LM / VM Head design questions

[Old Fart]

Hello all! I'm about as green as it comes when it comes to the art of distillation and have finally decided to take the plunge and build my own still and have a few questions for the masters. I have been lurking here for some time now and have gathered enough info to be just a bit dangerious. I don't like to re-do something I built so I figured I'd try to get it right before I start. Here's a drawing (not too good) of my proposed VM/LM head.

The questions I have are as follows:

1. The "wye" for the VM take off is 2x2x2 with a 2x1 reducer for the VM port. This provides no restriction for the reflux (LM) condenser. I have noticed people building them both ways, both restricted and unrestricted and was wondering what is the better way to go? I could just as easily reduce the column to 1" with a reducer and use a 1x1x1 "tee" instead if the 2" wye and increase back to 2" going into the condenser. I understand convergant and divergant when it comes to air/vapor flow and it seems to me that an unrestricted condenser may reflux too much vapor and result in a reduced flow to the VM port. HELP!

2. How far above the VM port should the LM condenser be? Does it really matter if the reflux is returned to te column externally? HELP!!

3. I'm planning to use 5/8" copper for the reflux return piping just because of it's availability and restricting liquid return by metering holes in the bottom of the condenser. I'm planning to use the dam inside and not returning any reflux to the column internally. Anyone see any problems with that? Also what size hole would be good? I was thinking 1/4" x 2 would be plenty. HELP!!!

4. Next (and final) questions have to do with the reflux return trap under the VM take off port. How much below the VM port should this be located? And how tall should it be? Also would it be OK to continue the 5/8" OD tubing into the column? HELP!!!!

I know I'm a newbie and am probably going to be told to do my homework before posting but I think I already have and given the multitude of variables and the risk of putting together ideas that are incompatible resulting in something inefficiant I feel these questions are relivant. Thanks much for any help, it is appreciated!!

Old Fart

[HolyBear]

Hey there ol fart, I was going over the posts and noticed that you hadn't had a response so I thought I'd bump it. Maybe I bumped this post to help you, but also I am interested in building a VM /LM combo.

Now first off, I noticed this is yer first post, hmm, Hello? How bout sauntering over to the welcome center and giving us a proper howdy do? (Might have something to do with no response)

As for your specific questions, well, since I haven't built one myself yet, I would only be talking from what I've read. I do know that there are a few here with VM/LM combos and hopefully since this has been bumped, maybe they will be so kind as to help you.... welcome to HD!!!

[Old Fart]

Thanks for the reply!! I'm sitting here with a pile of copper in front of me just drooling about getting started. I've got most of the boiler done already and have pretty much figured out what I'm doing for a heat sorce so I'm kind of at a stand still. (Ha Joke there). Anyway here's a picture of my keg, hope the rest turns out as good. Made the column attachment 4" for my future column and a reducer for the one I'm building now.

Thanks, I'll go to the welcome center and introduce myself.

[maheel]

Anyway here's a picture of my keg, hope the rest turns out as good. Made the column attachment 4" for my future column and a reducer for the one I'm building now.

DSCN0021.JPG

thats a MASSIVE tri clamp !!!

[myles]

Hello there. Your "wye" is a sweep T and it might help with the split in the vapour paths. Regarding the condenser - a bit of packing under it will 'assist' the flow into the product branch by introducing a small amount of back pressure at the entrance into the reflux chamber.

A VM's MAIN driving factor is the relative cross sectional areas of the 2 ports from the vapour splitting chamber. 1 into the product branch and the other into the reflux condenser. However, it is taken for granted by most folks that the vapour is turbulent, and that the pressures are balanced.

Increasing the vapour speed with a column constriction below the vapour splitting chamber is 1 way to increase the turbulence. I use an offset condenser as it has a physical obstruction in the vapour path to ensure turbulence, but there are other ways to do it also.

The main function of the external reflux return is to prevent reflux condensate (potentially heads contaminated) from passing through the vapour stream (clean) that is about to go into your product branch. Height above the VM section is not really important. A VM column will run perfectly well with an additional heads column above the VM section - if you have the space available.

5/8" tube is more than adequate, but if it is what you have available then just use it. As for the distances involved, this is usually an issue of practicality. I use a reduced branch T for my reflux return point, so this introduces a gap of 3" or 4". Provided you don't eject your reflux return back into the VM section it probably is not critical.

This was an early VM of mine - just to show proportions and placement of components. It worked OK'ish.

