3" VM column into a 2" reflux condenser

[BoisBlancBoy]

Hey guys I'm looking at making this style VM:

IMG_0439.JPG (8.32 KiB) Viewed 3284 times

Now I already have a 3"x48" column and a 2"x10" double wound reflux condenser. There any issues reducing from the 3" column to the 2" condenser? Or would that be a non-issue?

[rad14701]

There should be no problem reducing from 3" to 2" for the reflux condenser... I'm pretty sure several members have repurposed 2" reflux condensers on 3" VM columns... You may want to consider extending the 3" take off branch as far horizontal as you can before reducing, however... Hard to say is that was your intention from the picture...

[BoisBlancBoy]

There should be no problem reducing from 3" to 2" for the reflux condenser... I'm pretty sure several members have repurposed 2" reflux condensers on 3" VM columns... You may want to consider extending the 3" take off branch as far horizontal as you can before reducing, however... Hard to say is that was your intention from the picture...

Thanks Rad.

What I was thinking was reducing from the 3" column to 2" at the bottom of the TEE. So everything would be 2" from the TEE up, except when reducing for the take off.

What is the purpose of extending the take off horizontal branch?

[rad14701]

Sounds like a good plan, BoisBlancBoy...!!! The purpose of extending the take off branch as far as possible it to keep the split ratio more equal... We had the discussion, and some experiments were done, some years ago when VM's were becoming the rage for neutral spirits... Older designs would reduce right off the Tee and output rates took a big hit... The longer the branches remain the same size after the Tee, the better the overall performance... Some folks even wait until after the 90 degree turn-down to reduce to product condenser size...

[BoisBlancBoy]

So here is a crude, very crude drawing of what I'm planning and a picture of what I have. I want to make sure what I'm thinking will work but my biggest question mark is dimensions for the take off and length of the horizontal run for it to make sure I can get a good reflux ratio.

What do you think?


My reasoning for wanting to redevelop this rig is this: I feel the 1/2" line into the reflux condenser is causing a vapor speed that is too high. Once I get the power up it starts venting alcohol out of the vent holes even if I have the cooling water maxed which will be nice and cold exiting the condenser. Plus the reflux line carrying the fluid back into the column will be cold.

If I turn down the heat so the condenser does not vent and adjust the cooling water so it is between warm and hot exiting the condenser and run it like that with a take off rate at 1.75L/H my ABV is 90% coming from a batch of low wines. I can get my ABV up to 94.5% but my take off rate is SLOW. The valves had a bar bolted to them so that no way could both valves be closed. I took it off and set the reflux valve wide open and left the handle off to prevent any safety issue hoping that I could get it to reflux more and help the situation. From what I could tell there was no change in its operation. I just feel for a 4'x3" column packed with marbles that my ABV and take off rates are too low. Maybe I'm inexperienced enough with columns yet to be missing something. Picture of my condenser also.

[Danespirit]

So here is a crude, very crude drawing of what I'm planning and a picture of what I have. I want to make sure what I'm thinking will work but my biggest question mark is dimensions for the take off and length of the horizontal run for it to make sure I can get a good reflux ratio.

What do you think?


My reasoning for wanting to redevelop this rig is this: I feel the 1/2" line into the reflux condenser is causing a vapor speed that is too high. Once I get the power up it starts venting alcohol out of the vent holes even if I have the cooling water maxed which will be nice and cold exiting the condenser. Plus the reflux line carrying the fluid back into the column will be cold.

If I turn down the heat so the condenser does not vent and adjust the cooling water so it is between warm and hot exiting the condenser and run it like that with a take off rate at 1.75L/H my ABV is 90% coming from a batch of low wines. I can get my ABV up to 94.5% but my take off rate is SLOW. The valves had a bar bolted to them so that no way could both valves be closed. I took it off and set the reflux valve wide open and left the handle off to prevent any safety issue hoping that I could get it to reflux more and help the situation. From what I could tell there was no change in its operation. I just feel for a 4'x3" column packed with marbles that my ABV and take off rates are too low. Maybe I'm inexperienced enough with columns yet to be missing something. Picture of my condenser also.

