vided with a portion disposed normal to and projecting outwardly from the keyway and terminating beyond the periphery of the outer ring.

The inner wall of the casing half is provided with an annular groove adapted to receive the outer ring portion of the diaphragm half, and an internal borei extending partially through the casing is provided in the groove to receive the projecting portion of the key. The groove is of slightly larger radial extent than the outer ring, so that an annular clearance is attained for thermal expansion purposes during operation of the machine.

During assembly, after the diaphragm half has been placed in mating relation with the groove in the casing half and with the key projecting portion received in the bore, the diaphragm half is first vertically positioned with structure 16 about a central axis, and an annular array of nozzle blades 18 disposed therebetween, as well known in the art. I

For ease of manufacture and assembly, the diaphragm structures 15 areeach diametrically divided into an upper half portion 19 and lower half portion 20, thereby imparting a semicircular shape to each of the diaphragm in halves. This is attained by splitting the outer and

inner ring structures

16 and 17, respectively, into semicircular halves or portions. V

Th inner diaphragm ring 17 may furtherv be provided with adivided labyrinth seal ring structure 21 disposed in concentric but closely spaced relation with the rotor 14, thereby permittingrotation of the rotor but minimizing leakage of steam therepast from stage to stage. Accordingly, as shown in FIG. 1, there is provided an annular space 22 of very small width between the labyrinth ring 21 and therotor 14. Since the space 22 is of relative- 1y small Width, it is essential to' position the rotor 14 'in closely controlled concentric relation with the, diaphragm structures 15.

As illustrated in FIG. 1, the upper lower diaphragm halves 19 and 20 are disposed. in mutual abutment at their diametric edges 23 and 24, respectively,

' andm'aintained in keyed relation with each other by a diaphragm halves 20, corresponding to the lower casing an ennae half 12, are then positioned in the lower casing half 12,

in such a manner that their central axes are substantially coincident with the central axis of the casing structure.

To precisely space and position the diaphragms 15 along the longitudinal axis of the casing structure 11, 12, the upper and lower halves of the casing structure are provided with annular grooves 26 disposedin axially spaced relation with each other and parallel to a plane normal to the axis of the casing structure.

To permit thermal expansion of the diaphragms 15 Within the casing 11, 12 during operation, the diaphragms 15 are formed to a slightly smaller radial dimenslon than that of the grooves 26, thereby permitting the employment of an annular space 27 of small width be-' tween each of the diaphragm outer rings '16 and the inner surfaces of the associated grooves 26, as best shown in .FIGS. 3 and 4. Accordingly, to maintain the diaphragms 15 in centered relation with the turbine casmgstructure 11,12, the diaphragms must be supported agamst vertical movement in downward direction as well as horizontal movement.

with respect to the horizontal central plane by' suitable means beyond the scope of this invention. However;

During assembly, the lower half of the casing 12 is disposed in the position shown in FlGf '1 and thelower diaphragm half 20), with the key fitted in the keyway 29, is lowered into mating relation with the associated groove 26. At this time, the key 39 ,is preliminarily positioned in such a manner thatits projection 32 is re ceived in the bore 28, while the set screw 34is disposed out of locking engagement with the key Accordingly, the lower diaphragm half 20 isfreely movable, relative to the casing half '12 in a horizontal direction, normal to the central vertical plane.- The lowjer'diaphragm half 20 is then adjustably positioned until the spacing 27 between the periphery of the lower diaphragm half 20 and the groove 26 is substantially uniform throughout its extent. After this position is attained, the set -screw 34 is'ascrewed downwardly into tightly fitting engagement with the flange portion 31 ofthe'key, thereby ensuring' that the key 30will not inadvertently or otherwise be moved out of the position thus'attained.

