Fantastic thread!

Thanks for that informative post Mike C. It answered alot of my questions on what I need to do/bulid.

quote:

quote:
Originally posted by bdubet:
Excellent and very informative thread. Thanks, all!

I seemed to have missed one little process in all this.

How do you control the temperature of the pot? Is there a thermostat wired into the system or do you simply turn off the elements after reaching a particular temp?


I do not use a thermostat, and think that is true for most home brewers who recover their methanol.

The boiling point of methanol is about 65C (149F) If the pot were entirely full of methanol, the temp of the boiling pot would never go above 149 until the meth was all boiled out (assuming atmospheric pressure).

In fact, we do not have a pot full of methanol. There's all kinds of junk in there, including a little water that is produced as a byproduct in the primary biodiesel reaction. As a consequence, the temperature in the pot provides excellent clues about what is going on in there. During the course of my typical distillation run, the initial temp runs up pretty fast to some number (I actually measure at the point where the gas leaves the pot), say 150F just to grab a number.

Once you enter the main part of the distillation, that number will stay pretty steady and very slowly creep up. Once most of the methanol is gone (recovered! Woo Hoo!) from the pot, the number will go up much more quickly. You should measure and graph this as you go, because when the slope changes dramatically like that, you're just about done. When I see the temp of the output gas at 185F, and methanol production has dropped dramatically, I'm done.

This is all done with ~constant heat input and without thermostat. I suppose you could put one on for thermal runaway protection, but it serves no use in regulating the distillation itself.

This works because the heat input capability of the still is carefully matched to the heat removal ability of the condensor. The condensor MUST be able to remove heat just as fast as you put it in, or you will lose some of the methanol as uncondensed gas, and possibly poison yourself in the process.

Finest regards,

troy

Troy,
How about an industrial temp controller? I just happen to have one around here.

quote:

Originally posted by jammer:
One more question. Has anybody ever put in a way to stir the pot? (I am very good at the other form of this).....
Hope ya had a nice vacation.
Jammer

How about using a pump and circulate from the bottom to the removed top element hole?

[


How about using a pump and circulate from the bottom to the removed top element hole?[/QUOTE]

exactly... turn it into a spray at the top for increased surface area as well as a way to pump out demethed byproduct.

quote:

Originally posted by Coach:

quote:

Originally posted by jammer:
One more question. Has anybody ever put in a way to stir the pot? (I am very good at the other form of this).....
Hope ya had a nice vacation.
Jammer

How about using a pump and circulate from the bottom to the removed top element hole?

Is it possible to have too much agitation? Do you think the gylcerine might start foaming?

Dear Coach,

What would be the role of the industrial temp controller?

Also, with the elements operated at half voltage, all stirring/pumping seems unneccesary, so can't comment about foaming problems with pumping. Also can't comment about if that would add life to elements operated a full voltage. I would be concerned about getting the pump totally cleaned out after each run, as the NaOH based byproduct WILL turn into a solid at room temperature once you remove the methanol.


Finest regards,

troy

Bump, for renewed interest in an easy still.

Finest regards,


troy

Troy, do you use any sort of pump or paddle to stir inside the still?

Dear Raften,

No, I don't pump, or stir or aerate (yet).

I had such good results with the plain setup that I never felt the need to go fancy. I think this is due primarily to the low watt density heating elements. No local burning around the elements, just heating, then "thermosyphoning" or convection currents to keep the pot mixed up.

I'm in the middle of a move, so my setup is down at the moment. I intend to add some air to the bottom of the pot to see if I get improved yield while maintaining excellent purity, as reported by others.

Isn't science fun!!??

Finest regards,

troy

Hey Troy and others, great thread!

Troy, think way back to december of 2005:

quote:

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.

Why do you figure this is the case? I am not arguing here, just curious...

I am playing with a similar setup for our glycerine still, except I'm using a discarded coil of aluminum from the back of a dehumidifier. This is in a bucket with cold water coming in the bottom, warm water outlet at the top.... pretty much a version of what you have pictured here.

The catch is that my aluminum coil is a double loop... so the hot methanol vapor enters the bucket through a hose sealed into the lid, but then enters the coil at the bottom of the bucket. It then is intended to travel through the coil as it winds upwards and then ends back a the bottom of the bucket where it should exit to the methanol carboy. Confusing? Suffice to say that my coil has a big upward bend in it that does not allow the vapor/liquid methanol to travel directly downward to the reciever.

If there's a reason this won't work I'd enjoy understanding why!

We built a GLPlumber's Delight for our appleseed to recover methanol from the biodiesel. That thing works great... it is a simple tube in shell counterflow condensor, took us $50 and a few hours to build. The condensor outlet is always cool...

Anway with regards to my question about no dips, sags, or upward loops, we have the output of our plumber's delight we have the running through a clear poly hose into the receiver carbouy. This hose is sloped slightly upward, unintentionally. The result though is that I can watch the methanol puddle up in the hose, and then it will "glub" as the pressure increases slightly, and liquid is dribbled into the reciever. This is more exciting than when it just dribbles straight down in and gives me some visual input on the methanol production.

Do you think the very minor back pressure from the slight slope of the outlet tube helps to slow the vapor stream and increase condensation?


We did inject air on the two biodiesel/methanol recovery runs we have done so far, and it definitely works to increase production. It is visually obvious that when the production from heating alone has stalled, a trickle of air up through the drain immediately brings out more condensate.

