US910164A - Elastic-fluid turbine. - Google Patents

Description

E. J BERG.

, BLASTIG FLUID TURBINB.

APPLICATION FILED APB.20.1907.

Patented Jan. 19, 1909.

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W/'Lrzess'ess may E. J. BERG.

ELASTIG FLUID TURBINE.

APPLIUATION FILED APR.20.1907.

Patented Jan. 19, 1909.

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E. J. BERG.

ELASTIG FLUID TURBINE.

APPLIUATION FILED 9141.291907.

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` ERNsT J. BERG, or SCHENEOTADY, NEW YORK, AssIeNoR To GENERAL ELECTRIC COMPANY,

A CORPORATION or NEW YORK. v

i ELAS'IIG-'FLUID TURBINE.

Specification of Letters Patent.

Patented Jan. 19,1909.

Application led April L 1907. Serial No. 369,252.

To @ZZwh-om 'it ma'yconcr'rt:

Be it known that I', ERNST J. BERG, a citizen of thevUnited States, residing at Schenmoderate fluid velocities, so as to avoid exthe one directly receiving the motive fluid,

cessive bucket speeds. In each stage of the simplest form of the invention are located two bucket wheels mounted to revolve in Opposite directions, one 'wheel receiving steam or other elastic fluid directly from a nozzle or other. iiuid-discharging device, the other receiving its supply from the firstmentioned wheel. One Wheel of each stage is mounted on its individual shaft which extends outwardly from the inclosing casing, and the remaining wheels are mounted on a shaft common thereto and extending between the casings.4 By reason of this construction tlie use of shafts located one inside of the other and the consequent disadvantages a-re avoided.

The shafts: for the vwheels are preferably locatedin axial alinement, andv are carried by suitable bearings mounted-on a bed-plate or other support. Since these wheels are separate and* arev not in engagement with each other, absolute alinement visunnecessary, although desirable. The buckets of the wheels are properly designed to extract the velocity ofthe fluid stream due to the nozzles by successive operations. In an arrangement of this kind, the losses dueto fixed or intermediate bucketsare' avoided because the fluid iws directly' from one wheel to the other.- 'llh'e velocity ofthe fluid leaving the'nozzle orl nozzles can be relatively high i withoutlhaving unduly lhigh .bucket speeds, because of the fact that the buckets rotate inv opposite directions. In a turbineof this character" the first: wheel, or

develops a materially greatertorque` thanl` The distribution of' does the second wheel. work between the two wheels in a given stage depends upon the relative spouting velocity ofthe motive fluid, the bucketshapes I and thef bucket speed.'

Tests made on a turbine-constructed@ in accordance with my invention show that- With a given amount'of energy and a bucket speed for each wheel of 5610 feet'- per second,

the work performed by the first orprimary Wheel will be about A'70% 30%. 4AThese ligures are given merely as illustrations and not limitations of the fact that the wheels develop different torques. An increase in bucket speed'will cause the of" the total and the, remaining or secondary vwheel about primary wheel`to do somewhat more Work and the secondary wheel less. A decrease in bucket speed has the opposite-effect. .To

state the matter in another way, the ratio between the two wheels as to the work per,L formed changes with changes in bucket speed for the same available energy, arid for the same speed with changes in available energy.' The dierence in torque developed rby the two wheels of such a combination has long been considered a serious drawback and;

attempts have been made to avoid it but without success. To compensate-for the difference in torque the wheel of the first stage developing the lesserl torque may be connected .to the wheel of a succeeding stagehaving af greater torque, the other wheels driving individual loads. For example, in a-two-stage four-wheel combination, the first Lwheel may. drive an individual-'load such as thev revolvlng,A member of" an electric generator; unit, and somay' also the last, while the-remaining or intermediate wheels may be connected-in a manner to drive as a coni, mon load-the revolving element of another generator unit.

however imposing thereon conditions inimical to safe design.

