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propposed method to dewater your bio-diesel. Need some input
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Originally posted by Samuel:
Ok Jon you got my attention.

Keep in mind ASTM quality fuel is only recommended for 6 months storage. If you plan to store bio diesel longer than that, one may need to exceed the ASTM quality in certain areas.

If what you say is correct, it is used by commercial pants and turns out astm quality fuel I will take a very hard look at it.

Ok it sounds good but there are still some small issues.
I like working with high FFA oil. The process I use produces water which contaminates my methanol. I have to dry methanol and I use Epson Salt for this. This methanol (dried by Epson Salt) repeatedly comes in contact with my oil. This is why i must water wash my biodiesel to make sure there is no Epson Salt remaining in the finish product. This is because I don't know the effect Epson Salt has on diesel motors. If I were to stop water washing the Bio-diesel there is a possibility I may have to switch from Epson Salt to something else. As of yet I don't know of a good alternative. I doubt very much that the wood chips would remove Epson Salt from Bio-diesel.



When filtering with wood isn't there still a moister issue? Water, soap and glycerin is made in the last lye methanol step. Seems to me some water will be suspended with the bio-diesel and 5% methanol. After the methanol is removed some water remains. How much water remains and should it be removed?

I observed when very wet biodiesel is heated most of the water will settle out. There still will be moister in the biodiesel and I am thinking the percent is close to that in the biodiesel filtered by the wood chips unless the wood chips are baked dried before use. This would filter and dry the biodiesel at the same time.

Is this what you had in mind Jon?

If so, bake drying the wood chips would be another step and I am not sure how easy this will be. I am quite sure this would be more difficult than bake drying Epson Salt.

And what about recovering the soaps?

For a good conversion I use excess lye and this sometimes(based on water contamination) makes excess soap.
Is there a way to recover the soap from the wood chips? I am wondering if water can be ran through the chips right before changing the chips to flush out the soaps. I recycle 100% of my soaps. Sometimes this can be 5% to 15% so this adds up quick. Most of the soap is in the glycerin layer but still quite a bit remains in the biodiesel. Soap+water+acid=FFA FFA+methanol+Acid=Biodiesel/water.

Unfortunately, until I know for sure there is no Epson salt in the biodiesel or until i use a different way to dry the methanol it seems I'am stuck with water washing. I have checked quite a number of drying agents and most are not suitable for methanol with the exception to molecular sieves which is something I am going to check out. I thought there were high but it seems the prices have come down since i looked last/

Molecular sieve 3A (for methanol drying) is around $3 to $4 pound. This is Much higher than Epson salt but considering it can absorb water up to 21 times its own weight it definitely cheaper in the long run. This means a lot less time is spent in regenerating the Molecular sieve 3A. 1 pound Molecular sieve 3A = around about 21 pounds of Epson Salt.


I wonder if the polymer found in disposable diapers can adsorb water without absorbing methanol. It sure would be cheap to get. Dumpster diving behind some daycare center for used pampers might be a little weird though and one would have some explaining to do if caught.

This message has been edited. Last edited by: Samuel,


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Location: Indiana | Registered: June 13, 2005Reply With QuoteReport This Post
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I do WBD recovering the methanol from the biodiesel and glycerin at the same time, I get about 98% purity methanol recovered. Then I drain hot fuel (~175F) into a tote where I bubble dry air through it over night, this drives off any remaining methanol and water and results in crystal clear, bone dry biodiesel the next morning.
Most of the soap comes out in the glycerin when doing WBD and very little comes out in the chips, not enough to bother trying to recover it IMO... I just empty my chip drum once a year for a spectacular fire out at the fire pit.
As far as dry chips, go to a furniture joint and talk to them, you want to make sure you get chips that are not contaminated with glue from particle board or laminated wood. I get mine from a Mennonite guy who makes oak chair spindles, its all kiln dried good stuff. I have also used ash chips with great success. I have heard other folks on here using store bought bagged chips from the pet/farm stores with good success.
I dont know what to tell you about the salt, I would think that if you only use it before adding the caustic it would get washed out with the glycerin like the other salts that get created in the reaction but that is pure speculation on my part.
Cheers,
Jon
 
Location: Wellington County, Ontario Canada | Registered: February 07, 2008Reply With QuoteReport This Post
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Can I jump in here? Is this conversation limited to only chemical means of drying fuel?

