NEMA SM23-1991.pdf

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NEMA SM23-1991...

Description

Steam Turbines for Mechanical Drive Service

Published by:

National Electrical Manufacturers Association 1300 North 17th Street, Suite 1847 Rosslyn, VA 22209

O Copyright 2002 by the National Electrical Manufacturers Association. All rights including translation into other languages, reserved under the Universal Copyright Convention, the Berne Convention for the Protection of Literary and Artistic Works, and the international and Pan American Copyright Conventions.

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NEMA Standards Publication No. SM 23-1991(R1997,R2002)

NOTICE AND DISCLAIMER The information in this publication was considered technically sound by the consensus of persons engaged in the development and approval of the document at the time it was developed, Consensus does not necessarily mean that there is unanimous agreement among every person participating in the development of this document. The National Electrical Manufacturers Association (NEMA) standards and guideline publications, of which the document contained herein is one, are developed through a voluntary consensus standards development process. This process brings together volunteers and/or seeks out the views of persons who have an interest in the topic covered by this publication. While NEMA administers the process and establishes rules to promote fairness in the development of consensus, it does not write the document and it does not independently test, evaluate, or verify the accuracy or completeness of any information or the soundness of any judgments contained in its standards and guideline publications. NEMA disclaims liability for any personal injury, property, or other damages of any nature whatsoever, whether special, indirect, consequential, or compensatory, directly or indirectly resulting from the publication, use of, application, or reliance on this document. NEMA disclaims and makes no guaranty or warranty, express or implied, as to the accuracy or completeness of any information published herein, and disclaims and makes no warranty that the information in this document will fulfill any of your particular purposes or needs. NEMA does not undertake to guarantee the performance of any individual manufacturer or seller’s products or services by virtue of this standard or guide. In publishing and making this document available, NEMA is not undertaking to render professional or other services for or on behalf of any person or entity, nor is NEMA undertaking to perform any duty owed by any person or entity to someone else. Anyone using this document should rely on his or her own independent judgment or, as appropriate, seek the advice of a competent professional in determining the exercise of reasonable care in any given circumstances. Information and other standards on the topic covered by this publication may be available from other sources, which the user may wish to consult for additional views or information not covered by this publication.

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NEMA has no power, nor does it undertake to police or enforce compliance with the contents of this document. NEMA does not certify, test, or inspect products, designs, or installations for safety or health purposes. Any certification or other statement of compliance with any health or safety-related information in this document shall not be attributable to NEMA and is solely the responsibility of the certifier or maker of the statement.

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NEMA SM 23

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NEMA Standards Publication No. SM 23-1991 (R1997)

Steam Tuhines for Mechanical Dive Service

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Published by: National Electrical Manufacturers Association 1300 North 17th Street, Suite i847 Rosslyn, VA 22209

Q Copyright 1997 by the National Electrical Manufacturers Association. All rights including translation into other bnguages, reserved under the Universal Copyright Convention, the Berne Convention for the Protection of Literary and Artistic Works, and the International and Pan American Copyright Conventions.

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STQ-NEMA

SM 23-ENGL 1991

6470247 0524297 714

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TABLE OF CONTENTS

Sectkn 1

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............................................. .................... ..................................... ........................................... ....................................... .................................... CiassiñedbyExhaustcaiditiasis.............................. . -N Tiabmc .................................. CoadensingTUrbinc ................................... classified by Number of Stages and Coam1Valves .................... SingleValveSingieSEagC'Iirrbint ............................ Single Vaive MuuistegeMine ............................. Multi* [email protected] stage m i n e ............................ Muitivaive Muitisiage'ïixòine ............................. C i a s s i ñ d b y ~ N e e d s................................ controlled (Alumtic) Exeraction Turbine ....................... NoncwtrolletiExtractiosi nlrbhw ............................ Noacontrolled Induction 'linbine ............................ CmmUed InQiCtim(Mixdnesslire) M e ..................... InductimExtractionTirrbine .............................. SteamIIiabinecctUl~ts.................................. Turbinecasmg ....................................... SteamInletEndseCtion ................................. ExhaustEI?dstction ................................... Irlemedia&sactiw ................................... Steam Chest (GOV~IIKN vahe Body) ............................ SteamRing ......................................... Nozzles ........................................... StatiomyReveEngBladcs ................................ StationaryRevczsingCham~ .............................. Diciphragm ......................................... sw.nlrbirbe ........................................ ImpuIseStage ...................................... ReactianStage ...................................... shaftseals ......................................... casingshaftseals ..................................... Intemagestlaftseals .................................. BearingHousing ...................................... Bearings ........................................... RacüaiBcarings ..................................... ThnistBearings ..................................... AntitÌiCtianBearings ................................... RotorAssembly ....................................... [email protected]) ......................................... Biades(Buckets) ........................................ Shroud ............................................. [email protected]) ......................................... RotectiveDevice ....................................... COnmhgDevi~. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ExtemalcontrolDevice .................................... WamingDeVice ........................................ SCOPE REFERENCEDSTANDARDS AND DEPlNlïïONS RefaencedSEancbrrds Definithm CONSTRUCTION 'I)pesofSteamT

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PiSc i

ii 1 1 1

3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 4 4 4 4 4 4

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FOREwom . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

plr

...................................

Sentinel W h g Valve soleplate(s) .......................................... Basephte ......................................... FeatmsandAccessan?es

...................................

BasicFeaMesaQd............................... OptiOnalFeaMesandAccessorics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . c o n t r o n e d ~ ~ a n d c o n t r o l l ?Itrrbines e d ~ ................. Ncmwntroiled Exüacîh Turbhes

............................. Nonconp.olled InductiaiIlabines ............................. ?IiirbineRating......................................... power ............................................ speed ............................................ Ratedspeed ....................................... Maximum continwusspeed .............................. N d Power end Speed and Steam Caiditions ..................... Stcamconditiaas: ...................................... MinimwnSteam(hKiibS ............................... MaximumStcamconditions .............................. MinimumEnergystcamccmditions .......................... Inletsteampressure ................................... ExhaiistSteampressUre ................................. Extraction Steam Rressiire

................................

Induction Steam Pressure ................................ Inlet Steam Tempemure ..................................

............................... ..............................

www.bzfxw.com ExhaustSteamT~ perame

Extiaction SteamTemperatrae LndpctimSteam Tempgatme Maximum Mowable Working PressuresandTeanptmtms

DualSteamconditions

.............................. .............. .................................

............................. .......................... Thermodynamic?Iienns .................................... SteamRateS ......................................... TheOretidSteamRate ................................. ActualsteamRates ................................... GuaranteedSteamRate .................................

VauiationsinSteamconditions Flow Limits for an Automatic Exaaction ? M i h e . . . . . . . . . . . . . . . . . . . HowrjmitpforanInductionTurbine Units of Measurement for Absolute and Gauge Pressure . . . . . . . . . . . .

I

?Iiirbineconnectiais......................................

outputshaftExte~..................................

..................................... ................................... ...........................................

Steamcohus AuxiliaryconnectionS LlbiClUb

..................

NonpFessure?lSpeLubncation(Single stage lbbines) oil Lulnicztred sleeve Beanngs (HarizwEalTiirbines) G?ease or oillubricatadAntinictionBearings ..................... pressure?lslpeoilLu~ InProduction Oilnrmpr ........................................ oilReservoir

.................

............................... ....................................... ....................................... oilcooler ........................................ OilFdt~zs.........................................

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sectlocr2

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S T D - N E M A SM 23-ENGL L99L

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b470247 0524299 5 9 7

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............................... ................................ .......................................... ............................... ...................... ..................................... ............................. vi’bration .......................................... Singlestageïùrbim .................................. M d t i s t a g e ï ù r b ~ ................................... clitwspeeds.L................................... NameplateData ....................................... CONTROLS .......................................... GoveaningSystem ....................................... SpeedGOmar ....................................... Multivariable Govexnor ................................... CoatmlMeChanism ..................................... GOvmorconmlled WVe(S) ............................... Servomom System ..................................... E x t e m a l C d D e v i w .................................. Speedcbangetlype ................................... RemoteSetPointQpe .................................. Valve Actuating.................................. speedchanger ....................................... Speed Govaning System classification ............................ SpeedRange ........................................ [email protected] .................................... speedvariation ....................................... DeadBand ........................................ stability ......................................... Speed Regulation. Steady State .............................. steamPressurecaritrd .................................... PressureRegUlatingSysíea~................................ PressureRegUlatw ..................................... Control MechaniSn ..................................... nessUre Controlled Wves ................................. pressurechanger ...................................... SteadyStatePxess~mRe guûuion .............................. PressureReguiatioaiC . ............................ stability ........................................... pressure control perfamilmce ............................... Compensated coatrol System ................................. Electronic Governing System ................................. Basic Features ........................................ Accessones ......................................... Control Primiries ..................................... Control of inâuctimor Extracoon ............................ Missing Signai Detection Featrae ............................ SensorRedundancy ...................................

