Flare Design: Air-assisted flare

How is the flare designed to minimise methane? > Flare Design: Air-assisted flare

Summary

Air-assisted flare design utilizes forced air injection into the combustion zoneThe area of the flare flame where the gas and vapours found just after a flare tip combine for combustion. Elevated Flare definitions and calculation methods from 40 CFR 63… which provides smokeless flaring while maintaining the desired combustion efficiency.

How it works

Air is fed through a blower system into an air riser where it is combined with waste gas. The extra air flow causes turbulence in the waste gas stream which improves mixing and increases combustion efficiency.
Air-assisted flare tip designs vary by manufactures.

Air assist flare designs (Images courtesy of © John Zink Company LLC)

Advantages

Produce less noise than the steam-assisted flares.
Best option for harsh conditions such as desert environment where water is scarce.
Provides smokeless flaring with 98% destruction efficiency provided that the amount of air is monitored and controlled to maintain the desired combustion efficiency.

Limitations

If too much air is applied by operating the combustion air blowers at higher flow than required could result in a low-pressure zone at the tip which tends to pull air into the tip causing burn back and damage the flare tip.

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Case study

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Improve efficiencies

Maintaining effective cobustion efficiency and destruction efficiency are key to minimising methane from flaring. This can be achieved through improving the mixing of flare gas and air to enable complete combustion and/or by only lighting the flare when required using ignition and pilot-light systems that avoid the risk of venting.

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