Why You Can't Control Temperature

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Why You Can't Control Temperature

Post by fizzix » Sat Aug 10, 2019 5:12 am

=This deserves its own thread=
----------------------------------------
Why You Can't Control Temperature
by Saltbush Bill:

A few things for you to ponder, regarding temps and how alcohols react in a still boiler
Firstly you can not regulate the temperature of the wash in your boiler, there for its kinda hard to regulate the vapor temperature.
Water boils at 100 C ......no matter how much heat you apply to it it wont get hotter...it will just boil harder and create more steam/ vapor.
Alcohols work in the same manner.
Acetone boils at 56C
Methanol at 64.7C
Ethanol at 78C
Water at 100c
That is only the boiling point of four of the many things found in the average wash.
Now to complicate things further you are trying to boil a mix of the above ...........what is the boiling point of that mixture????????
The answer is that the boiling point is constantly changing as the different / lower boiling point alcohols leave the boiler. It will increase the whole time as the ABV of the wash gets lower.
This is one of the things about distilling that many newbies have trouble understanding at first.
The last thing worth thinking about is that if you put a shallow bowl of water outside in hot weather , after a few days the bowl is empty. Liquids don't need to boil to evaporate and that is partly the reason you can never make perfect cuts / separate the fractions of a wash perfectly. Different still types do a better or worse job of it, pot stills smear worse than most.

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Re: Why You Can't Control Temperature

Post by decoy » Sat Aug 10, 2019 5:29 am

+1

Something new distillers can try next time, you can do this on your stove.
Save 100-200ml of heads for this one.
Bring about 1L of water to boil, then turn of the heat and wait a few sec's for the boiling to stop
now slowly tip about 100ml of heads into it.

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Re: Why You Can't Control Temperature

Post by jonnys_spirit » Sat Aug 10, 2019 8:28 am

I’ll contribute a little with some Fahrenheit conversion and this is great info. Thanks for the detail fizzix.

—— snip ——
Acetone boils at 56C = 132.8F
Methanol at 64.7C = 148.46F
Ethanol at 78C = 172.4F
Water at 100c = 212F
—— snip ——

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Re: Why You Can't Control Temperature

Post by fizzix » Sat Aug 10, 2019 8:33 am

jonnys_spirit wrote:
Sat Aug 10, 2019 8:28 am
I’ll contribute a little with some Fahrenheit conversion and this is great info. Thanks for the detail fizzix.

—— snip ——
Acetone boils at 56C = 132.8F
Methanol at 64.7C = 148.46F
Ethanol at 78C = 172.4F
Water at 100c = 212F
—— snip ——
Thanks for the conversions, jonny. And this is ALL Saltbush Bill's doing. Being buried elsewhere just wasn't doing it any justice.

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Re: Why You Can't Control Temperature

Post by jimmayhugh » Sat Aug 10, 2019 4:08 pm

jonnys_spirit wrote:
Sat Aug 10, 2019 8:28 am
I’ll contribute a little with some Fahrenheit conversion and this is great info. Thanks for the detail fizzix.

—— snip ——
Acetone boils at 56C = 132.8F
Methanol at 64.7C = 148.46F
Ethanol at 78C = 172.4F
Water at 100c = 212F
—— snip ——

Cheers,
Jonny
At sea level with 29.92 inches of barometric pressure...
YMMV depending on altitude, humidity, wind, etc, etc, etc...

Here in Las Vegas (~2000ft altitude), water typically boils at 209F

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Re: Why You Can't Control Temperature

Post by still_stirrin » Sun Aug 11, 2019 5:24 am

jimmayhugh wrote:
Sat Aug 10, 2019 4:08 pm
...Here in Las Vegas (~2000ft altitude), water typically boils at 209F
Of course we all know....”what happens in Vegas...stays in Vegas”. :ebiggrin:
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Re: Why You Can't Control Temperature

Post by Mr Sippy » Sun Aug 11, 2019 5:32 am

...the boiling point is constantly changing as the different / lower boiling point alcohols leave the boiler.
I'm sure SBB knows it; but for folks learning this, it's helpful to note the the lower boiling components won't leave the still at that boiling point. The alcohols are attached to water by force of hydrogen bonding. It take more energy to break those molecular bonds; i.e. higher boiling point.

