Document jMK45qXdO0YNXGkJzgOb8eRO

TURBINE-GENERATOR Ann *------ L'KB I HE- GENERA T OR AMP ACCESSORIES . NO! TUfBriE9EHEF:A70r AMP ACCESSORIES F'E GENERAL ELECTRIC TURBINE-GENERATOR UNIT I? A 50.00C Xw TAN PET- CDM7 0.JNL , DOUBLI --LOW, CONHENSING, 3600 RPM STEAM TURBINE DESIGNED :-'3R '".\i FIAL STEAM CONDITIONS OF 1250 PSIG, 950 DECREE c., Ev.HAUET:Hu r; .. ' S1!7TF PROVISION FOR DOUBLE AUTOMATIC EXTRACTION OF STEAM AT 'P'S :'"IG AND 235 ,:'SIG AND UNCONTROLLED EXTRACTION AT VARYING PRESSURE. THE TURBINE IS DIRECTLY CONNECTED TO THE HYDROGEN COOLED, 5.4,VOi_T 3600 RPM, THREE PHASE, TWO-POLE, 60 CYCLE GENERATOR WHICH IS RATED AT 58,324 KVA AT 0.85 POWER FACTOR AND 30 PSIG HYDROGEN PRESSURE. FIELD EXCITATION IS SUPPLIED BY A MAIN EXCITER MOTOR-GENERATOR SET; THE MOTOR RUNS OH THREE PHASE 2300 VOLT, 60 CYCLE POWER; THE GENERATOR IS RATED 200 KW AT 250 VOLTS DC. AN IDENTICAL SPARE IS ALSO PROVIDED. NO. 1 TURBINE THE LOW PRESSURE CASING OF THE TURBINE [S SUPPORTED ON LEVEL SOLE PLATES AND THE FRONT STANDARD IS SUPPORTED ON FOUR VERTICAL FLEX PLATES WHICH ALLOWS FOR LONGITUDINAL EXPANSION. AS EXPANSION TAKES PLACE, THE MACHINE GROWS FORWARD FROM THE HIGH PRESSURE END OF THE LOW PRESSURE TURBINE WHERE THE EXHAUST SUPPORT -GOT IS KEYED TO THE SOLI. r'LA7E WHICH CAUSES THE FLEX PLATES TO BEND IN A FORWARD DIRECTION. EXPANSION OF' THE LOW PRESSURE TURBINE CAUSES THE CASING TO MOVE TOWARD THf GENERATOR THE TURBINE CASINGS ARE SPLIT HORIZONTALLY AT THE SHAFT CENTERLINE. TLL JOINTS HAVE METAL-TO-METAL SCRAPED SURFACES WHICH ARE SEALED AMY 7in;.: they are re-assembled with a heavy coating of triple boiled LINSEED OIL. STEAM ADMISSION VALVES (VI> ARE CONTAINED IN THE UPPER AND LOWER STEAM CHESTS LOCATED ON THE OUTER SHELL AT THE FRONT OF THE HIGH i-REGSURE CASING. INTERNAL STEAM EXTRACTION VALVES (CALLED SPOOL VALVES' ARC LOCATED AT THE SIXTH (V2) AND NINTH ;V3) STAGES. THE FRONT STANDARD PROVIDES SUPPORT FOR THE NUMBER ONE BEARING (WHICH SUPPORTS THE FRONT END OF THE HIGH PRESSURE TURBINE), THE THRUST BEARING, MAIN SHAFT DRIVEN OIL PUMP AND SOME OF THE GOVERNING AND CONTROL MECHANISM. 'HE "r JRBIMr ROTORS ARE MADE FROM SOLID ALLOY STEEL FORGINGS SOLIDLY BOLTE 1' TOGETHER BY A SO-CALLED "MARRIAGE" COUPLING BETWEEN THE HIGH AND L mm PRESSURE ELEMENTS. THE ROTOR SHAFT, SEAL AREAS, BEARING JOURNAL. AND ( LULLING F...ANGES ARE MACHINED FROM THESE FORGINGS TO FORM TWO SOLID KOTOR THE TURBINE END OF THE GENERATOR COUPLING IS ALSO MACHINED FRO(r HIS rORGIHG, ----------Wdk VH I^Uf ing and running opera- tlona. The area between the hlgh-p: saure casing and front standard is covered with metal lag; g as is that area between the generator end bearing \ Refer to Procedures Manual for Ti collector ring housing. startup procedure. December 1973 Jm Page 165 DO 125P94 CONFIDENTIAL ^l '.FT AM -A1H 'LAM i"R0f1 THE. :.2S03 MAIN STEAM HEADER FLOWS INTO THE TURBINE MAIN STOP VmLUE WHICH CONTAINS A REMOVABLE, CLEANABLE STEAM STRAINER. THIS VALVE HYDRAULICALLY OPERATED AND IS DESIGNED FOR QUICK CLOSING UFO!I EITHER EMERGENCY DR HAND TRIP OPERATION. STEAM ENTERS THE UPPER AND LOWER ' 'L'RBI ME STEAM CHESTS THROUGH TWO STEAM LEADS FROM THE STOP VftLVE. THE LINE TO THE UPPER HALF OF THE TURBINE CASING IS COUPLED TO F: AC j L..'! rATI. REMOVAL OF THE UPPER SHELL FOR MAINTENANCE. FROM THE STEAM CHESTS, ..TEAM IS ADMITTED THROUGH THE UPPER AND LOWER INLET VALVES (VI) TO THE FIRST PRESSURE STAGE OF THE TURBINE. THE STEAM THEN EXPANDS THROUGH FIVE MORE PRESSURE STAGES TO THE SIXTH-STAGE SHELL WHERE THE 4753 i.V2) VALVES ARE LOCATED., THE STEAM THAT IS NOT EXTRACTED PASSES THROUGH THREE MORE PRESSURE STAGES INTO THE NINTH-STAGE PRESSURE SHELL WHERE THE 2353 (V3) VALVES ARE LOCATED. THE STEAM THAT IS NOT EXTRACTED MIXED WITH ANY THAT IS ADMITTED AT THIS POINT PASSES THROUGH TWO MORE STAGES AND ANY' THAT IS NOT EXTRACTED THROUGH THE UNCONTROLLED EXTRACTION PASSES THROUGH THE CROSS-OVER PIPE INTO THE DOUBLE-FLOW LOW PRESSURE TURBINE. THE STEAM, AFTER EXPANDING THROUGH TWELEVE MORE STAGES (SIX IN EACH DIRECTION) EXHAUSTS TO THE CONDENSER WHERE IT IS CONVERTED INTO CONDENSATE. SHAFT SEALING SYSTEM STEAM LEAKAGE OUT OF THE MACHINE AND AIR LEAKAGE INTO THE MACHINE ARE PREVENTED BY STEAM LABRYINTH PACKING SEALS AT BOTH ENDS OF THE HIGH PRESSURE SHELL AND BOTH ENDS OF THE LOW PRESSURE SHELL. SEALING STEAM OVER AND ABOVE THAT WHICH COMES FROM THE VI, V2 AND V3 PACKING LEAK-OFF IS PROVIDED BY 2353 STEAM FROM PROCESS CONTROLLED BY A SEAL STEAM PRESSURE CONTROL VALVE AND DUMP VALVE ARRANGEMENT. THE SEAL STEAM PRESSURE IS CONTROLLED AT 2 TO 3 PSI ABOVE ATMOS!" HER It TO PREVENT AIR LEAKAGE INTO THE CONDENSER WHICH WOULD RESULT IN LOSS OF CONDENSER VACUUM. WHEN OPERATING AT ANY LOAD, THE TURBINE INTERNAL PRESSURE AT THE FRONT END OF THE HIGH PRESSURE TURBIN;." LB CONSIDERABLY ABOVE ATMOSPHERIC AND SOME STEAM WILL ESCAPE ft) THE ATMOSPHERE AT THIS POINT. ft GLAND EXHAUST SYSTEM CONSISTING 'r A TUBE-TYPE SURFACE CONDENSER AND AIR REMOVAL EQUIPMENT IS USED TO PROVIDE A MEANS FOR DISPOSING OF STEAM THAT LEAKS PAST THE PACKING RINGS. THE GLAND EXHAUSTER MAINTAINS A SLIGHT VACUUM IN THE TURBINE PACKING RING ANNULUS CLOSEST TO THE ATMOSPHERE; THIS PULLS THE LEAKAGE STEAM DOWN INTO THE GLAND CONDENSER WHERE IT IS CONDENSED BY CONDENSATE FLOWING THROUGH THE TUBES AND IS RETURNED TG THE MAIN CONDENSER HOTWELL BY FLOAT TRAPS. IF THE ESCAPING STEAM WAS ALLOWED TO FLOW TO ATMOSPHERE IT WOULD CONDENSE OUT OH COOLER PORTIONS OF THE TURBINE LAGGING CAUSING CORROSION AND ALSO POSSIBLY TRAVEL PAST THE BEARING OIL DEFLECTORS, MIXING WITH THE BEARING OIL WHERE IT WOULD BE CONVERTED INTO WATER AND CON TAMINATE THE SYSTEM. , AIIA0 ran MQ --- admitted to the/ low-pressure packing to prevent air leakage into the condenser. When operating et normal load, the turbine Internal pressure at the high pressure end Intermediate pack-- lng is considerably abov^e atmosphere and, therefore, at this condition steam will escape from the. turbine at these points. ( Dec mber 1973 J Page 166 CO 125295 CONFIDENT TAi TURBINE-GENERATOR AND ACCESSORIES (cont'd) C A gland exhauster^ constating of a shell and tube-type surface condenser and air removal equipment, is used to provide means for disposing of steam that leaks past the packing rings. This exhauster system maintains a slight vacuum in the turbine shaft packing rings closest to the atmosphere, thus preventing steam from escaping to the atmosphere. The turbine can be operated without the air removal equipment, but this is not desirable. The escaping steam would condense out on the cooler metal surfaces in the area and cause corrosion. It is also possible, and some times It does happen, that the escaping steam vapors will get past the bearing oil seals and become entrained in the oil, thus contaminating the system. \ ;\ 1 Control Mechanism and Governor Under normal operating conditions, the speed and load of the unit are controlled by the TS-500 located in the Control Room. The Tri-Sen Speed Processor s dedicated microprocessor substystem used to monitor and analyze pulse input signals from up to four magnetic pickups (two on the turbine and 2 on the Be"a*r> * These speed probes are located in the front standard of the turbine and on the outboard and of the generator rotor. These signals are c0"v""^`ft"1"''main processor to a digital nord proportional to speed (rpm) a"d """`"^n" '5or to computer system for use in its control program. The speed of the machine * synchronizing are controlled from the TS-500 front panel which is the principal operator interface. --. ... gvyciuvi iarre gu ujjciai_e anu cne macDine overspeeds. In the_caae of overspeedf the emergency governor releases a valve controlling oil .supply, to the emergency stop valve, causing It to close and thus shutting off .the supply of steam to the turbine,. The emergency stop valve Is of the quick closing type and functions primarily by being tripped to close either by hand or by overspeed of the turbine. The valve Is fully open when oil pressure from the turbine hydraulic system Is permitted to flow past the emergency tripping mechanism pilot valve to the operating cylinder piston of the stop valve. The valve is fully closed when oil pressure is not maintained under the operating cylinder piston as the result of either failure of the hydraulic system or overspeedlng of the turbine. In the latter case, the emergency governor pilot valve shuts off the oil supply to the stop valve and at the same time opens a dump thereby relieving the oil pressure under the operating cylinder piston which results In closing the stop valve by spring action. The operating cylinder of the emergency stop valve is equipped with a tast to permit periodic testing t make December 1973 Jm Page 167 DO 1 conftdfnttai TURBINE-GENERATOR AND ACCESSORIES (cont'd) sure that the valve stem Is not sticking. This ** < made by operating the test valve on the * thereby allowing from under the piston. Since In operation the piston of the operatingcylinder Is at a position above the drain to the test ve&cy^wlth this relief in oil pressure the piston will start to travel in the valve closing direction until the port Is covered by the piston. At this point, the piston and main disc will again travel In an upward direction due to full oil pressure on the bottom of the piston, A cutout switch Is mounted on the stop valve to operate the generator flrli>etseutt breaker when the stop valve closes. Load-limiting andlsynchr^ilzing devices provide means of changing the speea or koad on the unit. The load-limiting mechanism Is used If01^1 tarting the unit, bringing It up to speed In comblnatilny^lth the speed-changli^g or synchroniz ing device, for limiting the steam flow and KW load, and for shutting down th&4inlt. The synchronizing or speed-changing device Is used ho aegulate speed or load in combination with dr independently oAthe load-limiting mechanism, depending upon whether ^che unit Is operating Isolated or In parallel with other units. December 1973 Jm Page 168 i! > Prior to starting the turbine, several items must be verified. (Refer to Safe Work Procedure "Starting up Steam Turbine //1). With the stop valve open and 1200 psig steam chest pressure, the start sequence "Ready" light will be flashing, indicating that the unit is ready to operate. The amount of time recommended to bring the unit to rated speed is dependent on the time the unit has been shut down. (Refer to curve in G. E. Manual). The starting sequence is done automatically in 3 stages with the operator initiating each stage of the sequence. The 3 stages of the starting sequence are: 1) Slow roll, 2) energize field, and 3) ramp to synchronous speed. The first ramp rate controls the amount of time to reach the slow roll level of 500 rpm. The second ramp rate controls the ramp speed from 500 rpm to 3600 rpm with a hold in the startup sequence at 800 rpm to energize the field. Shutdown of the unit is done from the TS-500 panel in the Control Room. (See Safe Work Procedure , "Turbine 24" - Steam Turbine 1, 2 & 3 Shutdown). , T-------------------^ T_ J J3uvud). CtgCL O^r-jy- O __ _Cr^AJcA U _o*_ . ______ _____________ _ . f^O f. is hna i4_Qj_ cv\s_ judb .|jjcn^ ~?