One of the problems with the horizontal condenser is just that. It is easier if it can be just OFF horizontal to get the reflux to where you want it to be. One possible solution is to do this:

Simplicity of build was one of the reasons I changed to an offset condenser, as it is easier to just rotate it a few degrees off horizontal and to fit a heads trap at 1 end.

[Old Fart]

thats a MASSIVE tri clamp !!! [/quote]

It's a 10". I found it at Brewers Hardware. The beer guys have all the cool stuff! I am thinking about adding a vertical thermowell to it for a referance dial thermometer but I wasn't sure it would be the right place to take the temperature of the vapor. Ayone have any thoughts on this? I also heard from my cousin that if I use a thermowell that I should but mineral oil in it to aid in heat transfer to the probe. You guys do that with your digital probes in the upper column right? Ifnot than you probably should.

Thanks for any responses!!

Old Fart

[Old Fart]

[quote="myles"]Hello there. Your "wye" is a sweep T and it might help with the split in the vapour paths. Regarding the condenser - a bit of packing under it will 'assist' the flow into the product branch by introducing a small amount of back pressure at the entrance into the reflux chamber.

Thanks Myles for the response. I presume back pressure is the reason I see many slant plate LM/VM heads being built without a change in column diameter. I will look into this further. BTW what size tubing is your current head made with? Looks like 2" and maybe 1 1/4"?? Just wondering.

Thanks,
Old Fart

[myles]

2" and 1.4". Well spotted, it is actually 54mm and 35mm but that's because our plumbing tube is metric and our HVAC tube is in inches I routinely mix and match imperial and metric units.

[Soggy Bottom Boy]

.

HFC, a manway in a keg! An absolute necessity if you ever have to get your head in there for a closer look!

Might I ask, how much was the PTFE gasket for that?

.

[Old Fart]

Might I ask, how much was the PTFE gasket for that?

$6 US and it's silicone. Not much difference in the temp ranges between PTFE and silicone, both are above 400F. Am I missing someting here? Silicone is OK to use right?

That wouldn't be the mud riding "Soggy Bottom Boys" from the deep South would it be?

Thanks,
Old Fart

[Samohon]

Am I missing someting here? Silicone is OK to use right?
Old Fart

Personally I would ditch the silicon gasket and go with one of THESE... They last a long long time....
That way you can be sure 100% that your product is safe...

Welcome to HD...

[Soggy Bottom Boy]

That wouldn't be the mud riding "Soggy Bottom Boys" from the deep South would it be?

Old Fart

No, but, "I Am a Man of Constant Sorrow".

Although I do get muddy from time to time.

=O)

.

[Old Fart]

Finally made some progress on my new column. It's still a work in progress though. I have some glass for the sight glasses on order as well as a 1/4" needle valve for the LM section. Cooling lines are under construction as well. Here are some pic's for everyone’s enjoyment. Comments, criticism, and questions are welcome, moderators feel free to move this post to a more appropriate board area.

Thanks,
Old Fart

[Old Hippie]

Anyway here's a picture of my keg, hope the rest turns out as good. Made the column attachment 4" for my future column and a reducer for the one I'm building now.

DSCN0021.JPG

Mother of Nancy that's a nice looking slab of stainless! I've been considering a keg boiler and I'd be eternally grateful if you'd share 1) a pile of pics of that thing and 2) tell me where you got it or the parts to put it together. I've got a good local welder who can do stainless, if that's the ticket, but I need to know what parts you used and where to get them

Cheers!

OH

[Old Fart]

Got it at Brewers Hardware dot com. It's a 10" Tri-clamp ferrule, cap and clamp. The only gasket available for it from them is silicone, I have another source looking for a PTFE one. Here's a couple of more pictures of the keg and a couple more of my still build that is in progress....
Old Fart

[Soggy Bottom Boy]

.

Austenitex.com has them, $42.67 each plus $8.68 shipping by USPS (or $10.76 UPS) to the West Coast from Delaware. >>>>CLICK HERE<<<<

.

[Old Fart]

Thank You for the info on the gaskets. Good to know they are available. Here are a couple more detailed pictures of my keg.

Old Fart in the wind.....

[pfshine]

man you are doin good I like it. That has got to be the biggest thermometer I have ever seen.

[Old Fart]

I wanted to see it from across the room!

Old Fart

[Old Hippie]

I wanted to see it from across the room!

Hell you could see it in the next county!

[Old Fart]

I got a good deal on 4 of them so I have 3 for sale. One is a 6" rigid stem and the other 2 are 4" stem with any angle view. All are liquid filled. $15 plus shipping....... or trade for something good......

Old Fart

[Old Hippie]

Here are a couple more detailed pictures of my keg.