Also worth mentioning:
The boil point point is determined by the sum of the individual vapor pressures of the various components.
Individual vapor pressures are determine by their ratio of their mols in the mix.
When the total vapor pressure equals your atmospheric pressure the mixture boils. That is the boil definition.

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Re: Why You Can't Control Temperature

Post by Saltbush Bill » Sun Aug 11, 2019 5:57 am

Yeah lets make this as complicated as possible to confuse newbies even further......cant this just be kept simple and be explained in simple terms?

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Re: Why You Can't Control Temperature

Post by Bushman » Sun Aug 11, 2019 6:26 am

I believe in simplicity but I also believe the devil is in the details. I love the science behind it thus I am enjoying this thread (thanks fizzix for starting it). Yes, we don’t need to know all the detail but for me I enjoy the discussion.

The more we know, the more we forget;
The more we forget, the less we know;
The less we know, the less we forget;
The less we forget, the more we know!

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Re: Why You Can't Control Temperature

Post by DCS5458 » Fri Nov 08, 2019 5:21 pm

Thank you fizzix for starting this thread and jonnys_spirit for the conversion (I am in the USA) ....... I am new to all of this and really do appreciate any of your views and advice for my build .........

Thanks again from DCS5458 .........
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Re: Why You Can't Control Temperature

Post by Sailman » Sat Nov 09, 2019 7:46 am

First off let me say that I'm new to all of this so I have a question. If you record the temperature of the vapor before it goes in the condenser and you discard any product that comes out of the condenser up to the boiling point of methanol would that be a good point to start looking for the hearts? I understand that small Cuts jars would be needed to verify this and that several compounds mixed together boil at different temperatures. But if you let the temperature stabilized let's say a couple two or three degrees above boiling point of methanol and you hold it there until you have no more product coming out of the condenser would this not Ensure that all of the nasties have been boiled off? Help me understand why I am wrong!
I'm sure a lot of this will become clear after I've got a few runs in the jar. I'm just trying to learn the right way of doing things and why they are the right way.

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Re: Why You Can't Control Temperature

Post by cayars » Sat Nov 09, 2019 9:03 am

I understand what is trying to be said here but I'm not sure I agree with this as stated.
We do in fact control our stills by temperature. We can control both the boiler temperature and top of column as well. In reality temperature applied to the boiler is the only thing we do control assuming you have a proper water supply of sufficient temp knocking the vapor down.

There is most definitely a correlation of ethanol to water, ethanol to methanol, etc. that affect the boiling point of what is in the boiler. Take the most basic of stills (pot still) and bring it up to temp very slowly and you can pull off more of the volatiles earlier then the ethanol. There will always be some degree of smearing but it's far more controlled. You can "compress" the heads more by running the lowest temps as needed while very slowly raising the boiler temp as needed. This will give you cleaner (for a pot still) heads to hearts conversion. Add in column temperature control and you have far better reflux control based on temperature.

Compare that to just cranking up the heat quickly bringing everything to 100C and getting everything smeared very badly across the whole run. Surely the temperature is at play here as a higher than needed temperature will increase the vapor rates. Many of the still automatons make use of boiler temp, column temp, flow rates, etc and adjust things on the fly specifically to control different temperatures to get cleaner cuts and to compact heads and tails.

With the right equipment you can automate this with algorithms that do exactly this. You can monitor temps, rates, ABV in boiler, ABV in output, etc and control everything by adjusting temperatures.

Of course you can't remove everything as it's not that simple but you can "compact" things based on temperature and holding certain temps for a period of time. This is exactly what many higher end stills do.

What am I missing?
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Re: Why You Can't Control Temperature

Post by Twisted Brick » Sat Nov 09, 2019 9:45 am

.
I believe Sailman was asking about a pot still.

His question was: since we cannot control the temperature of the wash in a boiler, why can't we just regulate the temperature of the vapors that come off and separate them accordingly?

The short answer is that a pot still smears based on the aggregate volatility/ABV of that particular wash at that power level on that still. Change either of these variables and the entire scale gets thrown out of whack. That's why we collect in jars and make salient cuts after the fact. It's also why keeping a log of each spirit run is important as hearts (on my still) have appeared anywhere between 87%ABV and 83%ABV. No two runs are exactly the same. Same deviation can apply to heads and tails. The fact that the ABV coming off a pot still is a moving target further complicates the mission.

