Environmental Engineering Reference
In-Depth Information
CMA as a medium, SO 2 and NO could reduced by 70% - 80% and 50% - 80%,
respectively, at gas temperature levels of 1100 - 1200 °C within a 80 kWe
pulverized-coal boiler. Atal et al . [66] found that CMA not only removed SO 2 and
NO x but also strengthened the removal of HF, Hg and sub-particles.
The aforementioned investigations all employ a technique of Ca-based sorbent
injection combined with deNO x combustion conditions to achieve SO 2 and NO x
simultaneously. Major disadvantages of this technique are the medium removal
efficiencies and high operation cost of organic calcium. These in-furnace
multi-pollutants control technologies, which are efficient in small sized industrial
boilers, are hardly to be used in large-scale utility boilers because of the high cost
of the large organic calcium consumption and unavailability to meet the
increasingly stricter emission legislations.
1.3.2 Flue Gas Multi-Pollutants Emission Control Technology
Compared with the in-furnace combined multi-pollutants removal technology, the
flue gas multi-pollutants removal technology usually has a higher efficiency and
operation cost. Depicted in recent studies, the post-combustion flue-gas
multi-pollutants removal technology can be classified into the following
categories.
1.3.2.1 Multi-Pollutants Removal Technology Combined with SCR/SNCR
A combination of various types of sulfur removal technologies (including the
Ca-based adsorption, CuO/Al 2 O 3 oxidative adsorption, precious metal-catalyzed
oxidation, active carbon adsorption technologies, and etc), accompanied with
SCR/SNCR, can accomplish a good performance in deSO x and deNO x at the same
time. However, desulfurization and denitrification are independent with each other.
Usually the initial investment and running cost required are mostly high. Several
types in this aspect are introduced as below.
Ca-based adsorption combined with SCR/SNCR . Within a called
SO x -NO x -RO x -BO x (SNRB) technology that appearing in the 1990s [67,68] ,
desulfurization, denitrification, and high-temperature dust baghouse can follow a
free combination pattern and operate at temperature ranging from 300 - 500 °C. A
SNRB technology with annularity SCR catalyst placed in high-temperature
baghouse filters, which was developed by Babcock & Wilcox Company, could
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