please set me straight - VM build

[choppinlow]

I have read many posts on VM designs but I still cannot get something clear in my mind.

Does the take-off diameter solely determine minimum reflux ratio, or is it any restriction/diameter reduction in the vapor path prior to the condenser?

Would I have the greatest flexibility if I use a 2x2x2 tee with a 2" SS gate valve (I know it costs more) or is there no advantage over 1" valve? Following the same logic, would it be best (not cheapest I know) to condense in 2" pipe like with a small coil, or again, is there no advantage to this over all the narrow lebig condensers I see used?

Thanks in advance

[Maritimer]

There was a little discussion about the diameter of the take-off pipe in a recent thread: http://homedistiller.org/forum/viewtopi ... 6#p7070194 . There are some who say that the take-off should be 2", but I made my VM with a 1" takeoff and it works very well. Here is the technique I used shown in a diagram: http://homedistiller.org/forum/viewtopi ... 6#p7070567 . A 2" gate valve is unnecessary, and might even cause problems by being too big. I use a 1" gate valve but only open it two turns. There is an impression that the reflux ratio is determined by the ratio of the sizes of the openings of the reflux to product condensers, but the pull of the ethanol vapour as it goes down the tube past the gate valve to the Liebig must be quite strong. At two turns my reflux ratio is 0.83 (that's one way to measure RR = mass of vapour condensed by the reflux condenser / total mass of vapour coming from the boiler).

A Liebig will easily condense your product. At this point, it would seem that you don't have a feel for the vapour as it moves and condenses in the still. Welcome to the club! With some experience you'll soon be advising others.

M

[DAD300]

The size of the takeoff "T" means almost nothing. The size of the smallest restriction means a lot! It doesn't matter if it is the "T", valve or product condenser inlet!

Look at this design...Condenser Controlled VM

No valve necessary.

3"x3"x3" T

[/attachment]

Coil lowered below take-off

Coil above take-off

3" column, with 3" "T" to Liebig Condenser...with no valve. The reflux condenser is movable up and down. When down it is 100% reflux, when up it is approximately 15% reflux.

Leave the tails on your reflux condenser long enough to stick out the top when condenser is below the take-off. Make the reflux coil diameter a tight but movable slip fit to the inside of the column dia. I move this Reflux Condenser up and down without gloves because it stays about 100 deg F.

I hate valves as I see them as the largest source of pooling and therefore smearing. And the cost. A good valve cost more than the column material and or boiler.

OH did I say, "No valve?"

[choppinlow]

Thanks for the replies gentlemen. And DAD, that is definitely a different design I had not considered (or have even seen before).

DAD, very curious about your rig and the cuts. Not sure that I plan to build like that at the moment, but you have peaked my curiosity for sure. The simpler and better operating the better.

Still not totally sure which way to go, but both of your comments are helpful. I just need to make up my mind and choose. I was hoping to have a solid design in mind before I built, but if I am not happy with the way it operates I guess I can always tear it back apart and rebuild.

Thanks again.

[DAD300]

The 3" is my fifth still. I had valves and still have them around. These valves, ball, butterfly and gate, were designed for liquids, not vapor. I've also seen valves become cooled by supercooled reflux and no mater where the valve is set, the valve starts to become a condenser and drop liquid back down the column.

My cuts are no different than anyone else.

I put the coil down below the take-off for total reflux and equalization. Just like others close a valve.

About 20 minutes later, I lift the coil up to start the take-off. Just like they open a valve.

I speed take off by raising the coil higher and slow it by lowering it. Just like a valve...but I didn't buy an expensive valve and I have no condensate pooling behind a partially closed valve or a reduced take-off port. I have vapor in the column and vapor in the take-off when I raise reflux coil. I portion same by amount of "T" I expose.

I've used the same setup in 1.5" and 2" and it works as well. In fact the smaller versions are not even a coil just a loop of SS pipe (cold finger).

Simple loop with SS Scrubbie

tails sticking out top

There is at least one other similar design by Manu Hanoi using a condeser control VM slanted at about 30 degrees for height control.

And there are at least three others running Condenser Controlled VM around the world.

I have about $150usd in my SS 3" VM column, buying TriClover parts off ebay. TriClover, TriClamp or EZflange Copper is the way to go. You can change things at will on the cheap. And it all fits on an unmodified keg.

[choppinlow]

Do you get good heads/heart separation? I assume no complaints or you wouldn't keep using it. How particular is the "adjustment" of coil height and how can you tell where the coil is once it is up and running? Do you use anything to hold the coil in place or just the tension of the coil and packing? Thanks again for the comments and pics.

[DAD300]

I feel I get better separation than any valve could offer. Any valve setup will restrict the vapor flow(s) and hold some liquid. This setup diverts the vapor flow...never holds any liquid.

