VM Valve question

[minime]

anyway just wondering. have you/anyone used that head on a same-sized column? would reducing the relative size be a problem?

There's two or three members besides Punkin who have built entirely of 2" and report good success both in maximizing quantity and good quality so jump right in.

[snuffy]

It's an open question how small a valve can be used, so bigger is better.

I'm running a 1 3/4" column 48" tall with 1 1/4" tee and a 3/4" valve. My production maxes at 90% abv using 1450W immersion element. That's maximizing rate with the valve open a little more than half way. I haven't tested it to see what the %abv is with the valve full open for long.

Going for purity, I haven't been able to get above 93% abv at about 30% valve opening. I've been fooling around with junk at the top of the column that I'm thinking is actually shortening the effective column length.

It would be interesting to have a table showing column diameter, column length, power input, tee size, elbow size and valve size with output stats for different columns. If people would PM me their numbers, I'll put the table together.

I'll bet if we got that all listed in one table, something would smack us right in the eye about the design parameters.

[Wai‘ona]

Hello All,
I am in the process of building a VM still. I had thought to build an off-set head valved-reflux still (LM), but after much reading of forum posts and the mother site I 've been convinced that a VM still-head is probably a better way to go. I live in a relatively remote part of the world, so some of my materials are bought off of the internet. Shipping usually more than doubles the cost of parts. I'm trying to work with what's available locally as much as possible.

Following this particular thread I have a question about stream splitting at the base of the reflux condenser on a VM still-head...

I have a 3" x 12" piece of type L copper I was going to use as the condenser shell on the LM still-head. I would like to keep this piece of copper intact and use it for the reflux condenser shell for my VM still-head (it is a beautiful piece of copper, I don't want to cut it if it's not necessary). The larger condenser shell will also fit a wider radius condenser coil. Trying to wind a coil to fit inside of 2" condenser shell is not something I would look forward to.

I have a 3" x 2" reducer to connect the 3" pipe to the 2" x 2" x 2" T where the take-off stream separates from the column. Does anyone have any thoughts on how a 3" condenser shell will affect take-off flow? Reflux rates and temperature?

Also, I am thinking of using a 1/2" brass ball valve. I've seen by his photos that minime uses these types of valves. Any thoughts on 1/2" brass ball valves?

Someone's signature say's that this forum is addictive. Yessir buddy! I've got it so bad that I read this forum on my iPhone wherever I am when I have a few spare minutes...

VM Still Design 3-22-09A.jpg (37.95 KiB) Viewed 4512 times

[HookLine]

Hi Wai‘ona

Your design is basically okay.

1) For a 2" column you only need 6-7" of 2" coil condenser, 12" x 3" is serious overkill.

2) I don't think the 3" shell will alter reflux or take-off rates, others have used a 3" shell on top of a 2" column and they don't seem to have any trouble.

3) 36" of packing is okay, and will work, but the take-off rate will be relatively slow. If you can go higher then do so. Optimum packing height for 2" column is about 55-60".

4) I am not a fan of brass valves. Stainless is more expensive, but a much better investment, IMHO. Remember that you only have to buy it once, it will last your lifetime.

5) The outside tube (coolant jacket) on your Liebig only needs to be 3/4". Having a bigger coolant jacket is a less efficient use of coolant. The general rule is to have a coolant jacket that is only the next tube size up from the inner product tube. So 1/2" inside 3/4", or 3/4 inside 1", etc.

6) How long is the coolant jacket on your Liebig condenser? Will you also be using it for stripping runs? If so, then a coolant jacket length of about 20-24" should be fine for up to maybe 4000-5000 w of heat.

Cheers
Hook

[punkin]

Sorry for the slight sidetrack, but i sent Snuffy my figures and couldn't attach a piccie to the PM like he wanted, so here's a pic of my head

vmbuildhead1.jpg (37.36 KiB) Viewed 4516 times

[uh-60 pilot]

Wai‘ona,
I just built a 1/2" lebig with a 1" outer pipe because it left me just enough room to wind a coil of 1/8" around the outside of the 1/2" and still pack it into the 1". Im hoping that I can get a little more than standard cooling out of my +/- 2ft leibig.

