Why You Can't Control Temperature

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cayars
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Re: Why You Can't Control Temperature

Post by cayars »

One man's pain is another man's pleasure. If you know your ABV in the boiler then you can easily calculate your expected ABV out of the still (can look it up) at different boil temperatures. So if you run the same thing or nearly the same thing ever again and have notes you can dial in your cut points with a PID controller based on boiler temperature because you know that X temp produces Y% ABV out. You only need to change the temp this way a couple of times during the run which is not a big deal. Some people enjoy this control since they are basically just standing around anyway changing jars.

When you follow the same procedures for mashing and produce the same ferments you can easy find the cuts points you prefer based on ABV out of the still. Once you know your preference for whiskeys, rums, etc and how big/small a heads, heart, tails cuts you like or prefer it's not hard to dial this in based on temp. It's not rocket science or anything.

After a couple of runs you can fine tune this pretty well.
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Re: Why You Can't Control Temperature

Post by 6 Row Joe »

cayars wrote: Sun Nov 10, 2019 7:27 am One man's pain is another man's pleasure. If you know your ABV in the boiler then you can easily calculate your expected ABV out of the still (can look it up) at different boil temperatures. So if you run the same thing or nearly the same thing ever again and have notes you can dial in your cut points with a PID controller based on boiler temperature because you know that X temp produces Y% ABV out. You only need to change the temp this way a couple of times during the run which is not a big deal. Some people enjoy this control since they are basically just standing around anyway changing jars.

When you follow the same procedures for mashing and produce the same ferments you can easy find the cuts points you prefer based on ABV out of the still. Once you know your preference for whiskeys, rums, etc and how big/small a heads, heart, tails cuts you like or prefer it's not hard to dial this in based on temp. It's not rocket science or anything.

After a couple of runs you can fine tune this pretty well.
Do commercial distillery's run that way? I would imagine so.
Last edited by 6 Row Joe on Sun Nov 10, 2019 3:50 pm, edited 1 time in total.
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Re: Why You Can't Control Temperature

Post by NZChris »

cayars wrote: Sun Nov 10, 2019 5:19 amWhat 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).
This isn't done at distilling temperature, so is off topic. If using a PID for this, the thermowell should be in the liquid, not in the vapor path.
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Re: Why You Can't Control Temperature

Post by NZChris »

cayars wrote: Sun Nov 10, 2019 5:19 am 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.
This is monitoring the temperature and/or flow rate, not controlling the temperature. You don't need a PID for this.

You can make cuts using temperature without having a PID cause the production to grind to a halt. It's as simple as swapping the jar at a predetermined temperature, (I'm not saying that's a good idea either).

If you are using a PID so that you can run your still and make your cuts unattended you won't be too popular with the Safety Police around here.

Constantly having to raise a PID setpoint to keep the still producing at a desired rate is a very Mickey Mouse way of adjusting the heat input. A power controller lets you dial up how many Watts you need for the still to keep constantly producing. I doubt you will find any commercial pot distillers using anything that remotely resembles a PID to control heat input during distillation.
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Re: Why You Can't Control Temperature

Post by NZChris »

I don't know if all PIDs control the same way, but mine pulse. Pulsing isn't great in a pot still boiler, which is why newbies have trouble trying to distill on simmerstat controlled elements
The constant expansion and contraction from the pulsing is much tougher on elements than controlling the Voltage. I tried one to control the temperature in my smoker on Friday and the element failed after five hours. The usual controller has a wide temperature differential so doesn't switch anywhere near as often as the PID was.
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Re: Why You Can't Control Temperature

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NZChris wrote: Sun Nov 10, 2019 2:21 pm I don't know if all PIDs control the same way, but mine pulse. Pulsing isn't great in a pot still boiler, which is why newbies have trouble trying to distill on simmerstat controlled elements
The constant expansion and contraction from the pulsing is much tougher on elements than controlling the Voltage. I tried one to control the temperature in my smoker on Friday and the element failed after five hours. The usual controller has a wide temperature differential so doesn't switch anywhere near as often as the PID was.
Yes they are on/off but should stabilize within a few minutes. I like my variable controller. I turn it on high to 125° vapor temp and then to low and it steadily climbs to 205° or so over the course of a couple hours during the run. Just about a perfect drip, drip, spurt out of the spout.
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Re: Why You Can't Control Temperature

Post by cayars »

NZChris wrote: Sun Nov 10, 2019 1:45 pm This isn't done at distilling temperature, so is off topic. If using a PID for this, the thermowell should be in the liquid, not in the vapor path.
Sorry but these are done at distilling temperatures and this is pretty clear. The butter Rum things does it differently (on this forum) but could have been done at distilling temperatures as others due it this way. That was only mentioned by me to show that some people have found you can bring out flavors by manipulation of temp in the still as with controlling foaming especially with rye mashes.

