US1008530A - Marine steam-turbine. - Google Patents

Description

C. G. CURTIS.

` MARINE STEAM TURBINE.

APPLmATIoN rILBD Nov. 19, 1910.

Patented Nov. 14, 1911.

4 S IEETBSHEET 1.

0. G. CURTIS. MARINE STEAM TURBNB. APYLIGATION FILED Nov.1s.191o.

Patented Nom-'14, 1911.

4 E NIETS-SHEET 3.

:Inventor @wy/@ir Witnesses C. G. CURTIS.

MARINE STEAM TURBINB.

APPLIOATIQN FILED Nov.19,1910.

L 1 9 1 4, ,1 V. N d nu t .n ...u na D..

4. T E E u T E E H s l.

i Irwentor C@ qm N HW Attorney.

UNITED sTATEs PATENT oEEIoE.

CHARLES e. CURTIS, or NEW Yonx, N. Y.

i l MARINE STEAM-TURBIN E.

Specification of Letters Patent.

Patent ed Nov. 14,1911.

Application led November 19, 1910. Serial No.' 593,160.

7,'0 al( whom it may concern: i

Beitknown that I, CHARLES G. CURTIS, a citizen ofthe United States, residing at New York city, in the county and State of New York, have invented a certain new and useful Improvement in Marine Steam-Tui'- bines, of which the following is a specification.

` thrusts, including that of the propeller, by

reversed drum pressurestages, set vforth in that application, is made useful in a marine steam turbine having turbine elements operated at different steam pressures-on the same shaft. In a turbine o f this, character it is important that the two elements of the turbine on the same shaft should be independent of each other with respect to longitudinal expansion and contraction, and hence it is usual to dividethe shaft between the two elements and connect the two sections of the shaft'together by a coupling permitting a. longitudinal slip. The two shaft sec-v tions are held against longitudinal movement by independent thrust blocks and the propeller thrust is taken only by one section of the shaft. Heretofore -in the construction of marine steam turbines o f this character having initial jet impulse stages, and built in two elemen ts complete on one shaft, it has been the practice to employ in the high pressure element a number of wheel stages only, which, having ythe same steam pressure on opposite sides of the wheels, avoidthe production in this yelement of excessive longitudinal thrusts which .would have tov be carried by the .thrustblock and which reduce the steam .pressure to the low pressure' re- 'quired to neutralize the propeller-thrust;

and toemploy in the low pressure elementa drum pressure stage, having a steam tight pressure @head closing Ithe steam `space between' the 'l1-'um ,andf the shaft, and producing afthri t opposed to the propeller thrust.

cated is Aopen lto the .erablenumber of e diaphragm andsteam spaces which increase the cost and length ofthe turbine, and, on account of the inaccessibility of tie diaphragm bushings, increasethe diiiic ilty and expense of, repairs. By my presen 1 invention these obreversed and are so proj )ortioned relative to the steam pressuresthat the thrust produced by one drumstage is pr Lctically neutralized by the other drumstage, andthe shaft thrust when present is also prf ctfioally neutralized,

" jections are overcome by replacing the wheel Astages inthe high pres :ure element largely or partly by drum ress ire stages with steam jtight pressure hea s, wl Aich drum' stages are -65 at all substantial power s,'so thatthe thrust carriedfby the thrust bl( ck for this element if any, ,is small in amo int. The propeller thrust is Wholly or'laigely neutralized at all4 substantial element by a rsingle di rect drum pressure stage.,

'A further feature of t le present invention relates to means for vadusting the relative thrusts of the reversed drums in 'the high pressure element so as tc secure amore com- 'plete b alance in this eler Lentr under different conditions of steam flow ind pressure. This is accomplished by rov ding a by-pass for the steam, eontrolle by i. valve, around one or each of the drum stag es so as to vary the pressuredrop between tl e ends of one or of c ach of 'such drum-stage; to suit the conditions of operation. y

Another feature of i Lvention relates to the| construction of the improved turbine for a 4-shaft arrangemer t.- In carrying out this part of -the inventio i the turbine is divided into'four element; mounted on two shafts, .e., a high press ire element on one shaft, an intermediate pressure element on the other shaft of the sain( pressure element and ta [ring the full flow of steam from the hi h pressure element,

and two low pressure e ei cents` (one on each shaft) which receive-th steam flow from owers in the low^pressurepowerA as the highthe intermediate pressur element in multiple. AThe high and intermediate pressure elements are balanced `wizhin themselves `by 'the use of reversed druin pressure stages,

while the two low pressu e elements receive a low enough steam pre: sure to wholly or largely neutralize the ti'rust .of the propellers at all substantial )owers by the ernployment in each of a single directV drum pressure stage. ,y

The invention is illust ated'as embodied nal half section v,of a four-element i and 5),.

