PID controller for initial warmup

[BarkAtTheMoonshine]

Someone smarter than me said something along the lines of "if you can imagine the worst case scenario, you have a poor imagination." Can someone help me imagine better?

I have a 1500W low density heating element in my 5 gallon boiler controlled with an SSR and a PID controller that I run in manual mode (100% till about 150, then drop it slowly till starting to produce, able to run at about 45%). I have a thermowell with Type K thermocouple in the side of the boiler for wash temperature.

My thought is that I could use the PID to set the temperature to 160 for initial warmup, then use the 30-45 minutes it takes to clean fermentation jugs and jars, prepare the next ferments, tidy up the shop, etc. Basically be in the same general vicinity as the still, but for all intents and purposes, the still is unattended. Once the still is up to 160, I'd switch the PID back over to manual and continue running with the usual full attention.

I know the torches and pitchforks come out with unattended stills, and for good reason as this hobby can generate some very dangerous conditions if the proper care is not taken. But for a submerged heater, hooked to a controller that sends the power to zero before any vapors form, what's the worst that can happen?

[OtisT]

Funny you mention this, as it came up in Buried in another thread earlier today. I think that is a perfect application for a PID controller. It adds a level of safety that you would not get without having the PID controller in place configured to shut down at a pre defined pre-boil temp.

I like a level of redundancy in my safety measures so if I had a PID controller tied to boiler temp, I would still set a timer to remind me things are getting close. That’s just me.

Otis

[BarkAtTheMoonshine]

...I would still set a timer to remind me things are getting close.

That's a great idea. Not to go off topic, but I've already used the PID for Shine0n's butter rum process with some pretty great results (heating to 135 for two hours the night before and letting it cool back down to ambient). I was surprised that I hadn't seen people using a PID for warmup, and was curious if there was something I was missing w.r.t. safety.

Could you please link to that thread? I'd love to read more.

[Desvio]

I'll be honest, running an SSR (DSPR1) for many years in know pretty close to when the first drops are coming out, and set my power at startup knowing it'll kick off in 20 or 60 min. Granted, most of the time I'm bottling beer, a previous run or cleaning/waxing a car or bike. I can also shut my system down with my cellphone because I put a Wemo Wifi controller inside my box.

[NZChris]

I've got a PID holding a boiler charge at 150F right now. After six days, I'll put a pot still head on it and run it with an SCR.

[OtisT]

Could you please link to that thread? I'd love to read more.

What I referred to is not really worth reading for details on using a PID. It just that earlier today someone was taking about a bad puke at first boil, and I simply said that if ever there was a use for a PID on a pot still it would be for warmup. Just a coincidence that you posted this later the same day. From the other responses you got it seems like they may be able to help you in the right direction.

Otis

[NZChris]

If it's anti-puke you're after, a thermocouple somewhere just below the goose neck can be used to switch something based on the height the puke has gone up the riser. My preference is to switch the power off to let the puke collapse, then restarting at lower Watts after a minute or two, keeping the Watts low until the foreshot has been taken. A latched relay can be used for this. I then move the thermocouple to the condenser outlet and set the latched relay to trigger a shutdown if there is any problem with the cooling water.

[BarkAtTheMoonshine]

I've got a PID holding a boiler charge at 150F right now. After six days, I'll put a pot still head on it and run it with an SCR.

Wow, that's a long time! What does that buy you?

[cayars]

Wow, that's a long time! What does that buy you?

A big electric bill. LOL sorry couldn't resist.
I'm quite curious as well.

[NZChris]

I've got a PID holding a boiler charge at 150F right now. After six days, I'll put a pot still head on it and run it with an SCR.

Wow, that's a long time! What does that buy you?

Rum esters for future blending.

It's well insulated, so the power used to hold it is minimal.

I'm holding today's first UJSSM strip at 150F by dialing up 300W, which is about how much this still loses to the shed at this time of year. No PID required, just turn the Watts down when the still head feels warm enough.

[BarkAtTheMoonshine]

Rum esters for future blending.

Interesting; looks like I've got some more reading to do now!

[NZChris]

Start here;
viewtopic.php?f=44&t=55301

[Tennessee_Spirits]

My controllers have grown more complex over my year and a half learning to make spirits. I started with a K-type thermocouple in a mighty mini 3 gallon at the still head. I found it oscillated in temperature and output, but provided adequate control if I used the stove top on low to medium settings and for warm up. I killed that stove top! Then I retired and moved and I'm using a garage and I got 100 amp panel installed and built a second controller for 240 volts. This time I added pulse width modulation in parallel with the PID's SSR so that if either are on the element is on. I run the PID on start up at 145F and it produces fore shots and the output stops. I remove the fore shots and set the PWM to about 15% and gradually bring it up. The oscillation stooped and the process became predictable and smooth.

[Birrofilo]

Yes, also, any thermostatic switch would work just as well (the STC-1000 or the InkBird ITC-308 that most homebrewers have in their setup). They are cheaper than a PID and you can use one you already have at home. There will be a little bit of oscillation around the set point maybe but that should not be critical for this application.

