Hi there, I was checking out the Bio Pro Series and I noticed that it seemed like there is no need to titrate the batch. Am I correct? If I am, then can I just use a pre-determined amount of KOH, methanol, and sulfuric acid per x amount of gallons of WVO to convert to biodiesel? And ummm did I mention that i'm a total beginner? Any info would be GREATLY appreciated! Thanks in advance

Hello Josh -

That is the case, with some very important caveats:

1 - the oil can have a maximum FFA level of 5%. Most restaurant WVO is below this level, but it is good to check. This can be determined with a Go/No Go kit from Utah Biodiesel Supply.

2 - The oil needs to be dry for the esterification to be effective. (Water brings the reaction to equilibrium prematurely.) If your oil is not dry, the BioPro owner's manual describes how you can use the BioPro to dewater the oil, if you don't have a separate device for that purpose.

Thanks for the quick reply!

I was wondering if you can give me the numbers for using pre-determined amounts of your KOH, Methanol, and Sulfuric Acid for batches that contain a maximum FFA level of 5%? That would be great!

We have had WVO that titrates 2 or less not pass 3/27. I suspect an overdose of acid takes out the base catalyst, causing the problem.
Two solutions come to mind.
We have tested both successfully.
Titrate your oil…not a bad idea just to keep your perspective on what is happening. If it is under 3 NAOH no acid is necessary, but you will need to jog past that acid stage with the Biopro and add the extra methanol directly into the processing tank.
Another method is to use about ½ the acid and process as usual. This will convert the remaining FFA to BD but the residual acid will still be present, taking the same amount of catalyst to overcome.

Galen,
Correct me if I am wrong here.
Thanks,

Bob

Methinks it would be foolish to not titrate your oil. How the hell are you going to know the proper amount of catalyst to add to the methanol? Biopro or not, titration is relevant.

Follow BobAbbey's advice or spend some more time at the tutorial section of this forum.

quote:

We have had WVO that titrates 2 or less not pass 3/27. I suspect an overdose of acid takes out the base catalyst, causing the problem.

We had this issue, when I was messing around with one of those computerized washing machines. So, we went to skipping the acid stage all together. That only worked some of the time.

TWIW.

For oils with >5% FFA, can an acid esterification be done to lower the FFA and then process the oil through a BioPro using a normal cycle?

quote:

For oils with >5% FFA, can an acid esterification be done to lower the FFA and then process the oil through a BioPro using a normal cycle?

Theoretically, oils with tremendously high FFA levels can be reduced using acid esterification. The difficulty lies in the fact that one of the esterification reaction products is water, and the ratio between water and alcohol present dictates when the reaction reaches equilibrium (quits reducing the FFA level).
This is why it's important to have dry oil when doing an esterification (more important than for a transesterification).
The BioPro's are set up to reduce an FFA level of up to 5% down to around 1.5% or so. In reality, they can tolerate an FFA level a bit higher than that, especially if your oil is very dry.
If you were to perform an esterification before putting your oil into the BioPro, the BioPro esterification would be fairly ineffective unless you first dehydrated the oil after your initial esterification. Unfortunately, removing all of the water generally means removing the methanol as well, which means significant energy is required to then purify the methanol/water distillate. That's why multi-stage esterification is not a commonly used solution for very high FFA feedstocks. Ir works well, but it is expensive and process-intensive.

quote:

Originally posted by BobAbbey:
We have had WVO that titrates 2 or less not pass 3/27. I suspect an overdose of acid takes out the base catalyst, causing the problem.
Two solutions come to mind.
We have tested both successfully.
Titrate your oil…not a bad idea just to keep your perspective on what is happening. If it is under 3 NAOH no acid is necessary, but you will need to jog past that acid stage with the Biopro and add the extra methanol directly into the processing tank.
Another method is to use about ½ the acid and process as usual. This will convert the remaining FFA to BD but the residual acid will still be present, taking the same amount of catalyst to overcome.

Galen,
Correct me if I am wrong here.
Thanks,

Bob

Not understanding the acid reaction very well, this puzzles me even more. Does this mean that the sulfuric acid is consumed by the reaction? Or does this mean that there is not enough base to neutralize the acid with low titrating oil. If this is the case, why does Graydon recommend cutting back the base catalyst on low titrating oil? I could be very wrong as it is a long time since I sat in any chemistry class. But I thought the sulfuric acid is a catalyst and is therefore not consumed. I therefore made the assumption that Dkenny uses more acid to make the reaction faster, kind of like the catalyst being an accelerator? Now I am more confused than ever.
Thanks in advance!

The sulfuric acid is not consumed by the reaction, being just a catalyst. However, since you're using a base catalyst in your subsequent reaction, the sulfuric acid is neutralized ("consumed" - turned into salts) when the base catalyst shows up.

