Preheater design question

[NZChris]

Thanks for that - "I'm not going to talk about THAT - it's not part of the distillation " - lol

We have speculated somewhat about what happens inside the "onion" - and here is the answer - from Hennessey - there's a brief "cutout" shot around minute 4 !

https://www.youtube.com/watch?v=as4k-eFpoyI

The commentary on the preheater at 5 minutes made no sense to me.

[Pikey]

Not the commentary Chris - there is a brief cutaway view of the pipe bends within the preheater - at just after minute 5. use the pause function to stop it and see what's going on.

[Edit ; Note too that they DO use the bypass valves to prevent the prheater getting too hot it seems. I prefer your second Liebig myself - but there we go, we can do that, they probably can't maintain the integrity of their distillation by doing so.]

[NZChris]

Which shows it as being similar to mine.

[Pikey]

Which shows it as being similar to mine.

Yes it does

[SaltyStaves]

Not the commentary Chris - there is a brief cutaway view of the pipe bends within the preheater - at just after minute 5. use the pause function to stop it and see what's going on.

That clears that up for me. Thanks. Downward incline makes sense too.

[Pikey]

Okay - I think we need a TIME _ OUT For SAFETY here.


We are getting into new ground for everyone except NZChris AFAIK.

To any newbies wanting to try this - It is vitally important that anyone who tries to go down this clearly advantageous path be completely aware that the preheater MUST be vented since the air trapped in the enclosure WILL build up a high pressure, as the wash warms up. Dorn's still has that little curly pipe to do this and Chris has a separate head and Liebig to do this. - I am likely to follow his example.

Do NOT attempt the preheater without venting and DO consider the excaping alcohol vapours as the preheater gets up to temperature
OK 'Nuff said.

[Pikey]

I cut the first of the cylinders just before it got dark

Boy is this going to need some cleaning ! Amazing how crappy it can get with just mains water for a few years. Anyhow I'll post pics when it gets light.

Now I'm thinking that it's bigger than my pot by a fair amount, but maybe I'll keep it that way - gives me the facility for a bigger pot at some stage in the future. Many years of added "Fernox" has had an effect on the insides of the coil too I'm unsure I could EVER get that clean enough to drink out of.

[Pikey]

Pictures ;

Inside could do with a bit of a clean !

[Pikey]

Couple of minutes with a stiffish yard brush - you can see th colour coming through already !

This is going to clean up Okay !

[EDit - we just has a light shower and it's looking cleaner already.

Now I have to decide whether to cut it down or not. AS shown, I calculate that from the high point of the bottom, it would hold 97 litres, completely filled to the brim, so probably could be usable to around 80 litres.

I currently run a 25 litre boiler, but have designs on a larger one. I think that so long as the element is covered, this woud be ok with a 25 litre charge allowing me room for expansion later. - Anybody see any snags ? ]

[Pikey]

Decided to give it a go (forming the flange) as is - I've never done one before

Doesn't look too bad and a quick going over with oxalic acid is beginning the cleanup !

[Edit - that flange has stiffened it up a treat ! ]

I've not even given up on the coil completely yet !

I'm not intending to use all the coil, likely just the first turn and a half - as NZC has done. Outside is cleaning ok - so I'll see what a pan scrubber pulled through a few times in acid of some sort can do.

[Bart Meijer]

Intresting post !
Been thinking along these lines earlier, thinking about making a Bain Marie still fed with steam wand.
But this might be the idea to work a double kettle.
hmm, where is me think tank?

Cheers Bart

[Yummyrum]

LOL , here's my one and only attempt at a pre-heater set up I did a few years ago .This was my look into continuous strippers to get a feel for how much heat could be transferred from the condenser to the wash ....never had time to take it further .

I used a fountain pump to pump wash through the Product condenser of my VM head which I plugged and bunged as a Pot head and had no packing ....so it was a pot still stripper .
The valve at the bottom of the VM shotty condenser adjusted the flow of wash ....too fast and it was not heated enough , too slow and the exiting strip would be not fully condensed ...hence the Liebig to further cool

The pre-heated wash ended up in the Keg to be stripped next .
I had another liebig attached to the condenser to further cool the product as I found at the point where the wash become nicely heated , the exiting product was not fully condensed .....It was a few years ago so I'm not prepared to argue the finer point s now

[yakattack]

Yummy. Instead of dumping the preheated into another keg, you can circulate it back into the same bucket. Allowing you to run it faster for proper cooling, while still heating up that charge sufficiently.

