US1099970A - Steam-turbine. - Google Patents

Description

W. G. DODD. STBAM TURBINE. APPLIOATION FILED AUG.14, 191s.

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W. G. DODD. STEAM TURBINB.

APPLICATION FILED AUG.14i 1913.

Patented June 16, 1914.

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WILLIS Gr. DODD, OF SAN FRANCISCO, CALIFORNIA.

STEAM-TURBINE.

To all whom it may concern:

Be it known that I, WILLIS G. DODD, a citizen of the United States, residing within the city and county of San Francisco, California, have invented certain new and useful Improvements in Steam-Turbines, whereof the following is a specification.

My invention relates to steam turbines, more particularly to that type or class, in which the static energy of steam under pressure has been converted into velocity energy and is repeatedly redirected upon a rotor by means of a cooperating stator, and :may be termed a velocity staged turbine.

Heretofore, one of the principal losses occurring in turbines of this type, has been due to spilling, that is, the inability to safely and efliciently gather, all the steam discharged from the nozzle upon the rotor within the initial chamber of the stator, and this loss has been especially marked when a, relatively slow speed of the rotor has been required. l

A further loss has been due to the inability heretofore, to provide a path through the rotor and stator which would confine. the several convolutions of the steam, while traveling through the rotor and stator at different velocities, and prevent them from mixing, and thus dissipate the velocity energy they contain by doing useless work upon themselves.

The obj ect of this invention is to construct a turbine of this class, which can be operated at any desired rotative speed without spilling, and to conduct the steam through the rotor and stator upon a natural path in the form of a coil or helix, and substantially prevent the several coils from mixing or interfering with each other, and thus obtain a higher efficiency than has been heretofore obtained with turbines of this class.

Now I have discovered a method of constructing a turbine of this class by means of which, the object of this invention 1s obtained, which is, (l.) The pitch, and length of the steam path within the rotors buckets, must be made to conform substantially to the ratio existing between the acting velocity of the steam issuing from the steam nozzle, and the peripheral velocity of the rotor.

(2.) The coperating stator must be provided with a series of reversing nozzles, each having a diiferent, but a defined pitch, said pitch being determined for each reversing Specification of Letters Patent.

Application filed August 14, 1913.

Patented June 16, 1914.

Serial No. 784,746.

nozzle Vwith reference to, the length of the steam path within the buckets of the rotor, the acting velocity of the steam within the buckets of the rotor engaging said reversing nozzle, and the peripheral velocity of the rotor itself.

The features of construction embodying the discovery herein mentioned, will be understood from the following Vdescription and the acc-ompanying drawings, in which I have illustrated so much of a turbine of this class, as is necessary to a full understanding of the invention.

In the drawings: Figure l, represents a vertical section through the steamV nozzle, the rotor and the stator of a turbine of the class described and embodying my improvements, all in relative operating position, the broad arrow indicating the direction of rotation. Fig. 2, is a section through the rotor and stator on the line /w-m, indicating a steam path of substantially constant deflection within the rotor and stator. Fig. t, is a vertical section through the rotor and stator on the line y-a, indicating substantially the egg-shaped form of the recess required between the rotor and stator to provide a steam path of constant deflection, and should be specially constructed to meet the conditions governing each particular case. Fig. 4, is a plan view of the rotor with the stator super-imposed thereon, showing the steam nozzle, the rotors buckets, and the reversing nozzles of the stator in relative position. illustrating the method of determining the pitch of the rotors buckets, and the pitch of the reversing nozzles. Fig. 6, is a developecl plan of the stator indicating the path of the steam through the rotor and the stator, the broad arrows denoting the active path of the steam through the rotor, and the line arrows the path through the reversing nozzles within the stator. Fig. 7, illustrates the shape of the steam coil, helix, or worm, formed due to my construction by vthe steam in its passages through the rotor and stator, from its inlet to the outlet or eX- haust.

