An Experimental Analysis of Flame Stability of Open Air Diffusion Flames

The relief gas flares common in petrochemical production, processing and storage facilities are macro-scale examples of open air diffusion flame burners. Typical relief gases flared can range from high inert content purge streams to high heat content pure hydrocarbon streams. In addition, hydrogen is often a major relief constituent. For the extensive matrix of possible petrochemical plant relief compositions, the flare burner must be selected such that the combustion dynamics of the turbulent jet are compatible with the relief gas combustibility. To meet its prime objective of safe, effective disposal, the flare burner must provide stable ignition and complete combustion of the relief gases. Recent tests have, in fact, shown that a properly designed and operated flare can achieve extremely high hydrocarbon combustion and destruction efficiencies. Conversely, if a mismatch occurs between the flare burner (design, application or operation) and the combustibility characteristics of the relief gas, combustion may not occur or may proceed inefficiently. It is the purpose of this paper to study the stability of the open air diffusion flame as related to the combustion characteristics of the gases to be flared.