Baking & Snack - April 2004 - 96

PROBLEM SOLVERS REPORT

Terminal
Velocity
Continental Mills settles its dust issues.

ust from flour, sugar, starch
and other dry bakery ingredients is a common nuisance that, if bad enough,
forces employees to wear dust filter
masks during ingredient unloading
or mixing operations. However, in
most bakery operations, once liquids are added to a mixer, dust is
minimized. Not so when the final
product is the dry blend itself.
For Continental Mills' Kent, WA,
dry mix facility, the dust issue was
compounded three times. This producer of Krusteaz-brand pancake and
muffin mixes has three major areas of
dust generation: indoor silos, supersack and bag unloading, and mixing.
"This 25-year-old plant wasn't
designed to mix the significant SKUs
of retail, food service and industrial
products we produce on a weekly

basis," said Chris Rodebaugh, plant
manager at the 150,000-sq-ft production facility. "We had a number
of issues with the old dust collection
systems. First, each area had its own
individual collection and filtration
system. Second, the systems were
undersized for the mixers we are
currently using. Third, the systems
used outdated technology."
In the mixing area, there was no
control or consideration of the various terminal velocities for each ingredient, according to Mr. Rodebaugh.
"Each ingredient has a particular
density as well as particle size that
combine to determine its terminal
velocity. This is further defined as the
point at which air velocity or vacuum
pressure will cause dust particles to
become airborne," he said.
Mr. Rodebaugh noted also that
vents on the indoor silos were undersized, and the filters rapidly clogged
with dust. At the combination supersack and bag unloading area, one
shared system made vacuum collection to either process inefficient.
UPGRADE, INTEGRATE. The plant
finally resolved to take action, according to Mr. Rodebaugh. "We
began looking at options to not only
upgrade but also integrate each of
the three dust collection areas into
a central collection system."
The company decided on a comprehensive solution that promised to
ᮤ Continental Mills relies on a "smart" dust
control system to compensate for constantly
changing airflows in its mixers.
CHRIS LEAVITT PHOTOGRAPHY

96 / BAKING & SNACK / April 2004

reduce airborne dust by as much as
80%, according to Mr. Rodebaugh.
Continental Mills chose equipment
and control software systems from
MAC Equipment, Sabetha, KS.
"In addition to its history of quality service and attention to detail,
MAC was the only supplier that
came in, analyzed our procedures
and took samples of each ingredient
- more that 20 materials in 23 silos.
It determined individual terminal
velocities in order to accurately
customize the solution to our ingredients and formulas, and it did not
try to force us to change procedures
to match a standard off-the-shelf
system," Mr. Rodebaugh said.
AUTOMATED CONTROL. While
there were several installation challenges to overcome, the plant ended
up with a solution that quickly
reached desired dust removal levels.
At the top of each indoor silo, vent
size was quadrupled to increase filtration area and minimize ingredient loss
through air displaced as the silos were
filled. One challenge for MAC was fitting the equipment onto the existing
silo bins because of very low overhead
clearance - less than 36 in. The supplier used its standard filtration components to design custom filter units
for the application. By doing this, replacement parts would remain standard. The filters actually extend into
the silos using the empty space created
by the ingredient material's angle of repose. MAC engineers then employed a
2-piece design to get the filters onto
each silo.
In the plant's bag dump area where
supersacks and multi-walled bags are
unloaded, MAC removed all the existing equipment and replaced it with
three separate unloading stations -
two for unloading supersacks and one
for hand-dumping ingredients. Using
equipment that directly couples the
supersacks to the process equipment
and some innovative dust control
design, MAC cleaned up this area that
for most plants is very messy.

Baking & Snack - April 2004

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