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Cleaning of polymerization reactors



Does anyone have experience with cleaning polymerization reactor vessles from adhesive manufacturing?  

Chris Montovino
Technical Director
Pacific Northwest Pollution Prevention Resource Center
1326 Fifth Avenue, Suite 650	
Seattle, WA 98101
Phone: 206-223-1151
FAX: 206-223-1165
email:  cmontovino@pprc.org
Web Site: http://www.pprc.org/pprc


----------
From:  Charlie Rosenberg[SMTP:charlie@TECnet.org]
Sent:  Friday, March 20, 1998 1:40 AM
To:  mep-field-engineers@tecnet.org
Subject:  Cleaning of polymerization reactors

*******************************************************************
If you can help, please reply to the address below and send a copy
by e-mail to charlie@tecnet.org.  
PLEASE INCLUDE THE ORIGINAL MESSAGE WITH YOUR REPLY.
*******************************************************************

[I will share information with Greg in regards to CO2 pellet blasting so
if you have provided information on that before, no need to re-send it. 
-Charlie]

I am working with a company that makes water based adhesives from a
variety of monomers.  They are interesting in increasing the capacity of
the plant by improving the cleaning of polymerization reactor vessels.
These processes generally operate on a semi-batch basis and are
exothermic. 

One of the two reactor vessels we are investigating has a capacity of 2000
gal. and uses a gate agitator during the polymerization of a polyvinyl
acetate product.  Build up occurs on vessel walls (thin, hard coating) and
agitator surfaces (thick soft coating that will peel).  The reactor is not
cleaned between batches of the same product.  A hot water boil out is used
between batches of dissimilar products.  Build up continues through a
number of production batches.  The reactor is then shut down for 24 hours
of power wash (10,000 psi) and manual chipping involving confined space
entry. 

The second reactor (2900 gal.) uses more conventional low shear turbine
mixing blades to produce a variety of acrylate-based pressure sensitive
products.  The build up is more uniform and tends to remain softer in this
reactor.  After a number of batches, this reactor is also shut down for a
long cycle of power washing and scraping. 

We are looking for equipment suppliers and best practices involving
clean-in-place equipment that can clean quickly (1 hour or less) between
batches.  We are also investigating how and why the buildup occurs, to see
whether some simple process changes may make the cleaning process less
onerous. 

Any suggestions?

Greg Hume <hume@iams.org>
Institute of Advanced Manufacturing Sciences
1111 Edison Drive
Cincinnati, OH  45216-2265
513-948-2017
513-948-2109
hume@iams.org

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-Charlie

Charlie Rosenberg, TECnet/NIST Manufacturing Extension Partnership
4 Colby Street,  Room  153                       Medford, MA 02155
Tel: (617) 627-3818  Fax: (617) 623-1427        charlie@tecnet.org
http://www.mepcenters.nist.gov             http://www.mep.nist.gov