Off-Flavors in Distillate

[HDNB]

a picture is worth a thousand words. offset with a reflux condensor is quite a bit different than what i had in my mind from the first description of 2" reduced to a 3/8 worm....

on the subject of cleaning - what do the scrubbies and reflux coil look like? nice and clean?

[still_stirrin]

...Can you point me to some literature as to why this type of reflux column does not work?

Nothing wrong with a Nixon-Stone (LM) design, if properly built. See my other response to better understand what I mean by this reply.

...So I like this, because you are telling me a solution may be to lengthen the column. Which wouldn't be too hard to do (unsoldering the current column and putting a longer piece of 2" pipe in it's place). So I guess my question stemmed from this little sub-topic is... How tall?

Typically, the (potential) reflux reboilings says that the height should be 20 diameters of (packed) column to reach azeotropic purity. Of course, the type of packing will affect this process and how efficiently the condense/reboil cycles occur.

...It was my understanding (from what I read on the parent site and looking at the charts and stuff)... that the column height is directly proportional to how "pure" the product will come out when collecting (in one distillation)... and I read nothing about how extra length will help with smearing. Which honestly, the word smearing is pretty new to me after browsing these forums for a year or so. So... explaining why a 2' column is not sufficient enough to eliminate smearing vs. a 3' column eliminates it, would be great.

The diameter of the column affects how “how fast” you can produce the vapors. Actually, you want the vapor speed to be less than 20 feet/second to minimize pressure drop through acceleration of the vapors. So, heat input is consequently affected by the diameter of the column....that is, how fast the boil will produce vapors and that vapor will flow through the column (and reflux).

But the height of the column affect the number of reboil cycles the rising vapors undergo. And keep in mind that the number of reboil cycles affects the separation of the constituents as you “stack the column”. Constituents with a lower boiling point will accumulate in the top while the constituents with a higher boiling point (water, for example) will concentrate at the bottom of the column, or even return to the boiler.

So, height does matter for the purity. And the opposite of purity will be smearing, when parts of the heads and tails will be distributed throughout the run (to a varying degree). I refer you to Kiwistiller's Guide to Cuts to better understand this. It is certainly more evident when using a potstill than a reflux column. But a reflux column that is too short will behave more like a potstill even though you do have some reflux.

Happy reading.
ss

[rparody]

Here are the pictures "attached"

[rparody]

One more thought, since you said you like to build instead of buy...did you do the mandatory cleaning protocol with your new build? If not, that could be the source of your crappy tasting product.
ss

Firstly, I ran a wire brush through all of the copper. And soaked all of them in vinegar just to get the crud out. Then after I soldered it, I gave the column a run of half water / half white distilled vinegar for about an hour. And then after that, I ran a run with just water to steam it out.

I am unsure of what the mandatory cleaning protocol is... but I would love to see it

[rparody]

a picture is worth a thousand words. offset with a reflux condensor is quite a bit different than what i had in my mind from the first description of 2" reduced to a 3/8 worm....

on the subject of cleaning - what do the scrubbies and reflux coil look like? nice and clean?

The scrubbies were soaked in hot water for a few mintues and then rinsed in tap water for a minute or so.

The reflux coil has only had water ran through it, and no cleaning was done to the outside (bought the stuff from home depot in a rolled coil, figured it didnt need any cleaning)

[rparody]

...Can you point me to some literature as to why this type of reflux column does not work?

Nothing wrong with a Nixon-Stone (LM) design, if properly built. See my other response to better understand what I mean by this reply.

...So I like this, because you are telling me a solution may be to lengthen the column. Which wouldn't be too hard to do (unsoldering the current column and putting a longer piece of 2" pipe in it's place). So I guess my question stemmed from this little sub-topic is... How tall?

Typically, the (potential) reflux reboilings says that the height should be 20 diameters of (packed) column to reach azeotropic purity. Of course, the type of packing will affect this process and how efficiently the condense/reboil cycles occur.

...It was my understanding (from what I read on the parent site and looking at the charts and stuff)... that the column height is directly proportional to how "pure" the product will come out when collecting (in one distillation)... and I read nothing about how extra length will help with smearing. Which honestly, the word smearing is pretty new to me after browsing these forums for a year or so. So... explaining why a 2' column is not sufficient enough to eliminate smearing vs. a 3' column eliminates it, would be great.

The diameter of the column affects how “how fast” you can produce the vapors. Actually, you want the vapor speed to be less than 20 feet/second to minimize pressure drop through acceleration of the vapors. So, heat input is consequently affected by the diameter of the column....that is, how fast the boil will produce vapors and that vapor will flow through the column (and reflux).

