Gas Turbine Class Presentation

Gas Turbine Principle and its major

components

Completed by : Mohammad Ibnul Hossain

Executive Engineer (Operation)Tongi 80(105) MW GT Power Station

Bangladesh Power Development BoardE-mail : [email protected]

What is Turbine ?A turbine is a rotary engine that extracts energy from a fluid /gas 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. Early turbine examples are windmills and water wheel.

Types of Gas Turbine :

1.Impulse

2.Reaction

P1 P2

V1 V2Here , P1 > P2v1> v2

Velocity-v, pressure-P

If Pressure decreases Velocity increases Kinetic Energy increases RMP increases

Change in pressure is done :

1) By Convergent Nozzle .

2) By Convergent Blade.

In Turbine ( Gas or Steam) : Impulse Turbine has Convergent Nozzle system and uniform blade system . Reaction Turbine has Convergent Blade system and uniform nozzle system

Impulse Turbine nozzle and blading arrangement

Conver- gent

Guide van Here :

P1 >P2V2> V1

Moving Blade Fixed Blade

ConstantArea

MovingBlade

P1 P2V1 V2

Impulse Turbine in Action

ConstantArea

Guide vane

Conver- gent

Nozzle Here

P1 > P2V2> V1

Reaction Turbine nozzle and blading arrangement

Fixed Blade MovingBlade

P1 P2V1 V2

Reaction Turbine in Action

A reaction turbine is moved by two main forces:

1.There is expansion of steam is there , pressure is decreasing so there is increase in kinetic energy by increasing velocity .

2. the push or impulse of the gas impinging upon the blades

Impulse Turbine create large amounts of Tangential thrust

Reaction turbines create large amounts of axial thrust, and so require the use

So the combination of impulse -reaction turbine is widely used .

Impulse –Reaction Turbine reduces both the tangential and axial stress To the Rotor

Impulse – Reaction Blade

The fixed blades are set in a reversed manner compared to the moving blades,

Fixed Blade Lower Part

Fixed Blade Upper Part Moving Blade

Lower Part Moving Blade Lower Part

Lower Part Impulse Turbine Upper Part Reaction Turbine

What is a Gas Turbine ? A gas turbine, also called a combustion turbine, is a type of internal combustion engine which has rotary impeller type thermal power mechanism with gas or liquid as working medium . It has an upstream rotating compressor coupled to a downstream turbine, and a combustion Chamber in-between.

The main components of a gas turbine :

1.Compressor 2.Combustion Chamber 3.Turbine .

Compressor

Combustion chamber

Turbine Generator

Air Inlet

Fuel Intel (Gas/Liquid fuel)

Exhaust

Compressor

Combustion chamber

Turbine

Air Inlet


Exhaust

Compressor

Combustion chamber

Turbine Generator

Air Inlet


Exhaust

Compressor

Combustion chamber

Turbine Generator

Compressor

Combustion chamber

Turbine Generator

Air Inlet


Exhaust

Compressor

Combustion chamber

Turbine

Air Inlet


Exhaust

Compressor

Combustion chamber

Turbine Generator

Air Inlet


Exhaust

A QUICK BROWN FOX JUMPES

OVER THE LAZY

DOG

When the turbine starting system is actuated, ambient air is drawnthrough the inlet plenum assembly >>>>>>>>> filtered, >>>then compressed in the 17th stage, axial flow compressorthe variable inlet guide vanes are in the closed position.When the speed corresponding to 95 per cent the variable inlet guide vane actuator energizes to open the inlet guide vanes (I.G.V.) to the normal turbine operating position

.

>>>Compressed air from the compressor flows into the annular space surrounding the fourteen combustion chambers>>>>from which it flows into the spaces between the outer combustion casings and the combustion liners.The fuel nozzles introduce the fuel into each of the fourteen combustion chambers where itmixes with the combustion air and is ignited by both (or one, which is sufficient) of the twospark plugs.>>>At the instant one or both of the two spark plugs equipped combustion chambers is ignited,the remaining combustion chambers are also ignited by crossfire tubes that connect thereaction zones of the combustion chambers

>>>The hot gases from the combustion chambers expand into the fourteen separate transition pieces attached to the aft end of the combustion chamber liners and flow towards the three stage turbine section of the machine.

>>>>Each stage consists of a row of fixed nozzles followed by a row of rotatable turbine buckets.In each nozzle row, the kinetic energy of the jet is increased with an associated pressure drop, and in each following row of moving buckets, a portion of the kinetic energy of the jet is absorbed as useful work on the turbine rotor.

After passing through the 3rd stage buckets, the exhaust gases are directed into the exhaust hood and diffuser

which contains a series of turning vanes to turn the gases from the axial direction to a radial direction

thereby minimizing exhaust hood losses. Then, the gases pass into the exhaust plenum.

When the turbine starting system is actuated, ambient air is drawnthrough the inlet plenum assembly >>>>>>>>> filtered, >>>then compressed in the 17th stage, axial flow compressorthe variable inlet guide vanes are in the closed position.When the speed corresponding to 95 per cent the variable inlet guide vane actuator energizes to open the inlet guide vanes (I.G.V.) to the normal turbine operating position

.

