An overview on the definition, classification and working principle of ST

1. STEAM TURBINE

2. CONTENT
I. Introdution
II. Working principle
III. Construction
IV. Operation

3. What is the Turbine?What is the Turbine?
TURBINE is a power machine to drive working machine such asTURBINE is a power machine to drive working machine such as
compressor, pump, electrical generator.compressor, pump, electrical generator.
 Steam TurbineSteam Turbine
 Gas TurbineGas Turbine
 Water TurbineWater Turbine

4. Steam TurbineSteam Turbine

5. Gas TurbineGas Turbine

6. Water TurbineWater Turbine

7.  Steam turbines are made in a variety of sizes ranging fromSteam turbines are made in a variety of sizes ranging from
small <0.75 kW (<1 hp) units (rare) used as mechanical drivessmall <0.75 kW (<1 hp) units (rare) used as mechanical drives
for pumps, compressors and other shaft driven equipment, tofor pumps, compressors and other shaft driven equipment, to
1 500 000 kW (1.51 500 000 kW (1.5 GWGW; 2 000 000 hp) turbines used to; 2 000 000 hp) turbines used to
generate electricity.generate electricity.
 Selection of steam turbine type depend on the overall processSelection of steam turbine type depend on the overall process
requirement and configuration as well as project/ operationrequirement and configuration as well as project/ operation
cost reason.cost reason.

10. Parts and equipmentParts and equipment

11.  Steam turbine can be classified as theSteam turbine can be classified as the
following:following:
• By steam supply and exhaust conditions:By steam supply and exhaust conditions:
 Back pressure Turbine or none condensing turbine.Back pressure Turbine or none condensing turbine.
 Condensing Turbine.Condensing Turbine.
 Extraction Steam Turbine.Extraction Steam Turbine.
 Induction Steam TurbineInduction Steam Turbine
 Reheat Steam TurbineReheat Steam Turbine
• By Blades and Stages design:By Blades and Stages design:
 Impulse TurbineImpulse Turbine
 Reaction Turbine.Reaction Turbine.

12. Non-Condensing Steam Turbine:Non-Condensing Steam Turbine:
Non-condensing or back pressure turbines are most widely usedNon-condensing or back pressure turbines are most widely used
for process steam applications. The exhaust pressure is controlledfor process steam applications. The exhaust pressure is controlled
by a regulating valve to suit the needs of the process steamby a regulating valve to suit the needs of the process steam
pressure.pressure.

13. Condensing Steam TurbineCondensing Steam Turbine
Condensing turbines are most commonly found in electricalCondensing turbines are most commonly found in electrical
power plants. These turbines exhaust steam from a boiler in apower plants. These turbines exhaust steam from a boiler in a
partially condensed state, typically of a quality near 90%, at apartially condensed state, typically of a quality near 90%, at a
pressure well below atmospheric to a condenser.pressure well below atmospheric to a condenser.

14. Extraction Steam Turbine:Extraction Steam Turbine:
In an extracting type turbine, steam is released from variousIn an extracting type turbine, steam is released from various
stages of the turbine, and used for industrial process needs or sentstages of the turbine, and used for industrial process needs or sent
to boiler feed water heater to improve overall cycle efficiency.to boiler feed water heater to improve overall cycle efficiency.
Extraction flows may be controlled with a valve, or leftExtraction flows may be controlled with a valve, or left
uncontrolled.uncontrolled...

15. Induction Steam TurbineInduction Steam Turbine
Induction turbines introduce low pressure steam at anInduction turbines introduce low pressure steam at an
intermediate stage to produce additional power.intermediate stage to produce additional power.

