Removal of Sulfuric Acid Mist Emissions from Semiconductor Manufacturing Process with an Efficient Scrubber System

摘要

According to Taiwan EPA's regulation for the semiconductor manufacturing industry, the removal efficiency of control devices for the H2SO4 mist should be more than 95%, or the total H2SO4 mist emission rate per factory should be less than 0.1 kg/hr. The collection efficiency of fine mist is not high enough when a conventional packed tower is operated. Our previous study showed that many semiconductor manufacturing facilities cannot maintain the removal efficiencies or the emission rates within the regulation criteria using wet scrubber system because of small H2SO4 mist diameter. This study was targeted to enhance the performance of packed towers for removal of low-concentrations of H2SO4 mist from waste gases. The use of low-concentration surfactant in scrubbing liquid for packed bed combined with a modified demister was demonstrated to enhance the pollutant removal efficiency. The proposed surfactant system was installed in one pilot scrubber and the pilot tests were performed under the operating conditions adopted from most of the wet-scrubbers operated in semiconductors manufacturing facilities. The performance of the improved scrubber system was evaluated and compared with the original one. The results showed that use of the surfactant with scrubbing liquid in packed bed enhances the H2SO4 removal efficiency averaged from 45.7 % (n=10) to 80.2 % (n=8). Similarly, use of the surfactant with scrubbing liquid in packed bed and in demister simultaneously enhances the overall removal efficiency averaged from 45.7 % (n=10) to 85.5 % (n=12) for inlet average concentration of 8.25 mg/m~3. This study showed that the application of surfactant with scrubber system could be used as a H2SO4 mist collector, especially for acidic waste gas in semiconductor manufacturing industry.