Home Distiller

I have wanted to experiment with an electronical thermometer with a shut off so that I can set it to maintain the temperature in the still at just 172 deg. Doesn't it make sense that this will extract more of the "good stuff" than just letting it rip? I have a Still Spirits reflux/pot still set it pot still mode.

This came up recently when someone wanted to use a digital controller to maintain temp.

As I understand it, the components of the wash determine the temperature of the wash and also of the vapor. You Can't really control it by varying how much heat you are putting in the bottom. You set it going and it all starts to heat up... the methanol, the lower bp components, the ethanol, the water...The still will start to run when it gets to the boiling point of that whole mix... as the lower boiling point components like methanol begin to rise out of the mixture and get condensed and leave the still only the higher BP components are left. As this happens the temperature of the wash and the vapor will rise. This is how the seperations are made between the good cuts and the bad. Equilibrium is key to this process, so fooling around with the heat input won't get you anywhere. Most stills will run with a pretty wide range of power inputs anyhow.

generally: you can control the velocity, but you can't control the temperature.

From the very first three paragraphs of the parent site to this forum under the heading THEORY.


When you have a mixture of liquids, each with its own boiling point when pure, then the boiling point of the mix will lie somewhere in the middle, and this will depend on the relative concentrations of each liquid. Pure water boils at 100 deg C, and pure ethanol boils at 78.5 deg C, but a mixture of water and ethanol will boil at some point in between. The major point about distillation is that when a mixture like that boils, then the vapour given off is richer in the most volatile component, and when that vapour condenses then the resulting liquid has a lower boiling point than the mix it came from. By repeating this boiling and recondensation process up a column, using packing to hold the condensed liquid at each stage, you can separate the components more and more.

So if you have a mixture of liquids each with a different boiling point, then you heat the mixture, it will heat up until the new intermediate boiling point is reached. When you first start a distilling run, the packing in the column will be at room temperature, so vapour given off by the boiler condenses on the first cool packing it reaches. In condensing, the vapour gives up a lot of heat, and this warms that packing until the liquid on it boils again. However, this liquid is richer in volatiles than the mix in the boiler, so its boiling point is lower. When it does boil again, from the heat given off by more condensing vapour, what you get is even richer in those most volatile components. This process of boiling and condensing continues up the column and, because the condensed liquid is always getting richer in volatiles, the temperature gradually falls the higher you go. The temperature at any point is governed solely by the boiling point of that liquid mix, and any attempt to interfere with that process will disrupt the separation that Nature is carrying out automatically.

In contrast, the boiling point of the mix left in the boiler will very slowly start to rise as it is left with less and less of the most volatile components.

Grayson_Stewart wrote:From the very first three paragraphs of the parent site to this forum under the heading THEORY.

I have read that (and the rest of the site) over and over again, but sometimes the info on here is so drawn out, people like me need to hear it plain as day.
Set the heat input (turn on elements, turn on stove, etc)
and let it run until a spike in temp.
Right?
I have noticed this after FINALLY doing a test run, it will stay at a certain temp (5.5% beer, stayed at I think about 97c)

I have a long ways to go still, but I only ask to understand.

Despite what is being said here previously automatic temperature control does work and is beneficial. It is just that you can't pick a single temperature and say that is the temperature to be used when distilling as the most appropriate temperature will depend on the makeup of the wash.

However, as you say, for the majority of a distillation the temperature tends to stay stable only rising towards the end.

So IMHO the question is why don't we bother with automated temperature control? For most it a question of cost and for the purist it is not what distilling is about after all it is a hobby and if it is all automated, we wouldn't be able to tinker would we?

You see the simpliest level of temperature control is exactly what you talk about "a simmerstat or thermostat" the problem is they are only accurate to between 2 and 5 degrees C. This is not accurate enough for distilling as it would create huge temperature variations.

The next level up uses two elements and a Triac controller on both elements, which is in turn hooked up to an electronic temperature heat sensor at the top of the column. The primary element needs to be set at a temperature that is slightly too low, with the secondary element then adjusted via the Triac for the required temperature. In this way the temperature can be kept stable. You then also have the bonus that you can use both elements on full for a quick start up.

The most sophisticated method uses a PID (Proportional Integral Derivative) controller but as the cost is typically out of the reach of the amateur, lets just say it provides very presice temperature control and is used by scientific establishments when temperature control is critical.

