US1235936A - Steam-turbine. - Google Patents

Description

l1917 2 SHEETS-SHEET l.l

J. C. SHAW.

STEAM TURBINE.

APPucATloN FILED Nov. 2, 1914.

Patented A110: 7,

Zai...

J. SHAW.

STEAM TURBINE.

APPLICATION FILED Nov. 2. I9I4.

-SHEET 2.

Patented Aug.

2 sHEEVTs v @nue/nto@ @Quo/Magid w wit/museo ITE@ SATES PART @FFIQE JAMES C.y SHAW, OF PHILADEIIHIA, PENNSYLVANIA, ASSIGNOR 'IO THE WILLIAM CRAMP & SONS SHIP 8c ENGINE BUILDING COMPANY, A CORPORATION 0F PENN- SYLVANIA.

STEAM-TURBINE.

Specification of Letters Patent.

Patented Aug. 7, 1917.

Application filed November 2, 1914. Serial No. 869,769.

To all whom t may concern.'

Be it known that I, JAMES C. SHAW, a citizen of the United States, residing at Philadelphia, in the county of Philadelphia and State of Pennsylvania, have invented certain new and useful Improvements in Steam-Turbines, of which the following is a full, clear, and exact specication.

This invention relates to steam turbines, and more particularly to steam turbines for driving propellers of ships, wherein for various engineering and mechanical reasons it is desired to more or less balance the propeller thrust by opposing thereto a force within the turbine derived from the steam pressure.

The present invention has for its objects to simplify the construction, operation and repair of this type of marine turbine, and the invention is more especiallyy intended for marine turbines of the impulse type.

The improvementsv consist generally in the elimination of wheel stages with consequent elimination of diaphragme, there being but one diaphragm of the split type, the upper half of which is preferably bolted to and removable with the casing. Further improvements relate to the manner of admitting and controlling the steam to the 1 n1 tial nozzles, so that objectionable throtthng of the steam will be avoided at low powers, and also in the manner of distributing and conveying the steam through the various stages within the turbine so as to control the net axial thrust. rlhe total stages are divided between opposed drums, and the steam drop is so distributed by means of one or more compound velocity stages carried by the drums, that the net axial thrust at various powers is lrept within reasonably low limits. The steam is admitted intermediate the ends of the casing` at one side of the diaphragm, through multiple chambers controlled by valves, and thence passes through nozzles to a compound velocity stage wheel mounted on one end of' the high pressure` drum, to secure an initial drop, and thence passing through the drum stages wherein a further predetermined drop is effected. The forward gland is subjected to this steam of reduced pressure, and thence the steam passes to and through nozzles carried by the other portion of the single diaphragm to a second compound velocity wheel stage in case of low propeller thrust,

and thence through the opposite low pressure drum stages to the condenser. A reversing turbine mounted on the same shaft is also provided, and as shown herein comprises one or more impulse nozzles, a compound velocity wheel stage carried by the reverse turbine drum, and the reverse turbine drum, leading to the condenser. t will be seen that according to this invention, the net thrust available for opposing the propeller thrust in either direction is controlled by the numberA of compound velocity stages, and the volume of steam required at various powers is controlled without objectionable throttling by the separate valves controlling the admission of high pressure steam to the high pressure side.

The invention is shown in two forms herein, of which,

Figure l represents a longitudinal section of' a turbine adapted for an installation where the propeller thrust is low;

2! is a cross-section on the line 2-2 of Fig.A l;

Fig. 3 is a longitudinal section of a turbine adapted for an installation where the propeller thrust is somewhat higher, and also shows a construction by which the steam is led from one drum to the other along the shaft, instead of externally of the casing as in Figs. l and 2, and

Fig. 4f is a cross-section on the line 4:-1 of Fig. 3.

