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Clear liquid on top, milky on bottom????
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Hi all,
Processing the last of some oil that titrated just over 20 I have run into a problem. Here's the steps taken so far:

80 gal batch.
Pretreated with Glycerol from a previous batch.
Drained glycerol / gunk.
T is then 16.
Introduced a mix of 9 gals of methanol and 1032 grams (not ml's) of 93% sulfuic acid at 120 degrees and mixed 6 hours to lower T further. This amount has worked well before.
Turned off pumps and heater, let settle overnight.
Next day when attempting to drain (temp now only 55 F.)it appears I have oil at the bottom and clear liquid at the top. So I can't drain anything.
I go read some posts here on the forum and decide that temperature could be to blame so I mix again while heating to approx 105 degrees. Settle for 2.5 hours and temp is close 100 but already I have a clear phase on top, looks like about 2.5 gallons, much more than the amount of acid I added but much less than the amount of methanol. At the bottom I now have milky emulsion looking gunk which I drained off, about 1 gallon worth, then clear oil coming through.

So, am I forced to skim off the liquid at the top? No way to make it drop so I can just drain?
And what is it... methanol and acid? How would I get that out safely if it's full of Sulfuric Acid?
Normally I have gotten a black gunky liquid drop out with the acid that I could drain, not this time, nothing black top or bottom?!?!?!

Thanks for any thoughts and suggestions in advance,
Dan
 
Location: Central California | Registered: April 24, 2010Reply With QuoteReport This Post
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Dan
-liquid on top = methanol creamy sludge is an indication that water is present
-AE does not work well after byproduct pre treatment. Byproduct contains both caustic material and water, a caustic and an acid can't co exist in a container at the same and water as you know is another ae killer. For ae to to be predictable the PH of the mix, acid/methanol and uvo, must be 1 or less. I have found that if ph is above 2 the ae reaction is always poor. 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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Thanks,
I thought the pretreatment actually removed water, that was the whole point of doing it, plus lowering T of course. I did settle and drain the glycerol.
Anyway, I hear what you are saying otherwise, so at this point can I just add more acid and it will go to the bottom ? Or is it better to just skim off the clear liquid at the top and move on to base stage?

Thx much,
Dan
 
Location: Central California | Registered: April 24, 2010Reply With QuoteReport This Post
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Dan
-you are right, the byproduct treatment is touted as a good method of removing water, but how do you get all the byproduct out prior to base processing. I find it near impossible to find the uvo/byproduct interface.
-what to do now Eek I would add more acid make sure the ph was 1 or less and let the batch settle as per a normal AE process.


" 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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Thanks,
Will I need to heat to 130 again? Or can I just mix it up for say an hour at 80 degrees and then settle it right away or?

In terms of draining the glycerol after the pretreatment, yes it is hard to see the interface, a change in viscosity is usually my best indicator as well as making sure that the amount drained is a bit more than the amount of glycerol initially added. What oil is wasted will eventually come to the top of your glycerol container and can be reclaimed later. I'm sure none of this is news to you though...

Thanks again,
Dan
 
Location: Central California | Registered: April 24, 2010Reply With QuoteReport This Post
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Dan
-yes you will need to heat, AE will not work at room temp. I have had test batches sit for one month and no conversion, then drop the sample into a hot bath overnite and it worked fine. 100F would be the minium temp. I use 120 - 135f at that temp it takes about 12 - 14 hours, at 165f it will be done in about 4 hours ,mixing is required for the entire process at the higher temp to keep the methanol mixed in.
- byproduct treatment is not one that I have spent much time one. All my oil titrated at 8-12 KOH as of last week that has increased to T20 @#$! oil cleaners! Big Grin so AE is part of every batch I process. 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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Now you are confusing me Tom.
The last thing that I remember you posted about mixing was that continual mixing gave a worse result because it kept the acid/methanol mixed in and all that was wanted was for the acid/methanol to be reacting the FFA's that had been washed out of the oil.
quote:
Originally posted by Biotom:
Dan
...mixing is required for the entire process at the higher temp to keep the methanol mixed in...
Tom
 
Registered: October 04, 2010Reply With QuoteReport This Post
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-Don't be confused. In HTAE (hight temp acid esterfication) mixing is a must because at that temp the methanol boils out of the mix, condences in the head space of the processor then falls and floats on top of the oil.
-it is true that AE with continuios mixing has a higher ending T at the time the pump is turned off this is because all the acid is still in the mix, by not mixing throughout the process the acid has a chance to settle to the bottom. If for heating reasons you need to mix for the duration of the ae process let the mix settle for several hour then check T, it will be lower. 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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quote:
Originally posted by Biotom:
-Don't be confused. In HTAE (hight temp acid esterfication) mixing is a must because at that temp the methanol boils out of the mix, condences in the head space of the processor then falls and floats on top of the oil.
Tom
What type of reactor are you using? If you run the reaction at 165deg doesn't the methanol just boil and go out the vent?
 
Registered: October 04, 2010Reply With QuoteReport This Post
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Providing you allow sufficient head space and incorporate a lenghth of pipe at the top of your processor venting methanol will be a non issue. this is what I have


" 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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I still do not understand why you are recommending HTAE that requires mixing when you have stated many times that mixing gives a poor reaction.
Why not just use MTAE (Moderate Temperature Acid Esterfication) which omits the mixing so that you get better results?
 
Registered: October 04, 2010Reply With QuoteReport This Post
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HTAE is very fast, usually done in 3 - 4 hours.


" 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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But it does not give as good a results does it?
quote:
Originally posted by Biotom:
HTAE is very fast, usually done in 3 - 4 hours.
 
Registered: October 04, 2010Reply With QuoteReport This Post
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