Combustion Air Calculator for Air Quantity
Combustion of fuel requires the right quantity of air including excess air which is supplied by an FD Fan. The quantity of air is calculated using stoichiometry involved when air reacts with the fuel.
Fuel which is a mixture of Fixed carbon, Moisture content, Ash and Volatile material can be further broken down into simple elements such as Carbon, Sulfur, Nitrogen, Oxygen, Hydrogen, water vapor, and ash particles.
Proximate and Ultimate analysis of fuel is done experimentally to determine the mass percent of various fuel elements.
You can also refer to Thermodyne’s Boiler Bible that provides you the general composition of the above elements for various fuels.
Following are the basic chemical reactions involved in the combustion of air with fuel:-
C + O2 CO2 (Complete Combustion)
S + O2 SO2
2C + O2 2CO (Incomplete Combustion)
2H2 + O2 2H2O (Moisture)
Air quantity is calculated keeping in mind the complete combustion of fuel, so for the complete combustion of fuel excess air is kept to around 20% – 50% depending upon the type of fuel, size of fuel particles and degree of mixing.
The Combustion Air Quantity Calculations calculator below helps you determine the theoretical as well as actual air requirement per Kg of fuel by providing the elemental composition of fuel and its mass faction.
See Also: Boiler Blowdown Calculator
For boiler system related calculations Check out All Thermodyne Calculators
Combustion Air Calculator FAQ
Excess air is the amount of air that is added to a fuel during combustion in order to ensure complete combustion. Complete combustion occurs when all of the fuel is burned, leaving no unburned carbon or other pollutants.
Excess air is important to calculate because it can affect the efficiency of a combustion process and the amount of pollutants that are emitted. Too much excess air can lead to wasted energy and increased emissions, while too little excess air can lead to incomplete combustion and the formation of harmful pollutants.
There are a few different ways to calculate excess air. One common method is to use the following formula:
Excess air (%) = (O2 in flue gas – O2 in air) / (O2 in air)
where:
O2 in flue gas is the percentage of oxygen in the flue gas
O2 in air is the percentage of oxygen in the air
Another method for calculating excess air is to use a combustion analyzer. A combustion analyzer is a device that measures the concentration of various gases in a flue gas, including oxygen.
There are two main types of excess air: theoretical excess air and actual excess air.
Theoretical excess air is the amount of excess air that is required for complete combustion.
Actual excess air is the amount of excess air that is actually used in a combustion process.
Excess air can have a significant impact on the efficiency of a combustion process. Too much excess air can lead to wasted energy, while too little excess air can lead to incomplete combustion and the formation of harmful pollutants.
Excess air can also have a significant impact on the emissions from a combustion process. Too much excess air can lead to increased emissions of nitrogen oxides (NOx) and other pollutants, while too little excess air can lead to incomplete combustion and the formation of harmful pollutants such as carbon monoxide (CO).
The recommended levels of excess air vary depending on the type of fuel and the application. For example, the recommended level of excess air for natural gas is typically 10-15%, while the recommended level of excess air for coal is typically 20-25%.
There are a number of ways to reduce excess air. One way is to use a combustion analyzer to measure the actual excess air and then adjust the combustion process to reduce the excess air. Another way to reduce excess air is to use a fuel with a higher heating value.
There are a number of benefits to reducing excess air. These benefits include:
Increased efficiency
Reduced emissions
Lower operating costs
There are a number of challenges to reducing excess air. These challenges include:
The need to adjust the combustion process
The need to use a fuel with a higher heating value
The need to invest in a combustion analyzer