TM 5-815-1/AFR 19-6
6-7.
Cyclone operation
region must be maintained in order to eliminate a high
circulating dust load and resultant erosion. The cyclone
area most subject to erosion is opposite the gas inlet
impingement and rubbing of dust on the cyclone walls.
where large incoming dust particles are thrown against
Erosion becomes increasingly worse with high dust
the wall, and in the lower areas of the cone. Erosion in
loading, high inlet velocities, larger particle size, and
this area may be minimized by use of abrasion resistant
more abrasive dust particles. Any defect in cyclone
metal. Often provisions are made from removable lin-
design or operation which tends to concentrate dust
ings which are mounted flush with the inside surface of
moving at high velocity will accelerate erosion. The
the shell. Erosion resistant linings of troweled or cast
areas most subject to erosive wear are opposite the
refractory are also used. Dust particles below the 5 to
inlet, along lateral or longitudinal weld seams on the
10 micron range do not cause appreciable erosion
cyclone walls, near the cone bottom where gases
because they possess little mass and momentum. Ero-
reverse their axial flow, and at mis-matched flange
sion is accelerated at inlet velocities above approx-
seams on the inlet or dust outlet ducting. Surface irreg-
imately 75 ft/sec.
ularities at welded joints and the annealed softening of
b. Fouling. Decreased collection efficiency,
the adjacent metal at the weld will induce rapid wear.
increased erosion, and increased pressure drop result
The use of welded seams should be kept to a minimum
from fouling in cyclones. Fouling generally occurs
and heat treated to maintain metal hardness. Continu-
either by plugging of the dust outlet or by buildup of
ous and effective removal of dust in the dust outlet
6-13
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