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Water Wash too time consuming
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I have been home brewing for a couple years with very good success. I have processed the same way the entire time and use a water mist for about 24 hours (or until the water runs clear) and then 2-3 bubble washes of 30% water by volume. The 3rd bubble wash would finish with the water crystal clear.

Over the last few months I have to bubble wash 8-10 times to get the water to be clear. The oil is from the same source and I have not done anything different.

Any suggestions or ideas on how to speed this up since I can't seem to get it clear up quicker?

Thanks
 
Location: Mid Michigan | Registered: September 29, 2005Reply With QuoteReport This Post
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Most washing problems are caused by glycerides.

Glycerides can come from an incomplete reaction or transfer of glycerin into your wash cycle.

High water content in the raw oil can cause poor reactions resulting in more glycerides in the bio.

Most of my batches wash within 12hrs.


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Registered: March 09, 2006Reply With QuoteReport This Post
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I don't think it is very responsible to suggest that people stand over a drum of freshly reacted biodiesel and run a garden hose to wash . There is still alot of methanol in the fuel and running the pump to recirculate will cause alot of methanol fumes . This could very easily lead to methanol poisoning .
 
Location: Crosby Tx. | Registered: June 14, 2005Reply With QuoteReport This Post
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quote:
Originally posted by steved:
The point I am making is that because of the impeller design you can use the PitBull pump to do the washing for you. You can do it in less than 2 hours and get clear water in the shakeup test. This will not work with the open impeller pumps I have tested, they will cause an emulsion. The PitBull has not made an emulsion yet. Smile

The pump is only on a few mins. Most of the 2 hours is letting the water settle.


With the shear forces of a 2000+ RPM impeller, what difference would impeller design make?


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Registered: March 09, 2006Reply With QuoteReport This Post
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Well I'm not sure.
My thinking is that its something not related to the impeller.
Shear forces at those speeds don't seem like they would make a difference.

Also, when you understand what causes an emulsion, its all a mute point anyhow.


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Registered: March 09, 2006Reply With QuoteReport This Post
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Steved,

Are you pre-washing with the 5% water?

After you drain off your glycerin, are you aerating to flash off the excess methanol or are you just firing up the Pitbull and spraying water into the outlet stream?

Please post a step by step so I can try to duplicate it. I was thinking the same as Murphy wondering how it doesn't make an emulsion. The Pitbull is still creating turbulence.

Thanks for the info.
 
Location: Mid Michigan | Registered: September 29, 2005Reply With QuoteReport This Post



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I do a variant of agressive washing using an industrial full cone spray head hooked up to a ShurFlo pump (see webpage in sig).
Using hot water to wash I can do it all in one afternoon and be ready to dry the next AM after settling overnight.
The key to agressive washing is like Murphy said; no glycerides due to underreacted oil and no glycerides due to glycerine layer contamination. It's a water and oil thing;they will always seperate unless you give them a reason not to.
Another variant is using a paint stirrer and drill. It is the first wash you have to be mindful of methanol from,so cover the first wash and you will be fine.



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Location: :-) Great White North eh ? | Registered: December 10, 2004Reply With QuoteReport This Post
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steved,
I think I see your confusion now.

The term "emulsion" can mean a few things.

In biodiesel, we only care about "stable emulsions".. IE: those that stay that way for a long time after they are made.

I can make an emulsion out of any oil and water.. That's simple.
The question is how long does it take to separate after its been made.

Here in is the problem that you seem to be assigning one term to a "time" variable.

Now that I understand your confusion, I can take an engineered guess at why you see the difference between the two pumps.

The pitbull pump is a high pressure, low volume type.

The HF pump is also a high pressure, low volume type but a with a bit less pressure I beleve, and a bit more volume.
I'd have to see the two impellers side by side and know the motor rpms on both units to accuratly predict it. But, my guess is you dont get any emulsion at all with the pitbull because the oil and water are separating faster than the pump can mix them.

2nd, what you are getting is a temporary emulsion.. That's not a problem in biodiesel production.. In fact, its a good thing because it means you got complete interaction between the water and the oil. When the water just sinks straight to the bottom of the barrel in one big glop, it means that all water didnt interact with all the oil it could have.

