Columns Losing Temperature?

[NYDist]

So this is a totally new issue for me.  Out of the blue we can't get distillate to come over.  What's been happening is that our pot will heat up fine, our column seems to heat up normally, but then right as the top of the column is getting to our "go-time" temperature, it just crashes.  Then the column starts heating up again, and the whole thing repeats.  Heat up to just before the distillate runs over, temp crash, heat up, etc.  We've been running bourbon distillations for a few days in a row with no issue, and then one day the equipment just doesn't work the way it always has.  A couple things I've tried is just adding more heat to the steam jacket, and we got a tiny bit of distillate over before the temp crashed again (so same issue overall).  The other thing we tried to do was drain/blow out the steam baskets, which did have a little more water in them than they ought to, but that didn't make any impact whatsoever.  I don't think it's a boiler issue, as we can heat and run our mashes just fine, so I'm worried that either the still itself has something screwy with it, or the program running it is messing up somehow (though it looks like it's been running normally, at least on the surface).

[Kindred Spirits]

How are you controlling your cooling water for your columns? I'm guessing its some sort of automated valve?

[NYDist]

Yes, we adjust the setting in our program.  I have to confess that lately I haven't kept a close eye on the program to see if it was fouling up at the dephlegmator.  No need to monitor something when it's working normally, right? 🥴

[Cosmic.Distiller]

I agree with kindred spirits there... to me it sounds like the partial condensers on the top of your columns are getting screwy, crashing it and disappearing at intervals. Let us know what you find!

[Alex_Sor]

On 7/25/2022 at 2:52 PM, NYDist said:

So this is a totally new issue for me.  Out of the blue we can't get distillate to come over.  What's been happening is that our pot will heat up fine, our column seems to heat up normally, but then right as the top of the column is getting to our "go-time" temperature, it just crashes.  Then the column starts heating up again, and the whole thing repeats.  Heat up to just before the distillate runs over, temp crash, heat up, etc.  We've been running bourbon distillations for a few days in a row with no issue, and then one day the equipment just doesn't work the way it always has.  A couple things I've tried is just adding more heat to the steam jacket, and we got a tiny bit of distillate over before the temp crashed again (so same issue overall).  The other thing we tried to do was drain/blow out the steam baskets, which did have a little more water in them than they ought to, but that didn't make any impact whatsoever.  I don't think it's a boiler issue, as we can heat and run our mashes just fine, so I'm worried that either the still itself has something screwy with it, or the program running it is messing up somehow (though it looks like it's been running normally, at least on the surface).

1) If you are asking for help, please indicate the dimensions of your equipment.
2) This behavior may be due to uneven water supply, or from insufficient heating. I'll explain.
When the vapor of alcohol + water evaporates, energy is carried away, and you should have an equilibrium, but with a bias in the "alcohol output", i.e. the power taken off (cold water in the jackets of the condenser and dephlegmator) should be equal to the power input during the distillation process.

I have seen a picture like yours many times in my small experimental setup. Much attention must be paid to the balance of power and the "regulation point".

If you try to regulate (seize the moment) according to the temperature at the top of the column (the floor of the reflux condenser), then problems await you.
It is necessary to regulate the temperature in the tank and the temperature at the outlet of the tank (steam + alcohol, vapor phase). Usually it's even simpler: you supply power to the tank heater and watch (just watch) the temperature of the steam leaving the tank and look at the plates of the column. It is impossible to make a "closed control loop" according to the temperature of the steam at the outlet of the tank.

The control system itself must control either the power of the tank heater (1), or stabilize the temperature of the tank (water in it) (2).
In case (1), you adjust the water flow to the reflux condenser and condenser based on the alcohol outlet temperature and the alcohol exit rate (water to the reflux condenser).
Water to the dephlegmator controls the "reflux ratio" of your installation. This is also "the rate of alcohol output at a given power supplied to the tank."
In case (2) you will have a complete shutdown of the installation when the alcohol content in the tank becomes less than a certain value equal to your tank heating temperature.

If I didn't explain well, ask questions.