High Pressure Boiler Practice Exam

When air is burned with minimal excess, complete combustion occurs. This type of combustion refers to a process in which a fuel reacts fully with oxygen, converting all the carbon in the fuel to carbon dioxide and all the hydrogen to water.

In complete combustion, the ideal stoichiometric ratio of fuel to oxygen is achieved, meaning that the fuel is completely consumed without any of it remaining unburned. The presence of minimal excess air ensures that there is enough oxygen to facilitate this complete process while avoiding the additional heat loss or the production of harmful byproducts like carbon monoxide or unburned hydrocarbons that may arise from incomplete combustion.

This process is efficient, resulting in maximum energy release from the fuel and producing only carbon dioxide and water vapor as byproducts under ideal conditions. Thus, the choice that describes the combustion of fuel with minimal excess air is complete combustion.