1. FUNDAMENTAL OF MAIN TURBINE
( 500 MW KWU,GERMANY DESIGN )
MANUFACTURED AT BHEL,HARIDWAR
MECHANICAL MAINTENANCE
DEPARTMENT
TURBINE MAINTENANCE

2. TURBINE SYSTEM
HPT
IP
T
LPT
GENERATOR
EXCITER
1 2 3 4 5 6 7
THREE STAGE TURBINE :
• HIGH PRESSURE TURBINE (HPT)
• INTERMEDIATE PRESSURE TURBINE (IPT)
• LOW PRESSURE TURBINE (LPT)
SEVEN NOS JOURNAL BEARINGS
BEARING N0. 2 THRUST CUM JOURNAL
BEARING
FOUR NOS RIGID COUPLINGS BETWEEN
• HP-IP TURBINE
• IP-LP TURBINE
• LP-GENERATOR
•GENERATOR - EXCITER
CONDENSER

3. HIGH PRESSURE TURBINE
 SINGLE STEAM FLOW OF TWO SHELL (CASING) DESIGN
 OUTER CASING IS OF BARREL TYPE AND HAS NEITHER ON AXIAL OR RADIAL
FLANGE. DUE TO THE PERFECT SYMMETRIC DESIGN OF THE OUTER CASING AND
UNIFORM WALL THICKNESS AT ALL SECTIONS, PREVENTS MASS
CONCENTRATIONS WHICH WOULD CAUSED HIHG THERMAL STRESSES AND
REMAINS LEAK PROOF DURING QUICK CHANGES IN TEMPERATURE DURING START
UP AND SHUT DOWN.
 THE INNER CASING IS AXIALLY SPLIT IS ALMOST CYLINDRICAL IN SHAPE AS THE
JOINTS FLANGES ARE RELIEVED BY HIGHER PRESSURE ACTING FROM THE OUT
SIDE.
 CASING IS MADE OF CREEP RESISTING CHROMIUM-MOLYBDENUM-VANADUIUM
(Cr-Mo-V) STEEL CASTING.
 THE TURBINE HAS 2 MAIN STOP VALVES (ESV) AND 2 CONTROL VALVES
(CV)LOCATED SYMMETRICALLY TO THE RIGHT AND LEFT OF THE CASING. THE
VALVES ARE ARRANGED IN PAIRS WITH ONE STOP VALVE AND ONE CONTROL
VALVE IN A COMMON BODY. EACH ESV AND CV HAS A DEDICATED HYDRAULIC
SERVOMOTOR.
 THE STEAM LINES FROM ESV & CV ARE CONNECTED TO THE INLET
CONNECTIONS OF THE OUTER CASING BY BREECH NUTS.

4. INTERMEDIATE PRESSURE (IP)
TURBINE
• THE IP TURBINE IS OF DOUBLE FLOW CONSTRUCTION WITH TWO NOS
HORIZONTALLY SPLIT CASINGS ( INNER & OUTER CASING).
• THE HOT REHEATED (HRH) STEAM INTERS THE INNER CASING AT THE MID
SECTION FROM TOP AND BOTTOM AND EXPENDS IN OPPOSITE SIDE IN TWO
BLADE SECTIONS AND COMPENSATE AXIAL THRUST.
• THE INNER CASING CARRIES THE STATIONARY BLADING.
• THE IP STOP AND CONTROL VALVES 2 NOS ARE SUPPORTED ON THE
FOUNDATION COVER PLATE BELOW EL 17.00 M FLOOR IN FRONT OF TURBINE
–GEN UNIT.
• CASING IS MADE OF CREEP RESISTING CHROMIUM-MOLYBDENUM-
VANADUIUM (Cr-Mo-V) STEEL CASTING.
• THE SHAFT IS MADE OF HIGH CREEP RESISTANCE Cr-Mo-V STEEL FORGING.

