StillSmart

I have a thermowell in the 180° bend on top of my Still but it's only a 4mm hole, I think what we would really need for an automated run would be two temp probes, one on both the boiler and the vapour path.

Somehow you need to account for the fact that the boiling point increases as the alcohol content decreases, the boiler temperature is also proportional to the ABV of the vapour on a pot still, that's how the digital parrots calculate the ABV.

The trick would be to control the boiler to give a constant product output speed.

I normally just leave it to the ALVA and don't bother because when the boiler gets to a set temp the PID algorithm takes over from the amounts I entered at the start.

What I'll have to do when I do my next run is measure the temp of the boiler, the temp of the vapour and the ABV in the parrot all at the same points and post them as a chart to see if you can work anything out.

Probably next week end before my wash will be ready.

Hi VT

Here's a chart from the eParrot design thread over on VisionStills, our good but seldom seen friend YHB has made some great progress building his eParrot, anyway this chart shows the relationship between a mixture of water and ethanol when boiled, at any temperature you can determine the % ABV in the boiler and the % ABV of the vapour, it's a pretty useful bit of info.

That has been downloaded to look at again in the cold light of day.
Thanks.

Robert.

I have the grainfather and wonder if if this new controller would benefit spirit runs? I did my last spirit run set at 500w but although it worked OK most say it needs to be a bit higher 650w? wonder if this could be set to maintain that temp.

You will get a load of grief if you ask this on home distiller forum as they are bloody minded determined that power control of any sort is impossible and temperature control is similar.

I'd maintain that power and temperature control are not easy, probably not worth it but yet a load of extra fun to play with in our hobby after we get to understanding our still and what washes we like.

guest5234 wrote:I have the grainfather and wonder if if this new controller would benefit spirit runs? I did my last spirit run set at 500w but although it worked OK most say it needs to be a bit higher 650w? wonder if this could be set to maintain that temp.

Temperature needs to gradually increase to maintain output or a maintained temperature will lead to output reducing to zero. Nothing wrong with either, but one or other will happen.

I like vino-tinto's version (as I understand it) of output correctly reducing at each temperature level and then temperature increasing to next level for a pre-set amount of time.

Yeah the one that VT uses, you program your boiler charge's volume and ABV and what your collection rate is, from those factors it will either use a look up table or calculate a boiler power curve over time.

It will use this increase the power to compensate to the rising boiling point and subsiquent drop in product output, in order to maintain the programmed product collection rate.

However it's not a fully automatic system, it only measures temperature, it doesn't know how much reflux your using (if any) and it doesn't measure your output collection rate, the calculated curve or table it uses will probably pretty accurately guess and give you the desired output for a pot still.

But if your also refluxing I'm guessing it will not be so accurate, there would need to be some way of programming a correction factor to account for the reflux.

Maybe there's a +/- option during the run to adjust the power until you get the output speed you want if it isn't correct, @vino-tinto how does it work with a reflux column.

Anavrin you're correct with your assumption, I have the ability to overide and ramp up the power at anytime during the run.

I have'nt as yet run the ALVA with my Boka, just my pot still. I am of the opinion that my Boka really needs a full 2Kw to climb the 1 metre of SPP and I don't think the ALVA will hack it on a lower boil.

I could make a shorter column using the same Boka top half, that might would work because when my T500 was packed with SPP I ran it as low as 1.2Kw. My only concern would be, will the ALVA running a low boil create enough pressure to climb say 50cm of SPP.

I know that you are running a different beast to my Very Silly Still, but it occurs to me that turning down your cooling would allow the boiler to push out the product at a lower boiler temp.
Or is this something that you wish to avoid, perhaps for faster speed of run?
Just asking as I had to run my still at 530 watts tonight to keep it slow enough,(above 90%) OK, a metre of SS scrubbies are not the same as a metre of SSP.
But I would like to know your methodology.

Robert.

Hi Robert

I don't think the cooling has any affect on the point the boiler charge boils at, that's determined by the composition of its contents, the efficiency of the packed section is controlled by the cooling of the reflux coil, you want lots of reflux to make it more efficient and get a higher ABV, but if it's too much and it over cools the top of the packed section, it becomes less efficient.

Running slow with low power is one way to ensure a good reflux return if the reflux cooling is not so good but it will take a very long time to collect your product.

The reflux coil can only condense a fraction of what you hit it with if you want some to pass though and be collected, in general

For a CM Still
More cooling water = More reflux, higher ABV and lower speed
Less cooling water = Less reflux, lower ABV and higher speed

For a VM or LM Still
Opening the valve = More speed, lower ABV and less Reflux
Closing the valve = Less speed, higher ABV and more Reflux

But you also have power to control, like you said, even 500w will boil a wash eventually given enough time but the speed will be slow as there won't be so much energy to create a lot of vapour.

That's why Vapour Speed is important, depending on the size of the column (width not so much height) there are ideal power levels to reach the ideal vapour speed, I believe the Ideal vapour speed is 22" per second ( although I can't find where I got that number from )

There's a vapour speed calculater on this page

http://homedistiller.org/calcs/rad14701

This should give an idea of what power to aim for, if you having to lower your power significantly, to keep the ABV high, then you have a problem with either poor column packing of not enough reflux return coming back down it.

the new controller has a manual power controller mode which will let you control the power output to the element in 5% increments, specifically for distilling. So if you set it to 70% you should get around 1.4kw.

