"Reverse LM" idea

[rad14701]

There you go, Hookline... Much better... I was working on an off line reply, but not as elaborate as Huskers... I just came back to lookup the sight glass design that FREAK! posted... Would be nice to see the reflux, but not mandatory... Several of the other designs in this thread also miss the RLM definition...

[snuffy]

This is quite known design in my country.
...After setting by valve reflux remains constant. Product stream decreases during the process (less alcohol in keg and vapour).
It could be supplemented by electronic control of heating giving real ARC. The control algorithm is simple and output power is only a function of the temperature in keg. Because reflux is constant, power decreasing decreases product (it means reflux ratio RR increases).
E.g.
keg temp. [ºC] 78 93 96 97 98 99 100 102
power [%]_____75 70 65 63 59 62 65 65
Where full reflux is for 50% of power, 65% gives 4/1 RR (the same 65% gives 8/1 RR for low percentage of alcohol in keg). Additionally, at the end of process, head temperature is taken into account. If it increases above 0.05ºC power is reduced giving 100% reflux. After head temperature drop to its initial value 8/1 RR is forced by increased power. This last loop is repeated until in full reflux temperature can not drop....

Constant reflux flow rate, but it can be tuned by power management, manually or automatic.

The temperature sensor could be in the boiler, the head or in the middle of the column. I'd guess two sensors (one in the boiler to sense shutdown, another to sense azeotrope) and an adaptive control program would be most accurate.

I'm liking this the more I think about it. Went right past me at first.

[Husker]

Snuffy,

Im glad you have been watching this design idea also. You seem to be the one driving a lot of the column theory lately (riku also). Many people 'use' the techniques, but you are driving the new theory.

I am not sure this RLM is 'new', but I certainly see where this could be a pretty large improvement over traditional LM, along with, as you have stated, 'linking' into some form of computer control. This still seems like a very intriguing design (at least to me, heh).

H.

[rad14701]

I think there is also some good merit as far as use for LM is concerned as well... Considering how VM really isn't suited for small scale stills this might be a nice alternative for small scale design... After all, we can't all go as big as we might like... I'm actually entertaining the slant head idea because it would buy me a few extra inches of column for a stove top unit... It would still place the needle valve quite high up, but if you don't need to fiddle with it as much then it's not as big of an issue as it might otherwise be...

[yonch]

cemik: thanks for posting the design. Seems like I re-invented the concept, but I'm glad you engaged the discussion..
husker: I couldn't have explained it better (and didn't)

I have built an RLM still, all except for the boiler. Kegs are hard to find around here, although they do seem like the best option for a boiler.. Once I finish it, I'll post the results.. If anyone else has experience with these (cemik or others) it would be nice to receive more information about operating these babies, if they do shut off when there is no more alcohol or if they require an extra adjustment to get the last part of the hearts, and similar information.


yonch

[Aces High]

All those people who built Nixon stone offset head LM units with a valve for output and a valve for the reflux return tube and people were always saying they dont need the valve on the reflux return.
They could actually run in reverse LM by simply running the outlet fully opened then setting the flow of the reflux return. Does that make sense?

There is often wisdom in older things, that us young-uns just dont see

[minime]

All those people who built Nixon stone offset head LM units with a valve for output and a valve for the reflux return tube and people were always saying they dont need the valve on the reflux return.
They could actually run in reverse LM by simply running the outlet fully opened then setting the flow of the reflux return. Does that make sense?

There is often wisdom in older things, that us young-uns just dont see

The design shows both outlets off the bottom. Minor mods would make it feasible however. The main problem I've seen with the design is the large reservoir of liquid. The smaller the pool the quicker corrections can take place.

[HookLine]

There is often wisdom in older things, that us young-uns just dont see

Sure is.

[snuffy]

...The main problem I've seen with the design is the large reservoir of liquid. The smaller the pool the quicker corrections can take place.

that's why I made a larger reservoir -- to see how much that matters. I'm thinking that it might actually have benefits in making the cuts sharper like the heads reservoir in Riku's designs. At the boundaries between heads, hearts and tails it could allow high reflux to concentrate the transition, then you could dump the heads all at once and move into the hearts where things should stay pretty stable. When the head temp rises at the onset of tails, cycling to 100% reflux would compress the last of the hearts and make the transition to tails sharper. At least that is what I hope it will do when I get around to playing with it. Gotta test it to be sure.

If it works, it would be a cinch with a solenoid valve and controller. There are laboratory stills with solenoid valves where you set the reflux rate by varying the duty cycle pulse width going to the valve.