My invention, with respectto the`arrange- Such an arrangement re- 'sults in three independent-units whose power in the aggregate maybe very large without# ment of the generator units, is exceedingly flexible, since by combining the parts in various ways, the output of any particular generator unit can be made to be relatively large or small as conditions demand. Since the primary wheels develop considerably more power than the secondary Wheels, it is evident that for a given total output a combinationy of two prlmary wheels driving the intermediate or central unit will, when properly designed, give the maximum power; a primary and a secondary wheel, other things being equal, will give less power, and two secondary wheels will give still less power. The same holds true for the outside or end units. When they are driven by primary Wheels, they will develop the maximum power and when driven by secondary wheels, other things being equal, av lesser amount of power,v where the turbine is employed to drive a generator since vit enables me to produce by a combination of different types of units a much. larger turbo-generator than is possible with the ordinaryl types of apparatus where one generator supplies all of the current, since for certain speeds sonic of-these machines are limited to small units.

The synchronous y alternating-current generator, usually having a distributed stationary armature winding and a revolving field structure, the coils of which are excited from a suitable source of direct current, is limited in sizefc'for a given speed by mechanical considerations. In so far as present designs are concerned, for machines running at 3600 R. P. M. Vthe upper limit is about 750 kilowatts. .lVith lower speeds the output can of ,course be increased,"but by reason ofthe more efficient extraction of energy, it is desirable to use relatively high bucket speeds without abnormally large diameter on account of the great centrifugal stresses developed under such latter condition.

Assuming that the stages do equal amounts of work and that the first unit, -considered fromv left to right, is driven by a primary wheel, the second unit by a secondary and a primary wheel and the third unit byv a secondary wheel: the first unit would, for a given bucket speed and available energy, develop 30% of the total, the second 50% and the third .20%. Now, .assuming'that the limit in size of a synchronous maehine'for the givenl'shaft speed is 750 kilowatts, the third or last unit will be of 750 kilowatts output; the second unit would be2-3 X7 5021875 kilowatts, and the first unit )(75021125 kilowatts. The first and second units would therefore be of the induction type, the third of the synchronous type and the total out-V put at' normal load for the given speed would be 3750 kilowatts, or five timesas large as machine of the ordinary synchronous type with the limits now imposed y in the design.

The induction alternator, depending for its excitation upon alternating current derived from a suitable source, iswell adapted This is a very important factor.

to large outputs at high speeds, since the rotating member can be of the squirrel-cage type and therefore capable of high shaft as well as peripheral speed. It is, however,

vnecessary to havelsome alternating current source of supply to furnish the excitation.

When induction and synchronous units arev combined, the latter will supply the current for exciting the former. instead of making the stages perform equal amounts of work, one orV the' other may perform a larger amount, while the ratios between the units may also be changed.

In order that the generator units may supply current to a common load, such as the bus-bars on the switch-board in a power station, they are wound to deliver current at the same potential. When all are of the synchronous alternatingcurrent type and properly connected in multiple to the load, they will as is well known run at the same speed because the tendency of one machine to go faster or slower than normal is opposed by the current generated in other units in circuit. When synchronous and induction generators are connected in multiple they will operate in .electrical synchronism and very nearly, although not exactly, in mechanical synchronisrm In the case of direct -current machines, may tap the armature of each machineat suitable points and run multiphase Aconnections between the units, which connections willkeep the machines running at the same speed, andhence all will deliver current at the same potential. These connections form what may be termed an electrical gearing between the generator units,\since the action is to maintain the same speed for all of the machines, and cach machine contributes its share towards supplying the total amount of current required. Since these connecions may be depended upon in alternating or direct-current machines to maintain the 'same or substantially the same speed for all of the generator units, it follows that it is only necessary to govern the admission of motive fluid to one stage and the other will l take care of itself, although such an arrangement does not necessarily preclude the use of a governing mechanism'for the second stage where high economy is a factor of more importance than the additional first cost and that of maintenance.

My invention is directed principally to turbine generators containing means therein for causing them to run in svnchronism or vsubstantially in' sy'nchronisn'i uwith thc other units, but instead of'providing each generator unit or member with such means and forming a part thereof, separate means may be provided for the purpose. 'Such an arrangement is particularly useful where the turbine drivesl members other 'than electrical New# generator units. In this case each turbine shaft may be provided with asmall generator unit and the.necessary connections and slip-rings between moving and stationary parts to cause the shafts to run at the same speed..

