US830892A - Means for preventing the distortion of bucket-wheels. - Google Patents

Description

PATENTED SEPT. 11, 1906.

W. L. R. EMMET.

MEANS FOR PREVENTING THE DISTORTION 0P BUCKET WHEELS.

APPLICATION 'I'ILBD MAY 6, 1904.

2 SHEETS-SHEET 1.

Fig.5.

Witnesses.

PATENTED SEPT. 11

W. L. RLBMMET. MEANS FOR PREVENTING THE DISTORTIION 0F BUCKET WHEELS.

, APPLICATION FILED KAY 6, 1904.

2 SHEETS-SHEET 2.

Inventor: William L.F?.Emmeb,

Witnesses:

ITED- STATES PATENT OFFIGE.

IVILLIAM' L. It. EMMET, OF SOHENECTADY, NEW YORK, ASSIGNOR TO GENERAL ELECTRIC COMPANY, A CORPORATION OF NEW YORK.

lnEANS FOR PREVENTING THE DISTORTION OF BUCKET-WHEELS.

Specification of Letters Patent.

Patented Sept. '11, 1906.

Application filed May 6. 1904- Serial No. 206,709-

I s It has been found in connection with elastic-fluid turbines, and particularly in those having wheels of large diameters, that when in operation a difference exists in the mean temperature on oppositesides of the wheel,

and, further, that this difference varies under different conditions of operation. .This temperature diflerence is sometimes noticeable in starting the turbine, as well as during its normal operation, and is usually detected by the sound occasioned by the rubbing of the relatively rotating parts. In other words, the temperature on one side of the wheel may be greater than on the other, and when this difference exceeds a certain amount it causes a prohibitive distortion or Warping of the wheel parts. The diflerence in temperature is largely due to the fact that the tem erature of the steam or other motive fluid lea ing through the clearances between the nozzles or other discharging devices and the buckets and also around the shaft is above that discharged from the wheel, the said leakage being frequently in a superheated condition. The temperature diflerence is also due to radiation from the adjacent wall or diaphragm of the stage of higher pressure. Another reason for this difference is found inconnection with. those stages where by reason of their construction a difference in pressure exists on opposite sides of the wheel. My observation in connection with vertical-shaft machines having wheels occupying horizontal planes with the flow of motive fluid downward in an axial direction is that the excess temperature on the u per side may cause a downward deflection o-the wheel, thereby causing the buckets on the exhaust side to rub unless the clearances are excessive. The same action may take place in horizontal machines; but in such event the distortion is in a horizontal or approximately horizontal direction instead of. vertical or approximately vertical direction. The deflection is more noticeable in the last wheel of"a turbine, wherein the active area of the at a more nearly uniform temperature.

from warping or distorting the wheel.

wheel is greateras, for example, when the nozzles and intermediates cover the entire or substantially the entire circumference of the wheel but it also takes place in other wheels located in stages or compartments of higher pressure.

Broadly, my invention contemplates the idea of preventing or reducing this distor: tion to a point where it can be disregarded by protecting the surface or surfaces of a turbine which are normally exposed to motive fluid by a suitable covering or mask applied surfaces will be less susceptible to temperature effects.

My invention also broadly contemplates the idea of compensating wholly or in part for any tendency which the turbine part or parts may have to warp or distort, due to unequal temperature effects.

. The invention is applicable to turbines having one or a number of wheels in the at any suitable place or places, so that said same or separate compartments, and I do not limit myself to any particular wheel construction, either as to the body of the wheel or to the arrangement of the buckets. Neither do I limit myself to the character or arrangement of the devices which supply motive fluid to the wheel or to the controlling 'mechanism or to the arrangement of the buckets.

The particular wheel or wheels to be prochambers which further serve to prevent distortion by causing the entire wheel to operate To made in single I state the matter differently, the covering and chambers, considered together or separately, act to prevent sudden temperature chan gs e temperature of thewheel as a whole can be increased or decreased, as. desired; but the changes should be brought about in such a manner. Between the covering and themanner that no substantial difference exists at any given instant of time on those surfaces which are capable of causin distortion.

In order to compensate or any tendency to distortion which may exist under varying conditions of operation, I may connect one or all of the chambers with one or moresources of fluid-pressure which is capable of changing the temperature of the wheel parts to a certain extent. The arrangement of the chambers and supply-passages should be suchthat ,the effect of the fluid is readily felt over 'those' surfaces which are capable of causing distortion. The chambers may be formed at the time the wheel is made or they maybe formed inha bluilt-up structure that is attached to the w ee Y In order to carry out the invention withexlstlng constructlons, a

'dlsk or covering, usually of metal, may be mounted on the in let side of thewheel which covers theentire surface or a large portion of said surface.

main body or web ofthe wheel is a' chamber which may or may not contain a heat-resist-' ing medium, or in certain cases a cooling me-- dium may be introduced. On the exhaust side of the wheel isa suitable covering which protects that side of the Wheel from the Bf. fects of the steam or other elastic fluid in the compartment in which the wheel is'located.