On Monday we recovered about 1.25 gallons of 92% pure methanol from 48 gallons of biodiesel. We use 22% or about 10 gallons for the batch.

Yeah, science is fun! I get pretty giddy over the recovered methanol, kind of like my first batch of BD!

Thanks,
farmer

Hey again Troy and all...

Regarding safety, Troy are you using some controls to prevent dry fires of the heater element with no liquid to cover? If so, care to describe that set up?

At this point we are just being heads up.

Also our appleseed recovery setup is indoors, in our ventilated shop. I turn on the big vent fan when we are in recovery phase or if I suspect fugitive emissions. Currently I am venting the reciever carboy to the outdoors via tubing, but we are also looking at doing a fumeless return loop like Graham Laming describes in this excellent posting Eco-system

Anyway if you want to flush out some safety discussion here I am all ears... if there is a more appropriate thread fo discuss methanol recovery safety I can go there too...

Right now I feel like I understand the safety basics but would hate to learn the hard way!

Thanks,
Farmer

quote:

Originally posted by farmer:
Hey Troy and others, great thread!

Troy, think way back to december of 2005:

quote:

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.

Why do you figure this is the case? I am not arguing here, just curious...

Thanks,
farmer

There are at least three concerns if you have a condensor that doesn't naturally and easily drain.

Number one, which you alude to, is the fact that you may trap a "pocket" of methanol and pressurize the still. No, I don't think this is the end of the world, so long as it's less than a few psi and you have a way to tell that. An overpressure safety valve would be great, but it's hard to find them in the very low psi range we want and need.

Second, instead of a nice steady output, any pockets, dips, sags and so on may cause your output to spurt methanol periodically and perhaps violently, so that's a potential safety issue.

Third, how will you drain the methanol that's trapped in the first "loop" of your condensor?

On an unrelated issue, methanol is somewhat caustic to aluminum, so keep an eye on that if you use this for very long. Nobody has reported any bad events due to this issue, but you could be lucky and first.

Finest regards,

troy

quote:

Originally posted by farmer:
Hey again Troy and all...

Regarding safety, Troy are you using some controls to prevent dry fires of the heater element with no liquid to cover? If so, care to describe that set up?

At this point we are just being heads up.

Also our appleseed recovery setup is indoors, in our ventilated shop. I turn on the big vent fan when we are in recovery phase or if I suspect fugitive emissions. Currently I am venting the reciever carboy to the outdoors via tubing, but we are also looking at doing a fumeless return loop like Graham Laming describes in this excellent posting Eco-system

Anyway if you want to flush out some safety discussion here I am all ears... if there is a more appropriate thread fo discuss methanol recovery safety I can go there too...

Right now I feel like I understand the safety basics but would hate to learn the hard way!

Thanks,
Farmer

Briefly,

I don't have any hardware method for preventing dry firing/exposed element. That would be nifty and very worthwhile, I just haven't thought of an elegant way yet.


Many folks think that it's a bad idea to run a still indoors. I have only run mine outdoors, just because, if I have a bad event, that could turn into a structure fire in a heartbeat.

That's all that pops in my head at the moment.

Finest regards,

troy

Thanks Troy...

I ended up ditching the aluminum coil in bucket condensor for now. The copper plumbers delight is working really well for getting methanol out of the BD in our appleseed, and I have been retooling the retooling the little water heater that we plan to use for GLY recovery. In the end my plumbing to the bucket was kind of hokey...

Nonetheless, on the issue of dips n sags in condensor plumbing:

The outlet tube from our plumbers delight (a straight column) is clear poly tubing, which runs to the methanol carboy. This tube slopes upward slightly, so that the liquid methanol pools up there and then glugs into the carboy as pressure from the still pushes it through. It must be very slight back pressure (less than 1 psi) but perhaps this slows the gas down enough to guarantee full condensation. The copper above the outlet tubing is always nice and cool, so I know I'm not pushing the condensor.

Thanks for the safety considerations. I agree that working indoors is a little hairy... Just havent figured out how to get the 80 gallon appleseed out doors conveniently. I like to recover the methanol from the BD while its still in the reactor, perhaps even taking advantage of residual process heat.

We'll continue to be extra careful.
Regards,
Farmer

quote:

Originally posted by BobAbbey:

Methal Honey in all her glory


Her Head


Her hotspot

This is our pot still for methanol recovery.

She was a honey barrel so we named her "Methyl Honey".

She has a 5500W/220V element running on 110V.

That's a Ford Festiva radiator (aluminum that I was told methanol will eat), it's been ok so far after 5 batches.

I get about 5 gal of clear methanol from 20 gal. of glycerin in about 12 hours. She just seems to perk along at 160-170 head temp until she's about done then starts to ramp up the temp. Then I shut her down.

Using the 5% prewash we get 85% methanol this way. I haven't tried the un-pre-washed glyc yet.

Bob

Bob, I was curious how your setup is working. I need to build a methanol recovery and was going to use a heat exchanger/radiator from a car. It looks like your line coming off the still is plastic is that OK to use given the temps? Do you angle the radiator at all to make sure no methanol pools up inside it?

Are you only measuring the head temp? I saw in another post that Farmer recommends going to 260F in the pot temp to get the glycerol low enough in methanol content so its not classified as a hazmat

Regards