quote:

I probably missed it, but how do you fellows check for residual catalyst in your biodiesel?

This is the residual catalyst and soap test procedure:

For starters, I weigh out 0.5g glycerine, 5g unwashed bd, or 100g washed bd.

This is a modified version of the AOCS method Cc 17-79, soap in oil that I got from one of Gerpen's articles. This is a two step titration where you first titrate with HCl to neutralize the free catalyst and then you continue to titrate with HCl to free the Na+ or K+ from the FAA and salt.

The procedure is:
1. Dissolve sample in 100 mL isopropyl alcohol and 2mL 1% phenolphthalein indicator (in isopropyl).
2. Titrate with 0.01N HCl until you get the phenolphthalein color change (red to clear). This indicates that you have neutralized the free catalyst in the sample. Designate the titrant volume as "A".
3. Add 1mL 0.4% bromophenol blue indicator (in water).
4. Titrate with 0.01N HCl until the color changes from blue to yellow. This indicates that the pH is low enough that all of the soap should be split into FFA and salt. The strong acid that we are adding (HCl) is more strongly attracted to the metal ion on the soap than the free fatty acid chain. So, the metal ion combines with the Cl from the HCl to produce NaCl, and the hydrogen freed fromt he HCl converts the fatty acid chain to a free fatty acid. Designate this volume as "B".

Here are the equations.

(A x (conc. of HCl) x (MW of catalyst))/(1000 x (weight of sample)) = grams of catalyst/gram of sample

(B) x (conc. of HCl) x (MW of soap))/(1000 x (weight of sample)) = grams of soap/gram of sample

The MW of NaOH = 40.0, KOH = 56.1, NaOCH3 = 54.0
MW of sodium oleate = 304.4, potassium oleate = 320.56

To express your results to ppm (part per million), multiply by 10^6 (one million).

When the level of catalyst and soap are small, it is a good idea to use blank samples. Just prepare a second sample without glycerine, BD unwashed, or BD washed. Titrate the blank at the same time as the sample and subtract the quantities for the blank from the numbers from the sample.

You need to remember that methanol vapor is flammable. This means that when the vapor is present, there is the possiblity that a spark or other source of ignition can ignite the vapor. I think that the lower explosion limit (LEL) for methanol is ~3-6% in air. Although the immediacy of the situation called for you to turn off the heater, the spark produced from removing the plug could have been sufficient to provide an ignition source. I would suggest that people should use a 'kill' switch to shut off power to the BD equipment and that this switch be in a remote location. Without proper combustible gas detection equipment it is not possible to know the concentration of methanol in such a confined space as an enclosed garage. Please be careful out there!

dieseldan

Do you ever find any free caustic in well settled but unwashed biodiesel? By "well settled" I would think overnight should do.

Well I took my 40 gallons of biodiesel, heated it to drive off the methanol, added a BUNCH of Magnesol to soak up my way high soap content, and recirculated for 20+ minutes while stirring the stuff that settled to the bottom with a piece of PVC every 3 minutes or so to keep it moving (yes, it settles that fast).
Then I kept recirculating while I periodically opened another valve on the discharge side of the pump to fill my 50 micron sock filters. (I cut two 6 inch holes in the top of a 55 gallon HDPE-2 barrel and dropped my 50 micron 7 inch by 32 inch sock filters in the holes.) Not the fastest way to do it, and you definately have to be there to keep it going, but it works.
Then I hand pumped some through a 1 micron sock filter.
I was not happy with the clarity so I dumped it all back into the processor and piped in a whole house water filter. Unfortunately the only element I have for it is a 10 micron spun poly filter. I had it recirculating for 15 minutes while watching and it did not seem to be clearing things up. I went ahead and left it running on a timer for 1 hour. I'll look at it in the morning. I think I need to get some 1 micron spun poly filters ASAP.

