Biopowered - vegetable oil and biodiesel forum
Biodiesel => Chemistry and process => Topic started by: dgs on July 20, 2016, 10:56:15 PM
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I thought I would take advantage of the warm weather today. I had an IBC of good oil (700 litres) and 100 litres of glycerol, some used once for pre-treating and some virgin ex -process.
Mixed for 1 hour with my jabsco self priming pump, about 40lpm (not really ideal for the job, hence my post asking for another TAM 120)
Just checked now, 4 hours after stopping the pump and nice clear oil on top with the glycerol at the bottom.
I have actually done this before with an IBC that I used to keep in my polytunnel.
The extra tap on this IBC is set at the 350litre mark, so I can add more glycerol or oil and re-pump the contents.
When the glycerol height gets to 300 litres I will run some off and add fresh.
It just saves doing a separate glyc wash for every process.
I don't know how long I can do this for as the weather turns colder but we will see.
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Why don't you get a Clarke bip1000. £60 new and you could run 4 for the same power consumption. Or add it to the Jabasco and get 80Lpm turnover.
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Good idea Manfred. The only thing is that when I come to add more glycerol or oil, when the bottom tap is opened to the pump the glycerol is really thick so I need something really powerful to start the mixing process.
After the initial mixing then it is easy.
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Dave. PM sent. Hope you see this before 18.00. Gaz.
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Sorry, missed it. Just looked on forum now.I pm'd anyway.
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I just added another 100 litres of oil and 70 litres of glycerol and re-mixed, all seems to be going well so far.
It's just short of the 1000 litre mark in that IBC so next time I have some glycerol I will mix it in another.
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What effect is it having on the titration doing bulk pre treating. You know that it's going to be very dry if nothing else and no glycerol carry over.
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Good question Manfred, I don't know is the answer.
I use low titration oil for processing, so I would assume the oil doesn't now show any titration. The glycerol pre-treatment using the normal amount of glycerol from the last process can usually neutralise oil that titrates up to around 2.0 (depending on amount of glyc and how chemical rich it is) after that the normal amount of glycerol will struggle to achieve zero titration unless it is enhanced with a small amount of methoxide.
What I am saying is that if a glycerol pre treatment is going to be done then ideally it needs to neutralise all the ffa's in the presence of glycerol so all the resultant water is absorbed.
oK, it will help the process even if it reduces the titration but it is a lot of work to still leave the oil with a positive titration, just to produce more water when the methoxide is added.
I will titrate it now and report.
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Suprisingly enough Manfred, it still has a titration of about 0.5 (KOH)
This oil is not the best that I use for my road fuel process but even so I'm suprised by the result.
Either this oil originally titrated higher than I thought, or (as I suspect) the ambient temperature glycerol mixing at around 25degs does not allow as much of a chemical reaction to take place. If this is the case this type of ambient mixing even at this time of year is not going to be as useful.
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0.5 is still low enough to get straight into processing and also no or little drying needed.
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Thats true Manfred. The other reason I'm thinking is that the gentle mixing with the jabsco isn't sufficient.
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0.5 is still low enough to get straight into processing and also no or little drying needed.
That is true Manfred. The other reason the oil still shows a small amount of FFA's is possibly the over gentle mixing with the jabsco.
i will have to re-mix for 1 hour with Rosseys 120 when it comes.
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I ran some oil off one of the IBC's yesterday where the oil is now stood on glycerol. I added some more oil and glycerol. In the absence of the TAM 120 (soon in transit, I hope) I used compressed air from the small compressor via the bottom tap to mix the contents.
It did an excellent job, I checked last night with the torch and the glycerol layer had settled nicely.
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I've continued to pre-treat the oil for road use in the 600 litre IBC. I let the glycerol build up to 100 litres or so, then when I have more I run some off before I re-mix. When I have more oil I sometimes re-mix with the glycerol already in the tank.
I now use a 1/2hp compressor for the mixing which is a lot cheaper to use than the TAM120.
Two local brewers who don't pre-treat give me their glycerol, so sometimes I have 50 to 60 litres to go in.
Some of the oil can be treated 3 or 4 times doing it this way. The appearance of the oil is totally transformed doing this, also the oil in the IBC presently gives 7.5mls dropout with a 10/90
I used 75% of base catalyst for my last process and had a pass in one stage using 11% methanol.
I will post some photo's later today.
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(http://i67.tinypic.com/28br2fn.jpg)
Here is the photo of my IBC. The glycerol layer is clearly visible at about the 30 litre mark. The oil in the cubie is from the IBC, it wasn't dark to start with but considerably darker than it is now.
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Is all this pretreating done at ambiant temps?
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Is all this pretreating done at ambiant temps?
Yes it is. In the midsts of Winter it doesn't work quite as well but as long as the temp is 10degs or over it works fine (maybe not quite as well as heating it but not far off) Many energy saving advantages to this method though as no heat reqd and I now mix it only with the 1/2hp compressor instead of the TAM120 so only 25% of the electric is used.
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24 hours ago I treated 150 litres of WVO with glyc at ambient temps for the 1st time.
The glyc has still not separated.
