how gas turbines work

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How does it work? How does it work? How does it work? This is a Gas Turbine. This is a Gas Turbine. This is a Gas Turbine.

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How Gas Turbines Work

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Page 1: How Gas Turbines Work

General Questions to All Manufacturers

How does it work?How does it work?How does it work?

This is a Gas Turbine.This is a Gas Turbine.This is a Gas Turbine.

Page 2: How Gas Turbines Work

General Questions to All ManufacturersContentsContents

• How Does it Work?

• Gas Turbine Components

• Gas Turbine Performance

• Gas Turbine Applications

Page 3: How Gas Turbines Work

General Questions to All Manufacturers

1) Compression

2) Combustion

3)Expansion (Turbine)

Output Shaft Power

Output Shaft Power Two ShaftTurbine EngineTwo ShaftTwo ShaftTurbine EngineTurbine Engine

Single ShaftTurbine EngineSingle ShaftSingle ShaftTurbine EngineTurbine Engine

Page 4: How Gas Turbines Work

General Questions to All ManufacturersThe “Simple Cycle”The “Simple Cycle”

• Compressor Pumps Air into Combustion Chamber

• Fuel in Gaseous or Liquid Spray Form Injected into Combustion Chamber and Burned

• Continuously Expanding Combustion Products Directed Through Stationary Airfoils

− react against the blades of a turbine wheel, causing the shaft to turn, driving the compressor

• Remaining High Energy Gas Can be Used

− expansion across a nozzle (propulsion)− expansion across another turbine stage (shaft power)

Page 5: How Gas Turbines Work

General Questions to All Manufacturers

Simple Cycle Gas Turbines Simple Cycle Gas Turbines as Aircraft Engines and Land Based Prime Moversas Aircraft Engines and Land Based Prime Movers

COMPRESSOR TURBINE

COMBUSTOR

FUEL

AIR IN

EXHAUST GAS OUT

POWER

OUTPUT

COMPRESSOR TURBINE

COMBUSTORFUEL

AIR IN

EXHAUST GAS OUT

NOZZLE

THRUST

HIGH VELOCITYJET

POWERTURBINE

Page 6: How Gas Turbines Work

General Questions to All ManufacturersCommonalitiesCommonalities

• Use One or Multiple Compressors• Have Combustor• Use One or Multiple Turbines to Drive

Compressor(s)• Aeroengines Generate Propulsion Either by a

Hot Gas Jet, Driven Fan or Propeller, or Combination

• Industrial Gas Turbines Generate Mechanical Power Using Turbine Driven by Hot Gas

Page 7: How Gas Turbines Work

General Questions to All Manufacturers

12

3 57

Brayton Brayton Cycle (Simple Cycle Gas Turbine )Cycle (Simple Cycle Gas Turbine )Ve

loci

tyTe

mpe

ratu

rePr

essu

re

Station

1 2 3 5 7

Flame Temperature

Page 8: How Gas Turbines Work

General Questions to All Manufacturers

Gas Turbine ComponentsGas Turbine Components

Page 9: How Gas Turbines Work

General Questions to All ManufacturersEngine External Components

Industrial Engine on SkidIndustrial Engine on Skid

Page 10: How Gas Turbines Work

General Questions to All Manufacturers

12

3 57

The Compressor SectionThe Compressor Section

• Axial or Centrifugal Flow• Axial Flow

higher efficiency higher flow more stages

• Centrifugal Compressors on smaller engines and some mid-size industrial engines less stages rugged simple

• Driven by the Turbine on a Common Shaft

• Compressor Uses 2/3 of the Fuel Energy That’s why keeping it

efficient (read CLEAN) is so important!

Page 11: How Gas Turbines Work

General Questions to All ManufacturersAxial CompressorAxial Compressor

• Airflow Parallel to Rotor Axis

• Air Compressed in “Stages” row of moving blades

followed by row of stationary blades(stators) is one stage.♦ Moving blades impart

kinetic energy♦ stators recover the

kinetic energy as pressure and redirect the flow to the next stage at the optimum angle

Page 12: How Gas Turbines Work

General Questions to All ManufacturersAxial CompressorAxial 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)

Page 13: How Gas Turbines Work

General Questions to All ManufacturersThe CombustorThe Combustor

• Also Known as the “Burner”• Must be Compact and Provide “Even Temperature

Distribution of Hot Gases to the Turbine• Three Basic Configurations:

− annular− can− can-annular

12

3 57

Page 14: How Gas Turbines Work

General Questions to All ManufacturersAnnular CombustorAnnular Combustor

Injector

CombustorLiner (requires intensive cooling)

Shaft

Page 15: How Gas Turbines Work

General Questions to All ManufacturersCombustor DesignCombustor Design

• Annular− Donut shaped, single,

continuous chamber that encircles the turbine

• Can-annular− multiple, single burners

(“cans”) evenly spaced around the rotor shaft

• Silo or Can− One or more

combustion chambersmounted externalto the gas turbine body

Page 16: How Gas Turbines Work

General Questions to All ManufacturersFuel InjectorFuel Injector

• Used to introduce fuel into the combustion chamber.

