Newbee design check and questions and stuff.

[Sinker]

Howdy folks. Newbee here.

Bit of a long first post, but here we go...

Been seriously reading about distilling for quite a while now, mainly here and at homedistiller.org (and a big thanks to Tony Ackland). I am impressed by the distilling knowledge and craft skills of many of you guys, and it is almost entirely guys, isn't it? Well, here's another sausage.

I have a trade/engineering/science background and interests, so this sort of thing is right up my alley. Small scale home distilling has to be pretty close to a backyard tinkerer's heaven, sure beats tuning the car for the umpteenth time.

I am not a big drinker, just the occasional 1-2 for me, no danger of me ever being an alco, but the prospect of cheap, clean, low-hangover booze is still pretty appealing.

I also use about 5-6 litres of methylated spirits a year for cleaning purposes, sterilising plant grafting knives, etc, and I would love to have a supply of cheap, high purity, high strength, RESIDUE AND STINK FREE ethanol instead of the adulterated crap that is commercial methylated spirits.

I also have an increasing interest in bio-fuels (being able to distill could be useful for that alone before too much longer).

And then there's that tinkering thing.

So all up, you got me hooked!


There are two basic designs that appeal to me as a first still, the Bokabob elliptic plate, and the 45º offset Nixon-Stone valved reflux.

I am currently leaning to the elliptic plate (EL) column, with some modifications, including a fixed upper plate, increased size, and allowing for a future vapour management (VM) port.

Stainless steel (S/S) construction would be nice, but I don't have access to a TIG welder, while I do have access to a friendly plumber, cheap custom cut copper pipe, and brazing equipment.

I will learn to use liquid management (LM) first to understand the behaviour of a basic reflux/fractionating column, and then later add on the VM.

Heat source will be 2000-2400w of electric elements run flat out to bring the boiler with sugar mash to the boil, and then the power level will be cut back to 800-1200w for the main run.

Here is my design so far:

http://i152.photobucket.com/albums/s197 ... gn_v11.jpg" onclick="window.open(this.href);return false;" rel="nofollow

I am interested in any comments or suggestions you may have about this design.

The specific issues/questions I have are:

1. I have one concern about Bokabob's EL design. It has a 1/4" (6mm) vertical clearance between the two plates, for a 1&1/2" diameter column.

I don't see the advantage of such a small, and apparently quite constricting gap. If anything, it would seem to be a disadvantage. Or have I missed something?

Is there a particular reason for having the vertical clearance this small?

Is there any reason not to make the clearance much larger, say 15mm (for a 50mm column), as I have done in my plan? Or even 20mm?

My understanding is that the optimal speed range of vapour flow up a column in ethanol distillation is about 250-400mm per second (10-16"/s). This is not fast, just a gentle breeze. Is this speed range simply too slow to be affected by the constriction?

The valved reflux offset Nixon-Stone style of head avoids any possible problem of constriction by being the same cross-sectional-area all the way through to the condenser. But is this a significant advantage at the low vapour speeds being used?


2. I notice some people set their elliptic plate angle at 45º, instead of 60º (off vertical, equals 30º off horizontal). Is there any advantage to 45º?


3. What is a good size (internal diameter) for the thermometer holder tube?


4. Is 19mm (3/4") the best size for a VM take-off port on a 50mm column?


5. Has anyone had any problems with the non-soldered flange/socket type joints I have drawn for joining the 3 separate column sections together? (The joints will be sealed with either PTFE tape, or dough, during use.)

How deep should the flanges be? How far should one section slide into the other? (I have them at 20mm in the drawing.)


6. How much contact with copper does the ethanol vapour/liquid need to get conversion of sulphides?

Given that my column is going to made entirely from copper, if I use copper mesh packing in the column, do I need to use it for all of the packing, or can I use for just the top 25-30%, and use S/S scrubbers for the rest? Indeed, do I need copper packing at all in an otherwise all copper still?

Is it just a case of more contact with copper during distillation is better?

And lastly, and at the risk of restarting old battles and getting shot at, (takes deep breath), two comments on...


7. Silicon bronze. (UNS number C65500 in particular, but possibly anything from C64700-C66100.)

I have been doing some reading about silicon bronze alloy (not silicone, silica, or silicate), and I cannot find any reason not to use it. Its basic composition doesn't seem to be a problem (96% copper, 3% silicon, 1% manganese, sometimes iron or nickel). It is a very inert material with excellent resistance to degradation under a wide range of physico-chemical conditions, has a similar ductility to plain copper but a higher strength, and is used to build containers to hold strong chemicals. It certainly doesn't seem any worse than standard brass or plain copper from a health point of view, and may even be safer.

If silicon bronze is safe, then:

a) its high copper content might help remove sulphides from the ethanol (assuming the copper component is not rendered too inert by the additional alloying components); and

b) second-hand, silicon bronze, electric hot-water tanks could be good and cheap boilers.

My plumber friend can get new, fully insulated, 50 litre silicon bronze tanks, with a 2400w S/S element, very cheaply (old stock that ain't selling, everyone is going to solar hot water around these parts), and I am seriously considering getting one of these for my boiler.

