Environmental Engineering Reference
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with increasing the NO 2 initial concentration. Increasing the molar ratio of O 3 /NO
enhances the NO x absorption removal. Especially, as the mole ratio reaches to 1.4,
the NO 2 removal efficiency jumps to 96%. Ozone oxidization effectively helps to
convert NO 2 into N 2 O 5 but is insensitive to SO 2 . Consequently, increasing the
ozone dosage advances greatly the NO x lye-absorption removal and barely impact
on the SO 2 removal efficiency.
(2) Adding reductive tetravalent-S components with a concentration below
0.01 mol/L greatly increases the NO 2 removal efficiency. The redox reactions of
NO 2 and tetravalent-S components are the dominant reactions related with NO 2 in
the liquid phase and generate a high NO 2 concentration. A high pH value
increases the SO 3 2 concentration and improves the NO 2 absorption rate. However,
the NO 2 removal efficiency is found to be around 70% under the typical liquid
phase conditions appearing in desulfurization towers.
(3) The existence of SO 2 weakens slightly the NO 2 removal. In comparison
with an atmosphere without SO 2 , the denitrification efficiency in the simulated
flue gas is reduced by only 3% when 500 ppm SO 2 is added. Accordingly, SO 2
also results in negligible effects on absorption products of NO 2 . The existence of
NO 2 also weakens a little the SO 2 removal. However, the NO 2 negative effect on
the SO 2 removal seems to be a little stronger. That is, the desulfurization
efficiency can be reduced by 4% when 300 ppm NO 2 is co-absorbed. The sulfate
produced in the solution uplifts owing to the oxidation of NO 2 .
(4) A simultaneous desulfurization and denitrification method incorporated
with ozone oxidization and dual-tower scrubbing and its setup thereof were put
forward previously. Here the schematic of the setup for a real-furnace flue gas
treatment and the introductory material about the technological process is repeated
in detail. Again, some important results in the published work is presented to
disclose (i) the factors that affecting that removal efficiencies, (ii) favorable
scrubbing solution conditions for recycling the byproducts, and (iii) measures to
improve the O 3 oxidization performance for a less O 3 dosage consumed.
References
[1]
Chameides WL. The photochemistry of a remote marine stratiform cloud. Journal
of Geophysical Research: Atmospheres, 1984(89):4739-4755.
[2]
Weast RC, Astle MJ, Beyer WH. CRC Handbook of Chemistry and Physics.
Cleveland: CRC Press, 1988.
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