US2300766A

US2300766A - Multistage centrifugal compressor

Info

Publication number: US2300766A
Application number: US391581A
Authority: US
Inventors: Baumann Adolf
Original assignee: BBC Brown Boveri France SA
Current assignee: BBC Brown Boveri AG Germany; BBC Brown Boveri France SA
Priority date: 1940-05-10
Filing date: 1941-05-02
Publication date: 1942-11-03
Anticipated expiration: 1959-11-03

Description

Nov. 3, 1942. I A. `BAUMANN 2,300,766

MULM'TI STAGE CENTRIFUGAL COMPRESSOR NOV 3, 1942- A. BAUMANN MULTISTAGE CENTRIFUGAL COMPRESSOR 3 Sheets-Sheet 2 Filed May 2, 1941 Nov. 3, 1,942. A. BAUMANN MULTISTAGE CENTRIFUGAL COMPRESSOR Filed May 2, 1941 '5 Sheets-Sheet 3 -intentes Nov. s, v1942 2,300,766 v MULTISTAGE CENTBIFUGAL COMPRESSOR Adolf Baumann, Wettingen,

to Aktiengesellschaft Brown,

Switzerland, assignor l Boveri & Cie,

Baden, Switzerland, a joint stock company oi' Switzerland Application May 2, 1941, serial No. 391,581

1n switzerland May 1o, 1940 9 claims. (ci. 23o-114) The present invention relates to multistage centrifugal compressors and in particularto regulating means therefor.

It has previously been proposed to provide adjustable guide vanes in the gas passages between successive impellers of multistage centrifugal compressors in order to divert the duid stream more or less from a helical path into a radial path as it enters the intake of each succeeding impeller.- guide vanes in one direction or another determines the pressure output of the compressor, depending upon whether the adjustment of the guide vanes results in fore-rotation or counterrotation of the air stream.

In the prior proposals the means for adjusting the movable guide vanes, usually arranged behind the impellers, are not' adaptable to the adjustment of guide vanes immediately in advance of the axial intake of the impellers but are confined to use with guide vanes adjacent the circumference of the passages between the diffuser of one impeller and the entrance of the intake passage of the next. Heretofore it has not been considered practical to build a multistage centrifugal compressor with adjustable guidevanes immediately adjacent the axially located intake ports of the impellers because of the resultant undue lengthening of the compressor to provide sufficient space between adjacent impellers to accommodate the vane mounting and adjusting mechanism.

It is an object of the present invention to pro- The amount of adjustment of thesev vide a multistage centrifugal compressor with i adjustable guide vanes immediately in advance of the axially disposed intakes of the'respective impellers and to just-ing mechanism for the guide vanes which does not result in increase in the over-al1 length of the compressor.

More specifically, it is an object of the invention to provide a compressor of any desired number of stages with adjustable guide vanes in advance of the intake of the impellers in which the adjustable guide vanes are built or mounted in a cage or unit separate from the housing of the compressor, suchcages being mounted on the rotor shaft between the impellers and assembled therewith in the housing and forming with portions of the housing the continuation of the uid reversing passages between the rotors, whereby the vanes mounted in said cages form, in effect, continuations of the guide vanes mounted vin the housing itself.

provide novel mounting and ad novel transmission connectionsv the adjustable guide vanes.

Other objects and advantages of the invention will become apparent during the course of the following detailed description of the same and reference to the accompanying drawings referred to therein. y

In the drawings Fig. 1 is an axial section through a multistage compressor embodying the invention; Fig. 2 is a section on the line 2-2 of Fig-1;'

Fig. 3 is an enlarged fragmentary detail view on the same section as Fig. 1;

Figs. 4 and 5 are axial and transverse sections, respectively, illustrating a modied drive arrangement for the adjustable guide vanes;

Figs. 6 and 'l are axial and transverse sections, respectively, illustrating another modified drive arrangement for the adjustable guide vanes; and Figs. 8 and 9 are axial and transverse sections respectively, illustrating still another modified drive, arrangement for the adjustable guide vanes. Y

Referring more particularly to the drawings, in which a four-stage compressor isshown by way of illustration, I, 2, 3 and 4 indicate the successive impellers which are retained in spaced rela-- tion` on thecompressor shaft Ii by means of spacing bushings 5. It will, of course, be understood that the impellers are keyed or otherwise rigidly fastened on the shaft 6 which is driven by a suitable prime mover, not shown. The first impeller I discharges circumferentlally into a diffuser 1 in which the velocity of the gas is converted into a pressure head. The diffuser leads into a reversing passage 8 into which the iiuid is turned to flow radially inwardly to the intake ofthe next impeller wheel 2 where the cycle is repeated. Adjustable guide vanes 9 are mounted adjacent the inner portion of the reversing passage 8 on pivots I0 journalled respectively in spaced disk members II and I2. The disk Il is provided with a central aperture, receiving the shaft 6 and with suitable packing I3 which seals the same against the bushing 5. The disk I2 is provided with a ange overlapping the adjacent rotor Wheel and carries a suitable packing I4 for sealing the joint. The disk II adjacent its periphery carries fixed guide vanes I5 through which it is connected to a counter-ring I6 which is secured peripherally on the disk I2 by screws or bolts I1. It will thus be It is also an object of the invention to-` provide seen that the disk I I and the disk I2 and the peripheral ring I6 form an annular cage or housing with denitely spacedrside walls between' which theV adjustable guide vanes are mounted, y

