Page 284 - Air Pollution Control Engineering

05_chap_wang.qxd 05/05/2004 3:51 pm Page 263
Wet and Dry Scrubbing 263

Fig. 11. Concurrent absorption of sulfur dioxide using a selected packing material and
scrubbing solution. (Courtesy of Lantec Products Inc.)

CO + NaOH → NaHCO
2 3
NaHSO + NaOH → Na SO + H O
3 2 3 2
3. Important applications of a suitable, optimized packing material such as Q-PAC for
wet scrubbing are presented next. The high capacity of an optimized packing material
can be utilized in different ways. When designing new equipment, the cross-sectional
area of a scrubber can be reduced in order to reduce fabrication costs of the vessel and
capital expense of the recirculation pump. Additionally, even the cost of packing
required to fill the scrubber is reduced because less is needed to pack the scrubber. This
is a consequence of the fact that as the diameter of tower size is reduced, the volume
of the tower is reduced geometrically. The fan size need not be increased nor the oper-
ating costs of the scrubber system increased. Additional added benefits to reduced
tower size is a smaller footprint for the scrubber system as well as reduced noise during
normal operations of the system.

As an alternative, wet scrubbers can be sized for conventional gas velocities (375–475
fpm) but packed with an optimized packing material, such as Q-PAC, in order to
reduce the pressure drop for resultant reduced fan power consumption and, hence,
lower power costs for the lifetime of the system.
Retrofitting an existing scrubber with an optimized packing material makes it possi-
ble to increase the air being treated in the scrubber without changing the fan. In this