US963178A - Elastic-fluid turbine. - Google Patents

Description

R. H. RICE.

ELASTIG FLUID TURBINE. APPLIUATION rum 215.10, 1908.

Patented J uly 5, 1910.

Witnesses fpass to atmosphere.

UNITED STATES PATENT OFFICE.

RICHARD H. RICE, OF LYNN, MASSACHUSETTS, .SSIGNOR TO GENERAL ELECTRIC COMYANY, A CORPORATION 0F NEW YORK.

ELASTIC-I'LUID TURBINE.

Application tiled February 10, 190B.

To all whom it may concern:

Be it known that I. Ricimnn H. Rica. a citizen ot' the United States, residing at Lynn, county of Essex, State of Massachusetts, have invented certain new and useful Improvements in Elastic-Fluid Turbines, of which the following is a specitication.

The present invention relates to elastic fluid turbines. and more especially to those of the impact type, and has for its objects to improve their etlicieiiey and also their construction. In the accompanying drawing which illustrates one of the embodiments of my invention, Figure l is a partial axial section of a vertical shaft turbine; Fig. 2 isa detail sectional view taken on line 2-2 of Fig. l; and F ig. 3 is a view in side elevation of a turbogenerator.

1 indicates the base. ot' the turbine havin-r an outlet 2 through which the exhaust .steam normally passes to a condenser or it, may Bolted to the base is a spider 3 that. supports the stepand lower guide bearings. and carried by the base. is a parl-:ing 4 to prevent the escape ot' steam from the chainbered base; or the entrance of air.

5 indicate the niaiii shaft upon which awy I n been pointed out. the velocity of the tluid secured the bucket wheels, a single whwi with two rowsl ot bueliets being provided for each stage.

Mounted on the base is a wheel casing made up in segmental sections of suitable size. the upper or high pressure end of the easing being larger in diameter than the bottom or low pressure end The upper end of the easing is provided with a head 't' having a central bore through which the shaft passes and a par-king 8 to prevent the escape of steam or other elastit-.lmotive fluid. In the head are passages l) communicating with the val\e chest l() and with the sections or pai-'sages of the divergent nozzle 11 bolted or otherwise secured to the under side of the head. These admission nozzles cover a relatively small wheel are and have a 'greater iatio of expansion than the stage nozzles so as to reduce the pressure within the first stage or wheel compartment to such a low value under all conditions of operation as to keep the strains on the casing within a safe margin.

The idea of a multistage impact'. type of turbine operating with a greater pressure Spee? cation of Letters Patent.

Above the guide -bearing Patented Juiy 5, 1910.

Serial No. 415,024.

drop in the first. than in any one of the subsequent stages is notof itself broadly new but I provide for a materially greater ressure drop than has been contemplated 1eretofore, and by reason of this and other features am enabled to obtain superior results. Turbines of the character referred to are provided with stage nozzles which are normally in service and other stage nozzles which are putJ into service automatically or otherwise as the, load increases and` the steam pressure in the, first stage tends to build upor when additional steam -is needed. Then the stage valves operate automatically they are. arranged, in so far as possible, to maintain a constant stage pressure under varying conditions of load. By reducing the pressure in the first stage to an extremely loir7 value as I do, it is lower at', light loads than is necessary to safeguard the wheel casing, hence when the load in; creases to maximum the pressure will only rise by a certain predetermined amount, the total value of which does not exceed the safe working limits of the casing and its parts.

liroin this itwill be understood that I ain' able to dispense with stage valves, and hence all of the stage nozzles will constantly be iu service when the turbine is in use. As has ATssiing from the admission nozzles is greater `han that from the stage nozzles7 hence in order to extract an amount of velocit from the steam in the first stage comparab e with thatI extracted .in the subsequent stages the bucket speed should be higher. This is attained by making the first stage 'wheel larger in diameter than the wheels of the subsequent stages. Oiving to the fact that the pressure in the tirst stage is abnormally low as conti-:Med with pressures previously eniployed, l' ain able. to utilize a wheel of large diameter and this withoir` high rotation losses because ot' the low density of the steam. By rotation losses .I mean the losses due to friction between the wheel and the surrounding medium and the fan-like action of the wheel buckets. Decreasing the first stage pressure as described renders it easier to pack the wheel shaft. where it passes through the easing head. Other things being equal it also reduces the weight, of the casing, head, diaphragm, etc. Dispensing with stage valves reduces mechanical complication and initial cost. Further it decreases the number of parts which have to be looked after by the engineer in charge of the machine.