I'm sure the approach Sailman questions has been asked/tried before, but it is still a worthwhile question.
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Re: Why You Can't Control Temperature

Post by cayars » Sat Nov 09, 2019 10:48 am

Ah, a split thread! I wish the mods would edit the first message of a split thread to indicate it was split from another thread which can help with context. Having just said that and now looking at the first post that says "=This deserves its own thread=" I guess I'm half blind. :) But it would be nice to know what thread it's split from.

Yes, in that context I might not have replied. However, this topic is convoluted and we do actually control pot still by temperature so it's not a clean cut conversation. Temperature/heat directly relates to how much vapor is produced. The vapor rate affects the smearing, etc... These things are all inter-related.

Thanks for taking the time Twisted Brick to elaborate the context of the op post.
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Re: Why You Can't Control Temperature

Post by NZChris » Sat Nov 09, 2019 11:01 am

cayars wrote:
Sat Nov 09, 2019 10:48 am
Ah, a split thread! I wish the mods would edit the first message of a split thread to indicate it was split from another thread which can help with context. Having just said that and now looking at the first post that says "=This deserves its own thread=" I guess I'm half blind. :) But it would be nice to know what thread it's split from.
viewtopic.php?t=74802
cayars wrote:
Sat Nov 09, 2019 10:48 am
Yes, in that context I might not have replied. However, this topic is convoluted and we do actually control pot still by temperature so it's not a clean cut conversation. Temperature/heat directly relates to how much vapor is produced. The vapor rate affects the smearing, etc... These things are all inter-related.

Thanks for taking the time Twisted Brick to elaborate the context of the op post.
Please don't include me in that "we" group, Cayars. I've never controlled the temperature in any of my pots stills, ever.

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Re: Why You Can't Control Temperature

Post by Saltbush Bill » Sat Nov 09, 2019 11:38 am

Nor have I ....i have never controlled any still by temp regardless of type. You are wrong cayars, you just dont know it yet.
That may be the reason that there isnt a type of still called a TM " Temprature Management" .......were as we do have VMs CMs and such.

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Re: Why You Can't Control Temperature

Post by cayars » Sat Nov 09, 2019 12:35 pm

Guys if you add or remove heat from a pot still you are controlling temperature and vapor rate of what's in the boiler up to the point of it's boiling point.
If you adjust the flow rate on a pot still by changing the energy being applied to the boiler you are changing temperature (energy applied to it).

You run a pot still by changing temperature or if you prefer "heat energy" applied to the boiler. It's as simple as that. Now you may not be watching a thermometer or using anything other than watching the drip, drip, spurt (flow rate) coming out but you adjust this by changing the energy applied which many people simply refer to as the heat source temperature. Energy in this case is heat and this is what people refer to as "temperature" even if not 100% correct.

You can argue that at 212 F/100C the temperature won't go higher but the vapor rate will increase and of course this is true.

This is relative. I can set my oven to 212 F or 350 F and put a pan of water in it. Both will cause it to boil and the water itself will only reach a certain temperature but the temperature (or more correctly energy applied) is quite different. If I externally adjust that oven dial temperature setting I can change the rate of evaporation. With a different liquid a much higher liquid temperature of course can be had when applying the same "temperature" per the "dial".

This is what people are referring to by "temperature". Some may not like that nomenclature and I certainly get that. Had I said "energy applied" rather then temperature then I doubt there would be much discussion.

Technically "temperature" is wrong and energy would be more accurate and I certainly get that but it's beyond what most people mean when they say "temperature".

And yes, both of you guys do adjust the temperature of your pot stills. You do it by controlling the amount of heat energy you apply to it. You start out at room temperature (most likely), then increase temperature until you get some flow. Depending on what you run you may hold temp or reduce the temperature slightly till you get past heads then maybe raise it a bit for faster flow rates of hearts or reduce temperature for slower flow rates. Then you may change the temperature again to quickly pull off tails. <-- This is what people mean by talking "controlling temperature" but we know it's actually the energy applied in some form to the boiler. Temperature and/or vapor rate is actually the direct result of the heat (energy) applied.
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Re: Why You Can't Control Temperature

Post by Sailman » Sat Nov 09, 2019 1:22 pm

Thanks for the further explanation it makes a little more sense now with the to relation of heat energy and temperature.

