Vacuum method for dewatering

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

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Vacuum method for dewatering

Postby toadshade » Sat Feb 10, 2018 9:38 am

First post. Hi everyone. I am starting my research on drying methods for WVO. I have been researching vacuum methods of dewatering since it seems to take care of all of the combined water issues. So far, I have not found a lot of information because it seems like it is not a common practice. One reason is that it is an expensive option. I am a pressure vessel welder and I happen to build vacuum ovens, so I was going to build a 50-100 gallon vessel to try and vacuum dry the oil. I wanted to know if this is a system that could work all on its own? My idea was to circulate the oil through the vacuum vessel and through a filter at the same time, and that's it. Or, if there is any issue with the filter under a vacuum, then filter first, then just circulate the oil while vacuuming. Ideally, I would like to add Sun Wizards' capacitive % saturated meter[/u] (Sorry, I am no good at using forum tools) in line and then just circulate under vacuum until "cooked" or in other words, when the meter tells me the oil is dry.

So if the principal idea would work, then I have a couple questions:

What temperature would I want the oil to be in the vacuum chamber? Oil smoke points are about 450 degrees +/- depending on the type of oil. I have not been able to find any information on how that temperature changes for oil under vacuum. Or would a safe bet be to just worry about the point water will vaporize at whatever mbar I am pulling with my pump?
Would it be a good idea to agitate or even spray the oil in the chamber for higher surface area contact versus just circulating, or would circulating be enough?

Hopefully I didn't get too complicated on my first post. And I also hope I am not trying to reinvent the wheel here. I would really like this system to work. Any help would be appreciated.
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Re: Vacuum method for dewatering

Postby SunWizard » Mon Feb 12, 2018 9:14 am

No vacuum needed, I heat to 160F and then spray is all thats needed with the dry climate here. See the Dieselcraft CF thread here for more info. The CF makes it so I dont need to buy a new filter with each 55 gallon batch I run, I just scrape and wipe the gunk out of the bowl. Heat and spray is also what many biodiesel makers use to dewater.
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