My bag filters were due for replacement so instead I purchased a 50 GPH fuge from Pa. Biodiesel. I make 150 liter batches with very dry oil that titrates around 2.5 in a standard appleseed processor with NaOH.Conversion is great, usually pass the 3/27 test with at least 4 ml of bio. After a 5% prewash and a few hours settle time/ drain, bio is heated to 160* and moved to a settle tank and bubbled with a fan blowing across the surface for 24 hours. Floating and soap stuck on the barrel is skimmed off. After 3 days settle time I moved it to centrifuge barrel and fired up the fuge. The original soap test showed 190PPM, after 8 hours of 90 psi fuge time I took the rotor apart to check progress, not much of anything in there. Water was well within spec but the soap only dropped to 120 PPM. If I ran my usual 1 micron bag filter that long soap usually ends up 35- 70 PPM. Can anyone tell me if the centrifuge can get the soap out and what do you do for technique? Thanks in advance.

WDP

Fabricator tried the fuge to remove soap with limited results. The problem he discovered was that the BD heats up as you are fuging which allows the soap to stay suspended in the BD. If there was a way to keep the BD cooled down it would probably work.

I think a better solution is to filter it through hardwood shavings. That's what I have been doing for the last 16 months or so and have had great results.

Looks like a fuge will not drop the soap to acceptable levels. It cleaned out some remaining glyricine and did a good job on the water but even with cool bio to start the fuge did not drop the soap below 100 ppm. Next batch I will run the fuge and filter at the same time and see what happens. My advice if you run the GL method, don't buy a centrifuge for soap final polish, it doesn't work.

WDP

This is a tough message to write. Probably because I tried it.

Biodiesel compatible parts are difficult to find in the fuging business. AND the centrifuge pump will heat up the biodiesel as you are filtering. Heat is not your friend. Cold biodiesel will be successful when running through the fuge. As the biodiesel heats up, it will actually start to pull soap from the fuge back into the biodiesel.

How about soap rough removal? I picked up a small centrifuge with an eye toward using it for gross soap reduction, then drywash resins for final soap removal. A way to invest in a piece of equipment to extend my resin life, I'd like to get the full rated lifetime per pound of resin to make that an even cheaper cost.

I would use the centrifuge for cleaning up the oil before processing. Settle out the soap for a few days after processing and filtering through hardwood shavings prior to using the resin as a final polish. Your resin will last much longer.

I have been doing some reading about coalacing as aprocess to speed up settling time. I started a thread hereIt may have been in the wrong place so nobody saw it. The idea appears good and a unit may be constructable by one of the forums more creative people. It would be good if it helps.

quote:

Originally posted by Eurocab:
I would use the centrifuge for cleaning up the oil before processing. Settle out the soap for a few days after processing and filtering through hardwood shavings prior to using the resin as a final polish. Your resin will last much longer.

I'll have to see if I can find a ready supply of hardwood shavings. I can get softwoods really easily, being the US Southeast, but hardwood seems more difficult. Most of the cabinet shops around here are working with "engineered lumber" and veneer these days...

I've commented before on the wood shavings, but I'll add this here because it was brought up, we lower our soap values with wood shavings after settling. I don't know if anyone has tried it, but we were running low on shavings a few weeks ago, and only had enough for about a foot in the bottom of our shavings barrel. we just happened to have a bale of nice second cutting hay (mostly grasses) laying around, so my partner dropped in about 4 flakes of hay on top of the shavings, then recirculated the 100 gallon batch for 6 hours as normal. worked like a charm! we usually do the initial filtering from the settling tank through the last batches spent shavings, but decided the hay worked so well, we would see how it would hold up. It lasted 400 gallons! I have no idea what the initial numbers were, but every batch finished at under 30 ppm. I'm not advocating using only hay, but I didn't have a regular supply of shavings, I'd be willing to try it. we'll be playing with this more in the future. I'll keep everyone posted.

we tried to polish with a centrifuge before using wood shavings, but had little improvement (nothing in the rotor). we do however run the fuge on our incoming oil to lower our titration values. This seems to really help.