Using A Biodiesel Stand-Pipe Wash Tank
by Graydon Blair of Utah Biodiesel Supply
1- Transfer Biodiesel into Wash Tank
2- Turn on Heater & heat the biodiesel to at least 80 deg F.
3- Once it's to temperature turn on the misters.
NOTE: Don't mist too agressive to start with. You want a nice, light mist, preferrably somewhat above the Biodiesel.
4- Mist until you fill the tank w/ washwater up to the stand-pipe
5- Turn off the misters & let it sit for 3-4 hours to let the water settle.
6- Drain off the first wash water using the non-standpipe opening
7- Mist again, but this time using a more aggressive mist up to the standpipe level again
8- Let it sit again for 3-4 hours
9- Leaving the wash water in the tank, begin a VERY LIGHT bubble. Bubble too hard and you're going to get emulsion.
10- Bubble like this for about 8 hours
11- Turn the bubbler off.
12- Let it sit for about 3-4 hours.
13- Turn Bubbler back on, only this time more aggressive for another 8 hours
14- Turn off bubbler & check to see if it's done.
Way To Check If The Biodiesel Is Completely Washed & Ready To Dry:
This took about 15-20 minutes to settle out on a nice warm day. Depending on temperature and humidity and a bunch of other factors, your settling time may take longer.
Notice the nice, clear water on the bottom though. If your water doesn't come out clear, it means you need to do more washing. The Biodiesel doesn't go completely clear at this stage though, it's still a bit cloudy but the water on the bottom is nice & clear.
Also, here's some additional tips from Jack Jones, the person I learned to make Biodiesel with...
"I don't usually time my mists. I just turn the mister on and check the water level every once in a while. When the water level is at about 10 gallons I turn off the mister. By the way, I do not bubble while the mister is on and I don't recommend bubbling during the mist, it's likely to be too agressive."
After misting the water into the washer I usually let it sit for maybe 5 minutes after turning off the mister. At this point all I'm looking for is a nice distinct layering. i.e. a definite water layer, maybe a small layer of scum (maybe 1 inch thick max), then a distict biodiesel layer. If the "scum" layer is much bigger then 1 inch then you probably have an emulsion and need to think about breaking that emulsion before moving on.
At Step 10, you can usually tell a lot sooner then 8 hours if you can turn the bubbles up to be aggresive.
I usually turn the bubbles on low and watch for any signs of emulsion, like white slimmy maonaisse type stuff
rising up with the bubbles, or an actual emulsion layer building up between the water and the bioidesel.
The slimmy stuff rising up with the bubbles happens immediately. The emulsion layer will occur within an hour or
two. If I see no signs of emulsion then I crank the bubbler up and let it go for about 24 hours. If I see signs
of emulsion then I drain the water, do another mist, and then bubble."