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Graduated conical tube for 3/27 test
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FYI: I have adopted the base/base method but would like to refine the proceedure by measuring the amount of unconverted VO after the first step and calculate the amount of additional lye and methanol necessary. Looking for a way to actually measure the unconverted VO I recently purchase some graduated conical centrifuge tubes (two different types). One is made for the petroluem industry to measure water in oil and measures down to 0.05 ml while the second is made for measuring butterfat? and only measures down to 0.1 ml.
Attached is a picture of the 1st showing the settled VO after the first base treatment. It measured about 0.7 ml of the 8.3 ml added to give a 8.5% unconverted.
In my prelimiary trials a few droplets cling to the side of the tube without centrifugation so I may be forced to build a simple handcrank centrifuge.
I had to purchase several of each so if some of you are interested let me know.

This message has been edited. Last edited by: Shaun,
 
Registered: March 23, 2004Reply With QuoteReport This Post
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Anybody else having trouble getting the picture to download. All I can get is about the top inch of the photo and the download stops.

Norman
 
Location: Lincoln, NE | Registered: April 10, 2006Reply With QuoteReport This Post
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yep I only get the top inch or so.

You may have to reload the picture.
 
Location: East Yorkshire | Registered: January 14, 2006Reply With QuoteReport This Post
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Rick G

Keep in mind the impact of diglycerides and monoglycerides when calculating addition catalyst/methanol needed in the second step.

TGs convert "step-wise" to DGs and then to MGs and then to methyl esters (biodiesel). Even if no more TG shows up in the 3/27 test, you must complete the conversion of the majority of the DG and MG that are still in the solution.

The major component that will show up in the 3/27 test is unreacted triglycerides. I have seen reasearch papers that say 100% of the TG will be reacted at the 95% conversion point.
But, the reaction needs to achieve about 98% conversion of the available TG to meet ASTM specs.

Therefore, even though the 3/27 shows either no or very little settlement, you still may have to drive the reaction another 3 or 4 percentage points to achieve the conversion you are seeking.
 
Location: Illinois | Registered: February 21, 2006Reply With QuoteReport This Post
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quote:
Originally posted by producer:
(Excellent description of stepwise chemistry SNIPPED) I have seen reasearch papers that say 100% of the TG will be reacted at the 95% conversion point.
But, the reaction needs to achieve about 98% conversion of the available TG to meet ASTM specs.


Point of clarification, Producer: did you mean to say that all triglycerides can be reacted at only 95% total conversion, but ASTM spec calls for 98% conversion of total glycerides (including mono- and di-)?


George Reiswig
North by Northwest Expedition
1983 Mercedes 416 Doka
2005 Jeep Liberty CRD
http://www.4x4wire.com/mercedes/nnw/intro.htm
 
Registered: December 26, 2005Reply With QuoteReport This Post
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greiswig

It is the triglycerides (TG) in the oil that converts to methyl ester (ME) in a base catalyzed, transesterification process.

To me, the definition of conversion amounts to "what percent of the TGs were converted to ME".

In reality the conversion is divided into several parts or steps; ie, what % of TG is converted to DG; what % of DG is converted to MG; and, what % of MG is converted to ME?

At the beginning of the reaction (using a "pure" oil) the following concentrations are present: TG = 100%; DG = 0%; MG = 0%; and ME = 0%. Near the end of the reaction, at a time when virtually all of the TG have reacted to form other products, an estimate of the concentrations of the reactants and products would be something like: TG = <0.5%; DG = 2%; MG = 3%; and ME = 95%.

Biodiesel that meets ASTM requirements may have a profile similar to: TG = <0.25%; DG = <1%; MG = <1.5%; ME = >97.5%. (The ASTM spec's actually specifiy allowable concentrations of free and bound glycerol present in the methyl esters. Percent conversion is not an ASTM standard.)

The 3/27 test identifies compounds that are not soluble in methanol. TG is not soluble in methanol. DG are partially insoluble in methanol. MG and ME are soluble in methanol. Any fallout seen in the 3/27 test is (ignoring any impurities that may have been in the oil) primarily TG and secondarily DG. And, since almost all TG will have been converted to DG, MG, and ME by the time the overall reaction is only about 95% complete, then a failure of the 3/27 test almost surely means the fuel will not meet ASTM spec's.