If you then start struggling at the end of the run, cut that pumo, and run either a secondary bucket of water or tap water for the final cooling.

Just a thought for ya. Carry on.

Sexy rig btw

Yak

[Pikey]

A pre-heater is on my to-do list, after I finally get my tiny still going and then the bigger one...

I think it would work best if you start with the boiler, say, half full; distillation would start much sooner. Then the next wash would be partly pre-heated already, for you to top up the boiler....

Geoff

NZChris - I know you normally do equal volumes in both and have done "double distils" using a smaller volume in the preheater, but I'm wondering - have you ever done a "half volume" in the still and a full volume in the preheater ?

I have a 25 litre and a 50 litre and was wondering if it would make sense to start with the 25 litre and 50 litres in the preheater, then to do the distil and drop the 50 litres from the preheater into the 50 litre pot and switch over to using that one from then on in.

I was wondering if you have any information as to how warm a double charge in the preheater would get, since in the early stages the temp differential would be large, I would think it should get almost up to full temperature ?

[NZChris]

Energy wise, it seems to make sense to put the smaller charge in the main boiler first as the greatest heat transfer happens at the greatest temperature difference, but I've never had a reason to try it. If the preheater doesn't have it's own Liebig and is teed into the main Liebig it would make sense to go that way so that alcohol from the preheater doesn't fool you into thinking you are still getting production out of the main boiler when you're not.

I've never bothered with a thermometer in the preheater. Sometimes it distills, sometimes it doesn't. It's latest run, in winter, the wash had gone much colder than usual before stilling day and it didn't produce anything. I'd gone to the trouble of automating it's Liebig and it never turned on once

[Pikey]

Energy wise, it seems to make sense to put the smaller charge in the main boiler first as the greatest heat transfer happens at the greatest temperature difference, but I've never had a reason to try it. If the preheater doesn't have it's own Liebig and is teed into the main Liebig it would make sense to go that way so that alcohol from the preheater doesn't fool you into thinking you are still getting production out of the main boiler when you're not.

I've never bothered with a thermometer in the preheater. Sometimes it distills, sometimes it doesn't. It's latest run, in winter, the wash had gone much colder than usual before stilling day and it didn't produce anything. I'd gone to the trouble of automating it's Liebig and it never turned on once

no I'd still use 2 condensers - I agree with you completely there. Might even do them in series with the water going through the Preheater condenser first then down to the still condenser, since the still condenser would be at higher "knockdown" temp. - I'm now thinking say 30 litres in the 50 Litre pot and 50 litres in the preheater - forget my little 25 litre pot completely. I've just never used the 50 litre and it's a bit scary to run that in a complicated config like this straight off - I guess I need to do 1 or two runs in "simple" mode first. This would really go well with my 220 litre fermenters.

I do like to "see" what's going on so I'd probably add a thermo in the preheater. Might even produce a graph of what happens. I've now "Flanged" the cap as well and they fit pretty well, but need to solder some "Sideways restraints" into the junction.

From a previous conversation, I'll probably Pump the wash into the preheater - I just happen to have one of these lying about - Just needs mending

http://www.ebay.co.uk/itm/Jabsco-ParMax ... Swk5FU1U0T

[Edit - yes I think it makes sense "energy wise" too - and also "time wise" - If we can get product running say 1/2 hour earlier, then we are saving there as well. Also the use of more heat energy, will waste less cooling water. ot huge perhaps - but when all added up, down the pub 30 minutes sooner - with money for extra 1/2 litre saved

[NZChris]

The cooling water from my Liebig is way too hot to use in another condenser.

[Pikey]

The cooling water from my Liebig is way too hot to use in another condenser.

OOps - edited behind you !

I hear what you say - I'm quite anal about the temp of my cooling water - mine would deffo be cool enuff !

