US1722721A - Compound turbine - Google Patents

Description

2 July 3o, 19:29.-

H. H. WAIT 1,722,721

COMPOUND TURBINE Original Filed March 20, 1923 5 Sheets-Sheet l BY v I; "2 ATT RNEY.

July 30, 1929. H. H. WAIT I couPouND TURBINE Original Filed March 20, 1923 3 SheetST-Sheet INVENTOR. .ffr

AT ORNEY.

H. H. WAI'I coMPoUND TURBINE July 30, 1929.

Original Filed March 20, 1925 5 Sheets-Sheet 3 INVENTOR. .2Q/7% z ATT R'NEY.

m. v nu In. \N Mme y 4 55u55Mggvivw nwmwmonswiwm wFWHFFE vwv l Patented July 30, 1929.

UNITED STATES HENRY H. WAIT, '0F oHEs'rEnroN, INDIANA.

COMPOUN D TURIBIN'E.

Application filed March S20, 1923,'Seria1 No. 626,401. lRenewed May '21, 1929.

It is the object of my invention to improve the construction of turbines. More specilically, it is the-object of my invention to produce a compound turbine combining the aflvantages ot' the re-entrant type and the impulse type, and involving a high-pressure reentrant turbine wheel and one or more im'- pulse `turbine wheels operating at lower pressure, with a plurality `of separating diaphragms dividing the turbine into stages; to provide Aan advantageous and `compact arrangement of the return guides of the reentrant turbine wheel and the adjacent diaphragn'i, whereby the axial length of the turbine may be shortened, and yet the steam flow through the diaphragm may be interfered with as little as possible by the return guides; to provide a beneficial shroud arrangement for the 11e-entrant turbine wheel; 2o to provide an effective means for holding the diaphragms and shroud concentric with the shaft and casing, while still permitting the relative expansion due to their different temperature variations; and to provide a steamexhaust arrangement which will pe-rmit the steam to leave the turbine at either side, and to do so etliciently and without undue back pl'tSSlll'G.

The accompanying drawings illustrate my invention: Fig. 1 is a vertical longitudinal section through a turbine embodying my invention, taken substantially on the line 1-1 ot Fig. 2; Fig. 2 is a transverse section, on a somewhat smaller scale, taken substantially on the line 2 2 of Fig. 1; Fig. 3 is a fragmentary detail section, substantially on the line 3-3 of Fig. l, to show the mounting of the shroud in the casing to provide the steam passage around the re-entrant turbine wheel; Fig. l is a fragmentary enlargement of the upper part ot Fig. '2, to show the structure and mounting of one of the guidepins of a diaphragm on the shroud; Fig. 5 is a fragmentary development of the lowel part of the turbine, including the re-entrant turbine wheel and the lirst impulse turbine wheel, and two of the diaphragme; and Fig. 6 is an enlarged detail section on the line G 6 ot Fig. 5, to show the steam passages behind the return guides to the openings between the blades and the first diaphragm.

The turbine comprises a casingV 110 carrying a plurality of diaphragnis 11 12, and 13, which divide the turbine into a plurality of stages, there being three diaphrag'msfor the tour-stage turbine shown; and `Aa 'shaft 141-v which carries a plurality of turbine wheels 15,16, 17, and 18, four in number in such four-stage turbine, one in each stage. The diaphragms 11,12, and 13 are preferably of the rib-reinforced type which is set forth in my co-pending application Serial No. 620,263, filed February 20, 1923; but it is not essential that they be of that type. The turbine wheels are provided at or near their periphery with suitable blades 19 mounted in a suitable manner; andthe diaphragme are similarly provided with suitable bladesl 20; but the details of such blades 19 and 20 andtheir mounting form no part of this present invent-ion, and so they are not illustrated in detail.

The first or high-pressure stage ot my ,presentjturbind with the turbineiwheel 15 therein, is of the re-ientrant'type; but thel remaining turbine wheels 16, 17, and 18 are of the impulse type, and are separated from one another by the'diaphragms12 and 13, and as a group are separated from the highpressure re-entrant turbine by the diaphragm 11. This combination of a highprcssure ire-entrant turbine wheel with one or more lower-pressure impulse turbine wheels is a new construction, so tar as I am aware; and I have found .that it makes a most efficient combination for abstracting the energy from the steam and converting it into the energy of rotation of the moving element of the turbine.

