Environmental Engineering Reference
In-Depth Information
absorber surface properties, reaction temperature, gas humidity, ratio of NO 2 to
SO 2 , and O 2 content can all affect the multi-pollutants removal performance.
These circumstances mean that this technology is not economic enough. Again, its
general removal efficiency is not high enough, with a desulfurization efficiency
usually reaching up to 80% and denitrification rate below 50% in lab-scale tests.
For a called ADVACATE deSO x and deNO x technology, Rochelle' group [79,80]
focused on the effects of different additives and reaction conditions on (i) the
removal efficiencies and (ii) interaction between SO 2 and NO x during the removal
process, followed by establishing fixed-bed chemical reaction models to predict
the deSO x and deNO x efficiencies. Sakai et al . [81] and Odowd et al . [82] also
reported a number of related studies in this subject. On the basis of an increase of
the specific surface area of a Ca-based sorbent, Jozewicz et al . [83] found that Hg 0 ,
SO 2 , and NO x removal efficiencies could be enhanced by adding an oxidant into
flue gas, thereby implementing successfully the collaborative removal of SO 2 ,
NO x , and Hg 0 .
Na/Al 2 O 3 adsorbent based multi-pollutants removal technology . The
adsorbent used here is a sodium salt loaded on Al 2 O 3 , which can be further
regenerated by CO, H 2 , and other reductive gas. A NO x SO technique belongs to
this subject, with removal efficiencies of above 90% and 70% reported in SO 2 and
NO x panels, respectively [84] .
NH 3 /V 2 O x -TiO 2 adsorbent based multi-pollutants removal technology . The
reactants of both desulfurization and denitrification are NH 3 . It regards V 2 O x ( x =
4 - 5), which is present on metal oxides such as TiO 2 , as the catalyst. For example,
Kasaoka et al . [85] employed this V 2 O x catalyst and NH 3 to conduct a series of
SO 2 /NO collaborative removal experiments at 130 °C in a fixed bed.
1.3.2.3 Free-Radical Based Multi-Pollutants Removal Technology
In this type, various high-energetic free radicals such as O, O 3 , OH, and HO 2 ,
which are generated by e-beam, pulsed-corona, and other plasma methods, are
used to oxidize efficiently NO and Hg 0 . Combined with a alkali absorption process
and wet electrostatic precipitator, these free radicals can be used to effectively
remove SO 2 , NO x , particles matter, heavy metals, and VOCs at the same time.
Meanwhile, high-energetic free radicals can also generate N radical, which can
reduce NO into N 2 . But unfortunately, the energy consumption of this type is
particularly high, since the triple bond N 2 is the most stable molecule in the flue
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