US1008529A

US1008529A - Marine steam-turbine.

Info

Publication number: US1008529A
Application number: US59315910A
Authority: US
Inventors: Charles G Curtis
Original assignee: Individual
Current assignee: Individual
Priority date: 1910-11-19
Filing date: 1910-11-19
Publication date: 1911-11-14
Anticipated expiration: 1928-11-14

Description

c. G. CURTIS. MARINE STEAM TUBBINE.

APPLIUATION'FILED NOV.19,`1910.

Pa ;ented Nov.14,1911.

2 SHEETS-SHEET 1.

Inventor Awf,

C. GfCURTIS.

MARINE STEAM TURBINE. APPLIOATIQNWFIILBD Nov; 19, 1910.-

Patented 11011111911.

2 SHEET -SHEBT 2,

i backward CHARLES G. CURTIS, 0F NEW YORK, N. Y.

MARINE STEAM-TURBINE.

Specification of Letters Patent.

Patel lted Nov. '14, 191,1.

Application iiled November 19, ISM). Serial No. 593,15 l.

To all w72 om 'it may concern:

Be it known that I,- CHARLES G. CURTis,

a citizen .of the United States, residing at New York city, inthe county and State of 5 New York, have invented a c'ertain new and useful Improvement in Marine Steam- Turbines, of which the following is a specification.

The object I have in view is to simplify and cheapen the construction and repair, :and also to increase the eiiciency, of marine steam turbines, particularly those having initial jet impulse stages.

In the employment' of steam turbines for the pro ulsion of ships, the high speed of the tur ines makes necessary or desirable the'4 relieving of vthe thrust blocks, so far as possible, of the thrust due to thepropel- 1ers. In marine steam turbines of the axial flow `t pe, steam pressures are available, exerte longitudinally of the' propeller shafts, which can be employed to neutralize the propeller thrust. The utilization of the steam pressure to neutralize the propeller thrust has created a limitation upon4 the design'of marine steam turbines especially of thosehaving initial jet imfpulse'stages, resulting Vin complication o parts and excessive length and cost of the turbine In the design of im ulse marine steam turbines, in order to obtain the large number of steam expansions necessary to give the re- (pllired 1 w straft speed rwith highl eiiiciency, t e prac ice has been to providefat the steam `admission end ofthe turbine a considerable number of wheelsiistages with their accompanying disgihra'gms to separate the 'essures carrie in the different -sta es. 4 `his has beenV necessary in order to ring the pressure down to a point Vso that whenthe steam is a liedjto a final drum pressure stage, the i erenc'e in pressure on t e drum head will give a backward-thrust on the shaft which will equal ap roximately the- ,.45 'forward thrupt of the prope er. This ressuremust below, because the area o the drum .head islarge, andgbecause in steam turbines' of Vthe impulse type,'or those havi'ng initial timpulse stages, an additional f st-results from the fact that the shaft. atthe ends of the turbine casing isusually Isteppeddown o't reduced in diameter to give a practical' size for effective packing by means of stuing boxes or pack- 5K5 lng glands. 'hisconstrlltlon produces an area subject to. the highfpressures existing lthis respect, howevq r,

` inthe early wheel` which exerts a thrust opposed to th( propeller thrust, due to the fact that at th l other end of the turbine casing where the shaft is similarly stepped, the corresprnding area is subject to the exhaust or 'tcl lninal pressure. This thrust produced by t le reduction in size of the shaft at the ends of the turbine casing, and which will hereil after be referred to as the shaft-thrust n ay be as great as forty pe?? cent. of the prt peller thrust, or even more, and hence redu :es the amount of propeller thrust, which must be neutralized by the head of the final drum stage. The necessitl which thus a rises for employing a consi erable number of wheel stages results 'in an increase of cor lplication and expense 1n constructlon, and also 1n an increase 1n the length of the t1 rbine, due tothe nu- -merous diaphra ms and steam spaces required.` The di cult; f and cost of repair are also increased' on, ac :ount of the inaccessibility of the diaphrs gms and the bushings carrled by them, wluch reduce the steam leakage between the 'wheel stages.

