Environmental Engineering Reference
In-Depth Information
solution to absorb SO
2
and NO
x
and recycled sulfur to make the process easy. In
another application example, Fe(EDTA) or some other denitrification absorbents
such as sodium salts
[98]
was added into the wet desulfurization solution, so as to
enhance the NO
x
absorption.
Liquid-membrane method
. The US Department of Energy developed an
Fe(EDTA)-membrane method for simultaneous desulfurization and denitrification.
Accordingly, a series of investigations into the simultaneous removal of SO
2
and
NO
x
by the solution-membrane method were performed in Steven Institute of
Technology
[99]
. It was reported that in University of Calgary in Canada
[100]
,
flue-gas purification tests were conducted with polyethylene glycol and glycol
amine as immobilized liquid membranes. Researchers in Nagoya University in
Japan attended to investigate the removal of SO
2
and NO
x
in flue gas with the help
of Na or K carbonate, alkyl amines, and Na
2
SO
3
aqueous solutions
[101]
. The
absorption was based on the hydrophobic-microporous hollow-fiber membrane
module liquid membrane method.
Strong oxidant method
. As an effective co-removal approach for SO
2
and
NO
x
in flue gas, this technique type utilizes the strong oxidants (such as
NaClO
2
/HClO
3
, KMnO
4
/NaOH, P
4
, and others
[87-91]
) that can oxidize NO and Hg
0
into theirs oxidized forms. The oxidized species, namely NO
2
, HgCl
2
, HgO, and
etc are water-soluble to be easily removed in the WFGD process. However, these
strong oxidants are of weakness spontaneously, such as corrosive and
non-degradable, thereby irrefutably leading to a secondary pollution risk. As an
example in this technique type, the NO
x
SORB technology
[102]
developed in the
Argonne National Laboratory, uses HClO and NaClO to oxidize NO to NO
2
and
Hg
0
to Hg
2+
. Subsequently, SO
2
, NO
2
, and Hg
2+
can be successfully co-absorbed
in the alkali solution. However, both chlorate and hypochlorite are strongly
corrosive and un-degraded, which may have a secondary pollution risk.
References
[1]
Rubin ES, Hao Y. Engineering and Environment Introduction. Beijing: Science
Press, 2004.
[2]
China Statistical Yearbook 1978-2007. National Bureau of Statistics of China.
Beijing: Statistics Press, http://csp.stats.gov.cn.
[3]
Wang CH. Status of nitride oxide pollution and its treatment technology
development and standards. Machniery Industry Standardization & Quality,
Search WWH ::
Custom Search