>>>Compressed air from the compressor flows into the annular space surrounding the fourteen combustion chambers>>>>from which it flows into the spaces between the outer combustion casings and the combustion liners.The fuel nozzles introduce the fuel into each of the fourteen combustion chambers where itmixes with the combustion air and is ignited by both (or one, which is sufficient) of the twospark plugs.>>>At the instant one or both of the two spark plugs equipped combustion chambers is ignited,the remaining combustion chambers are also ignited by crossfire tubes that connect thereaction zones of the combustion chambers

>>>The hot gases from the combustion chambers expand into the fourteen separate transition pieces attached to the aft end of the combustion chamber liners and flow towards the three stage turbine section of the machine.

>>>>Each stage consists of a row of fixed nozzles followed by a row of rotatable turbine buckets.In each nozzle row, the kinetic energy of the jet is increased with an associated pressure drop, and in each following row of moving buckets, a portion of the kinetic energy of the jet is absorbed as useful work on the turbine rotor.

After passing through the 3rd stage buckets, the exhaust gases are directed into the exhaust hood and diffuser

which contains a series of turning vanes to turn the gases from the axial direction to a radial direction

thereby minimizing exhaust hood losses. Then, the gases pass into the exhaust plenum.

.

.

1. Air-Intake System. inlet plenum assembly

2. Inlet Guide Van (IGV). variable inlet guide vanes

3. Compressor. compressor4. Combustion Chamber. combustion chambers combustion casings

Combustion liner spark plugscrossfire tubes transition pieces

5. Turbine-Rotor. three stage turbine

fixed nozzles rotatable turbine bucketsturbine rotor.

6. Exhaust- Plenum or Chimney.exhaust hood and diffuserexhaust plenumturning vanes

Schematic drawing of major components of gas turbine

Gas Turbine Auxiliaries

Air Inlet System

CompressorSection

Exhaust System

Turbine Section

Combustion Section

AirInlet

Compressor TurbineSection

CombustionSection

ExhaustSection

Air-Intake System :

Pre-filterPad

High Efficiency

FilterTo the Bell-

Mouth

Rain hood

Pre-Filter Pad

• Glass fiber pad with progressive density• Strong resilient design• Impregnated with gel-like adhesive• High dust holding capacity• Disposable

Coalescer Filter Pad

• Low Pressure Drop. • Economical in use. • Long Service Life. • Highly Efficient Midst

Eliminator

High Efficiency Filter

• High efficiency and dust holding capacity• Lightweight, easy to install• Low average operating resistance• Longer life than standard filters• Less filter change out

Air filtration is ensured by :• Rain hood placed on the front of the filter housing.• Bleed-heating device• Pre-filters installed in the first stage of supporting frames.• Coalescer pads installed against the front face of the high efficiency filter cells ; bothfilter elements placed in the second stage of supporting frames.

Variable Inlet Guide Vane

IGV

Variable Inlet Guide Vanes (IGVs)

IGVs are used to control the airflow through the compressor, in turn controlling the airflow through the entire machine.

The IGVs modulate during the start-up and acceleration of the gas turbine to rated speed, loading & unloading of the generator and deceleration of the gas turbine during shutdown.

Condition IGV opening

Startup - 2850 34⁰

2850- Loading 57⁰

Loading increases >> exhaust temperature increase

IGV opening increase

At Base Load to keep the exhaust temp. from 570⁰ C

84⁰

At Peak Load to keep the exhaust temp. not beyond to 575 ⁰ C (+5⁰ C)

84⁰

Compressor

•inlet guide vanes, •The axial-flow compressor section •consists of the compressor rotor and the inclosing casing.•the 17 stages of rotor and stator blading, • the exit guide vanes.

Compressor

Compressor Structure Inlet Guide Vane

Compressor Structure Compressor cylinder

Compressor cylinder has 3 parts:

•Forward casing ; •After casing •compressor outlet casing.

Compressor Structure

Forward casing After casing

Discharge casing


Compressor outlet casing


compressor structure

Compressor vane: IGV, stationary blade and EGV (Exhaust Guide vane)

IGV

EGV

StationaryBlade

Compressor StructureStationary Blade (lower half of the Cylinder )


Compressor moving blade

compressor rotor Compressor rotor is a drum

structure with 17 impellers (including a half shaft).17 impeller panels are tightly pulled by 16 long bolt pull rods to be integrated.


Working Principle : •air is confined to the space between the rotor and stator blading >>>>compressed in stages by a series of alternate rotating (rotor) and stationary (stator) airfoil shaped blades.

•The rotor blades supply the force needed to compress the air in each stage and the stator blades guide the air so that it enters in the following rotor stage at the proper angle.

•The compressed air exits through the compressor discharge casing to the combustion chambers.

•Air is extracted from the compressor for turbine cooling, for bearing sealing, and during start-up for pulsation control.