But the height of the column affect the number of reboil cycles the rising vapors undergo. And keep in mind that the number of reboil cycles affects the separation of the constituents as you “stack the column”. Constituents with a lower boiling point will accumulate in the top while the constituents with a higher boiling point (water, for example) will concentrate at the bottom of the column, or even return to the boiler.

So, height does matter for the purity. And the opposite of purity will be smearing, when parts of the heads and tails will be distributed throughout the run (to a varying degree). I refer you to Kiwistiller's Guide to Cuts to better understand this. It is certainly more evident when using a potstill than a reflux column. But a reflux column that is too short will behave more like a potstill even though you do have some reflux.

Happy reading.
ss

Thank you Stirrin... I am going to look into the modifications needed to turn this Offset LM into a more efficient one. And when you said 20 diameters, I assume you mean since this is a 2" diameter column, the place where the reflux should start going back into the column should be 40" from the lid? Is that correct?

[still_stirrin]

...I am unsure of what the mandatory cleaning protocol is... but I would love to see it

Well, it’s obvious you haven’t read enough yet.

Cleaning protocol (after every new build or modification):
—> 1st run is steam, and give it a thorough steaming for an hour, or so.
—> next, a 50/50 mix of water and vinegar, also with a good steaming, for at least 30 to 45 minutes, or more.
—> finally, a sacrificial alcohol run, collecting and disposing of the alcohol. This run should be a couple of hours, preferably longer.

Incidently, a mechanical cleaning is adviseable but doesn’t eliminate the need for any of the described cleaning runs.

So, your source of bad taste likely is from the flux from your build because often times the flux isn’t adequately cleaned until the sacrificial alcohol run. It is not healthy to drink the sacrificial alcohol, so you should dump yours.
ss

[still_stirrin]

...when you said 20 diameters, I assume you mean since this is a 2" diameter column, the place where the reflux should start going back into the column should be 40" from the lid? Is that correct?

Yes, exactly. That should get you to azeotropic alcohol, at least the ability to separate the fractions capable to isolate azeotropic alcohol.

I still recommend collecting into at least 20-30 containers during a run so you’ll be able to cut the heads and the tails after the run.

You should be able to reduce the reflux ratio by increasing the liquid takeoff, as that will return less of the produced condensate to the column.
ss

[rparody]

Woooo baby, that column is going to be loooooonnnngggg. I am going to have to adjust shelving and drop the boiler much lower in order to accommodate for such a tall head. But all of this stuff is very doable as modifications to the current still.

[StillerBoy]

On column length, you can make it 36" long on a 2", if you are using the proper column packing which will assist in giving you 95%.. the only different between a 36" and 40" will be the rate of your take off.. lava rocks are better than ss srubbies in improving rate off..

On your usage of srubbies, are you sure that they are stainless steel.. most so call ss srubbies are galvanized, not ss.. check them out with a magnet.. if the magnet is attracted to it, they are galvanized not ss.. ss srubbies will not be attracted to the magnet..

And by the way, thank you for posting pictures of your setup, and reposting them here on HD..

Mars

[rparody]

On column length, you can make it 36" long on a 2", if you are using the proper column packing which will assist in giving you 95%.. the only different between a 36" and 40" will be the rate of your take off.. lava rocks are better than ss srubbies in improving rate off..

On your usage of srubbies, are you sure that they are stainless steel.. most so call ss srubbies are galvanized, not ss.. check them out with a magnet.. if the magnet is attracted to it, they are galvanized not ss.. ss srubbies will not be attracted to the magnet..

And by the way, thank you for posting pictures of your setup, and reposting them here on HD..

Mars

Sure thing! Yeah I was thinking about ultimately just switching over to Copper scrubbies (im sure they are more expensive), but that will be ok for the amount of times I will use them. Just want to get this setup into a final state and make some good quality neutral.

Also I am not sure if I stated. But I am going to remove the coil condenser on this guy and make a shotgun condenser using 8-9 3/8" tubes in a 2" jacket with 1/2" inlet and outlet ports for water movement. I have read these shotgun condensers really really cool way better than the coils. Which my understanding is... the stripping run will go faster

[still_stirrin]

...I am going to...make a shotgun condenser using 8-9 3/8" tubes in a 2" jacket with 1/2" inlet and outlet ports for water movement.

It may be tight to get eight or nine 3/8" vapor tubes inside a 2" jacket. But if you can, that will be a good thing. Make sure you put at least 3 baffles between the two end baffles so that you get some swirling action in the water flow as it flows through the jacket. Also, I would suggest making the shotgun (at least the tube baffle section) 18 to 20 inches long. That way, you'll have plenty of cooling capacity for stripping as well as good knock down for your spirit run.