Why not just use vacuum dehydration.. There are no consumables or chemicals that have to be restocked or rejuvenated, no possibility of accelerating oxidation through exposure to air, and very little actual energy is used.

Additionally, the process is extremely effective, relatively speedy, and can remove water to non-detectable limits.

And once you're set up, it can also remove the water from your incoming oil and/or remove excess meth from the glycerin or fuel.

About the only drawback is that it does cost a bit more to set it up.. but that would be made back in the savings.

Hope that helps,


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Registered: March 09, 2006Reply With QuoteReport This Post
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Yep, that's the only way to go in my opinion Murphy. I have used vacuum since I started.
Cheers,
Jon
 
Location: Wellington County, Ontario Canada | Registered: February 07, 2008Reply With QuoteReport This Post
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quote:
Originally posted by Murphy:
Can I jump in here? Is this conversation limited to only chemical means of drying fuel?

Why not just use vacuum dehydration.. There are no consumables or chemicals that have to be restocked or rejuvenated, no possibility of accelerating oxidation through exposure to air, and very little actual energy is used.
Hope that helps,


Vacuum dehydration is perfect for removing methanol.

Removing water from oil or biodiesel is another thing. If any water whatsoever settles to the bottom of a tank that is say for an example 6 feet tall you can forget pulling it off with a vacuum. Even with a good vacuum and heating this tank of biodiesel to almost 212F there is still a issue pulling this water out.

With a very good near pure vacuum water will boil at almost at any temperature up to the point of freezing. When water is under oil or biodiesel, the pressure effect of the oil/biodiesel pushing down on it is enough that a vacuum seems to have little or no effect. This is a law of physics I have totally overlooked when I built my vacuum dryer. I ended up heating to above 212F and was still have issues pulling this water out with a vacuum. I would open the bottom tap and all be darn there would still be water coming out. This happen even though my heat source was at the bottom of the tank.

This is why there is little steam explosions when heating an open pan of oil/biodiesel with a little water at the bottom. The pressure hinders water from turning to steam and when it finally gets hot enough the water explodes into steam often plashing the oil out of the pan.

I am not sure if moister suspended in the oil has this same effect but if it settles to a bottom its hell to pull off with a vacuum. Bubbling hot dry air through hot oil is probably a better way.

This message has been edited. Last edited by: Samuel,


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Location: Indiana | Registered: June 13, 2005Reply With QuoteReport This Post
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If any water whatsoever settles to the bottom of a tank

...then drain it out while it's separated from the fuel. If dewatering is happening by settling then work with it.

With the fuel I process, settling removes most of the water. Then a water absorbing polymer brings it below 500 ppm as measured with a carbide manometer.
http://www.burnveg.com/forum/about72.html



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



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Originally posted by john galt:

...then drain it out while it's separated from the fuel.




Wet Bio-diesel can be tricky. When its cold it seems to hold more water than when warm. I did drain off the water prior to pumping it into my vacuum tank. To assist with the vacuum I added heat. This is what caused additional water to settle out. Had I heated it first to the temperature I intended to use in the vacuum tank and drained the water off I probably would of had better luck.


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Location: Indiana | Registered: June 13, 2005Reply With QuoteReport This Post
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quote:
Originally posted by Samuel:
quote:
Originally posted by Murphy:
Can I jump in here? Is this conversation limited to only chemical means of drying fuel?

Why not just use vacuum dehydration.. There are no consumables or chemicals that have to be restocked or rejuvenated, no possibility of accelerating oxidation through exposure to air, and very little actual energy is used.
Hope that helps,


Vacuum dehydration is perfect for removing methanol.

