industrial gas turbine (air cooling & sealing sys) 5th
TRANSCRIPT
INDUSTRIAL GAS TURBINE
Unit 305 – Gas Turbine Cooling System
Topic:
Cooling Air and Sealing Air system
Page 2
Aim and Objective
Aim:
To demonstrate the knowledge on the function of industrial gas turbine
cooling system.
Objective
At the end of the lesson, you should be able to:
Describe the purpose and operation of cooling air system.
Decsribe the function of sealing air system.
Analyze the uses of the cooling air system of gas turbine engine.
Page 3
Type of cooling system
3 Types of Cooling system fitted for Gas Turbine:
Cooling Oil System
Cooling Air System
Cooling Water System
Page 4
Why Required Cooling and Sealing Air System?
The system have several function, which are:
To ensure that certain parts of the engine and accessories does not
absorb heat from the gas strem.
Provides sealing for bearing chambers and flow paths.
Balance and reduce Thermal load through out the engine thrust range.
Perform for the safe and efficient of the gas turbine operation.
To control the temperature of compressor shaft and discs.
How to achieved those function?
Controll the amount of air from compressors to flow around the
components.
Page 5
Turbine Cooling
Why turbine blade and vanes need cooling?
High thermal efficiency of gas turbine is depend upon the high
temperature entry to turbine section.
However, this can be limited by turbine blade and nozzle guide vanes
material.
By providing continuous cooling, these component capable to exceed
their melting point without affecting the blade and vane integrity.
Turbine vanes and blade life are not only depends on their form but also
on the method of cooling.
Page 6
The compartments that required Air Cooling are:
Combustor
Turbine
Bearing Chambers
Gas Turbine Accessories
Page 7
Nozzle Guide Vane and Turbine Blade Arrangement
H.P
Cooling Air
L.P
Cooling Air
Turbine
Blade
Pre-swirl
Nozzle
Nozzle
Guide Vane
Pre-swirl Nozzle
It reduce the temperature and
pressure of the cooling air fed to
the disc for blade cooling.
Nozzle Guide Vane
It assist efficient entry of the air
into a rotating cooling passages.
Page 8
Latest Turbine Blade Design for Cooling…
Quintuple Pass Blade
Multi-feed internal cooling with extensive film
cooling.
Page 9
Bearing Chamber Cooling
Air cooling at bearing chambers is not normally necessary since L.O sys
already adequate for cooling purposes.
Good practice to have a double skinned bearing housing with cooling air
is fed into the intermediate space.
Page 10
Function of Sealing Air System
What are the purpose of sealing air?
To prevent oil leakage from engine bearing chambers.
To control cooling airflows of the main stream gas to the turbine disc
cavities.
Type of sealing method:
Labyrinth Seals.
Ring Seals.
Hydraulic Seals.
Carbon Seals.
Brush Seals.
Hot Gas Ingestion.
Page 11
Sealing Air Method - Labarith Seal
This type of seal used:
To retain oil in bearing chamber.
As a metering device to control internal airflows.
To prevent oil leakage.
To induces a positive pressure in assists the oil return system.
Fluid and Abradable lined
Labyrinth seal
Continuous Groove Inter-
stage Labyrinth seal
Thread Type Labyrinth
Oil seal
Page 12
Sealing Air Method - Ring Seal
This type of seal used:
For bearing chamber sealing, except hot areas.
Ring type oil seal
Page 13
Sealing Air Method – Hydraulic Seal
This type of seal used:
To seal bearing chamber, fitted between two rotating members.
Inter-shaft Hydraulic seal
Page 14
Sealing Air Method – Carbon Seal
This type of seal used:
To maintain contact between the carbon and the collar.
Carbon seal
Page 15
Sealing Air Method – Brush Seal
This type of seal has advantage of:
Withstanding radial rubs without increasing leakage.
Brush seal
Page 16
Sealing Air Method – Hot Gas Ingestion
This type of seal used:
To prevent the ingestion of hot
mainstream gas into the turbine
disc cavities.
Page 17
Component of Cooling & Sealing Air System
It comprised of:
Air actuated compressor bleed valve.
Solenoid actuated air control valve.
Air filter.
Various fitting (piping & internal passageways).
Page 18
Operation of Cooling & Sealing Air System
Page 19
Recap
Describe the purpose of cooling air system
(including the turbine blade design for cooling
and their arrangement).
Decsribe the function of sealing air system
including their types.
Explain the operation of cooling and sealing air
system of gas turbine engine analyze it using the
flow diagram.
Group Work activity…
Page 20
Overview of Next Lesson…
Section ‘E’ – Cooling System
Topic: Cooling Water System
Thank you for your Attention