In the drawings,-A, represents an expansion or accelerating nozzle, by means of which the static energy of the steam is converted into velocity, B- represents a rotor, the buckets of which are preferably formed by inserting within the peripheral recess, thin plates of polished steel -C, these buck- Fig. 5, is a series of diagrams series of Lreversing nozzles -F, are formed,

preferably by inserting within the recess of the stator, thin plates of polished steel -G.

' Each of these reversing nozzles has a different, but a pre-determined pitch, depending upon the conditions under which the turbine operates, the reason for which will be hereiiiafter explained.

Merely for the purpose of illustration, let it be assumed, that a rotor is to be employed twenty-four inches in diameter, fitted with buckets two and nine sixteeiiths inches in y diameter, and is to operate at twelve hundred and fifty revolutions per minute under a steam pressure of one hundred pounds per square inch, and exhaust to atmosphere, we would then have: (1) The velocity of the steam issuing from the steam nozzle and directed'upon the rotor would be, approximately 2400 feet per second. (2) A rotor 24 inches in diameter and rotating at 1250 revolutions per minute, would have a e- 4riphei'al velocity of approximately, 181 feet per second. (3) The diameter of the rotors buckets beingy 2.57 inches, their circumferencel would be substantially 8 inches, which,

divided by 2, would provide an acting steam fi path within the buckets of the rotor, of substantially four Linches in length. These quantities being known, the required pitch of 'the rotors buckets, is now determined as follows As a portion of the steam velocity is vabsorbed at each action upon the rotor,

for lthe purpose of illustration, the acting 40 velocity of the steam may be taken vas that issuing from the rotors buckets. As the Nsteam is issuing from the steam nozzle at a A f velocity of 2400 feet per second vand `enters the buckets of the rotor, which is moving at 15 a velocity of 131 feet per second, it would emerge therefrom, neglecting frictional `A`losses at, 2400 feet minus 262 feet, or 2128 fe'et per second. The ratio therefor, between the acting velocity of the steam and the peripheral velocity of the rotor would then be,2138 divided by 131, or substantially 16,

giving Aa lratio of 16 to 1, indicating that,

' v Aunder the conditions named, the pitchvof the buckets, must be equal to one sixteenth, of the length, Vof 'the steam path within the buckets, or 4 divided by 16 which is .25

Vinches, as may be illustrated by diagram -1,

-of Fig. 5. If a particle of steam moving at a velocity of 2138 feet. per second, starts to move across the rotor, along the line, from ther point` 1 to 1, which is four inches in Y I length,.and vis moving in the direction indicated by :the Ybroad arrow, at a velocity of 131 t'feet per second, the particle will be de- S flected or carried forward and discharged 'then :be 2138 minus 262, or 1 the steam entering the first reversing nozzle, would be carried lthe point of entrance to thatof 5, as shown, diagram2, of Fig. 5, or equal to, 4 inches divided by 14, giving amiamo at 1 or a distance represented by -a, which is one quarter of an inch. The buckets of the rotor are now formed by inserting within the peripheral recess of the rotor thin plates of polished steel, spaced one quarter of an inch apart. This being the width or pitch -D, of the buckets, required for the rotor, under the conditions named.

Practice has demonstrated that the pitch or diameter of the steam nozzle should not exceed one fifth the diameter of the rotors buckets, and that it must engage evenly full buckets, and to prevent spilling the rear wall of the steam nozzle, must substantially register with the initial wall of the first reversing nozzle. In Athe present illustration, the

Vsteam `nozzle is made of a pitch engaging two full buckets ofthe rotor, and the initial wall G1 of the initial reversing nozzle Fa, is located as shown, registering at its receiving end substantially with the rear wall of the steam nozzle in such a manner, that all the steam discharged by the steam nozzle, will be safely and eHiciently conveyed within the first reversing nozzle under the conditions named, and redirected upon the rotor ahead of the steam lnozzle. The location of the second wall G2 of the reversing chamber is now located as shown parallel with G1, the pitch ofthe initial reversing nozzle F being equal to that of three of the rotors buckets, and it may be stated that the pitch of the initial reversing nozzle is always substantially equal to, the pitch of the nozzle plus the pitch of one rotor bucket. Thus constructed, the initial reversing nozzle F receives efficiently all the steam dischaiged from the rotors buckets in its initial action upon the rotor, in a compact form, reverses it within and along a natural path free from distortion, and redirects it upon the rotor,

;at substantially the same velocity as received therein.