Removing water from oil or biodiesel is another thing. If any water whatsoever settles to the bottom of a tank that is say for an example 6 feet tall you can forget pulling it off with a vacuum. Even with a good vacuum and heating this tank of biodiesel to almost 212F there is still a issue pulling this water out.

With a very good near pure vacuum water will boil at almost at any temperature up to the point of freezing. When water is under oil or biodiesel, the pressure effect of the oil/biodiesel pushing down on it is enough that a vacuum seems to have little or no effect. This is a law of physics I have totally overlooked when I built my vacuum dryer. I ended up heating to above 212F and was still have issues pulling this water out with a vacuum. I would open the bottom tap and all be darn there would still be water coming out. This happen even though my heat source was at the bottom of the tank.

This is why there is little steam explosions when heating an open pan of oil/biodiesel with a little water at the bottom. The pressure hinders water from turning to steam and when it finally gets hot enough the water explodes into steam often plashing the oil out of the pan.

I am not sure if moister suspended in the oil has this same effect but if it settles to a bottom its hell to pull off with a vacuum. Bubbling hot dry air through hot oil is probably a better way.


The vacuum dehydrator system I designed and sell plans for via my website will thoroughly remove water or methanol from oil or glycerin to near non-detectable limits. No steam explosions, no trapped water, no guesswork. As with all of my designs, it works every time all the time.

Bubbling hot dry air through hot oil is a guaranteed way to accelerate the oxidation process. I'm not saying I would never do it, I'm just saying its a sure fire way to oxidize the fuel.


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Registered: March 09, 2006Reply With QuoteReport This Post
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quote:
Originally posted by Samuel:
quote:
Originally posted by john galt:

...then drain it out while it's separated from the fuel.




Wet Bio-diesel can be tricky. When its cold it seems to hold more water than when warm. I did drain off the water prior to pumping it into my vacuum tank. To assist with the vacuum I added heat. This is what caused additional water to settle out. Had I heated it first to the temperature I intended to use in the vacuum tank and drained the water off I probably would of had better luck.


You would be referring to suspended water. Free water, (water that settles to the bottom) is very easy to remove. Its the dissolved water that is suspended that is difficult to get out.


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Registered: March 09, 2006Reply With QuoteReport This Post
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The trick is to heat and circulate, you spray the heated liquid into the head space of the vacuum tank/reactor. When the liquid exits the pipe into the head space the pressure drops and the methanol or water flashes off and gets sucked out via the condenser.
Cheers,
Jon
 
Location: Wellington County, Ontario Canada | Registered: February 07, 2008Reply With QuoteReport This Post
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Its the dissolved water that is suspended that is difficult to get out.

That's where a carbide manometer or SandyBrae test is useful to determine just how dry fuel is and how effective different dewatering methods are.



 
Location: coldest N.America | Registered: May 03, 2005Reply With QuoteReport This Post
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Samuel; You might have a look at "Flash Evaporation" on Wikipedia. To set it up might be more trouble and expense than it is worth, but that will dry vegetable oil.
 
Location: Texas | Registered: April 27, 2011Reply With QuoteReport This Post



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Originally posted by Murphy:
Can I jump in here? Is this conversation limited to only chemical means of drying fuel?

Why not just use vacuum dehydration..



Are you using heat when using vacuum on your waste glycerin ??

It seems you know something about vacuum dehydration. Removing 5% methanol from biodiesel with vacuum is probably very easy fast and efficient. I am going to assume once a vacuum is pulled it will pull off all the methanol without dropping the temperature of the biodiesel that much.

When removing methanol from waste glycerin there is quiet a lot of methanol. I believe heat is required.. When methanol vaporizes it takes a tremendous amount of heat with it which rapidly chills the remaining liquid and methanol. The chilling effect is so great that it creates a problem. How are you working around this??


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Location: Indiana | Registered: June 13, 2005Reply With QuoteReport This Post
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Originally posted by WesleyB:
Samuel; You might have a look at "Flash Evaporation" on Wikipedia. To set it up might be more trouble and expense than it is worth, but that will dry vegetable oil.


