Air Washing Biodiesel
By Rick Da Tech
Drywashing Biodiesel with air or 'Air Washing' has been around for a while. It is bubbling air through unwashed biodiesel to evaporate and carry away methanol from unwashed biodiesel. The Ecosystem Processor was developed from this idea. There are also several people on the Yahoo biodiesel list promoting their version of air washing. If not done properly, it can be very dangerous.
My opinion is that this method is fine for bucket batches, outside, away from people. A bucket batch will have less than 500ml of methanol to evaporate.
Dick on the Yahoo Biodiesel list sent me these pictures. He uses the shop vac to supply the air to bubble the biodiesel. The PVC tubing in the drum is how the air is distributed. He vents into the air through the big PVC pipes mounted in the lid. He vents to the outside, and has stated that he doesn't see a problem with the methanol vapors. There has been a discussion where dumping the air vents into a drum of water was suggested as a way to scrub the methanol vapors out of the vented air.
Dick says he can run four batches through the drum before having to scoop out the soap. He suggests 1 and 1/4 hours of bubbling for every 10 gallons being processed. His resutls were (I think) 150 to 300 ppm of soap left in the finished biodiesel.
This system was originally promoted by Del Martins. Del does not make biodiesel since he lost his home, business, and biodiesel processing equipment to fire a while back. The official cause was reported as a wiring fire. Del broke the most important biodiesel safety rule. He made biodiesel in his home.
Air Washing Biodiesel - Infopop thread Ryan P. discuses his process of air washing. He uses KOH
50,000 PPM of Methanol in the air in my shed! - Infopop thread on air washing safety