By my present invention two or more drum pressure stage` are employed having steam, tight heads alapted to withstand a considerableV pressu: e difference without change of shape, and one or more of these drum stages is or an reversed so as to produce a'thrustin the same directionms the propeller thrust.4 BI properly proportionlng the'steam passge areas through the drum stages, so as to secure the proper )ressure drop between th l. two ends of euch rum stage, andby having each drulnhead of the proper comparative area, the `aiding thrust ofthe' reversed dru n stage or shages will bear such a relation to the opposing thrust of the direct drum si age or stages,thut, tuking into considerati n` the opposingshuftthrust, there will be produced a 'thrustopposing the propeller thrust whichwill substantially neutraliz( or balance .the propeller thrustor red ice the resultant. thrust which must be carr ed bythe thrust block to an entirely'practi able amount.' The turf' bine thrusts, which rre dependent upon the steam pressure, vary with the load, as liked wise doe's the propl ller thrust, but not in exactly the same r: tio. The diiference in is not great enou4 h :tical balancing of e to prevent the pra propeller thrust by the turbine thrust at all substantial power i. The drum stages'may A neutralizing the propeller thrust already set be constructed so as to operate on the impulse or on the reaction principle. If they operate on the latter principle, the blade thrust, due to differences in pressure between the entrance and exit edges of the moving blades, Will also have to be taken into consideration as an element in the construction of the turbine.

By the employment of the reversed drum pressure stages, I am enabled to largely reduce'the number ofV the initial wheel stages, and the accompanying diaphragms, steam spaces, etc. Two or three such wheel stages will probably be found sufcient for the objects which they subserve in my improved turbine, although more than three or only one may be employed, depending upon the power to be developed and the steam pressure to be used. These objects are to secure by the nozzles of the first Wheel stage a considerable reduction in pressure to a point which can be practically controlled as to leakage by packing aroundthe shaft, and to reduce the pressure and increase the volume of the steam before reaching the first drum stage so that the com-plete annular admission of steam at the drum sta e can be secured with blades of such a dept (radially) that the loss by tip clearance leakage Will be s reduced to a .permissible percentage. the wheel stag'es, although the volume of the steam is small at this point, the buckets can be made of the desired radial depth because of the fact that a artial peripheral admission of the steam i. e., jet admission) .is employed in these stages. The principle of forth may also be applied to the reversing turbine, but with the-simple and low eiciency forms of reversing turbines now eni-4 ployed, this is not necessary, since a small number of wheel stages can be emlployed, and a final drum pressure sta e can used whose diameter will be so re uced that the area presented by the drum -headwll give the necessary pressure to reduce the resultant thrust upon the thrust block .to a practicable amount.

Another feature of my present invention consists in providin a construction which will give accessibillty to the diaphragm bushings .or packin so that-'they can be renewed or repaire ,Without removing `the shell or casing of the turbine. vThis 1s accomplished by such an arrangement of thel parts that spaces are provided adjacent to the diaphra s-large eno h -to permit the removal 'an 4replawement-o the bushings or packings in sections without the disturbance of other parts, which spaces, in the .case ofA hi h y power turbines may be large enough togadmit the 'body ofa workman. Accessisgiven 'tojthese spacesby of man-holes' or hand-holes in the-heads 4and sidesfof the iphragn l i Zales It ,iw'hichrprodueeta fmfthprjcearversi casing, and."i'fnecessary, inone or -morediaphragms, which man-holes or hand-holes are provided with suitable covers, readily detachable. In cases where pipes are employed exteriorto the casing, to carry the reverse steam flow for one or more reversed drum stages, these pipes may be connected with turbine. This .feature of accessibi ity to the diaphragm bushings is also applicable to the reversing turbine.