As above stated, in my improved turbine the velocity ot' the steam in the first stage is higher than in any ot the remainder` and the said stage does considerably more Work, in

the turbine illustrated about one-third of the .creases without, however, endangering the casing, and lsince the pressure distribution in the stages changes somewhat under these conditions the lower pressure stages will automatically do more work as the pressure increases. As the load falls ottl the pressures in the several stages gradually change until the initial condition is resumed. As an eX- ample of the pressure relations: that of the supply may be 200 pounds absolute, the pressure in the first stage 30 pounds absolute, and that of the exhaust l pound absolute. The great drop in pressure due to the nozzle 1l having divergent walls results in a high spouting velocity of the steam. In order to etfectually utilize this velocity I provide a bucket wheel l2 in the first stage of considerably larger diameter than those of the succeeding stages, and owing to this large diameter the bucket speed closely approaches the theoretical for the conditions mentioned. For example, the bucket speed may be 500 feet per second with a normal spouting velocity at the nozzle end of 2200 feet Der second. The diameter of the upper end of the casing is greater than that of the lower end` to accommodate the large bucket wheel. At the point of change in diameters a shoulder is provided upon which rests the largest diaphragm 13 in the machine. lt is not only larger in diameter but it is also thicker. Surrounding the diaphragm is an annular chamber 14. the annular outer and bottom walls beingr formed by the casing. the inner wall by the l'tcriphery ot' thc diaphragm and the upper wall by a rclativck,Y thin metal ring 15 riveted or otherwise attached to an internal projection on thc wheel casing and to the peripheral edge of the diaphragm. This ring is cnt away at a pointdirectly under the admission nozzles to t'orm a segmental opening ol suitable .shape and area to permit the steam exhausting from the whccl-t0 freely enter it. it is to be noted that the annular chamber ll surrounds thc diaphragm 13B instead ol" bcing conlncd in a .small arc directly between thc exhaust side ol' thc lirsl uio-cl and l-lnI nozzles ol. the nc.\t stage. This arrangement. permits olI a chamber of large cross-section without increasing the, axial length of the turbine by any appreciable amount. Owing to the great drop in pressure in the admission nozzles the volume of the steam increases enormously by the time it enters the chamber and to utilize this to its best advantage all of the stage nozzles leading into the second stage as well as those leading into the succeeding stages are active. Boiled to the largest diaphragm is a stage nozzlel 16 that imparts velocity to the steam and completely surrounds the second stage wheel so that all or practically all oi: the buckets will be active. This nozzle or the sections thereof are fed with steam from the annular chamber 14 by passages 17 cored in theperipheral portion of the diaphragm. Owing to the fact that the chamber 14 is annular and communicates with all of the second stage nozzles the latter are all supplied with steam at the same pressure.

The stage nozzles may be divergent or nondivergent in character, in any event the velocit of the motive fiuid discharged thereby will e considerably less than that discharged from the admission nozzles. For example, the spouting'velocity of the steam atthe ends of these nozzles may be 1G00 feet per second when that of the adniission nozzle is 2200 feetl per second. Under these condi-A tions the bucket speed of the low pressure stages can with advantage be about 425 feet per second.

' In the second stage compartment 18 is a bucket wheel 19 of considerably smaller diameter than the one in the rst stage. This wheel as well as the others in the turbine are each provided with two rows of buckets Q0 and intermediate buckets ,21 between the rows. In the first stage these intermediates cover only a comparatively small wheel arc, substantially the same as covered by the admission nozzles, while in the second and in the succeeding stages they cover the entire wheel circumference. I

The diaphragms between the stages of the lower pressure diti'er in construction from thc large high pressure diaphragm. Since the construction of these diaphragms and their supports are the same a description of one ot them will be sulticient.

