Page 277 - Wastewater Solids Incineration Systems

Incinerator Operations 239

• Begin injecting fuel oil to the bed, if applicable, when the bed temperature
reaches 621°C (1150°F).
The fluidizing air blowers and induced draft fan, if installed, must be oper-
ating before fuel oil can be injected to the bed.
As the operator increases the rate of fuel oil firing, the operator should
decrease the rate of preheat burner firing.
• Start the feed cake when the bed temperature is higher than 649°C (1200°F);
air pollution regulations may require a higher temperature before the operator
injects the feed cake.

• Gradually increase the feed cake rate to the operating rate.
• Adjust the airflow rate to maintain sufficient excess air, typically 4 to 10% O .
2
• Adjust the fuel firing rate to maintain a constant bed temperature.
If the feed cake is autogenous the operator should decrease the fuel firing rate.
If the feed cake is nonautogenous, the operator should increase the fuel
firing rate.
• Set all controllers to the automatic position when the operating feed cake rate
has been established and the incinerator operation has stabilized.
Once these steps are completed, the incinerator should be operating normally.

3.1.2 Standby
A fluid bed incinerator may be placed in hot or cold standby modes. During hot
standby, the incinerator is kept hot and is ready to accept feed cake. During cold
standby, the incinerator is kept at room temperature and must go through a cold
startup procedure before accepting feed cake.
Because the sand bed has a large heat capacity and thus retains heat well, the flu-
idized bed incinerator is well-suited for hot standby. Typically, the heat loss from the
incinerator is approximately 5 to 10°C (10 to 20°F) per hour. Fluid bed incinerators
may be placed in a hot standby mode if the incinerator is shutdown with no warning
and without interrupting the dewatering process. Alternatively, incinerator opera-
tions may be intermittent, such as in a facility where there are only two shifts per day,
five days per week.
To place a fluid bed incinerator in hot standby, the operator will

• Stop the cake feed to the incinerator.
• Heat the incinerator to 871°C (1600°F) using auxiliary fuel and a reduced flu-
idizing air rate.