StillSmart

Nah! I'd be lost before I got there.

You see, in my little mind pressure is what you get in things like a 'pressure cooker' or any enclosed container where expanding gas or liquid is prevented from escaping by means of closure seals and explosion of the vessel is prevented by means of safety valves.

The kind of pressure you're talking about is way above my pay grade (sic;interest).

Although my head works as well as I want it to I have always tended to average things and avoid letting technicalities become the focus. In other words I've always sought enough knowledge to be able to do what I wanted and then I'd work on perfecting my performance at that thing. That's not to say I have no ambition. I most certainly do but my ambitions are always in pursuit of doing and producing - I'd make a lousy nerd.

Take Home Distillation; I wanted to learn how to distill my own spirits - I can do that now and my still produces an adequate sufficiency of clean ethanol for my purposes. Now my focus is improving the flavour and enjoyment of my end product - Happy Me

Take Building a Bigger Still; Once I discovered that I enjoyed what I could produce with my Airstill I wanted to build a bigger one. Part 1 - the Pot Still - is completed and working, Happy Me again Part 2 is the VM Column - this is in the process of being completed and will be running by the end of June. - that'll be me happy as a pig in shit

At the end of the day I'm not a Vulcan. I'm happy to leave all the technical stuff, the exploration, going where no distiller has gone before, etc., to those who enjoy such things and if you guys come up with something useful I'll happily adopt and exploit your discoveries

I only posted because Ant used the term "Constant pressure control " which, without the explanation, led my tiny little mind to go "Holy Shit! you can't say that - the children might pick it up! "

Anyway, thanks for the info Brian and no offence Ant - wasn't having a go just a little OTT about safety!


AM

No offence taken and thank you Brian for explaining.

The control is to detect pressure above atmospheric. Yes there is always about 14 pounds per square inch even in what you think of as no pressure. The difference being controlled is less than 1 psi; to quote:

"Throughout the process it is necessary to monitor the pressure in the evaporator tank. It should be 3 to 5 mm Hg. of Art. (Or at least no more than 10 mm Hg. Art.). Pressure changes in alignment by a few percent power at TENe."

By automatically using pressure feedback, to control the heating, output is maximised and flooding avoided.

This is how to do it from a clever Russian.

http://www.svoimi-ru-kami.narod.ru/Mete ... rpress.htm

and

http://translate.googleusercontent.com/ ... NhxlOF2Aow

Brian is absolutely correct about the pressure - but is only slightly higher than the ambient air pressure.
I have a 0-15 psi over a 270o gauge and if my column floods it can be spewing reflux out the top of the column and the pointer wont even budge off the zero stop pin (BTW I don't let it get as far as that after the first time it happened)

We are talking about pressures much much less than a child blowing bubbles with a straw in a glass of fizzy pop, the eastern Europeans who exploit pressure changes are using very sensitive electronic switches - the rest of the time when we say we should avoid pressure in a still (even though this is not strictly true) we are talking about it being open to the atmosphere for safety.

When I welded the keg I pressure tested it to 15psi with compressed air- I recently using water vapour got it up to 5psi using a cork and a weight in the neck of the boiler while testing a switch I'm hoping to use as a power cut out device. It was really hissing and making a racket by the time it got up to 3psi - I think that's about as high as we should consider if looking at cut out.

I know that's not what we were talking about - but I think its valid since pressure was brought up.

ant wrote:So what is the shortest you have run the column so far with the Spp?

I only have the one column - it has 36" of SPP in it - my goal is not to run a short column but to get the best purity out of the one I have - so I wont be experimenting with this any time soon.
However - I will be running with 12" of SPP before the end of the summer, this is the top half of my column and I'll be using it in this "stumpy" config for rum (click to see full size - its a shit photo in bad light but you get the idea)

Capt-Cudellez wrote:Brian is absolutely correct about the pressure - but is only slightly higher than the ambient air pressure.

Yes a fraction of one pound per square inch

Capt-Cudellez wrote:I have a 0-15 psi over a 270o gauge and if my column floods it can be spewing reflux out the top of the column and the pointer wont even budge off the zero stop pin (BTW I don't let it get as far as that after the first time it happened)

Exactly what the pressure control prevents.