(You can avoid oscillation by reducing heat once when you are near the set point).

[NZChris]

I run the PID on start up at 145F and it produces fore shots and the output stops.

Most of us who run electric here remove the foreshot at our preferred set volumes, then carry on stripping, controlling the power to the elements with SCRs and the like throughout the entire run.

Where did you get the idea of using a PID to control a still element?

[NZChris]

The two STC-1000s I've tried to use at distilling temperatures have been unreliable, so if I do use them for this, it is to trip a latched relay to turn off the second element, leaving the main element on and controlled at about 300W. From then on, it's up to me to adjust the Watts to hold the temperature, which I seldom have to do.

I prefer to control the Watts, rather than having a thermostat or simmerstat switching the power on and off, as having low power constantly on prevents solids settling on the element where they may burn, plus extends the life of the element.

[Tennessee_Spirits]

I got the idea for building PID controllers from George Duncan of Barley and Hops. I used it for about 6 months with a build similar to his with fan and SSR in the larger portion of the box. In the lid I mounted the PID. The PID is especially good at getting the foreshots collected without an overshoot and puking. But I found that when I use the PID there is oscillation that no adjusting would completely stop. I tried tuning the PID and manually adjusting the proportion, integral and derivative settings. I had discovered that limited fix heat would smooth the still considerable. The oscillation is due to the thermal time constant of the system. I found a square wave generator on Amazon for $14 that outputs about a volt under the supply. I got a switch node power module for about $6 at 9-12 volts. The SSR only needs about 7 volts to trigger the optical coupler in it that in turn triggers the thyristor. I determined this with a bench power supply and got reliable triggering with the square wave generator. It is safe to parallel two of the same time SSR. Doing this means that the element will be pulsed by either trigger and it allows using PWM at the same time as the PID without panel switches. You just set the PWM for constant heat and the PID as a temperature control. This works great. The flow rate is constant and the output is higher because there is virtually no oscillation.

[Tennessee_Spirits]

Here are the build pictures of my combined PID and PWM controller. It is rated to 40 amps at 240 volts and does not need a neutral wire.

[Tennessee_Spirits]

I could only post one photo and it was the 120 volt unit that I also use as cooling control, but that is another topic. The only problem I've had has been with the yellow connectors and I got mash spill on the encoder that made it sticky for awhile.

[Saltbush Bill]

I got the idea for building PID controllers from George Duncan of Barley and Hops.

George really doesn't have any idea what hes doing , we get people here all of the time who have followed his instructions.
I'm sure others will be long to tell you about George and his theorys

[Tennessee_Spirits]

Here is the 240 volt build with two 40 amp SSR in parallel. One is for the PWM control and the other the PID.

[Tennessee_Spirits]

I wrote George and told him about the problems with PID control and he blew if off. At that point I'd already added PWM control to the unit and fixed the problem. The PID works fine at getting to 150 F and collecting the foreshots. It then sits there with base level of power from the PWM controller that I start about 10%. After that initial stabilization I inch the power until I get the flow rate desired. I agree with you largely about George Duncan, but nobody is perfect. Smooth control of distillation beats oscillation every time. Besides stopping the occasional puking the PWM modification doubled the rate of output by simply smoothing out the rate. I consider this a solved problem.

[Tennessee_Spirits]

I find the PID really useful for the boil kettle/hot liquor tank. In my set up it is the same 18 gallon kettle with 5500 watt heating element. I use PID for control of temperature. I use a PID with a RIMs heater during a 2 step mash. The first step is corn at 185 F and the PID does a nice job of holding this temperature. I use a second PID to control cooling. The mashing circuit includes a heat exchanger. So after the corn mashing I use the PID to lower the temperature to 150. It does this in about 15 minutes using cooling water from a hose.
This 120 vac valve was intended for a dishwasher and requires minimal current to open the valve. Power off it is closed by an internal spring. The second PID is set in the cooling mode and outputs to an outlet built into the controller.

[Birrofilo]

I see a PID as the "pause" button on a video player. The process is just stopped, but it can be a convenience.

One might decide to use a PID and raise the temperature a little bit at a time - instead of leaving a steady raise of vapour temp during collection - for a number of reasons: being able to collect registered mail, to take the children from school, to do some purchases (maybe you broke something that you want to re-buy soon) or to watch a foot-ball match, or to answer the phone, or to go to the bathroom with due calm. When the engagement has ended, you start again exactly from where you were beforehand.

Without a PID we have to program a stretch of time without football matches, postmans, children, purchases and phone-calls.

I don't plan to insert a PID in my setup but I find there is some kind of bigotry here regarding PIDs, everytime one mentions a PID there is without fail somebody arriving with the usual sermon "you cannot make the cuts by temperatures". PIDs are not necessarily used to make cuts by temperature, and if one wants to make cuts by temperature, he can do that without a PID.

[NZChris]

I see a PID as the "pause" button on a video player. The process is just stopped, but it can be a convenience.