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Re: Why You Can't Control Temperature

Post by Saltbush Bill » Sat Nov 09, 2019 1:25 pm

Finaly you have got something right. You can not use energy input and the word temperature to mean the same thing..They are two very differnt things..
I stand by my words, You can NOT control the temperature of wash or vapor in a boiler or still..
You can control the energy input which is a completely different thing.

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Re: Why You Can't Control Temperature

Post by Saltbush Bill » Sat Nov 09, 2019 1:49 pm

cayars wrote:
Sat Nov 09, 2019 9:03 am
Compare that to just cranking up the heat quickly bringing everything to 100C and getting everything smeared very badly across the whole run.
This statement alone shows a lack of understanding and only serves to confuse hell out of newbies.
You could put a Nuclear reactor under the boiler ...it wouldn't and wont reach 100c unless the only thing in that boiler is water.
No fear of smearing anything there.......there is nothing but water to smear.
Last edited by Saltbush Bill on Sat Nov 09, 2019 2:18 pm, edited 1 time in total.

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Re: Why You Can't Control Temperature

Post by Pikey » Sat Nov 09, 2019 2:07 pm

NZChris wrote:
Sat Nov 09, 2019 11:01 am
...................
Please don't include me in that "we" group, Cayars. I've never controlled the temperature in any of my pots stills, ever.
I have - when I first started !

My thinking was exactly along the lines Sailman suggests ! It is just SO Obvious to anyone who has learned on their own and not had a "Mentor" that this is the right way to do it !

I have put up the pictures of the comparitive yields elsewhere in the forum

Then I discovered the power of disconnecting the thermostat !

As to those conflagrating "temperature" with "Energy supplied" - well that is both plain Wrong and confusing for anyone who trying to understand.

Temperature is temperature.
Energy is Energy.

And NO you cannot increase Temperature above boiling point in a liquid at a specified pressure.

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Re: Why You Can't Control Temperature

Post by Saltbush Bill » Sat Nov 09, 2019 2:28 pm

Sailman wrote:
Sat Nov 09, 2019 1:22 pm
Thanks for the further explanation it makes a little more sense now with the to relation of heat energy and temperature.
Sailman There is no relationship between the energy input and the temperature of the wash.
There is a relationship between energy input and how hard the wash boils.
Sorry if this whole thing has confused you :(

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Re: Why You Can't Control Temperature

Post by NZChris » Sat Nov 09, 2019 2:53 pm

Pikey wrote:
Sat Nov 09, 2019 2:07 pm
NZChris wrote:
Sat Nov 09, 2019 11:01 am
...................
Please don't include me in that "we" group, Cayars. I've never controlled the temperature in any of my pots stills, ever.
I have - when I first started !

My thinking was exactly along the lines Sailman suggests ! It is just SO Obvious to anyone who has learned on their own and not had a "Mentor" that this is the right way to do it !
Unfortunately, there are some self appointed "Mentors" who haven't figured it out yet, who have posted their mistaken thinking as instructional videos on Youtube. Hopefully, they haven't got much of a following.

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Re: Why You Can't Control Temperature

Post by cayars » Sat Nov 09, 2019 2:58 pm

Saltbush Bill wrote:
Sat Nov 09, 2019 1:25 pm
Finaly you have got something right. You can not use energy input and the word temperature to mean the same thing..They are two very different things..
I stand by my words, You can NOT control the temperature of wash or vapor in a boiler or still..
You can control the energy input which is a completely different thing.
You're trying parse words as people use them. People do not always talk scientific but use common language and the vernacular of everyday language. If someone asks you to raise the temperature of the oven or stove you know they want the heat/energy being applied to increase. When cooking a piece of meat or turkey or any other thing in the oven you may set the temperature to 400 but that doesn't mean your meat is that temperature. Hopefully you would apply energy while watching the temperature of the meat until it gets to the correct temp.

Remember that temperature is the degree or intensity of heat present in a substance or object usually expressed according to a comparative scale. If you have water at 212 F or 100 C and apply additional heat you have increased the intensity of heat present in the water. A particular scale such as a thermometer may stop recording temperature increases at 212 F due to that being it's boiling point but due to the increased intensity of heat being applied will now vaporize quicker. You can add more heat to the water and increase the intensity of the water. A thermometer is only one way to measure temperature, not the only way.

