1. OBJECTIVES
1. DESCRIBE the process for converting heat energy to rotational energy in turbines.
2. DESCRIBE the components that comprise a turbine.
3. DESCRIBE reaction and impulse turbine blading.
4. DESCRIBE the function of a nozzle in turbine blading.
5. EXPLAIN the concept of turbine staging.
6. DEFINE turbine efficiency.
7. DESCRIBE the steam flow path through a turbine.
8. DESCRIBE accessories and support systems associated with turbines.
9. DESCRIBE failure mechanisms and symptoms associated with turbines.
ABC / Mechanical Science / Chapter 10 / TP / Rev 02

2. WORK IN A TURBINE VISUALIZED
Fig 10-1
ABC / Mechanical Science / Chapter 10 / TP / Rev 02

3. IMPULSE TURBINE PRINCIPLE
NOZZLE
STEAM CHEST
ROTOR
Fig 10-3
ABC / Mechanical Science / Chapter 10 / TP / Rev 02

4. PRESSURE-VELOCITY DIAGRAM FOR A TURBINE NOZZLE
ENTRANCE
HIGH THERMAL ENERGY
HIGH PRESSURE
LOW VELOCITY
STEAM INLET
EXIT
LOW THERMAL ENERGY
LOW PRESSURE
HIGH VELOCITY
STEAM EXHAUST
PRESSURE
VELOCITY
Fig 10-4
ABC / Mechanical Science / Chapter 10 / TP / Rev 02

5. IMPULSE TURBINE NOZZLE-BLADE ARRANGEMENT
Fig 10-5
ABC / Mechanical Science / Chapter 10 / TP / Rev 02

6. PRESSURE-VELOCITY DIAGRAM FOR A MOVING IMPULSE BLADE
TURBINE
SHAFT
DIRECTION OF SPIN
ENTRANCE
HIGH VELOCITY
STEAM INLET
REPRESENTS MOVING
IMPULSE BLADES
EXIT
LOW VELOCITY
STEAM EXHAUST
VELOCITY
PRESSURE
Fig 10-6
ABC / Mechanical Science / Chapter 10 / TP / Rev 02

7. PRESSURE-VELOCITY DIAGRAM FOR A FIXED IMPULSE BLADE
FIXED BLADES
NO MOVEMENT
ENTRANCE
STEAM INLET
REPRESENTS NON-MOVING
IMPULSE BLADES
EXIT
STEAM EXHAUST
PRESSURE
VELOCITY
NOTE: PRESSURE AND VELOCITY OF STEAM
DO NOT CHANGE ACROSS FIXED
IMPULSE BLADE. IT IS USED ONLY
FOR DIRECTIONAL FLOW CONTROL.
Fig 10-7
ABC / Mechanical Science / Chapter 10 / TP / Rev 02

8. REACTION TURBINE PRINCIPLE
STEAM CHEST
ROTOR
Fig 10-8
ABC / Mechanical Science / Chapter 10 / TP / Rev 02

9. PRESSURE-VELOCITY DIAGRAM FOR A MOVING REACTION BLADE
TURBINE
SHAFT
DIRECTION OF SPIN
ENTRANCE
HIGH PRESSURE
HIGH VELOCITY
STEAM INLET
REPRESENTS MOVING
REACTION BLADES
EXIT
LOW PRESSURE
LOW VELOCITY
STEAM EXHAUST
PRESSURE
VELOCITY
Fig 10-9
ABC / Mechanical Science / Chapter 10 / TP / Rev 02

10. PRESSURE-VELOCITY DIAGRAM FOR A FIXED REACTION BLADE
FIXED BLADES
NO MOTION
ENTRANCE
HIGH PRESSURE
LOW VELOCITY
STEAM INLET
REPRESENTS NON-MOVING
REACTION BLADES
EXIT
LOW PRESSURE
HIGH VELOCITY
STEAM EXHAUST
NOTE: A FIXED REACTION BLADE
IS ESSENTIALLY A NOZZLE
PRESSURE
VELOCITY
Fig 10-10
ABC / Mechanical Science / Chapter 10 / TP / Rev 02

11. IMPULSE TURBINE STAGING
MOVING
BLADE
PRESSURE
VELOCITY
NOZZLE
1ST STAGE –
NOZZLE & MOVING
FIXED
BLADE
MOVING
2ND STAGE –
FIXED & MOVING
Fig 10-11
ABC / Mechanical Science / Chapter 10 / TP / Rev 02

12. REACTION TURBINE STAGING
NOZZLE
MOVING
BLADE
FIXED
BLADE
MOVING
BLADE
PRESSURE
1ST STAGE –
NOZZLE & MOVING BLADE
2ND STAGE –
FIXED & MOVING BLADE
VELOCITY
Fig 10-12
ABC / Mechanical Science / Chapter 10 / TP / Rev 02

