Biopowered - vegetable oil and biodiesel forum
Biodiesel => Chemistry and process => Topic started by: John Galt on July 14, 2014, 07:08:50 AM
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At
http://www.biopowered.co.uk/wiki/Two_stage_process_with_no_titration
The formula states that 2nd stage is
remaining 20% of the methanol" with "unprocessed oil volume x base" catalyst.
however when one runs the example for 100 liters through the calculator at
http://www.biopowered.co.uk/forum/tools/notitration.php
with 10% drop-out, the calculator does not show 4 liters for the amount of 2nd stage methanol required, [ie."remaining 20% of the methanol"] instead it shows 2 liters, as if one was calculating the amount of methanol at 20% for the 10 liters of unreacted VO.
Which is correct? The formula posted, or the calculator?
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The methanol should be added for the remaining, unconverted, only.
I would also suggest that 20% (of the remaining) is excessive, as there will be residual methanol in the solution from stage 1.
Personally, i use 10% (of the unconverted), however, im sure others do differently.
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Ah - yes, this is probably a hangover from the older days of experimenting with two stage processing.
Essentially, both should work. But you may save some Methanol by using 20% of the unreacted volume, rather than just dumping in the remaining Meth/Methoxide mix that you have.
Excess Methanol is never a problem aside from the extra cost of Methanol, and having to recover more at the end if you're into reclaiming the excess Meth for the next batch. We will amend the wiki page - thank you for your input :)
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Tony,
I think excess meth can be an issue. I made a pigs ear of a batch ages back, when i kept adding catalyst + 20% meth (of the unconverted) on a batch that would not drop the glycerol.
In hindsight, i now realise that my 90/10s were (probably) being thrown off by the glyc still in solution, and i just kept on adding meth : /
What i should have done is add the caustic in a small amount of meth, and it would probably have split, but i wasnt smart enough for that (or it was late, i was covered in oil, frustrated, and all the rest - as usually happens when it goes wrong!)
Anyhow, im sure that, at the end of the mess, it was the excess methanol messing things up.
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"this is probably a hangover from the older days of experimenting with two stage processing."
Which is "a hangover"? Is the calculation page valid?
Where is the current information on two stage 'no titration' processing?
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"this is probably a hangover from the older days of experimenting with two stage processing."
Which is "a hangover"? Is the calculation page valid?
Where is the current information on two stage 'no titration' processing?
Hi John, yes it is.
Initially when we were experimenting with titrated two stage we would mix up the methoxide as per normal for a single step batch, but split it into two steps, the first using 80% of the methoxide, draining the glycerol, then putting the remaining 20% of the methoxide back in.
But the titrationless two stage requires measuring the unreacted volume after stage 1.
Because the process was evolved, I think the wiki page still had a guideline the followed the titrated two-stage process (this was the hangover from the titrated process). This has been updated now to reflect that this was not correct, both the wiki page and the calculator should now tally.
In summary, for stage 2:
- measure the dropout and calculate remaining unprocessed oil, this is used to calculate the methoxide as follows
- "unprocessed oil volume x 20%" methanol
- "unprocessed oil volume x base" catalyst
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Is anyone using this 'no titration' method with consistent success?
While updating the wiki page it might be a good idea to modify this statement to be more understandable
"what you are doing is a softly softly approach"
Why "softly softly" ??
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Is anyone using this 'no titration' method with consistent success?
Consistent, yes. Constant, no.
I very much doubt anyone has constant success with any method that they do not modify, on the fly, with their experience.
At the start, your experience will be lacking, so luck will be required also (and asking for help if needed).
"softly softly" -
You do something softly. And then you do a bit more in a soft way.
Ie you add a smaller amount of base than otherwise. And then you add a small amount again.
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If you don't want to use the softly softly approach you could always move on to the slightly more advanced method, the slowly slowly catchy monkey reaction, I've never had a bad batch using it.
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some batches need 12grs or less base (Kohl), some need 18, 20 grs. I do a Dr pepper test using a base of 12 to give me a guide.
I think that some of the more experienced on here can tell just by looking at the wvo.
Or maybe theres a taste test :o
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The very best brewers rub themselves in the oil then see how far they slide on a succession of tarps to work out what reaction method to apply.
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Is that like a tit test, average of three trails? :D
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I work with me own method, if it looks like it, smells like it and tastes like it it is without doubt WVO so I use it, job done.
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Yes, consistent success using this method and ASM
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Yes, consistent success using this method and ASM
An' I don't not neva get bad batches wiv ASM, been using it for years now, y'can't wack it for supa bio.
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So you only put 20% meth of the unconverted veg after stage not the remainder if the 20% from the first stage?
Have I been overdosing?
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I only use 15% methoxide on both stages, so yes you've been well over dosing.
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Is that 15% of the drop out you on the first stage aswel?
Ie 100litre batch = 15lt of meth for first stage
0.1 drop out = 150ml of meth for second stage?
