What is the lowest percentage of methanol can you use to make a conversion? Would 14% work?
Different oils require slightly different amounts of methanol as a minimum to achieve virtually complete conversion.
The accepted methanol % to get this reaction is 12.5 However because of the nature of the reaction an excess of methanol is required, so most use somewhere between 15 and 22%
I personally use only between 10.5 and 12.5% added methanol, but this can only be achieved if the oil is pre-treated with the glycerol from the last reaction (an easy way to recover most of the methanol from the glycerol)
If you up the methanol % you will find the reaction is easier to get near complete conversion a lot sooner and you will use less catalyst. However if you have no way of recovering the excess methanol from the glycerol or both glycerol and bio together this can be a bit of a waste.
it's all a bit of a balancing act.
I have been using 30 lts to 180 oil ( which is about 16%)and was wondering if 25lts to 180 oil ( 14%) would work. I was wondering if anyone had tried it at 14% before I tried, just in case it didn't work.
I am interested in the glycerol treatment you mentioned. Is there info about that on here please? I have been making bio for a while but use basic methods.I have read about mixing cement into the methanol and let it settle for three or four days and then drain off the methanol. It is supposed to extract the water from the methanol and then you can do cold mixing rather than heating the oil.Have you heard of that?The reason I asked about the % was because I mixed my 30 lts of methanol with 5 kg of cement and after the settling period I ended up with 25 lts. Hence the question.Surely there wasn't 5 lts of water in the methanol.
Can you be more specific about your production procedure and whether the biodiesel you produce passes the Warnqvest/ 3-27 test
This is commonly called a glycerine pre-treatment.
There is a description of it here
What it amounts to is that there will be both methanol and caustic remaining in the glycerine.
If you begin your reaction by mixing this glycerine with the WVO you will be performing a first stage partial reaction with the chemicals already contained in the glycerine.
You then drain the glycerine and perform a second and possibly third stage reaction using just methanol/ caustic.
I do not recall ever seeing this procedure. Can you post a link to the procedure you are using.
In any event you do not need to heat the oil to any particular temperature to perform the reaction.
As long as everything remains liquid temperature is not a limiting factor to the reaction.
The "rule of thumb" is that in a single stage reaction and assuming your reactor is of adequate design, the reaction will be finished in about an hour at 50C.
For every 10C the temperature is reduced the reaction time doubles
I usually use virgin methanol so it is low in water. There is always water present in mixed methoxide but as it is usually at reasonable levels, so it doesn't effect the process too adversely.
I have never heard of mixing cement with methanol to dry it.
Here is a link to the glycerol pre-treatment.
Tilly is correct re the theory of ambient reactions as regards the increased timings, however in practise this is incorrect. I mostly react at ambient temperature and leave each stage around 45 mins, it works very well. If you do this you will find the glycerol takes much longer to settle. If you have enough time to react this way it is really convenient, not having to re-heat etc.
Terracan; The theoretical lowest amount of methanol that would be required to make methyl biodiesel from 1 litre new corn oil is about 120.3117292 milliliters of anhydrous methyl alcohol. But using the 100% theoretical amount would not produce 100% conversion because of the equilibrium reached in this organic reaction. Many organic reactions do not proceed 100%. The more dry methanol you use the closer to a 100% conversion you would get. I make small quantities of various types of biodiesel in a (usually) one litre boiling flask. I do not have a large processor. I usually use about 20%-25% methanol and get what is probably a good result. Biodiesel can be made from longer chain alcohols, that have different physical properties. I studied some chemistry in school. The theoretical amount of methanol number that I gave above is for corn oil. For other types of vegetable oil, like palm kernel oil or flakes the percentage would be a little different.This message has been edited. Last edited by: WesleyB,
That is interesting.
Can you explain what you mean?
Do you mean that at room temperature the reaction is finished after 45 minutes?
Or do you mean that you can achieve "full Conversion" (pass 3/27) at room temperature using the "normal" amount of chemicals in a single stage reaction in 45 minutes.
Both statements are true Tilly. I prefer to do several reactions but if I dosed the oil with the correct amount of methanol and KOH (or as I very often use nowadays a 50/50 mix of ASM/KOH) then for sure the reaction would complete in 45 mins if I added the correct chemicals for a single reaction. The reaction I did today started at 8degs C and I have ended up using 6.5gms/litre KOH and 12% methanol. This includes the chemicals added to the glycerol for the enhancement stage.
Using a very powerful pump the transfer delivery line pressure is 31psi going through an 8.5mm eductor ( using a smaller eductor the pressure was 71psi which was too much) even so the transfer of fluid energy increases the temperature at the end of the reaction to 25degs.
There is a slight downside as it seems as though a higher % of mono's are left after the reaction, but after heating prior to de-mething the increase in temperature seems to convert these.
Have you actually ever done a single stage reaction at room temperature to verify this?
