BIODIESEL & SVO DISCUSSION FORUMS





Sponsors    Biodiesel and SVO Forums Home    Forums  Hop To Forum Categories  Biodiesel  Hop To Forums  Acid Esterification    New to AE, could use some tips.
Page 1 2 

Moderators: Shaun, The Trouts
Go
New
Find
Notify
Tools
Reply
  
New to AE, could use some tips.
 Login/Join
 
Member
posted
Ladies and Gentlemen (and I use that term loosely);

I could use some assistance from your knowledge base.

Recently, I constructed a new 23 gallon processor from stainless steel. In it, I process 16 gallon batches of WVO into Bio, using a single stage base method. I have only done 2 batches in this new processor. Prior, I was using a mild steel 16-gallon drum that processed 10-12 gallon batches. I did about 30-35 batches in the old processor without any emulsions.

As of late, my WVO supplier has become horribly inconsistent in their WVO, and it may titrate anywhere from 12-24 before a glycerin pre-treatment.

My last batch of 16 gallons netted very poor, titrating at 18 after pre-treatment.

After doing a lot of reading here, I've opted to switch over to a AE process for anything titrating over 14.

Right now, I have 61.45 liters of WVO in the processor, which titrates to 24koh (no pre-treatment). Using the DKenny method, I took 24 and subtracted 3, then multiplied by .2, which yields a value of 4.2ml of acid per liter. Multplying the 4.2 times the 61.45 liters nets 258.1ML of acid for my AE stage.

I mixed the 258.1ml of 93% sulfuric acid into 1.95 (12%) methanol and poured it into the processor, mixing for 2 hours at 52-57C.

After letting it settle all night, I drained off 1 gallon from the processor, which included some really nasty looking stuff. I then re-heated and mixed for 5 minutes, then did another titration, which was 18koh (down from 24koh). Rather shocked that it was that high. After conferring with some other biodieselers who admittedly have no AE experience, we came to the conclusion to dump the 1 gallon I drained off back into the top, heat, and continue mixing for up to 12 hours.

Two hours into the mixing I did another titration, which came up to 20koh. Rather surprised that the titration went back up.

After reading here, since my processor has a vented lid, I feel I may have evaporated some of the methanol out, which could be part of the high titration? At any rate, about 30 minutes ago I added another 1 gallon of methanol to the processor, and mixed at temperature for about 5 minutes. I have since shut off the heat/mixing and am letting it settle.

After reading the forum extensively, I can only come to the following conclusion:

1. Did not mix long enough.
2. Evaporated out the methanol.
3. Did not add enough acid.
4. There's water in the oil.

However, I have no idea which of the above is my issue.

On a side note, the last two batches I've done (the last one being single stage base), and now this AE batch, the oil doesn't want to mix well with the iso alky in the titration. At first, it mixes ok, but as I add more and more titration fluid, the oil wants to re-combine.

I could certainly use some guidance, and would appreciate any help or suggestions.

-WildBill
 
Location: STL Metro | Registered: October 18, 2011Reply With QuoteReport This Post
Member
posted Hide Post
Well, it may be lack of methanol. The extra 1 gallon I added brought some "tan" colored crap to the top, but after 15-20 minutes, it disappeared.

I read in another thread by Biotom where he said that excessive methanol will cause the tan stuff to float. So since it's not floating, apparently I didn't have too much.

I just drained off 1 gallon from the bottom... Boy is it some thick, nasty, stuff...but it doesn't smell like methanol.
 
Location: STL Metro | Registered: October 18, 2011Reply With QuoteReport This Post
Member
posted Hide Post
Surprised Tom hasn't replied to this yet.

First off 93% sulfuric acid is very low. It is going to be very difficult to get good reactions using that. You want 96+ or even 98% if you can find it.

I'm not sure I'm reading this right. You had 64L of oil but only added 1.95L of methanol? That might be too low yes.

I don't think mixing is the issue or lack of acid or evaporation, I would bet it's due to water (the water in the acid definitely didn't help) and lack of methanol if I read that right.

For an initial acid # that high the stuff you drain from the bottom isn't really re-usable directly in the base stage. I would drain the stuff from the bottom and add it to the glycerin waste rather than try to mix it back in. It's going to be mostly water.

Also whether the layer sinks or floats depends on the water/acid/methanol ratios. Since yours sank and you didn't use much methanol (again if I'm reading that right) that again points to too high initial water content. If you go through the big long AE thread there are some posts by DoubleD where he did some calculations to determine what methanol/acid ratio's to use to ensure that the byproduct sinks. Page 36/37 I believe. Generally it's easier if it sinks since you can just drain it off the bottom.
 