So, in short,
There is nothing wrong with an emulsion. My washes are so aggressive that the oil instantly emulsifies.. and then separates within 10 or 15 minutes or so.

When you say you are not getting an emulsion, its because your pump isnt moving enough of the two liquids to keep them emulsified.

Pick up one of my 1.5hp units and I promise you will have a full interaction between the water and the oil.


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Registered: March 09, 2006Reply With QuoteReport This Post
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Well I've never seen a pitbull pump so I know very little about it.

However, which pump you use has nothing to do with emulsion issues.


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Registered: March 09, 2006Reply With QuoteReport This Post
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quote:
Originally posted by steved:
Hi Murphy, Is that what your testing shows or is that what you think. Have you done any pump wash tests with these 2 different pumps ?

I don't recall you posting any pump tests at all.

Surely if it takes you 12 hours to wash you have not ?


Hey I tried..



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Registered: March 09, 2006Reply With QuoteReport This Post
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Murphy,

quote:
However, which pump you use has nothing to do with emulsion issues.


That is a bold claim. Have you tested enough to say that as a fact under all conditions?

I see different degrees of emulsion from different pump with the same BD & water.

Yes, the amount of glyceride is a major factor. The amount of soap is anoter key variable. So is temp.

In the kitchen, did you ever try to make mayonaise with warm oil? Much harder to make it persistently emulsified than with chilled. The degree of mixing sure looks like it matters, too. More thorough mixing can cause more stable emulsions, at least from what I have seen.

I am not saying that a certain pump will always produce a stable emulsion. Just that, from what I see, all else being equal, more vigorous mixing will create a more stable emulsion.

Andrew


Andrew

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Location: Northern California | Registered: February 27, 2006Reply With QuoteReport This Post
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quote:
Originally posted by Andrew Morris:
Murphy,
I am not saying that a certain pump will always produce a stable emulsion. Just that, from what I see, all else being equal, more vigorous mixing will create a more stable emulsion.

Andrew


but with properly made biodiesel, no water/bio emulsion is going to be stable. Vigorous mixing may produce a 15 minute emulsion where Super-Vigorous mixing might create a 30 minute emulsion.. What's the big deal?

Now, if you have glycerides in there, and we all do, then the amount of agitation is going to make a difference.

However, to suggest the use of a certain brand of centrifigul pump to achieve a certain amount of blending or other wash tank agitation is just kind of silly.

Everyone processes fuel under different circumstances. Try running some high titrating oil through your process and use some reverse-osmosis water to wash with. Run that through the centrifugal pump washing system and watch what happens.

I'm not saying the pitbull pump is bad to wash with in any way.. if it works for your process and you like it, GREAT! That's a good thing to know.. But to suggest it causes or doesnt cause emulsions over some other similar brand pump is back to silly again.


Now, if you want to talk about pump quality, I'm a bit envious of Ricks pump Here

These little blue HF pumps have a lot of thread problems.


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Registered: March 09, 2006Reply With QuoteReport This Post



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quote:
Originally posted by Murphy:
Now, if you want to talk about pump quality, I'm a bit envious of Ricks pump Here

Nobody beats The Godfather!
DD
 
Location: NY | Registered: February 20, 2006Reply With QuoteReport This Post
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I agree with Murphy that you have to qualify your statement about certain pumps being better for washing.

I work at a biodiesel plant that produces about 25 million gallons of biodiesel a year. I have been working in the lab a lot recently doing a lot of R&D.

If you're making a stable emulsion with a pump, you should trouble shoot your process, not the pump.
 
Registered: July 16, 2007Reply With QuoteReport This Post
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Murphy,

Yes, you make a good point. If the difference is only 15 min, so what? But that may not always be the case.

quote:
but with properly made biodiesel, no water/bio emulsion is going to be stable.


Can you define properly made BD? This sort to wording needs definition, in my oppinion.

