Reece

there is no vacuum system it works at atmospheric pressure, and many people(including myself until recently) believe the theory of a high chance of reversing the reaction, but as some of us are now finding this isn't panning out in reality when the meth vapour is sucked through a condensor by a venturi.

Chug

Demething the whole batch ensures that virtually 100% of all catalyst added to the reaction will convert to soap. This includes catalyst added for the titration and for the base reaction. Evaporation of methanol leaves the catalyst behind. The catalyst then attacks the biodiesel to make soap.

quote:

Originally posted by Chug:
. . . believe the theory of a high chance of reversing the reaction, but as some of us are now finding this isn't panning out in reality when the meth vapour is sucked through a condensor by a venturi.

The rate of the reverse reaction is based on the efficiency, time, and temperature of the methanol removal step. The rate of reverse reaction is not based on whether or not the vapor is sucked (actually recirculated in this case) through a condenser.

quote:

Demething the whole batch ensures that virtually 100% of all catalyst added to the reaction will convert to soap.

For this to be true, wouldn't there have to be a significant amount of water available.

Here's the reaction you're talking about. Oil could mean biodiesel.


Oil + lye -> soap

In order for that to happen, there has to be water present. That's why we try to run the biodiesel reaction anhydrous, to prevent that unwanted side reaction as much as possible.

Finest regards,

troy

quote:

Originally posted by troy:
. . .Oil + lye -> soap

In order for that to happen, there has to be water present. That's why we try to run the biodiesel reaction anhydrous, to prevent that unwanted side reaction as much as possible. . . .

There is always plenty of water for this reaction to proceed. The trace amounts of water in the biodiesel exists in solution with the methanol. During methanol distillation, especially at low temperatures, the methanol is driven off earlier than the water. This leaves an increasingly higher concentration of water in which the catalyst remains. As the water also evaporates the catalyst looks to fatty acids as its new home.

Think of it this way: if the catalyst does not combine with FA to make soap, then what is the fate of the catalyst?

It does not evaporate with the methanol. Nor, does it precipitate out in solid form. It breaks off as much fatty acid as it needs, either from under reacted TG or from fully converted BD, and makes soap.

quote:

Originally posted by producer:
Chug

Demething the whole batch ensures that virtually 100% of all catalyst added to the reaction will convert to soap. This includes catalyst added for the titration and for the base reaction. Evaporation of methanol leaves the catalyst behind. The catalyst then attacks the biodiesel to make soap.

Hi Producer,

thanks for your input, I tried to read/learn as much as I can from folks who have researched this, but it mostly seems based on theory and repetition rather than actual tests/research, is this your own experience/theory or from someone elses research into reaction reversal?

If this is correct about NaOH producing soap from the bio once the methanol has been recovered then I would expect to see a lower bio yield, but so far this hasn't been the case, but I haven't done any real accurate measuring.

quote:

Originally posted by producer:
The rate of the reverse reaction is based on the efficiency, time, and temperature of the methanol removal step. The rate of reverse reaction is not based on whether or not the vapor is sucked (actually recirculated in this case) through a condenser.

Is this your own theory or have you found some research I haven't managed to find?
any pointers appreciated.
I would have thought the venturi and condensor size and efficiency play a big part, there would surely be a difference with more or less suck from the venturi and a bigger or smaller condensor?

This message has been edited. Last edited by: Chug,

SUPERFAST GLYCEROL SETTLING...VIDEO (after whole batch demething)


Here is a short video clip of the glycerol settling superfast out of biodiesel after a whole batch demeth.

You can see it happening before your eyes after only a few seconds and after 1 minute it's clearly visible but unfortunately an almost full memory card only allowed just over 3 mins video time.

The glyc took approx 6 mins for the main bulk to settle out, within half an hour the bio is clear.

http://www.youtube.com/watch?v=rw4P8eeqswg

quote:

Originally posted by Chug:
SUPERFAST GLYCEROL SETTLING...VIDEO (after whole batch demething)

http://www.youtube.com/watch?v=rw4P8eeqswg

Nice vid! I always like looking at peoples biodiesel pictures and vids..

