Introduction and ARC Still questions (Not 56k friendly)

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Perch
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Introduction and ARC Still questions (Not 56k friendly)

Post by Perch »

I guess I will start with a brief introduction. I'm a Mechanical Engineering Student from Winnipeg, Canada. Last year I was bitten with the distillation bug and have followed this forum every since.

I had originally intended to build a valved reflux still. That was until I happened across this site. The article entitled "Simple Low-cost Stills" contains a section (Page 22) detailing what the author calls an "Automatic Reflux Control" I was fairly intrigued by this concept but have yet to find any further information to back up his theory. Does anyone have any further insight?

SolidWorks and I spend a couple nights together and I created a model based on the "ARC" design detailed by the author here.

The specs I designed to

- Stainless 15 gallon Keg
- 304 Stainless flanges
- Cork flange gasket
- Heating element still undetermined (depending on column size, probably 3000watt with voltage control)
- 3" column, 5' tall (length of packing)
- Copper mesh packing (White in pictures)
- Cooling coil, 1/4' tube, 12" high
- Airlock, 1/4" tube
- ARC, 3/8" tube, 2' long

Here are a couple screen shots.

Still cutaway
Image

Boiler cutaway
Image

Top-end cutaway
Image

ARC cutaway
Image

Air-lock
Image

Problems I foresee

- I have a history of designing with a "go big or go home" attitude. Is a 3" column to big?

- I'll probably simply the flanges, depending on what column size I use. Probably go with a 4"/6 bolt pattern rather than the 8" and 12

- I'm concerned about vapour flow through the funnel below the cooling coil. Either I'll add some venting, or redesign with wires to channel liquid to the bottom funnel.

- The cooling coil is still in early development. I just threw together something for demo purposes. I need to run the numbers and find my optimal surface area/heat transfer configuration. Possibilities are 2 separate 1/8" coils, a tapered helix configuration or a combination of both.

Well, I think that about covers it. I would really appreciate input on this design. What do you guys think?
stillman
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Post by stillman »

I can't give you any advice on the Technical aspect of making a still. But I wanted to write that your drafting is awesome. Gives a great look at what's going on compared to a 2D sketch. Can you animate it?
You bring the fair maidens, I'll bring the panty-remover.
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Post by Brett »

looks along the lines of a glorified bokabob still?
Plastics n stillin sucks
alluminium n stillin sucks
Dont go there
NUFF SAID
Swag
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Post by Swag »

Very interesting concept, sort of like a coffee perculator.
It looks like your center tube doesn't go down very far. I thought 80% of the column height was typical.
I don't think you have to get fancy with your coil. A 10" coil of 1/4" tubing in a 2" housing should be plenty.
rectifier
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Post by rectifier »

A couple nights no kidding! Your model is exquisitely detailed. I love Solidworks but haven't used it since going Linux on my computer. I miss it.

I too would love to hear more about ARC, but there seem to be a very small number of people (perhaps only one?) who are involved in its development.

I get the theory, but what happens during operation is a bit of a mystery. Electronic ARC with a valve is simple, but the various pressures/purities/temps in a "mechanical" ARC do not seem like they would operate in a very predictable manner.

Decoy, want to build a glass one so we can see what's going on? :lol:
Perch
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Post by Perch »

