US1889554A

US1889554A - Steam chest construction for steam turbines

Info

Publication number: US1889554A
Application number: US464140A
Authority: US
Inventors: Frank W Kennedy
Original assignee: Laval Steam Turbine Co
Current assignee: De Laval Steam Turbine Co
Priority date: 1930-06-27
Filing date: 1930-06-27
Publication date: 1932-11-29
Anticipated expiration: 1949-11-29

Description

Nov. 29, 1932. F. w. KENNEDY STEAM CHEST CONSTRUCTION FOR STEAM TURBINES 7 5412/? mzzlzca y FI G.

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Nov. 29, 1932. w KENNEDY 1,889,554

STEAM CHEST CONSTRUCTION FOR STEAM TURBINES Filed June 27, 1930 2 Sheets-Sheet 2 Patented Nov.j29, 1932 FRANK w, KENNEDYQOn'r ENTON W JERSEY; ssIeNonfTo DE :IQAVAI. scrum ;'rurua'n-in COMPANY, on 'rnnnron, E JEB SESLA CORI'ORATfIONOFfNEWJERSEY Y s'rnmonnsrconsrnucrrron non STEAM roam mas Application filed June 27,

V This invention 'relates't0 a steam i'chest construction particularly adapted for steam turbines, the construction being such "that the steamchest may expand independently of the the turbine casing can be caused by sudden turbine casing to prevent distortion. thereof.

It is desirable, in the constructionfot a steam. turbine, to 7 provide means whereby only a minimum amount of distortion of or unequal heating thereof. If steam: is ad 7 mittedsuddenly to asteam chest which is:

' a part of the main turbine, casing,;there results, due to. suddenheating of, thG POI'bIOIIS of the turbine casing coming. into intimate contact with the steam,- une qual expansion and consequent distortion due to the fact that other portions of the casing are at much lower I temperatures than ncoming steam.

the 7, temperature of. the

' Ina marine turbine, where-areversing element is necessary, the reversing; element is usually mounted in the-exhaust end of the turbine. If the steam chest of the reversing element be made. a portion; or, the vmain turithe case of a marine turbine .IIOQPIGVlOIlS} warming up of the reversing element is .possible and the steam is turnedintothereversing element s steam chest: quitesu'ddenly.

.In view of the'fact that the reversing element of a marine turbine is :mounted' in the exhaust end thereon-during forwardoperation it is subject to the fullrvacu-um and the corresponding, low temperature. For instance, in a marine turbine operating at a vacuum of 28.5 inches, the exhaust end, which is subject to the full vacuum, ,is at a temperature of approximately 92 The en tire exhaust vend including the reversing elementand its steam-chest will accordingly'be at this low temperature; If the steam is now suddenly admitted to' the reversing element in order to back the ship, the reversing. elements' stealnchest will then be subject to a temperature equal to-thatoflthezfull steam tempe'rature,whieh under modern conditions may befrom 600 .to 750 F. @The sudden change intemperature, coupled withthe, fact steam chest to the casing.

1930. Serial No.464,140.

that certain portions of the casing in the im-, mediate vicinity of the steam chest will heat more rapidlythan others, results in unequal expansion and distortionof the; wheel case. The object of this inventionds the. provision of a steam chest which can be subject to; sudden great changes in, temperature w thout resulting in the distortion or warp mg ofthe wheel case.. In viewof this feature, the steam chest is particularly adapted for use in connection with the revers'ing'element ofa turbine. 7 1 This result is accomplishedlby. mounting this steam chest in the turbine in, such a manner that the steam chest itself is separate from the main turbine casing and be ng inlthe exhaust end of the turbine when used in connection with the reversing element .is surrounded with vacuum, thereby preventing, as far as possible, thetransmissionuof Z heat from the steam chest toj the turbine casmg. 'llhe steam chest-is. mountedin the eas- -ing by'comparativelysmall bolts which,'.d,ue

totheir small area and long length, can trans;- m1t only anominaljamount of heat from the The accomplishment of object of th invention: and also-of more specificobjects relating to details of cone, struct on Wlll be apparent: from .the following description, ,readinconjunction withthe accompanying drawings, in; which ,Eig. .1-; is;.a vertical section through the I Fig. 4 is ave'rtical axial section ona reduced scale showing the relationship; or. the for ward and reversing elements. i

The turbine illustrated in the drawings is of theiusu'al marine type, the, reversing end .onlybeing illustrated in-detail, The casing i of the turbine consists offalower member 2 i r and an upper member 4, the upper member beingsurmounted by a casing, 5.. :The shait 100 is mounted in suitable bearings in the casing in the usual fashion and carries the reversing rotor 8 carrying the spaced series of buckets indicated at 10, between which are located the stationary buckets indicated at 12. The shaft also carries the forward rotors 13, the buckets of the last stage of which discharge into the discharge chamber 15 common to both the forward and reverse elements, and being subject to the condenser vacuum.