I've been consistent in saying that the temperature is monitored in the boiler.
NZChris wrote: Sun Nov 10, 2019 1:46 pm This is monitoring the temperature and/or flow rate, not controlling the temperature. You don't need a PID for this.
I'm sorry but that's just trying to split hairs of things I've been very clear about trying to hang on this idea you can't control temperature. As already covered, temperature is a measurement and nothing more. You change the heat input IN SOME WAY to get the boiler to a specific temperature. Monitor boiler temp, adjust heat, monitor, adjust until it's at the temp desired. That is "temperature control" because you are targeting specific temperatures.

I agree you do not need a PID for this but you can use one to do it and it will and DOES work regardless of what many people around here say. Far to many people use them to say they don't work. They will quite effectively bring the boiler to the temperature dialed in. That's what they do when set up CORRECTLY. I've not advocated their use per say, only defended their use in certain situations. Cheap PIDs will require more hands on use. But if you are staying with your still as should always be done, is it a big deal to adjust a temperature setting and actively doing something vs just waiting to switch jars? That is a personal opinion each person would need to decide for themselves.

I'm not really hung up on the method of controlling the heat input (like a PID) but the concept of "temperature control" and it' use in running the still and producing more consistent runs. What ever control used needs to be designed properly into the system or the operator will constantly be fighting it and it will be worse then running the still manually.
If you are using a PID so that you can run your still and make your cuts unattended you won't be too popular with the Safety Police around here.
I'm sorry but I haven't seen any mention of safety issues in any way. You are reading into what's hasn't been said. Automated cuts vs Unattended cuts are different. Automated cuts are more like the compaction on a reflux still where you pull of heads, then adjust the still to move into hearts, then adjust and pull of tails. Similar concept for the pot still but of course will always have more smearing. Unattended is stupid and unsafe and let's leave it at that as no one here is advocating that in any way shape or form, certainly not me.
Constantly having to raise a PID setpoint to keep the still producing at a desired rate is a very Mickey Mouse way of adjusting the heat input. A power controller lets you dial up how many Watts you need for the still to keep constantly producing. I doubt you will find any commercial pot distillers using anything that remotely resembles a PID to control heat input during distillation.
If you actually had to CONSTANTLY adjust it then that could be a pain, but still might be the BEST way for some people. If you only need to make a few changes while you're waiting to switch jars anyway, it may not be a big deal to many people. If anything it would make sure the person stays with the still vs walking away which is a good thing. :)

Several commercial distilleries have and use PID controllers. PID controllers do not need to be simple devices and can be rather complex such as those from Omega and Watlow to name just two brands. They use a rather complex "approach" algorithms that can compensate for lag in systems and take out the need to "fine tune". You can interface with these PIDs and control them via computer over RS232, RS485 or Ethernet. You can use a computer and any computer language to control them as well. These run around $200 list.

One or two PIDs like these with some minimal programming language experience and you can build your own G-Still or I-Still like automation if you wanted. Of course there are much cheaper less complex PIDs available as well with external control that allow you to roll your own algorithms and just use the PID for control and not for it's algorithms. You can also forgo computer control and manually control them as well. Just depends on the GOAL of the system.

PIDs are not the only way. There are a few other ways to control system temperatures as well that can be easily controlled and tuned if that is the goal.
NZChris wrote: Sun Nov 10, 2019 2:21 pm I don't know if all PIDs control the same way, but mine pulse. Pulsing isn't great in a pot still boiler, which is why newbies have trouble trying to distill on simmerstat controlled elements
6 Row Joe wrote: Sun Nov 10, 2019 7:36 pm Yes they are on/off but should stabilize within a few minutes. I like my variable controller. I turn it on high to 125° vapor temp and then to low and it steadily climbs to 205° or so over the course of a couple hours during the run. Just about a perfect drip, drip, spurt out of the spout.
And there's your problem and why you guys don't like PIDs. PID stands for proportional-integral-derivative. Not every controller uses all three of these mathematical functions. Many processes can be handled to an acceptable level with just the proportional-integral terms. However, fine control, and especially overshoot avoidance, requires the addition of derivative control. If you're PID only uses P and not ID functions your outcome may be less than stellar as what you have isn't a "true" PID.