stillman wrote:I can't give you any advice on the Technical aspect of making a still. But I wanted to write that your drafting is awesome. Gives a great look at what's going on compared to a 2D sketch. Can you animate it?
Thanks stillman, but I can't take all the credit. These days, 3D modeling programs are very powerful. It's crazy what you can do with them and how relatively simple they are to pick up. If you were to run through the tutorials for a couple hours, you could produce similar results. I haven't dealt much with animation, but I was seriously thinking about it. I'll see if I can find some good adobe tutorials :)
Swag wrote:Very interesting concept, sort of like a coffee perculator.
It looks like your center tube doesn't go down very far. I thought 80% of the column height was typical.
I don't think you have to get fancy with your coil. A 10" coil of 1/4" tubing in a 2" housing should be plenty.
Ya, I wondered the same thing. The still I modeled it after was in similar proportion. A 1.6 m (63") column and 60 cm (2ft) ARC. The difference being he only was using a 1.5" column. I designed to a 3". Thanks for the info on the cooling coil. What are you thoughts on using a 3 " column? I'm seriously thinking about starting with a 2" and getting a working ARC and then moving to a 3". I'd ideally like to try my hand at introducing vacuum into the system. I just need to take the baby steps first. :wink:
rectifier wrote:A couple nights no kidding! Your model is exquisitely detailed. I love Solidworks but haven't used it since going Linux on my computer. I miss it.
Solid modeling is a passion of mine, I loose all sense of time when drawing. It's sad sometimes :D I've been working with SolidEdge the last little bit and it has some neat features that dare I say, exceed SolidWorks.
rectifier wrote:I too would love to hear more about ARC, but there seem to be a very small number of people (perhaps only one?) who are involved in its development.
Ya, I get that feeling too. Guess that leaves lots of room for research and development?
rectifier wrote:I get the theory, but what happens during operation is a bit of a mystery. Electronic ARC with a valve is simple, but the various pressures/purities/temps in a "mechanical" ARC do not seem like they would operate in a very predictable manner.
We're in the same boat here. I'm still having a hard time wrapping my head around the idea that when the liquid in the ARC is boiling, the liquid coming from the cooling coil will overflow the funnel rather than flow out of the product take off tube. I was hoping someone could clear that up for me. How and why does the output flow stop because the liquid in the tube is boiling?. I think I'm going to take a picture of my "Water distillation" device to my Fluid dynamics teacher and see if he can explain it.
rectifier wrote:Decoy, want to build a glass one so we can see what's going on?
Can I second that motion?
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Post by possum »

Interesting.The bit about the funnel overflowing and not siphoning or pushing out the product take off tube... Are the tubes all drawn to a relative scale? Is the tube under the funnel larger diamater than the product take off tube ? Does the outlet tube make the bend above the funnel...

Also did the design include a testamonial after it was run, or was it like: Boy this can't fail, the design will wash your dishes, clean your car and cure 15 deadly disseases ?

Is this the "oh my gosh I cant belive I don't have to moniter the reflux rate or vapor temp still" ?

Garunteed to not let the tails come across ?



This could be cool.


A glass collumn would need only one hole in the side.


Sorry for grillin' ya perch, This has me confused and excited, dangerous combo for me :lol:
Hey guys!!! Watch this.... OUCH!
Perch
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Post by Perch »

Well, I'm just going to pull a nasty cut and paste for this section of Riku's article. It will be easier to quote and dissect.
Riku wrote: Automatic Reflux Control (ARC)

The newest gizmo in amateur distillation is ARC, which is generally used to control a regular LM head. The idea in ARC (to my knowledge first introduced by “Farbror Plast”) is to use the temperature at the top third (or so) of packing to control the output/reflux ratio. The actual system is amazingly simple and can be attached to most LM heads. Here are few pictures of building an external pipe version.
Image
PIC – EL-ARC – note, sensor pipe was lengthened later. Note, in the picture I have used silicone hoses. I recommend you use a 5-6mm copper pipe instead.

From LM heads product takeoff you have a copper pipe (8-10mm have been successfully tested) that is sealed at the bottom end, goes down 80% of packed column height (i.e. 80cm pipe for 1 meter column) and is soldered to the outside of column pipe to get good heat transfer. About 20 cm from the top of the pipe is the actual products take off. From the takeoff we have vapor lock and the pipe goes up again to 1-2cm below the liquid surface on LM reservoir and back to collection vessel. On the highest point of this product takeoff is a ventilation hole to prevent siphoning (required for at least smaller pipe diameters).

The principle of operation is that the liquid at the bottom of the 80cm pipe will boil if the temperature at the lower parts of the column where the pipe is attached is higher than the boiling point of liquid inside the sensor pipe (in practice 78.1-2C since it’s the first stuff that reaches the top of the column). When the liquid boils no liquid will enter the product takeoff tube, but all is returned to column via LM head due to pressure difference. When the temperature at the column (in the part where the pipe is soldered to) evens out the boiling stops and liquid will start to flow out of the product takeoff. This causes less reflux and the temperature in the lower part of the column starts to rise. When it’s high enough the output stops and the cycle starts again. In practice this works very well. It adjusts the reflux ratio automatically and stops the collection before any higher boiling point alcohols have a chance to get to the top of the packing.

