Reflux Still Temperature Regulation

[gin.stiller]

I've just finished my first distillation and I have a few questions for everyone who has done this more than once. I'm mostly concerned about temperature regulation but I will describe everything I did and would welcome general comments.

Setup:
32 liter reflux still
40 inch column
column packed half with copper mesh and half ceramic rings
column insulated
1500 W hot plate
7000 ft above sea level
Room temperature approx 10 C
Cooling water is very cold
24 liter turbo yeast sugar wash
Trying to produce neutral spirits

I started heating the boiler and it was going quite slowly until I left the room. In about half an hour the temp went from 12 C to 80 C and steaming was blowing out the condenser quickly. It was condensing on my stainless steel table and I appeared to have lost quite a bit. For the next half an hour I spent frantically adjusting the hot plate and water flow rate. Temps were fluctuating between 34 C and 80 C. Eventually, I got it fairly stable but with the hot plate cycling the temp varied between 60-75 C. It took about 2 minutes to vary between these two temperatures.

Q1. What can I do to better regulate the temperature given my setup? Using propane is impractical for me.
Q2. Do I try to get my column into equilibrium? I know you want to with a fractionating still but can you do it with only a reflux still? If so, how do I do it?

Even though I apparently lost a lot, I disposed of the first 50 ml. I then collected the next 400 ml in 100 ml increments. These varied from 89 to 92% ABV and they all smelled a little like isopropyl alcohol. That first 400 ml I stored as heads. I then started collecting the body although the smell never changed.

Q3. Is the isopropyl smell normal?

In the next 11 hours I collected around 3 liters. Temperatures got as high as 79 C and some of that tested at 80% ABV. It seemed that some of the temperature variation then could be attributed to changes in water pressure at that tap.

Q4. Anyone know a good way to maintain constant water pressure?

After that 11 hours I hadn't noticed a change in smell but I assumed I was near collecting the tails. Since it was the middle of the night at that point, I started collecting back into the jar with heads in it. In another 4 hours I had collected about 500 ml. At that point I noticed less pleasant but not disgusting smell. I then shut down the boiler.

Q5. Where can I improve my next attempt?

Thanks for any comments

[byacey]

it sounds like you are juggling too many things. First off, the temperature of the steam will be low right up until the liquid actually starts boiling and producing steam at which point the temperature will shoot up like a rocket within a few seconds.

Once this happens you have to cut back the heat until you are just maintaining a slow boil and the condenser is recondensing all the alcohol. If it isn't your heat input is too high, and/or the condenser flow rate isn't fast enough to remove the heat from the condenser. I would start with a high water flow rate, and gradually cut it back when things equalise. The temperature will self stabilise when the column reaches equilibrium.

The first stuff to come over is going to smell like acetone. Dump the first 200 ml or so, Then start collecting and checking until the smell disappears. Keep using a fresh rinsed container to collect a small sample when checking the smell, because it lingers in the collection container if you don't. Keep dumping these samples into a "heads" jug until the smell in the sample disappears. Then you start collecting the good stuff in a seperate container.

[Nykter]

Of course you should use electric heating. But a hotplate can be difficult to fine tune, since it reacts very slowly, better use an internal element. I wouldnt dare using open fire for boiling a flammable liquid, but you will find other opinions here on that...

First some counterquestions:
- What kind of reflux management does your still use? CM, VM och LM?
- how do you regulate the power? Is it with the hotplate's own knob, it migt be a thermostat, and that swithes the plate on and off regulating the temperature of the plate. A triac regulator, as BWredneck states is better. It gives a constant power instead of on/off switching.

Your questions:

Q1: A triac regulator, as BWredneck states is better. It gives a constant power instead of on/off switching.

Q2: I haven't yet grasped the difference between those terms used on this forum. I cant see the use of a column without reflux. Having that said, yes, you should let it equilibrate, and very slowly increase the power or decrease the cooling or decrease reflux, depending on reflux management system.