Even so, I am conviced that mine is properly made, given that it passes 3/27 every time. And, compares favorably with my ref sample which GC tests at .2548 total glycerides. However, I don't think it would stand up to your washing methods, unless both BD and water we hot. Even then, it might not. Another factor which affects emulsion tendency is remaining methanol. I tend to skimp on that as much as possible. So, I go a bit heavy on the catalyst to force the reaction, (but makes more soap). Both of these factors lead me to wash more carefully.

It seems to me that all of these factors have an effect, so I think you need to be careful about blanket statements unless you are sure they apply under every situation. Otherwise it leads to people oversimplify things. Don't you think?

Andrew


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Location: Northern California | Registered: February 27, 2006Reply With QuoteReport This Post
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Hi Steve!

Hahaha!! True salesman! I talk to salesmen on a regular basis trying to get my to buy tower internals, pumps, centrifuges, filter/coalescers, flow meters, valves, etc. The best thing about salespeople, free lunches. Where's my free lunch? Haha!

Seriously though, I'm just stating that for faster washing the type of pump you select depends on what kind of biodiesel you are making. In our process, you can run our biodiesel and water through a high shear mixer and not get a stable emulsion.

If you are making biodiesel that is prone to making a stable emulsion, then maybe your pump is the way to go. But if you are making biodiesel that does not form this stable emulsion, you may get better washing with a different pump that would normally cause you to create a stable emulsion, mainly because the high shear factor contacts the two liquids better. That's all.
 
Registered: July 16, 2007Reply With QuoteReport This Post
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Steve,

By the way, in Spanish "te invito" means "I invite you" litterally, but also it typically means, "my treat". So if you're inviting me, I'll send you my address so you can send me my free pump. Wink
 
Registered: July 16, 2007Reply With QuoteReport This Post
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Hey Steve,

I could have used you a few months ago before I bought a TV online! I wasn't too pleased with what I got and it ended up costing me (in the end) the same as if I had gone to a store like Best Buy and just bought one from there. Lesson learned.

By stable emulsion, I mean something like mayonaise. Ideally, you WANT to create an emulsion because, as Murphy stated before, it means that you have contacted the oil and water over the maximum surface area. A non-stable emulsion will not stay that way, a stable emulsion will.

After looking at your pumps impeller, it appears that it would not create the shearing factors that an open faced impeller would. It looks like the incoming fluid enters the impeller at the center, then gets channelled through the impeller without coming into contact with additional entering fluid. The open faced impeller would do the same thing, but new fluid entering the pump would "hit" the fluid moving away from the axis of rotation, thus causing a significant amount more turbulence in the pump, ie. mixing.

There are a different breeds of pumps that are specifically designed for high shear mixing. I would assume that this pump is design for the opposite.

If you want to improve the time it takes to wash AND improve your washing, the best bet would be to use a pump that mixes well, and combine that with a centrifuge to separate the two fluids of different specific gravities.

Maybe someone can design one out of an old washing machine. Anyone? Wink
 
Registered: July 16, 2007Reply With QuoteReport This Post



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WOW!! this has really provoked more discussion than I ever thought it would.

I made a batch today and was playing with different ways to wash and discovered something interesting. I did the 5% water prewash, let the glycerin settle out and drained it off. I then put 1/2 gallon of BD into a glass container(which is still pretty warm and orange juice looking from the prewash). I added 1/4 gallon of warm water to the container and shook it up. It did not create an emulsion so it settled quickly and so I did it again and shook harder. No emulsion, quick settle and the water was almost clear. On the 3rd time, I shook the snot out of it and it settled quickly and the water was clear. I then put my air line with diffusing stone into the jar and bubbled it for about 5 minutes. When it settled out, the water was cloudy again just like on the 2nd wash.

Anyone have any theories on this?
 
Location: Mid Michigan | Registered: September 29, 2005Reply With QuoteReport This Post
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I forgot to ask, where can I buy the Pitbull for $35 plus shipping?

Also, this may be a dumb question but explain the 3/27 test. Smile

Thanks
 
Location: Mid Michigan | Registered: September 29, 2005Reply With QuoteReport This Post
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