Another issue I see many have is not designing the system for the PID they have and try to shoe-horn it in. Even using cheap PIDs you want to design the system correctly. You likely wouldn't want a PID to control a single 5K element but instead a much smaller 500 watt or 1K element used for fine control while a bigger element is used to bring the system to rough temp. Both could be controlled. Then even using a cheap PID the temp change would be minimal and any "Pulsing" would be negligible. Think about it. If you wouldn't consider turning coolant flow completely on or off, then why would you turn heat completely on or off to control temps?

Use a better controller or design your system properly to use cheap controllers and results will be much better. But a proper PID can fully control a ball valve from completely open to fully closed and everywhere in between. It can control anything this way when designed properly.
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Re: Why You Can't Control Temperature

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cayars wrote: Mon Nov 11, 2019 3:14 am You change the heat input IN SOME WAY to get the boiler to a specific temperature. Monitor boiler temp, adjust heat, monitor, adjust until it's at the temp desired. That is "temperature control" because you are targeting specific temperatures.
This guy just doesn't get it :crazy:
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Re: Why You Can't Control Temperature

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Saltbush Bill wrote: Mon Nov 11, 2019 3:54 am
cayars wrote: Mon Nov 11, 2019 3:14 am...bla...bla...bla... "temperature control"...
This guy just doesn't get it :crazy:
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Re: Why You Can't Control Temperature

Post by emptyglass »

Heres my take.

Don't matter who you are. You can't change the temp that water boils at. Most of us know its 100c at sea level. Less at high altitude.

Ethanol boils at 76ish C.

While your ass points to the ground you cant change this.

What you can change is how much heat you put in (heat = energy, be it from wood, gas, coal, sun, wind, nuclear, or other)

The amount of energy you put in determines how much rate of evaporation you will create. And how much product you will collect in a given time.

Don't forget your condenser must be capable of removing the heat you put in.

There are many calculators on the net and here that correlate the temperature of your boiler. If you accept that Eth boils at 76c and water at 100c, its not hard to see that a mix of these two will always boil above 76c and less than 100c (as its not pure water)

From a typical UJ type wash I'll start collecting at about 96c. When its at 99c I know i'm pretty much done. And no, my boiler thermo is not calibrated past me boiling and ice bathing it

Some say boiler thermos are not needed and they are correct. But they are handy. They prove you cant control the temp, only the amount of vapour.

And they are handy to tell you what point of a run you are at. no matter the still head. but I digress....
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Re: Why You Can't Control Temperature

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Well said Emptyglass.
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Re: Why You Can't Control Temperature

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Totally agree you can't change what the pot/boiler will boil at as that is a function of the mixture of what's in the pot. You can however "know" what this will be within a degree or so (hobby level) based on the ABV of what is in the boiler. More so when you run exact same ferments back to back or when using highly accurate monitoring (commercial distiller level). Either when done correct will likely be better than you can do in real time, fresh off the still.

If you know the ABV of the boiler charge, you can know roughly (or specifically, depending on your equipment) what's going to come out of the still.
Image

So if you have a 10% ABV wash then it will boil around 93 C and will output at roughly 54% ABV. If using computer control this can be automated pretty easily via lookup tables or using the math from Raoult's law which is the foundation for this table. This can then be stepped down as the progress of the run progresses or better yet monitored the ABV of the boiler charge.

It's not hard at that point to understand how to work backward from your cut points and ABV out of the still, to control the input and when the cut points will change. You can thus monitor and control the temperature of the boiler via many different ways/devices.

As long as you can control the heat input (regardless of technology used) to get to a specific temperature then you can control things. Without playing with words or parsing them, you are controlling boiler temperature and controlling the ABV output and cut points.
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Re: Why You Can't Control Temperature

Post by emptyglass »

Your bang on cayars.
You got this shit nailed dude.

So if you have a 10% ABV wash then it will boil around 93 C and will output at roughly 54% ABV.

Don't think too hard about it. There is heaps of science but nothing matters like how it tastes for you. it pays to focus on that first
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Re: Why You Can't Control Temperature

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Let me just add without quoting posts that there is a world of difference between different PIDs (since much of this conversation seems to be around the hatred/dislike of them). Many devices that claim to be PIDs are not. They only function at the "P" level and not "ID" levels.

To give an analogy using cruise control on a car. A PID using only "P" will cycle the engine from idle to highest RPM to keep you at speed. It only knows 2 states (idle, full) and cycles between them. You can imagine what this would be like riding in a car using this type of cruise control with sudden acceleration followed by nothing, following by full engine then idle engine. It would not be pleasant.

