Page 308 - Air pollution and greenhouse gases from basic concepts to engineering applications for air emission control

10.2 Control of Particulate Matter Emissions 285

Clean reverse
air

Dust
laden
air

Filtering: dust Bag collapse: dust Bag inflation
cake buildup on cake break and
inner surface of falls down
the bags

Pulse Shaking
Dust jet bag
laden Dust
air
laden
air

Filtering: dust cake Pulsing: dust
buildup on outer cake break and Filtering: dust cake Shaking dust
surface of the bag falls down buildup on inner cake break and
surface of the bags falls down
Fig. 10.4 Three bag-house cleaning methods: reverse-air (top), pulse-jet (bottom left) and shake/
deflate (bottom right)

10.2.3 Wet Scrubbing

Wet scrubbers can be applied to control the emissions of both gaseous pollutants
and particulate matter. They remove air pollutants by inertial of diffusional
impaction, reaction with a sorbent or reagent slurry, or absorption into a liquid
solvent. These types of scrubbers can be used for the control of hazardous air
pollutants (HAP), inorganic fumes, vapors, and gases (e.g., chromic acid, hydrogen
sulfide, ammonia, chlorides, fluorides, and SO 2 ). They may also occasionally be
used to control volatile organic compounds (VOC).
Wet scrubbers are comparable to but not as effective as filters or ESPs for the
removal of sub-micron particles. However, wet scrubbers were noticeable when
certain gaseous components are to be removed simultaneously, or the particles are
too sticky or corrosive to be accepted by other alternatives.