Adding salt or baking soda to help settle

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

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Postby coachgeo » Tue Sep 09, 2008 10:51 am

Try mixing in some salt/brime to help it settle? Is suppose to reallly help.

Do some search on that topic to get an idea on how much salt etc. to do this. Then try it ad CF what's left good after that settles?
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Postby Burbarian » Tue Sep 09, 2008 12:54 pm

Brine works wonders on dirty oil. Increases the density of water by 35%. Oil typically has a specific gravity of about 0.9 and water, 1.0. With brine being 1.35, you get a 45% differential, and the stuff separates out rapidly. About a week's worth of settling in a day or better with very wet oil that's been churned into chocolate syrup by a mortar mixer. Emulsions don't stick around. According to the salt drying process used by the petroleum industry, it can even take out dissolved water.

I typically mix 2lbs of salt with a gallon of hot water in a 5 gallon bucket. That's more salt than is needed and it will not completely dissolve. Then pour in and blend to an even consistency. The undissolved salt just falls to the bottom with the crud. A less labour and attention intensive process is to trickle the oil through plastic rain gutter that's full of salt and collect off the top at the far end, which is what I'm experimenting with now.

Oil that's been brine washed, then left to settle for a week in a 30 gallon drum tests bone dry from the top down to about a foot from the bottom before you start seeing small bubbles. The apparently clear oil near the bottom that still has water, when collected and filtered then allowed to settle and slowly cool for another week, will settle out some more water. It also precipitates out fine salt motes, finer than table salt but eyeball visible and able to be captured by a 2 micron filter.

Note however that running the entire concoction through a CF without waiting for it to pre-settle first will subject your CF rotor to highly corrosive brine. It does a really bad number on aluminum and steel.
Last edited by Burbarian on Tue Sep 09, 2008 1:08 pm, edited 2 times in total.
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Postby coachgeo » Tue Sep 09, 2008 1:02 pm

Burbarian wrote:...Note however that running the entire concoction through a CF without waiting for it to pre-settle first will subject your CF rotor to highly corrosive brine. It does a really bad number on aluminum and steel.
THANKS Burbian. Premo information!!!

Is there another substance like flour? That would give simular affect as brime but not be damaging to CF?
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Postby Burbarian » Tue Sep 09, 2008 2:40 pm

Magnesium chloride and calcium chloride (ice melt road salt) look to be significantly better than regular table salt (sodium chloride), and is much less corrosive.
1987 GMC Suburban 6.2L V8 IDI
1985 Merc 300TD
1968 CAT D4D 3304 dozer
1971 Waldon 4100 loader
1981 IHI 30F excavator
1995 Changfa 195 w/ ST 10kw genset
Burbarian
 
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Location: Vermont

Thanks for the tip Burbian and Coachgeo!

Postby HoldOnTight » Tue Sep 09, 2008 5:29 pm

I was contemplating adding salt water, but I hated to see what happened to the CF. Now I understand to let it settle out before CFing, and the CF won't be subjected to the salt. Should I add process as I do to dewater with heat to help it settle faster before CFing?
Late 99 Ford F-250, Designed and installed at home, 30 kMi on VO. WVO temp at solenoid valve is 185-195+F, winter-summer.
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Postby HoldOnTight » Tue Sep 09, 2008 5:40 pm

Burbian, Two questions at this point, After adding brine, how long do I let it settle before CFing? And, the amount of brine is 1 gallon for 55 gallons of UVO?
Late 99 Ford F-250, Designed and installed at home, 30 kMi on VO. WVO temp at solenoid valve is 185-195+F, winter-summer.
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Postby HoldOnTight » Tue Sep 09, 2008 7:24 pm

Okay, Okay, Rereading and reading more... 2 lbs salt/gal H20 and wait a week for it to settle out, got it.

Do either of you have experience with adding baking soda or flour to the peanut buttery mix? Seems like baking soda, being a base, might react with some of the FFA into a salt...taking the water with it.

I am sure the salt will help, so that is my safety net. I just added about 1/5th cup of baking soda, since I had that on hand, mixed with boiling hot water and added it to about 15-20 gal. of the murky UVO.

I didn't have rock salt or MgCl or CaCl handy. I do have water softner salt, but it is the yellow bag, which has chemicals in it to clean the rust out of the brine tank of the softener (possibly acidic). I'm not sure where to get the Ice Melt at this time of year... :( Suggestions?
Late 99 Ford F-250, Designed and installed at home, 30 kMi on VO. WVO temp at solenoid valve is 185-195+F, winter-summer.
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Postby HoldOnTight » Tue Sep 09, 2008 7:28 pm

Oh, to clarify, I added 1/5 cup of Baking soda to 1 cup of hot water...not much but I'm hoping it will get the separation started so I can start CFing oil this weekend...like a baby weening to satisfy it's hunger...