The only thing to be careful of would seem to be making sure it has no lead residue on the inner surface, and the health authorities (in Australia) would be pretty unlikely to allow much free lead on the inner surface of a domestic hot water tank in the first place.

I will be using silicon bronze rods, the type used by plumbers on copper drinking water pipe, as my brazing filler.

Perhaps The Chemist could comment on this issue?

http://www.corrosion-doctors.org/MatSel ... bronze.htm" onclick="window.open(this.href);return false;" rel="nofollow
http://www.budgetcastingsupply.com/Metals.htm" onclick="window.open(this.href);return false;" rel="nofollow
http://www.suppliersonline.com/property ... #chemistry" onclick="window.open(this.href);return false;" rel="nofollow
http://www.copper.org/applications/arch ... intro.html" onclick="window.open(this.href);return false;" rel="nofollow
http://www.copper.org/resources/propert ... asses.html" onclick="window.open(this.href);return false;" rel="nofollow
http://www.russianbells.com/founding/bronzealloy.html" onclick="window.open(this.href);return false;" rel="nofollow
http://periodic.lanl.gov/elements/" onclick="window.open(this.href);return false;" rel="nofollow


8. Condenser coil shapes.

My point here is not a major one, just a minor one about efficient use of resources.

I am not convinced that everyone in the online distilling community understand how a heat exchanger (condenser coil) works.

I had a nice job many years ago fixing medical and laboratory equipment. Some of this equipment had various kinds of heat exchangers in them, that dealt with various kinds of fluids (gases and liquids) moving around in various kinds of ways. (I kind of already knew the basic principles of distilling before I came to this site. Though I had never read up the detail or done it myself.)

Some of the condenser coils on display here, while very impressive in their construction, and no doubt very effective at their job, seem to me a little on the large side. I understand the need to have a good margin of error, especially for backyard stuff like this, but some of those coils are huge.

An substantially oversized condenser coil has three downsides. First, it wastes increasingly expensive copper. Second, it can waste precious column height, and every 100mm or so of lost packing height is a lost plate (HETP). Third, it may need a more powerful coolant circulation pump.

The main problem is the lack of a proper gap between the adjacent winds of the same coil, and also between the inner and outer coil in a double coil.

If you want to maximise heat exchange efficiency, (that is, minimise the resources required to shift a given amount of heat), then you have to maximise the area of heat exchange surface that the fluid (vapour) will flow around and across for a given size (overall length) of condenser coil, and you can't do that if half the surface of each coil winding is resting hard up against adjacent windings, preventing vapour flow around and between them.

Gap-free coil windings mean you have to use a longer coil, or colder coolant, or faster coolant flow, to do the same amount of heat exchange with same diameter coil tube.

For small tubes, around 6-10mm diameter, the gap between a heat exchange surface (the surface of the tube) and any other surface should be about equal to or slightly less than the diameter of the tube. This is for a vertical coil, like the ones used in many stills, where the coils are stacked on top of each other. Horizontal coils, where the coils are stacked side-by-side, can be spaced a bit closer but still need a decent air gap.

It will probably also improve coil efficiency if you solder some small angled deflector vanes somewhere in the bottom half of the condenser to give the vapours a horizontal twist and get them turning around the coil, in the same direction as the coil is wound (with the wind, not against it). This makes the vapour take a much longer path to the top of the condenser, and pass over much more heat exchange surface lower down.

In the same way as going up to the top of a circular building by a lift is a much shorter distance to travel than walking up stairs spiralled around the walls to the top.

The angle of the vanes would be fairly critical, around 35-40º off horizontal would be my initial guess, and the number and spacing would also be important. The idea is to get the vapour travelling as close to parallel to the coil tubing as possible, without constricting vapour flow (sound familiar?). The vanes will also double as coil positioners, keeping the coil in the centre of the column, and will also help exchange more heat (by increasing heat exchange surface area).

Less copper, less money spent, a little more packing height, and a slightly better product.

I am going to put my money where my mouth is and build a single coil, 200mm long, from 6mm tubing, with good spacing between adjacent winds of the coil, and deflector vanes. The only tricky bit is picking the angle of the vanes. Nothing like a hard objective experiment to sort the guessers from the genuinely insightful. I'll let you know which one I am after the experiment.

My aim with these comments on coils is to minimise the amount of copper, and the amount of column height needed to do the job of condensing.

Okay, your turn. Fire back.


But seriously, that covers all the questions I have left before I start building.

Thanks in advance for any help you can offer.

Elbows up!

[Sinker]

Blank

[Rebel_Yell]

Welcome aboard Sinker.

You seem to have put some thought into this. That is great.

You have so many points and considerations that tend to make your post overwhelming.

I guess that I am one to sit back and say you just go dude and tell us what for....

Try it all and tell us what works.

[hornedrhodent]

="Sinker"
I am going to put my money where my mouth is and build a single coil, 200mm long, from 6mm tubing, with good spacing between adjacent winds of the coil, and deflector vanes. The only tricky bit is picking the angle of the vanes. Nothing like a hard objective experiment to sort the guessers from the genuinely insightful. I'll let you know which one I am after the experiment.