Registered: February 25, 2010Reply With QuoteReport This Post
Member
posted Hide Post
Sorry, that's 1.95 Gallons, not liters, of methanol.
 
Location: STL Metro | Registered: October 18, 2011Reply With QuoteReport This Post
Member
posted Hide Post
In the end, it had a total of 2.95 gallons of methanol.
 
Location: STL Metro | Registered: October 18, 2011Reply With QuoteReport This Post
Member
posted Hide Post
O.k. sounds like too much water then.
So to fix what you have now you have a few options.

If you have a day or two to kill just let it settle for 2 days and then see how much more crap you can drain from the bottom. From there you can either try to re-dry the oil/methanol/acid mixture and then add more methanol/acid or just add more acid/methanol to try to get the acid # down to a managable limit. Again with 93% acid though your acid stage isn't going to be very effective.
 
Registered: February 25, 2010Reply With QuoteReport This Post



Member
posted Hide Post
Well, since I didn't get any response I sort of figured this forum was dead, and went ahead on my own experimentation.

After having drained off the bottom and waiting overnight, I did a titration, which came up to, again, 20KOH. So, I went ahead and did a glycerin pre-treatment as I would normally do with my base processing and let it sit overnight. Titrated in the morning, and shockingly, it was still 20KOH.

Did the processing last night, drained off the new glycerin this morning, then air washed it for 90 minutes. There must have been a considerable amount of methanol suspended in the fuel, as I lost 2" of fuel in the processor after the air washing, this equates to about 1.3 gallons of methanol (or other fuels evaporated).

So now, I'm waiting for the soaps to fall to the bottom of the processor and I'll drain them off in the morning, then do some water washing to get the remaining soaps out of the fuel.
 
Location: STL Metro | Registered: October 18, 2011Reply With QuoteReport This Post
Member
posted Hide Post
I'll see if I can find acid with higher purity for the next batch. From what I was reading, 93% was adequate per the Dkenny method, and easy to come by at Lowes.
 
Location: STL Metro | Registered: October 18, 2011Reply With QuoteReport This Post
Member
posted Hide Post
93% will work but remember the other 7% is water!! water kills AE so you have to really make sure your oil is dry if using the acid. I will fully answer your questions tommorrow pm once I check your numbers. 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
Member
posted Hide Post
having problems with post button, try again tommorrow

Oh that worked! anyway,93% acid is ok but the oil must be dry, remember that the other 7% is water and water is an AE killer. Let me check out your proceedure and numbers and I will post back tommorrow. 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
Member
posted Hide Post
Tom;

Here's the numbers in a more easily read format:

Liters of WVO from Pg1 61.45
Gallons of WVO from Pg1 16.23
Titration from Pg1 24.00
Target Titration 3
ML of Acid per Liter of WVO 4.2
Total Acid Volume in ML 258.1

12% Methanol Required in Liters 7.37
12% Methanol Required in Gal 1.95



I tried attaching my spreadsheet, but the forum doesn't support excel files.
 
Location: STL Metro | Registered: October 18, 2011Reply With QuoteReport This Post
Member
posted Hide Post
Wild Bill,

Thanks for explaining this so clearly. Having been doing biodiesel for 3 years, and today I just got my first batch of horrible oil - 20+ Titration. It will be my first AE.

Doug
 
Location: Los Angeles | Registered: March 25, 2008Reply With QuoteReport This Post



Member
posted Hide Post
Bill those numbers look good, with 4.2 ml of acid per ltr of oil the t will be 24 + 8 = 32. (about) after mixing the oil/methanol and acid. If you measure t at 20 after mixing and settling, the AE has worked somewhat, but not as well as you would like. Free fatty acid holds water, that is not easily removed from the oil the higher the T then the more bound water that is present. As the esterfication reaction takes place the water is released and that's what stops the ae reaction. So I hope you can see the need to remove as much free water as possable, and as B Wilder stated you would have better luck with 96 or 98% acid. With higher t oils two or more ae will be required, with draining betewwn reactions. drain an amount = to 1/2 the methanol used. This drivs the cost of biodiesel production up unless you can recove the methanol from the drainage.
If you recover methanol use it for base stage only, always use NEW methanol for AE, because it will be dryer.
I never use 12% methanol, I use 8.75 - 10%
I'm not understanding the air wash part of your previous post, why where you removing the methanol at this stage?


