From WVO

[gwalker Senior Member Find all posts View Profile Close gwalker]

Re: From WVO

..
Assuming that you get an incomplete reaction at any time, and you do want to get 100% conversion there is no reason why you cannot repeat the reaction ...
I would do the reaction again without any "lye"

Chris,
I understand this to mean that you add extra methonal without lye because there is already enough lye present in the reactor. Is this after the 1st produced glycerine has been decanted or before?

..or have I got it wrong?
G

[Dodge Senior Member Find all posts View Profile Close Dodge]

Re: From WVO

David i would think the viscosity is the more important thing to aim for in the final product, i think the reason for doing the reaction is to remove glycerine this reduces the viscosity and also glycerine is harder to burn.
So the final result is a more flammable oil that is the same viscosity as diesel or close to it, then it can flow through the injector pump and injectors like diesel.
So it would be interesting to see the viscosity of several batches of biodiesel that have different rates of conversion, that may show a more sensible real world target to aim for, but then it may show that 98% conversion is needed to produce a final product that will behave the same as dino diesel.

Crapolla i think i have confused myself.

[Chris Senior Member Find all posts View Profile Close Chris]

Re: From WVO

Chris,
I understand this to mean that you add extra methonal without lye because there is already enough lye present in the reactor. Is this after the 1st produced glycerine has been decanted or before?

..or have I got it wrong?
G

Mate you got this one right
The reaction does produce some water, traces, which is an impediment Decanting the water is a necessary step
We take out any water formed with a centrifuge

[tillyfromparadise Senior Member Find all posts View Profile Close tillyfromparadise]

Re: From WVO

Hello Chris

Do you leave the glycerine layer in or remove it before you perform the methanol only re-process?
Tests have shown that the NaOH that is not in the glycerine layer is fairly quickly consumed turning biodiesel into soap.
How long after finishing the first mix can I wait before performing the methanol only re-process?

The "Standard" reprocess formula is to mix 1g NaOH into 50ml methanol.
How does the results of the methanol only procedure you recommend compare to the results of the standard procedure.

Wouldn't any NaOH that might be remaining in the biodiesel be tied up with the water that you centrifuge out?
While I understand there is a small amount of water produced during the reaction, I have never seen water in the reactor that resulted from the reaction.
If removing this water is a necessary step, what do you do if you do not have a centrifuge?

Tilly

[Chris Senior Member Find all posts View Profile Close Chris]

Re: From WVO

Hello Chris

I am disappointed that you seem to be offended that I question some of the information you posted.
Snip
I am not offended at all Tilly
I am not questioning your credentials or the knowledge of the professionals you employ.
Snip
I am more than happy to be questioned that is the only way we can all go forward I question our techos all the time this forum has helped us along
Making biodiesel is not magic, the procedure is really rather well understood and whether you make 3 tonne or 3 litres the chemistry does not change.
Snip
Agreed
I do question a good deal of the information you have posted as it goes against what i understand the situation to be.
Snip
I have never professed to know everything

* I have never heard of doing a re-process using just methanol with no caustic.
Snip
The basis of using caustic is alter the ph of the oil once this is done is done full stop Methanol in the ratio of 6:1 which is in excess of the mollar conversion is used as it improves the transesterification of the TG's into EME's
* You imply that it takes a "Pressurized Reactor" to obtain 98.5% conversion.- 99.89% conversion is possible in a non pressurized single stage procedure in your kitchen.
Snip
You are geting into heavy ground here Let's see if i can deal with it
There are a number of benefits having a reaction under some pressure
Methanol and oil are non miscible Miscibility can be improved with a higher temperature which is desirable
As the temp raises above 65 c the boiling point of methanol is reached
In a static batch reactor this is not desirable so a slight pressure will stop the methanol boiling off At 1 Atm the methanol will stay liquid up to about 70 C
It is not a problem in a plate column R D Reactor where methanol is forced to mix with the oil in a counter current mode
In so far as percentages of conversions are concerned one needs to define if these are weights of materials or converrsion of the tg's into esters So i will pass on that one


