Performed my first N2 assist yesterday with cold gas (-78*C) and my dewaxing column at a similar temp. I run bi-directional, 2LB column, so I first let the systems vacuum suck the liquid solvent into the column from the bottom, shut the ball valve and let it soak for about 20 minutes. All was going well.
Liquid solvent was moving just fine, and I ran at about 50PSI until the dripping stopped. Pushed it a little higher and more solvent was released. Stopped dripping.
Yield seems really great, and it has an awesome color. However, I was left with a little over 1lb in the solvent tank. Yes, I ran the N2 into the vapor port. Is this normal to have remaining solvent in the tank when running cold with N2 assist? I was under the impression it would have pushed all solvent out and only N2 would remain, attractive because I could turn around, pull vac, and use the initial cylinder as a recovery cylinder as well. More pressure maybe?
Boy that 40CUF N2 tank went quicker than I thought… may have to upgrade to a 100.