16. Reheat Steam TurbineReheat Steam Turbine
In a reheat turbine, steam flow exits from a high pressure sectionIn a reheat turbine, steam flow exits from a high pressure section
of the turbine and is returned to the boiler where additionalof the turbine and is returned to the boiler where additional
superheat is added. The steam then goes back into ansuperheat is added. The steam then goes back into an
intermediate pressure section of the turbine and continues itsintermediate pressure section of the turbine and continues its
expansion. Using reheat in a cycle increases the work outputexpansion. Using reheat in a cycle increases the work output
from the turbine and also the expansion reaches conclusionfrom the turbine and also the expansion reaches conclusion
before the steam condenses, there by minimizing the erosion ofbefore the steam condenses, there by minimizing the erosion of

17. Impulse & Reaction TurbinesImpulse & Reaction Turbines

18. Impulse TurbinesImpulse Turbines

19. Impulse Steam TurbineImpulse Steam Turbine
 On Impulse Turbine a thermal expansion take place only in theOn Impulse Turbine a thermal expansion take place only in the
nozzles and static energy is converted to the kinetic energynozzles and static energy is converted to the kinetic energy
 There is no pressure different at inlet and outlet of blades onThere is no pressure different at inlet and outlet of blades on
the rotor, because the thermal expansion only in the nozzles. Itthe rotor, because the thermal expansion only in the nozzles. It
means no thrust force acting on the rotor disc.means no thrust force acting on the rotor disc.

20. Reaction Steam TurbineReaction Steam Turbine
Reaction stage
Thermal expansion occurs both in the nozzles and blades. The impulse force
comes from the kinetic energy which is converted in the nozzles, and
reaction force created in the blades comes due to decreasing steam pressure.
These two forces produce the rotation torque of the blades on the rotor. On
this type, differential pressure between the inlet and outlet of blades
generates thrust force to turbine shaft. Therefore, to reduce the thrust force
acting on the shaft, shaft diameter is equal to the diameter of the blade root,
and blades are mounted on shaft directly.

21. Impulse and Reaction TurbineImpulse and Reaction Turbine

22. Actually, Steam turbine using in the refineries are combined impulse andActually, Steam turbine using in the refineries are combined impulse and
reaction to get more advantages and less disadvantagesreaction to get more advantages and less disadvantages

23. NozzleNozzle

31. Thrust & Radial bearingsThrust & Radial bearings

32. Journal BearingJournal Bearing

35. Self Equalizing tilting padSelf Equalizing tilting pad

36. Sealing ProblemSealing Problem

37. Labyrinth effectivenessLabyrinth effectiveness

38. Sealing of Steam TurbineSealing of Steam Turbine

39. Monitoring systemMonitoring system

40. Function of Trip Throttle Valve (TTV)Function of Trip Throttle Valve (TTV)
 Adjustment of steam flow to turbine duringAdjustment of steam flow to turbine during
start-up.start-up.
 Close valve quickly as the pressure ofClose valve quickly as the pressure of
control oil lose due to interlock trip ofcontrol oil lose due to interlock trip of
turbine or push the button trip.turbine or push the button trip.
 Partial stroke test of TTV.Partial stroke test of TTV.

41. Trip Valve and Control ValveTrip Valve and Control Valve

42. Trip ValveTrip Valve

43. Trip Throttle ValveTrip Throttle Valve

44. Trip Throttle ValveTrip Throttle Valve

45. Throttle valve operationThrottle valve operation

47.  Condensing system(Cond)Condensing system(Cond)
• Air in condenser is sucked by steam ejector and send to inter coolerAir in condenser is sucked by steam ejector and send to inter cooler
together with ejector driving steam. In inter cooler steam is cooltogether with ejector driving steam. In inter cooler steam is cool
down by condensed water and convert to water and returns todown by condensed water and convert to water and returns to
condeser through siphon tube.condeser through siphon tube.
• Air in inter cooler is suck again by steam ejector and send to afterAir in inter cooler is suck again by steam ejector and send to after
cooler and only water in after cooler return to condenser throughcooler and only water in after cooler return to condenser through
steam trap and air goes to outside.steam trap and air goes to outside.

48. Assume that:
- Steam stream meets all the conditions about pressure and
temperatue before to be taken to turbine.
- All the systems including: electrical, control, pneumatic system,
closed cooling water system, condensate system, feed water
system, boiler) in normal operation condition. No more failure on
the devices
The steps for starting turbine as following:
Start-up Procedure
OPERATION

49. 1. Placing the turbine lubrication oil system in service:
- Start one duty pump and place the remain in spare
- Test change over
- Check parameter: pressure,temperature, condition of cooler,
filter..

