Whenever a process requires that entrained droplets be removed from a vapor stream, a knockout drum should be integrated into the system. Condensation can occur when hot process gases cool considerably in the flare gas header and riser, and some gases also go to dew point at ambient temperatures and pressures and can therefore generate liquids. These droplets must be removed in order to avoid the phenomenon known as flaming rain, which occurs when liquid droplets are blown out the top of a flare stack along with ignited process gases. These vessels can be either horizontal or vertical.
The dynamic (velocity) seal is a simple innovation which ensures significant cost savings over time. The reverse conical baffle design reduces flow area in the flare tip while simultaneously increasing purge gas velocity. In combination with the dynamic seal, a constant flow of purge gas will maintain a seal in flare system, ensuring that air infiltration does not occur. A vortex effect is created as the exiting purge gas inspirates intruding air. This intruding air is drawn out of the boundary layer and into the exiting purge gas flow column, thus purging the flare tip. This technology is a standard on various flares.
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