I've played with the CM head by putting it into 100% reflux and then surging the power to blow the top of the column through quickly. It works better at the transition to tails than at heads. CM seems to spread the heads out a bit. But I got several clear auto-shutdown at tails by controlling the power in small increments. The auto shutdown at heads kept acting like more ethyl acetate was forming in the column. I didn't test the pH, so it might have been doing that.

This seems to be how the cemik1's design uses the cycling: 100% reflux to concentrate at the top of the column and then move that off until the column loses dynamic equilibrium and then start the cycle again at 100% reflux. So a larger reservoir might assist this.

[minime]

The auto shutdown at heads kept acting like more ethyl acetate was forming in the column. I didn't test the pH, so it might have been doing that.

I'm pretty certain that's exactly what's happening. Even though the bulk is gone there's always a bit more forming. Riku and Manu like long risers above the takeoff to improve the collection of hearts. I believe Manu had his distillate tested and it came back positive for trace amounts of ethyl acetate prompting him to address it with the riser. The cleaner the booze the more obvious it's presence from my experience. That's why I like running hard and just achieving 95%. You can't tell it's there

[cemik1]

...power management, manually or automatic.
The temperature sensor could be in the boiler, the head or in the middle of the column

To get ARC power management must be automatic but manual is also possible - user is resposible for analise data and set the level. In RLM systems: lower power - higher RR. It is quite opposite in "clasic" LM where to get higher RR power must be increased (there is often power limit) what could lead to column flooding or mash burning. Sumarising - RLM allows to build real ARC without flooding, burning and power limit problems.
One temperature sensor is in the boiler or in column inlet. The second measures head temperature.
In the main process they are resposible for:
1st - (lower order) power reduction in function of temperature to increase RR
2nd - (higher order) stabilisation start (full power for preheating), periodic mode in the process end (increase of head teperature, 100% reflux set, temperature decrease, 8/1 RR set ...), switch power off when head temperature remains to high.
Power/temperature table must be slightly trimmed to particular design. Because rectification is relatively slow process a PC can easy control it.

[cemik1]

cemik1, did this design originate in the early '80s during the final phase of the Russian occupation?

It was published later, I think 2-3 years ago, and from inventor name it is called:
AAbratek (slanted clasic LM):

or improoved AAbratek (slanted RLM):

[minime]

To get ARC power management must be automatic but manual is also possible - user is resposible for analise data and set the level. In RLM systems: lower power - higher RR. It is quite opposite in "clasic" LM where to get higher RR power must be increased (there is often power limit) what could lead to column flooding or mash burning. Sumarising - RLM allows to build real ARC without flooding, burning and power limit problems.
One temperature sensor is in the boiler or in column inlet. The second measures head temperature.
In the main process they are resposible for:
1st - (lower order) power reduction in function of temperature to increase RR
2nd - (higher order) stabilisation start (full power for preheating), periodic mode in the process end (increase of head teperature, 100% reflux set, temperature decrease, 8/1 RR set ...), switch power off when head temperature remains to high.
Power/temperature table must be slightly trimmed to particular design. Because rectification is relatively slow process a PC can easy control it.

Very intriguing design cemik1, just want to thank you for bringing it to our attention.

[muckanic]

I'm sure this has all been thrashed out before, but power management bothers me. It is a practically easy variable to control, but whether it is the most appropriate variable is another matter entirely. It clobbers any double-boiler based approach, for starters (due to thermal inertia). Putting a controller on the valve in a conventional LM system makes more sense to me personally, difficult though that may be. And of course the whole point with RLM is that valve control isn't really required, except possibly at a couple of transition points where manual intervention would most likely be just as effective. I guess it depends on your tastes for complete, hands-off automation!

[HookLine]

Thanks for the pics, cemik1.

I Googled AAbratek, and one of the things I found was a Polish stilling forum (Bimber), with this page full of still pics:

http://bimber.ovh.org/galeria.html" onclick="window.open(this.href);return false;" rel="nofollow

Some good stuff in there.

[cemik1]

Detailed AAbratek description can be found at http://www.bimber.info/forum/viewtopic.php?t=2103 (in Polish but contains plenty of figures and photos).
It is much easier and cheaper to control boiler power in RLM than reflux in LM. It is a clue of invention.

[Aces High]

funny hookline.. i did exactly the same thing and found still porn european style. Its funny to see these peasant looking houses, with the most professionally made stainless stills out front. Check out Mr Maag and you'll understand http://bimber.ovh.org/gal_mr_maag.html

[muckanic]

Pardon me if I am being dense here, but as far as I can tell RLM will not permit 100% reflux in the design as presented. IOW, with the valve wide open, there will still be some product take-off. That could be solved with a second valve on the product line.

