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| quote: Originally posted by AZBiodsl: jehu if you don't do a soap test after your wood towers how can you know its taking out the soap? Unless the soap falls out of solution and begins to clump together the sawdust won't take out the soap
AZ, who told you this? Its nonsense. |
| Location: Scotland | Registered: March 19, 2006 |  
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| I am not a scientist or a chemist either, but after filtering over 1/2 million gallons of bio I have drawn a few conclusions.
1:Sawdust chips work, they DO remove soap. Life is dependant on the ppm of soap in the bio going into the sawdust. Many, many soap test over the last year and a half have shown this. I like to see soap numbers in the 500ppm range or less before the filters.
2:Methanol left in the fuel greatly reduces the soap removal properties of the dust. For the first several hundred gallons you want see this with the soap test, your results will look good.(volumn will be dependant on cubic feet of dust used) As the wood chips are used and soak up more and more methanol your soap numbers will start to rise. From experience and many test if the fuel is demethed I can filter several thousand gallon before soap numbers get to high, but if the fuel is NOT demethed I was lucky to get 1000 gallon before failing soap test.
3:The amount of methanol removed by the sawdust is negligible, you will definately not pass ASTM flashpoint this way.
I used to homebrew thanks to all the info I got from this forum (avid reader not a poster). I made 30 gal batches, If I were using a 55 gallon drum for a sawdust filter, making 1 to 2 batches per/week it would probably take several months for the above results to showup. I can see where people would say it doesnt make any difference if you demeth before or after, most people probably change there chips more often than this.
I can also see where people doing like Jehu are not having problems. The methanol laden fuel is filtered through the sawdust and removes gross soap level. The methanol that is still present in the fuel holds the rest of the soap in solution. The fuel is probably being used fairly quickly and doesnt sit for long periods of time where the methanol could evaporate and let the rest of the soaps fallout. Burning soap is another story. You dont know your soap ppm without testing.
Or......The saw dust is being changed often enough that soap ppm is staying low enough that soap is not a problem.
Bottom line...If the fuel you make works for you and you are happy with it Great! |
| Registered: January 22, 2010 |  
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| Dude, I looked at buying/purchasing a dry washing tower and the cost was horrendous, £898. I sat and thought and the ideal home made solution is the old fashioned fire extinguisher. The old water version with the big brass twisty thing at the top. Remember hit the top and the water rushes out. The design is spot on; the vessel is pressurised, it has an out let which has brass fittings with a feed from the bottom. Make a hole on the opposite side and that is the out let. Brass fittings work well. The Eco2pure sits in the bottom circa 1.5 kg and then a pump is fashioned to flush it through. The hard part is to get a filter on the outlet side..........I am still working on this, I think an inline with 75 micron washable affair, £29.99 with 2 filters (Ebay). Tried it with out the inline filter through a filtakleen bio-diesel filter with 1 micron filter (found in a scrapyard) witha new filter from Luton. Found bits in the polishing pot so need the inline bit. This so far cost me £19.00 inc delivery for the polisher filter and Eco2pure £70 inc VAT and delivery. I am now building a oak sawdust filter system for pre tower and polish any advice gratefully. Good news my neighbour is a bespoke carpenter with gallons of superdry sawdust and ..............its oak  Bananaman |
| Location: UK | Registered: May 04, 2010 |  
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| quote: Originally posted by Overworked:
3:The amount of methanol removed by the sawdust is negligible, you will definitely not pass ASTM flash-point this way.
My experience differs. The sawdust works because it removes the methanol thus precipitating the soap which is then depth filtered out by the same sawdust. If this did not happen it would be impossible to get zero soap content using the method as residual methanol would always hold a significant portion of soap in the bio which would then be detected by the testing method used in the particular instance. It is a fact that zero soap content has been achieved with the method and been tested and shown to work by a reputable university laboratory. Thus methanol has to be removed. Logic and lab testing aside it is my observation that this happens also.
mathematical elegance -- desired result achieved with minimal complication
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| Location: Manchester UK | Registered: June 03, 2003 |  
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| Ok guys, How is it going here with the dry washing? No comments for months. I have been waiting for you guys to get this dry washing down to a science so that I could implement it without have to go through a bunch of trial and error.
Running on bio diesel since sept 05
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| Registered: September 15, 2005 |  
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| I have been "dry washing" for a couple years now. Once the biodiesel is transferred leaving the settled glycerine behind is it then circulated and demethed. A settling period of at least a few days gets the suspended soaps to fall out and what is not immediately removed by gravity is taken out by the 200L drum of hard wood chips followed by a lead /lag resin tower set up and final polished using a 2 micron CAT fuel can. My fuel has frozen and thawed several times over winters and there has been absolutely NO fall out. It test zero PPM soaps in the lab. HTH |
| Location: :-) Great White North eh ? | Registered: December 10, 2004 |  
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