2 Phase Flow & Line Blowing Solvent with Nitrogen

[PharmaB]

I am trying to find a basis for calculating the required Nitrogen pressure and velocity for blowing a 2inch solvent pipeline. The aim is to empty the solvent line as much as possible following a centrifugal pump transfer. The pipe run is approximately 50meter in length that has both horizontal and vertical runs from the Nitrogen tee to the receiving vessel. The elevation of the Nitrogen tee is about 10metres below the receiving vessel and is located at the suction of the pump. The available Nitrogen pressure is 4barg from a 1inch line. Is there a straightforward basis for calculating the required Nitrogen pressure and velocity to blow forward the solvent into the receiving vessel with minimal solvent remaining in the line??

 

[MikeHalloran]

To get the line really clean really fast, you need to rig a 10 m vertical leg at the pump suction and introduce the N2 at the top of it.

Good luck figuring out the timing, but a blast of gas will push the solvent forward as a slug. Vent the line, and the solvent comes back. Get the solvent 'rocking' back and forth with alternating blasts of gas and venting, and when you've got it in resonance, _then make the last burst of gas really long and blow out the last of the solvent.

The technique may or may not scale up well. It works great on a 3/8" refrigerant line running the length of a van and back.










Mike Halloran
NOT speaking for
DeAngelo Marine Exhaust Inc.
Ft. Lauderdale, FL, USA