I'm likin' the look of that a lot!

So it looks to me like you did the following:

10-inch ferrule, clamp and cap;
welded a 4-inch ferrule on the cap and fit it with a 4-inch cap and clamp;
then welded a 2-inch ferrule to that.

Is that right? I'd like to know your thought process on that -- set it up so that you could put a wider-than-2-inch column on if you want?

I'm thinking about putting that on a 1/2-bbl keg, using the 10-inch ferrule so I can get inside the keg to clean things, but then having the 2-inch ferrule on the 10-inch cap.

From the bottom up, here's how it's shaping up:

1/2 bbl keg with mods: 1) Stilldragon element protector and electric element in the keg; 2) stainless stub to NPT added to the keg for a drain (will attach ball or gate valve to that); 3) 10-inch ferrule/cap/clamp on top; 4) 2-inch ferrule, etc. to attach column.

Column 2-inch by three or four feet (depending -- I have plenty of copper to go either way or both and see how it works). Copper mesh packing.

VM head. I'm thinking seriously about using convector pipes to air-cool the reflux and then possibly create a fan-forced air-cooled product condenser. I may have mentioned water is scarce. Pissing it away for cooling makes little sense. If water-cooling is necessary I'll work out a recirculating water system like an old screen-flow tractor radiator and circulate the water with an aquarium pump. Stillheads are pretty easy to build and mess with, so I can keep at that until it does what I want.

Heat control: either a burst-fire controller of some kind or my preferred option, a nice hefty Variac autotransformer.

It's not the cheapest rig I've ever run nor the smallest but it looks to me like it'll do what I want in the long-term and handle any size batch I'm likely to make. I reckon I can pull the packing if I want, put a different cap on the column with a lyne arm to the condenser, and run it in pot-still mode if i want (or make a shorter column/gooseneck and attach to the boiler...). Lots of options and flexibility.

Interested to hear what folks think.

Cheers,

OH

[Soggy Bottom Boy]

.

I was doing some google research on barrels, ...and came up with this.


Optional use for a keg with a 10" ferrule.....

.....clown bullfighting barrel for the midget rodeo??? Hehe...

Let'er Buck!

[Old Fart]

So it looks to me like you did the following:

10-inch ferrule, clamp and cap;
welded a 4-inch ferrule on the cap and fit it with a 4-inch cap and clamp;
then welded a 2-inch ferrule to that.

Is that right?

That's correct. I want to build a 4" flute one day and I thought since I have to pay for stainless welding that I would have it set up that way now. I have a 2" conumn that is 6' tall under construction right now. Just got my glass in for my sight glass today so it looks like I'm doing a vinegar steam clean this weekend:). I don't have a power controller yet, been looking at big variacs on flea bay, they are expensive. Looks like I'm building a phase controller......

Old Fart

[Old Fart]

I need some advice form the pros. I filled my boiler with water last night and brought it up to a boil and was checking the operation and I have some comments and a couple of questions. First off the Jackson cross flow seems to be an EXTREMELY EFFECTIVE condenser. It can reflux everything my 5500W element can vaporize at full power. I'm impressed!! I had a steady flow of condensate and it was easy to regulate with amount of cooling water fed to it. The problem I see with my build is that the VM arm seems to be too small. When I cut the supply of water down to the LM section and turn on the VM cooling I get some discharge from the product port but I'm loosing vapor out of the vent on top. I put a little more cooling water to the cross flow and the venting stops but so does the VM output. Does anyone have any thoughts on what to do? Can or should I put a cork in the vent when operating it? Should I tear it apart and go larger on the VM arm? Is it going to act different with alcohol in the boiler?

Thanks,
Old Fart

[Ben the Stiller]

Hi Old Fart - I have a question about condensing temp on a VM machine. My column (generally) runs at the correct temp (192 F) and the vapor goes to the condenser. I have a thermocouple running down the center of the condenser coil to check the condenser temperature. Assuming that I throw out the light ends at the start, does it really matter what temp I condense the vapors at? Seems to me that once we get rid of the light ends, the ethanol is what is hitting the condenser (as long as the column stays at 192). So if I goose up the condenser flow rate and lower the condenser temp to around 150 or back off the condenser flow and let the condenser run at 165, will it make any difference in the quality of the product? I would think the only thing that is important is that you see no vapor sneaking out the top of the condenser (losing product)

thanks

[Old Fart]

Boy you're asking the wrong person as I've only done a vinegar cleaning run at full power with my still. I'm still waiting on Mule Kicker to send me my power controller. I have 24 gallons of sugar wash (wino's) almost completed fermenting. Still bubbling but slowing down. I have to let it clear for a week or so after it finishes so I'm still a couple of weeks out on my first alcohol run. After much reading I believe that 168 degrees will condense all the foreshots and 172 degrees will condense the hearts. If you go too hot too fast than you will smear the foreshots into everything else. Also temperature is best taken on the top of the column BELOW the condenser and must be shielded from the droplets falling off the condenser so it's reading only vapor temperaure. Hope this helps, it's all book knowledge though.......