• Can be for single or dual fuel

• Fuel can be mixed with combustion air either…− in the combustor

(standard combustion system)

− pre-mixed prior to entering combustor( lean pre-mix, DLN (dry-low-Nox), DLE (dry low emissions), (SoLoNOx)

Pre-Mix Barrel

Solar Mars Injector

Standard vs SoloNOx

Standard injector

Dry-Low-NOx injector

Page 17: How Gas Turbines Work

General Questions to All Manufacturers

12

3 57

The TurbineThe 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.

Page 18: How Gas Turbines Work

General Questions to All ManufacturersAxial TurbineAxial Turbine

Turbine Nozzle SegmentTwo Stage Axial Turbine

Nozzle

Rotor Blade

Nozzle

Rotor Blade

rotation

rotation

• First Stage Turbine Nozzle Sees the Hottest Temperatures

− Referred to as TIT (Turbine Inlet Temperature) or TRIT (Turbine RotorInlet Temperature)

− Modern engines run TRIT as high as 2200 F (some even higher)

Page 19: How Gas Turbines Work

General Questions to All ManufacturersBlade Cooling SchemesBlade Cooling Schemes

COOLING AIR INLET

HOTGASFLOW

HOT GAS FLOW

COOLING AIR

SHOWER HEADFILM HOLES

Film CoolingConvection Cooling

Page 20: How Gas Turbines Work

General Questions to All ManufacturersTemperature DefinitionTemperature Definition

TIT TRIT T5

Combustor

1st Nozzle1st Rotor 1st PT Nozzle

Cooling Air Flows

All temperatures are considered total.

Page 21: How Gas Turbines Work

General Questions to All Manufacturers

Gas Turbine Performance Characteristics

Gas Turbine Gas Turbine Performance CharacteristicsPerformance Characteristics

Page 22: How Gas Turbines Work

General Questions to All Manufacturers

Gas Turbine Performance vs. Ambient Temperature

Gas Turbine Gas Turbine Performance vs. Ambient TemperaturePerformance vs. Ambient Temperature

0100020003000400050006000700080009000

10000

-20 -10 0 10 20 30 40 50

T amb (deg C)

Pow

er, H

eat r

ate

HPHR

Page 23: How Gas Turbines Work

General Questions to All Manufacturers

Efficiency at Part Load OperationEfficiency at Part Load OperationEfficiency at Part Load Operation

Gas Turbine Thermal Efficiencyη/ηref versus Load P/Pmax (Typical, for 3 arbitrarily selected industrial engines)

50

60

70

80

90

100

110

50 60 70 80 90 100

Load (%)

Rel.

Ther

mal

Effi

cien

cy (%

)

Page 24: How Gas Turbines Work

General Questions to All ManufacturersGas Turbine ApplicationsGas Turbine Applications

Page 25: How Gas Turbines Work

General Questions to All ManufacturersIndustrial Applications

Page 26: How Gas Turbines Work

General Questions to All ManufacturersGas Turbine Driven Compressor SetGas Turbine Driven Compressor Set

Page 27: How Gas Turbines Work

General Questions to All Manufacturers

00

HE

AD

1 UNIT 2 UNITS 3 UNITS IN PARALLEL

SITE POWER AT 75F

FLOW

Operational FlexibilityManaging Varying Demand

Operational FlexibilityOperational FlexibilityManaging Varying DemandManaging Varying Demand

Operating Points in a Compressor Station

Page 28: How Gas Turbines Work

General Questions to All Manufacturers

Centaur 50Centaur 50

Gas Turbine Driven Generator Gas Turbine Driven Generator Gas Turbine Driven Generator

Page 29: How Gas Turbines Work

General Questions to All ManufacturersApplicationsApplications

• Base Load (Continuous Duty)– Designed to operate 6,000-8,000 hrs per year (more

or less continuously)• Peak Load

– Designed to operate approximately 1,000 hours per year (started during peak power demands, usually about once per day)

• Stand-By– Designed to operate less than 1,000 hours per year

(started if other systems fail)– A “Standby Duty” unit is operated as a backup to, not in

parallel with, a normal source of power. – Typical operation ranges from 50 to 100 hours per year

with one start per week.

Page 30: How Gas Turbines Work

General Questions to All ManufacturersBase and Peak Load UnitsBase and Peak Load Units

• Firing Temperature − Output Power− Exhaust

Temperature− Life− Maintenance

intervals/Cost of Maintenance

Output Power

Exhaust Heat

Maintenance Cost

Net Cash Flow

TRIT

Maintenance Interval (hrs)

Page 31: How Gas Turbines Work

General Questions to All Manufacturers

Base Load, Peak Load and StandBase Load, Peak Load and Stand--By UnitsBy Units

• Engine Life depends on Firing Temperature(and number of starts*)

– Thus, a peak load unit can be fired at highertemperatures without any design changes

– Higher Firing Temperature means more power, but shorter engine life.

* According to some manufacturers