Couple questions...

[Fermentanator]

I have built part of my re-circulating cooling water system, how big a water bucket will I need to ensure it keeps cool? Was thinking instead of having it be cooled after coming out of the still, it could just go back into the water supply, with some frozen plastic bottles in it. Bad idea? If so I have and idea of using a decent length of coiled copper (kinda like a radiator) with a fan blowing on it, we'll see I guess.

Hopefully my submersible aquarium pump will supply enough water. I did test it, it's fairly substantial.

Also, for the column insulation, would some roofing insulation be suitable? I have a little spare that I could fix to the column with cable ties.

Would you use stainless steel or copper for lenghthening the column?

Thanks for advice.

[Mud Mechanik]

Will you be cooling a reflux section and a liebeg with the same water or what? I have done a couple of runs with my closed loop water circulation, on a friend of mine's mile high reflux still, the water in a 55 gallon drum went from 74 degrees to around 85 degrees in a ~4 hour run, it was cooling both the liebeg and reflux section using the same fountain pump. On my pot still the same amount of water in the drum barely gained 3 degrees during a ~4 hour run, but I am only cooling my output. Hope this helps. MM

[Vodka_Master]

I also recirculate my water. When i started out i had a 20L bucket and 50 gph pump. The water was being used to cool just the stillhead (dont use anything to cool output) and it went throught a computer radiator with a fan blowing on it. With that setup the water was comming out burning hot from the column, and pretty warm from the radiator. Took something like 2h to overheat the bucket. Now i have a 100L drum all full of water, a 300 gph pump, with the same fan and radiator. When i start off, i have fresh cool water from the hose ( around 15 celcius) and i dump a bit of ice into it, so the thing is really cold. After a whole day of running witch is around 10 hours, the water is around 30 degrees.

So from my experience i would say a bucket is too small, it will heat up too fast even with a radiator. Better off getting something big that will hold more water, so you wont have to worry about changing or icing the water.

[Mud Mechanik]

Good call VM, I forgot to mention that my pump is rated at 350gph at 0 ft lift but is only pumping about 200gph at around 5 feet to my condenser. MM

[mrhooch]

I live in a land where you can leave buckets of water out overnight and you will end up with blocks of ice in the morning. So i'll add this little bit.

How much cooling in water you need is based on how big a charge you have. lets say you're distilling 5 gallons. In potstill mode, you will deal with at worst, 3 times the amount of heat generated to heat the wash up in the first place. It is a lot of heat. Cooling into a volume 3 times larger will result in a heat gain of roughly 75 degrees.

From my first statement, a chunk of ice the size of the wash, will cool the process for the duration I've found. Then you need a smaller bucket, Add just enough water for the pump to run, then ice, it will melt!

My cheapy pump couldn't provide the head (lift) so I had to elevate it to get enough flow through my reflux, something to watch out for.

Any insulation on your column goes a long way to improving the results, even a towel!

Good luck with your setup!

Hooch.

[Husker]

How much cooling in water you need is based on how big a charge you have.

Close, but no cigar. How much water you need, it fully determined by how much power you are putting into the system (minus any power you vent back out of the closed loop, but for now, we will ignore that, and assume there is none of that happening).

So, if you run a 25L boiler with 1500W for 8 hours (8 hours after heat up), using high reflux % in a column, you will need a hell of a lot more coolant water, than the same 25L still charge, if all you do is heat it up with that 1500W, run it for 2 hours, in pot still mode.

In the first case, you have to have a heat sync capable of holding 12k watt/hour of power, and in the 2nd case, you have to only heat sync 3k watt/hour of power.

Same size still charge, but very different cooling requirements.

H.

[mrhooch]

Ok...First, I did a bit too much taste testing of the new batch last night, shouldn't post under the influence.

What I was trying to explain was the sleazy way of calculating cooling requirements. You are absolutely correct in that you have to dissipitate all the heat that the boiler generates while you are collecting. You can do it by calculating the power input, or by observing the results the application of said power has on a known quantity, which is what I was attempting to explain in my befuddled manner.

If your unknown heat source takes 1.5 hours to heat up say 20 liters of wash, (forget about the small delta in differences in the specific heat capacity between alcohol and water, and just consider it all as plain water), then if you run for the same amount of time, you will need to absorb the same amount of heat as it took to heat up that same volume up to roughly 190F. If you had the same volume of water as the batch to cool with, then at the end it would roughly end up at 190F. If you run reflux for 10x the heatup period, then you will heat 10X the volume of water 200L to roughly 190F.

With water as long as you are not melting it or vapourizing it, needs x amount of power per volume V to raise it by temprature T. In other words V1*delta T1 = V2 * delta T2. Example, the heat to raise 1 liter of water 10 degrees will raise 10 liters of water 1 degree.

Because all the scientific stuff cancels out at the end, I was trying to come up with some hillbilly math to give a good guess as to how much water you need to absorb the energy you are putting in.

Time for more coffee...

Hooch

[Fermentanator]

Thanks everyone. I very much appreciate the advice given. With my pump, I think I will have to elevate it, to be on the safe side. Once I get it all set up I will do some calculations and testing.

Thanks again.

[olddog]

Your cooling supply vessel should be at least the size of your boiler, if its bigger then that's OK.

With my pump, I think I will have to elevate it, to be on the safe side.

Raising the pump does not make any difference, raising the height of the water level does as it decreases the headroom.


OD

[mrhooch]

OD:

With my little pump it couldn't produce enough lift for it to pump water into my reflux condensor with the bucket on the floor. So I put the water bucket on top of a upside down garbage can and problem solved.

Hooch.

[Dnderhead]

pumps "push" better than "pull", and if you install your return lines back into the tank, once the system is full the pump just needs to circulate, not lift.

[rad14701]

+1 on what Dnderhead said...

Let the siphoning effect work to your advantage...

[mrhooch]

Ah yes, but I never did get around to sealing the two parts of my cold finger together. The down pipe is insulated, and soldering the two parts together would likely have melted the insulation. So there is a vacuum break that prevents the siphoning from happening in my setup.

I don't need to have a huge flowrate to knock down all the vapour so it doesn't leak under normal running conditions.

Hooch

[Fermentanator]

Yes, not raisethe pump, but the water. Thanks for the rule of thumb that is should be at least the size of your boiler olddog.

May even run it in the bath room,next to the bath tub, plenty of water, ceiling fan, all tiled so easy clean up.

[mrhooch]

Folks:

I have an aquarium magnetic drive pump which at most will lift water 5 feet. The top of my reflux condensor is 7', and the water just never got there until I raised the pump and bucket. I use ice because the amount of energy to just melt the ice, is equivalent to heating up the equivalent amount of water by roughly 80C.

Hooch.