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Since reading a post on here a couple of months ago about 15.8% methanol used, I have been aiming for around 16 to 17 % total used and have had no problems. i also find that i only get 1 or 2 ltrs of meths on the final demeth on 100 ltr batches.
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Is that 15% of the drop out you on the first stage aswel?
Ie 100litre batch = 15lt of meth for first stage
0.1 drop out = 150ml of meth for second stage?
Yes but I am using ASM so no water is created in the methoxide, if you're using KOH or NaOH go for a little more, say 16 - 17% first stage and 15% second.
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Since reading a post on here a couple of months ago about 15.8% methanol used, I have been aiming for around 16 to 17 % total used and have had no problems. i also find that i only get 1 or 2 ltrs of meths on the final demeth on 100 ltr batches.
If you don't put the methanol in you can't get it out.
As I'm using ASM that is included in the 15% but I still get 3 - 3.5ltr back in reclaimed, mind you I do have a squirrel so demething is very efficient.
My total methanol input is around 14 - 15% including the reclaimed.
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I make 90L batches with 11L of methoxide (koh) for stage 1 and 3L for stage 2. I get a nice clear pass on the 10/90 after the second stage and recover about 1L of methanol when demething. The input is 15.5% and the amount consumed in the reaction is 14.4%. I used to use more, but it didn't make the reaction better, it just made demething take longer.
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My total Virgin meth per 100ltr batch is 10 - 11%, just love saving money.
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Yes, consistent success using this method and ASM
What is ASM ?
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Yes, consistent success using this method and ASM
What is ASM ?
Anhydrous Sodium Methylate, a liquid sodium based catalyst without the presents of water.
We use a 30% sodium solution the remaining volume is 99.9% methanol.
I worked out a very simple formula for its use and it's getting very popular over here.
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Yes, consistent success using this method and ASM
What is ASM ?
There's info on the wiki about it here ... http://www.biopowered.co.uk/wiki/Anhydrous_sodium_methylate
and here ... http://www.biopowered.co.uk/wiki/Processing_with_anhydrous_sodium_methylate
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Thanks for the info. ASM is not an option here. It's difficult enough getting methanol, and only NaOH is available.
So, to rephrase the question:
Is anyone getting consistent success with the no-titration method using methanol and NaOH as described in the wiki?
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I get very good results using two stage method with koh and dry wash I do use mainly rapeseed oil only ever washed once or twice on my very first batches three years ago run b100 all year in three motors
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I get consistent 2 stage results, but I overdose on catalyst as part of my process. (Source oil need to be very dry for this!)
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My 2 stage results are very consistent
Glyc wash
Stage one
test
Stage 2
pass
Quantities vary in stage 2 depending on how bad the oil was to start (3 out of the last 4 batches have had a 1st stage good enough pass) with but I've never ended up doing a 3rd stage since I started doing a glyc wash. Admittedly I err on the high side with the catalyst in stage 1
Using around 17% meth overall I reckon. I probably should get more accurate measurements but if it ain't broke etc etc :)
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@Jmg "I err on the high side with the catalyst in stage 1"
What does " err on the high side" amount to in grams of NaOH per liter of UVO?
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@Jmg "I err on the high side with the catalyst in stage 1"
What does " err on the high side" amount to in grams of NaOH per liter of UVO?
I use KOH at roughly 7g/l, my current batch has .05ml dropout in a 5/45 test, at that level I usually call it a pass and carry on although a few of the batches I made with all liquid oil had no dropout after stage 1 at all.
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Hello John, it's been a long time since I've read a post by you, how are you? are you still a regular on infopop?
I've been doing titless with NaOH for years, longer than anyone else I think, and most of the peeps who are now using ASM used to do titless with NaOH, or maybe titless and KOH, I dunno whats happened but it used to be quite sensible here.
What method are you using yourself these days?
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Chug, thanks for the info. Yes, I sometimes look at infopop, however traffic has reduced significantly. Most of the activity is in the Ireland biodiesel section.
For variable quality UVO from a variety of small suppliers the traditional one stage titration method has been mostly successful. However titration can be tedious and if the reagents are not made fresh, then the results can be misleading. There were a couple of batches of over-reacted BD with soap/glycerol dissolved in residual methanol that passed through a 5µ filter, but then deposited 'gummy varnish' in the fuel system when the methanol evaporated in the warm tank. Residual soap/glycerol is a much bigger problem than a few percent of unreacted UVO.
One major supplier has changed their kitchen procedures to cater to a 'high end' market and the UVO is now much better quality with no PHO or animal fats, and gives consistently low titration. Therefore I've been considering using the no titration two stage process with that oil.
What base amount of NaOH are you using for the first and second stages?
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I never really got on with no titration when I was using NaOH, it was just too fiddly as my plant didn't lend its self to mixing additional small quantities of methoxide.
The other draw back I perceived was that a 3/27 test can take several hours or more to drop all the oil, so using it as an instant test isn't that accurate, just an indication.
I used a similar method when using ASM but I looked for different phases of the conversion to judge how much catalyst to add. First stage would be taken just passed the point where the mix would start to drop glycerin, and then a second stage run using a 3/27 test to confirm full conversion at the end.
