Started making small batches of Bio diesel. I see all kinds of recipes with basic amount of lye/liter ranging from 3.5g to 5.5g as the base amounts. My oil titrates at 0.3ml and with the scale I have I measured 6g(I used 5.5g as base amount) for each liter of oil . The bio did seem to pass the 3/27 test but Im thinking using 5.5g as base amount seems to be an overkill?
What is the most current recipe for producing highly converted Bio diesel?
For NaOH I have always used a base of 5 and 22% methanol with great success. For KOH I use a base of 8 grams per litre.
ytk, the actual base amount required depends on various things.
The water content and type of oil are certainly factors. The processor/pump mixing are also variables.
After a glycerol pre-treatment I have experimented with various multi-stage experiments where I have had the amount of added KOH reqd for full conversion down to 3.5gms/litre of oil. This equates to @ 2.25gms of Naoh/litre. This was also with a total of 16% methanol. I do not recover methanol from the process.
My usual usage is @ 6gms KOH ( @ 3.9 gms NaOH) after a glycerol pre-wash, but whatever works for you is OK, the methanol is the more expensive chemical.
Jon (prev post) is a great believer in a single reaction and for him this works very well. The 22% methanol he uses is not wasteful as he recovers the excess of this.
Performing a glycerol pre-wash/ glycerol pre-treatment (they are the same thing) is the first stage of a 2 or 3 stage procedure which makes use of the residual chemicals remaining in the glycerine layer.
Multi stage procedures require less total chemicals than single stage procedures.
When Dgs says he uses 3.5g added KOH per litre and a total of 16% methanol he is not including the KOH or methanol that was already in the first stage glycerol pre-wash.
A Single Stage formula that will usually achieve good results is 8g KOH (90% purity)/ 5g NaOH and 20% methanol in single stage. More chemicals will help insure a more complete reaction.This message has been edited. Last edited by: Tilly,
Thanks a lot for the replays ,
The oil I collect is usually soy oil,I always check for water content.
For my first big batch I will use the higher numbers but it will be nice to reduce methanol percentage in the future as it is the more expensive ingredient .
Another question I have : Is it possible to dissolve the NaOH in a small part of the methanol first and then adding this mixture to the rest of the methanol of the batch? It is much easier to shake a 5 liter jag then a 20 liter one. Does the methanol and NaOH have a saturation point?
All the best,
Yes you can do this.
Yes it does, but I do not know what it is.
It has been a long time since I have used NaOH. Like most people on the forum, I have gotten lazy and now use KOH
Let us know how things turn out.
I just had a quick look and found this page which gives the solubility of NaOH with Methanol as 23.8 g/100 mL
http://www.cheaperchem.com/casutic-sodaThis message has been edited. Last edited by: Tilly,
Just be careful of the heat generated when you mix the large amount of caustic into the small amount of methanol. Its an exothermic reaction and I have had the methanol actually boil from adding too much caustic too quickly to the methanol.
If your using a HDPE plastic container to mix the caustic it could deform if you get it too hot too.
Thanks Tilly,Dgs and Jon,
Well I have done the mixing this way and the small container did become boiling hot and I had to open the cap allot to release pressure but i was done mixing it in less then 5 minutes . It is potentially more dangerous I think .Adding this methoxide to the rest of the methanol resulted in less heat in the total amount which I wonder if it affects the bio diesel reaction.
I think this bigger batch (80L oil) was a bit less converted then the test batch I have done . In the 3/27 test I had a bit of oil settling - Out of the 3 ml oil I had 0.2 ml oil settle to the bottom which is 6.6% of the 3ml. Does this mean if all the 3ml dissolves its 100% conversion? In this case I would have 100%-6.6%= 93.4% conversion? Is it a right way to measure it?
All the best and thanks,
Yes, you have measured it in the correct way.
It depends what vehicle you will be using it in if the 6.6% is acceptable, please tell us.
I'm sure that there will shortly be a post from Tilly, stating that the 27/3 test overstates the dropout. Although this may be the case if you take it as read ie 6.6% you will be OK.
No, this is not correct.
