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Sunday, September 23, 2012

PowerPoint Presentation On Combustion Theory

PPT On Combustion Theory

Combustion Theory Presentation Transcript:
1. What is COMBUSTION ?
High speed, high temperature chemical reaction
Rapid union of an element or compound with oxygen to liberate heat – controlled explosion
Combustion occurs when elements of fuel such as carbon and hydrogen combine with oxygen

2. Chemical reaction in Combustion
Stoichiometric or theoretical air is ideal amount of air required for burning 1 kg of fuel
Ex:1 kg of fuel oil requires ~14.1 kg of air for complete combustion

3. 3 Ts of Combustion
TIME All combustion requires sufficient Time which depends upon type of Reaction
TEMPERATURE Temperature must be more than ignition temperature
TURBULENCE Proper turbulence helps in bringing the fuel and air in intimate contact and gives them enough time to complete reaction.

4. 3 Ts of Combustion
Ignition Time and Residence Time- Furnace volume to be large enough to give the mixture time for complete combustion.

5. 3 Ts of Combustion
Ignition Temperature- Fuel-Air Mixture maintained at or above the Ignition Temperature

6. 3 Ts of Combustion
Oxygen and Fuel thoroughly mixed.

7. What are the three types of combustion?
Perfect Combustion is achieved when all the fuel is burned using only the theoretical amount of air, but perfect combustion cannot be achieved in a boiler.
Good / Complete Combustion is achieved when all the fuel is burned using the minimal amount of air above the theoretical amount of air needed to burn the fuel. Complete combustion is always our goal. With complete combustion, the fuel is burned at the highest combustion efficiency with low pollution. 
Incomplete Combustion occurs when all the fuel is not burned, which results in the formation of soot and smoke.

8. Combustion of Fuel oil
Viscosity of 100 Redwood/ secs at burners
Atomising air 1- 3 Kg/cm2 (about 2 % of total air requirement)
14 Kg of air/kg fuel is required for complete combustion. Optimum efficiency with 10 % excess air
Flue gas should be analysed for CO2 or O2
Sulphur dewpoint at 160oC. Corrosion max at 30oC below dew point

9. Combustion of Fuel oil (contd.)
Slightest damage to burner tip may increase fuel consumption by 10-15 % and hence worn out tips should be replaced immediately
Oil pressure at burner should be 17-20 Kg/cm2
Correct flame is normally short. Impingment on walls, tubes cause carbon formation
Too short a flame indicates high excess air and air supply to burners should be adjusted for light haze brown out of chimney

10. For more please refer our PPT. Thank You.

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