~S~SOO pna .Cj..CfcSJtcV. mJ^ gj^kA^j JLinui-v- TSbi. TS ~S^O O ____________________________ dtSLa. I _ .Ml -lk_ -tfc '_A ^a> e, i iT\ j>peJZc$l~/^OQd- T. -- T. <. A_______ . ^ - (J&CJlZJjS ^ D 1?SP98 CONFrDFNT TAI iwith the, extraction sMBtemmciyayaiiahle ,'yith-alltste'ajr.nc^^f^^^tf^a^ Yah-berre&d^MgffffithT@TM&riagyfl?^^ iettnrblne,, operating valves wider than'h6ma'l>~and"*th^pressure's af'the^tiir'binb'^iftfactlon "s'tag*es"('SSa>,^f^,0thoseJ preceiSlng) are" l^6rrgb'ted^y^thi!h^mprove'(f efficiency" of~tKe~unit" relative to norma!!^ To,,guard against^e^enj^y^of steam into the turbine through the*! eVtractibh>llhes1%)^ir^itraS'tlohalitrd"'i8"i!pf6vided'vith -air-air - ? 'operated,' free'flow'reveirse `current' valve whicHTs'intercomected with the turb1nb'"~diItiySS^aultiC^system of'the','tfip"iahd^oversp'eed ... protection .mebhiM^^''means"6f'the' non-return`Valve tbip' relay.' ^^l^b^event^'ihe^'Sj^Dfiie trips, a double seated valve" in the relay which moves in response to oil pressure on a spring opposed piston cuts the air supply to the non-return valves thus closing it. Hand operated air test valves are provided to permit routine operating checks to insure that the non-return valves are ready to function when called upon to do so. A low vacuum trip which also is an element of the trip and over speed mechanism functions to shut off the steam supply of the tur bine in case of loss of vacuum. If the vacuum drops to 15 inches the relay will dump the oil pressure in the governor system and so shut off the steam supply at the stop valve. An alarm signal which is annunciated on the mechanical vertical board is provided to indi cate that it is low vacuum which has tripped to close off the oil supply. lubrication System The turbine provided^ ^" LUBRICATION' AND HYDRAULIC OIL SYSTEMS ;LL I URHI ME IS PROVIDED WITH A SELF-CONTAINED OIL PRESSURE SYSTEM LOciirSIiNO if A lube oil reservoir, pumps, coolers, filters and PIP!NS ""OR SUPFLYING OIL AT A PRESSURE SUITABLE FOR BOTH THE FYlPA'Jli: ANT LUBRICATION NEEDS OF THE Uhilf THE SYSTEM CONSISTS OF 'IF'F.E 'COPS WHICH ARE INTERLOCKED; THE MAIN CENTRIFUGAL PUMP DRIVEN BV THE TURBINE SHAFT, A SEPERATE STEAM TRUBINE DRIVEN AUXILLALRY PUMP AND A TURNING GEAR MOTOR DRIVEN PUMP. BOTH THE HYDRAULIC AND LUBRICATING SYSTEMS ARE NORMALLY SUPPLIED BY THE SHAFT DRIVEN PUMP LOCATED WITHIN THE TURBINE FRONT STANDARD. THIS PUMF DELIVERS OIL AT 200 PSIG FOR ACTUATING THE HYDRAULIC CONTROL APPARATUS AND ALSO SUPPLIES HIGH PRESSURE OIL TO THE OIL TUFBINE DRIVEN BOOSTER PUMP IN THE LUBE OIL RESERVOIR. THE BOOSTER 'CMP f'F.0vi'iES I HE SHAFT DRIVEN PUMP WITH SUCTION OIL AT ABOUT 11 Pblt. Fit. 200 PSIG OIL THAT IS USED TO DRIVE THE HYDRAULIC TLT'BINE IS REDUCED IN PRESSURE TO ABOUT 65 PSIG AS IT ACCOMPLISHES THIS WORK; IT IS THEN REDUCED IN PRESSURE TO 25 PSIG BY THE BEARING ''RESSURE REGULATOR WHICH IS LOCATED INSIDE THE RESERVOIR. THE r-F(`p INC' 1H. THEl' FLOWS THROUGH THE FULL FLOW FILTER, THROUGH THE COOL'-P AND INTO THE BEARING SUPPLY HEADER FOP LUBRICATION OF rUP2'!IE-GENERATOR BEARINGS, A BACK-UP SUPPLY TO THE GENERATOR HYOPGGE!-! .-.E--.L GIL SYSTEM AND TO OTHER SMALLER COMPONENTS THAT RLCU1RL -L:.. Hi REDUCED PRESSURE. ,,_____ rage i /u DO 125299 CONFTDFNTTAl The booster pump Is located in the main oil tani and consists of a conventional pump casing^ housing a rotating element^ comprised -e - -i----iiv - hiieket wheel Tluvin+ert <">" ana """ THE BO1u1 STI r.R PUMP, WHICH IS LOCATED INSIDE THE RESERVOIR, CONSISTS Or RATHER CONVENTIONAL CENTRIFIGUAL PUMP CASING HOUSING A ROTATING 1 !'MEWT WITH AN IMPELLER ON ONE END AND A TURBINE BUCKET WHEEL OH i HE OTHER END,. THE BUCKET WHEEL ACTS AS AN HYDRAULIC TURBINE AND IS DRIVE!! BY A PORTION OF THE HIGH PRESSURE DISCHARGE OF THE SHAFT DRIVEN PUMP. THE ROTATING MOTION DRIVES THE IMPELLER ATTACHED TO `U;L OTHER END OF THE SHAFT, PUMPING OIL FROM THE RESERVOIR TO THE SC!. '[OR O'' THE. MAIN SHAFT DRIVEN PUMP. THE ENT IRC CYCLE IS INITIALLY STARTED BY THE STEAM DRIVEN AUXILLARY OIL PUMP WHICH. 13 USED r'GI CTART-LT BUT IT IS ALSO CAPABLE OF DOING THE EXACT SAME JOB AS ';JE SHAFT DRIVEN "'UN-',, THE AUXILLARY STEAM TURBINE DRIVEN OIL PUMP IS USED TO SUPPLY LUBRICATING OIL TO THE BEARINGS, TO OPEN THE STOP VALVE AND FOR CONTROL OF THE VI, V2 AND V3 VALVES DURING THE STARTING OPERATION WHEN TURBINE SPEED IS TOO LOW FOR THE SHAFT DRIVEN PUMP TO ACCOMPLISH THIS TASK. THIS PUMP IS ALSO IN A STANDBY MODE DURING NORMAL OPERATION OF THE TURBINE SUBJECT TO THE CONTROL OF THE AUXILLARY OIL PUMP PRESSURE GOVERNOR, WHICH IF CORRECTLY ADJUSTED, WILL START THE PUMP AUTOMATICALLY ANYTIME THE STEAM BLOCK VALVE TO THE PUMP IS OPEN AND THE HIGH PRESSURE GIL SYSTEM DROPS BELOW THE SETTING OF THE PRESSURE GOVERNOR. A BY-PASS VALVE IS PROVIDED FOR USE IN APPLYING STEAM TO THE PUMP TURBINE l'N CASE OF FAILURE OF THE PRESSURE GOVERNOR. A "T" HANDLE ARRANGEMENT IS PROVIDED FOR CHANGING THE SET POINT OF THE PRESSURE GOVERNOR CAUSING THE PUMP TO COME ON AUTOMATICALLY A'! A HIGHER OR LOWER PRESSURE. A TEST VALVE LOCATED OH THE NORTH SIDE OF THE RESERVOIR CAN BE USED TO TEST THE OPERATION OF THE PRESSURE GOVERNOR DURING NORMAL OPERATION OF THE TURBINE. THE !URNIMG GEAR MOTOR DRIVEN OIL PUMP IS JUST WHAT THE NAME IMPLIES; IT IS USED WHEN THE TURBINE IS DOWN AND ON TURNING GEAR FOR THE PURPOSE OF SUPPLYING OIL TO THE BEARING SUPPLY HEADER. IT WILL COME OH AUTOMATICALLY UPON LOSS OF PRESSURE IN THE SYSTEM. TWIN OIL.. COOLERS, EACH CAPABLE OF COOLING THE TOTAL OIL DEMANDS Of THE TURBINE, ARE PLACED A7 ONE END OF THE RESERVOIR. WATER FLOW FROM THE PLANT COOLING WATER SYSTEM IS CONTROLLED BY THE VIDEO-SPEC SYSTEM IN THE CONTROL ROOM, THE COOLERS, ONE IN SERVICE AND ONE ON STANDBY, CAW BE TAKEN IN AND OUT OF SERVICE BY A COOLER TRANSFER VALVE LOCATED WITHIN THE RESERVOIR. LI turbine beaxinn drat"-------^tErT LOCATED SOUTHFbF^SUAPPED WITH ="iSSfS. rjws&r-sr THE TURBINE ON1*^ uhit CAN HUSO BE ________ THETf oEELOCATEt TM THE PIP*. __ _____ Asa UAVL VnL __vTi irclAn T* ifi January, 1974 Page 171 DO 135300 CONF JDFNTTAI is mounted on the lube oil reservoir to exhaust water vapor to the atmosphere and to provide ventilation of the entire lubrication system. Approximately one-half inch of water vacuum is maintained in the reservoir by the vapor extractor. A high pressure alarm indicates loss of vacuum in the reservoir. The generator bearings are equipped with a seal oil system to prevent the escape of hydrogen from the casing along the rotor shaft or the entrainment cf hydrogen in lube oil returned tc the reservoir. Oil from the air side of the seals drains to bearing drain enlargement which is used as a chamber where air entrained in the oil may be liberated and vented to atmosphere. The drain oil then passes through a loop seal to a connection box where it mixes with the drain oil from the outboard side of the generator bearings and is returned to the main oil tank. The loop seal provides a wet barrier between the bearing drain enlarge ment and the oil storage tanks, and in the event of failure of the shaft Beals, hydrogen 1b vented to atmosphere from the bearing drain enlargement instead of passing on to the main oil reservoir. The oil flowing to the hydrogen side of the shaft seals passes into the drain lines and thence to the seal drain enlargement, which consists of a horizontal length of closed pipe divided by a baffle into two equal sections. Both sections are pipe connected at the bottom and drain through a loop seal to the seal-oil con trol unit storage tank. This arrangement prevents the circulation of oil vapor through the seal drain piping from any difference in fan pressure existing at opposite ends of the generator. The seal drain enlargement provides a large surface area for the oil, and this permits the removal of large bubbles of hydrogen from the oil before it passes into the storage, tank. The seal oil unit is an assembly, mounted on a common base, comprising the storage tank, float trap, seal-oil pumps, pressure governors, oil filters, high oil level alarm switch, oil pressure relief valve and gauge board. The Btorage tank is provided as additional source of oil for the seal oil control unit pumps when the seal-oil pressure demand ex ceeds that being supplied by the bearing header. The floav trap prevents the loss of hydrogen through the seal oil storage tank vent line when operating at elevated hydrogen pressure. Whenever seal-oil pressure is needed in excess of that being supplied by the bearing header the additional seal-oil pressure is supplied through the operation of one of the two seal-oil pumps. The dif ferential pressure governor is adjusted to maintain a seal-oil pressure slightly higher than the gas pressure in the generator casing. The second pressure governor is adjusted for a seal-oil pressure of about 1/2 lb. lower than the first pressure governor. This second pressure governor is used as a standby in case the first pressure governor fails to operate. Two cleanable oil filters, connected in parallel, prevent foreign matter in the oil lines from passing to the shaft seals. Differential pressure switches are mounted on the gauge board, and these switches are electrically con nected to actuate either the main seal-oil pump, the emergency seal-oil pump, or the low differential pressure alarm. The switches January, 1974 Page 172 DO 125301 CONFTDFNTTAl ; .SUSP's sense the seal-oil pressure with respect to^the gas pressure in the casing, and bring the pumps into operatic' as needed. An electri cal interlock is provided in the wiring^of each seal-oil pump motor so that when either motor is^running, the other motor is pre vented from coming into operation. Another pressure switch senses the main seal-oil pump discharge pressure. If this pressure dropped to some predetermined value, and the main motor pump ceased to function, the discharge pressure switch would override the interlock on the main seal-oil pump, and bring the emergency pump into opera tion. A seal-oil pressure relief valve is connected into the dis charge side of the seal oil pumps. The oil, in excess of what is necessary for shaft sealing, is discharged through the valve to the suction side of the pumps. A float ,switch and sight flow gauge are incorporated in a pipe line from the seal drain enlargement and when the level of the oil in the seal drain enlargement rises sufficiently, the float switch closes an alarm circuit which indicates that abnormal condition exists which prevents proper draining of the seal drain en largement. The gauge board is mounted on the seal-oil control unit - -oiicres _for measuring seal-oil pressure, and hydrogen --Tn-oreinent. The gauge board also carries -an2dS_Storage ror cnditionine ^Ployed itl whih turb*ne lubricati puffiPs is used h centrifuge tv* g 011 a contin b\lns headers U i-STtESS* "lth "SS f*T" la the suction - - Lube oi* fW ?.!U8h a ^U~flnJ^f.feed *nd dis,hJt w..h.e.re. ,, ,, f the cntrl,'1"* by SravityUfr'fl" fUtor; befTM urge 011 to* " - ooUda " I' '< Pump.7!," the oil to che purified reservir dispj "s centrn u6^ . The amount of incoming wtu.. amount of dirty oil which flows fier. reservo?r.