General Questions to All Manufacturers
This is a Gas Turbine.
How does it work?
Contents
General Questions to All Manufacturers
• How Does it Work? • Gas Turbine Components • Gas Turbine Performance • Gas Turbine Applications
General Questions to All Manufacturers
Single Shaft Turbine Engine
Output Shaft Power
3)Expansion (Turbine) 2) Combustion
1) Compression
Output Shaft Power
Two Shaft Turbine Engine
The “Simple Cycle”
General Questions to All Manufacturers
• 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)
General Questions to All Manufacturers
Simple Cycle Gas Turbines as Aircraft Engines and Land Based Prime Movers THRUST FUEL COMBUSTOR EXHAUST GAS OUT
HIGH VELOCITY JET
AIR IN
COMPRESSOR
TURBINE
NOZZLE
FUEL EXHAUST GAS OUT
COMBUSTOR
POWER AIR IN OUTPUT COMPRESSOR
TURBINE
POWER TURBINE
Commonalities
General Questions to All Manufacturers
• 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
General Questions to All Manufacturers
Velocity Temperature Pressure
Brayton Cycle (Simple Cycle Gas Turbine )
Flame Temperature
2 1 1
2
3 Station
5
7
3
7 5
General Questions to All Manufacturers
Gas Turbine Components
General Questions Components to All Manufacturers Engine External
Industrial Engine on Skid
General Questions to All Manufacturers The 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 2 • Driven by the Turbine on a Common Shaft 1 • Compressor Uses 2/3 of the Fuel Energy That’s why keeping it 3 efficient (read CLEAN) is so important!
7 5
Axial Compressor
General Questions to All Manufacturers
• 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
Axial Compressor
General Questions to All Manufacturers
• 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
Stator Vanes (fixed to case)
Rotor Blades(rotating)
The Combustor
General Questions to All Manufacturers
• 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 2 1 3
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Annular Combustor
General Questions to All Manufacturers
Injector
Shaft
Combustor Liner (requires intensive cooling)
Combustor Design
General Questions to All Manufacturers
• 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 chambers mounted external to the gas turbine body
Fuel Injector
General Questions to All Manufacturers
• 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)
Dry-Low-NOx injector Pre-Mix Barrel
Standard injector
Solar Mars Injector Standard vs SoloNOx
The Turbine
General Questions to All Manufacturers
• 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.
2
1 3
7 5
Axial Turbine
General Questions to All Manufacturers
Two Stage Axial Turbine
Turbine Nozzle Segment
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 2200 F (some even higher)
General Questions to All Manufacturers Blade Cooling Schemes
HOT GAS FLOW COOLING AIR
SHOWER HEAD FILM HOLES COOLING AIR INLET
Convection Cooling
HOT GAS FLOW
Film Cooling
Temperature Definition
General Questions to All Manufacturers
TIT
T5
TRIT
Combustor
1st Rotor 1st Nozzle
All temperatures are considered total.
1st PT Nozzle Cooling Air Flows
General Questions to All Manufacturers
Gas Turbine Performance Characteristics
General Questions to All Manufacturers
Power, Heat rate
Gas Turbine Performance vs. Ambient Temperature 10000 9000 8000 7000 6000 5000 4000 3000 2000 1000 0
HP HR
-20
-10
0
10
20
T amb (deg C)
30
40
50
General Questions to All Manufacturers
Efficiency at Part Load Operation Rel. Thermal Efficiency (%)
110 100 90 80 70 60 50 50
60
70
80
90
100
Load (%)
Gas Turbine Thermal Efficiencyη/ηref versus Load P/Pmax (Typical, for 3 arbitrarily selected industrial engines)
General Questions to All Manufacturers Gas Turbine Applications
General Questions to All Manufacturers Industrial Applications
General Questions to All Manufacturers Gas Turbine Driven Compressor Set
General Questions to All Manufacturers
Operational Flexibility Managing Varying Demand 2 UNITS
3 UNITS IN PARALLEL
HEAD
1 UNIT
SITE POWER AT 75F
0 0
FLOW Operating Points in a Compressor Station
General Questions to AllGenerator Manufacturers Gas Turbine Driven
Centaur 50
Applications
General Questions to All Manufacturers
• 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.
General Questions to All Manufacturers Base and Peak Load Units
• Firing Temperature − Output Power − Exhaust Temperature − Life − Maintenance intervals/Cost of Maintenance
TRIT
Output Power Exhaust Heat Maintenance Cost Net Cash Flow
Maintenance Interval (hrs)
General Questions to All Manufacturers
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