Thanks again...
Late 99 Ford F-250, Designed and installed at home, 30 kMi on VO. WVO temp at solenoid valve is 185-195+F, winter-summer.
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Postby Burbarian » Tue Sep 09, 2008 7:58 pm

I tried baking soda once, and you are correct, it reacts with the FFAs and water in the oil, and makes soap. However, the soap acted like an emulsifier and dispersant, slowing down settling and created a bubbling froth on top. The bubbling didn't stop for days, and the froth on top needed to be skimmed off carefully before the oil could be used. As a personal preference, I just use leftover mag chloride saturated hot water. I figure the water will dilute any non-FFA acids (like vinegar) and other impurities in the oil and draw it down to the bottom as it settles.
1987 GMC Suburban 6.2L V8 IDI
1985 Merc 300TD
1968 CAT D4D 3304 dozer
1971 Waldon 4100 loader
1981 IHI 30F excavator
1995 Changfa 195 w/ ST 10kw genset
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Postby coachgeo » Tue Sep 09, 2008 9:20 pm

Burbarian wrote:...I just use leftover mag chloride saturated hot water. ...
left over from job site or another WVO project orrr???
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Postby Burbarian » Tue Sep 09, 2008 10:17 pm

Started with table salt, then tried out the other salts available in 50lb bulk bags. They seem roughly equivalent at breaking emulsions. I've been using some mag chloride to keep the walkways de-iced, as it works better than sodium chloride at low temperatures and is less toxic to the plants. Had some left over from last winter.
1987 GMC Suburban 6.2L V8 IDI
1985 Merc 300TD
1968 CAT D4D 3304 dozer
1971 Waldon 4100 loader
1981 IHI 30F excavator
1995 Changfa 195 w/ ST 10kw genset
Burbarian
 
Posts: 195
Joined: Wed Mar 05, 2008 12:14 pm
Location: Vermont

Postby Burbarian » Thu Sep 11, 2008 10:31 am

As an additional note, salt brine is very handy as you can keep reusing the stuff over and over again. Just pumped out the top 2/3 of a salted batch, tested dry as usual. Top off the insulated drum with pre-filtered hot lard, 5 minutes of churning, then leave that alone for a week. You could have concurrent drums doing parallel batches for greater throughput. Another nice bonus is that the saturated brine that settles out with the sediment is a hostile environment to the majority of microbes that might contaminate the mix. My feedstocks come primarily from dead animals after all. And wet animal bits are a bacterial buffet. Unless thoroughly salted.

All I need to figure out now is how to cheaply filter out the little solid bits floating around in the dried oil. A bit more of it settles out if I leave it alone, but it is a diminishing-returns scenario. And much of it seems to never settle out at all, being about the same specific gravity as the hot lard. Been running it through 50/10/2 filter socks, but was wondering if there was alternatives. Filter replacement and disposal is a messy business.

Oh, I should relocate this side topic and not hijack the thread.
1987 GMC Suburban 6.2L V8 IDI
1985 Merc 300TD
1968 CAT D4D 3304 dozer
1971 Waldon 4100 loader
1981 IHI 30F excavator
1995 Changfa 195 w/ ST 10kw genset
Burbarian
 
Posts: 195
Joined: Wed Mar 05, 2008 12:14 pm
Location: Vermont

Postby HoldOnTight » Fri Sep 12, 2008 8:47 am

RESULTS: I tried 1/4 cup baking soda (from the kitchen shelf) in cup of boiling hot water, mixed until dissolved and added it to a sample of ~20 gal peanut butter colored emulsified oil. The next morning, I found some floating waxy substance. After the second day, more floaties. I skimmed it the third day (even more floaties) and viola, clear oil on top. Not sure how far down it goes, but, I have confidence in this approach...simple. I would guess it speeded up settling 3 times as fast, maybe more. Now I've got to treat a 50+ gal batch after moving to a container I can take out to wash afterwards. That will be this weekend's task. Thanks for the tips!
Late 99 Ford F-250, Designed and installed at home, 30 kMi on VO. WVO temp at solenoid valve is 185-195+F, winter-summer.
HoldOnTight
 
Posts: 137
Joined: Fri Mar 07, 2008 9:40 pm
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