Is it true: Wider column = faster run?

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Is it true: Wider column = faster run?

Post by BoomTown »

I saw a posting on a different forum, said that a wider column would run faster than a narrow range one. So I’m running 1 ¼” column choking down to a ½” chiller.

Would my rig run faster if I used 1 ¼” chiller, possibly choking down at the fluid exit ?

I know that as the vapor condenses back to fluid, there is a volume reduction that creates a vacuum that should suck air to refill the volume as the condenser converts the vapor back to fluid...is this backdraft part of the chilling characteristics of the condenser?
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Re: Is it true: Wider column = faster run?

Post by still_stirrin »

Is it really a “column”? Columns are used in reflux stills. Columns are packed. If you’ve got a potstill, the pipe off the top of the boiler is just a “riser”. It allows you to put the condenser where you need it to do its job. It does not induce reflux, so height doesn’t matter.

Now, about the size, or diameter, ie - cross-sectional flow area. The size affects vapor velocity, or more specifically, the acceleration of the vapor through the pipe. And as it “speeds up”, it will become less dense, because the static pressure falls as the vapor flows. This may seem counter-intuitive, especially when compared to a liquid flow. But that’s what happens with vapor.

So, diameter (flow area) really doesn’t affect the purity measurably. But, again because of the limiting factor of vapor flow velocity, slower flow velocity will transfer its heat quicker and your condenser will be more efficient.

You’ve asked about a vapor “backdraft”. Indeed, that can happen with “shock cooling”, or a sudden vapor collapse. If your condenser has a high water flow rate and/or the water is cold, you can get this sudden collapse in the condenser and it will make a sucking (huffing) sound as ambient air pulses into the condenser to replace a volume of vapor as it condenses quickly. Slowing the cooling water flow helps, as it will create a longer temperature gradient within the condenser. As a result, you’ll get a more gradual condensation of the vapors.

Hope this helps answer your questions.
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Re: Is it true: Wider column = faster run?

Post by Setsumi »

well for me it is not a race/time competition. BUT i rather go slow on in big diameter column than fast on a small diameter column. i appreciated the tech of my 54mm Bokakop but my 76mm CCVM were just better. yes go lager diameter if possible.

edit after ss. did not realize you were on potstill.
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Re: Is it true: Wider column = faster run?

Post by Saltbush Bill »

Without knowing what kind of still or column your talking about its hard to say,
A six inch plated column running 4 plates sure is faster than a 4 incher run the same way.
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Re: Is it true: Wider column = faster run?

Post by BoomTown »

still_stirrin wrote: Mon Mar 22, 2021 11:46 am Is it really a “column”? Columns are used in reflux stills. Columns are packed. If you’ve got a potstill, the pipe off the top of the boiler is just a “riser”. It allows you to put the condenser where you need it to do its job. It does not induce reflux, so height doesn’t matter.

Now, about the size, or diameter, ie - cross-sectional flow area. The size affects vapor velocity, or more specifically, the acceleration of the vapor through the pipe. And as it “speeds up”, it will become less dense, because the static pressure falls as the vapor flows. This may seem counter-intuitive, especially when compared to a liquid flow. But that’s what happens with vapor.

So, diameter (flow area) really doesn’t affect the purity measurably. But, again because of the limiting factor of vapor flow velocity, slower flow velocity will transfer its heat quicker and your condenser will be more efficient.

You’ve asked about a vapor “backdraft”. Indeed, that can happen with “shock cooling”, or a sudden vapor collapse. If your condenser has a high water flow rate and/or the water is cold, you can get this sudden collapse in the condenser and it will make a sucking (huffing) sound as ambient air pulses into the condenser to replace a volume of vapor as it condenses quickly. Slowing the cooling water flow helps, as it will create a longer temperature gradient within the condenser. As a result, you’ll get a more gradual condensation of the vapors.

Hope this helps answer your questions.
ss
Excellent explanation, thank you. By your explanation, l am not using a column, though I’ve packed longer ‘riser’ pieces with copper mesh in the past. In re-engineering this rig, I’m inserting a thumper, using 1 ¼” copper throughout the vapor path, including the condenser, with no reduction in the vapor flow at all. I’ll bring the riser out of the thumper directly into 20” length enclosed inside of a 3” pvc sleeve fed by a ⅛” water flow, gravity fed water with the water recycled by an aquarium pump. The condenser section will be packed with copper mesh, and output collected as it exits the 1 ¼” opening. I have run at lowest possible heat without the thumper, but will add heat at the Pot, hoping the thumper will chil the Pot’s output to the vapor point of alcohol before feeding into the chiller. When running in the past, runs took 4 to 6 hours foe the 16L pot. Hoping to drop run time to 3 hours, or less.
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Re: Is it true: Wider column = faster run?