Capt-Cudellez wrote:We are talking about pressures much much less than a child blowing bubbles with a straw in a glass of fizzy pop, the eastern Europeans who exploit pressure changes are using very sensitive electronic switches

Yes I know that is what the links I posted show. Brian originally drew my attention to them. Sensitive comparators but quite cheap I believe.

Capt-Cudellez wrote:- the rest of the time when we say we should avoid pressure in a still (even though this is not strictly true) we are talking about it being open to the atmosphere for safety.

well yes of course I do know that also though it was never what I was referring to.

Capt-Cudellez wrote:When I welded the keg I pressure tested it to 15psi with compressed air- I recently using water vapour got it up to 5psi using a cork and a weight in the neck of the boiler while testing a switch I'm hoping to use as a power cut out device. It was really hissing and making a racket by the time it got up to 3psi - I think that's about as high as we should consider if looking at cut out.

If you fill the vessel with water before applying the test pressure you can conduct a hydraulic test to destruction if necessary, without creating a shrapnel bomb. I realise you were using a system to safely vent the pressure if it increased but if you want to know what pressure a vessel can take that is how you can test them safely.

I actually believe we should be cutting out at a fraction of one psi rather than 3; using the sensitive but reasonably priced electronic comparators referred to in those links.

Capt-Cudellez wrote:However - I will be running with 12" of SPP before the end of the summer, this is the top half of my column and I'll be using it in this "stumpy" config for rum (click to see full size - its a shit photo in bad light but you get the idea)

Yes that is the configuration I was curious about. I will be interested in the results when you do this.

ant wrote:Yes I know that is what the links I posted show

Sorry Ant, I missed your post - looks like we were posting at the same time. I'll have a look at those links when my head isn't so sore,had too much red last night.

No probs mate.

Looked up the UK price and they are less than £8 each, plus vat and postage I expect, from Farnell who are not always the cheapest of suppliers. Need to price and build the rest of the circuit as well of course but not a lot in total I think.

http://uk.farnell.com/freescale-semicon ... dp/1555605

Capt-Cudellez wrote:...
Yes I ran with and without the BB - only difference was the power it took to flood it, 1600w without and around 2200w with. ...

Now that is really interesting. It shows that the dia at the top is not the only factor effecting when it floods. Feeding it with concentrated vapour reduces flooding and allows more power to be used. This makes sense of comments I read about using a short fat column to feed a taller thinner column. The comments were from experienced users on Artisan, made while observing a youtube video of just such a glass column. they felt it would enhance stability to have the lower column feeding vapour to the upper column. It can be hard to get your head around what is actually happening and why the upper dia is not necessarily a fixed limiting factor on when the column floods. I think your bubble ball is probably a better option than a fat column full of spp if only for reduced mass. Nice to get a handle on why the spp might work that way though.

Remembering other comments I have read I am beginning to think the bottom and the top dia have more effect on flooding and driving power than the central dia. Bubble ball at the bottom, 2" column with a 4" head (including a short spp packed 4"column) might allow a lot of power before it floods. Best of different worlds as the 2" would use smaller spp and have more theoretical plates per length for better purity in less hight. Also reduces total mass over using 4" all the way. Might just flood where the 4" meets the 2" instead of at the top. Not sure on that one, could depend on just how much 4" you use.

I could be wrong in my interpretation of other peoples results and comments but I think I might try it that way as it seems to make sense to my limited understanding that it should work well for spp use. I am no Vulcan myself, I'm not that good, not even a half Vulcan Spock. Definitely Sci-fi though so I like to take the best of what I can find others have done and try to make something slightly different.

the pressure controller looks to be about a £20ish build. Farnell looks like the best supplier. More the time and effort that is off-putting than the cost. you still need a physical gauge to calibrate it with.

Might make the effort after I have some stainless put together.

Something I forgot to add - I know the SPP is working well as the mid column temp (above 24" of SPP) reads a good 0.5 - 0.6 oC cooler than when I ran scrubbers, so the packing must be stripping out a good lot more water that the scrubbers.