The features of the invention herein'Set forth are applicable to various turbine arrangements, some of which will form the subject of separate applications for patents. In the present case, Athey are shown in the drawing applied to a simple form of vturbine, in 'which all the elements, includin' the reversing turbine, are mounted upon a singleA shaft, and inclosed by the'same casing.

In the drawing, Flgure 1 is an elevation with the upper half in longitudinal section of a simple :form-of turbine embodying my invention. Fig. 2 is a plan view on asmaller scale of the turbine in outline showinV the, relation thereto of the pro eller am? the thrust block. Fig. 3 is an e evation of theorward -head of the turbine vwith the upper and' Fig. 4 is a vertical lateral section of the turbine on theline in Fig. 1.

The rotati elements are mounted upon a vshaft 5, -wh e the stationary elements lare attached to a-'cyl-indrical casing whose sides are indicated at 6, Vand whose .forward and aft heads are limiicated by 7 and 8. A-t the forward end lof the casing are two wheels 9.,- 10, -whch are mounted upon steps formed fon the shaft, which is reduced in diameter at. the poi-nt 11, where titi-passes through the stuing box 12. The d' erenee in diameter vwheeLlO .at the point 13`pro'duces .a thrust which opposes the Y:propeller t rust. The wheels 9 and 10 carry preferahl-. a

rated' 2b stationary intermediate buckets carried y thecasing. 'The Aisteam in the .are

,hawaii vuit sima a .11 enav the hub' af the ris' -a-rea subjected to thearst stage pressure',

steam .chest .14 epasses Ynozzles l5,- which .nozzles convert velocity',

f and, deliver the steam' to a partei :the iperiphery of the wheel '9. The .steam p'reure on opposite sides-ofthe .wheel 9 ls'the'sam'e. Betweenthe .wheels..9 and' :10 Tis the da 16, 'the vsecond stage non# of pressureA into velocity 'and deliverlthe steam to'a part 4of the periphery of the second wheel l'lhfwhich operates `like the first wheel 9 on the impulse principle, a ,d has the same pressure on opposite sides" The diaphragnrl is .supported by n the casing, and is subject` i the vdifference @in pressure between the` rst and second wheel stages. lV here itl-surrounds vthe'y lshaft it is provided with amfdfiaphra m bushin 18, which may be any -lsuitab e' form o diapliragmbushing, orf by reason ofjthevaccessibility for replacement, may be some` form of packingmmaking actual contact with the shaft vor theiwheel hub. The space 19 in front of the, -iaphra"gml16 is made large enough to permit the removal'and replacement in segments of the diaphragm bushing or packing 18 Withoutl removing the casing or the' further separationof the `wheels. Access'is given to the s ,ace` 19 by and-holes" means of covered man-holes or 20 (one or more) in thecasing head 7, and

through one for more openings v21 in the webof the wheel 9. Access to the'bushin of the diaphragm following the iristwhee stage is important, because' the first stage pressure ispresentat this bushing and the steam leakage at this point is greater than at any succeedin phragm 16 may a so'be provided withcovered man-holesA or hand-holesl22v (one or more) to give access throughdhe or more openings 23 in the web'ofl-ivheel 10 to the space 24 in front of diaphragm 25, which in the .form of turbine illustrated, closes .the

\ interior of ,the casing following the second mediate buckets carried wheel stagey and precedingthe first drum stage iny orderfthat the steam flow through the first drum stage 'maybe reversed; The drum 26 of the first drum .stage is supported upon the shaft by a steam tightshead 27 having the proper strength to resist the steam pressure difference to which it is subjected without change of shape. The drum 26 carries a number ofV annular rows of moving buckets, separated by stationary interthe flow of the steam through these buckets is a forward one from the space 28 toward the head of the machine, instead of a flow toward the aft end of the machine,vas in the wheel stages. The admission ,of steam to `the buckets of the first drum stage is av combf the diaphragm 25 to plete peripheral admission, andthe buckyt'the casing, and' diaphragm. The diay ets of this drum stage may operate upon thev impulseprinciple or upon the reaction pr.1n,` `ciple. The result in either case is a considerable reduction in pressure be't-ween the space 28 aftl of the head 27 and the space 29 forward of that head. l

