Flare inspection

[mcmg]

Hi all,
We have two flare system, hot and cold. The flare tips are stacked side by side, approximately ~0.4 to 0.5m difference, center to center. The plan is to turn off the hot flare as the hot KO drum is intended to be inspected. The cold flare is still, however, in service as we have some equipment connected to it that are in service. The hot flare still have some PSV's connected, but mostly fire case PSVs, and the actions to be taken for this is to stop any hot work activity on the equipment connected.

I am unsure if there are any safety implications if we proceed with this path forward, i.e, as there may be burned HCs and steam, is there a potential for the fluids release to "go" into the adjacent stack, given that there wind dynamics and release velocity (depending on the instances of the HC's flared) may change. We've tried to ask the vendor and there was no definite answer.

Thank you all.

 

[MHM-PCG]

mcmg, suggest you review the relief study for each PSV connected to the HF.

Other cases (e.g. blocked outlet) may give a smaller relief load than the fire case. Even though it is not the governing case, potential overpressure from such event is possible and should be mitigated as well.

 

[mcmg]

Hi,

Actually, what is connected to the cold flare are PVs for two cryogenic tanks, although, the BOG compressors are working during this time, hence based on data, the demand for the PVs on these tanks connected to the cold flare is very small. On the hot flare, aside from fire case PSVs, blocked discharge scenarios are on the BOG compressors, but there are high alarms provided to which operator can utilize to stop the BOG compressors (closed monitoring activity). Aside from these, 1 more PV on the accumulator (within the BOG system) is connected, but as long as the BOG system is okay, the demand for this PV is also small.

Options we have considered is to jumpover this one PV (2" valve) to the cold flare line (there are isolation valves we can utilize), however, as per above, I am unsure that it is okay to have the cold flare running whereas the hot flare is turned off considering the distances between them. Another option is to have these lines rerouted to atmosphere, size and length are based on dispersion models.

 

[hacksaw]

You might have to use purge steam to protect your system

 

[georgeverghese]

Many of these PVs' and PSVs' and other vent valves on the hot flare header may be leaking even when they are nominally closed.