Page 202 - Wastewater Solids Incineration Systems

Emission Control and Monitoring 169

FIGURE 7.15 A spray dry absorption system (I.D. induced draft).

further capture of acid gases. Spray dry absorption systems can be one or two stages
with single-stage systems being more common. Activated carbon slurry can also be
used in an SDA system for mercury control as discussed later in this section.

2.8.3 Operation and Maintenance
The primary maintenance requirement of a fabric filter is periodic replacement of the
bags. An important monitoring device is the pressure drop between inside and out-
side of the bags. A gradual increase in pressure drop indicates particulate buildup on
the outside of the bags and signals that the unit should go into a cleaning cycle. A
sudden drop in pressure most likely indicates a breach in the fabric on one or more
bags. A broken bag detector should be installed downstream of the bag filters to indi-
cate any increase in particulates escaping the bag filter. Alternatively, if the inciner-
ator has a particulate or opacity continuous emission monitoring system (CEMS),