VM head variations

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VM head variations

Postby gbdsl0 » Sun Jul 26, 2009 4:04 am

Hello all. Some time ago I erroneously built the Still Maker Internal Reflux Still (I have taken some re-assurance from the fact I am not the only one) After plenty of reading I have decided I am going to recycle this still and convert it to a VM still.

It's seems relatively simple to do and I was originally going to replicate the design outlined in the Compleat distiller.

I have throughly searched this site for everything relating to VM and have found there are several variations as to where the gate valve is placed and the design of the take-off point. Please forgive my rudimentary drawings
Still Head 1.jpg
Still Head 1.jpg (6.82 KiB) Viewed 35972 times

Still Head 2.jpg
Still Head 2.jpg (6.45 KiB) Viewed 35961 times

Still Head 3.jpg
Still Head 3.jpg (6.85 KiB) Viewed 35963 times

Still Head 4.jpg
Still Head 4.jpg (6.81 KiB) Viewed 35957 times

Still Head 5.jpg
Still Head 5.jpg (8.27 KiB) Viewed 35705 times


I have my head around the reasons for different designs around the take off point (Reflux control) but can't seem to find solid reasoning for the placement of the gate valve. Does this just come down to perosonal choice of the builder or is it efficiency/cost related. I can see placing the valve on the vertical allows the use of a smaller valve but I already have a 1 inch valve.

I'm sure this has probably been covered but I haven't been able to find it after over a week of searching.

Thanks to all those who have posted the excellent pics of their rigs and offered their time and advice helping us newbies out.
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Re: Converting Internal Reflux Still to VM

Postby FeralPig » Sun Jul 26, 2009 11:09 am

Seems like if you place the gate anywhere but in the horizontal, it should work but you would get a fair amount of condensed stuff building up there. That doesn't seem like a good idea.
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Re: Converting Internal Reflux Still to VM

Postby HookLine » Sun Jul 26, 2009 10:01 pm

Any of those arrangements will work.

A slight variation on number 3 is what I have.

There is another arrangement, a variation on number 4. Keep the large diameter take-off arm through the elbow, and then reduce it in the vertical section, then into the valve.
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Re: Converting Internal Reflux Still to VM

Postby gbdsl0 » Mon Jul 27, 2009 6:04 am

Ended up going with No. 4, only because I already had the 1 inch gate valve and was recycling the Lieberg condenser from my Internal Reflux still which has a 1 inch core.

Going to try and fabricate my first condenser coil tomorrow, found some good info on the site re "Winding a Coil". Also thanks to all those who have posted pics.

If it doesn't work out may have to buy one from Hookline. (They look so neat)

Will post the results. :D
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Re: Converting Internal Reflux Still to VM

Postby gbdsl0 » Tue Jul 28, 2009 8:11 am

Wound my first coil today and the still has for all intents and purposes been converted, 1st run will be tomorrow.

Attached is a picture of my condenser coil. Many thanks to Hookline and other who have posted pics of their coils and offered advice. Big thaks to QDanT for inventing his jig for making the coil and sharing his idea. Using the jig was was a snack. I used soft annealed 1/4 inch copper tube. There was know need to pack with salt. Managed to wind both coils without kinking any copper.

Annealed 1/4 inch copper pipe is usually sold in 30 metre rolls but if you shop around you will be able to find a shop that will sell it to you by the metre (Approx $3.00 Aud per metre), I was able to find a couple. The annealed copper is very easy to work with.
P1010042.JPG


Coil turned out okay, jus need to attach a couple of elbows and it is ready to go.
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Re: Converting Internal Reflux Still to VM

Postby rad14701 » Tue Jul 28, 2009 1:39 pm

Looks great, gbdsl0... Congratulations... Hope it performs as well as it looks...
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Re: Converting Internal Reflux Still to VM

Postby HookLine » Wed Jul 29, 2009 2:28 am

Your condenser looks fine to me. Good work.

