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Chapter # 1 TURBINE

1.1 Introduction

1.2 Types Of Turbine

1.2.1 Steam Turbine

1.2.2 Gas Turbine

1.2.3 Transonic Turbine

1.2.4 Contra-Rotating Turbine

1.2.5 Statorless Turbine

1.2.6 Ceramic Turbine

1.2.7 Shrouded Turbine

1.2.8 Shroud less Turbine

1.2.9 Bladeless Turbine

1.2.10 Water Turbine

1.2.11 Wind Turbine

1.2.12 Tide Turbine

1.3 Turbine Component

1.3.1 Shell and Casing

1.3.2 Nozzles

1.3.3 Diaphragms

1.3.4 Turbine Seals


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1.3.5 Turbine Rotor and Buckets

1.3.6 Standards

1.3.7 Bearings

1.3.8 Turning Gear

1.3.9 Shaft Grounding Brushes

1.3.10 Main Steam Valve

1.3.11 Auxiliary Steam Valve

1.3.12 Moisture Separator

1.4 Theory of Operation

1.5 Basic Performance of Turbine Stage

1.6 Uses of Turbine

Chapter # 2 STEAM TURBINE

2.1 Introduction

2.2 History

2.3 Types of Steam Turbine

2.4 Principle of Operation

2.5 Turbine Efficiency

2.6 Function of Turbine Stages


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2.7 Operation and Maintenance

2.8 Speed Regulation

Chapter # 3 IMPULSE TURBINE

3.1 Introduction

3.2 IMPULSE PRINCIPLE

3.3 Impulse

3.4 Types of Impulse Turbine

3.4.1 Single Stage impulse Turbine

3.4.2 Compounded Multi Stage impulse

Steam Turbine

3.4.2.1 Velocity Compounded Impulse Turbine

3.4.2.2 Pressure Compounding Impulse

Turbine

3.4.2.3 Comparison between Pressure and

Velocity Compounding Impulse Turbine

3.5 Advantages of Impulse Turbine

3.6 Design Considerations of Impulse Turbine

3.6.1 Principle Component Of Impulse

Steam Turbine

3.6.2 Blading Design


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3.6.3 Turbine Staging

3.7 Power Development

3.8 Control

3.9 Overall Performance Characteristics

Chapter # 4 Thermodynamic Cycle

4.1 Introduction

4.2 Thermodynamic Power Cycle

4.3 Types of Thermodynamic Cycles

4.4 Carnot Cycle

4.5 Rankine Cycle

4.5.1 Process of Rankine Cycle

4.5.2 Equation

4.5.3 Rankine cycle With Reheat

4.6 Regenerative Rankine Cycle

Chapter # 5 Construction

5.1 Material

5.2 Tooling


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5.3 Maintenance

5.4 Calculation

Chapter # 6 Conclusion


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CHAPTER- 1

TURBINE

1.1Introduction :-

A turbine is a rotary mechanical device that extracts energy from a fluid

flow and converts it into useful work. The simplest turbines have one

moving part, a rotor assembly, which is a shaft or drum with blades

attached. Moving fluid acts on the blades, or the blades react to the

flow, so that they move and impart rotational energy to the rotor. Earlyturbine examples are windmills and water wheels.

1.2Types Of Turbine:-

1.2.1 Steam Turbine:-

A steam turbine is a mechanical device that extracts thermal

Energy from pressurized steam, and converts it into rotary

Motion. Its modern manifestation was invented by Sir Charles Parsons

in 1884. It has almost completely replaced the reciprocating piston

steam engine (invented by Thomas Newcomen and greatly improved by

James Watt) primarily because of its greater thermal efficiency and

higher power to weight ratio. Because the turbine generates rotary

motion, it is particularly suited to be used to drive an electricalgenerator about 80% of all electricity generation in the world is by

use of steam turbines. The steam turbine is a form of heat engine that

derives much of its improvement in thermodynamic efficiency through

the use of multiple stages in the expansion of the steam, which results

in a closer approach to the ideal reversible process.


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1.2.2 Gas Turbine:-A gas turbine, also called a combustion turbine, is a type of internal

combustion engine. It has an upstream rotating compressor coupled to

a downstream turbine, and a combustion chamber in-between.

1.2.3 Transonic Turbine:-The gas flow in most turbines employed in gas turbine engines remains

subsonic throughout the expansion process. In a transonic turbine the

gas flow becomes supersonic as it exits the nozzle guide vanes,

although the downstream velocities normally become subsonic.