This system gets rid of the tails but there is still the problem with heads. Several methods to get rid of the heads are researched, but I’ll present here the simplest one.
Image
PIC-heads-collection-bottle

With this system the heads will go to the bottle, and when it’s full to the set limit (ventilation hose/pipe inside the bottle) product will start to flow to the collection vessel. The amount of heads can be adjusted by varying the length of the hose/pipe inside the bottle. The ventilation pipe/hose needs to go above the point where pipe to product vessel leaves, as liquid inside the ventilation pipe will rise to this level. The vaporlock in the tube prevents heads in the bottle from contaminating the product and also enables the adjustment by vent pipe. Otherwise the liquid in the bottle would rise up to the actual feed tube bottom. I recommend this type of system to be built from 8mm pipe as minimum diameter
Image
PIC-Heads collection bottle in practice (built from leftover parts).

So, an example of easy to operate system at the time I write this (actually my current test rig):
1.6 meter column,
40mm wide
700W power (uninsulated fermentation bucket)
1-meter (or a bit more) convector pipe for reflux cooler
ARC to control product takeoff (internal sensor pipe is nice)

Bottle system for heads Fill the boiler, set up heads collection system, turn on the power and let it run. After 14 hours or so (could take a bit more) turn off the power, store heads, empty and clean the still, dilute the ethanol and enjoy the product.

A limitation of external sensor pipe ARC is that it won’t work well with high % (over 20%) mashes. To counter this problem an internal sensor pipe can be used. After some trial and error I constructed following simple to build modular system that has worked very well.

To start with I have a 40cm piece (for 1 meter column, 60cm for 160cm column) of 8mm copper pipe. It’s pressed shut at the lower end, this allows slow dripping of contents meaning that heads won’t stay at bottom of the pipe. At the top I have a double funnel (or funnel with drip ring) where reflux from condenser drips to (you may need a small guide or collar to direct drips to funnel). The ethanol that’s not removed via ARC will overflow and drip from the bottom of the funnel/ drip ring to the packing around the sensor pipe. ~6cm below the funnel top we have a product takeoff from sensor pipe. This is a 6mm pipe that goes through the capillary joint and has a vaporlock and ventilation hole arrangement outside the column, just like with external sensor pipe version. Through the capillary joint you can solder a piece of 8mm pipe. 8mm pipe can be used as a capillary joint for 6mm pipes (seal with PTFE tape) meaning that you can make modular system as shown in picture where the external parts can be removed during disassembly. Another good thing about such setup is that you can use this to adjust the height between LM reservoir and highest point of product takeoff (i.e. actual take off rate). By turning the entire external vaporlock system to an angle in relation to column centerline you can lower the highest point of takeoff tubing and increase the takeoff rate. This is very useful in fine-tuning the system performance. Once it is set you can mark the angle and duplicate the setup for consequent runs. After building this just wrap some mesh/scrubbers around the sensor pipe and insert it into the column. PTFE tape is again used to seal the joint and column is filled from below for the rest of the packing. In my tests I was able to halve the amount of heads by using this version when compared to external pipe version. When tested with 160cm column and 60cm sensor pipe it produced extremely pure ethanol and ceased output before any tails did appear. With 100cm / 40cm combo the ethanol was very good but there was a very faint sweet taste from burned sugar.
Image
PIC – drawing of internal pipe ARC

Image
PIC – internal pipe ARC in practice

Image
PIC – Fine-tuning ARC output

Now the latest innovation for removing heads (pioneered by “Farbror Plast”) is to use separate heads column for that. In practice this means that we have another column that’s closed at the bottom and the bottom of that column goes down to mash in boiler. This gives enough heating for the column to let it operate normally. The product from ARC column goes to top of packing of this heads column. At the top of the column we have condenser as usual, and below the condenser we have a reservoir of 100-150ml where heads will be collected. The pure ethanol is taken out from the bottom of the column. Now the biggest problem with this type of approach is that at the start the column is fed with lots of heads and at the end there’s mostly pure ethanol. This means that we need to give the column some time to stabilize before we start taking product out. Two methods for this have been identified so far:

1. We let the ethanol pool at the bottom of the column and when adequate level is reached it starts to flow out. Finding a proper level requires experimenting but this has been tested to work

2. We collect all the reflux below the packing and feed it back to column via needle valve. When there’s enough reflux flowing the needle valve will restrict the flow and some pure ethanol will start to come out.

