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Methoxide Mixing Tank Designs

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September 23, 2012, 03:35 PM
Agri-Plus Products
Methoxide Mixing Tank Designs
I need some suggestions. Here's my dilemma... I have a NWR Alternative Fuels 80 gal processor. When we bought the processor about a year and a half ago, we made our first 80 gallon batch exactly like the instruction manual said. From then we've made some adjustments and now know the process by heart but there is still one problem. The one instructional piece that we couldn't change was the fact that we can only mix 500 grams of KOH at a time. This is very inefficient considering we have oil that requires over 6000 grams sometimes and only a hand-operated diaphragm pump to mix it with. We have bought another electric processing pump to mix it with but haven't hooked it up yet. At one point we got impatient. I mixed 1500 grams all at once, started pumping and methoxide shot out the top of the cone tank. I'm not sure what happened because I've seen some people on youtube mix all of their catalyst at once. I don't know if it needed a bigger vent or it's because our oil requires so much catalyst that it becomes dangerous to mix more in. (When I mixed the 1500 grams in, I had already mixed about 5000 grams in 500 gram increments). Also, could the hand pump not mix it quick enough, would the electric pump prevent this? My main question is how could I adjust the design to make my methoxide mixing more efficient while keeping it as safe as possible? As of right now it is a 30 gal polypropene cone tank with a hand pump for mixing. We pour our catalyst through the top and let it dissolve before adding more (usually takes 2-3 mins each 500 grams). And please keep in mind, the most important factor is mixing the chemicals safely.

Thanks,
PJ
October 07, 2012, 07:01 PM
Rick G
PJ,
My first questions is; Why so much base? My oil titrates 3-4 ml of 1mg/ml NaOH, I make 65 gal batchs and I only use 2kg NaOH. Six kg seems like a great deal more than needed for 85 gal batches.
I'm not familar with your system so be skeptical of any suggests I make. I use an inexpensive floor model drill press. Set the pulleys to the lowest speed possible. Using a length of 1/4 in stainless steel rod bent in a L-shape ( like a paint stirrer made from a coat hanger) The length of the shaft is long enough to reach the bottom of a 5 gal plastic bucket with the horizontal long enough to sweep most of the bottom. Fill the bucket with a measured amount of methanol (about 4gal or 50 lbs), place on the drill press table, raise the table until the rod almost touches the bottom, center the bucket and start the stirring. When the methanol is stirring smoothly, slowly add no more than 1kg of NaOH. The bucket will become quite warm but unless the initial temperature of the methanol is quite warm it should not boil. I always use a full face shield, long gloves and long sleeve shirt. It should be fully dissolved in 2-3 min. Any remaining undissolved solids are probably sodium carbonate formed when NaOH is exposed to air. Poorly stored NaOH can absorb carbon dioxide rapidly. The sodium carbonate is ineffective catalyst. When dissolve I remove from the drill press and add to the batch of circulating oil. It takes two batches of methanol/NaOH mixture to make my 65 gal batch of BD.

Caution: Stirring small amounts (less than 2gal) of methanol/ NaOH is not recommended because the agitation causes much splashing and the bucket tends to move and hit the stirring rod.

This may not be the safest method but works reasonably well for me with practice.
Also, I mix next to an open doorway of the BD processing shed well away from the house. While it is mixing I step out side the building. I also have a 22 in box fan mounted next to the drill press at chest level blowing the vapors away from where I stand and making good air circulation through the shed. Windows in the rear of the shed are wide open and the fan runs even during cold weather while I process BD.
Hope this helps
October 07, 2012, 07:08 PM
Biotom
I use a modified 60lb propane tank for mixing methoxid . Mixing is done with an air powered drill and a paint type stirer.




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November 08, 2012, 12:24 AM
Julliward A Woods
Is it needed that the tank must contain carbon materials???


site senior
November 08, 2012, 01:00 PM
TheVol
Hi Julliward....

Are you with the Utility System there in Daphne?