Restriction for using valves in Flare KO Drums

[ChemE2912]

Hi there!

Is there any limitation in installing a control valve (i.e. flow control valve), in a flare Knock out drum pumps discharge line?.

The issue is that some vendors are recommending us to consider a centrifugal pump (I would rather use a positive displacement pump...) to pump out the liquids from the vessel, and the range of operation for the pump may vary as fluid viscosities can range between 10 to 700 cP!!!

Therefore, in order that the pumps are not overran in the case of low viscosity, a control valve should be installed.

However, we are used NOT to install any restriction in these type of systems, in order to avoid any restriction to the flow.

The pumps are intended to start/stop automatically on level (hi/lo).

Any advice is appreciated.

ChemE2912.

 

[MortenA]

I dont see any problems with a control valve downstream the flare KO reject pump. If the max head < piping design pressrure you wont event need a PSV.

Pumping of the liquids in the vessel is not a safety related operation - but something you do AFTER an incedent.

Best regards

Morten