In the improved construction, the steam chest comprises a hollow ring shaped memher 1 1 which is preferably continuous in small turbines. This steam chest is provided with discharge nozzles 16 of usual form arranged to direct steam into the buckets 10 carried by the reversing rotor. The annular steam chest is held in position by a series of radial bolts 18 and a series of axial bolts 20. The bolts 18 are connected between the steam chest and a central ring shaped portion of the casin which has a small diameter so that all of the stresses on the casing due to radial expansion will act at its small diameter and upon a rigid ring which is not in itself liable to distort. The bolts 18 are of long length, bent as illustrated in Fig. 2 so that expansion of the steam chest-tending to increase its diameter can be taken care of by the bend in the bolts without unduly stressing the turbine casing. V

I The axial bolts 20 are threaded into bushings 22 carried by the steam chest and are provided with heads 24 having spherical seating surfaces engaging within spherical recesses formed in the casing. The bolts are provided with squared heads 26 engaged in cooperating openings in caps 28 which are threaded into the casing. By rotation of caps '28 the'bolts =20 may be readily adjusted, the

caps 28 forming an airtight closure of the casing so as not to affect the vacuum. It will be understood, of course, that the bolts are seated at 24 so as to be free to move angularly to take care of outward expansion of the steam chest when heated.

Steam is led into the steam chest through a neck 30 which passes outwardly through an opening 32 in the cover plate 5 without contacting therewith. An expansion joint is formed by the use of an annular member of corrugated metal which is clamped at its lower end to the cover 5 by a ring 36 held down by bolts and at its upper end to a flange plate l0 by an annular ring 38, the flange plate 40 being bolted toboth the neck 30 and the steam admission pipe -12. By reason of the provision of this expansion oint, it will be obvious that expansion of the steam chest may take place without distortion of the easing. On the other hand, the casing is completely closed so that proper vacuum maybe maintained therein during operation.

The expansion joint, besides serving the purposes just noted, also permits the ready disassembly of the cover from the casing, since the various elements forming the expansion joint may be readily disconnected and the cover may be withdrawn from the neck 30, the flanges of which. will pass through the enlarged opening 82.

By the construction just described, it is possible to make the steam chest as a conthe steam chest itself, will be readily apparent. and 20 and the absence of any enlarged conducting path in the expansion joint 34 assures that there is no substantial direct conduction of heat through metallic parts from the steam chest to the case.

During operation the space surrounding the steam chest is under high vacuum, being in communication with the discharge space 15 through the buckets 10 and about rotor 8 and is accordingly at a low temperature of steam corresponding with that vacuum. In other words the portions of the casing adjacent the steam chest are maintained at substantially the temperature of the exhaust steam and conduction or convection is practically elimmated by reason of the existence of a high "vacuum surrounding the chest.

Due to the fact that the expansion joint 84.-

is only subject to the vacuum temperature and pressure, it does not involve any difliculties in construction.

While the invention has been specifically described as applicable to the reversing element of the turbine, in which case it is of very particular utility as pointed out above, it may sometimes be advantageous to have the main steam chest of a similar construction in order to prevent warping or distortion of the turbine casing, particularly where very high temperature steam is used or there are other conditions which might ordinarily cause unequal heating or excessive expansion of the casing.

While the steam chest is preferably a solid ring, it need not necessarily'be so. It may, for convenience and to meet special conditions, be divided into two or more parts bolted together with internal joints in the turbine casing or cast in separate pieces with separate connections on the outside of the turbine casing. In other words the solid ring construction is not essential but it is the most desirable construction for most conditions.

VVhilereference is made above and in the claims to a steam turbine, it is intended that The small cross section of the bolts 18 j the casing provided with means arranged to longitudinally distortable by reason of devia tion of portions thereof from straight lines joining their points of engagement with the shaft and casing. I v

2. A turbine comprising a casing, a rotor within the casing, a chest within the casing provided with means arranged to direct driving vapor to the rotor, and rods securing the chest to a portion of the'casing of small radius, said rods being readily longitudinally distortable by reason of deviation of portions thereof from straight lines joining thelr 7 points of engagement with the shaft and easing. j

3. ,A turbine comprising a casing, a rotor within the casing, a chest within the casing.

provided with means arranged to direct driving vapor to the rotor, and axially extending elements free to move outwardly during expansion of the chest and'securing the chest to the casing.