To secure the reversal of the steamthe steaml may be conducted` after leavijigif,ifi the propeller thrust a1 'alldsubstantia the wheel, stages from the pace24 yin front e space 28 by means of pipes`30 `eater-i )r to the casing. The thrust produced by the difference in steam pressure upon ,the l ead 27, it will beV seen, is in a forward dire1tion., the same as` inner opening surrounding the shaft and accessible in the space 28. 'I his diaphragm 31 i closes the space between t] te casing and the shaft between the first a ud second drum stages; The spaces 24 ald 28, which are.

connected by the exterior I ipes 30,"are'large spaces, whlchin a high power `turbine would be 'large enough to i dmit .thebody of a;workman, and by removi 1g any one of the pipes 3Q, a Workman can nter these spaces to repair or replace the bushings `or packings carried by thediaphi agms 25 and 31."y

The steam, y:after passing `:hrough the first: drum stage, enters an am lar space 32 in the shell, which is conne :ted by channels 33 with the space 34 back 1 f the diaphragm 31, which space forms tht entranceA to the second drum stage. The drum 35 of the second drum stage is sup ported from Ithe `shaft in 36, whic is formed to witl lstand the differ-A ence in pressure to which it is subjected without change of sha its afi or rear side facingl a space 37, w ich is cc nnected'with the ex aust 38, so that the hea d 36 is subjected part by means of a steam tight head on its forward side to the admission pres- 4 sure of ,the second drum sta ige, and o n its, aft

side to the exhaust pressu e. The hubsy ofv the drum heads 2T and 361 neet on the shaft and are surrounded by a stl ain ring 48 which tsover shoulders on the h lbs of 27 and 36. Thls strain ring forms a true surface, facingthe bushing of the diaphragm 31 and also tends to prevent separa tion of the ,eads

27 and 36 whlch are subject ed to steam res-l sures fending to separate tziem. The 'um 35 ofthe second drum Stage carries, like that of the first drum stage! h nl i ber of annular rrows of buckets separated 1 10 intermediate 1ng,and operatingy on the im' uls'e or reac-' f tkm thrust, and opposed stage, results in the practic l neutralization one way or the other, is tal by the upon them, that thi forward thrust. v produced by the ha 2(v ofthe first drum lso I of l22,000 S.

.block 39 (Figf2). In 2 the shaft developing at `full power 11,000 S. H.

Ato be at,r full .gi ving a y Under .these conditions,'witli a pro ulsive eiciency of 60%, vthe thrust lofweao `pro-k y peller Vwill be 86,000 lbs. kat. -full power and 26,500 lbs. at 20% power. "In thisexainple,

the moving buckets of -the Vdru'in stages lare considered as operating on the impulse ,principle. In the steam chest supplying'the vfirst `stage nozzles, the steam pressure may 1 for illustration, 200 lbs. (absolute) yand 40 l". superheat and the ex'haustpressure of the turbine 28 inches of vacuum or about`one pound absolute, the latter pressure acting on the rearward side ofthe second drum stage.

Let us assume that the first `stage essure, acting on the shafttlirust area, is igned ower -100'lbs. (absolute) and the second wi ressure Von the Lac'lmission side of the first, 4um stage of about 72 lbs.- This pressure 'being. rixed,` and yayconvei'iien-t pitch diameter fort-he two drum stagesbeing selected, say, for, example, v8"V feetyand 9*,.feet respectively, the pressures necessary on the two sides v'of the'drum heads 27 and 36 to balance the lthrust-can ibe readily calculated` when the areas subject to .the steam pressures are known.V The shaft vthrust area which lreceives 'the firststage pressure alrac'ly assuined :to `be '100 lbs. absolute, is ound'by computing the varea of the `aiinulus formed-by vthel smallest and 'largest diameters of the shaft subjectto this pressure, Awhich .may be,

