US1896809A - Multistage turbine - Google Patents

Description

K Sheets-Sheet 2 Feb. 7, 1933. o. D. H. BENTLEY MULTISTAGE TURBINE Filed Maron 5, 1930 Feb- 7, 1933- o. D. H. BENTLEY 1,896,809

MULT I STAGE TURBINE Filed MaICh 3, 1930 3 Sheets-Sheet 3 Patented Feb. 7, 1933 W- UNITED :STATES PATENTQFFICE;

OLIVER D. H. BENTLEY, or NORFOLK,` MAssACiiUsETTsQAjssrGivoR To. n. F. STURTEVANT j COMPANY, or HYDE rARK, MASSACHUSETTS, A CORPORATION vor* MASsiioHUsiizTTs MULTTSTAGE 4Tnaiainn j Application led March 3,

Y The present invention relates to m'ultistage turbines.

The principalobject'of thepresent invenltion is to provide a multi-stage turbine of -5 high eiiciency and oi readily manufactured construction.

l With this and other objects in View, as will hereinafter appear, the present invention contemplates the provision `of a turbine having a plurality of rotors or wheelswith means for admitting the steam or other elastic Working iuid to the several rotors in succession according to the radial fiow principle. The radial low construction is common for single f vstage turbines, but for multi-stage turbines, the so-called axial flow principle is ordinarily employed. The radial flow construction, according to the present invention, is to be preferred not only because of s'uch manufacturing advantages as simplicity, compactness, and ease of assembly, but also because of the greater utilization of the energy of the fluid. In the accompanying drawings, Fig. 1 is a longitudinal `sectional elevation of the pre- '25 ferred form of turbine; Fig. 2 is a section on line 2 2 of Fig. 1; and Fig. 3 is a section on line 3;-3 of Fig. 1.

The illustrated embodiment of the' invention comprises a turbine havinga casing provided with an inlet 'steam chest 6. The casing is suitably lagged with heat insulating material 8. The shaft l0 is of usual form and is secured to a series of rotors 12 by keys 13. Each rotor has peripheral or radial flow l i? buckets 14. The buckets of the several rotors are of increasing size from the inlet to the exhaust end ot the turbine to accommodate the increasing volume of steam. rlhe last stage exhausts into an outlet chamber 15 -43 which is closed by a conical end piece 16 bolted to the casing. The usual glands or stuiiingboxes 18 are provided to prevent leakage along the sha-it. i

Fre-m the steam chest 6 the steam is admitted to the irst rotor through an annular passage 20. The steam from this rotor is eX- hausted radially into an annular inter-stage iiuid directing passage 21 from which it is admitted according to the radial flow principle to the next succeeding rotor. Other simi- Vby the rings 26 is a diaphragm or separating 1930.'` Serial gNo. 432,637.

lar annular inter-stage `Huid directing :passages 21 receive the exhaust steam from one rotor and-deliver itv toV the next in succession, until it is `finally*dischargedfrom the last P rotor into the .exhaust or outlet chamber 15.

OneofV thesepassages 21, namely," the passage be'ween the third and fourth rotors, is indicated at 22 in Fig. 2. lAll of the interstage passages are of similar form but are of increasing sizeV toward the exhaust end of` the turbine in order to accommodate the increased volu'me of steam as 4the pressure decreases. The annular inter-stage passages are formed in thejstjator of the turbine inthe P following mannerf Adjacent to the steamA chest 6 Va ring 24is vfitted vintothe casing "sur-` rounding Vand vclose to' thel rst rotor; A series of closely-fitted adjoining rings26 is received in the casing. Each ring has aninternal annular Vmachined groove 28 of general toroidal contourforming the outer boundary of eachinter-stage passage.V f -Each ring has an inwardly 'extending flange yportion 30.v Extending into each annular chamber" formed plate 32 vhaving an-outer -to-roidal surface defining' the inner bo'unding surface of Aeach inter-stage passagef Eachdiaphragm is secured to and spaced from the next preceding ring 26 by means 'of a plurality of bolts 34 80 and spacing washers 36, only one oi which is shown in Fig.f1. j"

