I'm sure we all dry our biodiesel in one way or another. From testing lots of peoples samples, I'm sorry to say that most ways don't seem to work. Bubbling with ambient air, sprayring devices, etc.
Now don't get me wrong here guys, I'm not trying to preach to you but I think getting the water down to reasonable levels is important. I personally like mine down to below the german spec of 300ppm. I know lots of others would disagree.
One of the difficulties we face is that testing bio for water is not one of the easiest tests we can do.
For years I dried my bio by bubbling with ambient air. When I got my Sandy Brae I was horrified that the level was 8 to 900ppm. I never had any trouble with my bio, but at the time it was going into two older indirect injection vehicles. I gave a sample to a commercial producer who had a KF and he confirmed the 800ppm.
So I thought I would do a simple experiment and put the compressor inlet into a cardboard box. At the opposits side of the box I cut a flap and directed a small fan heater to inside. I left it for 4 hours. Result was 400ppm water.
It was after this that I got interested in making one of IMB's turbo dryers. He had experimented with all sorts of things, dehumidifiers, fan heaters, spray devices etc and in the end came up with this idea.
I will post a drawing when the wife comes in (still learning)
Basically the dryer is a plywood disc that sits on top of the processor/wash tank. On top of the disc is a 10-15 litre plastic drum with a sealed lid. on top of the drum is something like a tuppaware sandwich box with about 2" of self-indicating silica gel inside. Small holes are drilled in the lid of the sandwich box and the base (through the top of the 15 litre tub)
inside the tub is an aquarium bubbler, with the pipe going down to the tank bottom. At the back of the plywood disc is a 4" computer fan pulling air out of the headspace, driven from a small led transformer also inside the tub. All joints, lead exits are sealed with silicone.
The air pump can only pull air that has come through the silica gel, as the air goes down the line it gets warmed by the biodiesel (50 to 65 degs)
The results my dryer gives are;
before dryer after water washing, @ 1200ppm
after 4 hours 500ppm
after 7 hours 150ppm
after 13 hours 50ppm
I usually leave mine 7 to 8 hours, the 13 was just to see.
I heat the bio to 60 degs, when it gets to 40 I start the dryer, when at 60 I leave it for 3 hours, then swith off the heat, when it gets down to 40 I turn off the dryer. Total time 7 to 8 hours.