Offtake Temp Safety

[Rabid_Raccoon]

Hello all,

I have a rig that is used for distilling water and for the most part runs just fine. If I try to push a large volume thru it I can get offtake from the condenser that is steaming hot, even though the condenser jacket is still cool to the touch. This tells me that it is outrunning my knockdown capacity of the condenser and for what I am doing it is not a huge safety issue. (commercial stainless still we bought for water and essential oil production)

I don't plan on ever running alcohol through it, I am in process of applying for federal and state permits to become a legal micro distiller before I upgrade.

My concern is if someone were to push a load of wash for a stripping run, there may be output with high alcohol and high temps.

How scary would this be? At what point would someone be in the danger zone?

Thanks all!

RR

[Sporacle]

Don't push a large volume and understand the limits of your condensor, if your condensor is overpowered then it's vapour and sparks and AIT and flammable atmospheres and a whole world of hurt. Just don't over run your system and why would you tbh?:D

[Yummyrum]

Yes its quite a known fact around here that if your vapour speed is too high , it will blast vapour through the condenser at a higher rate than the condenser can transfer the heat out of it .

There has to be a certain minimum dwell time where the vapour is in contact with the surface to allow the transfer of heat through to the coolant medium .

The thickness of the condenser walls and the material it is made from will effect this also . Thin copper walls will transfer the heat faster than thick stainless steal walls .
Water will take more to condense than Alcohol .

So yes , as a general rule , we never run our boiler so hard that un condensed vapour comes out the end …. Its just plain stupid and dangerous .

[Rabid_Raccoon]

Let me clarify,

We dont get water vapor pushing out, we get offtake that is steaming hot in the catch vessel, or offtake that is really, really warm to the touch.

Thanks,

M

[Saltbush Bill]

One solution to the problem would be to buy a cheap power controller. They can be had from sellers like SD for around $50.
In theory this would allow you to properly control the heat input to the boiler.
Another thing to take into account is that water vapour and alcohol vapours act quite differently when they hit a condenser.

[Sporacle]

Sorry I assumed when you said steaming hot that you meant steam as in vapour, hence my reply on the steam and the implied alcohol vapour and associated risks. If its steam then don't get burnt, steam burns are nasty, expansion ratios of H2O are ridiculous but you may end up with really clean pores, see how you go
Posted at the same time as Bill

[Rabid_Raccoon]

Heya Bill,

I have a controller that is used every time we make a run. Especially the oil runs, they can get crazy bad fast without one...

The only time I have had really hot offtake hit the bucket is when I got impatient and cranked things up to 100% power to blast thru a water run.

No, really, I actually distill water here on the farm for feeding my bees and such.

RR

[still_stirrin]

Let me clarify,

We dont get water vapor pushing out, we get offtake that is steaming hot in the catch vessel, or offtake that is really, really warm to the touch.

Thanks,

M

Simple….your product condenser is too short.

Although you have condensed the steam (water in the boiler, right?), it still holds a lot of heat and that heat results in an elevated temperature of the condensate. Water (H2O) has a very wide saturation point, so it requires a lot of heat to boil and it likewise requires the removal of a lot of heat to condense.

And then, to lower the temperature of the condensate to or near to the temperature of the coolant’s inlet temperature you’ll need to have a long enough condenser (as Yummy said, “it’s about the dwell time”) for the heat transfer to complete. And this also requires a counterflow condenser arrangement where the coolant’s inlet and the condensate’s outlet are coincident (at the same end).

Parallel flow (condensate and coolant flows are the same direction) won’t allow the condensate to cool to the coolant’s inlet temperature.

Now the obvious….alcohol will behave (or misbehave) differently. Because the heat capacity of alcohol is significantly different from pure water, it will boil quicker given the same heat input. And the (measured) temperature of the vapor will be lower than pure steam. And the alcohol will condense at a lower temperature than the steam will as well, resulting in a product jar that “feels cooler” because it is.

So, the temperatures (scaler measurements) will be different for a boiler filled with water and the same boiler filled with an alcohol wash. And it will be even more pronounced when the boiler is charged with low wines at 30% ABV.

Does this help answer your questions?
ss

[Rabid_Raccoon]

Well, yes and no.

I understand the condenser issue for my still if I open the throttles all the way. I have what is essentially a Leibeg condenser with a 1/2" thruput and a 1" water jacket and I am looking at upgrading my rig to a 3" shotgun condenser to match my column size for those days we are cranking out big water.

