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Biodiesel Quality Description

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  #1  
Old 11-18-2008, 10:18 PM
lew ward lew ward is offline
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Will the 3/27 test be affected by water in the unwashed fuel? I have had a problem with making soapy fuel (oil not dry enough) and am wondering if there was too much water in the fuel while it was being made, would it affect the 3/27 test? My last batch was the first time I have tried the 3/27 test and it failed. I titrated using 3 different pH indicators, so I am sure my amount of catalyst is correct (7.8+titration value) and I am using 20% methanol.
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Old 11-18-2008, 10:26 PM
girl mark girl mark is offline
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I think water made in your soapy fuel's process ended up in the glycerine.

however, soap will make the 3/27 sometimes have white soap precipitate out. That's not necessarily a failure but it's hard to read the result.

Also, if you have a 7.8 titration, it's a LOT harder to get high conversion quality fuel because the process destroys some of your lye, more than is easy to account for. If you're only using 20% methanol, I think your chances are bad for making a 3/27 passing fuel with one stage.

See www.biodieselcommunity.org base/base two-stage article on one way to deal with this. Also, a glycerine pretreatment (not described at biodieselcommunity yet) is a good way to go for the oil you're describing.
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  #3  
Old 11-18-2008, 10:26 PM
producer producer is offline
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Quote:
Originally posted by lew ward:
Will the 3/27 test be affected by water in the unwashed fuel? . . .
Yes, in at least two separate ways.

1) Any water present in the biodiesel will be added to the methanol with the biodiesel. The water will tend to dilute the methanol and change the solubility dynamics of the Biodiesel/methanol/TG mixture.

2) The water present in the reaction will accelerate the formation of FFA through hydrolysis. Once the FFA forms, then the catalyst will immediately bind with the FFA to form soap. This mechanism "robs" the catalyst from the biodiesel making reaction, leading to incomplete conversion, and making it less likely that your biodiesel will pass the 3/27 test.
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Old 11-19-2008, 07:07 AM
lew ward lew ward is offline
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Girlmark

I am using 90% KOH and my base amount of catalyst is 7.8, this is not my titration value. For the oil I was using, it titrated out at 6.0, maybe too high for a single stage process anyway? So my total catalyst would be 13.8g per liter oil. I will check out the biodieselcommunity site for some input. Thanks.

Producer,

I get what you are saying, Get the water out. I thought my settling process would do this for me (2-3 weeks settling in one tote then sucking off of the top and transferring to another to another tote for another 2-3 weeks of settling) Obviously this is not working. Will have to do some drying after settling to get where i want to be. Thanks.
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Old 11-19-2008, 03:32 PM
Andrew M Andrew M is offline
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Quote:
it titrated out at 6.0, maybe too high for a single stage process anyway?
This is marginal, so I'd use glycerine pre-treatment.

With regard to passing 3/27 with unwashed fuel, water in the fuel is a potential issue. Other known issues are the temp at which the test is done, and water in the methanol.

So, what temp are you doing the test at?

Also, are you using yellow heet, or production methanol?

On 3/27, lastly, the 3/27 is most accurate on washed, dried fuel. On unwashed fuel, I consider it a pre-test. So far, I have never seen fuel pass unwashed and fail washed and dried. So if it passes you are good, IME. I have seen some fuel which tests slightly better washed and dried than it did unwashed.

In getting high conversion, another key factor is processor run time. How long do you run? I have seen improvement at 3-4 hours and suspect that meaningful improvement continues beyond that point, as long as your processor is closed while running.
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  #6  
Old 11-19-2008, 09:47 PM
lew ward lew ward is offline
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andrew m

I am using yellow heat for the testing and tried testing attempts between 60 and 100 degrees. I kept bumping the temperature up trying to "force" the test to pass. I ran this batch for a little bit over 2 hours.

I have started researching the process of a glycerine pretreat. What I haven't run across yet is monetarily wise, which is makes more sense, to pretreat with glycerine and lose your excess methanol or to recover the excess methanol?
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  #7  
Old 11-19-2008, 10:01 PM
girl mark girl mark is offline
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Lew,

I agree, your numbers are marginal for a passing quality fuel. Just bump up the KOH a bit on the base side, try 2-stage 80/20. or, like people say, try the glycerine pretreat. The 6 titration you're getting makes it a perfect candidate for pretreat.
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  #8  
Old 11-19-2008, 10:36 PM
Andrew M Andrew M is offline
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Quote:
I am using yellow heat for the testing and tried testing attempts between 60 and 100 degrees. I kept bumping the temperature up trying to "force" the test to pass. I ran this batch for a little bit over 2 hours.
If you are still failing at 100f after 2 hours of processing, then 2 stage may be required.

At what temp do you process?

Another (potential) issue is water in your oil. Have you tested for water in the oil? If there is significan water in your oil, it will affect the reaction be consuming catalyst, producing soap, and making more water. This is particularly important due to your FFA level.