`through the stuffing boxes, producingshaft at 11, 12. The high pressure element, as

in two forms of turbine, Figures 1 to 6 showing a turbine composed of a high and a low pressure element complete. on one shaft, and Fig. 7 showing a turbine of four element divided between two shafts.

In the drawings, Fig. 1 is a side elevat-ion, of the high pressure element of the turbine complete on one shaft, 'with the upper half in longitudinal section on line -l-1 in Figs. 4 and 5;l Fig. 2 is a longitudinal sec- 'tion on line 2-2 in Figs. 4 and 5; Fig. 3 is a Referring particularly to Figs. 1 to 6,

A and B are respectively the high and low pressure elements of the turbine.' I will first describe the high pressure element of'ithe one-shaftV form of turbine (Figs. 1, 2, 4 Its shaft scction'7 which carries the rot-ating partsis preferably stepped 'downto smaller diameters where it passes thrust areas subject to the'steam pressures at the ends of theshell.A The sides 'of the 'shell or` casing are shown at 8, its forward andv aft heads at 9, 1() and the stuffing boxes shown, is provided with two initial jet wheel stages. The nozzles 13- of the first stage are carried by .the head 9. The wh'el 14 Aof the first stage carries, preferably, a plurality of Y' rows of moving buckets co-acting with stationary intermediate buckets carried by the shell. Following the wheel 1.4 is a diaphragm 15 supported by the shell and having a bushing or packing surrounding the shaft. The space in front of the diaphragm 15 is large enough to permit the removal and repair'of the bushing or packing in segments, and access is oiven to' this space by I hand-holes or manholes 16 in the head. 9

and by `one or lnore Y openings 17 in the web ofthe wheel 14. The

. -dlaphragm 15 carries the second stage n ozzles '18, and .these deliver the 'steam tothe buckets' of the second jet wheel stage whichar'e carried by the wheel 19 and by the shell.

The-wheel v19 is mounted upon the pressure' head'20 of the first' drum pressure stage,

. which pressure head is formed and propor- 60 shape'the difference in pressure to which it tioned so as to withstand without change of is subjected. The drum v21 of thejirst drum stage -is supported inl art-by the'head 20 whlch' closes .steam tig t the space Abetween the drum and' the'shaft. 'The first 'drum' 'reaction principle.

stage carries the steam' in the same direction as the initial wheel stages and receives it directly from the second wheel stage. The' drum of the first drum stage carries a number of annular rows of buckets separated by annular rows 'of stationary buckets carried by the casing. TheseJ buckets operate on the impulse or on. the reaction principle. In either case there is a diffrence in steam pressure between the admission and discharge ends of the drum stage which is effective on' the head'20 to produce" an aft thrust on the shaft. As will be understood the admission-V of steam tothe buckets of the rst drum stage is a complete peripheral one, vwhile at the wheel stages the nozzles occupy only' apart of the peripheries of the wheels. In passing through the wheel stages the steam is reduced in pressure and increasedin volume so that a complete peripheral admission can be had atthe first drum stage with buckets of a sufficient` radial depth to keep the tip clearance leakage' within permissible-limits. y

The radial dept-h of the buckets of the wheel stages can be made as vgreat-as desired because of the fact that a partial peripheral admission e., jet admission) is employed in these stages." `The-use of the initial ]'et wheel-stages also results in a reduction in pressure within the casing head* to thatwhich can be practically controlled by the shaft stuing box.

' Following the first drum stage, the steam space between the shell and the shaftisV closed a diaphragm 22'having a bushing surrounding the shaft. A working space is provided in which this bushing or packing may be-repaired or replaced in segments, which space isaccessible through a Vcovered man-hole 'or hand-hole'231in the casing'.