[HookLine]

Because of the slopes on the reflux and product take-off lines (mostly on the take-off line, also see my drawing here), if the reflux valve is wide open the condensate will prefer to run back down the reflux line and into the column. When the reflux valve is restricted and does not let all the condensate through, the overflow backs up and goes down the take-off line. So you can get 100% reflux with this design just by fully opening the reflux valve.

[guerrila distilla]

would i be right in saying you could use a gate valve rather than a needle valve for this reverse lm type setup? a needle valve (unless it was a large, expensive one), wouldn't be able to handle the flow of reflux.

i'm quite interested in the theory that you could have the advantages of lm, without the need for the adjustments you would normally have to do. i do like the sound of this idea, but could you guys clear a few things up for me.

am i getting it right here, the idea is to make an lm still that will require less fiddling towards the end of the run to maintain the same reflux ratio?
towards the end of the run would it be the flow rate or the purity that will drop?
does it hold any advantages over a VM still, which looks a lot less fiddly to build?
finally, has anybody actually tried and tested this type of still?

i am talking about a manual setup here, i'm not too keen on automating a still as that seems like taking half the fun out of the hobby. the fact is that regardless of control by temperature changes, tails still find their way in there somehow. just look at commercial spirits, i'm sure many of us make a much cleaner product than many commercial distilleries manage just by using our noses.

[yonch]

would i be right in saying you could use a gate valve rather than a needle valve for this reverse lm type setup? a needle valve (unless it was a large, expensive one), wouldn't be able to handle the flow of reflux.

It seems like you can get by with a very small valve. I haven't tested mine yet, but this is how I chose the model.

I calculated it like this: by playing with the calculators on tony's site, for a 2000w heating element (which is a lot), there will be around 2.4 liters an hour going through the top of the column. Some of it is collected, and some of it is refluxed back in. Usually, valves are specified in Cv, which is a measure of how much goes through the valve for any given pressure. Usually it is in US gallons per minute (GPM) per 1 PSI of pressure. The pressure here is the pressure of distillate pushing on top of the valve - it is not pressure of vapor. Apparently, how I calculated it, 10 cm high of ethanol is 0.1 PSI. We said we need 2.4 liter per hour, so even if we calculate for one gallon per hour, it's still 1/60 gallon per minute. So at most, I'll need at most 1/6 Cv (which is 1/60 divided by 0.1) for full reflux. So you don't need a big valve, I got a 1/4 inch one, Hoke's 3712H4Y. Then, there should be a 10cm high resevoir built above the valve, which should be reasonable. As I said, I haven't tested it yet, so YMMV

You can see the flow curve on page 28 of http://www.hoke.com/products/needle/793 ... -03_lo.pdf" onclick="window.open(this.href);return false;" rel="nofollow
It is the flow curve for 3700 series with regulating stem tip.

am i getting it right here, the idea is to make an lm still that will require less fiddling towards the end of the run to maintain the same reflux ratio?
towards the end of the run would it be the flow rate or the purity that will drop?
does it hold any advantages over a VM still, which looks a lot less fiddly to build?

VM should maintain the same reflux ratio throughout the run. LM actually increases the reflux ratio when the run is advancing, which might be better for purity than VM. The reason for the increased RR is that you put in the same amount of heat (for example you have a 2000W element), but there is more water in the mixture that leaves the water. Since water has much higher energy of vaporization per ml, there are less ml of liquid being condensed in the condenser. Since RLM makes the same amount of reflux (in ml) flow back to the column, the amount of distillate collected will drop, and the RR will rise.

[minime]

does it hold any advantages over a VM still, which looks a lot less fiddly to build?

One distinct advantage is it's possible to collect all the condensate as in pot still mode. That's the main drawback of a VM column. It is also possible to get away with just one condenser although the product would be pretty warm.
I 'm anxious for somebody to report on a build also. Somebody better do it or I'm going to have to. Hookline has a nice little offset design drawing that I really liked. Maybe he'll post it.

[snuffy]

These are good. It only takes a trickle.

https://www.surpluscenter.com/item.asp? ... =hydraulic" onclick="window.open(this.href);return false;" rel="nofollow

[rad14701]

Good legitimate questions, guerrila distilla...

As for reflux valve choice, needle valve usually have a finer and more linear adjustment range than a ball valve or gate valve... Even a cheap needle valve can handle the volume, it's just a matter of precise adjustment that can be lacking - but still usually better than other valve types...