Yet that is the type of PID controllers many of you guys use or have experience and base conclusions on. These device only really meet the "P" in PID but leave off the "I & D" functionality. It's like controlling a ball valve that is either open or closed with no incremental adjustment. If I had them I wouldn't like them either! Now use a proper and real PID controller that can incrementally open the ball valve at various point and results are vastly different!

A PID controller is NOT the correct choice for everyone. It's usually going to be the wrong choice for most people BUT it can be the perfect choice for some people. It depends on need and goals.

Can we stop concentration on PIDs? The thread was about temperature control and there are many other ways to control temperature than a PID successfully.
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Re: Why You Can't Control Temperature

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yeah, but your just running a still dude.

programming a 1980's VHS video recorder is harder
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Re: Why You Can't Control Temperature

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many folk here utilise reflux control via pid and temp feed back.
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Re: Why You Can't Control Temperature

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Semi-related thread on "Temperature & ABV Relationship Charts": viewtopic.php?f=1&t=10158 for anyone interested.
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Re: Why You Can't Control Temperature

Post by StillerBoy »

Well stated emptyglass and cayars.. I'm with you guys on this debate.. all still function from a temperature behavior..

Distillation is not rocket science.. but it become complex only because one fails to learn and understand the relation between energy input, boiler load abv, water cooling rate, and take of rate.. in other words vapour behavior..

Once that's understood, it doesn't matter was still configuration you use, you will be able run it and get the results you want..

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Re: Why You Can't Control Temperature

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StillerBoy wrote: Mon Nov 11, 2019 8:05 am Well stated emptyglass and cayars.. I'm with you guys on this debate.. all still function from a temperature behavior..

Distillation is not rocket science.. but it become complex only because one fails to learn and understand the relation between energy input, boiler load abv, water cooling rate, and take of rate.. in other words vapour behavior..

Once that's understood, it doesn't matter was still configuration you use, you will be able run it and get the results you want..

Mars
Yes, I helped a newbie that got this for a wedding gift. He has studied a bit and was monitoring all the temp gauges while I was feeling the column temp with my hand and suggesting turning down the heat when the output went from a stream to vapor during the run. He still was concentrating on the temps and I was concentrating on the output. I'm sure he thought my seat of the pants approach was pretty crude but his charts of temps didn't work for his new rig and the UJ in the pot. This is quite a bit different than mine but still operates the same. With a little practice and some common sense, you should be able to run most pot stills without a temp gauge or PID controller in sight.
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Re: Why You Can't Control Temperature

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6 row.. If you start from the point, that people have a hard time with relating to words and their meanings, then reading or talking are just that, and nothing more unless the instruction are put to test at that moment in time..

So I start by showing a new comer to the hobby by boiling a pot of water with a thermometer on the stove, and make him see the relation between heat input and vapour reaction, to which he can now get a visual idea of what is happen inside a close vessel that we call a boiler.. and from that activity he can relate to was is happening in distillation..

That is the major problem with new comers to the hobby, they have no clue what vapours are and what they do within a column, and that apply a cross the board no matter what still heads is used..

Mars
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Re: Why You Can't Control Temperature

Post by cayars »

6 Row Joe, that still might make me get married again if I knew it was a present and could ditch the girl and keep the still down the road.
Well, not really, but that's a great pot still to be proud of and should perform really well! A computer controlled reflux still might motivate me however. :)

You did right by feeling the flow of heat up the column to the condenser. Pot stills are easy to run by your senses like this. You manually/instinctively knew to change the heat applied based on what you felt (temperature monitored). The same thing you did manually/intuitively (from experience) can be automated as well rather easily.

The physics of how this all works isn't rocket science, and I'm sure if he measured the ABV correctly and the boiling temp (in the boiler) it would be pretty spot on. From that pic, there is no temp gauge in the pot itself so there is no way to monitor the boiler temp based on ABV so this is an apples to oranges comparison to what I've talked about or possibly advocate. Trying to run a pot still by column temp is going to be an exercise that will likely fail on multiple levels.

BTW, 6 Row Joe, I love your tag line:
"I don't drink alcohol, I drink distilled spirits.
Therefore I'm not a alcoholic, I'm spiritual."

I've used your "spiritualist" line on friends/family and they love it. Such a great/original tag line!

PS Mars posted while I was typing this but couldn't agree more with what he said. Leaning the dynamics of what is going on in general is key.
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Re: Why You Can't Control Temperature

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I blame 6th grade at school for all this .
I cringe each time I hear the science teachers doing distillation as part of the separation substances topic .
“ alcohol boils at 78.3°C they say , water boils at 100°C , you can separate them by temperature “

Then then do a demo with a glass distilling apparatus with a thermometer in the top . I had one teacher throw the thermometer at me telling it was broken because it was reading 90°C when he thought it should have been 78.3°C .
What hope do the kids have

That same miss information plagued me when I first started this hobby as it has many many more . It takes a while to come to grips with this myth and move on .
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Re: Why You Can't Control Temperature

Post by cayars »

That's pretty funny Yummyrum.

