I use a 700 watt power drill to mix 180 litres of oil/methanol. It's not an efficient motor, but suggests you'd need at least 5KW into a 300 gallon tank. 3 phase is more efficient so you might get away with 4Kw.
The milk bulk tank "mixers" I've seen are really only stirrers. They'd struggle to get enough agitation for a reliable biodiesel reaction. I'm moving over to an enclosed tank with recirc pump. I could probably get away with less power, but intend to use a 1.5KW 80m head water pump. The ester is more viscous, but it won't be lifting more than 3ft so should be well over rated. A pump should be more efficient than a propellor, so I expect to get a violent mix. I've also thought about using a venturi in the pump outlet pipe to draw in the methoxide. The turbulence of a crude venturi should make sure most of the mix happens in the pipe. Tank turbulence will make sure. How are you containing the methanol fumes with your dairy bulk tank? Dave --- In [EMAIL PROTECTED], Keith Addison <[EMAIL PROTECTED]> wrote: > >To: <[EMAIL PROTECTED]> > >Organization: Appal Energy Co-op > >From: "Appal Energy" <[EMAIL PROTECTED]> > >Date: Fri, 8 Jun 2001 13:24:28 -0400 > >Subject: [biofuel] Mixing times for complete reactions > > > >I know that there are differing beliefs on this list as to required > >mixing times for reaction completion. > > > >We never had any need to vary mixing time beyond 2 hours until we > >got up to the 300 gallon level. What we found was that our mixing > >times changed relative to the motor we were limited to and the > >number of gallons being batched out. The limiting factors on the > >motor were amperage draw, available electric supply, etc, coupled > >with the propeller configuration to get vigorous mixing (too large a > >prop over amped the motor, too small resulted in slow attainment of > >homogeneity). > > > >Another variable was the tank geometry. Whereas most tanks are > >cylindrical and vertical, our prototype was a used 400 gallon > >stainless steel dairy cooling tank. (It was free, so we aren't > >complaining.) In such a tank, the far left and right regions of the > >tank don't receive as much agitation as the center area, which means > >a requisite longer reaction time than something akin to a 55 gallon > >drum - again, cylindrical and vertical. > > > >100 gallon batches took ~8 hours, 300 gallons took ~24 to insure > >that the reaction was complete. > > > >Using nothing but shadetree ingenuity, completion here is being > >determined by subjecting a liter of supposedly finished product to > >the entire process a second time to determine if any more glycerin > >will drop out. (An antique gas chromatograph is on its way.) > > > >So, while 2 hours may be sufficient for a 55 gallon drum reactor, > >unless the agitator is increased in mechanical capacity to > >proportionally match the increase in fluid volume being processed, > >we strongly suggest increased reaction times when upscaling, until > >such a time as the exact completion point can be determined by the > >operator. > > > >It's a whole heck of a lot easier to increase reaction time until > >the appropriate time window can be determined than ending up with a > >passel of mega-emulsifying mono- and di-glycerides from an > >incomplete reaction - read "mayonnaise" - and suffering deflating > >bouts of biodiesel despair. (Been that. Done there.) > > > >Todd > >Appal Energy > >[EMAIL PROTECTED] Biofuels at Journey to Forever http://journeytoforever.org/biofuel.html Biofuel at WebConX http://www.webconx.com/2000/biofuel/biofuel.htm To unsubscribe from this group, send an email to: [EMAIL PROTECTED] Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