My aim with these comments on coils is to minimise the amount of copper, and the amount of column height needed to do the job of condensing.

Okay, your turn. Fire back.

Would a spiral strip, like is put down the chimney of a gas fridge, do the same as your angled vanes?

[Harry]

Some of the condenser coils on display here, while very impressive in their construction, and no doubt very effective at their job, seem to me a little on the large side. I understand the need to have a good margin of error, especially for backyard stuff like this, but some of those coils are huge.

An substantially oversized condenser coil has three downsides. First, it wastes increasingly expensive copper. Second, it can waste precious column height, and every 100mm or so of lost packing height is a lost plate (HETP). Third, it may need a more powerful coolant circulation pump.

I solved all of those problems and more when I designed the crossflow condenser. Since you know a bit about heat exchange design parameters, I'm sure you'll see immediately the benefits of this concept...
http://homedistiller.org/wiki/index.php/Condenser" onclick="window.open(this.href);return false;" rel="nofollow

It's been built & tested by several independents, and the reports are that it is far more efficient than anything it's size. I have since changed the takeoff & reflux arrangement (for ease of manufacture) but the original fabrication procedure is included in a paper I published. You are welcome to use it to build one for personal use, but not for commercial gain. You'll find it on my Library site...
http://distillers.tastylime.net/library/BAPHS/index.htm" onclick="window.open(this.href);return false;" rel="nofollow

.

[CoopsOz]

Where's the follow-up Sinker? How did you go?

[Sinker]

Thanks for your responses, and pardon my silence. Between a nasty flu, bushfires, and my new ISP seriously playing up, I have been a bit busy and am only just catching up with everything. My apologies.


RebelYell: Thanks for your encouragement. Sorry if I went a bit overboard, I was a bit revved up after all that damn reading about distilling. I probably should have put the two comments on condensers and silicon bronze in separate threads, maybe over in the Research and Theory section. I am happy to do that if other members, especially the moderators, think it is still worthwhile.

I will certainly let you all know how it turns out. Least I can do given how easy the mother site and forums make it.


HornedRhodent: I presume you are talking about absorption based refrigeration, using ammonia, hydrogen gas, and heat. Without having seen a plan or image of the spiral strip chimney, I think the answer is yes. Heat exchangers all work on the same principles, and there aren't too many basic design variations, as far as I know.

There are a couple of new threads related to to this stuff:

http://homedistiller.org/forum/viewtopi ... 33&start=0

http://homedistiller.org/forum/viewtopic.php?t=3344

And Wikipedia have an article on absorption fridges here:

http://en.wikipedia.org/wiki/Absorption_refrigeration" onclick="window.open(this.href);return false;" rel="nofollow


Harry: The crossflow condenser is an excellent design, (as is its counterpart, the shotgun condenser), and credit to you for adapting it over to small scale home distilling purposes.

But from the actual constructed examples I have seen in photos posted on the net, I don't know that it offers big height savings over a properly constructed coil type condenser, for the column heights and diameters used by hobby beverage distillers (approx 500-1500mm height, and 30-60mm diameter).

From everything I have read and seen, it seems that a 150-200mm coil condenser is enough for a 50mm diameter column. But when you take into account the T-connector part of a crossflow condenser in particular, and also the vent tube on the top, a crossflow condenser for a 50mm column takes up a similar overall vertical height to a coil type condenser. The height savings from a crossflow condenser probably start becoming substantial with wider diameter (i.e. higher output rate) columns, say above about 75mm diameter.

As far as I can tell, a crossflow design also has the big advantage of being able to operate with high volume, low pressure pumps, which is very useful for recirculating coolant systems, and hence water conservation. But it also has the disadvantage of requiring a substantially larger volume of coolant flow than a coil condenser. (I could be wrong.) If you run a non-recirculating system with coolant water being supplied straight from the tap, then high back pressure and a low volume of coolant flow are not a problem, and are actually desirable. There is the problem of wasting water, but we are not talking big amounts, and because a coil condenser outflow is just clean tap water it can always be collected and re-used for other purposes.

I am interested to know how you measured the heat exchange efficiency of the crossflow design?

Lastly, the crossflow design also needs extra electrical power to run the recirculating pump. Small amounts, to be sure, but it adds to costs and inefficiencies.


Update on my still project. I have started scrounging around the local salvage shops, off cuts bins at engineering firms, and friend's scrap collections. A friend of a friend had a good condition S/S beer keg sitting unused in the back of his shed, he was going to make a still but never got around to it. The keg still had the valve assembly and old beer in it under a fair bit of pressure, as my friend found out when he pressed hard on the ball valve with a screwdriver. Old warm beer shot out and covered him from arse to tit. Interesting smell. Good thing it happened outside. And pretty damn funny. At least having beer in it under pressure for that long means the keg has no leaks. Cost $40 (Australian). Is that reasonable for a keg? It was certainly cheaper than the alternatives.

I still think silicon bronze is worth checking out as a metal for boilers. Silicon bronze hot water tanks are relatively cheap and common. Although the ones I saw were noticeably taller than a keg.

