Environmental Engineering Reference
In-Depth Information
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symptom 4.
Oxygen content of multiple hearth furnace stack gas
is too low.
Causal factors:
Increase in volatile solids or grease content of the
sludge; air feed rate too low
Corrective actions:
Increase air feed rate; decrease sludge feed
rate.
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symptom 5.
Multiple hearth furnace refractories are deteriorated.
Causal factor:
Rapid startup/shutdown of furnace
Corrective actions:
Repair furnace refractories; follow specified
startup/shutdown procedures.
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symptom 6.
Unusually high cooling effect is observed in the mul-
tiple hearth furnace.
Causal factor:
Air leak
Corrective action:
Locate and repair leak.
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The multiple hearth furnace has a short hearth life.
Causal factor:
Uneven firing
Corrective action:
Fire hearths equally on both sides.
symptom 7.
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symptom 8.
Center shaft shear pin in the multiple hearth furnace
has failed.
Causal factors:
Rabble arm dragging on hearth; debris caught
under the arm
Corrective actions:
Adjust rabble arm to eliminate rubbing;
remove debris.
•
symptom 9.
Scrubber temperature in the multiple hearth furnace
is too high.
Causal factor:
Low water low to scrubber
Corrective action:
Adjust water flow to proper level.
•
symptom 10.
Stack gas temperature in the multiple hearth fur-
nace is too low.
Causal factors:
Inadequate fuel feed supply; excessive sludge feed
rate
Corrective actions:
Increase fuel feed rate; decrease sludge feed
rate.
•
symptom 11.
Stack gas temperature in the multiple hearth furnace
is too high.
Causal factors:
Increased volatile solids content (heat value) in
sludge; excessive fuel feed rate
Corrective actions:
Increase air feed rate; decrease sludge feed
rate; decrease fuel feed rate.