Although there is not much of the centre cold finger tube sticking out the cap for the coolant hose to hang onto. Maybe I missed something?
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Re: VM head variations

Postby HookLine » Wed Jul 29, 2009 5:20 am

Variation number 5 now added to the original post.
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Re: VM head variations

Postby plonker » Wed Jul 29, 2009 5:27 am

Hookline, is there much variation with the output quality or quantity across the various designs?
Im assuming that the reflux ratio is the main thing.. and the smaller the output takeoff diameter, the better the reflux?

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Re: Converting Internal Reflux Still to VM

Postby gbdsl0 » Wed Jul 29, 2009 5:32 am

The transformation is now complete. It all went pretty smoothly. I was able to re-use 90% of the old still. To complete the transformation I purchased the following items

1 - 40 cm 2 inch copper pipe (Condenser housing) $12.00
2 - 10 metres 1/4 inch annealed copper pipe (Condenser) $30.00
3 - 2 x 2 inch joiners (Repair column where reflux tubes used to pass through) $6.00
4 - 1 inch gate valve $18.00
5 - Column insulation - $12.00

The remainder I already had (1/2 inch pipe and joiners/elbows)

Total Cost $78.00
P1010039a.JPG

P1010039.JPG


Gave it a vinegar and water run today to clean it out and all went well. Hoping to distill some feints tomorrow. I think my condenser could be sitting a little high above the take off point (approx 4.5 inches), I have read a thread about condenser placement in a VM still but can't seem to find it. (I hate that). If anyone can point me to the relevant thread it would be much appreciated.
Last edited by gbdsl0 on Wed Jul 29, 2009 6:10 am, edited 1 time in total.
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Re: VM head variations

Postby HookLine » Wed Jul 29, 2009 5:51 am

As far as I know, these minor design variations all give the same basic result. Slightly different paths to the same destination.

It is both reflux ratio, and maximum take-off rate. Very closely related, but different. So you can't keep reducing the take-off diameter, just because it gives a higher and higher reflux ratio. The take-off rate will quickly fall to impractically low levels. (You wanna take off all the hearts at a drop a second? Not me. :mrgreen: ) Also, above a reflux ratio of about 5, the purity gains diminish very rapidly, and become too costly in time and energy.

For a VM column, having a minimum inherent reflux ratio of about 2 or 2.5 to 1, is plenty. Much below those ratios and you are getting into pot still territory.
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Re: VM head variations

Postby rad14701 » Wed Jul 29, 2009 1:52 pm

Looks like a successful modification, gbdsl0... I'm sure you'll be happier with this VM design...

As far as the distance from the branch to the reflux condenser, as long as you don't go beyond 3X the column diameter you should be fine... Give it a good workout and if you think you need to reduce the distance, then drop it by a half diameter at a time till you're happy with the performance... Don't do anything until you have a good handle on how the column performs, however...

Good luck with your first wash run through your new column...
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Re: VM head variations

Postby gbdsl0 » Wed Jul 29, 2009 4:13 pm

Thanks for the info rad14701 much appreciated :D
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Re: VM head variations

Postby HookLine » Wed Jul 29, 2009 6:42 pm

Looking good.

If the bottom of the condenser is 30-50 mm above the branch, you should be fine.
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Re: VM head variations

Postby gbdsl0 » Thu Jul 30, 2009 5:12 am

Completed my first spirit run and was pretty happy with the results but looking for a little advice.

To start with I followed the procedure for running a reflux still as outlined by Husker viewtopic.php?f=17&t=5107&start=0.

My wash contained 3.5 litres of ethanol.

1. I found that quite a bit of liquid had condensed behind my gate valve while I had the still running at 100% reflux and this made it difficult to remove the foreshots and head without disturbing the equilibirm in the column. Has onyone else experienced this and is there a work around? I am considering moving my gate valve onto the horizontal part of the take-off.

