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Just can't make it work
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Well, I just don't seem to have the magic touch. I have never been able to get the acid/base process to work properly, and I don't know why. Here's the latest attempt, which went exactly the same as all other attempts, even when I had tried draining between batches.
    Appleseed processor, BIG pump
    Oil - 205 liters of well-dried soy, titrated at 10.5 KOH (heated to 250F, then maintained there for 45 minutes while bubbling with nitrogen..passed dry test without a single bubble on a 300F hot plate)
    Acid stage - 24l methanol, 250ml of 98% H2SO4
    Reacted 10 hours, intermittent cycle of pump, reactor sealed. Starting temp 137F, max temp 145F, ending temp 142F.
    End titration - 2.65
    Base stage - added 15l methanol with 2286g KOH without draining
    React for 2 hours. Warnqvist FAIL.
    Reprocess with 4l methanol and 160g KOH for 1 hour. Warnqvist FAIL
    Reprocess with 4l methanol and 100g KOH for 1 hour. Warnqvist PASS


The only thing I can think of is that my acid or my methanol are bad every time I've tried this. The acid is the only commonality, since I am still using the same gallon of it that I've used from the start. I know there were a couple of attempts at acid/base when even my base/base processes weren't working well because the methanol was contaminated with something (probably water) that I didn't know about until I switched barrels and suddenly everything was working peachy.

I don't get it.


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
-your not alone on this one, many people have problems with base reacion after esterfication, In this case, you have used too much acid in my opinion, the more acid you use, the more caustic you have to use to neutealize it, that process makes water, the ae process makes water and the following base process makes water ( am I staring to sound like a broken record? Big Grin). the caustic in the base stage will turn all remaining FFA's to soap, as well the soap makeing reaction will compete with the transesterfication process. So really the enemy here is water, the only water that you can contorl is that which is brought into the process in wet wvo, and by incraesed amounts of acid.
-for your next batch, concider that the methanol you used in the ae process is 30% compromised, and add that much more in the base reaction. You will be surprised at the resut
-there is no need to drain anything when you start the ae process with T 10 wvo. Why did you stop the ae process at 2.65T Was it finished at that point, if so the wvo was not as dry as you think. It's water that stops the ae process, lack of heat will also cause it to stop, but with heat, all you have to do is reheat to reactivate the process. Tom

EDIT -forgot to mention, when you do the finnal T after ae, base the caustic amount on the full load in the processor, in your case, on 229 ltr. This point was made on the acid thread by Double D. this will improve the base reaction as well.


" 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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quote:
EDIT -forgot to mention, when you do the finnal T after ae, base the caustic amount on the full load in the processor, in your case, on 229 ltr. This point was made on the acid thread by Double D. this will improve the base reaction as well.



Now that just makes good sense. Wink I never thought about basing the catalyst on the total amount of fluid in the processor after esterification. That explains some of my woes with this two stage process. I guess I will have to give it another try soon.
 
Location: Chambodia | Registered: December 31, 2007Reply With QuoteReport This Post
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Eurocab
-the other thing you should look at, and it makes a big differance, is add more methanol in the base stage to make up for the watered down methanol coming from the ae process, I did this on the last two batches, it really works. 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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Biotom,

Thanks for the reply. I am pretty sure the oil was dry going into the processor. I tested it, and it didn't bubble even a little on a very hot hot plate.

As for using too much acid, I've read through the threads where calculations are put forward, and tried to interpret them so as to come up with the correct amount. In this case, the calculation was ((Starting titration, 10.2) - (titration goal, 3)) * .17, which came out to 1.224 ml acid per liter oil. Oil was 205 liters. Can you show me where my calculation is off?

This also explains why I assumed the AE (acid esterification) was done: my goal was titration of 3, and I was below that after 10 hours of time in the processor.

The only time that I've come close to getting this to work was when I had taken the un-de-methanol'ed byproduct of a previous base-stage reaction and mixed it into the reactor after the AE stage, let it settle out, and drained it. My theory was that it would help pull some of the water out, and possibly neutralize the FFA even further along with any remaining sulfuric acid. But there is not a clean layer separation when you do this, so it's tricky, and even though it worked somewhat better, I still had to reprocess.

If I always have to use substantially more methanol, I'm not sure the cost is worth it: I can use 16% in a base-base reaction even with titrations around 10, and pass quality tests every time. My yield is not THAT much better with AE at the front end, and it adds hours and energy cost to the mix, plus I use more methanol?

What puzzles me is that other people are making it work but I'm not. That's what takes me to looking at the variables, and the one left that sticks out seems to be the quality of my sulfuric.


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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quote:
Originally posted by Eurocab:
[QUOTE]EDIT -forgot to mention, when you do the finnal T after ae, base the caustic amount on the full load in the processor, in your case, on 229 ltr. This point was made on the acid thread by Double D. this will improve the base reaction as well.



Interesting...in this case, that would have added 300g to the base amount that I would have used. My reasoning for basing the base amount on the oil volume was that the added volume was basically methanol, but I think what you're saying is that's not true: the added volume is methanol plus acid, so the added volume can't be assumed to be neutral. Right?


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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quote:
Originally posted by greiswig:
quote:
Originally posted by Eurocab:
[QUOTE]EDIT -forgot to mention, when you do the finnal T after ae, base the caustic amount on the full load in the processor, in your case, on 229 ltr. This point was made on the acid thread by Double D. this will improve the base reaction as well.