4. A turbine comprising a casing, a rotor within the casing, a chestwithin the casing I provided with means arranged to direct driving vapor to the rotor, readily longitudinally dist-ortable rods securing the chest to a por-' tion of the'casing of smallradius, and axially extending elements free to move outwardly during expansion of the chest and also securing the chest to the casing. V

5. A turbine comprising a casing, a rotor within the casing, a chest providing in annular driving vapor receiving space within direct driving vapor to the rotor, and rods securing the chest to the casing, said rods being readily longitudinally distortable by reason of deviation of portions thereof from straight lines joining their points of engage ment with the shaft and casing. r v

6. A turbine comprising a casing, a rotor within the casing, a chest providing an annular driving vapor receiving space within the casing provided with means arranged to direct drivingvapor to the rotor, and rods securing the chest vto a portion of the casing of small radius, said rods being readily longitudinally distortable by reason of deviation of portions thereof from straight lines joining their points of engagement with the shaft and casing.

7. A turbine comprising a casing, a rotor I shaftand casing.

within the casing, a chest providing an annular drivingvapor receiving space within the casing provided with means arranged to direct driving vapor to the-rotor, and axially extending elements free to move outwardly during expansion of the chest and securing the chest to the casing. i 1 8-. Aturbine comprising a casmg, a rotor withinthe casing, a chest providing an anj nular driving vapor receiving space within the casing provlded with means arranged to direct driving vapor to the rotor, readily. longitudinally:distortable rods securing the chest to a portion ofthe casing of small radius and axially extending elements'free to move outwardly during expansion of the chest and 1 alsosecuring the chest to the casing.

'9. A turbine comprising a casing, a rotor withinthe casing, an annular chest within the casing providedwith meansarranged to direct drivingvapor to the rotor, radially extending readily longitudinally distortable i-odsfsecuring the chest to the casing, axially extending elements free to move outwardly during expansion of the chest, a neck for conducting vapor to the chest through the casing, andan expansion'jointbetween the neck and casing where the neck passes through the casing. a

10.- A reversing turbine comprising a cas- 1ng," a rotor within the casing includlng a reversing element, a chest within the casing,

provided with means arranged to direct driving vapor to the reversing element, said chest being substantially heat insulated from the casing and adapted to be surrounded byexhaust vapor at low temperature from" the 'a'head stages of the turbine, and rods securing the chest to a portion of the casing of smallradiu's, said'rods being readily longi tudinally distortable' by reason of deviation of portions thereof from'straight lines joining their points of engagement with the shaft and casing. V v a 11. A reversing turbine comprising a casing, a rotor within the casing including a reversing element,a chest within the casing providing an annular driving vapor receiving space and provided with means arranged to direct driving vapor to the reversing element, said chest being substantla'lly heat 1nsulated fromthe casing and adapted to be surroundedfby exhaustvapor at low temperature from the ahead stages of the turbine, and rods securing the chest to a portion of the casing of small radius, said rods being readily longitudinally distortable by reason of deviationof portions thereof from straight lines joining their points of engagement with the 12. A reversing'turbine comprisinga casing, a rotor within the casing including a reversingelement, a chest within the casing provided with means arranged to direct driving vapor to the reversing element, said chest being substantially heat insulated from the casing and adapted to be surrounded by exhaust vapor at low temperature from the ahead stages of the turbine, readily longi- 5 tudinally distortable rods securing the chest to a portion of the casing of small radius, and axially extending elements free to move outwardly during expansion of the chest and also securin the chest to the casing.

13. A reversing turbine comprising a casing, a rotor Within the casing including a reversing element, a chest within the casing providing an annular driving vapor receiving space and provided with means arranged to direct driving vapor to the reversing element, said chest being substantially heat insulated from the casing and adapted to be surrounded by exhaust vapor at low temperature from the ahead stages of the turbine, readily longitudinally distortable rods securing the chest to a portion of the casing of small radius, and axially extending elements free to move outwardly during expansion of the chest and also securing the chest to the casing.

14. A reversing turbine comprising a casing, a rotor within the casing including a reversing element, a chest Within the casing provided with means arranged to direct drivin g vapor to the reversing element, said chest being mounted so that it may expand relatively to the casing Without imparting substan tial strain thereto and being adapted to be surrounded by exhaust vapor at low temperature from the ahead stages of the turbine, a neck for conducting vapor to the chest, said casing having an opening through which the neck passes outwardly, and an expansion joint between the neck and easing Where the neck passes through the casing, said oint closing the opening to prevent the escape of vapor.

15. A reversing turbine comprising a casing, a rotor within the casing including a reversing element, a chest within the casing providing an annular driving vapor receiving space and provided with means arranged to direct driving vapor to the reversing element, said chest being mounted so that it may expand relatively to the casing without impartin substantial strain thereto and being adapted to be surrounded by exhaust vapor at low temperature from the ahead stages of the turbine, a neck for conducting vapor to the chest, said casinf having an opening through which the neck passes outwardly, and an expansion joint between the neck and casing where the neck passes through the casing, said joint closing the opening to prevent the escape of vapor.

In testimony of which invention, I have hereunto set my hand, at Trenton, county of Mercer, N. J., on this 23rd day of June, 1930.

FRANK W. KENNEDY.