|
lucite fabrication
Kinetic mixers are used conventionally for plastics processing
and compounding applications, i.e., mixing fillers, colorants
and/or additives with polymers. The advantage of kinetic mixers
for plastic processing stems from the ability to vary batch composition
including polymer type, polymer grade, filler material and filler
loading on a batch-to-batch basis with little or no system and/or
parameter modification. Capital equipment cost is also low for
kinetic mixers compared with alternative processing methods (e.g.,
Banbury mixers, single-screw extruders, twin-screw extruders,
or continuous mixers) with equivalent processing capacities. [(16)]
Application of stock processing equipment, like the kinetic mixer,
for new uses not included in original engineering design often
results in specific technical deficiencies. During process development
work, modifications were made to the kinetic mixer to enhance
waste processing and permit the processing of actual hazardous
and/or radioactive wastes. Kinetic mixer modifications included
a new feed tube and feed gate, installation of vent ports for
an off-gas collection system, and repair of the mixing blades.
System improvements included the erection of a steel superstructure
around the kinetic mixer, design and construction of an off-gas
collection system and fabrication of a containment enclosure.
The as-received LEX mixer was not equipped with any off gas collection
capability necessary for application to microencapsulation of
mixed waste. Thus, BNL designed and constructed an offgas system
to collect and contain vaporized gases and moisture. A schematic
diagram of the off gas system components is shown in Figure 2.4.
The process chamber was modified with two ventilation ports to
accommodate the off gas system. The outboard end of the mixer
was disassembled and the outer mixing chamber wall and end flange
removed. Two 0.5 inch (1.3 cm) vent ports were drilled through
the hard-facing on the mixing chamber wall and through the end
flange by the BNL machine shop. The ports originated near the
centerline of the mixing shaft. Off gases flow through steel mesh
filters to reduce carryover and are then plumbed to a jacketed
copper condensation coil that uses countercurrent flow-through
water cooling as a heat exchange medium. Condensed vapors are
collected in a 16.5 liter Lucite collection vessel. Off gas is
then drawn through a liquid nitrogen trap, prefilter, HEPA filter
and activated carbon bed. Vacuum is provided by a 41 ft3/min (116
l/min) vacuum pump. The system is fitted with three pressure gauges
to monitor potential pressure drops due to plugging or leaking.
Figure 2.5 is a photograph of the kinetic mixer off gas system.
The condensation coil, Lucite condensate collection vessel, and
rectangular HEPA filter box are clearly discernable
Please Contact Us to discuss your lucite fabrication needs. You design it, we build it.
lucite
fabrication
|

|