US 3531223 A
Description (OCR text may contain errors)
Sept. 29, 1970 J, H, DALTRY El'AL TURBO-'FEED PUMP ASSEMBLY Filed Jan. 28. 1969 \\\mmf United States Patent "ice 3,531,223 TURBO-FEED PUMP ASSEMBLY John Harold Daltry and Geoffrey Bernard Thomas, Rugby, England, assignors to The English Electric Company Limited, London England, a British company Filed Jan. 28, 1969, Ser. No. 794,490 Claims priority, application Great Britain, Jan. 31, 1968, 4,952/ 68 Int. Cl. F04d 13/02, 25/02 U.S. Cl. 417-409 7 Claims ABSTRACT F THE DISCLSURE This application is a copending application with our application Ser. No. 794,489, filed Jan. 28, 1969.
This invention relates to turbo-feed pump assemblies.
According to this invention, a turbo-feed pump assem- 'bly comprises an elongated casing providing an inlet and outlet passage for the turbine at or near one of its ends and a part of a suction and delivery passage for the feed pump towards its other end, said casing also having a bore formed therein which extends from the feed pump end thereof, a capsule adapted to be located in said bore, and a shaft common to the turbine and the feed pump rotatably mounted in the capsule, one end of the shaft having a turbine disc provided with at least one row of radially arranged axially extending blades which, when the capsule is located in the casing, extends into a space between the turbine inlet and outlet passages and aligns with at least one row of stator blades carried within said casing, said shaft also having at least one pump impeller which, when the capsule and shaft are in the located position, extends into the suction part of the feed pump passage, the arrangement 'being such that the capsule and shaft as a complete unit can be inserted into, or withdrawn from, the feed pump end of said casing.
In order that this invention may be readily understood, a turbo-feed pump assembly constructed in accordance therewith will now be described, by way of example, with reference to the accompanying drawing, which is a somewhat diagrammatic sectional view through the upper half of the assembly.
Referring to the drawing, the assembly comprises a turbine unit 1 and a feed pump unit 2. The casing 3 of the turbine unit is of annular form and has a steam inlet passage 4 which extends along an axial centre line through the assembly to an annular nozzle box 5 having a number of radially-directed nozzles 6 spaced therearound. The nozzles 6 direct steam through a two-stage velocity compounded radial turbine arrangement which comprises a row of stator `blades 7 disposed within and carried by the turbine casing 3, and two rows of rotor blades 8 carried by a turbine disc 9, said blades 7 and 8 extending axially with respect to the assembly. After passing through the turbine arrangement, the steam is fed through a dilfuser 11 into an annular exhaust chamber 12 which is provided with two exhaust ducts 13, said ducts being disposed directly opposite to each other.
The turbine casing 3 has a flange 14 which is bolted and spigoted solidly on to a mating flange 15 forming 3,531,223 Patented Sept. 29, 1970 part of an annular feed pump casing 16, thus ensuring alignment of the two units.
An axial bore extends throughout the feed pump casing 16, this bore being defined by the dotted line 17 and solid line 18 in the drawing, and is in alignment with a further bore 20 within the turbine casing 3. A capsule 19 is adapted to be inserted into these bores through an opening 21 in the outer end of the feed pump casing 16 and to be located therein by wedge members 22 and a split ring 23. The wedge members 22 act between the flange 15 of the feed pump casing and a slanted face 24 provided on the capsule 19. These wedge members ensure that no movement takes place between the capsule 19 and the turbine and feed pump casings 3 and 16 respectively and are held in place by suitable tie bolts (not shown). The split ring 23 is located in an annular groove 25 formed in the feed pump casing 16 adjacent the opening 21 and engages the outer end of the capsule 19.
The capsule 19 is a circular steel casing and includes an intermediate portion 26 of the suction passage for the feed pump. A shaft 27 extends through the capsule and is rotatably mounted in journal bearings 28, 29 and 29A, which are conveniently made of carbon impregnated with copper. This shaft carries two pump impellers 30 which extend into the intermediate portion 26 of the feed pump suction passage and a 'balance piston 30A, and the inner end of the shaft has the turbine disc 9 formed integrally therewith. That part of the capsule 19 which extends into the bore 20 within the turbine casing 3 is sealed by a pair of piston rings 31. The shaft 27 is maintained in position within the capsule 19 by a back stop bearing 32 which engages one face of a thrust ring 33, and the other face of said thrust ring has a thrust bearing 34 associated therewith. The thrust bearing, which conveniently also acts as a seal to prevent steam escaping into the chamber 43, is arranged with six cavities 35 spaced therearound and each of said cavities is fed with fluid which in this embodiment is water at high pressure via ducts 36 eX- tending through an annular 'bearing block 37 for the thrust bearing. Said high pressure fluid is fed to the ducts 36 from a source not shown, via pipes 38. This high pressure fluid leaks from the cavities 35, as shown by the arrows in the drawing, into an annular chamber 39 and thence to a return duct 41 by the action of a thrower 42 formed around the periphery of the thrust ring 33, and said iluid also leaks into a further annular chamber 43 via the mating surfaces of the shaft 27 and bearing 28, and thence into said intermediate portion 26 of the feed pump suction passage via the mating surfaces of said shaft and bearing 29, thereby providing for lubrication of said bearings 28 and 29. The bearing 'block 37 carrying the thrust bearing 34 is urged towards the thrust ring by a spring ring 44.