Referring first to Fig. l, l represents a main steam supply from the boiler, leading into a steam belt 2, mounted on the top half of a casing 3. The steam passes directly from belt 2 to a chamber 4 without lany valve and may also pass to additional chambers 5, 5, 5, 5, each controlled by valves 6 and hand wheels 7. These chambers 4, 5 are contained' within an interior segmental ring 8V which is attached to the upper half 9 of a diaphragm, the segmental ring 8 and diaphragm part 9 being preferably bolted to the upper half 3 of the casing and remova-ble therewith. At the center the diaphragm carries a packing 10 surrounding the shaft lfl. At one side of the diaphragm ring 8 is a series of nozzles 12, by which the steam is directed forwardly through the compound velocity wheel stage 13. This may have as many velocity stages as is desired for the particular installation in view, and there are also the usual stationary* Y by the drum 14 is made of considerably greater pitch diameter than the succeeding drum stage, so that a reasonable pressure drop in steam is permitted through the nozzles 12, consistent with efficiency. From chamber 16 the steam passes forwardly of the turbine through the forward drum stage l13, thence into chamber 19, where the steam has of course dropped considerably from its initial pressure. This pressure in chamber 19 is that applied on the forward gland 20 and consequently, simplification and reduced loss .of steam at this gland is obtained because of not applying the highest pressure of the steam thereto, as would be the case with steam admitted at the front head of the upper casing. Also, this makesthe forwardgland and the forward bearing more accessible by reason of the removal of pip ing, and the forward bearing is maintained at a. more even temperature owingY to its removal from the initial high temperature of the steam.

v At the high powers, all of the chambers 5 as' well as the chamber 4 will be employed, but at low power by shutting the valves 6, only the chamber 4will be employed, and this arrangement has the advantage of not throttling the high pressure steam. Also, the nozzles 12 are preferably of different numbers of sections, each having a different Ytotal nozzle area. By employing the proper combination of one or more valve groups controlling these variable nozzle sections with the nozzle section of chamber 4, which is always open, the total effective nozzle area can be varied to suit the desired power with the use of a very few valves and without throttling the steam. This condition is very favorable for efficiency in this type of turbine.

From the chamber 19 in Fig. 1, the steam passes by one or more pipes 42 into a nozzle chamber l21 formed in the lower half 22 of the diaphragm. rIhis diaphragm is provided with a nozzle 23, which discharges the steam into and through the blading on "the wheel 25 in a chamber 24. The second compound velocity wheel stage 25 is similar in general construction to the compound velocity stage 13. Although the volume of steam has increased, the lower partial admission nozzle 23 furnishes a sufficient area to pass. the steam to the compound velocity stage 25. Thence the steam passes into chamber 26 and through the rear drum stage 27 to the condenser chamber` 28. The rear drum 27 is carried by a head 29 which is keyed to the shaft 11. The head 29 is larger than head Y thrust.

14. In the reverse turbine, the steam enters at 30 into a nozzle chamber 31,thence through nozzles 32 to the compound velocity rear stage 33, thence to drum stage 34 of smaller diameter, then to the condenser chamber 28. 35 is the propeller of the ship, it being seen that a net pressure opposing the thrust of the propeller will be produced of relatively low value owing to the two compound velocity stages 13 and 25. The net forward thrust on drum 14 will be equal to the initial pressure, less the drop in compound velocity stage 13, multiplied by the area of drum 14, less the area of drum 14 multiplied by the pressure in chamber 19. The net backward thrust on drum 29 will be drop in compound velocity stage 25 multiplied by the area of drum 29, less the area of drum 29 multiplied by the condenser pressure. The net backward pressure will be equal to the difference, and it will be seen that the use of a compound velocity stage with one or both drums, absorbing a portion of the total drop, permits a greater range in the design of the drum diameters, and consequent range in blade speed, for efficient operation, than where the drum areasV are solely relied upon to secure the desired net Also, this invention avoids the use of excessive wheel stages in order to economically use the steam. The omission of velocity stage 25 would cause greater pressure on the forward side of drum 29 and thus increase the net thrust opposing the propeller, and is specifically illustrated in Figs. 3 and 4. @ne or the other arrangement will be employed depending upon the conditions required by a given installation.

