Abstract: Flare system is used to deal with the flammable gas discharged in refinery and chemical plant in accidents and the flammable gas leaked by equipment such as control valve or safety valve, so it plays a vital role in ensuring the safe production of units. At present, elevated flare is the most commonly used flare system. If the air enters the flare pipe network from the flare head and mixes with the flammable gas existing in the pipe network, explosive gas mixture will be formed, easily leading to backfire explosion accident when it meets with the ignition source. Flare system is the last defense for security of petrochemical enterprises, and its anti-backfire design, as a crucial link in the process design of flare system, will play an important role in the safe and stable operation of flare system as well as the energy saving and consumption reduction.

Key words: anti-backfire, water seal, gas sealer, purge gas