Hello all. I do not do a 5% pre-wash and recently tested the purity of my recovered methanol using an alcohol hydrometer. My purity is 93%, which has been good enough for me to mix 1.5 gallons of recovered methanol with 8.5 gallons of 99%+ virgin methanol for use in transesterfication.

I'm contemplating using the 5% water pre-wash to speed up my glycerin settling phase, but I don't want to screw up my recovered methanol. Can anyone tell me what their recovered methanol purity is when using a 5% pre-wash? Keep in mind, I'm using a simple plumber's delight condensor and heating my biodiesel up to 200f, so if you're triple distilling or anything, that won't help me too much. Thanks!

mines over 98%.

but I control the temperature within 1 degree F at the top of my reflux column. without good control here you'll have a hard time recovering high purity methanol.

-dkenny

quote:

Keep in mind, I'm using a simple plumber's delight condensor and heating my biodiesel up to 200f, so if you're triple distilling or anything, that won't help me too much. Thanks!

First, are you recovering methanol from your biodiesel phase, from your glycerine phase, or both? 200F is way higher than necessary -- any water in the pot would be coming over at that temp.

Second, what sort of still head do you have between the pot and the plumber's delight condenser? If it was even 1" in diameter and a few inches long, you could squeeze in one or two copper scrubbers and get some fractionation happening.

I don't have good temperature control so I just let it get up to about 200F, figuring that it will distill faster this way. To keep it around that temperature I use an outlet timer. It is set for 15 min on and 15 min off.

I'd like to get some sort of setup where I can use a PID to control the temperature, but I don't know how to do it. I'm mechanically and electrically inclined, so with instructions, I'm sure I could accomplish it.

I do have a few inches of head between the pot (my water heater) and the 90 degree turn on the condenser. I'll try adding some material in here, if I can.

Would you suggest that I try to run my process at 170-180F?

Would something like this work?

http://cgi.ebay.com/PID-Temperature-Controller-SSR-Kiln...QQrdZ1QQcmdZViewItem

I'm just not sure how to wire it up. Should I monitor both pot and condensor head temps?

I use vacuum distillation with no extra heating after draining off the glycerin (BD temp about 130F). I get 90-93% purity of methanol, and I do the 5% prewash.

quote:

Would you suggest that I try to run my process at 170-180F?

Temperature should not go above 150F at the point where the still head feeds into the condenser. Temp in the pot doesn't matter.

I'd still like to know if you're recovering from the biodiesel or from the glycerine -- water will be more of a problem from the glycerine, but you can recover a lot more methanol too. Personally, assuming you wash your biodiesel, I wouldn't even bother recovering from the biodiesel.

Right now, I'm recovering from my biodiesel. I get about 1.5 gallons back from 10 gallons of methanol used.

mine's from the gly only. this gly is from acid/base processing, base only, base/base, and all with >5% prewash.

if the head temp is controlled well enough, the vertical height before the turn to the condenser is high enough, 200F pot temp is too low to get all the methanol, but it get far bit of it. the boiling point continues to rise as the methanol is boiled out. mine normally hold around 180 for hours then starts to slowly climb.

the higher the head temp the lower the purity, but the faster the methanol is recovered.

just my 2 cents

-dkenny

cfunderburg:

Assuming your 10gal methanol is converting 50gal oil, 6gal is consumed in the reaction, leaving 4gal theoretically recoverable (maybe 3.5 actually recoverable).

You're getting 1.5 from the biodiesel, meaning 2 still in the glycerine. If you did a 5-10% prewash, almost all the methanol would be in the glycerine (maybe someone else knows just how much)
and could be recovered at 95% purity with only a little refluxing.

Something to consider (I'm sure you have :-))

will wash water in the glycerine affect soap making?

And what about the PID I put a link to above?

cfunderburg,
don't know about the soap making for sure. the only time I tried to make soap from gly after methanol recovery..worked but the soap was supposed to be liquid soap instead its more of a gel.

I use watlow 965 pid in my setup. but just about any pid with the correct thermal couple should work. my thermal couples at type J and K. they connect using 1/8" compression fittings.

-dkenny

quote:

Originally posted by jon h.:
I use vacuum distillation with no extra heating after draining off the glycerin (BD temp about 130F). I get 90-93% purity of methanol, and I do the 5% prewash.

Can you tell what kind of vaccuum pump do you use?

I found the methanol I'm getting from a race shop here in So Cal is only 85% pure and it's been working fine.

My recovered methanol (PID controlled at the headspace) is 95% with prewash. I get it up to temp, then set a timer that shuts the whole thing down after 8hrs. I recover about 2 gallons from 10 gallons of glycerin (which includes the prewash).

You might just run your system a little longer at a lower temp....I'd consider trying that with your current system and focus on the results instead of the best "theoretical" method. The amount of work you'll put into modifying your system might not be worth it for you.