5. LOW PRESSURE (LP) TURBINE
• LP TURBINE CASING CONSISTS OF DOUBLE FLOW UNIT AND HAS A TRIPLE
SHELL WELDED CASING.
• THE OUTER CASING CONSISTS OF FRONT AND REAR WALLS, TWO
LATERAL LONGITUDINAL SUPPORT BEAMS AND THE UPPER DOME AND
CONNECTED TO CONDENSER BY WELDING.
• THE INNER-INNER & INNER-OUTER CASING CARRIES THE TURBINE GUIDE
BLADES AND DIFFUSER.
• STEAM ADMITTED TO THE LP TURBINE INNER CASING FROM IP TURBINE
FROM BOTH LEFT AND RIGHT SIDE HORIZONTALLY. EXPANSION JOINTS
ARE INSTALLED IN THE STEAM PIPING TO PREVENT ANY UNDESIRABLE
DEFORMATION OF THE CASINGS DUE TO THERMAL EXPANSION OF THE
STEAM PIPING.

6. TURBINE BLADING
HP TURBINE MOVING AND STATIONARY BLADES :
• HP TURBINE BLADING CONSISTS OF 17 REACTION STAGES WITH 50 %
REACTION.
• BLADES ARE HAVING THREE MAIN PARTS :
1. AEROFOIL : IT IS THE WORKING PART OF THE BLADE WHERE STEAM
EXPANSION TAKES PLACE.
2. ROOT : TI IS THE PORTION OF THE BLADE WHICH IS HELD WITH ROTOR
OR CASING
3. SHROUDS : END PORTION OF BLADES ARE HELD TOGETHER
• THE STATIONARY AND MOVING BLADES OF ALL STAGES ARE
PROVIDED WITH INVERTED T-ROOTS. ALL THESE BLADES ARE
PROVIDED WITH INTEGRAL SHROUDS WHICH AFTER INSTALLATION
FORM A CONTINUOUS SHROUD.
• THE MOVING AND STATIONARY BLADES ARE INSERTED INTO THE
CORRESPONDING GROOVES IN THE SHAFT AND INNER CASING. THE
INSERTION SLOT IN THE SHAFT IS CLOSED BY A LOCKING BLADE
WHICH IS FIXED BY GRUB SCREWS.
• SEALING STRIPS ARE CAULKED INTO THE INNER CASING AND THE
SHAFT TO REDUCE LEAKAGES LOSSES AT THE BLADE TIPS.

7. TURBINE BLADING
IP TURBINE MOVING AND STATIONARY BLADES :
• IP TURBINE BLADING CONSISTS OF 12 REACTION STAGES PER FLOW WITH 50 %
REACTION.
• THE STATIONARY AND MOVING BLADES OF ALL STAGES ARE PROVIDED WITH
INVERTED T-ROOTS. ALL THESE BLADES ARE PROVIDED WITH INTEGRAL
SHROUDS WHICH AFTER INSTALLATION FORM A CONTINUOUS SHROUD.
• THE MOVING AND STATIONARY BLADES ARE INSERTED INTO THE
CORRESPONDING GROOVES IN THE SHAFT AND INNER CASING. THE INSERTION
SLOT IN THE SHAFT IS CLOSED BY A LOCKING BLADE WHICH IS FIXED BY GRUB
SCREWS.
• SEALING STRIPS ARE CAULKED INTO THE INNER CASING AND THE SHAFT TO
REDUCE LEAKAGES LOSSES AT THE BLADE TIPS.

8. TURBINE BLADING
LP TURBINE MOVING AND STATIONARY BLADES (FIRST 3
STAGES) :
• LP TURBINE BLADING CONSISTS OF 12 REACTION STAGES PER FLOW
WITH 50 % REACTION.
• THE STATIONARY AND MOVING BLADES OF FIRST THREE STAGES ARE
PROVIDED WITH INVERTED T-ROOTS. ALL THESE BLADES ARE PROVIDED
WITH INTEGRAL SHROUDS WHICH AFTER INSTALLATION FORM A
CONTINUOUS SHROUD. FIRST THREE GUIDE BLADES ARE MOUNTED ON
INNER-INNER CASING.
• THE MOVING AND STATIONARY BLADES ARE INSERTED INTO THE
CORRESPONDING GROOVES IN THE SHAFT AND INNER CASING. THE
INSERTION SLOT IN THE SHAFT IS CLOSED BY A LOCKING BLADE WHICH
IS FIXED BY GRUB SCREWS.
• SEALING STRIPS ARE CAULKED INTO THE INNER CASING AND THE
SHAFT TO REDUCE LEAKAGES LOSSES AT THE BLADE TIPS.

