US3163396A

US3163396A - Means for the discharge of liquid from rotors

Info

Publication number: US3163396A
Application number: US284559A
Authority: US
Inventors: Csillag Istvan
Original assignee: Associated Electrical Industries Ltd
Current assignee: Associated Electrical Industries Ltd
Priority date: 1962-06-20
Filing date: 1963-05-31
Publication date: 1964-12-29
Anticipated expiration: 1981-12-29
Also published as: CH413990A; GB1014812A

Description

Dec. 29, 1964 3,163,396

MEANS FOR THE DISCHARGE 0F LIQUID FROM ROTORS l. CSILLAG 2 Sheets-Sheet 1 Filed May 51, 1965 Dec. 29, 1964 l. CSILLAG MEANS FOR THE DISCHARGE OF LIQUID FROM ROTORS 2 Sheets-Sheet 2 Filed May 31, 1963 United States Patent 7 MEANS FOR THE DISCHARGE 0F LIQUID FROM ROTORS Istvan Csiliag, Sale, England, assignor to Associated Electrical Industries Limited, London, England, 'a British company V p Filed May 31, 1963, Ser. No. 284,559

Claims priority, application Great Britain, June 20, 19152,

23,783/ 62 7 Claims. (Cl. 253-3915) This invention relatesto improvements in means for the discharge of liquid from rotors, and more particularly to water discharge means for, the water cooled rotors of turbo-generators.

In a water cooled turbo-generator rotor, it is convenient to supply the cooling Water to the rotor axially through one end of, the, rotor, for example as'described in our copending patent application based on our United Kingdom Patent No. 971,507, applicants Associated Electrical Industries Limited, the cooling water then passing through passages or pipes in or on the rotor and being discharged from the rotor through radial or substantially radial ports in the rotor into a discharge chamber. 7

' It is found that, due to the centrifugal pumping action of the rotating rotor upon the water contained in the radial ports in the rotor, low pressure zones are produced in the passages in the rotor andcavitation is liable to occur and give rise to erosion.

..An object of the present invention is the provision of improved means for the discharge of liquid from rotors and of rotors provided with such improved means.

, Accordingto the present invention, means adapted to discharge liquid from a rotor comprise collecting chamber means in or on the rotor arranged to receive liquid to be discharged, ports extending outwardly from the chamber'means and-arranged when the rotor is stationary to discharge liquid from that'chamber into a receiving chamber surrounding the rotor and arranged not to rotate with the rotor, and a venturi nozzle disposed in one of the said ports and through which the liquid flows, the V throat of the venturi nozzle being provided with ports in communication with a source of gas, whereby when the rotor is rotating the gas is induced into the throat of the nozzle to reduce the density of the fluid fl'o'wirfg outwardly through the venturi nozzle and, when the speed of the rotor is sufliciently high to produce a sub-at mospheric pressure in the chamber means, to permit the outward flow of liquid through the venturi nozzle to cease and to permit the venturi nozzle to act as a gas inlet port to the collecting chamber means to reduce the degree of vacuum in the chamber means.

The invention will now be described, by way of example, v

with reference to the accompanying-drawings, in which:

FIGURE 1 is a sectional side elevation through a short end part of a turbo-generator rotor shaft and an end part of an extension shaft secured coaxially thereto; FIGURE 2 is a transverse sectional elevation taken on the line IIII of FIGURE 1; I

FIGURE 3 is a sectional side elevation of a venturi nozzle shown in FIGURE 1 but drawn to a larger scale than in that figure; and I 7 FIGURE 4 is a sectional plan view taken on the line IV-IV of FIGURE 2. V a f In FIGURE 1 the end of a turbine rotor shaft 1 has secured coaxially to it one end of a stainless steel extension shaft 3, the two shafts being formed with coaxial bores 5 and 7 respectively through which cooling water ICC are provided with an annular passage 15 through which cooling Water can flow in the directionvindicated by the arrows 19.

The extension shaft 3 is formed with an annular cham- Two diametrically opposite ports 23 are each provided with a venturinozzle. 33. "IEach of these two ports 23 is screw-threaded'throughout its length, and the nozzle 33 includes a main part 33A (see FIGURE 3).Which is externally screw-threaded and screwed in place, and a cap 33B having internally screw-threaded annular skirt 35 by which the'cap is mounted on a part of the main part 33A WhlCh lies inside the chamber 21. The main part 33A is formed with a bore of circular cross-section which diverges outwardly from the shaft axis. The cap 33B isformed with a bore of circular cross-'sectionwhich diverges. inwardly toward the shaft axis. The divergence of the bore in the cap 333 is greater than the divergence of the bore in the part 33A, and the two bores together form an outwardly directed venturi nozzle. The outer surface of the part 33A is formed with four equally spaced, axially'exte nding grooves. 37 and at its inward end part33A is formed With four radially extending grooves 39 which form extensions of the grooves 37.

When the venturi nozzle is assembled in position as shown in FIGURE 2, the

grooves

37 and 39 together form passages which extend between'the periphery of the shaft 3 and the throatnofthe venturi nozzle and through which air from outside the shaft 3 can be induced into the throat of the venturi nozzle. q r

When the rotor: shafts-1 and 3 are stationary, and cooling water is pumped through the rotor, flowing inwardly through the bores 7 and 5 and returning through the annular passage 15V to the chamber 21, the water flows from the chamber 21 outwardly through all six ofithe ports23 into' the, chamber 29.from whence it drainsaway through drainpipe v31. When the

rotor shafts

1 and 3 are rotating, the cooling water continues to flow in the manner described above, but centrifugal force acting on the water in each of the ports 23 produces an outwardly increasing pressure difference along the port. In the 'case of the four ports not provided with the venturi nozzles 33, this pressure difference increases with the speed of revolution of the rotor shaft, and could cause such a reduced pressure in the chamber 21 that cavitation could occur in the chamber 21 and in the passages leading to it.

