US1789861A

US1789861A - Controlling means for turbines

Info

Publication number: US1789861A
Application number: US312767A
Authority: US
Inventors: Birmann Rudolph
Original assignee: Laval Steam Turbine Co
Current assignee: De Laval Steam Turbine Co
Priority date: 1928-10-16
Filing date: 1928-10-16
Publication date: 1931-01-20
Anticipated expiration: 1948-01-20
Also published as: US1832445A

Description

Jan. 20, 1931. R, BIRMANN 1,789,861

CONTROLLING MEANS FOR TURBINES Filed Oct. 16, 1928 Sheets-Sheet 1 I I I.

H 1 I 1 1 II zrrm/vfr Jan. 20, '1931.

R. BIRMANN 1,789,861 CONTROLLING MEANS FOR TURBINES Filed Oct. 16, 1928 1 4 Sheets-Sheet 2 Jan 20, 1931 R. BIRMANN 1,789,861 CONTROLLING MEANS FOR TVURBINES Filed Oct. 16, 1928 4 Sheets-Sheet 3 WM 5 8y I AI'I'OIPAEZ 6.

' R. BIRMANN CONTROLLING MEANS FOR TURBINES Jan. '20, 1931.

Filed Oct. 16, 1928 4 Sheets-Sheet 4 Patented Jan. 20, 1931 TUNITED STVATEST- PATENT OFFICE.

RUDOLPH BIBMANN, OF TRENTON, NEW JERSEY, ,ASSIGNOB T DE LAVMJ STEAM TURBINE COMPANY, OF TRENTON, NEW JERSEY, A CORPORATION OF NEW JERSEY CONTROLLING MEANS FOR TUBBINES Application filed October 16, 1928- Serial No. 312,767. r

This invention relates to a boiler feed Fig. 8 is a section through the steam nozzle pump particularly adapted to locomotives and governing means therefor. and controllable from the cab thereof. More The casing in which the operating parts specifically, it refers to a turbinedriven 1111- are enclosed is designated generally by impeller adapted to impart to feed water the moral 2- and consists of three chambers, pressure necessary to feed the boiler. \Vh1le namely. an oil chamber 4, a turbine chamber various improvements are described with (3, and an impeller chamber. 8. The body porreference to a feed pump of this character tionsof these chambers are preferably formed their broader application to turbines in genas a single casting,

chambers

4 and 8 being 1 eral,'or other machines, will'be obvious. providedhwith top covers and chamber 6 Heretofore turbines have been provided being provided with an end cover carrying with means in the throats of their nozzles for the steam nozzle. properly relating the throat area and expau- Shaft 10 on which the turbine and impeller sion ratio, the means employed being fixed wheels are mounted, is carried in split bearand governing being accomplished by a valve mgs 12 and 14 within the oil chamber, these in the steam line. bearings being provided with suitable oil One object of the present invention is, acgrooves supplied with oil under pressure in cordingly, the provision of means which a manner described below. Rings 16 on shaft may be used not only for regulating the 10 engage the ends of bearing 12 preventing flow through the nozzle to obtain n'laximum excessive endwise play ofthe shaft while per-. efficiency but also for governing thus elinumltting a slight movement to allow balance nating losses due to throttling in the ord1- of the parts at the impellerin a manner to be nary governing valve. described.

A further object relates to an emergency I Secured on one end of shaft 10 within t i ping mechanism adapted to stop the t urchamber 6 is a. wheel 18 provided with blades bine and more particularly to a tripping 20 ofthe usual type, receiving steam through mechanism particularly adapted to close the nozzle 22. A reentry nozzle 24 is carried by valve referred to above. The provisions of 'the casing to redirect steam through the means for effecting such tripping both manblades and exhaust 26. A suitable packing, ually, upon diminution of the oil supply and not shown in detail, is of course used to preat excessive speed, form more specific objects vent escape of steam Where the shaft passes of the invention. through the casing wall. It will be noted Another object is the provision of a. comthat a space 27 open to the atmosphere is bi d il gauge d t i i d i provided between