Transonic turbines operate at a higher pressure ratio than normal but

are usually less efficient and uncommon.

1.2.4 Contra Rotating Turbine:-With axial turbines, some efficiency advantage can be obtained if a

downstream turbine rotates in the opposite direction to an upstream

unit. However, the complication can be counter-productive. The design

is essentially a multi-stage radial turbine (or pair of 'nested' turbine

rotors) offering great efficiency, four times as large heat drop per stage

as in the reaction (Parsons) turbine, extremely compact design and the

type met particular success in backpressure power plants.

1.2.5 Statorless Turbine:-Multi-stage turbines have a set of static (meaning stationary) inlet

guide vanes that direct the gas flow onto the rotating rotor blades. In a

Statorless turbine the gas flow exiting an upstream rotor impinges onto

a downstream rotor without an intermediate set of stator vanes (thatrearrange the pressure/velocity energy levels of the flow) being

encountered.

1.2.6 Ceramic Turbine:-


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Conventional high-pressure turbine blades (and vanes) are made from

nickel based alloys and often utilize intricate internal air-cooling

passages to prevent the metal from overheating. In recent years,

experimental ceramic blades have been manufactured and tested in

gas turbines, with a view to increasing Rotor Inlet Temperatures

and/or, possibly, eliminating air-cooling. Ceramic blades are more

brittle than their metallic counterparts, and carry a greater risk of

catastrophic blade failure. This has tended to limit their use in jet

engines and gas turbines to the stator (stationary) blades.

1.2.7 Shrouded Turbine:-

Many turbine rotor blades have shrouding at the top, which interlockswith that of adjacent blades, to increase damping and thereby reduce

blade flutter. In large land-based electricity generation steam turbines,

the shrouding is often complemented, especially in the long blades of a

low-pressure turbine, with lacing wires. These wires pass through holes

drilled in the blades at suitable distances from the blade root and are

usually brazed to the blades at the point where they pass through.

Lacing wires reduce blade flutter in the central part of the blades. The

introduction of lacing wires substantially reduces the instances of bladefailure in large or low-pressure turbines.

1.2.8 Shroud less Turbine:-Shroud less Turbine has no shrouding. Modern practice is, wherever

possible, to eliminate the rotor shrouding, thus reducing the centrifugal

load on the blade and the cooling requirements.

1.2.9 Bladeless Turbine:-Bladeless turbine uses the boundary layer effect and not a fluid

impinging upon the blades as in a conventional turbine.


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1.2.10 Water turbine:-A water turbine is a rotary engine that takes energy from moving water.

Water turbines were developed in the nineteenth century and were

widely used for industrial power prior to electrical grids. Now they aremostly used for electric power generation.

o Pelton turbine, a type of impulse water turbine.

o Francis turbine, a type of widely used water turbine.

o Kaplan turbine, a variation of the Francis Turbine.

o Turgo turbine, a modified form of the Pelton wheel.

1.2.11 Wind Turbine:-Wind turbines extract energy from the wind, mostly for electricity

generation. These normally operate as a single stage without nozzle

and interstage guide vanes.

1.2.12 Tide Turbine:-A tidal turbine acts underwater in a very similar way to how wind

turbines operate in the air. Water is some 800 times denser than air,

and so even slow moving tides can exert much greater forces than thewind on a turbine. Therefore a working tidal turbine can have much

smaller diameter rotors than equivalent power outputs wind turbine

keeping costs of manufacture and transportation down.

An emerging renewable energy technology is the shrouded tidal turbine

enclosed in a venturi shaped shroud or duct producing a sub

atmosphere of low pressure behind the turbine.

1.3 Turbine Component:-Major Centerline Components
http://en.wikipedia.org/wiki/Francis_turbinehttp://en.wikipedia.org/wiki/Francis_turbinehttp://en.wikipedia.org/wiki/Francis_turbine


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This section describes the major components of turbines which

on turbine centerline such as turbine casing and rotors, as well as

important supporting components such as standards and

bearings. Major turbine valves and supporting systems are

described later.

1.3.1 Shell and casing:-The function of casing and shell in the turbine is to either keep

the steam in the turbine and/or air out. The shell and casing

also supports the stationary internals of the turbines and hold

those parts in alignment with the rotors.