Anyone have any suggestions on how to do the final polish filtering to get it "crystal clear?"

jim, did you do a 50/50 water/ bd wash test on the "unpolished" fuel? The cloudiness is likely soap or water. You can remedy both with more magnesol. Or,if the wash test comes up clean, you can be pretty sure it's water, just flash evaporate, heat evaporate, bubble dry, atomize or dry by whatever means you find most feasable.

diesel dan, are you currently employing that magnesol filteration settup? My inclination is that one pass through that magnesol filter won't be enough surface area contact to maximize the efficiency of the magnesol. We're doing 200 gallon batches at our coop and I'm curious what the flow rate will be if run on a system that recirculates the fuel through the magnesol filter several times. I'll do some experiments on this. For now, we let most of the magnesol settle out after 6-12 hours (before it can congeal), drain out what precipitate we can, then suck from the bottom valve of our conical wash tank (using a gear pump), and pump it through the top of the wash tank where we have a 20 micron sock filter hanging. We recirculate until it looks like we've gotten all the magnesol. Then recirculate thorugh a 10 micron in the same manner. And then through a 2.

I will build one of your described magnesol filters and do a comparison and post results shortly.

quote:

Originally posted by biodavid:
jim, did you do a 50/50 water/ bd wash test on the "unpolished" fuel? The cloudiness is likely soap or water. You can remedy both with more magnesol. Or,if the wash test comes up clean, you can be pretty sure it's water, just flash evaporate, heat evaporate, bubble dry, atomize or dry by whatever means you find most feasable.

I have not done any testing yet. I have a sample pulled, but an too tired to trust myself to do it right.
Could be soap.
Most likely not water. Oil was dry to begin with and there has not been any water anywhere near the batch. Even if it is, the discharge of the filter line is dropping the biodiesel 12 inches back into the open topped 55 gallon barrel that it is pulling from. Much like a spray/air dry setup.
-Jim

I just went out and stirred the barrel with the piece of PVC. The pump has been off for about 2 hours. It is amazing how readily the magnesol falls out of suspension.

When I came back in I took a look at the sample I pulled 2 hours ago. It is not crystal clear, but it looks really good. It is clear enough to read a newspaper through it. The sample jar is a 1 quart mason jar, so it is a pretty thick sample. I'll check for soap in the morning.

I found some .5 micron nominal 10 inch spun poly water filters for about $15. They also have 1 micron nominal ones for $3.95.

-Jim

quote:

Originally posted by neutral:
dieseldan

Do you ever find any free caustic in well settled but unwashed biodiesel? By "well settled" I would think overnight should do.

I usually let my bd settle over night (about 20 hrs), separate it, and test it.

I use 5g NaOH + titration. I never find it in the bd and rarely in the glycerine when I perform single base or acid/base. When I performed a base/base procedure, I did not find it in the bd either stage, but I did in the glycerine. The first stage I had 0.142g NaOH/g sample and on the second stage, I had 0.0152g NaOH/g sample. When I performed some acid/base/base experiments, test showed no free catalyst in any of the bd samples in any of the base stages, but it did make over twice as much soap in the second base stage. I also tested the glycerine, but I did not get any glycerine to settle on the second base stage. I did find it however when I experimented with 9g NaOH + titration. It had 0.11 %ffa, so I used 9.2 g of NaOH. The bd had 0.000276g NaOH/ g sample and the glycerine had 0.0252g NaOH/ g sample.

Thanks dieseldan, we can safely conclude therefore that it is correct to say that in a normal biodiesel reaction there will be no free catalyst left in the biodiesel after standing for some time. This should be reassuring to those using unwashed biodiesel.

It is surprising how often one reads that washing is done to remove, among other things, free catalyst. People do keep asserting things they don't really know. Myths persist.

biodavid

I vacuum filter through diatomaceous earth a few times. It was recommended by the Dallas Group to recirculate it a few times. I am still experimenting with magnesol, so I do not have a large set up. I am thinking about using a filter press on large quantities. The problem I am having with magnesol is that the bd it slightly high for ASTM standards in carbon residue and sulfated ash. I think this is due to the filtering. I have increased the times that I recirculate to see if that help, but I am still waiting on test results.

carbon residue test is an indirect test for conversion- is the fuel 'in spec' for total and free glycerol if washed the normal way? that is, is it the magnesol's fault or might it just happen to be offspec (common enough)?

Mark

quote:

is the fuel 'in spec' for total and free glycerol if washed the normal way?

Yes. The samples I did were liter batches where I did a bubble wash on half and used magnesol on the other. In all the bubble washed samples, the bd was in spec, but the majority of the magnesol samples were slightly higher in those two test. All the other test(flash point, viscosity, cetane, cloud point, copper corrosion, free gly, total gly, gravity, heat of combustion, and sulfur), are close in their results.

dieseldan, the sulpahated ash test is a measure of residual soap. I think the carbon residue test would also pick up soap.