The advantage of RLM is that you set the reflux rate and then only collect what doesn't reflux... So, for example, when your reflux is adjusted to hold you at 78C without wavering you might start out with 4 drips per second take off rate... As the run progresses the reflux remains the same but the take of rate slows to 3 drip per second... A little later and the rate is down to 2 drips per second... Now, at some point the reflux rate won't be enough to hold that 78C temperature without adjustment... If you do try to increase the reflux then your take off could drop to almost nothing... Note that the example drip rates are low, like for a small scale still, and most units perform better than this...

So, essentially, you can use reflux to maintain your chosen "purity" and the still decides what you get for take off rate - the opposite of how standard LM works... You could just as easily adjust your reflux to maintain a reflux temperature of something like 174.5F (79C), or about 88% ABV instead of 172.5 (78C) at 95% ABV... You'll still need to fiddle around a bit during the run, but not as much as with LM...

And what the other guys said while I was typing - and watching the news...

[HookLine]

Hookline has a nice little offset design drawing that I really liked. Maybe he'll post it.

Ask and ye shall receive.

This design variation might allow a small amount of condensate coming off the reflux coil to drip directly down the take-off line. There are ways to prevent this happening. Or maybe an easier solution is to use this variation I put up earlier on this thread, with the uphill bump in the take-off branch.

[yonch]

Hookline, maybe a vapor-lock in the product line would be good. Without a vapor-lock you might get an unwanted VM-like effect from the product condenser in addition to the RLM product.

I mean that the vapor coming from the column will condense partly on the main condenser and partly on the product condenser, and you will get a mixture of RLM and VM: most of the product will condense on the main cd'or and will go through RLM, but some will not. I think this is unwanted because it hurts the "purity stability" you get from RLM (the RR in a mixed system will increase as the run progresses, but not by as much as a "pure" RLM)

edit: The uphill bump in the design Hookline mentioned could be a vapor-lock, but the slope on the bump would have to be higher, to disallow vapor escaping through there...

[HookLine]

yonch

Not sure what you mean by the product condenser. There is only one condenser on these two designs, that condenses both reflux and product.

But I see now that as I have drawn it the second design would simply allow vapour to escape out of the take-off line. And the first design (with the bump, see below) would have variable liquid level, so it would also allow vapour to escape under certain conditions (medium-high reflux ratio, and 100% reflux). So I agree that a vapour lock on the take-off line is necessary for both these designs to operate properly (and safely).

[HookLine]

Just been looking over all the RLM designs on this thread, and it seems to me that they all need a vapour lock on the output line to prevent vapour escaping that way, and that the vapour lock would need to be primed at the start of the run (plain water would be fine).

[muckanic]

It seems to me that both the standard LM and RLM designs run into problems at reflux extremes, at low reflux and high reflux rates, respectively. A bend in either the return line or take-off line, respectively, could very well be all that is needed to solve the problem. An unbent return line in a LM design poses a particularly nasty problem at low reflux rates: the return line could actually start functioning as a gas vent line, which could in turn muck up the reflux. It wouldn't be difficult to insert a section of glass tubing in a LM return line (no need for stainless housings or the like). It's a shame no-one ever does that so that any bubbling could be observed. At that point, you might wish you had a valve to counteract the problem. OTOH, it's debatable whether a return line is even necessary with LM, although it clearly is with RLM (unless some way of varying the reservoir size dynamically could be worked out)!

[guerrila distilla]

i don't know if i got it right, but this is my interpretation of the idea.

i hope i'm in the right ballpark here, i added a valve on the product takeoff, which is only to be used when the still is heating up and gaining equilibrium. once equilibrium is reached, the takeoff primer valve can be opened fully and will not be used during the run. it's pretty much to prevent vapour escaping whilst the column is at 100% reflux.

during the equilibrium period the reflux valve will be fully open, to be adjusted once equilibrium is reached. you will have to close the valve for a few minutes after equilibrium is reached to fill the product air lock.i have used an inline idea in which the product tube is set higher in the reflux collection area than the product tube. both the reflux and product tubes have liquid locks to prevent vapour travelling through them. the idea is that as the reflux valve is closed the collector fills until it reaches the product tube (which is air locked)

basically this is my theory on using the still :-

1, close the product primer valve, fully open the reflux valve and turn on the still.
2, when equilibrium is achieved, close the reflux valve for 1 minute to prime the product air lock, open the primer valve fully.
3, begin the run by adjusting the reflux valve very slowly.

i hope i'm on the right lines here, let me know guys, thx