The ldiaphragm 22 is made necessary because the steam flow is reversed through the second drum stage.' rIhe second drum' stage Vhas a' drum 24 carrying` a number of :annular"rows. of buckets eo-acting witlrannular rows of intermediate buckets carried by the casing, andv operating r on the impulse or In .either case, as with the first drumstage, there is a difference in steam pressurebetween 'the Aadmission and discharge ends of the'stage which'is effec- Ative on a steam tight pressure head *25 closing the space between the .drum and' the shaft and formedand-proportioned to withstand the pressure difference to which it `is subjected without changcof'shape. The

steam is admitted to the aft end of the second' 'velocity stage by channels 26 in the' Casing (Figs' 2, ,4 and 5) connecting the space'in frontof the diaphragni 22 with the A spaceaft of the pressure heady 25, while the steam-*discharged from this `stage into the space forward ofthe head 25 is carried back to the 'chamber 27 in" th'e aft head 1 0 of the high pressure element by channels 28 (Figs. 1, 4 and 5). The difference in pressure on the shaft thrust areas and the ditf ference in pressure on the first drum stage produce an aft thrust oir the shaft, Whilepowers, so that the unbalanced thrust, if

any, will be small.l In order to secure a more complete balance of the thrusts under different conditions of operation acontrollable 'by-pass may be provided around one or each of the drum 4stages solas `to enable the adjustment of the differences in pressure carried by the pressure heads 20 and 25. A pipe 29 having a valve 30 'performs thisoflice for the irst drum stage, while an opening 3l (controlled by a' valve 32) he- `tween the chamber 27 and the admission side ofthe second drum stage serves toV 'shunt steam around the second drum stage.

The shaft section 7 of the high pressure element A, is connected with the shaftv section 33 of the low pressure' element Bby a slip coupling 34. The casing 35 of the Vlow pressure element has fore and aft heads 36, 37, provided with stuiing boxes 3S, 39, preferably surrounding reduced diameters of the shaft. One or fmore pipes 40 convey the steam from the chamber 27 of the high pressure element tothe fore head of the low pressure element, and have a slip A.or expansion joint 41 permitting the relative movement ofy the two` elements. Within the casing of the low pressure elementis a drum pressure stage havin a number of annular rows of moving and stationary buckets operating on the impulse or reactioujprirr ciple.` ,The drum 42 of this drum stage is supported from the shaft in part by a steam tigl'it pressureY head 43 formed and proportioned to withstand the difference 'in pres sure to which it is subjected without change of shape. The pressure head 48 is subjected. onl its forward side to the steam pressure existingat the admission end of the drum stage while its rear side is open to the eX- haust 44 and hence receives the exhaust pressure. i steam passage area through this druml stage4 and by giving it a proper thrust area, the thrust aft produced by it wilTbalance practically, or reduce to a jjaacticable a'l'upunt,

at all powers, the forwardthrust of the` propeller (not shown.) which is carried by the shaft Any llnl'ialanced thrust, one way or the other, will be small. ln Fig. 6

By properly1 proportioning .the

the 4high and low prf ssure l eleinents are shown assembled, the t'irust blocks 45,- 46, Afor the sections 7 and 33 oftheshaft being illustrated. These thru ltblocks may be located eitherat theyfor vard or aft end of either element. `The .reversing turbine is shown as "'"inclosed in tie rear-end of the casing of the low pressi] re element'. As will be understood, it hasa. lrum pressure stage opposing the propeller hrust Y The yturbine shown in Figs. 1 to 6 is use-r ful in any arrangement of one or more propeller shafts, in 'which' it is desired to ern-` ploy a complete indepen lent turbine on each shaft.

A special constructi )n of the turbine adapted for a *fl-shaft arrangement is illustrated in Fig. J7, to Whic 1 reference -will now p be made. The turbine is divided into four elements, C,'D', E and F. The elements C andD are respectively iigh and intermediate pressure elements, tie latter taking the entire flow of steam fro n the former, while the elements E and F 2 re low pressure elements which receive the steam from the intermediate pressure elerr ent in multiple, each `taking one-half the How of steam. The elements G and D are (f practicall equal power, as likewise are tl e elements L and F,