Old Fart

[rad14701]

Ok, I'll bite... Where are you two getting these temperatures you think you can control in a reflux column...??? Something just ain't right here...

[Ben the Stiller]

Thanks for jumping in Rad. Here's what I think I know....
I put the wash in the keg and plug in 3 submersible heaters. In one hour, the liquid temperature in the keg gets really high - I want to say 250 deg F. I unplug one heater but the temperature of the wash remains about the same. I have a temp gauge in the top of my reflux column. When the whole thing behaves, that temperature runs up to, and sits on 192 deg, which I understand is the boiling/vapor temp of a 10% alcohol/water mixture. The vapor passes from that column to what I call the vapor head (because I don't know the correct name for it), where I have a condenser. Most of the liquid from that condenser flows back to the reflux column and a way little bit goes to product. My reflux ratio has to be around 10 to 1 based on valve stem turn ratios.

I can adjust the temperature in that vapor head (condenser) by water flow rate. In Colorado at 7500 feet elevation, I think that I should be condensing alcohol at around 168 degrees. But once I collect the foreshots and dump them, does it matter that the condenser might be running cooler than 168 deg?

So, I have a few questions. First, should I be running the wash in the keg at a much lower temperature (like 192 deg vice 250 deg). Second, once I remove the foreshots, it wouldn't seem that the condensing temperature matters too much. As long as the column is running at 192 degrees, doesn't that mean that I have pretty much only ethanol and water going up the column? Once the temperature in the column starts creeping up to 194 or higher, I figure I've captured most of the ethanol and am now grabbing propanol, and other nasties. I've checked around the forum and went to the main website and have not been successful in finding answers to these questions. Any advice would be much appreciated.

[Old Hippie]

should I be running the wash in the keg at a much lower temperature (like 192 deg vice 250 deg).

I'll admit it's been a few years since chemistry and physics lectures in university, but something isn't adding up for me here.

What I learned is that in a solution of liquids with different boiling points (or even in a pure liquid), you're not going to push the temperature of the liquid past the boiling point until you have every bit of it in vapour phase.

Also, if you heat up a mixture to the boiling point of the lowest-boiling-point constituent, the temperature will stabilise there until that consituent has entered vapour phase, then will step to the boiling point of the next highest constituent. Vapour-phase temperatures can be much higher than boiling point as witness high-pressure steam for instance, but if there is liquid left it has to be essentially at boiling point for whatever's still in liquid phase.

Enter the role of pressure -- as in the case of steam you need to increase pressure to raise the temperature of the vapour phase. Lower the pressure, you lower boiling point and lower the temperature of the vapour.

What I'm trying to say is that if you're measuring 250 degrees at the top of the column you're not measuring wash temperature. I'm not sure where that temperature is coming from, as a column head should be sufficiently isolated from the boiler that it should never see that temperature unless you've boiled the boiler dry and and are now melting it into a puddle. Even thermal conduction along a copper pipe insulated with pipe wrap shouldn't get that high with normal atmospheric pressure in a boiler filled with mostly water.

The first response is "it can't do that." Of course, you say you've seen it do that. Whether you've seen it is not the problem. The problem is that I can't imagine why you'd be seeing it.

The second response is "is that an artifact of poorly calibrated measurement tools?" If you are at high altitude (lower air pressure) you should see lower boiling temperatures, not higher. Have you calibrated your thermometer in a boiling water bath, correcting the temperature for your altitude?

Before I assume that the temp you're recording is related in any meaningful way to what's really going on inside your rig, I'd try to track down where the anomaly is entering. Either something isn't measuring correctly, or you're running pressure in which case you're operating a bomb. What are the temps lower in the column, and (if you can get a thermowell in there) what is your actual wash temp?

Although it wouldn't be classically "scientific" if you can figure out that when everything's going tickety-boo it's just going to be 250 degrees at that point, then you can use it as a reliable (but not valid) benchmark. You'd still have that uncertainty over why something that shouldn't happen is apparently happening, however, and you would likewise have no way to correlate changes in that benchmark with what may be changing in the system.