Development of Pollution Control Technology During Coal Combustion - Simultaneous Multi-Pollutants Removal in Flue Gas by Ozone - page 13

injected into the furnace zone with gas temperature ranging from 800 - 900 °C
and into the flue gas passage, respectively. The ratio of absorbent to mercury
concentration is kept around 600 - 1600. The particulate mercury can be
successfully trapped by the ESP or fabric filter. Then, the oxidation process takes
place, which converts elementary mercury into oxidized mercury at 150 - 160 °C.
The oxidized mercury can be absorbed in the following wet scrubber. The bench-
and pilot-scale experimental results have confirmed that both the gaseous and
particulate mercury in flue gas could be eliminated by as high as 85% [47] . This
approved the potential to put into practice in the further demonstration and
industrial applications.
1.2.4 VOCs Control Technology
VOCs are organic liquids and solids that have vapor pressures greater than 70.91
Pa at room temperature and have boiling points below 260 °C in air. VOCs
emissions regarded as the second largest category of atmospheric pollutant
(following the dust pollutant) mainly come from chemical companies, waste
incinerations, and insignificant pollution sources including household combustion,
paintings and coatings, etc. VOCs control has attracted a lot of attention because
of its serious harm to human health. However, the existing control technologies
seem to be unsatisfied, specifically for the huge volume of flue gas with very low
VOCs concentration. Until now, cost-effective methods are still not being applied
in power plants.
VOCs control technology can be divided into two categories, namely, the
separation and transformation methods [48] . The former separates organic matters
from gas including condensation, absorption, adsorption, and membrane-
separation methods. The latter converts organic matters into harmless CO 2 and
H 2 O, including (i) thermal incineration and catalytic combustion methods and (ii)
biological, photochemical, and electrochemical degradation technologies. In
practice, impact factors such as characteristics of pollutant species, conditions of
production, and purification requirements should be considered.
1.2.4.1 Adsorption Method
The adsorption method is one of the most common methods for controlling
VOCs [49] . The adsorption efficiency is extremely attributed to the adsorption