chambers

4 and 6 to min- Further objects relating to improvements ag of 'g l Q the Oil chamben 85 of specific portions of the mechanism'will be Sultable 011' wnefit'lng rings are Provlded 011 apparent from the following description read i gi lgsg g g'i l leaveis chamber 4 to P 1 y 4 1 mumtlon Wlth the accompapymb Threaded on the end of the shaft opposite the turbine is an impeller wheel 28 the hub of 90 the s; which is rotatable within packing 30 held in 1g. 1 1s a plan view of the pump, a r F 2 f t 1 Y th place by a suitable gland. The impeller le- Ton ere) h wheel draws water through a supply conduit g- 3 1S Vertlcal Sectlon through t e 32' into passages 34 and discharges through mam shaft; diffusing ring 36 into volute 38 communicato5 v v Fig. 4 1s an elevatlon of the adplstable i ith th it 4() Th diff i i g lealr-ofi' ring; which is held stationary in the casing, has an F g. 5 1s a sect on on lme5-5 of Fig 3; inwardly extending annular flange 42 form- Fig. 1s a section on line 66 of Fig. 3; ing a stationary fixed balancingdisk. Fac- Fig. 7 is a section on line '7 of Fig. 6; and ing this disk is a. revolving balancingring 44, I

' bottom of the chamber and ing to prevent rotation wheel 60 to which the rotor 62 of the carried by the hub of the impeller wheel, which at its opposite face cooperates with an adjustable stationary leak-off ring 46, shown in elevation in Fig. 4. This leak-oft ring is threaded into the stationary difiusing ring 36, as shown in Fig. 4, and is provided with a cylindrical flange 48 provided with slots 50. A set screw 52 is arranged to pass through a suitable slot into a fixed portion of the casof the ring.

During operation of the impeller, the intake suction and steam pressure tend to move the impeller wheel, shaft and turbine wheel to the left as viewed in Fig. 3. As will be noted from this figure, the discharge of the impeller communicates with the opposed plane faces of disk 42 and ring 44, so that these faces will be forced apart by the discharge pressure causing movment of the impeller to the right and permitting escape of water over the periphery of ring 44. lVhen such escape takes place, pressure may build up at the right of ring 44 balancing the pressure at the left thereof and permitting movement of the impeller to the left. As soon as such movement takes place, the liquid to the right of ring 44 leaks between the opposed plane faces of

rings

44 and 46 and through passages 54 and 56 to the discharge. An equilibrium position is thus attained, the distances between

rings

42 and 44 and

rings

44 and 46 becoming so related as to maintain a continuous flow of liquid the'rethrough thus maintaining ring 44 out of contact with ring 42 and providing a thrust bearing for the impeller and its associated rotating parts. In order to permit this balancing, the clearance between bearing 12 and rings 16 is made larger than the range of axial movement of ring 44.

The adjustable construction of ring 46 provides for ready and exact initial assembling and adjustment for wear. In order .to obtain proper clearance in assembling, ring 46 may be screwed inwardly until the three rings are brought into engagement. By then backing oif ring 46 byturning it a distance corresponding to a definite number of notches 50' and inserting screw 52, the proper clearance is obtained. A turn of the ring through an angle corresponding to that between adjacent notches corresponds to a definite axial movement of the ring so that the clearance may be readily determined. a

In order to supply lubricant under pressure to the b'earings, an oil pump is enclosed within the lubricant chamber and driven from the main shaft. To this end, the shaft is provided with aworm 58 meshing with a worm pump is secured, being journalled in asuitable bearing 63. A pump housing 64 consisting of a tube, is mounted in spaced relationship to the is surrounded at its lower end by a filter screen 65. The pump rotor has its lower portion formed as a screw 66 rotatable within the tube while its upper portion is formed with impeller blades 68 adapted to discharge through diverging passages 70 in tube 64 into an annular passage 72 formed in aboss in the wall of the lubricant chamber. Passage 72 communicates through passages 74 in the chamber casting with holes in bearings 12 and 14, as shown in Fig. 3, which serve to distribute the oil in the lubricant grooves.

The con'lbination of the screw lift 66 with the centrifugal impeller 68 is found to be of particular advantage in an oil pump. Because of the high speed of operation, centrifugal pumps for lubricating oil heretofore used in turbines have been found very unreliable because of the tendency to dig them selves dry or to stop delivering oil because of foan'ling. In such pumps the oil was drawn in under vacuum.

