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Demeth before water wash
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I am just curious if demething my bio will make washing easier. I have an appleseed setup and usually have very little or no fallout in the 3/27 test and I have a bad soap problem everytime when it comes to washing. I do have soft water and seems from what I've read, that is usually one of the reasons for problems with washing. I have done the "quick fix" with using 5 gallons of salt water and that seems somewhat fix the problem but seems from what I've read on here is that after you demeth a batch the emulsion problems disappear and it makes everything settle to the bottom and makes cleaning and washing far easier. I don't really want to go the route of dry washing, I'd rather do water wash since I am already setup to do that. Just wondering if its worth the time and money to make a demeth setup or not. Should I just plan to use a somewhat salty mix for the first few washes (which is what my next plan was). I also read a few things on here about letting a batch sit and settle for weeks after demeth and that it was almost perfectly clean.
Any help would be greatly appreciated.
 
Location: Olympic Peninsula, WA USA | Registered: October 07, 2015Reply With QuoteReport This Post
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Make washing easier is the understatement of the day.

I do exactly that. De-meth, leave it to stand 2 days, soap is then less than 200ppm. I then decide if I need to leave it another week to just settle, then centrifuge or if I should water wash.

With the soap that low you can wash how you like, as aggressively as you like and you WILL NOT create an emulsion.

The 'norm' with water washing is not to de-meth as the water removes the methanol, true but this is where the trouble starts, methanol present = soap present.

Settling is as good as water washing, but you have to wait until all the soap/glycerine has settled. Keep doing a soap test, when it's low it's good to use.
 
Location: YORK UK | Registered: April 27, 2014Reply With QuoteReport This Post
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Make sure that you are reaching complete conversion, the 3/27 is less sensitive to partial conversion ie presence of di and mono glycerides. Have you come here from the journey to forever website?
 
Location: New Zealand | Registered: August 15, 2006Reply With QuoteReport This Post
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I came here just from doing searches online about making bio. This site has a wealth of knowledge about bio better than anywhere else.
I have been using cleaned up WVO for the last 4 years in my 85 300d and my OM617 powered 4runner, which was nice from a financial aspect (40,000 miles on free 100% WVO) but after dealing with the problems of having inconsistent viscosity depending on the temp of the fuel or temp of the engine, I just decided to start making bio since I bought a 97 powerstroke. Sounds like the efi on the later 7.3s are a lot more temperamental than the old Benz motors on WVO so I figured now is the time to start learning how to make it. It's sooooo nice to hope in your rig in the morning and have it start effortlessly and idle perfect. That never happened with WVO. After running bio in the Ford and 4runner for the last two months, I am sold. Worth the time and money IMO.
 
Location: Olympic Peninsula, WA USA | Registered: October 07, 2015Reply With QuoteReport This Post
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Dgs, that's nice to hear! That is my plan then. I don't mind letting time and gravity take care of helping me clean my bio. I've spent way too much time in the last month walking back to my wash tank to warm it up and then come back later to wash it just to come back later again and repeat that process over again. Frustrating! Nice to know!
 
Location: Olympic Peninsula, WA USA | Registered: October 07, 2015Reply With QuoteReport This Post
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I forgot to mention that I do have a centrifuge that I had built when I was first learning about cleaning WVO. I've since stop using it but because the cold upflow method using a bed sheet is so much easier with far less time ( and electricity) involved. I just have to dig it out and start using it again for the final cleaning of the bio.
 
Location: Olympic Peninsula, WA USA | Registered: October 07, 2015Reply With QuoteReport This Post



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Hi ouchfoss,
Welcome to the forum!

You are correct, soft water does exacerbate the tendency for an emulsion when water washing

It has been at least 4 years since I last water washed.
I just leave the biodiesel sit and de-meth and the soap and glycerine falls out over time.

Since changing to this method of "washing" I find that my "sacrificial" inline filters last MUCH longer.






 
Location: ลึก ประเทศอินเดีย | Registered: March 03, 2001Reply With QuoteReport This Post
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Very good to hear! Makes me have a little more confidence in going the demeth route.
 
Location: Olympic Peninsula, WA USA | Registered: October 07, 2015Reply With QuoteReport This Post
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You could check out whole batch demeth, and vacuum demeth.
 
Location: New Zealand | Registered: August 15, 2006Reply With QuoteReport This Post
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II've read a little bit about that and was unsure if I could do it with my Appleseed setup or not. Something about reversing the reaction didn't sound too appealing to be messing around with. I figured I'd just use my 55 gallon drum dryer with a pipe going into and out of the top with forced air. Is there different ways of doing the whole batch demeth? I was almost thinking of turning my thermostat on my hot water heater after two hours of mixing and see how much of the methanol I could boil off thru my vent pipe. Sounds simple enough.
 
Location: Olympic Peninsula, WA USA | Registered: October 07, 2015Reply With QuoteReport This Post
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Something you might consider in deciding how to design your process is, water , except distilled water has mineral impurities dissolved in it to some extent. Those minerals often contain calcium and magnesium salts of some kind. Without looking it up in a reference book, there's a chemical reaction maybe called a double displacement reaction. The way it works is sodium or potassium soap switches the sodium or potassium for calcium or magnesium to make calcium soap from sodium or potassium soap. That's the material in ring around the bath tub. It's like a soap but the calcium is bonded to two fatty acid molecules rather than sodium or potassium bonded to one fatty acid molecule. Calcium soap doesn't dissolve in water much. I'm not sure what calcium soap dissolves in but you might be aware that water washing introduces impurities into your crude biodiesel product that might cause a problem. Washing with salt water to break emulsions puts a little salt into the biodiesel that needs to be completely removed before burning the biodiesel in an engine, salt in the combustion chamber would probably be bad.
 