The 1/2" pipe is definitely the culprit. As you wrote, the vapor speed is the problem.
This causes the vapor to be forced into the RC and eventually out of the vent hole.

You shouldn't have any problems with the RC as it is. It takes surprisingly little to knock down the vapor. Remember, Ethanol is liquid below 78 C.
Mine looks like this: http://homedistiller.org/forum/viewtopi ... 0#p7262900 (the steel ruler is 150 mm or a tad under 6"). It sits in a 2" column, fired up with a 2KW heating element.
For the best performance, you want an equal vapor split 50/50 to the RC and take off.This can be ensured by equal diameters of the tee.
So, your 3" column with a 2" tee will work just fine...you could even eliminate the need for a valve and make a CCVM out of it..
From the tee, there could be a 90 degree 2" and then a reducer to your Liebig. Make the Liebig detachable and put a threaded fitting/tri clamp on it.
An easy and cheap solution. Plus, you wouldn't have high vapor speeds due to the 3/4" valve you plan on using (that will be the choking point of that construction).
You could salvage the piece with the ferrule from the splitting head you have and fabricate a pot still head...just an example.

Edit: I just saw you considered a 1/2" valve on the take off...don't..! A 1/2" isn't gonna work (even if it's full bore).
It will create a Venturi effect and really choke the column down.

[BoisBlancBoy]

Ok those valves on the old head are 1/2", no good! I'm going to save and use whatever I can from the old head. I have a 6' piece of 2" pipe. I think the only thing I will need is the TEE and valve. So 3/4" valve minimum or should I go 1", does it make much of a difference. I want to go the valve route.

On the 2" TEE take off branch how long do I need to keep it 2" before reducing down to the valve and also to the Liebig? The old head and Liebig attach with a 1/2" union any reason not to use those?

[skow69]

That horizontal tee design you have will ensure a better vapor split than the vertical one you are contemplating. It's just that the pipes are way too small. Stick with 1" minimum on both sides until you reduce for the liebig. The price difference isn't that much and 1" might even be marginal for your 3" column if you want to run it hard.

EDIT: But probably not and the jump to 2" fittings and valves adds a lot of expense.

[BoisBlancBoy]

That horizontal tee design you have will ensure a better vapor split than the vertical one you are contemplating. It's just that the pipes are way too small. Stick with 1" minimum on both sides until you reduce for the liebig. The price difference isn't that much and 1" might even be marginal for your 3" column if you want to run it hard.

EDIT: But probably not and the jump to 2" fittings and valves adds a lot of expense.

Are you saying go with a 1" valve? My plan is not to reduced anything from the 2" TEE except the take off branch. It will reduced from the 3" column to the 2" TEE. Straight up through the TEE into the condenser is all 2". Again just reducing down at some point off the horizontal take off portion of the TEE. Should I go with a 3/4" or 1" valve, then reduce from there to the Liebig? Which is 1" over 1/2".

[still_stirrin]

I recommend using a 1" valve. It will give you the widest range of reflux ratios. Sure, 1" is more $$$ than 3/4". Buy once...cry once. The 1" will work better for you.
ss

[BoisBlancBoy]

Ok thanks. Only thing I'm not sure of is how far off the TEE do I need to extend out before reducing to the 1" valve or does that not matter?

Will my 1" over 1/2" Liebig work?

[der wo]

Will my 1" over 1/2" Liebig work?

Why not 3/4 over 1/2? Cheaper and lighter. Same functionality.
Because you will never run a VM without reflux, a 1/2 inner tube is ok. But if you want to use the liebig for a potstill for stripping too, I would go 1 over 3/4.

At least in my country there are two versions of ball valves (full or reduced throughput). Get the full version.

[still_stirrin]

Will my 1" over 1/2" Liebig work?

Does it work now? I mean, does the Liebig knock down the vapor from your potstill? Then, it should work just fine with the reflux still.

The concern with reducing diameter too soon, or even too abruptly, is that it causes the vapor to accelerate through the venturi. That can cause the flow to "choke", restricting the mass flow rate. And your new 3" column will (or, is capable of) flow(ing) much more vapor than a 2" column will, provided you have the power (heat input) to drive it.