9. TURBINE BLADING
LP TURBINE MOVING AND STATIONARY BLADES (LAST 3
STAGES) :
• LAST THREE STAGES OF LP TURBINE ARE ALSO REACTION STAGES. EACH
STAGE IS MADE OF GUIDE AND MOVING BLADES.
• THE LAST STATIONARY BLADES ARE MADE BY WELDING INNER RING,
BLADES AND OUTER RING TOGETHER TO FORM GUIDE BLADE CARRIERS IN
TWO HALVES AND ARE BOLTED TO INNER-OUTER CASING. THE
STATIONARY BLADES OF 4TH
AND 5TH
STAGES ARE MADE OF CAST STEELS
AND 6TH
STAGE STATIONARY BLADE ARE MADE FROM STEEL SHEETS TO
FORM HOLLOW BLADED. SUCTION SLIT ARE PROVIDED IN 6TH
STAGE
BLADES. THROUGH THESE SLITS WATER PARTICLE ON THE SURFACE OF
THESE LAST STAGE GUIDE BLADES ARE DRAWN AWAY TO THE
CONDENSER.
• THE 4TH
STAGE MOVING BLADE IS OF TAPERED TWISTED BLADES HAVING
INTEGRAL SHROUDS WITH T-ROOT. THE LAST TWO STAGE MOVING BLADES
ARE OF TWISTED DROP FORGED BANANA TYPE CONSTRUCTION HAVOING
CURVED FIR-TREE ROOTS WHICH ARE INSERTED IN AXIAL GROOVES IN
THE TURBINE SHAFT AND SECURED BY MEANS OF CLAMPING PIECES. LAST
TWO STAGE MOVING BLADES ARE NOT HAVING ANY SHROUDS.

10. TURBINE SHAFT SEALS
HP TURBINE SHAFT SEALS :
• HP TURBINE HAS SHAFT SEALS IN FRONT AND REAR. FRONT
SHAFT SEAL IS OF LABYRINTH TYPE WHILE REAR SHAFT SEAL
IS SEE THROUGH TYPE.
• THE FUNCTION OF THESE SHAFT SEALS IS TO SEAL THE
INTERIOR OF THE CASING FROM ATMOSPHERE AT THE END
OF THE SHAFT ON THE ADMISSION AND EXHAUST SIDES.
• THE SEALING BETWEEN THE ROTATING AND STATIONARY
PARTS OF THE TURBINE IS ACHIEVED BY MEANS OF SEAL
STRIPS CAULKED INTO SEAL RINGS OF THE CASING AND INTO
THE ROTOR.
• THE PRESSURE GRADIENT ACROSS THE SEALS IS REDUCED
BY CONVERSION OF PRESSURE ENERGY INTO VELOCITY
ENERGY WHICH IS THEN DISSIPATED AS TURBULENCE AS
STEAM PASSES THROUGH NUMEROUS COMPARTMENTS
ACCORDING TO THE LABYRINTH PRINCIPLE.