^ same amount of A lube oil storage tank with three compartments is provided for scor ing a reserve of fresh oil in one compartment, a change of purified oil in another and for receiving a full change cf dirty or contaminated oil in the last. Each compartment has an electric heater to keep the oil at maximum temperature of l40. A 50 gallon per minute lube oil transfer pump is installed for pump ing oil from either compartment of the storage tank into the turbine reservoir or back into either storage tank compartment. A 50 gallon per minute lube oil return pump is provided for pumping oil from the turbine reservoir into either compartment of the lube oil storage tank. ,, Turning Gear \ The turning gear and drive motor are mounted in the number three turbine bearing housing. The turbine shaft is driven by an induction January, 1974 Page ,173 , 00 1 CONF rDFNTlAi ~ \ J "To __ &*rJ -*SV^GJdfr* C^L .J.'AaSwoi O pJ"' ` *\f>t;- ') O"-*- Cr^riri (~j * J^Jtt-'^` JlA., ul-j-<AXL- I . ,JJL>. xj/v 'T , J<r: '.V^'. ^ fi!^-J .oI JiitL. ^<Uiawj."+Cj *t,.;,'c_. oo lLoc* r/Y-* jX^tt .`ii " ^/v).-*^. zAXjJ r/i^r.-c-'L utJJ-V- CX ,Ak^ A^V^ ^ jr^ ^ T'j *T a * f 0C/v^jt1i. d^lii^JtiJa^'-- . j C?Qj&-j ^jnoj*3^sn^ri- cvmX. jJ^,_ i^ p(U^, JL ^y lfcRe>__ Cj3~ _CfSfeo-C' f^oo^*nL i J /Siji4i_ --*A*Si^L_I!fcRJ _^WrvtJ^c. ^O/uxJ-eLiX' jLaA/a^iihlI {&*&* ^O'CaudLi/*^ _ ^ ^ ^ *n n n " o^- <y^j9-c, r^jk/i ---g--j------- f-1-ri I_r^ -------- -- -------------- ---------------------- 1----------- ^ *--------1~" ` _________ lAujSilHJr-*'-___ t^itAS- _0**dLs jQji-^s-i_%i, n/>A^ZA^aa^________ 7<^. 4Six<^ rA tj^lo/ijTjF. gc-J ; ' C^*lojo*jsa*__. QhdL ^Ji.u!-'_ CHuj ______ jaJLcia*ifte_O^, . l^JUUiSrO'J-' _D-tJc5L?_ iAjJlJa*V^ _Uj .... ; CUhdL. ..^RA^Lija^ . j^k^zsJ^MfJkAy . ___ _ _ _._ _. . ____ --L V --- - - - - rnP 1 ^303 - - CNFrDFNTTAl B. Speed and Cam Position Kndicatoiy- This instrument provides a permanent record of tae speed^f the unit during starting and shutting down perio* and w record of rotation of the control valve cam-shaft Vhile Ahe unit is connected to the line. Since valve opening am load cn the machine are functions of cam position, the et'featsfcf system disturbances, which are not discernible on a speedVecord, are clearly shown on the cam position record. TheyaVstrument automatically switches from speed recorder to cmm rosition recorder when the main generator breakers are XiosecL The speed signal is trans mitted from a tachomeyr gerie\ator located on the end of the turbine shaft within Mne fronf^standard. Cam position is transmitted through m wire wound voltage divider and arm mounted on the end m the control valve cam-shaft. C, Eccentricity Recorder - A continue^ indication and record of shaft eccentricity islkept by Jmis instrument. The eccentricity is measuredfLn milyauring turning gear opera tion. This information i' parjjicularly valuable during the starting operations in de ing the amount of shaft bow. A detector coil is mounte ,hin the front standard housing on a rigid bracket with tb ole tips spaced a specified dis- tance from a concentric r 6n the turbine shaft. Any variation in this gap ca^be by shaft eccentricity is trans mitted to the recording JLne ient. Excessive eccentricity is annunciated on the nechanlcai vertical board. N D. Vibration amplitude recorc r -~Th*E recorder provides a periodic record, in mils, of the trl isveire vibration occurring at each of the main turbine general arings. A-C signals, generated by detectors mounted on eac the bearing caps, are trans- mitted in sequence to the ording instrument. Excessive vibration is annunciated e mechanical vertical board. Details of oplj^cion, calibration, tallation and maintenance of all superv^rory instruments are contained in the manufacturers' Instruction Imk, No. 1 Generator The hydrogen-cooled generator is completely enclosed for operation with hydrogen gas as a cooling medium. The ventilation system is completely self-contained, including gas coolers and fans, thus preventing the entrance of dirt and moisture. The separately ex cited rotating field, driven by the steam turbine, rotates inside the stationary armature and is supported by bearings located ir. the end shields mounted on the generator frame. The stator, according to the manufacturer's description, is made sufficiently strong to withstand safely the force of a hydrogen-air explosion. January, 1974 Page 175 00 175304 CONFIDENT TAL The stator frame consists of a gas tight cylindrical casing of welded plate construction, reinforced internally in the radial direction by stationary web plates, and in the axial direction by spring bars and braces. The stator frame is supported on the foundation by feet welded to the sides of the frame. Heavy end shields which contain the generator bearings are bolted to the ends of the frame. The frame also serves as the support and enclosunv for the gas coolers. Ihe stator cone is made up of segmental, annealed, insulated punchings of high quality silicon steel to give minimum electrical loss. The punching insulation is a varnish which maintains its insulating value under the most abnormal ef fects of heat. The stater winding is composed of insulated bars, which are made up of insulated copper conductors or strands and arc assembled in the stator slots, Joined at the ends to form colls, and connected in the proper phase belts by bus rings. The stator and rotor are ventilated by axial flow type fans with individual blades that are fastened to fan hubs near the ends of the rotor. The rotor is machined from a single alloy steel forging with logitudinal slots machined radially in the body which contain the field coils. Additional slots are machined in the teeth to provide ventilation for the rotor body. The field winding consists of rectangular copper bars, edgewise bent and formed into coils. Several turns in one pair of slots around a pole form a ceil. Several coils are assembled around each pole to form the winding. Connections, Excitation Switchgear, Metering and Generator irotection These are all described in the Electrical Section. Exciters Field excitation is provided by an indoor type, fil'ered air cooled, main exciter motor generator set, 200 KW at 250 volts d-c exciter and 23OO volt, 3 phase, 60 cycle motor. Spare excitation is pro vided by an identical motor-generator set. This exciter is als; a space for 2 generator. Refer to Procedures Manual for starting up, paralleling, and securing exciters. Cooling System Hydrogen is used as the cooling medium for the generator because of the smaller windage loss and because of its higher rate of heat transfer. Also, with hydrogen, less maintenance is required since dirt and moisture are excluded and less deterioration of insulation occurs due to corona. January, 1974 00 125305 CNFTD ENTTAl. Page 176 Hydrogen within the sealed generator stator J.s circulated to all parts of the stater rotor by the fans mounted on each end of the rotor. The hydrogen is cooled by circulation through four generator gas coolers thac are mounted vertically at the four corners of the stator frame and using plant cooling water as the coolant. A gas dryer is provided to insure a dry atmosphere in the generator. To prevent leakage through the bearings, the generator shaft is sealed by a floating ring oil seal. Oil is supplied under pres sure to create an oil film between the sealing rings and the shaft to prevent leakage of hydrogen along the shaft. TBimaal Moneys temJdP^^e^gW^*4/hie^vrtypnt Piping and control equipment are provided so that carbon dioxide may he admitted into the generator casing prior to filling the generator with hydrogen to prevent formation of an explosive hydrogen-air mixture. The air is first purged by carbon dioxide after which hydrogen is admitted. The hydrogen instruments and alarms are mounted on the hydrogen control panel. A complete alarm system including reset switches, audible alarms, trouble indicating lights and alarm voltage failure circuits is provided to operate on low pressure, high temperature, low purity, low hydrogen supply and low seal oil pressure. Operation of the hydrogen panel alarm system also annunciates il n uNff^llHlilnii lanl *iii I li'inl limiin'iHn the control room. The generate* uju.mgeu ojro^ciu ucauiibed in the General Electric Turbine-Generator Manual. January, .1974 00 125306 CONFTDFNTTAL Page 177 ) C9ou >1 DO 1 7 5 3 0 7 CONFTDFNTTAl NO. 2 TURBINE -GENERATOR AND ACCESSORIES General The General Electric turbine-generator unit no. 2 is a 60,000 kw tandem compound, double flow, condensing, 3600 rpm steam turbine designed for initial steam conditions of 1250 psig, 950 f., exhausting to 2" HgA with provisions for single automatic extraction of steam at 235// and uncontrolled extraction at varying pressure depending on load. This unit was de-rated to approximately 62 mw in 1988 for economy reasons. The turbine is direct connected to a 75,000 kw, h2 cooled, 14,400 volt, 3600 rpm, 3 phase, 60 cycle generator which is rated 88,253 kva at 0.85 power factor at 30 psig hydrogen pressure. Field excitation is identical to #1 unit and they share a common spare exciter. cycle Inoto^. The J^ame spare exciter is utilized for this unit." No. 2 Turbine The turbine exhaust casing and the turbine front end standard are supported on a level sole plate. As expansion takes place, the machine slides forward on these plates from a transverse anchor key located between the center exhaust sole plate and exhaust casing support footing. The turbine casings are split horizontally at the Bhaft centerline. All Joints have metal-to-metal scraped surfaces. Steam admission valves are contained in the upper and lower steam chests located on the outer shell at the front of the high pressure casing. Steam extraction valve is located at the eighth stage. The front standard provides support for the high pressure casings, the number one main bearing, thrust bearing, the main oil pump, and the 400 cycle generator for governing and control. The turbine rotors are made from solid, alloy steel forgings solidly bolted together between the high and low elements. The rotor shaft, seals, bearing Journals, and coupling flanges are machined from these forgings to form a solid rotor. The outdoor unit is protected against adverse weather conditions by sheet metal lagging provided with weatherproof Joints. An enclosure is provided over the turning gear and adjacent machine parts. This enclosure is provided with a door for access to the turning gear controls and to permit observation of the turning gear engaging and running operations. The area between the high pressure casing and front standard is covered with metal lagging as is that area between the generator end bearing and collector ring housing. Steam Path Steam from the "boiler jmperheater outlet passes through the main turbine stop valve, in which-is located a steam strainer. This January, 1974 Page 179 DO 125308 CONFTDFNTTAl. ',, / b. no. 2 turbine-Generator and accessories (contd.) General (COntd.) valve is hydraulically operated and is arranged for quick closing upon either emergency or hand trip operation. Steam enters the upper and lower turbine steam chests through two steam leads from the stop valve. Steam is admitted to the turbine nozzles by the control valves. These valves control the flow of steam through separate passages In the turbine shell to particular sections of the nozzles. They are raised