PID Controlled Solenoid Takeoff Valve

[gatetwelve]

Hey all, this is my first post. So, if I made a glaringly obvious mistake in my logic, please, be kind.

I know that the use of PIDs are generally frowned upon for pretty much any application for distilling. But I'm putting together a new still, and got to thinking about what I thought might be a good application for one. In a reflux still capable of being under 100% reflux, could one use a PID to control the takeoff of condensate? When vapor temperature at the head reaches an appropriate level set on the PID (say, 78.2C), the PID would open the takeoff solenoid. Due to takeoff occurring causing decreased reflux ratio, vapor temperatures rise, and upon reaching the set "unacceptable" level (79C/80C), the solenoid is closed, sending the still back into full reflux until vapor purity/temperature reaches the acceptable set-point to re-open the solenoid.

Can anyone point out something that might throw a wrench in this? Other thoughts?

[MuleKicker]

Welcome man. Walking wolf will be here any minute to scold you into going to the welcome center to introduce yerself first. He'll give ya the whole bar room sceneario and what not. Dont worry, hes only pokin fun.
I have been workin on such a concept myself. One to turn cooling water on when head temp rises. I dont think youll want to have it open a distillate valve cause A: you want to run in full reflux fer a while to equilize, B: You dont just want to open a valve, you need to tune it ( i know there are ways around it). Its not just that easy to do, you still need to be there to make cuts, which are not going to be exactly the same every time.
there are no problems with pid controllers when they are used proplerly. Mine has a % out put 4-20 MA which i have running a 4-20ma phase angle relay. If yer tryin to control heat with one by simply using the thermostat and on/off function, your right, there is a big prob with that.

If you could get a time function worked out where it opened the valve (that was pre tuned to only, say come out at a drip or 2 a sec) after say 2 hrs. or something, it would kinda work. You would still have to be there to babysit and make cuts. So if yer lookin at a auto pilot set and forget it still. No way.

As fer open/closin that valve when head temp fluctuates? No way. you want that temp to be steady, dont tease yer collumn by goin full reflux/no reflux. That wont work, and will deffinately effect your product. when conditions are right, you want to open yer valve, take off a little bit, not enough to effect your reflux flow enough to alter yer head temp. That will fuck everything up. Do some readin on reflux still operation. you will see. Equalibrium man... its a beautiful thing.

[gatetwelve]

Thanks for the welcome. I have a long habit of poor etiquette in not introducing myself in forums - can't explain why.

If you could get a time function worked out where it opened the valve (that was pre tuned to only, say come out at a drip or 2 a sec) after say 2 hrs. or something, it would kinda work. You would still have to be there to babysit and make cuts. So if yer lookin at a auto pilot set and forget it still. No way.

As fer open/closin that valve when head temp fluctuates? No way. you want that temp to be steady, dont tease yer collumn by goin full reflux/no reflux. That wont work, and will deffinately effect your product. when conditions are right, you want to open yer valve, take off a little bit, not enough to effect your reflux flow enough to alter yer head temp. That will fuck everything up. Do some readin on reflux still operation. you will see. Equalibrium man... its a beautiful thing.

Hmmm, so maybe I formed my post while the thought was still a bit immature. I definitely wouldn't suggest a fully open, fully closed solenoid, although that's what my post seems to indicate. I was actually thinking of a proportional solenoid valve driven in percent by a 5-15VDC or 0/4-20ma control signal, and set the PID to work with "slow" acting elements so that it would gradually step up to a fully open takeoff valve (if it ever even got that far).

I was imagining always keeping the reflux valve open to 100%, so that in the event the takeoff valve did, somehow, make it to 100% open, you should still be at ~50% reflux in worst case scenario. I see what you're saying about not wanting to be taking off so much distillate that it would cause any change to head temperature and kill equilibrium, though. I wonder if knocking reflux down to 50% would do this...?

I fully agree that this would not be an automation magic bullet, and that's definitely not what I was trying to suggest. Well over half of my fun comes from coming up with the concepts for, and the building of, the apparatuses for my hobbies - and I really, really love making basic control systems. You'd still have to perform cuts (thought this may cut down on the volume of the tails, it will not help as to when to make the cut), you'd have to get the still up to equilibrium for an acceptable time before powering on the PID, and you'd still have to watch/monitor the still for the duration of its run.

Thanks for the feedback.