Subsequent thereto, the lower diaphragm half 20 may be removed from the lower'casing half 12 and,-it' desired, the key 30 maybe more firmly and positively locked in the keyway 29 by a pair of pins 35 (see FIGS. 4 and 5 These pins 35 may be of the dowel type and driven into tight engagement with a pair of holes 36 drilled in the diaphragm ring 24.). To facilitate the drilling of the holes 36, the key 39 may be originally provided with a In actual practice, the "upper. and lower diaphragm halves 1a and 28 are positioned In accordance with the invention, each of the grooves 25 in the casing portions 11' and 12 is provided with an internal bore 28 disposed'in the wall of the casing and be described. The lower diaphragm half 20 correspond, 1 mg to the lower casing half 12 is provided with an el'ohpair of holes 37 to permit location of the holes 36. With the key 3t) thus firmly locked in its final position, the set f screw 34 may be removed, if desired, and the lower diaphragm half 24) is then refitted to the lower casing half 12.

In the same manner, all ofthe other diaphragm halves 19"and 20 may be positioned in the lower and upper its upper diaphragm halves 19 in proper assembly relation may be superimposed on the lower casing half 12,

and the entire structure joinedby the bolts 13 to comthe possibility of 'eccentricitybetween the rotor 14 and 'the. sealrin'gs 21 with-otherwise attendant excess leakga ted keyway 29, which keyway may be of T-shaped I cross 'section.(as best shown in 'FIGS. 2 and 3).; The keyway 29 extends in a chordwise manner along a chord line disposed in parallel relation with the diametric edge '24 of the lower diaphragm half 20 or; stated in. another 7 L portion 31 held captive in the keyway and a projecting portion 32 extending outwardly therefrom. The pro! jection 32, as best shown in FIGS 5 and '7, is desirably of square cross-section- The bore 2%, on theother hand, may be of elongated oblong shape; However, the bore 28 is of elongated shape'in' a direction parallel to the central longitudinal axis of the casing, so that the. key' projection32 is free to move therein in a direction parallel to this axis. to the axis of the easing, the projection 32. fits snugly fin the bore 28,, so that only a very small amount of play, in this direction; is attained. The-outer ring 16 tending into the keyway 29 (as best shown in FIG. 3). A'suitable 'set screw 34 is threadedly received'in the threaded opening33 fora purpose which will subsequently be described.

' ageof steam'and/or rubbing between the seal rings and the rotor. 7 V

With the above arrangement,- even though during manufacturing close dimensional tolerances in machining 'maynot be attained, the adjustable keying arrangement provided by the keyway 29 and the key 39 serves to overcome such variations in manufacture and permit precise positioningof the diaphragm structure 15 inthe casing structure. V g

While the invention has been shown in one form, it will be obvious to those 'skilled in the art that itis not so lirnited,*but is susceptible of various other changes However, in a direction normal 7 .70 may further be provided with a threaded opening 33 exand modifications without departing from the spirit there0f Y A Vie claim as our invention: v 1. An axial-flow elastic fluidutilizingimachme comprising a tubular casing structure having'a first central axis.

. an annulardiaphragm structure disposed in said cas- 7 ing structure and having a second central axis, said diaphragm structure being diametrically divided into upper and lower diaphragm half portions of substantially semicircular cross-sectional shape,

said upper and lower diaphragm half portions being associated with said upper and lower casing portions, respectively,

one of said diaphragm half portions having a semicircular outer ring portion disposed adjacent the internal wall of the associated casing portion,

the associated casing portion having a bore in its internal wall,

said ring having an elongated keyway extending chordwise therethrough,

a key member received in said keyway and slidable chordwise therein and having a portion projecting outwardly from said keyway into engagement with said bore, and

means carried by said ring portion for locking said key to said ring portion.

2. The structurerecited in claim 1 in which the one diaphragm half portion is of smaller radial extent than the wall portion of the associated casing half portion, and

said key member is etfective to maintain the second central axis in a vertical plane extending through the first central axis.

