Biopowered - vegetable oil and biodiesel forum
Biodiesel => Chemistry and process => Topic started by: countrypaul on December 19, 2021, 07:16:31 PM
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I've just put a batch of rough oil/fat in a barrel with some ASM and methanol, normally I would give it an hour to process at 60C, but this is between 5 and 10C. Can anyone based on their past experience give an idea on how long this should be left to react? Based on normal princples 1 hr at 60C would require about 3 days, but since there is no agitation will it need longer? My past batches like this with good clear oil got left for a couple of months in summer, can't remember why, but did achieve an easy 27/3 pass.
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I've never done it without some sort of mixing Paul, even if only a short shuggle of the cube, so I wouldn't like to say how long with no agitation, maybe Dave has tried it and can enlighten us?
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How much oil is there?
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How much oil is there?
4 barrels (ex mango chutney) each with about 25L of oil and 3.5L of methanol/asm
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I've just put a batch of rough oil/fat in a barrel with some ASM and methanol, normally I would give it an hour to process at 60C, but this is between 5 and 10C. Can anyone based on their past experience give an idea on how long this should be left to react? Based on normal princples 1 hr at 60C would require about 3 days, but since there is no agitation will it need longer? My past batches like this with good clear oil got left for a couple of months in summer, can't remember why, but did achieve an easy 27/3 pass.
I've never done it without any agitation. In a 20 litre container with a few shakes it works fine, even outside in Winter.
When you say 'normal principles' you mean the rule of thumb of 10degs lower= double the process time. For whatever reason it seems not to apply to our process. Biggest drawback is the time the glycerol takes to drop but as regards the actual process you won't notice any difference (mixing aside)
I've been processing at ambient for a long time and must have saved a lot on electricity, especially at todays prices and more so what they will be in the New Year.
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All this would seem very confusing, particularly to someone coming to the game from scratch.
While the ambient processing must work (dgs uses it and gets results) it does seem to fly in the face of everything that is put out on the web.
Reactions generally require heat. I think that is accepted knowledge.
But is the downside of the ambient processing simply the length of time it takes (possibly weeks instead of hours), or is there something else going on ?
Maybe we could have a group-trial. Everyone makes a, say, 10 Litre batch in a cubie following the same Meth/ NaOH mix. Then report back the results ?
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I gave the barrels a good stir but within a couple of minutes a thick layer of methanol/methylate had appeared on the top. I may get a chance to check them (and stir them) late in the week when they have had 4 days to react. I wil try and report results as and when I can check them.
The oil was fairly poor in appearance (did not titrate it) with a lot of fat present, so not easy to compare with decent clear oil as far as results go.
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If you give them a good stir a few times during the first 24 hrs or so I'm sure it will work ok.
As you are doing a reaction on poor, non glyc washed oil surely you are wasting your precious ASM. Just use a bit of cheaper sodium.
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All this would seem very confusing, particularly to someone coming to the game from scratch.
While the ambient processing must work (dgs uses it and gets results) it does seem to fly in the face of everything that is put out on the web.
Reactions generally require heat. I think that is accepted knowledge.
But is the downside of the ambient processing simply the length of time it takes (possibly weeks instead of hours), or is there something else going on ?
Maybe we could have a group-trial. Everyone makes a, say, 10 Litre batch in a cubie following the same Meth/ NaOH mix. Then report back the results ?
There is so much mis-information on the web about all aspects of biodiesel. When I started making bio I had lots of questions that no one seemed to be able to answer. Most of what I say comes from lots of testing and experiments over the years.
The 10deg/double time thing is just a rule of thumb and doesn't apply to everything. It doesn't seem to apply at all to our process. I've processed 500 lts in an outside IBC in mid Winter at no more than 5degs and it doesn't seem to take any longer.
I don't think there is any need to do more trials on this. Many on here now process at ambient.
Just to confuse you further there is also Julians intermittant pumping method. I use my pump for 8 mins per stage and I think Julian has now reduced his mixing even further.
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If you give them a good stir a few times during the first 24 hrs or so I'm sure it will work ok.
As you are doing a reaction on poor, non glyc washed oil surely you are wasting your precious ASM. Just use a bit of cheaper sodium.
I am trying to tidy up alot of stuff at my father's that I should have done some time ago but various little things have been getting in the way!
The barrels are 60 miles away so not easy to give them a good stir a few times in the first 24hrs, they got one good stir and have them been left. You are right about using ASM, but I had nothing else around so decided to use what I had at that point. Not actually sure how poor the oil is, it doesn't look good, but has been settled, filtered and had no free water. Not sure if the gel present was just due to the temperature, or fat. I cannot remember where it came from, but do know it has been stored for over 2 years - and could be much longer! No mould in the containers it came out of which was a bonus. As I said earlier, I may get a chance to check them on this coming thursday and give them another good stir - might even try a 27/3 if all the methanol has been dissolved.