Keeping all lines as large diameter as possible...as long as possible...helps the flow stability, reducing conditions which can upset the equilibrium. So, I suggest reducing to your Liebig's vapor tube diameter right before the flow enters the Liebig. Otherwise keep the vapor path as large as possible, be it 3", or 2", or even 1" ID.
ss

[BoisBlancBoy]

Will my 1" over 1/2" Liebig work?

Why not 3/4 over 1/2? Cheaper and lighter. Same functionality.
Because you will never run a VM without reflux, a 1/2 inner tube is ok. But if you want to use the liebig for a potstill for stripping too, I would go 1 over 3/4.

At least in my country there are two versions of ball valves (full or reduced throughput). Get the full version.

I already have that Liebig. The 1" over 1/2" that I got as a part of the old head of the picture I posted early on in this thread. Just figured as long as reducing down to 1/2" is fine might as well keep using it. Never has any issue of it not knocking down everything thrown at it.

[BoisBlancBoy]

Will my 1" over 1/2" Liebig work?

The concern with reducing diameter too soon, or even too abruptly, is that it causes the vapor to accelerate through the venturi. That can cause the flow to "choke", restricting the mass flow rate. And your new 3" column will (or, is capable of) flow(ing) much more vapor than a 2" column will, provided you have the power (heat input) to drive it.

I just switched to electric, 220v and a 5500 watt element.

Keeping all lines as large diameter as possible...as long as possible...helps the flow stability, reducing conditions which can upset the equilibrium. So, I suggest reducing to your Liebig's vapor tube diameter right before the flow enters the Liebig. Otherwise keep the vapor path as large as possible, be it 3", or 2", or even 1" ID.
ss

So if I come off the 2" TEE with a piece of 2" pipe a few inches, reduce down to 1" and connect to valve then go a couple more inches to reduced to the 1/2" to connect to my Liebig?

[Prawnstarr13]

Sounds like a good plan, BoisBlancBoy...!!! The purpose of extending the take off branch as far as possible it to keep the split ratio more equal... We had the discussion, and some experiments were done, some years ago when VM's were becoming the rage for neutral spirits... Older designs would reduce right off the Tee and output rates took a big hit... The longer the branches remain the same size after the Tee, the better the overall performance... Some folks even wait until after the 90 degree turn-down to reduce to product condenser size...

So rad are we talking making the horizontal 3' length the same or greater length than the vertical after the tee, i.e. Make sure that the reducer horizontal restriction is further away from the tee than the 2' reduction for the condenser?
If I were to do this build in 3" stainless the bends are cheap but tees are not available I was going to drill / cut the hole in side of column and slip the horizontal tube in with a slash cut but ideally both pieces after the imaginary tee would be joined with triple/clover clamps
Err I think I'm struggling to see my point now
Lols

[Yummyrum]

Biosblankboy , are you going to use this still for stripping ?
If yes then carry on as advised .

If not ( you have a pot head for stripping ) then there is no need to be all anal about havng takeoff ports as large as possible .
You are building a VM right ? It will be used to make a nutral and therefore will be operated with ahigh rux ratio maybe around 10:1 .
The point is there is no use having a huge arse expensive ball valve and related bends etc. because it will only ever be partially open .

I know , I built one many years ago and still use it but the valve is bearly just cracked open .... a whole lot of worry and extra stress over nothing .

[BoisBlancBoy]

Biosblankboy , are you going to use this still for stripping ?
If yes then carry on as advised .

If not ( you have a pot head for stripping ) then there is no need to be all anal about havng takeoff ports as large as possible .
You are building a VM right ? It will be used to make a nutral and therefore will be operated with ahigh rux ratio maybe around 10:1 .
The point is there is no use having a huge arse expensive ball valve and related bends etc. because it will only ever be partially open .

I know , I built one many years ago and still use it but the valve is bearly just cracked open .... a whole lot of worry and extra stress over nothing .

Yes this VM will only be use to make neutrals and will not be used for stripping.

[der wo]

Yummyrum is right. We didn't ask you, what you want with the VM.
If you want during the whole run a high reflux rate, you can take a smaller valve.