That looks interesting. I have lots of tools, welders torches plasma cutters ect, so building a unit shouldn't be too hard. Right now winter is coming so i am doing what I can do fastest and that is building a 350 gallon tank which is heated by wood. I am low on methanol and have around 400 gallons of waste glycerin. My 350 gallon flash tank is almost done. I am working on some last minute safety issues so I don't blow myself up. Later on I will look at other methods. I am particularly interested in using anything that is a continuous process.


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Originally posted by Samuel:
Are you using heat when using vacuum on your waste glycerin ??

Yes but just a little... The input heat is more a function of energy replacement, due to the evaporation cooling effect, than a need to operate at higher temperature. Although most would agree that things happen faster at the higher temps, they are by no means a requirement.

quote:

It seems you know something about vacuum dehydration. Removing 5% methanol from biodiesel with vacuum is probably very easy fast and efficient. I am going to assume once a vacuum is pulled it will pull off all the methanol without dropping the temperature of the biodiesel that much.

I sell plans for a dehydrator system on my website.
Yes, removing methanol is fairly easy. Be careful with your assumptions if you are not familiar with fluid and thermal physics. Evaporative processing always creates a cooling effect. A great example is an air conditioner. From a mathematical perspective, there is very little difference between the average air conditioner system and my dehydrator.

quote:

When removing methanol from waste glycerin there is quiet a lot of methanol. I believe heat is required.. When methanol vaporizes it takes a tremendous amount of heat with it which rapidly chills the remaining liquid and methanol. The chilling effect is so great that it creates a problem. How are you working around this??

Ah yes.. Didn't read this far when I was replying above. You are correct. You will require some thermal replacement energy (heaters) to keep the temperature in the goldilocks zone. If you're located in a tropical climate, your "heaters" could be nothing more than some black piping and a partnership with that big fuzzy nuclear furnace in the sky.


Hope that helps,


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Originally posted by WesleyB:
Samuel; You might have a look at "Flash Evaporation" on Wikipedia. To set it up might be more trouble and expense than it is worth, but that will dry vegetable oil.


I made one of those back in 07.. Very effective, very fast, but very dangerous.... I don't sell plans for that because of the excessive danger involved.


Here's a photo.. it processed about 60 gallons per hour and could have probably done more.



The heater was based on my waste oil heater designs.


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Registered: March 09, 2006Reply With QuoteReport This Post
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Originally posted by Murphy:
easy to remove. Its the dissolved water that is suspended that is difficult to get out.


Speaking of dissolved water. If oil or biodiesel is heated to 250F will there be any dissolved water in the oil or biodiesel?? If there is then what temp will remove all the dissolved water?


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Location: Indiana | Registered: June 13, 2005Reply With QuoteReport This Post
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If there is then what temp will remove all the dissolved water?


Its stupid high. Fluid pressure on the suspended water keeps it from boiling and steaming off until such a high temp as to be impractical for home brewers to reach 0% water that way. I can't recall exactly...but maybe its in the region of .5-1% it can get down to from heating only?
 
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Originally posted by Samuel:
quote:
Originally posted by Murphy:
easy to remove. Its the dissolved water that is suspended that is difficult to get out.


Speaking of dissolved water. If oil or biodiesel is heated to 250F will there be any dissolved water in the oil or biodiesel?? If there is then what temp will remove all the dissolved water?



Heating your oil past the boiling point of water will not get rid of the water as you are thinking it will...
It might work if the fluid in your tank was only an inch deep, but that's not really practical.


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Actually, it's really not that hard to remove water from biodiesel or WVO, the low energy method most often used is Headspace Desiccation. And, yes it can removed even dissolved water. If the air is kept dry, water will naturally move from the oil to the air over the oil. How fast is regulated by a number of factors, including surface area, temperature and how wet the oil and how dry the air are. It works and you can get your oil below 500 ppm routinely not to mention keep it dry using Headspace Desiccation.

Rick
 
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