When I'm looking for neutral alcohol at the highest ABV I can get. I already have enough seperation in my column to get to 95% ABV. I'm not equalizing for hours hoping the reflux action gets me there.

So there is chemistry and physics working for you here. The foreshots come off first, let them out first, equalize or take off very slow for a while, then speed up and let nature take it's course. Collect in small cups, sort out the cuts later after everything is cool.

Adjustment is easy and I have found the "sweetspot" where I basically know where the condenser is by the position of the ends. And once I get the take-off set, I almost never need to adjust it.

If you know where your condenser is in relation to say a 2" take-off "T", moving it an inch is about 50%, 1/4" is ~12%,...

The condenser has enough friction to hold itself where ever I leave it. Although on the simpler loop version the SS Scrubbies add some friction. When building this idea I thought about using a clothes pin at the top to hang the condenser by, but not needed.

You also have another option for adjusting reflux...if I feel i need a tiny incremental adjustment, I can speed or slow the cooling water flow! You'd have that option with any reflux condenser setup.

And one of the beauties of this idea, you could always add a valve if you feel you're not getting the adjustment you need. nothing lost. I bet you won't want to.

[Halfbaked]

Dad, Very interesting build thanks for sharing it with us.

[F6Hawk]

DAD, I'm intrigued. Curious why you went with 3" as opposed to 2"... won't the top of the keg be your limiting factor?

Also, I'd like to see how you handle your output from that 3" ELL to your jars, if you have some more pics to share, perhaps?

Also, what are you using for packing?

Thanks M8!!

[myles]

There is one other aspect to consider. The vapour enters a chamber of some sort or other where it splits. 1 path into the reflux condenser and the other into the product arm. You want the vapour in this chamber to be turbulent - to aid the splitting process.

1 way to help this along is to have a restriction between the top of the column and this splitting chamber. This restriction increases your vapour speed, that increases turbulence etc etc. Any restriction in the reflux condenser, like a bit of packing, acts as a further offset to encourage vapour to go into the product branch.

Now I favour a T at the top of the column with an offset condenser - the physical obstruction virtually guarantees a good vapour split - but I still put in a restriction to increase the vapour speed. In truth I suspect a T the same dimension as the column would still work, but I use a smaller one regardless.

All other things considered if the 2 paths out of the vapour splitting chamber have the same cross sectional areas, and there are no other back pressure factors involved, then in theory you should get a potential 50:50 split.

I can certainly see the appeal in replacing the valve in the VM branch with a dephlegmator, but bear this last thought in mind.

Can your column remain stable if you fully open your product branch for a 50:50 split? You need to increase the reflux ratio as the alcohol content in the boiler drops, but even at the very start of the hearts phase you may not be able to maintain column stability at very low reflux ratio's. That might be the true limiting factor, not valve size or condenser size but the ability of the column to remain stable when at high product rates.

Keep increasing boiler power and you reach a point where the column floods, unless you split your reflux and divert some directly back to the boiler.

[DAD300]

The top of the keg is a 2" unmodified opening...call it the first plate of sorts. I have done it with a 3" opening from the boiler and no real difference. The 3" opening would lower the initial vapor speed.

The packing is home made SPP (Spiral Prismatic Packing) patterned after Heli-Pak size "C." http://www.wilmad-labglass.com/Products/LG-6730-104/" onclick="window.open(this.href);return false;" rel="nofollow This link will tell you why I made mine. It takes 11 pounds for 3" x 30" column.

before etching SPP

The 3" column is purely for speed...I average 4L first hour at 95%. A run is less than 3 hours from gas on to gas off! 50 minute heatup and a liter every 12 minutes to start, slowing to about 18 minutes and 93% at the end.

TURBULENCE- I have added a wad of SS Srubbie at the top of the SS SPP for turbulence/reflux spreader, with or without the scrubbie, not much difference. I don't have to encourage take off. I easily get 4L an hour and could speed it up.

SPP has a problem with high vapor speed. If the vapor speed is too high it can cause the SPP to entrain more than desired liquid and choke. The same problem can occur with super cooled reflux. I monitor the cooling water for ~110F at exit.

I've also thought about changing the Top TEE to a 3" X 3" X 2" and using the 2" as the take off. But it has worked so well I haven't tried it yet. I think I would loose some adjust ability with the 2" take off.

As for the adjustment, I can vary the adjustment of reflux/takeoff by raising or lowering the reflux condenser. The tails of the condenser never get too hot to handle (~100F). There is a pressure fit between the coil and the column wall. I can go from full to 50% reflux by position. I can also go less than 50% by reducing cooling water to reflux condenser. I can raise and lower the coil during distillation.

But there is a sweet spot...the SPP is so good (my HETP gives almost 14 plates) once I open for the take off to ~50% reflux, the heads hearts are 95% ABV and the tails almost stop at around 93%. When the tails start, I know the volume of product I should have and I turn the gas off by volume collected or lack of product flow.