' for example, 22 inches andr32 inches respec-A end of second drum en# the shaft,

tively, giving'an area Vof 424 square inc hes. The areas -,of the high and low ,pressure sides -of Athe first or' reverse .stage will lbe :found to be respectively r6,104 square inches and 6,434 square inches, andthe areas ofthehigh and llove-pressure sides of the second or direct drum stages will be :found rte be respectively-'8,027 square inchesI and 48,545 square inches. 'Starting with a ksteam res- -Esure o72 llbs. y,hi pressure si e of with :an exhaust' gpresauresvneces'sary .tio

the figstdrum .m i ressureof l vlli.,=t i Ymaintainedlon Vtheflow'y rassure side of lthe:rstdruinet, anden.k e'h'A pressure sideof the 'to i lance';the

4thrust under :f lie'feondit'ions l'will :be I*found to .be'about'34jlbs L'Illi'ispressure will' reverb prupomnns be :maintained thefurea ofthe b e gap at the `admission aref The steam 'tamtam mi einen? uma .low pres-' sure lsides adffffthe 'two `drum stages :at the ofthe propeller eel stage x pressure 72.5 lbs.,

.and 20% Vpower respectively? From this table it willbe seen'that at full power there kis analmost exactrneutralization of the thrusts, including the propeller thrust, anditisevident that by further refinement, an exact neutralization j could be forward 'thrust lindicated by the table is so small that it can ibereadily takencare of by fthe' lthrust block. As showny by the table, when the report-ions lare those specifically stated, t e l,tendency is for the unbalanced thrust lto approach in amount the propeller thrust at low powers, but this is not im ortant because the unbalanced thrust is Smal and can be readily taken care of by' a Athrust block of convenient size.l At al Substantial powers .the pro ller thrust is Wholly orlargely neutralize It is evident that the areas and steam pressures may neutrahzationor` of -minimumfunbalanced thrust will be 'at either end of the power range,-or atsome yintermediate point, orso jthat at fall'powers y.there will be a resul-tant thrustin the block. l A -l The reversing turbine, which is 'shown to :the left-'in 1, is of the simple construction already referred to, having two wheel stages 41, v42 and one intermediate rdia- ,phra 43, to Vthe vbushing or packing of whi access is had by covered man-holes or opening 45 in the wheel 41, in the same wheel at the head ,of .the turbine.

stage '46 which discharges into 'fthe exhaust 88. VIliexlrurnstage 46 ofthe reversingturbine `vis `inade 'of'srnaller diameter 'than the stages of the vgro-ahead turbine, and head 47 has a smaller `area so as to approximately .neutralize the ,propeller under the-conditions of operati u vof fthe memingfturbine. This also fbringsthe Full thrust. m, power thrust.

Forward. Art.- Forward. Aft.

basan 164,000 158,800

The second wheel stage of the reversing. iff- '-turbinedelivers the steamdirectlyto aldrum fa,-

25, 215,103, 10.2- and 0.74.

thrust in -pounds atfull `power secured. At 20% power, the unbalanced be proprtioned so that the point of exacta' same direction on the vthrust l hand-holes 44' in .the L'casing head 8 and :manner-.asexplainedinconnection with therv f diaphragm Avbetween fthe-first and second 12.

I:site directions and producing a resultant" dischar e of steam from the two turbines out 'of ine so that there is a. free passage for the steam from the ahead turbine into the exhaust.

