Biodiesel and SVO Forums Home
Easy still, no vac pump, used water heater, copper coil in bucket of water

This topic can be found at:
http://biodiesel.infopop.cc/eve/forums/a/tpc/f/4441089311/m/7761034611

December 01, 2005, 11:46 AM
troy
Easy still, no vac pump, used water heater, copper coil in bucket of water
First the fine print. We're dealing with a flamable, explosive, neurotoxic liquid/gas here. Also note that if you try to drain the glycerin immediately after the distillation, it will be extremely dangerously hot. The information here is presented for educational purposes only. This setup worked well for me, but I take 27 multiple redundant steps to INSURE my safety which I am not showing or describing, since you can't possibly describe every possible thing that can go wrong, and what to do to prevent it.

If you decide to build a still, YOU are responsible for doing your research to make CERTAIN that you are doing this in a safe and responsible way, outside, with fire extinguishers of suitable size and type, etc etc etc.

OK, you've been warned.

For those who don't want to mess about with the expense and complexity of a vacuum pump, here's a straightforward atmospheric still. By the way, I haven't seen anybody show the math for how you save energy or money with vacuum distillation vs simple heat/atmospheric distillation. Sure, it takes lower temps with some vacuum, but you're also consuming energy to make your vacuum. There really is no such thing as a free lunch. Vac pumps usually aren't cheap either.

I'll describe it, then I'll post links to pic's of the components.

The condensor is a ten foot length of 1/2 inch soft copper tubing coiled up in a five gallon plastic bucket to hold the cold flowing tap water. The coil is secured at the top, the bottom, and once in the middle, which is the short copper tube soldered on at right angles. It's just a brace to the bucket.

I run a bubbler from an aquarium pump in the bucket because I was getting a lot of temperature stratification in the water. Quite hot on top, cool on the bottom. The condensor must slope smoothly downhill to the output, which should be the lowest point. No dips, no sags, etc. The condensed methanol must freely drain into the catch vessel just by gravity. I run a slow but steady stream of cold tapwater through the bucket, so there's an overflow for that. I like to keep the water in the bucket at 70F or less. My tapwater comes out around 50F prior to hitting the bucket.

Your condensor must be capable of removing just as much heat as you are putting into the still, pretty much. A single bucket of icewater won't be nearly enough cold to condense all the methanol from one batch.

The still itself is a converted 30 gallon water heater with an electric element (220 operated on 120 to preserve element life). I now run two 220V elements each rated at 4,500 watts. I had to weld in ports to do that. I couldn't find a big enough cheap 220V element that produced enough heat when operated on 120V. Since I operate them on 120V, that cuts the effective wattage to 1/4 of rated, or 1,100 watts each, a total of 2,200 watts (actual). I did a couple of runs with a single 220V element run at full voltage/wattage. It was plenty of heat to get the run done in a timely manner, but the element burned out on the second run. The pic of the still shows a bare tank, but I put a fiberglass water heater blanket over it when I run it. It's important that the boiler/pot/water heater be well insulated, or you waste energy and make the distillation go unneccesarily slowly.

I typically put 16-20 gallons of byproduct in for a batch. I welded a two inch port on the top to make it easy to dump glycerin in. And don't forget when you're done, the glycerin will become a solid at anything close to room temperture (if you used NaOH as your catalyst). So don't wait too long before you drain you meth-free glycerin out. I replaced the mickey mouse drain valve with a 3/4 inch ball valve to drain it efficiently. Don't burn yourself when you drain it.

I monitor the temperature of the output right where it comes out, and it runs around 140F while the bulk of the methanol comes out. As production goes along, the temperture climbs. I stop production when the output temp is about 180F. By this time, the rate of methanol production has dropped to a very low rate. This suggests that I have recovered the vast majority of the available methanol.

I used a piece of automotive heater hose to make the 180 degree turn from the output of the still to the 3 foot piece of straight copper that connects to the condensor.

Here's the first pic of the condensor:

This message has been edited. Last edited by: troy,


May 22, 2014, 12:46 AM
Yuka
Do you pump the glyc.
You bubble air.
Or just heat it?

Thanks.
Eduardo.