The re-entrant turbine wheel 15 may be of any suitable construetion,' and the details of this re-entrant turbine wheel, per are not involved in the present invention. This re-en-tran-t turbine wheel 15 is supplied with steam on the high-.pressure side by suitable lnozzles 21, 22,'and 23,\the nozzles 21 and 22 being regular-service nozzles, and the nozzle 23 shown being -a supplementary or heavyload nozzle.` There may be any number of .these nozzles, though the Ydrawings show only three; and all three ot' these nozzles are shown as located -in the lower half of the turbine, at distributed point-s thereon as indicated yby the development shown in Fig. 5. Opposite -the `regular-s'ervice nozzles 21 and 22, in posit-ion to receivesteam passing through -the turbine wheel l5 from such nozzles, are re-entra-n-t guides 24 and 25. These, per se, maybe of any suitable character, with the usual intermediate crescent-shaped guide lates 26; and after receiving steam which lies enea'passed'-through the turbine wheel 15, they, direct such steam .back-into and throughsuch' Lfturbine wheel aisecond time, in the usual manner of reentranttype turbines. The steam after thus passilllgybacl through the re-entrant-type turbine wheel; finds its way around the oute1edge.of p n tends up beyond the horizontal dividing lme such wheel into the space 27 between such re-entrant turbine 4wheel 15,: and` the diaphragm 11, in which` space 27 the steam is .:.relativelyquies'cent. 1. .ep i

No return guide is ordinarily provided opposite the: supplementary or heavy-load nozzle 23, as that nozzle is only an emergency nozzle and is not primarily intended for regular use. Therefore, the steam from the nozzle 23 passes only once through the turbine .wheel 15, and from such turbine wheel is discharged directly into the space y27. Because the heavy-load nozzle 23 has'no re- -turnfguid'e opposite it, itv may be closer to the nozzle 22 than that nozzle is to 4the nozzle 21.

v"From the space A27, .the steam passes through suitable nozzle-openings between the blades in the diaphragm 11, into 'and through the turbine wheel 16'; then through s'uitable. noz'zlezfopeiiingsl between the blades 20 in the diaphragm 12, into and through the turbine wheel. 17;' then through suitable nozzle openings between the blades 2O in the diaphragm 13, into and through the turbine -Whelfl8g1and thence'into the exhaust space 28. In passing through the turbine wheels 16, 17, and 18, the steam acts on the blades 19 thereof in the usual manner of impulse turbines,-witl1 small pressuredrop; while in passing through the diaphragms 11, 12, and 13 the steam is expanded and speeded up lto the necessary -velocity to produce the impulse effect on the respectively succeeding turbine wheels.I

The exhaust space 28 is of considerable Isize between the lowest-pressure' turbine wheel 18 and `the end wall of the casing 10, and communicates at the bottom with a transverse chamber 29 passing from one side of t-he turbine to 'the other. f"This transverse chamber 29 is formed between the outer face of the lower part 10 of the turbine-wheel enclosure l() and the inner face of a 'lower downwardly bowed wall 30 Salso formed as -part of the housing 10. The chamber 29 is provided with horizontalv outlet openings 31 at both ends, or on bothsides'of the turbine. from either or both of which outlet openings the exhaust steam may be taken off though usually one of these outlet openings will be closed by a cap platef32, -and-thefsteamiwill be taken ofi' only from the other. This cap plate-32. is interchangeably mountable over either opening. This arrangement provides a convenient way of getting the exhaust steam' from the turbine .from either side as desired,with the same turbine-structure, and facilitates installation while avoiding the necessity for different.,structures 4according to thei-side from which.' the exhausti steam is to be taken.

`Both return guides24 and 25 are mounted in the'lower half "ofntle casing, in the construction shown; but the return guide 24; eX-

between the-,upper 'and lowerghalves of the casing, as indicated by the break in such guide at -the left'of Fig. 5. This is adesirable construction, thought it is not essential. In order to shorten the axial length of the turbine, and `reduce the distance between bearings, the return guides 24: and 25 extend into openings 35 provided in the diaphragm 11, as is clear-from Figs. 1 and 5. These openings 35 preferably extend throughthe diaphragme, for convenience in construction; but on their low-pressurel sides these openings`35 are closed by closingplates 36 suitably attached to the diaphragm 11 and preferably countesunk in the -low-pressure face of such diaphragm 11' so that they will closing plates 36farefrelatively -thin,'to allow as 4much space as possible for the return guides in the plane ofthe diaphragm 11,