piping and Instnunentation nwisons for the Esrvin>nment Eaclosufe Exposwe to Nanrral Elements Exposure to Abnonnal Ahnœphedic conditioas GeneraiRequiremeats PltsSureandTempemmRanges

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...................................... ........................................... Automatic S t a t Controls ................................... OverSpeeaTnp

Genexal

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. 11 12 12 12 12 12 12 12 12 12 13 13 17 17 17 17 17 17 17 17 17 17 17 17 17 18 18 18 18 18 18

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20 20 20

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STD.NEMA Sfl 23-ENGL 1991 m b470247 0524300 039

secth4

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Sectbn6

sectm7

sectkn8

......................................... ......................................... ......................................... Overspeed'LtipSystem ................................... OverspeedScnsingD ................................. n i p speed .......................................... nipvalve .......................................... Combined 'Ltip and IhrottltValve ............................. overspeednipsystemsetting ............................... FACIDRYTESTING ..................................... 'Iiirbine ............................................. HydroTd .......................................... NoLoadRUnmngTesc ................................... SOUNDPñESSUREJEVELS ................................ Gtaeral ............................................. swnd€3essweLev& ..................................... soSmd~LevelMtasuremcntprocedme........................ Camction for BacLgrwnd Noise ............................... souadResolution ....................................... Instnuneats........................................... S d A ü e nd o n ....................................... PRapARATI0NFORS"TANDSTORAGE .................... PRûïECTiON BasicFeaûues UanUalTrip

S h i j l p i D g R e ...................................... ~ Shipneat ............................................ W i t and Storage of Equipmeat .............................. INSTALLAIION In-tion ........................................... SupervisionOfIaseallation

....................................... ................................... ........................................... Fouudation ......................................... steam Inlet and Exhaust Piping ............................... C i e a m n g o f ~ S t e a m P i p i n g............................. SteamPipingSystems ..................................... I n e t i o n .........................................

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........................ ............................... .................................. ................................. .................... .......................................... ........................................... .................................... ...................................... Grwting ............................................ FlushingûiiSystem ...................................... OPERATONANDMAINTENANCE ............................ The Piping noblem as Applied to ?brbines FbmsDue to Stearn Pressure FbmsDue to Temperatwe FarcesDue to Dead Weight AuowaMe Fœces and Moments on Sttam Turbines DrainPiping IÆak-ofli Fuil-FiowReii&Device CoUptingAlignmcnt

seCtrOn9

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..........................................

operatioa ............................................ Noncondensin ' g 'hbine opetatianof aMultisragecondensia . g'Ihrbine .......... 'I)pical SEertmg Seqaence fima Steam nirbine ........................

..........................................

Maintlmance Intluduction

.........................................

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S T D m N E U A SU 23-ENGL 1991

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SeCtknS Sacth10

6470247 0524303 T75

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UitemalWaterWashing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . steamhinty . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . INQUIRYGUIDE.. .....................................

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52 52 67

S T D * N E M A SU 23-ENGL L99L

9 6470247 052430il 7 D l W

Foreword Ilhis standard has been developed by the Steam "wbiine Section of NEMA. In its preparation andrevision,considaationbas been given to the work of other organizations. such as the American National Standards institute, the American Peuoleum institute, the AmericanBoiler Manufacturas Association, and the Amencan . SoCiety of Mechanical Engineers, striving toward the deveiopment ofstandards,anddtishaebygiventoaii whosesiandardsmayhavebeenh~~inthepreparatian of this publication. nK purpose of this standard f a singie stage and multistagemechanid drive steam turbines is to faciiitate the appiication of the.se turbines by engineers, users, aad conuactas, to promote ecwomieS m driving rotalhg mechanical equipment, and to assist in the proper seiection and app~ofthedifferingmechantcaldesigns of turbines. NEMA Standards P u b l i a SM 23-1991revises and SupeISedes the NEMA StandardsPubliCation Steam Turbinesfor Me~hanicalz)rive S e M e , SM 23-1985. User needs have been considertd throughout the development of this standard. Proposed M recommmdedrevisions should be submitted to: Vice Resident,Engineering Depamnent NationalEiecaicalManufacturersAssociation 2101 L S l E a Nw,suite 300 Washnigton,DC 20037 (202)457-8400

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1

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S T D - N E M A SU 23-ENGL L99L

b 4 7 0 2 4 7 0524303 848

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ii

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S T D - N E M A SM 23-ENGL 2992

6470247 0524304 784

Section 1 REFERENCEDSTANDARDS AND DEFINITIONS

AmtriamNationolStandandsInstitute 1430Broadway NewYork,NY 10018 Spcjficprionfor Soundikwl Meters [email protected] for Octave-Bad, Fractional Octaw-Band Anolog Md

S1.4-1983 s1.11-1%

DìgM Füms

ANSUASME B 16.1-1989 B16.5-1988 B1.20.1-1983 B31.1-1989

Can Iron Pipe Flanges mid Flanged Fìttings,Class25,125,250anàW piPC F b g e s and Flrurged F&gs General Purpose Pipe ThrecuFr (Inch) PowcrPìpìng

www.bzfxw.com J h t Ililrinnfactprors Association 25 North Broadway -,NY 10591

The S t a d a d sf the IIqmsion Joìnt Matu#actmrs AssocirrtiOn (1980) (198s Addendum). Riuiont-An -t deviarian in SM caiceaoicityiodicattdbytheoatputofaprmimityprobc whichisduetovariatiaas in the electricalcondllctivjtyœ magnetiCpopertiesOfthtobsavedshaftsraface.

EntrrippedEwrgy-'Ibe~whichcemainsintk

volume of steam bappad betweem the turbine and a trip valve ur notmew Valve. FhibleShriPt-Ashaftwhichisintendedfmapera0ioa atspeedsgreaterthanthe firstlateral c r i h i speed. Hmting-Tñe oscillationof speed or other c011PD)led pamnmx above and below the mean vaiue. An MsEable

coaditioll. Hydno --A test fm leairs and mtegrity 0fthepn~smecontainingcompentsofthe turbinebypressip1pag with water. ïntemaiWaterW~g-Aproceduremwhichsteam having a high percentage of moisture is hjecteä into the tuhine forthepinpose of removhg water soiuble &posits from the tirrbine blades and aozzles.

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STDmNEMA SM 23-ENGL 1991 W b 4 7 0 2 4 7 O524305 bLO

Laterpl C r i h l Speeds-The speeds at Which the ~ITIplitude of die iaterai vibration of a machine rotar due to shaft rotation I.each their maximum due. Proximity Probe-A non-contacting device which eiecîronidy measures the position or displacement motion of an obsexveú surface relative to the probe position. Purge A i r 4 method of seaihg in which air (or ineat gas) is bid into the seal ar housing to maintain a slight positivep.essrireandthuspreventtheentranceofcoaruuninants.

ResiSEnace lkmperaîure Detector (RTD)-A device for d g temperature in which the eíwhicai resistance of tbe &vice changes with mperaiure. Respoase The-'ib time required to m v e r to the d y suue operatingvalue afterasudden change in bad. Service Factor-ïhe factor by which the maximum power capability of a device exceeds its rated m.

SpeeiTied Conditions-Specified conditiolls are aU customer d e f d power, speed and steam conditions at which the turbine must operate. Steam liirbine-A prime mover which converts the thermal energy of steam directly into mechanical energy of d o n . StiffShaft-A shaft which will not be operated during n o d circumstancesat speedsgreaterthan the nrst lareral

criticalspeed. Therm0coupl-A &vice for Sensing temperatures in which a pair of dissimilar conductors are pined at two pints so that an electromotive force is developed by thermoeiectric effects when the junctions are at merent temperature. NEMAStandard 130-91.

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SM 23-1991 Page 2

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STD*NEMA SM 23-ENGL 1991

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b470247 0524306 5 5 7

SM 23-1991

Page 3

Section 2 CONSTRUCTION 21 TYPES OF STEAM TURBINES

2.1.1

clsssified by Exhaust conditkns

2.1.1 .I NO"DPISING TURBINE A noncondengng turbine is a steam turbinedesigned to aperate with an exhaust steam pressureequal to ur greatex tbanatmospkricpressure. NEMA11-13-1969. 21.12 CONDENSING TURBINE Amturbine is a sream Wine designed to operatewithanexhauststeampressurebelowamia6p~c

P=-=

2.1 3.2 N O " T R 0 U D EXTRACTlûN TURBYSE A nonconmiied exnaction turbine is a steam trrranC which has an opening(s) in the turbine casing for thc extraction of steam but which does not have means f a cantrollingthe presswe of the extracted steam. NEMA SIPndard 6-21-1979.

2.1.3.3 NO"TR0LLED N ITuRBWE A I1oI1contTdled mduction turbine is a steam Mbine whichhas an opening(s) in the airbinecasingfainductioa of steam but which does not have means for CQltlDUiilie the pressureof the inducted steam. NEMA S W d d 11-14-1W.