3. The structure recited in claim 1 in which the keyway extends along a chord line disposed substantially parallel to the horizontal plane, and

said key member is eflfective to maintain the second central axis in a vertical plane extending through the first central axis.

4. An axial-flow elastic fluid utilizing machine comprising a tubular casing structure axially divided into first and second casing half portions of substantially semicircular internal cross sectional shape,

an annular diaphragm structure received in said casing and diametrically divided into first and second diaphragm half portions of substantially semicircular cross-sectional shape,

said first and second diaphragm half portions being received in said first and second casing half portions, respectively,

said first casing half having a semicircular groove and 7 an internal bore communicating with said groove,

6 said ring portion having an elongated keyway extending chordwise therethrough, a key member slidably received in said keyway and slidable chordwise therein, said key member having a portion projecting transversely and outwardly from said keyway,

said projecting portion being disposed in mating relation with said bore and positioning said first diaphragm half in said first casing half, and

means for locking said key to said ring portion.

5. The structure recited in claim 4 in which said first and second diaphragm half portions have diametrically exgending edges disposed in abutment with each other, an

said keyway extends along a chord line disposed substantially parallel to said edges.

6. The structure recited in' claim 4 in which said keyway is disposed normal toa central plane bisecting said first diaphragm half, and

said key member is eiiective to prevent movement of said first diaphragm half in a direction normal to said central plane.

7. The structure recited in claim 1 in which the bore and the key member are so proportioned relative to each other that the key member is freely movable therein in a direction parallel to the central axis of the casing but restrained by the bore from horizontal movement transverse to the central ax1s.

8. The structure recited in claim 4 in which the bore is elongated in a direction parallel to the central axis of the casing structure, and

thetkey member is so proportioned with relation to the bore that the former is freely movable therein in said direction but restrained by the bore from move ment transverse to said direction.

References @ited in the file of this patent UNITED STATES PATENTS Matson Jan. 3,

Claims

1. AN AXIAL-FLOW ELASTIC FLUID UTILIZING MACHINE COMPRISING A TUBULAR CASING STRUCTURE HAVING A FIRST CENTRAL AXIS AND HAVING AN INTERNAL WALL PORTION OF SUBSTANTIALLY CIRCULAR CROSS-SECTIONAL SHAPE CONCENTRIC WITH SAID AXIS, SAID CASING STRUCTURE BEING AXIALLY DIVIDED ALONG A CENTRAL HORIZONTAL PLANE INTO UPPER AND LOWER CASING HALF PORTION, AN ANNULAR DIAPHRAGM STRUCTURE DISPOSED IN SAID CASING STRUCTURE AND HAVING A SECOND CENTRAL AXIS, SAID DIAPHRAGM STRUCTURE BEING DIAMETRICALLY DIVIDED INTO UPPER AND LOWER DIAPHRAGM HALF PORTIONS OF SUBSTANTIALLY SEMICIRCULAR CROSS-SECTIONAL SHAPE, SAID UPPER AND LOWER DIAPHRAGM HALF PORTIONS BEING ASSOCIATED WITH SAID UPPER AND LOWER CASING PORTIONS, RESPECTIVELY, ONE OF SAID DIAPHRAGH HALF PORTIONS HAVING A SEMICIRCULAR OUTER RING PORTION DISPOSED ADJACENT THE INTERNAL WALL OF THE ASSOCIATED CASING PORTION, THE ASSOCIATED CASING PORTION HAVING A BORE IN ITS INTERNAL WALL, SAID RING HAVING AN ELONGATED KEYWAY EXTENDING CHORDWISE THERETHROUGH, A KEY MEMBER RECEIVED IN SAID KEYWAY AND SALIDABLE CHORDWISE THEREIN AND HAVING A PORTION PROJECTING OUTWARDLY FROM SAID KEYWAY INTO ENGAGEMENT WITH SAID BORE, AND MEANS CARRIED BY SAID RING PORTION FOR LOCKING SAID KEY TO SAID RING PORTION.