Conversely, fuel that passes the 3/27 test can not be quaranteed to meet ASTM spec's, but it will be very, very close.
 
Location: Illinois | Registered: February 21, 2006Reply With QuoteReport This Post



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Great explanation! Thanks for taking the time to write it down.


George Reiswig
North by Northwest Expedition
1983 Mercedes 416 Doka
2005 Jeep Liberty CRD
http://www.4x4wire.com/mercedes/nnw/intro.htm
 
Registered: December 26, 2005Reply With QuoteReport This Post
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Producer,

I appreciate your knowledge and the fact that you are looking at the studies.

quote:
Keep in mind the impact of diglycerides and monoglycerides when calculating addition catalyst/methanol needed in the second step.

TGs convert "step-wise" to DGs and then to MGs and then to methyl esters (biodiesel). Even if no more TG shows up in the 3/27 test, you must complete the conversion of the majority of the DG and MG that are still in the solution.

The major component that will show up in the 3/27 test is unreacted triglycerides. I have seen reasearch papers that say 100% of the TG will be reacted at the 95% conversion point.
But, the reaction needs to achieve about 98% conversion of the available TG to meet ASTM specs.

Therefore, even though the 2/27 shows either no or very little settlement, you still may have to drive the reaction another 3 or 4 percentage points to achieve the conversion you are seeking.


Can you direct us to that study? Do you have some GC tests and 3/27 results to go along with that?

My understanding of an equilibrium reaction is that it will never go to 100%. It is true that there will still be some di's and more mono's while tri's are very low. But each of the individual reactions is affecting the EQ point of each of the others. It is not like all of one reaction happens, then the other one starts.

My testing, which is only based on one feedstock, and one seris of 3 batches, shows that the fail point for 3/27 is very near ASTM spec. If you recall the three batches I had tested taht you commented on here.

For batch 3 to pass, and it is a cloudy pass with no fallout, the temp. needs to be at least 68f. This is .2548% mass percent total glycerol.

Further, Bob A, who has done lots of tests on home brew and compared the GC with 3/27 says the 3/27 testing cutoff is pretty close to the ASTM spec in other cases, as it was my case.

From talking to Bob and Randal Von Wedel (set aside what you think of phlip, he has done lots of work in BD research and is very well qualified/respected in the field), the one major caveat with 3/27 is that there is some variation in the ratio of Tri to Di to Mono in various batches. What causes these variations is explained by them as only "process variations". By this I gather they mean different amounts of catalyst, methanol, stages, or temp. etc.

So, it will never be an absoute predictor of GC test results in terms of total glycerol, it is a pretty good estimate. I'd say Warnquist was both very smart, and very lucky that it works as well as it does!

Andrew


Andrew

http://biodieselcommunity.org
03 Dodge 2500 B100 homebrew
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Location: Northern California | Registered: February 27, 2006Reply With QuoteReport This Post
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quote:


So, it will never be an absolute predictor of GC test results in terms of total glycerol, it is a pretty good estimate. I'd say Warnquist was both very smart, and very lucky that it works as well as it does!

Andrew


I totally agree with these statements, Andrew.

IMHO, the 3/27 is the best thing since the Collaborative Biodiesel Tutorial for homebrewers, but should NOT be counted on by commercial producers (of any size) as a go-no go gauge for ASTM level conversion.

The ASTM selects their test methods carefully, and for now, they identify a cool-on column GC method for determining the free and total glycerine levels in biodiesel.

That being said, the 3/27 test is an EXCELLENT test (properly done as described on this forum)for homebrewing, non-commercial users to assess how well their batches are converted.

I also agree with the point that both producer and Andrew are making - that any significant level of tri-glycerides in a sample of methyl esters suggests less than ASTM conversion. It seems that when you have pushed the reaction as far as it needs to go to meet the ASTM spec, barely a tri-glyceride survives unscathed.

FWIW, I don't recall seeing any samples on our GC that had virtually NO remaining tri-glycerides, but failed ASTM due to elevated levels of di's and mono's. Typically, mono.s is the last peak to come down (as producer is pointing out), but only does so at the expense of the remaining tri's.

