Fill Level of Still

[adamOVD]

How low is too low? My still is always a bit finicky when it comes to surging, but today was atrocious. I had to just shut it down and walk away. The best thing I can think of is that is was under-filled.

I usually run my low wines in my small still, but I had a lot saved up, So I put them in my "Large Still" and planned to run it over the course of 2 days. First day it was 3/4 full and ran great all day. Second day when I started it up It was about half full with Low wines, and it was nearly impossible to run. The problem with my theory though, is that when I do my final run of Gin after macerating my botanicals, by then end of the run the liquid level in the still is probably even lower but has no problems. 

It is a Bain Marie water jacket. I was running it through two plates. I gave up at one point and just tried stripping the rest with no reflux, and it still surged like mad.

[PeteB]

I posted on this surging problem some time ago but don't remember anyone following up on my suggestion.

I had a similar surging problem with a bench top still. 

I completely eliminated it by putting a few small chips of a ceramic tile in the boiler. I remember this technique from University chemistry days.

I tried it in my production still that very occasionally surges but not certain that it helped because it only happened occasionally.

Find a very hard tile or porcelain dinner plate and smash so you have lots of small pieces with sharp points. It is those points that allow the allow the liquid to boil off a lot easier and should prevent surging.

[adamOVD]

Thanks Pete, I really dont want to throw anything in the botton of the still, as it also serves as a mash cooker and ill have to pull them out again. It also has a pretty oversized agitator, which i would think would create plenty of bubbles and nucleation points. It has quite a few sharp corners on it as well. 

In the past i isolated the surging to my condensor being too cold. This seems to be something else and is much more dramatic. I topped off the still with water, and ill look over the plates and lyne arm before i try again. I can't run the still again until monday though, so i thought id try to see if anyone here had an idea.

[SlickFloss]

what's your heat source? element or steam? If steam are you able to see pressure in real time?

[adamOVD]

15 hours ago, SlickFloss said:

what's your heat source? element or steam?

It's a Bain Marie with electric elements. I talked to the still manufacturer and he confirmed that if still is less than 30% full the surging will get worse and worse. I filled it with hot water before trying again, and it ran super smooth.

The agitator is vertical, not offset, and there is a fin on the side that works as a vortex breaker. My theory is that if the liquid drop below the fin, the vortex causes some sort of vacuum effect. I wish I had tried running it without the agitator to confirm my thinking.