Chemical Engineering February 2014 - 22

Ajax Equipment
Chemineer
Newsfront
Mixing
in the
spotlight
In an attempt to increase
efficiency, chemical
processors consider new
mixing technologies
P
ressure to become more flexible
and provide shorter cycle times
have prompted chemical processors
to examine their mixing
operations to determine whether
there is a way to increase process efficiency
via mixing equipment. And,
they just might be onto something,
as modern mixing systems are designed
for particular process requirements
and mixing tasks, allowing
them to operate efficiently. The
greater efficiency allows increased
productivity for existing production
and enables processors to overcome
existing limits with respect to product
quality and quantity.
Here, experts weigh in on the various
types of mixing equipment and
how different technologies can provide
efficiency improvements in the
chemical manufacturing industry.
From batch to continuous
" In recent times, the inflexibility of
batch mixers has come to the fore
with their inherent interrupted process
path, risk of spoiled or off-specification
batches - not just waste
but delaying subsequent process
steps, equipment space and capacity
issues, " says Eddie McGee, technical
director with Ajax Equipment
(Bolton, U.K.; www.ajax.co.uk).
" This has resulted in a movement
Amixon
towards continuous
mixers, which
offer a smaller footprint,
a range of mix capacities
and capabilities
and the ability to monitor
and adjust to ensure product
mix quality in realtime. "
In chemical processing, especially,
continuous mixing offers significant
advantages over batch mixing, he
says. Continuous mixing handles a
range of products, from dry powder
and coating applications to wetting
applications, and even the potential
to mix pastes. The mixer body and
the screw shafts can be heated (or
cooled) as necessary, and additional
materials can be added later in the
mixing cycle to the already combined
materials. Two other benefits
of continuous mixers are the capability
for continuous output and
high processing flexibility. And, continuous
mixing works at a smaller
scale than batch mixing, giving a
greater degree of control over the
processing, and allowing continuous,
consistent production.
For this reason, Ajax Equipment
has recently introduced a new continuous
mixer (Figure 1) for the
chemical process industries (CPI).
The mixer's features include increased
range of processing capabil22
ChemiCal engineering www.Che.Com february 2014
Figure 1. (above left) The
continuous mixer from Ajax
Equipment features include an
increased range of processing
capability, rapid screw changeover
and enhanced shaft seals
Figure 2. (above right)
Chemineer's UltraTab static
mixer is suitable for turbulent
flow applications where a high
degree of mixing is required in
a compact space
Figure 3. (left) The vertical
cone mixer from Amixon is suitable
for mixing dry, moist and viscous
materials at variable filling levels
ity, rapid screw changeover
and enhanced shaft seals.
The continuous mixer is
available with both single- and
twin-screw arrangements. Chemical
powders are combined as they move
along the screws with either dry mix
or a combination of dry and wet.
Ajax offers a choice of screw augers
with ribbon flights or paddle flights
for difficult-to-mix materials. Fabricated
in stainless steel, the mixer
can have a polished, crack- and crevice-free
finish, if enhanced cleanability
is required. These mixers can be
easily cleaned between campaigns,
offering flexibility on process run
times and avoiding cross-contamination
on sensitive applications. The
screws can either be cleaned-in-place
or quickly released without disrupting
the drive-end motor.
Kevin Walsh, director of sales and
marketing at Chemineer (Dayton,
Ohio; www.chemineer.com), agrees
that many chemical processors are
moving away from batch mixing.
" Batch mixing is often done with rotating
agitators that are inventory
intensive because it requires large
vessels of product, " he says. " Also,
it's typically a higher energy-type
mixing process, so many companies,
http://www.chemineer.com http://www.ajax.co.uk http://www.Che.Com
Chemical Engineering February 2014

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