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53
Into Thin Air
Allen L. Ray, ProcessBarron,
explores making material buildup problems
on preheater ID fans vanish.
I
n the early construction of preheater towers,
the induced draft (ID) fans most often used
were of a radial blade design. This type of
blade design is straight, extending from the
centreline of rotation to the tip of the rotor.
It is an age-old design that has self‑cleaning
characteristics, making it preferred in
dust‑laden, material buildup environments. The
major disadvantage of this design is that it is
inefficient to operate. In addition, the material
particles tend to impact on the front side of
the blade and, over time, a layering of buildup
occurs, causing imbalance when the buildup
sheds unevenly from the blades.
Starting in the late 90s with the realisation
that draft fans are one of the largest parasitic