What percentage of carbon dioxide in flue gases indicates proper combustion of fuel?

• A. 5 to 10 percent
• B. 10 to 15 percent
• C. 15 to 20 percent
• D. 20 to 25 percent

Answer: (B)

Proper combustion of fuel typically results in the formation of certain byproducts, including carbon dioxide (CO2). When examining flue gases, a CO2 concentration of about 10 to 15 percent is generally indicative of efficient combustion. This range suggests that the fuel is being burned effectively, with a sufficient amount of oxygen used and minimal unburned hydrocarbons or other gases present.

When CO2 levels are at this percentage, it indicates that the combustion process is producing a relatively high amount of CO2 compared to other potential byproducts, such as carbon monoxide (CO) and unburned fuel, which can occur when combustion is incomplete. High CO2 levels within this range are desired, as they reflect improvements in combustion efficiency and reductions in emissions of pollutants. Maintaining CO2 within this percentage range is essential for both environmental compliance and operational efficiency in combustion systems.