Combustion Section

Combustion Chamber

Main Components

1.Cap-Liner: 14 Nos 2.Primary Fuel Nozzle: 14 Nos 3.Secondary Fuel Nozzle: 14 Nos 4. Transition Piece (TP): 14 Nos

Combustion Chamber

Cross-fire

tube

SecondaryFlame

detector

Primary Flame

Detector

Some notable arrangements in combustion Chamber:

a)Primary Flame Detector in the Chamber 1,2,3,14b)Secondary Flame Detector in the chamber 1,2,3,14c) Primary , Secondary and Tertiary Fuel Connection

clock wise direction from manifold .

Introduction of combustion chamber structure

TRASTION PIECE

FLOW SLEEVE

Cap-liner

Primary Nozzle

Secondary and Tertiary Nozzle Tertiary Nozzle

Tertiary Nozzle

Working Principle : The combustion system is of the reverse-flow type with 14 combustion chambers This system also fuel nozzles, spark plug ignition system, flame detectors, and crossfire tubes.

Hot gases, generated from burning fuel in the combustion chambers, are used to drive the turbine.

High pressure air from the compressor discharge is directed around the transition pieces and into the combustion chambers liners. This air enters the combustion zone through metering holes for proper fuel combustion and through slots to cool the combustion liner. Fuel is supplied to each combustion chamber through a nozzle designed to disperse and mix the fuel with the proper amount of combustion air.

Combustion wrapper :The combustion wrapper forms a plenum in which the compressor discharge air flow is directed to the combustion chambers. Its secondary purpose is to act as a support for the combustion chamber assemblies .

Combustion chambers :Discharge air from the axial flow compressor flows into each combustion flow sleeve from the combustion wrapper. The air flows up-stream along the outside of the combustionliner toward the liner cap. This air enters the combustion chamber reaction zone through the fuel nozzle swirl tip, through metering holes in both the cap and liner and through combustion holes in the forward half of the liner.

The hot combustion gases from the reaction zone pass through >>> a thermal soaking zone and >>>> then into a dilution zone where additional air is mixed with the combustion gases.

Metering holes in the dilution zone allow the correct amount of air to enter and cool the gases to the desired temperature.

Along the length of the combustion liner and in the liner cap are openings whose function is to provide a film of air for cooling the walls of the liner and cap asshown in figure.

1-fuel gas duct 2-outer casing 3-flame cylinder 4- fish-scale cooling hole 5-igniter6-transition conic top 7-valve plate 8-fuel nozzle 9-swirler, 10- ejecting hole (for combustion ) 11-combustion area, 12-mixed ejecting hole (for cooling) 13-mixed area 14-annular chamber

FUEL NOZZLES (GAS)Description :•Each combustion chamber is equipped with a fuel nozzle that emits the metered amount required fuel into the combustion liner. •Fuel nozzles are used in gas turbines burning gas.•The fuel nozzle functions for proper distribution of the gas fuel into the reaction zone of the combustion•Liner which promotes uniform, rapid and complete combustion.

TRANSITION PIECESDescription :Transition pieces direct the hot gases from the liners to the turbine first stage nozzle. Thus,the first nozzle area is divided into 14 equal areas receiving the hot gas flow.

Spark plugs :Combustion is initiated by means of the discharge from two high-voltage, non-retractable spark plugs bolted to flanges on the combustion chambers and mounted in a primary zone cup in adjacent combustors (N° 11 and 12).

Flame detectors :During the starting sequence, it is essential that an indication of the presence or absence of flame be transmitted to the control system. For this reason, a flame monitoring system is used

consisting of eight sensors, each pair installed on four combustion chambers (n° 4 and 5, 10and 11 primary and secondary zone).

Actuated by the ionization of the gas inside it by getting ultra-violet emission from the flame.

Turbine Structure

• The requirements for turbine• To bear high temperature• To bear thermal stress and thermal

shock• To sustain heat alignment

Turbine Structure

• StatorTurbine stator consists of gas cylinder, stationary blade and support, force transmission system. Stators are stationary part of turbine.

Turbine Structure turbine cylinder

Turbine Structure

turbine structure turbine exhaust casing

5-6 turbine exhaust casing1- outer casing2- inner casing3- NO.3 bearing4- exhaust diffuser 5- exhaust frame6- exhaust casing support

Introduction of turbine structure• turbine blade and flow part

The high temp. gas from combustion casing enters the first stage nozzle through transition part. After expending in the nozzle, it enters the first-stage turbine moving blade.

Introduction of turbine structureThe first stage turbine nozzle consists of turbine stationary blade and inner and outer ring of nozzle. there are 18 section pieces and 2 stationary blades in each.there are 36 stationary blades in first-stage turbine nozzle.

Introduction of turbine structure

• the second stage nozzle and sealing of turbine

透平结构介绍


• the third stage nozzle and sealing of turbine


turbine retainer

Introduction of turbine structure In second or third stage of

turbine retainer inner side, we use bee-nest shape structure to enhance sealing effect.

turbine rotor


Introduction of turbine structureturbine moving blades

There are 3 stages turbine moving blade with fir tree shape of each one’s root. The blade connects with mortise groove of vane wheel axially and tightly locked by bolts in case of moving out axially.

透平结构介绍

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Gas Turbine Class Presentation

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