Maybe send one of these charts to your old teacher.
Image
Image

Maybe then he'll understand the relationship of boiling point to alcohol content. :)
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Re: Why You Can't Control Temperature

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cayars wrote: Mon Nov 11, 2019 3:14 amSeveral commercial distilleries have and use PID controllers.
I'll bet they do too, as there are places in a distillery where they are useful, but I'll also bet that they are not using them to control the heat input to the boiler by reading a temperature somewhere in the boiler like you are telling us they do.
cayars wrote: Mon Nov 11, 2019 7:29 amCan we stop concentration on PIDs? The thread was about temperature control and there are many other ways to control temperature than a PID successfully.
You brought them up as a control option and are the one who claims they work.

What a PID controls is temperature, not boiling point, so they are excellent tools for that purpose, but when you set a PID a target temperature in a pot still, the PID decreases the heat input to the boiler as the constantly rising boiling point of the charge approaches the set point. What you have controlled is the heat input, not the temperature. It doesn't make any difference what type of PID it is, or how much you spent on it, it will only ever interfere with the smooth operation of a pot still.
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Re: Why You Can't Control Temperature

Post by Hillbilly Popstar »

Cayars, in you example of a 10% abv boiler charge, in which you predicted the temp and output,
How do you account for the varrying amounts of methanol and acetone and fusel oils (among other things)? You cant. Unless you send a sample of every ferment off to a lab to have it analyzed, what you've proposed just wont work in the real world.

Furthernore...
When I charge my still I can either do a spirit run or a stripping run. Either way, I get the same volume of the same products, over the same range of temps. Distillate might start coming over at around 80*f and the run is done around 202*f.
If I do this as a stripping run, I apply more heat. The result is more smearing but a quicker run.
If I do this as a spirit run, I apply less heat and the result is less smearing and a longer run.
But either way the temps dont change. The run still goes from 80*-202*. Only things that is changing with my energy input is the amount of time it takes to do the run and how mu h smearing takes place.

Please explain how those temps fail to change at all based on your theories.
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Re: Why You Can't Control Temperature

Post by NZChris »

cayars wrote: Mon Nov 11, 2019 3:14 am Think about it. If you wouldn't consider turning coolant flow completely on or off, then why would you turn heat completely on or off to control temps?
I do that with all of my pot still condensers :D
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Re: Why You Can't Control Temperature

Post by Hillbilly Popstar »

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acfixer69
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Re: Why You Can't Control Temperature

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PID's can do much more then control temperature. For that you only need a thermostat. A PID has a looping that notes the rate of change and the widest range of difference. With that data it varies the amount of power applied to limit the over shooting and still maintain a steady temperature. I'm a old timer and did this with pneumatic controllers. But have done many with Electronic Digital controls, all of them can be overrode and set to a manual that can be set to a power input that is selective and doesn't look at the temperature at all. All that said WE don't control the boiling temp the wash ABV does so WE set the rate of the boil. This may help.....

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Re: Why You Can't Control Temperature

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acfixer69 wrote: Mon Nov 11, 2019 5:17 pm All that said WE don't control the boiling temp the wash ABV does so WE set the rate of the boil. This may help.....
In agreement with the statement, but it is still temperature related..

Rate of the boil = input energy + boiler load ABV = which generates a temperature level which in turn generates an evaporation temperature.. (as the temperature of the boiler load will always be different than the temperature of the evaporation temperature until they become equal)..

So.. The rate of energy input is just a means to generate an evaporation temperature and therefore temperature driven..

In a pot mode, if one leaves the energy input at the same level through out the run, as set at the start, the output flow will almost come to a stop, and it is the same behavior in a flute when the first plate dries out..

Reason.. the evaporation level of the ABV is depleted, therefore temperature related..

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acfixer69
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Re: Why You Can't Control Temperature

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In a pot mode, if one leaves the energy input at the same level through out the run, as set at the start, the output flow will almost come to a stop, and it is the same behavior in a flute when the first plate dries out..

Reason.. the evaporation level of the ABV is depleted, therefore temperature related..

Of course temp related that is why I pointed that out but in a pot still that is not the same as a plated still I can send water back to the still and change the boil point and repeat over.........
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