* you said: "using WVO We get as close as 92% in a commercial environment with WVO slowly." People routinely make biodiesel from WVO using the single stage method that passes ASTM which requires a conversion of 98%
Snip
The amount of FFA in your oil will be about the amount of waste you will generate This has no relationship to the conversion rate looked for in the ASTM method that looks for a percentage of converted to unvcorverted TG's into the finished biodiesel
* You say: "with new oil over 95% quite fast"- 95% is probably quite fast with WVO, it is the last little bit that takes time; i hour at 50deg C in a well designed home reactor.
Snip
It is well known that the reaction is driven hard with excess Methanol Pushing it to the right so as to convert the TG's into Esters The mechanics are complex, in simple terms as little as .5% of water that is naturally formed in the reaction will slow down your reaction So you have an initial high rate of conversion which slows down as it proceeds due to water formation in the main The situation becames more complex with WVO due to the fact that the oil may be a mixture of oils with different characteristics as well as different ratios of conversions within these various oils In other words you can adjust your parameters say with new Canola oil as you know what the different Acids it is made up from acids in this case meaning TG's not an impossible task with WVO unless you do a full chemical analysis a very costly excersise
* You talk about a "complete reaction" and a "high conversion". What do you mean by "Complete Reaction"?
Snip
Se point above
* You said: For home production given some simple steps with some well thought out variations to the reactor one can get complete conversion with a fairly high yield"- This is not magic, people have routinely been making very high conversion biodiesel (98%+) for years in a single stage using WVO with a hot water heater as the reactor.
Snip
Agreed Than you can tell me we are in furious agreement?

Tilly

Thanks for the Challenge Tilly have a look at your PM there is a link there have a read of it as well as all the cited references please
We can than pick up a further discussion on the subject
I will now quote our cybor guru favourite Greek dude " I know that I know Nothing"

[tillyfromparadise Senior Member Find all posts View Profile Close tillyfromparadise]

Re: From WVO

Hello Chris
The link you PM'd me was talking about Acid Esterfication and acid/base procedures. I could not spot anything particularly relevant to our current discussion.

In your latest posting, in response to my statement:
"I have never heard of doing a re-process using just methanol with no caustic
you responded:
"The basis of using caustic is alter the ph of the oil once this is done is done full stop Methanol in the ratio of 6:1 which is in excess of the mollar conversion is used as it improves the transesterification of the TG's into EME's
This is not correct, biodiesel is an oil and oil does not have pH.
The basis of using caustic is to neutralize the FFA's by converting them into soap and to provide the catalyst for the reaction.
There is also a side reaction running at the same time that is consuming the caustic by converting biodiesel and Veggie oil into soap.
Once the NaOH is used up in this side reaction the reaction stops regardless of how far the reaction has gone or how much extra methanol you add. In order for the reaction to continue, more NaOH/KOH mixed in methanol must be added.

What do you mean"Heavy Ground" when discussing pressurization?
All pressurization allows you to do is increase the temperature of the reaction which increases the speed the reaction occures at.
A good rule of thumb is, provided your reactor is of sound design, you use the correct procedures, and the correct amount of chemicals:
At 50deg C the reaction takes about 1 hour
At 60deg C the reaction takes about 30 minutes
At 70deg C the reaction takes about 15 minutes
At 80deg C the reaction takes about 7.5 minutes.
Neutral performed some tests which showed that pressure was not necessary to keep the methanol from boiling until the reaction temp reaches about 70deg C.
This is not rocket science.

You said:
"In so far as percentages of conversions are concerned one needs to define if these are weights of materials or converrsion of the tg's into esters So i will pass on that one"
Fair go! You were the one talking about conversion % when you were answering Dave's question about Conversion. Do you really want us to think you did not know what you were talking about?
You are the one who makes 3 tonne of biodiesel an hour. Conversion % means only one thing in biodiesel talk.
You and Dave and I were all talking about conversion as in 98% conversion is required to pass ASTM.

In your post to David you used the three terms:
complete Reaction
highest conversion
high yield

Everyone understand highest conversion, that was what David and you and I were talking about.
Everyone knows what yield is.
What do you mean by complete Reaction?

Now, back to the original question.
Where does the NaOH come from in a methanol only re-process when the usual reason the process stops in the first place is that the NaOH has all been consumed in the side reaction?