One might decide to use a PID and raise the temperature a little bit at a time - instead of leaving a steady raise of vapour temp during collection - for a number of reasons: being able to collect registered mail, to take the children from school, to do some purchases (maybe you broke something that you want to re-buy soon) or to watch a foot-ball match, or to answer the phone, or to go to the bathroom with due calm. When the engagement has ended, you start again exactly from where you were beforehand.

Without a PID we have to program a stretch of time without football matches, postmans, children, purchases and phone-calls.

I don't plan to insert a PID in my setup but I find there is some kind of bigotry here regarding PIDs, everytime one mentions a PID there is without fail somebody arriving with the usual sermon "you cannot make the cuts by temperatures". PIDs are not necessarily used to make cuts by temperature, and if one wants to make cuts by temperature, he can do that without a PID.

Are you advocating running a still unattended?

[LWTCS]

I see a PID as the "pause" button on a video player. The process is just stopped, but it can be a convenience.then you'll crash the gradient. Not a big deal for those who don't care about making the highest quality finished product possible.

One might decide to use a PID and raise the temperature a little bit at a time - instead of leaving a steady raise of vapour temp during collection - for a number of reasons: being able to collect registered mail, to take the children from school, to do some purchases (maybe you broke something that you want to re-buy soon) or to watch a foot-ball match, or to answer the phone, or to go to the bathroom with due calm. When the engagement has ended, you start again exactly from where you were beforehand. this mind set is completely irresponsible. You'll soon find yourself being heavily moderated if you do indeed endorse this type of loose and sloppy planning

Without a PID we have to program a stretch of time without football matches, postmans, children, purchases and phone-calls. again, this kind of planning is not endorsed here. It is lazy and irresponsible.

I don't plan to insert a PID in my setup but I find there is some kind of bigotry here regarding PIDs, everytime one mentions a PID there is without fail somebody arriving with the usual sermon "you cannot make the cuts by temperatures". over simplification as well as false equivalence. Optimal operation and mastery of the art is what this forum promotes. PIDs have their place, but using a PID to apply heat to a distillation kettle is not optimal.
PIDs are not necessarily used to make cuts by temperature, and if one wants to make cuts by temperature, he can do that without a PID. You seem to debate for the sake of debate. You cherry pick your talking points with very little regard for practical application. All to do what?

[acfixer69]

Well said +1 Larry.

[Birrofilo]

I don't understand all this rage. I don't see problems in leaving the still unattended when you are in the other room (and check from time to time), or for a few minutes, or even for half an hour if the still is not producing. If you lower the temperature a couple degrees, you can leave it at there for days. Besides, the window must always be left open etc.

If you use a PID, the still will stop producing and you go back to the initial case of "initial warmup", that is you let the broth at a temperature where no alcoholic vapours are produced. Only that temperature level is now higher than before the distillation begun.

The dogmatic attitude in this forum is disappointing. If you "attend" at your still, you can always fall asleep, you can have a sudden problem, you can knock your head at a piece of furniture, you can skid on the floor and break a leg, you can faint, you can die. A PID going step by step will make the still innocuous even if the person attending it is not conscious any more. A PID used with small temperature steps and the operator is safer than the operator alone.

LWTCS You look for dangers where there are not, and I think you have some axe to grind regarding myself, and the sentiment is NOT reciprocated, because I believe in free exchange of opinions without some people patronising other users. You don't seem to be the person with whom it would be pleasant to drink a beer discussing matters. You talk with a hammer in your hand. I suggest you adopt a more friendly way of expressing your opinion, and frankly also a more friendly avatar, because you don't seem to be the person who is not afraid of exchanging opinion, or accepting dissent and contradiction. You should learn that people think in different ways and that there is no need to try to scare other forum participants with menacing avatars. That tells a lot about your way of seeing a forum, and yourself. I also think that you use your moderator "status" to just wage your personal little war against people who differ from you, and to protect yourself, somehow, from contradictions by other users; you seem to be afraid to be contradicted. You are shielding yourself, you have fears that you should work on. And now ban me if that makes you feel better, for life. I have a life outside fora, a life made of friendly exchanges.

[Birrofilo]

Are you advocating running a still unattended?

If with a PID at a temperature at which it does not produce, yes. You do the same. You said you kept your kettle warm with a PID, without boiling point, for 6 days! Where you there night and day? No, it would be idiotic. The still is not producing alcoholic vapour, and it cannot produce them if laws of physics hold.

This principle holds also during distillation. If you set your PID let's say half degree or 1 degree at a time, it will stop producing and you will be able to do something without hurry (also for 6 days).
If you are in the midst of the heart, you can just set the PID a degree or two below, check that production has stopped, do what you must do, and then resume again.

A PID can certainly be a convenience in any phase of distillation. You don't trust a manual regulation of your kettle (by manually regulating the wattage so that it is in equilibrium) to keep it for 6 days at a temperature below boiling because there is no feedback. A PID (or a thermostat) is necessary for safety and peace of mind. The same applies during the distillation process. You lower the temperature just a bit, the process is in pause, and then you resume it, all with great peace of mind.

[NZChris]

Holding a set temperature in a fast aging reactor is not running a still unattended, which is what you seem to be advocating.