, What I claim is:

l. The combination with `the propeller and propeller shaft of a ship, of a steam tule bine directly connected with said propeller shaft, said turbine having reversed drum pressure'stages exerting thrusts in oppo-l thrust opposed to the propeller thrust and` varying with the load so .as to wholly or pressure stages, the latter exerting (and propeller shaft lai-gel neutralize the propeller thrust 'atv all su forth. i

2.V The combination with the` propeller and propeller shaftof a ship, of a stealnturbine directly connected with said propeller shaft, said turbine having one or more ini-1,

reversed drum tial jet wheel stages and 'thrusts' in opposite directions l ,and producing a resultant thrust opposed to the propeller thrust and varying with the load so as to wholly or largely neutralize the propeller thrust at all substantial powers, substantiallyas .set forth. v

3. lThe combination with the propeller of anship, of a `steam connected with saidv pro-y peller shaft, said turbine having one ormore initial jet wheel stages, a reversed drum pressure stage producing `a thrust 'in the same direction4 as the propellerthrust and a turbine directly direct drulndpressure' stage producing a thrust o pose to the propeller thrust andl greater t an the-thrust ofthe reversed drum stage, whereby` a resultant turbine thrust' will be ,produced opposing the propeller thrust and varying with the Yload so as to and propeller shaft of a prodwng'. Q Y propeller trust landvarying -with the load so as to wholly or largely neutralize the pro- 'p'eller thrust at all substantial powers substantially as set forth.

5. The combination with the propeller and propeller shaft of a ship, of a steamtun bine directly connected with said popeller shaft, the shaft within the turbine reduced in size at itsends and seid turbine avf uvtcent'eaeli, by addressing the' "C4 mniissienerof latenti Whittington, D. C." A i j Copie: of this patent may be obtained im' stantial powers, substantially as ing one or more `in tial jet wheel stages the team ressure in which acts on the shaft pr thrust, and reversed exerting p p producing with s aftthrusta resultant thrust opposedtothe propeller thrust and rum pressure stages uce a thrust opposed to the propeller thrusts im opposite' directions and Vrvarying with 'theluad so as to wholly or largely neutralize tl propeller-thrust at all ubtslantial powersr substantially as. set yor 6. In a st eam tt rbine, the combination .withthe casing, the shaft and the rotatin @diierent steam ldiaphragms supporxed by the casing for 'separating theastag is having bushings or packings surroundin `tween the diaphragm 'for" enablin the d a hragm bushings or ackings to repaired) ismantling the turb ne,and means for givf forth. y .7. In a steam tux-b; ne,

wheel stages and separated. from Ithe wheel by a space packin and one or more openlngs in the head o the casing an d in the first wheel to give accessto this sp ace, the head opening or openings being co1 ered', substantially asset forth. p

8. In' a steam turl line, the .combination sep arating sta es, of one ox-inore coverV openings in the iaphragm for giving access to interior spaces of the turbina-substantially is set forth'.

9. In steam'turbii e, thecombination of a drum stage,.diaphi argms separating the i ing and succeeding with a diaphra .drum stage from prec i k stages, a working' spa( e on one side `o`f eac diaphragm and openin gs in the sides of the casin giving aoss `;o`-. such spaces, sub- V 11.0

stantially 'as-set forth. v

10.1.Ina steam turb ine, their-combination with lftheshaft and cas n of a lurality of wheel stages and a plui ity of rum stages, diaphragms` separating the several stages and bushedor packed. working spaces separa ing the diaphragms from rotating element: andcovered open g the shaft, spacesbes and rotating elements v 0r replaced without ing access to such spe ces, Vsubstantiallyas set la: e enough to permitmanipulation `of -the ligaphragrn bushing or around theshaft,

bucket elements divi led into stages in whic pre s'sures are maintained,-

, uw cambiano off" wheel stages located yadjacent the head of4 the casing, -a `cliapl ragm separating ings in .the heads and si des ofthe-casing foigiving aecessftcjsuchworking stantially-as set 4 This. specification si, :ned andwitnessed this 15th day ofNovem ber, 1910. y f;

` CHAR] ES G.

Witnesses Jorrit L. Lomax.

GUs'rAv A. Mex.

spaces, sub#