Temperature is just a measurement of the degree of heat present or being changed. No one changes "temperature" per say but adjusts the energy which is measured can be measured as temperature or vapor speed.
Saltbush Bill wrote:
Sat Nov 09, 2019 1:49 pm
cayars wrote:
Sat Nov 09, 2019 9:03 am
Compare that to just cranking up the heat quickly bringing everything to 100C and getting everything smeared very badly across the whole run.
This statement alone shows a lack of understanding and only serves to confuse hell out of newbies.
You could put put a Nuclear reactor under the boiler ...it wouldn't and wont reach 100c unless the only thing in that boiler is water.
No fear of smearing anything there.......there is nothing but water to smear.
Again, using the vernacular. I'm quite sure you know what that meant in the context of what was being said. BTW, it's not just water in the boiler. You can surely at times heat it to more than 212 F or 100 C recorded by a typical thermometer. It depends on what is in the boiler. The amount of minerals and salts in the solution can surely allow the solution to rise above 212 F or 100 C. Add a pound of salt to a gallon of water and try to boil it and record the temp. :)

I believe the boiling point temperature will increase about a one-half degree Celsius for every 58 grams of dissolved salt per kilogram of water. This isn't exclusive to water. It occurs any time you add a non-volatile solute (such as salt) to a solvent.

And yes, if you heat slowly and have a slower vapor rate you can have less smearing than if you crank the heat and create more vapor and faster flow than wanted. The two are correlated. With to much vapor (from to much heat) you will not only smear the different alcohols (and other substances) but will smear the water in with it as well.

Personally I'd not use a nuclear reactor as I'd be afraid my distillate might taste a bit "hot". LOL
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Re: Why You Can't Control Temperature

Post by Saltbush Bill » Sat Nov 09, 2019 3:32 pm

I see mention of a Turkey ....how appropriate. I value my membership here so I'll just :silent: for now.

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Re: Why You Can't Control Temperature

Post by NZChris » Sat Nov 09, 2019 4:01 pm

cayars wrote:
Sat Nov 09, 2019 2:58 pm
You're trying parse words as people use them. People do not always talk scientific but use common language and the vernacular of everyday language.
If you don't use a term correctly, it is reasonable to expect to be misunderstood.
cayars wrote: If someone asks you to raise the temperature of the oven or stove you know they want the heat/energy being applied to increase. When cooking a piece of meat or turkey or any other thing in the oven you may set the temperature to 400 but that doesn't mean your meat is that temperature. Hopefully you would apply energy while watching the temperature of the meat until it gets to the correct temp.
An oven cooking a piece of meat has little to do with temperatures in a still.
cayars wrote: If you have water at 212 F or 100 C and apply additional heat you have increased the intensity of heat present in the water.
Not when I went to school. If you add more heat to already boiling water, it boils faster and gets rid of it.
cayars wrote: Temperature is just a measurement of the degree of heat present or being changed. No one changes "temperature" per say but adjusts the energy which is measured can be measured as temperature or vapor speed.
The vapor speed is related to the heat input and the abv. The temperature it is happening at isn't going to help you run the still. You would be better off to pull your thermometers out and control the takeoff speed by the heat input.

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Re: Why You Can't Control Temperature

Post by cayars » Sat Nov 09, 2019 5:37 pm

NZChris wrote:
Sat Nov 09, 2019 4:01 pm
If you don't use a term correctly, it is reasonable to expect to be misunderstood.
I get this but sometimes you just have to understand VERY COMMON vernacular without changing into scientist mode. If your wife asks you to turn the oven on to 450 F do you correct her that you don't adjust an oven temperature but change the amount of heat input/energy being applied and use temperature to monitor the status of the energy change? That's kind of my point.
NZChris wrote:
Sat Nov 09, 2019 4:01 pm
Not when I went to school. If you add more heat to already boiling water, it boils faster and gets rid of it.
That's what "increased the intensity of heat present in the water" does. It makes the vapor coming of faster. You can take lightly boiling water on the stove and add more heat to it and it will boil more violently (more thermodynamic intensity) and thus also create more vapor. Same thing on a pot still. Turn up the heat and the vapor escaping the boiler increases as well.