But as I said at the beginning, that would take all the fun out of it, after all we need to do something as we sit by our still Hic .... Hic .... Hic

Using a thermometer to automate the reflux ratio might work, but the "vary the heat method " will be near to useless.

Unless done on a comercial (Grand) scale, this RR automation might not be worthwile, but it might be posible.

Hackers wrote:So IMHO the question is why don't we bother with automated temperature control?

And the answer is...the temperature is already automatically controlled by the composition of the vapours at the head.

As the concentration of ethanol/water vapours at the head changes, then the temp rises. To counteract this, you increase reflux ratio, which returns more liquid for reboiling and further processing (separation). This brings the purity back to where it was, but reduces the takeoff stream. There's always a tradeoff.

Now, if you introduce you electronic automation, when the concentration of vapours changes, your automatic switch will shut off the heat. So what happens? No more vapours.

Now this may be a way of separating the tails in a carefully controlled distilling environment (no ambient temp fluctuations through breezes etc.), but it won't work if there are minor fluctuations (common). The distilling action in the column will stop momentarily, and the liquid holding up on the packing will dump. That's not good. It will also separate most of the ethanol and leave it in the boiler. I don't think anyone will appreciate only getting 1 or 2 litres of product from a 20 or 30 litre run.

If you really want to automatically separate tails, build Riku's ARC setup.

.

Hackers, ya don't understand the physics behind distillation.

The temp of the vapor isn't driven by the heat added to the system... it's driven by the composition of the liquid in the boiler.

its true that the temp is controlled by the chemicals in the boiler but if you want a nice stable reflux with a stead EVEN flow of vapour than a constant heat is required, a heat, off, heat, off will make surges of vapour up the column. wrecking the equilibrium you are after. but a PID controller is WAY over the top, even a triac controller, give me good old gas or if i had to go elec it would be a variac all the way

theholymackerel wrote:Hackers, ya don't understand the physics behind distillation.

The temp of the vapor isn't driven by the heat added to the system... it's driven by the composition of the liquid in the boiler.

Rather than disagree with you, let me put it this way. As the composition of the liquid in the boiler changes, you need to either adjust the temperature or the reflux - correct.

So if you automate the control of the temperature to apply the correct amount of heat to keep the temperature constant then low and behold you have compensated for the composition of the liquid in the boiler - must be magic or maybe I do understand

hackers I don't get what your saying... Why do you need to adjust the power input or reflux?

Do you have a still with that control mechanism you describe?

" So if you automate the control of the temperature to apply the correct amount of heat to keep the temperature constant then"... what? why?

yes sir, Mr. Hackers. I wanna know.

Rez

The answer to the question, "Do I have a still like the one I describe?", is "YES, absolutely" and it works just as described. I can set it and forget it.

I have a Triac Controller with a modification to allow it to control one of my two heat sources with dual heat/wattage controllers. What happens is I have it set so it will heat up the wash to 78 degrees C at a high setting and then automatically reduce the power as it approaches 78 degrees.

A low voltage temperature probe (Type K) is inserted into the top of my Reflux Column and connected to the temperature controller. This temperature controller is set at 78 degrees C and is connected via a relay. The first element (1500W) is adjusted so that it heats up the still in conjunction with the main running element (1000W) both on full power. When the temperature reaches 70 degrees the first element turns off. The main running element is set via circuit A to cycle at 78 degrees, the second circuit is set to cylce slightly lower at 75 degrees.

In this way the temperature will cycle the High and Low Indicator Lights alternately, maintaining the correct temperature.

By using a sensitive and accurate temperature controller (in my case a Triac BTB 16-400) I get very close to the performance of a PID at a fraction of the cost.

I also have it set that when the temperature reaches 85 deegrees C it automatically cuts the power. Because of the design of my condensor, I have no risk of creating a vacuum and therefore can go out, go to sleep or simply watch the rugby while it does its thing.

I would be more than happy to post a schematic of my setup but as you need to be appropriately qualified to mess with this sort of thing I won't post constructional details. If anyone is interested just ask.

Thanks for doubting me.

[Hackers wrote]
The answer to the question, "Do I have a still like the one I describe?", is "YES, absolutely" and it works just as described. I can set it and forget it.

I have a Triac Controller with a modification to allow it to control one of my two heat sources with dual heat/wattage controllers. What happens is I have it set so it will heat up the wash to 78 degrees C at a high setting and then automatically reduce the power as it approaches 78 degrees.