1.3.2 Nozzle:-A nozzle is a device that converts thermal energy of a fluid into

kinetic energy by expanding the fluid.

Before reaching the turbine, the fluid'spressure headis

changed to velocity headby accelerating the fluid with a

nozzle. Pelton wheels and de Laval turbines use this process

exclusively. Impulse turbines do not require a pressure

casement around the rotor since the fluid jet is created by thenozzle prior to reaching the blading on the rotor. Newton's

second law describes the transfer of energy for impulse

turbines.

The nozzles are made up of various proportions that have

appearance of air foils, similar to rotating blades


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Nozzle

1.3.3 Diaphragm:-

Partitions between pressure stages in a turbine's casing arecalled diaphragms. They hold the vane-shaped nozzles and

seals between the stages. Usually labyrinth-type seals are used.

One-half of the diaphragm is fitted into the top of the casing,

the other half into the bottom.

Diaphragm

1.3.4 Turbine seals:-Seals are used to control the leakage of steam. The leakage

may be between turbine stages inside the turbine or where theshaft penetrates the turbine shells or casings. The interstage

seals, as they are called, are mounted on the inside diameter of

the diaphragms.


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1.3.5 Turbine Rotors and Bucket:-The turbine buckets or blades work with the steam from the

stationary nozzles to produce a torque on the rotor, or spindle

as it is sometimes called. The rotor holds all the buckets andtransmits the rotating mechanical energy to the generator.

Turbine rotors are large forgings with a bore hole at the

centerline.

Typical Turbine Bucket

1.3.6 Standatds:-Standards support the turbine shells and/or turbinebearings. Standards, such as the front standard, alsohouse turbine controls and instruments.


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1.3.7 Bearings :-

Bearings support and/or properly position the turbine rotor with

respect to the stationary turbine parts. There are generally two types ofbearings, (1) journal or radial and (2) thrust. The journal or radial

bearings support the weight of the rotor and position it radially. The

thrust bearing absorbs axial forces on the rotor and positions it axially

with respect to the stationary turbine parts.

1.3.8 Turning Gears:-

The turning gear turns the turbine rotor slowly, about 3-7 rpm,during shutdown, prior to starting the turbine, or when the turbine is

hot. Turning the rotor slowly ensures that it is heated or cooled

evenly. If the rotor is allowed to come to a rest when hot, temporary

bowing and excessive vibration can result. Distortion of the turbine

casing also results because the hotter steam rises to the top of the

casing.

The turning gear consists of an electric motor driving a speedreducing gear train. A simplified turning gear is shown in Figure.


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1.3.9 Shaft Grounding:-A static charge can build up on the turbine rotor due to the flow

of steam over the buckets. This affect is somewhat similar to the

accumulation of static charge in clouds that result in lightning.Voltages on the turbine rotor can also result from currents in the

generator rotor and/or the exciter. When the voltage difference

between the rotor and bearing became large enough to jump to

oil film in the bearing. The high voltage discharge (up to 150 volts)

would damage the bearings. The shaft grounding brushes provide

a low resistance current path from the rotor to ground.

1.3.10 Main Steam Valve:-The main steam valves control the flow of steam from the boiler

to the turbine under emergency and normal operating conditions.

1.3.11 Auxilary System:-Near are several kinds of auxiliary steam valves used on turbines

; specific manufacturers information should be referenced for

details. Common auxiliary steam valves discussed in this chapter

are :

Extraction nonreturn valves (positive nonreturn)

Packing blowdown valve

Ventilator valve

Heating steam blocking valve

Heating steam feed valve

Steam pipe drain valves

1.3.12 Moisture Separator:-Moisture separators are large vessels with special panels which

force the wet steam to follow a zig zag path. These panels are

made up of chevron plates as shown in Figure . The water


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droplets cannot follow the same path since they are so much

more dense than the steam. The droplets fall out and are drained

from the vessel. These moisture separators can remove all but a

small fraction of (less than 1%) the moisture in the steam.

1.4 Theory Of Operations:-A working contains potential energy (Pressure Head) and kinetic

energy (Velocity Head). The fluid may be compressible or

incompressible several physical principles are employed by

turbine to collect this energy.

a)Impulse Turbine

b)Reaction Turbine

1.5 Basic performance of a Turbine Stage:-

Velocity triangles can be used to calculate the basic performanceof a turbine stage. Gas exits the stationary turbine nozzle guide

vanes at absolute velocity Va1. The rotor rotates at velocity U.

