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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