These methods are still experimented with and I’ll publish the results when I’ve found a method I’m happy with.
Perch
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Post by Perch »

possum wrote:Interesting.The bit about the funnel overflowing and not siphoning or pushing out the product take off tube... Are the tubes all drawn to a relative scale? Is the tube under the funnel larger diamater than the product take off tube ? Does the outlet tube make the bend above the funnel...

The tubes are drawn to relative scale, but I spec'd the "product takeoff tube" (PTT) as 1/8" tube. Riku's specs are closer to 1/4". The tube under the funnel is larger, at 3/8". From my understanding, the PTT outlet should on the same level as the top of smaller funnel.

Also did the design include a testamonial after it was run, or was it like: Boy this can't fail, the design will wash your dishes, clean your car and cure 15 deadly disseases ?

It seems legit and he does include a testimonial. There are no specific alcohol percentage numbers.
In my tests I was able to halve the amount of heads by using this version when compared to external pipe version. When tested with 160cm column and 60cm sensor pipe it produced extremely pure ethanol and ceased output before any tails did appear. With 100cm / 40cm combo the ethanol was very good but there was a very faint sweet taste from burned sugar.
From the pics and detailed writeup I feel that testing actually happened. I can't see a reason Riku would go to the trouble of doing such and extensive writeup if it had failed. It also seems that several others were involved in the initial design. Riku credits “Farbror Plast” with the initial concept?

Is this the "oh my gosh I cant belive I don't have to moniter the reflux rate or vapor temp still" ?

Garunteed to not let the tails come across ?

Ya, I'm not a big fan of the "Walk way method", but then some people are more about the product than enjoying the hobby.

This could be cool.

A glass collumn would need only one hole in the side.

Sorry for grillin' ya perch, This has me confused and excited, dangerous combo for me :lol:
Join the club :D
stoker
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Post by stoker »

Automatic Reflux Control
I can also have that when I adjust my valve.
with that design, you can't change your reflux, is you have build your still, and want to run it, and notice you have 85°, you can't change it anymore (unless you cut and solder again)
that makes a valve more usefull for me
-I have too much blood in my alcohol system-
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Post by Swag »

Perch wrote:Ya, I wondered the same thing. The still I modeled it after was in similar proportion. A 1.6 m (63") column and 60 cm (2ft) ARC. The difference being he only was using a 1.5" column. I designed to a 3". Thanks for the info on the cooling coil. What are you thoughts on using a 3 " column? I'm seriously thinking about starting with a 2" and getting a working ARC and then moving to a 3". I'd ideally like to try my hand at introducing vacuum into the system. I just need to take the baby steps first.
Have you priced 3” copper pipe and fittings yet? I would definitely start with a 2” column.
It also seems to me a critical point on how long the inner tube is. Your temperature will vary all the way up the column. Which part do you want to control the boiling in the center tube?
The control of this type of still would only be through heat I suppose. With the top open you would pretty much have to run full cooling or lose a lot of vapor. I think it would be good to know just how much control that would buy you.
This design may work just fine, but there are a lot of unknowns at this point. I wouldn’t recommend it for your first still. There are a lot of other time proven designs that are much more versatile than this unit.
However, I would be curious to see it work.
Perch
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Post by Perch »

stoker wrote:
Automatic Reflux Control
I can also have that when I adjust my valve.
with that design, you can't change your reflux, is you have build your still, and want to run it, and notice you have 85°, you can't change it anymore (unless you cut and solder again)
that makes a valve more usefull for me
The reflux can be adjusted, even put into full reflux. The airlock protruding from the side of the column is just a slip fit, sealed with Teflon tape. This allows for the level as related to the ARC funnel to be adjusted.
Image
Perch
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Post by Perch »

Swag wrote:Have you priced 3” copper pipe and fittings yet? I would definitely start with a 2” column.
Good call.
It also seems to me a critical point on how long the inner tube is. Your temperature will vary all the way up the column. Which part do you want to control the boiling in the center tube?
The control of this type of still would only be through heat I suppose. With the top open you would pretty much have to run full cooling or lose a lot of vapor. I think it would be good to know just how much control that would buy you.