I imagine the cure is to heat it up, pump it around for a while & then wait for it to settle, which is what I'd normally do anyway.
Just wondering why I've got no split.
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That is really strange. I have always had separation even at less than 10degs although the colder the temp the longer it takes.
I actually did a glyc wash a short time ago, 450 litres of oil and 80 litres of glyc. Compressor has been stopped 45mins after 1 hour of mixing. Already I can see the glycerol pooling at the bottom of the 600 litre IBC.
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I know this sounds really stupid but for the last few glyc washes I have added some of my 50/50 glyc /water from the 5% prewash method. The resultant oil seems to be lighter in colour.
So today the mix was;
450 litres oil (already glyc washed in the 600 litre IBC)
Added 100 litres of oil
Added 70 litres of ex process glycerol.
Added 30 litres of wet glycerol.
Mix temp was 19degs. It was mixed for 1 hour.
All this added as it was being mixed by the compressor. I will take a sample tomorrow and test for conversion and water. I've tested glyc washed oil for water before when mixed with wet glycerol and it has always been <500ppm. However this mix had 15 litres of water in 85 litres of glycerol.
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Tested the oil today:
Dropout using 10/90 was 7.5mls
Water 380ppm (even though it was washed with glycerol containing at least 17% water)
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Good stuff Dave,
Its times like this I wish I had kept notes instead of putting it online and it getting lost in forum upgrades, anyway I think it was Frank the chemist "Neutral" on infopop who did tests on the amount of water glyc can absorb, I did some basic throw amounts of water into glyc and see tests and found it has an amazing ability to suck water up, so I'm not surprised that your water laden glyc still has little affect on its cleaning ability, especially mixed witha large amount of dry glyc.
Why not try a small test with just some water laden glyc and cruddy wvo, I bet it still does a good job
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Thanks Chug, I'll do that.
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One point about conversion that I have been intending to make-
Ive begun to think that ex process glycerol, even when well settled, contains locked up bio.
If I ever add ex process glycerol to a prewash, I only ever get about 50% back out again, even if I settle for days..
I've never done the sums as to the volume that stays in the reactor, and the conversion test of the feedstock, but I would be interested to know how they compare?
I have also thought that there should really be no catalyst left in the glycerol of a well calculated process, so, again I wonder about conversion?
This sounds like I'm disagreeing, but it's more of a comment - it's interesting stuff to get to the bottom of, and, as with all of this, there are so many variables that it's all just "sometimes" or "most of the time" etc anyhow!
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Hi Julian, Yes I think you are correct on most points.
There is certainly tied up bio in glycerol, even if it doesn't show on the surface. I dried some glyc in a tea urn for several hours (this was an expt that didn't work) then added it to some oil. The oil went really dark. HC2 said the retained bio in the glyc had been burnt during the long drying process, I'm sure he is correct.
There is more catalyst in the glycerol than realised. Because we tend to skimp on the methanol the chemicals left in the glycerol are biased towards the catalyst. Under certain circumstances a fair degree of conversion can be achieved by enhancing the glycerol with methanol only.
A lot of the volume retention noticed when glyc pre-treating is due to 1; soap. (glyc contains around 40% and some of this will remain suspended in the oil. For those who have ever re-titrated after glyc pre-treating the soap retention will affect the titration so the oil may still actually titrate higher than it seems. and 2; the glycerol itself is partially retained in the oil, I have found this is very roughly 2 1/2 litres in a 200 litre batch after 24 hours.
Because of my larger volumes when glyc washing in the 600 litre IBC I never notice any increase in volume and as the treated oil is pumped into the processor any increase is never taken into consideration when measuring yield.
Just to add, the way I do it (using mostly other peoples ex process glyc) to achieve around a 20% conversion before processing, leaves me using a maximum of 12% methanol and equivalent to about 6.5 gms KOH/litre for full conversion.
Nowadays I would never attempt to convert any oil that had a positive titration. what would be the point in wasting my own chemicals when I can use the residual chemicals in other peoples glycerol to do the same thing.
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Hi Dave
All very interesting as always and you have me itching to have a go at treating in bulk. I have a 600litre ibc that I can use with a decent tap at the bottom. I gather from this thread that you favour bubbling air in at the bottom rather than circulating with a pump. I take it that even a large aquarium bubbler would be too small for the job but I wonder what sort of compressor would be suitable? I have a little Clarke piston compressor but that would be in pieces if I left it running for an hour and it’s so noisy. What type of compressor is yours please?
Kind regards to all
David (Leeds)
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Ive used a compressor from a fridge before
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I use a Broom Wade small compressor (like the one Tony had at the bbb 3 years ago) he rekoned the output was 2 to 3 cu ft/min which equates to between 57 and 86 litres/min. It seems to be as efficient as the tam120 at mixing glyc and oil. As the IBC is outside any methanol fumes arn't an issue.
I started using it as it is only 0.5HP so uses 1/4 of the electric consumed by the 120
I've never tried a fridge compressor but obviously worked for KH
My IBC faces South and with the good Weather we have been having the last mix was done at nearly 30degs.
I think an aquarium pump would be too weak, the compressor really churns it up.