Also checked out 1/4" S/S needle valves. $110, including delivery. Ouch! But no surprise. Like most people, my hobby money is limited, so I might have to go for brass (treated, of course).

Cheers for now.

[speedfreaksteve]

Very well thought out for a newbie!

You might want to also consider looking into the alternative of using propane as your heat source. When I first started I used electric but found that a propane burner was really much faster and more consistent. Very inexpensive as well.

[Sinker]

Thanks for that Steve. Again, pardon the delay in responding, I am still catching up with everything at my end.

I did consider propane, and obviously it works well and safely, but I decided on electricity for a bunch of reasons, such as:

Electricity is pretty cheap here, and I will only be doing half a dozen runs or so a year, and I don't have any other use for the propane.

Electrically generated heat is very convenient and constant, and can be controlled very accurately (although propane is pretty good if you don't have wind to contend with). Plus I have some electronics/electrical in my background, so I can work with electricity no prob.

One of the big pluses of electricity is that if you use an internal heating element you can thermally insulate the entire outside of the boiler, which can significantly improve energy efficiency, and reduce boil up time. The insulation I will be using for the boiler is a foil-backed, plastic bubble-pack called 'Air-Cell', which is used for building insulation. (It is leftover from renovations at my house, and works very well for buildings, don't know about for boilers yet). Air-Cell is extremely easy and safe to work with, and has a melting point of 145ºC so it should be fine for distilling temperatures. But obviously it wouldn't handle a naked flame at all.

http://www1.aircell.com.au/pages/residential.aspx" onclick="window.open(this.href);return false;" rel="nofollow

A burner ring under the boiler also adds more height, at least another 100-150mm (4-6"). And overall height is an issue as I am now going with a much longer column (see below).


Update to my still project:

I have just about finished building my first coil condenser design, it is all formed and cut, I am just waiting on some 10mm end caps before I solder it all together. I don't have a digital camera, but when it is done I will borrow one to post some photos here, and definitely some design drawings and notes. And for the still as well.

There are some interesting photos of condenser coil winding here:

http://www.pjmuth.org/still/stilpix.htm" onclick="window.open(this.href);return false;" rel="nofollow

and here:

http://homedistiller.org/forum/viewtopi ... ght=hornys

My plumber friend got sacked from his job, and so doesn't have access to cheap copper pipe anymore. After a bit of scrounging around various places I picked up a nice piece of thin walled S/S tube (not thick walled pipe), 50 x 2000mm, for $60 (Australian), which is less than the retail price of 1000mm of new copper pipe. So now I will be able to get much more packing height, which is nice.

I am not cutting the top out of the keg, and instead will be mounting the column onto the Sankey fitting. However, fitting the 50mm S/S tube column to the Sankey is a bit tricky. I ended up getting BSP pipe fittings. But I'll explain the details of how I did it when I get some photos.

Have now got all the bits for the boiler and column, so off to the welder next pay day. (S/S welding is for pros, not amateurs like me.)

With a bit of luck I might have it ready for the first drinking product run in time for a Xmas present to myself.

Cheers for now

[nanosleep]

There are two basic designs that appeal to me as a first still, the Bokabob elliptic plate, and the 45º offset Nixon-Stone valved reflux.

My vote is for the inline head. I've never built an eliptical, but the design looks reasonable. I have used a nixon-stone type, and a "single reducer" inline type. I didn't like the nixon-stone since it was unbalanced, consumed more height, and cost more to build.

I will learn to use liquid management (LM) first to understand the behaviour of a basic reflux/fractionating column, and then later add on the VM.

Consider a threaded fitting at the top of your column. This allows easy change out of different head designs. Also thread your boiler using the same fittings. This allows you to attach the head directly to the boiler for potstill operation.

Heat source will be 2000-2400w of electric elements run flat out to bring the boiler with sugar mash to the boil, and then the power level will be cut back to 800-1200w for the main run.

Depending on your boiler size, you may want more power for heat up. I use 3000 watts to heat up a 3 gallon (~11 liter) boiler and sometimes I get annoyed at the heatup times. On the other hand you may not be able to safely draw more power without upgraded wiring.

The valved reflux offset Nixon-Stone style of head avoids any possible problem of constriction by being the same cross-sectional-area all the way through to the condenser. But is this a significant advantage at the low vapour speeds being used?

I don't think the vapor speed has any importance after the vapor has left the packing. The importance of vapor speed while in the packing is to give sufficient transit time and avoid flooding the column. As long as the clearances in the head don't "hold up" liquid you should be fine.

2. I notice some people set their elliptic plate angle at 45º, instead of 60º (off vertical, equals 30º off horizontal). Is there any advantage to 45º?

The advantage is your miter box has a 45 degree slot. No differences that I'm aware of. The purpose of the eliptical plates are only to hold back some liquid so it will run out the valve. Minus the eliptical plates the column would operate totally happy under full reflux.

