Turbine & Aux-Final - Copy

8/8/2019 Turbine & Aux-Final - Copy

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TOTAL-4260MWSTAGES:-

STAGE1-6X210MW

STAGE2-2X500MWSTAGE3-2X500MW

STAGE4-2X500MW


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COAL USED-BITUMILOUS

CARBON CONTENT-75% TO 85%

CALAROFIC VALUE-7000K CAL/KG.

SIZE WHEN FEED IN FURNACE-200 MESH(200HOLES PER INCH SQUARE)


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GENERATOREXCI

TER

1 2 34 5 6

CRH

CONDEN

FROM RH

LPBYPASS

TO LP HEATERS

HPT -

IPT LPT

2X6

TURBINE LAYOUT


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Turbine is anengine thatconverts energy of

fluid intomechanical energy

The steam turbineis steam driven

rotary engine.


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The first turbine was madeby Hero of Alexandria in thesecond century

In the end of XVIII century theIndustrial Revolution began (in1770 first reciprocating pistonsteam engine invented byThomas Newcomen andinvented by James Wattstarted its work)

The first steam turbines wereconstructed in 1883 by DrGustaf de Laval and in 1884 bysir Charles Parsons

In1896 Charles Curtis receiveda patent on impulse turbine

In 1910 was created radialturbine (Ljungstrm)
http://www.history.rochester.edu/steam/parsons/Fig_4.GIF


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Impulse stage wholepressure drop in nozzle(whole enthalpy drop ischanged into kineticenergy in the nozzle)

Reaction stage pressuredrop both in stationaryblades and in rotary

blades (enthalpy dropchanged into kineticenergy both in stationaryblades and in the movingblades in rotor)


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a) way of energyconversion

- impulse turbines

- reaction turbines


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b) flow direction

- axial- radial

c) number ofstages

- single stage

- multi-stage


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d) rotational speed

- regular

- low-speed

- high-speede) inlet steam pressure

- high pressure (p>6,5MPa)

- intermediatepressure(2,5MPa


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f) way of energyutilisation

- condensing

- extraction

- back-pressure


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CASING

ROTOR

BLADES

SEALING SYSTEM

STOP & CONTROL VALVES

COUPLINGS & BEARINGS

BARRING GEAR


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HP Turbine Casing:

Outer casing: a barrel-type without axial or radial flange whichprevents mass accumulation with high thermal stresses.

Barrel-type casing permits quick startup and high rate of changeof load.

The inner casing : Cylindrical , Axially split.

The inner casing is attached in the horizontal and vertical planesin the barrel casing so that it can freely expand radially in all

directions and axially from a fixed point (HP-inlet side).


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The casing of the IP turbine is split horizontally and is ofdouble-shell construction.

Both are axially split and a double flow inner casing issupported in the outer casing and carries the guideblades.

Provides opposed double flow in the two blade sectionsand compensates axial thrust.

Steam after reheating enters the inner casing from Top &Bottom.

Outer casing is subjected to only low pressure and lowtemperature conditions


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The LP turbine casing consists of a double flow unit andhas a triple shell welded casing.

The shells are axially split and of rigid weldedconstruction.

The inner shell taking the first rows of guide blades, isattached in the middle shell.

Independent of the outer shell, the middle shell, is

supported at four points on longitudinal beams. Steam admitted to the LP turbine from the IP turbine

flows into the inner casing from both sides.


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Purpose: To take care of thermal expansions andcontractions of the machine during thermal cycling.

The fixed points of the turbine are as follows:

The bearing housing between the IP and LP turbines.The rear bearing housing of the IP turbine.

The longitudinal beam of the I.P turbine.

The thrust bearing in rear bearing casing of H.P turbine.


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HP Rotor:

The HP rotor is machined from a single Cr-Mo-V steel forgingwith integral discs.

In all the moving wheels, balancing holes are machined toreduce the pressure difference across them, which results inreduction of axial thrust.

First stage has integral shrouds while other rows haveshroudings, rivetted to the blades are periphery.


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The IP rotor has seven discs integrally forgedwith rotor while last four discs are shrunk fit.

The shaft is made of high creep resisting Cr-Mo-V

steel forging while the shrunk fit disc aremachined from high strength nickel steelforgings.

Except the last two wheels, all other wheelshave shrouding riveted at the tip of the blades.To adjust the frequency of the moving blades,lashing wires have been provided in some stages.


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The LP rotor consists of shrunk fit discs a shaft.

The shaft is a forging of Cr-Mo-V steel while the discs areof high strength nickel steel forgings.

Blades are secured to the respective discs by riveted forkroot fastening.

In all the stages lashing wires are providing to adjust the

frequency of blades. In the last two rows satellite stripsare provided at the leading edges of the blades to protectthem against wet steam erosion.


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Most costly element of turbine

Blades fixed in stationary part are called guideblades/nozzles and those fitted in moving part

are called rotating/working blades.

Blades have three main parts

Aerofoil: working part

RootShrouds

shroud are used to prevent steam leakage & toguide steam to next set of moving blades.


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Three types of root arrangements are commonly used. They are (1) T-roots: for small blades; (2) Fir Tree or serrated roots - for longerblades; (3) Fork and Pin root: for longer blades shrunk on disc typerotors.

Integral shroud for are used for shorter blades and shrunk fitting for

larger blades.

Lacing wires are also used to dampen the vibration and to matchfrequencies in the longer blades.

Since in the reaction type machine the pressure drop also occurs across

the moving blades it is necessary to provide effective sealing at theblade tips.


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Turbine Blades


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Large power achieved by relatively small sizeHigh efficiency

Simple design

High revolution


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SECTIONAL ARRANGEMENT OFCONVENTIONAL 3-CYLINDER

TURBINE


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LP TURBINE


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CONDENSER
http://en.wikipedia.org/wiki/Image:Dores-Cond-diag1.png


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REAR WATER

CHAMBER

REAR

WATER

BOX

OUTLET

NOZZLE

FRONT

WATER

BOX

INLET

NOZZLE

LOWER DOME WALL

UPPER DOME WALL

SUPPORT

PLATE

CONDENSER

SOPPORTS

BOTTOM PLATE

DOME INTERNAL

STIFFENING

FRONT WATER CHAMBER


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STEAM EJECTORS

Motive

steam

Non condensibile gases and

water vapour from condenser

Convergent

divergent

diffuser

Nozzle

Discha

rgetoc o

ndenser


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De Aerator


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CMP C

GB

C BP

Turb

TDBFP - Arrangement


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Feed Water Heater


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Turbine & Aux-Final - Copy

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