| Summary: | 碩士 === 國立交通大學 === 工學院產業安全與防災學程 === 102 === Packed wet scrubbers are widely used to control the emission of acid and basic gases. However, these conventional scrubbers have poor removal efficiency for high-volumetric flow rate and low-concentration acid and basic gas pollutants, which can’t meet the emission standards promulgated by the Taiwan EPA. In order to improve the performance of existing wet scrubbers, a honeycomb plate-type scrubber was designed and tested to enhance the removal efficiency of these gas pollutants. In the present scrubber, tellerettes, typical tower packings, were replaced by a honeycomb multi-parallel-plate module. The parallel plates in the module were made of polypropylene coated with nano-TiO2 particles to enhance hydrophilicity for scrubbing liquid to form uniform water film. The honeycomb module with large specific surface area and high hydrophilicity significantly enhances the removal efficiency of the present scrubber.
The gas removal efficiency experiment was conducted by introducing inorganic acid gas pollutants in the exhaust gas stream from a wet scrubber in a semiconductor factory. Results show that when the gas flow rate of 1620 L/min (corresponding to the retention time of 0.5 sec ), the pH value of scrubbing liquid ranging from 9 to 10, the scrubbing liquid flow rate was 15 L/min and the liquid-to-gas ratio is 9.26 L/min3, the removal efficiency of acidic gases, HF, HCl, HNO2, HNO3 and H2SO4, are 93.4%, 91.3%, 91.0%, 90.2% and 93.3%, respectively. Results show that when the scrubbing liquid flow rate was increased from 15 to 30 L/min (corresponding to an increased in liquid-to-gas ratio from 9.26 to 18.52 L/min3), the removal efficiency for HF, HCl, HNO2, HNO3, and H2SO4 was found to increase by 1.25%, 2.53%, 5.63%, 5.88%, and 2.66%, to be 97.8%, 95.6%, 98.6%, 99.8%, and 98.0%, respectively. The removal efficiencies for these gases were also greater than 95%, which meet the emission standards for packed towers in the semiconductor factory.
The removal efficiency of the present scrubber for the waste gas containing both acid and basic gas pollutants in an optoelectronic factory was also shown to meet the emission regulation by increasing the gas retention time, scrubbing liquid flow rate, and liquid-to-gas ratio.
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