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Nylon 6 Extrusion - Caprolactam Waste

Nylon 6 Extrusion - Caprolactam Waste

Nylon 6 Extrusion - Caprolactam Waste

Hello all -

My plant runs five Nylon-6 extrusion lines, each fitted with a vacuum vent and liquid-ring vacuum pump using water as the seal fluid. During normal operation, we pull a large amount of caprolactam waste and other solid/liquid contaminants into the vacuum system. Despite two knockout pots before the pumps, this crud reaches the pumps and mixes with the seal water, which then must be disposed of as a hazardous waste.

Housekeeping is a real issue on these lines - seal fluid leaks are inevitable, capro-waste is the consistency of lard, and cleaning out knockout pots is not a clean job. We are also spending a big chunk of money each year on hazardous waste disposal. I'm looking into ways to reduce this waste stream or at least make handling and housekeeping a bit easier. Changing the seal fluid, redesigning of our knockout pots, redesigning our extruder vents, moving to dry-vacuum pumps, etc. My supervisor has been looking into fractional crystallization but I don't anticipate that being any cleaner than our existing knockouts.

A few vacuum system vendors have recommended against dry vacuum pumps as the process is just "too dirty," but I feel like there must be a way to clean up the process a bit. Any of you folks have any insight into a system like this?


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