and to provide a steam space behind such freturn-guidesl naar; Y Y

Thissteamspace is important, and'fis augmented by the mounting which lIv'provide for .the return guides. The 'return guides are supported wholly from the 'yinside, by inwardly projecting supports, shown as a .flange for each return guide. This allows the steam in the' "space 27 to pass freely around the outside of such return guides. Moreover, this support 37` for the return guides is not only from the inside, but is spacedv from the diaphragm'lL'by lateral lugs'or *posts 38,`which may be integral with such diaphragm. Thelange 37 is fastened to the diaphragm 1,1 at such lugs or posts by suitable attaching mea-ns,- such as screws 39and pins L10. 'The lugs or posts 38 are spaced inwardly lfrom the inner side of the return guide, to provide open spaces between. B reason of these lugs or posts 38, and of `t ie-'wholly internal support for the returnguides, the steam in the space 27 can circulate vall around suchreturn guides, and'into the spaces 35; so that the gaps in the series offblades 20 of Ithe diaphragm 11 -be iiusli with suchA low-pressure face: @The and in the nozzle spaces between such blades 'may be' as short circlunfe'rentially as pos- 'fthe return guides into t e plane of the diaphragm 11 `it may be possible to use almost the entire ycircumference of such diaphragm 'for the blades 20 and the nozzle spaces which they provide. l A

Around the'outer part oty the rel-entrant- 'type-turbine1wheel'15, I provide a shroud 45. "This isin general iU-shaped in crossvil section, with the base 'cumferentially surrounding the periphery V1., 'mare 1 of the U closely cirof the turbine wheel 15, and with the legs of the =U projecting inward as ianges from such base on the sides of such turbine 'wheel past the blades 19 thereof. The inwardly projecting flange on the high-pressure side is cut away 'to provide openings `for the nozzles 21, 22, and 23; and also to provide openings opposite the discharge parts of the return guides 24 and 25, so that there will be no backing up of the steam flow through the turbine wheel 15.A On the lowpressure side of the turbine wheel l5, the iange of the shroud is -cut away to provide spaces for the ret-urn guides 24 and 25. A development of this shroud for the lower part of the turbine is shown in Fig. 5; but the fia-nges are continuous throughout the whole of the upper half of the shroud, save where the toe of the return guide 24 projects upward into such upper half, which is beyond the left end of the development view lof Fig. 5.

In order that the steam which has passed twice through the re-entrant turbine wheel 15 may again pass by the plane of suoli turbine wheel `and into the space 27, I provide steam passages 46 across such plane outside of the shroud 45. These steam pas sages 46 are formed by making the shroud with an outer series of supporting feet 47 which bear against the inside of the casing 10, the passages 46 being between the feet 47, as is clear from Fig. 3. The outer edge of the shroud 45 is set in an internal eircumferential groove in the casing 10, and the diaphragme 11, 12 and 13 are set in similar internal circumferential grooves in such casing 10; but the groove which receives the shroud 46 diiiers from the other grooves in that it is wider than the part it receives. This is so that the side walls of said groove will not stop the passages 46.

By having the shroud 45, I am able to reduce the rotation loss incident to the reentrant turbine wheel 15. This reduction in rotation loss is augmented by an annular rib 48 on each face of the turbine wheel 15 just inside of the blades 19 of such wheel. These ribs 48 project axially into close proximity to the flanges of the shroud 45. The shroud and these ribs serve to break up the currents in the surrounding medium caused by the rotation of the turbine wheel 15; as in any such rotating wheel the steam in engagement with the surface' of the rotating` member is entrained and thrown outward, and this involves an iniow along the surface of the shroud 45. By this shroud and these ribs, the free How of this entraiued steam is largely prevented, and the loss caused thereby 1s minimized.

