Development of Pollution Control Technology During Coal Combustion - Simultaneous Multi-Pollutants Removal in Flue Gas by Ozone - page 14

characteristics of the adsorbent, which means that the adsorbent must embody a
strong selective absorption capacity, large surface area, adequate mechanical
strength, as well as thermal and chemical stabilities. Considering that a large
surface area yields large adsorption capacity, activated carbon, activated carbon
fibers, and hydrophobic zeolite that are commonly used in industries, can be
applied to deal with organic compounds with a molecular weight 40 - 150 and low
boiling point. Although adsorption is a simple, recycling-effective, safe, and
reliable method to deal with VOCs, various problems such as a high flow
resistance during the adsorption process, high amount of adsorbent and high
equipment investment needed, and complicated operations of the absorbent bed,
necessitate to be resolved before industrial applications.
1.2.4.2 Catalytic Combustion Technology
Catalytic combustion is one of the most common organic-waste-gas control
methods [50] . This method, almost applied to all kinds of organic hydrocarbon
waste gas, embraces advantages summarized as follows. Firstly, the cost of the
auxiliary fuel required is greatly reduced because of the lower ignition
temperature (250 - 450 °C, compared with the 600 - 800 °C of direct combustion)
and energy consumption. Secondly, this method generates no secondary pollution
and combustion products (CO 2 and H 2 O) with purities above 95%. Moreover, the
NO x formation is largely reduced at the reduced combustion temperature levels.
Thirdly, the equipment size is less than one thermal incineration. However,
drawbacks of this method include the catalyst deactivation and limited flue gas
treatment.
1.2.4.3 Biological Control Technology
Organic matters are energies or nutrients of microbial survival produced through
microbial metabolism [51] , which can be eventually translated into simple inorganic
matters and cell components. Biological control technology has three forms,
namely, biological washing, filtration, and trickling deleted.
Biological control technology has several advantages, such as less secondary
pollution generated, simple equipment requirements, low investment, and low
operation cost. When handling low VOCs concentrations and good biodegradable
gas, this technology is even more promising in terms of economy [52] . However,