Ya, I was planning on running full cooling to knock all the vapours back down. This is also the reason why I was going to run the numbers on the most optimal cooling coil configuration. I've got some theories I've been knocking around in my head over the last couple days about how the ARC actually works and the reason why the pipe is the length it is. I need to gather my thoughts on this and try some experiments. Thanks for the input!
This design may work just fine, but there are a lot of unknowns at this point. I wouldn’t recommend it for your first still. There are a lot of other time proven designs that are much more versatile than this unit.
However, I would be curious to see it work.
Ya, your probably right about that. The nice thing is that this design can easily be adapted to a valve reflux still configuration. All that is needed are:

2" T fitting
2" 90 elbow
2" cap
2 needle valves
A couple sections of 1/'4 tube

Image
nimrod77
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Can we see a cut away of the head on the last one

Post by nimrod77 »

Can we see a cut away of the last head design there? I'm not sure how it's meant to work?
Cheers
Perch
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Post by Perch »

nimrod77 wrote:Can we see a cut away of the last head design there? I'm not sure how it's meant to work?
Ask and you will receive..

Image

The cooling coils are an idea I played around with tonight for a couple hours. Ya I know, there's interference. Some dummy forgot to add the diameter of the pipe when he was calculating the helix's.

A better picture
Image
rkr
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Post by rkr »

Nice pictures, but I hope you'd link my book instead of copying sections of it.

This liquid based ARC is indeed a working system and several have been built by amateur distillers around the world, among them 3" and 4" versions. So yes, 3" will work quite well and is well suited for 2kW heating element. Latest addition to the system is automatic heads compression and removal section (no, not the bottle based one). I'll have it all and plethora of other things in the new version of my book which comes out whenever Mike Nixon finishes editing it.

Now about the sensor pipe and stuff. You need 6mm ID or larger pipe, otherwise the surface tension will prevent the ARC from operating properly. The same goes for product pipe, although to lesser extent. The principle of liquid shooting out inside the column is quite simple, the mass difference of liquid after the T in the sensor pipe. It will shoot out from refluxe plate before the pressure pulse has tim to shoot out from the product take off. For the length of internal sensorpipe I recommend 60cm nowadays. A 40cm pipe will work but at the very end of the run there's a risk of some propanol getting through.

- Riku
jbrew9999

Post by jbrew9999 »

Nice to see you here, Riku.

Your writtings on ARC are very interesting but I have lost my copy of the big one, can you post a link for it?
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Post by rkr »

http://distillers.tastylime.net/library ... 20Listings" onclick="window.open(this.href);return false;" rel="nofollow

Book is "Simple low cost stills".

- Riku
jbrew9999

Post by jbrew9999 »

Thanks. Is there a pdf I could use for offline reading?
Perch
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Post by Perch »

rkr wrote:Nice pictures, but I hope you'd link my book instead of copying sections of it.
I meant and still maintain no disrespect, but I did reference and link your article in my first post.
Perch wrote:That was until I happened across this site. The article entitled "Simple Low-cost Stills" contains a section (Page 22) detailing what the author calls an "Automatic Reflux Control"
I apologizes for not being able to find a direct link and for copying sections further in the post.
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For Riku

Post by nimrod77 »

Latest addition to the system is automatic heads compression and removal section (no, not the bottle based one). I'll have it all and plethora of other things in the new version of my book which comes out whenever Mike Nixon finishes editing it.


Riku,
The Auto heads seperator, how does that work? I'm actualy 80% finished building my still with ARC, and was going to use the bottle method for collecting the heads. Could you give me some insite/pictures of how your method without the bottle system?
PLEASE PLEASE??
stoker
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Post by stoker »

why would this design be better then a normal coil?
one valve will be enough, the one on top (and that tube) are/is unnecessary
-I have too much blood in my alcohol system-
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Please Continue...

