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RE: Cleaning of polymerization reactors



We have had success using several relatively benign chemistries, which
are then recycled on-site to reduce cost/waste even further.  The
practice of chemical removal, coupled with a more aggressive cleaning
cycle may shorten the time spent cleaning.  Ultimate value of
introducing a chemical ($) in place of water vs. the shorter cycle time
would have to be calculated on a case-by-case basis.  Let me know if you
think chemical cleaning to achieve faster turnaround is an option for
this facility.

Bill Green
bgreen@ecolink.com
http://www.ecolink.com

> -----Original Message-----
> From:	cmontovino@pprc.org [SMTP:cmontovino@pprc.org]
> Sent:	Friday, March 20, 1998 11:59 AM
> To:	p2tech@great-lakes.net
> Cc:	'charlie@TECnet.org'
> Subject:	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
> 
> --
> Please reply to the address above and send a copy by e-mail to
> charlie@tecnet.org. Please include the original message with your
> reply.
> 
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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
>