3. What is a good size (internal diameter) for the thermometer holder tube?

I don't use a thermometer holder tube. I use a cheap meat thermometer. The probe is stainless steel and great for direct insertion into the column. I use a compression fitting on the thermometer shaft to get an airtight fit. If you have a holder tube, make sure your thermometer probe gets good contact with the holder tube. Perhaps use some heat sink compound (cooking grease for the non-toxic version).

5. Has anyone had any problems with the non-soldered flange/socket type joints I have drawn for joining the 3 separate column sections together? (The joints will be sealed with either PTFE tape, or dough, during use.)

I've tried using a solder type collar, but with no solder. I used teflon tape to seal the gap. This worked poorly since it was a serious pain to get the tape to stay in the gap during assembly. Threaded connectors are much better. Use threaded connectors not a union as the unions are typically much more expensive. Use teflon on the threads to avoid jamming after a heat-cool cycle.

6. How much contact with copper does the ethanol vapour/liquid need to get conversion of sulphides?

I use stainless packing in a copper column with no problems.

My plumber friend can get new, fully insulated, 50 litre silicon bronze tanks, with a 2400w S/S element, very cheaply (old stock that ain't selling, everyone is going to solar hot water around these parts), and I am seriously considering getting one of these for my boiler.

You won't have a convenient way to clean the boiler. This limits your mash to feedstocks that don't have solids (sugar, juice, etc).

The only thing to be careful of would seem to be making sure it has no lead residue on the inner surface, and the health authorities (in Australia) would be pretty unlikely to allow much free lead on the inner surface of a domestic hot water tank in the first place.

I don't know your laws, but here it's illegal to use lead in any drinking water system.

The main problem is the lack of a proper gap between the adjacent winds of the same coil, and also between the inner and outer coil in a double coil.

I originally built a double coil style. If I built another I would probably only do a single coil, but pack it with copper or stainless scrubbers. The scrubbers will be in tight contact with the coil and will transfer the heat well (copper especially) and will provide heaps of surface area. My current coil is only 4 inches long (10cm) and uses surprisingly little water. I use water from the tap so I don't need any pump or have any problems pushing through the tubing in the coil. Other condenser designs may be better suited for recirculation and a pump.

It will probably also improve coil efficiency if you solder some small angled deflector vanes...

The vanes are going to be a pain to build. Scrubbers provide the same benefits and are very easy.

Hope this helps.

[Sinker]

Thanks for the considered response, Nanosleep (great handle).

Particularly appreciate the two bits of info about the reliability of slip/collar type joins, and how much copper to use.

Other points of interest are:

"I don't think the vapor speed has any importance after the vapor has left the packing. The importance of vapor speed while in the packing is to give sufficient transit time and avoid flooding the column. As long as the clearances in the head don't "hold up" liquid you should be fine."

You are probably right about the vapour speed above the packing. But I wonder if maybe there is some small back pressure generated by the partial restriction from closely spaced elliptic plates, and if that back pressure might help keep the column in equilibrium during operation. The restriction might help buffer the column against vapour speed/pressure changes in the packed section, and hence buffer against temperature changes. Just a thought.

In regards to using hot water tanks for boilers you say:

"You won't have a convenient way to clean the boiler. This limits your mash to feedstocks that don't have solids (sugar, juice, etc)."

Good point. I ended up getting a s/s beer keg, and I am getting a drain plug put in the bottom, so it will be pretty easy to flush out. I am also only really interested in the cleanest neutral vodka possible, so so will only be running sugar mashes.


"I don't know your laws, but here it's illegal to use lead in any drinking water system."

Generally illegal here too, but standard plumbing brass fittings contain small amounts of lead to allow for easy machining, so there are some exceptions to that rule. Silicon bronze has a lead-free composition, but sometimes when casting metals they use various linings on the mold for easy release, and these linings can leave a residue on the final product, that is all I was concerned with.


"Depending on your boiler size, you may want more power for heat up. I use 3000 watts to heat up a 3 gallon (~11 liter) boiler and sometimes I get annoyed at the heatup times. On the other hand you may not be able to safely draw more power without upgraded wiring."

I will be heating about 40 litres at a time. I work from home so managing long runs shouldn't be a big problem. I also live in a warm climate and can take advantage of plenty of sun to preheat the mash. If it still takes too long to heat up I will get another element socket welded on and run two elements. My house has more than one power circuit so there isn't a problem running higher power heating for short periods. I also have some serious boiler insulation, which should help a lot.


"The vanes are going to be a pain to build. Scrubbers provide the same benefits and are very easy."

You might be right about that too. Though I have a one piece vane design that is relatively simple to build and attach. Still haven't tested it coz the stainless welding ain't done yet. Will post some photos when it is all finished (and I borrow a digital camera).

The more I think about coil condenser efficiency, the more I agree with the Amphora guys who use 3/16" copper tube, which is a whole lot more efficient at heat exchange than 1/4" tube. The only problem with 3/16" tube is that it is very difficult to buy it by the metre (here at least), you have to buy a whole 30 metre roll when you only need about 2-3 metres. But it is easy to buy 1/4" by the metre.

Cheers and Best of the Season.