The 3/27 test is only a pass/fail test.
If there is no fall out that means the biodiesel is around 98% conversion or better.
If there is fall-out that means the conversion is less that 98%.
Repeated testing has shown that the 3/27 test IS NOT an accurate test for determining percent conversion.
It is disappointing that Dgs continue to give incorrect information about what the 3/27 test is capable of telling you.
There has been no testing performed that clearly shows whether it will overstate or understate the conversion at any particular amount of dropout every time.
All that we both know for sure is that the 3/27 test Is NOT a test for percent conversion and pretending it is is not helpful.
Telling poeple the 3/27 test does tell conversion percent does not help anyone
Here's another way of saying what Tilly is trying to get accross:
The 27/3 test can be described as a qualitative test of your fuel's ability to fully dissolve in methanol. Due to many uncontrolled variables, e.g. soap content, temperature, methanol purity, etc., it is not an appropriate method for accurately assessing the remaining unreacted glycerides in the form of mono, di, and triglycerides that also have different solubilities in methanol.
In my opinion, the 27/3 test is a good qualitative test method and a very unreliable quantitative test for glycerides in your fuel.
Just because Tilly said it doesn't make it wrong. IMHO he's pretty savvy about biodiesel, and about getting under people's skins.
Got Renewable Fuel?
Most of us would agree with that.
So a bit confused now. If there is no dropout at all you have more then 98% conversion and if there is any dropout you have no clew about it. Which would mean that for a naked eye that could miss tiny microscopic dropout particles this test is not even good as a pass/fail test?
Is there any way for the home brewer to have a clew about how well was the conversion?
Do you guys or other home brewers get no dropout at all in this test?
If I do have dropout now there are many things that could have caused it, from chemicals quality to processing time , mixing and more?
I am planning on using the bio on two vehicles: Toyota Hilux 96 with a 2L pre chamber engine which is now running on a two tank SVO system, the bio would replace the diesel.
A 99 VW with a non turbo direct injection. This model is intended for running on both Diesel and B100 (which meets European standards) which is way I want to try and make high quality Bio.
Thanks a lot,
To start with I would strongly advise you to obtain a proper dropout tube so you can do a 10/90 test which is far more accurate than a 27/3.
Although Bob is correct in that the contaminants get in the way of the test, they don't seem to effect the result, only serve to make it longer to read(when the methanol phase is clear)
Even though there are anomolies with the test it does serve as a good guide when adding 2nd stage chemicals.
The lower the amount of dropout, the more accurate the test is.
You do have to keep in mind this is a 25 cent backyard test and will not give the same results as an $85 GC test.
It also depends at least in part on how you read the results of the test.
The test is finished when the methanol is bright and clear. You can wait for hours for this to happen or it can happen immediately, sometimes within seconds.
Testing I have performed showed that the higher the conversion of the biodiesel being tested the quicker the methanol will clear.
If you really want biodiesel of the highest conversion, then set a time limit for how long it takes the methanol to go bright and clear.
Many people report they routinely make biodiesel that passes the 3/27 test. I have made biodiesel that gives bright and clear results in a matter of seconds.
However, since my car has an IDI 5 cylinder Mercedes diesel, conversion is not important to me, just clean separation of glycerine and biodiesel.
Yes. Historically, it seems that insufficient/ inadequate mixing caused by using too small a pump is the main cause for an incomplete reaction which results in not passing the 3/27 test.
My first diesel was an IDI Isuzu Gemini/ I-mark with a rotary pump (Denso I think) and it ran on pretty much anything.
I have just read Jon Heron's reply and I agree with what he has said.
Jon makes a lot of biodiesel!
You do not seem to understand this.
Repeated testing has show no mathematical formula that will give you an accurate reading on the percent conversion by measuring the dropout in a 3/27 test, no matter how long it takes for the methanol to clear. End of story.
We are not talking about second stage chemicals, we are talking about whether the 3/27 test gives a reliable reading on percent conversion. At this point it does not.
I am patiently waiting for Drum to finish his testing to see what he comes up with.
Can you explain what you mean and the tests you performed and their results.
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