and lowered In proper sequence through action of their levers which ride on cams mounted on a camshaft. The camshaft is rotated by the hydraulic operating mechanism through a lever with a gear segment and a pinion. The camshaft for the lower valves is actuated by a rod fitted with a rack. The rod and rack assembly is connected to the lever driving the camshaft. During starting, the movement of the controlling valves is under hand control of the operator through the load limit mechanism. When operating speed is reached, the speed governor controls the movement of the inlet valves. From the control valves the steam is admitted into the first pressure stage and to the first stage shell. The steam then passes through 5 more stages into the 7th stage where the 235 psig extraction valves are located. There are provisions for extracting steam at either the 8th or 10th stages for deaerators heating also. The steam then expands to the 12 stage, through the crossover pipe and into the center of the low pressure double-flow section. The steam after expanding through four more stages exhausts to the condenser. Leakage of steam along the shaft between stages is minimized by labyrinth special bronze metallic alloy packing placed at the shaft base of the diaphragms and having close clearances between the rotor and packing teeth. The turbine exhaust casing and condenser are protected against excessive back pressure by an atmospheric relief diaphragm located on the top of the exhaust casing. This diaphragm is designed to relieve at 5 psig and to pass maximum throttle flow. Shaft Sealing System SAME~AS~~#1TURBINE "V December 1973 gm Page 180 ,,D0 1?5309 CnN^TDENTTAl. A gland fcxhayter, consisting of a shell and tube type surface condenser\n<yair removal equipment, is used to provide means for disposing steam that leaks past the packing rings. This ex- hauster sy, i maintains a slight vacuum in the turbine shaft packing closest to the atmosphere, thus preventing steam from es inc Control Mechanism and Governor There are essentially two major sections which comprise the control system of No. 2 Turbine. They consist of turbine control console containing the "electronic computer section" and the high pressure hydraulic power pack which makes up the "hydraulic fluid power" section. The computer is composed of a number of simple, electrical, solid state circuits which are capable of providing the "intelligence" functions needed to control the position of the turbine control valves. The "muscle" power required to move the control rams, in correspondence with the computer command signals, is provided by the companion high pressure hydraulic system. r Under normal operating conditions, the speed of the turbine rctor is sensed by a permanent magnet generator (IMG) driven directly by the turbine rotor. There are two purposes of the IMG: first, it serves as the source of power for the computer when the turbine rotor speed exceeds 3300 RIM and second, It serves as the source of frequency signal which controls turbine speed. IMG frequency signal is converted to DC control voltage. Hence, changes in turbine speed will show up as a change in DC level. Speed control is thus effected since the position of the turbine control valves is sensitive to ^/the magnitude of the DC control signals. Once the unit is electrically synchronized the speed load control mechanism establishes the KW power level of operation. This function is accomplished by varying the magnitude of the DO reference signal - the higher the DC signal, the farther the con trol valves are open, hence the larger the load. The adjustment of the DC load can be made locally, at the control console panel, or remotely by energizing the mechanically connected positioning motor. The emergency or overspeed governor operates independently of the speed governor and is designed to shut down the unit in case the speed governor fails to operate and the machine overspeeds. When overspeeds occurs f the plunger of the emergency governocr movefT out wardly to _atrike a trigger to unlatch the steam inlet valve to'close off the steam supply to the turbine. This emergency governor may also be tripped at rated speed by a manually operated valve which injects a stream of oil into the governor to upset the balance of the plunger and makes it move outwardly to trip. January, 1974 00 125310 CONFIDENT TA1, Page 181 This turbine has a "stop-valve test" device similar to that on No.l Turbine. It is also equipped with a shutout switch on the stop valve which opens the generator breaker when the stop valve closes. Steam flow to the turbine is controlled by the turbine load limit ing and speed changing mechanism. The load limiting device is used for starting and stopping the unit; bringing it up to speed ir. combination with the speed changing as synchronizing device; and for limiting the steam flow and KW load. The synchronizing or speed changing device is used in combination with or independent of the load limiting mechanism, depending upon whether the unit is operating Isolated or in parallel with other units. This turbine is also equipj&d with air-operated, free flow reverse current valves on the extraction lines which guard against steam re-entry into the turbine in event of a trip. These valves are similar to those on No. 1 unit. A low vacuum trip will shut off the steam supply to the turbine in case of loss of vacuum. This device is similar also to that on No. 1 unit. Lubrication System Turbine No. 2 is provided with a self-contained lubrication system which consists of a Bupply tank, pumps, coolers, strainers, gauges, piping, etc. The main oil tank provides the oil supply and houses most of the components pertinent to the lubrication system. This tank is equipped with high and low level alarms and also a high tempera ture alarm. As a protection against hydrogen explosion damage, the reservoir is equipped with hinged relief doors. A motor driven vapor extractor is mounted on the top of the lube oil tank for the purpose of exhausting water vapor to the atmosphere and to pro vide ventilation for the entire lubrication system. Approximately to 1" of water vacuum is maintained in the reservoir. The ex traction is equipped with an alarm in case of low vacuum ir. the reservoir. During normal operating conditions the turbine's lubrication needs are supplied by a centrifugal pump driven by the turbine shaft. This pump takes suction at approximately 18 psl from a turbine driven booster pump located in the main oil tank and supplies 190# oil to the emergency trip mechanism, emergency governor exerciser, steam seal regulator, the booster pump and various alarms and pressure switches. This 190# oil, after leaving the booster pum& is reduced to 75 psi by means of a relief valve before going through the lube oil coolers to the seal oil system and bearing oil regulator. An auxiliary ateam driven centrifugal pump located on and within the main oil tank la provided to initially establish oil pressure in the system when starting or stepping the turbine and to supple- January, 1974 00 1?5311 CONF TOFNT T At Page 182 'V u went the main shaft driven pump. This steam driven pump is subject to the control of a pressure governor which operates in response to pressure changes in the system, starts auxiliary pump when main pump pressure is insufficient, and stops it when pressure is restored. Lubrication of this pump is by means of passages from the pressure side of the pump to the bearings. A centrifugal turbine driven booster pump is provided to supply suction pressure to the main oil pump and is located in the main oil tank. This turbine driven oil pump is moved by a portion of the main pump output pres sure (or auxiliary oil pump) and is adjusted to produce 18 psi out put to the main oil pump suction. Adjustment is by means of a baffle valve to increase or decrease oil flow against the turbine oil pump buckets to vary speed and thereby vary output pressure. 75# oil from the relief valve, on the driving end of the booster pump, after going through the coolers is further reduced by means of a pressure regulator before going to the turbine shaft bearing. This 75# oil also goes to the turning gear interlock and the ground ing brush nozzle. An alternate source of bearing oil is supplied, if needed, by a motor driven centrifugal pump located on and within the main oil tank. This pump will start automatically, or can be started manually, upon loss of bearing oil pressure. It is used mainly to supply bearing oil and seal oil when the turbine is on turning gear and situations where isolation of the 190# system is necessary. A two-way valve located in the main oil tank will allow the motor driven bearing and Beal oil pump to bypass the lube oil cooler and feed only the seal oil unit when in the tripped position. Oil Coolers During normal operation, proper temperature of oil to the bearing and seal oil system is obtained by means of an oil cooler where the oil temperature is reduced by passing the oil over tubes through which water is circulated. There are two oil coolers and each is capable of cooling full capacity lube oil flow. A two position valve on top of the main oil tank is provided for switching coolers. Oil temperature is regulated from the mechanical console by a con trol valve in the outlet cooling water line. The oil level of the main oil tank should not be permitted to drop below the operating level. On the other hand, it should not be filled to a point where the level will obstruct the oil drain lines. Most turbine oils at a temperature .of 120 F. or less will maintain water in suspension, but at 130 F or above, they will not. Water carried in suspension by the oil circulates through the system may cause corrosion of the ferrous parts. It is therefore advisable to maintain the oil temperature in the tank at or above 13O0 F. Temperature to the bearings should be kept frcm 110 to 120 F. and temperature from the bearings should hold between 140 and l60 F. January, 1974 Page 183 DO 12531.2 CONFTDFNTIAl A motor driven pump along side of the reservoir is piped to the reservoir to flow oil through a filter and through manipulati on of valves this pump is also used to empty the reservoir, if the need arises, to the Bowser storage tank. A centrifuge is alBO piped to the reservoir for removal of water and is alternated on a weekly basis with the filter and return pump. Lube Oil Conditioning & Storage For conditioning the No. 2 turbine lubricating oil, a DeLaval centrifuge type purifier with attached feed and discharge pumps is used. Oil feed system is the same as No. 1 unit. Turning Gear The turning gear and drive motor are mounted in the number three turbine bearing housing. The turbine shaft is driven by an inductlon motor, through a link belt and gear train, at about revolutions per minute. The turning gear must be operated at least one hour prior to starting the unit and immediately after the unit is shut down so that the turbine shaft will not bow due to temperature differentials within the casing. Oil is admitted to the gear from the bearing supply header by a manually operated valve. An oil pressure switch controls the electric circuit to the turning gear motor and prevents operation of the motor in case of insufficient oil pressure. The gear 1b engaged with the turbine rotor by means of a hand lever. This cannot be done, however, unless the driving motor is running. The gear is automatically disengaged as soon as the turbine is relied with steam, however, it is necessary to manually stop the turning gear motor and shut off the oil supply 'he turbine gear. Lubrication is provided by a separate motor driven oil pump which supplies oil from the main oil tank to the turning gear and to the bearings through the main bearing header. The hand valve in the oil supply line from the bearing header must be opened before the turning gear is started and should be closed when the turning gear is not in use. Supervisory Instruments To supply indicttJAn and records on important functions of turbine operation and cbr^rol, the unit is furnished with the following supervisory inst/anents: 1. Shell and rfrferential expansion recorder. 