Gas Turbine: Basics Reviewed by
Muhammad Salman Bilal BSEE,MSEE,MSEM
Introduction Purpose of the plant
Gas turbine technology
Main components, system configuration History, energetic considerations, description
Turbogenerator
Technical description, mechanical and electrical systems
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Introduction Purpose of the plant Main components, system configuration
Gas turbine technology
History, energetic considerations, description
Turbogenerator (Solar Titan)
Technical description, mechanical and electrical systems
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Main points Basically we apply the co-generation concept in order to produce heat energy (steam) from one side and electrical energy from the other. The electrical energy is also such an important argument where a reliable network is necessary (chemical, textile, 3rd world,…) Network voltage failure Other particular situations Advantages Better efficiency in the energy production. Better quality of the energy (self made = more reliability, flexibility…)
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Main components The system is basically composed of : Turbo generator Produce electric energy and (or) thermal energy Medium voltage (MV) station (accessory) Ensures the electrical power connection between the turbo generator, the plant and the network Boiler (accessory) Convert the thermal energy in steam Diesel engine generator (accessory) Produce electric energy Gas Compressor (accessory Ener project) Increase and stabilize the gas pressure when it drops
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MV plant Diesel engine
Gas turbine
Electric Generator
Turbogenerator auxiliary System (LV)
Electric Generator (11000 Vac)
Main plant
Main package supply
MV station
Air compressor ………
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Introduction Purpose of the plant
Gas turbine technology
Main components, system configuration Energetic considerations, description
Turbogenerator (Solar Titan)
Technical description, mechanical and electrical systems
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Main components The gas turbine is composed of 3 main parts : The compressor Increases the pressure of incoming comburant air.
The combustion chamber The mixture fuel /air is burned and gas temperature increased.
The power turbine Which converts the thermal and kinetic energy of the burned gases to mechanical energy, avalaible on the gas turbine rotor shaft.
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The gas turbine can be compared (continous cycle) with a four stroke engine (alternating cycle):
exhaust
Air inlet compression
combustion 9
ďƒ˜ Gas turbine power flow Exhaust gas
Power turbine
Combustion chamber
Compressor air
Gearbox
Generator
Fuel
Chemical power
Thermal power
Mechanical power
Electrical power
Global efficiency 10
The compressor stator 1
rotor 3
2
ω
Stage = stator + rotor Through the stages of the compressor the gas decelerates and the pressure increases. In the compressor, the mechanical energy is converted in potential energy, increasing the gas pressure.
u
P Pressure evolution 11
The combustion chamber The combustion chamber shape is annular. There the mixture fuel/air is burned at constant pressure. Because of the high combustion temperature (~2000 °C), the gas temperature is reduced with air coming from the compressor (dilution air) to obtain an admissible temperature of the metallic parts (turbine blades and combustion chamber) → 800-1200 °C
Fuel inlet
Dilution air holes
Combustion chamber 12
The combustion chamber Ignition torch
Primary air Air from compressor
Tertiary air Injector
Injector nose
Secondary air
combustion chamber section 13
Power turbine Stage = rotor + stator rotor
stator
Through the stages of the power turbine the gas accelerates and the pressure decreases.
1
3
2
ω
u
In the turbine, the potential energy of the gas is transformed to mechanical energy. The total aerodynamic force acting on the rotor blades is transferred to the rotor shaft, which rotates at the speed ω .
P Pressure evolution 14
Power turbine
Turbine blades Through the Cooling air stages of the power turbine the gas is accelerated and energy trasferred to the rotor blades, which rotate the shaft. The power is finally trasferred to the compressor and the electrical generator.
Power turbine blades (T130)
Combustion chamber
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Introduction Purpose of the plant
Gas turbine technology
Main components, system configuration History, energetic considerations, description
Turbogenerator Technical description, mechanical and electrical systems
Diesel generators (800 kVA, 1400 kVA) Air compressor
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Turbogenerator group Package design Main components :
Gas turbine Gear box Generator
Main circuits :
Electric start system Lube oil system Gas fuel system Liquid fuel system Air system
The electric system :
Control room panels Field bus modules 17
Front view (Titan)
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Top view (Titan)
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Rear view (Titan)
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General view (example)
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Turbine type : - single shaft - axial flow design
1 2 3 4
1) Gearbox assembly 2) Air inlet assembly 3) Axial flow compressor 4) Combustor assembly 5) Turbine assembly 6) Exhaust diffuser and bellows 7) Supporting frame
5 6
7
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Titan 130 –20501 gas turbine engine specifications Description
COMPRESSOR Type Number of stages Compression ratio Speed COMBUSTION CHAMBER Type Ignition Number of fuel injectors TURBINE Type Number of stages
Data Axial 14 17 : 1 11197 rpm Annular Torch 14
Axial 3 23
Titan 130 Air inlet duct
The compressor
Through the air inlet duct, pre-filtered ambient air is drawn into the axial compressor and then used for combustion process.