[MuleKicker]

It sounds like you dont have alot of experience actually running a still. He is what you need to do. Build a still, and run it manually, until you get the hang of it. then start implementing your ideas. Its not that you have bad ideas. You just need to know what exactly to do with them. And that take time in this hobby. I was once in yer shoes. I wanted to over complicate and build a still to run itself, without truly knowing what I needed the still to do. Take your time.

[gatetwelve]

It sounds like you dont have alot of experience actually running a still. He is what you need to do. Build a still, and run it manually, until you get the hang of it. then start implementing your ideas. Its not that you have bad ideas. You just need to know what exactly to do with them. And that take time in this hobby. I was once in yer shoes. I wanted to over complicate and build a still to run itself, without truly knowing what I needed the still to do. Take your time.

No offense taken; you got the nail on the head. I built a still many years ago, but didn't have the time to exact anything on it. So this build would really be considered my first. I fully intend on running manually for quite some time, and was merely throwing an idea out.

[MuleKicker]

And Im not shooting down your idea. I have thought of it myself. But once you get there you will see. Easier said than done. Not impossible I might add.

[kiwistiller]

your first post comes quite close to what is known as a VM-E-ARC design. As I recall, a PID isn't ideal for them unless you disable a part of it. I'm not an expert though. If you're interested in automation, I'd recommend buying Riku's book, designing and building automatic stills, then looking over the advancements to the design in his forum. A lot of R&D has been done over the years, and it'll save you a large amount of legwork.

[manu de hanoi]

have a look at this :
http://homedistiller.org/forum/viewtopi ... =8&t=15532

he is really cheap, I wonder why he didnt get more feedback. I built one prototype myself, and I intended to sell for twice his price.

So, people interested in automation should really jump on his offer.

[gatetwelve]

Kiwi, thanks for the reply. I just read a little into what the book covers, and the principle is exactly what I was getting at (just way more in-depth, worded better, and has more knowledge behind it ): automatically controlling the reflux/takeoff rate based on the head temperature. Since this idea with the solenoids and partial automation was kind of extemporaneous, I don't know if I'll get a copy right now...maybe after I run manually for a while. At least now I've got a term to describe the idea I was after.

[Kentucky shinner]

What language are you guys talking in....LOL WTF is a PID valve...???

Mine has a % out put 4-20 MA which i have running a 4-20ma phase angle relay---No shit.... boy I feel stupid... \

Hell here in Kentucky were just glad to get a new pair of flip flops.... LOL and hope its not jail issued...

[gatetwelve]

lol Not a PID valve, but a proportional solenoid driven by the 0-20ma or 5-15VDC control signal from a PID. A high-price example would be: http://www.thevalveshop.com/menu/auto/burkert/6223.html (I dunno if exterior links are allowed...I'm sure I'll get hollered at if they aren't... ). Works in the same way phase angle relays, or SCRs work, but instead of outputting/regulating a voltage by varying percent, it opens the valve/solenoid by varying percents.

[rad14701]

Those valves are WAY too expensive to be trying to incorporate into our home distillation equipment... The cheapest being $406 and requiring a $235 power supply... We aren't trying to a man on the moon here... There is good reason why we practice the KISS concept around here... We aren't in a commercial enterprise where we will readily recoup our costs...

[gatetwelve]

Those valves are WAY too expensive to be trying to incorporate into our home distillation equipment... The cheapest being $406 and requiring a $235 power supply... We aren't trying to a man on the moon here... There is good reason why we practice the KISS concept around here... We aren't in a commercial enterprise where we will readily recoup our costs...

Like I said, that link was to the high-price, brand-new, Cadillac of valves. Depending on where you look, you can get them for under $50, and that power supply is their high-price optional accessory, and by no means necessary. I don't know about others, but I'm not getting into this hobby to save money. I've done AG beer brewing for a while, and I'm quite sure I've put more money into that than I've saved/will ever save. Building the apparatuses and control systems are the joys of my hobbies, second only to the product I get out them at the end. Hell, sometimes, the build for me is more fun than what I get...

[suspct]

Those valves are WAY too expensive to be trying to incorporate into our home distillation equipment... The cheapest being $406 and requiring a $235 power supply... We aren't trying to a man on the moon here... There is good reason why we practice the KISS concept around here... We aren't in a commercial enterprise where we will readily recoup our costs...

LOL Not if you work in a dairy factory!!!!

