dewatering questions

Collecting, filtering and dewatering of WVO SVO vegetable oil. For Biodiesel producers too.

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Postby David » Sun May 16, 2010 9:13 am

othello wrote:
The discussion around your cold upflow system seems to indicate that it works for some people, but not for all. Not everybody lives north of 60.


Not even sure what 60 is although I assume it is a grid reference but I think it may be a significant factor as far as cold goes.

I settle my oil for many months removing all fats and particles except those invisible to the naked eye and have never been able to get oil that passes a HPT without external drying and neither has several knowledgeable people I know.

I dump the as collected oil in an IBC and leave it for around 6 months then pump the oil off the top into another IBC where it sits for another 3 months on average. In tests I have done, I see no difference between the oil on the top of the first tank nor the oil on the top of the second tank several months later.

I pump the dregs from my tanks out about once a year now in winter and suck from the bottom to get all the creamy and thick rubbish I can. I give this to a friend whom uses it for Bio production. What I have noticed is that once the water is driven off, the oil that was previously thick and fatty will then stay liquid to a temp much cooler than it was before.
Clearly the water attaching itself to the oil has the effect of thickening some of it up and when that water is gone, the oil or a significant portion thereof ( there are some solid fats in what I collect) will remain liquid to much lower temps than before drying.

I believe once the dissolved water content gets down to a certain level, either the time required to get the water out to pass a HPT is exponential and for most peoples purposes, impractical or there are other factors at work such as heat or cold or a mixture thereof that or responsible for allowing oil to pass a HPT rather than just the settling process itself.

None the less, once you get the oil down to this level any other drying will be a lot faster, simpler and efficient than trying to process as collected oil without being pre settled.


Settling will greatly reduce water content as well as all other rubbish and reduce the amount of work you have to do to the oil further along in the refining process. Upflow or just putting the stuff in a tank dosen't matter, just as long as the oil has the time needed to allow the rubbish to drop out.
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I don't give a damn about what might or could happen until a significant group of people can tell me it HAS happened to them.
Until then, it's just more endless gloom and doom Veg folk law.
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Postby John Galt » Sun May 16, 2010 1:14 pm

A commonly held misbelief is that somehow used cooking oil conforms to some international standard and that what works to clean the UVO in one case will work for everyone else.

Logic dictates this is totally fallacious. The difficulty in removing water and other contaminants depends on the type of oil used and what's been cooked in it and how long the oil has been used. Just because a process works for someone else does not mean it will or will not necessarily work for you. It has very little to do with where they live other than the ambient processing temperature available and how that effects the different components and how their contaminant load separates from the clear clean oil you want as motor fuel. It's a common misconception among new users that if they can somehow find the perfect recipe and follow it precisely that somehow they will get the same results. What they fail to understand is that it's almost impossible to have the same UVO in almost every case.

You have to experiment with different processes with your UVO to find what works best in your case. Parroting someone elses process without first understanding the basic principles will always result in frustration and disappointment, often followed by accusations toward the person whose process you tried to copy.
It's all part of the learning process. Some achieve that understanding through research and experimentation, while some others never will.
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Postby coachgeo » Sun May 16, 2010 7:43 pm

Well said John
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Postby David » Mon May 17, 2010 7:40 am

Your Mellowing quite a bit John.
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I don't give a damn about what might or could happen until a significant group of people can tell me it HAS happened to them.
Until then, it's just more endless gloom and doom Veg folk law.
David
 
Posts: 333
Joined: Thu Mar 06, 2008 4:12 am
Location: Sydney Australia

Postby coachgeo » Mon May 17, 2010 10:37 am

David wrote:Your Mellowing quite a bit John.
shhhhhhh.... dont stir him up 8)
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