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CASTABLE CAN PROVIDE THE SAME ENERGY
PERFORMANCE AS A BOARD LINING.
Please see the following heat flow calculations and
comparisons to BNZ Materials' board system:
THERMAL PROFILE A
For the same thickness of castables vs boards, the
BNZ Materials' board system yields a cold face
temperature 32% lower (148 °F
vz 220°F)
and correspondingly 59% lower heat flow vs castables.
In addition, heat storage is reduced about 73%.
This results in quantifiable energy and cost savings
based on furnace dimensions and unit energy costs.
THERMAL PROFILE B
This heat flow calculation shows that an
additional 7+ inches of refractory construction are
needed with a two-component castable lining to
approach the same cold face and heat loss as with
boards. That is an 87% increase in wall thickness.
This increases structural costs and floor space
requirements.
THERMAL PROFILE C
A 13½ thick 3-component lining using 5½" of
Furnacon* 70 XR and 6" of Plicast* LWI 20 with 2" of K-FAC
19 comes closer in cold face temperature and heat loss
to the BNZ Materials board system, but it doesn't even
theoritically equal it.
This occurs even though the total refractory construction is 13½" vs the
BNZ boards 8" total! This is still a 68% increase
in wall thickness.
Conversely, if one were to build a castable furnace to
the same thermal specifications as a board linede
furnance, and keep the same outer dimensions, the a very
large reduction in working volume results.
THERMAL PROFILE D
Not until 4" of K-FAC 19 are used with 4" each of
Furnacon 70-XR/National and Plicast LWI 20 are cold face
temperatur and heat loss equal to the BNZ board system.
This is still a 50% increase in wall thickness.
CASTABLES ARE TOUGH AND CAN WITHSTAND AN AGGRESSIVE
CLEANING STYLE
Dense castables can take considerable abuse but are not
as tough as perceived. Our Marinite A calcium
silicate boards have better non-wetting characteristics
than castables. Since they resist oxide
penetration better to begin with, they require less
aggressive and less frequent cleaning.
In addition, the very nature of castables results in air holes on the hot
face, even with the best vibrations. These voids
are mechanical attachment sites where the aluminum
adheres and begins the cleaning degradation process.
Also, the additional toughness of a dense versus insulating castable is
what increases the thermal conductivity to high levels,
resulting in additional heat loss and wasted energy.
CASTABLES ARE SO EASY TO USE
This is incorrect because castables entail adding water,
mixing, placing and curing. These are the final
manufacturing steps and are subject to possible mistakes
and variation in the field. Marinite boards have
their manufacturing and quality control inspection
finished at the Billerica plant before exiting.
If mixing is too wet or too dry, the resulting castable will not cure to
the predicted strength or density. Also, castable
linings are difficult to cure and dry in the field, and
most visible problems develop in this process.
Cracks are the most common failure caused by drying too
fast or unevenly.
Low cement castables are difficult to place manually or via pumping, and,
if not careful, can develop porosity or create
artificial parting lines.
Since Marinite and ZelieBlok are finished products, they give excellent
consistency in density, dryness and structural
integrity, hence, they do not have any of the
aforementioned shortcomings of castabes.
In
addition, boards offer the following advantages:
Board-lined furnaces have no water added; therefore,
dry-out time is minimal and safety problems due to
entrapped steam are eliminated.
Board-lined can be pre-build in a modular fashion, dropped in place, and
fully installed in a short time (sometimes one day).
Baffles constructed using board can be replaced, unlike castable baffles.
Typical castable linings have much greater heat storage vs Marinite
linings, so furnace power requirements usually need to
be increased to hold the same temperature. |
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