3 replies to this topic

[Himanshu Sharma]

Hi !

I am working as a process engineer for abt an year but have no idea about flare design aspects.
i would like to particularly know about water seal drum and molecular seal.

i have a vague idea that waterseal drum prevents the entry of liquid HCs in flare stack(as the gas bubbles thru water). Molecular seal prevents entry of air in the flare stack.
i request that someone please elaborate "How" of the process.


and one more thing to add that i have seen operations people concerned about entry of air in the satck while we flare lower molecular weight gases.

as per my knowledge lighter the gas more the exit velocity (from satck) ..so there should not be any concerns..


ok this is not realted but the last one... please tell me how the "Hot tapping" is done while line is full of HCs.

Please try n help me out !

[JoeWong]

i have a vague idea that waterseal drum prevents the entry of liquid HCs in flare stack (as the gas bubbles thru water). Molecular seal prevents entry of air in the flare stack.
i request that someone please elaborate "How" of the process.

Please read API Std 521, Jan 2007, Fifth edition, section 6.4.3.6.1 and 7.3.3.3.3.

and one more thing to add that i have seen operations people concerned about entry of air in the satck while we flare lower molecular weight gases.

as per my knowledge lighter the gas more the exit velocity (from stack) ..so there should not be any concerns..

It subject to flare tip design, how low is the flowrate, composition, etc...

ok this is not realted but the last one... please tell me how the "Hot tapping" is done while line is full of HCs.

Search results via GOOGLE (CLICK here)...

[Zauberberg]

Look at this attachment for explanation of hot tapping procedure:

[attachment=849:Hot_Tapping.zip]

[Technocrat]

Hi,

The purpose of flare stack is to burn gases released from relief valves in a safe and controlled manner at a safe location above the ground. The gas must be burnt at the tip of flare and not inside the stack carrying gas to the top of the flare. If the air enters the stack it can form explosive mixture inside the stack and an explosion can happen inside the stack which is not good.

The purpose of the water seal drum is to avoid backflow of flame to the source of relief gas (i.e. towards the plant). If there is any backflow of flame then the flame will extinguish in the water seal. The water seal must be maintained by an overflow pipe where continuous flow of water in maintained.

Regards.