US862118A - Steam-turbine. - Google Patents

Description

No. 862,118. PATENTED JULY-so, 1907.

J. w. SMITH.

STEAM TURBINE.

l 1 il PATENTED JULY 30, 1907.

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UNITED STATES PATENT erstes.

JOHN W. SMITH, OF ERIE, PENNSYLVANIA, ASSIGNOR TO BALL ENGINE COMPANY, OF ERIE, I

PENNSYLVANIA, A CORPORATION OF PENNSYLVANIA.

sTEAM-TURBINE;

To all whom it may concern:

Be it known that I, JOHN W. SMITH, a citizen oi the I United States, and a resident of Erie, county of'k Erie, and State of Pennsylvania, have invented certain new and useful Improvements in Steam-Turbines, ot which the 'following is a specication.

' This invention relates to improvements in steam-turbines, and more particularly to improvements in that class of steam-turbines, which have chambers of gradually increasing cross-section arranged'along the path of the rotating buckets, to guide the steam in a spiral path from the inlet to the exhaust.

The invention has for its object to provide means for balancing the different pressures exerted by the steam on the different parts ofthe rotating member of the turbine, so as to obviate any loss in efficiency byunequal strains.

The invention has further for its object to provide an improved means of by-passing steam, which consists therein, that steam isl impinged directly against the .buckets of the turbine wheel, instead of supplying steam oi high pressure Ito a stage oi Vcomparatively low pressure as heretofore, for the-purpose of increasing the rotatory force of the turbine wheel to make it capable of meeting over-load conditions. i

The invention has urtherjor its object to arrange release blades in respect to the nozzle blanks, so as to be in line with the central portion of the nozzle blanks.

To accomplish the Iirst oi these objects the invention consists in providing the casing of the turbine with means for supplying steam to its chamber, of a pressure higher than that of the outlet casing.

For the second of these objects, the invention consists of an additional nozzle for impinging steam directly against the buckets to meet over-load conditions.

. The invention consists for accomplishing the last of these objects oi the arrangement of the release blades in respect to the nozzle blanks so that the blank extends far enough ahead of the tip oi the release blade to allow the density of the steam of one bucket to fall to that of the adjacent stage, before the nozzle of the adjacent stage directs the steam into a bucket which has just left a stage carrying a higher pressure. The tip of the release blades being arranged so as to be in line with approximately the central portion of the. nozzle blanks.

,The invention consists further of certain novel features of construction and combinations of parts which will be more fully described hereinafter and finally Specification of Letters Patent. Appnason sie@ Mami so, 1906. sayin No. 308,883.

PatentedJuly 3o, 1907.

of the low pressure casing partly in section and partly in elevation, and Fig. 4 shows a cross-section of my improved nozzle blanks, showing the arrangement of the release blade relatively thereto. I Similar letters of reference indicate corresponding parts..

Referring to the drawings, A represents the' high pressure casing and B the low pressure casing, A3 and casing. In the high pressure casing, a turbine-Wheel Al provided at its periphery with buckets D is secured to the shaft C. A main nozzle E, serves to im- 'pinge the high pressure steam against the buckets D,

and a plurality of admission vchambers F, F1, F2 and F3 and release chambers G, Grl and G2 serve to -guide the steam in a spiral path from the admission E to the opening R and the exhaust P. The walls forming the nozzle and the admission chambers extend clear down into operative proximity with the buckets of the turbine-wheel, and form, so as to say, blanksl. Intermediately between these blanks I of substantial thickness are arranged admission blades H .compara. tively thin and sharpened which serve to gu-ide the steam and to cause it to impinge in several streams ',againstthe buckets of the turbine-wheel. The wallsl inclosing the release chambers and forming the release blades extend also clear'down into operative proximity with the buckets of the turbine-wheel andare provided at these ends with scooped shaped portions f, ,which serve to gather up the steam emanating from the buckets of the turbine-wheel, ,and conj duct it against the release blades, whichthen guide it to the next admission chamber. The scoopedshaped releaseblades' are larranged relatively to the. nozzle blanks I, so as to be in line with approximately the 'central portion of the nozzle blanks, as shown for provided at its periphery with buckets D1, is secured to the same shaft C, as that to which the high pressure turbine-wheel A1 is secured. A nozzled shaped admission chamber F4 and admission chambers F5, FG, F7 and Fs similar toA those of thehigh pressure casing are arranged;'the walls of which also have their ends in operative proximity to the buckets of the turbinewheel forming nozzle blanks II of substantial thickness. Intermediately between these blanks II, -admission blades M comparatively thin and sharpened are'arranged which serve toguide the steam in several streams and impinge it against the buckets of the turbine-wheel. The 4low pressure casing is alsol provided' with release chambers G3, G4, G5, G and G7, the wall of which form release blades provided at their lowery j ends withscooped shaped parts in relative'position high pressure casing may be prin/ided-l in one oi its halves 1 with ythese operative elements, while the low presg causing work to'be d one will fall to 94 lbs. This consure casing might be provided in both halves with the same. `In this partof the casing the steam leaving the high pressure casing would pass through R and around thel upper or unused portion of this high pressure casing, and enter the upper half of the low pressure casing at S. Owing to the fact that no means for balancing unequal pressures had been devised, 4no turbine of the multiple impulse type having several pressure stages around the peripheryof its turbine wheel was considered practicable. And further, when no wheel cham ber pressure .was carried the leakage was excessive. In order to obviate these loss'es and to secure a proper balancing oi the turbine-wheel, the pressures of the steaml proposed to be used to operate the same', are such that one pressure is above that of the pressure of the wheel shown, one is of the samev pressure, and the other of a pressure lower than that of the wheel chamber.