Chug,
You are basically doing the same thing as GL does in the push/pull minus the push and adding acid to neutralize the caustic. I should be getting some phlip tests this week and I will be testing the biodiesel before and after the recovery for an indication of a back reaction. I will let you know how it goes but keep in mind I neutralize the caustic with acid as per GL's instructions...
I have been doing this for almost 2 years now with no issues so I dont anticipate the tests to show any big difference between the pre and post demething...
Jon

I've made three 100L batches this last month using this method. Even while I do not pass 3/27 with most batches (and that result does not change after de-meth), I have gotten very good results.

I can attest to the very fast glycerol separation. Yesterday, I opened the drain about 10 min after stopping the pump and drained out very pure and dark glycerol with a very good separation...i.e. the glycerol drained first, then a very clear transition to BD.

I have had the soap settle out of finished BD in my 55 gal settling tank as fast as 12 hours (or perhaps faster, but that is the shortest interval i have checked it).

I also stop short of recovering every last bit of methanol, probably about 500ml short...probably out of fear mostly...but also because I know my current processor does not produce 100% conversion. Substandard? Maybe, but my cars are 10 and 7 years old, respectively and are perfectly happy on the current fuel I make.

I will be making some improvements to my processor shortly.

I have no idea as to any other testing, as I don't do it and don't yet understand it.

Hi Fred,
If your fuel is already not passing the 3/27 and you are satisfied with that, then I would not give back reaction a second thought and just go for it! The back reaction will not even show up in a 3/27 test unless it has gone EXTREMELY bad from what I understand so you have nothing to worry about since all of your oil has not been converted anyways...
Jon

Chug,

I'm willing to give it a go. I asked once or twice about demething the whole batch in a non Push/Pull setup and heard very little in response. I've got a 40Gal water heater GL-1day setup with a Jamesrl venturi and plumbers delight condenser.

I've got 100L of good looking WVO which titrates at 3. I'm using NaOH. So I mixed 22L of Methanol (probably 4L was recovered from biodiesel in the last 2 batches) together with 800G of NaOH. I heated the WVO to 140F and dosed in approximately 80% of the methoxide. Mixed for 1 hour. Then dosed in the remaining methoxide. Mixed for 2 hours. Then shut down the mixing pump and went to bed. I drained the pipes this morning and I am waiting for the bio and glycerin to cool and separate so I can perform the 3/27 test. If I pass, then I am going to turn on the heating element and distill methanol from the whole batch. My setup distills very nicely for me despite the need for some upgrades.

QUESTION: is there any drawback to adding 100ml of Muriatic acid to neutralize the caustic? I've got some laying around if I can find it. I don't think it would be a big deal to add in a small amount of acid to provide extra insurance against reversing the reaction.

I plan to draw off the settled glycerin (after methanol distillation) and drive off the remaining methanol in another container (water wash/dry setup) by circulating it in my drying tank, then pump it through the centrifuge until enough soap is removed.

If this works, these will be the benefits that I hope to see:
* It will radically change my process in terms of efficiency and effectiveness
* It will mean that I can reclaim MUCH more methanol volume and eliminate the need to reclaim methanol from glycerin separately.
* My cost per gallon for making biodiesel should go down quite a bit because I'm able to reuse more methanol per batch.
* Also, this will mean that more soap will fall out from the biodiesel into the glycerin, dramatically reducing the soap content in the biodiesel, making waterless soap removal MUCH easier

Thoughts??

I hope to upgrade my process this year with PID heat control, a larger distillation condenser, and a GL design carboy lid for reclaimed methanol.

PwrStrk6spd

quote:

QUESTION: is there any drawback to adding 100ml of Muriatic acid to neutralize the caustic? I've got some laying around if I can find it.

I guess it would depend on the concentration of HCL in the muriatic acid and how much pure acid it would require to neutralize the caustic. Are you planning to use an indicator to determine when the mix is neutral? If not you could end up with acidic BD. The soap could revert back to FFA's.