Now just to have some fun with semantics and using terms correctly. :) How can it boil faster if it's already boiling? You meant it will boil more violently correct? That's what I mean about vernacular. You knew what you meant, and I knew what you meant and would assume others also knew what you meant even if it wasn't said exactly correctly.
NZChris wrote:
Sat Nov 09, 2019 4:01 pm
The vapor speed is related to the heat input and the abv. The temperature it is happening at isn't going to help you run the still. You would be better off to pull your thermometers out and control the takeoff speed by the heat input.
Totally agree it's related to the heat input (measured by temperature and flow rate). Now where I disagree is if monitoring this temperature can help you or not. When you have high proteins in your mash and want to avoid foaming and pukes with tougher grains like rye for example it can help a lot. If you are trying to bring out certain esters/flavors it can help, etc. Certain flavors such as "butter" can be brought out by controlling boiler temp for a specific duration followed by ramping up temps. Certain flavors can be altered by holding the boiler contents at specific temp ranges. So if you want to hold a boiler temp for 20 minutes at X temperature a controller that monitors temperature is the ideal way to do this. So for anyone to blatantly assume there is not a reason to control boiler temp via temperature monitoring and control, well lets just say we'll have to disagree. The manufacture of higher end still will likely disagree as well as they use temperature control as well (and flow rates and other monitored variables).

Now is this for the average or beginning home distiller? Probably not and for them I'd agree no temperature devices are needed and just watching the output of the still is enough for normal ordinary runs. But people should not assume that because they do not have a reason to hold at specific temps or do slow ramp up at specific temp ranges that others do not.

This is why I started my first comment with "I understand what is trying to be said here but I'm not sure I agree with this as stated." because you can control any still by monitoring certain variables and affect an outcome a certain controlled way. This can be via automation or by a human watching/monitoring things and making changes manually.
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Re: Why You Can't Control Temperature

Post by NZChris » Sat Nov 09, 2019 7:02 pm

cayars wrote:
Sat Nov 09, 2019 5:37 pm

Totally agree it's related to the heat input (measured by temperature and flow rate). Now where I disagree is if monitoring this temperature can help you or not. When you have high proteins in your mash and want to avoid foaming and pukes with tougher grains like rye for example it can help a lot. If you are trying to bring out certain esters/flavors it can help, etc. Certain flavors such as "butter" can be brought out by controlling boiler temp for a specific duration followed by ramping up temps. Certain flavors can be altered by holding the boiler contents at specific temp ranges. So if you want to hold a boiler temp for 20 minutes at X temperature a controller that monitors temperature is the ideal way to do this. So for anyone to blatantly assume there is not a reason to control boiler temp via temperature monitoring and control, well lets just say we'll have to disagree. The manufacture of higher end still will likely disagree as well as they use temperature control as well (and flow rates and other monitored variables).
Pukes are prevented by adjusting the Watts, Amps, Joules, BTUs, whatever unit you are using, to maintain the boil below what makes it puke. If you do a lot of pukey washes, you soon learn when to turn the heat down. A sudden rise in a high placed thermometer is a good puke warning and I can, but seldom bother to, automatically shut down an element using a thermocouple placed in the head. Note that this is cutting Watts into the boiler to prevent a puke, not an attempt at controlling the temperature.

Holding the wash temperature to speed up production of various esters is done below, or at, the boiling point of the wash, prior to turning the heat up to start distillation. The temperature is best read from the wash to do this, not somewhere in the still head. E.g. my still dissipates about 350W at 68C in winter, so setting the controller to 350W when it hits 68C will have it idling close enough to that temperature until I want to start it distilling.
cayars wrote: Now is this for the average or beginning home distiller? Probably not and for them I'd agree no temperature devices are needed and just watching the output of the still is enough for normal ordinary runs. But people should not assume that because they do not have a reason to hold at specific temps or do slow ramp up at specific temp ranges that others do not.
Using temperatures somewhere in the still to trigger actions that have been successfully used on repeat washes is not the same thing as controlling the temperatures at certain points during the distillation.

It's the assumption that there is a good reason to control, or hold, a vapor temperature somewhere in a pot still that is a mistake. What are these temperatures? What makes them special? How do they work?

