1

STEAM TURBINE

POWER PLANT

- Group Members: H. M. Furqan (EE106024)

Muhammad Taha

(EE106013)

Faisal Iqbal Khan

(EE306071)

2

DEFINITION

Turbines are used in  systems to convert kinetic energy of  fluid to mechanical energy

Steam Turbines.flv

3

C

saturated water

hot gases

SteamTurbine

Gen

compressed water

superheated steam

Condenser

Pump

cooling watersaturatedsteam

Steam Generator

Steam Turbine Power Plant

4

The Simple Steam Power Plant

5

Steam Turbine to produce Electricity

Oil could be used instead of coal.

6

CHOICE OF STEAM TURBINE

The choice of steam turbine depends on the following factors :

(i) Capacity of plant(ii) Plant load factor and capacity factor(iii) Thermal efficiency(iv) Reliability(v) Location of plant with reference to availability of water for condensate.

7

Rotor  Blades or Buckets Nozzles Bearing

Construction

8

Turbine Blades(Buckets)FIXED BLADES: These are constructed in halves. Fixed blades have a

convergent nozzle shape.

MOVING BLADES: These can be shaped either in reaction or impulse.

The K.E is transferred to a row of moving blades. Moving blades converts this K.E in to mechanical energy by rotation.

9

Rotor

10

11

12

Nozzle

13

Nozzle

14

Bearing

15

Bearing

16

Impulse Turbine Basic Priciple The toy pinwheel can be used to study

some of the basic principles of turbines. when you blow on the rim of the wheel, it spins rapidly the harder you blow the faster it run.

17

IMPULSE TURBINE An impulse turbine has fixed nozzles that orient

the steam flow into high speed jets. A pressure drop occurs across only the stationary blades, with a net increase in steam velocity across the stage.

The steam leaves the nozzle with a very high velocity

The steam leaving the moving blades is a large portion of the maximum velocity of the steam when leaving the nozzle

18

Impulse Turbine

19

Basic Principle of Reaction Turbine Reaction turbine is built on principle of

Newton’s third law of motion which state:

For every action there must be an equal and opposite reaction

20

REACTION TURBINE In the reaction turbine, the rotor blades

themselves are arranged to form convergent nozzles. This type of turbine makes use of the reaction force produced as the steam accelerates through the nozzles formed by the rotor.

The steam then changes direction and increases its speed relative to the speed of the blades

21

A pressure drop occurs across both the stator and the rotor, with steam accelerating through the stator and decelerating through the rotor, with no net change in steam velocity across the stage but with a decrease in both pressure and temperature

22

Comparision of Impulse and Reaction Turbine In case of an impulse turbine the pressure

remains same in the rotor,but in case of reaction turbine the pressure decreases in rotor as well as stators also.

In case of impulse turbine the pressure drop happens only in the nozzle part by means of its kinetic energy. In case of Reaction one the stators those are fixed to the diaphragm act as a nozzle.

23

24

25

Main Componets of TurbineTANDUM COMPOUND:

The different cylinders(HP-IP and LP cylinders) mounted over one common shaft to derive a generator is called the tendum compound.

SHROUDING: A metal band along the outer rim of the blading is

called a shrouding, which ties the blading together.STAGE: One row of moving and one row of fixed blade is

called a stage.26

ROTOR: The rotor assembly consists of turbine shaft and

attached moving blades.

CYLINDER: A turbine rotor assembly and casing as a unit

is called a cylinder.

BEARINGS: Bearings keep the rotor in its correct axial

position.

27

TURNING GEAR:

Function of turning gear is to keep the turbine turning during startup and shut down periods.

EXHAUST HOOD COOLING SYSTEM:

This system is designed to reduce the stresses on turbine parts that could result from exposures to high temperatures

GLAND STEAM SEALING:

The steam is admitted to the rotor glands to prevent air ingress to LP turbine and steam leak out from HP-IP rotor glands.

28

TURBINE VALVES Main stop valves

MSV pilot valves open and steam enters in chest by full arc admission. Its for proper warming of steam chest

Governing valves Valve transfer takes

place,control shifts from MSV s’ to GV s Interceptor valves

ICV regulates or shuts off the steam flow rate during emergency or shut down. Starts to close on overspeeding. 29

ECCENTRICITY: The amount that rotor deviates from its normal

center of rotation. It will be active up to 600 rpm.

ROTOR POSITION: Rotor position indicator indicates relative

movement between thrust bearing collar and thrust bearing pedestal.

VIBRATION: The radial movement of the shaft is measured

in terms of vibration. The excessive vibration will cause shaft and seal wear and bearing damage.

30

PROTECTIVE DEVICE

Following protective device must be carried out on

monthly basis.

