If you could recirculate long enough, wouldn't the recovery of methanol from biodiesel happen at lower temperatures (around 70C) since you are above the boiling point of methanol. I only ask because it takes me a long time to get up to 70C. The heater was only designed to go to about 50C.

Thanks for any feedback.

Ross

The short answer is: yes, you can recover methanol at a temperature less than 70 deg C in a GL type eco-processor with a venturi recirculation system.

There are some complex relations in play when recovering methanol.

A pure solution of methanol boils at about 64-65 deg C. Methanol in biodiesel is not pure. It is combined with various other compounds such as water, soap, glycerol, etc. The boiling point of methanol in mixtures with these other compounds is higher than 65 deg C. It may be as high as 70-75 deg C. Therefore, a temperature of 70 deg C may not high enough to cause the methanol in solution with other compounds to boil.

Not to worry. The methanol will still evaporate at that temperature.

In fact methanol will evaporate over very wide range of temperatures, from very cold all the way up to the boiling point. Methanol will evaporate faster from solutions at higher temperature than from solutions at lower temperatures. Therefore, a temperature of 70 deg C may not cause the methanol to boil, but it will certainly cause rapid evaporation.

The above phenomenon occur at atmospheric pressure.

The venturi in the system creates a "lower than atmospheric pressure" area in part of the system. Methanol boils at a lower temperature when the pressure is reduced. Methanol evaporates faster at lower temperatures, all other factors being equal.

Wow! Thanks for the depth provided. I don't quite have an eco-system processor, but something similar and larger. My studies/readings led me to believe what you are saying, but wanted confirmation.

Thanks
Ross

Hi, I am curious about mathanol recovery. Someone said that the methanol recovered is not pure. Is it pure enough to run in the next batch or is there another reason to do the meth recovery. In the process of building a BD processor and want to have the best set up I can.. Thanks

You can use the recovered methanol. You will probably need to mix in some fresh with it though. I have read that you should only use 25% reused methanol with fresh, but have personally done batches that were 75% or so recovered methanol. The stuff is anywhere from $3 to $4.50/gallon... you should recover it in my opinion.

Search the site, you will find plenty of good reasons to recover.

Ross