Removal of Gas Pollutants of a Thermal Oxidizer with a Dynamic Scrubber

Abstract

The absorption of gas pollutants including CO 2 , CO, NO, NO 2 , SO 2 , and H 2 S from the exhaust of a paint recuperative oxidizer into NaOH solution has been studied using an industrial scale dynamic scrubber. Experimental results show the influence of the absorbent concentration on the pollutant removal efficiency. The best removal efficiencies of CO 2 , CO, NO, NO 2 , SO 2 , and H 2 S were 79, 80, 80, 100, 75 and 88 %, respectively, with 2 % NaOH as the absorbent. A comparison of these results with previous studies shows that the liquid-to-gas flow rate ratio (F L /F G ) in this dynamic scrubber is much smaller than for traditional NaOH scrubbers and spray dryers. IntroductionAir pollution has a widespread affect on the world. It threatens the health of human beings and other living things on our planet. Although often invisible, pollutants in the air create smog and acid rain, cause cancer or other serious health problems, diminish the protective ozone layer in the upper atmosphere, and contribute to the potential for world climate change.Nitrogen oxides (NO and NO 2 ) are produced largely by industry. Nitrogen oxides can also originate in the atmosphere by reactions which combine reactive oxygen containing molecules with nitrogen from the atmosphere [1]. Nitrogen oxides (NO x ) play a major role, together with volatile organic compounds (VOC), in the atmospheric reactions that produce ozone and acid rain, and may affect both terrestrial and aquatic ecosystems [2,3] 1) . They can also cause increased breathing difficulty for asthmatics. The US Environmental Protection Agency (EPA) uses NO x as one of the 'criteria pollutants' to indicate air quality [4].Carbon monoxide (CO) is a product of incomplete combustion. Its main sources are combustion processes involving vehicles, heating, coal-fired power generation, and biomass burning. It is emitted from the exhausts of motor vehicles and engines where there is incomplete combustion of fossil fuels [1]. Carbon monoxide (CO) interferes with the body's ability to carry oxygen, thus impairing perception and thought, slowing reflexes and causing drowsiness. Prolonged exposure to high levels of CO can cause unconsciousness and even death [5].Sulfur dioxide (SO 2 ) is produced by the burning of coal, vehicle emissions and emissions from oil/gas fields and refineries. Sulfur dioxide in high concentrations, with or without exercise, is a respiratory irritant, provoking airflow limitations. Ambient SO 2 may contribute to acid aerosol (H 2 SO 4 ) formation. In some studies, SO 2 , sulfates, and acid aerosols have been associated with increased emergency visits and hospitalizations for asthmatics [1,6].Hydrogen sulfide (H 2 S) is produced by many industrial processes, and by the decomposition of oil or dead vegetation. Clinical and research findings indicate that the nervous system is a target of H 2 S. At high concentrations, exposure can cause loss of consciousness or death. Breathing H 2 S at greater than 500,000 ppb can affect the brain's respiratory center, leading to...

Computational Fluid Dynamics Modeling for Urea Hydrolysis in a Batch Reactor for Flue Gas Conditioning

“…These power stations have always created environmental hazards like ozone depletion, acid rain, or air pollution. The combustion of coal in these power stations results in the production of large quantities of ash (fly ash and bottom ash) along with the release of NO x , SO 2 , CO 2 , and other harmful gases [1][2][3][4][5][6]. The fly ash particles, which are in suspension in the flue gas, contribute to an increased suspended particulate matter in the surrounding environment.…”