In yt-he accompanying drawings7 which illustrate embodiments of the invention, Figure 1 is an axial sect-ion of a. turbine of the jet or impact type having oppositely rotating bucket Wheels; Fig. 2 is a more or less diagrammatic view showing a two-stage turbine of the type set forth in Fig. 1 connected to three electric generator units with the intermediate unit arranged to develop the major portion of the electric energy, the two outside units being smaller and hence of reduced capacity,- F ig. 3 is a more or less diagrammatic view similar to the above but with a different distribution of thel turbine parts to develop different torques; Fig. t is a similar view showing the -turbine parts arranged to develop more nearly equal torques; Fig. 5 showsl still another `arrangement of parts for the same purpose; Fig. 6 is a diagram showing two induction and one .synchronous alternating-current three-phase generator units connected to a common load, 1n such manner as to control their speed relation; Fig. 7 shows a suitable arrangement for direct current machines; Fig. 8 is a diagrammatic view of an inductiontype alternating current generator; and Fig. 9 a synchronous type alternating current generator.

Referring tov Fig. 1, 1 and 2 represent wheels, each having a row of peripheral buckets 3, the buckets of one wheel bein shaped to rotate in 'one direction and those vo ,the other wheel in the opposite direction.n

Steam or other elastic fluid is admitted to the first wheel by an expanding or non-expanding nozzle 4 as the conditions require.

The nozzle is or may be provided with charging device is bolted to one-half of the casing and the other half is provided with an exhaust chamber 6 connected by aconduit 7' with another stage or with a condenser depending on whether it is a highor a lowpressure stage. Motive fluid is admitted by a conduit 8 leading from the boiler, super` heater .or other source of supply. This conduit discharges into a chamber or chest 9' andthe latter supplies the nozzle passages.- To simplify the illustration, the governing mechanism has been omitted but 1t is to be understood that I may use one 'of any suitable construction.

bearings mounted on the bed-plate so that(l the alinement of one is independent of that of the other. By locating the shaft bearings on opposite sides of the wheel casing and making them of generous dimensions, I avoid the troubles due to alinement and also those which would be experiencedA if the shafts f' were telescoped. `Where the shafts pass through the walls of the casing, packings 13 are provided to prevent the escape of fluid when the pressure is above that of the atmosphere and to prevent the entrance of air when the pressure is less. These packings can be of any well known construction, those shown comprising carbon rings 14 closely encircling the hubs with springs 15 between, which press them against the. stationa'ry seats 16 and 17. The second stage of such a machine is similar in construction to the first except that the nozzles or other Huid discharging devices and bucket passages Aare made somewhat larger to 'accommodate the increased volume of motive fluid.

In Fig. 2-is shown atwostage threesgenerator unit combination wherein each of the end units .develops about fifteen percent. of

the total, `and the intermediate unit about.

seventy pei` cent. The intermediate unit is of the induction type and the end 'units of the synchronous type. Steam or other fluid enters the left-hand Stage of the. turbine by the conduit 8, flows through the primary bucket wheelthat is connected to the rotat ing member of the main enerator unit 18 and through the secondary' ucket wheel con-"1 nected to the left-handgene'rator unit 19. After exhausting from the'secondary wheel the Huid is conveyed to the nozzles of the second stage by the conduit 7. For the purpose of illustrationv these conduits are shown above the turbine and generators, but' obviously they may be located wherever it is the most convenient After the` pressure ofthe motive Huid is converted intoA velocity by the second-stage nozzles it actsy 1on the wheel buckets and the latter abstract the energy thereof by successive operations. ,The fluid exhausting from the second stage is conveyed by the conduit 20 to a condenser or to other exhaust. The primary wheel of the second stage is connected to the rotating member of the main generator unit 18 and the secondary wheel to the rotating member Tof the right-hand generator unit 21.-

In Fig. 3 the arrangement ofthe parts has been changed to give a different distribution r of energy. Here' the center generator unit is of the induction type and is driven by one primary and one secondary wheel of the two stages7 and as a result gives about fifty per cent. of the total output. The generator unit 19 is of the synchronous type and is driven by a secondary wheel as-before, and so its output remains unchanged at about fifteen per ceiit. of the total. The generator unit 21 is of the induction type and is `'driven by a primary wheel and therefore is larger than before and has an output of about thirty-five per cent. of the total. In this case the unit 19 can supply the exciting current for the other units.