[Kiint]

I just finished my first Still design on the weekend and put the first run through on Tuesday. The end result was a slight metho smell, but a very clean taste. I am currently running it through an Essencia Pot Filter (ceramic and carbon) to polish it a little, but other than that it appears to be very palatable compared to the Essencia turbo stills.

The one thing I have noticed though is how critical my reflux valve is to its operation.

To give a quick rundown ...

It is a SS Keg with the top cut out to fit a 50mm flanged nut which is brazed to the top. Then a threaded fitting is at the bottom of my column which screws into the flanged nut of the keg.

The boiler uses a 2400W element from a hot water heater ($108 ouch) to do the boiling which is always running at 100% with no thermostat or rheostat to turn it down.

The whole column, condenser assembly is 100% copper, it consists of 1300mm of 50mm pipe to 2x 50mm T pieces. The T's are joined into a H with 50mm x 50mm. The digital thermometer fits into the top of the end cap at the top of the T above the column, while the condenser go's on the top of the other T with the collector at the bottom of the same T as the condenser.

There is an endcap at the bottom of the condenser T with a 6mm tube soldered to it and a 6mm T which feeds into the reflux. From the other side of the T go's to a valve which controls the reflux.

Its an extremely basic design, nowhere near as elaborate as many of the designs here, however it works and produces a higher quality product than the essencia stills commonly available in Australia.

The curious thing I noticed compared to using the essencia stills is that the valve on mine (which the essencia doesnt have obviously) dictates exactly how the still operates. If you crack it open full on first boil, then the coumn overheats past 80deg very quickly. I have worked out its best to keep closed till it comes up to temp keeping the still in full reflux.

Once its up to temperature, you then crack it open slighly to begin collecting but always making sure there is reflux happening. If you crack it open full with no reflux the column shoots to over temp.

However the stages it passes are quite noticable, from 78.6 for the heads, to 78.9 for mids (about 70% of collected liquid) its quite reliable. However once you are in the tails (from about 79 upwards) it begins to shoot very quickly, so I know I am definately collecting the most possible.

*edit* Anyone know an easier way to solder 50mm copper pipe, the MAPP bottle just wont get the heat into it, so all my soldering looks like crap, but is still sealed well, just lumpy and runny *edit*

[HookLine]

Howdy. It is actually Sinker here, I had to re-register for some reason and couldn't re-use my original handle.

Finally finished my still and tried a couple of runs.

Here's my pics and notes. I have only posted five of the pics I took. There are a whole bunch more in my Photobucket album:

http://s152.photobucket.com/albums/s197 ... ?start=all" onclick="window.open(this.href);return false;" rel="nofollow







The column is 50 x 1800 mm stainless, with 1500 mm of structured mesh packing.

Ended up going for VM because I am after vodka and VM seems the best for the job, is easier to clean out than an LM slanted plate (Bokabob), and welding stainless plates into the column seemed too fiddly. (As soon as I can find 500 mm of 50 mm copper tube I will also build a copper pot column for stripping runs.)

The stainless welds were done by a pro, who didn't blink when I gave him the job. He had some kegs sitting at the back of the workshop, so he probably does a few stills a year. I am very happy with his work, but I wasn't his highest priority and it took a couple of months to get it done. There were two tricky bits. The first was aligning the 50 mm BSP nipple with the column. The stainless nipple is designed for pipe not tube, and the inside diameter of the nipple is about 2.5 mm greater than the outside diameter of the column tube, so there is a gap between them and the nipple doesn't sit flush on the column. But the welder did a real good job of centering it and aligning it with the column, and when it is screwed into the boiler the top of the column is only about 10 mm off centre, and this is easy to get vertical with a thin spacer under one side of the boiler. The second tricky bit was welding the 10 mm thermo tube into the VM socket, for some reason it was hard to get the weld to start on the tube, but it turned out fine. All the custom stainless welds, and the whole keg, were also treated with phosphoric acid after all the work was done.

The 10 mm thermo port tube is drilled out so a piece of 6 mm copper tube just fits inside, and the thermo probe just fits inside the copper tube, all sealed up with a few turns of PTFE tape. Both tubes have a slight tapered ream in the top end to allow the PTFE to slide in easily and make a better seal.

The mesh retainer is made from a cheap stainless steel kitchen sink food trap, and it slips in and out of the boiler connection easily. It probably isn't necessary as the mesh seems to stay in place by itself.

The heating element in the boiler is a standard 2400w water heater element, with the tin/zinc(?) coating stripped off. I replaced the standard rubber seal that came with the element, with a nitrile rubber o-ring.

The power controller is a 3kw burst fire module.

The boiler insulation is two layers of Aircell building insulation, that has a maximum operating temperature of 140ºC. Interestingly, Aircell is also used for insulating wine vats.
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The condenser section of the Liebig is 800 mm long, with a 20 mm centre tube inside a 25 mm cooling jacket.

The product pipe at the bottom of the Liebig is only held there by the cord, but is quite secure.

The reflux coil condenser is 180 mm long. Coolant flows down a 10 mm tube in the middle, out into the t-piece, and back up the coils.

