A Gas Flare, also known as flare stacks, is basically a stack, or open pipe, discharging a combustible gaseous waste directly to the atmosphere with the end of the stack containing a pilot flame, a source of steam and an exit nozzle.
The steam is used to generate turbulence and momentum, promoting good mixing with surrounding air, as a source of heat to help in cracking complex molecules within the gas stream to provide smokeless burning as well as a reactant in the combustion process to help oxidize carbon to gaseous state. Combustion air is provided by the surrounding atmosphere.
Incineration by gas flaring is a simple controlled discharge into the atmosphere. Gas Flares are used as low cost means of disposal of relatively large amounts of gas containing combustible components.
They are suited to processes which are not continuous and as such heat recovery is not economical.
For gases that contain little or no oxygen but that will burn mixed with air, rich-mixture incinerators are needed. Gas Flares are often seen in petroleum refineries, typify such systems.