Depending on the process to be carried out, industrial furnaces ideally operate with stoichiometric air/fuel ratio (also known as ‘correct ratio’), with which we make sure we burn the fuel completely without an excess of air.
For this purpose, it is typically rounded to 10 parts of air for each of natural gas or 25 parts of air for each part of LP gas, in those cases where the process requires it.
We can work with an oxidizing flame and excess air when using drying ovens, or a reducing flame (with excess of fuel), which can be used in some heat treatments and the melting of certain metals.
In this process, excess oxygen in the atmosphere must be avoided and excess fuel used to ensure the presence of zero oxygen. The excess gas is normally burned when leaving the furnace through the chimney and mixes with the oxygen in the environment.
The air/fuel ratio must be monitored frequently to prevent the burners from operating incorrectly and affecting combustion. Another way to monitor air/fuel ratio is by measuring the combustion gases.