Stability at 50/50% probably not. I never open the TEE fully. This design is infinity variable, like any valve. I could take off anywhere between 0-100%. 100% by removing the condenser and capping the top.

If you do this design, never let your reflux condenser touch the top of your column packing. It will flood instantly. Ask me how I know!

Product Condenser is a three wall leibig using the SS Flex pipe up the center. It's made from a keg spear covered by PVC and the SS flex pipe up the center.

3 wall made from keg spear

product flow

Never throw away a keg spear!

I collect 300ml for foreshots, 500ml jars for heads, 1L jars for hearts, back to 500 ml jars for tails.

Product exits about 85 F. I usually put a piece of cloth at the end to stop splashing.

[F6Hawk]

Thanks, DAD. From what do you make your SPP? And how do you wrap it?

[DAD300]

I made my SPP from .032 SS welding wire. Spun on a lathe around a modified screw driver tip.

tips/mandrels

I made several mandrels, all from screw driver tips and settled on the oval shape to mimic the Heli-Pak.

Start

tube

coils

Tension on the wire changes the shape.

I spun long chains of wire and cut them with diagonals. Cutting was the tedious part!

[F6Hawk]

DAD300, do you have a thread about your build? Components used? More pics? Me thinx I am going to try and build myself a 3" SS tower.

TIA!

[DAD300]

There are other pics on the forums...but really very straight forward.

Keg to 2" x 3" cap adapter, to 30" x 3" SS pipe (I have a 20" x 3" pipe also as an addon for experiments), to 3"x3"x3" "T" (the most expensive part) a 3"x9" pipe on top for reflux coil. The 3" takeoff of the "T" has a 3" 90 degree elbow, 3" to 1.5" adapter to a 1" x 20" triple wall leibig (made from a keg spear). And a lot of clamps...the coils are 1/2" SS corrugated flex pipe with poly hoses for cooling water.

Column packed with 2" of copper. 28-48" of SPP and a SS Scrubbie on top. If this were just Scrubbies, it would have to be about 3" x 90" of column.

I run my cooling water from tap to hot tub or garden at less than a quart a minute. I use too much cooling water, but try to recycle it as best I can.

The triple wall leibig is overkill, My distillate comes out at about 80 degrees F. The pics here show most of the details.

I can actually charge 15 gallons with no puking (except rum). Measure the airspace and you'll still have about 6" at the top. Kegs are built for 15.5 gallons of beer and a headspace. I put a tablespoon of real butter in the charge as an anti-foam.

I do 18 gallon ferments. I aim for no more than 14% ABV in a ferment, 15 gallons x .14 = 2.1 gallons

The move to 3" was strictly for speed. I can run gas on to gas off in about three hours, 45 minute heatup, 15 minute equilibrium, and average a quart every 15 minutes at 94-95% for two hours. Boom 7-8 quarts collected and cut to 1.5 quarts heads, 3.5 hearts and 1 tails usable and 2 not usable.

[F6Hawk]

Which gaskets are you using on the tri clamp joints?

[DAD300]

I have the PTFE (hard white) above keg joints, but I use the silicone at the keg. I have had what amounts to an "O" ring at the keg, and the PTFE tape works there as well. The only leaks I've had I induced by not getting the joints together properly.

[FirstRunnings]

DAD300
Let me run something by you.
I built basically a 2" copper version of your design. Only difference is that the 2" T doesn't exist. Instead I saddled the 2" pipe with a piece of 1" pipe as a takeoff.
Had the same idea about moving the coil up and down past the takeoff.
This was my first design. my goal was to either use it as a Pot Still head or a VM head.
So I went on the forum and asked some questions after being frustrated with the quality of product.
I promptly was told that the head would not work in either configuration because I did not use a 2"x2"x1" reducing T.
Luckily I had some other coddling about learning more about cuts!
Well it works great as a PS and I never bothered packing the column or installing the condenser above the take off because of the comments I received.

Long story short the product is great period.
Now that i see your design I will probably remove the valve in the takeoff and use the adjustable height coil.
And from what I read it should probably work quite well running it as a VM head moving the coil up and down to control the reflux.
So what do you think?
Remember it a piece of 2" pipe saddled with a 1" pipe.

Got a 4" column on the bench and if the 2" works I will duplicate the VM head

[DAD300]

The 1" takeoff will work, but there will not be much adjust-ability. But maybe you won't need any. Make sure enough reflux coil can get below the takeoff to eliminate vapor getting to the takeoff port. If you add the packing, make sure the coil does not touch top of packing. If coil touches packing...it will flood the top of the column and puke.

As to work or not...sounds like you made your own "T". What's the diff?

If the coil can block the takeoff, you get full reflux with no takeoff.

