US1941361A - Air inlet control and method of operating a pump-turbine - Google Patents

Description

Dec. 26, 1933. l.. F. MOODY I,941,361

AIR INLET CONTROL AND METHOD OF OPERATING A PUMP TURBINE Filed MaICh 14, 1931 n- Illlll llllllllllllllllI Patented Dec. 1933 Perser @FFI-CE i lluNl'lso STATES This invention relates to hydraulic machines and particularly to an improved method of op- -eration of machines of the reversible pump-turbine type in changing from turbine to pump? operation and vice versa, andincludes improved air control mechanism for use in carrying outthis method as well as for use in hydraulic machines "such as turbines or pumps in general. Y

In the operation of hydraulic turbines it is often desirable tounwate/r the rotor to permit driving the machine with minimum friction losses. For instance, when a turbine-generator unit operates as a synchronous condenser the tur'- bine gates are closed andthevacuum'in the draft tube broken by admission of air thereto so as to unwater the runner, thereby allowing the runner-to rotatefreely in the air. The admission of this air is effected usually automatically in accordance with the gate position. In the case of reversible pump-turbines, or of ,pumps alone Y Lsometimesfit is desirable tocontrol air admission for the purpose of priming the pump or-'to insure 3 stability and smoothness of operation. The

automatic air control equipment heretofore used .od for changing from turbine to. pump operayfor turbines alone doesY not havethat degree of vflexibility of operation to renderrit efficienter entirely adapted for both turbine andpump operations. y

Hence it is one object ofA my invention to provide an air control mechanism'having an improved arrangement of elements so constructed and coordinated in their functions thatthe desired ldegree and timing of air control may be had for either turbine, pump or reversible pump-turbine units. l Y A further object is to provide an improved arrangement whereby-the Ausual automatic air control may be had for turbine operation'but with an improved control adapted to supplement the automatic control either by acting as anadjustment of the automatic control or-of effecting air control independently of the position of the Vautomatic control. Another and more specific object of the invention in this respect'is to have the cooperating control subject to manual operation p and preferablyV `operable independentlyV of the .automatic control such, for instance, vas not being movable upon operation of the automatic control and vice versa.

A still further specific object is to provide an improved air valve mechanism wherein the valve seat and cooperating valve member are each movable not only with respect to the valve casing but also with respect to each other.

fcompressed air.

A further object is to provide an improved air l admission control Afor a reversible pump-turbine so'that the hand operation of the air valve `may beused in starting and synchronizing rthe vunit when operating as a pump whereby the machine may be startedand-synchronized with the runner revolving in air and with the" guide vanes closed,

after which the air'inl'et may be closedv by hand and the runner space be allowed to ll with water. For low settings of the' runner, below tailwater level,y compressedair maybe connected to the air 'valve and the water forced vout of the runner space, with a second, hand operated, valve to relieve the air pressure after starting; or the compressed. air may be admitted .through-a.` second valve-with Athev air vent-valve Vas-shown herein used for relief after starting, thelatter being usually the preferable arrangement.

A further and more specific object of my invention Ais to provide a valve seat adjustably rotatable so that the gate position for closure or opening of the air valve may be deiinitely'adjusted by ahand wheel or if desired' adjusted by a motor operate through afremotecontrol. N v an improved meth- Another object is tol provide tion or vice versa.

Other objects and-advantagesnwill parent to those'skilled in the-art from the following description Vof the accompanying'drawing flFig. l is apartial plan view of'my improved yarranger'nent applied to a turbineof either the Francis or 'high speciicspeed propeller: types its .operating mechanism and lpart `of a Francis turbine; and I Fig. 3 is a partial plan view`of the valve and the operating gear.` y