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Can anyone say how long to react ? I made methoxide solution with potassium hydroxide + methanol + some calcium oxide . Using new corn oil with stirring I added the methoxide solution at about 21 degrees celcius . I don't have my notes in front of me on that experiment I left the reaction overnight . After about 8 hours I treated the reaction liquid as if it was done . If I remember correctly I got a 3/27 test pass . If you are processing at 5 degrees with stirring/mixing it should take about 3 times longer or 24 hours , if water , and soap making isn't a factor . Without mixing I don't know how long it might take .
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I've never known it to take any longer at ambient Wesley. However one extra spanner in the works is the fact that when I have done a reaction in my outside conical IBC I nowadays mix with air via a compressor. It works so well and being outside, the fumes aren't an issue.
If it were no for the fumes I would use air to mix my normal process inside, it seems so efficient and the compressor is about 350watts compared to 1500 for the tam120.
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So you would be pushing air at ambient temperature through the oil mix and thus reducing the oil temp quite quickly to that of the outside air, say 3C on a day like today ?
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So you would be pushing air at ambient temperature through the oil mix and thus reducing the oil temp quite quickly to that of the outside air, say 3C on a day like today ?
I don't know how much the air temperature affects the oil/bio mix, probably not a lot. When the compressor gets warm the exiting air is also slightly warm. I have a spare tam120 and used to plumb it up to the ibc but it is 1500w so as an expt I used the compressor (which is what I use to glyc wash with) and found it works really well, it probably mixes better than the tam120.
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What sort of compressor and particularly pressure are you using, I might give it a go.
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What sort of compressor and particularly pressure are you using, I might give it a go.
Its a 50 year old little broom wade (like the one Tony brought to the bbb several years ago) It puts out 2 to 3 cu ft/ min. Pressure will be low, <10psi.
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Going back to the original cause for this thread, looks like some process has taken place in some barrels! 2 had a layer of what I presumed was methanol/catalyst , but less than half the original amount, the other two appeared to have absorbed all the methanol, one seemed to have thinner oil than it started with (which woud be the case if some was now bio), the other looked as though it was brown cottage cheese (not sure if any process has occured. All barrels got another stir, but I did not have the chance to carry out a Warnquist test.
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What sort of compressor and particularly pressure are you using, I might give it a go.
Its a 50 year old little broom wade (like the one Tony brought to the bbb several years ago) It puts out 2 to 3 cu ft/ min. Pressure will be low, <10psi.
Thanks for that might find something to try.
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This may not be the right place for this, but here goes.
I have been doing a few of my little 2 Litre 'test' batches recently. No problems and they have found their way into the fuel tank.
But I made a couple of 2 litre tests over the last two days.
The first one titrated at four Gram.
So I used 200mL Meth and 16 gram NaOH to make up the methoxide. (5+titration per litre x2).
The oil had been boiled dry. and was around 55C when I added the methoxide. Did my usual shake mix over the next hour and left it overnight.
In the morning there appeared to be about the right amount of glyc drop-out. So I did a 10/90 test and so far nothing has dropped out. So it looks good.
However.
Today I did another 2 litre test using the same dried oil. But I thought 'maybe I'll do a sort of two stage reaction this time. That way I will be able to try the drop-out calculation for the second stage.
So I used 190 mL per litre Meth but only 5 g per litre NaOH to make the methoxide. Reasoning that was pretty much what is done in the two stage no-titration process anyway.
The oil was, again, at around 55C, Shake up procedure was the same.
Then I left it on the bench and went inside.
Coming back half an hour ago I fine a bottle of very thick paste. No drop-out.
I have added methanol to bring it up to 200ml/Litre. Stood it in a bowl of hot water then given it a good shake. I'm hoping that I will get some sort of glyc drop-out so I can carry on with a second stage.
What do you think caused this thick paste to form ? I suspect the low temperature in the shed, but Dave (dsg) works at ambient and this doesn't happen to him.
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I do use an ambient reaction but use a mixed 50/50 catalyst. Using just Sodium with an ambient reaction would probably cause trouble.
I don't know why you have thick paste unless its the temperature however the absence of glycerol is probably that you didn't even add enough sodium (if my reading of your post is correct) to neutralise the ffa's so no transesterification would have taken place.
EDIT Reading your post again Dave you say the oil titrated at four grams, do you mean 4mls of 0.1% NaoH. If so then to do a 2 stage on your 2nd sample surely you needed to add titration amount for 2 litres= 8 gms + say about 3.5gms NaOH/ litre which should be 15gms NaOH, not the 10gms you added. Using the 19% methanol is more than sufficient.
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Dave,
The reasoning behind what I did was that, in the no-titration process, you start out with a low amount of catalyst (around 4 Gram/litre, then use the drop-out to calculate the amount of catalyst required for the next stage.
As the normal titration method always requires titration amount + the base amount (4-5 G/Ltr) I would just initially use the base amount for the first stage Then calculate the next stage from the drop-out.
At least that was the plan.
After last night's re-treatment today I have about 400 mL of bio sat on top of a thinner solution that looks as if it may simply be unreacted oil. No discernible Glyc drop-out.