2. Speed andfcamVosition Indicator DO Ip5313 CONFJOFNT TAI January, 1974 Page 184 3* Eccentricity Reorder 4. Vibration Bmpjmtude Recorder Details of openftion of these instruments are contained in the manufacturersx4struetion books. No. 2 Generator This machine 1b practically identical to No. 1 Generator except in physical size and load capability. Connections, Excitation Switchgear, Metering and Generator >Totectioi. These are almost identical to No. 1 Generator. Exciter Field excitation is provided by an indoor type, filtered air cooled exciter motor generator set, 250 KW at 250 volts d-c exciter and 2300 volt, 3 phase, 60 cycle motor. Spare excitation is provided by a unit identical to No. 1 Exciter and is a common spare for both generators. Refer to Procedures Manual for paralleling ex citers. Cooling System Eydrogen is used as the cooling medium for the generator because of the smaller windage loss and because of its higher rate of heat transfer. Also, with hydrogen, less maintenance is required since dirt and moisture are excluded and less deterioration of insulation occurs due to corona. Hydrogen within the sealed generator stator is circulated to all parts of the stator and rotor hy the fans mounted on each end of the rotor. The hydrogen is cooled hy circulation through four generator gas coolers that are mounted vertically at the four corners of the stator frame and using plant cooling water as the coolant. A gas dryer is provided to insure a dry atmosphere in the generator. To prevent leakage through the bearings, the generator shaft is sealed by a floating ring oil seal. Oil is supplied under pres sure to create an oil film between the sealing rings and the shaft to prevent leakage of hydrogen along the shaft. The seal oil supply and scavenging system is described under the lubrica tion system on page 64p of this section. Piping and control equipment are provided bo that carbon dioxide may be admitted into the generator casing prior to filling the generator with hydrogen to prevent formation of an explosive hydrogen-air mixture. The air is first purged by carbon dioxide after which hydrogen Is admitted. January, 1974 r? ^5314 Con^ofNTtai Page 185 The hydrogen instruments and alarms are mounted on the hydrogen control panel. A complete alarm system including reset switches, audible alarms, trouble indicating lights and alarm voltage failure circuits is provided to operate on low pressure, high temperature, low purity, low hydrogen supply and lew Beal oil pressure. Opera tion of the hydrogen panel alarm system also annunciates in the mechanical board in the control room. The generator hydrogen system is completely described in the General Electric Turbine-Generator Manual for Ko. 2 TurbineGenerator . / i January, 1974 DO 1?5315 CONFTDFNTTAl Page 186 <w5-0* pS<o r-'N & ) *" C. NO. 3 TURBINE-GENERATOR AND ACCESSORIES General Hie General Electric Turbine-Generator Unit No. 3 Is a 60,000 KW tandem compound, double flow, condensing, 3600 RPM steam turbine designed for initial steam conditions of 1250 PSIG, 950F,.exhaustIne to 2" HgA with provisions for single automatic extraction/of at 235 PSIG and uncontrolled extractlona*aMfr4099^HHhtivf*dlfiifeB^v The turbine is direct connected to the 75,000 KW, H2 cold, ,14,400 volt, 3600 RPM, 3-phase, two-pole, 60-cycle generator which / Is rated at 96,000 KVA, at 0.85 power factor and 30 PSIG hydrogen pressure. Field excitation is supplied by a static exciter-regulator. The same spare exciter Is utilized for this unit. No. 3 Turbine The turbine exhaust casing and the turbine front end standard are supported on a level sole plate. As expansion takes place, the machine slides forward on these plates from a transverse anchor key located between the center exhaust sole plate and exhaust casing support footing. The turbine casings are split horizontally at the shaft centerline. All joints have metal-to-metal scraped surfaces. Steam admission valves are contained in the upper and lower steam chests located on the outer shell at the front of the high pressure casing. Steam extraction valves are located at the eighth stage. The front standard provides support for the high pressure casings, the number one main bearing ^thrust bearingf The turbine rotors are made from solid, alloy steel forgings solidly bolted together between the high and low elements. The rotor shaft, seals, bearing journals, and coupling flanges are machined from these forgings to form a solid rotor. The outdoor unit is protected against adverse weather conditions by sheet metal lagging provided with weatherproof joints. An enclosure is provided over the turning gear and adjacent machine parts. This enclosure is provided with a door for access to the turning gear controls and to permit observation of the turning gear engaging and running operations. The area between the high pressure casing and front standard is covered with metal lagging as is that area between the generator end and bearing and collector ring housing. Steam Path Same as No. 2 Turbine Shaft Sealing System Same as Turbine No. 1 00 1?5317 cqnftdfnttai December 1973 gm Page 188 Control Mechanism and Governor This governor is made by Triconex in California and is sup Tri-Sen. The TS--3000 governor is a triplicated system. I main processors (computers) and all Input/Output modules a triplicated. Eacfa Input/Output module has 3 legs which ti< to the 3 processors. If a failure occurs on one or two pr< an alarm will sound but the process will not be affected, if one or two legs on a module goes bad, the process will i affected even though the module shows a failure. The programming language is a combination of a basic-like l language and a ladder logic. Programming changes are permi through a personal computer to a user who has access to the Start-Up The turbine start-tip sequence is done automatically and acc the program. The Operator controls the process by pushing buttons as ''start*/ "hold" and "continue". The Metra provi i Operator with the governor interface. If all start permiss i satisfied, the Operator will be allowed to push "start". I warm-up" is selected, the governor will automatically go th i 12 steps of warm-up The Operator can select "manual warm-^ ! chooses. After warm-up, the Operator can roll the turbine J j "continue". The turbine will automatically ramp up to 500 ] i then pause. When the Operator is ready, he can press "cont; | the turbine will automatically ramp up to 3200 rpm. During interval, the turbine will pass through the "critical" speec 3200 rpm, the neutral and field breakers are closed and the is flashed. Afterward, the turbine will ramp up to synchror speed of 3600 rpm, ready to be synchronized. At any time du this start-up sequence, except while going through "critical the turbine can be held an any speed by pressing the "hold" Critical Speed All objects have a natural frequency at which they will vibr an excitation force is applied, similar to a tuning fork whe struck. The critical speed of rotating equipment is when th* frequency (in revolutions per second) is equal to the natural of the shaft, casing, support system or any other component < system. This critical speed can also be affected by blade v; in the case of a turbine or bending of the shaft by dynamic i or a bow. The effects of critical speed are evident in the i equipment by large lateral (sideways) vibration amplitudes wl equipment is rotating at a critical speed. DO 1?5318 CONFTDFNTTAI The tube bundle Is the cooler element with waiter through the tubes. The oil to be cooled flows outside the tubes through the oil tank. Full cooling load at rated temperature or below can be carried with one section out of operation. The oil level of the main oil tank should not be permitted to drop be low the operating level. On the other hand, it should not be filled to a point where the level will obstruct the oil drain lines. Most turbine oils at a temperature of 120F or less will maintaLn water in suspension, but at 130F or above, they will not. Water carried in suspension by the oil circulated through the sytem may cause corrosion of the ferrous parts. It is therefore advisable to maintain the oil temperature in the tank at or above 130F. Temperature to the bearings should be kept from 110 to 120F. and temperature from the bearings should hold between 140 and 160F, A motor driven pump along side of the reservoir is piped to the reser voir to flow oil through a filter and through manipulation of valves this pump is also used to empty the reservoir, if the need arises, to the Bowser storage tank. A centrifuge is also piped to the reservoir for removal of watez^t Lube Oil Conditioning & Storage For conditioning the Mo. 3 Turbine lubricating oil, a DeLaval centri fuge type purifier with attached feed and discharge pumps Is used. Oil feed system is the same as No. 2 unit. Turning Gear The turning gear and drive motor are mounted in the front standard hous ing. The turbine shaft is driven by an induction motoq through a link belt and gear trali^ at about 2 1/2 revolutions per minute. The turning gear must be operated at least one hour prior to starting the unit and lnniedlately after the unit is shut down so that the turbine shaft will not bow due to temperature differentials within the casing. QMoaMpMMAAdmlMiiit* An oil pressure switch controls the electric cir cuit to the turning gear motor and prevents operation of the motor in case of insufficient^olLpressure. The gear is engaged with the turbine rotor by means of a push-button located on the front standard^ This cannot be done, however, unless the driving motor is running. The gear is automatically disengaged as soon as the turbine is rolled with steamy however, it is necessary to manually stop the turning gear motor and shut off the oil supply to the turbine gear. January 1974 page 190 DO 1?5319 CONFIDENT TAI Lubrication is provi plies oil from the m^ ings through the main line from the bearing^ started and should bf a separate motor driven oil pump which supfi. 