The pitch of the second reversing nozzle .is now determined as follows: Neglecting frictional losses, and assuming that the ve locity within the initial reversing nozzle is 2138 feet 'per second, its acting velocity would 876 divided by 131, gives substantially 14, indicating that the rotors buckets from forward by Ithe v-rotor 'before discharge, from a distance equal to substantially .29 inches. A vertical line is `now erected from the point 2, of Fig. 6, and

the distance is set off, from which point fthe third nozzle wall or plate G3 is inserted parallel to G2 thus forming the second reversing nozzle --Fb, within which the steam -is again reversed, and again redirected upon the rotor. able velocity Proceeding as before, the availwithin this nozzle being substantially 1876 feet per second, we have,

formed as before.

1876 minus 262 gives 1624 feet per second as the acting velocity, which divided by 131, gives substantially .12 indicating that the next advance of the steam in passing through the rotor will be equal to 4, divided by 12, giving substantially .33 inches,.or a distance equal to 0, as shown, diagram 3, of Fig. 5. A vertical line is now erected. from point 3, of Fig. 6, and the distance 0, is laid off, and the reversing nozzle F3 is The available velocity of the steam within this nozzle being substantially 1624 feet per second, the acting velocity would then be 1624 minus 262, this gives substantially 1362 feet per second, which divided by 131 gives substantially 10, indicating that the next advance of the steam in passing through the rotor will be 4 divided by 10, equal to .40 inches, or a distance equal to 65, diagram 4, of Fig. 5. A vertical line is now erected from point 4, of Fig. 6, and the distance cZ, is laid off, and the reversing nozzle Fd is formed as before. The velocity of the steam within this nozzle being 1362 feet per second, its acting velocity would be 1362 minus 262 or 1100 feet per second, whichV divided by 131 gives substantially 8 indicating that the next advance of the steam in passing through the rotor will be equal to 4 divided by 8 equals .50, or one half inch, or a. distance equal to e diagram 5, of Fig. 5. A vertical line is now erected fro-m the point 5 of Fig. 6, and the distance c is laid off and the reversing nozzle F e is formed as before. The velocity of the steam within this nozzle being 1100 feet per second, its acting velocity would be 1100 minus 262 or 838 feet per second, which divided by 131 gives substantially 6.4, indicating that the next advance of the steam in passing through the rotor, will be 4 divided by 6.4 which gives substantially .63 inches, or a distance equal to f diagram 6, of Fig. 5. A vertical line is now erected from point 6, of Fig. 6, and the distance y, is laid off, and the reversing nozzle Ff is formed as before. The velocity of the steam within this nozzle being 838 feet per second, its acting velocity would be 838 minus 262 or 574 feet per second, which divided by 131 gives substantially 4.4, indicating that the next advance of the steam in passing through the rotor will be 4 divided by 4.4 or substantially .9 inches, or a distance equal to g diagram 7, of Fig. 5. Avertical line is now erected from point 7, of Fig. 6, and the distance g, is laid 0H, and the reversing nozzle Fg is formed as before. The velocity of the steam within this nozzle being 574 feet per second, its acting velocity would be 575 minus 262, or 312 feet per second, which divided by 131 gives 2.38 indicating that the next advance of the steam in passing through the rotor will be 4 divided by 2.38 or 1.7 inches, or a distance equal to L, diagram 8, of Fig. 5. A vertical line is now erected from the point 8 of Fig. 6, and the distance la is laid oif, and the reversing nozzle Fh is formed as before. The velocity of steam within this nozzle being 312 feet per second, it would emerge from the buckets of the rotor at a velocity of 312 feet minus 262 feet or 50 feet per second, and would require for its exhaust from the rotor a distance equal to e, diagram 9, of Fig. 5. A vertical line is now erected from point 9, of Fig. 6, and the distance 7c is laid 0E, and this distance indicates the space required for the exhaust, and also, gives the least possible distance available for the location of another steam nozzle with its accompanying stator.

