Bok Flood - Post mortum

[Expat]

Had an bad experience today, and I wanted to run it past the group to see what people thought.

Loaded my boiler today for a spirit run, same as any other time....14g low wines @ 40% in my keg boiler and turned on the power. 3kw electric heat. 2" Bok packed with medium dense copper mesh. 3kw is the normal power for the duration of a run.

Boiler warmed up as per normal and reached temp. Cooling water running at normal levels, vapour climbed the column and I was watching to see equalization begin.... First sign of a problem I saw two drips come from the thermo port, moments later a large gurgling sound from the condenser at which point liquid alcohol started coming out of the pressure vent.

Panic. killed power. opened the takeoff valve to drain the excess accumulation of liquid. Clean up big mess. PHEW. Thanking GOD i'm not using propane else it would probably have been a big fire. Also another reason why I always pay close attention!!!

So now, I try to figure out what the HELL happened. No process changes, No changes to the equipment. I did the very same run on Monday (and many times before) with absolutely no issues.

I've never seen flooding before. Any ideas what changed? Appreciated for any advice from the more experienced.

[shadylane]

I had a similar experience when the reflux condenser sprung a leak

[Expat]

Thanks for the tip Shady! I'll give that a look. I inspected by condenser before my previous run and everything looked normal. I'll push some water through it and open up my take off and see if I get anything.

Edit: doesn't appear to be a leak. Ran full pressure to the condenser for a couple minutes and got nothing from the takeoff. Happy and Sad about that.

[der wo]

Probably you know that 3kW is pretty much the maximum for a 2".
Perhaps nomally your low wines are a bit lower in abv? The higher the abv the more vapor per kW.
Or perhaps there was an area where the packing was too tight?

[Expat]

Much appreciated for the info there Der Wo. Actually I wasn't aware about that limit. The power is all I have for input at the moment so I've never been able to experiment with more. In this regard I guess I hit the sweet spot by accident.

I did wonder about the packing, but since I hadn't changed anything since the previous spirit run earlier in the week, I don't know what it would be.

Regarding the low wines, i'm fairly consistent about making sure that its 40% or lower as I don't want any safety issues. So i'd guess the variance is a few % at most.

A further update on the situation. I let things sit for awhile and cool down a bit, at which point I restarted and brought the boiler back up to temp.... and this time the column behaved normally! No flooding, temp peaked and then started equalising. So was the cause of this a fluke in the fluid dynamics within the packing or something? Definitely has me wondering.

[bitter]

do you normally run a little bit lower % in the boiler. my 3" with a normal wash will handle about 5500 watts. But when doing a neutral run with 40% I need to cut power back a fair bit or I get the column flooding.

[Saltbush Bill]

But when doing a neutral run with 40% I need to cut power back a fair bit or I get the column flooding.

Wondering how much a "fair bit " is? Ive been running 2400w on a 3 inch with 40% charge and it seems to work well at that.

Probably you know that 3kW is pretty much the maximum for a 2".

My initial response was to agree with this, however you say you have run it with that power before and it worked ok though.

[bluefish_dist]

I always cut back power as I reach temp so if I get an foaming I don't flood the column. Was a bit slow this week and looked up to see my plates looking like fish tanks. Really common as I believe the proteins will cause foaming until then get boiled a little. I have had the same thing happen on strip runs.
If you warm up at 3k, I would pull back to maybe 1200-1400 as you hit temp, let it stabilize and then add power back as you start takeoff.
Some time at temp allows a hot break and the foam will subside afterwards.

[der wo]

When riding the still at the limit, small variations can cause flooding I think. So a bit more abv or a little more power in the electrical lines tonight, a small area with stiff packing, whatever.
And after cooling down and starting again perhaps a few foreshots were already gone, the abv a bit less. Or perhaps fusel oils from the last tails are washed away from the packing now, so the reflux flows down faster, I don't know, it's speculating.
I only think, yes, a 2" with 3kW can flood. t doesn't need a puking wash or a dead mouse in your column.

[Expat]

Yes, 30-40 spirits runs I've probably run since I built my bok. When in the learning to drive phase, I kept increasing the power waiting to see any sign of flooding, but that never happened so I've always just run under full power. So you can imagine my surprise when condensate starting spurting out of the atmospheric vent. For reference, my column and boiler is well insulated so I don't think i'm wasting juice anywhere....

I'd be amazed if a 3" diameter would require less power than i'm using on mine.

Bluefish - would you expect to see foaming issues with sugar head low wines? they don't seem to be capable of that...

der wo - LOL i'll check for the mouse

[Expat]

I didn't say it before, but Thank you all for your help in understanding what happened here.

[bluefish_dist]

I rarely run straight sugar washes. Usually a mix of sugar and something else. I always slow down when up to temp as I have had too many times where I overflowed the column. You are going to stabilize anyway before takeoff and a lower heat Input won't hurt as you are not taking anything off.

[Expat]

Fair enough BlueFish, I do sugarheads as part of my gin production, minimising extra flavours. Using the power suggestions you've made has brought things under control now.

Further follow-up. I ran a batch of cleared 10% sugar head wash and had the same flooding effect occurring in the column. I think its probably a safe assumption that this point that something has changed (shifted or compacted) in some way so as to change the dynamic of the packing.

When I finish my current run of neutrals i'll breakdown the column for cleaning and repacking, at which point I should get a clear answer. Afterwhich its back to UJSM and Rum runs with the pot head so none of this drama.

[underdog]

You have had some good advice. Most folks cut back their power once their rig gets up to temperature.
You need extra heat to bring your wash and your rig up to working temperature. Once there, you only need to put in as much heat as necessary to do the work at the speed you want to do it.
That's going to depend on your rig and your desires, but it's certainly going to be less heat than you needed to get things up to temperature.

I've kept logs on every run, so I know about how long things should take. I also have a laptop connected to my thermocouple that will give me an alarm as soon as it sees a temperature a few degrees above ambient as a backup.