1 tank to the turning gear and to the bearfaring header. The hand valve in the oil supply ader must be opened before the turning gear is sed when the turning gear is not in use. Supervisory Instrument To supply iwiicatiow and records on important functions of turbine opera tion and control, Jne unit is furnished with the following supervisory instruments: 1. Shell and Differential expansion recorder 2. Speed and Position Indicator 3. Eccentric/rty Recorder 4. Vibratio/ Amplitude Recorder Details of #peratior\of these instruments are contained in the manufac turers instruction broks. No. 3 Generator This machine is practically identical to No. 2 Generator. Exciter Field excitation is provided by the arrangement o the static exciterregulator equipment using AC machine terminal voltage and line current. Spare excitation is obtained through the common spare exciter which is also used for Nos. 1 and. 2 Generator. ^ The metering, automatic and manual controls are located in the main Control Room. ftufcrTU O.G>. Ihiuuul Cooling System - Same as No. 2 Generator January 1974 Page 191 DO 12S370 CONFTDFNTTAl ij c_ p 3CP1 VO o- m vNO> N* 3 GENERATOR OIL DIAGRAM DO 1 2 5 3 P 1 CONFTDFNTTAL D. NO. 4 TURBINE - GENERATOR AND ACCESSORIES General The General Electric Turbine-Generator No. 4 is a sGjOO(MtW rated, 3600 rpm, single-automatic extraction of 475 psig, non-condensing steam turbine, exhausting to ^VMg'back pressure. ^ ^ The Turbine is direct connected to the 85,000 KVA, H2 cooled, 14,400 volt generator. Field excitation is supplied by a static exciter regulator. The motor driven spare exciter is used for this unit also. This Turbine was designed to meet the specific needs of this plant. It provides large quantities of process steam at two controlled pressures and flows. The higher pressure process steam is supplied by extraction at 475 psig and the lower process steam by the exhaust at fhis lower pressure steam is steed-f* dean [lull I id /yg Turbine No. 4 construction and materials are basically the same as the other three units. TURBINE 1. Steam Path Steam from the boiler superheater outlet passes through the main turbine stop valve. In which is located a steam strainer. This valve is hydrauli cally held open and is arranged for quick closing, by spring action, upon i either emergency or hand trip operation. Steam enters the upper and lower turbine steam chests through two steam leads from the stop valve. Steam is admitted to the turbine nozzles by the upper and lower inlet control valves. These valves control the flow of steam to the Turbine. They are opened and closed in proper sequence through action of levers which ride on cams mounted on a camshaft. The camshafts are rotated by the hdyraullc rams through a rack and pinion gear arrangement. During start-up the movement of the controlling valves is under hand control of the control room operator through the load limit mechanism. When operating sphed is reached, the speed governor controls the movement of the inlet valves. From the inlet control valves, the steam is admitted to the first stage diaphram (the diaphrams are the stationery stages of an Impulse type turbine) which re-directs the flow of steam so it impinges on the first stage rotor blades at the proper angle. There is one diaphram (stationary stage) ahead of each rotating stage of the turbine. Steam then passes through four more stages into the fifth stage cavity where the 475 psig extraction valves are located. The steam then passes through six more stages and exhausts to the meader. Leakage of steam along the shaft between stages is minimized by special bronze alloy metallic labyrinth packing placed at the shaft base of the diaphragms and having close clearances between the rotor and packing teeth. The turbine exhaust is protected against excessive back pressure by several relief valves located on the exhaust discharge line. These valves are sized to pass maximum throttle flow. December 1973 Page 193 no 1?S37? CONFTDFNT TA( > r>. > D. No. 4 Turbine - Generator and Accessories (C ntd.) Turbine (Contd.) 2. The gland exhauster system prevents steam from escaping past the outer shaft packing rings to atmosphere at each end-of the turbine shaft. By maintaining a slight vacuum In the outer leakoff chamber, the system continuously removes any leakoff steam. This system Is quite similar to Turbines 1 and 2. The basic system consists of a surface condenser, motor-driven air bl ower^ ^lisdam Manometer connections In the leakoff piping permit measurement of system vacuum. Adjustable regulation dampers (butterfly valves) balance the leakage flow from the glands. ^j-^o 1 ryn Kir I- ^ A blower throttle valve Is used to regulate system vacuum. A water-loop seal on the outlet side of the blower prevents condensate from running back to the blower from the vent piping. The loop seal on the drain side of the blower prevents air from being pulled Into the system. By-pass piping around the condenser to a blowoff tank permits an uninter rupted flow steam leakage from the gland in the event the condenser has to be opened for maintenance. The water-loop seal at the bottom of the condenser acts as a tell-tale to show a clogged drain or broken condenser tube. In either case, the loop will discharge a steady flow of water. The desuperheater Is not h<ronally used during system operation but only when the condenser and/orUHower Is taken out of service. At such times, the desuperheating waterJuray is turned on to cool the steam and air mixture thereby creatin/aLslight vacuum at the glands. For further details of the packing and leak-off system, refer to G.E. Dwg. 2130596. 3. Turbine Control Mechanism and Governor Turbine 4 has essentially the same twouiaj of sections which comprise the control system as Turbines 2 and 3. Th onsist of (1.) the turbine control console located In the main con 1 room which contains the electronic computer section and (2.) igh pressure hydraulic power unit which provides the mechanical fpfcce. No. 4 Turbine Servo System unit Is located at the west end of the Auxiliary Bay under No. 4 Turbine. This self-contained high pressure hydraulic system has two parallel pumping systems, a fluid reservoir, two fluid coolers, and an auxiliary heating system. Either pimping system can be used as the on line pump while the other remains on standby and will come In on low pressure. Hydraulic fluid Is supplied directly from the hydraulic unit to the power actuator assemblies to operate the control valves on the turbine. It should be remembered that this system supplies high pressure hydraulic fluid only and is completely separate .from the turbine lubrication system. December 1973 Page 194 D. Wo. 4 Turbine - Generator and Accessories (Cootd.) Turbine fContd.) 3. Turbine Control Mechanism and Governor (Contd.) The computer Is composed of a number of simple, electrical, solid state circuits which are capable of providing the "intelligence" functions needed to control the position of the turbine control valves. The "muscle" power required to'move the control rams, in correspondence with the computer coranand signals, is provided by the high pressure hydraulic aystew mentioned above. Under normal operating conditions, the speed-load control subsystem compares actual turbine speed,\sensed by the permanent magnet generator (PMG) driven by the turbine rotor, with a speed reference and provides one command signal to the flow control subrsystem. The console is energized from 60 cycle, 115 VAcVhouse" power whenever turbine speed is below 3300 RPM, At speeds abova 3300 ^IPM, the FMG produces a 420-cps signal as well as AC powerVor the computer, BIG frequency signal is converted to DC control vqltag'e by the computer. Hence, changes in turbine speed will show ub al a change in DC voltage level. Speed control is thus effected since Vhe position of the turbine control valves is sensitive to the magnitude of the DC control signals. Turbine 4 is different from Turbines 2` and 3 in that it is a non-condensing unit (therefore it has no low pressure section as do 1, 2 and 3) which exhausts into the main 30# header. Our deaerators are designed so that they must have a steady, stable supply of bteam in order to safely accomplish their functions. If No. 4 turbine cannot supply the required steam to maintain deaerator pressure, the ocher turbines will make up the difference through uncontrolled extraction points or through reducing stations. This will also occur while No. 4 turbine is down or operating at low loads. /\ Once the Board Operator puts this turbine on automatic back-pressure and extraction control, the KW power level output ls\secondary to changes in extraction and back pressure control. In other words, should deaerator or process steam demand decrease,/the computer wobld sense the slight rise in exhaust pressure and thus' call for a reduction in throttle steam through the control valves. Unless there would beSa corresponding increase in 475# extraction demand, KW output would .drop slightly. Turbines 1, 2 and 3 are designed to maintain the required KW output of the generator with extraction and exhaust being secondary. 4. Lubrication System This turbine is provided with a lubrication system which consists of a supply tank, two AC driven Bearing and Seal Oil Pumps, one DC driven Emergency Bearing and Seal Oil Pump, three coolers, strainers, gauges, piping, etc. This system is almost identical to Turbine #3. The main oil tank provides the oil supply and houses most of the ccmpon nts pertinent to the lubrication system. This tank is equipped with high and low level alarms and also a high temperature alarm. As a protection against hydrogen explosion damage, the reservoir is equipped with hinged relief doors. A motor-driven vapor extractor is mounted on the top of the lube oil tank for the purpose.of exhausting water and H2 vapors to December 1973 mo Page 195 Do 1?53?4 CONF 7DFNTTAI, D. No. 4 Turbine - Generator and Accessories (Contd.) Turbine (Contd.) 4. Lubrication System (Contd.) the atmosphere and to provide ventilation for the entire lubrication system. Approximately 1/2" to 1" of water vacuum is maintained in the reservoir. During normal operating conditions, the lubrication and seal oil require ments are taken care of by either of the AC driven pumps. Provisions for automatic startup of the standby AC pump and/or DC pump are made in event of failure of running pump to satisfy the demand or allows oil pressure to drop to a predetermined level. Bearing oil is supplied from the discharge of the pump through a 3-way valve (which can allow flow to the seal oil system only in event turbine is down and bearing oil not required) to the Bearing Oil Pressure Reducing valve. This reducing valve is located in the main oil tank and is set to maintain approximately 25 psig on the bearing oil header. See sketch of Bearing Oil System. Hydrogen seal oil is supplied from the discharge of the pump through the 3-way valve to the seal oil Differential Pressure Regulators. These regulators are located at the Seal Oil unit and are set to maintain approximately 4.5 pounds differential between seal oil and generator hydrogen pressure. (See drawing of Seal Oil System following). 