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Flare Knockout PSV

Flare Knockout PSV

Flare Knockout PSV


We have a small flare liquid knockout vessel (scrubber) at the base of our flare of our oil and gas facilities. This vessel is rated for 125 psi and is fed by another, larger scrubber upstream with its own control valve and PSV. The question is whether the final small liquid knockout vessel at the base of the flare needs a PSV. The vessel discharge feeds into the flare stack with no valves between. The one aspect I'm not sure about is that we have a flame arrester at the point where the pipe enters the flare stack. Is this flame arrester something that needs to be considered for a blocked outlet and would thus require a PSV? We're having some internal debates and disagreement about this.

RE: Flare Knockout PSV

Our flame arresters plug. Vapor phase monomers condense on cold surfaces (flame arrester internals). This results in uninhibited liquid monomer which polymerizes to a solid. We have scheduled cleanings. Missing a cleaning is a human error; a valid scenario.

That's our situation. You'll have to hash out yours with your team.

Good luck,

To a ChE, the glass is always full - 1/2 air and 1/2 water.

RE: Flare Knockout PSV

Why do you have a troublesome flame arrestor? Why not continuous gas purge of the flare header?

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