Metal Finishing Guide Book

2011-2012 Surface Finishing Guidebook

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Page 95 of 707

characteristic of the steam condensate passing through the carbon assists in removing solvent residue. The mixture of steam condensate and solvent then passes through a water-cooled heat exchanger, which cools the solution. This allows for gravity separation to occur in a water separator device due to the dif- ference in specific gravity of the liquids. The reclaimed solvent is now ready for reuse or disposal. The water discharge is channelled for treat- ment or disposal. (See Fig. 2.) COOL DOWN As hot, wet carbon will not readily adsorb solvent, the recently des- orbed carbon must be dried and cooled before the next adsorption cycle. Ambient air or process air, which dries and cools the carbon, is drawn through the bed for a pre-set period of time. At the end of this cycle, the unit shifts into a stand-by mode ready for the next adsorption cycle. CURRENT REGULATIONS The most current regulations regarding solvent degreasers and the sol- vent that is used in them that affect many users today are: • EPA regulations: Clean Air Act/Title V permitting/Hazardous Waste Streams; • OSHA: Health Assessment of fluids to operators/ppm exposure limits; • NESHAP compliance for equipment (Federal minimum guidelines); • Record keeping for NESHAP compliance; • Local environmental regulations can exceed Federal regulations; • SNAP approval for listed solvents. There are other issues to consider, but the above-listed items are the most frequently addressed items by the degreaser end user, environ- mental permitting agencies, equipment manufacturers, solvent sup- pliers, and regulatory field inspectors. BETA SITES Multiple-field Beta sites have been operational for several months with successful results. These sites were processing different types of work under various conditions. The continuous analytical testing of the reclaimed solvent has proven the validity of the process. SUMMARY This new technology allows for the capture and recovery of nPB solvent 94

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