[BoisBlancBoy]

Yummyrum is right. We didn't ask you, what you want with the VM.
If you want during the whole run a high reflux rate, you can take a smaller valve.

Will this affect take off rate much? Instead of a 1" downsizing to a 3/4"?

[der wo]

Yummyrum is right. We didn't ask you, what you want with the VM.
If you want during the whole run a high reflux rate, you can take a smaller valve.

Will this affect take off rate much? Instead of a 1" downsizing to a 3/4"?

Yes. Like always. Either you send the spirit back down the column or you take it off. The more you send back the higher the purity. The question is, how pure do you want the product...

[BoisBlancBoy]

Well I definitely want to make a very pure neutral but want to have at least a normal take off rate which I'm not sure exactly what that is! Haha. Right now with the current setup I can get 1 pint every 35 minutes at 189 proof or speed up to 1 quart/35 minutes at 180 proof.

[der wo]

I am not the best one here judging take off rates, but perhaps it would help, if you tell us, with how much wattage you feed the 3" column.

The main benefit of a normal VM is that a low abv vapor reduces the output rate. So if the abv drops, the still corrects this a bit. But you have to feed the 3" efficiently at first, this is more important than LM/VM/CCVM...

[Danespirit]

I use a 3/4" valve on my 2" VM...but it's a full-bore..!
A very important thing to remember, because one can also get a valve that ain't full-bore and that reduces the internal diameter substantially.

[BoisBlancBoy]

I am not the best one here judging take off rates, but perhaps it would help, if you tell us, with how much wattage you feed the 3" column.

The main benefit of a normal VM is that a low abv vapor reduces the output rate. So if the abv drops, the still corrects this a bit. But you have to feed the 3" efficiently at first, this is more important than LM/VM/CCVM...

To be honest I've only got 1 run with this still since I've switched to electric. I ran the whole run at about 60% power on a 220v/5500k element. I also loaded the boiler with 3 gallons of 65%ABV low wines and then 10 gallons of water. But the last time I ran with with propane it was a full charge of low wines dilute down to 40%ABV and it reacted the same with either.

[BoisBlancBoy]

I use a 3/4" valve on my 2" VM...but it's a full-bore..!
A very important thing to remember, because one can also get a valve that ain't full-bore and that reduces the internal diameter substantially.

Going point. I haven seen that in the descriptions when looks at valves. I think no matter what I'll get a 1" valve just to be safe.

[Yummyrum]

This might give you a clue as to how much open aperture area verses what area to reflux coil . This is important to grasp . It clearly shows the Reflux ratio or proportion of vapour that is taken off verses how much is Refluxed .

In this case I have a dual reducer from 2" to 1 1/4" and a 1 1/4" ball valve so the ball valve open area is quite relevant .

I have marked my ball valve at .Just closed , drips for fores removal and where I take off hearts .

Here is just cracked for fores and early heads take off

Heres heads take off

Heres as open as it ever gets , this usually putting out around 95% ABV at around 1 liter per hour max . For a purer neutral , I usually run it closer to where I take off heads but the take off rate drops back to about 3/4 liter /hour .

So you can see that there is bugger all actual aperture area required to run a VM for producing a neutral and like Dane said , 3/4" on a 2" is probably pretty much in the ball park .
Derwo is right about power requirements as unless you are applying enough power to keep up the required amount of reflux , you won't be able to take off as fast as you would like to without seriously loosing quality .

[skow69]

I think gate valves are worth the extra price. Easier to be repeatable.

Just another opinion.

[der wo]

Great pictures, yummyrum

I think it would be stupid to pay the extra price for a bigger valve and bigger diameter of the product path and then not to buy a full-bore (thanks for the new vocabulary) valve. Except a full-bore is much pricier than a reduced diameter one.

When I look at yummyrums pictures of his valve settings, I think a smaller diameter would be sufficient.

[BoisBlancBoy]

So you can see that there is bugger all actual aperture area required to run a VM for producing a neutral and like Dane said , 3/4" on a 2" is probably pretty much in the ball park .
Derwo is right about power requirements as unless you are applying enough power to keep up the required amount of reflux , you won't be able to take off as fast as you would like to without seriously loosing quality .

Thanks for the info and pictures. Very informative.