US3447320A

US3447320A - Condensing steam turbine plant

Info

Publication number: US3447320A
Application number: US692012A
Authority: US
Inventors: Keith Norman Hitchcock; Geoffrey Bernard Thomas; Henry Watson
Original assignee: English Electric Co Ltd
Current assignee: English Electric Co Ltd
Priority date: 1966-12-21
Filing date: 1967-12-20
Publication date: 1969-06-03
Anticipated expiration: 1986-06-03
Also published as: GB1171179A

Description

June 3, 1969 HWCHCOCK ETAL 3,447,320

CONDENSING STEAM TURBINE PLANT Filed Dec. 20. 1967 1 Sheet of 2 June 3, 1969 c ccc ETAL 3,447,320

CONDENSING STEAM TURBINE PLANT Sheet Filed Dec. 20, 1967 FIG.2

United States Patent 3,447,320 CONDENSING STEAM TURBINE PLANT Keith Norman Hitchcock, Geolfrey Bernard Thomas, and Henry Watson, Rugby, England, assignors to The English Electric Company Limited, London, England, a British company Filed Dec. 20, 1967, Ser. No. 692,012 Claims priority, application Great Britain, Dec. 21, 1966, 57,256/66 Int. Cl. F011: 19/00 US. CI. 60-95 8 Claims ABSTRACT OF THE DISCLOSURE The invention provides a radial condensing steam turbine plant in which the or each LP. turbine and its associated chamber housing the condensing means are separate from each other and are separately supported so as to permit relative movement to take place between them, and flexible bellows are provided at each end of the chamber, which bellows extend to and are sealed to the LP. turbine casing or its support structure, depending upon the positioning of the steam exhaust ports of said turbine, so as to enclose the chamber around its LP. turbine, the flexible bellows thus permitting said relative movement to take place.

This invention relates to condensing steam turbine plant of the kind having at least one low pressure (L.P.) turbine from which steam is to be exhausted and a chamber which encloses the LP. turbine, the chamber housing condenser means for the steam which are disposed around the LP. turbine casing.

Such plant is usually referred to as radial condensing steam turbine plant, and in such plant the LP. turbine and its associated chamber housing the condenser means are normally rigidly connected to each other and are provided with a single support structure.

According to the present invention, in condensing steam turbine plant of the kind referred to above, the LP. turbine and its associated chamber housing the condenser means are separate from each other and are separately supported so as to permit relative movement to take place between them, and flexible bellows are provided at each end of the chamber, which bellows extends to, and are sealed to a part of the LP. turbine casing or its support structure, depending upon the positioning of the steam exhaust ports of said turbine so as to provide an enclosed chamber around the LP. turbine casing for the exhaust steam.

In order that the invention may be readily understood, and further features made apparent, a radial condensing steam plant constructed in accordance with the invention will now be described, by way of example, with reference to the accompanying drawings in which:

FIGURE 1 is a diagrammatic part-sectional elevation of the low pressure stages of the plant, and

FIGURE 2 is a section on the line IIII of FIGURE 1.

Referring to the drawings, the LP. stages of the plant comprises three LP. turbines 1 from which steam is to be exhausted on a common shaft 2, suitable bearings 3 being provided for the turbines. An annular chamber 4 housing a plurality of condensers 5 is provided for each turbine 1, and the condensers are disposed radially around the casings of their respective turbines as shown in FIG- URE 2. The chambers 4 in this embodiment are interconnected and are separate from their associated turbines 1 and separately supported so that they may move relatively to their associated turbines. The support structure for the LP. turbines 1 comprises two main axial beams 3,447,320 Patented June 3, 1969 6 and 7 which extend completely through the low pressure stages on each side of the turbine casings, which beams are supported at the position of the bearings 3 by vertical girders 8 extending from the plant foundations and through spaces 30 between said interconnected chambers. Each turbine casing is provided with axially extending flanges 9 which seat on and are bolted to cooperating flanges 11 provided on the beams 6 and 7. Further support is given to the turbine by shallow substantially V shaped cross members 12 extending between the beams 6 and 7. The chambers 4 are supported by further vertical girders 13 which are arranged in pairs, one pair for each side of each chamber, and which connect at their upper ends to axially extending flanges 14 provided on the chamber casings. Deflector cones 15 carried by the turbine support structure are disposed adjacent the exhaust ports for the turbines '1 so as to deflect steam exhausted from the turbines into the chambers 4; in this embodiment the turbines are of the dual flow type, i.e. steam exhausts from both ends of the turbine casings, and therefore the cones 15 are disposed as shown in FIGURE 1. The outermost end walls of the interconnected chambers 4 are each sealed to

annular end walls

16 and 17 respectively, which form part of the turbine support structure, by an annular tubular flexible bellows 18, and further bellows 31 are provided between the turbine support structure and chambers 4, so as to seal said chambers from atmosphere and yet permit relative movement between the LP. turbines 1 and their associated chambers 4 to take place. It will be seen from FIGURE 1 that the bellows 31 are provided at the points where the deflector cones 15 are attached to the turbine structure, and that conveniently the bellows are extended around the pperipheries of these cones to permit relative movement to take place between them and the inner walls of the interconnected chambers. The bellows referred to above may, for example, form part of the bellows arrangement described in our co-pending patent application filed Dec. 20, 1967, Ser. No. 692,116.