Thus, assume the pressure in the wheel chamber to be 1'24lbs., the pressure in the nozzle E to be 160 lbs., and

the pressure below that ofthe wheel chamber` pressure to be 15 lbs; the` steam in the nozzle with the pressure of 16() lbs. will impinge against the buckets and in stitutes the first stage. The steam passing throughthe first release chamber G enters the admission chamber F and impinges again against the buckets, so that its pressure falls'to 62 lbs; constituting the second stage or stage No. 2. With this pressure, it passes through the lsecond release chamber Gl enters the admission chamber F1 to be again impinged against the buckets. In doing rso and: performing useful work, the steam is reduced in pressure to 39 lbs., forming stage No. 3. The i steam of this pressure passes through the third release chamber G2, enters the admission chamber F2 and in impinging against the buckets and doing useful works falls to the pressure of the wheel casing, namely 24 lbs. This forms stage No. 4. Emanatingfrom the-buckets with this pressure, the steam passes through the release chamber A5 in the d irection of and into the admission chamber F3, Which directs the steam so as to impinge it against the 'turbine-wheel, in doing. which its pressure falls to about 15 lbs. or 9 lbs. below that of the wheel vchamber pressure, forming stage No, 5. .The amount of these pressures both for the high and low pressure are simply given for example, it b eing clear that other pressures may be used. 'i

It will be noted that the admission not, as usual, arranged in order as to size with .the other chamberl F3, is

of the wheel chamber at a place adjacent the place acted l upon by the high pressure, exerting a force on lthe turbine-wheel in the opposite direction, a counterbalancingl of the turbine-wheel is obtained. This arrangement of pressures reduces leakage, and at the same time tends to conterbalance the excess radial pressure; `for while the steam in 'stages 1, 2, and 3, tends to force the 4,bucket 'wheel away from the nozzle, the wheel chamber pressure acting on the circumference of the turbinewheel at lstage No. 5 tends to force the bucket wheel againstythe nozzle. AIn actual practice the pressure fiuctuates and there is always an excess in the vertical direction tending to raise the turbine-wheel and release some ofv the load on the turbine bearings, however, this excess force is never equal to the weight of themoving,

with the admission chamber F4 of ythe low pressure cas- 4iVely through admission chamber F5'and release chamber G4; admission chamber F5 and release chamber G5; admission chamber F7 and release chamber G6; and admission chamber F8, release chamber Gr7 and exhaust v 'pipe Q, constituting successively stages numbers 7, 8,` 9 and l0, withpressures of 5.95 lbs, 3.71 lbs., 2.33 lbs..

' 1.45 lbs. and with 1 lb.,at the exhaust pipe Q.

Holes Nl, N2, vN3 and N4 are arranged in the low pressure casing head B4 nearest the low pressure casing, as

shown inFig. 1,'the object of which is to supply a vsuitable wheel chamber pressure, which in this instance isI equal to the pressure in the last stage before 'entering the low pressure wheel chamber, the turbine-wheel B1 l i is proyidd .with holes N6.

The fundamental principle of balancing when steam lis admitted in the high pressure casing at one entrance hinges on two features, the most important of which. lis the carrying of a suitable pressure in the wheel chamber, while the second is to place the negative stage adjacent the high pressure stage. As the density are disconnected at the point where the pressure on the wheel chamber is carried. Hence there is no bucket displacement loss. Thus the means described form practically a perfect counterbalanced condition. The fundamental principle which is common to both the high and low pressure turbines is the carrying of a suitable wheel chamber pressure equal to at least one stage higher than the pressuren the outlet of said casing.

A second form of balancing is made use of in the lou pressure case which is effected by allowing the stea to-be admittedon opposite sides.