Relative to the rotor, the velocity of the gas as it impinges on the

rotor entrance is Vr1. The gas is turned by the rotor and exits,

relative to the rotor, at velocity Vr2. However, in absolute terms

the rotor exit velocity is Va2. The velocity triangles are constructed

using these various velocity vectors. Velocity triangles can be

constructed at any section through the blading (for example: hub,tip, midsection and so on) but are usually shown at the mean stage

radius. Mean performance for the stage can be calculated from

the velocity triangles, at this radius, using the Euler equation:


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Hence:

where:

specific enthalpy drop across stage

turbine entry total (or stagnation) temperature

turbine rotor peripheral velocity

change in whirl velocity

The turbine pressure ratio is a function of and the turbine

efficiency.

The primary numerical classification of a turbine is its specific speed.

This number describes the speed of the turbine at its maximum

efficiency with respect to the power and flow rate. The specific speed is

derived to be independent of turbine size. Given the fluid flow

conditions and the desired shaft output speed, the specific speed can

be calculated and an appropriate turbine design selected.

The specific speed, along with some fundamental formulas can be used

to reliably scale an existing design of known performance to a new

sizewith corresponding performance.


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1.6 Uses of turbine:-

Almost all electrical power on Earth is produced with a turbine of some

type. Very high efficiency steam turbines harness about 40% of the

thermal energy, with the rest exhausted as waste heat.

Mostjet engines rely on turbines to supply mechanical work from their

working fluid and fuel as do all nuclear ships and power plants.

Turbines are often part of a larger machine. A gas turbine, for example,

may refer to an internal combustion machine that contains a turbine,

ducts, compressor, combustor, heat-exchanger, fan and (in the case of

one designed to produce electricity) an alternator. Combustion turbinesand steam turbines may be connected to machinery such as pumps and

compressors, or may be used for propulsion of ships, usually through

an intermediate gearbox to reduce rotary speed.

Reciprocating piston engines such asaircraft enginescan use a turbine

powered by their exhaust to drive an intake-air compressor, a

configuration known as aturbocharger(turbinesupercharger) or,

colloquially, a "turbo".

Turbines can have very high power density (i.e. the ratio of power to

weight, or power to volume). This is because of their ability to operate

at very high speeds. TheSpace Shuttle's main engines useturbo pumps

(machines consisting of a pump driven by a turbine engine) to feed the

propellants (liquid oxygen and liquid hydrogen) into the engine's

combustion chamber. The liquid hydrogen turbo pump is slightly larger

than an automobile engine (weighing approximately 700 lb.) andproduces nearly 70,000 HP (52.2MW).
http://en.wikipedia.org/wiki/Aircraft_enginehttp://en.wikipedia.org/wiki/Aircraft_enginehttp://en.wikipedia.org/wiki/Aircraft_enginehttp://en.wikipedia.org/wiki/Turbochargerhttp://en.wikipedia.org/wiki/Turbochargerhttp://en.wikipedia.org/wiki/Turbochargerhttp://en.wikipedia.org/wiki/Superchargerhttp://en.wikipedia.org/wiki/Superchargerhttp://en.wikipedia.org/wiki/Superchargerhttp://en.wikipedia.org/wiki/Space_Shuttlehttp://en.wikipedia.org/wiki/Space_Shuttlehttp://en.wikipedia.org/wiki/Space_Shuttlehttp://en.wikipedia.org/wiki/Turbopumphttp://en.wikipedia.org/wiki/Turbopumphttp://en.wikipedia.org/wiki/Turbopumphttp://en.wikipedia.org/wiki/Megawatthttp://en.wikipedia.org/wiki/Megawatthttp://en.wikipedia.org/wiki/Megawatthttp://en.wikipedia.org/wiki/Turbopumphttp://en.wikipedia.org/wiki/Space_Shuttlehttp://en.wikipedia.org/wiki/Superchargerhttp://en.wikipedia.org/wiki/Turbochargerhttp://en.wikipedia.org/wiki/Aircraft_engine


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CHAPTER- 2

STEAM TURBINE

2.1 Introduction:-A steam turbine is a device that extracts thermal energy from

pressurized steam and uses it to do mechanical work on a rotating

output shaft

Because the turbine generates rotary motion, it is particularly

suited to be used to drive an electrical generator about 90% of

all electricity generation in the United States is by use of steamturbines. The steam turbine is a form of heat engine that derives

much of its improvement in thermodynamic efficiency through

the use of multiple stages in the expansion of the steam, which

results in a closer approach to the ideal reversible process.