NEMAStandard 1-30-91. 2.1 6 4

2 1 2 CWslfîedbyNunberofStegesand Cœlwvahrea STAGE TURBINE 2.1 2.1 SINGLE VALVE -LE A singie valve single stage turbine is a steam airbine which has one govmor conmiled valve and one stage.

m

D INWCTION

(m

PRESSURE) m B W E A controlled induction (mixed pressiire) turbine is a steam turbine which is povided with sepíirate inlccs far steam at two pressures and has an automatic device f a conb.olling the flow of steam to the turbine stages following the induction opening. NEMA stendprd 6-21-1979.

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6-21-1979.

2.1 2.2 SINGLEVALVEMULTISTAGE TURBINE A single valve multistage turbine is a steam trirbine which has one govmorconaoued valve and two or more stagts,

NEMASEendard 6-21-1979.

2.1 9.3 MULTIVALVE SINGLE STAGE TURBINE A mdtidve Agie stage turbine, is a steam turbine wbich has two or m a t governorcontmkdvaives and one stage.

NEMA spnd9id 6-21-1979.

2.1 9.4 YULTIVALVE MuLTWTAOETURBPIE Amuitivaive muitistageturbine is asteamuxbine which has two ar more governar Caimlled valves and two OT -stages-

NEMAStandard6-21-1979.

215 C ~ b y P F o c e s S N e e b s 2.1 3.1

m

D ( A W W A C ) EXTRACTION

TURBINE

A controlled (automatic) extraction turbine is a steam turbme which has an opening(s) in the turbme casing for the extraction of steam and which is provided with means far directly reguiacing the flow of steam to the turbine stages following the extraction opening for the purpose of

mmiiingextraction pressure.

2.1.3.5 INDUCTION EXTRACT" TURBINE An induction exmtion Mbinc is one which combincs the fatum of extraction (controlled ar nanconmikd) with the featuresof induction. NEMA standerd 6-21-19B. 2.2 STEAM TURBINE COMPûNENTS 2 2 1 nirblnecaslng A turóine casing is the e n c l o m which sumomis tbc rotating element of the turbine and supports the s t a t i m steamparts.CasingsshallbeaxiallysplitJadiauysplifa a combination thereof. he turbine casing W be divideaintotwourmon sections as follows: NEMA Standard 6-21-19B. 2.2.1.1 STEAM INLR ENDSECTION The steam inletend section is that portion of the riffpinn which containsthe higher pressure steam. NEMAStandard 6-21-197W. 2.2.1.2 EXHAUST ENDSECTION The exhaust end section is that partion of the cssing which contains the exhaust connection and the steam at exhaust conditions.It shaü also contain the low pressnn stage(s) of a multistage turbine. NEMA Standard 6-12-1979.

NEMAStandaid 6-21-1979.

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S T D - N E M A SM 23-ENGL L99L

H 6470247 0524307 493

SM 23-1991 page4

2.2.8.1.1 Aptsure impulse ur Rateau stage coLIsi8t8 d smionmy expnshx~nozzíe(s) and one row of rotatiag bkides. 2.2.8.1.2 A velocity-compoanded impuise or Curtis stageconsistsofstationaryexpansionnozzle(s)Imdtwoa more rows of rotating blades. 2.2.8.13 A v e l o c i t y ~ p u n i d e d i m p u i s e ~ ~ s i a g e umsists of Srationary expansion nozzie(s), am?IOW at

rotatiogbladesandoneormorereversingchambas. TbepressmdropacrossaRateanstageisreiativelybw inwmpoaisontothepssmdmpacmsaCmtis~. Authorized E n g W n g l t l h n a h6-21-1070.

2.2.8.2 R ~ C T I OSTAGE N A reaction stage consists of stationary expanSion nozzie(s)discharginghighvelocitysteamjetsaitherotat-

ingblades.Apressuredropoccursinboththesiatioaary and rotatingelements. NEMAStandardô-21-107B.

2.28.1 CASING SHAFT SEALS Casingshaftsealsminimizetheleakageofsteamoutof uie casing dong tbe shaft. For condensing turbines, seals are arranged to jxemt rhe entnuiceof airinto the casingdong the ShaR *yare aaraaged fur the admifipimi of steam at a canstant low pressmcand low mperalme.

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NEMAStandard6-21-1979. INTERSTAQE SHAFT SEALS

Interstage shaft seals minimize the leakage of steam h g the shaft between stages m amuitisfage m r b h NEMAStandaid6-21-1979.

2.2.10 Beerlngtlouslng Abearing housing Coataias andsupputs abeariagfs)

andisequippedwithseaistopreventlcíücageofdaodttie entnince of m o h , dust,and foreign matmi&. NEMA-

6-21-1970.

2.2.11 ûmtln(Y 2.2.11.1 RADIAL BURINOS RaclialbearingsarebearingsWhich s u p p a r t t b e ~

elementinhorimtalshaftbirbines.Iheyareofihtsl~~, tilting pord mantifriction type. In verticat tmbrnes,these bearings tnri;sllv positiOn the mtar assembly. NEMAStandrurl6-21-1970.

2.2.11 9 T H R W BEARINGS

Thrust bearings rn m g s which trammitthe axid thrust of the rotatllig dement to the beaping bousmg and maintain the axial position of the mux assenibly m the

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229 shaftseals

STD-NEMA

SM Z3-ENGL

I99L

W b470247 0524308 32T

m SM 23-1991 Page 5

casing. They m of the antifrictm, laad, ar scgmeniai tutuigpadtypt. NEMASWdaid6-21-1939.

2.2.113 ANTFRICTION BURIN08

2.2.18 ConadllngDeVice Acoatrolliagdevice is OM which manidly icaliy initiates action of a system which caaerols a(MnB1 apaationofthetiirame. NEMA-

11-13-1968.

Antiúictim bearings stmuid have a minimum rating life of3 yearsa25 o0Ohoursw h e n a p e r a t e d ~ ~ a t 2219 ExtemalcontrdDwlce maxgnumtblUStdradislloadsaodat~speed. An extanal control deviœ is an element which is EAuthorized Engheeiing Inkrmillion 6-21-1979. sponsive to signais other than turbine spaad, ie., flow, The rating life is tbe number of houisatcunstant speed presswe, -,and soforth,dacis toconirol the tbat9ûperctntofagroupofidcnticalbearhgswiiiopcratc fbw o f steam t o the turbiDe. shalt be pnemwidY* befcxe the fitaeviâe-nce of fatigue devebps. mecbanidy, hydraulically.or electricany actuated fiom kthomed E n g i i n g Inbnnaakn 6-21-1979. the signal sollfcc to position the governor [email protected]). (Ref2.2.12 RotorA88etnbly mmœ Section 3.1.6.) NEMAStandard 6-21-19'19. "be r ~ oassembly t is the rotlltingelemnt of the turbine

u

whichinclubesaiîpartsattachedtotheshaft,excludiugthc caipling(S) unless coupling is integral Witb the shaft. NEMA-

621-1979.

2.2.13 W h 0 d s m ) wheels arediscs which are inmgrai witb,orñxcdto, the ~ieshaftandoawhichbladesaremounted,orinwwhich

bladesorbuclrmsaremachined.

NEMA-

6-21-1979.

2220 WamlngDeVlce A warning de* is one which,by visiõle or auáiblc means, or both, indicates that an abnomai apefatingumditionexiscs, NEMAStandard6-21-1879.

2.2.21 Sentlnel Wamlng Valve A sentiael waming valve is a pressure warning device whichopenswhaithesteampressurerisestoapredetermined1eveLThedeViceshaü dischge tothe atmosphere andshallbesolocatedasto be plainly visible& For condcaskig tl&K%% it shall be set at 5 psig 135 kFa(gauge)]. For noocondensing m n ie s the minimm seüing shall beeither 10 percent or 10psi (ïOLpa) above maximnm exhaust steam pftssuR, Whichever is greater. NEMA standard 6-21-1979.

A sentinci warning vaive is not recoaimended for the

following applications: a i n e s which utmd volatile gase^ locatiais where the discbarge of steam to the am+

-

2.2.16 H a n d W 0 ( S ) A hand [email protected]) is the valve which isalates steam flow to a gmup afnozzle(s) to pennit e&cient apetriton at

redmtdpowerawithdualsteamconditionsHaudvalvalves can be either manuaily condied or arbomated and are used on singie valve turòines oniy. NEMA SiaKliUd6-21-1979.

2217 PmtecthreDeVice Apotective device is one which, alone oras p?* Qf a sy9iem,respondsinsomepredetemiinedmannerto,~sormalconditionsaoendllig theopewtion ofthe unitorsystem towhichit is connected. NEMA Standard6-21-1979.

sphaeisobjcctionable,hamdousorpmhibkdbyhw

- Mbineswhicbareanangedforauiomaticworunatmdedstart-up

hir these applicaliom, an alteniate wanimg device œ optionaitrip device is iecommended. Authorued Enginwing Information 1-91.