2. My gate valve leaked at a steady 1 drop per second even when fully closed. (Is this a common problem. Should I consider replacing it with a needle valve)

3. After removing the foreshots and heads, I collected the first 700ml at 95.4% (I was pretty happy with this) The next 700 mls however dropped to 92%. I was then not able to imporve on this through the remainder of the hearts run. (Readings were corrected for temperature)

I varied my collection rate between 10ml - 20l per minute by adjusting reflux and still no change
My condenser is able to run on as little as 150ml per minute and I was running on a low heat setting. I increased the input heat and increased the water flow to the condenser - no change - (From what I have read this shouldn't make a change anyway.)

The thermometer showed a steady 78.8c degrees right until the tails (This is so much easier than using the CM still)

Are my expectations too high or am I just trying to run the still too fast.
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Re: VM head variations

Postby rad14701 » Thu Jul 30, 2009 12:43 pm

More heat would produce more reflux which will in turn increase purity... You probably have more than enough reflux condenser to handle more heat, and by the sounds of your coolant flow it'll handle far more heat ... You want to take a measurement of how much output you get with the gate valve wide open at a given heat setting... Once you get that measurement you can reduce the take off if you want more reflux while leaving the heat setting unchanged...
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Re: VM head variations

Postby FeralPig » Fri Jul 31, 2009 7:27 am

gbdsl0 wrote:Completed my first spirit run and was pretty happy with the results but looking for a little advice.

To start with I followed the procedure for running a reflux still as outlined by Husker http://homedistiller.org/forum/view ... 07&start=0.

My wash contained 3.5 litres of ethanol.

1. I found that quite a bit of liquid had condensed behind my gate valve while I had the still running at 100% reflux and this made it difficult to remove the foreshots and head without disturbing the equilibirm in the column. Has onyone else experienced this and is there a work around? I am considering moving my gate valve onto the horizontal part of the take-off.

2. My gate valve leaked at a steady 1 drop per second even when fully closed. (Is this a common problem. Should I consider replacing it with a needle valve)

3. After removing the foreshots and heads, I collected the first 700ml at 95.4% (I was pretty happy with this) The next 700 mls however dropped to 92%. I was then not able to imporve on this through the remainder of the hearts run. (Readings were corrected for temperature)

I varied my collection rate between 10ml - 20l per minute by adjusting reflux and still no change
My condenser is able to run on as little as 150ml per minute and I was running on a low heat setting. I increased the input heat and increased the water flow to the condenser - no change - (From what I have read this shouldn't make a change anyway.)

The thermometer showed a steady 78.8c degrees right until the tails (This is so much easier than using the CM still)

Are my expectations too high or am I just trying to run the still too fast.


Number 1 was the reason I posted my previous question about that design. It seemed to me that putting the gate valve in the horizontal would be best. Same thing might mitigate number 2. Or a better valve.

A taller column might help number 3. Here my knowledge breaks down as to adding heat. I know adding reflux with my valved design improves purity.

I went to a sump pump and 20 gallon closed loop cooling system. So I just run coolant wide open from moment one.

Luck
This is so much fun it ought to be illegal..wait..never mind.

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Re: VM head variations

Postby rad14701 » Fri Jul 31, 2009 7:47 am

I've gotta agree with FeralPig on his response... In the horizontal portion of the branch you are only dealing with vapor and any potential condensate would be more apt to flow back into the column as reflux...
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Re: VM head variations

Postby HookLine » Fri Jul 31, 2009 8:27 pm

Agree with the previous two posts. Although the initial pooling of condensate in the vertical valve variations does not seem to affect the overall outcome, my choice would still be to have the valve in the horizontal section, and as close to the column as reasonably possible. Mostly coz it is just one less variable to have to worry about.
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Re: VM head variations

Postby Retrobate » Fri Jul 31, 2009 11:20 pm

Mine has the valve below the elbow. It is 50mm by 50mm by 50mm. It only collects 35ml during two hours equilibrium that is discharged to allow the beginning foreshots to flow. It does not cause any problems or things to worry about.
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Re: VM head variations

Postby gbdsl0 » Sat Aug 01, 2009 1:29 am

Hi guys, thanks for all your responses and advice.

