Why does distillation stop mid run?

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Still of the Night
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Why does distillation stop mid run?

Post by Still of the Night »

I bought a 5 gallon pure copper alembic still a year ago. It's one of those round pot belly tank ones with what I heard called an onion on top and a neck to a worm. For heat source, I went electric for heat, an 8" diameter 1000W hot plate. Took me a few months to get how too's and recipes, etc. I did a vinegar cleaning run, all went well. couple of months later, I did a "sacrificial" run per instructions and a funny "recipe" I received. I am over a mile high so temperatures are different than at sea level. I studied those. I start the run, at 150deg F I start getting drips, I filled a quart quickly. Temperature got to just under 180deg F and had a good drip rate, filled five more quarts. Then, without touching anything, dripping slowed, temp was just over 180deg F. took an hour to get not even a quart. Then it stopped. Temp still at 180. I waited over 30 minutes and never started back up. while cleaning the still, I noticed a leak in one of the solder joints. I cleaned it and soldered it. Couple of months later I did a regular recipe, fermented two weeks, and did the run. Same thing happened, but much much much slower and worse, eight hours and not even three quarts. Temperatures and events the same, just slower and less volume. I have tried searching for this issue and doing research on processes too see if there is any mention of this. None. So I am reaching out to you fellow shiners. What causes distillation to stop mid-run?
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Yummyrum
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Re: Why does distillation stop mid run?

Post by Yummyrum »

Have you got your hot plate connected to a PID controller ?
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NZChris
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Re: Why does distillation stop mid run?

Post by NZChris »

Is the hot plate turned up to it’s maximum? If it is, you need a better heat source.
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Re: Why does distillation stop mid run?

Post by Rum Agol »

You mention a "funny" recipe and a regular recipe but nothing about what they were or their abv. Did the first one have more alcohol in it hence more output ? Has the hotplate got a simmer stat or thermal cut out control built in ?
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subbrew
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Re: Why does distillation stop mid run?

Post by subbrew »

What was the proof or ABV of the last jar before it stopped? I am at about 5000 ft and started out with an under powered system as well. I would start collecting with a vapor temp of about 160 and it would slow to almost a stop at 188 or so but by then the output was down to about 18 or 20 ABV so I just stopped. It talks more power to change water to vapor than to change alcohol to vapor. So as the water was a larger part of the mix I was running out of power to make the liquid to vapor phase change.

Sounds like you running out of power as well. That can be a problem with hot plates for two reason, one is just low watts, the second is they cycle on and off. I also use a hot plate on my first still and what I do is set my still in a tamale pot filled with oil. This mitigates the cycling as the oil provides a heat reservoir. the lack of power, would need a larger hot plate or possibly you can make a difference by insulating your boiler and onion so all the power is staying in the liquid/vapor. I also took an old coat and made a coat for my still and put one sleeve on the riser. This helped a lot on speed to first product.
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Re: Why does distillation stop mid run?

Post by cob »

this is the welcome center so welcome.

complaining about getting a gallon and a half

out of a 5 gallon alembic needs to go in a

how the hell did you do that thread.
be water my friend
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Ben
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Re: Why does distillation stop mid run?

Post by Ben »

More power!
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Grundefuht
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Re: Why does distillation stop mid run?

Post by Grundefuht »

short version: at some point Reflux value reaches 100%.

bit longer: "Onion" (and still walls also) radiates heat while cooling down vapor. At start temperature inside helm is low and some(or most) of vapor goes to worm. At some moment temperature reaches point where Helm cooling is equal to Heating value.
Try to get more power.
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bluefish_dist
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Re: Why does distillation stop mid run?

Post by bluefish_dist »

At 180 deg you are not getting hot enough. At 5200 ft boiling for water is a little over 200 deg and for alcohol 165 ish. Try a new hot plate or a stove burner. Your boiler should peak out at a little over 200 with all the alcohol out.
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Still of the Night
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Re: Why does distillation stop mid run?

Post by Still of the Night »

Thanks everyone for the info, more power. I was wondering about that. Just confused by the temperatures, got up ok and held the temp. I did see the plate kick in and out but temp held.
The first batch, I did not take a specific gravity before fermentation and didn't have a meter for ABV since it was a throw away run. Second batch specific gravity was 1.1 and ABV of the foreshot was over 70%.
I will find better heat source and investigate a PID controller.
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Ben
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Re: Why does distillation stop mid run?

Post by Ben »

image.png
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You can use those three charts to figure out about what your temps should look like. Once you have some success you will know what your temps are, but this will give you a chance...
:)
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Re: Why does distillation stop mid run?

Post by NormandieStill »

A PID controller will get you no-where fast. You need a straight forward linear controller (SCR / SSR) which will allow you to control the power. You can't control the temperature at which your wash boils, you can only observe the vapour temperature and extrapolate from there.
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Re: Why does distillation stop mid run?

Post by Sporacle »

+1 with Normandie, don't go anywhere near it with a PID, get a SCR as he suggested. Don't worry about actual temperature use your senses to judge the power required :D
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NZChris
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Re: Why does distillation stop mid run?

Post by NZChris »

Still of the Night wrote: Mon Oct 11, 2021 6:52 am I will find better heat source and investigate a PID controller.
A PID controls temperature. What you need for a pot still is control of the power.

The temperature just is what it is according to the ever changing boiling point of the ABV in the still at the time. A still can be run without any thermometers anywhere, just by controlling the output stream.

If you cannot resist the temptation to fiddle with the controller while watching the temperature, you should remove the thermometer, or tape over it.
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Re: Why does distillation stop mid run?