The covering may and preferably should cover all ora very large portion of its surface. Between the covering and the main body or web of the wheel is preferably a chamber of suitable size. This chamber is adapted to receive a heated medium-such, for example, as the motive fluidfor increasin the mean temperature of the exhaust side o the wheel, The fluid may enter the chamber in any suit able way'. I have shown two such ways. In one case the fluid enters through one or more openings or passages formed in the web of the wheel and in the other case through one or more passages formed in the hub of the wheel. These latter passages are arranged to receive the fluid'whieh leaks from one stage to an other around the packing's. In this manner the leakage fluid is rendered more effective than heretofore and any tendency towarping or distortion compensated for. Arranged at one or more suitable and preferably out of line with the inlet-passage, are passages or openings through which the fluid escapes after having given up its heat or a certain per cent. thereof to the sur faces of the wheel. The fluid thus escaping from one wheel discharges into a comparttwo paths, the normal or main path through the nozzles, wheel, buckets, and intermediate oints in the covering,

buckets, where the latter are used, and an auxiliary path conveying a small portion of the fluid for heating purposes alone. The main and auxiliary paths are arranged in multiple, the former being of relatively low resistance and the latter of relatively high resistance.

It is desirable to cover both the admission and exhaust sides of the wheel, but the covering onthe admission side can be omitted under certain conditions, and I aim to embrace this arrangement in the claims.

In the accom anying drawings,which illustrate one eml iodiment of my invention, Figure 1 is a partial vertical section of a jetturbine of the multistage type having two rows'of wheel-buckets per stage. Fig. 2 is a transverse section of the same. Fig '3 is a detail sectional view showing the arrangement of the inlet and outlet ports or passagesv for conveying motive fluid into and out of the chamber on the exhaust side of the wheel, and Fig. 4 is a detail perspective view of one of the channel-irons employed to support the covering. v

1 represents the main shaft, upon which are mounted'one or more bucket-carrying Wheels 2 Eachof these wheels is provided with one or more rows of buckets 3. In the present instance each wheel isprovided with two rows of buckets. v shown in the present construction, which are inclosed in a casing 4, made up of suitable sections. The wheels are separated one from the other by diaphragms 5, which 100 divide the easing into compartments, a single wheel being located in each compartment. Between the diaphragms and the shaft or the hub ofthe wheel is anacking 6 for reducing the leakage between the wheel-compartment and the next. Steam or other elastic fluid is supplied to the wheel-buckets by a valvechest -7, which is connected to the source of supply. Mounted in the valve-chest are a number of valves 8, each of which is actuated a piston 9, that is or may be under the control of a relay-valve, the latter being controlled by a speed-responsive device. Each valve controls the passage of fluid to one or more nozzles or nozzle-sections 9, which in turn discharge the fluid at the proper angle against the buckets. Where two or more rows of buckets are provided for each wheel, intermediate buckets 10 are provided be tween two rows ofwheel-buckets. The arrangement of the nozzles and buckets is the same throughout the machine, except that V the active p'ortionof the wheel graduallyenlarges from the inlet to the exhaust.

The wheel-casing is mounted on a base 11, which contains a chaml r 12, that is'corinected to a condenser or to the atmosphere, as is desired. Mounted on the upper surface of each wheel to be protected are concentric rings or supports 13 and 14, which support F our wheels are the protecting-covering 15, the latter being of disk-like formation and made up of one or more pieces. In the present construction this covering is made up of two sections of sheet metal riveted together, as shown in Fig. 2. The covering is supported at intermed1 ate points by channel-irons 16, shown in dotted lines in Fig. 2 and in perspective in Fig. 4. On the under side of the wheel are attached concentric supporting- rings 17 and 18, to which the covering 19 is attached. This covering is supported at intermediate points by channel irons 20 of the same character, as shown in Fig. '4. Between each of the coverings and the web of the wheel is a chamber 21, the chamber on the upper side of the wheel acting simply as a dead-air space or chamber, while the chamber on the under side is connected to the steam-space above the wheel by one or more openings, passages, or conduits 22. In the present illustration there are a number of circular openings near the periphery of the wheel and other openings near the hub of the wheel. In addition to these are passages 23, formed in the hub of the Wheel, which communicate with grooves formed in, the pack-ings 6, so that any'leakage through thepacking will be diverted into the chamber on the under side of the wheel.