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2.2 History:-

The first device that may be classified as a reaction steam turbine was

little more than a toy, the classicAeolipile, described in the 1st century

by Greek mathematician.

The modern steam turbine was invented in 1884 by the Anglo-Irish

engineer Sir Charles Parsons, whose first model was connected to a

dynamo that generated 7.5 kW (10 HP) of electricity. The invention of

Parson's steam turbine made cheap and plentiful electricity possible

and revolutionized marine transport and naval warfare.

1889 De Laval developed the first particle impulse turbine. The machinedeveloped around 2Kw of power.

An Illustration of Heros Aeolipile
http://en.wikipedia.org/wiki/Aeolipilehttp://en.wikipedia.org/wiki/Aeolipilehttp://en.wikipedia.org/wiki/Aeolipilehttp://en.wikipedia.org/wiki/Aeolipile


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2.3 Types of Steam Turbine:-

Steam turbines are made in a variety of sizes ranging from small


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Non-Condensing (Back-Pressure) Steam Turbine

III. Reheat Turbines:-Reheat turbines are also used almost exclusively in

electrical power plants. In a reheat turbine, steam

flow exits from a high pressure section of the

turbine and is returned to the boiler where

additional superheat is added. The steam then goes

back into an intermediate pressure section of the

turbine and continues its expansion.

IV. Extracting Turbines:-Extracting type turbines are common in all

applications. In an extracting type turbine, steam is

released from various stages of the turbine, and


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used for industrial process needs or sent to boiler

feed water heaters to improve overall cycle

efficiency.

Extraction Steam Turbine

V. Induction Turbine:-Induction Turbine introduces low pressure steam at

an intermediate state to produce additional power.

b)According to Casing or Shaft Arrangement :-These arrangements include single casing, tandem compound and

cross compound turbines.


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I. Single casing units are the most basic style where a single

casing and shaft are coupled to a generator.

II. Tandem compound are used where two or more casings are

directly coupled together to drive a single generator.

III. A cross compound turbine arrangement features two or more

shafts not in line driving two or more generators that often

operate at different speeds. A cross compound turbine is

typically used for many large applications.

2.4 Principle of Operation:-

An ideal steam turbine is considered to be an isentropic process, orconstant entropy process, in which the entropy of the steam entering

the turbine is equal to the entropy of the steam leaving the turbine. No

steam turbine is truly isentropic, however, with typical isentropic

efficiencies ranging from 2090% based on the application of the

turbine. The interior of a turbine comprises several sets of blades, or

buckets as they are more commonly referred to. One set of stationary

blades is connected to the casing and one set of rotating blades is

connected to the shaft. The sets intermesh with certain minimum

clearances, with the size and configuration of sets varying to efficiently

exploit the expansion of steam at each stage.

2.5 Turbine Efficiency:-

To maximize turbine efficiency the steam is expanded, doing work, in anumber of stages. These stages are characterized by how the energy is

extracted from them and are known as either impulse or reaction

turbines. Most steam turbines use a mixture of the reaction and

impulse designs: each stage behaves as either one or the other, but the


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overall turbine uses both. Typically, higher pressure sections are

impulse type and lower pressure stages are reaction type.

Turbine Can be classified into two basic types:-

Impulse turbine:-

An impulse turbine has fixed nozzles that orient the steam flow into

high speed jets. These jets contain significant kinetic energy, which the

rotor blades, shaped like buckets, convert into shaft rotation as the

steam jet changes direction. A pressure drop occurs across only the

stationary blades, with a net increase in steam velocity across the

stage.

As the steam flows through the nozzle its pressure falls from inlet

pressure to the exit pressure (atmospheric pressure, or more usually,

the condenser vacuum). Due to this higher ratio of expansion of steam

in the nozzle the steam leaves the nozzle with a very high velocity. The

steam leaving the moving blades has a large portion of the maximum

velocity of the steam when leaving the nozzle. The loss of energy due to

this higher exit velocity is commonly called the carry over velocityorleaving loss.