5. Oil Coolers (t The three gravity flow lube oil coolers are finned type and mounted hori zontally in the lube oil tank. The principal parts of the Cooler are the tube bundle, tube sheets, water boxes, distribution baffle, gaskets and hardware. The tube bundle is the cooler element with water flowing through the tubes. The oil to be cooled flows outside the tubes through the oil tank. Full cooling load at rated temperature or below can be carried with one cooler out of operation, dependent of course, on river water temperature and cleanliness of the remaining coolers. The oil level of the main oil tank should not be permitted to drop below the operating level. On the other hand, it should not be filled to a point where the level will obstruct the oil drain lines. Most turbine oils at a temperature of 120F or less will maintain water in suspension, but at 130F or above, they will not. Water carried in suspension, by the oil circulated through the system may cause corrosion of the ferrous parts. It is therefore advisable to maintain the oil temperature In the tank at or above 130F. Temperatore to the bearings should be kept fron 115 to 120F. and temperature from the bearings should hold between 140 to 160F. A motor driven pump along side of the reservoir is piped to the reservoir to flow oil through a filter, and through manipulation of valves this pump is also used to empty the reservoir, if the need arises, to the Bowser storage tank. December 1973 Page 196 ONFTD FNTJat D. No. 4 Turbine - Generator and Accessories (Contd.) Turbine (Contd.) 5. Oil Coolers (Contd.) A centrifuge Is also piped to the reservoir for removal of water and solids and Is alternated on a daily basis with the filter and return pump. No. 4 Turbine oil temperature is regulated from No. 4 Turbine Control Board located in the main control room by a control valve in the outlet cooling water line. This system is identical to No. 3 Turbine. 6. Lube Oil Conditioning and Storage For conditioning No. 4 Turbine lubricating oil, a Delaval centrifuge type purifier and a 50 GPM pump and cartridge type filter are used. Both are located just north of the oil reservoir. (An Instruction manual on the operation and maintenance of the centrifuge is available in the control roan.) The centrifuge is a high-speed sensitive piece of equipment which must be properly cleaned and lubricated. The operating principal involved is that of subjecting a mixture of dirty oil and water to high centrifugal force. This causes the water to separate from the oil because water is heavier than oil. The dirt and sludge are also separated from the oil. High centrifugal force, many times greater than the force of gravity, is accomplished by revolving the "bowl" many thousand revolution per minute. The bowl is so constructed that the purified oil and water each i have a separate discharge. The dirt and sludge remains in the bowl and must be cleaned out at regular Intervals. The height of the lube oil in the centrifuge base should be checked at lease once a day with the oil level stick located on the underside of the oil filler cap. This should be done while the purifier is not running. Remove the oil filler cap, wipe the rod clean and replace. Again remove the cap, this time noting the height of the oil on the gauge. There are two lines on the gauge, the lower one is the danger mark, the the upper one is the full mark. The oil level should be checked in this manner before each starting also. Fill with DELAVAL POWER OIL or alternate. See photographs on following pages for centrifuge and oil manifold piping arrangements. 7. Turning Gear The turning gear and drive mote : Stinted in the front standard housing, The turbine shaft is driven by iction motor through a link belt and gear train at about 2% revolut minute. The turning gear must be operated at least one hour prii r starting the unit and inmediately after the unit is shut down so Sat the turbine shaft will not bow due to temperature differentials v; the casing. An oil pressure switch contr gear motor and prevents op oil pressure to the turb*^ the electric circuit to the turning on of the motor in case of lnsufflcl nt generator bearings. December 1973 g Page 197 DO 125326 OONF TDFNTTAl '^ D. No. 4 Turbine - Generator and Accessories (Contd.) 7. Turning Gear (Contd.) The gear is engaged with t\e turbine yfftor by means of a push-button located on the front standard, ^Thl^^annot be done, however, unless the driving motor is runnlis. The^C is also a "T" handle linkage protruding from the front sund^a lagging for manually engaging the turning gear. The turning should never be engaged (either mechani cally or electrically) untjUnthe rotor has come to a complete stop. The gear is automaticall^^iscngaged as soon as the turbine is rolled with steam, however, it is Secessaw to manually stop the turning gear motor. This system is ident^al to No\ 3 Turbine. NO. 4 GENERATOR Except for size, this generator is practically identical to Nos. 1, 2 and 3. Generator Design Data Sheet follows. H2 Cooling System Hydrogen is used as the cooling medium for the generator because of the smaller windage loss and because of its higher rate of heat transfer. Also, with hydrogen, less maintenance is required since dirt and moisture are excluded and less deterioration of insulation occurs due to corona. Hydrogen within the sealed generator stator is circulated to all parts of the stator and rotor by the fans mounted on each end of the rotor. The hydrogen is cooled by circulation through four generator gas coolers that are mounted vertically at the four corners of the stator frame and using plant cooling water as the coolant. A gas dryer is provided in the event the H2 becomes contaminated with moisture. This system is almost identical to the other turbines. Safety Precautions The importance of frequent checks and a thorough understanding of the Hydrogen system cannot be overemphasized. Under normal operation in hydrogen, the atmosphere in the generator will be non-inflammable. However, a mixture of between 5 and 75 percent hydrogen in air will explode if Ignited in an enclosed space. To ensure complete safety operation of the hydrogen cooled generator, a hydrogen purity between 93 and 95 percent is maintained in the generator casing at all times, thus making an explosion within the casing normally impossible. Causes of low H2 Purity can be found on page of this manual under Section of Gas Purity Alarm. When completely assembled and operated in the proper manner, the generator housing, which forms the hydrogen container, will be a gas-tight, s lf-ventilated enclosure strong enough to limit the destructive effects of an explosion of the hydrogen contents to the generator frame, housing and enclosed parts. The hydrogen equipment of the generator is so arranged that ample ventilation is provided for the parts from which hydrogen leakage to atmosphere might occur. Any abnormal condition should be checked iranediately to determine the cause. If for any reason, you cannot find the problem, be sure to Inform the supervisor and ask his assistance. December 1973 Page 198 DO 1?S3P7 CONFIDFNTIAI D. No. 4 Turbine - Generator and Accessories (Contd.) No. 4 Generator (Contd.) Shaft Sealing System 1. Shaft Seals Hydrogen must be held within the generator casing to be effective. Therefore, shaft seals are required at each end of the generator where the rotor extends through the casing. A radial oil film type seal Is used for the purpose. The shaft seal at each end of the generator consists of a seal housing containing a pair of segmental bronze rings. The sepnents are positioned against the side walls of the housing and are held concentric with the shaft by a garter spring. The rings which have a bore diameter of only a few mils greater than the shaft journal, are free to float radially but are prevented from rotating with the shaft by a stop in the upper half of the housing. This housing Is bolted to the end shield. Oil from the seal-oil control unit at a pressure of 4.5 psl above the hydrogen pressure in the generator Is supplied to the seal housing. The oil then passes radially through the space between the rings and axially along the shaft in both directions. It is this thin film of oil between the shaft surface and the rings that actually seals the hydrogen within the casing. The total oil flow to the Inner or hydrogen side rings of the two shaft seals is less than one gallon per minute, while the flow from the outer or air side rings may be several times that amount. A large air-side flow is needed to cool the rings while a low hydrogen-side flow is essential for satisfactory operation of the continuous scavenging system. 2. Seal Oil Control Unit (Same as #2, 3 and 4) Pressure oil for the seals Is supplied from the main oil system intermediate pressure header to the seal oil control unit where it is filtered and regulated to maintain the 4.5 psl differential. Also the quantity of the total seal flow can be read directly in the flowmeter. 3. Oil Filter The oil filter is a duplex bag type unit which permits either or both sides of the filter to be placed into service. Each filter is sized to continuously handle the full seal-oil requirements. 4. Differential Pressure Regulator A differential pressure regulator is provided for controlling the sealoil pressure at the shaft seal. The valve in the pressure regulator is actuated by a diaphragm. The upper connection to the diaphragm is piped to the seal drain enlarge ment and senses the gas pressure in the generator casing. The lower connection of the diaphragm i* piped to the seal-oil supply lln at the shaft seal and senses oil pressure being supplied to the shaft seals. Once adjusted, the regulator will maintain a constant 4.5 psl differential ) through the complete range of hydrogen differential pressures. December 1973 gm Page 199 DO 1?53?8 CONFIDFNTTAL. <S-" s~\ D. No. 4 Turbine - Generator and Accessories (Contd.) No. 4 Generator (Contd.) 5. Flow Meter The flow meter Is provided for obtaining an Instantaneous reading of the total seal-oil flow. 6. Ins trumentation A differential pressure gauge and two differential pressure switches are mounted on the gauge board. These instruments sense seal-oil pressure at the seals with respect to gas pressure in the casing. The switches are electrically connected to actuate both the DC emergency seal-oil pump located on the oil tank and the annunciator drop in the hydrogen control cabinet on low differential pressure. Valving is provided for adjusting and testing these switches. The seal-oil differential pressure as read on the differential pressure gauge will be the same at the two seals due to the natural hydraulic balance obtained by oversized pressure feed piping to the generator and a balanced piping circuit to each seal. 7. Bearing Drain Enlargement The air side seal-oil and the generator bearing oil drains to a detraining chamber mounted under the generator casing. This detraining chamber, which has been designated as the Bearing Drain Enlargement, provides a large surface area for detraining the oil before it is returned through the loop trap to the main oil tank. The bearing drain enlargement is vented to the roof. In addition to the natural draft in the vent line, an exhauster is also provided to maintain a slight negative pressure in the enlargement. In the event of failure of the shaft seal oil supply, hydrogen will pass from the generator into the bearing drain enlargement and be vented to the roof. The liquid loop trap provides a barrier to prevent the hydrogen from entering the main lubrication oil tank. i 8. Seal Drain Enlargements Two small detraining chambers, known as seal drain enlargements, are provided for removing entrained hydrogen gas from the oil which drains from the hydrogen side seal rings. One of these enlargements is mounted on each end shield and the two are drained through a common line to a float trap. The float trap, which is required to prevent the loss of hydrogen with the drain oil when operating at elevated hydrogen pressures, drains to the bearing drain enlargement where further detraining takes place before the oil returns to the main oil tank. A vertical pipe open at the top terminates in the upper part of each section of the seal drain enlargement. The other end of this line connects to a control valve and flow meter in the hydrogen control cabinet. This arrangement permits a small amount of hydrogen to be continuously discharged to atmosphere from each seal drain enlargement. This discharge of hydrogen causes a small flow of hydrogen past the inner oil deflector of the generat r casing. The flow prevents air liberated from the hydrogen December 1973 00 1?S3p9 c'ONfjoFnttai Page 200 D. No. 4 Turbine - Generator and Accessories (Contd.) No. 4 Generator (Contd.) 