Are you planning this shotgun to be used as the reflux condenser on top of the offset? If so, it's going to make your tower taller too. But, it will be very effective at reflux knockdown (which is also your product condenser since the product is liquid out of the product outlet).
ss

[rparody]

Are you planning this shotgun to be used as the reflux condenser on top of the offset? If so, it's going to make your tower taller too. But, it will be very effective at reflux knockdown (which is also your product condenser since the product is liquid out of the product outlet).
ss

Yes sir. I was gonna make it 2' tall. So we were thinking alike on that. But the baffle idea is something I did not think about and something that I like! That sounds like a really good idea to have something swirling the hot and cold water mixture around. Nice call Stirrin!

[rparody]

Hey Stirrin. To stop the still from being too ridiculously tall, do you think I could back the column length down to 36" like recommended by StillerBoy suggests? With the copper scrubbies packed up in there, do you think that would be ok?

[still_stirrin]

...To stop the still from being too ridiculously tall, do you think I could back the column length down to 36" like recommended by StillerBoy suggests? With the copper scrubbies packed up in there, do you think that would be ok?

It will work, sure.

Twenty times column diameter is a "seat of the pants" for enough theoretical plates to reach azeotropic separation in a tower that is producing at a nominal vapor flow rate. Shorter will work as long as you keep the reflux ratio a little higher (which you can adjust by reducing the liquid takeoff rate).

And as StillerBoy pointed out, the type and materials of the packing will affect the efficiency of the reflux cycles such that shorter columns can be proven effective, especially as you learn the "sweet spot" of operation for your setup.
ss

[rparody]

...To stop the still from being too ridiculously tall, do you think I could back the column length down to 36" like recommended by StillerBoy suggests? With the copper scrubbies packed up in there, do you think that would be ok?

It will work, sure.

Twenty times column diameter is a "seat of the pants" for enough theoretical plates to reach azeotropic separation in a tower that is producing at a nominal vapor flow rate. Shorter will work as long as you keep the reflux ratio a little higher (which you can adjust by reducing the liquid takeoff rate).

And as StillerBoy pointed out, the type and materials of the packing will affect the efficiency of the reflux cycles such that shorter columns can be proven effective, especially as you learn the "sweet spot" of operation for your setup.
ss

So maybe we have gotten off of topic here. But does this adjust and help with "Smearing" as well? Because that ultimately is what might have been problem that I am having. The nasty awful taste is bleeding into everything. And I was running the spirit run low (1400W) with easily a 2:1 reflux ratio. So I am just curious if this ultimately will help solve that problem? Or did I just not do a sacrificial run, and the nasty taste out of the alcohol is from all the nasty flux and whatever leftover from when I built it?

I guess what I am saying is... I am not sure if this increasing the column ultimately will help with smearing.

[still_stirrin]

...what might have been problem that I am having.... (a) nasty awful taste is bleeding into everything....So I am just curious if this ultimately will help solve that problem? Or did I just not do a sacrificial run, and the nasty taste out of the alcohol is from all the nasty flux and whatever leftover from when I built it?...I am not sure if this increasing the column ultimately will help with smearing.

Well, since you didn't do a sacrificial run (properly), the awful taste very well could be from the construction materials (as I've already noted...and you've refused to accept).

And, smearing will happen unless you properly fractionalize the vapors, which is accomplished through reflux. Again (as I've already noted...and you've refused to accept), purity is proportional to the height of the column and the number of theoretical plates (which relates to the cycles of condensing and reboiling...also known as reflux). So, your smearing problem WILL be reduced if you add theoretical plates via the taller tower.

Collecting a cleaner (better separated) product will aid you to make better cuts so that you don't get "crap" smeared into your product spirit. It'll allow you to put the feints where they belong...in the feints jar, not into your spirit jar.

Now, please don't ask these same questions again. You've got reading to do...not only in this thread, but many others. And I want (make that DEMAND) you to read Kiwistiller's Guide to Cuts. It will explain how smearing occurs and how you can reduce the effects. Do your homework!!
ss

[rparody]

Wow. I had no idea I was asking the same question. and Clearly I am not refusing to accept anything that you have said. But I do appreciate you pointing me to KiwiStillers Gude.

[NZChris]

It's just as much trouble to add a foot as it is to add two and the extra foot will make better product. I chain mine to the ceiling to keep it stable and for storing it.

SISO. I can turn a nice wash into nice vodka with two passes through a pot still, but even with 48" of marbles, I doubt my reflux could turn nasty low wines into something that I would consider was good enough to drink as a vodka or use for gin base.