In Fig. 3, the steam is similarly controlled by the valves 6, and passes first through tbe compound velocity stage and then through the forward drum into chamber 19 in the same manner as in Fig. 1. From chamber 19, however, instead of passing through the pipes 42 to the chamber 24, the steam passes through passages 38 formed in a sleeve 39 keyed to the shaft 11, which sleeve also carries the drum 14. The diaphragm has a packing 40 in each instance. The lower half of the diaphragm is imperforate, in Figs. 3 and 4, and the steam passes'from the chamber 19 directly through passages 38 and rear chamber 24 to the rear drum stages 27. The reverse turbine is constructed similarly to that of Fig. V1. In this form, it will be seen that the net thrust opposing the propeller thrust will be greater owing to the omission of velocity stage 25, but this omis sion is not essential. Nor is it essential in either form, except as stated in the appended claims, that the steam bepassed from one drum to the other precisely in the respective ways shown. Y

Various other modifications andV changes in the precise arrangements shoivn may be made VWithout 'departing -from the A,scope l.of

the claims.

linitial drum ',stage, a live steain inlet close to said diaphragmiat one 'side thereof and a steam conduit'fro'mthesame' side ofsaid diaphragmbeyond the drum on'` that side to the other side of the `,diap'hragm at a point close thereto.

2. In` a marine steam turbine comprising a shaft" carrying a'propeller and opposed pressure stage drums Vhaving a resultant opposite to vthe'propellerv thrust, aI single diaphragm betweenl said drums'and a conipound "velocity stage of larger diameter than and lcarried by one of said drums adjacent to said diaphragm for effecting a drop in thev effective 4press'ure before it isy applied tothe drum'head4 and initial drum stage,v a livey-lsteamy inlet close to said diaphragm at onefside'thereof 'and a' steam conduitffronr the' v7saine iside of said diaphragm beyond the druinjonv that sideto the other Vside of Vtlie'fdiaphragm atr apoint close thereto.

3. In a marine steam turbine installation,

`a shaft carrying oa propeller, a plurality of 40'y l y pressure staged V'drums thereon'havin'g a revsultant opposite to4 the propeller thrust, a

diaphragm l separating said drums, a j steam inlet at one side .thereof for supplying steamgtolone of vsaid drums, means for conducting steamjfrom',th`e .discharge end of saidudrum through the diaphragm to fthe Vother drum, and additional blading in advance of the stages of one of lsaid drums 'for Y eifecting av drop in the eective pressure before it is appliedto'the drum headiand initial drum stage.

4. A marine steam turbine comprising' opposeddruins, a single split diaphragm, one half being chambered and vhaving nozzles at the inlet side of one drum and cutting off the other drum, and means for passing the steam from the discharge of said iirst mentioned drum to the other drum, whereby intermediate Wheel stages and diaphragms are eliminated.

5. A marine steam turbine comprising opj posed drums, a single split diaphragm, one half being chainbered and having nozzles at the inlet side of one drum and cutting off the other drum, and means for passing the steam from the discharge of saidfirst mentioned drum through the other part of said diaphragm to the other drum,Whereby" intermediate Wheel stages' and diapliragms are eliminated.`v if 6. A marine steamturbine comprising opposed drums, a split; diaphragm"separating said drums, nozzles openingthrough one part Of `said diaphragmitothe blading of one of said drums, a steam passage leading from said iirst mentioned drum 'to the other part of said diaphragm, andtnozzles in" said other part for directing't'he steam to vthe blades Of said second drinn.

7. Amarine steam turbine comprising opposed drums, a split diaphragm separating said drums, nozzles openingthrough one part of slaidadiaphragm tothe blading of one of said drums, :and av steam passage through another partuof said diaphragm adjacent the shaft to said second drum.

S. A marine steam turbine comprising opposed drums, a split' diaphragm separating said drums, impulse nozzles openiiigthrough one part of'said diaphragm to the blading of one of said drums, asteam passage leading from said drum to the'other part of said diaphragm, and impulse nozzles in :said other part for directing the steam to the blades of said second drum.

9. `A marine steam turbine comprising opposed druins, a split diaphragm separating said drums, impulse nozzles opening `throug one part of said diaphragm to the blading of one ofsaid drums, and a'steam passage through another part of said diaphragm` adjacent the shaft to said second drum.

10. A marine steam =turbine comprising la casing, a'nl intermediate high4 pressure steam inlet thereto, la diaphragm dividing said casing at one sideof said inlet, a drum` on' each side of said diaphragm, nozzles between said steam inlet and one drum, and a steam passage'from the dischargeA end of said drum through nozzles carriedby said vdiaphragm to said second drum;

11. Amarine steam turbine comprising double opposed unbalanced drums, a diaphragm separating said drums,'an inlet adjacent one side of said diaphragm,impulse nozzles' opposite said diaphragm, a com-f pound velocity kstage beyond saidV nozzles mounted on one of said drums,y pressure staged buckets of smaller pitch diameter carriedby said drum between said velocitystage and the end of the casing, asteam passage from said first drum to saidsecond opposed drum, and pressure staged'buckets on said second drum.