8. Seal Drain Enlargements (Contd.) side seal-oil as It passes through the drain chamber of the seal housing from passing Into the generator casing. Since this scavenged hydrogen must be continually replaced with pure hydrogen, the purity of the gas In the generator casing Is maintained at a high value. Another vertical pipe open at the top is also installed In one of the seal drain enlargements to collect the oil which results from an abnormal oil level in the enlargement. This overflow is piped to a high level alarm switch. Since the two enlargements are connected by a common drain line, a high level in either would normally result in the operation of the alarm. Abnormal oil level is usually caused by incorrect operation of the drain valves. FOLLOWING THIS IS A DIAGRAM OF "SHAFT SEAL ADJUSTMENT DIAGRAM" GAS CONTROL SYSTEM The oil supplied to the shaft seals is taken from the turbine.lubrication system and contains an appreciable amount of air in solution, about one percent by volume. The air will be largely given up to the hydrogen as the oil from the seals enters the hydrogen atmosphere. If all of the air liberated from the seal-oil were permitted to pass into the generator casing, a large amount of fresh hydrogen would have to be continuously wasted in order to maintain the hydrogen purity in the casing at a satisfactory value. /tv* However, if most of the air liberated from the seal-oil can be removed before it can pass, by diffusion, into the generator casing through the space between the oil deflector and the shaft, a considerably smaller amount of hydrogen will be required to maintain the hydrogen in the casing at a satisfactory value. The removal of the air is accomplished by continuously scavenging a small quantity of hydrogen and discharging It to atmosphere from the two ends of the seal drain enlargement. The scavenged hydrogen is piped through flowmeters and control valves In the hydrogen control cabinet In order that the rate of scavenging can be controlled. This outward flow of hydrogen from the seal drain lines induces a corresponding outward flow of hydrogen from the generator casing through the radial clearance between the oil deflector and the shaft, thereby reducing to a very small value the Inward diffusion of air from the seal-oil Into the generator casing. Through the operation of this system of continuous scavenging, a hydrogen purity of approximately ninety-seven percent Is maintained in the generator casing, and a purity of about elghty-flve percent Is maintained In the space between the oil deflector and the shaft seal, with the waste of a relatively small amount of hydrogen. CARBON DIOXIDE SYSTEM It is necessary to avoid an undesirable hydrogen-air mixture when initially charging the casing with hydrogen, or after removing the hydrogen from the casing before opening it to atmosphere. An inert gas is used to purge the casing of air before admitting hydrogen, and also to purge the casing of hydrogen before admitting air. D cember 1973 00 1P5330 OONFTOFNTIAI Page 201 D. No. 4 Turbine - Generator and Accessories (Contd.^ Carbon Dioxide System (Contd.) Carbon Dioxide Is usually used for this purpose and is let Into the casing through a perforated distribution pipe extending the length of the Inside of the casing. Coranercial bottles of carbon dioxide are connected to the distribution pipe through a manifold. This manifold assembly Includes a pressure gage, relief diaphragm, and the hand valve which controls the flow of gas to the casing. During the purging operation several bottles, of carbon dioxide are discharged simultaneously into the casing. The generator can also be purged using the portable liquid C02 trailer and vaporizer. When removing either air or hydrogen from the casing, carbon dioxide is admitted to the bottom of the casing through the carbon dioxide feedpipe and the air or hydrogen in the casing is discharged to atmosphere through the hydrogen feed pipe. Carbon dioxide is admitted until a mixture of seventy percent carbon dioxide in air is obtained in the gas discharge to atmosphere. Hydrogen is then admitted to the casing through the hydrogen feed pipe and the carbon dioxide in the casing is discharged to atmosphere through the carbon dioxide feed pipe. When a mixture of ninety-five percent hydrogen in carbon dioxide is obtained in the gas discharged from the casing, the generator may be placed in operation. For removal of hydrogen from the casing with carbon dioxide before opening the casing to atmosphere, carbon dioxide is admitted until a mixture of ninety percent carbon dioxide in hydrogen is obtained In the discharge gas. The carbon dioxide in the casing may then be removed by admitting air to the bottom of the casing and discharging the carbon dioxide to atmosphere through the carbon dioxide feed pipe. The valves in the hydrogen and carbon dioxide feed piping for control of the purging operation are located adjacent to the gas manifolds. PURGING CONTROL GAS ANALYZER A portable gas analyzer is used to supervise the purging operations. The gas analyzer operates on the principle of thermal conductivity, and must be calibrated before each phase of the purging operation. Connections are available from both the carbon dioxide manifold and from the hydrogen mani fold for calibrating the analyzer. The principle of operation of the analyzer is explained in the insert covering the portable gas analyzer. LIQUID DETECTOR Water or oil can collect in the generator casing as the result of a leaky tube in the gas cooler, or from excessive oil flow to the gas side of the shaft seals. A liquid detector is connected in the drain line from the bottczn of the generator casing, and this device is a float actuated switch which operates an alarm at the hydrogen control cabinet. A sight glass permits visual detection of any accumulation of liquid from the generator casing. *J"S1 GAS PURITY ALARM The indicating instrument mounted on the front panel of the hydrogen control cabinet is equipped with an alarm circuit that will operate on either high or low purity. December 1973 Page 202 ^ONFJDFNT TAI. D. Ho. 4 Turbine - Generator and Accessories (Contd.'} Gas Purity Alarm (Contd.) The contacts for this alarm system are set by adjusting the knobs on the front of the indicating instrument. Generator casing Purity Alarm Contacts: The low purity alarm should be set at ninety percent and the high, purity alarm set. at.98 percent. In addition to Indicating the hydrogen purity in the respective areas, the low purity alar* may indicate (a) loss of Ac supply to the cabinet; (b) failure of the thermal cells in the detector unit; ' (c) moisture in the detector unit cells; (d) failure of the vacuum tube in the alarm amplifying relay. If the source of the alarm is the generator casing, observe reading of the fan-pressure gage. If this also Indicates low hydrogen purity, admit hydrogen to the generator casing from the connected bottles to restore the purity to a satisfactory value. Then determine the cause of the decrease in purity and correct (low purity is usually an indication that the scavenging rate is too low). If the seal housing is indicated as the source of the alarm, the scavenging rate should be Increased until a satisfactory purity is obtained. Failure (a) would be denoted by extinguishing of AC pilot lamp. Failure (b) would be indicated by an appreciable reduction in the readings of the milllameter. The high purity alarm may indicate (a) Incorrect calibration; (b) failure of one coll of the thermal cell in detector unit: or (c) too high a current through the thermal cell. Condition (a) may be checked by passing pure hydrogen through the detector unit by way of the calibration valve. .Failure (b) would be Indicated by an appreciable reduction in the reading of the mllliameter. Condition (c) would denote adjustment of rheostat. FLOW CONTROL AND SCAVENGING RATE The rate of hydrogen flow through the gas analyzer cell should be maintained between 100 cc and 700 cc per minute for satisfactory operation. In general a flow of 400 to 700 cc per minute should be maintained when operating with hydrogen pressure In the generator casing below 15 pslg and 200 to 400 cc per minute when operating with hydrogen pressure in the generator above 15 pslg. Higher flow rates Induce flow error in the purity readings obtained and may increase maintenance of the cell by introducing foreign matter into the cell block. The gas analyzer is Independent of flow error over a vide range. However, if flow is increased beyond a certain amount the reading will change indicating an apparent Increase in hydrogen purity. The gas analyzer may be checked f r flow error by decreasing or shutting off the flow for a short time. Any change in the reading will be flow error. The required flow is obtained during operation of the generator from the differential pressure across the generator fan. The flow rate is controlled by adjustment of the needle valve and needle by-pass valve. With the generator at standstill, the flow of hydrogen from the generator casing t the analyzer unit is btaln d by allowing hydrogen from the flowmeter to December 1973 Do 1?533? ^onftdfnttai Page 203 Ho. 4 Turbine - Generator and Accessories (Contd.) Flow Control and Scavenging Rate (Contd.) be discharged to atmosphere through the vent piping. Since under this condition of operation the hydrogen Is wasted, It Is desirable to reduce the flow to a minimum value for which satisfactory operation of the analyzer can be obtained. This value Is between 100 cc and 200 cc. The filter dryer unit Is filled with approximately four ounces of activated alumina. A light blue Is the normal color of the drying agent which turns to light pink and then to white when expended. The expended drying agent can be replaced. December 1973 gm Page 204 CQNFTOFNttAI r> i' 0 s n I ft tu*o>J DO 1 ? 5 3 3 4 CO NFIDENT TAl *f0t <8 to woi N A GENERATOR OIL DIAGRAM