Neutral

I've had bathches were the combined glycerine is close to max spec and the ash exceeds spec. The could be soap but could it also be mono & di-glycerides from low conversion? Magnesol doesn't seem to be able to "fix" mono & di-glycerides present in the FAME...

neutral

quote:

It is surprising how often one reads that washing is done to remove, among other things, free catalyst. People do keep asserting things they don't really know. Myths persist.

Myth has been busted!

This is what I found on those test:

D874 Standard Test Method for Sulfated Ash from Lubricating Oils and Additives
This test method covers the determination of the sulfated ash from unused lubricating oils containing additives and from additive concentrates used in compounding. These additives usually contain one or more of the following metals: Ba, Ca, Mg, Zn, K, Na and Sn. The elements S, P and Cl can also be present in combined form. Ash-forming materials may be present in biodiesel in three forms: abrasive solids, unremoved catalysts and soluble metallic soaps. The two former can contribute to injector, fuel pump, piston and ring wear, and to engine deposits. Soluble metallic soaps have little effect on wear but may contribute to filter plugging and engine deposits.

D4530 Standard Test Method for Determination of Carbon Residue (Micro Method)
This test method covers the determination of the amount of carbon residue formed after evaporation and pyrolysis of petroleum materials under certain conditions and is intended to provide some indication of the relative coke forming tendency of such materials. This test method is applicable to petroleum products that partially decompose on distillation at atmospheric pressure and was tested for carbon residue values of 0.10 to 30 % (m/m). Samples expected to be below 0.10 %(m/m) should be concentrated by an initial distillation to remove the top 90%. Carbon residue gives a measure of the carbon depositing tendencies of the fuel. While not directly correlating with engine deposits, this property is considered an approximation. Most biodiesel boils at roughly the same temperature, and it is difficult to remove the top 90%. Thus, a 100% sample of biodiesel must be used even though its carbon residue value is expected to be below 0.10%.

Is it possible that the carbon residue could be contributed to diatomaceous earth? I was filtering through a 1 micron filter sock, but it was absorbing a lot of bd. To get as much bd as I could, I would ring the sock slightly. I came across a vacuum filter and that is what I've been using since. I am also thinking that the sulfated ash might be due to the magnesol getting through the filter.

Both sulphated ash and carbon residue will pick up diatomaceous earth and magnasol as well as soap.

The best way to use diatomaceous earth is with a vacuum filter on a flat plate filter funnel with small holes. This supports the filter paper and prevents damage. The first pass through the filter will show some earth gets past the filter while it beds in. Once the diatomaceous earth has made a thick, stable layer on top of the filter paper it should work properly. It is a good idea to put another sheet of filter paper on top of the diatomaceous earth layer to ensure that the layer is not disturbed when pouring in the oil.

neutral

Thanks for the info.

Foxcreek

The sulphated ash test could not pick up mono and di glycerides because they would burn completely, having no metal in them, unlike soap which contains sodium.

Neutral,

So does that mean that my above spec on ash would be residual soap and/or glycerine? If it were glycerine, would that mean some of the material picked up by the glycerine would contribute to the ash content, not just the glycerine itself?

Thanks...

A couple of pages back I posted good results with a DrP batch of Magnasol cleaning. It worked great.

Now I've been working with a larger batch (25 gal) and mixed it with the pump using a down tube into the barel to keep it from setteling and I'm sure that the magnasol has done the job.

The problem I'm having is in seperating/filtering the mag out. I tried circulating it through filter socks from 50 micron to 25 micron and the inside of the socks get a buildup and stop up.

I've tried to let it settle and am drawing out of the tank about an 1 or so off the bottom. Tried pumping slow as not to stir it back up and the batch is still a little cloudy and still stops up the socks.

Is this method better suited to a conical bottom tank. I have a flat bottom but tilted tank.

I went to heat it back up as it's about 25f here and that started a convection effect thus churning. Shut that down and I'm looking at either buying a 60gal conical bottom plastic tank of buying some 16ga and making a bottom for the tank I have. This would accomodate being able to effectivly drain the mag sluge from the batch.

Am I barking up the right tree?

Is anyone else doing this with a flat bottom tank?

Open for input...