Post by Yummyrum »

I think a 1.25” copper inside a 3” Shell is not going to be very effective . ... for two reasons .

1.25” is a relatively large diameter . And being only 20” long , there will be a lot if laminar flow where the vapour in the middle of the pipe will flow straight through . Adding mesh should help with making the flow more turbulent and hopefully allow the middle flow to mix to the cool wall.

Secondly , you would be better off with a smaller diameter shell .... perhaps 1.5” . The thinner the jacket space , the more efficient the condenser is .


But to answer your topic question . With respect to a reflux still with a packed column , yes you can apply more power because the area is larger and this will scale up the takeoff rate .

Just increasing diameter does not increase speed .
You have to scale up the power as well . ... which you can do because the area in the Column is larger and can cope with the extra vapour .
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Re: Is it true: Wider column = faster run?

Post by Kindafrench »

I was thinking of a, let‘s call it „Dyson cooler“. But will start a separate thread later. Just sparking the idea (which is possibly total humbug). This could use a 2“ pipe for turbine turbulent vapor flow, but how to cool? Lots of work for bad efficiency? Who knows.
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Re: Is it true: Wider column = faster run?

Post by cartoonStiller »

Hi all
I'm probably going to get in trouble for asking but I am at my wits end.
We are a licenced commercial brewery with a 500L pot still with a 52cm wide column all the way though to the tapered exit pipe with a 2 stage condenser of 500mm long and then a 100mm condenser and an agitator, digital temp control and 5000L cooling tank.
Currently we are experiencing extremely slow distillation speed taking about 12 hours to get 80l from a 16% wash or am I simply being impatient.
Any help would be apricated sorry if I have posted in the incorrect section.
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Re: Is it true: Wider column = faster run?

Post by Yummyrum »

Sounds to me like you don’t have enough power going into your boiler . .... that could have something to do with the temp controller you mentioned .

A pic of your setup might help ... just a bit unsure about what you are talking about regarding your 2 stage condenser setup .
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Re: Is it true: Wider column = faster run?

Post by Expat »

cartoonStiller wrote: Thu Mar 25, 2021 1:48 am Hi all
I'm probably going to get in trouble for asking but I am at my wits end.
We are a licenced commercial brewery with a 500L pot still with a 52cm wide column all the way though to the tapered exit pipe with a 2 stage condenser of 500mm long and then a 100mm condenser and an agitator, digital temp control and 5000L cooling tank.
Currently we are experiencing extremely slow distillation speed taking about 12 hours to get 80l from a 16% wash or am I simply being impatient.
Any help would be apricated sorry if I have posted in the incorrect section.
Would require more information to do more than guess.
How much power is being applied, and how much is there available in total?

Also... "digital temp control" sounds suspiciously like a PID, which isn't appropriate for distillation.

So how much power are you applying or are you trying to run the pot by temp (you can't)?
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Re: Is it true: Wider column = faster run?

Post by Saltbush Bill »

Expat wrote: Thu Mar 25, 2021 4:08 am Also... "digital temp control" sounds suspiciously like a PID, which isn't appropriate for distillation.
My first thought also.
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Re: Is it true: Wider column = faster run?

Post by cartoonStiller »

Apologies the pot is 500l oil jacket 3phase 45amp or about 17kw which is running off a PID and my thoughts were because the pot is jacketed a PID is fine as the oil has excellent thermal mass and no thermal shock? (Also the PID is running on a solid state relay that can switch current off/no in the micro seconds.) We are getting stable flows its just taking a long time. Side not I'm also wondering if I have over filled my pot as well.
I will post pictures of the setup in the morning thanks all
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Re: Is it true: Wider column = faster run?

Post by Expat »

Okay, the details help.

17KW its going to take a good while to heat 500L, plus the mass of the copper, steel and oil.... something like 8 hour warm up?? if it got it right. This i'm assuming is a large part of the above run time, which would make sense given the thermal mass.

Yeah, a bain marie will help to normalize the transfer of heat (avoid scorching and the like), but its not going to change PID being a temperature feed back loop. You want % power input not temp. Once you have that level of control, you can accelerate the vapor production rate by increasing power.
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Re: Is it true: Wider column = faster run?

Post by Butch27 »

Expat wrote: Thu Mar 25, 2021 3:48 pm ....its not going to change PID being a temperature feed back loop. You want % power input not temp. ....
First, I do not know much about PIDs, but I am thinking it may be ok in this case IF it is trying to control the temp of the oil and not the boiler.
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Re: Is it true: Wider column = faster run?

