碩士 / 淡江大學 / 水資源及環境工程學系 / 92 / Nitrogen oxides refers to nitric oxide gas (NO) and nitrogen dioxide gas (NO2) and many other gaseous oxides containing nitrogen. Nitrogen oxides can travel long distances, causing a variety of health and environmental problems in locations far from their emissions source. The treatment and disposal of nitrogen oxides have become one of the most important issues in air pollution control. Various technologies have been developed for reducing nitrogen oxides emissions from combustion and production effluents. For the removal of nitrogen oxides, several dry and wet processes have been developed and discussed on the fundamental characteristics, but satisfactory achievement has not yet been obtained in every process. Recently, selective catalytic reduction (SCR) and selective non-catalytic reduction (SNCR) for NOx control have achieved commercial status for some applications. With respect to nitrogen oxides, several wet scrubbing processes have been developed and their technical systems have been established. Thus it is convenient to treat nitrogen oxides in the wet scrubber.
Nitric oxide is very low in solubility so it escapes the scrubber as part of the exhaust air. There are techniques for interfering with this reaction including oxidation and reduction chemicals. This study investigated the first staged by using sodium chlorite (NaClO2) to oxidize NO to NO2 under various operational parameters. The absorption of NO by an aqueous solution of alkaline NaClO2 was accomplished at room temperature and atmospheric pressure. This system is a promising wet scrubbing process for the removal of nitrogen oxides. With current pilot test result to combine with NO2 absorbing test,the study can be extend to perform a lower cost, higher NOx removal air pollution control technology for industry.The pilot experiment explores the influence of L/G ratio, NaClO2 concentration, pH value, gas retention time, gas velocity on NO conversion.The pilot experiment concluded the following findings:
1. The paractical range of 0.94 to 4.71 liquid to gas mass ratio (L/G) was studied. The data indicate that when L/G ratio is higher than 3.77, more than 90% of NO conversion is achieved.
2. The optimal range for scrubber parameters are 398.4 lbs/ft2-hr gas mass flow rate and 1500 lbs/ft2-hr liquid mass flow rate.If the gas mass flow rate is lower than optimal and the liquid mass flow rate is higher than optimal, the outlet NOx will only consist of NO2.
3. Within pH 4.5 to 6.5, the NO conversion is not very sensitive.
4. The gas retention time was varied from 1.5 to 6.2 seconds and the gas velocity was varied from 0.3 to 1.19 m/s. For NO oxidation, the 5.5 seconds of gas retention time or 0.45 m/s of gas velocity were found most of the NO is oxidized to NO2.
| Identifer | oai:union.ndltd.org:TW/092TKU00087013 |
| Date | January 2004 |
| Creators | WU HOU YU, 吳侯諭 |
| Contributors | Luke Chen, 陳俊成 |
| Source Sets | National Digital Library of Theses and Dissertations in Taiwan |
| Language | zh-TW |
| Detected Language | English |
| Type | 學位論文 ; thesis |
| Format | 95 |
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