Fig. 4 is a fragmentaryvertical section of'v a modified form of the valve adapted for'fthe use of The invention as speciiically illustratedvherein lmay beapplied to diiferenttypes of turbines, such asthe Francis or rhigh speciiic speed types, by'jhaving the adjustable gate mechanism operatively connected with my improved arrangement whereby an air adnfiissionvr valve may be "controlled 'either automatically in accordance be more .ap-

be clear from one specic form of the invention described herein where wicket gates 1 are indicated in dotted lines and operated through usual gate arms 2 pivotally connected to connecting links 3 which in turn are pivotally connected to and actuated by a usual shifting ring 4. This ring and the adjustable or wicket gates 1 are disposed, as is well known, concentrically to the axis of runner R.V Any suitable power means such as a piston and cylinder motor, connected to a pivot 5 of the shifting ring, may be employed to oscillate the shifting ring to adjust the wicket gates to their open or closed positions. It is seen that either the movement or position of shifting ring 4 represents the movement or position of the wicket gates. Hence in the broader aspect of the invention the shifting ring, adjustable guide vanes and any associated linkages may be considered as gate or iiow control mechanism. The shifting ring and associated linkages are as shown in Fig. 2 disposed above the usual turbine head cover 6.

To admit airwithin the runner passage P, preferably directly to the draft tube as through suitable openings in the head cover or runner,

an inlet 7 provided with a ball-check valve is have an axial flange 13 partially encircling the' seat 11 so as not only to increase the effectiveness against leakage but also prevent dirt or other foreign matter gaining access to the sliding surfaces. The seat has a series of openings 14 Aangularlyspaced so as to provide alternate closed portions 15 of substantially similar extent to the openings. A portion of the periphery of this seat is provided with a gear segment 11a which meshes with a hand wheel operated pinion 11b, the hand wheel pinion being carried by basev 9. The gear ratio is preferably such as to cause upon one revolution of the hand wheel an angular displacement of seat 11 substantially equal to the angular extent of the openings 14.

Also rotatably supported on stud 12 is a movable valve element 16 having openings l7'adapted to register with the openings `14. Openings 1'7 likewise are angularly spaced so as to have closed portions therebetween whereby the openings 14 may be covered when desired.

An arm 18 normally xed to the hub of valve 16 by a set screw 18a but adapted to be freely rotatable thereon upon loosening of the set screw,

carries a roller 19 disposed within a slot 20 which is formed in a plate 21, this in turn being secured preferably to the inside of the shifting ring 4 as by bolts 22. As seen in Fig. l the cam slot 20 has a substantial arcuate portion concentric to the axis of the shifting ring 4 and a small oirset portion 23. By loosening the set screw acomplete independence is had between the two controls.

In turbine operation it is desired to open the air admission valve when the gate mechanism is in closed position. In this case the openings in both the valve seat and movable valve element 16 are in register which has been effected due to roller 19 having engaged the surface of oiset cam slot 23, this cam surface having been moved into engagement with the roller when the shifting ring 4 was moved to closing position by the gate operating servo-motor. With the air valve thus open the draft tube will be vented and the turbine allowed to rotate freely in air. When the gates open to a predetermined position, determined by the length of the arcuate slot 20, the air valve will close. The arcuate slot thusl delays closing of the air valve so that air is admitted to thedraft tube during initial part-gate operation oi the turbine, this being desirable.

1f the hydraulic machine is a reversible pumpturbine and itis desired to change its operation from turbinel to pump, the machine will be brought to a stop and the generator operated as a motor in the reverse direction, it being understood that the runner preferably has fixed blades or at least blades which are not adjustable past each other, thus necessitating reverse direction of runner rotation for pump operation. With the machine now running in the reverse direction for pump operation and with the gates still closed and the vent open, the pump is primed by first closing the air control valve, this being possible in my improved arrangement' notwithstanding that the gate mechanism is inclosed position and the arm 18 is held against movement by roller 19 being in engagementwith the offset cam slot 23. The valve is closed merely by rotating the hand wheel operated pinion 11b, .thereby shifting the valve seat 11 relative to the other valve element 16 untilthe openings 17 of the latter are closed. Any suitable mechanism may now be employed to prime the pump either by an injector or other usuall arrangements. After the pump is primed the gates are opened so kas to permit pump discharge therethrough.` VI-f, during opening ofthe gates, the valve element 16 is actuated by the cam so astotend to open the air inlet then the hand wheel-'control may again be superimposed on the action of the automatic control so as to maintain the valve closed. If for any reason during pump operation it should be desired in order to establish stability or smoothness of operation, the air control valve may be opened to any desired extent.