[snuffy]

Aloha.

You could save that 3" for something else and use a reducer to 1 1/2" for the tee and elbow (cheaper parts). A stainless steel ball valve would be better, but brass if you must. Try these guys: http://www.klgstainless.com/services.html" onclick="window.open(this.href);return false;" rel="nofollow

You don't say how much power you're planning for the boiler, but with good boiler and column insulation, 1500W delivered to the head should be in the ball park.

A coldfinger can handle reflux in less space than a coil. This one is good for 3000 W. It is 12" x 1" with 3/8" water lines. The rule of thumb is 90W condensing power per sq inch of copper surface exposed to vapor.



This picture shows half of the packing so you can see the relative dimensions of tube and packing. The trick is keeping the void space to a minimum by packing with copper mesh. This trick works with Liebigs, too. The vapor space is where it happens, there's not much to gain from increasing heat transfer to the water if the vapor to copper transfer can't keep up. Water has enormously more heat capacity per volume than vapor.



This shows the vapor line at about 1400W and moderate water flow.



An alternative to mesh packing is to add cooling fins. This is 6" x 1/2" and can handle 1300W.



And this one is turned inside out with the cooling on the outside.

[Wai‘ona]

Great ideas and pictures! Thank you all for your responses.

I'm trying to use the parts that I already have gathered for the LM still-head I was going to make - to make the VM still-head instead. 1 ft. of 3" L type tube, 5 ft. of 2" L type tube, 10 ft. of 1" L type tube, 10 ft. of 1/2" L type tube, all of the reducers, nipples and Ts shown in the drawing above, plus a handfull of 1" x 1/2" x 1/2" copper Ts to use for making a Liebig condenser or three. To change to 1-1/2" or 3/4" means having to buy more copper. I'm in the dog house already for spending too much money on parts... so unless it means goofing up, I'm going to try to make it work with what I have. Over-kill is OK. Reducing quality or output volume is not OK. I'll buy more parts if I have to, to keep from goofing up, but there will be a price to pay beyond the cost of the parts...

xx7777xx's Still Design Opinions post got me thinking:
http://homedistiller.org/forum/viewtopi ... m&start=15
I can build two stills with a common boiler and a 2" x 2ft. base column connected to the boiler with a tri-clamp. Then connect the potstill head or the VM head to the base column with a 2" union. I have all the parts to build both heads already. The VM head will top out near nine feet high (tall buggah!)

I live in a tropical rain forest so cooling-water conservation is not an issue. I have a 55 gal rain-barrel that overflows pretty much continually. I could probably cool two or three stills with just the overflow.

Will a Liebig that is a 1/2" tube in a 1" shell work OK, or will it provide too much cooling? Using Snuffy's equation for cooling capacity (90W/square inch of copper) a 1/2" core on a Liebig should provide cooling at around 141W/linear in. or a tad over 5000W (17,300 btu/hr) for a 36" liebig. Is that enough cooling capacity to condense a potstill?

Centimeter gave me some good advice on coil winding and I managed to wind a pretty nice condenser coil out of a 1/4"ID (3/8" OD) x 12ft long piece of tubing to fit into my 3" condenser shell. With two 6" stubs extending out of the shell to connect the coil to the cooling water lines I calculate the coil should have a cooling capacity of around 14 kW. Is that too much cooling for a reflux condenser?

My heat source is a propane cooker that maxes out at 150 kbtu/hr or around 44 kW. I use it for crawfish boils and brewing beer. It will heat 12-15 gals of water to a boil in less than a half an hour. It has a water heater type burner (concentric rings of tiny little holes) so it fine tunes down very low. I'm hoping low enough to keep from flooding my column. I know if needed I can use a heat difuser to throttle down to less than 1000W (3410 btu/hr).

I'm working on getting a stainless ball valve. My soldering/brazing skills are such that I don't look forward to trying to get it connected into the system. Any ideas/suggestions about that?

Thanks again for sharing what you know. I do appreciate it!