Q3 Isopropanol is produced by the yeast, and it has a boiling point very close to that of ethanol, so it is difficult to separate. At sea level it boils at 82.3 C ompared to the ethanol/water azeotrope which bolis at 78.15 C.

Q4 I would rather make a still thats not so sensitive to the water pressure, its easier...

[tracker0945]

Don't want to appear as the 'I told you so type' - but - One of the first things you should learn is NEVER leave an active still alone. Especially so on the first run.
Safety at all times is our first, second and third rule.
Cheers.

[gin.stiller]

I will definitely look into the controller. Right now I regulate the temperature by adjusting the hot plate knob. Any idea if I can use that controller with my hot plate by disabling its internal controller or do I need a different heater?

I suppose I am using cooling management. I call it a reflux still instead of fractionating because it doesn't have any valve to directly control the amount of reflux.

So to equilibrate, I should turn on the heat and open the cooling water
to a high rate then lower the water flow rate when it reaches 70ish? Is it in equilibrium when the still head temp reaches the methanol BP? Should I only be adjusting the water after that to control the rate of production?

I felt sufficiently stupid when I saw the steam escaping. The only reason I left the room at that stage is because I plotted 4 or 5 temperature measurements and it looked like it would be a couple of hours before it started boiling. So, I've learned that lesson.

[Nykter]

Yes, you could use that controller to a hotplate. You need to short out the thermostat of the plate. You will have the trouble with slow reaction though.

To equilibrate, start boiling until the top of the column gets hot, then set the power to the maximum power at wich it doesnt leave any product. Dont look at the thermometer, you dont actually need it. It will allways be 78C (Sea level, dont really know were at your altitude, but its always constant.)

Keep the power at this level for atl least half an hour, then gently increase it until the still leaves product really slow. Blead of foreshots and heads really slowly. You can increase the speed in the beginning of the mainrun, but slow off later when approaching tails. Allways collect in small jars and smell and taste (dilluted) untill you get the feeling for it (years later)

You might want a thermometer in the boiler though. It will let you know when its about to start boiling, and later how much ethanol its left.

[theholymackerel]

I think this bears to be said again: a reflux still requires steady EVEN heat.

[Old_Blue]

What Tracker said about not leaving that thing alone.

Didn't see fire extinguisher listed as part of your equipment

[Fiddler]

OK, I've got a safety question. This comes from lack of experience in that I've not completed my still and therefore haven't cranked it up. I've read that during initial heat-up of your compound still, you want to keep the product valve closed until you reach a state of equilibrium. If the valve is closed then there is no outlet. This is contrary to rule # 2 - ALL stills must be open to the atmosphere. They should NOT be closed. A closed still will build up pressure, and can blow up. An open still, will have part of the still (after the condenser) fully open to the atmosphere. You must design your still, so that there is no pressure buildup, EVER.

So how do I reach that state of equilibrium?

[HookLine]

The top of the column, above the reflux condenser, is permanently open to the atmosphere. If your reflux condenser is working properly it will knock down all the vapour inside the column, and none will escape past it to the outside.

You are absolutely right. Never fully seal up a still. NEVER.

[Nykter]

And in a CM still you usually don't have a valve for product. Maybe one for the coolant.

[Fiddler]

Ah, OK, the top of my reflux condenser that sits at the top of my column is supposed to be open to the air? The Compleat Distiller didn't explain that and I figured I needed a cap with the inlet and outlet running through.

Thank you, Hookline, for clearing that up. So as long as my condenser is sized properly and water is flowing I should be OK? The size of my reflux condenser worries me a bit. It's made from about 24' of 1/8" ID copper tubing wound into a 1-1/2" coil that is approximately 11-1/2" long. I have it in an insulated 2" copper shroud at the top of my 2" column. I'll be running a 1500 watt heating element. Will that be adequate?

Nykter, my still design came from the Compleat Distiller book and is supposed to be a vapor management compound still. The book said to have a gate valve as a product valve. I hope I didn't misinterpret that as well.

