Can't maintain temperature during distillation.

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Can't maintain temperature during distillation.

Postby JTrin » Sunday May 22, 2011 10:49 pm

Hi,
Been having lots of fun with making spirits, but we can't ever seem to maintain the temperature of our unit between 79-84 degrees C, which we were told is the best range for the one we've got.

It's all well and good, but because we're not getting much over 45% alcohol out of the still, we're not getting as big a yield as we'd like, therefore we're less fun at parties. So far the most potent stuff we've had was 70%, but we've been told it should be up around 90% with what we're using.

We have a copper reflux head that a very experienced distiller made for us, the details are:

The reflux tower is approx 550mm in height and is made of 32mm diameter copper pipe

The outer (water jacket) is 50mm copper pipe

The water inlet & outlets are ½” rigid copper

The condenser unit is over 1 meter of coiled 3/8” annealed copper tube in a 50mm jacket

All joints are brazed and or soldered (lead free) to ensure strength and a proper durable seal

The column is packed with stainless steel wool - pot scrubbers from go lo we stretched out and matted together.

Image

We bought our boiler from the same guy, figuring if he'd made both boiler and head, they'd work together. It's a 50L keg with a 2200W element in the bottom.

Our thermometer has been checked and is accurate within +/- 0.1 of a degree.

We're just not sure what would be causing the constant rise and crash in temperature. Occasionally it will sit in the low 60s before rising again and getting way too hot! The thing just won't find a temp it's happy to sit at, no matter what we do with the water flow rate. We've been recommended to run it at a litre a minute (but have also been told that this is pretty high).

It's been suggested that 2200 watts in the boiler might be too hot, but we did this on a cold night outdoors and had a fan pointed at it, and had it sitting on a mag wheel so the air could get underneath it as well.

It's also been suggested that the condenser bit where the spirits drip out could be a bit narrow, but if so, we're not sure how to compensate for this.

I'm pretty sure it's a decent setup, the guy really did know what he was talking about and it's amazingly well made, but we just can't seem to make it work. Any suggestions? We'll try pretty much anything if it means we get a drink at the end.

As usual, thanks in advance for any suggestions or advice. :-)
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Re: Can't maintain temperature during distillation.

Postby JTrin » Wednesday May 25, 2011 8:10 pm

I think we may have somewhat fixed the problem. So many variables though, it's hard to tell.

Today was rainy, so we had to set the boiler up inside the shed. This meant we had to use a longer length of hose between the tap and the head, and also we were on concrete instead of pavers. The night might have been a little cooler too.

Got a pretty decent yield out of it this time, of about 4 litres averaging out somewhere between 75% to 80%.

So we're guessing it's a combination of the 2200W element being a bit too hot, the length of the hose going into the head being too short, and perhaps even the surface we were doing it on.

Still, it would be awesome to know what you guys think about these factors - how come it worked so much better when all we did was move five meters into the shed?

What do you reckon?
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Re: Can't maintain temperature during distillation.

Postby Tipsy » Thursday May 26, 2011 1:25 pm

JTrin wrote:It's been suggested that 2200 watts in the boiler might be too hot, but we did this on a cold night outdoors and had a fan pointed at it, and had it sitting on a mag wheel so the air could get underneath it as well.


I don't know enough to give you an answer, but something to think about is some people insulate their column so as not to get temp flucuations from wind.
A fan pointing at it might not be good.
The element might be too big and then be flooding the column, but really I'm just guessing. :roll:
Good luck with it.
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Re: Can't maintain temperature during distillation.

Postby hirns » Saturday May 28, 2011 7:42 am

Can you post a pic of where the thermometer sits in the column. Between 79 and 84 degrees seems problematic to me as whilst alcohol evaporation point is @79 degrees I've always run stills at 93C. If been doing it infrequently over too many years to remember where I first got that number or it could be the consumption of the regular 90% runnings that I get. I've used two different stills in my experiences, one a still spirits model http://homedistiller.org/image/AV25Lreflux.jpg and a home made stainless unit similar to http://homedistiller.org/image/AV25Lpot.jpg but with a 50mm 500mm long reflux tower. The tower sat on a 50l keg with a 2400 watt element.