My cooling water is a 500gallon buried reservoir with 600 liner foot of 1" pex buried under the footings of our canning kitchen. Runs hella cool and no ice to worry about =)

So, I got the condenser issue noodled out, just need to upgrade.

Let me rephrase my original question because my clarity sucks.

When shooting an alcohol run of any type, how warm is too warm in the collection jar before you would get freaked out and panic?? 90f? 100f? 150f? Is it %ABV dependent?

Thanks! Love this stuff.

RR

[Deplorable]

My target temperature for the offtake is always 60F since that's what my alcometer is calibrated for. Obviously I can't always get that since my supply if cooling water is subject to ambient heat.
On stripping runs, I'll tolerate a higher product temp than I will on a spirit run.
As long as your product condenser is knocking down ALL the vapor, you're good to go, but it makes determining true proof a pain in the arse.

[Demy]

In general it is a good thing that alcohol is at "environment" temperature, this also depends on the temperature of your water, if for example your water is 20 ° C you cannot get a distillate at 15 ° C but at most you can Point at 20 ° C. Surely you don't want your distillate "burn your hands", especially if you distill something with a delicate aroma risks that your aroma evaporates. I recommend a maximum limit temperature of 30 ° C (about 86 ° F) but it is only one of mine. If I understand your water is fresh ..... so your problem is to improve the cooling system (you're doing it) and enter less power in the boiler. The alcohol will behave in a diversity manner 'water but if distill something with little alcohol (for example in a stripping) you will have almost the same problems with water. They are just practical suggestions, others could say different things.

[Yummyrum]

On a stripping run I use gas and a 6’ long Liebig (1” over 3/4”) .
I have that gas burner fair cracking . I’m taking off at around 20liters an hour and the distillate is still coming out under 40°C .
On one occasion I did push to see how hard it could go , I had flames so far up the side of the keg that poo was filling my pants . I clocked it at a gnats dick under 30l/h and I was starting to see the beginnings of un condensed vapour:

I guess my point is that I don’t run so hard that my condenser is at its limits. Distillate temp seems to suddenly rise when you do .

Not that I use a thermometer to monitor it , but around 35-40°C is a good place for me . I am always sticking my fingers under the spout to rub and smell so I am always aware if the warmth .

Edit : thats at the end if the strip . At the start, it’s a lot cooler .around 25-30°C

[NormandieStill]

I run my stripping runs at a point where the distillate comes out at around 40°C. I do feel this helps to air out some of the more nasty volatile stuff but it's just a feeling. That said, when your distillate is already coming out hot, you've used up most of your margin in the system so when something goes wrong (not if) it takes microseconds for it to go badly wrong. If I suffer a coolant problem during a stripping run, I've got less than a second before I'll see vapour out of the end of the tube. The same problem during a stripping run could still leave me 30 seconds or more before the liebig was overpowered.

As with driving (or any remotely dangerous activity) it's best not to run the system at it's limits.

[still_stirrin]

When shooting an alcohol run of any type, how warm is too warm in the collection jar before you would get freaked out and panic?? 90f? 100f? 150f? Is it %ABV dependent?

Well, “too warm” certainly is %ABV dependent.

If your distillate is 170 proof (quite typical for a spirit run with a potstill), then 185*F is the saturation temperature where the mixture can exist at both liquid and vapor. Below that, and it should always be a liquid. Personally, if your collection jar is warm to the touch, it may be too warm, and you need to cool your coolant reservoir temperature, speed up the coolant flow slightly, or reduce your boiler heat input (slow vapor production).

And if your distillate is 190 proof (if you’re running a reflux still), then the saturation temperature is lower, 174*F. But, you should never let the distillate collect at anywhere near that temperature because you’ll have alcohol vapor well above its flash point (explosive) and with enough vapor and air and you could become a “firework” like a 4th of July novelty. Again, if the collection jar is warm to the touch, you need to adjust the heat input or increase the product condenser’s coolant flow.

Be safe, responsible, and discrete…..not stupid!
ss

[Rabid_Raccoon]

Thanks all, I really appreciate the input. All makes sense.

For our uses, hot doesn't matter much since we aren't messing with anything flammable except for giving me a metric of how my rig is running.

After I get done with my distilling school and fed/state paperwork I will feel better about firing up the good stuff.

RR