13. PRESSURE COMPOUNDED TURBINE
Fig 10-13
ABC / Mechanical Science / Chapter 10 / TP / Rev 02

14. VELOCITY COMPOUNDED TURBINE
Fig 10-14
ABC / Mechanical Science / Chapter 10 / TP / Rev 02

15. VELOCITY COMPOUNDED IMPULSE TURBINE
Fig 10-15
ABC / Mechanical Science / Chapter 10 / TP / Rev 02

16. PRESSURE COMPOUNDED IMPULSE TURBINE
Fig 10-16
ABC / Mechanical Science / Chapter 10 / TP / Rev 02

17. PRESSURE-VELOCITY COMPOUNDED IMPULSE TURBINE
Fig 10-17
ABC / Mechanical Science / Chapter 10 / TP / Rev 02

18. PRESSURE – VELOCITY – COMPOUNDED IMPULSE TURBINE (CURTIS AND RATEAU STAGING TURBINE)
Fig 10-18
ABC / Mechanical Science / Chapter 10 / TP / Rev 02

19. PRESSURE COMPOUNDED REACTION TURBINE
Fig 10-19
ABC / Mechanical Science / Chapter 10 / TP / Rev 02

20. PRESSURE-VELOCITY COMPOUNDED REACTION TURBINE
Fig 10-20
ABC / Mechanical Science / Chapter 10 / TP / Rev 02

21. Difference between impulse and reaction turbine
It consists of nozzles and moving blades
Moving blades (nozzles) and fixed blades (nozzles)
Steam stikes the blade with kinetic energy
Steam passes over the moving blades with pressure and kinetic energy
Pressure drops in nozzles and not in moving blades
Pressure drops in fixed blade as well as moving blade
Blade speed and steam speed are high
Blade speed and steam speed are less (small pressure drop)
Profile type blade shape
Aerofoil type blade shape
Low efficiency
high efficiency
Suitable for small power requirements
Suitable for high and medium power requirements
Occupies less space
Occupies more space
ABC / Mechanical Science / Chapter 10 / TP / Rev 02

22. GENERAL ENERGY EQUATION FOR A TURBINE
ABC / Mechanical Science / Chapter 10 / TP / Rev 02

23. IDEAL VS. REAL LOW PRESSURE TURBINE PROCESS
(b) T-s DIAGRAM P1 P2 2 2 T1
T2 & T2
WET STEAM
CRITICAL POINT
SATURATION
VAPOR
LINE 1 s
SPECIFIC ENTROPY (Btu/lbm R)
TEMPERATURE ( F)
(a) h-s DIAGRAM 2' h1 h2
SPECIFIC ENTHALPY (Btu/lbm)
h2
WET STREAM
Fig 10-21
ABC / Mechanical Science / Chapter 10 / TP / Rev 02

24. TURBINE EFFICIENCY TURBINE WORK
Equation 10-3
Equation 10-4
Eq 10-3, 10-4
ABC / Mechanical Science / Chapter 10 / TP / Rev 02

25. EXAMPLE
The enthalpy of the steam entering a turbine is 1,200 Btu/lbm and the ideal exit enthalpy of the exhaust steam is 780 Btu/lbm. The steam flow rate is 1  106 lbm/hr. The turbine efficiency is 90%. 1 HP = 2.54  103 Btu/hr.
1. Calculate the ideal work and shaft horsepower, produced by the turbine.
Ex 10-1
ABC / Mechanical Science / Chapter 10 / TP / Rev 02

26. EXAMPLE Using the conversion factor:
2. Calculate the real work if  = 90%.
Ex 10-1
ABC / Mechanical Science / Chapter 10 / TP / Rev 02

27. AXIAL FLOW TURBINE Fig 10-22
ABC / Mechanical Science / Chapter 10 / TP / Rev 02

28. DOUBLE AXIAL FLOW TURBINE
Fig 10-23
ABC / Mechanical Science / Chapter 10 / TP / Rev 02

29. JOURNAL BEARING LUBRICATION
Shaft at Rest
Thin Pad of Oil Formed
Oil Wedge Supports the Shaft
Rotation Starts
Fig 10-24
ABC / Mechanical Science / Chapter 10 / TP / Rev 02

30. THRUST BEARING
BABBIT
Fig 10-25
ABC / Mechanical Science / Chapter 10 / TP / Rev 02

31. TAPERED-LAND THRUST BEARING
COLLAR ROTATION
OIL
BEARING
SEGMENTS
WEDGE
THRUST COLLAR
SHAFT
Fig 10-26
ABC / Mechanical Science / Chapter 10 / TP / Rev 02

32. TYPICAL LUBE OIL SYSTEM
Fig 10-27
ABC / Mechanical Science / Chapter 10 / TP / Rev 02

33. LABYRINTH PACKING GLANDS
Fig 10-28
ABC / Mechanical Science / Chapter 10 / TP / Rev 02

34. CARBON PACKING GLANDS Fig 10-29
BLOCK OR STRIP
BORMETRIC
CONDENSER
(VACUUM)
PACKING
SPRING
KEY
TURBINE
SHELL
ATMOSPHERE
SHAFT
Fig 10-29
ABC / Mechanical Science / Chapter 10 / TP / Rev 02

35. TYPICAL TURBINE EXHAUST HOOD COOLING SYSTEM SCHEMATIC
Fig 10-30
ABC / Mechanical Science / Chapter 10 / TP / Rev 02