In Fig. 4 is still a different arrangement. Here thev center generator unit 18 is driven by two secondary wheels and hasl an output ofabout thirty per cent. of the total while both'the end generator units areA driven by primaryvwheels, and each has an output of about thirty-five per cent. of the total. Such a combination is well adapted for directcurrent units. i

In Fig. 5 another arrangement is shown,

wherein the generator unit 19 is driven by a primary wheel as before andthe generator unit 18 by one primary and one secondary wheel and the third generator unit 21 by a secondary wheel. In this arrangement the generator unit 19 has a 'capacity-'egaal' to about thirty-five per cent. of the total, unit 18 about fifty per cent. and unit 21 about lifteen per cent.

In Fig. 6 is shown a diagram of connections of the generator units above referred to and illustrated in Fig. 3. These units are of the three-phase synchronous and induction alternating-current types. and the diagram is typical of the connections for the groups or arrangements of' induction and poses described.

synchronous units shown in the other figures. Each armature winding is connected by three connections 22, 23 and 24 to'the conductors 25, 26 and 27, which may be the bus-bars on a switch-board for example. The synchronous generator can be excited from a suitable source of direct current 28.

In Fig. 7 are shown three direct-current 'generator units 29, 3() and 31 with arnjiature 'taps 821200 apart which are connected by wires through slip-rings 38 with eachother and form a three-phase electrical gearing beelo-,164

alternating current unit suitable for the vpurposes described. Itfcomprises a stationary armaturestructure -37 and a revolving field magnet structure 38 having a winding 39 thereon supplied by some direct4 current source of supply. f, y

, I have shown each of the wheels provided with a single row of wheel buckets, since it is ideallyv simple in construction, but the invention is not to be construed as being limited thereto unless so stated specifically in the claims,' because Vmany ofthe advantages of my invention will follow where each wheel is provided with two or more rows of buckets either with or without stationary intermediate buckets. By using a greater number of vwheel buckets and the same Spm'itingve-v locity of the motive iiuid, other things being equalyI can obtain a lower shaft speed than where each wheel has only a single row of buckets.

In some cases it will be desirable to use intermediate buckets for the purpose of getting la better angle of entrance 'to the buckets of thesecondary wheels. 1By suitably shaping these buckets the wheels may be made to re volve in opposite directions, or by a change in shape they may be made to revolve in the ame direction. Irrespective ofthe direction of rotation imparted to the wheels, the benefits of my invention in so far as the generator isconcerned,.will follow; By dividing the generator into units and mounting the movable member of each unit on its own shaft, which shaft is entirely independent of each of the others, I am able to construct a larger generator for a given. shaft speed with units of standard. and Conservative design than has heretofore been possible.

`By dividing the generator into units andarranging them. in the manner specified, I am abl'e to utilize that type of generator unit 'which is best adapted for the given output and shaft speed, and by properly directing the steam or other elastic fluid thereto, each.

unit will perforniits share of the work. I

in this manner as being a very important .regard the idea of subdividing the g-eiierator` advantage Aboth from an electrical and me. ,y

ehanical standpoint. By utilizing three in'- dependent shafts in the manner specifiech troubles dueto the almementaiid lubrication l are reduced to. a minimum, and each electrical unit. and its driving member can read- -ily be assembled or taken down. The shafts can be made' relativelyl short thereby avoid* ing the .whipping action found with long` shafts and the bearings can be made ci a size best adapted foi' the work and located where they are readily accessible. I

The invention is shown in connectiouwith a turbine having p'afalleldiow siagesybut it is notnecessarily limited thereto, since the Y marea.'