Each of the diaphragme il., l2, 'and lllantl the shroud 45 is supported concentrically with the casing 10, by a special supporting arrangement which permits the relative eX- pension and contraction of the casing 10 and such diaphragm or shroud. This supporting arrangement lis the same for each diaphragm and for the shroud, and therefore it is shown specifically only in connection with one of the diaphragme, illustrated in Fig. 2. Each diaphragm and the shroud is made in two parts, an upper part and a lower part, with the parting line substantially on the horizontal diameter. The outer edge of each diaphragm and the shroud is received in an integral groove in the casing 10, as already stated; and the diaphragm ts closely Within these grooves, because they must support an axial pressure which is at times very heavy, sometimes amounting to several tons; but the shroud is notsubjected to any such axial pressure, and for that reason also need not tit closely in its groove in the inner face of the casing. By this axial pressure, each diaphragm is firmly seated against one side wall of its groove. The two halves of each diaphragm or the shroud are held in proper relative position, with respect to each other, by one or more dowel pins 51. I prefer to use only a single dowel pin, as is illustrated in Fig. 2, though it is not essential that there be no more than one. If only one dowel pin is used, it may be any place along the parting line, although I have shown it near one end thereof. This dowel pin makes the 'two halves of the diaphragm, or of the shroud, expand and contract together horizontally. The lower halt of each diaphragm, or of the shroud, has near the horizontal parting line between it and the upper half two supporting and guiding 4pins 52, which project horizontally inward from the casing 10 into a horizontal hole parallel to such parting line, and fairly close thereto. The pin 52 preferably has a tight fit in such hole, but the fit is not sufficiently tight to prevent movement of the diaphragm or shroud on such pin longitudinally thereof. Preferably the two pins 52 are in alinement, though that is not essential. The diaphragm, or the shroud, may contract or expand horizontally, or along a horizontal diameter, vwith respect to the casing, but this horizontal diameter of the diaphragm or the shroud is held substantially co-incident with the horizontal diameter of the casing by the pins 52. Thus the pins 52 hold the diaphragm, or the shroud, concentric with the casing so far as vertical movement is concerned. To hold the diaphragm, or the shroud, concentric with the casing so far as horizontal movement is concerned, I preferably provide a guide pin from the casing into the diaphragm or shroud close to the vertical diameter. I have shown such a vertical guide pin 53 projecting from the casing 10 into the upper half of the dliapliragm, in

Fig. 2, andA doing i HTH-Unt so close to the vertical diameter. By this guiding pin 53, which is similar to the guiding pin 52, the diaphragm, or the shroud, is prevented from becoming centrally displaced horizontally with respect to the easing, so far as the center of the casing and diaphragm are concerned. In other words, the pin 53 holds the diaphragm, er the shroud, concentric with the casing, so far as relative horizontal movements are concerned. Thus the pins-52 and the pin 53 together' serve to hold the diaphragm, or the shroud, concentric both vertically and horizontally with respectto the casing.

One'of the pins 52 er 53 is shown in detail in Fig. 4. It comprises merely a pin driven tightly through a hole in the easing 10, and into an alined hole in the diaphragm or shroud. The outer edge of the hole in the casing is counter-sunk, and may be closed by a screw-plug 54, which is separate from the pin 52 or 53, and is merely a hole-closing device. To remove a pin 52 or 53,'the screwplug 54 is first removed; which renders accessible the outer end of the pin. lThen a threaded instrument is inserted into a threaded hole provided in the outer end of the pin 52 or 53, and such pin is Withdrawn. If desired, an additional hole 55 may be provided in the casing 10, and may also be closed by a screw-plug 54; and when this hole 55 is open it is possible to insert a pushrod to force the diaphragm-halfor shroudz" "'tweftheasing-halfirv'hb it is mounted. The hole 55 is also preferably located close to the vertical diameter, as is clear from Fier. 2. Such a push-hole 55 is especially desirable in the upper casing-half, where I have illustrated it.

I claim as my invention l. In a steam turbine, the combination of a casing, one or more turbine Wheels therein, a normally stationary annular part projecting inward from the casing but separable therefrom and movable relatively thereto upon relative changes in temperature and bearing axially thereagain'st on fiat surfaces on which the two parts are relatively slidable upon such relative changes in temperaturc. and supporting and guiding means projecting from said casing into said. a'nnular part wholly on two lines substantially perpendicular to each other.

2. In a steam turbine, the combination of a casing, one or more turbine wheels therein, a normally stationary annular part projecting inward from the casing but separable therefrom and movable relatively thereto upon relative changes in temperature and bearing axially thereagainst on flat surfaces on which the two parts are relatively slldable upon such relative changes in temperature, and supporting andguiding means rejecting from said casing into said annu ar part wholly on two lines substantially perpendicnlar to each other and close to the diameters which they parallel but spaced from such diameter in the case of at least one such line.

3. In a steam turbine, the combination of a casing, one or more turbine wheels therein, a normally stationary annular part projecting inward from the casing but separable therefrom and movable relatively thereto upon relative changes in temperature and bearing axially tliereagainst on flat surfaces on which the two parts are relatively slidable upon such relative changes in temperature, said annular part being divided substantially along a diameter, supporting and guiding means projecting from said casing into said annular part substantially parallel to and close to said division line, and another guiding means projecting from said casing into said annular part substantially perpendicularly to said division line and near the diameter which is perpendicular to the division line, said casing and said stationary annular part beingfree from interconnecting guiding means between themsave on the lines specified.

