1 reply to this topic

[KeJoSa2010]

Hi,

 

Could one ever justify using a common HP/LP Flare Knockout Drum? In my limited experience, I have seen a common LP/HP flare stacks; however, there have always seen separate knockout drums for the two systems. Has anyone ever seen this approach in use, and if so, what was the justification for doing it?

 

Thanks

[Dazzler]

Keeping the LP and HP systems separate could arise for example due the temperature of the stream.  The HP gas may have been let down in pressure from something very high and has become very cold, so that stainless steel is needed for mechanical design temperature considerations.

 

Additionally, one stream compared to the other may have water present, or could be corrosive, or have liquids that will need to be pumped away rather allowed to just eventually evaporate.

 

The HP vent system during a major relief scenario may be pressurised due to back pressure to higher than acceptable for the LP relief valves, meaning larger and more complex LP valves and headers are needed.  

 

One needs to clearly understand the sources of the relief streams and their conditions and properties. 

 

I'm sure there are other factors.   Hope this helps.

 

Dazzler