Vapour/smoke/haze at end of stripping runs

[tubbsy]

I'm running a boka and do the stripping runs with the valve and packed column removed to speed it up. When it's outputting <20% and >99°C in the boiler I have noticed a vapour cloud hanging around at the top of the condensor. I have increased coolant flow, stuffed copper wool down there and even redesigned and rebuilt the condensor, but it still appears at the very end of each stripping run. Any idea what it is?

[OtisT]

Sounds like water vapor. My sight glass starts to fog up at the end of a run. Happens when you are almost out of alcohol vapor.

If it is not vapor condensing it could be a scorch. Actual smoke. You would likely smell that.

Otis

[zed255]

Likely just some tiny droplets of low ABV condensate. I get this sometimes, more so when the condenser is being run too cold, just as you say towards the end of stripping. I think it is essentially just huffing, the violent collapse of vapour. Seems to me it causes a mechanical oscillation kicking some vapour out my vent.

I have tried a few things, mind you I'm running a vertical coil type condenser so my solution my not apply to you. Ultimately I just set a marble with a much larger diameter than the vent on the vent hole to act as a one way valve. Takes almost no pressure (used compressed air to experiment) to dislodge the marble but stops air being sucked in and expelled from the vent during this huffing. Running with good water control to get nice warm / hot water off the condenser helps too. Ensure the water is running counter-flow to the vapour as well.

[tubbsy]

Thanks guys. Water vapour was my guess too, but needed to make sure.

Otis, I don't think its smoke. I'm running on gas and not noticing a burnt smell.

zed, I have a vertical coil as well, but the top is completely open so can't use a marble over the vent.

[zed255]

When I was experiencing the phenomenon lifting my coil up to create a gap between the shell and cap, effectively opening the top completely, stopped the mist entirely. I also note in my case, it was a mist that was actually cold, so not a vapour at all. In fact my condenser seems to be such overkill that I only use about 1/3 to 1/2 of its 12" length most of the time. Been better since adding an adjustable pressure reducing regulator so I can get lower flow rates.