Formed on the inner wall of the wheell casing is a shoulder 22 and seated thereon is a ring comprisingan inner and an outer cast metal portion and sheet metal partitions dividing thc space between them into passages all of which extend in the .same direction and discharge .steam al the same angle to tho wheel buckets. ln .':iaking these rings the shcct metal partitions are put into the coreI and the coro is then placed in the mold in the, usual manner. The part of the mold forming the inner portion of the ring is poured lit-sl. 'tcr thc metal has had a izo chance to cool somewhat the outer portion of the ring is poured. In coohng the outer portion will contract somewhat and instead .of the partitions being under tension, as

. which I regard as being an important adwould be the case if the parts were poured simultaneously, they are under compresslon vantage. In so far as the broader features of my invention are concerned they are not to be construed as limited to the particular construction of these rings and diaphragms. The outer portion ofthe ring rests on the internal shoulder of the casing While its inner portion is provided with a shoulder to receive the diaphragm prcper. This diaphragm 24 is provided With a shaft opening and supports a packing sleeve 25 of suitable character around the shaft.- It is provided With concentric ribs to strengthen it, and also with sheet metal disks 26 on opposite sides each of which present a smooth surface to the steam in the compartment soas not to oppose its movement, and also to decrease the size of the Wheel compartment so as to limit the amount of steam contained therein. Located above the casing is a stool 27 that supports the casing 28 of an electric generator. The upper end of the turbine shaft is provided with a guide bearing .29 supported y the stool. On the end of the shaft is a coupling 30 for uniting it with the generator shaft 31 above it. The guide bearing is supported at suitable points by the stool and between the points of support are spaces to erxnit of access to the bearing. From this it follows that the heated air from around the turbine would pass directly into and through the generator thereby increasing its temperature and endangering its life. To prevent this a ring shaped plate 3; is provided that is bolted to the stool or other supporte It is provided with one or more openings through which access may be had to the parts above. and these openings are covered by doo 's that are held in placeA by bolts or other means.

By reason of my im proved construction I am able to produce a turbine which has a relatively low shaft speed and at the same time one having high economy of operation. The parts are simple and rugged in lconstruction and the machine can be erected or taken down with a minimum expenditure of time and labor. By using a larger first stage wheel and a' casing having two diameters. ample provision can be made for the annular chamber receiving steam therefrom and this Without unduly increasing the axial length of the machine. Since I avoid the use of stage valves and separate nozzles controlled thereby 'the first cost of the machine is materially reduced as is also the number of parts. The cost. of attendance and main tenance is also reduced.

I have shown the Wheels all located in the same casing since this is a desirable construction but the. invention is not to be construed as so limited unless specified in the claims.

I obtain the high bucket speed of the first stage by `using ay larger wheel than in the later stages and mounting all of the wheels on the same shaft, but in those cases vvhere a divided shaft arrangement can be utilized IVhat I claim as new and desire to secure by Letters Patent of the United States, is.-

l. A turbine that is divided into stages of expansion, divergent admission nozzle which discharges the motive fluid into the first stage at a pressure that is only a small perccntage of the initial pressure with a correspondingly high velocity so that a larger l percentage of the Work will be performed in the first stagethan in any one of the later stages and the casing strains under varying load conditions and the leakage losses will be reduced -to a relatively low value, a wheel for said stage that has a bucket speed great enough to effectively convert the high vc locity ot the fluid into mechanical work. stage nozzles each of which converts a lesser percentage of the pressure into velocity than the said admission nozzle. a wheel for cach of the lo\.\.'pressure stages located adjacent its nozzle v.bich acts on the impact plan to fractionally extract the velocity, each wheel having a ucket speed which is less than that of the initial stage, shaft means for carrying the wheels, inclosing means. for the wheels, and exhaust-receiving means.

2. In combination, a turbine divided into stages, admission and stage nozzles, the former having a greater ratio of expansion and imparting a greater velocity to the motive fluid than the latter. bucket wheels for the stages all of ivhich act on the impulse plan to extract the'velocitv produced b v the nozzles in successive operations, one of the high pressure. stage Wheels operating at a higher bucket speed and performing a greater amount of Work than a low pressure stage bucket wheel, and an exhaust conduit.

3. In a multi-stage turbine, the combination of a casing. means dividing the turbine into separate wheel compa rtmcnt;'- or stages. a supply chest, admission and stage nozzles, the former shaped to cause a greater drop in pressure and a. higher spouting velocity of the. motive fluid than the latter, bucket wheels in the. stages, the bucket wheel in the, first stage havin" a. greater diana-ter than the remaining w ieels and performing more work than said wheels, and an exhaust conduit.

