US2651495A

US2651495A - Turbine inlet structure

Info

Publication number: US2651495A
Application number: US57940A
Authority: US
Inventors: Francis P Corbett
Original assignee: Westinghouse Electric Corp
Current assignee: CBS Corp
Priority date: 1948-11-02
Filing date: 1948-11-02
Publication date: 1953-09-08
Anticipated expiration: 1970-09-08

Description

Sept. 8, 1953 F. P. coRBETT TURBINE INLET STRUCTURE Filed Nv- 2. 1948 INVENToR'. FRANC/s Roo/MUT BY t ATTORNEY wwwwwwh Patented Sept. 8, 1953 UNITEDY STATES PATENT OFFICE TURBIN E INLET STRUCTURE Francis P. Corbett, Drexel Hill, Pa., assignor to Westinghouse Electric Corporation, East Pittsburgh, Pa., a corporation of Pennsylvania Application November 2, 1948, Serial No. 57,940

3 Claims. l

The invention relates to the expansion joint between adjacent nozzle blocks and it has for an object to provide apparatus wher-ein the joint is formed by clearance between component parts of a composite nozzle vane separating adjacent nozzle passages of adjoining nozzle blocks and which clearance space is sealed off from the nozzle chambers and opens into one of the adjacent nozzle passages through the convex face of the composite vane and into such nozzle passage at the downstream side of the throat of the latter.

A further object of the invention is to form the nozzle block discharge side edges of the clearance substantially in the same plane normal to the turbine axis, whereby decrease in the clearance for any reason, such as expansion, will not result in increased interference with proper steam flow in the nozzle passage with which the clearance communicates.

The foregoing and other objects are effected by my invention as will be apparent from the following descr-iption and claims taken in connection with the accompanying drawings, forming a part of this application, in which:

Figure 1 is a transverse sectional view of a turbine having nozzle boxesin connection with which the invention is applied;

Figure 2 is a sectional View taken along the line II--II of Figure 1;

Figure 3 is a developed sectional view'showing adjacent nozzle blocks and the clearance spaces separating adjoining ends thereof; and

Figure 4 is a fragmentary detail and enlarged sectional view, similar to Fig. 3, showing in greater detail a composite Vane with structure for connecting the components to adjacent nozzle boxes and the structure and components arranged to provide a separating expansion clearance space.

In the drawing, there is shown a plurality of nozzle boxes I0 supplied with steam which undergoes expansion in the nozzle passages II and Ila and then is delivered for action on' impulse blading comprising, for example, rst and second rows of blades I2 and I4 carried by the rotor I5 and a row of stationary and reversing blades I6 carried by the cylinder or stator I1.

Each nozzle box I9 includes wall structure I8 bounding a steam chamber I 9 and a nozzle block 20 attached to the wall structure and formed so that steam can issue from the chamber only through the nozzle passages.

Each nozzle block 20 is joined to the nozzle box by a spacing or bridging structure 22 con- 2 nected by bolts 24 to the nozzle chamber wall structure I9.

The nozzle blocks include vanes 25 and 25a defining nozzle passages II and IIa, each vane 25a separating adjacent nozzle passages II and I la and being comprised by component parts 2l and 28 separated by the clearance space 29 and which are joined to adjacent end walls 3l and 32 of the bridging structure 22 and which end walls have a clearance space 33 therebetween and registering with the clearance space 29..

The clearance 29 extends rearwardly and circumferentially in the general direction in which the nozzle passages extend, it having a forward portion 34 in an axial plane of the turbine and a rearward portion 35 which extends rearwardly and obliquely to provide a rearward end 36 opening through the convex face of the composite vane into the nozzle passage IIa at the downstream side of the throat 3l thereof.

As the forward edges of the component parts 2l and 28 of each composite vane are sealed with respect to adjoining ends of adjacent bridge structure, no leakage of steam can occur from the latter to the clearance space between the components. Formation of the clearance space between vane components so as to extend generally in the same direction as the vane provides for opening of the clearance space through the convex face of the composite vane at the downstream side of the throat of the nozzle passage partially bound by such convex face, whereby bypassing or loss of steam from a nozzle passage is avoided; and, since the clearance space does not extend across a vane, loss of steam from one nozzle passage at one side of the Vaneto the nozzle passage at the other side of the vane and disturbance with ow through the nozzle passages is avoided.