1t is thus seen that 1 have provided a very simple arrangement of parts whereby air control may be obtained for either pump or turbine operation by f' employing elements which are common to both operations, thus providing a structure which is economical in initial cost of construction and of maintenance in addition to having a wide range of flexibility as is necessary in a reversible pumpturbine machine. It is also to be noted that in the specic valve shown one valve element acts as-a seat while the other is themovablevalve element and vice versa.

In some cases it may provide means for holding the air valve. closed independently ofthe action of the gate operating mechanism and cam, to use the stationary disk 9a instead of just radial arms. The disk has openings registering with those in the movable seat 11 so that when the seat 11 is rotated by the handwheel so as to place the openings in 11 above and in line with those -in9a, the openings will be controlled entirely by the operating mechanism and cam acting upon the valve disk 17. rWhen the seat 11 is rotated so that its closed vportions cover the openings in 9a, the valve remains closed independently of the motion of the valve disk 17 and of the turbine gates, Also, if seat 11 is adjusted to give a certain maximum opening then this can never be desirable, in order to Y described.

be made larger by the movement of valve l'l a1- through it might be made smaller thereby. If instead of using a disk 9a, radial Supporting arms are provided so as to have an opening over lthe Whole area then the operation is as previously In the Fig. 4 modication' al suitable cover 25 encloses the valve mechanism and operating gear, whereby compressed air may be supplied from any source through an inlet 26. In this figure is also shown a means of remote control by the use of an electric motor-'27 geared tothe valve spindle, and having a sliding pinion r28 for disengaging the motor drive to permit manual operation by the handwheel Whendesired. It Will be understood that a similar remote control device can'be applied to the other-forms of valve illustrated,

so that it is unnecessary to repeat this portion of Fig. 4 in the other figures as its applicationV to them will be obvious.

In the case of propeller turbines having adjustable runner blades' such as is shown, 'for'examplf-z, in my copending application, Serial No. 33,940, it is also possible, and may in some cases be desirable, to have the air admission valve actuated or controlled oy the runner blade'position rather than by the guide vane position. In describing the air valve as being controlled by the adjustable gate mechanism I therefore intend to include itsl control by runner blade adjustment since such runner blade adjustment has the effect of con-` trolling the ow and-may be considered to supplement or replace the control by the guide vane adjustment, being in the nature of a gate mechanism in which the runner blades perform the additional function of gates While in motion with the remainder of the runner. vAdjustable runner blades may be used as the sole flow control means n `It will of course be understood that various changesmay be Ymade in the construction, ar-I rangement and operationof parts and of the device as a whole, Without departing from' the spirit of my invention as set forth in the appended claims.

I claim: f y

1.`A hydraulic machine comprising, in combination, a runner, a passage therefor, adjustable gate mechanism for .controlling the iloW through said passage, an air inlet for said passage, means for controlling said air inlet automatically in accordance with a predetermined gate position, and means for additionally controlling the admission of air to said passage notwithstanding that the gate mechanism is in said predetermined position and having yprovision for determining the maximum extent of automatic air admission and of v limiting the same if desired.

2. A hydraulic machine comprising, in combination, a'runner, a passage therefor, adjustable gate mechanism having actuating means, an in- `1et through which air is admitted to said runner passage, a valve mechanism for said inlet, operating connections between said gate and inlet valve mechanism whereby the valve mechanism is adjusted automatically in accordance withthe gate operation, and means for additionally controlling said air inlet while said operating connections remain in normal operative condition and having provision for limiting the maximum extent of automatic air admission. y

LEWIS YFERRY MOODY.

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