Environmental Engineering Reference
In-Depth Information
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Torque control keeps tripping.
Causal factors:
Feed rate too high; feed solids concentration too
high; foreign material (e.g., tramp iron) in machine; misaligned gear
unit; gear unit mechanical problem
Corrective actions:
Reduce flows; dilute flows; remove conveyor
and clear foreign materials; correct gear unit alignment; repair
gear unit.
symptom 3.
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symptom 4.
Vibration is excessive.
Causal factors:
Improper lubrication; improper adjustment of vibra-
tion isolators; discharge funnels contacting centrifuge; plugged por-
tions of conveyor flights (causing an imbalance); improperly aligned
gear box; damaged pillow box bearings; bowl out of balance; parts
not tightly assembled; uneven wear on conveyor
Corrective actions:
Lubricate according to manufacturer's instruc-
tions; adjust isolators; reposition slip joints at funnels; flush cen-
trifuge; align gearbox; replace bearings; return rotating parts to
factory for rebalancing; tighten parts; resurface and rebalance.
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symptom 5.
Power consumption suddenly increases.
Causal factors:
Contact between bowl exterior and accumulated
solids in case; effluent pipe plugged
Corrective actions:
Apply hard surfacing to areas with wear;
clear solids discharge.
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symptom 6.
Power consumption gradually increases.
Causal factor:
Conveyor blade wear
Corrective action:
Replace blades.
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symptom 7.
Solids discharge is surging spasmodically.
Causal factors:
Pool depth too low; rough conveyor helix; feed pipe
too near drainage deck; excessive vibration
Corrective actions:
Increase pool depth; refinish conveyor blade
area; move feed pipe to effluent end (if applicable).
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symptom 8.
Centrifuge shuts down or will not start.
Causal factors:
Blown fuses; tripped overload relay; motor over-
heated/thermal protectors tripped; torque control tripped; vibra-
tion switch tripped
Corrective actions:
Replace fuses; flush centrifuge and reset
relay; flush centrifuge; reset thermal protectors.
10.7.5 sludge incineration
Not surprisingly, incinerators produce the maximum solids and
moisture reductions. The equipment required depends on whether the
unit is a multiple hearth or fluid-bed incinerator. Generally, the system
