Document evgNBR1145J2jyQbLZw4gdk74

CANADIAN HYDRO PROJECTS continued both plant* the spaed ring* are aeeurcly anchored to the reinforcing in the con* crete forming (he scroll cases and sub* structures. The higher turbine settings of the francis units above tallwater level kept scroll-ease pressures low enough to permit forming the water passages and scroll cases directly in the concrete. Studies indicated the lower setting re* quired for propeller turbines would have increased scroll-case pressure to where steel-plate penstocks .snd scroll oases would be required with their added cost. For these reasons, francis turbines with concrete scroll cases and water passages gave the most economi cal design. Scroll-case pressures at Des Joachims made it desirable to use steel-plate scroll cases, triple*rlveted to cast-steel speed rings. Clreutnferentlal joint be tween plates of the easing! are held* welded, and longitudinal joints are shopwelded or field-riveted. Scroll cases are designed for 165-ft head, which includes an allowance for pressure rise. Pen stocks ere steel plate, 22 ft in diameter with welded longitudes! seams and riveted circumferential joints. Turbine Runner*. At all three plants, turbine runners are east steel, double heat-treated to insure proper grain re finement throughout. Shafts are forged to meet special requirements as to re* duction in forging end heat treatment. Exposed parts of each shaft are ma chined and polished to a finish of about 63 microinches. The guide bearing journals are machined and polished to a finish of 16 mleroinehes or less. Turbina Bearings. There has been s recent trend toward oil-lubricated bab bitt bearings for hydraulic turbines. Earlier turbines were generally installed in open flumes and the bearings were of necessity water lubricated. Lignum* vitae blocks, generally used, became standard equipment even on modem vertical-shaft units with relnforccd-concrete or steel-plate spiral scroll cases with a head cover. Turbine bearing is close to the head cover and might be flooded If water pressure develops above crown of runner. Weter*lubriceted bear ings made it unnecessary to worry about water getting into the oil. A* turbine and generator sixes in creased It became difficult to keep fignum-viiae bearings adjusted to insure turbine and generator parts running true. Therefore it was desirable to use oil-lubricated bearings that could be adjusted to close lojeroncea. Sealing arrangements to prevent water leaking into these bearings have Iteen developed so oil-lubrlcsied guide bearings are to day accepted as a necessary part of hydroulic turbine equipment. Oil Lubrication, ft is Interesting to seo Storing block___ CrcttfOi! omtfa " V. -. j 4v - - * pMSW Oil meHen from lump i&M " i SAoft rototion Vlteoeity-pump groove font of tie) 5 Segment pi turbine's guide bearing shows viscosity-oil pump, oil riser and ae How pipe at Dei ioochims, Chsnoux, and on units No. 5 lo 8 at lo Pflndpal Faluia, Dimensions, WeljMs ol Ttutfiies, Genentors Installed it La Cava, Oes Joashltns and Chenata Torbiae Fotrsi Manufacturer............. Dcslcn bead, ft.......................................... Capacity, hp.............................................. Speed, rpa................................................. Specific apead, Na..................................... Rated diacharfi, el*.................................. Rmaw dtarhargt dU, ft.......................... Oiitda-viaa drda dla, ft........................... aaida-vana hetsht. ft............................... Runner vanes, cumber............................. QukJe vanca, number................................ Stay vanca, number.................................. Shaft diameter, la..................................... Water Usnm ai runner, tb...................... Welfhl rotatma porta, lb......................... Wd*ht of turbtoa rtjuipenent, one uait, I flrreO ease.................................................. Otnerolor Footuros blanafaeTurer............................................. Capacity, kva.. IVcr factor.. Vottacc. bv......................... fetter dlunettr, la............. Alr-cwlnc* tachin equart.. Alr-cnlnt. hdsHt. bt........ Rotor weight, lb............... Oraerator weight, lb,.. .. Machine total weight, lb . . Canadian Dominion Don AJIb-Chalunrv John IngUe Buglutulng ffmtmrrhi Xrancto FVaneta PMnete rin 100.000 1U.000 mooo 110.000 141.000 150.000 170.000 140.000 111.000 370,000 sas.ooo UT1.000 sr^os OSS 131 JIOJ 370.000 01.000 1.311,000 110.000 1,100,000 I.SII.0Q0 3SMP itifa liow this trend toward oil-lubricated guide bearing has taken place on hy draulic turbines installed by the JfydroElectrie Power Commission of Ontario. During the 35 years before 1948 the Commission built 18 hydroelectric plants with S3 vertical shaft units of shout 1,300,000-hp total capacity. Only two of these hed babbitt bearings and they were installed about 25 years ego. All other turbines, put into operation, hive water-lubricated lignum-riloe bearinpj| Since that time 34 vertical-shaft uotall have been installed, including La CswJj totaling about 1,200,000 lip in soJj plants. 