If the column and takeoff are the same size, you get better ability to adjust takeoff. The left drawing would be 50%/50% and the right would be 80% reflux and 20% takeoff.

If the column is 2" and the takeoff 1" you'd never get more than 25% takeoff and the coil would be either blocking the takeoff or fully open. Hope that makes sense.

"People" told me my version, with column and take off same diameter wouldn't have any adjustment and that the reflux coil down would never make total 100% reflux...both work well.

As for how I adjust mine...the reflux coil never gets so hot I can't use my bare hand to move it. My waste coolant temp is around 110-120 F. I usually move it twice during a full keg run. From fully closed to what I measure as half open and very late in the run to full open as the quantity of vapor and vapor speed diminishes.

A valve in the takeoff of a VM is both unnecessary added expense and construction complication.

[FirstRunnings]

DAD
I can easily adjust the coil to totally block the takeoff.
It's a 4' column so its not a problem keeping it above the packing packing.
The valve is already there and its a full throat ball valve so I am gonna leave it for now.
If I get the results you are I am going to build the same head for my 4" column instead of an LM head.
It is definitely a cost effective head for 4" pipe.

[DAD300]

FR, 4" x 48" length. Too cool. What packing?

I'd say with 48" for SPP (get about 20 plates) and at 48" for scrubbies (only about 12 plates). More is always better as you can always cut it down.

The only other issue is boiler and product condenser...on a 15.5 keg over gas, you'll have a heatup of 45 minutes and a run of maybe an hour. This would make Production/collection very fast!

With that 4" setup, I'd want a boiler I could dump and fill without removing the column.

I'll have column envy...

[FirstRunnings]

DAD
No more gas fired now using 5500 watt water heater element with a PWM controlling it, 7 gallons ambient temp to boil in 25 +- minutes. So I don't have a problem waiting 50 minutes for 14gal.
The propane is to expensive and the PWM electric version has superior control. May use a Phase Shift control later on.
Gona use copper mesh.
The plates give me an idea of the design and do the plates sit on the packing?
also
When you run it for product and pull the coil up above the takeoff do you kill the feed water to the coil in the head?
Will use a Libig 1" x 3/4" on the takeoff, probably 36" and 48" overall.
One thing I didn't tell you I use my pool for the condenser water supply. (Water temp now about 78F) works well on my PS.
For the coil in the head I have a 12V agricultural diaphragm pump that has a constant output of 60PSI.

Originally I went for the 4" column because my stripping runs as well as my product runs took forever.
Other thing is the if the output is lousy I use the stuff to soak my greasy parts in. Works great!

[DAD300]

I was talking Theoretical Plates based on Scrubbies (mesh) as the packing, not bubble caps... I use Stainless Spiral Prismatic Packing, but have used Stainless Scrubbies in the past.

[FullySilenced]

MINIME has been doing some testing using rolled med and fine ss wool rolled up nice and tight... i understand it works extremely well .... to the point he pulled his spp out of service... its not expensive and is made in the USA... comes in roll 4 to 5 inches wide i think i read..


stainless steel wool says call em for a discount here: http://www.briwaxwoodcare.com/" onclick="window.open(this.href);return false;" rel="nofollow

and they have copper wool as well in 5lb rolls...


just a thought

[HookLine]

If you taper your condenser down at the bottom, and to the side opposite the take-off port, you will probably get finer control, particularly in the 90-95.6 % ABV range.

Something like this:

The taper might work better as an exponential curve.

Something like this:

[HookLine]

Besides simplicity and not needing an expensive valve, a condenser controlled VM head has the big advantage that the reflux condenser can be completely removed, and the top of the column safely capped and sealed, so it can be used as a pot still. (Because there is no valve on the take-off arm to be accidentally closed to make a pressure bomb.)

The only 'special' requirement for a condenser controlled still (VM or LM) is the same as for a standard CM still, the coolant supply pressure must be constant (ie stable).

[F6Hawk]

I have the PTFE (hard white) above keg joints, but I use the silicone at the keg. I have had what amounts to an "O" ring at the keg, and the PTFE tape works there as well. The only leaks I've had I induced by not getting the joints together properly.

Here's what I'm using at the keg: http://www.brewershardware.com/F1GASSIL.html" onclick="window.open(this.href);return false;" rel="nofollow

[FirstRunnings]

Fittings are quite expensive.
Anytime I can make a fitting joint I do.
A saddle connection is pretty easy to complete.
Hole saw the vertical pipe and then you have to cut the shape of the saddle in the takeoff.
Here is a link for a calculator that generates a PDF you can tape around the pipe then cope it out.
http://metalgeek.com/static/cope.pcgi" onclick="window.open(this.href);return false;" rel="nofollow
I use StaBrite soft solder and have no problems with strength, you can also use 65% silver solder and braze it.