A low voltage temperature probe (Type K) is inserted into the top of my Reflux Column and connected to the temperature controller.


[Harry says]
Well that's the problem right there. The thing is NOT a 'temperature controller', it's a "Power Controller". You said so yourself, "automatically reduce the power". One of the biggest problems we have in this hobby is people not calling items or procedures by their correct names. Hence all the confusion.




[Hackers wrote]
This temperature controller is set at 78 degrees C


[Harry says]
No, the 'Power Controller' is set to 'trip' @ 78 degC.


[Hackers wrote]
and is connected via a relay. The first element (1500W) is adjusted so that it heats up the still in conjunction with the main running element (1000W) both on full power. When the temperature reaches 70 degrees the first element turns off. The main running element is set via circuit A to cycle at 78 degrees, the second circuit is set to cylce slightly lower at 75 degrees.

In this way the temperature will cycle the High and Low Indicator Lights alternately, maintaining the correct temperature.


[Harry says]
No, it's maintaining the correct amount of power input to hold a particular temperature. There's a big difference.


[Hackers wrote]
By using a sensitive and accurate temperature controller (in my case a Triac BTB 16-400) I get very close to the performance of a PID at a fraction of the cost.

[Harry says]
Again, it's not a temp controller (I don't care what the manufacturers call it). It's a power controller. It regulates the quantity of power input to a process in a given timeframe.

[Hackers wrote]
I also have it set that when the temperature reaches 85 deegrees C it automatically cuts the power.


[Harry says]
Ya see? Even you agree it's the 'power' being controlled, not the temp.


[Hackers wrote]
Because of the design of my condensor, I have no risk of creating a vacuum and therefore can go out, go to sleep or simply watch the rugby while it does its thing.


[Harry says]
Yep. It can be done, but it's not wise to leave processing machinery unattended, regardless of how many safety/monitoring procedures you have in place. Just ask the folk at three mile island & Chernobyl. Besides, while ever there are those in this hobby who insist on doing this (flaunting safety issues), there's very little chance of our hobby EVER being granted legit status by legislators. Cowboy operators spoil it for everyone.


[Hackers wrote]
I would be more than happy to post a schematic of my setup but as you need to be appropriately qualified to mess with this sort of thing I won't post constructional details. If anyone is interested just ask.

[Harry says]
Post away. There's enough of us here who are professionals in the trades to sort it right quick.

[Hackers wrote]
Thanks for doubting me.

[Harry says]
You're welcome.

.

What a WHALLY - after all what comes first the chicken or the egg!!!

You control the temperature by controlling the power. You use the power to control the temperature. Get a life and understand that sermantics don't matter!!!!

In simple terms you have two variables and with that I am creating one constant.

Variable One: Power input, I don't care and don't directly control how much, I just need some.

Variable Two: A wash, I don't care and don't try to control its makeup (for the purpose of this argument)

and I'm using them to create One Constant - Temperature

Therefore I would say I'm looking to control temperature (at the still head, NOT in the wash).



The bottom line is that automation DOES WORK !!!

So where's the schematic?

Hackers wrote:

.....and therefore can go out, go to sleep or simply watch the rugby while it does its thing.

I'd rather watch the still going drip, drip, drip, than watch thugby.

Hackers, there is a big difference, its not just semantics...You have automated the power supply on your still. Thats great, nobody is knocking you for that. But your setup does not accomplish the goal as stated in the original post. Your setup does not control the temperature it controls a couple of setpoints turning the power down and off. Its hard to tell from your description, but if it also cycles the elements off and on during a run then that is not beneficial. It may work, but its not ideal. And it has no effect on the temperature at the condensor. it only reacts to the temperature.

so yes, automation does work. But it doesn't work to control the temperature at the condensor. And as hard to grasp as the concept can be, you can't control the temperature by controling the power input.

