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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,
> 
>