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Butch27 wrote: Thu Mar 25, 2021 4:49 pm
Expat wrote: Thu Mar 25, 2021 3:48 pm ....its not going to change PID being a temperature feed back loop. You want % power input not temp. ....
First, I do not know much about PIDs, but I am thinking it may be ok in this case IF it is trying to control the temp of the oil and not the boiler.
Much the same thing, allowing for the thermal transfer properties of the metal in-between.
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Re: Is it true: Wider column = faster run?

Post by Butch27 »

Expat wrote: Thu Mar 25, 2021 4:55 pm
Butch27 wrote: Thu Mar 25, 2021 4:49 pm
Expat wrote: Thu Mar 25, 2021 3:48 pm ....its not going to change PID being a temperature feed back loop. You want % power input not temp. ....
First, I do not know much about PIDs, but I am thinking it may be ok in this case IF it is trying to control the temp of the oil and not the boiler.
Much the same thing, allowing for the thermal transfer properties of the metal in-between.
I don't think so. If the boiler temp was 190, you could have the PID bring the oil to 200, thereby having a 10 degree difference between the oil and the boiler and actively trying to heat the boiler to 200. You could possibly control the heat input by having two temp sensors, one in the oil and one in the boiler. The operator would then control the heat input by setting the difference between the two temperatures in the PID. As the temp in the boiler rose the PID would add more power to try maintain the oil at a temperature that number of degrees above the boiler. The larger the temp difference set, the more power applied to the unit.
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Re: Is it true: Wider column = faster run?

Post by MartinCash »

Butch27 wrote: Thu Mar 25, 2021 5:24 pm I don't think so. If the boiler temp was 190, you could have the PID bring the oil to 200, thereby having a 10 degree difference between the oil and the boiler and actively trying to heat the boiler to 200. You could possibly control the heat input by having two temp sensors, one in the oil and one in the boiler. The operator would then control the heat input by setting the difference between the two temperatures in the PID. As the temp in the boiler rose the PID would add more power to try maintain the oil at a temperature that number of degrees above the boiler. The larger the temp difference set, the more power applied to the unit.
I agree you can do this, but it seems unnecessary and suboptimal, when constant power input that you can regulate would be more than adequate.
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Re: Is it true: Wider column = faster run?

Post by shadylane »

Expat wrote: Thu Mar 25, 2021 3:48 pm Okay, the details help.

17KW its going to take a good while to heat 500L, plus the mass of the copper, steel and oil.... something like 8 hour warm up?? if it got it right. This i'm assuming is a large part of the above run time, which would make sense given the thermal mass.

Yeah, a bain marie will help to normalize the transfer of heat (avoid scorching and the like), but its not going to change PID being a temperature feed back loop. You want % power input not temp. Once you have that level of control, you can accelerate the vapor production rate by increasing power.
I'm thinking a PID would work good for controlling the oil temp in a Bain Marie.
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Re: Is it true: Wider column = faster run?

Post by Saltbush Bill »

I started out thinking along the same lines, your not using the PID to control boiler temp, you would be using it to maintain the oil in the bane marie at a safe but optimal working temperature.
The oil temp would be much hotter that the maximum temp needed for the still to function properly.
The boiler temp would still self regulate.
........then the more I think the more Im not sure.
Energy input control still becomes a problem at times when you want the still to produce at different speeds such as when taking fores?
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Re: Is it true: Wider column = faster run?

Post by cartoonStiller »

Expat wrote: Thu Mar 25, 2021 3:48 pm Okay, the details help.

17KW its going to take a good while to heat 500L, plus the mass of the copper, steel and oil.... something like 8 hour warm up?? if it got it right. This i'm assuming is a large part of the above run time, which would make sense given the thermal mass.

Yeah, a bain marie will help to normalize the transfer of heat (avoid scorching and the like), but its not going to change PID being a temperature feed back loop. You want % power input not temp. Once you have that level of control, you can accelerate the vapor production rate by increasing power.
Yes agreed. I think on Monday I'll do a 380L batch and see how that goes. Unfortunately the PID will have to stay until we build our continuous steam still as the bank is looking a bit empty xD. I might also put a small vacuum pump on as well but will see.
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Re: Is it true: Wider column = faster run?

Post by BoomTown »

Yummyrum wrote: Mon Mar 22, 2021 11:14 pm I think a 1.25” copper inside a 3” Shell is not going to be very effective . ...


But to answer your topic question . With respect to a reflux still with a packed column , yes you can apply more power because the area is larger and this will scale up the takeoff rate .

Just increasing diameter does not increase speed .
You have to scale up the power as well . ... which you can do because the area in the Column is larger and can cope with the extra vapour .
Well Yummyrun, I’ve run my cleaning run and first beer run, and thought you’d like my follow up.