'In the construction disclosed, on the other hand, the oil is delivered to the impeller underpressure, the pressure being increased by the impeller to the necessary degree to insure proper lubrication. It is found that, by the use of the screw lift, whereby the production of a vacuum is prevented at the intake of the impeller, not only is the pump positively self-priming, but the objections to the use of a centrifugal pump above referred to are completely avoided, there being no tendency to draw air from the surface of the oil or to produce foaming.

Besides operating as a pump, just described is made to function as a separator of water from the oil in case any steam should leak in from the turbine and condense therein. For this purpose, anannular groove 7 6 is formed in the interior of tube 64 at the top of the screw 66. A plurality of small holes connect this groove with an outer pasthe device sage 78 communicating with a receptacle 80.

As a mixture of oil and water is pumped upwards by the screw a rotary motion is imparted thereto. Water being heavier than oil, it is thrown outwardly to the walls of the tube and passes into groove 7 6 and thence into receptacle 80 where it separates by gravity from the oil and may be drawn off by opening a stopcock connected to a passage 82. The oil overflows from the receptacle through passage 84 back to the lubricant chamber as indicated at 86.

Since the mechanism must not operate without lubricant, a combined means for giving visual indication of the amount of oil in the chamber and ping the machine in case of excessive diminution of the oil supply is provided. This means comprises a float 88 provided with an upwardly guided stem 90 containing indicatfor automatically stop- 1,7aa,ae1

. mark on the stem at a determined height. To

efiect stopping of the pump. when the oil level drops to a dangerous degree, whichmight result in failure of the pump to properly lubricate the bearings, acollar 96- is providedlon stem 90, normally positioned" above a s ring arm 98, the bifurcated end of which em races the stem. Arm 98 is carried by a latch member 100 pivoted at 102 to the casing and urged by spring 104. in a clockwise direction as viewed in Big. 5. Upon drop of oil level below a predetermined degree the weight of the float through collar 96 will depress arm 98 and trip latch 100.

Slidably mounted in the casing wall is a rod 106 which is urged outwardly by means of a spring 108 and is normally prevented from inward movement by engagement within a notch 110 in latch member 100. The outerend of rod 106 contacts with the first of a series of balls 112 contained in a tube 114 which, as shown in Figs. 1 and 8, extends to the housing of the turbine nozzle valve The last ball of the series contacts with the outer end of a. plunger 116 which is mounted to slide in the wall ofva'lve housing 118.

Vithin a cylindrical bore in housing 118 slides a. bushing 120 provided with a slot 122 in which engages a pin 124 to prevent its r tation. A spring 126 between the bushing and cap 128 tends to move the bushing inwardly. A valve stem 130 carr ing a needle valve 132, for controllingthe ow of steam from 133 through the nozzle, is threaded as at 134 through the bushing. The underside of the bushing is provided with a cam face 136 engaging the bevelled edge of plunger 116.

rangement of this type which simultaneously changes the throat area'and the ex ansion ratio, but such valve has been used or perthere was always a loss of usefulenergy.

In the present construction the nozzle regulating valve used directly as a governing valve, being operated through a series of shafts and universal joints connected to stem 130 and leading to the engineers cab. The use oi a single valve in the steam line to-the turbine results in maximum steam economy a t all loads with greatest simplicity of oper-- ation,sin'ce full steam pressure is maintained 1 at the throat of the nozzle.

A further advantage of thevalve which I makes it particularly adapted for emergency tripping is its lightness since the steam at the nozzle has a high velocity and consequently the valve may be small without producing Attention may be called to the nozzle and needle valve associated therewith. Hereto- ,fore it has been customary to use a valve arthrottling such as occurs when a separate small" governing valve is used in the steam line. In fact, for anything approaching'satisfactory operation with a; separate governing valve,.the valve mustbe seven to ten times the size of the valve'described herein.

Assuming the pump to be operating, the

bushing beingretained in the position of Fig. Shy plungerllfi so as to maintain the valve open, ifdepression of arm 98 occurs, latch 100 releases'rod 106 and plunger 110,

balls 112, and rod 106 are moved to the left against light spring 108 by the cam action of 136 under spring 126. Bushing 120 moves downwardly carrying with it needle valve 132 thus closing the nozzle.

