When you recover the methanol from a batch, how much yield do you get back. If you start with 8 gallons of methanol, how much of that do you get back?

Another question: how many times can you recover that first same 8 gallons of methanol?

thanks

nitroman

This has been answered before, but trying to find it would be..difficult, at best.

The theory is you use 20-22% methanol originally, but the reaction only needs ~14%. So 8% of the original WVO volume should be able to be recovered in methanol. This would be 36% of your original methanol volume. You lose some to inefficiencies in the recovery still, so to say 1/3 would probably be pretty close.

I run 40-45gal batches of glycerin for recovering the methanol, and pull 12-14 gallons from it. This would be 25-31%, which I think supports the theoretical numbers.

As far as reusing the "same" methanol, its limitless. But you are always adding new to the recovered because some is getting used and the recovered is always just less than 100% pure. I use 50/50 new and recovered methanol for all my batches.

thanks ryan p. That gives me a general idea. So, you just hang on to your glycerin until you get about 40-45 gallons and then you recover or do you recover on every batch of bio when you process?

Maybe some pics and info on your recovery process...

thanks

nitroman

I just hold on to the raw glycerin until I get around to running a recovery...the recovery still I built holds about 40-45 gallons...I probably have 200gals to run through it still before I am caught up. I got through about 200 gallons last summer, so I hope to have no raw glycerin stored by the end of this summer.

Here's the still I use...


...the other side...


The plumbing.

Pump output flows through an in-line heater (6500W 220V at 120V, so 1625W actual) then into the drum through a Rilla Biofuels' 2-Pipe Drum Port through the long tube. Pump return is through the short tube with a 90deg fitting so it draws "down" from the glycerin flow in the drum. Condenser is plumbed in the top, smaller port on the drum.

It loses heat as fast as the heating element can replace it, so I only run recovery when the outdoor temp is 80F or above. I don't have any pics of it set up yet, as I moved last Nov. and haven't completely unpacked it, or fixed the couple things that broke on it in the move.

Where did you get your idea at for this setup?

thanks

nitroman

The condenser is the standard Plumber's Delight from Graham Laming's page.

The inline heating element is like a few use on their processors as an added level of safety since the element is always submerged. I felt it was beneficial here due to the goal of removing a flammable substance from another marginally flammable substance.

Then it was just adapting what so many others had done to what I had available for a vessel...which was a basically brand new 55 gallon drum. Other specific things were done my my own design to fit what I wanted it to do.

1) On a wheeled trailer because I had it and needed to be able to drag it around to reach power and water and store it out of the way.

2) Placed the drum on its side to maximize the internal surface for evaporation and to place the exit/entry port below the fluid level without modifying the drum. The drum was intact and in good shape, so I didn't want to punch a bunch of new holes in it and create weak spots. Its flammable goodies, after all.

3) Since I only had 2 ports, and one had to be for the condenser, I had to use to 2-port plug from Rilla...which I had seen before on some 55gal drum processors.

4) Then the internal flow of out the long pipe and in the short was just to make sure I was turning over the full volume, and not just creating some short loop with the 2 pipes in the same drum hole.
By doing this I also established a fluid flow that moves toward the condenser, which I think should transfer to a gas flow toward the condenser, helping move methanol to the condenser.

5) (Missed one) I used the 12V pump because I had a 12V laboratory power supply, and that lets me dial the pump's speed up or down to maximize the cooling water contact time within the condenser. If the water is exiting the condenser cold, I can slow the pump so it picks up more heat. When the water starts to get hotter, I can speed up the pump so it picks up less.

So, like so many things, it was take the examples I had seen and compile them into something that fit what I wanted.

I have one more question, and this one is stupid. How do you know what you are getting out is methanol when you are finished?

thanks

nitroman

Well...the weight test for purity shows it to be fairly pure. And when I make fuel with it...it works! If it was water (the other thing mostly likely to come out of glycerin when distilling), it would make a big gooey mess of the fuel O tried to make with it.

Here is the test graph you need to determine purity. You weigh 1L of your recovered methanol, divide by 1000, and reference that weigh to the graph on the appropriate temperature curve to find the purity. I'm usually in the 85-90% range.

It does make the assumption that you only have methanol and water in the sample. I sometimes get a little bit of glycerin in the distillate, and that will throw the curve off for reality, so I kind of have to fudge the number a little bit when I know it will be inaccurate.