Chug is not using acid to neutralize and isn't as concerned with high conversion fuel. You may not be willing to accept low conversion fuel.

It wouldn't hurt to try this out, but make sure you are adding the proper amount of acid.

quote:

Originally posted by Eurocab:
PwrStrk6spd

quote:

QUESTION: is there any drawback to adding 100ml of Muriatic acid to neutralize the caustic? I've got some laying around if I can find it.

I guess it would depend on the concentration of HCL in the muriatic acid and how much pure acid it would require to neutralize the caustic. Are you planning to use an indicator to determine when the mix is neutral? If not you could end up with acidic BD. The soap could revert back to FFA's.

Chug is not using acid to neutralize and isn't as concerned with high conversion fuel. You may not be willing to accept low conversion fuel.

It wouldn't hurt to try this out, but make sure you are adding the proper amount of acid.

Eurocab,

I guess I could effectively titrate the biodiesel and glycerin solution with my acid? Take a sample of 100ml of biodiesel and glycerin but I'm a little confused on the process of titrating this. Does anyone have a good procedure?



Chug,

Tiny setback. Went out to test the biodiesel for conversion and failed badly. I may not have stirred the batch long enough. These blue pumps don't stir 100L very fast so I'm going to mix for another 2 hrs and retest.

When demething whole batch and checking for back reactions I really suggest you go higher than 3/27. To see the amount of fall out from a back reaction go atleast 5/45..higher the better. 3/27 will struggle to pick up a slight change caused by back reaction.

Pwrstroke, why do you not titrate your solution mixture to find out how much acid to add to neutrolize? When its all mixing during reaction 2 take off a small sample and check. Phenol red (not phenolphtaline) or bromo blue can both be used to check when a solution is close to pH 7. Titrate with your muriatic acid. Then as its still all mixing add the required amount react for 5 more mins then start demething. As eurocab said, too much acid will split soaps back to FFAs, and too little will still leave room for back reaction (althought reduced as concentration of your caustic has been decreasd).

Another thing. If you have a vacuum set up, try to do your recovery fast. The longer the time the more back reaction. Some Commercial producers use flash evaporations for this very reason..

Sounds like you have a really nice biodiesel processor set up..

quote:

Originally posted by Reece123:
When demething whole batch and checking for back reactions I really suggest you go higher than 3/27. To see the amount of fall out from a back reaction go atleast 5/45..higher the better. 3/27 will struggle to pick up a slight change caused by back reaction.

Pwrstroke, why do you not titrate your solution mixture to find out how much acid to add to neutrolize? When its all mixing during reaction 2 take off a small sample and check. Phenol red (not phenolphtaline) or bromo blue can both be used to check when a solution is close to pH 7. Titrate with your muriatic acid. Then as its still all mixing add the required amount react for 5 more mins then start demething. As eurocab said, too much acid will split soaps back to FFAs, and too little will still leave room for back reaction (althought reduced as concentration of your caustic has been decreasd).

Another thing. If you have a vacuum set up, try to do your recovery fast. The longer the time the more back reaction. Some Commercial producers use flash evaporations for this very reason..

Sounds like you have a really nice biodiesel processor set up..

Thanks. My setup is small, making only 25 gallons at a time. I hope to change that to a 50 gal per batch capacity this year. As far as it being nice, I just followed Graham Laming's design for the GL-1 Day Eco processor http://www.graham-laming.com/b...tate_diagram_new.htm.

As far as a procedure for titrating the biodiesel and glycerin... Do I need to dissolve the solution in isopropyl alcohol OR Methanol (because its plentiful) in order get the acid and red phenol into the biodiesel for testing? How about acid? Does it need to be diluted in distilled water?

So if I pulled 10ml of bio/glyc, how much phenol do I need? Alcohol? Acid? How do I convert the acid titration to amount of full strength acid added?

Fred,PwrStrk6spd and all

the first couple of batches of whole batch demeth (WBD) had slight traces of mono and diglycerides so I adjusted the method slightly and the latest method I'm using is to stop recovering when I've almost reached the stoichiometric average of 12.5% methanol, then settle and drain glyc and pump bio to settling tank and bubble overnight to remove any residual traces of methanol.