As shownin Figs. 2 and, each ring 26 and each diaphragm32, as well "as the ring 2li4 `and the. casing, are constructed in two parts ysecured by bolting flanges 38 to facilitate assembly. The turbineV may be disassembled by removing the end cap 16 and separating the casing, after which the entire upper half of the stator, includingthe halfrings and half-diaphragms may be lifted off. Thel rings are tightly'secured against end- Wise' play by la plurality of pressure bolt as`- semblies, one of which isshown at 41secured in the outer Vend of the casing'and bearing against the outermost ring. l' i At the'center of each diaphragm is secured a serrated plate which engages and'wears into a soft metal bearing 425cm the'shaft to preventleakage of fluid along the shaft.` V 100 The several steam admission passages including the initial passage 20 and the entrance sides ofthe inter-stage passages 21, are yprovided with vanes to directthesteam into the buckets along nearly tangential lines. For the inter-stage passages,these vanes, whichY areiindicated at 44, are' milled or cut 4out of the outer faces of the diaphragms 32,

Each vane is therefore integral with the diaphragm and projects outwardlyy therefrom to engage closely with the'next adjacent of the rings 26. As shown in Fig.j2, adjacent vanes have parallel fluid directing surfaces,

and thus the vanes are Vnecessarily of taperedk form, being of less thickness attheir inner than at ytheir outer ends." The straight parallel sides'of the lvanes are of considerable length, lat least as great as' the perpendicular distance betweenadjacent vvanes, toy form a fluid directing throat. lEach vane is roundved at-its outer end 46 to permit non-turbulent entrance of VHuid .into the throat.`

The ring 24 on the inlet 'side (that is, the left side, as viewed in Figl), is similarly vformed with vanes extending intothev passage 20.

Thevanes44, acting'to direct-the fluid toy the rotor in a nearly tangential direction, form nozzles -which nozzles, however, are not necessarily of the expanding type. Straight sided nozzles, as shown inthe drawings, may be used whenthe steam in any nozzle does not expand. to f such' extent that' the pressure is less than"58% of the pressure `at the inlet of the nozzle. 1 Ina six-stage turbine, the pressure drop in any stage will not ordinarily be vgreatenoughjto require expanding nozzles.

Thus, in the illustrated embodiment of the invention,-jif the steam expands to 58% pressure in each stage, the exhaust steam-pressure is lessthan 4%-,ofthe initial pressure.V Ordinarily, this represents af greaterv expansion than can be .takenfcare of ingasingle turbine, but if further .expansion is necessary, lit may be effected by 'theuse of additional'stages,

or VbyV cutting the v anes 44 in expanding form.

It will be seen that the invention provides f for radialA flow inV each stage of a multi-stage turbine. It will be understood that thete'rm radial flow as employed lherein`,is' as usually employed in this art, to signify a radial component.- ofA flow and to `distinguish from axialI flow` by the total absence of any'axial f or longitudinal component.- lThe radial Aflow e. principle'permits theextraction of a greater proportion'of useful energy from the'steam in anysingle lstage because of the fact that the fluid, in entering and leaving the buckets,

directing vanes in the inter-stage passages.

2. A multi-stage, elastic'fluid turbine comprising a shaft, a plurality of rotors each provided with a series of peripherally dis-V posedy buckets, andmeans forming radial Howinter-stage passages between vadjacent rotors, said-means comprising a diaphragm separating the rotorsy and a ring surrounding the diaphragm and having an annular internal groove spaced from the outer surface of the diaphragm, and iiuid directing vanes formed on the diaphragm and projecting into the inter-stage passages. c.

3. A multi-stage, elastic fluid turbine comprising a shaft, a plurality of rotors each Yprovided with a series of peripherally disposed buckets, andv means forming yradial flow inter-stagepassages between adjacent rotors, said means comprising a diaphragm separating the rotors and a ring surrounding the diaphragm and having an annular interf i nal groove spaced from the outersurface of the diaphragm, each diaphragm and ring being split, and bearing means between. the diaphragm and the shaft.

`4. A multi-stage, elastic fluid turbine comprisingfa shaft, a plurality of rotors along the shaft, each rotor having lsymmetrical peripherally disposed 'action buckets U- shaped in axial section, astator having any nular interstage chambers between adj acent rotors, each chamber being U-shaped in axial ing U-shaped portions extending beyond the rotors and within the chambers to form continuous U-shapedvinterstage passages.

, VIn testimony whereof I have signed myy name to this specification.V

'OLIVER D. H. BENTLEY.-

" turns completely through an angle of Having vthus ,described the invention, what is claimed'is: l Y 1.l .A multi-stage, 'elastic fluid turbine comprising a shaft, a plurality of rotors each provided: witha series-of peripherally disposed"` buckets,v .and means` forming radial 105 section, and means separating the rotors havi

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