Reflux problem

[wedwards]

The last 2 times I have used the reflux still (pure distilling) I have had a weird issue. It seems to get up to temp ok, but after a little while it does this weird thing where the temp starts to rapidly drop. At the same time I can hear bubbling up the column. If I cut the power to the boiler (25 litre boil a beer thingy) the temp in the column immediately rises back to normal and the bubbling goes away. I can then fire up the boiler again for a little while before it does the same thing again.

Did some research and some people said this might be caused by a leak somewhere but I've double and triple checked and there's no leak.

It's also not too much product in the boiler, because last time I only half filled it and got the same behavior.

If it helps, I'm just distilling some dodgy wine this time, and last time it was a bunch of low wines of tpw.

Any ideas what might be going on?

[Hobo]

I am no expert and I am not using the same setup as you are but my rig does that when it reaches near the end of the run which is when I turn it off.
Sometimes you can get rapid drop of temp if you are working outdoors and get some breeze.
I have just done a few "salvage" runs and found that my still does not behave as usual.
Brew up another wash and see how you go, cheers

[Canadoz]

Have you tried adjusting the coolant flow lower when this happens? It sounds like you're suddenly refluxing too much and no vapor is getting past the packing to hit the thermometer probe. That would explain the temperature drop. Does the water pressure in your house fluctuate? if the mains pressure jumped up and forced too much water into the reflux column it could conceivably drop the temperature enough to hit full reflux and stop your output. The balance between just the right amount of reflux and too much is a very fine line. That's why needle valves are used. We need VERY fine control.

I can't explain why shutting off power to the boiler would stop the problem unless it simply causes you to readjust the coolant flow as you bring the temperature back up, or allows enough time to pass for the mains pressure to drop back to where it was when you started your run. :think:

It could also be that by turning off the heat you slow the flow of vapors and less vapor going up means less liquid coming back down, so that may be enough to restore equilibrium. try adjusting the cooling first next time before shutting the boiler off. if you catch it as soon as the temperature starts dropping or you hear bubbling (whichever is noticeable first) you may be able to get it balanced again in a few moments. every still is different, yours may be very touchy, I don't know..

[wedwards]

I'll try backing the coolant off a bit and see how it goes - out water pressure is actually really good and I don't think it's fluctuating.

The other thing is also that half way through the run it seem to settle down and start to behave.

[wedwards]

Ok that didn't help - within a couple mins it did it again. Will try extra water and see if that affects it

[Canadoz]

Ok that didn't help - within a couple mins it did it again. Will try extra water and see if that affects it

Is there an adjustment of any kind on the boiler? can you raise or lower the heat? if so, try lowering the heat input slightly. too much throughput can overwhelm any distilling column.

[Canadoz]

I'll try backing the coolant off a bit and see how it goes - out water pressure is actually really good and I don't think it's fluctuating.

The other thing is also that half way through the run it seem to settle down and start to behave.

how full is your boiler?

you could be making it almost puke if it's too full, which would also explain what you describe.

you need some room at the top for all the bubbling and foaming the wash will do....

Depending on the brew you're distilling you may need more, or less headroom. a good rule of thumb is to only fill to within 15% of your boiler's top.

try leaving it a minute when the temperature drops, if it spits wash out the alcohol take-off then that's your problem. drop the level in your boiler and bob's you uncle.

[wedwards]

Tried water faster and slower and it has made no difference either way so far - took longer to screw up when water was really really slow but it still screwed up eventually.

[wedwards]

It's definately not the volume as it did it to me last time when it was only half full with tpw.

I've used this thing for years and never had an issue with the way I run it, nor with water temp/volume - that's what's really confusing.

[wedwards]

It might be the heat but I just can't work out why it's not done this in the last 7 or so years I've been using it. Have also done a lot of dodgy wine runs as my step father can't make good wine to save himself, and never this issue before.

[wedwards]

Could it be that the column needs some kind of cleaning or something?? I've never taken the packing out - every 4 or 5 runs depending on what I am running I usually whack some citric acid through it a few times. Haven't done that for a little while though.

[Canadoz]

Could it be that the column needs some kind of cleaning or something?? I've never taken the packing out - every 4 or 5 runs depending on what I am running I usually whack some citric acid through it a few times. Haven't done that for a little while though.

You should always at least back flush the column with water after a run. if you never have, I guess it could be gunked up or something? It might be time to take out the packing, clean and re-pack the column. it's a head scratcher to be sure, what sort of packing is in the column? pot scrubbers?

[wedwards]

Have watched it a little closer and it seems to rise about half to one degree right before the temp drops and I start to hear bubbling in the column. Dunno what that means, but hope it means something to someone ;)

[wedwards]

Packing is copper definately - looks like its all one piece.

[Linno]

Gday mate

i used to have one of these rigs, never had this issue - whats a rapid temp drop mate 5 - 10 - 20 degrees? also what happens to the output at this time?

also if you can hear bubbling in the column i dont think thas a good thing.

[Canadoz]

It might be the heat but I just can't work out why it's not done this in the last 7 or so years I've been using it. Have also done a lot of dodgy wine runs as my step father can't make good wine to save himself, and never this issue before.

Are you using it in a different part of the house? a different circuit maybe? I've noticed the voltage isn't the same on different circuits in my house. can be +/- 5V or so. just a possibility again.

I wouldn't totally rule out puking. Have the last couple washes been the same stuff? maybe it's just really really foamy stuff? that happens with rum washes. you can't go above about 60 - 70% full because they foam so much. If it's homemade wine that Failed and didn't convert all the sugar, The sugar in it could be foaming like no tomorrow. a little cooking oil in the wash can help.
can you reduce the volume in the boiler easily into a pot or a bucket and try with it less full?

[Canadoz]

Just checked out the specs on your still head, looks like it's a modified boka design: http://homedistiller.org/forum/download ... &mode=view

which means it doesn't use a product condenser coil, just a reflux coil and a little sump to catch your output. This tells us two things.

1 you almost can't make it puke.

2 there's no such thing as too much coolant flow.

Which leads me to the conclusion that the only possible explanation is that the wash is entering the distillation column. There's absolutely nothing else it could be.

As per my comment about sugary washes. try reducing the volume in the boiler and see what happens. If that doesn't fix it it's time to call the manufacturer.

[wedwards]

Will just have to watch it super close and keep manually stopping and starting the boiler to keep it under control then after in done this thing is going to get ripped apart.

[wedwards]

Yeah ok cool thanks I will definately try that again next time - just can't understand as I've had the same stuff in it way more volume in the past and never had a problem like this

[Canadoz]

Yeah ok cool thanks I will definately try that again next time - just can't understand as I've had the same stuff in it way more volume in the past and never had a problem like this

If it's TPW did you run it a little earlier than usual these past 2 times? less time to settle I mean? that would mean more stuff in the boiler that could foam up.
Alternately, did it finish at a higher SG than usual? or was there anything else about these last 2 batches that was different at all? That's likely your reason for the sudden change.