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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 bythe rotor. Steam is directed onto the rotor by the fixed vanes of the

stator. It leaves the stator as a jet that fills the entire circumference of

the rotor. The steam then changes direction and increases its speed

relative to the speed of the blades. 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, reflecting the work performed in the driving of the rotor.

A typical reaction turbine is the Francis Turbine which is generally

arranged with a vertical shaft.


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Schematic diagram outlining the difference between an impulse and

a 50% reaction turbine


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2.6 Function of turbine stages:-

Each steam turbine stage consists of a stator ring containing

stationary flow guides, or nozzles, and a rotor which carries

rotating blades. These components are shown in Figure 5. Nozzles

and blades are both made to precise dimensions in order to

accurately provide the required geometry of the flow passages in

which the work of the steam is done. The nozzles and blades which

form these passages are precisely designed to achieve the desired

energy conversion in an efficient manner.

The blades convert the thermal energy of the steam into

mechanical force. The rotor then converts this force into torqueand mechanical work. This energy conversion is accompanied by a

prescribed decrease in steam pressure and steam temperature,

and by a corresponding increase in steam velocity, across the

stage, as the steam expands.

Turbine Stage Component


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There are two basic types of steam turbine stages: impulse stages

and reaction stages. Impulse stages are used mostly at the high

pressure inlet end of the turbine. In an impulse stage, the steam

accelerates as it expands through the nozzle row, as shown in

Figure 6. Little further expansion occurs within the rotating blade

passages. Energy is then transferred to the rotor by the change in

direction of the steam flow within the blade passages. The blades

exert a turning force on the steam, and this force drive the rotor.

Reaction blades are customarily used toward the low-pressure end

of the turbine. In a pure reaction stage, the blades and nozzles are

of similar (possibly identical) profile, and the steam expands

continuously as it passes through both the stationary and rotating

rows. This operation is shown in Figure 7. This permits a more

controlled expansion of the steam to be designed into the turbine.

2.7 Operation and Maintenance:-

When warming up a steam turbine for use, the main steam stopvalves (after the boiler) have a bypass line to allow superheated

steam to slowly bypass the valve and proceed to heat up the lines

in the system along with the steam turbine. Also, a turning gear is

engaged when there is no steam to the turbine to slowly rotate the

turbine to ensure even heating to prevent uneven expansion. After

first rotating the turbine by the turning gear, allowing time for the

rotor to assume a straight plane (no bowing), then the turning gear

is disengaged and steam is admitted to the turbine, first to theastern blades then to the ahead blades slowly rotating the turbine

at 1015 RPM (0.170.25 Hz) to slowly warm the turbine.

Any imbalance of the rotor can lead to vibration, which in extreme

cases can lead to a blade breaking away from the rotor at high


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velocity and being ejected directly through the casing. To minimize

risk it is essential that the turbine be very well balanced and turned

with dry steam - that is, superheated steam with minimal liquid

water content. If water gets into the steam and is blasted onto the

blades (moisture carry over), rapid impingement and erosion of

the blades can occur leading to imbalance and catastrophic failure.

Also, water entering the blades will result in the destruction of the

thrust bearing for the turbine shaft. To prevent this, along with

controls and baffles in the boilers to ensure high quality steam,

condensate drains are installed in the steam piping leading to the

turbine. Modern designs are sufficiently refined that problems

with turbines are rare and maintenance requirements are

relatively small.

2.8 Speed Regulation:-

The control of a turbine with a governor is essential, as turbines need to

be run up slowly, to prevent damage while some applications (such as

the generation of alternating current electricity) require precise speedcontrol. Uncontrolled acceleration of the turbine rotor can lead to an

over speed trip, which causes the nozzle valves that control the flow of

steam to the turbine to close. If this fails then the turbine may continue

accelerating until it breaks apart, often spectacularly. Turbines are

expensive to make, requiring precision manufacture and special quality

materials.

During normal operation in synchronization with the electricitynetwork, power plants are governed with a five percent droop speed

control. This means the full load speed is 100% and the no-load speed is

105%. This is required for the stable operation of the network without

hunting and drop-outs of power plants. Normally the changes in speed

are minor. Adjustments in power output are made by slowly raising the


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droop curve by increasing the spring pressure on a centrifugal

governor. Generally this is a basic system requirement for all power

plants because the older and newer plants have to be compatible in

response to the instantaneous changes in frequency without depending

on outside communication.


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CHAPTER-3

IMPULSE STEAM TURBINE

3.1 Introduction:-

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