Percent Excess Air Formula:
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Definition: Percent Excess Air means that amount of air supplied in addition to the theoretical quantity necessary for complete combustion of all fuel or combustible waste material present.
Purpose: It helps engineers and technicians optimize combustion processes by determining how much extra air is being supplied beyond what's theoretically required.
The calculator uses the formula:
Where:
Explanation: The difference between actual air fed and theoretical air required is divided by the theoretical requirement and converted to a percentage.
Details: Proper excess air calculation ensures efficient combustion, minimizes fuel waste, and helps control emissions in industrial processes.
Tips: Enter the moles of air actually fed to the process and the theoretical moles of air required for complete combustion. Both values must be > 0.
Q1: Why is some excess air necessary?
A: Excess air ensures complete combustion, but too much excess air reduces efficiency by carrying away heat in the flue gas.
Q2: What's a typical percent excess air value?
A: Most combustion systems operate with 10-20% excess air, but this varies by application and fuel type.
Q3: How do I find the theoretical air requirement?
A: Theoretical air can be calculated from the stoichiometry of the combustion reaction for your specific fuel.
Q4: What if I get a negative percentage?
A: A negative result means you have insufficient air (deficiency), which leads to incomplete combustion and potentially dangerous conditions.
Q5: How does this relate to oxygen content?
A: Percent excess air correlates with flue gas oxygen content - higher excess air means higher O2 in the exhaust.