10 represent .the best embodiment thereof; but

I desire to have it understood that the appaiatus shown isonly illustrative, and that the invention can be carried/out by other means.

What I claim as new and desire to secure by Letters Patent of the United States, is, f

l. A turbine comprising stages each having bucket wheels, iii combination with a mem-ber located between the adjacent wheels 20. of the different 'stages and driven thereby,

and other members located on the oppositev side of said stages and driven by the outer wheels.

2. A turbine comprising stages each having bucket wheels, in combination with a member driven by two of said 'wheels and other members each driven by an individual Wheel.

3. A turbine comprising stages each having bucket wheels, in combination with a member driven by a pair of said wheels located in different stages and other members driven by individual wheels, and means for controllingr the rotation of said members.

4. A turbine comprising stages each having oppositely rotating .bucket wheels, in combination with a member driven by a pair .of said. wheels and other members driven by individual wheels, and means con- 40 necting the several wheels in such a' manner as to control their speed relation.

5. A'turbine comprising stages, each con- -taining a primary and a secondary bucket Wheel which develop unequal torque and '45 shafts therefor, in combination with mem' bers driven thereby, 'one of which is mounted -on the shaft connecting'two of said wheels while`each of the other members is driven by an individual wheel`,theshafts for which extend in opposite directions.

6. Aturbine comprising stages each hav-c ing oppositely rotating bucket wheels, in combination with power-transforming units driven thereby, one f said units being con- .55 nected to a greater number of wheels than another,- and connections between the units the shaft connected to the pair of Wheels,

for controlling their speed relation.

7. A turbine comprising stages each hav-v fing bucket wheels, in combination with 'members driven thereby which require unequal amounts of power, the largest ofsaid members being located between two wheels and driven by both while the others are each driven individually by a wheel.

8; A turbine comprising stages each having bucket wheels,'shafts therefor, and independent bearings for each shaft, in combination with power-transforming units driven thereby which develop unequal amounts of' energy at the same shaft speed, the largest` of said units being driven by a greaternum'- bei' of `bucket wheelsthan the others, the shaft for `the largest unit being located between those of the other units and independent thereof.

9. A- turbine comprising stages each having oppositely rotating bucket wheels, -in combination with power-transforming units driven thereby which -develop unequal amounts of energy at the same shaft speed, and connections between the units to control their shaft speed. y

l0. A turbine comprising stages each having individual primary and secondary wheels which develop unequal torque at the same shaft speed, in combination with individual members driven thereby, one of said members being driven by primary w'lieels,

and a means for controlling the speed of the wheels and said members.

1l. A turbine comprising stages eachl having individual primary and secondary wheels-which develop unequal torque at the same shaft speed, vin combination with individual members driven thereby, one of said members being driven by primary wheels, the others by Secondary wheels, and means connectingthe several wheelsin such manner as to .control their speed of rotation.

12. A turbine comprising stages each having individual primary and secondary wheels which develop unequal torque at the same shaft speed', in combination with indil` vidual. power-transforming units driven thereby which produce unequal amounts of energy at the same shaft speed, and connections which unite the units and control the speedvof rotation of them and their connected wheels.

13.' A turbine comprising; stages each having oppositely rotatingwheels, in cmbination with a member driven by wheels of both stages, and other members driven indi- 'vidually by the remaining Wheels of said stage.l- 4

14. 'A turbine comprising compartments eachv having individual wheels mounted therein, a shaft for a pair of wheels, and individual shafts-for the remaining wheels, in combination with a member,driven by other members driven separately bythe individual shafts, and means for causing the shafts to rotate synchronously or.substan A ivio dvdul shafts for the other wheels, inde- In Witness 1.-'1ma1eos E have le'eunto seb pmdent bearings fir the shafts, and a bedmy hand this 19th my o'Apil, 1907. p ate common to t e bearings in combnay tion vwith a power-absorbing 7unit for the l ERNST J BERG' 5 shaft which s common to Wheelsl of both Witnesses:

stages, and other power-absorbng units, one BENJAMlN B. HULL, for each of the other shafts. HELEN ORFORD.

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