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Biodiesel induced corrosion
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Stuff it: I found corroded fuel tanks on all my vehicles! Fuel after wash is around 7.5 but samples taken from tanks read 4.1! This is acid and bad news. Why is the freakin' stuff turning acid when sitting in tanks? Brass strainers go green too. I use hydrogenated vegetable gunk as stock and I wash my batches. I get plenty of white wax cristals that fall to the bottom and separate naturally. Is there any left water in the fuel from the wash? Anybody had this trouble before or know the answer to acidity?


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Location: Outback Cairns, Nth Queensland | Registered: August 06, 2002Reply With QuoteReport This Post
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cant say about acidity but on the water in fuel after wash ... YES

ASTM allows .05% water and sediment, I found that I could not get below .15% water without also heating to 125 while spray drying. I weigh out a 400gram sample and heat it, if I lose more than .2 grams weight I know it is still above the upper limit. I shoot for .1 or less weight lose.

Trc


If you can't dazzel them with brilliance, then baffel them with bullchit.
 
Location: north of houston, south of dallas, east of austin | Registered: August 31, 2006Reply With QuoteReport This Post
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All oils and the biodiesel you make out of them have a specific oxidation stability. Usually oils with a higher vitamin E content are more stable while others oxidize while you're watching.

You can determine the oxidation stability and add anti-oxidants accordingly.
 
Location: Netherlands | Registered: December 22, 2006Reply With QuoteReport This Post
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Thanks Dimitri You are touching on an very important subject here. Can you develop that a bit more?


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Location: Outback Cairns, Nth Queensland | Registered: August 06, 2002Reply With QuoteReport This Post
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What metals are used in your processing equipment? What metals are used in your storage tanks? How long does the biodiesel sit in storage? Are there any high temperatures introduced during storage or processing?
 
Registered: August 14, 2006Reply With QuoteReport This Post
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BTW, frog, brass is not biodiesel-compatible, and the greening you're seeing is oxidizing. I doubt that is super-responsible for the acidifying, but it could be part of the problem. Certainly if you have a bunch of other non-compatible metals like copper or brass around, that could do it.

Typically, oxidative stability is a much longer term issue than what you seem to be describing, unless you are using very old fuel, fuel stored very poorly, or fuel made from drying oils like hemp or linseed.


Kumar Plocher
Yokayo Biofuels
Yokayo Biofuels Facebook page
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Location: Ukiah, CA USA | Registered: September 19, 2001Reply With QuoteReport This Post



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@frogmobile

Well aside from the natural oxidation stability which you can enhance with synthetic vitamin E or other anti-oxidants, there may also be some electrolysis taking place with certain metals.

Just keep the biodiesel in a closed glass jar and compare oxidation with the biodiesel in the tanks. If it is the same, it's natural oxidation, if the biodiesel in the glass jar oxidizes more slowly, the oxidation in the tanks is catalyzed by some metal.
 
Location: Netherlands | Registered: December 22, 2006Reply With QuoteReport This Post
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Frogmobile

It occurred to me to ask you -

1) describe exactly the corrosion in your tanks please, and
2) how are you measuring the pH of your biodiesel?

Paul
 
Location: New Zealand | Registered: August 15, 2006Reply With QuoteReport This Post
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Sorry fellers, I had a lot of trouble with my phone line and my Internet connection, seems to work today for the first time... I will answer all your questions as soon as poss. thanks for your concern.


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Location: Outback Cairns, Nth Queensland | Registered: August 06, 2002Reply With QuoteReport This Post
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Well, I use steel 44gal drum with conical bottom for my reactor, I heat to 100°C then process at 60°C. There is no copper or cupro metals in the processing line. I store in 1000 l plastic cubi-tainer elevated (bowser) Now if there is water all this corrosion and electrolysis is the result of that presence of H2O in steel tanks. The sample in the jarr are unaffected, so why on earth is there rust in my tank? Rust, sludge and acidity. I mesure the Ph by washing the sample fuel with water and then mesure the Ph on that water with phenol and other colour reactives. When you watch that water very clean and separating instantly, you already know that you're acid. (My elctronic Ph metre conked out days after the waranty expired!) One jarr with bits of copper showed green discolouration in the fuel, indicating a reaction with the fuel. The corrosion occured in tanks where fuel tend to sit for a while, ex the bulldozer. How will I get a fuel that is totally INERT? Is hot lime a possible dehydrant for BD?