[gin.stiller]

To allay your fears, Old_Blue:

I did have a fire extinquisher within 10 ft of the still. I was also using a heavy duty extension cord to handle the draw of the hot plate. I am not using any plastic in the system and I am recording all my data in a lab notebook with a blue pen.

I do appreciate everyone's concern and input. I'm looking forward to trying this all again.

Regarding the temperature regulation through the hot plate, I am going to borrow a heavy duty variable voltage transformer from my old research lab. I'll let everyone know how that works out.

[HookLine]

Ah, OK, the top of my reflux condenser that sits at the top of my column is supposed to be open to the air? The Compleat Distiller didn't explain that and I figured I needed a cap with the inlet and outlet running through.

You can have a cap on top, but don't solder it on, just have it sitting there, and put a hole in it, 1/2" is enough.

Check mine out.



The full album is here.

So as long as my condenser is sized properly and water is flowing I should be OK?

Yes.

The size of my reflux condenser worries me a bit. It's made from about 24' of 1/8" ID copper tubing wound into a 1-1/2" coil that is approximately 11-1/2" long. I have it in an insulated 2" copper shroud at the top of my 2" column.

Is that 1/4" OD? If so it is plenty. A 6-7" coil is enough.

I'll be running a 1500 watt heating element. Will that be adequate?

That will be enough, though it will take a while to get to boiling, depending on how big you boiler is. Are you using 1500 w for the main run? It is at the high end for 2" but should be okay, as long as you have a tall column.

[birdwatcher]

Buy this book http://www.gin-vodka.com/making-gin.html" onclick="window.open(this.href);return false;" rel="nofollow

G

[Fiddler]

Piece of cake. A 1/2" hole through my 2" cap. No problem. Thanks.

My tubing is actually 3/16" OD and 1/8" ID. In it's former life it was a 25' averaging sensor used for temperature control for large air handlers. I removed the sensor portion and was left with a 24' tube that makes a nice tight coil.

I read somewhere that a scrubber placed at the top of the reflux condenser is useful. Is that the case?

I have a 2" dia. 40" tall column. I hope that will suffice. If not, I'll have to get my copper pipe stretchers out.

Birdwatcher, thanks for the hint on the book. I've been wondering how good that one was and as you can imagine, the public library doesn't carry it.

[HookLine]

3/16" will give you very efficient heat exchange.

Scrubbers are a good solution if the condenser is letting vapour past, especially for single coil condensers. But given the length of your condenser, and that it is made from 3/16", I doubt you will have any problems, even if it is single coil.

40" of column is okay, though it depends how much of that is packing, coz it is the packing height that counts. How much packing height do you have?

I have a tall VM column (5' of packing, 6' total), and it works great. So simple and consistent to run. I have no regrets about choosing VM.

[Old_Blue]

have a fire extinquisher within 10 ft of the still.

Gin.stiller, Glad to hear you got one

But I caution you not to get it too close. Hard to get to if flames are leaping. I always suggest putting it next to the door leading toward the out side so if you have to run to get it, you're heading toward the exit. If things get to bad you don't get trapped.

Folks probably get tired of me harping on this but I spent 15 years in the fire service and dug my share out of the ashes. Nasty as it gets. Safety first.

[HookLine]

Folks probably get tired of me harping on this but I spent 15 years in the fire service and dug my share out of the ashes. Nasty as it gets. Safety first.

If people get sick of hearing about it, then they ain't paying attention to your good advice. I used to do safety inspections and give classes for med and lab gear, and one thing you learn is that people (including yourself) need reminding pretty regularly.

Maybe you could write a tutorial about fire safety?

[Old_Blue]

people (including yourself) need reminding pretty regularly.

Yes I (we) do Hook.

Don't want to distract from Ginstiller's post but I will say this...

I get pretty anal about this sometimes - just ask my wife - but some things, like the sea and fire, don't have much sense of mercy. There is a good sticky about safety that Tater started (Mash, Ferment and Distill) which many regulars contributed to that covers all types of hazards,including fire, of this fine art. Maybe it needs to be moved to the Novice section so it will get the attention of all the new folks that come straight here.