Chapter 4 - Combustion Chemistry Flashcards
Natural gas consists primarily of ______
CH4, Methane
What are illuminating gasses
Mixture of “other gases” in the make up of Natural Gas
Why is combustion chemistry a valuable tool
Gain an understanding of the combustion process Fuel/air ratios CO2 Ultimates COAF Other information
Combustion is synonymous with ____
oxidation
Percentage Oxygen to Nitrogen in the air
21% oxygen, 79% hydrogen
79/21 = 3.76
3.76 volume of nitrogen drawn in for 1 volume oxygen
Why is nitrogen a problem for gas engineers (2)
- Nitrogen gets heated….energy wasted by the heating of Nitrogen. This lowers flue gas temps and affects the rate of heat transfer and efficiency.
- Nitrogen forms NOx at elevated temperatures. NOx is the start of air pollution and smog
What are Transport Losses?
The losses caused by the heating of nitrogen in the air during the combustion process.
What is the slow oxidation processes
Rusting and corroding
What is the moderately fast oxidation process
Combustion
What is the rapid oxidation process
Denotation and knock
What is the very rapid oxidation process
Explosion
What is excess air?
Air supplied to the combustion process above and beyond the amount of air required by the Stoichiometric mixture requirements.
Can burn with as little as 20-25% excess air
What are the keys to thorough mixing
Adequate mixing time and turbulence in the gas mixture
What is CO a sign of
incomplete combustion
impingement
What is CO2 an indication of
Can indicate the amount of excess air in the combustion process
How close the combustion process is approaching the ultimate