2.222 s o w w s ) A soleplate(s) is a machined fiat steel piate(s) or casting(~)for mounting of the equipment supports and far biting and grouting to the foundatiar. NEMAStandard 11-13-1689.

2.223 ûmapiate Abaseplate is a fabricated of cast continuwsstructure havingmachinedpads for mountingof the equipment and for bolting and grouting to the foundation. NEMASQndard 11-13-lQ69.

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S T D -NEMA Sfl 23-ENGL

2.3 FEATURESANDACCESSORIES

m 6470247 05243ûq 266

9. Insulation for the high tempemm section of tht Wine to limit exposed siirfaoe temperatme to 16pF (74OC) or other tempemture specified by the

.-P

ring, nrststage,dexhauststenimpressure. 11. Coupling between the turóine and driven machine (normaiiy fumhhed by the m8nufacturea of the dnven equipment). 12. coiipling guard SuppOIted frwi tbe baseglate oc adjacent bealing housmg(s). Tbe couplmg guard shouldbecasilyremovableandbe~ientlyrigid to withsiand deflection and plevent rubbing as a resuuofnaïmalt!odilycaitsctbypersonnel.Wbco continuauslylubaicatedcouplragsare~the coupiing guard œ housing should be fitted so that oil leaks will bepmted. 13. GlandleakageevacUatingappIiratuswhendiegland casngdesignrequiresitsuse. 14. Tachometer of the vibaatuig mai, machanical, ‘ a r e~type;iodicatiagspeedsfroniabovethcûip speed to M o w the minimum aperatiag speed. Thchometers shall be suitaóle for the specifmed eavi-

Ionment. 15. Supemhry instniments to monitor such as vibration, axial shaft movement,tempemtms, etc. 16. Shaftgroundingdevicetocarrytogromdanysíatic charge which might be developed on the hirane romandwhichmayotherwisebuildtoLevelswhich ddâamageturbhcbearings. 17. Rotor turning gear togeUier with driving maus, engagement and äisengagementfeaiures, and lube oil pressure interlocks to permit slow turning of the

mtorsystemonstatt-upandsbutdown. ..

18. AlbusSm trip valve which provides a means far quick and positive shutoíf of admjssion stcam f a emegencY tnppuig. 19. Nonretuni valve(s) for blocking ihe revme flow of steamfkom~intotheturbmethrough~ orextractioaopenings. 20. Redmiantoverspeedtrip. 21. Exhaustreliefvalveornrptriredisctopre~over piessrning of the exhaust end section (see Sectim 8.7).

22. Vacuumbreakertoadmitairiatotheexhau9tam nections d a condensing turbiue in cmk to reduce coastdowntime. Additbd items may be availsble. Authorized E n g i i t q ~ infamaiion 1-1.

2 s ControlledEXttadknandmled krdudknmrblnes Conwlleü exmaion, ccmtrolled indoction, and ummlled induction exmction turb8nes &ail include basic

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10. Steampresswegaugestoindi~inletsteam,~

SM 23-1991 page 7

features W i n items 1 thrwgh 6ofU.1, together Witti those lisied in 23.3.1 through 23.3.4. 2.33.1 Controlled extraction turbhm shall bave apre+ 8utt regdath8 SySteB for mtroiiing mt p s s m of the extracted ste9m by regulaiing the fbwof steam to the turbine stages fallowing the extracth opening(s). Anonreturn valve br the extraction apallng(s), which is also actpated by the ovaspetd tip system. is nquind far installationintheexoactimsteamline(s).

2.3.3.2 controlled mduction turbines Shan imve apesme regdating sysrem for cantrolling tticpm5urcof the imjucth steam toregulate t h e b w ofsteam tothe turbine --``,`,``,,``,```,``,`,`,,,``,-`-`,,`,,`,`,,`---

stagesfoiìowingthein&ctionopening.Atripvaivewbi& isalsoactuatedby theoverspeedmpsystemisnquired fnrinstallaaon . intheinductionsttamk. NEMA-

190-1991.

233.3 Dependmg on the source of induction steam, the usashould consider the need for a steam ssainer in t i i s h e to protect the loweapressure stages of me turbine.

AumaiEed Engineering Infornietion 11-14-1985.

2.3.3.4

Controlled extraction turbines and controlledinduction turbines shall have a multivariablemiml system which provibes interconnectiOn die pressiut rCguiatingsystemaadthespeedgovemingsystem.

2.335 conarouedinductim ~rtractioatrabinesshall inchdethecombinationofthefcxegoingitems. NEMA-

11-14-1085.

23A ~ ~ E x t r a c t b n T i a M n e r Nonccmmiiedextnictionturbinessballincludetbbasc

242 speed 2.4.2.1 RATED SPW Ratcdspeedisthespeedcanesponduig * toratedpowa. It is measiaed at the output shaft of the turbíw, is expressed in rievdutioas per minute, and is quai to M less than m8ximm~ u o u speed. s NEMA standprd 6-21-1979.

2.4.2.2 W u u Com~uous SPEED Maxm i um conhinuous speed is the highest specifiad speed at whicb a turbine can be operatcd continwusly pwidedproperovaspeed~goverwr- a r e

iastalledand operatianal.

-

NEMA-

621-1979.

2 ~ 3NomralPower,SpeedandSteam

corabns

m

hJpower, and cooditionsaretbost caiditionsfwadmd~aadatwbichrhesteam ratcwillbeguafan~ NEMA-

6-21-1979.

U A Sî~Conditlons 2.4.4.1 WNuW STW C û t d m Mn im i um steam ~ t i ~ a thelowest r e inlet stcam pressure and tempemm and lowestexhaustprcssm to which theturbineissubjectedincontinuwSopaatiOa. NEMA stadard 6-21-1979. 2.4.4.2 M A # ~ ~ ~ ~ T E A ~ ~ ~ N ~ T K I N ~ Maximum steam CDnditiOIls am thehighest inlet steam pitssrrre and imperature and exhausspIesllm to Whicb the tiirbmeis subjectedincaltinuousopaation. NEMA-

621-1979.

feaaacsiistedinitemsl througIi60f2~.1,togctfrtr~ith mwisecmnvatve(s)far theextractionopening(s). 'he quan2.4.4.3 Wuuu E N m v Smw tity and lomion of nomearni valves are tobedetermhl MïniInm~geamconditi.Mlsiuetbe~inltt bythetrirbincman~basedonentrappedaiergy steam presswe and t e m m and the highest CxImust ~redimdaacypolicy. pmsm at which the turbine is requucd to produœ a NEMAStandard 130-1991. specinedpower~speed 2.3.5 N ~ l l e d k i $ u á k n n i i b l I l @ S 2.4.4.4 hLET STEAM PRESSüRE NoaiconmIIedinduction turbines shaü inchidethe basic uiietsteampressiireis the pressureof the steam supplied feahaeslistBdinit«nS1 tl1rough6of23.1,togetheswirb t o t k tUrbii.Jtis m«wredat the $tcf3minlet conncctim a trip [email protected])for the induction opening(s). of the airbine and is e x m a s a gauge piessure. NEMA-

11-14-1985.

2.4 TURBINE RATING 2A.i

Power

Rated power is the maximum specifiedpower output of the~ine.Itismeasuredattheoutpitshaftofthearrbine. NEMA Standard 6-21-1979.

NEMAStandard6-21-1979.

2.4A.5 EXHAUST STEAM PRESSURE Exhaust steam pressure is the pressure of the steam system to which the turbine exhausts. It is measured at the exhaust connection of the turbine and is expressed as a

gauge pressure far- n ' airbineSandasanabsolute pressrrre for condensing tuhines. NEMAStandard6-21-1979.

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STD.NEMA SM 23-ENGL 1971 D b470247 0524311 9L4

2.4.4.6 ExtRAcT#))JSTEAM PRESSURE Extraction steam pmsm is the pressine of the steam extractedfrom the turbine. it is measuredat theextraction wnnecticm of the turbine, and is expressedas a gauge

P===

NEMA-6-21-1979.

2.4.4.7 hwCnON STEAM PRESSURE Inductionsteam~isthepIessureofthesecoadary steam supplied to the Wine.it is measureâatthe inductionconnectian of thetrirbineandis expressedasagauge p#rsiae.

NEMASEandaid6-21-1979.

2.4.4.13 DUAL Srrrun CûNMl"S Dual steam conditiansare two ofmmcombin8tons of iniet steam pressme, inlet steam tempenitine, or exhaust -pressure. NEMAStandard6-21-1979.

