*Gas Turbine Combustion Systems

* Motivation to study about Industrial Gas Turbines

What does combustor do?

Types of combustors

Design requirements

Introduction to combustion chemistry

Alternative fuels, pollutants, oscillations

Challenges related with variable load conditions

*Energy Outlook ReportUS DOE

*Trend of worlds energy consumption (Data from US Department of Energy)1 Quadrillion = 1015, 1 BTU = 1.055x103 JWorlds energy requirement can largely be classified into Electric power, transportation energy1 Quadrillion BTU = 45M Tons Coal or 1T ft3 Natural Gas or 170M Barrels of crude oil1 Barrel crude oil = 42 gallon = 6.1 GJ of energy

**Organization of economic cooperation and developmentTrend of worlds electricity consumption (Data from US Department of Energy)Fossil fuels: Coal, gasoline, diesel, natural gas and other petroleum productsAlternative sources of energy: Wind turbines, solar panels, hydroelectric, nuclear, geothermal, tidal, and list goes onAlternative fuels: Ethanol, bio-diesel, biomass, coke oven gas, syngas, municipal waste, landfill gases, anything rottingMajor sources of electricity production

*There is a very well established energy infrastructure based on fossil fuels in US and across the globe. The worlds proven fossil fuel reserves and lifetimesThe advantage of alternative fuels is that the existing infrastructure can be used.Gas turbines industry is going to stay in business for a long time

Sheet1

Pr

120.5083426895Difference between Heavy Duty and Aeroderivative Turbines

IndustrialAero-derivatives

Overhaul Life48,000 hours30,000 houts

Hot section inspection8000 hours6000 hours

Overhaul LifeOn-siteGas generator removal

Engine weightHeavy DutyLight

Fast start capabilityNoYes

Tolerance to poor fuelFairPoor

Ease of automationGoodGood

Suitable for off-shoreFairGood

PowerUp to 325 MWUp to 55 MW

Thermal Efficiency25-39%25-42%

FuelReserves (Q)Lifetime (y) No GrowthLifetime (y) w/ Growth

Coal24,000258140

Oil92806050

Gas69669050

*About Solars Gas Turbines

*How does this story relate with Gas Turbines Combustion systems?Types of engines Power generation: Gas Turbines, Steam Turbines, Nuclear, HydroTransportation : diesel, gasoline, aircraft engines (based on gas turbine cycles)Strictly speaking, energy is not consumed, but rather is converted into different forms.

Various types of engines are used to achieve this objective.Steam turbines are similar to gas turbines but they have different principles of operation. Nuclear power plants use nuclear energy to make steam which rotates the steam turbines.

*Gas Turbines find their applications in

electric power generation, mechanical drive systems, supply of process heat and compressed air, pump drives for gas or liquid pipelines

jet propulsion, land and sea transport (infancy state)Industrial turbines or prime movers

* Solar Turbines Incorporated, a subsidiary of Caterpillar Company is a world leading producer of mid-range (1 MW 25 MW) industrial gas turbines for use in power generation, natural gas compression, and pumping systems.

There are 12,500+ engines installed in 102 countries

Solar ranks as one of the 50 largest exporters in the United States

*Our units are used for power generation, gas compression, and mechanical drive applications

Power generation is the production of electrical energy whether for stand-by or base load power applications.

Gas compression applications include gathering (at the well head), transmission (pipeline), re-injection (storage), and pressure boost (compression).

Mechanical drive applications are units sold as prime-movers for non-Solar packaged driven equipment, whether generators, compressors, or pumps

*Harbor Drive Facility

*Gas Turbines OEMs

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*Latest additionOutput 22.3 MW Thermal Eff. 40%

*1) Compression2) Combustion3)Expansion (Turbine) Output Shaft PowerOutput Shaft PowerTwo Shaft Turbine EngineSingle Shaft Turbine EnginePower GenerationMechanical Drive

*Simplistic Gas Turbines working principles 1-2 Isentropic compression (in a compressor)2-3 Constant pressure heat addition (in a combustor)3-4 Isentropic expansion (in a turbine)4-1 Constant pressure heat rejection

*Petrobras, offshore Brazil, Power generation and crude oil productionPower generation for gas fields in SiberiaNatural gas transmission, Desert environment

*Solars presence in San Diego two, soon to be three, Titan 130's at UCSD two Taurus 60's at SDSU some recuperated Saturns at landfills in San Marcos and Santee a Saturn genset at the Hotel Del a Mercury 50 at the VA hospital two Mercurys at Qualcomm two Centaur 40s at the Balboa Naval Hospital a Taurus 60 at the Children's Hospital