Andrew, you have really helped all of us further our knowledge of the 3/27's abilities and have been a tireless proponent to those seeking a better understanding of its strengths and weaknesses. Including the Sewer Rat. Nicely Done. That what makes this forum so great!

Bob in Berthoud (soon to be Bob in Denton)

BTW, I have been using some nifty 15ml graduated centrifuge tubes to perform the "1/9 test" - here's a look...the "PASS" and "FAIL" were verified by our GC. The cloudy pass was at 0.22% bound glycerin - the clear pass was at 0.11% bound glycerin. The Bad fail was at about 0.9% bound glycerin, the not as bad fail was at about .4% bound glycerin. - all were washed and dried. Ambient temperature was about 22C (72F). The pictures aren't the best - but just the best I had. Smile



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Location: Moncure, North Carolina | Registered: April 21, 2001Reply With QuoteReport This Post
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quote:
Originally posted by Andrew Morris:
Can you direct us to that study? Do you have some GC tests and 3/27 results to go along with that?
Andrew


Three studies that you might want to look at are:
1)"Kinetics of Transesterifcation of Soybean Oil" by H. Noureddini and D. Zhu.
2)"Fatty Esters from Vegetable Oils for Use as a Diesel Fuel" by B. Freedman and E. H. Pryde.
3)"The Modelling of the Biodiesel Reaction" by Micheal Allen and Gumpon Prateepchaikul.

The Freedman paper presents a graph showing product composition (wt%) vs molar ratio of MeOH. Extrapolating the results of the graph, one can conclude that as the % composition of the ME approaches 95, then the % composition of the TG approaches 0. From that, I speculated that all of the TG will have been converted to DG and MG before the full conversion to ME is complete.

Noureddini lists individual reaction rates "k" in both the forward and reverse directions for each of the three stepwise reactions and for the overall conversion reaction. Energies of activation of each step are also shown.

This paper also contains excellent information about rates of the reaction at different times and the effect of mixing on the reaction.

Allen's paper, like Noureddini's discussed mathematical modeling of the reaction.


These papers provide some actual research data and a lot of computer modeling and simulation.

Your results, that you linked in your above posts, provided real life data through actual production and analytical results. Your data fit right in with the data in the above citations - providing validation for both.

The comments made about the 3/27 test passing and failing etc., I think, are still valid. To me the research suggested it, and your data provides a point of confirmation.

I do not have a GC so I will not be able to produce results as you have.

Keep in mind that no matter how many tests you run or how much data you personnally accumulate someone will always be able to come around and suggests you run more tests. You will never have all the data, so you must work with what is available. For me, that means a sample that shows drop out from a properly conducted 3/27 test in all probability will not meet ASTM spec's. Samples that pass 3/27 will be very close to ASTM quality. Isn't this exactly what your results show?

Given the choice between the two, research modelling vs actual results, one has to go with the actuals. It is nice that there is such good agreement between the two, as occurs in your results.
 
Location: Illinois | Registered: February 21, 2006Reply With QuoteReport This Post
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quote:
Originally posted by producer:
Given the choice between the two, research modelling vs actual results, one has to go with the actuals. It is nice that there is such good agreement between the two, as occurs in your results.


I *love* it when science works.

The papers you cited are excellent producer, I have read only two of the three and now am looking forward to the third.

Nice Post.

Bob


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Location: Moncure, North Carolina | Registered: April 21, 2001Reply With QuoteReport This Post
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producer,

thanks for the listing on the papers.

quote:
Keep in mind that no matter how many tests you run or how much data you personnally accumulate someone will always be able to come around and suggests you run more tests.


Yep!

quote:
Given the choice between the two, research modelling vs actual results, one has to go with the actuals. It is nice that there is such good agreement between the two, as occurs in your results.


Me too.

quote:
The 3/27 test identifies compounds that are not soluble in methanol. TG is not soluble in methanol. DG are partially insoluble in methanol. MG and ME are soluble in methanol. Any fallout seen in the 3/27 test is (ignoring any impurities that may have been in the oil) primarily TG and secondarily DG.