2.4.4.14 VARIAl"S IN STEAM CCXJüITlONS The Iatíng, capability, steam flow, speed re-, and pressme control shall be basedon operation at maximum stcam unuütions as defined m 2.4.42. Steam Mbiaes shall be capable of operating under the followingvariatioasininletpressureandm~but p e ? f ~ s h a l l n o t n e c e s s a r* yi lbem accardance with

thestandaadsestab~foroperatmgatmaximumsteam

2.4.4.8 INLET STEAM TEMPERATURE conditions.continuousopetatiaiatotherthanmaximum Inlet steam tempeniture is the total teInof the steam conditioI1s shaü require review by the turbiw mansteam supplied to the turbine. It is nreasiiredat thesteam ufacturer. inletcmnectionoftheturbineandisex~inde~ NEMAStandard6-21-1979. Fatireobeit~indegrces CeW. NEMAStandard6-21-1979. 2.4.4.14.1 VARUTKJNS FROU hhXUuUINLET STEAM

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2.4.4.9 EXHAUST STEAM TEMPERATURE luhapststeam temperameis the totai t e m m of the steam cxhartpted from the tinrbine. It is r n d at the cxhailst CoMectiOn of the tuxbine and is expresd m degrees Fahrenheit or in degrees Celsius. NEMAStanderd6-21-1979.

2.4.4.10 WRACl" STEAM TEMPERATURE Exaaction steam temperatureisthetotalteInperatureof the steam extracteü from the turbine. It is measuredat the exixmirn connection of the tintiineandis eJtpressedin äegreesFahrenheit or m degrees Celsius. NEMASEendaid6-21-1979.

244.11 1NDUCTK))II STEAM TENPERATURE Uiductioosteamtempenimreisthetotalm~of t h e ~ s t e a l n ~ W t o t Itislmasmtd h e ~ at the iiiductionconnectimof die turbine and is expressed in deFahrenheitorin Celsius.

PRESSURE

The turbine shali be capable of operating without damageat less than the guaranteedsteam flow tothe Mbine with average Wet pressure of 105 percent of maximum idet steam pressure. (This pemisible variation recognizesthe~inpressurewith~insteamflOW

encountered in operahion.) The inlet steam pxsure shall average not more than maximum pressiire over any 12 month opedug period, Theinlttsteamprwsureshailnotexceed110perccmd maximumpressurein maintainingtheseaverages,e;xcept during a b d COilClitioI1S. During abmnmal cosiditim,the steam paessare at the tiirbineinletconnection - shallbepermitredtoexdmaxh u m pressure briefly by as much as 2ûpesent, butîhe [email protected] drnation of such swings beyond 1M percent of maximumpssure shallnotexceed 12hwrsper 12mondi operatingpenod. NEMA-

NEMASEandaidô-21-1979.

6-21-19m.

2.4.4.14.2 VARIATIONS FROU WXiNUM INLET STHM mPERAlURE

Theinietsteamtempeniturestϟaveragenotmorethan maximum tempexatme over any 12 month operatmg pe riod. In maintaining this average, the tempemm shall not exceedmaximum tempemureby nme than 1fl(8oc) exceptduringabnnmalcoaditions.Duringabaonnalcooditions, the tempcratiae shall not exceed maximum ternperature by m m dian m ( 1 4 O c ) fwojmathgperiods

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-

S T D - N E M A SI 23-ENGL L77L

~

~

H 6470247 0524312 850

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SM 23-1991 page9

-

h2-theenthalpyofsteamatwrhaustsLeam paeasiiredinitialenaopy. NEMA s&idard ô-21-197Q. 2.5.1.2 AcniAL STEAM RA26.1.2.1 TURBINE

-TE îùrbinesmunrateisthequaatityofrmctsteamnqairad by the tlirbioe per miit of power outpit, lneasmdattbt ouiputshaftofthe tmbme. Itisd y-e inpounds ofsteamperhorstpower-hour(orinkilogremsa€steem pa kilowatt-hour). 2.51 -2.2 TURBINE GEARSTEAM WlE

Whenagearisprovidedòytheturbineman~,tht turbine gear steam rate is the quantity of inlet weam required by the turbine gear set per unit of power outpiit, measured at the output shaft of the! gear. It is &y

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STDeNEMA SM 23-ENGL 3993

M b470247 0524333 797

SM 23-1991 Page 10 eqxessed mpoundsof steam pet harsepower-hour (or in kil~0fsteampexkilowa#-hour.

intenial taper threads conforming to ANSI/ASME B 1.20.1-1983. NEMAStandard [email protected]!5.

NEMAStendardô-21-1979.

2.5.1.3 GUARANTEED STEAM RATE' Theguarauteed steam rate is thesteam rate which will not be exceeded When the turbine isoperaredat w)rmal power, speed. and steam condkions. NEMAStenderd6-21-1979.

2.6 TURM"CO"ECTK)NS

N E M A W 11-14-1985.

2.6.1 2 When a tapered shaft extension with keyway(s) is speciüed,the taper, wupiing hub, andmupiingnut shaü be in accardancewirb Figure 2-1. NEMA taper diameteSS areavailablefarshaflextenshsfrwi2 inches m 5 inches. 11-14-1985.

2.6.1.3 if cyhdrical shaft Cxtension is specfied, it is ncommendedthat the cwpling-to-shaftfit be an inmfer-

ence fit 11-14-1985.

26.1.4 When a hydraulic fit coupling is specified,the mountiug method should be reviewed with the turbine lnallllfimmr.

11-14-1086.

ste(leWW)

2.7.1.1

OIL LUBRlCATEûSLEEVE BWüNûS (tiomzomL~~meB) a LU~~WOII Should be prended by oil l h ~Similar means. b. Beating housings should be large enough to peanit solidsor water m d e to the bottarn and should haw a dtain connection at the lowest point, oil fiil fittings, and an oil level indicam. g ne^C. . F ~ i l i h f o r c d i nshouldbeprovided~hcn essary to assure the proper oil temperahrre. nie cooling water should be supplied at a temperame not exceeding 90%(32Oc).

2.7.1.2

GREASE OR OIL LLJBíUCAEû A N i F H C " BEAWNGS

Gmse-lubricated autifriction bearings should be regreaseable ~die IIkid. Grease fittings should extendtotheoutsideoftheniachiaetopermitregreasingduringopemion. Means should be provided far venting grease lutNicated bearings to pment the buildup of pnssure within the housing. Faciütiesforcoolingshouldbeprovidedwbennecessary to assure the proper lubricant tempemme. The cooling water shouid be suppiied at a temperature not exceeding 909: (32Oc).

2.6.1.5 Recommended use of one and two keys and keyways is as shown in Tbble 2-1. Authœiæd Enginwring Intomiobon * 11-14-1986.

SteamComecUons 'Iiirbmeflangedsteam Connections shallbe facedand drilled for bolting to flanges which arem accordancewith ANSUASME B16.1 or B16.5. CastiNnlflaagecOM~nsshallbeflatfaced The thicknessof cast iron exhaust flanged connections under 1 0 m c h e s ( 2 s o m m ) i n d ~ b e n o t l e s s m Class 25û of ANSUASME B 16.1. Singie vaive single stage hariuwallYsplitcasinganbines shall have steam cannectionsm the bwexhaifdthe trnbiae. connections for making up topipenot0ver2 inches in diametex (So m m nominal diamtter) shall have

NûiìpressueTypekibrîcation(Singie

2.7.1

NEMAStandard 11-14-1985.

2&2

27.2

Pressum tLpe Oil Lubrlcatiûiì

2.7.2.1 ~ O D U C T I û N It is recognized that there is awidevariation in turbine Szesandapplicaths which makes it impracticai to have one recommended lubrication systcm ckign. However,

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fat

casingandsteamchest,casingsealingglandsandbeariqg h~~,cooling~,valve~l~~,and~fforih 2.7 LUBRICATKIN

26.1.1 Omput shaft cxtensionS shall be Spatable for a cyimdrical coupling bore and provided with a keyway(& tapaed ooupling bom with a keyway(s), tapered for a hydraulic fít, or ntted with an [email protected] hub.

NEMA-

AuxiliarycotlIlectiomthataredireadedshallconf~to e

ANSVASME B120.1-1983. W y , these are a d ring prtssure gauge - , drain CoNEMA-

u 1 o u t p u t s h a f f ~

NEMA-

-

ArorlllaryConneUtons

26.3

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STD.NEMA

SM 2 3 - E N G L 1991 H 6470247 0 5 2 4 3 1 4 623

SM 23-1991 Page 11

the foilowingdiouidservewagenaal design guide tothe oeafur~hisraquirements.

total cooling loadandshouidbearrangedandventedf? maintaining eitha cooler with the Wire in ojmation.