However, in each of the ports 23 provided with the venturi nozzle 33 a reduced pressure is produced at the throat of the venturi nozzle, and air from the chamber 29 flows through holes 25, along grooves 37 and through grooves 39 into the throat of the venturi nozzle. This air is entrained by the outflowing water. The density of the fluid passing through the divergent outer part of the nozzle is therefore less than if the nozzle were filled with water, and as a result the pressure difference produced by the fluid in the nozzle is less. As the rotor speed increases 'still further, the increased suction in the chamber 21, in-

conjunction with the reducedpressure diflerence set up in the nozzle by the centrifugal force :as the fluid density decreases, causes the nozzle 33 to cease to discharge waterv and instead to act as an air inlet port for the flow of air Patented Dec 29, 1964 into the chamberZl and soreduce the degree of vacuum in that chamber.

In this manner the danger of cavitation, and the coninto the throat of the venturi nozzle towards the inner end of the member.

5. Liquid discharging means according to claim 4, in

which the elongated member is externally screw-threaded, the port into which it is fitted is formed with a complementary screw thread, and the member includes'a cap which has a skirt fitted ,onto'the radially, inner end of the ('0) portsin the rotor and extending outwa from.

the chamber means; V c (d) a stationary receiving chamber surrounding; the pant of the rotor providedwiththe ports andarranged' to receive liquid discharged from these ponts -when the rotor is stationary; f (e) means se'aling'the;liquid'in said'receiving chamber and permitting air to enter into said chamber; l

(f) a ventun'- nozzle having a convergent inlet'section: and a divergent outlet sectionand; a throat connecting these two parts, the nozzle being disposed in at least one of said'port's and arrangedlfor the through flow ofthe'liquidwhen the rotor is stationary; (g) passage means in the rotor through which air can flow when the rotor is rotating at a sufficiently high speed to break the flow of liquid through theventuri nozzle so that the nozzle is able thereafter to act as an air inlet po'rt for the radial'inflowof air to the collecting chamber means, thereby to reduce the degree of vacuum in the saidichamber means. 7

2. Liquid dischargingmeans according to claim 1:, in which the ports extend substantially radiallyfoustwardly from the collecting chamber means in= the rotor.

q 3. Liquiddischargingmeansaccording to claim 1, in which the collecting chamber means in the rotor are in the form of an annular chamber surrounding an inner chamber through which cooling liquid; can flow on its before passing to between the collecting chamberand the periphery of the rotor, and this elongated rnemb'eris formed with at least one axially extending external, groove opening, tothe atmosphere at the outer end of the member and opening screw threaded part, which" is'formed internally with'bne of the convergenfparts of the venturi nozzle, .aniwhich when in place forms-an axial boundaryto aipassage connecting'the external groove to:the throat ofthe venturi nozzle. 7 v

-6. Liquid discharging means according to claim 1, in which a coaxial cylindrical projection carried by the rotor is interleaved between coaxial cylindrical projections on the receiving chamber to provide a labyrinth seal;

7. A liquid cooled turbine rotor provided with liquid discharging means comprising:

(a) collecting chamber means arranged tofrotate' with the-rotor; v (b) liquid flow passages in the rotorarranged' to charge into the collecting chamber;

7 dis (c) ports in the rotor extending outwardlyfrom the chamber means;

(d) a stationary re'ceivin'g' chamber surrounding the part of the rotor'provided with'the ports and'a'rranged' to receive liquid dischargedifrom these ports when the rotor is stationary; V c

(e) means sealing" the liquid in said receiving chamber and permittin'gair. to enter into saidchamber; t

(f) a venturi' no'zzlehavin'g a convergent'inl'et' section andia divergent outlet section andathroaticonnect ing these two parts, the nozzle being disposed in at' least one of said ports and. arranged'for the througlr flow of the liquidlwhenthe' rotor isstationary; (g) passage meajnsin the rotor'throug'h which air can flow when the ,rot'o'ri's rotating'at' a sufijcient-ly high' speed-tobreak the flow of liquid throughthe venturi" nozzle so that the nozzle is able'thereafterto act as an air inlet port forthe radial inflow of air to' the, collecting chamber means, thereby to reduce thev degree of" vacuum in the said chamber means,

References Cited by the Examiner UNITED" STATES PATENTS 1,068,365 7/113 Rees 1 23o -10s: 2,646,208 "7/53 Layton- 230-108. JOSEPH H, BnA-NsoN, IR., Primary Exam e I

Claims

1. A ROTOR PROVIDED WITH MEANS ADAPTED TO DISCHARGE LIQUID FROM THE ROTOR AND COMPRISING: (A) COLLECTING CHAMBER MEANS ARRANGED TO ROTATE WITH THE ROTOR; (B) LIQUID FLOW PASSAGES IN THE ROTOR ARRANGED TO DISCHARGE INTO THE COLLECTING CHAMBER; (C) PORTS IN THE ROTOR AND EXTENDING OUTWARDLY FROM THE CHAMBER MEANS; (D) A STATIONARY RECEIVING CHAMBER SURROUNDING THE PART OF THE ROTOR PROVIDED WITH THE PORTS AND ARRANGED TO RECEIVE LIQUID DISCHARGED FROM THESE PORTS WHEN THE ROTOR IS STATIONARY; (E) MEANS SEALING THE LIQUID IN SAID RECEIVING CHAMBER AND PERMITTING AIR TO ENTER INTO SAID CHAMBER;