Interesting...in this case, that would have added 300g to the base amount that I would have used. My reasoning for basing the base amount on the oil volume was that the added volume was basically methanol, but I think what you're saying is that's not true: the added volume is methanol plus acid, so the added volume can't be assumed to be neutral. Right?


It's not about the methanol acidity.
It's about the 1ml of oil/acid/methanol mixture your titrating being a represenative sample of whats in the processor.
When running a base only stage your still calculating the base amount to use on the total volume in the tank that has been titrated, it just happens to be oil only.
 
Location: central virginia | Registered: March 13, 2008Reply With QuoteReport This Post
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greiswig
-I posted this picture on another thread yesterday, it shows how much moisture can be in the wvo even after it passes hpt.



-the reason I said too much acid, is because on the acid thread, it has been shown that we use toooo much acid for ae. the more acid you use, the more water that is created, so keep it to a minimum.
-the amount of extra methanol you have to use is minimal, and the results in the form of increased yield are well worth it, but there is for sure a learning curve here. The fact that you didn't notice a sizeable increase in yield would be the result of an incomplete ae process. Really, you can't compare the yield from t10 wvo base processed, and the same wvo processed with ae/base. I process 7000 ltr a year this way, and I'm not about to lie to you or anyone else. 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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Originally posted by Biotom:
greiswig

-the reason I said too much acid, is because on the acid thread, it has been shown that we use toooo much acid for ae. the more acid you use, the more water that is created, so keep it to a minimum.
Tom


This is close, the sulfuriic itself doesn't directly contribute to creating water. The combining of methanol and Free Fatty Acid, creates the water.
You can only create as much water as you have FFA in the batch. Though the sulfuric does catalyse the reaction which results in water.

Greiswig,
Using the __ ml H2SO4 x 2.25 gives you an ending Titration of 2.75ml KOH
This is based on your using 1.22ml H2SO4 per L of oil.
Your ending titration was 2.65ml which indicates that you esterified about all the FFA that you could in that batch (unless some caustic wat already in your processor). Basing your caustic on the total load in the processor after AE should get you to higher conversion in a single base stage (although maybe not at 19% total methanol). That would limit the amount of bio lost during draining. A titration of 10ml KOH is, in my opinion about the point where AE starts to show it's advantages, although negligable against a well run base/base process.

Using less acid in the AE stage should effectively lower your titration going into the base stage, resulting in less caustic being used which should reduce your soap production, increasing your yield.
 
Location: central virginia | Registered: March 13, 2008Reply With QuoteReport This Post
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DoubleD
-when the sufuric acid is neutralized does this not create water?


" 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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quote:
Originally posted by Biotom:
DoubleD
-when the sufuric acid is neutralized does this not create water?


Yes it does at the beginning of the base stage when the caustic is introduced.
My mistake Tom, I thought you were saying during the esterification stage. Frown
 
Location: central virginia | Registered: March 13, 2008Reply With QuoteReport This Post
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quote:
Originally posted by Biotom:
(SNIP)
-the reason I said too much acid, is because on the acid thread, it has been shown that we use toooo much acid for ae. the more acid you use, the more water that is created, so keep it to a minimum.


Tom, et al,

I'd love to keep the acid to a minimum for any number of reasons. Can someone point out how much less I theoretically should have used, or point me to a really good formula for determining it? Clearly the one I used called for more acid than you guys have been using?

Thanks, all!


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 looks like you may be able to use as little as .27ml H2SO4 per liter of your T10.5 KOH oil with 12% methanol used in the acid stage.

This comes from an experimental formula that was devised from several peoples results in the really long acid thread.
The formula is kind of long as well. You can be among the first to try it though and report your results if you so choose.

The formula is based on selecting a molar ratio of Sulfuric:FFA that gives you the results you desire, kinda, sorta.

The formula is:
((AxBx.4)+B)x40.4 = ml acid to use per liter of oil.
(B/A)x54 = ml Sulfuric to use per liter of oil.
where A = FFA in the ratio of FFA:Sulfuric (15:1, A=15)
where B = titration in KOH x .0178

Using your titration of 10.5ml KOH, and 12% methanol in the acid stage this gives us .27ml H2SO4.
A ending T of .6ml KOH would indicate a close to complete reaction.

If you choose to give it a go, you could add a bit more acid to be safe since this formula has yet to be tested. Your ending titration should indicate the effectiveness.
 
Location: central virginia | Registered: March 13, 2008Reply With QuoteReport This Post
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quote:
Originally posted by Double D:
Greiswig,
It looks like you may be able to use as little as .27ml H2SO4 per liter of your T10.5 KOH oil with 12% methanol used in the acid stage.

This comes from an experimental formula that was devised from several peoples results in the really long acid thread.
The formula is kind of long as well. You can be among the first to try it though and report your results if you so choose.

The formula is based on selecting a molar ratio of Sulfuric:FFA that gives you the results you desire, kinda, sorta.

The formula is:
((AxBx.4)+B)x40.4 = ml acid to use per liter of oil.
(B/A)x54 = ml Sulfuric to use per liter of oil.
where A = FFA in the ratio of FFA:Sulfuric (15:1, A=15)
where B = titration in KOH x .0178

Using your titration of 10.5ml KOH, and 12% methanol in the acid stage this gives us .27ml H2SO4.
A ending T of .6ml KOH would indicate a close to complete reaction.

If you choose to give it a go, you could add a bit more acid to be safe since this formula has yet to be tested. Your ending titration should indicate the effectiveness.


Thank you, DoubleD. My most recent batch titrated at 4, so I'll use base/base on it as usual. Next time I come up with something over 10, I'll try this formula and report back here.

Best,


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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