Recently I've gone back to methanol and NaOH using the standard two stage process, but reducing both catalyst and methanol. Usually the reduction is guess work but I recon it's probably around 8-10%.
I haven't yet tried the phase changing idea with methanol and NaOH ... I'll give it a try on the next batch. I suspect it won't be so apparent with NaOH as with ASM.
John, if you want a little reading on the phase changing observations, see here ... http://www.biopowered.co.uk/forum/index.php/topic,1264.0.html
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Just found this thread and would like to say I use this method. First I notice that the calculation for the first stage uses 80% of the total methanol and 100% of the base. If this process came from from dividing the total mix into 2 lots, then the 80% lot would also contain 80% of the base. Why does the first stage base use 100%?
If I use the second stage amounts as calculated, I always end up with an incomplete reaction and have to add a 3rd stage. Typically I have to increase the measured fall out by a factor of 1.5 and use this in the calculation to end up in a complete reaction. (i.e. if my measured fall out is 3.6ml, I would plug 5.4ml into the calculator)
Having said this, if I had only used 80% base in the first stage, I would likely wound up way short of base. I built a a measuring device to give me a 14/126 ratio to get accurate fall out data.
I prefer this method as I assume, all the unknowns such as water in the reaction etc. are no longer a factor for the second stage and I can't figure out why the second stage calculated values do not work for me.
There is some truth to previous comments about experience, as I notice more dark oil stock being used, I will up the base amount slightly.
Comments appreciated.
Jeff
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I use NaOH in my two stage process. As such, there is a delay in the second stage while getting the NaOH to dissolve in the Methanol. Was wondering if I could use KOH (faster dissolving) in the second stage. I do not use the glycerin for soap making. First stage I mix up the day before I start a batch. Can anyone think of a reason this should not be done?
Thanks Jeff
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No reason as far as I can see. If you know the quantity of NaOH in a given volume of premix, just add the second stage by volume of methoxide.
How are you mixing you methoxide? I use the mixer shown on the wiki ... http://www.biopowered.co.uk/wiki/Methoxide_mixer#Methoxide_mixer_design_1 (http://www.biopowered.co.uk/wiki/Methoxide_mixer#Methoxide_mixer_design_1) and it never takes more than 5 minutes to get quite quite a heavy dose dissolved.
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Spent the last couple of days thinking about my results from previous batches and why the no titration formula doesn't work for me and probably others too. Lets do a hypothetical batch with the following. Batch 100l, Methanol 16l, Base 5.2 NaOH and use a 14/126 test tube for drop out measurement. Drop out measures 2.1ml which is 15% or 15l unracted oil. (2.1 / 14). Here is the flaw in the published formula. If you continue to use the same base (5.2) for the second stage, you will end up with still 15% of the 15l unreacted. (2.25l in this example). This requires (theoretically ) an infinite number of stages to complete the reaction. Not two.
Also, since the first stage reaction is incomplete and a significant amount of methanol remains, the formula demands additional methanol to excess. Here is what I have so far.
Use the formula for calculating the first stage and measure drop out. As you will come to realize, the drop out measurement accuracy is the single most important step. Next, I added 5 iterations of calculating the base required and added them up. i.e. first stage unreacted X base,plus second stage unreacted X base plus.....a total of 4 times. The fifth simply adds the same amount as was calculated for the fourth stage as we are getting some relatively small amounts at this point.
I reviewed my batch history and as stated in previous posts, second stage was calculated from the published formula then a fudge factor was applies (largely a guess) adding additional methoxide. And yes there were occasions where I would guess wrong and end up with a third stage.
I used data from my batches applied them to my new formula and compared calculated total NaOH to the total actually used and the totals correlated reasonably well. Worst case was off by 7.5%. (remember the actual amounts used were arrived at by a swag.)
Additional work need to be done for the methanol calculation. I had been using a processor from which I recovered the methanol after second stage. I did this to reduce the amount of methanol remaining so I could effectively bubble dry the methanol out prior to my dry wash. What I noticed is there was a close correlation to the second stage methanol added and the amount recovered indicating most of the second stage addition was not required. The theory states that 12.5% of the methanol will be consumed by a complete reaction. Our first stage is not a complete reaction hence considerable methanol remains available for further reaction.
One additional foot note. Drying the oil is also important. A high moisture content will consume some base quantity therefor stopping the reaction sooner. Presumably, this amount of moisture will not be present after first batch draining of glycerol. This will result in a drop out percentage that will be higher than needed for subsequent calculations leading to excessive methanol and base additions. My current threshold for moisture content is 500 ppm max.
I am moving to new equipment that will not allow demething so working with the minimum amount of methanol will be an important detail for me. Will go back and review the second stage methanol calculation shortly. I will post my spreadsheet calculator when this is done if anyone is interested. Hope this helps.
Jeff
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The 12.5% of meth consumed is an average.
Depending on what your feedstock is made up with meth consumption can vary between 11 and 16%+.