6. • Brayton cycle is the ideal cycle for gas-turbine
T
P= Const.
1
2
3
4
QH
QL
1-2
isentropic compression (in compressor)
2-3
const. pressure heat-addition (in combustion
chamber)
3-4
isentropic expansion (in turbine)
4-1
const. pressure heat rejection (exhaust)
s
7. Combustion
chamber
Fan – low pressure
compressor
6 stage high
pressure
compressor
8 stage
intermediate
pressure
compressor
8.
9. Compressor
Compressor used in gas turbine is Axial –Flow type
Axial-flow compressors are dynamic rotating
compressors that use arrays of fan-like airfoils to
progressively compress the working fluid
10. Axial
Compressor
Modern Compressor
Designs are
Extremely Efficient
gas turbine
performance rating
depends greatly on
the compressor
efficiency
High Performance
Made Possible by
Advanced
Aerodynamics,
Coatings, and Small
Blade Tip Clearances
Even Small Amounts
of Deposits on
Compressor Blades
May Cause Large
Performance Losses
Inlet Guide Vane
Rotor Blades(rotating)
Stator Vanes (fixed to case)
13. Combustion air, with the help of swirler vanes, flows in around the fuel nozzle and
mixes with the fuel. This air is called primary air and represents approximately 25
percent of total air ingested by the engine. The fuel-air mixture by weight is roughly
15 parts of air to 1 part of fuel. The remaining 75 percent of the air is used to form an
air blanket around the burning gases and to lower the temperature.
14. 1
2
3 5
7
The Turbine
Two Basic Types - Radial and Axial
Almost all industrial Gas Turbines use axial flow
turbines
Like the Compressor, Turbine Expansion
Takes Place in “Stages”
a row of stationary blades (nozzles)
followed by a row of moving blades
= one stage.
15. Axial
Turbine
Two Stage Axial Turbine
rotation
Rotor Blade
Nozzle
rotation
Rotor Blade
Nozzle
First Stage Turbine Nozzle Sees the Hottest Temperatures
Referred to as TIT (Turbine Inlet Temperature) or TRIT (Turbine Rotor
Inlet Temperature)
Modern engines run TRIT as high as 1500C (some even higher)
16. The axial flow turbine consists of stages, each
made up primarily of a set of stationary vanes
followed by a row of rotating blades,
Typically modern aircraft gas turbine blades
have both impulse and reaction sections.
17. Exhaust System
Must perform four function
Reduce noise to the atmosphere
Hot gases away from personnel
Minimize backpressure to gas turbines
Mechanically well during extreme
temperature changes.
18. Types
Shaft power gas turbines: is a gas turbine
whose goal is mainly to deliver shaft power
Jet engine gas turbines: is a turbine whose
goal is mainly to deliver thrust
27. Turbine Performance is changed by anything
that affects the density and mass flow of the air
intake to the compressor
Ref.
GE3567H
28. The air density Reduces as the site elevation
increase
Result airflow and output decrease
29.
30. Turbine exhaust Temp is limited by material
condition
As we get higher efficiency when we increase in
firing temp. result in increase in exhaust temp
Till now maximum exhaust temp limit is 582 c
31. Efficiency at Part Load Operation
Gas Turbine Thermal Efficiency / ref versus Load P/Pmax
(Typical, for 3 arbitrarily selected industrial engines)
110
100
90
80
70
60
50
50 60 70 80 90 100
Load (%)
Rel.ThermalEfficiency(%)
32.
33. Heated fuel result in higher turbine efficiency
due to the reduced fuel flow required to raise
the total gas temp to firing temp.
The source of heat for the fuel typically is IP
feedwater
Since use of this energy in the gas turbine fuel
heating system is thermodynamically
advantageous
Combined efficiency is improved by
approximately 0.6%
34. Base Load, Peak Load and Stand-By Units
• Engine Life depends on Firing Temperature
(and number of starts*)
– Thus, a peak load unit can be fired at higher
temperatures without any design changes
– Higher Firing Temperature means more
power, but shorter engine life.
* According to some manufacturers
35. Very high power-to-weight ratio, compared to
reciprocating engines;
Moves in one direction only, with far less
vibration than a reciprocating engine.
Fewer moving parts than reciprocating engines.
Waste heat is dissipated almost entirely in the
exhaust. This results in a high temperature
exhaust stream that is very usable for boiling
water in a combined cycle, or for cogeneration.
36. Low operating pressures.
High operation speeds.
Low lubricating oil cost and consumption.
Can run on a wide variety of fuels.
37. Cost is much greater than for a similar-sized
reciprocating engine since the materials must
be stronger and more heat resistant. Machining
operations are also more complex
Usually less efficient than reciprocating engines,
especially at idle
Longer start up than reciprocating engines
Delayed response to changes in power settings.
38. • Caterpillar Power
Generation Systems
• Electro-Motive Diesel Inc.
• GE Gas Engines
• Hyundai Heavy Industries Co. Ltd
Mitsubishi Heavy Industries Ltd.
• MWM
Rolls-Royce
Hitachi Ltd.
Toshiba Ltd.
The engine extracts chemical energy from fuel and converts it to mechanical energyusing the gaseous energy of the working fluid (air) to drive the engine and propeller
In 1993 General Motors introduced the first commercial gas turbine powered hybrid vehicle—as a limited production run of the EV-1 series hybrid.Brescia Italy is using serial hybrid buses powered by microturbines on routes through the historical sections of the cityThe MTT Turbine SUPERBIKE appeared in 2000 (hence the designation of Y2K Superbike by MTT) Rolls-Royce Allison model 250 turboshaft engine, producing about 283 kW (380 bhp). Speed-tested to 365 km/h the most recent incarnation being Bombardier's JetTrain.
In every 2 min. an aircraft powered by GE technology lands in one of the top 4 airports in IndiaIn 2011 687 units are ordered for 28831 MW
these disadvantages explain why road vehicles, which are smaller, cheaper and follow a less regular pattern of use than tanks, helicopters, large boats and so on, do not use gas turbineengines, regardless of the size and power advantages imminently available.
