Re-boiler Within the Boiler?

[DAD300]

I think you're/we're missing the neatest part of the OP design.

There would be greater efficiency (Heat used) with the reboiler inside the primary boiler than with a bubble ball or an exterior thumper.

Another possible design strategy would be the use of the reboiler to introduce same flavors. How about we charge the reboiler with some grain or dunder?

[DAD300]

Edwin Croissant...your drawing is just a few steps away from a true laboratory fractionating column where there are multiple takeoffs, for different products inside a totally equalized column.

[googe]

I think you're/we're missing the neatest part of the OP design.

There would be greater efficiency (Heat used) with the reboiler inside the primary boiler than with a bubble ball or an exterior thumper.

Another possible design strategy would be the use of the reboiler to introduce same flavors. How about we charge the reboiler with some grain or dunder?

+5

[Lester]

Hello Edwin,

This run had no fusel oils in the boiler charge. I loaded it with water + 95% ABV alcohol. (Comment written on the hard data I posted earlier).

Now that you mentioned fusel oils, the shallow reboiler seems to have been a wise choice after all. The oils float to the top of the liquid and are the first ones to get discarded by the reboiler when it overflows. As such the oils will have minimal effect on the boiling point of the content's of the reboiler'. The liquid level marks on the pot used in the first trial indicate that the oils indeed float to the top of the reflux during distillation. Also, the oils will only come up towards the end of the run, not at the start as was indicated on the graph.

[Lester]

There would be greater efficiency (Heat used) with the reboiler inside the primary boiler than with a bubble ball or an exterior thumper.

Hello Dad,

Indeed I was after efficiency with this modification. Having the reboiler inside the boiler negates the need for insulation on an external thumper.

Another possible design strategy would be the use of the reboiler to introduce same flavors. How about we charge the reboiler with some grain or dunder?

I would love to try this but I'm a complete idiot when it comes to whiskey or rum.

[Lester]

Try to take a sample and measure the density to be sure.

Edwin,

I thought I might add:

My boiler's pressure is something like 5mm of water, not much. I actually measured this a month ago.

Since the boiler & reboiler both enjoy the same pressure, I can use the Ebulliometer method in determining RELATIVE alcohol concentrations. I am convinced that my methods are accurate enough for its intended purpose: To show if there's any benefit in having a reboiler inside the boiler.

I did ask for suggestions on how to evaluate this reboiler but got none so I did it this way.

Please don't get me wrong. I value your inputs and I think they go a long way in clarifying some points which I have not been so keen in explaining. Thank you!

[Edwin Croissant]

Hi LTWCS, it looks like Lester made himself a poor man's bubble ball

DAD300, I know, and I think that a fusel oil take off is something every self-respecting column should have in the future I found a thread on a Russian forum from somebody who is now trying to automate the takeoff quantity of his fusel oil take off.

Lester, you are right, I was not thinking hard enough . I later thought that eliminating the influence of fusel oil can also be canceled out by doing a run with diluted clean ethanol and I overlooked the fact that you were already doing that. And yes, you are measuring the temperature differential at equal pressure. Thinking a little bit harder: you can have a small leak in your condenser (very, very unlikely but mentioned nevertheless) and it is also possible that trying to measure a boiling point of a liquid in a kind of a furnace (the surrounding vapor has the temperature of the boiler) is effecting the temperature sensor. I had some limited experience with thermocouples 40 years ago and I recall that it is possible to measure a temperature difference by putting the hot junction in the boiler and the cold junction in the re-boiler. You can even combine multiple thermocouple junctions to get a higher output voltage. Like you did with your diodes in your temperature sensors.

The liquid level marks on the pot used in the first trial seems to indicate that the fusel oil concentration reach the level that the fusel oil is de-mixed, if that is the case you can better have this in your reboiler then in your column. Please tell me what do you mean with: “Also, the oils will only come up towards the end of the run, not at the start as was indicated on the graph.” ?

Regards,

Edwin

[DAD300]

Edwin,

I don't think we need dif take off points. It has been tried and failed.

Science provides that the elements come off a distillation in order by dif temps...I say we should learn to live with the natural order.

I only equalize the column to get the vapor to the top...then when I start my take off, nature separates the elements for me...the fores come off first, then...

At the hobby level we have neither the need or the capability of separating them in the column. Especially when it is sooooo easy outside the column after collection.

I think most over equalize and end up smearing everything together, over complicating an easy scientific process.

Some of the greats in the hobby have gone from 45-60 minute equalization periods to ten minutes. And mine is shorter than that. Once vapor has reached the top, I start take off. Because science says, "The bad stuff comes off first."