Location: Texas | Registered: April 27, 2011Reply With QuoteReport This Post
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And yet hard water makes washing easier.
 
Location: New Zealand | Registered: August 15, 2006Reply With QuoteReport This Post



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The water that I use is just my tap water and last year we tested it and it was essentially super clean with the only detectable impurity being trace amounts of copper which is understandable considering the plumbing in my house.
I always clean wash several times after a salt wash just to be sure there is none left in the bio.
 
Location: Olympic Peninsula, WA USA | Registered: October 07, 2015Reply With QuoteReport This Post
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DGs, are you using NaOH or KOH for your bio? I'm just curious about the settling time for the soaps because from what I've read, NaOH soaps settle far faster than KOH, which is what I'm using. I demethed 40 gallons 2 days ago and figured I'd check soap content today to see how fast its settling. I did the Dr pepper test on some bio from the top and bottom of the tank and they were both super cloudy. Just trying to get an idea on settling time. I dont mind waiting a while to let gravity do all the work for me ( to a certain extent) but just wondering if its a week or month or months long wait. My settling tank is not heated and our temps around here are in the 50s to 60s.
How well does a centrifuge work for cleaning the soap out of the bio once its demethed? I did a search on here and found different conclusions about how well or how fast it actually works. I'm probably going to dig mine out tomorrow and see about plumbing it into my setup.
 
Location: Olympic Peninsula, WA USA | Registered: October 07, 2015Reply With QuoteReport This Post
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Whoops. Thought the Dr pepper test was the soap test. What I meant was I just did a 50/50 water bio test to look for soap. Very soapy.
 
Location: Olympic Peninsula, WA USA | Registered: October 07, 2015Reply With QuoteReport This Post
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Hi ouchfoss,

quote:
Originally posted by ouchfoss:
What I meant was I just did a 50/50 water bio test to look for soap.
That test is commonly referred to as "The Shake-em up Test" Wink






 
Location: ลึก ประเทศอินเดีย | Registered: March 03, 2001Reply With QuoteReport This Post
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quote:
Originally posted by Tilly:
Hi ouchfoss,

quote:
Originally posted by ouchfoss:
What I meant was I just did a 50/50 water bio test to look for soap.
That test is commonly referred to as "The Shake-em up Test" Wink

I guess I misread things! Thanks. Smile
 
Location: Olympic Peninsula, WA USA | Registered: October 07, 2015Reply With QuoteReport This Post
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Hi ouchfoss,
You are correct regarding the different settling times between KOH and NaOH. I use KOH and when I just settle it is for a minimum of 9 to 10 days.

Ideally you need a soap test kit to check the soap as the batch needs to settle longer if the soap is over the astm spec.

Centrifuging bio does work well, unlike centrifuging oil you do not have to get the bio hot, ambient temperature will do. It is important that whatever fuge you use is turning at the design rpm otherwise you will use efficiency.

I have a 50 size fuge and power it with a piusi viscomat. I run the fuge at 100psi, adjusting the pressure with a by-pass valve.
From testing I have done the centrifuge removes glycerol and soap by a factor of @ 50%, so it's not 100% efficient on a single pass, but for instance if the soap level was 100ppm then centrifuging would reduce it to about the 50ppm level.
 
Location: YORK UK | Registered: April 27, 2014Reply With QuoteReport This Post



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Ouchfoss; The shake-em up test is a qualitative test, not a quantitative test. The quantitative soap test can be found on Utah Biodiesel Supply soap test for biodiesel on the internet. The quantitative test uses bromophenol blue pH indicator solution. Using a magnetic stirrer to do the test works. On June 14, 2014 I made methyl biodiesel from lard, pig fat. After I demethed the crude biodiesel in a small vacuum still, I tested the crude biodiesel product for soap content, It was 2372 ppm (parts per million). I treated the methyl biodiesel with magnesium silicate then tested for soap content again, the treated biodiesel had 224 ppm potassium soap. I filtered out the magnesium silicate with a 1 micron filter paper. My records indicate a precipitate formed, some of it fell out at a room temperature of 27 degrees centigrade. Maybe the higher melting fatty acid methyl esters solidified, I'm not sure what it was. Six days later I filtered the methyl biodiesel from lard again then test for soap content again, it was 128 ppm (parts per million) of potassium soap. The shake 'em up test is qualitative. The test using bromophenol blue pH indicator will give you a hard number to help you decide if your fuel is pure enough to suit your standards.
 
Location: Texas | Registered: April 27, 2011Reply With QuoteReport This Post
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quote:
Originally posted by ouchfoss:
Whoops. Thought the Dr pepper test was the soap test. What I meant was I just did a 50/50 water bio test to look for soap. Very soapy.


Lots of people get confused with cutsie names for tests that tell you nothing. That's why it's always best to describe the test you're using and avoid the confusing names some still use.

What you describe is a good test for residual soap and glycerol. Keep washing until the water in the soap test is clear enough to read through.



 
Location: coldest N.America | Registered: May 03, 2005Reply With QuoteReport This Post
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