1. Over speed test.

2. Condenser vacuum low trip.

3. Bearing oil pressure low trip.

4. Thrust bearing wear trip.

31

STEAM TURBINE CAPACITY The capacities of small turbines and coupled

generators vary from 500 to 7500 kW whereas large turbo alternators have capacity varying from 10 to 90 mW. Very large size units have capacities up to 500 mW.

Generating units of 200 mW capacity are becoming quite common. The steam consumption by steam turbines depends upon steam pressure, and temperature at the inlet, exhaust pressure number of bleeding stages etc. The steam consumption of large steam turbines is about 3.5 to 5 kg per kWh.

32

STEAM TURBINE CAPACITY(CONT) Turbine kW = Generator kW / Generator efficiency Generators of larger size should be used because

of the following reasons: (i) Higher efficiency. (ii) Lower cost per unit capacity. (iii) Lower space requirement per unit capacity.

3.45.1 Nominal rating. It is the declared power capacity of turbine

expected to be maximum load.

33

CAPABILITY The capability of steam turbine is the maximum

continuous out put for a clean turbine operating under specified throttle and exhaust conditions with full extraction at any openings if provided.

The difference between capability and rating is considered to be overload capacity. A common practice is to design a turbine for capability of 125% nominal rating and to provide a generator that will absorb rated power at 0.8 power factor. By raising power factor to unity the generator will

absorb the full turbine capability.

34

ADVANTAGES OF STEAM TURBINE

It requires less space. Absence of various links such as piston, piston rod,

cross head etc. make the mechanism simple. It is quiet and smooth in operation,

Its over-load capacity is large. It can be designed for much greater capacities as

compared to steam engine. Steam turbines can be built in sizes ranging from a few horse power to over 200,000 horse power in single units

35

ADVANTAGES OF STEAM TURBINE (cont)

The internal lubrication is not required in steam turbine. This reduces to the cost of lubrication.

In steam turbine the steam consumption does not increase with increase in years of service.

In steam turbine power is generated at uniform rate, therefore, flywheel is not needed.

It can be designed for much higher speed and greater range of speed.

The thermodynamic efficiency of steam turbine is higher.

36

SPECIFICATIONType………………………………….. Single reheat condensing tandem

two cylinder double flow

exhaustMCR…………………………………. 362 MWSpeed……………………………….… 3000 rpmDirection of rotation………………..... clockwise (from GV end)Inlet pressure……………………….... 169kg/cm2 Inlet temperature…………….….…… 538 C0 (Main steam and reheat)Exhaust pressure ………………….… 692 mmHgNo of Extractions………………….… 8 Blading:HP Turbine……………….Impulse ………1 Stage (Rateau). Reaction………11Stages.IP Turbine……………….. Reaction………10 Stages.LP Turbine……………….Reaction………..6 Stages.

37

APPLICATION

LIMIT ALARM/TRIP REMARKS

Main steam and hot

reheat steam (Turbine

Inlet)

+ 8 0 C

+ 14 0 C

+ 28 0 C

Max allowable temperature

Emergency Allowable

Max In A amount

With in 400 hrs in a year

With in 15 minutes continuously & 80 hrs a year

Main steam Pressure (Turbine

Inlet)

+5 %

+10 %

+20 %

Mean allowable for continous operation.

Maximum allowable for continous operation.

Max Emergency allowable.With in 12 hrs in a year.

38

APPLICATION LIMIT ALARM/TRIP REMARKS

Journal bearing metal temperature

107 0 C

113 0 C

Alarm

Trip

Thrust bearing metal temperature

99 0 C

107 0 C

Alarm

Trip

Bearing oil drain temperature

77 0 C Alarm

Exhaust Hood Temp.

80 0 C

70 0 C

120 0 C

AlarmSpray set point

Trip39

APPLICATION LIMIT ALARM/TRIP REMARKS

Condenser Vacuum

692 mm Hg

635 mmHg

500 mmHg

Normal

Alarm

Trip

Vacuum Breaker

< 400 rpm

Over speed trip.

< 111 %

Valve stem free test

75 % load

Bearing oil temp. at exit of oil cooler

50 0 C

40

APPLICATION LIMIT ALARM/TRIP REMARKS

Eccentricity 0.075 mm Alarm 0 – 600 rpm

Rotor Vibration

0.125 mm

0.25 mm

Alarm

Trip

Rotor Position

+ 0.9 mm

+ 1 mm

Alarm

Trip

+ thrust side.

- Anti thrust side.

Thrust bearing wear

2.1 Kg/cm2

5.6 Kg/cm2

Alarm

Trip

Differential expansion

- 1.7 – 15.8 mm

Alarm

41

Thank You

42