4:. In a'steam turbine, the combination of a casing, one or-more turbine wheels therein, a normally stationary annular part proj ecting inward from the easing but separable therefrom and movable relatively thereto upon relative changes in temperature and bearing axially thereagainst on fiat surfaces on which the two parts are relatively slidma mon www ture, said annular part being dividcdW stantially along a diameter, supporting and guiding means projecting from said casing into said annular part substantially parallel to said division line, and another guiding means projecting from said casing into 'said annular part substantially perpendicularly to said division line, said casing'and said A1stationary annular part being free from interconnecting guidingl means between them save on the lines specified.

5. In a steam turbine, the combination of a casing, one or more turbine wheels therein, a normally stationary annular part' projecting inward from the casingbut separable therefrom and `movable relatively thereto upon relative changes in temperature and bearing axially thereagainst on fiat surfaces on which the two parts' are relatively slidable upon such relative changes in temperature, said annular part being'dividcd' substantially along a diameter, sujiporting and guiding means projecting fromsaid casmr; into said annular part substantially parallel to said division line, and another lguiding means projecting from said casing into said vannular part substantially perpendicularly to said division line, said casing and said stationary annular part being `free from interconnecting guiding means between them save on the lines specified, and means for -llO interlocking the portions of said annular part so that such portions move together in their expansion and contraction.

6. In a steam turbine, the combination of a casing, one or more turbine wheels therein, a normally stationary annular part projecting inward from the casing but separable therefrom and movable relatively thereto upon relative changes in temperature and bearing axially thereagainst on flat surfaces on which the two parts are relatively slidable upon such relative changes in temperature, supporting and guiding means projecting from said casing into said annular part horizontally near the horizontal diameter, and a guide pin projecting from said casing into said annular part verticallyr near the vertical diameter, said turbine being` free from any guiding means between said casing and said annular part save at the places specified.

7. In a steam turbine, the combination of a casing, one or more turbine wheels therein, a normally stationary annular part projecting inward from the casing but separable therefrom andmovable relatively thereto upon relative changes in temperature and bearing axially thereagainst on flat surfaces on which the two parts are relatively slidable upon such relative changes in temperature, supporting and guiding means projecting from said casing into said annular part horizontally, and a guide pin projecting from said casing into said annular' part vertically, said turbine being free from any guiding means between said casing and said annular part save at the places specified.

8. In a steam turbine, the combination of a casing, one or more turbine wheels therein, a normally stationary annular part projecting inward from the casing but separable therefrom and movable relatively thereto upon relative changes in temperature and bea-ring axially thereagainst on flat surfaces on which the two parts are relatively slidable upon such relative changes in temperature, said annular part being divided substantially along a horizontal diameter, supporting and guiding means projecting horizontally from said casing into the lower portion of said annular part near the horizontal diameter, and a guide pin projecting vertically from said casing into the upper portion of said annular part vertically near the vertical diameter.

9. In a steam turbine, the combination of a casing, one or more turbine wheels therein, a normally stationary annular part projecting inward 'from the casing but separable therefrom and movable relatively thereto upon relative changes in temperature and bearing axially thereagainst on flat surfaces on which the two parts are relatively slidable upon such relative changes in temperature, said annular part being divided substantially along the horizontal diameter, supporting and guiding means projecting from said casing into the lower portion of said annular part horizontally, and a guide pin projecting from said casing into the upper portion of said annular part vertically.

lO. In a steam turbine, the combination of a casing, one or more turbine wheels therein, a normally stationary annular part projecting inward from the casing but separable therefrom and movable relatively thereto upon relative changes in temperature and caring axially thereagainst on flat surfaces on which the two parts are relatively slidable upon such relative changes in temperature, and supporting and guiding means projecting from said casing into said annular part, said supporting and guiding means being located wholly on two lines substantially perpendicular to each other.

ll. In a steam turbine, the combination of a casing, one or more turbine wheels therein, a normally stationary annular part projecting inward from the casing but separable therefrom and movable relatively thereto upon relative changes in temperature and bearing axially thereagainst on flat surfaces on which the two parts are relatively slidable upon such relative changes in temperature, and supporting and guiding means projecting from said casing into said annular part, said supporting and guiding means being located wholly on horizontal and vertical lines.

In witness whereof, I have hereunto set my hand at Indianapolis, Indiana, this 19th day of March, A. D. one thousand nine hundred and twenty-three.

.HENRY H. IVAIT.

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