[ozone39]

A modulating ball valve has more control than a open/close solinoid. They are a slow open/close valve that can have the power cut to them when they are only partly open. Or you could use a zone valve off a heat system, BUT, they return to the close position when the power is cut by a the means of a slow closing spring.

zone valve:
http://www.google.com/products/catalog? ... CCYQ8wIwAA#" onclick="window.open(this.href);return false;" rel="nofollow

Three way modulating ball valve:
http://dticorp.com/catalog/honeywell-vb ... -3132.html" onclick="window.open(this.href);return false;" rel="nofollow

This guy (I belive) would work well, the direction of flow would either send the flow to the condenser or back to the storage tank. This would be if you ran a continuous running pump and had to divert flow to either or. If you are running tap water then a two way valve would work (open close)..
Just throwing it out there....

[rad14701]

ozine39, that would definitely be a more affordable option if it could maintain a somewhat accurate vapor temperature... Good find...

[ozone39]

PID??? I'd just use an aqua stat....way easier...and cheaper...

http://www.pexsupply.com/Aquastats-Well ... gwodVmdv1g" onclick="window.open(this.href);return false;" rel="nofollow

[MuleKicker]

those zone valves have rubber seals on the insides. Might mention that they may work great for cooling water, but dont try using them on any application that comes in contact with alcohol.

[rad14701]

I kinda think we're beating a dead horse considering how the OP hasn't even been back to these forums since Sun Aug 15, 2010... The stagnant topic was resurrected by suspct four months after a lapse in posts...

[MuleKicker]

Even if the OP dont care anymore, it is an interesting concept. Just maybe more to it than some folks think. I have been toying with the idea on my own for a while. Having the PID turn on cooling water when the collumn temp rises. My partner is into automation big time. He wants this thing to drive itself. I kinda like it, just for the challenge. You know how it goes, you get what your building just perfect. Then you want to do something else cuz it aint fun anymore.

"I want to do it, just to see if I can"

[olddog]

I have been toying with the idea on my own for a while. Having the PID turn on cooling water when the collumn temp rises

This was my thought for applying super fine control for a Flute dephlagmater.


OD

[rad14701]

I can see it now, olddog... You won't be happy until you get a Rube Goldberg award for flute design and control...

[Kentucky shinner]

sorry this post was in the wrong place so I moved it over to flute talk..
another brain fart.

[MuleKicker]

I have been toying with the idea on my own for a while. Having the PID turn on cooling water when the collumn temp rises

This was my thought for applying super fine control for a Flute dephlagmater.


OD

Now thats what Im talkin 'bout Use it as a thermostat of sorts. Dutycycle the valve more/less depending on the temp. Superfine Kickass Control. That wouldnt be no regular magic flute... More like a kick ass Jazz flute.... Like Jethro Tull.

[LWTCS]

Vendome Copper & Brass Works 30 Gallon

Search that on Youtube.

Figger'd you fellers seen that a good while ago . No?

[MuleKicker]

umm yeah..... kinda exactly....what.... I had uh... pictured.....(speachless)...

[Braz]

I probably shouldn't comment since I pretty much don't know what I'm talking about on this subject.

But, since it is kind of "brainstorming" anyway... Might it be possible to adapt an automotive heater control valve in some way? Some of them use a "stepper motor" to adjust the valve opening increments. It might be possible if you can figure out a control circuit to tell the stepper motor to step.

[The Baker]

Do we need an adjustable valve?

Or just a PRE-SET valve set to a very narrow temperature band?

I'm quite seriously asking what may well be a silly question
(I don't really understand exactly what the valve does...,
in fact there may be more than one possibility for temperature control valves, for example to control take-off temperature and maybe to control cooling water temperature...),
but a pre-set one would probably be FAR less expensive than an adjustable one...

[ozone39]

Well, with that said. If you really want heat control then install a frequency drive on a submersible pump with a temperature sensor controlling the freq. drive. Now you control the flow with the pump and eliminate the valving all together.... This is the standard in commercial heating and cooling systems. Due to the fact that technology has made frequency drives much cheaper..

[MuleKicker]

I don't really understand exactly what the valve does...,

the valve is controlling waterflow through the condenser. more water= colder condenser= more reflux.

Well, with that said. If you really want heat control then install a frequency drive on a submersible pump with a temperature sensor controlling the freq. drive. Now you control the flow with the pump and eliminate the valving all together.... This is the standard in commercial heating and cooling systems. Due to the fact that technology has made frequency drives much cheaper..

That is not a bad idea. Can you get a frequency drive with a digital read out/ multiple inputs outputs? Im not that familiar with them.