11. TURBINE SHAFT SEALS
IP TURBINE SHAFT SEALS :
•IP TURBINE HAS SHAFT SEALS IN FRONT AND REAR. FRONT SHAFT SEAL IS
OF LABYRINTH TYPE DUE TO LOW RELATIVE EXPANSION WHILE REAR
SHAFT SEAL IS SEE THROUGH TYPE DUE TO GREATER RELATIVE
EXPANSION.
•THE FUNCTION OF THESE SHAFT SEALS IS TO SEAL THE INTERIOR OF THE
CASING FROM ATMOSPHERE AT THE END OF THE SHAFT ON THE
ADMISSION AND EXHAUST SIDES.
•IN THE FRONT, SEAL STRIPS ARE CAULKED ALTERNATIVEY INTO THE
SHAFT AND INTO THE SPRING SUPPORTED SEGMENTED RINGS IN THE
CASING FORMING A LABYRINTH.
•IN THE REAR SEE THROUGH SEALS ARE USED IN WHICH SEAL STRIPS ARE
LOCATED OPPOSITE TO EACH EATHER CAULKED INTO THE SHAFT AND INTO
SEAL RINGS CENTERED IN THE OUTER CASING
LP TURBINE SHAFT SEALS :
•LP TURBINE HAS SHAFT SEALS IN FRONT AND REAR ARRANGED BETWEEN
BEARING PEDESTAL AND THE LP TURBINE. BOTH FRONT & REAR SHAFT
SEAL IS SEE THROUGH TYPE DUE TO GREATER RELATIVE EXPANSION.

12. TURBINE BEARING
• HP ROTOR IS SUPPORTED ON TWO JOURNAL BEARINGS. JOURNAL BEARING AT
THE FRONT AND COMBINED JOURNAL & THRUST BEARING AT THE REAR.
• IP AND LP ROTORS ARE HAVING JOURNAL BEARINGS EACH AT REAR END.
• GENERATOR ROTOR IS SUPPORTED ON TWO JOURNAL BEARINGS AT EACH END.
•EXCITER HAVING A JOURNAL BEARING AT REAR END.
• JOURNAL BEARINGS ARE MANUFACTURED IN TWO HALVES AND USUALLY
CONSISTS BEARING BODY FACED WITH ANTI FRICTION TIN BASED BABBIT
MATERIAL TO DECREASE THE COEFFICUIENT OF FRICTION.
• ALL THESE BEARINGS ARE LUBRICATED WITH FORCED LUBRICATION WITH
SERVOPRIME –46 OIL AND HAVE A PROVISION OF FOR ADMISSION OF JACKING OIL

13. TURBINE BARRING GEAR
• PRIMARY FUNCTION OF THE BARRING GEAR IS TO ROTATE THE TURBO-
GENERATOR ROTOR SLOWLY AND CONTINUOUSLY AT 75-80 RPM DURING START UP
AND SHUT DOWN WHEN CHANGES IN ROTOR TEMPERATURE OCCUR.
• WHEN TURBINE IS SHUT DOWN, COOLING OF ROTOR ELEMENTS ARE TAKES PLACE
AT SLOW SPEED TO AVOID DISTORTION OF ROTOR. BARRING GEAR IS USED TO KEEP
THE ROTOR REVOLVING UNTIL THE TEMPERATURE CHANGES HAS STOPPED AND
ROTOR HAS BECOME COOL.
• DURING STARTING TURBO-GENERATOR ROTOR IS SLOWLY ROTATED TO HAVE A
UNIFORM HEATING OF ROTOR.
• BARRING GEAR IS A HYDRAULIC OPERATED (LUB OIL) TURBINE MOUNTED ON THE
SHAFT LOCATED IN THE FRONT BEARING PEDESTAL.
• HAND BARRING GEAR ALSO PROVIDED IN BEARING PEDESTAL NO.3 TO ROTATE THE
SHAFT BY HAND DURING EMERGENCY WHEN HYDRAULIC OPERATED BARRING GEAR
IS NOT AVAILABLE.

14. TURBINE FIXED POINTS
DESIGN OF SUPPORTS FOR THE TURBINE ON THE FOUNDATION HAS TO ALLOW
FOR THE EXPANSION OF THE TURBINE DURING THERMAL CYCLING.
THE FOLLOWING COMPONENTS ARE THE FIXED POINTS FOR THE TURBINE :
• THE HP, IP, LP TURBINE BEARING PEDESTALS
• THE FRONT HORN SUPPORT OF HP AND IP TURBINE CASING.
•THE LONGITUDINAL BEAMS OF THE LP TURBINE.
• ROTOR AT THRUST BEARING IN BEARING PEDESTAL NO. 3

