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Please correct me if I am wrong or being redundant here. I think this is the beginning of the new AAF method being employed by our friends across the pond. I have found very little reference to it here and thought it would be interesting to garner some comments.

Very simply, they add hot oil to methoxide (rather than the other way around) and pass 27/3 in 15 to 20 minutes.

Here is Paddygoat's video from about a year ago.

http://video.google.com/videop...4197553651520&hl=en#

Here is a link to the thread

http://www.vegetableoildiesel....176&page=1#pid114922

also search this site for jamesrl AAF method.

any comments?
 
Location: New Orleans | Registered: December 31, 2007Reply With QuoteReport This Post
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Here is the intro to the thread. The thread is only a few pages long.

By: paddygoat

Have I discovered a useful enhancement to biodiesel production technique?


For all the organic chemists out there, maybe you could read this and tell me your thoughts …..

As a bit of background information, a few months ago I produced a short DVD called ‘biodiesel production in the lab’ which, amongst other things featured a somewhat novel titration technique which involved titrating a known concentration of methoxide against vegetable oil. This technique has always worked well for me, especially when the hot oil is added to the methoxide rather than the other way around.

Today, I thought ‘what would happen if I titrated the hot oil against the methoxide, replicating more accurately what’s happening in the processor?’ Well, I did exactly that and found something very interesting.

The waste oil that I am using titrated at 35g potassium hydroxide per litre methanol, to be used at a ratio of 1:5 with the oil, using my ‘standard’ titration method above. But adding the oil to the methoxide I found that I could carry on adding more and more oil well past the 35g per litre mark and the reaction was behaving as normal. I added an extra 40% oil and still the reaction was going as normal. At this point I stopped as I wanted to have a good sample to photograph.

My own thoughts are that adding the oil to the methoxide produces a strong and quick reaction and a substantial amount of methyl ester is produced, especially when it reaches the ‘standard’ titration level. I would estimate that there is a 40% conversion happening at this point, only inhibited by the large presence of glycerol. But, thinking a bit more, if 40% of the veg oil has gone, then that 60% that is left only needs 60% of the ‘normal’ amount of catalyst?

The advantages of this method are that very much less catalyst would be required – approx 40% less (at least), which would save on chemical costs and, more importantly, make water washing very much easier as there will be less catalyst in the biodiesel prior to washing. Less acid would be needed to neutralize the catalyst and less chance of creating nasty emulsions.

What do people think? Have I discovered something useful? -- Paddygoat
 
Location: New Orleans | Registered: December 31, 2007Reply With QuoteReport This Post
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I tried adding oil to the methoxide once thinking I would get better conversion. The oil instantly turned into soap, I didn't do it again but maybe if I had reduced the amount of lye it might have worked.

In theory you should only need a small amount of catalyst but it seems to get pulled out of the reaction by the glycerin.
 
Location: Nimbin Australia | Registered: December 04, 2007Reply With QuoteReport This Post
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Just to clarify... it is well understood that good mixing is essential and the following poster uses a 2 stage eductor which is very efficient. However, what I find interesting is the introduction of the oil into the methoxide... as follows;

By jamesrl...

If you want to reduce reaction time use the AAF method.

Put 10% of the batch wvo into the reactor at reaction temperature, draw in 100% of the methoxide, engage eductor and pump in the remaining wvo, again at reaction temperature.
Mix for 15 mins and 3/27 test, if it passes go to demeth, if it fails mix for another 5 mins and retest.

The longest mix time needed in my experience is 25mins to get a 3/27 pass.

-- jamesrl
 
Location: New Orleans | Registered: December 31, 2007Reply With QuoteReport This Post
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quote:
Originally posted by dennislarock:
Please correct me if I am wrong or being redundant here. I think this is the beginning of the new AAF method being employed by our friends across the pond. I have found very little reference to it here and thought it would be interesting to garner some comments.

Very simply, they add hot oil to methoxide (rather than the other way around) and pass 27/3 in 15 to 20 minutes.

Here is Paddygoat's video from about a year ago.

http://video.google.com/videop...4197553651520&hl=en#

Here is a link to the thread

http://www.vegetableoildiesel....176&page=1#pid114922

also search this site for jamesrl AAF method.

any comments?


By my understanding the AAF method would require a eductor for most processor pumps. There are pumps sold by Murphy's that may not require an eductor, but would probably be recommended.

This is due to the actual mixing of the methoxide and the dry wvo. Also.....the oil must be dry. This would require a pre-heat/drying vessel, but is easily built.

Jamesrl does mention the AAF method here, but doesn't go into much detail. I'm going to join the other forum, but my reading is already started.

If I'm not mistaken (which I may be), Jamesrl is using the GL1 day design, but he may be using a push/pull design. He doesn't ever clearly answer this question.

James L
 
Location: Central Alabama (Marion Junction) | Registered: February 20, 2010Reply With QuoteReport This Post
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Eliminating a separate methoxide tank was one of their process changes aimed at meeting ATEX. It makes no difference on the processing times. It eliminates the methoxide transfer, which would be difficult (read 'more expensive') to do and still meet ATEX.