However, you seem to be omitting the chemicals already in the glycerine as well as the time.
An increase in temperature from 8C to 25C just from pumping is pretty amazing.
What type of pump are you using and what amount of oil is in your reactor?
How have you determined the higher percent of mono's?
I do recall that about 10 years ago Myke from SAFF claimed from their processor "After 10 seconds: 99% conversion to ester"
originally posted by Tilly
However, you seem to be omitting the chemicals already in the glycerine as well as time.
I don't ignore the chemicals in the glycerol, after all it is why I pre-treat, to recover them. I can't quote them because I don't know how much is in there!
I have indeed done a single stage reaction at ambient temperature.
The pump is a Clarke tam120; 75lpm 65metre head. Using the smaller eductor at 71psi someone on VOD calculated the jet velocity at 28 metres/sec
Monoglyceride determination is by the amount of emulsified mono's extracted after aggressive water washing. This emulsified layer is kept and separated. It is about 1/3 mono's and 2/3 water.
I have too- but not in just 45 minutes.
Just so I am clear about this,
I have noticed that sometimes when you report things you forget to mention all the stages you perform and chemicals used in a reaction.
In this case, when you say "single stage reaction" you did not do a first procedure that you might have thought of as a "neutralization" or an "Enhancement" or a "pre-wash" or anything else.
You just put WVO into the reactor at room temperature, added the required chemicals and made biodiesel that passed Warnqvest after mixing for 45 minutes.
It would be interesting to know the titration of the WVO as well as the amount of chemicals used.
I have done a single stage reaction (without glycerol pre-treating) at ambient temperature and also after pre treating.
When I have done multiple 10/90 tests during the ambient reaction I have found over 90% conversion after 5 mins.
If the required amount of chemicals are added for full conversion when doing a reaction at temperature the whole mix turns opaque. When this effect stops the reaction is over 90% complete and lasts about 4 mins. At ambient temp it lasts about 5 mins.
Try it Tilly and save some electricity.
My WVO is lightly used and titrates less than 1.5
When I react higher titrating oil for the c/heating I increase the chemicals in the pre-wash so afterwards the oil doesn't display any acidic properties. I also use the M67 for the pre-treatment to save on electric.
It is "common Knowledge" that the great majority of the reaction occurs very quickly- frequently within a minute or two.
You can see it happen when performing a Dr Pepper reaction as the contents of the bottle changes color and viscosity.
However at that point it will not pass the 3/ 27 test.
So once again I want to confirm that you have actually produced biodiesel in a single stage reaction at room temperature (no pre-treatments, neutralizations, enhancements, etc) that passes the 3/27 test after 45 minutes of mixing.
I am also very curious to know the amount of chemicals you used.
Thanks for the replys boys, but I must admit you lost me with the high tech stuff.I have been making bio for over 10 years and have never had one batch pass the 27/3 test. I use my bio in an old Hilux and have done well over 350,000 klm and never had any problems. However, I am going to try and make top grade bio to run in a common rail motor.
I have pre dried my menanol( with the cement) and will make a batch this arvo and let you guys know how it goes ( fingers crossed smily)
If all you want is for separation to occur and are not concerned with passing the 3/27 test, you could probably go as low as 10%- 12% mthanol in the reaction. maybe even lower.
If this is the case, then you need more than 16% methanol with the procedure you are using because right now you are not passing the 3/27 test using 16% methanol.
Why do you think your methanol is "wet"?
Where are you buying your methanol?
I have been told that when you mix methanol and potassium together it makes a certain amount of water.I wouldn't have a clue about that, but I am just trying the method.
I have just made a "batch"( done cold) and it separated nicely at 14 % methanol..
Tilly,once fuel passes the 27/3 test is it then good enough for a common rail motor, or does it have to pass other tests?
I am aware of the method you refer to.
I do not think it is actually cement that is used to dry the methoxide, but a chemical that is used in the manufacture of cement. I will look it up and post a link to it.
Yes, separation should be no problem at 14% methanol. It is very unlikely to pass the 3/27 test though.
Some people will perform water and soap tests too.
Please keep us posted on your results.
I have located the procedure for drying methoxide.
It was developed by Mark Imisides
According to the instructions you actually want calcium oxide/ Quicklime to do the drying
"In principle, this differs from the conventional method in that it modifies the methoxide solution by the addition of a drying agent (calcium oxide, or Quicklime)".
terracan, apologies from Tilly and myself for dragging this thread 'off topic'
It is more important that we give you information that helps you with your bio production than discussing our specialist 'off topic' matters.
If I have something to apologized about I will do it for myself thank you.
The discussion about your claim that the single stage reaction can be done at room temperature in 45 minutes is quite pertinent to this thread
No worries Dgs, all's good. I do want to upgrade my bio and reading what you guys are saying is helping Thanks.
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