.so that the power deve oped oneach shaft will be the same.'l The l wo shaft sections of 47, 48, and the slip coup] llng connecting them is shown at 49. The hi` gh pressure elel'nent, shown, has one jet wheeljstage 50, al'- though it may have tw 3 or more, and two drum pressure stagesll and 52 separated by a diaphragm 53,`and co1 nected so as to have a reversed steam flow t v pipes or channels 54. Tiese drum stage; have steam tight pressure heads 55, .56, `vhich exert thrusts upon the shaft section 47. inopposite directions so to practicallyi .eutralize the thrust within the Ahigh pressurl element of the turbine at all sllljistantial powers, as described in connection with Vthe high `pressure element A. The j low pi `essure element E, which is mounted on th shaft section 48, is similar in constructipn, tothe low pressure element B, already desc 'ibed, having a siu gledireet drum pressuri ,stage proportioned with respect to the area of its steam passage stautial powers. The s laft sections 47 and 48, it will be understoo( are provided with 'the high pressure element are indicated at independent thrust bloc lis, as illustrated inV Fig. 6. The intermedi: te pressure element l) receives` the `full tlow of steam from the high pressure element tirou'gh one or more rpipes 57. This element is provided withy i two drum pressure stage having steam tight pressure heads 60 and Gl, separated by a diaphragm 62. .The d1 um pressure stages '58, 59 receive the steam flow 1n opposite d1- rections, the discharge end of stage' 58 being connected with the head en d of stage 59 by steam channels 63. The reversed drum pressure stages 58, -59 are proportioned so as to produce thrusts in opposite directions and to practically neutralize at all substantial powers the thrusts upon the shaft within this element of the turbine. The rotating parts of the elementv D are mounted upon 'the shaft section 64, which vis connected with the shaft section 65 by a slip coupling 66. The low pressure element F, which is mounted on the4 shaft section 65, is similar to the low pressure element E, having a single direct drum pressure stage with a steam tight pressure head adapted to practically neutralize the propeller thrust at all substantial loads. vided with independent thrust blocks Asimilar to the shaft sections 47,1 48. rIhe exhaust from the intermediate pressure clement is divided between two pipesl G7, 68, which divide the steam iow between the two low pressure elements E and F, giving the large bucket areas required to pass the steam at the low pressure and large volume existing ncar the exhaust end of the turbine. It will be understood that the shafts shown in Fig. 7 are two shafts of a li-shaft arrangement, and that the other two shafts will be provided with a similarly divided turbine.

Vhat I claim is v l. In a marine steam turbine having elementsoperated at different steam pressures mounted on the same shaft, the combination of reversed drum pressure stages in one element, producing thrusts in opposite directions, and a drum pressure stage in the other element producing a thrust opposed to the propeller thrust, substantially ,as set forth.

2. In a marine steam turbine having elements operated at different steam pressures mounted on the same shaft, the combination of one or more initial jet wheel stages and reversed drum stages in the higher pressure element, the latter producing thrusts in opposite directions, and a drum pressure stage in the lower pressure element producing a thrust opposed to the propeller thrust, sub# stantially as set forth.

' 3. `In a-marine steam turbine, the combination of two elements operated at different steam pressures mounted en the same shaft, a slip couplingl in the sha-ft between the elements permitting the independent longitudinal movement of the two elements, separate lhrust blocks for the two shaft sections, reversed drum pressure stages in the higher The shaft sections 64, G5 are pro-V pressure element, producing thrusts in opposite directions, and a drum pressure stage in the lower pressure element producing a thrust opposed to the propeller thrust, sub-v stantially as' set forth.

4. In a marine-steam turbine, thecombi- `nation of -a drum pressure stage at the eX- haust vend of the turbine producing a Ythrust opposed to and practically the same as the propeller thrust and preceding drum pres- ,I

sure stages reversed with respect to each other and producing opposite and pr'afctif' cally equal thrusts', substantiallyas. set forth.

5.' In a steam turbine, the combination of reversed drum pressure stages exerting thrusts 1n opposite direetlons, and a controllable by-pass for the steam around one elements mounted on different 'shaftsfeachhaving reversed drum pressure stages pro.- ducing thrusts 1n opposite directions and two low pressure elements mounted onthc,

different shafts and receiving the steam flow in multiple from theintermediate pressure element, each of said low pressure elements having a drum pressure stage producing a thrust opposed to the propeller thrust, substantially as set forth.

8. Ina marine steam turbine, the combi nation with two shafts, of a high Apressure' turbine element on one shaft, an intermediate pressure turbine element having reversed drum pressure stages on the other shaft receiving the full How vof steam from the high pressure element, and two low pressure turbine elements mounted on the two shaft-s and receiving the steam flow in multiple from the intermediate pressure element, substantiallyas set fort This specification signed and witnessed this 15th day of November, 1910.l

CHARLES-e. sumas.

Witnesses:

yJOHN L. Lo'rsoH, GUsTAv A SoHELLAoK. Y

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

../Washington, I). C.

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