I originally put the valve in the vertical as it was a slightly easier conversion however now I think I will put it in the horizontal.

FeralPig wrote:Seems like if you place the gate anywhere but in the horizontal, it should work but you would get a fair amount of condensed stuff building up there. That doesn't seem like a good idea.


Feral Pig, I misinterpreted this and thought you were telling me to place the valve anywhere but the horizontal. (Was in a bit of a rush that night)

I pulled the gate valve apart and found there was a burr on the gate which was stopping it from closing. I took it back to the shop and they replaced it for me. Only downside is the internal diameter of the new valve is only 3/4" instead of 1/2" which means my minimum reflux will be a little lower (I can live with that though)

When my next wash is ready I will try running the still with a little more heat to induce more reflux. If that doesn't work I will extend my column and see if that makes a difference.

Regardless of that the end proudct I have is far superior to that of the old still. It was so easy to remove the foreshots and heads. As far as making neutral spirtis go I can't see how it could get any simpler.
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Re: VM head variations

Postby Cong » Tue Aug 18, 2009 3:06 pm

Hey guys,

I too am thinking of building a VM 2" column. What would the best take off size be?

regards

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Re: VM head variations

Postby HookLine » Tue Aug 18, 2009 3:25 pm

A 1" take-off port is plenty. Then you can quickly reduce it to 3/4 or 1/2" for the rest of the take-off arm.
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Re: VM head variations

Postby astrangebrew » Tue Aug 18, 2009 4:58 pm

Hey GD,
After a PILE of research (a lot here – thanx guys) I went for a 1” “T” & gate as per the COMPLEAT DISTILLER on top a 2” column. I figured for a starting point – that was as good as I could do.
There are some sophisticated arguments for placing the “T” on the down turn to the product condenser (you build so the volume in the downturned section above the gate valve is about the predicted foreshots volume that will be in the selected size of the boiler (too fancy for me at this time)
Also the size of the takeoff to the size of the column (and reflux condenser in my case) controls the minimum reflux ratio you can achieve (I came to the conclusion that this was not a primary concern to me (1” to 2” dia. is about 1:3 min. reflux)) I figured that was in my “happy spot”.
The only part of the setup that is a bit of a mystery to me is exactly why restricting the diameter of the “T” to achieve a high velocity flow is a good idea – my guess is that they are shooting for a turbulent flow verses laminar flow at the split.
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Re: VM head variations

Postby HookLine » Tue Aug 18, 2009 7:48 pm

astrangebrew wrote:The only part of the setup that is a bit of a mystery to me is exactly why restricting the diameter of the “T” to achieve a high velocity flow is a good idea – my guess is that they are shooting for a turbulent flow verses laminar flow at the split.

Turbulence, and lower inherent minimum reflux ratio (1:1 in this case).
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Re: VM head variations

Postby DestructoMutt » Wed Aug 19, 2009 4:45 pm

Cong wrote:...I too am thinking of building a VM 2" column. What would the best take off size be?...


HookLine wrote:A 1" take-off port is plenty. Then you can quickly reduce it to 3/4 or 1/2" for the rest of the take-off arm.