[NZChris]

[Edit - yes I think it makes sense "energy wise" too - and also "time wise" - If we can get product running say 1/2 hour earlier, then we are saving there as well. Also the use of more heat energy, will waste less cooling water. ot huge perhaps - but when all added up, down the pub 30 minutes sooner - with money for extra 1/2 litre saved

I don't think it would make enough difference to get excited about, certainly not enough to get an extra pint in before closing time. Your first charge will be finished sooner, but your second charge will take longer to get up to temperature.

[The Baker]

Pikey, you said, " I'd still use 2 condensers ."

That would be for safety and seems to assume that the pre-heater chamber is sealed.

But the Charentais still (find it on Google) has a fixed pipe from there to the boiler, with a tap. And no extra condenser, but the pre-heater chamber appears to have a hat on it.
So:
If there was a pressure build-up, that would lift the hat and release the excess steam/ vapour. But that would be a waste and the operator would avoid it.
The operator could tell by putting his hand on the pre-heater if the contents were very hot and release a little, gradually (?) into the boiler, or
dump as much as would fit into the boiler, and then
lift the hat and refill the pre-heater.

Little if any delay except he would have to at some time (when he judges the wash is spent) draw the fire (or close the dampers), wait a short time for boiling to cease, drain the boiler via the drain tap, and re-fill with new hot wash from the pre-heater....
And re-set the fire for distilling.

These oldies had the system worked out.

Geoff

[NZChris]

It's nowhere close to being that difficult Geoff. I don't know what drawing you are looking at, but they usually had a bypass valve to allow them to direct the vapor around the preheater should they so desire. Also note that they were not lagged, so there would be substantial heat losses, and the runs take a lot longer than your average hobby scale stiller would want, meaning more time for that heat loss.

[The Baker]

It's nowhere close to being that difficult Geoff. I don't know what drawing you are looking at, but they usually had a bypass valve to allow them to direct the vapor around the preheater should they so desire. Also note that they were not lagged, so there would be substantial heat losses, and the runs take a lot longer than your average hobby scale stiller would want, meaning more time for that heat loss.

Not difficult at all but the explanation is a bit wordy.

Geoff

[Pikey]

Pikey, you said, " I'd still use 2 condensers ."

That would be for safety and seems to assume that the pre-heater chamber is sealed.

But the Charentais still (find it on Google) has a fixed pipe from there to the boiler, with a tap. And no extra condenser, but the pre-heater chamber appears to have a hat on it............

Geoff, Chris's preheater is based on the Charentaise, which he found the design for some 30 years ago, long before "Google..." However he made a couple of modifications, one of which was the second condenser, which not only vents the preheater, but overcomes any issue of "Steam or vapour" escaping, (through the "Hat" ) by simply condensing any such and collecting the distillate.

If you look at my "Time out for safety....." I state categorically that it is Essential that the preheater be vented and explain why.

You can see that early on, I had a decision to make - ie "Bypass valve" or "Fewer heating coils". As Chris says the Charentaise uses a bypass valve.

There really isn't much else which can be changed. The main elements of mine are now fixed and I'm just trying to decide on the number of heating coils to incorporate. When the heat exchanger was part of a heating system, all the coils were used - so that represents the "Maximum efficiency" position. For various reasons I'm trying to reduce that number, because we have a "target" whereby, the distillation completes and the next charge is sitting fully ready to enter the still and be replaced in it's turn by a complete new charge, simply by opening a valve and operating a pump.

Adding wash a little at a time to an already part complete distillation, is not part of my plan. Runs will continue to be discrete, just "continuous" in that the gaps between "production" wil be eliminated as far as practicable.

If you take a look at the Hennessey preheater I linked to, you can see what they do inside the pot too. If you're wanting to make a preheater as you said earlier, I think you'll find most of what you need on this thread - It'd be good if you keep us up to date on how it's going

[Pikey]

been doing other things for a while but have now formed the flange on the lid and remarkably they're a pretty close fit.

I'm now thinking I need to solder a flat strip of copper inside the lid, around the circumference, to locate the lid and give me something to form a dough seal against.

