Knock-Out Drums

Knock-Out Drums are designed to effectively remove hydrocarbon liquids from the main flare relief gas to prevent the possibility of liquid carryover and flaming rain from the flare tip.

The size of the Knock-Out Drums is based on the criteria defined in API RP 521 considering residence time and knock out the velocity of the liquid particles in the vapour flow. Although flare tips can handle small amounts of liquid droplets, the allowable velocity in the drum may be based on that necessary to knock out droplets from 300 microns to 600 microns in diameter.

The drums are designed to avoid the accumulation of hydrocarbon liquid and will be equipped with instrumentation and control to monitor liquid levels with pump out or any drain facilities.