I agree with most of this, but it is not so black and white to say that TG is not soluable. It's low soluability appears to vary with temp. At lower temps. an even lower percentage of TG seems to be soluable. Also, it would seem that less DG is soluable at lower temps.

All of this is based on the fact the results of this test change dramatically with changes in temp.

Andrew


Andrew

http://biodieselcommunity.org
03 Dodge 2500 B100 homebrew
79 Rabbit B100 homebrew
 
Location: Northern California | Registered: February 27, 2006Reply With QuoteReport This Post



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Bob,

Thanks for the encouragement. And for all the support you have provided to the homebrew community by being a bridge to the commercial world with all its fancy gizmos (GC)!

Two questions though:

How do I get my hands on some of those "nifty 15ml graduated centrifuge tubes"?

Do they make bigger ones?

Andrew


Andrew

http://biodieselcommunity.org
03 Dodge 2500 B100 homebrew
79 Rabbit B100 homebrew
 
Location: Northern California | Registered: February 27, 2006Reply With QuoteReport This Post
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quote:
Originally posted by Andrew Morris:
All of this is based on the fact the results of this test change dramatically with changes in temp.
Andrew


I got a dramatic look at how temperature affects the 3/27 last month in Pennsylvania. I was hanging out with Matt Steinman ("farmer" on this forum) in his shop at Dickinson College that was about 50 or 55F inside (I'm guessing.) the results were *dramatically* different than when we let the samples warm to 70F or so.

I strongly suggest that the test be done in the 65F to 75F zone.

Maybe it's time to move back to Maui?


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Location: Moncure, North Carolina | Registered: April 21, 2001Reply With QuoteReport This Post
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Bob,
Those are some sweet pics! I loved seeing that!
Nice to see some more tests too compared w/ a GC (You realize we're all rabidly jealous of that thing....)

Have fun out in Texas...
-Graydon




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Location: Utah | Registered: October 08, 2004Reply With QuoteReport This Post
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Hi Andrew:

Here is a link to cynmar where I buy my Graduated centrifuge tubes. The 15ml ones work just right, enough head room after stopper.

http://www.cynmar.com/item_detail.aspx?ItemCode=11520824

They work very well. Good company, I have ordered most of my chemistry supplies from them. On the tubes, ask them that they have full marking down to the last 0.1ml. Most of mine have been fine, but two did not have the last two marking at the bottom.

I think that I ordered size #0 stoppers for them(check for correct size), the stoppers are very nice. I can fill a number of tubes with the methanol ahead of the batch, Then drop in 1ml of bio as I take samples without having to measure the methanal again. Nice for mixing and stops all fumes.

-Jim


86 MB 300SDL
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Location: Mechanicsville, MD | Registered: March 26, 2006Reply With QuoteReport This Post
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If I have a centrifuge, can I put these cylilnders in it to speed up the 3/27 test results?
Wags
 
Location: waterloo, il | Registered: July 24, 2006Reply With QuoteReport This Post
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quote:
If I have a centrifuge, can I put these cylilnders in it to speed up the 3/27 test results?


Yeah! Shake, shake, shake...10,000rpm for 30 seconds...DONE! Every last trickle in one bead at the bottom!
 
Location: Southern WI, USA | Registered: May 18, 2006Reply With QuoteReport This Post



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Jim,

Thanks very much!

Andrew


Andrew

http://biodieselcommunity.org
03 Dodge 2500 B100 homebrew
79 Rabbit B100 homebrew
 
Location: Northern California | Registered: February 27, 2006Reply With QuoteReport This Post
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Hi Wags:

Yes, they are for standard size test tube centrifuge. They allow you to measure the precipitate accurately.

Here's a hand version centrifuge:
http://www.cynmar.com/item_detail.aspx?ItemCode=CVT53882

In my experience the JAN test will precipitate out the TG and DG drops in less then 10 min anyway. Therefore, saving the cost and desktop space on the electric centrifuge. Of coarse, in chemistry labs the centrifuge is way cool. When you are trying to measure the salts/ions that would precipitate in say hours, the centrifuge will push them to the bottom in 3 min.

-Jim


86 MB 300SDL
05 Jeep Liberty CRD
 
Location: Mechanicsville, MD | Registered: March 26, 2006Reply With QuoteReport This Post
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