WFU Biofuels

Wake Forest students, faculty, staff and associates making and testing vegetable-oil based fuels.

Sunday, September 11, 2005

Captain Dave & Co.'s First Batch--Ideas?



Over the weekend we took a shot a making some fuel. Some things went well. The plumbing behaved as it was supposed to for the most part, or at least could be tweaked to do so. One problem, though, was the water heater, which didn't really heat much on Saturday. The attempt on Saturday resulted in no separation of fuel and glycerine, which might have been attributable to the low temp. So on Sunday we tried again, this time after getting the heat on. Our thermometer indicated that the temp got only to 120 F. We need to calibrate this thermometer and see if it is accurate. Assuming that it is, it was a mystery to me why we leveled off at 120 when I had the setting cranked to 130 and then 140 (Paul?). In any case, 120 seems close to 130 and Steve thought that as long as the oil was liquid that the difference between 120 and 130 was not a problem.

So, we're at 120, and I ran the circulating pump for about 90 minutes of reaction at 120 F. Except, looks like no reaction took place. I gave it all day to settle, and no separation occurred. It looks now the same as when we first mixed the methoxide with the oil on Saturday afternoon.

This evening I took some of the reaction mixture to the lab and got a pH, with a stir bar mixing well 1 ml of the reaction mixture in 10 ml of isopropanol. pH was 9.86! I was concerned that the mixture was still too acidic, because the sodium methoxide that we mixed with the oil on Saturday was made as 150 g Red Devil lye in 10 liters of methanol added to 50 liters of oil (3 g lye/liter of oil). This is at the low end of the lye concentrations that you find in recipes. Instead, the reaction mixture is quite basic. We need ideas on how it got to be so basic (something that had been in the water heater?), and how to get it into the desired 7-8 range.

Notes:
-I flushed the used water heater with tap water for about half an hour last week, and got a lot of sediment to drain out. When I was done, it seemed like nothing else was in there, but who knows.
-I have a sample of the original oil and of the current reaction mixture, in my lab. Marcus and Jen, would you like to have a go at them and see what you think they are made of?
-when the thermometer says 120 F, the pipes are pretty warm. I wouldn't want to take a bath at that temperature. So, I suspect that the thermometer is not far off.

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