-----Original Message----- From: Ackland, Tony (CALNZAS) Sent: Monday, February 19, 2001 9:59 AM To: '[EMAIL PROTECTED]' Subject: RE: [Distillers] Continuous still ?
First point to note ...I've mixed up my terms ... the new section below the feed point is actually a "stripping" section; the standard column above this is the "rectifying" section (not the other way round!) - thanks Mike Tim, I'd considered some sort of bleed-off for the other fractions, but the sticking point was knowing what sort of flowrate you'd get of each of them. e.g. off a 20L wash, I'd be surprised if there were more than a few mL of the tails present (in concentrated form). So, even if they were being carried in a "mostly ethanol" stream at the different heights, you'd still only want to limit their collection to a VERY slow drip. But I couldn't see how to do this accurately. Then I got to thinking, that if the total volume of wash was still say less than 100-200L (plenty for personal consumption !), then there would still only be a small total amount of tails, and it might be likely that they could either be fully retained within the column (at their own level), or likely to find their way out with the continuously discarded bottoms. I'm figuring that even as a "continuous" still, it is limited to batch running, and doesn't have quite the same concerns as something designed to run continuously for months at a time ? Its hard to know, given we don't know the relevant concentrations of them in the incoming wash. But what you suggest is an easy enough modification to make, should my guessing be wrong. Ted, Good thinking... my plan was to try and keep it as simple as possible, without using anything fancy (not even a pump) or extra - see if I could do it as a simple add-on to a normal column...but you got me thinking more about trying to use the condenser, rather than the boiler. I originally had problems with seeing how to pass the wash through the condenser coil (as my present one has quite a large pressure drop - doubtful that a simple gravity feed system would push through it). But - how about a "cold finger" design ? It doesn't have to be perfect - just as long as the feed does a fair chunk of its heating up there, it is freeing up the boiler to make the vapour. And keep the water cooled coil above it, for backup in times of low wash feedrate. The coldfinger could be a large diameter, with little pressure drop. The way I have my condenser at present, this could easily be added as a separate unit between the condenser and the metering valve - no modifications required. The only downside of not perfectly heating (or superheating) the feed is that it will use a bit more of the column to heat up - so get a small dead zone not doing much below the feed point, other than transferring heat - no dramas - just make the stripping section a little bit longer. I've included a second diagram - not to scale, but to show the layout By taking the coil out of the boiler, the boiler could be made even smaller. The new problem that this introduces is that the wash barrel now has to be higher than the top of everything - probably a couple of meters up. Need someway of getting it on top of a ladder, or using a header tank (and pump, damm !) I'll do the maths this evening and see how using the condenser for some preheating changes the flowrates etc. thanks for the input. Tony [Non-text portions of this message have been removed] ------------------------ Yahoo! Groups Sponsor ---------------------~-~> eGroups is now Yahoo! Groups Click here for more details http://click.egroups.com/1/11231/0/_/837408/_/982531540/ ---------------------------------------------------------------------_-> Biofuel at Journey to Forever: http://journeytoforever.org/biofuel.html To unsubscribe, send an email to: [EMAIL PROTECTED]
