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RE: solvent recovery



Frances,

What they need is a small ventilated box to hold the trays while drying.
The box can be slightly larger than the trays and be open on one side to
allow the trays to be slid in.  The TCE vapors should then be removed from
the box by means of a small blower that moves the vapors through a cooling
coil to a collection bottle.  A vent line from the bottle should go outside
the building to a safe area.  For cooling, the coil can be placed in a
bucket filled with ice.

In sizing the blower, try to use as small a blower as possible.  A rough
rule of thumb would be to maintain a velocity of 50 fpm across the open side
of the box.  This will ensure that the TCE vapors do not enter the work
area.  Do not be tempted to jack up the flow rate too high.  Safety people
love to jack up flow rates to ensure capture but it will defeat the
effectiveness of your recovery system (the ice coil).  A hinged lid along
the open face will allow you to cut down the vent rate.

If you need to speed up drying, a few light bulbs placed under the trays
will work.  You will need to experiment with the wattage.  Another option
might be to locate the box on top of a heat generating piece of equipment.
Both of these methods are not recommended if they switch to a flammable
solvent. If they can, have them try water.  For some reason, R&D people just
hate to try this option but it does work in some applications.

Hope this helps,

Mike.callahan@jacobs.com
> ----------
> From: 	Frances Bernards[SMTP:fbernard@deq.state.ut.us]
> Sent: 	Friday, February 27, 1998 7:41AM
> To: 	p2tech@great-lakes.net
> Subject: 	solvent recovery
> 
> A small business is interested in recovering solvent vapor from a ceramic
> slurry
> composed of ceramic powder mixed with trichloroethylene.  The solvent is
> used to
> dissolve the binder and the slurry is spread out on a plastic surface to
> dry
> (solvent vaporizes).  The end product is then used as a standard for
> electronic
> products.   Currently, there are no process controls, e.g. hood vents.
> This is a small operation, using less than 5 liters a day of solvent.  
> The owner is investigating a less toxic alternative to the
> trichloroethylene.
> 
> Does anyone know of an inexpensive way to collect the solvent vapors?  Or
> maybe
> a better way to produce the product?  I'm not familiar with this type of
> process, so this is a new one for me.
> 
> I'd appreciate some guidance.  Thank you!     
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