Page 269 - Wastewater Solids Incineration Systems

Incinerator Operations 231

2.8.4 Center Shaft Stoppage
If the center shaft stops and the remainder of the incinerator equipment continues to
operate, the operator should stop the feed. This prevents a large volume of cake from
building up on the top hearth. The operator should follow the procedure outlined in
section 2.8.1, Power Failure. However, the induced draft fan will continue to operate
for pressure control.

2.9 Multiple-Hearth Furnace Shutdown
The shutdown process for MHFs is basically the process of stopping feed to the incin-
erator. However, to avoid an immediate burnout the incinerator should remain in
operating mode until all of the cake in the incinerator is combusted. The burners and
rabble arms should remain in service with the air pollution control system until com-
bustion of the cake within the incinerator is complete. Depending on the characteris-
tics and quantity of cake within the incinerator, the incinerator can typically be
removed from service between one and two hours after the feed is stopped. Upon
shutdown of the incinerator the emergency bypass stack should be opened.

2.10 Typical Operator Duties

To ensure trouble-free operation of the MHF, the operator has a variety of duties that
must be performed. Following is a list of typical duties:

• Grease the center shaft bearings.
• Maintain the level of sand or steel shot in the upper and lower sand seals.

• Check the operation of the emergency bypass stack damper.
• Check the condition of the scraper tooth on the outer hearth rabble arm.
• Check the air filters for the combustion and center shaft cooling fans.

• Check and calibrate the total hydrocarbon and carbon monoxide monitors.
• Clean and calibrate the oxygen analyzer.
• Check for clinker formation and plugging of the drop holes.

• Check precooler and scrubber sprays and flow.
• Check operation of fans and drives.
• Coordinate with the solids dewatering system operators.