First of two previous messages linked to in this discussion (excerpts).
http://infoarchive.net/sgroup/biofuel/36779/
>Date: Sat, 10 Jul 2004 09:04:27 +0900
>To: biofuel@yahoogroups.com
>From: Keith Addison <[EMAIL PROTECTED]>
>Subject: Re: [biofuel] washing biodiesel in large processor
>
>Hi Todd, Ardis
>
<snip>
>>Some concern has been expressed in the past over the use of air to dry fuel,
>>the concern being fuel oxidation. It's beyond me why those who express such
>>concern (and rightfully so) don't say word one about bubble washing doing
>>the exact same thing.
>
>Indeed. For my part, I didn't say anything about air-drying but I
>did say something about bubble-washing and oxidation:
>
>>Meeting the German or Austrian standard isn't difficult, but the
>>Euro standard might be, especially if we think bubblewashing is a
>>great idea. Might have to drop bubblewashing, go for simple
>>stirring instead (and making the stuff properly in the first
>>place). Might have to use an additive as well. And, might have to
>>drop soy too. Something tells me the ASTM standard isn't about to
>>adopt these Euro oxidation limits any time soon.
>
>Bubble-washing certainly promotes oxidation. I've been sent some lab
>test results on that, or rather a precis of them. Those folks are no
>longer doing bubble-washing or air-drying. They use pumps and
>stirrers to wash.
>
>>Others express concern with pump- or prop-washed fuel not clearing as
>>quickly as mist- or bubble-washed. There's sound reason for this, all things
>>being equal. Pumps and propellers have the ability of better mixing the fuel
>>and water ("atomizing it"), bringing both in more frequent contact with each
>>other. This means greater surface to surface contact between water molecules
>>and all suspended/dissolved impurities. Fifteen minutes with a 1/2 hp motor
>>and 4" - 6" prop in a 200 gallon wash tank or bigger will achieve the same
>>thing or more as an all-day-affair with a mist- or bubble-washer. This
>>allows for hours of washing time to be converted to settling time, in turn
>>hastening the entire wash process.
>
>Faster, results as good or better. We still do bubble-washing, but
>then we do just about everything else too, except mist-washing, I
>really do think that's a blind alley, along with other well-known
>blind alleys. If this were just a production facility rather than
>also for demonstration, testing, investigation, we'd probably drop
>bubble-washing, or mostly anyway. It does have its advantages,
>especially if you're not in a hurry, and oxidation of an oil like
>canola/rapeseed or better (ie lower Iodine Values) isn't a problem
>as long as you use it quickly.
>
>We do a lot of demos all over Japan, and we hold these very popular
>monthly biodiesel seminars here, and when we demonstrate
>bubble-washing (easy to transport and easy to scale down to
>desktop-size if need be) it's a handily visual example of how
>washing works, but it's also a good way of introducing the subject
>of oxidation - after all, that's what the fish-tank aerator we use
>does for the fish, as everyone knows. It's also a good added
>reinforcement for what we lay the most stress on, other than that,
>yes, you too can do this: do it right in the first place, make
>complete fuel. We don't say bubble-washing's a no-no, we give the
>pros and cons of it. We do emphasise the bottle-shake wash test.
>
>I don't agree with what Mark said about the acid-base process
>creating a sulfate salt in the wash that might be masking washing
>problems.
>
>>yes, it won't emulsify as much, but it should be
>>investigated just what of the three factors (soap, mono and
>>diglycerides, and salt inhibition of emulsification) are at play here.
>>IT's probably different for each batch.
>
>If for instance you cut the 2nd stage short with an acid-base
>reaction and it doesn't go far enough to completion it emulsifies
>just as readily with the bottle-shake wash-test as incomplete fuel
>made by any other process, as we've found when we've investigated
>how far we could push the Foolproof method in various directions.
>Same as any other process, as we could see from similar tests with
>the other processes, using various types of oil with both. I don't
>think the salt factor is significant. Sulfate salts or not, most of
>the catalyst ends up in the glycerine by-product anyway. When we
>separate acid-base glycerine by-product into its components, the
>bottom layer is the catalyst salts. There's only 0.1% of sulphuric
>v/v oil to start with, and less catalyst to start with too, unless
>you're doing virgin oil, which is highly unlikely to have completion
>problems using the acid-base method. Not a lot of salt to mask mono-
>and di-glycs with. It washes well because they ain't there.
