Chemical Engineering June 2011 - 22

Sulzer Chemtech.
Newsfront
Column Internals:
the next BIg thIng
New technologies boost capacity and efficiency
of distillation trays and packings
W
hen it comes to distillation
trays and packing, chemical
processors require the same
criteria they seek from all
equipment in this tight economy -
technology that will reduce energy use
and boost throughput without costly
facility expansion. In an effort to meet
these needs, tray and packing specialists
are improving existing technologies
and launching a whole new generation
of trays designed to double
existing capacity.
" A main concern for processors is
the energy efficiency of their plants.
Because distillation represents a substantial
amount of the total energy
consumed, reducing energy use is a
key issue, " says Christoph Ender, vice
president sales for U.S. and Latin
America and the global marketing
and business development leader
with Koch-Glitsch, LP (Wichita, Kan.).
" This is also important from an environmental
point of view in that CO2
taxes are going to be applied in many
areas around the world, so any reduction
of fossil fuel consumption also reduces
the tax liability of the plant. "
Mark Pilling, manager of technology
with Sulzer Chemtech (Tulsa, Okla.),
agrees. " Our customers are very cost
conscious, so pressure drop is a big
driving force because it affects the energy
use and operating costs of system
components. Developing devices with
lower pressure drop is important because
distillation towers are massive,
so small savings in pressure drop can
result in millions of dollars saved over
the life of a project. "
In addition to reducing energy, today's
competitive environment has
processors on a quest to get more
capacity out of existing towers. " Increasing
throughput is a factor in
many industries where it is desired
to increase the economics of the plant
with minimal investment, " notes
Koch-Glitsch's Ender. He says this is
especially true in the U.S. and Western
Europe, which have to compete
with modern, large-scale plants in
the Middle East and Far East. " These
plants must stay competitive, so increased
throughput at minimal cost
plays an important role. "
Increased capacity is especially important
in the natural gas processing
industry and in petroleum refineries.
As the price of oil hits record highs,
the U.S. natural gas processing industry,
which provides a less expensive
and cleaner energy source, is currently
booming. " The U.S. natural gas industry
is investing heavily in new plants,
but many are also upgrading existing
plants, including investing in new distillation
technologies that can provide
cost-effective capacity increases, " says
Neil A. Sandford, tray product manager
with Koch-Glitsch.
U.S. petroleum refineries, too, find
themselves scrambling to add capacity
to existing facilities. " Refineries desperately
need more throughput from
their processes, " says Mike Resetarits,
technical director with Fractionation
Research, Inc. (FRI; Stillwater, Okla.),
a non-profit research consortium supported
by memberships, which include
the largest petroleum and petrochemical
companies in the world. " Environmental
regulations have forbid
the building of any new refineries in
the U.S. However, the population has
grown and everyone is still driving, so
the gasoline consumption in the U.S.
has doubled. This means refineries
have to squeeze more and more out
22 ChemiCal engineering www.Che.Com June 2011
Figure 1. This high-capacity, enhanced
structured packing offers new geometric
features that reduce the likelihood of premature
flooding at the interface
of the existing processes, so they desperately
seek new technologies to help
them do this. "
Improved packing designs
While the technology behind today's
trays and packings has been around
for quite a while, vendors are making
design changes that help processors
reduce energy consumption while increasing
throughput.
Sulzer Chemtech has been working
to optimize its structured packing designs.
What they have developed is a
device that can provide the same efficiency
at a lower pressure drop. " With
our new devices, we can save as much
as 40% on pressure drop across the
tower and, over the course of a lifetime
in a big plant, that can add up to millions
of dollars saved, " says Pilling.
Sulzer's MellapakPlus, touted as a
new generation of structured packing,
is a capacity-enhanced structured
packing that combines metal
sheet packing with new geometrical
features. The S-shaped design allows
vapor flow to smoothly change direction
at the interface between two packing
elements. At the interface, vapor
flow is nearly parallel to the vertical
axis of the column. The gas velocity is
therefore reduced by about 25% compared
to the velocity inside the packing
element. Both factors combine
to reduce the pressure drop and the
shear forces, which are especially critical
at the interface due to the presence
of thicker and less-stable liquid films.
As a result, premature flooding at the
interface is not a concern.
http://www.Che.Com
Chemical Engineering June 2011

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