It's the paddle mixer that lets him process quickly. Paddle/prop mixing is much more efficient than pump mixing. The reason we see more pump mixing is ease of construction. It's a whole lot easier to build a safe processor using pump than it is to make a safe paddle/prop mixer.

Rick
 
Location: Cowboy Country | Registered: December 06, 2004Reply With QuoteReport This Post



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quote:
Originally posted by sinbad:
I tried adding oil to the methoxide once thinking I would get better conversion. The oil instantly turned into soap, I didn't do it again but maybe if I had reduced the amount of lye it might have worked.

In theory you should only need a small amount of catalyst but it seems to get pulled out of the reaction by the glycerin.


Sounds like you may have had wet oil. The pre-heat/dry tank is necessary for the AAF method to work.

James L
 
Location: Central Alabama (Marion Junction) | Registered: February 20, 2010Reply With QuoteReport This Post
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quote:
Originally posted by RickDaTech:
Eliminating a separate methoxide tank was one of their process changes aimed at meeting ATEX. It makes no difference on the processing times. It eliminates the methoxide transfer, which would be difficult (read 'more expensive') to do and still meet ATEX.

It's the paddle mixer that lets him process quickly. Paddle/prop mixing is much more efficient than pump mixing. The reason we see more pump mixing is ease of construction. It's a whole lot easier to build a safe processor using pump than it is to make a safe paddle/prop mixer.

Rick


Rick,

As I understand jamesrl is using a pump, and is injecting his methoxide. But he has a very special demeth system which is probably never going to be public. I would assume (yep..I used that word), that his design could be hazardous for the uneducated to use (possible error could cause bodily harm).

James L
 
Location: Central Alabama (Marion Junction) | Registered: February 20, 2010Reply With QuoteReport This Post
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The twin tub processor, who's designer is quoted in the first post uses paddle mixing. Using an eductor improves the efficiency, but not to paddle levels.

For a typical 40 gallon batch to pass 3/27 in 30 min:

propeller mixing - 0.07 hp
pump w/ eductor - 0.33 hp
pump w/o eductor - 0.75 hp

At these power levels, the methoxide does not need to be added slowly.
 
Location: Cowboy Country | Registered: December 06, 2004Reply With QuoteReport This Post
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Any thoughts on mixing 100% of the methoxide with 10% of the oil... then the rest of the oil?
 
Location: New Orleans | Registered: December 31, 2007Reply With QuoteReport This Post
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quote:
Originally posted by RickDaTech:
The twin tub processor, who's designer is quoted in the first post uses paddle mixing. Using an eductor improves the efficiency, but not to paddle levels.

For a typical 40 gallon batch to pass 3/27 in 30 min:

propeller mixing - 0.07 hp
pump w/ eductor - 0.33 hp
pump w/o eductor - 0.75 hp

At these power levels, the methoxide does not need to be added slowly.


Ah, yes...... you are probably correct. I haven't read up much on the person who came up with the method. I have read a lot from jamesrl which is having great success with an eductor (plus a multitude of other gadgets).

I agree a paddle type mixer would be more efficient, but having the need for a pump, I believe the pump is still the best cost for operation.

But this is my opinion only, and not based on any cost/time comparison.

James L
 
Location: Central Alabama (Marion Junction) | Registered: February 20, 2010Reply With QuoteReport This Post
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Let us assume everyone is using a 2 stage eductor and paddles Smile

Does anyone have a comment on mixing 100% of the methoxide with only 10% of the oil (at processing temperature) and then drawing the remainder (90%) of the oil into the methoxide?

Not trying to jack the mixing discussion... just very interested in the method of introduction.
 
Location: New Orleans | Registered: December 31, 2007Reply With QuoteReport This Post



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I’ve been following this AAF method for some time now, but actual step be step info is hard to come by. I sent a PM (on the overseas forum ) to jamesrl about a month ago but no response. Yesterday I asked the question on their forum, can someone explain AAF and this is the response today.

AAF: Basically add hot de-watered oil to methoxide, rather than adding methoxide to hot de-watered oil.
Can't find the thread where it first came up but it was suggested by Paddy to improve conversion time. Using the venturi to introduce the components to a GL based system meant that you have to first introduce a small amount of oil so the venturi can be used to suck in the methoxide, then follow that with the hot oil.

More info on static mixer use here:

http://www.vegetableoildiesel....d=14749&page=1#pid...

Seems this method has as much to do with static mixers, eductors and such as it has to do with when the methoxide and oil are added. From what I have seen at that site, most people use ¾ copper plumbing and pumps similar the NT one many of us use.

I have quizzed the chemist that I get much info from, but so far he is at a loss to explain why this reaction should be any more efficient that the one we use, this conversation continues!

James uses a flash eliminator to evaporate his methanol, his set up seems quit simple and is one that I will try for sure. He pumps the product to be demethed at 2 bar (about 30psi) at this pressure the methanol remains liquid. When the liquid is dumped at that pressure into an ambient pressure tank the methanol is flashed off and removed by his vacuum system. Tom

-EDIT this is a bit off topic but if you go to the link above and click on the word cliky, you will see pics of a very simple continuous flow processor.