27292

2.7.2.5

OILPWPS

OIL FILTER(S)

Single or twin oil tilters may be used. Afiltafs) shoptd 272.2.1 A main oil pump drive^ from the turbine shaft be capable of nmving panicles iarger than 25 micmns. ar a seperately driven pump to provi& oil for lubrication When the film is clean, the pmsurc drop sbould not aadgovemingshouldbepm4de.d. exceed5 Pgi (35 kPa)atdesign t a n m a a d flow. Tiviu fílters should be piped in paraiicl witha confkw 272.2.2 Anauxiliaryoilpumpforuseduringthcstarttransfervalve to permit the transfa of oil fiom 011c filta u p ? s h p t - Q w n p e M d s h w l d b e ~ w h e n r e q ~ t o t h e o c h a w i t b u' tg~the oil flow. Each nUa by bic design ? whan qecihd. niiS pump should be should be sized fm the total oil flow end sbaild bc Upowaedbyadiffemismceofeaagythanthemainoil ranged aad vented for lminmining uthu filtawirh tbe pimp.AprrssurtsensingdeviceshouMbeprovidedfcx tiirbineinoperation.Acommontrsasfavalvemaybt~ aptomatically sfming the ruailiary oil pump when the oil fortheoilfílteIsaQdcoolas.m?íl~cartridgeshouldbe pmsmeintbcmainsystemdmpsbebwapredetermined camsion nesisauu. Filter cases should be suitable for valm opaationatapressurenotlesstbanthcreiidvahn~ For a Mbinedriven auxiliary oil pump, the turbine oftbepmitivedispiacementoilpumpsoratthemaximum 8bOdd d m to all of the @pli* pvisim of diese shut offdischarge pressiire of cenhifugal oil pump. sltmd&L

2.7.2.6 RPNûAND INSTRWEWTAT"

272.3 OILRESERVOIR A samate ail ~ ~ S U V O ~should T have

2.7.2.6.1 Pressure sensitive devices sboahl be prwidad forea&prtssurclevel(forwrampie,oiih&tokarings, discharge 6rom oil pumps, befase and afta fílta(s) and c ~ n h oil). ~ l Means should be pwidad fm BII ai-liee

a

a

main~asappropriaie.

c.

Authorired Engineering Inforniafion ll-lClOBs.

2.7.2.6.2 if bearing mctal thenwconples ot #Il)s arc not pviâcâ, tben thamometers should be povidad for oilwtlet fromcachbesring housing.Tbemiametasmay be provi&dbefore and after oil d e r @ ) . Thermowells should b e p v i d d in the piping f a t h e m ofthCr-

d t.

f.

m e t e r repiacemaitwhile oniine.Tbenmweiasshouki begaSfilledOrcrnrosion-resistantbimetalliCtypc. AuthorioedEngineeringIn-

--``,`,``,,``,```,``,`,`,,,``,-`-`,,`,,`,`,,`---

2.7204 oLcoolar(s) The oii coola should be capable of maimhhg the empuame oftbc oil supplied to the bcaringsatamaximimi d 120°F (49oc), with a maximum woling water tmrpaaaarcmx excealhg 90°F (32OC). It should have a f w l i n g f á C ~ o f O .on ~ lthe wataside fopcoaliag towel water anã afouling faaor asncommendcdby the manu-

2.7.2.6.3 An oil sight flow indicatm wbui spccifiaì shouldbe provided m the oil return from each öcaring housing where thedesign permis

Authofbd Engineering Infotmaütm 11-14-1985.

nicMafarothtrcoolingwate?sources.'Ibemo~sbould be suitable fora working pressmeof notkss than 75 psig [517 kPa (gauge)] m the w w side. Singkartwin~kmmaybeused.Eechcoolershould be capable of operatioa at a pressure quai to or peat ter tima the nlief valve setting of positive displacement oil pumps or ofth maxllnum shutoff dischargepressiae of ca~trifugaloil pumps. M coolets should be piped in paraüciwith acontintmusflow transfervalve topert., ,ithe traas6er of oil from one cooler to the ocher without interrupting the oil flow. Each cooler should be sized for the

Copyright National Electrical Manufacturers Association Provided by IHS under license with NEMA No reproduction or networking permitted without license from IHS

11-14-1985.

2.7.2.6.4 A pressiire regulam or relief vaive should be providedto maintain the oil pressure level(s). A u t h o n z e d E n g t n e a r i n*g I ~ 11-14-10Bti.

2.7.2.6.5 Afterfabricafim,pipingshauldbecleanedd passivated by mechanical an4or chemical means. Authomed EngVieering I n h i i o n 6-21-1879,

2.8 PROVISIONS FOR THE ENVIRONhENT

Encksure Steam turbines shouíd pfembly be installed in enciosedareas.Thee?Fe!&tsofundseMceconditi~may

2.8.1

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S T D - N E M A SM 23-ENGL 3991

b470247 0524335 5bT

m

SM 23-1991 Paga 12

Authobd Engineefing Infonnetkn 11-14-1985.

2m E x p o r i u r e t o N a á i f a l ~ in general, d exposed surfaces should be potected againstrusting by apaotectivecoatiagor paint after instalhion of the unit. Enposed workiqg parts which affect aperation d the unit such as govexnor, govexnor ïinkage, fuiuum pomts, Valve stems.and imilw elements should b e ~ a g a i a s t ~ g i s t u i g the b yuseof comwionresistantmatenalS. Equipment having nonpressure lubricated bearings

sbouldbedcsignedtopvcntîhetnaruiceof dust, and fmign mamiais to the governing s

*

y x bearinghai9ngs. EqpipntnthaMig~l&iCaboihydrauEicgovaning systans,or both, shouldbepruwtedasbilowx

2.82.1 The lULnisystem 09 goveanar system, 09 both, should be protected againstthe entrance of water or foreign materials by proper seaiing devices. The points to beprotectedinchideallcofinectuwis - orapeningstotbeoil Eale€Voir, goveznor. gBromotor, bearing housings, and

sidarelements.Tbereservoirshouiáóeprovi&xiwirha ventwithanairñiîerandcarnectionstofacuitsteremovd of water. 2.8.2.2 In addition to the foregoingprotectivemeasum, tbe following should be included when ambient ttmpezgtrires will be less than 4û?F (4%) 1. Far use durhg down times,drains sbaild vi&d whe€e water can colkctforallsteam,d, and waterlines, the turbme casing and steam chest, and the oil aad water si& of the oil coolex. Pneumatic "blow down- may benectssary m someiostances. 2 Aheater for the ail mservoir.Ifaa electric heater is specineditmustbeofawifncicntlylowwaadeasity topmt coking of lkoilAn auxiliary pump may be reqiiired to eosure oil CircUlatBon for unitonn

heating. 3. An enclosure or bood witb venting to cover the govemùlg system may be provided, and heating shouklbesuppliedtoprevent icing. The amountand type of enclosure and heating wiii be governed by localconditions. 4. Protection against fieeziag for instnuaenBand [email protected]& 5. m i n e manufacturer shouid identay those lines

~resuat-protectionoypa.asa.

Exposu~toAb110mialAtm0spheric oondltkns if possible, the turbine should be located away froin damaging fumaand vapars, or abrasive, magnetic ai metallic dust. If this is not pnictical, the atmospheric candirioas should be called to the aaention of the manufactufft. Suitable materialsor protective coatings may be 2.û.3

requiredtoansetthecomisiveeffectsofthefumes.When necessary, purge air connections on bearing housings, glaad cases,and govemm should be provided. Auth#ired EnQnWringInfonnaoion 11-14-1s.

2.9 GENERAL REQUIREMENTS

PmssureanâTemperaaireRanges Sieam turbines shouidbe designed and proportionedfar operationatmaximumsteamconditions.Genedpressnre and tempexatme ranges ¿utsíÍown in Figure 2-2. The ranges are general, accmding to tempeam&xsure cambinationsat which pomt material or design changes, OrbOth,~~berequired. 2.9.1

Authorlled EngineeringInformation6-21-1978.

Vlbratlon The vibmion of the turbine rotar (double ampïitude) within thespecifíedoperatingspeedrangeas measuredon thesprfacedtheshaftadjacenttotheradialbeaaingsshall be m accadancewith the foilowing: 2.9.2

2.9.2.1 SINGLE STAGETURBINES The maximum permissible w i o n shaü be not peatex than 2.0 mils for speeds 4ooo rpm and lower, or 1.5 mils for speeds 4001 rpm and higher. NEMAStandard 11-10-1985.

2.9.2.2 MULTISTAGE TüRBINES The maximum permissi'ble vibratian shall be inaccardaace with Figure 2-2. The absolute values for vibrath levels above 3ooo rpm can be derived from the following formule 1M Shaft mechanid and electrid runout sbaii be determined by slow rolling the rotor in its bearings while measming the Nwut witb a proximity probe. if it can be

demaisoatedthatmtcbanid&electncalnmoutis~ent, this shaü be added to the abwaòle vibration level op toamaximum 25 peacent of thedioweddoubleampiitude v i ¡ or 25 mils, whichever is greater. NEMAStendard 6-21-1978.

AuthobdEngineeMgInfomiehon 11-14-1985.

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--``,`,``,,``,```,``,`,`,,,``,-`-`,,`,,`,`,,`---

be [email protected] by the use of one or moxe of the measmes bescribed in 2.82 and 2.83.

