Dry Washing

AAARRRGGGH!  I've had it with water washing my biodiesel!  Takes way to  much time and water to get a batch done.  In replacement I've ordered some Purolite PD206 from the folks over at Houston Biodiesel to dry wash my biodiesel.  Houston Biodiesel offers plans, parts, and the Purolite for the building for the dry washing towers with standard PVC parts for a very reasonable price.

In simple terms, you take your biodiesel that has been separated from the glycerol by product and run it through the Purolite PD206, at a certain flow rate, and clear filtered biodiesel comes out ready to be put in your tank!  In theory from process time to fill up time could be achieved in less than 5 hours, depending on the amount of biodiesel needing to be filtered.  Once the Purolite PD206 is exhausted you just back flush with methanol to remove contaminants, dry and reuse!  One pound of the Purolite PD206 can in theory process up to 100 gallons before needing to back flushed, I'll report back on that.

Some Newbie Issues

So, after having completed the Jerry Rig and processed 13 gallons I made some rookie mistakes.  After some research and assistance from the the folks over at the Infopop Biodiesel forums I was able to recover from my mistakes.  My errors were two fold that all occurred after a successful initial process.  Both issues were post process errors that were frustrating.

Error number one was in attempting to get as a complete/pure biodiesel.  I performed a test called 3/27 that is a good indicator to the completeness of the process or purity of the biodiesel.  This test requires that you mix 3ml of biodiesel to 27ml of methanol and observe for any settling or fallout of any unprocessed oil.  In my case there was minimal dropout less than 1/2ml based visual inspection at the bottom of my test jar.  Based on this there is a standard reprocessing recipe that will remove the remaining free fatty acids.  This recipe is to mix 1ml of lye with 50ml for every liter of biodiesel.  Well, I got just a wee bit to much lye in the recipe and my biodiesel turned to gravy or better known as soap!  Well drained this out of the processor and into a jug for future experimentation.  It would appear that the combination of this "gravy" and glycerol (the by product of making biodiesel) in about 3:1 ratio allows for the lye to drop back out.  Tested this out with a liter of "gravy" and got my biodiesel back.

Second situation was in washing 8 gallons of biodiesel.  During the first wash I introduced a bubbler to help in the washing of the biodiesel, a popular technique.  After a couple of hours of bubbling I came back to find this very milky liquid that turned out to be emulsion, essentially soap suspended in the biodiesel.  I attempted to wash a second time but the results were identical, so back to the forums.  There I found that bubbling during the first wash was not recommended and it should be used during the second or third wash at the earliest.  DOH!  But the forums were awash with cures for this to rescue the biodiesel.  The cure is the use of a salt water solution to break the emulsion bonds.  I simply mixed one gallon of hot water and some Kosher salt, about 1/3 of the box, and mixed it into the biodiesel.  Mixed for about 5 minutes then let the batch settle overnight and VIOLA!  This particular batch has been washed and dried and is now in the Beetle!