(1-01) combustion training - basics of combustion

Praxair, Inc. - Business Confidential 1

Basics of Combustion

BASICS OF COMBUSTION


Worlwide Oxygen Market and Applications

49%

25%

6%

6%

4%

2% 8%

* Most of oxygen is used for high temperature metallurgical processes and combustion applications

Primary MetalSteel

- BOF*- Blast Furnace*- EAF*- Corex*- Direct Reduction*- Reheating Furnace*

Aluminum- Melting Furnace*

Copper- Smelting Furnace*- Anode Furnace*

Chemicals/Refinery- Ethylene Oxide- Syngas*- TiO2*- Claus Sulfur*- FCC Regenerator*- Sulfuric acid recovery*

Glass/Clay/Concrete- Melting Furnace*- Cement Kiln*

Welding & Cutting*

Healthcare

Pulp & Paper- Delignification- Black Liq. Gasfication*

Others - Waste Water- Aerospace*- Coal Gasification*

Source: Salomon Smith Barney 2002


Effects on Oxygen Enrichment on GeneralCombustion Characteristics

z Higher Flame Temperature is useful for welding, cutting and melting.

z Higher Flame Speedis useful for intense combustion.

z Lower Ignition Temperatureis useful for combustion of low heating value waste.

z Wider Flammability Rangeis useful for flame stability.


Benefits of Oxygen Combustion

Fuel Savings

Productivity Improvement

Equipment Cost Savings Flue gas cleanup (due to lower flue gas flow rate ) Elimination of regenerators and recuperators

Reduced Emissions NOx, Particulates, CO CO2 (through energy efficiency)


Air and Oxy-Fuel Combustion

COMBUSTION OF METHANE

Air-Fuel

CH4 + 2O2 + 8N2 2H2O + CO2 + 8N21.07 Nm3 of Air/Mcal

9600 scf of Air/MM Btu

Oxy-Fuel

CH4 + 2O2 2H2O + CO20.22 Nm3 of O2/Mcal

2000 scf of O2/MM Btu

cp (cal/g/K, Btu/lb/R)CO2 0.20O2 0.22N2 0.247H2O (Liq) 1.0H2O (Vap) 0.5

Lvap H2O = 546 kcal/kg (978 Btu/lb)


Oxygen Combustion Significantly ReducesFlue Gas Volume



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FUEL

FLUEGAS

WALLLOSS

PROCESS

Generic Energy BalanceAir-Fuel Combustion

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FUEL

FLUEGAS

WALLLOSS

PROCESS

Generic Energy BalanceOxy-Fuel Combustion

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FUEL

FLUEGAS

WALLLOSS

PROCESS

Generic Energy BalanceAir-Fuel Combustion

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FUEL

FLUEGAS

WALLLOSS

PROCESS

Generic Energy BalanceOxy-Fuel Combustion

kCHARGE > kREFRACTORY

k (W/m/K)Aluminum 200Copper 384Iron 60Steel 50Lead 35Alumina 18Mullite 6ZrO2 2SiO2 1.3

Higher emissitivy(eAIR = 0.17 vs. eOXY = 0.33)

Higher Residence TimeHigher Thermal EfficiencyE n

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Thermal Efficiency (Net Heat Available)Air-Fuel Combustion

0.2

0.3

0.4

0.5

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800 900 1000 1100 1200 1300 1400 1500 1600

Flue Gas Temperature (oC)

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Air-Fuel

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Air at 25 oC

Stoichiometric O2:Fuel Ratio


Thermal Efficiency (Net Heat Available)Air-Fuel vs. Oxy-Fuel Combustion

0.2

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800 900 1000 1100 1200 1300 1400 1500 1600


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Air-Fuel Oxy-Fuel

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Air at 25 oC

O2 at 25 oC



0.2

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800 900 1000 1100 1200 1300 1400 1500 1600


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Air-Fuel Oxy-Fuel Air (400 degC) Air (1000 degC)

0.2

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800 900 1000 1100 1200 1300 1400 1500 1600


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Air-Fuel Oxy-Fuel Air (400 degC) Air (1000 degC)

Thermal Efficiency (Net Heat Available)Air-Fuel vs. Oxy-Fuel Combustion

Air at 25 oC

O2 at 25 oC

Air at 400 oC

Air at 1000 oC



Potential Fuel Savings for Key Markets

0 250 500 750 1,000 1,250 1,500

Air Preheat Temperature (C)

Flue Gas Temperature (C)

272605388161093 Aluminum

Steel

Boiler

0

1020

30

40

5060

70

8090

100F

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a

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(

%

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Glass

Fuel: Methane, 2% O2 In Flue Gas

0 250 500 750 1,000 1,250 1,500

Air Preheat Temperature (C)

Flue Gas Temperature (C)

272605388161093 Aluminum

Steel

Boiler

0

1020

30

40

5060

70

8090

100F

u

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a

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(

%

)

Glass

Fuel: Methane, 2% O2 In Flue Gas


Adiabatic Flame Temperature for Natural Gas


Principle of low NOx Aspirator Burner

OXYGEN HIGH VELOCITYLOW VOLUME

FUEL

LOW TEMPERATUREHIGH MOMENTUM

ASPIRATION OF FURNACE GASES

O2 + FURNACE GASES

LOW VELOCITYHIGH VOLUME

PRAXAIRS A BURNER

AIR LOW VELOCITYHIGH VOLUME

FUELAIR BURNER

LOW TEMPERATUREHIGH MOMENTUM

OXYGENLOW VELOCITYLOW VOLUME

FUELCONVENTIONAL OXYGEN BURNER

HIGH TEMPERATURELOW MOMENTUM


Praxair A BurnerProvides Benefits of Oxygen at Low Flame Temperature

Fuel Tube

Oxygen NozzlesAnnulus Oxygen

Oxygen Jet

Oxygen to Annulus

Combustion Gases

Oxygen Envelope

Fuel Jet

Combustion Gases

Oxygen Jet

Oxygen to Nozzles

Fuel


2100

2000

1900

1800

Furnace Wall Temperature (F)

Isotherms, F

Measured Flame ShapeFiring Rate = 1 MMBTU/HRA Burner - Straight Nozzles

2400

28001800

90

Furnace Length, Inches

F

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Burner

20

10

-20

-10

0 10 20 30 40 50 60 70 80

0 280024002300

2000

1950

Flame Temperature Adjustability with Oxy-Fuel


2100

2000

1900

1800

Furnace Wall Temperature (F)

2150 Isotherms, F

2150

Measured Flame ShapeFiring Rate = 1 MMBTU/HRA Burner - 30 Divergent Nozzles

2100

2050

2300

2300

1580 1700

90

Furnace Length, Inches

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Burner

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-20

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0 10 20 30 40 50 60 70 80

Flame Temperature Adjustability with Oxy-Fuel


Oxygen Combustion General Characteristics

z Higher Thermal Efficiency (Net Heat Available)

z Higher Emissivity (0.33 with oxy vs. 0.17 with air)

z Oxy-Combustion process can promote low peak flame temperature with burners properly designed and sized.

z Higher Average Bulk Flame Temperature

z Higher Combustion Products Residence Time


Fuel Oil ViscosityImportance on Atomization

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(1-01) combustion training - basics of combustion

Documents

business confidential

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