S T D - N E M A SM 23-ENGL 1771

6470247 05243Lb 4Tb

SM 23-1991 Page 13 not have the specified margins betweem the apaating speadsand~speeds.ïnthiscasetheturbinedesigna should Catculanerotor response to unbalance. The prime caisiderationisseasitivitytom~ Authorired Enghming Inlonnation 6-21-1985.

-

2.9.4 NAMEPUTEDATA nie following minimum data tiabiae nameplale: 1. 2 3. 4. 5. 6. 7.

StlfJu

be given on the

Manufacainr'snameandbcatioa SaialnumW Ratedborsepower

Ratedspeed Maximuminletste9mpressure Maximmillletsteamtunpenitiite

8. Maximumexhauststeampressure 9. M a M m u m e x ~ ~ p r t s s u r e ( i f ~ blc) 10. Tripspeed 11. Maximum continuous speed (ifdifímnt fim rated rg6ed). 12 Fm i lataalcritical speed 13. purchaser's equipmeat item number (when speci-

fied).

--``,`,``,,``,```,``,`,`,,,``,-`-`,,`,,`,`,,`---

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NEMA standard 6-21-1979.

STD-NEMA SM 23-ENGL

m

1993

6470247 0524337 332

m

L

I

I

Copyright National Electrical Manufacturers Association Provided by IHS under license with NEMA No reproduction or networking permitted without license from IHS

CIE

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--``,`,``,,``,```,``,`,`,,,``,-`-`,,`,,`,`,,`---

ft +'

S T D - N E M A S U 23-ENGL

1991

6470247 0524318 2 7 9

SM 23-1991 Page 15

RPM. THOUSANDS

Figure 2-2 MAXIMUM PERMISSIBLE SHAFT VIBRATION

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SM 23-1991 Page 16

(up to & including) 1-50 2 250 3 350 4

450 5 550 6 650 7 7.50 8

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Table 2-1 RECOMMENDED KEY FITS

40 50 65 75 90 100 115 125 140 150 165 180 190

rn

9

230

10

w)

Twokeys may be used in any c89e.

Table 24 GENERAL PRESSURE AND TEMPERATURE RANGES

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S T D I N E M A SU 2 3 - E N G L 199L

b 4 7 0 2 4 7 0524320 927

SM 23-1991 Page 17

steam 00 cnmthe turbine. nie pilotvaivecoatroistbc flow of highpnssme fluid to the power cylink. This flow d highpressmfluidcausesthepistonmthepowcrcyinda to move in rcspaise to the signai h m thegovanœar conQo1mechasiism. NEMA-

612-1986.

81.6 Extemalcontrol-' Extanal calm1 devices shall be me of thne Eypcs

deaibedbebw: 3.1.6.1 SPEED CHANGER TYPE -mchangatypeisdirtcts,iaDothe governing system which in hun positions the g o m a r coatrolled vaivt(s). The govenoat shall be !Aaxcd to providethe9pecinedadjustaöiespecúrange.

3.1.6.2 ReuOlESET Popsr TYPE ?be remote set poiat type is mcorparated dinxtly mio

thegovanmgsystemwhichinmposi~tbegovam ancudfd valvc(S). Tbc gwawr shall be 8ekctcd to provide the specincd adjustableranges fœ aîi watroiüng patameta9

3.14 3 VALVE ACTlJAlWû TYPE Tbe valveacluating typeissepame h n l ttlegovanœ. 'ïñe extaaal signai acts to positiaa e i t k tbe gmaacr coamiied [email protected]) or a separate liac mounted valve In thiscase.tbe govemxacts oniy asa speeâhiting @e emergeacy)goveniar.

NEMA-

11-14-1985.

3.1.7 speed changer Thespeed changa is a device fwcbging the setting 0fthegoverningsy~withinthe~ifiedspeedrange while the turbineis in aperation. NEhkStrvidard 6-12-1885.

3.2

SPEU) GOVERNING SYSTEM

CLASSIFICATION SpeedgoYeaningsystemSs h a l l b e c ~ a s s h o w n m

Tablt 3-1. NEMA standatd 6-12-1985.

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STD.NEMA

S N 23-ENGL

3993

m

b470247 0524324 8 6 3

m

SM 23-1991 Page 18

--

TWb 3-1 SPEED GOVERNING SYSTEM CLASSIFICATION

A

10

B C

6

0.75 0.50

4

0.25

D

0.50 ~

13* 7* 7*

7*

O Z ~~~~

calsteamrate. Agowrnor system in seMce which meets ali the foliow-

ingwnd.itionsshallbecapableofiimiîingspeedtoprevent --``,`,``,,``,```,``,`,`,,,``,-`-`,,`,,`,`,,`---

overspeed trip when load is suddedy reduced from rateú to zero: a nie driven machine is synchronous perator. b. Thegovernorsystemisoperatinginamodeinwhich it m á s to demand for electrical power. c. niesteamturbinehasaninletpressureofatleast 150 psig i1035 kPa (gauge)]. d. Tbsteamturbineexîmuastoaccm&~. -Range Speed range, expressed as a percentage of rated speed, is the specined range of opeming speedsbeiow or above rated ,$xx!d, or both, for which the governor shall be d j d e when the tucbh is Operatmg nnder the control NEMAStanclard6-12-1985.

3.22 8bximunSpeedRlse The maxjrnum speed rise expressedasa percentage of ratedspeed,isthemaximummomentaryincxeaseinspeed which is obtaineü when the turbine is dcveiopmg rated power output atnited speed and the bad is suddenly and unnpletelyreducedtozeao. Maximum speed rise (%) =

Copyright National Electrical Manufacturers Association Provided by IHS under license with NEMA No reproduction or networking permitted without license from IHS

32.3 speedvariation Speed variaiion, expressed as a percentage of rated speed, is the total magnitude of speed change or fluctuations h m the speed setting unäer the steady state caditiom given in 33.4. 'Lhe speed change is dehedas the difíemœ m speed variation between the governiag system in Operation and the goveZnmg system biocked tobe inoperative,withalloiherconditionswnstant,Sjmdvari&an includes dead band and sustained osciiiati~ Speed variation (+ a)=

~~

* niese Maximum speed Rise Percent values can be achievedunderthef~wi43conditians: a Govemor system is adjustedfop maximum sensitivity. b. Rotational inertia of the equipment is relatively iargeforthepowerrating. c. Steam mditionsproduce a relatively low theoreti-

of~~goveanor.

(SeeFigure3-1for agraphic repmentationof speed rise charactexisticsof a Class D govenior.)

2xratedspeed

(See Figure 3-2 for graphic npresenratiai of speed variation charactaisticsof a Class D governor.) 3.23 DEADBAND Deadband is the totaimagnia>dtofthechange in steady state speed within which thereis no &ring measiirable change in the position of the governor [email protected]). It is a measure of the speed gweming system insensitivity and is expressed in percent of xated speed 9.232 SrMiUn Sîabiíity is theability of the speedgoveming system to position the goveniar conmlied [email protected]) so that a sustained osciliath of sped or of enezgy input to theturbine isnotproducedbythespeedgovemingsystemchniag

operation under sustaid load demand or following a change to a new sustainedload demand. 324 Speed Regulation, steady State Speed regdation, expnxsed as a percentage of rated speed,is the change in gli5t8ined speed when thepower output of the turbine is gradually changed fmn rated power oulput to zen, power outpit mider the following steady state conditions: 1. when the steam mditiom (inlet inlet temand exhaust pressrire) 8Ic set at rated valuesandheidconstant 2. When the speed changer is adjusted to give rated speed with rated power OUlpUL 3. When any exteanai conmldeviœisrenderedinoperative and blocked in the open positfon so as to offexnoresaictionstothefreefiowof steam tothe goveanar controlled valve(s).

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S T D - N E M A SI 23-ENGL

L99L

b470247 0524322 7 T T

SM 23-1991 Page 19

107%

100.0%

i I

I

I

I

w O

a w

I



1

I

I I I

O

LOU)

Figure 3-1 SPEU) RISE NEMA CLASS D GOVERNOR

259

t

Figure 3-2 SPEED VARIATION NEMA CLASS D GOVERNOR

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J

'

100%

STD.NEMA SM 23-ENGL 1991

m

b470247 0524323 6 3 6

=

SM 23-1991 Page 20 --``,`,``,,``,```,``,`,`,,,``,-`-`,,`,,`,`,,`---

P

O

I

1oOY

LOAD

flgure3-3 STEADY STATE SPEED REGULATION NEMA CLASS D GOVERNOR ’

3.3.5

PmssunChanger

Thepressurechangerisadevicebymeansofwûichthe setting of the pressure regdating system maybe changed for the piirpose of aajusting the p m s m of the exhaust staun or ofthe extraction or mduction steam whiie the turbme is m @on. NEMA standard 6-12-1985.