Post by nimrod77 »

If anyone makes any more headway into building one of these ARC stills, please post it here so we can all see the end result along with a bit of info on how it went. I will post my results & still here as soon as it is finished. My friend & I are building four (4!) of stills at once with a modular ARC system built in using a Bokakob eliptical head to feed the ARC. The ARC can be removed and the setup used as a regular Reflux still. The whole coloum can be removed aswell and the head & boiler used as a pot still too.
Always good to have options :)
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Post by possum »

I love modular construction. :D
Hey guys!!! Watch this.... OUCH!
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Re: Please Continue...

Post by rkr »

nimrod77 wrote:If anyone makes any more headway into building one of these ARC stills, please post it here so we can all see the end result along with a bit of info on how it went. I will post my results & still here as soon as it is finished. My friend & I are building four (4!) of stills at once with a modular ARC system built in using a Bokakob eliptical head to feed the ARC. The ARC can be removed and the setup used as a regular Reflux still. The whole coloum can be removed aswell and the head & boiler used as a pot still too.
Always good to have options :)
Are you making internal or external sensorpipe versions? Getting internal sensorpipe to work with EL head might be a bit tough, but it's much better than the external version.

- Riku
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ARC

Post by nimrod77 »

Are you making internal or external sensorpipe versions? Getting internal sensorpipe to work with EL head might be a bit tough, but it's much better than the external version.

- Riku
It's an internal type. I'll post some pictures once it's finished. Hopefully by the end of the week depending if I get enough time to finish it :)
Cheers
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For Riku More Clarification

Post by nimrod77 »

Riku,
Another question for your ARC stuff... The squashed end of the sensor tube, what kind of leak rate should there be on that? My practice piece drains out fairly quickly. How fast is too fast ( or too slow ) ?
Also, the heads compression & removal system, when I add this will I need to un-brase/cut anything to impliment it later on?
Thanks mate,
Nimrod
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Post by nimrod77 »

Posting this from Riku... Hope he doesn't mind but I thought that other people may find this info useful....
I have leak rate of ~1 drop / second, if possible it's a good idea to test it with alcohol as the surface tension is different from water. It doesn't matter much if it's a bit faster as long as the liquid has time to start boiling when the temperature rises.

The head compression unit can easily be added if you use capillary joints for assembling the column. If you do the 160cm version now you'll have to cut the column a bit and add some joints but that's really quite easy to do if you haven't soldered the capillary joint(s). Just glue them with aquarium grade silicone and you have a tight connection that can be easily opened later.

- Riku
Cheers,
Nimrod
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My ARC Still (BIG POST)

Post by nimrod77 »

Here's a couple of in progress shots of my modular ARC setup. The still is nearly finished. Just waiting on some welding to be done on the coloum & the boiler.
I have used the Bokakob Eliptical head design and added the ard section below it.

The ARC section can be removed and the still used as a normal Reflux still. I also have the option to remove the coloum and use the head/boiler as a pot still (not show here).
I have also implimented the attached eprouvette as disscussed before. I have tried this with water and it seems to work. I have silver soldered everything so if it is no good I can remove it later. I plan on making a cover for the eprouvette to hold the alcometer upright & reduce evaporation. More to come once it's finished!! :)
Let me know what you think. I hope that it has clarified what I said about using the EL head & internal ARC Riku. Comments/questions welcome!
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Post by Mech Eng »

I am still struggling with the concept of this design. There is a column “sensor” surrounded by packing. The “sensor” column will take the same temperature variations as the packing up and down its length. Let’s assume the condensed liquid falls down to the bottom. It will start to boil because of the temperature at the bottom of the “sensor” column is greater then the boiling point of the liquid. Now – if the condensing rate at the coil is greater them the leak rate at the bottom, it will continue to fill with fluid.

This is the part that gets sketchy.

I believe that the “sensor” tube will fill to the top and boil over giving the “reflux” to the packing. After some time, the temperature at the top of the packing will drop from the boil over liquid and create the first “liquid reflux”. Once it is lowered – the boiling will slow and stop until the temperature starts to rise again at the top of the packing and the “sensor” column will fill with a higher grade distillate.

Now if the first fill of the “sensor” tube is say 90% then it boils over and levels off. It will only fill the tube with the next fractionating % then boil again. So the first bit out is not at 96%.

After awhile, it will produce at the max 96% but it must fist cycle to that state.

Is this the concept?
Keep it simple
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