Cong - don't be too quick with the product take-off reduction....use a 1" gate valve followed by a short liebig of 1" ID x 16" long and then reduce to a smaller liebig to further cool your product. it's been confirmed that the smallest size opening that the vapor sees controls the reflux ratio.

gbdsl0 wrote:1. I found that quite a bit of liquid had condensed behind my gate valve while I had the still running at 100% reflux and this made it difficult to remove the foreshots and head without disturbing the equilibirm in the column. Has onyone else experienced this and is there a work around? I am considering moving my gate valve onto the horizontal part of the take-off. moving the gate valve will solve the problem

2. My gate valve leaked at a steady 1 drop per second even when fully closed. (Is this a common problem. Should I consider replacing it with a needle valve)

3. After removing the foreshots and heads, I collected the first 700ml at 95.4% (I was pretty happy with this) The next 700 mls however dropped to 92%. I was then not able to imporve on this through the remainder of the hearts run. (Readings were corrected for temperature) how fast were you collecting (700ml over what time period)? it looks like you collected too fast and upset the equilibrium.

I varied my collection rate between 10ml - 20l per minute by adjusting reflux and still no change
My condenser is able to run on as little as 150ml per minute and I was running on a low heat setting. I increased the input heat and increased the water flow to the condenser - no change - (From what I have read this shouldn't make a change anyway.) what was your heat input? you need to provide enough vapor for the column to work properly - not enough heat = not enough vapor. next time you run into this drop in %ABV, close the take-off valve and re-equlibriate your column.

The thermometer showed a steady 78.8c degrees right until the tails (This is so much easier than using the CM still)

Are my expectations too high or am I just trying to run the still too fast.


Remember, heads are a combination of hearts and foreshots. you want to get all of the foreshots accumulated in the top of the column (not pooled and mixed with hearts against the product take-off valve), so that you can slooooowly bleed off the foreshots and collect the hearts.
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Re: VM head variations

Postby HookLine » Wed Aug 19, 2009 6:18 pm

it's been confirmed that the smallest size opening that the vapor sees controls the reflux ratio.

Can you link to the experiments confirming this?

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Re: VM head variations

Postby Cong » Wed Aug 19, 2009 10:00 pm

I would have thought that the gate opening would largely determine the reflux ratio and that as the vapor starts to form liquid again, therefore taking less space, possibly even causing some sort of siphoning effect, that it would over come the reduction?
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Re: VM head variations

Postby HookLine » Wed Aug 19, 2009 10:13 pm

Cong wrote:I would have thought that the gate opening would largely determine the reflux ratio

Correct, but not quite what we are talking about here, which is the minimum inherent ratio in the column (ie with the valve full open), and that is determined (as far as I know) by the ratio of the column to initial take-off port (as cross-sectional-areas).

I have a 2" column with a 1" take-off port, that reduces to 3/4 through the valve and elbow, then reduces further down to a 1/2" x 3/4" Liebig. It works fine, its maximum output rate is well above what is required.
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Re: VM head variations

Postby DestructoMutt » Thu Aug 20, 2009 11:55 am

HookLine wrote:Can you link to the experiments confirming this?

unfortunately the board rules prohibit linking to other sites.

maybe a moderator could provide the link?

Cong wrote:I would have thought that the gate opening would largely determine the reflux ratio and that as the vapor starts to form liquid again, therefore taking less space, possibly even causing some sort of siphoning effect, that it would over come the reduction?

in reviewing the results posted on the other site, it appears that the "siphon" or "vacuum" affect is non-existent. a review of thermal dynamics and heat/mass transfer seems to confirm this. the phase change from vapor to liquid is not sudden, but slow and linear based on heat extraction.

HookLine wrote:I have a 2" column with a 1" take-off port, that reduces to 3/4 through the valve and elbow, then reduces further down to a 1/2" x 3/4" Liebig. It works fine, its maximum output rate is well above what is required.

again, based on the results posted on the other site, it appears that you have a RR of 16:1 (2" diam column vs. a 1/2" diam product condensor). the results seem to indicate that the least size of the pathway leading to the product condensor seen by the vapor is what controls the reflux ratio. a review of fluid dynamics and thermal dynamics seems to confirm this.

Hook - have you compared your product take-off rate, with the product valve fully open, to the heat input and the amount of vapor that should be produced based on the heat added to the boiler? i think that is what the postor on the other site did, with various product take-off set-ups.
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