3.3.6 SteaiyStatePressureRegulation Far controlid extraction or conmiled induction type turbines,the steady stare ~ ~ g u l a t i O n i s t h e C h a n g e in sustained extraction or induction pressure when, with identicalsettingsofall parrs of thespeedgoverningsysttm and of the presswe reguiating system(s), the exmxtmn ‘ a iaductian flow is gradually changed from rated flow Io zero flow. Fornoncondensmg ’ turbioesprovidedwithexhauscpressureregdatas,the steady s r a t e p r e s s u r e r e ~is the change in sustained exhaustpmsurewhen. with identical seüings of ail parts of the speed govemiag system and through tbe action ofthe p r t s m r r e m , the powa outputofthesteamtucbineispduaüyreduced6romrateú power output to zero power outpit. NEMAStandard6-12-1985.

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STD-NEMA

SM 23-ENGL

1991

b 4 7 0 2 4 7 0524324 5 7 2 M

SM 23-1991 Page 21 --``,`,``,,``,```,``,`,`,,,``,-`-`,,`,,`,`,,`---

3.3.6.1 PRESSURE REGULA^ Rcssueregulationiscoasideredpositivewhcnprtssure iacreaseswith decrease in steani flow. NEMASEandard6-12-1985.

3.4 COMPENSATED CONTROLSYSTEM Acompcrisatedcontral system is one which is proviâd with intaconneciions between its conml mechanisms so that the action dthe speed governar or of the pressure qdator(s) also directly actuates the Othet control mechanism.

3.3.7 Stablltty Stabiîity is the capabiiity of the pessure regulating NEMASEandaid6-21-1979. system(s) to position the pressurt controlled vaIve(s) so that sustained oscillationsof the coaadled pressrno(s) ar 3.5 ELEC”K= GOVERNING SVSTEM theeaxzgy~puttothesteamturbincarenotproducedby 3.5.1 BaslcFeatures the pressrire regulating SY-m drnmg m m undfx An electronicgovanhg system shaüincludethe foilowmstaimîfiow demands or fauowing achange to another value of sustained flow dtmand. ingbasiccompooeprs: For Ihe pirpose of this standad ~ ~ i l . l a t i1 Sensorswhichmeasureanoperat8igparamctaof ~ the turbineai system, andpoduce ~bY~pressureregulatiagsysteniOfelectricsipah. pressurtar of encrgy inpt are definedas the dinaence b c t w c c n t h o s e e ~ w i t h t h e p r e s 9 u r e r e ~ s y s t e m 2 Agovamx which compares -(s) fnw dic seagor(s) witb the seiectcd set point(s) and padeces a in semicc and thme existing with thepressrinregularing Qgnal(s)fobthevalveactuator(s)tomaintainsystem system blocked or inaperstve. NEW-6-12-1985.

338 Pressum~rolperformanee A Class D goveniOringsystem (see 3.2) shall exhibit the following characteristics when u t i h ú in a comconml system: w . 1 changeinsuseainedspeedshallbe196maximum for any sustamed change in flowwithin limits of 5%and 95%of maximum inductionorexmuionfbw guaranteed forthatload. NEMA-

11-14-1985.

3.3.8.2 Steady state plessare regdation shall be 0.5 psi (35kpa) maximmor496 of ratedexbaust, extrauion.n indmion plesule wtpressed m psig oc kPa (absolue); whichever is larger. N E W S U d d 11-14-1985.

3.3.8.3 sustained 0Scillat.i~of canttolled pressure, wiien aprating at C O I I S E B ~flow ~ demaad op foiiowing a change to another canstant flow, Shan notcxcetdoa psi (1.7 kPa) ar 2% of thecon~fledpnsnireexptssedin psi ob kPa (absolute); whichever is larger. NEMA-

11-14-1985.

Parametebs3. An [email protected])whicb positions the valve(s) directly or though a a m l nucbamm * inIespsetoh gov=SiEm. one or mon of followingparameters shallbecxxumlld bythegovemingsystem: a. speed b. Eachinduction/exaaction~ c. othersforspecificapplicatiom. NEMASE8ndard 11-14-1985.

332The following are accessories which may be selected, aependingonratingaod~ u . 1 CONTROLP~ES Asignal selectmmay be incorporated intbegOVUIIOrt0 aüowthegovenwrrtoreceivesignalsfromse.veralscnsus and tochoose the signal, which wiii result in thc piopa

-

valveopening. Any p aram m may be primary which the governing . . as constant during IK)iTmBI operation. SyAny panunetex could be secondary which is i g n d as lcQgasitisbelow the preset value.

334.4 s ~ o s c i l l a t i ~ o f e i a e r g y i n p u ~ w h e n o p3.599 CONTROLOF INDUCTION OR E X T R A m &gatconstant flow demand or foilowing achange to The governor may be designed to control the low presa n o r h e r ~ t f i o w , s h a U n o t e ~ 4ofratedpcwer. % surevahrt(s) daninductim urextlxtion mine in conjunctian wiíh the high pressure nive(~).in this case,the 338.5 The range of adjustment for ptsmre change(s) governar wnmls the flow to maintain the steam pressure shaü pennit adjustment of exhaust, extraction, or iaducat each controlled extraction or induction opening while tion pressure betweem f5 p i g (35 kPa) M f10% of the simuuaneously controlling speed when necessary for the coamlled pressure expressed in psi or kFa (absolute); appiication. whichever is iarger. NEMA11-14-1û8!j.

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S T D m N E M A SM 23-ENGL L991

Agoveniar with h i s capability incorporatesfeatUtes to adjustaii the ccmtroiied valves in mponse to a change in any controlled parameters. NEMAStandard 1-1-1991.

3.5.23 MISSHG SIGNAL DRECllONFEAtLIRE nie missing signai &tecrion feature monitors all input signahandaetaminesifthey are in the cmect range. Any signai that is out of range shwld cause immediate action by the electmiic govexnor to enSure safe operation of the tmbine,and should cause an alami indication.

3.52.4 SENSOAREDUNDANCV 8.5.2.5 OVU1SPEEDTmP nie overspeed trip feature in the governor can be provided in addition to the primary trip.

3.5.26 other demonic governor accessories m a y be available.

6470247 0524325 409

theirassociafedWiringshouldbepro~fmnheat,weat and induced signais Local codes and area classifshould be conWhenmi~basedturbinecontrolsystemsIrre provided which interface with plant distributed control systems, there may be some overlap of control loops and confusionregardinginpuWoutputs.in these cases the pni chaser and the vendor should mutually agree upon scapt and responsibility spiiL Extemal selpointscan come íknn the piant DCS but the turbine control loop should be suppiieü by the Wine manufacturer. A typid eiec&onic governor schematic is shown m Figure 34. NEMAStandard 1-30-1991.

3.6 AUTOMATIC START CONTROLS Automatic start controls are avaiiabie for turbine and driven machine. nie Wine manufacturer should te msuited for recommendedequipment and pnicediires Auaionred~neeringInfonnabon * 6-12-1mS.

GENERAL Caw shouid be talren in each installation to provide for adequate wiring. in addition, elecmnic governors and

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3.5.3

INPUTS

Figure 3 4 ELECTRONIC GOVERNOR FOR PUMP OR COMPRESSOR CONTROL

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SM 23-1991

Page 23

Section 4 PROTECTION 41.6 Comblned mp and mmle mive Thecambineatrip,and throttle valve is separate fmm the govelnor controlled [email protected]) and is closed (tripped) m response to the action of the overspeed sensing &vicc, other safety &vices or manuai trip device. ?his vaive pennits manual ttirottling of steam to the turbine. NEMA standard 6-21-1978.

4 1 BASICFEATURES Thefollowmgfeaturesandaccessoriesarenecessaryfar the proper functioning of equipment and safety of opera-

tion: 11.1

[email protected]

Each turbine shall be pvided with amanual tripping device to ciose h û i p valve or hip and throttic valve.

4.197

NEMASEandard612-1985.

4.12 ~ M p s y s t e m Theoverspeedtrip system shall besparkpioofandshall include the overspeed sensing &vice, linkage. and a (rip valveora combined trip and bottle valve sepatate from the spceü governor conmiled [email protected]). NEMA-

overspeed

m h g

The tnp speedseauigsshowninTable4-1shall be above the speedreacbeddue to the maximum speedrisecharacEeristic of the govetning system to avoid tripping the turbine on sudden loss of load. NEMA Standd 6-12-1985.

when design or application of driven equipment requires trip speeds other than thoseshown in Thble4-1, the trip speed should be specified.

11-14-1985.

A13 overspeedsensingDevlce The ovaspeed smsing device mc1Udes those elements which are direcily responsive to speed and which initiate action to close the trip valve at apmkammd -speed NEMA standard 621-1979.

Authohcl Engineering Infomiation6-21-1979.

Table 4-1 TRIP SPEED SEmNGS

mspeed Tbt trip speed is the speed at which the overspeed ansing device is set

41A

A B

NEMAStandard6-21-1979.

41.5 TñpVahre "be hip vaive is separate from the goveanor conmiied [email protected])and isclosed (tripped) in responseto the action of

C D

theoverspbedscnsingdcvice,othasaf~&~orman-

*An vrluaueinpe
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