15. BEARING PEDESTALS
FRONT BEARING PEDESTAL :
THE FRONT BEARING PEDESTAL IS LOCATED AT THE TURBINE SIDE END OF
THE TURBOGENERATOR UNIT. ITS FUNCTION IS TO GIVE SUPPORT HP
TURBINE CASING AND BEAR THE TURBINE ROTOR. IT HOUSES THE
FOLLOWING COMPONENTS:
• JOURNAL BEARING NO.1
• HYDRAULIC BARRING GEAR
• MAIN OIL PUMP WITH HYDRAULIC SPEED TRANSDUCER
• ELECTRICAL SPEED TRANSDUCER
• OVER SPEED TRIP DEVICE
• SHAFT AND BEARING VIBRATION PICK UP.
HP-IP BEARING PEDESTAL :
THE BEARING PEDESTAL IS LOCATED BETWEEN HP AND IP TURBINE. ITS
FUNCTION IS TO SUPPORT THE HP AND IP TURBINE CASING AND BEAR THE
HP & IP ROTOR. IT HOUSES THE FOLLOWING COMPONENTS :
• COMBINED JOURNAL AND THRUST BEARING NO.2
• SHAFT AND BEARING VIBRATION PICK UP
• THRUST BEARING SHIFT PROBES.

16. BEARING PEDESTALS
IP-LP BEARING PEDESTAL :
THE BEARING PEDESTAL IS LOCATED BETWEEN IP AND LP TURBINE. ITS
FUNCTION IS TO SUPPORT THE IP AND LP TURBINE CASING AND BEAR THE
IP & LP ROTOR. IT HOUSES THE FOLLOWING COMPONENTS :
• JOURNAL BEARING NO.3
• SHAFT AND BEARING VIBRATION PICK UP
• HAND BARRING GEAR.
LP-GEN BEARING PEDESTAL :
THE BEARING PEDESTAL IS LOCATED BETWEEN LP AND GENERATOR. ITS
FUNCTION IS TO SUPPORT THE LP TURBINE CASING AND BEAR THE LP
ROTOR. IT HOUSES THE FOLLOWING COMPONENTS :
• JOURNAL BEARING NO.4
• SHAFT AND BEARING VIBRATION PICK UP

17. CONDENSER
CONDENSER IS A SURFACE TYPE CONDENSER WITH TWO PASS ARRANGEMENT.
COOLING WATER IS PUMPED INTO EACH OF CONDENSER PASS BY VERTICAL CW
PUMPS THROUGH THE INLET PIPE. WATER ENTERS THE INLET CHAMBER OF
FRONT WATER BOX AT THE BOTTOM PASSES HORIZONTALLY THROUGH THE
TITANIUM TUBES TO THE WATER BOX AT THE OTHER END, TAKES A TURN PASSES
THROUGH THE UPPER CLUSTER OF THE TUBES AND REACHES THE OUT LET
CHAMBER AT THE TOP IN THE FRONT WATER BOX AND LEAVES THE CONDENSER
THROUGH OUTLET PIPE.
STEAM EXHAUSTED FROM THE LP TURBINE WASHING THE OUTSIDE OF
THE CONDENSER TUBES LOSSES ITS LATENT HEAT TO THE COOLING WATER AND
CONVERTED INTO WATER IN THE STEAM SIDE OF THE CONDENSER. THIS
CONDENSATE COLLECTS IN THE HOT WELL, WELDED TO THE BOTTOM OF THE
CONDENSER.
CONDENSER DESIGN DATA :
• COOLING WATER FLOW : 54300 M3/Hr.
• COOLING WATER SURFACE AREA : 35603 M2
• NO. OF COOLING TUBES : 24398 NOS ( CONDENSING ZONE:22688 NOS AND AIR
COOLING ZONE :1710 NOS)
•TUBE MATERIAL : TITANIUM SB-338 GRADE-II
• MAIN TUBE PLATE : MS WITH TITANIUM CLADED.
• WATER BOX : MS WITH FRE LINING ( GLASS FIBRE REINFORCED EPOXY LINING)