My brain is literally overloaded with information about methanol recovery. I’ve been researching stills, vacuum pumps, chillers, and testing methods until I’m just plain numb. It’s a critical step in the overall process of making biodiesel, since we can recover between 30 – 50% of the methanol used. At over $2.00 a gallon, that’s a significant savings. Plus, since methanol is toxic, the EPA gets a little concerned if you just start pumping methanol vapors into the atmosphere. Our biodiesel reactors are vaporless, so that’s not a concern, but we do want to get back as much methanol from the biodiesel and glycerol as possible.
My initial attempt was to use a counterflow chiller made in my garage. It worked, really well actually, but the energy required to heat the mixture until the methanol evaporated is too excessive. That’s where the vacuum comes in, by lowering the boiling point. I think Morgan and I have a pretty good idea for a working model to use at the scale-up plant using a combination of hot water heaters and vacuum pumps, but for large scale production, we’re still investigating options. I’ll post pictures of the contraption(s) when I can.