(geez, hackers, if Harry and theholymackeral are trying to tell you something, you might wanna listen... )

cant say ive got as much practical experience as Harry and theholymackeral but i do understand the physics concept

there is a huge difference between temperature and heat (power input). heat is the energy that is going into the system. eg. if using a 2000W element, that is 2000J of heat energy delivered every second. a certain amount of heat energy is required to heat the wash by a number of degrees and hence temp can be altered by power input. this works up to boiling point, when instead of continuing to raise the temp of the wash, the heat enegry is put into vaporising the liquid (it requires energy to change state to gas), so changing power input from then on will only change the amount of energy available for vaporisation and hence the amount of vapor leaving the boiler, not changing the temp at all.

the temp will start to rise by its own devices as the ethanol is boiled off and the boiling point changes, not from a change in power input

hope that summarises it

This is funny. We have yet no idea of what type of still head is in question and still people are generalizing that thermostats won't work in stills. As Harry said it's largely a question of terminology, but there are certain cases and still head types where thermostat's can be employed succesfully. From what I've read it sounds like we have a constant cooling CM head here and that's one case where thermostat controll of heating element can be employed.

I've studied this thing and built well working thermostat controlled LM and VM systems, but they require 0.1C accuracy for the thermostat and quite a lot of other tricks. The bottom line is, we still don't know what still head Hacker has so it's kind of a moot point to say that his setup won't work.

And yes, in GENERAL thermostats won't work with reflux stills, but there are special cases where they can be employed succesfully. It's all about understanding how the still in question functions and employing appropriate controll methods.

Cheers, Riku

Riku, it sounds like Hackers still does work correctly. The notion that you can control the vapor temp by varying the energy input is where I'm getting lost. Whether its a thermostat or a person with his hand on the gas valve makes no difference. The vapor temp is a function of its components.

I'd love details on the constant cooling CM head. Seems to my layman mind that a thermostat that controlled the reflux rate could be used to increase purity. That may need its own topic...

junkyard dawg wrote:Riku, it sounds like Hackers still does work correctly. The notion that you can control the vapor temp by varying the energy input is where I'm getting lost. Whether its a thermostat or a person with his hand on the gas valve makes no difference. The vapor temp is a function of its components.

I'd love details on the constant cooling CM head. Seems to my layman mind that a thermostat that controlled the reflux rate could be used to increase purity. That may need its own topic...

The point here is to controll the amount of vapor generated. With constant cooling effect CM system we controll the amount of vapor. When we increase the effect we increase the amount of vapor and they will pass the reflux condenser and are removed as product. By decreasing the effect the vapor amount is decreased and we are back in full reflux mode. The temperature can be used as an indicator of when to increase/decrease vapor generation. See the control logic here?

Cheers, Riku

Now that's a neat trick, newsgroup software that allows for later editing. Must be made for politicians. They like moving the goalposts also.

I'll dis the WHALLY remark. Takes more'n that to push My buttons.
Anyways, back to the matter at hand ...

In simple terms you have two variables and with that I am creating one constant.

Variable One: Power input, I don't care and don't directly control how much, I just need some.

Variable Two: A wash, I don't care and don't try to control its makeup (for the purpose of this argument)

and I'm using them to create One Constant - Temperature

Therefore I would say I'm looking to control temperature (at the still head, NOT in the wash).

To what end purpose? In simply terms, why do you want to control temperature at the still head?

Hi, this is my first post here. I've been lurkin around here for quite a while though.
And this thing wih the thermostate made me respond. I use a thermostate (0.1 C accuracy) for my CM ARC reflux which works excellent. I get 9-10 l of oh so pure 95.6% from three 25 l, stripped turbo 6 kg sugar mashes. My CM construction consists of a 30 l boiler, 1.5 m, 2 inch column filled with amphora scrubbers and with an air cooled 1 meter reflux convector. The convector is cooled by 11 "PC fans". Five of them run continousely and six are triggered by a thermostate, sensor 0.9 m from the top of the column. When the temp rises, the thermostate reacts and the fans give full reflux. I have to bleed the heads out but after that it's a piece of cake.

Having the sensor in the boiler is useless. You need to react on the vapor temp, but you might be able to control the boiler heating and thus the vapor speed with it as well, given you have an enough accurate thermostate. Only experiments can tell.

For those that are interested here are the schema diagrams of my Triac Temperature Controller.

First the basic Schema:



Next the modifications:



and lastly the key to the diagrams:



The bottom line is it works, regardless of whether you fellas think it shouldn't, it does and reliably helps produce 3.5L of 92% from a 25L wash. All I'm using is a stock standard Eurostill 30 with standard 2" reflux column. I have used it almost every week for the last three and a half years without a hitch and often get complimented that what I produce tastes better than the commercial equivilent.

If you want to know more I suggest you get hold of the book "Moonshine Made Simple and Still Makers Manual" - The schemas are reproduced for there as that was the basis for my design.

