OCR Text |
Show -5- An effective flame retaining device will allow both a higher exit velocity and a smaller flare tip. The flare flame will then be erect, stable and vertical, regardless of crosswinds. This results in lower thermal radiation at grade level and a much cooler, longer-lasting flare tip because flame lick along the side of the flare burner is reduced. An effective flame retainer is also critical for maintaining high combustion efficiency at velocities up to Mach O.B. State-of-art flame retainers employ VorTuSwirtM vanes to swirl approximately 300/0 of the flare gas in a vortex configuration. The other 70% goes straight up. The swirling ball of flame enhances recirculation at the base of the main flare flame, thus assuring a stable flame and preventing dangerous flame lift-ofts and flame-outs, regardless of variations in waste gas flow or weather conditions - from dead-still to hurricane- or typhoon-force winds. Design Pilots for Maximum Effectiveness All flares require dependable pilots, reliable ignition systems, and effective pilot windshields, which must protect pilot flames to ensure proper ignition of waste gas streams. Pilot windshields (nozzles), although often overlooked, are extremely important. Without them, the risk of an inoperable flare is real danger. Even if the flame is not extinguished by high winds, it may be directed away from the flare and rendered useless. The number of pilots used on a flare should be increased according to the diameter of the flare to prevent this possibility. Large flares require several pilots to assure ignition, regardless of wind direction. The size and number of pilots is determined by the size, deSign, and function of a flare, and the heat level of the waste gas. It is important to nc;>te that in our discussion of pilot windshields, we are referring to full windshields, which protect flare pilot flames in all directions. Partial windshields, supplied by some manufacturers, protect pilot flames from the wind in only one direction. (Many ineffective windshields trap rain, snow and condensate.) Dependable pilots incorporate stainless steel windshields, effective flame retention nozzles and pilot-air inspirating venturis with gas filters to assure a reliable source of primary air for stable, reliable pilot flames. Fluidic Windshields, previously mentioned, assure complete protection of pilot flames, regardless of wind speed, wind direction, and hurricane- or typhoon-force rains, which can extinguish poorly designed flare pilots, while filling ignitor lines with water and thus preventing re-ignition. { |