If you want to 'ramp up' the temperature slower, use less Watts and the temperature will rise slower.

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Re: Why You Can't Control Temperature

Post by cayars » Sun Nov 10, 2019 5:19 am

There are many different ways that professional distillers control rye wash foaming and one of those ways is specific temp control in the boiler during warm up. This helps to keep the foaming down which robs heat, then when the foam collapse the heat increases and is then followed by a puke. Pukes of course can happen just from too much heat and not enough head room as well as you mention. OTHER ways also include using commercial de-foaming agents, butter, oils in the boiler with the wash. Of course how the wash/mash is prepared comes into play as well.

What I was talking about is bringing out flavors by holding at certain temperatures like 135 F for X period then continuing to boiling point. Some flavors can be brought out by going to 145 F for X period, then drop back to 110ish F for Y period followed by going back to boiling. Different temps holds during the warm up can affect flavors especially at the correct pH.

This is an area of the hobby/profession that hasn't gotten much coverage around here possibly because people lack the ability to control this consistently. I think I've only seen one thread (Butter Rum) that touches on this to some degree but was done a bit differently. using an extended or overnight rest (not needed).
Using temperatures somewhere in the still to trigger actions that have been successfully used on repeat washes is not the same thing as controlling the temperatures at certain points during the distillation.
I think that's splitting hairs on the take away of temperature control. There is no reason this can't be done on a first time wash run. This is the way to experiment and try things in a repeatable fashion if you have good results. The more precision you have in control the better if you are willing to make the adjustments needed during the wrong.
If you want to 'ramp up' the temperature slower, use less Watts and the temperature will rise slower.
Agree, but if you have specific targets to hit due to a protocol you follow or are developing, then you DO NEED to monitor the temperature and/or flow rates end of story. If you do not and just want to run a plain-Jane pot still then of course you need nothing but your eyes/senses and proper heat input control while watching it run.

There is a lot of new territory that could be expanded by having more finer control of stills in general including pot stills, using "gasp" boiler temperature monitoring and adjusting the heat based on temperature. Of course being able to monitor other things like ABV in the pot and in the "parrot", flow rates, column temp (refux stills), coolant temps, coolant flow rates, etc would allow greater control. Most people see the usefulness of this on different types of columns but fail to see the use with a pot still. Granted there is less to control on a pot but non-the-less can be done and is being done by some. This is of course is more beneficial on reflux and hybrid type stills when you also get to control reflux much more finely. People used to thumb their nose at the ideas behind G-Still and iStill but look what they can do now. While not a reflux still, a pot can take advantage of some of the same limited techniques of control as well.

This may be beyond the original intention of the thread but some of it boils down to the most simplistic control. While many/most would say a temperature controller is the wrong tool to control a pot still, I'd argue it CAN BE the exact correct cheap tool as well depending on what you are trying to achieve and what you are monitoring (ie boiler, not column), even if it means lots of small adjustments to target temp(s) along the run. Your right there with the still anyway so what's a few adjustments along the way for finer control (if appropriate)? Knowing what is trying to be achieved is key, not just assuming they will run the pot still the way most people want to run them. Would this be the preferred way for most people, hell no, as it complicates things and a simple power controller is far easier to use and should be arguably the first build to just get used to running the still the "normal way".

For people beyond the novice stage and thinking "outside the box", that like to experiment, have fine control and wanting to try different things then other unconventional methods of control are exactly what the doctor ordered.
Programmer specializing in process control for ExxonMobil (ethanol refinery control), WT, Omron, Bosch, Honeywell & Boeing.
More than a decade working for NASA & FAA Tech with computer code used on Space Shuttles and some airline flight recorders.

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Re: Why You Can't Control Temperature

Post by 6 Row Joe » Sun Nov 10, 2019 6:45 am

I get a charge out of some of the You Tube distillers with their pid controllers. Set the temp according to the boiling point charts and run it until it quits producing and then bump the controller to the next temp. It might work if you run multiple batches and get the procedure down pat for your still and altitude. My controller set on the lowest setting will increase temp gradually over the course of a couple hours and top off at 206° before I have to turn it up. The progression through the cuts is pretty slow and easy to separate.
I don't drink alcohol, I drink distilled spirits.
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