The important features of the reflux condenser are that 1) the inner and outer coils are both wound in the same direction, which allows the vapour to turn around the coil's axis; 2) there is regular spacing both between the turns on each coil, and between the two coils; 3) the inner and outer coils are staggered vertically against each other (as best I could): and 4) the short copper tabs around the outside of the condenser, about 1/3 of the way from the bottom, which are spacers to keep the it centred in the column. I believe these four features improve the efficiency.

It is a fiddly design to build, and if I built it again, I'd ditch the t-section at the bottom, and the cap at the top, they are the tricky bits. (Although the cap helps to make the overall condenser a lot more rigid.)


When it was all finished, I put it together and closed off the gate valve, and filled it with water to check for leaks (an excellent suggestion, whoever made it). Didn't find any.

Then I fired it up for a water test run at 2400w (without any insulation, or packing), using tap water at 26.5 ºC for coolant, and adjusted the coolant flow rate for a coolant out temperature in the high 40s ºC:

Liebig condenser only (ie, in stripping mode). With a coolant flow of 1.25 litres per minute, coolant out was 47.5ºC, and product out was 26.5ºC. Only the top 1/3 or so of the Liebig condenser got warm/hot.

Reflux coil condenser only (ie, full reflux, gate valve closed, without vanes, water running into the 10 mm centre tube). With a coolant flow of 1.1 litres per minute, coolant out was 47.7ºC. About the bottom 5 turns of the outer coil (about 1/3 of condenser length), and about 1/2 the inner coil, were wet with condensate.

Lastly, I did a vinegar run without any cooling water to help clean it all out.

When I did my wine run (see below), barely the bottom 3 turns of the outer coil, and 5-6 turns of the inner coil, on the reflux condenser got wet with condensate (with coolant in temperature at 27-28ºC, and coolant out at 42-45ºC, and a flow rate of about 600 ml/min). When I get my pot column I will do a bunch of careful tests, including trying reversing the direction of water flow through the condenser, and of course also try the vanes.

By the way, what everyone here calls a 'double helix' isn't technically correct. A true double helix is two identical coils interwoven between each other; that is, offset by some amount around a common axis.

The standard home distiller's version of a double helix is more accurately described as a 'double concentric counterwind'.

The 800 mm Liebig is probably about 300 mm longer than it needs to be. Only the top 30-40 mm or so got warm during the alcohol run, and during the flat-out 2400w water test run only about 250-300 mm got warm, and that was with coolant water going in at a relatively warm 26-27ºC.


I did a wine run with 20 litres of some crap red wine that was on special at the local booze mart.

After heating up and then equilibrating for an hour, I very slowly bled 50 ml of foreshots off at one drop a second. Then opened the valve up a bit and took the next 500 ml off at one and half drops. Finally opened a bit more to three drops and sat there for the rest of the run.

I pulled 2.3 litres of crystal clear spirits, at 95%. (Expected yield was about 2.5 litres, but by 1:30 in the morning, with the vapour temp rising and the output rate falling, I'd had enough and called it quits.)

The foreshots came off easily enough. But the whole rest of the run had a real raw funky edge to it, with no clear distinction between the heads, hearts and tails, and it was undrinkable. So I sat it on sodium bicarbonate for a few days and on the second run the cuts were easy to do and it came out real nice, I reckon even better than the store bought stuff I am using for a comparison (though obviously I am biased, ha ha). So the bicarb worked very well.

I ended up with five 700 ml bottles of 38%, which is fine by me.

Last week I did my first run using my own ferment (45 litre, 12%, 'Heat Wave' Turbo). This time I did it in a single run, and also took the hearts off at 6 drops a second. It went very well, and I got 9.5 litres of 38% that was nice and clean.


Most credit for this project belongs to the online distilling community for the mountain of great info, so a big thanks for that, folks, it wouldn't have been remotely possible without it. Learning about distilling and building a still has been a great experience, although I have a lot more to learn about driving it and fermenting.

Also, a couple of friends of mine deserve some credit for helping out. Thanks guys, your reward will be delivered soon.

Now to make the damn thing pay back its cost.

Any questions, please ask.

Cheers

[stillbill]

Hi
Your long post has got me thinking, especially in regard item #8. Has anyone combined a Liebig and coil condenser into one? To me the added cooled surface of coil condenser would have to be a plus and add to it's efficiency and may leed to a size reduction.

[rad14701]

Hi
Your long post has got me thinking, especially in regard item #8. Has anyone combined a Liebig and coil condenser into one? To me the added cooled surface of coil condenser would have to be a plus and add to it's efficiency and may leed to a size reduction.

That would be a Graham Condenser...

[pHneutral]

Hey Tac,

I think some people just like making beautiful equipment

Also, a good VM setup will give you reliable flow through the entire run, and won't sputter or peter out. It also requires a lot less attending than other designs. And, if you've sized everything right, and done everything right, then you have less to worry about when it comes time to do a run. A VM setup will also make it possible to get higher purity with a shorter column.

But, if you just want some rum or whiskey, a good 'ol pot still will do just fine. Or if you just want 140 proof vodka, a non refluxed column will work just fine.