'If it is now desired to reset the valve, the engineer turns stem 130 in-the direction in which it would beturned to normally close the valve. Since the valve is already seated in the nozzle. throat, the result of such turning will be raising of bushing 120. As soon as cam 136 clears plunger 138, the plunger will be moved inwardly by spring 108 which will be latched by member 100. If now the stem is rotated in. a direction to open the valve, bushing 120 will be held up by plunger 138 and the valve may be opened to the desired degree. Y

The movable bushing has a further function in preventing excessive tightening of the needle valve on its seat which might result in its destruction, since the valve would not normally be tightened to a pressure greater than that of spring 126 unless, of course, excessive turning was resorted to.

The tripping mechanism may be set into operation manually .by removing cap 94 and depressing rod 92 by hand.

The emergency tripping means described above may also be set into operation by a plun er 140, eccentrically weighted, and slida ly mounted in shaft 10 overlying arm 98. This plunger will'move outwardl at excessive speeds against the pressure 0 spring to contact with arm 98 and thus trip latch The impeller, balancing means disclosed hereinforms the subject matter of an applicgtion filed by Arvid Peterson on October 3', 1928, Serial No. 309,909. The oil pump and lubricating system are described and claimed 16, 1928, Serial No. 312,168.

Vhat I- claimand desire to protect; by Lctters'Patent is: I

1.1m a. turbine, a rotor, a nozzle for direeting fluid to drive said rotor, 21 valve for controlling flow of fluid through the nozzle, a

lubricant chamber, a float in said chamber,

"in a division of this application filed October and means operable upon depression of the float to close said valve to stop the flow of fluid through the nozzle, said float having a stem extending outside said chamber to indicate the lubricant-level therein and adapted" for manual actuation to depress the float.

2-. In a turbine, a rotor, a nozzle for directing fluid to drive said rotor, a bushing capable of movement in the direction of the axis of the nozzle, said bushing being yieldingly' urged towards the throat of the nozzle, a tapered plug valve adjustable in the bushing in the direction of the nozzle axis to control the flow of fluid through the nozzle, a cam surface carried by the bushing, a plunger movable across the path of said cam surface, and a latch normally holding said plunger in the path of said cam surface to limit movement of the bushing towards the throat of the nozzle, tripping of said latch permitting the bushing to force said plunger out of the path of said can] surface to permit the bushing to to a seated position at carry the plug valve the nozzle throat to stop the flow of fluid through the nozzle.

3. In a turbine, a rotor, a nozzle for directing fluidto drive said rotor, a. bushing capable of movement in the direction of the axis of the nozzle, said bushing being yieldingly urged towards the throat of the nozzle, a tapered plug valve adjustable in the bushing in the direction of the nozzle axis to control the flow of fluid through the nozzle, a cam surface carried by the bushing, a plunger movable across the path of said cam surface, a latch normally holding said plunger in the path of said cam surface to limit movement of the bushing towards the throat of the nozzle, tripping of said latch permitting the bushing to force said plunger out of the path of said cam surface to permit the bushing to carry the plug valve to a seated position at the nozzle throat to stop the flow of fluid through the nozzle, and means automatically operable when the speed of the rotor increases beyond a predetermined limit to trip said latch.

4.. In a turbine, a rotor, a nozzle for directing fluid todrive said rotor, a bushing capable of movement in the direction of the axis of the nozzle, said bushing being yieldingly urged towards the throat of the nozzle, a

'tapered plug valve adjustable in the bushing in the direction of the nozzle axis to control the. flow of fluid through the nozzle, a cam surface carried by the bushing, a plunger movable across the path of said cam surface, a latch normally holding said plunger in the path of said cam surface to limit movement of the bushing towards the throat of the noz- In testimony *"hereunto set my ishes b'eyond a predetermined degree to trip said latch.

of which invention, I have hand, at Trenton, Oct, 1928.

this 10th day of RUDOLPH BIRMAN N zle, tripping of said latch permitting the bushing to force said plunger out of the path of said cam surface to permit the bushing to carry the plug Valve to a seated position at the nozzle throat to stop the flow of fluid through the nozzle, a lubricant chamber, and means automatically operable when the amount of lubricant in the chamber dimin- N'. J., on