12. A marine steam turbine comprising opposed drums, a diaphragmseparating said drums, an inlet adjacent one side of said diaphragm, impulse nozzles opposite said diaphragm, a compound velocity stage beyond said nozzles, a drum carrying the moving element thereof, buckets of smaller pitch diameter carried by said drum be tween said velocity stage and the end of the casing, a steam passage from said first drum to said second opposed drum, and a velocity stage in advance of said second drum having admission nozzles in said diaphragm opposite said admission nozzles for the first drum.

13. A steam turbine having a casing, a belt intermediate the ends thereof, a plurality of chambers within said belt, valves controlling the inlet of steam from said belt to said casing, nozzles in each chamber, a rotary element between said nozzles and the end of the casing, and a second rotary element opposing said first element actuated by steam from said first element.

lll. A steam turbine comprising opposed drums, a split diaphragm separating said drums, multiple nozzle chambers and valve mechanism on one side of said diaphragm for passing steam in variable quantity through variable nozzle openings in one part of said diaphragm to one ,of said drums toward one end of the casing, a passage from the discharge end of said drum through the other part of said diaphragm to the other drum, and nozzles carried by said other diaphragm part.

l5. A marine steam turbine comprising opposed drums, a split diaphragm separating said drums and one half being removable with the casing, means for directly supplying one of said drums with high pressure steam, and a passage from the low pressure end of said drum through the other` half of said diaphragm to said other drum.

16. In combination, a turbine casing divided into two parts by a single diaphragm with a steam inlet close to said diaphragm on one side thereof, a drum stage on the same side of said diaphragm, a compound velocity wheel stage carried by the drum stage receiving steam from said inlet and delivering said steam to said drum stage, the steam How through this stage being from the diaphragm toward the end of the casing, a conduit to conduct the steam from that end of the casing to a point close to the diaphragm on the other side thereof, a second drum stage through which the steam passes away from the diaphragm to the opposite end of the casing, an exhaust cham ber within the casing at said last mentioned end thereof, and a reversing turbine in said exhaust chamber.

17. In combination, a turbine casing havclose to the diaphragm on one side thereof,

and conducting it to the said drum stage and therethrough to the end of the casing, a

conduit from that end of the casing to the other side ofthe diaphragm at a point close thereto, and another drum stage through which the steam passes away from the diaphragm.

18. In combination, a propeller, a shaft therefor, a turbine casing around said shaft, a single diaphragm across said casing, two drum stages one on each side of said diaphragm adapted to receive the steam in succession with the flow away from the diaphragm, a compound velocity wheel stage carried by one of the drum stages and interposed close to the diaphragm so as to be subject to the steam flow before it enters the associated drum stage for each said drum stage, the resultant pressureson the two drum heads being substantially equal and opposite to the propeller thrust along the shaft.

19. In combination, a turbine casing with a single diaphragm across the same, a shaft within said casing passing through the diaphragm with a steam tight packing between the shaft and the diaphragm, two drums on the shaft, one on each side of the diaphragm'with large annular heads adjacent "to the diaphragm, blades on said drums,

means to admit live steam close to the diaphragm on one side thereofl toI -flow thence through the blades on the corresponding drum toward the end of the casing, a conduit to take said steam from thevend of the casing to the other side of the diaphragm at a point close thereto to pass away from the diaphragm through the blades on the other drum, an exhaust chamber at the corresponding end of the casing, and a compound velocity wheel stage carried by one of the drum stages close to the diaphragm and adapted to be subjected to the steam flow before it enters the blading on the corresponding drum.

In ltestimony whereof I aiiiX my signature, in presence of two witnesses.

JAMES C. SI-IAV.

Witnesses:

FRANCIS L. CRAMP, JAMEs I-I. KURTZ.

Copies of this patent may be obtained for ve cents each, by addressing the Commissioner of Patents,

Washington, D. C. Y

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