" I don't know what I don't know until I know"
1994 GMC 6.5 Tubo 2005 Dodge ram 3500, 3 VW's 2000, 2002, 2005.
 
Location: Manitoba Canada | Registered: March 24, 2009Reply With QuoteReport This Post
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Biotom

I think this is the thread and the accompanying video is in there as well

http://www.vegetableoildiesel....176&page=1#pid114922
 
Location: New Orleans | Registered: December 31, 2007Reply With QuoteReport This Post
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Damn! the link works in the first post... sorry
 
Location: New Orleans | Registered: December 31, 2007Reply With QuoteReport This Post
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quote:
Originally posted by Biotom:
I’ve been following this AAF method for some time now, but actual step be step info is hard to come by. I sent a PM (on the overseas forum ) to jamesrl about a month ago but no response. Yesterday I asked the question on their forum, can someone explain AAF and this is the response today.

AAF: Basically add hot de-watered oil to methoxide, rather than adding methoxide to hot de-watered oil.
Can't find the thread where it first came up but it was suggested by Paddy to improve conversion time. Using the venturi to introduce the components to a GL based system meant that you have to first introduce a small amount of oil so the venturi can be used to suck in the methoxide, then follow that with the hot oil.

More info on static mixer use here:

http://www.vegetableoildiesel....d=14749&page=1#pid...

Seems this method has as much to do with static mixers, eductors and such as it has to do with when the methoxide and oil are added. From what I have seen at that site, most people use ¾ copper plumbing and pumps similar the NT one many of us use.

I have quizzed the chemist that I get much info from, but so far he is at a loss to explain why this reaction should be any more efficient that the one we use, this conversation continues!

James uses a flash eliminator to evaporate his methanol, his set up seems quit simple and is one that I will try for sure. He pumps the product to be demethed at 2 bar (about 30psi) at this pressure the methanol remains liquid. When the liquid is dumped at that pressure into an ambient pressure tank the methanol is flashed off and removed by his vacuum system. Tom

-EDIT this is a bit off topic but if you go to the link above and click on the word cliky, you will see pics of a very simple continuous flow processor.


I can't say why this reaction works better, but I view the reaction somewhat like I do when mixing acid and water. Always, and I mean always acid is added to water and not the inverse. This is due to the reaction. Acid will react based on the available acid to react. If a drop of acid is dropped in water, there is little to react, so it is safe. On the other hand if you put a drop of water in acid it is a violent reaction.

I see this as the same situation, just using different elements. When adding methoxide to wvo, there is little to start the reaction, but when the inverse is performed, the reaction takes off like gang-busters. Then all we must do, is keep the reaction going.

My analysis may be way off in left field, but it is the way I view the AAF method.

James L
 
Location: Central Alabama (Marion Junction) | Registered: February 20, 2010Reply With QuoteReport This Post
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More on mixing, as we know this is a very important aspect of biodiesel production. My chemist friend has sent this formula to get the optimum mix rate

NRe = nD2p/u

Where
NRe = Reynolds number
n = stirring speed
D = stirrers diameter
p = density of the liquid
u = viscosity of the liquid
He states that studies have shown the best reaction results are achieved at a value of 5000NRe Tom


" I don't know what I don't know until I know"
1994 GMC 6.5 Tubo 2005 Dodge ram 3500, 3 VW's 2000, 2002, 2005.
 
Location: Manitoba Canada | Registered: March 24, 2009Reply With QuoteReport This Post
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There might be some slight increase in initial solubility between the reactants on the second stage. Not everyone would have the same results as minor changes water content of the oil would have a major effect on the first stage.

So far the only ones quoted using AAF are selling expensive processors that are adapted to the process.
 
Location: Cowboy Country | Registered: December 06, 2004Reply With QuoteReport This Post



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quote:
Originally posted by RickDaTech:
There might be some slight increase in initial solubility between the reactants on the second stage. Not everyone would have the same results as minor changes water content of the oil would have a major effect on the first stage.

So far the only ones quoted using AAF are selling expensive processors that are adapted to the process.


Rick,

That is new information to me. I didn't know they even offered processors. I do know jamesrl will make an eductor or injector for anyone who wants one, for a price of course.

I don't see that as a bad thing really, but would like to have a drawing with all the new gadgets.

Maybe I'll make one. I do have Autodesk Inventor.

James L
 
Location: Central Alabama (Marion Junction) | Registered: February 20, 2010Reply With QuoteReport This Post
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James
-your analogy is a good one and in all probability it is something along that line that is happening, what puzzles me is why can’t we get a good explanation of what the actual reaction is. If you read on the other forum, this process seems to be taking over.
-On the same note, I recently read instructions for biodiesel production (I’m looking for it) that clearly states “add the wvo to the methoxide”. When I find the reference I will post it here. Tom


" I don't know what I don't know until I know"
1994 GMC 6.5 Tubo 2005 Dodge ram 3500, 3 VW's 2000, 2002, 2005.
 
Location: Manitoba Canada | Registered: March 24, 2009Reply With QuoteReport This Post
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