gas turbine .pdf

8/9/2019 gas turbine .pdf

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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 Does it Work?

Gas Turbine Components

Gas Turbine Performance

Gas Turbine Applications


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1) Compression

2) Combustion

3)Expansion

(Turbine)

Output Shaft Po

Output Shaft PowerTwo Shaft

Turbine En

Two ShaftTwo Shaft

Turbine EnTurbine En

Single Shaft

Turbine Engine

Single ShaftSingle Shaft

Turbine EngineTurbine Engine


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Compressor Pumps Air into Combustion Chamber

Fuel in Gaseous or Liquid Spray Form Injected into

Combustion Chamber and Burned

Continuously Expanding Combustion Products DirectedThrough Stationary Airfoils

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

Remaining High Energy Gas Can be Used

expansion across a nozzle (propulsion)

expansion across another turbine stage (shaft power)


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Simple Cycle Gas TurbinesSimple Cycle Gas Turbines

as Aircraft Engines and Land Based Prime Moveas Aircraft Engines and Land Based Prime Mover

COMPRESSOR TURBINE

COMBUSTOR

FUEL

AIR IN

EXHAUST

GAS OUT

POWER

OUTPUT

COMPRESSORTURBINE

COMBUSTOR

FUEL

AIR IN

EXHAUST

GAS OUT

NOZZLE

THRUST

HIGH

VELOCITY

JET

POWER

TURBINE


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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


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1

2

3

5

BraytonBrayton Cycle (Simple Cycle Gas Turbine )Cycle (Simple Cycle Gas Turbine )

VelocityTemperature

Pressure

Station

1 2 3 5 7

Flame Temperature


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Gas Turbine ComponentsGas Turbine Components


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Industrial Engine on SkidIndustrial Engine on Skid


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Airflow Parallel toRotor Axis

Air Compressed inStages

row of moving blades

followed by row ofstationary blades(stators) is one stage.

Moving blades impartkinetic energy

stators recover thekinetic energy as

pressure and redirectthe flow to the nextstage at the optimumangle


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Modern CompressorDesigns areExtremely Efficient

gas turbineperformance rating

depends greatly onthe compressorefficiency

High Performance

Made Possible byAdvancedAerodynamics,Coatings, and Small

Blade Tip Clearances Even Small Amountsof Deposits onCompressor Blades

May Cause LargePerformance Losses

Inlet Guide Vane

Rotor Blades(rotating)

Stator Vanes (fixed t


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Also Known as the Burner

Must be Compact and Provide Even TemperatureDistribution of Hot Gases to the Turbine

Three Basic Configurations: annular

can

can-annular

1

2

35


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Injector

Combustor

Liner (requires

intensive coolin

Shaft


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Annular

Donut shaped, single,

continuous chamberthat encircles the turbine

Can-annular multiple, single burners

(cans) evenly spaced around

the rotor shaft

Silo or Can

One or morecombustion chambers

mounted external

to the gas turbine body


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Used to introduce fuelinto the combustion

chamber. Can be for single or

dual fuel

Fuel can be mixed withcombustion air either

in the combustor(standard combustionsystem)

pre-mixed prior to

entering combustor( lean pre-mix, DLN(dry-low-Nox), DLE

(dry low emissions),(SoLoNOx)

Pre-Mix Ba

Solar Mars Injector

Standard vs SoloNOx

Stand

injec

Dry-Low-NOx injector


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1

2

3 5

Two Basic Types - Radial and Axial

Almost all industrial Gas Turbines use axial flowturbines

Like the Compressor, Turbine Expansion

Takes Place in Stages a row of stationary blades (nozzles)

followed by a row of moving blades= one stage.


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Turbine Nozzle SegmTwo 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)


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COOLING AIR INLET

HOT

GAS

FLOW

HOT GAS F

COOLIN

SHOWER HEAD

FILM HOLES

Film CoolingConvection Cooling

TIT TRIT T5


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TIT TRIT T5

Combustor

1st Nozzle

1st Rotor 1st PT Nozzle

CoolingFlows

All temperatures are considered total.

G T biG T biG T bi


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Gas Turbine

Performance Characteristics

Gas TurbineGas Turbine

Performance CharacteristicsPerformance Characteristics

G T biG T biG T bi


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Gas Turbine

Performance vs. Ambient Temperature

Gas TurbineGas Turbine

Performance vs. Ambient TemperaturePerformance vs. Ambient Temperature

0

1000

20003000

4000

5000

6000

7000

8000

9000

10000

-20 -10 0 10 20 30 40 50

T amb (deg C)

Power,Heatrate

HP

HR


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

Gas Turbine Thermal Efficiency/ref 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.ThermalEfficiency(%)


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Operational FlexibilityOperational FlexibilityOperational Flexibility


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0

0

HEAD

1 UNIT 2 UNITS 3 UNITS IN PARALLEL

SITE POWER AT 75F

FLOW

p y

Managing Varying Demand

p yp y

Managing Varying DemandManaging Varying Demand

Operating Points in a Compressor Station


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Base Load (Continuous Duty)

Designed to operate 6,000-8,000 hrs per year (moreor less continuously) Peak Load

Designed to operate approximately 1,000 hours per year(started during peak power demands, usually about onceper 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 inparallel with, a normal source of power.

Typical operation ranges from 50 to 100 hours per yearwith one start per week.


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Firing Temperature Output Power

Exhaust

Temperature

Life

Maintenanceintervals/Cost of

Maintenance

Output Power

Exhaust Heat

Maintenance

Cost

Net Cash Flow

TRIT

Maintenance Interval (hrs)

SB L d P k L d d St d B U it


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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 higher

temperatures without any design changes

Higher Firing Temperature means morepower, but shorter engine life.

* According to some manufacturers

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