[minime]

Will a Liebig that is a 1/2" tube in a 1" shell work OK, or will it provide too much cooling? Using Snuffy's equation for cooling capacity (90W/square inch of copper) a 1/2" core on a Liebig should provide cooling at around 141W/linear in. or a tad over 5000W (17,300 btu/hr) for a 36" liebig. Is that enough cooling capacity to condense a potstill?

You won't have any problem with a liebig of that size.

My heat source is a propane cooker that maxes out at 150 kbtu/hr or around 44 kW. I use it for crawfish boils and brewing beer. It will heat 12-15 gals of water to a boil in less than a half an hour. It has a water heater type burner (concentric rings of tiny little holes) so it fine tunes down very low. I'm hoping low enough to keep from flooding my column. I know if needed I can use a heat difuser to throttle down to less than 1000W (3410 btu/hr).

A two inch column with more than one meter of packing will handle 1500W easily so you should be OK.

I'm working on getting a stainless ball valve. My soldering/brazing skills are such that I don't look forward to trying to get it connected into the system. Any ideas/suggestions about that?

Stainless ball valves are made to solder into 1/2" copper water systems and solder quite easily. Not much different than soldering brass.

I'm thinking your output rate might suffer with the 3" condenser shell up top. Here's a quote from The Compleat Distiller
If one aperture has 9 times the area of the other, then about 90% of the vapor will flow through it to the
reflux condenser, leaving about 10% to flow to the product condenser. The geometry of the pipes, the
viscosity of the vapor, etc will all affect this ratio, but in the system we’re designing, these effects are
small in relation to the large quantities of vapor, and the errors are insignificant for practical purposes.
The simplest way to do this is by inserting a pipe in the side of the column
head that has exactly 1/9 the cross sectional area of the column itself
(assuming you want 90% reflux).

If you must use the 3" shell up top pack it very tightly with scrubbers or mesh under the reflux coil to provide some level of restriction.

[HookLine]

I'm working on getting a stainless ball valve. My soldering/brazing skills are such that I don't look forward to trying to get it connected into the system.

Don't braze directly onto stainless valves without first removing the valve assembly from the body. Otherwise you will melt the PTFE seals.

Soft solder should be fine, as its melting temperature (about 180-200 C) is well below that of PTFE (327 C.)

Or just get a valve with threaded fittings.

[big_daddy_d]

http://www.pexsupply.com" onclick="window.open(this.href);return false;" rel="nofollow There prices seem to be pretty good. on fittings and valves

[Wai‘ona]

http://www.pexsupply.com There prices seem to be pretty good. on fittings and valves

Their prices are good, but their shipping charges are brutal! I live on the far side of BFE. Shipping from Pex Supply triples the cost.

Thanks for the suggestion though. I do appreciate it.

[Wai‘ona]

Sorry for the slight sidetrack, but i sent Snuffy my figures and couldn't attach a piccie to the PM like he wanted, so here's a pic of my head

Look at all of that stainless! Nice. What do you use to seal the threaded connections... teflon tape?
(definetly got some SS envy going on here)

[punkin]

Yes, i use teflon tape.

[eternalfrost]

well i finally got all the pieces gathered for this and began assembling today. its basically exactly like the one pictured on the first page of this thread, only on a 2" column

how long should the liebig be for 1/2 X 3/4 ??

[punkin]

well i finally got all the pieces gathered for this and began assembling today. its basically exactly like the one pictured on the first page of this thread, only on a 2" column

how long should the liebig be for 1/2 X 3/4 ??

There is calculators on the main site, you just enter your heat input in.

[eternalfrost]

would the heat input be much different then a LM?

I mean its sort of a catch 22, I dont know how much heat ill be putting in till i actually run it

Just looking for a ball park, what do you guys have? 6" 12" 18" 24"? that kind of thing

[punkin]

I just amke the liebigs to handle stripping as well. I usually make a 3/4 x 1" liebig 800mm long unless someone specifies otherwise. That's to handle 2400 watts.

I don't know if it's too much, but i do know it's more than enough