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Location: Outback Cairns, Nth Queensland | Registered: August 06, 2002Reply With QuoteReport This Post
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Frog

How long have you been having this problem? I notice you are just out of the rainy season in Cairns. Could it be that if daytime humidity and temperature are high, atmospheric water is condensing on the walls inside the tanks if night-time temperatures are cool? Do you keep your tanks topped up to minimize air circulation?

To the best of my knowledge, a little acetone in the fuel will absorb free water and allow it to be drawn out as part of the engine's normal fuel intake.

Might be best to ask Kumar about acetone and bio, however.

I presume that after washing your bio you are taking steps to dry it? Also, you might find that 100*C isn't enough to boil off water in your WVO feedstock. That temp might be okay for extended settling, but not boiling.

Paul
 
Location: New Zealand | Registered: August 15, 2006Reply With QuoteReport This Post
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I have residual wash water in the fuel, there is no question about that. The question now is" how to get rid of that water without boiling the whole bloomin' 200 litres batch at 100°". I am trying calcium sulfate (plater of Paris, to be patriotic) at the moment, will keep you posted.


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Location: Outback Cairns, Nth Queensland | Registered: August 06, 2002Reply With QuoteReport This Post



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Paulus, I don't know much about acetone used that way, but I am aware of a number of additives that act similarly, and my advice will always be to dry the fuel (take care of the cause, rather than the symptoms). If needed, clean out the vehicle fuel system and replace problem components (like the tank).

Frogmobile- there are a lot of ways to dry fuel, but it DEFINITELY has to be dry.


Kumar Plocher
Yokayo Biofuels
Yokayo Biofuels Facebook page
.........../ \..............
fueling / R \ evolution since 2001
'''''''''''''/____\'''''''''''''''''''

Sustainable Biodiesel...
 
Location: Ukiah, CA USA | Registered: September 19, 2001Reply With QuoteReport This Post
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Thanks Kumar. You know, a guy came around late last week to talk bio and he gave me a paper on adding a very small percentage of acetone to both diesel and gas engines to improve efficiency and raise mpg. Something to do with extending the burn time in the power stroke. Have you heard of this?

Paul
 
Location: New Zealand | Registered: August 15, 2006Reply With QuoteReport This Post
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Paulus;

I don't know about adding acetone to BioD, but I add about 2 oz to 10 gallons of my WVO that I put through my Listers. It tends to make them burn cleaner with less need to de-carbon (longer intervals). I have heard of people using it as an additive in DinoD and the reports I have received indicate that it works well in that situation too. However, I can't remember hearing anything about adding it to BioD - but there again, it could well work given the about 2 extremes.


JohnF
 
Location: Bourget, Canada | Registered: December 28, 2004Reply With QuoteReport This Post
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Well... I have been busy with other things and did not pay enough attention to my problem of corrosion in the tanks and the devil had another bite at me. This time I tried the Alex Kac's method of cracking the FFA with sulfuric Acid prior to basic transerterification with NaOH. It tested 100% conversion but it's too early to tell if this will solve the corrosion problem. I also dryed my last batch of fuel with salt. So wait and see. I could be forgiven to have trusted these carbon steel samples in biodiesel since 2004 and unaffected but it was vegetable oil BD, now I am using SOLID HYDROGENATED VEGE OIL badly cooked... Conversion is not as complete and water separation after washing not as good. I put new samples to the test with my new BD.