The homemade unit with 23l of wash would make it to 93C and sit there till you had collected the 4l of spirits(you know to throw the first cup don't you) and would only start to rise once the alcohol had been evaorated off. I don't think it would be the element, but it may be a very efficient 2400w element.

I would be checking your water pressure, as a long hose will reduce fluctuations in pressure. Even know you are running only a small amount through the still, if you are doing it in the afternoon when the neighborhood is showering, let alone your own family and the washing machine it will make a huge difference. Turn the kitchen sink on to a trickle and then go turn on the shower, flush a toilet etc and see what happens(are you on mains of a pump).

If things were good in the shed then it could have been the wind as Tipsy suggested. Don't underestimate the effect of a good breeze against the keg. When against the tower it should only increase the time taken to distill the spirits.

Check where the hoses go onto the tower, as the tower gets hot so to does the plastic and I've seen them kink stuffing your flow rate.

Finally, have you checked the alc of the wash before you put it in the still. If the wash had not fully fermented and contained only two L of alcohol, yet you extracted four litres of runnings then you can see the problem.

Hope that that provides you with a few ideas.

Cheers :)
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Re: Can't maintain temperature during distillation.

Postby JTrin » Monday May 30, 2011 10:06 pm

Thank you so much guys!
I didn't even twig to the water pressure/hose length situation, but I really think that could be what it is. As well as doing it inside so the wind wasn't a factor. So we'll keep doing what we're doing.
For the record, the thermometer sits at the very top of the column.
Thanks again for the advice.
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Re: Can't maintain temperature during distillation.

Postby McStill » Monday Jun 06, 2011 10:32 am

That still is a poor design is why your temps fluctuate, the cooling jacket is way to big and will not respond properly to coolant flow changes.

Also, I recommend you do a lead test on those solder joins, that guy on ebay that makes those units is known to use lead solder in his stills that will leach into your booze, this is a big problem if you end up with lead poisoning.

I've pulled a few of these apart for some friends and resoldered them with silver solder, so I do know what I'm talking about here :wink:

Cheers.
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Re: Can't maintain temperature during distillation.

Postby spud1700 » Tuesday Jun 07, 2011 4:17 pm

Hi All, new to forum but not distilling :) A well designed reflux still should pull 95% with ease, a lot of people have those off ebay. I had a mate buy one and he had no end of problems, eventually it was hung on the wall and he got another still. There is nothing wrong with your the keg or element though on a positive note

A few things going against it, not sure what advice to give you to fix your problems though.
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Re: Can't maintain temperature during distillation.

Postby JTrin » Wednesday Jun 08, 2011 6:34 pm

Sweet, thanks so much for the heads up on the still.
Admittedly we only bought that one because it seemed cheap and we didn't want to shell out too much on a hobby we didn't know if we'd stick with. It doesn't surprise me that it's not much chop - I did have my suspicions.
Now we love stilling though, and commercial spirits make us very sick and sorry the next day. So yes, we'll probably end up hanging this one up on the wall and upgrading when we can.
Thanks again, it's great to hear from knowledgeable people.
Any recommendations for ones to upgrade to would be much appreciated too :)
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Re: Can't maintain temperature during distillation.

Postby McStill » Wednesday Jun 08, 2011 7:45 pm

Hi JTrin,

I recommend you take a look at http://www.aussiehomedistiller.com/2-dr-boka-reflux-pot-combo-t220.html

There's a lot of stills on the market but they arent really the best designs, the brew shops and ebay sellers will give you a huge sales pitch and very little in the way of what they actually claim their stills can do.

I build stills for people as a hobby using proven designs that have been around for a long time, I let people using my stills tell the story :wink:

You'll see on my website the kind of pride I take with my work, others make claims and sales pitches where I make stills that work :mrgreen:

Send me a PM if you want :wink:

Cheers.
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Re: Can't maintain temperature during distillation.

Postby nictron » Friday Jun 17, 2011 4:09 pm

holy crap! that looks the goods.
today, the missus said "You cant just put beer taps on everything." BIG mistake.
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