In this embodiment the main steam duct 19 from the intermediate stages of the plant is conveniently situated beneath the chambers 4 and feeds each turbine 1 vertically through a branch duct 2-1, which latter passes through a recess 22 formed in the underside of the associated chamber 4, and further bellows 32, which may be similar to the

bellows

18 and 31, are provided between these recesses and the turbine casings.

Where the main steam duct 19 is situated below the chambers 4 as described above, an unbalanced thrust would normally arise due to the ducts 21 passing from atmosphere to the LP. turbines 1, and this could lead to undesirable changes in turbine alignment taking place. A feature of this invention lies in the provision of a thrust balancing arrangement generally denoted 23, for each duct 21. Thus, each thrust balancing arrangement comprises essentially two spaced

plates

24 and 25 which are connected to each other by a bellows 26 to provide a sealed space 27. The plate 24 is attached to the underside of the main duct 19 opposite to duct 21 and the plate 25 is, anchored to the associated chamber casing, or, as in this case, to the ground by a suitable tie bar 28. A small bore pipe 29 is then connected between the space 27 and the inside of the associated chamber 4, and thus this pipe ensures that whatever state of pressure is present within the chamber 4 is also present in the space 27 and hence a balance of pressure thrust is achieved.

It will be appreciated that the construction described above provides an alternative to the known constructions of radial condensing steam turbine plant referred to hereinbefore in which the turbine part of the plant is rigidly connected to the condenser part of the plant, and has the following advantages over the said known constructions:

(a) The turbine part of the plant could be erected totally independently of the condenser part of the plant.

(b) 'The condenser part of the plant would not require stress relieving, since it cannot affect the alignment of the turbine part of the plant,

' (c)' The condensers could be completely tubed in the factory.

(d) The complete plant may be conveniently fabricated in sections which are small enough to make export of this type of plant a very practical proposition.

(e) Thermal distortions of the condenser part of the plant cannot aflect critical turbine clearance, hence there is no real necessity for a symmetrical arrangement of the condensers.

(f) Out-of-balance forces cannot be transmitted to the condenser part of the plant, thus enabling the condenser part of the plant to be more highly stressed.

(g) The plant is much more amenable to dynamic analysis, as it consists of two completely separate parts.

We claim:

1. Condensing steam turbine plant of the kind having at least one low pressure (L.P.) turbine from which steam is to be exhausted and a chamber which encloses the LP. turbine, the chamber housing condenser means for the steam which are disposed around the LP. turbine casing, wherein the improvement comprises an associated chamber which is separate from its L.P. turbine, a support structure for said LP. turbine, a separate support structure for said associated chamber, the arrangement thus permitting relative movement to take place between said associated chamber and said L.P. turbine, and flexible bellows extending between the chamber and the LP. turbine so as to provide a sealed chamber around the LP. turbine casing and to allow said relative movement to take place between said associated chamber and said LP. turbine.

2. Condensing steam turbine plant according to claim 1, and in which a plurality of LP. turbines and associated chambers are provided in series, wherein said chambers are interconnected with each other.

3. Condensing steam turbine plant according to claim 2, wherein the LP. turbines are supported by a single support structure, and said support structure includes two main axial beams which extend along the length of the series-connected turbines andwhich are disposed one at each side of the turbine casings, co-operating axially extending flanges provided on the turbine casings and said axial beams, and a number of vertical girders which extend from the plant foundations to the axial beams via spaces between said interconnected chambers, flexible bellows being provided within said spaces between the chambers and the LP. turbines to provide for sealing of the chambers and said relative movement.

4. Condensing steam turbine plant according to claim 3, wherein the support structure further includes shallow V-shaped cross-members extending between the beams.

5. Condensing steam turbine plant according to claim 3, wherein the support structure for the chambers comprises vertical girders disposed on each side of each chamber which extend from the plant foundations and connect at their upper ends to axially extending flanges provided on the chamber casings.

6. Condensing steam turbine plant according to claim 5, wherein each LP. turbine is of the dual-flow type, each associated chamber is of annular form surrounding its respective L.P. turbine, and a deflector cone is provided on each end wall of each chamber, each deflector cone being arranged to deflect steam exhausted from tis respective L.P. turbine exhaust towards the condenser means.

7. Condensing steam plant according to claim 6, wherein the deflector cones are carried by the turbine support structure, and the flexible bellows extend between the peripheries of said cones and the wall of their respective chambers.

8. Condensing steam turbine plant according to claim 7, wherein all the flexible bellows are each of tubular form and form part of the bellows arrangement.

References Cited UNITED STATES PATENTS 1,781,107 11/1930 Grace. 1,781,108 11/1930 Grace.

MARTIN P. SCHWADRON, Primary Examiner.

R. R. BUNEVICH, Assistant Examiner.