Tilly

[Chris Senior Member Find all posts View Profile Close Chris]

Re: From WVO

Tilly
You are quite correct in saying there is no ph in lipids/oils as this a characteristic of polar compounds
Never the less If you where to get any oil add the same qty of distilled water mix it together let the phases separate, you can then read the ph of the oil in that water
It is not a common procedure however it is used Why don't you try it
There is no accepted way of direct reading ph of oils/lipids
If you want to know the proton concentration (ph) in any lipid you titrate
I did use the term loosely should have known better
The neutralisition of free faty acids in the oil will yield either fatty acid esters or soap
It is the ffa's which you neutralise as you quite rightly said
If one thinks about it why would you neutralise something?
You want to get rid of the water formed as it is a proton donnor which effects your process by altering the proton concentration once again after you have neutralised the FFA's
No you will not see any water in the tank
Is it fair to say that once you have neutralise the FFa's the only other component remaining is the alcohol?
Further the test for conversion posted by Tony from the west works just the same way Tilly, 27 ml of Methanol 3 ml of biodiesel Oil or glycerin falls out incomplete conversion, where is the K or N?
Why don't you try any way, it is not that hard as you have said yourself
It works for us

[tillyfromparadise Senior Member Find all posts View Profile Close tillyfromparadise]

Re: From WVO

Hello Chris
You said:
"You are quite correct in saying there is no ph in lipids/oils as this a characteristic of polar compounds"
That is not correct, pH is a charachteristic of Aqueous solutions.
pH is an index of the concentration of Hydrogen Ion (H +) in water. Since oil is not an ionizing solvent, it has no free hydrogen ions and therefore, it does not have a pH per se.

You said:
"Never the less If you where to get any oil add the same qty of distilled water mix it together let the phases separate, you can then read the ph of the oil in that water"
Not exactly, If the oil contains materials which when mixed with water supply hydrogen ions to the water phase, then these will register when the pH of the water phase is measured.

you said:
"The neutralisition of free faty acids in the oil will yield either fatty acid esters or soap"
What is a Fatty Acid Ester? Do you mean a Fatty Acid Methyl Ester (FAME)? As far as I am aware Neutralizing FFA's with NaOH/KOH results in soap.

you said:
"If one thinks about it why would you neutralise something?
You want to get rid of the water formed as it is a proton donnor which effects your process by altering the proton concentration once again after you have neutralised the FFA's"
I have not got a clue what you are saying here. Can you re-write this in English that I can understand?
Whether you want to neutralize the FFA's or not does not matter, it will happen, it is just all part of the reaction. NaOH/KOH will be consume in this reaction.

You said:
"Is it fair to say that once you have neutralise the FFa's the only other component remaining is the alcohol?"
No, that is not correct.
Only a portion of the NaOH/KOH is consumed converting FFA's into soap. That is why we do a titration, to find out how much extra NaOH/KOH is required as a reactant in the reaction which converts FFA's to soap.
We will still have the "Base" amount of NaOH/KOH remaining to catalyse the reaction (And eventually be consumed in the side reaction).

You said:
Further the test for conversion posted by Tony from the west works just the same way Tilly, 27 ml of Methanol 3 ml of biodiesel Oil or glycerin falls out incomplete conversion, where is the K or N?
No, that is not how it works.
The Warnqvest Conversion Test you refer to is just a soluibility test.
Methyl esters are soluible in methanol so they disolve.
Triglycerides are not soluable in methanol so they settles to the bottom.
There is no reaction.

I can recall Neutral performing an experiment where he reprocessed a litre of very high conversion biodiesel using the standard 1g KOH mixed into 50 ml methanol and left it sit overnight. No further glycerine settled out.
He then added some Veggie oil, mixed and still no glycerine settled out. The KOH had all been consumed overnight converting Biodiesel into soap and there was none left to transesterfy the oil that was added the next day.

Tilly

[gwalker Senior Member Find all posts View Profile Close gwalker]

Re: From WVO

Chris,
If you were setting up a small scale 'home' BD production system. What would build and what process would you follow?
G

[Chris Senior Member Find all posts View Profile Close Chris]

Re: From WVO

Tilly, I am out of this one

G
I would go to the journey to forever site and built the "deep thort" which in my view is a simple reactor with all the features that a home brewer would require including an effective simple methanol recovery system
It was built out of stainles steel I see no reason that you cannot save a lot of money by building one out of mild steel
If you visit the local scrap metal dealer and look for a piece of pipe around the same diameter with a flange on it you would have a good start
Alternatively an out of date LPG tank the tall ones, that are commonly used for homes would also be a good start
Good luck

[Chris Senior Member Find all posts View Profile Close Chris]

Re: From WVO

G,
I did not answer all your questions
In so far as process is concerned it is realy a matter of choice as to which one people will use
The outline of the process in the same spot by the designer of the "deep thort" is as as good as any
It is best you stick with one procedure, learn it well, make lot's of batches of biodiesel before starting to change around
There are problems when people keep on changing procedures without having learned how to do it well with just one method
The most important things in making biodiesel are: Dry oil, (no water), Titration 100% accurate, Temperature of the oil (not critical but important), the right ratio of methanol as well as "lye" for the reaction
Expect failures (they will happen) as well as succeses
It is not brain surgury it is also enjoyable