As shown in Fig. 4, the clearance 29 opens through the convex face of the composite vane 25aI into the nozzle passage I la at 36 at the downstream side of the throat, whereby communication of such clearance is had with the nozzle passage only after full expansion of steam in the latter. The clearance space or passage end is defined by a rearward edge 40 of the component 21 which is opposite to the edge 4I of the other component, such edges being located in the same plane normal to the turbine axis. Rearwardly of the edge 4I, the vane component 28 has a surface slanting rearwardly to complete the vane prole. As the edges 40 and 4I are in the same plane normal to the turbine axisVitI will be apparent that expansion of the nozzle blocks, with diminution in the thickness of the clearance space 25, may occur without the rearward edge presenting a shoulder or obstruction interfering with proper flow of steam through the nozzle.

From the foregoing, it will be apparent that I have provided an arrangement of nozzle boxes wherein provision is made for expansion incident to handling steam at high temperatures and pressures and wherein composite vanes separate the nozzle passages at adjacent endsloxadjoining nozzle blocks with the components of the compo; site vane providing clearance space accommodating expansion and wherein the components oi the composite vane are sealed off with respect to the associated nozzle boxes, thereby conning the discharge of steam from each nozzle box to the nozzle passages of its nozzle block, the components of each composite vane being formed to provide a clearance space which extends genere ally in the same direction as the vane so as to open throughrthe convex face of the latter at the downstream side of the nozzle passage partially bound by such convex face. The clearance accommodating for expansion, therefore, does not extend across a vane and it does not impair nozzle efciency. Byy having the clearance open into the nozzle passage at the downstream side of the throat of the latter, it is assured that suoli passage does not impair nozzle efficiency nor in any way interfere with full flow of steam through the throat. v

What I claim is: n

1. In a turbine provided with impulse blading at its high-pressure end, a circumferential arrangement of nozzle boxes each having wall structure bounding a steam chamber, bridging structures secured to the respective wall structure of said nozzle boxes, nozzle blocks carried by said bridging structures for the respective nozzle boxes and including vanes providing nozzle passages ior supplying steam from the nozzle boxes to the blading, each such nozzle passage including a throat where critical pressure drop occurs, the vane separating the nozzle passage Vat one end of one nozzle block from the nozzle passage at the adjacent endof the adjoining nozzle block including vane-forming components carried by the respective blocks and separated by a clearance space, said bridging structures for supporting the respective nozzle blocks being connected to the wall structures of the respective nozzle boxes so that discharge of steam from each nozzle box is restricted to the nozzle passages of the associated block, said bridging structures including adjoining end wall elements welded to the forward edges of said vane components and separated by a clearance space registering with the clearance space between the vane components, said vane components being formed so that the clearance space therebetween extends generally in the same direction as the nozzle passages with one end thereof opening through the composite vane convex face downstream of the throat of the nozzle passage partially bound by such convex face.

2. The combination as claimed in claim 1 wherein the clearance space between the components of each composite vaneincludes a forward portion extending in an axial plane of the turbine and a rearward portion which extends obliquelyfrom the forward portion to provide for opening thereof into the nozzle passage downstream @une ,threat-,

3. In a steam turbine, an arrangement of nozzlc boxes disposed fcircumferentially relative to the turbineA axis; bridging structures secured to said nozzle boxes, respectively; nozzle blocks carried by said bridging structures for the respective nozzle boxes including spaced curved -vanes forming nozzle passages having throat portions constituting th points of critical pressure drop of the steam expanding in said nozzle passages, each of said vanes having a convex face and a concave face joiningto form the downstream edge of the vane, such downstream edges of the vanes' being disposed at the throat portions with relation to the convex faces of the adjacent vanes, respectively; said nozzle blocks having adjoining ends each carrying a vane component complementary to the vane component of the adjacent 'nozzle block for providing a composite vane; each pair of said vane components beingseparated by a clearance spacel to allow for thermal expansion and being formed so that such clearance space extends generally in the same direction as said nozzle passages, withA one end of the clearance space opening through the v'oo r'nposite vane convex face downstream of thethroat portion of the nozzle passage partially bound by such convex face, for preventing expansion of high pressure steam into each clearance space; said one end of each clearance space being defined between clearance space edges of the anking vane components, said clearance space edges being aligned in a plane substantially normal to the turbine axis, whereby uninterrupted flow of steam from said nozzle passages is maintained at a constant angle without interference with said clearance space edges.

FRANCIS P. CORBET'I.

References cited in oneY me of this patent UNITED STATES PATENTS Number V Name Date A 2,391,786 Kenny Dec. 25, 1945 2,527,445 Pentheny Oct. 24, 19,50 2,527,446 Jenks Oct. 24, 1950 FOREIGN PATENTS Number. Country Date 439,905 Germany Jan. 22, 1927