Back view (from gearbox)
Lateral view 24
Titan 130 The compressor
Compressor case assembly 1) 2) 3) 4)
Compressor air inlet flange Forward compressor case Aft compressor case Variable guide vanes
4
3
2 1
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Titan 130 The compressor
Variable guide vane system The variable - position guide vane system (IGV) avoids compressor surge during starting and transient operation. The angular position of the inlet guide vanes And stator vanes of the first six compressor stages are in function of gas turbine speed for start-up and acceleration. Increasing speed will cause the guide vanes to move from close position (- 45 째) to full open position (5째). The guide vane system uses an electric motor-driven roller screw actuator with position feedback. The variable guide vane system is controlled by: - Guide vane actuator motor (command : 4-20 mA) - Guide vane actuator resolver (feedback : 4-20 mA) - Guide vane actuator controller
3 2 1
1) Variable guide vane (stator) 2) Rotor blades 3) Forward compressor case 26
Titan 130 Combustor assembly The combustor assembly is bolted to the aft end of the compressor diffuser assembly. The main components are: 1) 2) 3) 4) 5)
Fuel and air manifolds Fuel injectors Combustor liner assembly Torch igniter assembly Bleed air valve assembly
3 2
1
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Titan 130 Combustor assembly Bleed air system
The compressor bleed air system prevents compressor surge, reducing back pressure during start sequence and transient operations. The compressor air is bled from the combustor housing directly to the exhaust diffuser. The system is composed of : 1) Bleed air pipe 2) Butterfly valve 3) Electrical actuator 4) Clamp
4 1 2 3 28
Titan 130 Combustor assembly Bleed air system
Bleed air pipe
Electrical actuator
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Titan 130 Combustor assembly The turbine fuel supply system is composed of : Fuel supply system Three tubular manifolds, which encircle the combustor housing. (1)-Main gas supply (larger in diameter), (2)-Pilot gas supply, (3)-Atomization air (4)-14 liquid fuel injectors, which receive air and fuel from the manifolds.
4
3
1 2 30
Titan 130 Combustor assembly Torch The torch igniter assembly is installed on the bottom igniter of the combustorassembly assembly (7 o’clock position). During start cycle, a separate fuel line supplies liquid fuel to the torch which is lit by an igniter spark. The torch ignites the fuel / air mixture entering the combustor chamber through the injectors. When continous burning is recognized from the control system, the torch is extinguished.
Spark Liquid drain outlet Fuel supply inlet
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Titan 130 The power turbine is located aft of the combustor assembly. The power turbine assembly includes first, second and third stage turbine rotor’s disc and turbine nozzles. First and second stages of blades are cooled with bleed air. Around the third stage turbine nozzles 12 thermocouples that measure the T5 temperature are mounted.
Power turbine & exhaust diffuser 3
4
2 1) 2) 3) 4)
Power turbine assembly T5 thermocouples PCD air for cooling T5 ring Exhaust diffuser
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Titan 130 Gearbox General description The main function of the gearbox is to reduce the drive speed from the turbine to the generator. The generator speed is 1500 rpm for 50 HZ service. The gearbox is therefore located between the turbine and the generator. It has an epicyclic star-gear design. The gearbox is also equipped with two starter motors (used for turbine start) and is used to drive the mechanic oil pump (for the main oil circuit). These are the auxiliary functions of the gearbox. Two speed pick-ups (1) (for speed control and protection use) are also mounted on the gearbox.
1
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Titan 130 Gearbox Technical data Description TYPE MANUFACTURER RATING Transmitted Power Input Speed Output Speed Gear Ratio LUBRICATION (nom.val) Pressure Temperature GEARBOX WEIGHT Total weight
Data epicyclical ALLEN GEARS 22200 HP (16561 Kw) 11197 rpm 1500 rpm 7,465 1.7 – 3 barg 43 – 74 °C 6042 Kg 34
Titan 130 Gearbox Main reduction drive Primary stage 1) Central sun wheel 2) Star wheels (3) Secondary stage 3) Star wheel shaft 4) Internal gear ring 5) Star carrier 6) Low shaft speed
HIGH SPEED (input)
LOW SPEED (output)
Power flow 35
Titan 130 Gearbox Auxiliary drives 1) 2) 3) 4)
Starter motor drives Oil pump drive Gearbox output shaft Speed pick-up 4
1 2 4
1
3
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Titan 130 Generator General description •The generator converts mechanical power of gas turbine to electrical power. •The shaft of the generator is coupled to the slow speed shaft of the gearbox (1500 rpm). •The machine consists of a main generator, stator and rotor (internal-pole machine) and an exciter (external-pole machine). •The generator is air cooled, with two fans mounted on to the rotor shaft. •The main terminal box is mounted on the top of the generator. It contains the winding ends, the voltage and current trasformers for control, measurement and protection use. •An auxiliary box, also on the top of the generator, •contains low voltage terminals. 37
Titan 130 Generator Electric schematic
1) 2) 3)
Stator Magnet wheel (rotor) Rectifier bridge
4) 5) 6)
Exciter armature Exciter coil Automatic voltage regulator(AVR) 38
Titan 130 Generator Generator data Manufacturer : Type : Nominal power : Frequency : Voltage : Power factor : Speed :
Alstom( Leroy Somer) synchronous, 4 poles 17000 kVA 50 Hz 11000 V 0.8 1500 rpm
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