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Location: Outback Cairns, Nth Queensland | Registered: August 06, 2002Reply With QuoteReport This Post
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frogo I believe your problems are it being hydrogenated veg oil, it is tricky to process.I am also having trouble with this hydrogenated stuff. 4 batches ph of 4.1, 7.0, 9.4, 5.2, the 4.1 was polymerised smelled of old paint. I have noticed the oil is semi solid,needs heat to make it run and bubbles and froths as though it has water in it. Takes a very long time to seperate the phases after process has finished,18-24 hrs. In the bottom of my storage drums is a brown sludge from this stuff I have never had before. I dry wash using heat and air and this stuff does not like it I also do acid base/base it usually titrates at 14 it passes 3/27 and get good conversion 95% but it fails 50/50 test i am going the way of vacuum meth removal just need to work out neutralizing the base to halt reaction reversal good luck and hope you can conquer it regards andy
 
Location: south australia | Registered: November 17, 2008Reply With QuoteReport This Post
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I made some progress on the process of cracking that gunk (acid esterification, double base reaction) and on the drying process : I use salt and it seem to work well! Now the problem is oxidation of the BD after one month. It 's been talked about on the thread: "Does exist a test..." by Green Guy. Thanks Gilfish


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Location: Outback Cairns, Nth Queensland | Registered: August 06, 2002Reply With QuoteReport This Post



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IMO only Stainless steel (316 304) equipment should be used. You could also use Polyethylene for cold pipe pipework.

My VW Passat is off the road at moment with suspected corrosion to the Fuel pump (VP37) This due for inspection by a pump specialist and photos will be taken of the inerds. It has a plastic HDPE fuel tank.

I recently put my van (Vauxhall (Opal) Combo 1.7D) back on the road. When I mothballed it back in 2008 I pumped all the biodiesel out. But there must have been a small amount left. I have since had to change the fuel filter (Heated Purflux) 7 times in the last month! It has a steel fuel tank. A brown sticky gunk is slowly being cleared out by fresh fuel (Bio / veg / dino blend). The fuel is dark red colour.

I believe that metals copper, brass, zinc (zinc galvanising) possibly also cadmium and iron, mild steel all contribute to biodiesel instability or oxidation. It could be that the metals are a catalyst that tips the balance leading to uncontrollable oxidation and elevated acid levels (Acid No)

We use a Tokhiem fuel dispenser that has a cast iron pump. It had copper pipe work as well. The Copper has been replaces with stainless steel.
The problems we faced where green soapy deposits breaking off inside the pipework and blocking up the nozzle screen. Cleaning of the screen had to be down every fill up!

We don't make biodiesel but buy it in. There is no antioxidant added so we now add Baynox plus to all the fuel that comes in. The feed stock is a blend of recovered(used) Rapeseed / soy oils. 15% of the feedstock contains heavy fractions of palm and hydrogenated oils added during summer months.

Uncle Slabs


Home of Good Biodiesel http://www.cambridgebiodiesel.org

2000 Vauxhall (GM) 1.7 NA IDI Combo, Bosch VE, coolant heated fuel heater. In-tank strainer drilled out and inline filter fitted. Using FAME and veg oil blends.
 
Location: Cambridge, United Kingdom | Registered: October 21, 2003Reply With QuoteReport This Post
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Here ze are talking! Thanks for beeing frank about your demises. I know too well that brown gunk that is left at the bottom of drums after many month. Definitely adulterated biodiesel! Gilfish and Reece123 put me on the right track about ester beeing degraded over time. Funny, it was n't talked about very much on the forum. I found that brass is badly attacked as well. I like your idea that metals act as catalyst in the process of oxidation. If the result is acid (carboxylic acid mentionned by Reece123) no wonder the steel tanks get chewed up! Add to this a bad conversion, some residual water and you have a time bomb! I begin to see a bit more clearly now. I will be improving my conversion, drying and will get the additive Baynox+ if only I can find it in Australia! Confused Thanks for your reply- Cheers


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Location: Outback Cairns, Nth Queensland | Registered: August 06, 2002Reply With QuoteReport This Post
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