[Maxwell Member Find all posts View Profile Close Maxwell]

Re: From WVO

Hi Chris,fficeffice" />>>
I’m interested in your process of making commercial amounts of biodiesel, I would have expected that you would have neutralised the FFA with acid then done a two stage process under pressure to achieve a better conversion ratio!
Am interested in what process you have and why if you are willing to let people know!
Cheers
Maxwell

[tillyfromparadise Senior Member Find all posts View Profile Close tillyfromparadise]

Re: From WVO

Hello Maxwell

A conversion of 99.89% is possible in a single stage at normal atmospheric pressure.
I do not see much room for improvement using 2 stages under pressure.

Tilly

[Chris Senior Member Find all posts View Profile Close Chris]

Re: From WVO

Hi All
Just a little intercourse as well as a bit of history on the definition of "titration" as well as the concept of neutralising substances in general terms
If we want to determine the concentration of an acid we may react it with an alkali of known concentration
The reaction is continiued until is just complete, that is when the equivalence point is reached
We than use some indicator to tell us that we have reached the point which is refered to as the endpoint
This may be a good or a bad aproximation to the equivalence point
Even though it is fixed for a given reaction it may also vary
The volume of the acid added is noted we can then calculate it's concentration from the stoichimetric equation
In the case of alkali the process is reversed
This method/procedure is known as "titration"
The idea of acids has been around a long time however it did not satisfy observed phenomena
Liebig 1838 suggested acids are compounds containing Hydrogen replacable by metals
It did not provide the why, Arrhenius provided the criteria acids could produce H+ in solutions and bases could produce OH- in solution This effectively empasised the similarity in all neutralisation processes
Never the less there was still a number of observed phenomena which still fell out of these concepts the major drawback being inability to compare acid and base strengths quantitatively, besides the criteria confined acid base reactions to systems in which water is the solvent
The development of studies since then of non acquous solutions has progressed significantly
Lowry in 1923 as well as Bronsted, independently defined acids as well as bases in a simple and elegant way
Acids are proton donors
Bases are proton acceptors
The above difinition has been accepted as the basis in dealing with the subject
If we where to neutrilise our Free Fatty Acids in our oil we take our measured sample and add our solution of K or N both are alkaline
We do that a drop at a time until we reach the point of a colour change in our indicator
It is the nature of the process in which we add a few drops and nothing happens we then add another drop and bingo we have reached equivalence as well as the end point
If one looks at a graph in any chemistry book it will be clear, the graph goes from a very low acidic value to neutral straight up almost vertically to a very alkaline with very little addition of whatever we are using
We use an acid base indicator for detecting the equivalence point in titrations since the indicators themselves are weak acids they are converted into the conjugate bases of a different colour at a particular pH
Methyl red changes colour at around pH=5 while phenolphthalein does it at around pH=9
So either indicator will provide us with the equivalence point in our titration since we will be going from acidic to alkaline even though at two different levels
The point is bought out of the above is that the concept of proton transfer defined by the Bronsted Lowery principle is readily aplicable to non aqueous systems
The equilibrium constants which we measure the extent of the FFA content provide a measure of acid base strength in the oil we intent to turn into biodiesel
Even though the process of titration is similar in both aqueous as well as non aqueous solutions on the basis of proton transfer, donation or acceptance, there is no such thing as pH of oils or lipids
It is the equilibrium constants which measure the extent of solvolysis which provide us with a measure of acid-base strength
Cybor guru needs to put the spell check back asap, it takes me twice as long now to do a post So much of being spoiled

[Chris Senior Member Find all posts View Profile Close Chris]

Re: From WVO

Hello Maxwell

A conversion of 99.89% is possible in a single stage at normal atmospheric pressure.
I do not see much room for improvement using 2 stages under pressure.

Tilly

For your information a two stage conversion under a pressure of 1 Atmosphere will not convert any more than you have quite rightly said
However it will give you biodiesel that does not need to be washed
I would have thought that this would have to be an advantage
I am not intending to go into the ins and out's of this as I am not in a position of sufficient knowledge to do so
Suffice to say that most commercial biodiesel producers do have a pressurised conversion process and they do not use wash, neither do we