Glycerine pretreatment helps with water in oil along with reducing titration values.
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  #9  
Old 11-20-2008, 09:47 AM
lew ward lew ward is offline
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girlmark,
what would you consider a "bump" up in my KOH. From 6 to 6.1 or all the way to 7?

andrew m,

I am processing at 135 to 140 degrees. I did find that I had water in my oil, so I am taking measures to correct that. If I decide to do a 5% glycerine pretreat, would I do it before or after my dewatering treatment. I am assuming before.
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  #10  
Old 11-20-2008, 11:03 AM
JimKohler JimKohler is offline
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Why stop at 5%? Add as much as your processor will allow, your 6 should drop to about 2, also the pre-treatment drops out water as well as any junk left in the WVO. Makes making 'good bio' a pleasure.
This might also help. We mist wash a couple of times boosting the temp up to about 60, sorry 140F, we then pump the hot, hot water from the bottom and spray it violently onto the top of the bio. Clears in no time flat. Jim.
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  #11  
Old 11-20-2008, 03:05 PM
Andrew M Andrew M is offline
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Quote:
what would you consider a "bump" up in my KOH. From 6 to 6.1 or all the way to 7?

I am processing at 135 to 140 degrees. I did find that I had water in my oil, so I am taking measures to correct that. If I decide to do a 5% glycerine pretreat, would I do it before or after my dewatering treatment. I am assuming before.
As for your base #, I would move it up in .5 gram steps. The trade off is between more soap and higher conversion. Also, consider using a bit more methanol. Once you get things sorted out, you can back off again. Like 22-24%.

About the pre-treatment, it is different from the 5% glycerine pre wash. Pretreat uses the glycerine from last batch on the oil, prior to processing. Pre wash uses 5% water with the glcyerine still in the processor. 2 different things.
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  #12  
Old 11-20-2008, 03:23 PM
girl mark girl mark is offline
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I knew this mistake would happen sooner or later- not your fault, but the early people who worked out the '5% water prewash' used to call it the '5% glycerine prewash' which still referred to the technique of adding water to your biodiesel while all the glycerine was still in it in order to get more complete separation and soap removal from the biodiesel.

This is now confusing because we now have a technique called the 'glycerine pretreatment' which is when you treat your OIL with glycerine from a previous batch, then let the glycerine settle out completely, drain it off, and proceed to use the oil. THere's no magic number on how much glycerine to use but people usually use something like 20%-25%- about the amount that you'd get from your previous batch.
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  #13  
Old 11-21-2008, 10:20 AM
lew ward lew ward is offline
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For my size batch (180 liters) I drain off about 10 gallons of glycerine. 25% would be 2.5 gallons. So from what I understand, I should add about 2.5 gallons, or more, to my new batch, mix it, and let it settle out. Is there any reason I couldn't put the oil for the new batch in my processor, add the 2.5 gallons of glycerine, mix with pump and let settle(all at 130 degrees)? If so, how long will it take to settle out?
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Old 11-21-2008, 08:34 PM
taralec taralec is offline
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I would work on 20-25% of your new oil for the pre-treat-ie for 180Lt batch of oil,I would add 35-45Lts of glycerine from previous run.(assuming you mean US gallons,chuck it all in)
I run it for a good hour heating and pumping(50-55c).
I let it settle for 2hrs,then drain down glycerine-longer would probably be better,but I want to get to bed sometime,and I use NaOH-overnight the glycerine would probably go solid.
Gives fantastic titration lowering and lightens up the colour of your feed stock.
All the best.
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  #15  
Old 11-22-2008, 11:40 AM
lew ward lew ward is offline
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thanks to all. I will try some of these suggestions this weekend if it stops snowing.
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  #16  
Old 11-23-2008, 05:32 AM
Andrew M Andrew M is offline
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Lew,
Quote:
For my size batch (180 liters) I drain off about 10 gallons of glycerine. 25% would be 2.5 gallons. So from what I understand, I should add about 2.5 gallons,
When people say 20 or 25%, they mean of the volume of oil to be treated, not of the glycerine from the last batch. Use all the glycerine from the last batch.
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  #17  
Old 11-23-2008, 11:36 PM
lew ward lew ward is offline
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Thanks for clearing that up. I will try that on my next batch. A couple of questions though. Is it the glycerine or the unused methanol/koh mixture that actually removes the water and strips the FFA's? If it is the glycerine, could you reuse the glycerine a couple of times to remove more water?
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Old 11-24-2008, 05:16 AM
JimKohler JimKohler is offline
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Lew, Rather not, that glycerol will have all sorts of junk, water etc.and will be quite viscous. Anyway, you will always have glycerol from a previous batch to use.
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Old 11-24-2008, 07:11 AM
Andrew M Andrew M is offline
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Lew,
Quote:
If it is the glycerine, could you reuse the glycerine a couple of times to remove more water?
As I understand, it is the glycerine that removes the water, but the KOH that reduces the titration value. I suspect that you would continue to see benefit from a second use, but that would depend on how dirty and wet you oil is. I suspect that the benefits would be significantly less on the second go. But, test it out and let us know!
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