Still struggling a bit with the coil. NZChris has 1.5 turns of .5" copper, mine is 28mm (1") and to use the existing holes, will need to be 2 or more full turns. This will leave the inlet about a foot vertically above the outlet. If I do it like this, I will be able to use my existing knock down condenser directly onto the 1" outlet.

I should also be able to use my existing column (1") on my larger boiler (10 Gallon Imperial) by simply making an adapter to join it to a tri-clamp.

I'm wondering whether what will effectively be a 3 turn Worm in 1" will knock down the vapour well enough at the start of the run, so I won't need to use additionsl cooling water and whether it will transfer enough heat from the vapour to the waiting wash.

All the threads which discuss worm diameter seem to want to make them as small as possible but that "Hennessey" vid shows the pipework 2" or more I think but that has a couple of Sharp changes in direction within the Preheater rather than coils.

[Kareltje]

Looking for "Moonshine bible" resulted in several results.
Alaskan Bootleggers Bible
Complete Distillers Bible
Moonshine bible Facebook

We'll see which is usefull.

Please do let us know if you find any good ones

I'd follow the approach Stillstirrin used in post #2 "Distillation of alcohol from farm products" - on free google books, it is probably the best bet - I just got caught and paid a few quid for a reprint of "Public domain" info.

i have many of the newer books, but I love the old stuff because they spent the time and effort in understanding to the best of their ability - didn't just compile a load of "Internet info" without thought and research

Of course!
Downloading now. Rather dark, but there are certainly ways to make it more clear.

Interesting discussion you have here. Reminds me to think and experiment really good before I ever make a preheater system.

Edit: still downloading! It is really amazing (and inspiring!) how thoroughly things are explained. I envy this attitude.
Edit Edit: But BJFC: when I open the downloaded file (took 3 hours!), I see just black pages. BJFC!

[NZChris]

This will leave the inlet about a foot vertically above the outlet.

As long as you know you won't be running charges that don't cover the worm, a foot should be ok. I have done a spirit run in my preheater that would have been way less than that, but that was for entertainment, not something I would plan for.

My gut feeling, after seeing two preheaters operating, is that the worm should be in the bottom third of the charge, maximum. Mine would be much lower than that.

[NZChris]

I'm wondering whether what will effectively be a 3 turn Worm in 1" will knock down the vapour well enough at the start of the run, so I won't need to use additionsl cooling water and whether it will transfer enough heat from the vapour to the waiting wash.

I never start a preheater run with the cooling water turned on.
You could fill a preheater with as many turns as you could fit in one and you would still have to use cooling water eventually, but not at the start. If you want to cut back on cooling water costs as much as possible, control the condensate temperature by automating the water flow rate.

[Pikey]

This will leave the inlet about a foot vertically above the outlet.

As long as you know you won't be running charges that don't cover the worm, a foot should be ok. I have done a spirit run in my preheater that would have been way less than that, but that was for entertainment, not something I would plan for.

My gut feeling, after seeing two preheaters operating, is that the worm should be in the bottom third of the charge, maximum. Mine would be much lower than that.

Yes bottom third it will be.

I'm wondering whether what will effectively be a 3 turn Worm in 1" will knock down the vapour well enough at the start of the run, so I won't need to use additionsl cooling water and whether it will transfer enough heat from the vapour to the waiting wash.

I never start a preheater run with the cooling water turned on.
You could fill a preheater with as many turns as you could fit in one and you would still have to use cooling water eventually, but not at the start. If you want to cut back on cooling water costs as much as possible, control the condensate temperature by automating the water flow rate.

Naturally, if I can save a few bob in water, that will be good as will the savings in ELectric and also TIME - The main reason I'm thinking 3 turns is so I can stretch the coil and use the existing holes.

Where do you turn your cooling water on - I'm thinking somewhere between 50 & 60 C ?

[NZChris]

Where do you turn your cooling water on - I'm thinking somewhere between 50 & 60 C ?

Currently, the controller keeps the output around 24C-28C.

[Pikey]

Where do you turn your cooling water on - I'm thinking somewhere between 50 & 60 C ?

Currently, the controller keeps the output around 24C-28C.

That's pretty cool - I thought you were just "On-off" - have you upgraded to a variable speed pump ?