Thanks for the reply, I am trying to get an understanding of this process.
So if I am understanding this correctly.
You will be left with the same amount of sulfuric acid after the esterification reaction reguardless of the starting oil titration?
So is it safe to assume that the biopro uses the same amount of base catalyst to neutralize the sulfuric acid everytime reguardless of starting oil titration?
So oil that titrates a 3 with NaoH is roughly a 2.25% FFA. Do you think the sulfuric acid will turn most of the FFAs into BD? I guess my question is how efficient is the acid reaction in the Biopro with low titrating oil. I could be way wrong here, but I assume that with dry oil most of the FFA's will be turned into biodiesel. I therefore assume that you will need only enough base catalyst to neutralize the sulfuric acid and to cover the normal base amount for new oil plus a little for the small amount of remaining FFAs? So I would assume that with low titrating oil you will have an abundance and not a shortage of base catalyst? I guess I rationalize this by assuming that if your oil starts at 5% FFA that you will have more FFA's left after the acid reaction in the biopro than if your oil starts at 2.25% FFA. Therefore in the automatic cycle of the biopro the formula must be set to handle the 5% FFA which will require more base catalyst than the 2.25% FFA oil?
Are my assumptions way off here? I know I make a lot of assumptions. The deeper I dig into biodiesel the more confusing it becomes.
Thanks for all your help!

So is my assumption that it takes the same amount of base catalyst to neutralize the 190 mls of sulfuric acid regardless of the starting oil titration wrong?
What did I do to kill this thread?

quote:

Originally posted by BobAbbey:
Titrate your oil…not a bad idea just to keep your perspective on what is happening. If it is under 3 NAOH no acid is necessary, but you will need to jog past that acid stage with the Biopro and add the extra methanol directly into the processing tank.

I agree with the above post. Titrate your oil. Takes 2 minutes and adjust the amount of catalyst used. Each and very time we skipped the titration and used the "default" quatities, we ended up running in unexpected results and adding time to the process.
Also, if you want to skip the acid stage (aka "Reaction 1" on the BioPros), you can still use it as designed without having to add the methanol directly into the tank. All you do is start up the process and (a) either let it follow its course eventhough no acid is present (adds about 5-6 hours additional steering for "nothing" but the oil has time to heat up really well in the mean time) or (b) let it finish introducing the methanol (about 15 minutes) and then job directly to reaction 2 (transesterification).

How long does the machine take to heat up the oil?
How long does the machine take to mix the methoxide? I would be surprised if the methoxide is ready in the amount of time that it takes to pump in the first tank of methanol.

So I am still asking if the machine uses the same amount of base catalyst to neurtalize the acid catalyst in every batch independant of oil titration?

quote:

Originally posted by Rudolf:

Each and very time we skipped the titration and used the "default" quatities, we ended up running in unexpected results and adding time to the process.

So do you titrate and put in the calculated amount of base catalyst?
Do you ever run the acid/base and adjust the amount of one of those catalysts? If so can you explain this to me so that I can understand this process?
Thanks

1) You can definitely titrate the oil & just add the right amount of chemicals. That's what the manual mode is for.
You can also use the auto mode & just not add sulfuric

2) I back off on my KOH when the oil is really good because we noticed that if we used all that it called for we were more prone to emulsions. We backed down to about 2100 and still passed 3/27's.

3) I'm now messing with some oil that titrates at .5 mL and we're not adding any sulfuric at all. Just titrating and adding the KOH the titration calls for.

The machine can take about 2-3 hours to fully heat up the oil to 130 deg but I've also seen it heat it up quicker than that. A lot of it depends on what the ambient temp in the room is.

When we skip the sulfuric (and remember, we're not adding anywhere NEAR as much KOH that way) we let the KOH dissolve for at least 1/2 hour but I've manually kicked on the methoxide pre-mix switch to mix it all up in the tank.

I also check the temp of the oil and won't "dump in" the methoxide until the oil is at least 100 deg F.

Once it hits 100 or higher (obviously 130 is better...) then I jog it forward to the Reaction
2 and let it rip.

-Graydon

quote:

How long does the machine take to heat up the oil?

Good question - from what I saw, since the thing is not insulated, if it is cool, it can take a really long time. 4-6 hours in some cases. Seriously, not putting insulation on that thing is kind of odd. There is no good explanation I can think of other that it won't look all stainless steel shiny anymore. Others?

And, when you measure the temp. is there a gauge now, or did you mickey mouse one on to it?

quote:

Originally posted by Nekoda:

quote:

Originally posted by Rudolf:

Each and very time we skipped the titration and used the "default" quatities, we ended up running in unexpected results and adding time to the process.

So do you titrate and put in the calculated amount of base catalyst?
Do you ever run the acid/base and adjust the amount of one of those catalysts? If so can you explain this to me so that I can understand this process?
Thanks

I apologize for the late response, just saw your post (this website should let us know there's a post waiting...).

Yes, we titrate. We used to titrate when we had our appleseeds. We have skipped titration on a very few occasions (3 out of 20 batches) because machine was being operated by someone new to biodiesel.
We do run the esterification (acid/base reaction) but adjust the amount of sulfuric acid instead of the amount ot the catalyst.
hth

quote:

Originally posted by Andrew Morris:
And, when you measure the temp. is there a gauge now, or did you mickey mouse one on to it?

Mickey Mouse...