4 replies to this topic

[Pronab]

Hydrocarbon liquid condensate Coalescer PSV discharge is routed to HC(gas) flare line instead of routing to a liquid blow down line. Operating pressure/Temperature are: 30.0 barg & 60 Deg C , while PSV set pressure is 44.5 barg. Composition of hydrocarbon liquid condensate are from C1 up to C10+. Does it looks a design mistake/fault, should we recommend to change the route of PSV discharge to liquid blow down line in the coming shut down?

Thanks in advance.

 

 

[fallah]

pronab,

 

If the back pressure isn't so high and the condensate composition is such that after flashing from 44.5 barg to back pressure mostly converts to vapor phase, the design to select gas flare line as destination appears to be correct....

[Zauberberg]

It doesn't necessarily need to be an error if volumes of discharged condensate are small and there is a KO drum in the flare system, but it is very unusual to have such stream routing. Perhaps the condensate will flash and produce significant amount of vapors once when discharged into near-atmospheric pressure in the flare header, and this was the reason for considering this discharge route in the first place.

 

I don't know what other disposal systems you have there, and what do you refer to when saying "liquid blowdown". If this is a pressurized, closed hydrocarbon system, I'd agree it is likely the best place for disposing of a liquid stream. Another alternative may be to discharge the PSV somewhere downstream into a low pressure equipment. This is very common for e.g. TEG filters discharging back to the TEG flash drum. It requires further assessment.

[Pronab]

Fallah: HC Flare line is a near atmospheric pressure. I don't have any flash calculation but I can presume around 10% flash in this case. So discharge will be still a considerable amount of liquid in case of PSV pop-up.

We have a closed pressurized blow down system dedicated for liquid service.

[fallah]

pronab,

 

If the available back pressure in closed pressurized blow down system not to be a big issue for mentioned PSV operation; appears routing the PSV discharge to liquid blow down system to be best option for that PSV...