To give you an idea of how much better a good VM setup can do, I have a very short column (14" or so) on a VM style head, and it can takeoff at 170 proof, and can even go up to 180 in the center and beginning of the run. Slow as a snail, but it works. If I had a 48" column, I'd be doing a bit better

[Mr.Spooky]

off topic,,,, but what kinda plants are you grafting?
spooky

[Azures]

The main problem is the lack of a proper gap between the adjacent winds of the same coil, and also between the inner and outer coil in a double coil.

give the vapours a horizontal twist and get them turning around the coil, in the same direction as the coil is wound

This was my justification for the cooling in my design.

the pipes flush up against the outer pipe and inner pipe produce a helix passage which forces the vapour to take along spiralling corridor running up against distillate running down the corridor.

the corridor would need to be wide enough to avoid flooding but close enough for efficient heat exchange.

I accept that it needs of soldering to tack the cooling tube against the inner pipe.

Vm would be taken from below this cooling spiral head thingy, not in the diagram


2" diameter @ 1 twist per inch.

Path per 1" height = 2 * 3.14 = 6.28"

So 6" of cooling height = 6.28" * 6 = 37.5"

6 inches of height is equivalent to 3.125 feet or 95.25cm of cooling..... nothing is getting out the top.


this is modification from my original idea here ---> http://homedistiller.org/forum/viewtopi ... 17&t=19327

[rad14701]

I'm still not sold on the idea of blanking out the center of the reflux coil, and here's why...

You have a given amount of vapor entering your condenser section at a specific temperature and vapor speed... If you blank out (omit) the air void in the center of the condenser coil you will be causing the vapor to accelerate as it is forced to travel up between the coils... Then some of that vapor will condense and become liquid spirits which will then further constrict the area that the vapor has to travel in, further speeding in oncoming vapor... Sooner or later you will end up with flooding or vapor escaping the top of the condenser unless you run slow enough to compensate for the built in deficiency...

I'd like to hear your rationale for wanting to blank out the center of the condenser rather than leaving it open, filling it with structured packing, or using a cold finger... All you are doing is making a simple, tried and proven, condenser into one that is less efficient...

If anything I would have the top of the center tube capped, not the bottom... That way you would at least have ample condenser section volume to eliminate the increase in vapor speed... You would also benefit by having additional surface area for condensation on the inside of that tube which would otherwise be wasted...

Another issue that you haven't calculated is reflux centering... As designed, that condenser will be returning the condensed reflux down the side wall of your column, not down the center... And you have no elegant way of redirecting the reflux towards the center without adding yet another complex piece to the design... I see a snowball effect happening here...

If you think long and hard about what I am proposing, compared to your current thought process, you will discover that you are either over-thinking or under-thinking the processes at work here...

[Azures]

So now the cooling tube is bent and elongated to the centre, reflux will follow the pipe to the lowest position and then drips down the centre.

Provided the passageway is of suitable height the reflux running down should not block the gas vapour travelling up.

The increase vapour speed from bottle neck, would (hopefully) be countered by the greatly extended distance that the vapour must travel.

[Azures]

I'd like to hear your rationale for wanting to blank out the center of the condenser rather than leaving it open, filling it with structured packing, or using a cold finger... All you are doing is making a simple, tried and proven, condenser into one that is less efficient...

If the helix condenser is not closed in the centre the vapor will travel the easiest route, and will not enter the helix passage.
So it must be closed with only one option, to travel threw the helix.

cold finger is simple. just flood the centre with coolant.

I welcome all criticism, it is a working design.

I agree tried and tested way are very successful, but its nice to a have think and chat to exercise the grey matter.
Maybe we'll develop something better
...... probably not

[rad14701]

Well, the vapor doesn't go up the center of my single coiled condenser and escape... And, as mentioned, a bit of scrubber down the center would suffice...

As for the last drawing, you've re-invented the gloved cold finger design - a coiled condenser wound around a cold finger...

Yes, it is good to think of new ideas, but only when they are truly new ideas and not just new to you... Keep researching and keep thinking...

[Azures]

Well, the vapor doesn't go up the center of my single coiled condenser and escape...
re-invented the gloved cold finger design - a coiled condenser wound around a cold finger...

Yes I agree the vapour would not escape your single coil, they work well (Which is why I'm gonna make a conventional coil for my first build )

but with the helix path, this condenser could be 1/2 or 1/4 the height of your single condenser.
saving height on expensive 2" copper pipe, which can be given back to reflux column.

This is what I thought could be the benefit. more efficient use of height, with same cooling power, without increasing the coolant rate of water. Yay? Nay?

So its called gloved cold finger , flush up 'against the outer tube as well as the inner tube.

Maybe easier to make less 1/4 tubing required. larger mandrel to bend around = less flattening.

[micale]

Would a spiral strip, like is put down the chimney of a gas fridge, do the same as your angled vanes?

[yamastill]

I am building my boka this weekend and cant wait to get started. I plan on using a trash can to recirculate the water and a old car radiator I have kicking around. What do I use for a pump? Pressure? Volume? where to get?