The ring 44 permits the thrust bearing 34, via the bearing block 37, to maintain a parallel relationship with the thrust ring 33 on the shaft 27. Thus, such an arrangement caters for any misalignment of the shaft which may occur during continued operation of the assembly, for example, due to distortion of the capsule 19.
As an alternative to providing for lubrication of the journal bearing 28 by fluid leaking from the cavities 3-5 of the thrust bearing 34, diuid under pressure may be fed directly to the bearing surface of said bearing, for example, by a branch duct leading from the duct 36, or by a separate duct provided with its own feed pipe 38. In such an arrangement any fluid which leaks from the thrust bearing 34 towards the journal bearing 28j and vice versa is conveniently collected in a space between the two bearings and drained into the annular chamber 43 by drainage ducts suitably formed in the bearing block 37.
Turning now to the feed pump unit 2, when the capsule J 19 is located in position within the assembly, the intermediate portion 26 of the suction passage aligns with an annular inlet chamber 45 for said suction passage and a discharge outlet 46, these latter being formed within the feed pump casing 16.
It will be appreciated that the capsule 19 may be readily dismantled from the assembly by disconnecting the supply pipes 38 from the capsule body, withdrawing the wedge members 22 from their wedging position, and by removing the split ring 23. This permits the complete capsule to be withdrawn from the turbine and feed pump casing through the opening 21, and since said capsule carries the rotor blades for the turbine, the thrust bearing arrangement and the majority of the working components for the feed pump, these parts are readily accessible for servicing.
In the embodiment described above, separate casings are provided for the turbine and feed pump units 1, 2 respectively. However, it will be appreciated that a turbofeed pump assembly in accordance with the invention may be formed as an integrated assembly and that a single casing may be employed to house these units.
In a modification of the embodiment described above, the back stop bearing 32 may be replaced by a further thrust bearing which is biased towards the thrust ring 33. lIn order to lubricate this further thrust bearing, a duct would be provided in the body of the capsule 19 leading from the feed pipe 38 to said further thrust ring.
1. A turbo-feed pump assembly comprising an elongated casing providing an inlet and outlet passage for the turbine at or near one of its ends and a part of a suction and delivery passage for the feed pump towards its other end, said casing also having a bore formed therein which extends from the feed pump end thereof, at least one row of stator blades within said casing, a capsule adapted to be located in said bore, a shaft common to the turbine and the feed pump rotatably mounted in the capsule, a turbine disc at one end of the shaft, at least one row of radially arranged axially extending blades provided on said turbine disc, which, when the capsule is located in the casing, extends into a space between the turbine inlet and outlet passages and aligns with said row of stator blades, and at least one pump impeller mounted on said shaft which, when the capsule and shaft are in their located position, extends into the suction part of the feed pump passage, the arrangement being such that the capsule and shaft as a complete unit can be inserted into, or withdrawn from, the feed pump end of said casing.
2. A turbo-feed pump assembly according to claim l, wherein the capsule has part of the suction part of the feed pump passage formed therein, into which the pump impeller extends.
3. A turbo-feed pump assembly according to claim 1, wherein the casing is in two parts comprising a turbine casing and a feed pump casing respectively, said casings being connected together via mating anges, said bore extends completely through the feed pump casing and partway through the turbine casing.
4. A turbo-feed pump assembly according to claim 3, wherein the capsule is held in its located position within the casings by wedge members acting between feed pump casing ange and a slanting face formed on the capsule.
5. A turbo-feed pump assembly according to claim 1, wherein the shaft has a thrust ring adjacent the turbine disc, and the capsule has an annular member which carries a thrust bearing ring for the thrust ring and a journal bearing for the shaft, the annular member being slidable on said capsule and being biased so that its thrust bearing is urged towards one side of the thrust ring.
6. A turbo-feed pump assembly according to claim 5, wherein means are provided for feeding lubricating fluid under pressure to the thrust bearing, and the journal bearing is arranged to be lubricated by fluid leaking from the bearing surface of said thrust bearing.
7. A turbo-feed pump assembly according to claim 6, wherein a further thrust bearing is located on the Other side of the thrust ring and is arranged to receive lubricating fluid under pressure from the fluid feeding means.
References Cited UNITED STATES PATENTS 6/1961 Wise 103-87 XR 8/1965 La Fleur 230-116 U.S. Cl. X.R. 415--105, 219