In those cases where the requirements of an overload had to be met, it was usual to supply an additional amount of high pressure steam to a stage of comparatively low pressure which allows expansion to take place without im'pinging on the moving buckets. This method'is generally known as lay-passing the steam. This method of by-passing hasfthe. disadvantage that high pressure steam is delivered' to a stage carrying a comparatively low pressure, thus sacriiicing `a largev percentage of the kinetic energy. 'My improvement consists therein that an additional nozzle is'provided, which is supplied with high pressure steam and which .serves to impinge the steam of this pressure directly against the buckets of the turbine-wheel before mixing with the comparatively low stage pressure.' This has the advantage of utilizing all of-the`kinetic energy in the steam, and by this utilization'lto so increase the -overload efficiency. The improved nozzle constructionhereinbefore referred to is shown clearly in Fig. 2.

In arranging adjacenty to each 'other around the periphery ofa series of buckets, several pressure stages,

it is obvious, that the density of the steam in the buckets corresponds to the different'stages. Hence, a constant change of density takes place, as the bucket passes from one 'stage to an adjacent stage. The

blanks I of the high pressure casing or blanks II ofthe low pressurecasing, should extend A,far enough ahead ef dthe tip ef the reieese blade te anew the density of the steamin the bucket to fall to that ofthe adjacent stage, before the nozzle of the adjacent 'stag-e directs the steam-into a bucket, which has just left a stage lthat carried ya higher pressure. .In the embodiment of the invention shown in the drawings the tips o the release blades are arranged as to be in line with about the central part of the nozzle blank.v It is 'necessary in designing the release blade to so construct it that the steam from one stage will not escape into an adjacent stage and at the sametimer this release blade should be so designed so as not to `cause undue shock to the steam from the bucket. A

I do not wish to limit myself to the particular form and structure of the improvements herein shown and described as I have chosen them as one embodiment oi my invention., Many changes might be made without departing from the spirit of my invention.

Having thus described my invention I claim as new and desire to secure by Letters Patent:

1. In a steam-turbine havinga casing with an inlet and an outlet, a wheel-chamber, and means for guiding steam of different pressures from the inlet to the outlet, lmeans for supplying steam ,to the wheel-chamber of a pressure equal to one of the pressures of the steam guided by the means, and higher than the pressure of theoutlet.

2. In a steam turbine having a casing with an outlet, a wheel chamber and a turbine-wheel acted upon by pressure equal to, greater and less than that of the wheel chamber, positive means communicating with the wheel chamber for supplying steam ot one pressure thereto higher than that at the `outlet, and means for directing steam of high pressure, against that part of the turbinewheel which is adjacent to the part acted upon by the steam of a pressure lower than that of the wheel chamber.

3. In a steam-turbine having a casing forming a wheel-v chamber and having a nozzle and a plurality.. of guidechambers arranged therein for guiding steam of dierent pressures; means forming communication between one of said guide-chambers and the wheel-chamber, the admission-chamber having the lowest pressure being arranged close to the'nozzle guiding the steam of high pressure.

4. In a steam-turbine having a casing forming a wheelchamber and having a nozzle and a plurality. of admissionchambers of gradually increasing cross section arranged therein for guiding-steam of different pressures, means forming' communication between one or -said a'dnission- 80 chambers and the wheel-chamber, the admission-chamber having the lowest pressure being arranged close to the nozzle guiding the steam of high pressure.

' 5. In asteam-turbine having a high pressure casing, and a low pressure casing adjacent thereto havinga wheelchamber, and forming a compartment with the high pressure casing. holes in the 'low pressure casingat the side nearest the high-pressure casing f or the passage of steam from the lowipressure. casing, through the compartment to the wheel-chamber of the low pressurecasing.

6; In a steam-turbine, a plurality of nozzle blanks and a plurality of release blades arranged relatively to lthe nozzle blanks so as to be in line with some part of the nozzle blanks.

zie and the outlet for directingsteam separate from the stream of the rst nozzle and outlet, directly against the buckets.

9. In a steam turbine having a casing with an outlet, a turbine-wheel with buckets, a nozzle, and means forl guiding the steam in a stream through a spiral path from the nozzle to `the outlet, for successively impinging the steam against the4 buckets; an additional and Aseparatenozzle not in communication with the first nozzle, intermediately between the first named nozzle and outlet for directing steam in a stream separate from `that passing from the first nozzle in a spiral path to the outlet, directly against the buckets.

In testimony, that I claim the foregoing as my invention,-I have signed my name in presence of two subscribing witnesses.

'JOHN W. SMITH. Witnesses:

Ronnn'r L. Roniiin'rs,y WM. BLOOD.

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