0/ these only six units of I**;'] 000-bp total capacity have waier-luh cated lignum-vitae bearings. The otfcd 28 have oil-lubricated babbitt beariflpl| Owlde-Beoring Designs. These turblMl guide bearings ore preciiloo-bored, bH biti-lloed, oil-lubricated, but two di^j Star**' ttpotofor HO" udicotor mi W sto"****v*9" '^Cftos! iUfplf piping vQlrt ^WOfer-to&'r P'Pi'V from taoif ecu ,part of pit linir OH tump,, -D//-/PVP/ imfieotor end le*'livoiotarm ^Mtodcovtf Purler tiotogt voter underpressure Turbine hoM, La Cove unlit 1*4 have babbitted and llgnum-vitoe sealing surfaces combined with onnular grooves ftunntr leokoge meter uderpressure 7 Oes Joochimi turbines gulde-beoring-ond-lhoft woter seal uses flax pocking. At Chenaux. carbon rings oct at seals types ore used. Des Joochims design it tfiniUr lo that st Chenaux, and on ;*: oolu No. 5 to 8 at La Cave. For La Cave ' 'naiti No. 1 to 4, Fig. 1 shows the genvnl irrangement of the guide bearings ' sod oil pumps .An annular oil sump below the benr- t-(ng, currnunds the turbine shaft. A ^specially designed oil sllnger connects jj'to the shaft with a shoe-type viscosity- 'oil poop rubbing against the slinger. ;Thls pump is mounted lo the oil sump l; so it.-ii always below minimum oil level. ^Ojl discharges from the pump to a Timstl reservoir above the bearing. Leavfog this reservoir, oil goes to an annular V-dUiributlng well formed in the lop of 'be*ring block. -.'Oil, flowing by gravity down through jj/tfce bearing, is carried to til peris of It .by i netwoik of vertical and horisonta) * Cloves. Fig, 2 end 3 show details of ' fbe oil slinger snd viscosity pump, while Fig. 4 gives the oil grooves in the guide bearing. Oil, discharging from the hot- loo,end of the bearing, posses down b-_ **r Nt D slinger and goes lo the sump. An automatic molor-driven rotary pump ^ *Ppho* oil ta the.bearlng when start- I mg the unit, or as standby should the ^vlscchy pump fall, l Boaring Designs. Units No. 5 V* 8 it La Cate and ail units In Chen* IB* Dm Joachims hove different guMe-bearing srrangemenu. Machined >, , around iho bearing below- lihum oil level in the tump, a series M `pedal grooves acting at vitcoa* ity pumps supply oil to the Des Joach* ims guide bearings, Fig. 5 and 7. Oil enters the viscosity pump grooves at the deep end by holes A drilled through the bearing block. Eaeh pump groove leads to a specially shaped vertical one lhat acts as a riser to distribute oil to the bearing surface. Excess oil dis charges to top of bearing block through a hole B in lop of each riser and returns to the sump. Cooling coils in the sumps keep oil viscosity st a correct valuo snd prevent overheating. On Units No. 5 to 8 at Lo Cave, bearing blocks ire cored to form internal coolant passages, so cooling cnila oro not required in the sump. Water circulates under pressure through the coils and passages. Units No. 1 to 4 st La Cave do not have a cooling coil in the oil sumps. Water Sool*. Below the guide bearing of each unit a water seal or stuffing box prevents oil loss lo the tailroce or mixing ol leakage water trom above the runner with oil in the bearing. The seal has annual grooves that drain sway any water that may rise through the clear ances between the turbine shah and the * reuse* or water*Iubricoted sealing sur* faces. At La Cove, units No. 1 to 4 have babbitted and lignum.vitoe sealing sur faces, Fig. I and 6. Sealing surfaces at Des Joachims are flax packing, Fig. 7. Carbon rings are used for seating at Chenaux ond for unit No. 5 to 8 at Lo Cave. All turbine bearings other than that on the main shaft have high-pressure grease fittings, lubricated from s port able grease compressor. Oeneralors. At Des Joachims end Chenaux, rated generator capacity con forms to turbine capacity at rated head. Lo Cava operates at a head about 6% above the normal on which turbine rat ing is based during the season of large water storage. For this reason genera* tor ratings were based on turbine out put at maximum head. At all three plants the generators are totally enelosed, ventilating air being circulated through air* to water-heat ex changers, mounted whhin the enclosing housing. The housings are square end hero dampers so pan of the air may be circulated in the powerhouse for winter healing. Totally enclosed units were selected to (1) reduce cost of cleaning machine windings (2) reduce noise (3) have e cooler powerhouse in summer. At Chenaux each generator sets in the substructure so only part of the bridgo upper brocket and the exciter extends above the main floor. Stator is in e squore recess in the foundation with cover plotes at the main floor to complete the enclosure. Des Joachims and Ls Cove generator casings are above (he moln floor. Decause of the francia-tuTbina settings and deeper Mo tor frames, the limit to which the letter could be depressed would still have left a large port of the air casing exposed. Sprinkler rings are Installed la all (Continued on page 204) fNOINEtBlNO AND MANAGEMENT SECTION ro*0J I jttlUAtt \9S3 ENOINEESINO AND MANAGEMENT SECTION \