Finally getting my dry-wash/wood-chip set-up going.
I have a question - Does the BD coming out from your wood-chip process stay completely clear?
Some back-ground: Wood is kiln-dried shaving from hickory. Using a 20 Gal or so pool-filter.
I expected some resin through the first one or two bed volumes pushed through this set-up, but even after 4 bed-volumes, the BD coming out is hazy.
BD going in is good - pass 27/3 and titrates with almost no soap, filtered to 5um.
I have done a couple of experiments to see what causes this haze (at the small "bench" level).
1. Additional water wash. Water stays clear. No residual at the interface between BD and water. The BD continues to stay hazy after week long settling. Concluded that whatever is in the BD is not water soluble.
2. Let the hazy BD sit. Two weeks in a small bottle, no percipitation and the BD is still hazy.
3. Added 99% iso-propanol (about 10% by volume). Percipitate of whiteish material at the bottom after about two hours. Still waiting to see if the BD clears up.
4. Added 99% iso-propanol and did water wash. Quick separation, clear water. Looks like the BD may start to clear up a little bit. The theory would be that if the contamination is soluble in the alcohol, and then the alcohol is washed out with water, the contaminates stay in the alcohol/water solution. Still waiting for final result.
So any thoughts what may be going on? What is the contamination making the BD hazy?
My initial thoughts are resin from the wood or incompatible plastic dissolving by the BD in the pool-filter. I tested the main body of the pool-filter with BD for a long time (2 months) and saw no changes in the plastic. I did not test the valve-body/head though. Maybe the materials in the valve-body are dissolving and contaminates the BD...
Don't want to use this BD in my vehicles until I can figure it out.
Thanks for any suggestions.
What's the temperature of the hazy biodiesel? Is the biodiesel hazy before going into the wood chip dry wash? I'm thinking if it is cold where you are you might be hovering around a cloud point. You might take a glass beaker, put the biodiesel before the wood chip washing into the beaker, dump in some kiln dried wood chips, cover with plastic wrap with a rubber band to seal, warm it up to say 50-60 degrees centigrade for a while (few hours), filter out the wood chips and see if the biodiesel goes hazy. Try wood chip dry wash in a glass beaker. Do you water wash then dry wash? How did you get biodiesel with almost no soap? Lately to get my best small "bench" level results, I water wash to remove excess alcohol,catalyst & soap, then I dry the biodiesel, then I dry wash to remove mono and diglycerides. There's stuff in wood chips that will dissolve out, into biodiesel. But you probably know that. Does you hazy biodiesel clear up if warmed up. Thanks
Thanks for your reply.
The BD was crystal clear before it went into the wood chip wash. Not temp related, as the temp is 65+ F where I'm doing the sample tests, and the small sample of BD that I kept from before going through the wood chips is still clear.
I tried heating a small sample of the hazy BD before, but absolutely no change (went up to about 150 F).
The batch was processed in my normal manner, water washed (pump washed) and then dried. Wanted to start out the wood chip system with "clean" BD.
The sample with iso-propanol and water is starting to get a little clearer in the BD layer, but slowly. The sample with only iso-propanol definitely has "drop-out" collecting at the bottom.
Still think it is contamination from resins or from some other material that is dissolving in the BD. Even if I can remove the haze by alcohol "washing", it does not lead me to the source of the issue.....
Any change if you filter the hazy BD through 5µ ?
also, test the BD before and after the wood-chip column for water content.
Thanks for your suggestions.
However, the hazy samples have already been filtered to 5 um.
I also do not believe that the haze is from water contamination. In my experience, even with a fair amount of water, the BD will clear up given enough time to settle in a room temperature (65 F +) environment. One of the samples have been sitting almost a month now with no change.
Also, heating the sample up to 150 F has no effect. Normally, slightly "wet" BD will clear up at that temp.
I think a big clue is that I get fall-out when mixed with alcohol (iso-propanol). The fall-out is whitish/greyish and look "crumbly". Not a lot but in a 100 ml sample, I see maybe 1 ml or so.
Yes, your observations support the theory that the BD is leaching something from the wood chips.
Have you been able to isolate the drop out? When the drop out occurs have the sampled been cooled significantly?
Fuges have been used to pull out what folk were calling HMPE's (although in their concentrated form they melt at 50 deg C and go solid again as they cool below 44 deg C). This stuff sometimes drops out and sometimes stays in suspension, barely noticed. After fuging them a decent thick cake appears and this has a kind of waxy crumbly nature.
Could be barking up the wrong tree (or even barking mad) - who knows!
Ok, part of the mystery solved....
The contamination is definitely dissolved plastic/polymer material.
Disassembled part of the pool-filter today, and although all the main parts (body, riser tube, even the valve body) look great, the inlet "spreader" was apparently made from a different plastic material. It is pretty much gone...
(Note that I tested the body and riser with BD before I decided on using this set-up).
So now I have about 40 gal/170 l of contaminated BD. I estimate the part that dissolved to weigh 200g, giving me about a 0.14% (by weight) contamination of unknown plastic.
What to do with this BD? Haven't figured out a good way to really "wash" this contamination out, and I have no idea what it would do the the fuel system etc...
May just play it safe and discard it all...
I would try to clean it out with a glycerin wash, if that failed I would try to reprocess it, if that failed I would burn it in the shop furnace...
Simple schematic for a pump and heater control with a high limit
Sensor for the biodiesel/glycerin layer
I concur with Jon, but wouldn't do anything but add it to the fuel oil in a furnace or boiler. Vehicle injectors are too costly to service as compared with a burner nozzle if it needs replacing after burning plastic laced BD.
If you want to use wood chip dry wash, I suggest a 30 gal HDPE barrel and upflow the BD through the chips with a dip tube like we do with an upflow settling barrel.