API Std 537:2003 pdf download.Flare Details for General Refinery and Petrochemical Service
3 Definition of Terms
Terms used in this Standard as they relate to flares are defined in 3.1 through 3.68. 3.1 air seal: A device used to minimize or eliminate the intrusion of air back into the riser from the exit. 3.2 assist gas: Fucl gas that is added to relief gas prior to the flare burner or at the point of combustion in order to raise the heating value. 3.3 back blowing: The procedure by which the dry air seal drain line is blown back from the base of the drain into the buoyancy seal to ensure the line is clear. 3.4 blowoff: The loss of a stable flame where the flame is lifted above the burner. This occurs if the fuel velocity exceeds the flame velocity. 3.5 buoyancy seal: A dry vapor seal that minimizes the required purge gas needed to protect from air infiltration. It functions by trapping a volume of light gas in an internal inverted compartment. This prevents air from displacing buoyant light gas in the flare. 3.6 burnback: Internal burning within the tip. This might result from air backing down the flare bumer at purge or low flaring rates. 3.7 burn-pit flare: An open excavation normally equipped with a horizontal flare bumer that can handle liquid as well as vapor hydrocarbons. 3.8 burning velocity: The speed at which a flame front travels into an unburned combustible mixture. 3.9 coanda flare: A flare burmer that is designed to employ the acrodynamic effct where moving fuids follow a curved or inclined surface over which they flow. Flares of this type generally use steam or pressure to achieve smokeless performance. 3.10 combustion air: Air required to combust the flare gases. 3.11 combustion efficiency: The percentage of the combustible fuid totally oxidized in the burner. In the case of hydrocarbons, combustion efficiency is the weight percent of carbon in the original fuid that oxidizes completely to CO2. 3.12 condensable gas: A vapor that can condense at the temperature and pressure expected in a flare header during or after a flaring event. 3.13 derrick support: A support system for the elevated flare riser normally used for very tall flares or when plot space is limited. Various derrick supprted arrangements are avail- able: a fixed system has its riser permanently supported to the derrick; a dcmountable derrick has multiplc riscr scctions that are designed to be lowered and removed to permit lowering of the fare burmer to grade; a demountable derrick with one fixed riser provides for a single piece design to be lowered to grade as a single component. 3.14 design flare capacity: The maximum design flow to the flare normally expressed in kilograms per hour (pounds per hour) of a specific composition, temperature, and pres- sure.