I made a guide to recoverable amounts here using 22% methanol
http://www.biofuel-uk.net/recoverable%20methanol.doc

Stopping 500ml or so just short of the 12.5% has given great results with no sign of mono and diglycerides but if any of you have phlip test I would be very interested to see what result that gives on your bio from WBD?

I don't find any need for acid but hey give the WBD a go with and without acid and report back, I'm all for trying experiments.

Chug

quote:

Originally posted by PwrStrk6spd:
As far as a procedure for titrating the biodiesel and glycerin... Do I need to dissolve the solution in isopropyl alcohol OR Methanol (because its plentiful) in order get the acid and red phenol into the biodiesel for testing? How about acid? Does it need to be diluted in distilled water?

So if I pulled 10ml of bio/glyc, how much phenol do I need? Alcohol? Acid? How do I convert the acid titration to amount of full strength acid added?

Yes you do need to disolve in isopropanol. Well you dont have to, all it does is helps everything mix right (solvent). Methanol also works as a solvent, I ordered a pail of 99% iso prop for about $70 cos I was sick of always buying it. Soap titrations and washing out beakers i go thru a little bit of it. The amount of solvent (isopropol) you add is not important as it has nothing to do with the reaction. its only job is to facilitate mixing. So use enough so that your happy with how everything is mixing.

How much of each to add all depends on how concentrated your acid it. So for example, take 1L of BD/glyc mix sample, add a good squirt of phenol red and IPA. Titrate until the red goes back to yellowish. Multiply the mL of acid added by batch size (in litres). Thats how much acid to add to ur reactor.

Of course in reality you wouldnt do this as a 1L sample is massive and difficult to work with. Probably a 100mL sample. If its taking too much acid go down to a 10mL sample. If you do use a 10mL sample and 1 drop of acid is changing the colour then look at diluting your acid down.

Of course how much you dilute your acid doesn't matter. Cos titrating with whatever you have will tell you how many mL of the same titrant need to go into the batch to neutrolize. Problem there is you will get water in your recovered methanol so its best to keep your acid as concentrated as possible..

Chug, have you tried doing say a 30/270 (instead of 3/27) on both the before and afters?

using a big sample will help massively in spotting the tiniest differences in back reaction..3/27 imo is too small.. people who use 1/9 are just crazy, or have unbelievable eyesight and the cleanest of beakers

I've changed the thread title as my method uses NO ACID and folks are starting to discuss using acid in this thread, that is a completely different thing to what we are doing here.

yes I tried bigger amounts of bio, if the bio is high conversion then it will take much more than 3ml, same result post WBD.
Jim (jamesrl on here purveyor of venturi's) does WBD as his standard method now too and he always goes bigger than 3/27 too.... we don't have phlip in the UK but lots of folks are having a go at WBD and getting good results, so I'm looking forward to the results from those that try my version of WBD across the pond.

There have been 1 or 2 who have had slight problem with white fluffy cotton wool like tiny balls, but it's not certain if this is caused by WBD or not as the majority are getting great results with no problems and liking it as it's quicker and saves energy.

quote:

Originally posted by Chug:
I've changed the thread title as my method uses NO ACID and folks are starting to discuss using acid in this thread, that is a completely different thing to what we are doing here.

yes I tried bigger amounts of bio, if the bio is high conversion then it will take much more than 3ml, same result post WBD.
Jim (jamesrl on here purveyor of venturi's) does WBD as his standard method now too and he always goes bigger than 3/27 too.... we don't have phlip in the UK but lots of folks are having a go at WBD and getting good results, so I'm looking forward to the results from those that try my version of WBD across the pond.

There have been 1 or 2 who have had slight problem with white fluffy cotton wool like tiny balls, but it's not certain if this is caused by WBD or not as the majority are getting great results with no problems and liking it as it's quicker and saves energy.

Okay okay. No more talk about acid. I didn't think its a big deal but clearly I misjudged.

What is WBD stand for?