It is obvious that when high rotative speeds are required of the rotor, that the pitch of the reversing nozzles will be much greater than as here shown, and in order to hold the coils in proper trajectory intermediate abutments may be employe The method of construction of a turbine of the class describe-d and as herein disclosed, fully indicates and describes `step by step the operation performed at each action of the steamy upon the rotor, from the primary steam nozzle to the final exhaust, and it 9 shows that the path so formed for the 1mpelling medium under the operating conditions named, is a natural path, free from distortion, eliminates the loss due to spilling, and substantially prevents the several coils of the impelling helix from intermingling and thereby vdissipate the useful velocity energy they contain.

It is to be observed that the construction of a turbine of the class described, and as herein disclosed, constitutes within the rotor and stator an interlocking device, analogous to that of a worm gear and pinion depending for its efficiency entirely upon the conditions under which it is designed to operate.

Due to the interlocking of the rotor and stator, forming a natural helical path for the impelling medium through the rotor and stator, an inelastic iiuid may be employed as the impelling medium if so desired and under these conditions, the device may be properly described as, a velocity staged fluid motor, comprising a rotor, consisting of substantially a worm gear of uniform pitch, impelled by means of a fluid worm of uniform diameter, the several coils of which are, each of a different pitch and rotating at different velocities, said worm being held in operating position with referenceto the rotor by means of a coperating stator, within which hollow nuts of corresponding pitch are formed, whereby the fluid Worm travels through the rotor and stator, from the inlet to the outlet without interfering with 4each other, thus converting they ve-v rotor, within which are located a series of` circular acting buckets the pitch and length ofthe steam path therein substantially conforming to the ratio existing between the velocity v-of the iinpelling medium issuing from the nozzle and the peripheral velocity lof the rotor.

2. A velocity staged turbine comprising a. nozzlel for 'the iinpelling medium, a rotor within which are located a series of curved `working buckets, Ithe pitch ,and length of kthe active path. therein conforming substantial-ly to the ratio existing between the acting velocityof the impelling medium and the peripheral velocity oftherotor, in combination with a coperating stator Within which are located `a series of reversing nozzles pitched with reference to the length of the steain -patli within 1the buckets of the rotor, the acting velocity of the inipelling niediuni engaging said nozzles `and the peripheral velocity `of the rotor, whereby a convoluted path is provided for the iinpelling inediuin through the rotor and stator, as and for the purpose set forth.

3. A velocity staged turbine comprising a rotor within which are located a series of curved buckets, the pitch and length of the steani path therein conforming substantially7 to the ratio existing between the acting velocity of the inipelling medium and the peripheral velocity of the rotor, a nozzle for the inipelling medium kengaging one or more full buckets of Ithe Vrotor `in combination with a Acooperating stator having a series of reversing nozzles, the pitch of the initial reversing Anozzle being substantially equal to the ninnbero-f buckets engaged by the nozzle plus one more, and in relative position adapted to receive in a .compact forni the entire discharge from .the nozzle and redirect .it again upon the rotor.

In testimony that I claim the foregoing I have set my hand this 18th day of August, 1913, in the presence `of witnesses.

W. G. DGDD.

Witnesses A. M. SnwELoi-i, A. B. CRAIG.

C Qpies of this patent may be obtained for ve cents each, by addressing the Commissioner of Patents, Washington, D..0.'

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