drying with evaporation

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

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drying with evaporation

Postby david p » Mon Jan 26, 2009 10:43 pm

i've read in a couple of places that people making biodiesel often use evaporation to dry it. a couple of the common methods i've seen are recirculating the bio with a pump and using a nozzel to spray the bio, thus exposing it to air. the other is to bubble air through the bio using an aquarium bubbler. in both methods mild heating seems to be common.

i was wondering if these methods work for drying wvo? do they work the same? or is some drawback to these methods if applied to wvo?

thanks.
'02 VW Jetta with Elsbett 1 tank system (plan to run on WVO)
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Postby John Galt » Mon Jan 26, 2009 10:52 pm

Biodiesel is clean when it's dried with evaporation. WVO isn't. Removing water from WVO by evaporation concentrates the contaminants that were dissolved in the water. Settling by gravity or centrifuge is better. Final dehydration of clean VO with something like Quik 'n' Dri™ is useful.
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Postby 240Volvo » Tue Jan 27, 2009 9:23 am

Bubbling in WVO can create an emulsion with the oil and water that is difficult to break.
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questions

Postby david p » Tue Jan 27, 2009 3:48 pm

Thanks for replying. I've got a couple questions based on your responses. I don't mean to give the impression I don't believe your answers, I'm just trying to make sure I understand what you're saying.

Wouldn't Quick 'n' Dri concentrate the contaminants as well? I'm asking because I'm debating between using Quick 'n' Dri vs. evaporation. Also, if I did the evaporation after filtering to 1 micron, would you still worry about the problem of concentrating contaminants?

Can you point me in the direction of some information about the problems of creating an emulsion by bubbling? I've searched and can't find any, just general info. about what an emulsion is or why it's good to avoid.
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Postby John Galt » Tue Jan 27, 2009 10:26 pm

I use Quik 'n' Dri only for final polishing to ensure all of the water has been removed by settling.

Filtering does nothing to remove contaminants dissolved in water.
Last edited by John Galt on Wed Jan 28, 2009 12:46 pm, edited 1 time in total.
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Postby coachgeo » Tue Jan 27, 2009 10:50 pm

John Galt wrote:...Filtering does nothing to remove contaminants dissolved in water.
Could it be that your not realizing that John is including chemical contaminants that do not "filter out" cause they are "disolved" in the water" These create water soluble acids, bases, etc

Its more than just things like food particles, flakes of poly and the likes. These are easy to remove but if you evaporate the water after that you leave in the components that make up some acids etc.
Last edited by coachgeo on Tue Jan 27, 2009 10:57 pm, edited 1 time in total.
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Re: questions

Postby coachgeo » Tue Jan 27, 2009 10:54 pm

david p wrote:...Can you point me in the direction of some information about the problems of creating an emulsion by bubbling? I've searched and can't find any, just general info. about what an emulsion is or why it's good to avoid.
John might know of one..... though Im not sure if anyone really could point it out off the top of their head.

It is a tuff one. It's not written in nice sweet concise threads. It's spread out over thousands of threads and post that goes back years and years.

If you want to find it, will take tons of reading. Searching for information like this is an art. Get real friendly with your search engine. Takes alot of practice.
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Postby John Galt » Wed Jan 28, 2009 12:13 am

I have no experience with emulsions. However it seems to be a common problem with the people at biodiesel infopop http://biodiesel.infopop.cc/eve a search there should turn up all the emulsion information you want.
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Postby 240Volvo » Wed Jan 28, 2009 8:42 am

As I recall, it is the agitation of the fluid when bubbling that encourages emulsification in oil that has water present. Kind of like making a salad dressing in slow motion. You will have to search infopop on this. I have avoided mist washing and bubbling for this reason. Cold settling before filtering and a final heat and settle of filtered oil works for me.
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