I'll try a second stage and see what happens.
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If you have merely netralised the FFA and had little to no transesterification then you will have produced soap but little to no glycerol. The soap is normally present largely in the glycerol, so with no glycerol present it will be largely in the oil which could result why you appear to have a thick paste. The low temperature will make the paste appear thicker especially if near the gel point of the oil.
Adding the aditional methanol could have helped thin things down slightly, but bearing in mind that the veg oil is not miscible with methanol, the top layer could be largely methanol with whatever would dissolve in it, any thing that has transesterified, impurities that would normally be in the glycerol, and glycerol itself in the methanol.
The second stage should result in transesterification moving much further along and glycerol dropping out.
You could try adding only have the amount of caustic you were planning for your second stage which should result in significant reaction but is unlikley to get anywhere near complete, but should result in some glycerol dropout.
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If you have merely netralised the FFA and had little to no transesterification then you will have produced soap but little to no glycerol. The soap is normally present largely in the glycerol, so with no glycerol present it will be largely in the oil which could result why you appear to have a thick paste. The low temperature will make the paste appear thicker especially if near the gel point of the oil.
Adding the aditional methanol could have helped thin things down slightly, but bearing in mind that the veg oil is not miscible with methanol, the top layer could be largely methanol with whatever would dissolve in it, any thing that has transesterified, impurities that would normally be in the glycerol, and glycerol itself in the methanol.
The second stage should result in transesterification moving much further along and glycerol dropping out.
You could try adding only have the amount of caustic you were planning for your second stage which should result in significant reaction but is unlikley to get anywhere near complete, but should result in some glycerol dropout.
Paul, it isn't often that I read technical posts and think "Ah, I never thought of that" but your 1st paragraph is something totally logical that has never struck me before, well thought out.
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Thanks for the replies.
I mixed up about 20 mL of Meth with about 4 gram of NaOH. Warmed the oil back up to 50C,. Added the methoxide and gave it a good shaking over the next hour. Then let it stand overnight.
This morning I have some thing that looks like a normal brew but has less glyc dropout (as expected).
A 10/90 test shows 1mL dropout I take that as 10%.
So I think my next move is to mix 10% of my original base NaOH (10% of 5 gram/litre x2)=1 gram with a bit of meth and mix thoroughly.
Am I right ?
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Looks ok to me Dave.
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Nice to know that I am getting somewhere near.
But It would not be me if everything went to plan,
As I was about to carry out the last stage, I had to go collect my daughter from the Supermarket. And it was snowing heavily.
So, did the trip, dumped in the methoxide. Then realised that in the earlier confusion I had forgotten to remove the glyc from stage 1.
So it became a three stage project.
A 10/90 test produced 0.5 mL of dropout.
Mixed up a drop of meth and 0.5 gm of NaOH and (after removing the glyc this time) proceeded as before.
I do see a bit of glyc dropping, but will leave it until morning to do the , hopefully, last 10/90.
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Nice to know that I am getting somewhere near.
But It would not be me if everything went to plan,
As I was about to carry out the last stage, I had to go collect my daughter from the Supermarket. And it was snowing heavily.
So, did the trip, dumped in the methoxide. Then realised that in the earlier confusion I had forgotten to remove the glyc from stage 1.
So it became a three stage project.
A 10/90 test produced 0.5 mL of dropout.
Mixed up a drop of meth and 0.5 gm of NaOH and (after removing the glyc this time) proceeded as before.
I do see a bit of glyc dropping, but will leave it until morning to do the , hopefully, last 10/90.
Well done. Yes, you have have to careful removing the glycerol, it likes to 'eat up' chemicals. At least if you can glyc wash with it you will reclaim most of the chemicals. You will have to start using KOH or at least a blend of sodium and potassium, it is so much easier.
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I use NaOH as I was given a 25 kilo bag of it (which I keep very carefully sealed) some time ago.Though I do agree that KaOH is easier to use.
Anyway, I can report that this mornings 10/90 test resulted in zero drop-out after an hour with the sample being held at close to 20C. So I call that a result. It just remains to wash it.
I was thinking about the situation that caused my problem. The paste.
And that adding some meth helped to clear it.
Is there a definite ratio of NaOH to Meth that one mustn't exceed with the two stage no titration method ?
If the 5 Gram/200 mL brought things pretty close to turning to jelly it would appear that it's not safe to pass 4 gram/ 200 mL for the first stage.
I am aware from experience that too much caustic will turn things to jelly very quickly.
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10% methanol isn't a lot, I've had problems with the glycerol not dropping out at that kind of level.
I've never really thought about why, I always put it down to the liquid not being "thin" enough. But then I have a scummy dregs drum that put all the nastyness from the bottom of oil collection barrels into - and to that I add just glycerol, and stir it in with a stick. No heat. That seems to always separate out, but then I do leave it standing for weeks before skimming some good liquid off the top.
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Tony,
I am referring to 200 ml/Litre. That's 20%