I think what you would need to do to get it to work with reflux, in an automatic mode is to program one of the parameter differently, I think both the product output and boiler charge will not work for this but maybe by altering (frigging) the ABV value it could work.

Reflux will slow down the output as some distillate will be refluxed and not collected, the best way I can think of is if you used a VM column, let's say 2" diameter with a condensing coil at the top then a 1" pipe going to the liebig via a valve, with the valve half open it eqivelent to a 1/2" output.

I've used the above as an example as that's exactly as my VM setup works, half open gives a good clean neutral product output.

So let's talk numbers, 1/2" is one quarter of 2", but we are talking in terms of area so in this case 1/2 squared is 1/16th of 2 squared, so you will have a reflux ratio of 16/1

So if you increased the programmed ABV by multiplying it by 16, it should give the programmed output as if it was a potstill.

I've had a couple of beers tonight so please feel free to play with my maths or just call me a drunken idiot, but I believe this might just work.

Due to other life commitments and the fickle finger of fate, I have not contributed much recently. Things seem to be settling down and I would like to contribute when I can.

Which brings me to this thread and my thoughts.

What You Cannot Do.

You cannot control the temperature at which liquid boils, this statement holds good for any form of power controller, grainfather, PID etc etc. The only exception to this rule is made by carrying the boiler to the top of a mountain where the reduced air pressure will lower the boiling point of the liquid.

If anyone disputes this statement please fill your boiler with water and try and control the temperature at which water boils. Set the controller to 99 degrees and the water will never boil. Set the controller to 101 degrees and you will never reach that temperature, the water will reach 100 degrees, boil and evaporate not increase in temperature.

So why does the temperature of a boiling wash increase?
It only does that because the composition of the wash changes as some liquid evaporates. More alcohol evaporates than water, therefore the alcoholic strength of the wash reduces and the boiling point of the wash increases. If you increase the power then the alcohol evaporates more quickly and the boiling point also rises at a quicker rate.

The table shows the boiling point of various strengths of wash.

92.5625 11.0%
92.6250 10.9%
92.6875 10.8%
92.7500 10.7%
92.8125 10.5%
92.8750 10.4%
92.9375 10.3%
93.0000 10.2%
93.0625 10.1%

These values are extrapolated from the curves posted earlier and cannot be changed / controlled.


What You Can Do

You can

1) Increase the rate at which the wash boils.

Sometimes it is beneficial to have a rolling boil with minimum amount of vapour, other times it is advantageous to have a violent boil with lots of vapour.

Additionally the controller can be used to maximise power for heat up.

All of this can be achieved with a simple power controller, I have just finished making one it cost me £3.99 plus a couple of bits from my box of really useful bits. Anything else is not needed and the expense not justified. It is a different matter if you have an existing GF or PID for other purposes and are utilising it's functions at no additional cost, but is not worth spending the cash to try and control the boiler temperature.

2) Alter the rate at which the distillate is pulled off.

Speaks for itself.

3) Alter the amount of cooling to the reflux condenser.

This is where it gets fun.

By playing with the above 3 variables we can alter the reflux ratio which will directly alter the strength / quality / taste of the distillate.

The Reflux Ration is the ratio between the amount of distillate that is condensed & drawn off the still, and the amount that is condensed and sent back down the column.

100% Reflux Ratio - everything condensed and nothing drawn off.
90% Reflux Ratio - 10% drawn off 90% sent back down the column.
0% Reflux Ratio - everything condensed & drawn off with nothing being sent down the column for refluxing - ie a Pot Still.

LM & VM Stills

With these stills the Reflux Coil must condense all the vapour reaching it. Therefore there is no point in considering adjusting the cooling supply to these stills to achieve any form of control.

You are therefore limited to either adjusting the take off valves or adjusting the amount of heat to the boiler which will alter the amount of vapour reaching the reflux condenser.

CM Stills

With these stills the Reflux Coil needs to adjusted to allow part of the vapour to pass without condensation and part of the vapour to be condensed and returned to the column for further refluxing.

For these stills adjustment is limited to either adjusting the coolant supply to the reflux condenser or adjusting the amount of heat to the boiler to alter the amount of vapour passing the reflux condenser.


AUTOMATION / CONTROL

Consider how we control our stills now, with me and I know many others, the boiler heat is more or less a set and forget, with the likes of the T500 having no control available on this option. With my set up, I may increase the power rating once I have taken off the heads and perhaps once more before the tails come through. All other adjustments are with the product take off rate, fiddling with the needle valve on a LM takeoff or adjusting the needle valve on cooling supply line to the Reflux condenser on CM set-ups.

So perhaps you may want to consider putting the control on the valves rather than the power. Some people are playing with stepper motors on the needle or ball valves, These motors can give very small incremental & accurate movement when hooked up to some form of processor or computer and constantly adjust for %ABV / Vapour Temperature / Takeoff Rate.

Me - not interested in building a machine to adjust valves - I would rather do it myself. But there again perhaps I would be more inclined if my cooling supply was not very stable.

Just my thoughts and I have had bad ones before


Toodlepip

Nice post Brian, informative.
Should help some to a better understanding.
I am air cooled CM, so outside of most of it, but I am an oddball.
Bad thoughts? I have them all the time.
Merry xmas to you and yours.

Robert.