4. ln combination, a turbine divided into st ages, admission nozzles which cover a limited wheel arc and cause a greater drop in pressure between the source of supply and the tirst stage than do all of the stage noz- '/.lcs combined, stage nozzles, a bucket wheel for the tirst stage acting on the impulse.

plan, the buckets ot which have a greater velocity than those ot' the subsequent stages, bucket wheels for the remaining stages also acting on the impulse plan to extract the velocity of the motive Huid' in successive operations, and an exhaust conduit.

5. In combination, a turbine divided by diaphragms into stages, an admission nozzle which imparts a greater velocity to the motive fluid than do the stage nozzles, a bucket wheel cooperating therewith whose diametervis greater than that of the wheel of the stage of lowest pressure and which performs more work, an annular chamber which receives the fluid exhausting from the first stage and supplies it to the next, stage nozzles converting the pressure of the fluid into .\'elocit v, certain ot' said nozzles receiving motive fluid from said chamber, rotating buckets for the remaining stages all of which act on the impulse plan, and an exhaust conduit.

(i. In a turbine, the 'combination of a shouldered easing, a supply conduit, a removable diaphragm resting on one of said shoulders and which divides the easing into compartments. an aiiiinlar chamber which is located between the periphery ot' the diaphagn'i -and the inner wall of the casing,

wheel buckets exliaustiif;- into the chamber.

stage nozzles receiving motive fluid from the chamber, the conduits in the peripheral face of the diaphragm supplying motive fluid to said stage nozzles. additional dia-Y phragins resting on shoulders in the easing for dividing the latter into other compartments, stage nozzlesl and rotating buckets for the last mentioned compartments, and an exhaust ronduit.

i. ln a turbine. the combination of a casing havingr portions ol dilferent diameter with :i shoulder between the one of larger diameter being located at the high pressure are supported b v the portionthereot'liaving the smullendiameter, an aimular chamber bounded by the tirst mentioned diaphragm. the shoulder und llic lniu-r wall ol the cas ing, rotating buckets for the compartments separated by the diaphragms, admission and stage devices discharging Huid to the buckets. and an exhaust carrying means.

S. Tn a turbine, the combination of a easing liai'inga high pressure portion ofgreater diameter than the low pressure portion with a shoulder between, a diaphragm which rests on the shoulder. divides the casing into compartments and is provided with passages communicating with the tiuid discharging devices of the adjacent stage, an annular chamber which surrounds the diaphragm and supplies tluid to the passages, means dividing the casing into additional compartments, admission and stage de"ices for discharging motive fluid, buckets for the compartments for extracting energy from the motive tluid, and an exhaust conveying means.

il. ln an elastic fluid turbine. the combination of a casing. means dividing it into stages or compartments, rotating buckets for the stages which abstract velocity from the motive fluid due tothe nozzles, those in the' tirst stage performing a greater amount of work than those in any other stage, a support 'for the buckets, the portion for the high pressure stage buckets heilig greater in diair eter than the remainder to give a hit?l 1' bucket. speed, admission nozzles which impart to the tliiid a greater velocity aecoinpined by a greater pressure di'op than do the stage nozzles, the said admission nozzles supplying fluid to only a limited number of buckets, stage nozzles which imi-irtvelocity to the fluid and discharge itt-i il of the buckets in the. remaining stages; and an exhaust conveying means.

lt). ln au elastii` fluid turbine, the combination ot' a shouli ered casing, a diaphragm which rests on the .shoulder and divides the casing i'nlo compartments. :in aunula'r nozzle ou the low pressure side ot the diaphragm, and passages in the diaphragm which open on the peripheral t'ace thereof and convey fluid to the nozzle ou the side thereof.

11. ln a turbine, the combination of a casing, wheel buckets therein, a vertical shaft carrying the buckets, a device driven by the shaft. bearings for said shaft,I a means for preventing fluid at. high temperature from aroiiud the turbine passingupward into the said device, a door in said means through which access may be had to the parts of said device, and means t'or conreyingmotive fluid to and from the turbine.

ln witnesswliereol, l have hereunto set ltltllXltl) ll. RICE.

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