[Lester]

it looks like Lester made himself a poor man's bubble ball

Well, not exactly. There's no scrubbing action that's happening here unlike when vapors are bubbled through a liquid. The effect may be the same (probably not) but the means of getting there is different.

But then again, what stops us from putting perforations or bubble caps on this reboiler? It's a lot more difficult to make but can be done. Although contamination of the spent reflux by the wash seems to be a major problem.

Please tell me what do you mean with: “Also, the oils will only come up towards the end of the run, not at the start as was indicated on the graph.” ?

I don't want to spoil your fun. When you run your still for the first time I'm sure you will understand what I mean. You're not making a continuous still are you?

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If somebody else will build this reboiler I suggest the use of thin copper material. Faster heat transfer this way.

[Lester]

...I say we should learn to live with the natural order.

+1

[Odin]

Fusel oil concentration in your re-boiler is higher then in your boiler and fusel oil raises the boiling temperature of a water ethanol mixture. Try to take a sample and measure the density to be sure.

Regards,

Edwin

Love this tread. Great out of the box thinking, Lester!!! My compliments! I think Edwin has a point: you will create, especially during the second part of the run, a situation where you continuously re-introduce fusils in ever more concentrated amounts to your boiler, creating smearing.

A take-off would help you out.

Odin.

[Lester]

Love this tread. Great out of the box thinking, Lester!!! My compliments!

Thank you!

I think Edwin has a point: you will create, especially during the second part of the run, a situation where you continuously re-introduce fusils in ever more concentrated amounts to your boiler, creating smearing.

A take-off would help you out.

Sorry but I disagree with this. The fusel oils float on top of the distillate and they are the first ones to get discarded when the reboiler overflows. And the oils do indeed float as evidenced by the oily liquid level marks left on the inside of the reboiler during the initial trial (the first design, the tall reboiler, it doesn't overflow).

This was among the reasons why I went for rev. 1, a shallow reboiler instead of a tall one, so the fusel oils can overflow back into the boiler.

The other reason is because I wanted to displace the water in the reboiler quickly so I end up with more alcohol. It takes a lot longer for this to happen if I have so much water in there.

[Odin]

The fusils only float on top only when % in reboiler is 17 or less.

[zombie911]

How do you all feel about converting the re-boiler into a massive bubble plate sealed to the bottom of the lid (with overflows of course). Perhaps a dozen 1" bubble caps, and a few overflow ports.

Something like a converted copper pie plate?

[zombie911]

Forgot to mention... Love the thread Lester!

[Lester]

I see it working like a regular bubble plate, Zombie. But with less heat loss.

I would put several bolts & nuts all around plus a gasket for sealing it to the lid of the boiler. Not sure how you're going to empty it though, if you ever need to, without dismantling. Perhaps a drain can be included.

Good luck and do let us know how it works out!

[Lester]

I think that the vapor from the boiler cannot reboil a condensate (that what is coming out of the bottom end of the column) lower in ABV then the ABV of the boiler content itself.

Hello Edwin,

If you take a look at the graph on the previous page you will notice 2 things:
1. The ABV in the reboiler is HIGHER than the boiler content ABV.
2. The ABV depletes from the reboiler's content ahead of the boiler's content. It may not be boiling but the alcohol gets out of there anyway.

(I've placed a few drops of 95% ABV on top of my boiler lid while distilling and I saw that it doesn't boil also, and yet it evaporates quite quickly. Yes it's a fire hazard.)

[zombie911]

I see it working like a regular bubble plate, Zombie. But with less heat loss.

I would put several bolts & nuts all around plus a gasket for sealing it to the lid of the boiler. Not sure how you're going to empty it though, if you ever need to, without dismantling. Perhaps a drain can be included.

Good luck and do let us know how it works out!

You are my "Mr. Rodgers" You inspired me.
Never thought about the drain. Thank You!

[Prairiepiss]

I think that the vapor from the boiler cannot reboil a condensate (that what is coming out of the bottom end of the column) lower in ABV then the ABV of the boiler content itself.

Hello Edwin,

If you take a look at the graph on the previous page you will notice 2 things:
1. The ABV in the reboiler is HIGHER than the boiler content ABV.
2. The ABV depletes from the reboiler's content ahead of the boiler's content. It may not be boiling but the alcohol gets out of there anyway.

(I've placed a few drops of 95% ABV on top of my boiler lid while distilling and I saw that it doesn't boil also, and yet it evaporates quite quickly. Yes it's a fire hazard.)

I have physically seen liquids in my bubble plate boil from the vapor heating the plate itself. More then once. The temps of the vapors coming off the boiler. Will be higher then the boiling point of a higher abv liquid on a bubble plate above it. So yes it is possible.