for regulating A on the shaft 6 by` means of screws i8, 4as seen v clearly in Fig. 3. `The two-part construction of the cages made up of the split disks il and l2 permits the assembling thereof between the rotor. wheels after the latter have been fixed in position on the shaft and also facilitates the insertion of the packings I3 and I4 into position. The cage formed by the disks H and |21 is centered in position with respect to the main casing and is held in proper registry with the same by means of mating shoulder portions between which the packing 2| is inserted. The passage provided by thecompressor casing, which is aligned with the' passage provided by the disks Il and i2 when the casing is assembled in position, is provided with fixed reversing vanes 22 which, as seen more clearly in Fig. 2, align with the fixed guide vanes I5 so that each of the latter constitutes thetail end or tip of one of the vanes 22.

The fixed guide vanes 22 and the adjustable guide vanes4 9 are so shaped and mounted relative to each other that in all positions of adjustment ofV the vanes 9 the fluid pumped is guided in the Adesired path to the impellers with the least possible loss. The fixed vanes 22 and I5 are curved in the direction of fluid flow from the diii'users 1 and are set to provide guideways in which the uid is turned toward the axis and its circumferential component of movement reduced.

The adjustable vanes S are streamlined and curved in cross-section from leading to trailing edge and the pivotal axis I0 thereof is positioned at the leading edge in spaced relation to the tip of the rigid vane sections Il so that the vanes 9 define guideways leading from the guideways between the vanes 22--I6 and adjustable as to direction of discharge with respect to the axis of rotation of the impellers.

ing shaft 2l mounted in suitable bearings in the casing between the wall defining oneeside of the passage 8 beyond the disk I2 and the adjacent wall of the next diffuser 1. The shaft 26 carries a bevel gear 21 at its outer end which is driven from control shaft 26 by a gear '21 mounted thereonzie The control shaft .26 is disposed in a recess formed by a bulge in the mating halves il and 34 of the casing and in its pasage from one stage to the next is` provided with packing 29. Pins 22 are for the purpose of closing drilled In the position of adjustment of the vanes 2 shown in Fig. 2, the uid is fed substantially radially into the eye of the succeeding impeller without any appreciable tangential component, whereas, with the vanes 9 in the position shown in Fig. 2a. the fluid isgiven a fore-rotation or tangential component in the direction of rotation of the impellers. In these, as well as in all other positions of adjustment, it will be observed that the relation and shape of the adjustable vanes 9 with respect to the fixed vanes 22-Ii5 is such that the guideways formed by the vanes effect the desired directional feed to the impellers without production of eddy currents and with a minimum of loss of ediciency.

The vanes 2 are interconnected for simultaneous adjustment through the medium of 'suitable drive connections which, as shown, may consist of cable connections. The pivot shaft I0 of each vane extends at one end through the disk i2 and has a pulley i! mounted on the projecting end thereof.V 'I'he pulleys I3 are driven by a cable or rope 2li which makes a turn around each pulley in succession and has its ends joined by connectors which can be tightened to keep the cable tensioned. A'gear segment 22, which may constitute part of one of the pulleys i9, is mounted on one of the pivot shafts il) and meshes with a bevel gear 2l carried by a radially extendopenings in the casing opposite the ends of the shafts 25.

It will be noted that the shaft 2B and other driving parts of the vane adjusting mechanism lie in the plane of separation 33--32 of the casing halves SI-M and that the shaft mountings are carried half by each of the casing sectionsso that the same are exposed for removal upon lifting of the top casing half 3l.

It will be noted that with this construction the normal distance between impellers is Vnot increased as compared with pumps without adJustable guide vanes, since there is necessarily a space between the wallof the reversing passage leading to an impeller and the wall of the diffuser leading therefrom due to the'hub shape of the impellers and the sealing at Il.

The operation will be obvious from the above. The adjusting shaft 26, rotated by suitable means externally of the casing, drives the shaft 26 when adjustment of the guide vanes to a diiferent' setting is desired and the cable and pulley connections eifect the same adjustment of all of the vanes to effect the desired directional iiow through the reversing guideways to the eye of the respective succeeding impellers.

