Polymerization: Gas Phase Reactor Video Lecture | Chemical Technology - Chemical Engineering

you're not dreaming about rain right now
but these tiny crystals known as pellets
are the chief component in making a wide
array of plastic and is the end result
of polymerization you might be wondering
what is polymerization
well polymerization starts when a
catalyst meets with a basic molecule to
make longer more complex particles by
the breaking of double bonds and the
process of creating these repeating
structural units are known as
polymerization the origins of polymers
comes from reservoirs of oil and natural
gas being pumped piped and refined into
side products and byproducts this is
ultimately where feedstock comes from
which is the first step in polymerizing
plastics and the feedstock then goes
into a steam cracker where steam is used
to heat furnaces to break down the
feedstock into their base parts through
a maze of blazing-hot pipes is then
cooled into a dense liquid like gas
where it is then separated out into
ethylene propylene butadiene and crack
benzene it is then sent to their
assigned tanks where it awaits to be
used once it's determined what type of
plastic or polymer is going to be made
the monomer gas is preheated and ushered
into the molecular sieve where water and
other contaminants are filtered out by a
material called zeolites
the dry gas is now ready to interact
with the heart of the system and that's
the stirred gas reactor where
polymerization is continuously carried
out where propylene ethylene and
hydrogen are introduced to the reactor
solid catalyst is introduced to the
reactor to kick-start the formation of
polymers while this is happening a lot
of kete is created which is unfavorable
in polymer formation so this heat needs
to be dissipated the unreacted monomer
is recycled cooled and compressed and
then pumped back into the system to
regulate
richer and this ensures that the monomer
can be polymerized to specifications
once the polymer is made it is removed
from the reactor through dipping tubes
where the polymer goes through the
polymer gas separation process the
starts with carrier gas where steam and
additive are infused with the polymer to
deactivate the catalyst the product is
then filled into a discharge vessel
where unreacted monomer is recovered
when all the unreacted monomer is
extracted the polymer is then pumped out
and goes into the purge vessel very
single access door will mix nitrogen
which is pumped into the purge vessel
nitrogen helps stabilize the polymer and
removes any moisture and volatile
materials the nitrogen is also used to
to propel the powder to the powder silo
where awaits its last leg the extrusion
and mixing process this starts by
feeding the plastic material along with
water and additive through a hopper into
a barrel of the extruder the polymer
powder is gradually melted by the
mechanical energy generated by the
turning of the screw excess water and
off gas is removed via vacuum port and
the molten polymer is forced into a
underwater cutting die this is too cool
and shape the pellets the pellets are
then driven into a centripetal little
dryer where water is separated from the
pellets
are transferred to a series of mixing
silos for storage purposes while air is
integrated into the mix and silos to
recirculate the pellets to prevent
clumping and to facilitate the packing
of the final product and this is how
polymerization is done in a gas phase
reactor thank you so much for watching
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