>
>I'm puzzled by what Mark said in her post:
>
>>either mistwash or bubblewash works fine for big batches, but the same
>>rules apply as for small batches- more water is needed for misting and
>>less emulsification happens, much less water is needed for
>>bubblewashing but more chance of emulsification can take place.
>>
>>I actually use both now- mist for a few gallons (for a small 42 gallon
>>batch I mist for 4 gallons) and then I bubblewash with good use of
>>water recycling during bubblewashing. In my 350 gallon wash tank, my
>>small aquarium air pump gives fine results, but not all of the air
>>pumps might be able to handle such large batches. it looks like a tiny
>>amount of bubbles are rising but it works really well- less
>>emulsification than the same air pump agitating up a smaller batch.
>
>Emulsification with an aquarium air-pump?
>
>Mark says this too: "The disadvantage [of bubblewashing]: if you
>have made poor quality biodiesel, or are washing a very small batch,
>bubblewashing can agitate the water and the biodiesel too
>vigorously, causing emulsification of the two liquids.
>Emulsification is the quintessential "wash problem" -- but it is
>also a form of quality testing and feedback on your process. Once
>you know what causes it, it is easily avoided."
>
>Also: "The bad news is that poor quality biodiesel can emulsify just
>from the agitation of bubblewashing. The good news is that it's easy
>to make good biodiesel. Even with problematic biodiesel, you can
>predict emulsification in a simple "wash test", take steps to avoid
>it, and easily fix it if it does happen. The even better news is
>that bubblewashing emulsification isn't a problem for average
>well-made homebrew -- you should be able to use even nasty
>restaurant oil and still easily make fuel that won't emulsify under
>bubblewash conditions."
>
>And: "Some people use a super-gentle "mist washing" method to take
>vigorous agitation out of the picture. To me it seems that this
>masks the real problem -- which isn't agitation, it's poor fuel
>quality. I'd rather make sure I've produced fuel that contains less
>soap and less emulsifying monoglycerides and diglycerides (MG and
>DG), instead of decreasing the agitation to "ease washing". The
>agitation produced by standard bubblewashing isn't very strong, an
>average homebrew fuel should be able to handle it without
>emulsifying."
>
>?
>
>Puzzled.
>
>Not too sure about the "... or are washing a very small batch" bit
>in the first paragraph, it shouldn't mind bubbles. It shouldn't mind
>a blender too much either, bit drastic though. But I'm a friend of
>frogs! Hey Todd, why don't you horrify everyone by giving us that
>"Frog in a Blender" url? LOL! Urk...
>
>That's all from Mark's "Bubblewashing 101" article, by the way:
>http://journeytoforever.org/biodiesel_bubblewash2.html
>
>Best wishes
>
>Keith
>
>
>>Anyway, when all is said and done and no matter what wash method you choose,
>>you'll best serve your own interests if you make sure that your reaction is
>>complete before attempting any type of wash. All bubble- and mist-washing
>>tend to do is offer brewers the opportunity to wash an incompletely reacted
>>batch with one eye closed and sometimes the other eye squinted.
>>
>>Todd Swearingen
>>
>>----- Original Message -----
>>From: "ardis streeter" <[EMAIL PROTECTED]>
>>To: <biofuel@yahoogroups.com>
>>Cc: <[EMAIL PROTECTED]>
>>Sent: Wednesday, July 07, 2004 7:29 PM
>>Subject: [biofuel] washing biodiesel in large processor
>>
>>
>> > Hi,all ' I was wondering if anyone could tell me
>> > which way might be best for washing large batches of
>> > biodiesel??My processor is capable of processing up to
>> > 200 gallons at a time.I am still building the
>> > processor so I was looking for some imfo.from
>> > experenced biodiesel producers.So far I have the
>> > stainless pick up tank done,the methanol,lye mix tank
>> > done,the processing tank with heat exchangers and
>> > mixer done.Currently I am building the wash tank and
>> > was wondering if bubble washing or top mist washing
>> > would be better for a tank that is 46 inches in dia.
>> > and aprox. 90 inches high.The tank will hold aprox.
>> > 480 gallons.Also was wondering if the tank needs an
>> > agitoror or if the wash tank should be set up with a
>> > pump to stir the fuel,water wash?? Also would like to
>> > know if the wash water should be pre-heated because
>> > well water is around 55 degrees,would this cause a
>> > problem with proper washing.Thanks for any help||
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