*List of companies and their products

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*Difference between Heavy Duty and Aeroderivative Turbines

Chart1

63

19

17

1

Sheet1

Pr

120.5083426895Difference between Heavy Duty and Aeroderivative Turbines

IndustrialAero-derivatives

Overhaul Life48,000 hours30,000 hours

Hot section inspection8000 hours6000 hours

Overhaul LifeOn-siteGas generator removal

Engine weightHeavy DutyLight

Fast start capabilityNoYes

Tolerance to poor fuelFairPoor

Ease of automationGoodGood

Suitable for off-shoreFairGood

PowerUp to 325 MWUp to 55 MW

Thermal Efficiency25-39%25-42%

FuelReserves (Q)1995 Consumption (Q/y)Rate of Growth (%/y) 1987-1997Lifetime (y) No GrowthLifetime (y) w/ Growth

Coal24,000930.8258140

Oil92801411.16050

Gas6966782.59050

Fossil Fuels63

Hydroelectricity19

Nuclear Energy17

Geothermal and others1

100

*Evolution of products : Uprates

*Performance of Gas Turbines is limited byComponent efficienciesTurbine working temperatureCurrent state of the artPr = 35/1components = 85-90%TIT = 1650 K

*What makes Gas Turbines attractive for Industrial prime movers?Advantages Very high power-to-weight ratio, compared to reciprocating engines Smaller than most reciprocating engines of the same power rating Fewer moving parts than reciprocating engines Low operating pressures High operation speeds Low lubricating oil cost and consumption High reliability Goes for 30-50K hours before first overhaul. Usually runs for 100K-300K hours (10+ years) life cycleDisadvantages Cost is much greater than for a similar-sized reciprocating engine since the material must be stronger and more heat resistant. Machining operations are more complex Usually less efficient than reciprocating engines, especially at idle Delayed response to changes in power settingsThese make GT less suitable for road transport and helicopters

*Some Basics

*Gas Turbine componentsInlet system Collects and directs air into the gas turbine. Often, an air cleaner and silencer are part of the inlet system. It is designated for a minimum pressure drop while maximizing clean airflow into the gas turbine.

Compressor Provides compression, and, thus, increases the air density for the combustion process. The higher the compression ratio, the higher the total gas turbine efficiency . Low compressor efficiencies result in high compressor discharge temperatures, therefore, lower gas turbine output power.

Combustor Adds heat energy to the airflow. The output power of the gas turbine is directly proportional to the combustor firing temperature; i.e., the combustor is designed to increase the air temperature up to the material limits of the gas turbine while maintaining a reasonable pressure drop.

*Gas Producer Turbine Expands the air and absorbs just enough energy from the flow to drive the compressor. The higher the gas producer discharge temperature and pressure, the more energy is available to drive the power turbine, therefore, creating shaft work.

Power Turbine Converts the remaining flow energy from the gas producer into useful shaft output work. The higher the temperature difference across the power turbine, the more shaft output power is available.

Exhaust System Directs exhaust flow away from the gas turbine inlet. Often a silencer is part of the exhaust system. Similar to the inlet system, the exhaust system is designed for minimum pressure losses.

*What drives Research and Development work in Gas Turbines? In 1950s component efficiencies In 1990s emissions In 21st century it is emissions and alternative fuels Nature of application and location are always the factors

*Simplistic Gas Turbines working principles 1-2 Isentropic compression (in a compressor); h2-h1 = mCp(T2-T1)2-3 Constant pressure heat addition (in a combustor); h3-h2 = mCp(T3-T2)3-4 Isentropic expansion (in a turbine); h3-h4 = mCp(T3-T4)4-1 Constant pressure heat rejection

*Gas TurbineminCpTin(min+mF)CpToutShaft power mFqRcomb

*Consider Centaur and MercuryKnown P ratio = 10TIT = 1350 KCompressor Eff. = 0.86Turbine Eff. = 0.89Heat exchanger effectiveness = 0.8Ambient temperature and pressure, 300 K, 1 barSpecific heat Cp = 1.005 kJ/Kg-KSpecific heat ratio = 1.4Calculate (a) Compressor outlet temperature (b) Turbine out temperature (c) Compressor work (d) Turbine work (e) back work ratio (f) Efficiency for ideal, actual, and recuperator engine

*First Law:Stagnation enthalpyCompressor workTurbine workHeat inputFor isentropic process

*Thermal EfficiencyNet work out

*122344Equipment efficienciesTSProcess 1-2 and 3-4 idealProcess 1-2 and 3-4 actual

*122344TSRecuperator56Heat exchanger effectiveness

*Variation of Cp with temperature