quote:

I have followed your posts and they have been very informative. I have high FFA oil that generally has a fair amount of water as well, therefore I use the acid estrification for stage 1. You mention higher temps during estrification than 148F and containing the methanol during that process. Could you elaborate on that part of your process? Also, on the methanol recovery, do you typically step up the temps as the vapor boils off and how long does this methanol recovery process take? Are you recovering methanol from the appleseed after draining the gly and then later from the drained gly in another processor?
Thanks for your contributions to all of us. Jack

Hi Jack,
It sounds like we have similar problems with our oil supplies. At least 80% of my oil has to be acid etherified. Generally it's some really bad stuff titrating in at over 22 KOH.
As you know, heat usually makes a process go faster but if you get too hot the methanol will boil out of the wvo and not be available for the process. We can raise the methanol boiling point temp by putting the entire processes under pressure. If I intend to acid esterify under higher than normal temps then I will pump the oil into the processor while it is cool. I use the pump to suck the oil out of the sight tube and close the sight tube ball valves (top and bottom). Sucking the oil out of the sight tube is just a matter of partially closing the valve between the tank and the pump which causes the oil in the sight tube to be sucked out into the pump (similar to sucking methoxide into the tank). Then you quickly close the ball valve at the bottom of the sight tube before too much air is sucked into the pump. Then I'll add my acid/methanol mixture and close all means of methanol or pressure to escape. By the time the temperature of the wvo has reached 155F to 160F there is already 22 to 25 psi pressure in the tank. This is enough to keep the methanol from boiling out of the wvo.

The only time I see a significant benefit to processing at higher temps is when the wvo is "extremely" bad (much like the one I'm going to do right now).

Methanol recovery:
After I'm done with the base part of the process I check for completion using the 3/27 test. Then I let the BD settle for at least 8 hours and drain the glycerin. I don't try particularly hard to get every last drop off glycerin out; I just get the most of it. At the first sign of Bd coming out I stop. There is always going to be glycerin suspended in the BD by the methanol and I use a separate settling tank after I recover the methanol to catch all the residual glycerin/soap.

The BD is usually still quite warm at this point and it is a good time to open the ball valve to the condenser. I fire up the 5500w element on 220v until the bd reaches a temp of 140F or a little better. Then I switch to 110v on the 5500w element and start air injection. It's important to note, in my particular system I have to close the ball valve just below the pump to stop the injected air from traveling up through the pump rather than through the BD where it is needed. I also close the ball valve above the pump because some methanol will collect in the pipe during the process. You also need to be sure that both sight tube ball valves remain closed during the entire methanol recovery.

For those that aren't familiar with AI (air injection) I gently add compressed air into the glycerin drain to help the methanol depart from the bd. I just use enough air to get a steady stream bubbling inside of the processor without overwhelming the condenser. Obviously it is important to have a good condenser to do this. I rely on the air to agitate the BD; I don't use the pump to circulate during the process.

Using AI decreases my recovery time by almost 50% but it also lowers the purity as AI also helps any water out of the BD. I usually re-distill my lower purity methanol later in a still or mix it with new methanol to achieve an expectable purity methanol.

In my 50 gallon Appleseed, it takes just over 6 hours to recover methanol without AI and around 3 hours with AI. I can keep the temp of the BD down to 205F with AI and I get a much more complete recovery. Generally I can't detect the odor of methanol at all after recovery using AI. I haven't been able to achieve this using heat alone during recovery.

As soon as the temp of the BD has cooled to 150F I pump it to a separate standpipe tank for settling. There is a significant amount of glycerin and soap that drops out after methanol recovery and washing is usually considerable easier. After settling the Bd is washed.

The methanol from the glycerin is collected in a separate still using similar technique.

It's good to see folks interested in recovering their methanol. After carefully monitoring and measuring I have found you can recovery more than half of your methanol. Here is that Report.

-mcguyver

Hi, I took the Winter off and want to try the methanol recovery with my Plumber's Delight condensor soon. I think I may have messed something up though. I put the air inlet into the tube from the side of the hot water heater and after plumbing that in I read that the air should be introduced in the bottom of the tank so the air moves through the BD or glycerine at the bottom. Is that correct the air should be introduced at the bottom plumbed into the lower plumbing to cause a bubbling up, or is it OK where I have it now?

My thought was that the air was just to move the vapor out through the condensor but now it seems you want a bubbling effect through the liquid at the bottom.

Please let me know thanks!
Sean

Hi Sean,

If you are pumping the liquid all the time, it doesn't really make much difference where you add air.

But adding air isn't such a good idea, because the excess air needs to escape, and it will certainly carry some methanol with it, even if it's been thru a condenser.

If you are pumping, you can use a venturi so that you don't need to add any extra air at all. Keeps everything inside the system, minimises loss of methanol.

You may have already seen this, but if not, here's a link to consider....

http://www.london-electronics.com/bd/ecosystem/state_diagram_new.htm

Any questions, just shout.

I am curious why you let the temperature of the demethyed biodiesel drop to 150 before sending to the settling tank? Is it because your plumbing or settling tank cannot handle the temps, or is there another reason?

I ask because I did not bother to wait (only processed one batch thus far using this method) and pumped right into my settling tank.

quote:

venturi

Thanks for the info! What kind of venturi do you use?

Is it available at plumbing supply stores or do you build it?

If so how??

I am not too familiar with plumbing.

Thanks!
Sean

mcguyver,
thanks for the detailed "how to". this is especially helpful from someone who is working with generally poor quality oil. I have installed an AI valve as you described, isolating it from the pump. It has been very helpful in speeding up the methanol recovery at the end of that process. I am using a small plate and frame heat exchanger as my condenser and using my next batch of wvo to condense the methanol vapor and at the same time preheat the next batch. I use a carbonator pump to route the oil through a 15 micron bag filter before the condenser to insure that the oil does not plug the condenser and it needs to be cleaned of the particulate at some point anyhow. This is working very well although I would like to recover some of the methanol vapor that is escaping now. I have not figgered out where to get one of Graham's venturi's to siphon off the residual vapor back to the processor. that is a work in process. Again, thanks for your contributions of time and talent to respond to our newbie questions.
best regards, jackmac