In the embodiment shown in Figs. 4 .and 5, the shaft 26 is replaced by a belt, chain or cable 2l which drives one of the pulleys Il from la pulley on the shaft 26.

In the embodiment shown in Figs. 6 and 7, a link and lever connection is employed for transmitting motion from the shaft 26 to the pivot shafts lo of the vanes 2, theconnectinglink 26 being connected at its ends to crank levers 26a and 2Gb on the shaft 26 and one of the pivot shafts Il, respectively.

In the embodiment shown in Figs. B and 9.a

segmental spur gear 31 carried by the shaft 26 drives a larger intermediate spur gear 21a journalied in the casing and the latter drives a spur gear segment 2lb mounted on one of the pivot shafts I0. While preferred embodiments of the invention have been shown and described by. way of illustration, it will be understood that other modificai tions in the details of construction may be made without departing from the spirit of the invention within the scope of the appended claims.

I claim:

1. A multistage centrifugal' compressor oomprising a casing, a rotor shaft extending longitudinally within said casing, impellers mounted in spaced relation on said rotor shaft, means carried by said casing providing a diifusenfor eachl of said impellers and said casing including spaced wall portions defining the outervportion of a reand defining the inner portion of the reversing fluid passage leading to a next succeeding impeller, means rigidly connecting said disk members in spaced relation including rigid guide vanes extending between the same adjacent Vthe circumferential portions thereof, adjustable guidel vanes pivotally mounted on pivot shafts between said disk members inwardly of said rigid guide vanes and drive connections between the pivot shafts of said adjustable guide vanes; a control shaft extending longitudinally'within said casing and driving means effective to establish a drive between said control shaft and the drive connections of said pivoted vanes when said cage unit Ywall portions defining the outer portion of a reversing fiuid passage to convey fluid from a diffuser chamber to a next succeeding impeller, rigid guide vanes mounted between said spaced wall portions, a cage unit mounted between adjacent impellers and assembled with said rotor shaft and impellers in said casing, said cage unit comprising spaced disk members each having an axial opening for passage of said rotor shaft therethrough and defining the inner portion of the reversing nuid passage leading to a next succeeding impeller, means rigidly connecting said disk members in spaced relation including rigid guide vanes extending between the same adjacent the circumferential portions thereof, ad- ,instable guide vanes pivotally mounted on pivot adjacent the circumferential portion thereof, adjustable guide vanes pivotally mounted` between said disk members radially inwardly of said rigid guide vanes and means interconnecting said. adjustable guide vanes for effecting simultaneous adjustmentthereof; a longitudinally split casing comprising two halves formed with seating portions for each cage unit and with wall portions defining a diffuser chamber for the impeller in advance of each cage unit and a fluid passage leading from said diffuserchamber to the circumfere'nce of each cage unit when said casing halves are joined, with said rotor shaft, impellers and cage vunits enclosed therein, a control shaft mounted in said casing adjacent the circumferential wall thereof, and drive connections between said control shaft and the interconnections between said adjustable vanes.

4. A centrifugal compressor according to claim 3 in which the casing members are formed to provide a longitudinally extending recess within lthe Acasing for mounting said control shaft and said control shaft extends parallel to the axis of said rotor shaft.`

5. In a compressor as defined in claim 3, said drive connections being'disposed in the plane of Y control shaft and to the pivot shaft of one of said shafts between said disk members inwardly of` said rigid guide vanes, drive connections between the pivot shafts of said adjustable guide vanes; a control shaft extending longitudinally within said casing, driving means effective to establish a drive between said control shaft and the drive connections of said pivoted vanes when said cage unit is assembled in said casing and means for positioning said cage unit in said casing so that the rigid guide vanes of said cage unit form continuations of the rigid guide vanes mounted between said w'all portions of the casing.

3. In a multistage centrifugal compressor, a rotor shaft; a plurality of impellers 'mounted in spaced relation on said rotor shaft; av cage unit disposed between adjacent impellers, said cage units comprising spaced disk members each having an axial opening for passage of said rotor shaft therethrough, means rigidly connecting said disk members in spaced relation including rigid guide vanes extending between the same adjustable vanes.

7. A compressor according to claim 3 in which said interconnecting means comprise a cable and pulley connection between the pivot shafts of said adjustable vanes and said drive connections comprise a link and the crank connection between said control shaft and pivot shaft; of one of said adjustable vanes.

8. A compressor according to claim 3 in which said interconnecting means comprise a cable and pulley connection between the pivot shafts of said adiustable vanes and said drive connections comprise a pulley and cable drive between said control shaft and one of said pivot shafts.

9. A compressor according to claim 3 in which said interconnecting means comprise a cable and pulley connection between the pivot shafts of said adjustable vanes and said drive connections coml prise a gear drive between said control shaft and one of said pivot shafts. l

ADOLF BAUMANN.