50. 2. Running turning gear system:
- Turning gear is done before start up and after shutdown turbine.
- The turning gear times depend on the outage duration of turbine
(start up) or metal temperature (shutdown), may be from severe
hours to one day in case of start up.
Less than one day: 2 hours
Up to7 days: 6 hours
Up to 30 days: 12 hours
Over 30 days: 24 hours
Normally, a motor is used for turning gear. The turning speed varies
from above ten rpm to hundred rpm.

51. 3. Placing the turbine governing system (or EHC)
in service:
- Start the hydraulic pump, check header pressure
- Check condition of valve and pipe is not abnormal
- Trip test (by push Emergency stop button)
- Setting initial loading (for generator driven) or no-load
speed (compressor or pump driven) and loading limiter
(gradient)

52. 4. Pre-runup checks of turbine valves
- In order to detect valve malfunction before steam admitted to the
turbine
- If having any problem in valve operation , it must be repaired
before turbine start up
- The valves are tested including stop valves and control valves
- During the valve checks, the turbine isolating valves close to
prevent steam flow through the turbine. Once valve completely
checked, these valve open to allow steam flow to the emergency
stop valve.

53. 5. Place the condensate cooling water (ccw) system
in service:
-Start ccw pump, check the parameters
-Place the condensate cleaning system in service
-Place vacumn the primary system (for water box) in service
(if installed)
-Monitoring parameters..

54. 6. Place the gland sealing steam system in service:
- To sealing turbine before pulling condensate vacumn
- Before start up, gland sealing steam is extracted from the
live steam system ( or auxiliary steam systeam) and
decreased both pressure and temperature (pressure: sligher
than atmospheric about 30-40 mbar, temperature: different
from metal temperature about 50oC)
- Check the gland steam condenser in normal condition

55. 7. Pulling condenser vacumn:
Doing before start up:
-To reduce the tendency of the LP turbine exhause to overheat
-To prevent excessive flow – induced vibration of moving
blades in the turbine last stage
Activities:
-Start the vacumn pumps or ejectors.
-Monitoring the condensate pressure below 150 mbara

56. 8. Placing the LP turbine exhaust cooling system in
service:
- Supply the cooling spray water to protect the LP turbine last
stages, condensate tubes from overheating when turbine
exhaust temperature is high.
- The control valve will open and closing base on exhaust
temperature.

57. 9. Turbine warm-up
-To reduce thermal stress caused by temperature different
between live steam and turbine metal
-Normally, a control valve is used to extract steam from live
steam and taken to the turbine. The temperature rising of
turbine metal is limited and depend on the initial turbine metal
temperature, may from 30-100o
C/hour.
-After temperature different between live steam and turbine
metal below 50o
C, can finish warm-up step.

58. 10. Start - up turbine:
Base on initial turbine metal temperature, can classify 3 start up
modes:
- Cold start: Turbine metal temperature < 150o
C
- Warm start: Turbine metal temperature :150o
C - 410o
C
- Hot start: Turbine metal temperature > 410o
C

59. Before start up, operators must carefully check performance of all the
system concerned are normal and ready, example: vacumn pressure,
lube oil pressure and temperature, position of drain valve….
-Setting the speed target, run up rate, initial loading, holding speed,
warm up time.. base on mismatch diagram. Carefully check in case of
auto-setting.
-Press start button to run up turbine.
-The control valve will slowly open and steam flow to the turbine for
rotary
-Turning gear disengaged and turbine run up base on start up curve.

60. Start up curve

62. Start up on DCS

63. Monitoring in operation:
- Critical speed
- Shaft eccentricity
- Thermal stress
- Shaft vibration
- Differential Expansion
- Temperature: lube oil temperature, bearing metal temperature
- Turbine exhaust hood: Vacumn, temperature,
- Steam qualities: Silica, conductivity, pH