In order to permit the fluid to pass fromthe chamber either on the under or upper side of the wheel after giving up a certain amount of its heat to the Wheel parts or cooling it, as the case may be, one or more openings or passages 24, Fig. 3, are provided, the

said passages being offset from the inlet-passages to prevent the steam or other fluid .from passing directly from the inlet to the ,under side of the wheel, but in some cases certain of these passages can be omitted.

- From actual tests of my invention I have found that objectionable wheel distortions can be obviated andthat'the compensation may even be in excess of that required and actually cause thebuckets to move up instead of down. i

In accordance with the provisions of the patent statutes I have described. the principle of operation of my invention, together with the apparatus which I now believe to represent the best embodiment thereof; but I desire to have it understood that the apparatus shown isonly illustrative and that the invention can be carried out by other means.

What Iclaim as new, and desire to secure by Letters Patent of the United States, is-

1. A turbine comprising a casing and relatively movable parts, in combination with a protecting-covering attached to and moving with a part for preventing objectionable distortion thereof.

2. A turbine. comprising a caslng and a bucket-wheel, in combination with a protecting-covering applied to the web or body of the wheel.

3. A turbine'comprisinga casing and a bucket-wheel, in combination with a protecting-covering for the'web or body of the wheel and means for attaching the covering to the wheel.

4. A turbine comprising a casing and a bucket-wheel, in combination with a protecting-covering for both sides of the web or body of the wheel.

5. A turbine comprising a casing and a bucket-wheel, in combination with a protecting-covering for one side of the Wheel, and a chamber situated between the covering and the Wheel.

6. A turbine comprising a casing and a bucket-wheel, in combination with protecting-coverings for both sides of the wheel, and a chamber situated between each covering and the wheel.

7. In a turbine, the combination of a casing, a chambered wheel, and a conduit for admittingfiuid to the chamber.

8. A turbine com rising a casing and a bucket-wheel, in com ination with a protective covering carried by the wheel for preventing it from distorting, said covering being independent of the bucket-supporting portion.

9. A turbine comprising a casing and a bucket-Wheel, in combination with chambers moving with the wheel and arranged to receive a fluid for equalizing the mean temperature on opposite sides of the wheel.

12. A turbine comprising a casing and a bucketwheel, in combination with a protecting-covering for one side of the wheel, containing a chamber, and an opening or passage for conveying a heat-imparting fluid to the chamber.

13. In a turbine, the combination of a casing, a chambered wheel, driving-buckets carried by the wheel, and an opening or passage for conveying motive fluid from one side of the wheel into the chamber.

14. In a turbine, the combination of a casing, a chambered wheel, driving-buckets car-. ried by the wheel, and an inlet and an outlet opening or passage for the chamber.

15. In a turbine, the combination of a casing, a chambered wheel. buckets on the Wheel, nozzles discharging fluid against the buckets, an inlet opening or passage located nearthe periphery of the heel, and an outlet opening or passagelocated at a point remote therefrom .for preventing Wheel distor-' tion.

16. In a turbine, the'combination of a cas- 1 ing, a chambered Wheel, inlet-openings 10- cated near the center and near the periphery of the Wheel, and outlet-openings located'between the inlet-openings.

17. In a turbine, the combination of a chambered bucket-wheel, a casing therefor, a Wall situated Within and dividing the easing into compartments, a packingfor reducing the leakage around the wheel-shaft, and a passage leading from the packing to the chamber in the Wheel.

'cated on opposite sides of the wheel for 18; A turbine comprising a casing anda bucket-Wheel, in combination with means 10- equalizing the temperatures.-

. 19. In a steam-turbine, the combination of.

a chambered bucket-Wheel, a casing therefor, a device for protecting the inlet side of the Wheel from hot steam, and means for directing hot steam against the exhaust side of the Wheel.

20. In a turbine, the combination of a Wheel, a casing therefor, buckets on the Wheel between Whichthe major portion of the motive fluid passes to produce rotation, and an auxiliary path through Whichthe motive fluid passes to equalize the mean temperatures on opposite sides of the Wheel.

21. A turbine comprising a casing and relatively movable parts, buckets carried by one of the parts, and devices for discharging fluid against the buckets, in combination with a hand this 5th day of May, 1904.

WILLIAM L. R. Ei/niET.

Witnesses BENJAMIN B. HULL, HELEN ORFOBD.

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