Page 284 - Wastewater Solids Incineration Systems

246 Wastewater Solids Incineration Systems

3.4.2 High Incinerator Temperature
If the incinerator temperature rises above the set temperature, the bed temperature
supervision system stops the cake and auxiliary fuel feeds. Too much fuel (cake
solids and auxiliary fuel) and too little air are the primary causes of high incinerator
temperatures. The operator should monitor and adjust the cake feed rate, fluidizing
airflow rate, and auxiliary fuel rate before the incinerator bed temperature rises to the
set temperature.
If bed temperatures begin to rise the operator should increase the fluidizing air
rate. If the air rate is at a maximum, the operator should reduce the fuel rate. The aux-
iliary fuel feed is automatically controlled, but if the auxiliary fuel feed has not
responded to the temperature controller the operator should set the controller on
manual and adjust it manually. Adjustments to both the fluidizing airflow and auxil-
iary fuel rates typically take up to five minutes before a change is indicated on the
temperature recorder. The operator must wait before making additional adjustments.
Adjustment of the cake feed rate is more difficult. The dewatering equipment
that produces the cake must be adjusted. However, the effects of dewatering equip-
ment adjustment may take as long as 30 minutes to be visible. If the bed temperature
cannot be controlled by adjusting the fluidizing airflow or auxiliary fuel rates the
cake feed should be stopped. If the bed temperature supervision system (electrical
interlocks) does not stop the cake and auxiliary fuel feeds the operator must stop
these feeds immediately. This can be quickly accomplished by stopping the fluidizing
air blowers.

3.4.3 High Offgas Temperature
If the incinerator offgas or exhaust temperature rises above the set temperature, the
reactor freeboard temperature control system initiates water sprays and eventually
stops the cake and auxiliary fuel feed as the temperature rises. If the temperature
control system does not respond to increases in incinerator offgas temperature the
operator must immediately stop the cake and auxiliary fuel feeds.
3.4.4 Operating Problems
Table 10.3 provides a list of typical operating problems and possible solutions.

3.5 Typical Operator Duties
During normal fluid bed incinerator operations the operator must perform numerous
routine duties. These duties can be divided into categories based on frequency of
action. An important part of an operator’s duty is to record process information to