I have now read those links, and that looks like a good idea to control the power - most of the Russian and eastern European punters look to be running small diameter columns at much lower powers than I'm dealing with, so there would still be a level of experimentation needed to crack that I think.
I'll definitely be considering it, but not something I'll be looking this year before winter set in.

ant wrote:I actually believe we should be cutting out at a fraction of one psi rather than 3; using the sensitive but reasonably priced electronic comparators referred to in those links.

Now I've read those links I know what you were saying here, I wasn't talking about 3psi as a way of controlling the power, but as a safety cut out, when it gets to 3psi it kills the power for 30 sec and sounds a buzzer as something is seriously wrong. I also have a manual ball valve to dump the pressure though the cooling water tank - still need to source the hoses for that, but that's the plan.

Capt-Cudellez wrote:...I wasn't talking about 3psi as a way of controlling the power, but as a safety cut out, when it gets to 3psi it kills the power for 30 sec and sounds a buzzer as something is seriously wrong. I also have a manual ball valve to dump the pressure though the cooling water tank...

Ahh I see. That should work well I think. Dumping the vapour through a depth of cold water should trap most or all of the ethanol in the water. A nice safe, simple and effective method to avoid any atmospheric venting.

I looked more closely at the pressure circuit and it is actually just a digital pressure gauge as it stands. Since you need a physical one to calibrate it anyway I wonder what the advantage is supposed to be. I showed it to my half Vulcan mate Tom (Yes we call him Spock) and he thought the components used were a bit outdated and is willing to make up a new circuit based on a PIC chip with fewer parts and more functions i.e. this one will control the heaters like a PID controller for temperature. He will write the new code to program it all. Time will tell how that goes but he is good when he finds the time and it beats building the other one myself. I couldn't do the new one as I don't code.

So running my "stumpy" still right now.


Above the bubble plate its got 11" of SPP, 2x SS scrubbies, and some copper foil for sulphate removal. I'm putting in 1900w and pulling 95%+ at 1.6l/h.

I'm super impressed that such a short column is able to pull such high ABV. I now have no doubt that someone with a short still like a T500, charged with strip would be able to achieve azeotrope with this packing, it 'might' be possible from wash, but I think thats probably pushing it.
But you would need power control, as in my experience this packing holds on to so much liquid that you get flooding above 1600w (on a 2"), I can push slightly higher due to the bubble plate.

CC

Hi captain could your stubby column reach azeotrope without spp if not what percent increase is there, the column on the super reflux is only 8" but with good packing and power controller it can reach 93/94abv from wash, my original thought was spp might reach azeotrope with this Little column wich would make the purchace price worth it but not so if it only increased through put
cheers

billmcc wrote:Hi captain could your stubby column reach azeotrope without spp if not what percent increase is there,

-----------------------

No idea as its the first time I have ran this config - but I'll bet no, as it could still be a tricky with the full column using stainless scrubbers, if it was slightly off plumb it would pull 95% but not that last little bit.
There is a huge difference in quality from my 94% T500 output, and the 95.6% output on my VM.

If I had more time on my hands, I might charge with something similar to try that config out with scrubbers, but as I was not trying to reach azeotrope with this shorty, I was trying to run a slightly lower ABV to push more flavour in. I'll probably be looking at a choke above the output to force more output out the product arm (reduce the amount of being returned as reflux down the column) and hopefully this will reduce the ABV slightly.

So dont hold your breath on getting numbers from me anytime soon, but my curiosity might get the better of me sometime, and I'll do it to find out.

I did a few reading on my narrow range alcometer and this is what the stumpy was putting out.....

Sampled jar 6 (from about 2.5l into the run) measured 96% @ 21.3oC
Sampled jar 11 right off the still (just over 4l into the run) measured 95.2 @ 19.2oC

I don't have a 20oC reading, so it may or not be azeotrope, but its close for sure. I was also running with the valve fully open, so if it wasn't 95.6% then closing it down would surly push it up a point or two.

Thanks for the reply capt