I do see the control logic. And Vinifera's system is beautiful... I can see how controlling the reflux ratio will work to increase the "good stuff"

But, I still don't see how this is true...

"So if you automate the control of the temperature to apply the correct amount of heat to keep the temperature constant then low and behold you have compensated for the composition of the liquid in the boiler - must be magic or maybe I do understand Exclamation Laughing"

In this system the control is over the composition of the vapor at the still head. In my mind, the 'amount of heat' is irrelevant as long as the still is operating in its range of velocities... Clearly controlling the reflux will change the temp at the head in predictable ways, but not the heat input.


so, Hackers, I'm not looking for an arguement... I want to understand. I have no doubt your still works. But the reasons that you give for how it works still don't make sense. no offense intended... automating control of reflux...I like it, but the heat...I don't get. Straighten me out if I'm wrong. Is this what your design does? That page of a book doesn't mean much to me... not in the trades... Maybe we are getting lost in translation....

Like I said before, it's either good for cutting off tails, or adjusting the reflux to a higher ratio as the alcohol gets less & less. For that it works, as I also said before. Seems to me to be a high-tech solution to a low-tech problem. A quarter-turn on a needle valve will accomplish the same thing.

What I Do know is...it does NOT control temperature...the temperature triggers IT.

And I repeat my question to Hackers...

To what end purpose? In simply terms, why do you want to control temperature at the still head?

If you say it's to govern or improve purity, then it won't happen, because the moment the head temp goes over the trip setting, distilling will stop, because you cut the power. Then when the temp reads lower, it trips the power back on, restarting the distilling. IOW, it's cycling, and that's why your product can't get to 95.6%. The few seconds it takes to cut in & out destroys the distilling action in the packing, and separation is not complete. You would do well to actually watch distilling in action in a borosilicate glass column filled with mesh. It's a two-way process.

However the SAME setup hooked up to a metering valve (not the heating elements), to adjust the reflux vs product takeoff ratio, would certainly achieve better purity. But like I said, so would a quarter turn of a needle valve.

But I guess when you're a hammer, everything's a nail.

I can easily see how usin' temp to controll reflux can be a good idea.

I'm just havin' trouble seein' how usin' temp to controll power input to the system is good for a column still. It seems to me that alterin' the power in any way will unbalance the carefully created equilibrium inside the column. This can't be good.

Please explain to me what I'm missin' here.

An on-off power control is what's bad here. If you setup a continuously variable power control (and control it slowly) it should work quite well. The idea of having a reflux condenser with a fixed cooling capacity is a new idea to me. Seems like it should work quite well if you have fine grained adjustments to your input power. Basically you would be controlling the reflux ratio (and indirectly controlling temperature and purity).

There may be some benefits here.
You can automatically run low reflux rates if you have a very tall column, or are re-running a stripped wash.
The setup automatically adjust for the optimal reflux ratio. No more messing with twitchy valves.
The setup decreases power as the run progresses (to increase the reflux ratio). The power keeps decreasing until the end of the run where you are putting in enough power just to match the reflux condenser (no output). The setup stops itself at the end of the run.

Some difficulties.
There is significant lag time between changing the power level and getting a change in reflux ratio (and a temperature change). If the control logic isn't setup properly you run the risk of building an oscillator. In other words, the control system will be unstable and you'll be wildly turning on and off the power. Obviously not a Good Thing.
A "standard" head may not work well. The reflux in the standard head is controlled by a valve. If the valve is set and not adjusted, the power control will adjust the reflux ratio. However at the end of the run when no amount of reflux will give a high purity output, the valve will still be taking output. The setup will not stop itself at the end of the run.
Continuously variable power control on AC isn't always easy. Use a variable transformer, or switch on/off at every zero-crossing of the AC (yes, it's on/off control, but it's so fast it smooths itself out).
If you use a temp sensor with 1 degree accuracy, then your "balance" point will need to be at least 1 degree below the lowest head temp your setup can achieve. Otherwise if the temp is at this lowest point you don't know if the power level is correct, or if you could be running gobs too much reflux and need to increase power. If you set this balance point too high your run will terminate early and leave ethanol in the boiler. A particular column may not be able to get 90 something % from a 2% wash.

Hackers, your setup may work fine, but you would probably benefit from having a better understanding of what's really going on. I think everyone jumped on your case because you were the 1000th person to come in and say "why don't you just put a thermostat on it". It's a bit more complicated than that