After thinking about amping up the power, I decided instead to insulate the pot, wrapping it with 1” of commercial boiler approved fiberglass insulation. I packed the sleeve of the chiller with copper mesh, and the inside with copper mesh too.

Using the same pot, the same 1500wt hotplate, The total run time of the beer run is cut by half, that after reducing the temperature of the hotplate by half,(same setting for running slow, when formerly using ½” tubing throughout, including a chiller made with ½” Inclosed in a 1 ¼” sleeve) and adding a 1 gallon Thumper that had 2 pints of combined heads and tails from a previous Spirit run. Formally, there were faint, but detectable orders emitted during the run, those are now gone. Output averaged 160 throughout the run, an increase of 10 points overall.


So my conclusions are; it may be because of the insulation, or the bigger tubing, but the desired result was achieved. Using the tubing scaled up to 1 ¼” in combination with insulating the pot, definitely shortened the run time in and of itself, and inserting the thumper adds 10 points to the value of the ABV of the low wine resulting during a beer run. I can adjust the flow rate at the hotplate more effectively now too, varying the heat to increase the flow or diminish it. The hotplate is stock, no modifications to the rheostat, but there is a heat sink in the form of stone pebble 1” deep inside the pot, that compensates for the on\off design inherent to the off-the-shelf hotplate.

I’m now considering amping up the power, anticipating a drop in the ABV rating during the beer runs, and then choking back the heat even more during the spirit run to increase the ABV output through the thumper.

Thanks for your comments, they helped my thinking.
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Re: Is it true: Wider column = faster run?

Post by closetdistiller »

The output proof is determined by 2 things. 1) The mash ABV. 2) The effective number of plates.

With a pot still with 2 retorts (thumpers) you have 3 effective plates. No more, no less. It's the same as running a bubble column with 2 plates.

Running slow or running fast doesn't change the output proof. To change the output proof you need to add active reflux and plates or packing somewhere.
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Re: Is it true: Wider column = faster run?

Post by BoomTown »

On to now building a Boka. Using 2” copper column, I plan to insert 3 plates. Years ago, there was a link to cutting patterns for making the plates, but I’m locked out of seeing anything over a year back. Can someone repost those patterns, please?
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Re: Is it true: Wider column = faster run?

Post by Saltbush Bill »

I fail to see how you can be locked out of seeing more than a year back......why do you want 3 plates.?
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Re: Is it true: Wider column = faster run?

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closetdistiller wrote: Wed Apr 28, 2021 3:55 am
Running slow or running fast doesn't change the output proof. To change the output proof you need to add active reflux and plates or packing somewhere.
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Re: Is it true: Wider column = faster run?

Post by Saltbush Bill »

LWTCS wrote: Thu Apr 29, 2021 3:29 am
closetdistiller wrote: Wed Apr 28, 2021 3:55 am
Running slow or running fast doesn't change the output proof. To change the output proof you need to add active reflux and plates or packing somewhere.
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Re: Is it true: Wider column = faster run?

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Saltbush Bill wrote: Thu Apr 29, 2021 2:40 am I fail to see how you can be locked out of seeing more than a year back......why do you want 3 plates.?
Yeah, it troubles me too. I was gone for several years, and the problem manifested when my account was resurrected. Worked with Admin on it till I just gave up. As for the number of plates, I’m thinking I’ll set up one as the output, and two to reflux the condensed fluids below the spill from the higher plate...trying to maximize ABV. May set one lower in the mesh filler area, to contain the mesh, and feed it with one right at the top of the filler, and the take off plate just below the condenser coil?
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Re: Is it true: Wider column = faster run?

Post by MartinCash »

Hey @closetdistiller, please don't post wrong information.

Before adding anything, please learn about reflux ratio and its effect on ethanol concentration. Then meditate on the effect of changing the boil or collection rates on reflux rate and proof.
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Re: Is it true: Wider column = faster run?

Post by BoomTown »

MartinCash wrote: Thu Apr 29, 2021 3:21 pm

Before adding anything, please learn about reflux ratio and its effect on ethanol concentration. Then meditate on the effect of changing the boil or collection rates on reflux rate and proof.
Is there a specific source you’d recommend for learning about this?

Boomtown needs to learn more about this.
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Re: Is it true: Wider column = faster run?

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BoomTown wrote: Sat Aug 07, 2021 12:40 pm
MartinCash wrote: Thu Apr 29, 2021 3:21 pm

Before adding anything, please learn about reflux ratio and its effect on ethanol concentration. Then meditate on the effect of changing the boil or collection rates on reflux rate and proof.
Is there a specific source you’d recommend for learning about this?

Boomtown needs to learn more about this.

Source?
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