I have always had trouble with cloudy winter fuel ever since I started using rice bran oil from a couple of local sushi bars. Last year I raised this subject and after a fair amount of discussion, I decided that the problem was that rice bran oil makes a biodiesel with quite a bit of wax in it. Typically the fuel runs great when warm and clear but clogs fuel filters when cool and cloudy. I tried blending with Petro-D and that seemed to lower the temperature at which problems develop but not by enough to be worth the cost and aggravation of going to the man for fuel.
BTW, I live on the central California coast, and cold to me is only the low 40s to the low 50s Farenheit, with 30s now and then.
It seems that this spring, the fuel is more waxy than ever, and some cloudy batches don't clear until heated to near 100F. All of my oil from both of my sources is the same brand of rice bran oil and has been for nearly 3 years now. It titrates consistently at 0.7 to 0.8. I have tried the 80/20, 80/20 2-stage base processing technique, which does seem to give me a better crack than 1 step processing, but does nothing to solve the wax problem. I am using 22.5% methanol and 7 grams+titration (KOH) for methoxide. I process 40 gal. of oil at a time and run 7 gallons of methoxide on the first stage and 2 gallons on the second stage. The oil is preheated to 160F.
After a couple of days of settling, basically when no more glycerine is falling out, I bubble wash with 15 gal. of hot soft water, replacing the water periodically until the water drains clear and the fuel is sparkling clear over the water. If I change the water every couple of hours, the fuel temp. rises above 100F during the wash process, which is why I can get clear fuel over water. I almost never make a noticable amount of soap and occaisonally have a minimal amount of emulsions.
Once I am satisfied that the wash is done, I drain the water out and spray dry the fuel for an hour or more.
The most problematic batches sometimes never clear, neither in the wash nor in the drying. I have actually had a batch or two that I could not get to clear without heating the dry fuel to over 100F.
Typically, the cloudy stuff will settle to the bottom of the container over the course of a few days and I decant the clear fuel off the top and use it, saving the cloudy stuff to use sometime when I can warm it up first.
Recently I tried the 3/27 test on samples of this fuel. I have attached a picture. It was taken looking down into the mouth of a babyfood jar. The test sample was somewhat cloudy with a residue forming that resembles butter. This buttery stuff does not disolve in methanol, but dissolves in a 50/50 mixture of isopropyl and toluene.
I have also run the 3/27 test on samples of the decanted clear fuel that was drawn off after allowing the wax to settle. Depending on whether these samples were from 1 stage or 2 stage processing, they sometimes have a few tiny droplets of oil (but not butter) or are perfectly clear.
A 3/27 test of the waxy layer under the clarified fuel makes lots of butter, as I expected.
I am now convinced that my choices are either to abandon the rice bran oil or put a fuel heating system on my truck ('04 Duramax that has lived most of its life on BD.) I have been reluctant to make modifications to the truck since I still have 30K on the drive train warranty.
BUTTER1.JPG (9 Kb, 43 downloads) butter in 3/27 test
I don't think rice bran oil is the problem.
It makes fine bio.
Need a bit more info...
At what temp. are you doing the 3/27 test?
It could be what is cooked in the oil is putting animal fats with very high melting point into the oil.
At what temp. is your fuel cloudy?
At what temp. does the fuel start to gel?
At what temp. does the oil get cloudy?
At what temp. does the oil start to gel?
03 Dodge 2500 B100 homebrew
79 Rabbit B100 homebrew
3/27 temp is around 65F. In the low 70s the butter becomes liquid.
The fuel clouds in the high to mid 40s. once clouded, it doesn't clear until it reaches the low 70s.
The oil is never as clear as the fuel, even at 150F, which is my processing temp. I ran some of the oil (at 150F) through a coffee filter to get it as clear as possible, but still it is not as clear as warm fuel. I am chilling the oil as I write this to check the cloud point.
Since I first posted here, I have run a minibatch with 3 processing stages just to see if I could get this high temp stuff to crack, and it doesn't work. I still get the buttery stuff. This 3 stage processing goes like this:
Stage 1: 80% of methoxide
Stage 2: 20% of methoxide
Stage 3: 20% of methoxide
This makes 120% of the the methoxide called for by the titration. For each stage, I reheated the oil to 150F.
The third stage yeilded a trace of glycerine, so I repeated it again for a total of 140% of the prescribed processing. The final pass yeilded no glycerine at all, but a 3/27 test of the resulting fuel yeilded the same buttery stuff in about the same quanity as in other tests.
It appears to me that my feedstock oil contains a component that has a high melting point, around 70F, and which does not convert to methyl ester with base processing.
Only on really hot days, and then only in the afternoon, is the fuel in my tank clear enough to run properly in my truck. That turns out to be pretty much worthless.
I suppose the next step would be to get a liter of the virgin oil from my restaurant before they cook anything in it, and see if I get the buttery stuff in a test batch of that.
Hummm, I run rice oil quite often and don't have that kind of result. Please keep us informed as to what you find with virgin oil.
2001 Dodge 3500 CTD running B100
Self appointed Minister Of Propaganda, Order Of The Semi Sealed Steel Drum Reactor
Currently washing and drying with a "Death Trap" heater.
It may be a couple of weeks before I get around to the virgin oil test, since my daughter is getting married a week from tomorrow, and I've got my hands full trying to keep the truck running and doing all the stuff that fathers do at a time like this.
I really think the solution may be to go to a fuel heater. I like my restaurants and don't want to give them up. But even with nights in the high 40s and around 50F lately, I am still having problems with wax clogging my filter. It even happened one evening after an 80 degree day. I set a warm clear sample on the fence early this morning, and within a couple of hours, it was slightly foggy with the ambient temperature at about 50F.
I'll probably just run petro on the trip to the wedding so I don't have to fool with it.
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