Post by Saltbush Bill »

Still of the Night wrote: Mon Oct 11, 2021 6:52 am I will find better heat source and investigate a PID controller.
The following link might help you understand why the boiling temp of the contents of your boiler is constantly changing, and why a PID is the WRONG tool for the Job. Do not be fooled into thinking that they are worth trying by some of the garbage you might see and hear on Youtube. This forum is littered with threads by newbies who have tried and failed.
http://www.kelleybarts.com/PhotoXfer/Re ... gMyth.html
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Yummyrum
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Re: Why does distillation stop mid run?

Post by Yummyrum »

Yummyrum wrote: Thu Oct 07, 2021 12:21 pm Have you got your hot plate connected to a PID controller ?
I asked this not because I thought you needed one but rather assumed you might already be using one due to your fascination with Temperature .

As said ,wrong tool . Also trying to be a human PID by watching temp and adjusting power to boiler is also wrong . :thumbdown:

Watching the output flow and adjusting boiler power is correct method . :thumbup:

I also think that a 1kW hot plate on full should have no problems keeping your size boiler producing .
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NZChris
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Re: Why does distillation stop mid run?

Post by NZChris »

Yummyrum wrote: Mon Oct 11, 2021 11:41 pm I also think that a 1kW hot plate on full should have no problems keeping your size boiler producing .
Watching the Amps might tell another story Yummy. Solid plates often have a built in 'Safety' thermostat that cuts out one element, halving the Watts. Your 1000W plate might only be putting out 500W after the thermostat trips.
Still of the Night
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Re: Why does distillation stop mid run?

Post by Still of the Night »

Thanks a lot for all this valuable information. I am trying to assimilate and put things in perspective. There are questions that have been asked. Let me re-state the situation. I have this 5gal bubble pot copper still. The thermometer is in the lower portion of the onion. Didn’t really think about the location of the temp. Both runs were of potato mash with white cane sugar. Didn’t check specific gravity of first run since it was a total throw away (I know, should have checked, I make wine and always check). I did a lot of research on process, cuts, and temperatures, etc. Been on Clawhammer (Emmet), Mile Hi, Moonshiners club, and more. I know the mash has water and has to be removed. I am at 6300 feet elevation. Water here full rolling boil at 192 deg F. and ethanol should boil low 160s more like 162. Thanks for the charts. First run. Recipe only had 3# of potatoes, tomato paste, sugar, and lemon juice. The electric plate turned to max. Then the steps described in first post. Did temp adjustments and temp held or climbed. After stoppage, turned temp cntl to max, nothing. The second run. Full blown 25# potato mash and white cane sugar. Specific gravity 1.1 . The electric plate turned to max. Same temp steps as first run but took a lot longer. Same temp cntl adjustments and responses. Much much slower and stopped a lot sooner. The foreshot came in at ABV 70+%. I want to get to the point that lets my gut know what and when but I would need to know ballpark temps and ABV levels to get started on the cuts. OK, more powerful plate, I’ve started looking into 2500W, enough, not enough? I’ll check into the SCR. And watch the Amps. And trust my gut. Are there any suggestions on a particular electric plate?
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Ben
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Re: Why does distillation stop mid run?

Post by Ben »

More is pretty much always better as long as you can control it and you aren't scorching stuff. 2500w is pretty comparable to what I run, my element produces 4800w (5.5kw element), 13-14 gallon boils and is plenty sufficient, I run it around 40% power for most of the hearts section. It gets turned up for stripping. This is a keg boiler.

You could try insulating your pot, if you are marginal it might be enough to get you there.
:)
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subbrew
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Re: Why does distillation stop mid run?

Post by subbrew »

Still, you need to check your thermometer. Water should be boiling at 200.5 at 6300 ft.

Your description of the second run taking much longer, I wonder something failed in the hot plate. Assuming the same fill, more alcohol in the mix actually should have heated up sooner than your first run since alcohol has a lower specific heat than water.

Anyhow, more power would be good. Can you try gas, natural or propane, something other than a hotplate.
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NZChris
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Re: Why does distillation stop mid run?

Post by NZChris »

It doesn't matter if a modern, solid, hot plate is 1000W, or 2500W, they will still normally have a thermostat built into the plate that is cunningly designed to mess with the heads of unsuspecting newbie distillers who don't know about it and don't have an Ammeter to watch.

This is not the controller on the front. The controller on the front is usually a simmerstat that is cunningly designed to mess with the heads of unsuspecting newbie distillers by switching the power on and off causing the output to surge. It is not a thermostat or a temperature controller, even if the instructions that came with it say it is. It controls power. When I use them, I turn them to maximum and control the power to the hot plate with an SCR. Even then, I occasionally trip the internal plate thermostat when using too much power. If half it's rated power is enough to run your still, it doesn't matter.

The contents of your still won't boil at the BP of ethanol, but at the BP of the ethanol/water mix at the time, which is why pot stills shouldn't be run by trying to control the temperature. I suggest that you tape over the thermometer until you have learned how to run without it.
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Ben
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Re: Why does distillation stop mid run?

Post by Ben »

With the challenges posted, maybe its time to solder or weld a bung in the side and integrate an element...
:)
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NZChris
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Re: Why does distillation stop mid run?

Post by NZChris »

Ben wrote: Sat Oct 16, 2021 7:13 am With the challenges posted, maybe its time to solder or weld a bung in the side and integrate an element...
That can come with pitfalls as well, like when you want to run with solids in the boiler.

When I was running mine on a solid hotplate that was slightly underrated, I could keep it running by throwing a towel over it for some insulation. Now, I mostly run it on a hot plate that has a spiral element, so no hidden cutout, and I've bypassed the simmerstat.
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