" 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
Member
posted Hide Post
Doug you can AE process that good stuff in one AE reaction as long as you dry the oil well, pass hot pan test with NO bubbles. (better to build yourself a imake manometer) use 10% methanol and 3 ml of acid per ltr, 98% will give you a lower T but you can get workable oil with 93% ending t should be about 8 or 9 before settling and drainge takes place.


" 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
Member
posted Hide Post
quote:
Originally posted by Biotom:
Bill those numbers look good, with 4.2 ml of acid per ltr of oil the t will be 24 + 8 = 32. (about) after mixing the oil/methanol and acid. If you measure t at 20 after mixing and settling, the AE has worked somewhat, but not as well as you would like. Free fatty acid holds water, that is not easily removed from the oil the higher the T then the more bound water that is present. As the esterfication reaction takes place the water is released and that's what stops the ae reaction. So I hope you can see the need to remove as much free water as possable, and as B Wilder stated you would have better luck with 96 or 98% acid. With higher t oils two or more ae will be required, with draining betewwn reactions. drain an amount = to 1/2 the methanol used. This drivs the cost of biodiesel production up unless you can recove the methanol from the drainage.
If you recover methanol use it for base stage only, always use NEW methanol for AE, because it will be dryer.
I never use 12% methanol, I use 8.75 - 10%
I'm not understanding the air wash part of your previous post, why where you removing the methanol at this stage?


Tom;

Just to make clear...

1. Titration
2. AE Process
3. Titration
4. Drain
5. Glycerin Pre-Treatment
6. Drain
7. Titration
8. Base Process
9. Drain
9a. 3/27 Test
10. Air Wash
11. Drain
12. Water Wash

Of course, before every drain is at least 12 hours of settling.
 
Location: STL Metro | Registered: October 18, 2011Reply With QuoteReport This Post
Member
posted Hide Post
after the AE, don't use byproduct treatment, the caustic and acid will react creating a grainy salt which could plug up the pump impeller. Also, don't use a byproduct treatment prior to AE, if you do the oil will contain caustic resadue and that will neutralize the acid. everything else looks good


" 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
Member
posted Hide Post
Well, the best news is that there's no pump impeller to plug up.

Here's a couple photos of my setup:





I use a pair of 40 gallon fish tank air pumps to do my mixing, then a 1.5HP Shop Vac to dry wash. The 1" pipe has seven 3/8" holes in the bottom of it.

I think I'm trying to many new things at once. With winter coming on, I switched over to the air washing to avoid using much water (which could freeze from the hose outside the house). Now, with the high titration WVO I'm trying the AE.

Where can I pick up some economical (read cheap) sulfuric acid? The 93% is drain cleaner from Lowes. Admittedly, I wonder if there's something wrong with what I bought, as when I opened it up it's black. I've never seen black acid before. Usually it's clear or yellowish.
 
Location: STL Metro | Registered: October 18, 2011Reply With QuoteReport This Post
Member
posted Hide Post
I buy my sulfuric acid from a local chemical supplier, sometimes it is black also but it still works. as far as mixing I don't know how that could work, IMO not enough mixing, I've seen pump and paddle mixing but never air, and then there is all that air mixing into the biodiesel, oxydation may be a problem. Nice unit, did you make it?


" 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



Member
posted Hide Post
Yes, all hand made by me and a friend with a TIG. I did all the TIG work and he fixed all the leaks! LOL

The air mixing works great. Has worked all summer long without issue. Granted, my last processor was only making 10-12 gallons at a time, so I only used one pump. I purchased the second pump when I built the larger processor in case I needed more volume.

Here's a video of the air mixing with the twin fish tank pumps in action: http://www.youtube.com/watch?v=8-nuG8nW9kk

What you can't see in the back wall of the tank is the engraving. I made a base mark on the back wall and measured the gallons it took to get to the mark. From there, there's marks every 1/4" up the wall. It makes it REALLY easy to determine how much fluid is in the tank.

At some point I'll replace the black iron fittings and brass ball valves with stainless... But for now, what I have works just fine.
 
Location: STL Metro | Registered: October 18, 2011Reply With QuoteReport This Post
Member
posted Hide Post
Interesting, never seen anyone mix that large a volume using air before. If it works it works though. I just hope you aren't venting your 'mix' air directly into the same room as you or near anyone else for that matter. It's going to be full of methanol.
 
Registered: February 25, 2010Reply With QuoteReport This Post
  Powered by Social Strata Page 1 2  
 

Sponsors    Biodiesel and SVO Forums Home    Forums  Hop To Forum Categories  Biodiesel  Hop To Forums  Acid Esterification    New to AE, could use some tips.

© Maui Green Energy 2000 - 2014