[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

RE: DBE Distillation

Jeff -

I agree with Mike that a bit more specification on the problem might help
the group to provide you with useful suggestions.  Nonetheless, he provides
some good recommendations.  I'd also add the suggestion that you look at
how much of the DBE is being lost to the "bottoms" stream (e.g., the resin
and other material taken out of the still bottoms)?  Often times, the high
viscosity of still bottoms prevents the complete recovery of solvent from
such streams -- instead a portion of the solvent remains trapped in the
still bottoms to maintain "flowability."  This can sometimes be improved by
using a wiped-surface heat exchanger as the reboiler.

Scott Butner (rs_butner@pnl.gov) 
Senior Research Scientist, Environmental Technology Division
Pacific Northwest National Laboratory
4000 NE 41st Street, Seattle WA   98105
(206)-528-3290 voice/(206)-528-3552 fax

> -----Original Message-----
> From:	Callahan, Mike [SMTP:Mike.Callahan@jacobs.com]
> Sent:	Tuesday, June 01, 1999 12:37 PM
> To:	'Jeff Lewis'
> Cc:	'P2Tech'
> Subject:	RE: DBE Distillation
> Jeff,
> I can only guess what the solution to their "problem" might be because you
> have not defined the problem.  But here goes:
> 1. DBE is a mixture and its composition may change after repeated
> recycling.
> This might affect recovery and cleaning performance.
> 2. Is pure DBE used for cleaning?  Some cleaning products include NMP or
> other solvents.  These too may increase or decrease after repeated
> recycling.
> 3. How reliable is temperature control?  Rapid heating and/or too high a
> temperature may cause boil up and foaming. This will carry over
> contaminants
> and foul the product.  Insufficient heating may be caused by a dirty
> heating
> coil or vessel wall.
> 4. The same problem with carry over goes for too high a vacuum. Or, if
> there
> is an air leak, solvent recovery will be low due to low vacuum and solvent
> losses to atmosphere will be high.  Seals should be inspected routinely
> and
> replaced at the first sign of damage or swelling.
> 5. Large losses to atmosphere may also occur if the condensing coil is
> fouled or is not supplied sufficient cooling water.  The monitoring of
> condenser temperature should be conducted before and during distillation.
> Good practice dictates that the flow of cooling water to the condenser is
> the last item to be turned off.
> Just a few points for the shop to consider.
> Mike.callahan@jacobs.com
> > ----------
> > From: 	Jeff Lewis[SMTP:Jeff.Lewis@epa.state.oh.us]
> > Reply To: 	Jeff Lewis
> > Sent: 	Thursday, May 27, 1999 7:31 AM
> > To: 	p2tech@great-lakes.net
> > Subject: 	DBE Distillation
> > 
> > I'm working with a company who reports having difficulty with the vacuum
> > distillation (recovery) of dibasic ester (DBE).  The DBE is used to
> clean
> > spray equipment and tools used for fiberglass
> > reinforced plastics manufacuring.
> > 
> > Has anyone have any experienced problems with DBE recovery using
> > distillation?
> > 
> > I have put a call in to Dupont (maker of DBE).
> > 
> > Any suggestions for improving DBE recovery, factors to consider, or
> > recommended distillation equipment appreciated.
> > 
> > Thanks,
> > 
> >